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If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - - - -Title: Glue, Gelatine, Animal Charcoal, Phosphorous, Cements, Pastes and Mucilages - -Author: F. Dawidowsky - -Editor: William T. Brannt - -Release Date: October 25, 2016 [EBook #53363] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK GLUE *** - - - - -Produced by deaurider, Les Galloway and the Online -Distributed Proofreading Team at http://www.pgdp.net - - - - - - - GLUE, GELATINE, ANIMAL CHARCOAL, - PHOSPHORUS, CEMENTS, PASTES, - AND MUCILAGES, - - COMPRISING - - THE RAW MATERIALS AND MANUFACTURE OF SKIN AND BONE GLUE, - DIFFERENT VARIETIES OF GLUE, ANIMAL CHARCOAL, PHOSPHORUS, - GELATINE AND PRODUCTS PREPARED FROM IT; ISINGLASS AND - FISH-GLUE, METHODS OF TESTING GLUE AND GELATINE, - AND THE PREPARATION AND APPLICATION OF - CEMENTS, PASTES AND MUCILAGES FOR USE - IN THE WORKSHOP, LABORATORY, - AND OFFICE. - - - BY - F. DAWIDOWSKY, - TECHNICAL CHEMIST. - - - EDITED FROM THE GERMAN, WITH EXTENSIVE ADDITIONS, INCLUDING - A DESCRIPTION OF THE MOST RECENT PROCESSES. - - BY - WILLIAM T. BRANNT, - EDITOR OF “THE TECHNO-CHEMICAL RECEIPT BOOK.” - - ILLUSTRATED BY FIFTY-NINE ENGRAVINGS. - - SECOND EDITION, REVISED AND LARGELY RE-WRITTEN. - - - PHILADELPHIA: - HENRY CAREY BAIRD & CO., - INDUSTRIAL PUBLISHERS, BOOKSELLERS AND IMPORTERS, - 810 WALNUT STREET. - 1905. - - - - - COPYRIGHT, BY - HENRY CAREY BAIRD & CO., - 1905. - - - PRINTED BY THE - WICKERSHAM PRINTING CO., - 53 and 55 North Queen Street, - LANCASTER, PA., U. S. A. - - - - -PREFACE TO THE SECOND EDITION. - - -The first edition of this work has been out of print for some years, -but nevertheless there is a constant demand for it, and this together -with the fact that frequent inquiries are received for information in -this department of industry, are the inducements which have led to the -preparation of the present treatise. - -The book is arranged in two parts, Part I. comprising Glue, Gelatine -and Allied Products, and Part II. Cements, Pastes and Mucilages, and it -is fully illustrated with engravings of various types of apparatus. - -Since the appearance of the first edition much progress has been made -in the manufacture of glue and allied products. Old and wasteful -methods of working have been replaced by more approved processes, and -in the present volume it has been endeavored to place before those -interested in these industries, a practical and comprehensive account -of modern methods of operation. - -In order adequately to represent this advancement and development, the -best authorities have been freely consulted and drawn upon, special -acknowledgments being due to the following works: “Bone Products and -Manures,” by Thomas Lambert, and “Glue and Glue Testing,” by Samuel -Rideal. - -As the demand for phosphorus is steadily increasing, and the -manufacture of this product from bones and bone-ash forms an important -branch of the utilization of bones, it has been deemed advisable to -devote a chapter to this subject. - -The receipts for cements, pastes, and mucilages given in Part II. -have been gathered from numerous sources. They have been critically -examined, and are offered, with the full conviction, that they will not -be found wanting in efficacy. - -The Table of Contents and Index have both been carefully prepared, and -being very full, will make reference to any subject in the volume easy -and satisfactory. - - W. T. B. - - PHILADELPHIA, PA., AUGUST 10, 1905. - - - - -CONTENTS. - - - PART I. - - GLUE AND GELATINE. - - - CHAPTER I. - - NATURE of GLUE. - - PAGE - - Sources of glue; Change in the animal tissues by continued boiling; - Definition of what is known as glue; Most important glue-yielding - substances 1 - - Transformations of which glue and gelatine are the products; - Transition stages of glue; Production of the glue-yielding substance - of the animal body 2 - - Crude glue and jelly; Constitution of glue; Combinations of which glue - consists 3 - - Preparation of pure glutin; Properties of glutin 4 - - Preparation and properties of chondrin 5 - - Adhesive power of glutin and of chondrin; Properties of glue and its - behavior towards other substances; Quantity of glutin in glue 6 - - Properties of jelly before drying to glue; Absorption of ozone by the - jelly; Behavior of glue solution towards different salts; Effect of - acids upon glue; Meta-gelatin 7 - - Combinations of tannin with the jelly; Effects of dry heat upon glue; - Chemical composition of glue and glue-yielding substance 8 - - - CHAPTER II. - - USES of GLUE. - - Glue as a joining medium, and requirements for this purpose 10 - - Glue as a binding agent; Consumption of glue in the manufacture of - matches 11 - - Quality of glue required by bookbinders; Glue in sizing; Glue for - culinary and medicinal purposes 12 - - Glue for clarifying and fining beer, wine and other liquids; Bouillon - tablets; Glue as a healing agent 13 - - Glue for elastic masses and a partial substitute for rubber; Use of - glue in photolithography; Hectograph mass; Glue for fancy articles 14 - - Gelatine veneers and their uses 15 - - - CHAPTER III. - - RAW MATERIALS AND THEIR PREPARATION FOR THE MANUFACTURE OF GLUE. - - Principal substances employed for the manufacture of glue; Division of - raw materials into groups 16 - - Animal skin and its constitution 17 - - Portion of the skin of value for the manufacture of leather and glue; - Yield of glue from tannery waste; Influence of the age of the animals - from which the skins have been derived upon the quality of the - glue 18 - - Notes in reference to judging glue-stock 19 - - Liming of waste 20 - - Precaution and care required when buying glue leather; Arrangements - required for the preparation of glue stock; Location of the glue - factory; Lime pits; Contrivances for washing the limed stock 21 - - Washing drums; Pits or vats with proper arrangements for stirring, - draining and inspection; Glue stock washer invented by W. A. - Hoeveller, described and illustrated 22 - - Sheds for storing and sorting; Mode of carrying on the work in the - factory; Liming; Preparation of milk of lime 26 - - Importance of the quality of the lime used; Testing the value of a - lime by determining the amount of real calcium hydroxide contained in - it; Mode of conducting the operation 27 - - Washing the material after removal from the lime pit; Washing and - drying 28 - - Preservation of the glue-stock by means of carbolic acid; Preparation - of carbolic acid solution for this purpose 29 - - Use of other antiseptics for the purpose of preventing putrefaction; - Formaldehyde and boric acid; Classification of the principal varieties - of hides and leather for glue-stock 30 - - Bones and cartilages 31 - - Constitution of bones; Composition of bone cartilage; Value of bones - for the manufacture of glue; Necessity of exercising care in buying - bones 32 - - Sorting the bones; Crushing or grinding the bones 33 - - Stamping mill for crushing bones, described and illustrated 34 - - Bone crusher, described and illustrated; Crosskill bone mill, - described and illustrated; Sieve for sorting the crushed bones, - described and illustrated 36 - - Lime bath for bones; Treatment of the bones with hydrochloric - acid 37 - - Washing the stock; Use of dilute sulphurous acid in place of - hydrochloric acid as suggested by Gerland; Jullion and Pirie’s process - for the preparation of gelatine from bones 38 - - Leather waste; Mechanical manipulation of the waste; Comminution of - the waste and use of a rag-engine or hollander for this - purpose 39 - - Various methods of extracting tannin from leather waste 40 - - Raw materials for fish glue; Difference between isinglass and glue - manufactured from entire fishes; Principal points to be observed in - the manufacture of fish glue 41 - - Utilization of scales of large fishes 42 - - - CHAPTER IV. - - MANUFACTURE OF SKIN GLUE. - - Classification of operations; Definition of crude glue; Derivation of - the bulk of this stock 43 - - Cooking or boiling glue-stock; Boiler for this purpose, and manner of - using it 44 - - Duration of boiling 45 - - Mode of ascertaining the progress of the operation; Convenient - apparatus for glue-boiling with water, described and - illustrated 46 - - Extracting the glue stock by the use of steam 47 - - Boiler for this purpose, described and illustrated; Use of - open-jacketed pans heated by steam, described and illustrated 49 - - Process of cooking as described by Mr. Thomas Lambert; Terne’s glue - boiler, described and illustrated 51 - - Clarifying the glue-liquor 52 - - Distinction between clearness and color; Clarifying vats; Prevention - of putrefaction of the liquor 53 - - Use of alum and other chemicals for clarifying; Freeing the liquor - from coloring substances 54 - - Use of animal charcoal for this purpose; Bleaching the raw materials - previous to boiling them to glue; Use of chloride of lime or of - sulphurous acid for this purpose 55 - - Forming or moulding the glue; Moulds for this purpose 56 - - Detaching the glue from the sides of the moulding boxes; Cutting the - cubes of glue into commercial cakes or sheets; On what the shape of - the cakes depends 57 - - Use of stone-slabs in place of cooling boxes; Use of glass or zinc - plates for liquors which in gelatinizing do not become very - solid 58 - - Tools for cutting the jelly into cakes, described and - illustrated 59 - - Machine for slicing and spreading glue-jelly preparatory to drying - invented by Mr. J. Schneible, described and illustrated 60 - - Cutting apparatus patented by M. Devoulx, described and - illustrated 62 - - Drying the cakes of glue; Drying in the open air; Mode of conducting - the operation in a drying room 64 - - Size of the drying room; Circulation and change of air in the drying - room 65 - - Nets and frames for drying the glue; Objections to twine - netting 66 - - Metallic netting and its advantages; Regulation of the temperature of - the drying room; Means of promoting the dryness of the air 67 - - Use of long drying galleries; Apparatus for drying glue, invented by - W. A. Hoeveller, described and illustrated 68 - - Modern drying house, described and illustrated 71 - - Method to accelerate the drying of glue, proposed by Fleck 72 - - Mode of giving the dry cakes a good lustrous appearance 73 - - - CHAPTER V. - - MANUFACTURE OF BONE GLUE. - - Comminution of the bones; Various methods of extracting the fat; - Boiling bones 74 - - Steaming bones and apparatus for this purpose 75 - - Extraction of bones with benzine or carbon disulphide; Apparatus for - the use of benzine invented by Messrs. Wm. Adamson and Charles F. A. - Simonis of Philadelphia, Pa., described and illustrated 76 - - Adamson’s method for treating substances with hydrocarbon vapor for - the purpose of extracting oils, fats, etc., described and - illustrated 79 - - Adamson’s method for treating substances with liquid hydrocarbon for - the purpose of extracting oils, fats, etc., described and - illustrated 82 - - Adamson’s process for removing hydrocarbons from substances which - have been treated therewith, described and illustrated 84 - - F. Seltsam’s apparatus, described and illustrated 86 - - F. Seltsam’s apparatus as improved by Th. Richter, described and - illustrated 88 - - Alfred Leuner’s apparatus, described and illustrated 90 - - Extraction with hydrochloric acid 91 - - Sulphurous acid process 92 - - Generation of sulphurous acid 93 - - Apparatus for the generation of sulphurous acid constructed by Dr. - Bruno Terne, described and illustrated; Conversion of cartilage into - glue; Wm. Friedberg’s apparatus for this purpose, described and - illustrated 94 - - Mode of operation with this apparatus 95 - - Construction of the filter used in connection with the - apparatus 96 - - Settling tank, described and illustrated; Arrangement of an open - evaporating pan, described and illustrated 98 - - Cooling the glue liquor; Use of refrigerating machines for that - purpose; Spiral evaporators 100 - - Vacuum pan for evaporating glue and gelatine liquors, described and - illustrated 101 - - Instrument which indicates the amount of dry glue in the solution, - described and illustrated 103 - - Process for the simultaneous utilization of bones for fat, bone-meal - and glue 104 - - Crushing the bones; Apparatus for subjecting the crushed bones to the - action of high-pressure steam, described and illustrated 105 - - Mode of operation with this apparatus 106 - - Duration of steaming the bones for the manufacture of animal - charcoal 107 - - Sorting the bones for the manufacture of animal charcoal; Former - method of carbonization 108 - - Arrangement of a Belgian retort-furnace, described and - illustrated 109 - - Products evolved in the destructive distillation of bones; Mode of - operation with Belgian retort-furnaces 112 - - Products obtained in making animal charcoal on a large scale; Process - for the simultaneous utilization of the bones for fat, glue and - calcium phosphate; Degreasing the bones 113 - - Treatment of the bones with hydrochloric acid; Preservation of the - resulting cartilage; Boiling the cartilage in open vessels 114 - - Mode of extracting the phosphates from bones; Yield of glue obtained - from cartilage after extraction of the mineral constituents; - Constituents of the liquor obtained by treating the bones 115 - - Utilization of the liquor in the manufacture of fertilizers 116 - - - CHAPTER VI. - - MANUFACTURE OF PHOSPHORUS. - - Operations included in the ordinary method of preparing phosphorus; - Burning the bones to ash; Kiln used for this purpose 117 - - Improved form of kiln proposed by Fleck; Mode of operation with a kiln - of this construction 118 - - Quantity of substance which remains after burning the bones; - Composition of bone ash; Conversion of the bone ash into a coarse - powder; Decomposition of the bone ash by sulphuric acid 119 - - Separate processes which have to be distinguished; Embodiment of these - processes in equations 120 - - Actual yield of phosphorus; Methods by which the formation of calcium - phosphate may be effected; Process without the assistance of - heat 121 - - Decomposition of the bone ash in the warm way 122 - - Apparatus for hot lixiviation 123 - - Evaporation of the liquor; Mixing the fluid with charcoal 124 - - Yield of so-called distilling mass; Utilization of the liquor obtained - in treating bones for the manufacture of glue with hydrochloric acid; - Concentration of the liquor for crystallization 125 - - Mode of obtaining the calcium phosphate contained in the - mother-liquor; Drying the crystals 126 - - Mixing the crystals with charcoal; Evaporating pans; Treatment of - the residue of basic calcium phosphate left in the manufacture of - phosphorus; Distillation of the phosphorus; Conversion of the acid - calcium phosphate into calcium metaphosphate and reduction of the - latter; Retorts and furnace for distilling the mixture of acid - calcium phosphate and charcoal; The galley-furnace 127 - - Modification of the galley-furnace, described and - illustrated 128 - - Furnaces for the use of coke as fuel; Receivers for collecting the - phosphorus distilling over 129 - - Process of distillation; Indication of the commencement of - distillation 130 - - Removing the phosphorus from the receivers; Regaining the phosphoric - acid contained in the water from the receivers; Constitution of crude - phosphorus 131 - - Refining and purifying the phosphorus; Various methods of - purification; Percentage of loss of phosphorus 132 - - Distillation of the crude product in order to obtain pure phosphorus; - Retorts and distilling apparatus for this purpose, described and - illustrated 133 - - Process of distillation; Different qualities of the phosphorus - passing over in the various stages of distillation; Separation of the - phosphorus passing over according to quality 134 - - Moulding the refined phosphorus; Seubert’s apparatus for this - purpose 135 - - Disadvantages of Seubert’s apparatus; Improved apparatus by which - the operation is rendered perfectly free from danger, described and - illustrated 136 - - Moulding the phosphorus in wedge-shaped sheet-metal boxes 137 - - Mode of storing and shipping phosphorus; Manufacture of phosphorus - with the assistance of electricity; Mixture used for the - operation 138 - - Furnace employed for the electrolytic manufacture of phosphorus, - described and illustrated 139 - - Mode of operating the furnace 140 - - - CHAPTER VII. - - METHODS OF BLEACHING GLUE. - - Bleaching in the air; Bleaching with chlorine 141 - - Bleaching with animal charcoal 142 - - Bleaching with sulphurous acid; Apparatus for the production of the - acid solution, described and illustrated 143 - - - CHAPTER VIII. - - DIFFERENT VARIETIES OF GLUE AND THEIR PREPARATION. - - Joiner’s glue; Material for the best variety of joiner’s glue 146 - - How to make and use glue; Holding power of glue 147 - - Cologne glue 148 - - Russian glue; Additions by means of which the color and opaqueness are - imparted to this variety of glue 149 - - Patent glue; Gilder’s glue; Superior article of gilder’s glue; Size - glue and parchment glue; Paris glue 150 - - Liquid glues; Receipts for liquid glues 151 - - Preparation of saccharate of lime; Steam-glue; Russian steam-glue; - Pale steam-glue; Dark steam-glue 152 - - Chrome glue; Glue for attaching leather to metal; Glue for leather, - paper, etc. 153 - - Glue for parchment paper in making sausage skins 154 - - Tungstic glue; Indestructible mass for the manufacture of ornaments, - toys, etc.; Compound for billiard balls 155 - - Coloring glue; Process for this purpose invented by G. J. Lesser 156 - - Composition for printing rollers; Size 157 - - Process used in an English factory for making tub-size 158 - - Preparation of bone-size; Composition of the different grades - of size 159 - - Concentrated size; Bookbinder’s size; Water-proof glue; Glue solution - for rendering wrapping paper water-proof 160 - - Water-proofing fabrics with glue and tannin 161 - - Muratori and Landry’s process of water-proofing fabrics 162 - - Muzmann and Krakowitzer’s process of water-proofing fabrics; Glue for - joints in leather driving belts; Hectograph mass 163 - - Formulas for hectograph masses 164 - - - CHAPTER IX. - - MANUFACTURE OF GELATINE, AND PRODUCTS PREPARED FROM IT. - - Properties of gelatine; Change in the chemical constitution of - gelatine produced by concentrated sulphuric or nitric acid; Tannin as - a test for the presence of gelatine; Use of gelatine for culinary and - medicinal purposes 165 - - Skin gelatine; Method of manufacture introduced and patented, in 1839, - by George Nelson; Process patented, in 1844, by Messrs. J. & G. - Cox of Edinburgh 166 - - G. P. Swinborn’s improved patented process for the preparation - of gelatine from hides, skins and glue pieces; Modern process of - preparing skin gelatine; “Steeping” the skins 167 - - Washing and bleaching the skins 168 - - Digesting the skins; Clarifying the liquors 169 - - Evaporation of the liquors in vacuo; Drying the cut cakes; Bone - gelatine; Materials for this purpose; Crushing the bones; Solution of - the glue cartilage 170 - - Apparatus and improved manner of manufacture employed in the factory - of D. J. Briers, described and illustrated 171 - - Modern process of preparing bone gelatine 179 - - Colored gelatine; Uses of colored gelatine; Harmless coloring matters; - Colors for coloring leaves of gelatine with aniline colors for - technical purposes 181 - - Gelatine for fining purposes; _Gelatine Lainée_; Fining powder for - wine and beer; Liquid fining gelatine; Preparation of gelatine from - ordinary glue 182 - - Preparation of gelatine for photographic printing and for photographic - purposes in general; Removal of the salts from the gelatine 183 - - Gelatine capsules for medicinal purposes; Court plaster 184 - - Gelatine foils; Mode of coloring the foils 185 - - Gelatine veneers; Principal operations in the manufacture of gelatine - veneers 186 - - Preparation of the plates; Preparation of the glue solutions; - Proportions by weight of the mixtures for ten different varieties of - imitations of marble and enamel 187 - - Imitation of mother-of-pearl veneers 188 - - Pouring the colored solutions of glue upon the plates 189 - - Preparation of imitations of malachite 190 - - Transferring the layer of glue to a layer of gelatine 191 - - Drying and detaching the veneers 192 - - Water-proofing gelatine veneers; Uses of gelatine veneers; - Formo-gelatine and its uses 193 - - Use of gelatine in bacteriology 194 - - Artificial silk from gelatine 195 - - - CHAPTER X. - - ISINGLASS AND ITS SUBSTITUTES. - - Sources of isinglass; Properties of a good quality of isinglass; - Imitations of isinglass and their detection; Adulteration of isinglass - and its detection 196 - - Russian isinglass; Siberian purse isinglass; Preparation of isinglass - in Russia 197 - - North American or New York isinglass 198 - - East India isinglass; Hudson Bay isinglass; Brazilian isinglass 199 - - German isinglass; Isinglass from the scales of shad and herring; - Bleaching inferior qualities of isinglass; Ichthycolle - Française 200 - - Isinglassine; Chinese isinglass 201 - - Irish moss; Fish glue; Jennings’ process for the preparation of fish - glue 203 - - Treatment of fish scales; Production of fish glue on the Norwegian - coast; Substitute for isinglass according to C. A. Sahlström’s - process 203 - - Whale glue 204 - - - CHAPTER XI. - - TESTING GLUE AND GELATINE. - - Determination of moisture; Determination of ash; Determination of - acidity 205 - - Determination of glutin; Bisler-Beumat’s method 206 - - Analysis of samples of American glue by S. Dana Hayes; Deduction of - the quality of glue from indirect properties 207 - - Lipowitz’s method of testing the strength of a glue, described and - illustrated 208 - - Results obtained by comparative experiments 209 - - Facts shown by the results 210 - - Weidenbusch’s method of testing glue 211 - - Preparation of the plaster of Paris stick and of the glue solution - used in this test 212 - - Apparatus for testing the strength of the plaster of Paris sticks, - described and illustrated; Test adopted by the “Artillerie Werkstätte” - at Spandau 213 - - Determination of adulterations 214 - - Kissling’s results in testing a large number of samples of glue 215 - - Practical tests of glue 216 - - - PART II. - - CEMENTS, PASTES, MUCILAGES. - - - CHAPTER XII. - - CLASSIFICATION OF CEMENTS. - - Stohmann’s division of cements and pastes; Groups of cements 218 - - Chemical nature of cements; Oil cements 219 - - Resinous cements; Definition of resins 220 - - Properties of resinous cements 221 - - Rubber and gutta-percha cements; Glue and starch cements 222 - - Lime cements 223 - - - CHAPTER XIII. - - PREPARATION OF CEMENTS, PASTES, AND MUCILAGES. - - Oil cements; Putty and its preparation 224 - - French putty; Soft putty; Litharge cement; Red lead cement; Cement - for wash basins 225 - - Zinc-white cement; Mastic cement, mastic or _pierres de mastic_ 226 - - French mastic; Paget’s mastic; Water-proof cement; Serbat’s - mastic 227 - - Stephen’s oil cement; Oil cement for glass; Oil cement free from lead - for steam pipes; Oil cements for steam pipes; Oil cement for - marble 228 - - Oil cement for porcelain; Diamond cement; Hager’s diamond cement; - Resinous cements; Resinous cement for amber; Cement for - turners 229 - - Cement for ivory and bone; Cement for white enameled clock faces; - Cements for glass; Cement for glass upon glass; Cement for glass upon - metal; Cement for metal letters upon glass; Cement for wood 230 - - Cement for knife handles; Cement for petroleum lamps; Cement for - porcelain; Cement for porcelain which is to be heated; Cement to - withstand the action of petroleum; Cement for mica 231 - - Cement for horn, whalebone and tortoise shell; Cement for terra cotta - articles; Mastic cement for glass; Stick mastic cement; Sulphur cement - for porcelain 232 - - Insoluble cement for wooden vessels; Rubber cements; Cements for glass; - Soft rubber cement 233 - - Hard rubber cement; Elastic cement; Marine glue 234 - - Jeffrey’s marine glue; Marine glue for damp walls; Gutta-percha - cements; Cement for leather 235 - - Cement for hard rubber combs; Elastic gutta-percha cement; Cement for - horses’ hoofs; Cement for crockery 236 - - Cement for leather; Caseine cements; Preparation of pure caseine 237 - - Preparation of ordinary technical caseine; John A. Just’s method for - obtaining a purer technical caseine 238 - - Caseine cement which can be kept for a long time; Cement for glass; - Cement for metals; Cement for porcelain; Cement for meerschaum; - Cement for wood, etc. 239 - - Cement for porcelain; Water-glass and water-glass cements; Water-glass - and its properties; Cement for cracked bottles 240 - - Cement for glass and porcelain; Cement for hydraulic works; Cement for - uniting metals; Cement for tightening joints of pipes exposed to a red - heat 241 - - Cement for marble and alabaster; Glycerine and glycerine cements; - Properties of commercial glycerine; Glycerine and litharge cement 242 - - Lime cements; Properties of lime and chalk; Cement for glass; Cement - for joiners; Cement for cracked clay crucibles and porcelain 243 - - Lime and glue cement; Gypsum cements; Preparation of plaster of Paris; - Cement for plaster of Paris statues 244 - - Cement for glass and porcelain; Cement for iron and stone; Cements - for porcelain; Universal plaster of Paris cement; Iron cements; - Heat-resisting cement; Water and steam-proof cement; Cement for - iron 245 - - Fire-proof cement for iron pipes; Cements resisting high temperatures; - Cement for filling in defects in castings; Cement for cracked - stove-plates, etc.; Cement for iron water-tanks; Cement for cracked - iron pots 246 - - Black cement for stoves; Cements for chemical apparatus; Requirements - of such cements; Cement for small apparatus to be used for the - development of fluoric acid 247 - - Linseed oil and clay cement; Linseed oil and manganese cement; Cements - resisting very high temperatures; Cement resisting acids; Rubber - cement for chemical apparatus 248 - - Scheibler’s cement for chemical apparatus; Cements for special purposes; - Cement for attaching metal letters to glass, marble, wood, etc.; Cement - for joints of iron pipes 249 - - Steam boiler cement; Cement for rubber; Cement for tires; Cement for - steam pipes, etc. 250 - - Cement for marble; Cement for attaching wood, glass, etc., to metal; - Brushmaker’s cement; Cement for electrical apparatus 251 - - Jeweler’s cement; American cement for jewelers; Cement for celluloid; - Stratena; Cement for cloth; How to use cements 252 - - Importance of bringing the cement into intimate contact with the - surface to be united 253 - - Obstacles to the junction of any two surfaces; Importance of using as - little cement as possible 254 - - Cleansing surfaces to be joined from grease and dirt; Paste and - mucilages; Starch paste 255 - - Rules for preparing paste; Flour paste 256 - - Means to prevent the spoiling of paste 257 - - Shoemakers’ paste 258 - - Gum arabic and its properties; Dextrine and its use in place of gum - arabic; Properties of commercial dextrine 259 - - Preparation of dextrine; Blumenthal’s method 260 - - Heuzé’s method; Tragacanth, or gum tragacanth; Pastes and mucilages - for special purposes; Starch paste; Flour paste 261 - - Strong adhesive paste; Paste that will not sour; Venetian paste 262 - - Label paste; Elastic or pliable paste; Mucilage for labels; - Mucilage 263 - - Mucilage for postage stamps; Caseine mucilage; Tragacanth mucilage; - Adhesive paste; Fluid pastes 264 - - Sugar and lime paste; Liquid sugar and lime paste; Pastes for paper and - fine fancy articles; Albumen paste 265 - - Glycerine paste; Paste for fixing labels on machines; Paste for - mounting maps; Paste for fastening paper on tin-foil; Paste for paper - bags; Caseine mucilage for photographer’s use; Paste for scrap - books 266 - - Paste for skins; Strong mucilage capable of fastening wood on china - and glass; Dextrine mucilage; Paste for joining leather to - pasteboard 267 - - Paste for attaching labels to polished nickel; Mucilage for attaching - labels to tin; Mucilage for office use; Glycerine paste for office - use; Clean and durable paste 268 - - Banknote or mouth glue; Paste for cardboard; Paste for attaching cloth - or leather to table tops; Caseine mucilage; Very adhesive paste which - may be used for wood and parchment 269 - - Paste for pads; Paste for fastening paper on tin-foil; Paste for - attaching labels to glass, porcelain and metal; Preparation of - arabol-gum; Preparation of an adhesive substance from desaccharized - beet-root slices 270 - - Index 273 - - - - -GLUE, GELATINE, CEMENTS, PASTES. - - - - -PART I. - -GLUE AND GELATINE. - - - - -CHAPTER I. - -NATURE OF GLUE. - - -1. SOURCES OF GLUE. - -The organisms of all animals, but more especially of the higher -classes, contain tissues which are insoluble in cold, as well as in -hot, water. However, by continued boiling they become dissolved, and -yield on evaporation of the solution a glutinous, gelatinizing mass. By -further drying this mass exhibits, according to the degree of purity -of the material, a more or less transparent and brittle substance, -which in its pure state is devoid of color as well as of smell; it -swells up in cold water and dissolves by boiling in that liquid. This -substance, _i. e._, the product of the conversion of the so-called glue -or gelatine-yielding tissue, is what is known in the trade as _glue_. - -Among the glue-yielding tissues, the following are the most important: -Cellular tissue, the corium, tendons or sinews, the middle membrane of -the vasa lymphatica and veins, the ossein or organic matter of bones, -hartshorn, cartilage, the air bladders of many kinds of fishes, etc. - -Neither glue nor gelatine exists ready formed in the animal organism, -except under abnormal conditions as a phenomenon of disease, but they -are the products of various transformations. The first of these -transformations evidently takes place in drying the hide, since the -result of boiling to glue a green hide prepared in the usual manner by -liming, etc., but not previously dried, will be an entirely different -product of less consistency than that obtained by drying the hide after -liming and then boiling. A second transformation seems to take place -in boiling the material, and a third in drying the jelly obtained, and -this may explain the fact that the latter, which is not converted into -actual glue, differs in its behavior from glue solution. The series -of transformation does not end even with the actual glue, for it is a -well-known fact that glue dissolved in water and boiled for some time -does not gelatinize on cooling, but remains liquid. We have here to -deal with organic combinations which are distinguished from the more -solid organic compounds by passing more readily into decomposition. -However, it is an established fact that glue is an organic combination -presenting itself in different modifications. In the animal organism -it occurs ready formed only under abnormal conditions as a phenomenon -of disease, and hence it is only produced by first drying and then -by continued boiling of the glue-yielding substance, and finally by -evaporating and further drying the gelatinous mass obtained by boiling. - - -2. TRANSITION STAGES OF GLUE. - -We therefore distinguish: - -_a._ Glue-yielding substance. - -_b._ Crude glue. - -_c._ Jelly. - -_d._ Glue. - -_a._ The glue-yielding substance of the animal body is produced from -proteïne substances, albumen, fibrine and caseïne, in a manner similar -to that in which new substances are formed in the ripening fruit by -the transformation and disintegration into constituent parts of others -previously present. - -_b._ By _crude glue_ are understood glue-yielding materials free from -all foreign matter and physically prepared by drying. It forms an -intermediate link between glue-yielding substance and jelly. - -This distinction between glue-yielding substance and crude glue is -justified by experience. If, for instance, fresh calves’ heads, such as -the tanner cuts off after swelling the skins, be carefully limed and -then boiled without previous drying, the result will be a turbid liquor -containing, though everything be dissolved, no jelly whatever, or at -least, very little. - -_c._ _Jelly_ is obtained by boiling the crude glue. Its adhesive power -is far less than that of solution of finished glue, and it will become -more quickly putrid than the latter. - -_d._ The finished product _glue_ is, in most cases, not a definite -chemical compound, but a mixture of substances, with two of which -scientific research has made us thoroughly acquainted. - - -3. CONSTITUTION OF GLUE. - -Independent of impurities and accidental constituents, glue consists -of two distinctly distinguishable combinations, namely, _glutin or -gelatin_ and _chondrin_, the former being formed from the hide and -osseous parts, and the latter from young bones while still in a soft -state, and the “permanent” cartilages, such as those of the ribs and -joints. - -The manufacturer has it, of course, in his power to allow either of -these substances to predominate in his product, but since experiments -have shown glutin or gelatin to possess much greater adhesive power -than chondrin, it is advisable to separate as much as possible the -cartilaginous matter from other glue-yielding material. - -As an accurate knowledge of these constituents of glue is of great -importance to the manufacturer, brief reference will here be made to -what scientific research has made known to us in regard to them. - -Pure glutin or gelatin is obtained by treating buckshorn, etc., with -water containing hydrochloric acid, until the phosphate of lime which -serves, so to say, as a frame for the glue-yielding substance, is -dissolved, and the organic tissue called _collagen_ or _ossein_, -remains behind. After freeing the latter from fat by steeping in milk -of lime and careful washing, it is boiled, and the resulting jelly, -when cold, mechanically distributed in cold water, in which it softens -but does not dissolve. By thoroughly stirring the mass the glutin -yields its coloring matter to the water, the latter being replaced -by fresh water until all the coloring matter is extracted. Then pour -off the water and after dissolving the jelly in hot water, filter the -solution through a cloth. By mixing the filtered solution with an -equal volume of alcohol, a precipitate of pure glutin is obtained. By -the precipitation with alcohol, the separating glutin carries down -inorganic salts, especially phosphates, which may be present in the -solution. To free it from them, dissolve it in a small quantity of -lukewarm water, acidulate the solution with hydrochloric acid and bring -it into a dialyser. The salts and the acids diffuse in the water which -has from time to time to be renewed, and finally a jelly of pure glutin -remains behind; this is evaporated to dryness in shallow vessels. - -Pure glutin, in a dry state forms a glassy substance, almost colorless, -transparent to translucent, brittle or slightly elastic, free from odor -and taste, and remains unchanged in the air. Its specific gravity is -greater than that of water. It is neutral, exerts no influence whatever -upon vegetable colors and is insoluble in alcohol, ether, hydrocarbons -or oils. In cold water it swells up, absorbing as much as 40 per cent., -and becomes opaque, but does not dissolve. It dissolves in hot water -and on cooling forms a jelly even if the solution contains only 1 per -cent. of glutin. It gelatinizes at a lower temperature than chondrin. - -An aqueous solution of glutin is precipitated by chlorine, platinic -chloride, tannin and alcohol, but not by hydrochloric acid, -acetic acid, lead acetate, alum and ferric sulphate. Concentrated -sulphuric acid decomposes glutin, forming, besides other products of -decomposition, chiefly glycocoll and leucine. - -When heated, glutin softens, swells and diffuses an odor of burnt -hartshorn. In the air, it takes fire with difficulty, smokes, flames -only for a few minutes, and leaves a bulky charcoal difficult to -incinerate, the ashes of which consist principally of calcium phosphate. - -Glutin, when in the jellied state, and treated with alcohol, undergoes -dehydration, under the influence of which it contracts greatly. It was -by this means that Gonnor succeeded in reducing in a remarkable degree -the size of a print obtained in a very hydrated film of glutin, and -transferring it, so reduced, to stone, from which he obtained a new -impression, quite similar to the first, but more or less diminished. - -By taking these prints, on the contrary, with glutin very little -hydrated, and afterwards steeping them in water, a dilatation of the -plate is obtained, which enlarges the figures with the same regularity. - -Pure _chondrin_ is prepared by boiling for from 24 to 48 hours the -cartilages of the ribs, of the larynx with the exception of those of -the epiglot, or of the windpipe and the bronchi. - -Chondrin is precipitated from its solution by alcohol. The precipitate -is redissolved in warm water, evaporated, and dried. It forms a -semi-translucent mass of a slightly yellow color and resembles glutin -as regards fracture and all external properties, but differs from it in -being precipitated from its aqueous solution by mineral acids, acetate -of lead, alum and ferric sulphate, and also by organic acids such as -vinegar, citric and oxalic acids, none of which precipitate glutin. - -As regards its chemical composition, chondrin is poorer in nitrogen -than glutin, and contains more sulphur. Its formula approaches more -closely that of albumen, which corresponds also with the origin of -chondrin, for cartilages may be considered as transition-links between -the proteïne and glue-yielding substances. - -By the action of concentrated sulphuric acid upon chondrin, leucine -is only produced but no glycocoll. By potassium hydrate chondrin is -converted into glutin and yields then, like the latter, leucine and -glycocoll. By boiling with concentrated hydrochloric acid chondrin is -decomposed; a peculiar variety of fermentable sugar, to which the term -chondroglucose has been applied, being formed. - -It may finally be remarked that chondrin possesses less adhesive power -than glutin and its presence in glue may be considered detrimental. To -avoid its formation, the glue manufacturer should separate as much as -possible cartilages from bones. Chondrin, however, is useful for size. - - -4. PROPERTIES OF GLUE AND ITS BEHAVIOR TOWARDS OTHER SUBSTANCES. - -The product designated by the general term glue, is always a mixture of -glutin, chondrin and other substances not yet accurately determined. -Glue is formed by evaporating and further drying the jelly, and its -properties depend on the crude glue and glue-yielding material used for -the production of the jelly. - -It may here be remarked that even if the quantity of glutin contained -in the different products could not be determined by scientific means, -the glue obtained from various materials can be readily distinguished -by external characteristics. Every manufacturer knows that hides and -bones yield a distinct quality of glue as regards adhesive power, -elasticity and fracture, and that the jelly from glue-yielding -substances of older animals is more solid and gives a larger yield than -that obtained from the tissues of younger and weaker animals. Glue from -the bladders and scales of fishes, though consisting mainly of glutin, -differs materially from hide or bone glue. - -Generally speaking, the jelly, no matter whether consisting of glutin -or chondrin, possesses, before drying to glue, different properties -from glue solution. It has less adhesive power and spoils more quickly. -At a temperature of 68° to 72.5° F., jelly putrefies inside of 24 -hours, smells of ammonia, and decomposes, while glue solution can be -kept much longer without suffering deterioration. - -The jelly absorbs ozone with avidity and is decomposed by it, this -being the reason why an approaching thunderstorm may cause great damage -by destroying the coagulating power of the glue liquors, or causing the -glue to turn on the nets, _i. e._, to lose its consistency and become -liquid and foul. - -The behavior of glue solution towards different salts also deserves -attention. - -By adding potassium or sodium carbonate, neutral potassium tartrate, -Rochelle or Epsom salts to a lukewarm fluid containing 15 to 20 per -cent. of glue, the latter coagulates by the salt withdrawing the water -from it. A lukewarm solution saturated with common salt, sal ammoniac, -saltpetre, or barium chloride does not gelatinize. - -By adding to glue solution a large quantity of alum, the glue is -precipitated as a transparent mass. - -Glue compounded at a high temperature with dilute acids, does not -gelatinize by itself, but will do so on adding common salt. - -Boiling with slaked lime deprives glue solution of its power of -gelatinizing, and, on evaporation, changes it into a colorless gummy -mass which is soluble in cold water and in saturated solution of common -salt. - -From a glutin solution compounded with oxalic acid, the latter can -after some time be again separated by the addition of lime, the result -being a non-gelatinizing fluid which, however, possesses great adhesive -power. This is the so-called _meta-gelatin_. - -Glue solution also loses its property of gelatinizing by repeated -boiling and cooling (for about six days). - -Tannin enters with the jelly, as well as with glue solution, into -characteristic combinations which are formed even in solutions -containing only 0.005 per cent. of jelly or glue. Glue is, therefore, -an excellent agent for the detection of tannin. - -When quite concentrated glue solution is treated with tannin, a heavy, -flocculent precipitate of a dirty-yellow, caseous character is formed, -which turns brown on exposure to the air and, after drying, constitutes -a hard brittle mass, easily reduced to powder and soluble in hot potash -lye, but insoluble in water, ether and alcohol. This precipitate, if -not identical with, is closely allied to the combination of tannin with -skin, called leather. - -Glue exposed to a dry heat melts, diffuses a strong disagreeable odor -of burned horn and leaves behind a charcoal which has a powerful -discoloring effect like animal charcoal. When subjected to destructive -distillation, glue yields an aqueous solution of ammonium carbonate -and a thick brown oil consisting of a mixture of ammonium carbonate, -sulphur, ammonium cyanide, etc. - -The chemical composition of glue is such as to bring to mind that of -starch and cellulose derived from the vegetable kingdom. It contains: - - Carbon 49.1 per cent. - Hydrogen 6.5 per cent. - Nitrogen 18.3 per cent. - Oxygen and sulphur 26.1 per cent. - -which may be represented by the formula: C_{12}H_{10}N_{2}O_{4}. - -The composition of glue differs but little from that of the -glue-yielding substance. Isinglass is composed of: - - Carbon 49.5 per cent. - Hydrogen 6.9 per cent. - Nitrogen 18.8 per cent. - Oxygen 24.8 per cent. - -This justifies the assumption that glue in its various transition -stages does not represent different chemical combinations, but only -modifications of one and the same combination distinguishable from each -other by physical characteristics, as is the case with starch, which -without suffering an alteration in its composition, appears as dextrine -and grape-sugar, or as with cellulose, which, without altering its -composition, can be transformed into amyloid and grape-sugar. - - - - -CHAPTER II. - -USES OF GLUE. - - -An inquiry into the various technical uses of glue must be of interest -to the manufacturer so as to enable him, when acting, as is frequently -the case, as salesman, to know to whom to offer his product; and also -to learn what special demands he has to satisfy, as not every glue -is adapted to every purpose, different qualities being required for -special uses. - -_Glue as a joining medium._ In Chapter I, treating of the nature of -glue, special attention has been drawn to the fact, that the adhesive -power of glutin is greater than that of chondrin; and that glutin -obtained from skin and tendons possesses still greater adhesive power -than the product from bones. This is the reason why good sound glue -made from scraps of skin is preferred by those artisans who may be -considered the principal consumers, such as cabinet-makers, carpenters, -turners, instrument-makers, wood-carvers, carriage-builders, -brush-manufacturers, bookbinders, paper-manufacturers, etc., all -of them requiring glue of the greatest possible adhesive power. It -must, however, by no means be understood that a good quality of bone -glue cannot be used for the same purposes; because much bone glue of -excellent quality and at a low price is brought into the market by -manufacturers of animal charcoal and bone meal, and is used in glueing -wood, etc. - -Glue suitable as a joining medium for the above purposes should be of -an amber or brown-yellow color, transparent or translucent, clear, dry -and hard, and show a glassy fracture which should not be brittle, but -somewhat elastic. Placed in cold water it should swell up and absorb -as much of it as possible without actually dissolving, even if it -remains there for 48 hours. The supernatant water should be free from -a putrid odor and contain but a small quantity of foreign substances -in solution. Such glue passes into solution at 122° F., and dissolves -entirely on heating to 144.5° F. Heating to a higher temperature should -be avoided. - -_Glue as a binding agent._ Glue solution is used for bind-together -pulverulent substances, such as mineral colors in the manufacture of -colored paper and paper-hangings, in painting in distemper, in the -size of the gilder; or it is mixed with plaster of Paris or chalk for -the manufacture of plastic masses which become hard on drying, such -as stucco-work, papier-maché, etc. Generally speaking, it is best to -use only good sound glue for these purposes, though it may sometimes -be possible to utilize defective and cheap qualities without injurious -consequences. For color mixtures, the glue should at all events be -free from acids and alkalies, as they exert a decomposing and altering -effect upon the colors. The gilder should always use the best quality -of glue, as otherwise the work he applies later on to the size will -spoil. - -A very large quantity of glue is consumed _in the manufacture of -matches_, and much depends on its quality and drying properties. The -dipping composition for matches containing phosphorus is a bath of -glue of 25 to 50 per cent. strength to which the requisite amount of -an oxidizing agent, like potassium nitrate or chlorate has been added, -kept at a temperature of 100.4° F. The phosphorus is cautiously put -in; it melts, and is stirred to an emulsion, when the sand, glass or -other friction-agent is incorporated. The object of the glue is to -protect from oxidation, without diminishing the sensitiveness. Glue is -also used as the binding material in the heads and rubbers of safety -matches. - -_Book binders_ require for the better classes of work a glue which -should naturally be pale and strong, and without marked odor. Some -inferior glues which have been chemically bleached turn almost black in -the pot, owing to the bleaching agent not having been properly removed -or neutralized. - -Sand, glass and emery papers and cloths are made by coating the surface -with a thin uniform layer of strong glue, and sifting the powder evenly -on. - -_Glue in sizing._ The principal object of sizing goods is to impart to -them a certain degree of stiffness, to give them a nice appearance and -a good feel. - -As glue would injure the color of white goods, it cannot be used for -sizing them, but, on the other hand, much is employed for preparing -size for the use of hat and cloth manufacturers, weavers, etc. Before -the introduction of the paper machine and invention of rosin glue, -animal glue was exclusively used for sizing paper, but at the present -it is only used for sizing paper manufactured from rags, and for -pasteboard, and also by manufacturers producing drawing paper sized -with animal substances. The paper, after leaving the machine, is passed -through a glue solution and then dried in the air. - -For actual sizing purposes good and fine varieties of glue are only -used, or sometimes the manufacturers prepare their own size by boiling -to glue dried calves’ heads, or rabbit skins deprived of their fur, -scraps of parchment, etc. For cheap woollen hats, glue is used in place -of shellac. The cloth manufacturer procures his glue mostly in the form -of a jelly. This variety of glue deserves special attention and the -mode of preparing it will be referred to later on. - -_Glue for culinary and medicinal purposes._ The use of glue for these -purposes is based upon three properties: - -1: Upon its power of coagulating and inclosing while in this state, -substances mechanically dissolved and finely divided in a fluid, which, -being specifically as heavy as the fluid itself, render the latter -turbid and cannot be got rid off by settling. The glue in this case -acts as a clarifier. - -Large quantities of isinglass and gelatine, specially prepared for -the purpose, are used for clarifying and fining beer, wine and other -liquids, as well as for preparing jellies. The material to be used for -jellies and other culinary purposes must, of course, be colorless and -entirely free from odor. Jellies are made palatable by flavoring with -spices, sugar, essences, etc., before congealing, A vegetable gelatine, -Agar-Agar, which will be referred to later on is now brought from -China, and being cheaper and perfectly free from odor, has become quite -a competitor with isinglass and gelatine. - -Prior to the introduction of Liebig’s and other beef extracts, bouillon -tablets, consisting of a mixture of bone-jelly, meat broth, extract -of pot herbs and flour, were largely used. One hundred and ten pounds -of meat repeatedly boiled yield five pounds of bouillon tablets. A -good meat broth, though not equal to that from Liebig’s or other meat -extracts, is obtained from these tablets by the addition of thirty -times their weight of water. - -If glue be dissolved in water, it gelatinizes at the ordinary -temperature, and if the solution be mixed with other fluids, for -instance, meat broth, fruit juices and essences, which in the form of -jelly are to serve as food, it effects their solidification. - -Glue acts as a healing agent by preventing the access of air to -wounds. Court plaster is prepared from gelatine. When cabinet-makers -cut themselves, they apply glue to the wound with the best success. -In hospitals a compound of gelatine and glycerine is used as the -best means of closing wounds, the same compound having also been -successfully used for preserving articles of food such as eggs, fruit, -and even meat. - -Every good quality of glue can be used for the above purposes. - -Medicines of a disagreeable taste are frequently inclosed in gelatine -capsules, so that they can be taken without causing inconvenience to -the patient. The use of these capsules has grown to such an extent as -to form a special branch of industry. The mode of manufacturing them -will be described later on. - -_Glue for elastic masses and as a partial substitute for rubber._ Glue -mixed with glycerine forms an elastic mass resembling rubber. The -same effect can be produced by an addition of molasses. This elastic -mass, the preparation of which will be described later on, is of great -importance for the manufacture of printers’ rollers, for moulds, etc. -Some manufacturers prepare the mass ready for use, so that the printer -or lithographer need only remelt it, and cast it in a mould. - -Glue is of great importance in photolithography as, mixed with chromium -salts, it is the only known means of transferring a photographic -negative to the stone. In photography, gelatine is used for negative -pictures upon glass. For the manufacturer of casts of plaster of Paris -or cement, this glue mass, which is generally used without an addition -of glycerine, is indispensable for making moulds which are much -undercut. - -Glue mixed with glycerine may be used as a substitute for rubber in -manufacturing elastic toys, such as dolls’ heads, animals, etc. For -these purposes it is advisable to select glue which forms a very solid -jelly, even if it possesses but little adhesive power, pure bone-glue -being the best. - -Glue mixed with glycerine (1 part glue, 1 part glycerine) is used as -hectograph mass for the transfer of matter written with concentrated -solution of aniline color. - -_Glue for fancy articles._ Great progress has been made in the use of -glue and gelatine in the manufacture of fancy articles. - -The best known of all these products are perhaps the gelatine foils. -They form thin, transparent sheets, brilliantly colored, and are used -for printing sacred images, visiting cards, labels, etc. - -Gelatine veneers were first shown at one of the Paris International -Exhibitions. They consist of sheets varying in thickness, which -have been deprived of their translucency by an admixture of colors -in imitation of various crystallization of salts, and such stones -as lazulite, malachite and avanturine. Glue imitations of mother of -pearl, tortoise shell, and ivory were shown which closely resembled the -genuine articles. These veneers have been largely introduced in the -manufacture of fancy articles, cabinet ware, buttons, etc. The most -brilliant use to which they have been put is in the manufacture of -fans, for which ivory and tortoise shell were formerly used, and there -are perhaps few ladies that are aware that these glittering toys are -manufactured from horse bones from the knacker’s yard. - -The successful introduction of gelatine veneers was soon followed by a -substitute for horn in general, and combs, buttons, snuff-boxes, and -hundreds of other fancy articles have been manufactured from these -imitations. - -In the foregoing statement only some of the principal uses of glue have -been enumerated, and there can be no doubt that with an increase in the -knowledge of its nature and properties, a wide field is still open for -progress in this industry. - - - - -CHAPTER III. - -RAW MATERIALS AND THEIR PREPARATION FOR THE MANUFACTURE OF GLUE. - - -The raw materials used for the manufacture of glue consist of a variety -of animal offal. The principal substances employed are refuse from -tanyards, such as scraps of ox and other thick hides, the waste of the -workshops of leather dressers, morocco leather manufacturers, etc. The -tendons and intestines of many animals, rabbit and hare skins deprived -of their fur, cat and dog skins, scraps of parchment, waste of turners -and button makers, and offal from butcher shops and households, help to -swell the series of materials used for the manufacture of glue. - -The materials are collected and sold either directly to the glue -boiler, or to dealers making a specialty of glue stock. - -As a thorough knowledge of these waste products is of importance to -the manufacturer, this chapter will be devoted to their detailed -description, the success of the enterprise depending largely on -the selection of the raw materials and their careful sorting and -preparation. By bearing in mind the varied products—from the most -ordinary black glue to the colorless glassy gelatine for photographic -and culinary purposes—it will be understood that entirely different -raw materials have to be employed for the finer products than for the -ordinary qualities of glue. - -According to their derivation the raw materials may be divided into -three groups, namely: - -1. Skin-like raw materials: Skin, leather, tissues. - -2. Bone raw materials. - -3. Materials obtained from fishes: Air bladders, scales, etc. - - -1. ANIMAL SKIN. - -[Illustration: FIG. 1.] - -This consists of three layers, namely: 1. The thin upper-skin—the -epidermis—which consists only of cellular tissue, and is of no special -importance for the manufacture of glue. 2. The actual leather-skin, or -corium, which consists of fibres of connective tissue and forms the -actual object of the tanner as well as of the glue boiler. Underneath -the corium lies the under-skin, which consists only of cellular tissue -contaminated with particles of flesh and fat, which are detrimental -to the manufacture of glue. Fig. 1 represents a section of the animal -skin. _O_, is the epidermis, _L_, the corium, _U_, the under-skin. The -epidermis consists of two layers. The first, superficial one, _H_, is -known as the cuticle or lamellar layer, and the other deeper layer, -_S_, as the mucous or malpighian layer. The corium also consists of -two layers, the upper one _C_, and the lower one _C_{1}_, which is -the actual leather-skin. The under-skin, _U_, is an elastic tissue -containing many deposits of fat, _F_, and perspiratory glands, _D_, -which are connected with ducts, _D_{1}_, with the surface of the skin. - -For the manufacturer of leather and glue, the corium is the only -material of value. - -The tanner trims the skins before steeping them in the ooze. From sheep -and calf skins he removes the head portions, it being more advantageous -to use them for glue stock. He also cuts off the skin covering the -lower part of the thighs, and, to give the skin a neat finish, the -ragged edges of the belly part. Of bullock hides, the ears, tails and -foot pieces are utilized for glue stock, while the head parts are -tanned. Such tannery waste may yield 44 to 46 per cent. of glue. Scarf -skin of bullocks’ hides and waste in fleshing the hide, tendons and -hinder parts of cattle yield from 30 to 35 per cent.; horse sinews from -15 to 18 per cent. - -Scraps of parchment and bullocks’ feet are highly valued as glue -stock, since they are in fit condition for boiling without further -preparation. They may yield up to 62 per cent. of their weight in glue. - -Calf and sheep skins yield a superior glue; that from horse hides is -usually dark and poor in quality, although with careful working a -strong product can be obtained from the latter. - -Of great value to the glue boiler are the so-called calves’ heads, -which, after liming and drying, form a special article of commerce. - -Skins of hogs, hares and rabbits yield a light-colored glue of little -consistency. It is, therefore, best to use these last-named raw -materials for the preparation of jelly, such as is used in sizing, in -the manufacture of paper, etc. - -The older the animals from which the skins have been derived, the more -solid the glue will be. In many cases, especially where a certain -quality of glue is to be produced, it may be recommended to separate -the different kinds of skin refuse into lots, provided there is enough -of each kind to boil it separately. - -A considerable number of skins used for packing various articles, such -as indigo from South Africa, have been so much damaged in transit as to -render them useless for tanning, but they form good material for glue, -frequently yielding 50 to 55 per cent. - -In reference to judging glue stock some valuable notes are given in -an article on glue, published by the American Provision Co., Chicago, -Ills.: - -“Dry, uncured or salted stock, such as raw hide or South American, if -soaked for twelve hours in cold water, gains about 50 per cent. in -weight, and still remains tough, and the water sweet. The moisture, -dirt, and salt should not be over 10 per cent. - -“Green salted stock, such as hide pieces, sinews, calf heads and pates, -should have no excess of salt, nor be foul, discolored or heated; -should be tough, with the hair not loose, and have a mild animal odor. -Moisture and salt not over 40 per cent. - -“Dry limed stock soaked twelve hours develops a characteristic odor, -and should be firm, fibrous, and have no slimy pieces. The water should -not be dark. Lime, sand and dirt, not over 5 per cent. - -“Green limed stock should be smooth and soft, any remaining hair being -easily detachable, while the liquor should be fairly clean, sweet, and -not too alkaline. - -“A large quantity of waste bones accumulates in the preparation of -tinned provisions. If these have not been overheated and are in good -condition, a considerable amount of glue can be obtained from them, the -bones of the head, ribs, and feet giving a better yield than those of -the thighs and legs. - -“Horn piths should not contain over 12 per cent. moisture, and should -not have been overheated in drying; they should have been cleansed from -skin and hair, which are of little value to the glue-maker. - -“The age of the animals yielding glue stock has an important influence -on the product. While from younger animals the product, as a rule, is -of lighter color, more abundant and more easily obtained, it contains -more chondrin, so that from solutions of equal strengths, those from -mature animals will be found to be of greater consistence and the glue -more solid. - -“Abroad, dry hides are often, for weighing, soaked in chlorbarium, a -solution of barium chloride, and then in a bath of dilute sulphuric -acid, 1½ per cent., which readily soaks in, combines with the barium -to form the white insoluble powder of barium sulphate, leaving weak -hydrochloric acid in the fibre, to be afterwards neutralized in -liming, the chloride of calcium dissolving out. This treatment affects -considerably the subsequent making of glue, as, beside the effects of -the acids, the sulphate of barium will render the liquors cloudy and -difficult to clarify. Of course if colored glues are to be made this -will be no detriment.” - -To prevent putrefaction, which is always accompanied by decomposition -of glue-yielding substance and consequent loss, the scraps must be -carefully preserved, especially in summer. - -The tanner prepares the waste by liming, _i. e._, steeping it during -fifteen to twenty days in milk of lime which is frequently renewed. -By the action of the lime, adhering particles of blood and flesh are -dissolved and the fatty matter is saponified. After this treatment the -glue-stock is dried. - -In case this work is not done carefully in the tanyard, as is only -too frequently the case, the stock is of but little value to the -glue-boiler. - -By allowing the refuse to lie too long in a heap, as is sometimes done, -putrid fermentation sets in, the injurious effects of which cannot be -remedied by subsequent liming, or the lime bath has not yet been strong -enough, or has not acted sufficiently long upon the scraps to destroy -the adhering particles of blood and flesh. The lime bath, on the other -hand, may have been too strong, so as to attack the glue-yielding -substance. Frequently it is also the case that the scraps having been -dried under unfavorable circumstances, mould has commenced to form, -and finally they may be spoiled in winter by allowing them to freeze. -Frozen glue leather yields glue of very little consistency. - -It will be seen from the foregoing that great precaution and care are -required when buying glue leather. The manufacturer should especially -see that it is dry and tough, free from mould and all organic and -inorganic substances, and not too strongly limed. - -The glue-boiler should, in all cases, be prepared to undertake the -preparation of the glue stock himself. The following arrangements are -required for the purpose: - -Let us assume that the glue factory is located on a stream of water. In -the immediate neighborhood of the stream a sufficient number of pits -to prepare all the glue stock used, each about 6½ feet deep and 6½ to -10 feet in diameter, and lined with cement, are so arranged that their -bottoms are about 3 to 3½ feet above the level of the water. They are -supplied with water by means of a pipe line connecting one with the -other. Each pit is provided with a discharge pipe to draw off the dirty -water. - -As the glue-stock, before undergoing other operations, has to be -freed from the lime by washing with water, the simplest plan is to -place the limed stock in nets or wicker baskets suspended in running -water by means of a traveling crane or other contrivance erected on -the bank of the stream. This elementary method, however, is open to -several disadvantages, as it fouls a large volume of water and may -lead to legal interference, and its very simplicity is apt to lead to -neglect of precautions, such as brushing away solid particles of lime -or softened animal matters. Further, the great quantities of water -carry off small pieces of glue-stock and fat, if catch-basins are not -provided sufficiently large to allow fat, glue-stock, hair and lime to -separate from the water. - -The object is better accomplished and in a shorter time by the use of a -washing drum. This consists of a perforated iron cylinder about 6 feet -in diameter and 4 feet in length, and open on both ends. Around the -inside of the cylinder are fixed a number of wooden shelves 6 inches -broad, which, as the cylinder revolves, carry the glue-stock partly -round, ultimately falling to the bottom again, the movement dashing -it about under a spray of water. In the cylinder is also arranged an -iron plate supported by stays from the outside. While the washing -is in operation the plate is turned perpendicular; on completion it -is brought to a horizontal position, forming a table, on which the -glue-stock falls, and the latter is then removed to a hand-press to -squeeze out the water. The washed stock is then removed to the drying -ground, which should be in a sunny and airy location, and provided with -an inclined floor of planks or cement so arranged as to allow of the -admittance of air from beneath. - -As it is well known that small quantities of liquid, frequently renewed -and thoroughly drained off each time, effect the most complete and -economical washing, and in the shortest time, S. Rideal recommends the -use of pits or vats with proper arrangements for stirring, draining and -inspection. The lime scum from the pits can be used in the manufacture -of fertilizers. - -The glue-stock washer shown in Figs. 2 to 5, is the invention of W. -A. Hoeveler (American patent), and it relates to the construction of -apparatus for washing glue-stock. - -In apparatus for this purpose the stock is very commonly damaged by -being broken up too much, and considerable loss results, besides, -from the fact that the small particles are allowed to escape with the -wash-water. By the present construction and arrangement these defects -are remedied and other advantages derived. - -Fig. 2 is a transverse vertical section on line x-x of Fig. 3 of this -apparatus; - -[Illustration: FIG. 2.] - -Fig. 3 is a longitudinal vertical section of the same; - -[Illustration: FIG. 3.] - -Fig. 4 is an enlarged plan illustrating the screen and hinged covers, -one being opened and one closed; and - -[Illustration: FIG. 4.] - -Fig. 5 is a detail of the hub, stems and part of one paddle. - -[Illustration: FIG. 5.] - -The apparatus is constructed in the form of a rectangular trough-like -structure, with its sides and ends, _A_, substantially water-tight by -means of the double walls, _a a_. The upper portion of the interior is -occupied by the swinging wash-box, _B_, semicircular in shape, with -flat sides and rounded bottom throughout, the bottom being perforated. - -Upon a transverse shaft, _c_, journaled at the axis of box, _B_, is set -a paddle-wheel composed of a suitable hub, _d_, and adjustable paddles, -each composed of the radial stem, _e_, and the blade, _f_, or spoon. -The spoons, _f_ are set on the stems, _e_, so as to be capable of being -reversed or turned half-way round, more or less. One side of the spoon, -_f_, is rounded off, so that while passing through the stock the latter -will not cling to or remain upon it. The other side of the spoon is -flat, but slightly skewed or bevelled, so that when turned to face -with the direction of motion of the wheel it not only gathers up the -stock and holds it till out of the box, _B_, but upon further elevation -causes it to roll or slide along the paddle to a predetermined point, -where it falls off gently into a discharge-spout, _g_, which carries it -off for further treatment practically undamaged. During the operation -the box, _B_, and the body, _A_, are kept supplied by a stream of clean -or chemically-prepared water, and the wheel, _e f_, revolves slowly -in the box, the edges of the paddles sweeping around, while the box, -_B_, or its bottom, is kept oscillating, thus preventing an injurious -clogging of the perforations in the box-bottom. After the stock is -placed in the box, _B_, and the latter filled with sufficient water, -the wheel, _e f_, is caused to slowly revolve (by motive or hand -power), with the rounded sides of the spoons, _f_, presented forward. -This operation thoroughly agitates and cleanses the stock, while the -rounded form of the spoons prevents the breaking up of the natural -condition of the stock. The inventor gathers the finer particles as -follows, after they have escaped through the perforated bottom of -the wash-box, _B_. At the lower part of the trough, _A_, elevated on -crossbars or blocks, _h_, he places two parallel strips, _i_, and -between these, which are grooved to form ways, _k_, inside, is set a -long screen, _l_, placed on rollers, _m_, and movable thereby on the -rails or ways, _k_. To give movement to the screen, _l_, the inventor -attaches to its end a rod, _n_, which projects outwardly through the -walls, _a a_, by means of the packing-box, _p_, and cap or door, _q_, -which, when opened, allows the withdrawal of the screen, _l_, and -its burden. The shaking of the screen is accomplished by a suitable -motor applied to rod, _n_, and is kept going during the operation as -required. To the strips, _i_, which are placed at a little distance -from the side walls, _a_ (to leave a passage for the water and refuse -to go through), are hinged the two doors, _r_, which shut down upon -the rod, _s_, as a support, in which case nothing can fall upon the -screen, or which open up and rest against the sides, _a a_, in which -case the screen is exposed and the side passages closed by the doors, -_r_. During the initial or rough-washing stage the doors, _r_, are -kept closed, and the dirty water and refuse pass freely down the side -passages and out at a suitable opening at the bottom. After this stage -it becomes desirable to catch the particles which get detached from the -stock in box, _B_, and come through the perforations therein. Then open -up the doors, _r_, thus closing the side passages and compelling all -the water and small stock to go to the screen, _l_, which catches the -remaining stock. When sufficiently accumulated the screen may be drawn -out and the stock thereon removed. When the main body of stock in box, -_B_, has been cleansed, the paddles or spoons, _f_, are reversed, so as -to present their flat, skewed faces to the stock, and in revolving the -paddles now gently lift the stock and discharge it into the spout or -hopper, _g_. The washing and removal of the stock when washed are thus -accomplished without further manipulation than to reverse the paddles, -which obviously could be done by a reversing-gear on the motor, thereby -reversing the direction of movement of the paddle-wheel. - -Instead of the whole box _B_ being oscillated back and forth, its -bottom may be set on slides or rollers and oscillated, while the sides -remain stationary. - -In the drawings the box _B_ is shown as hung upon the shaft _c_ as a -centre; but as the provision of means of reciprocating or oscillating -the box or its bottom is within the skill of any machinist, it is not -necessary to describe any specific form. As the box with its contents -will be very heavy, the inventor prefers a special motor for it, which -may also be geared up to reciprocate the screen _l_. - -Instead of the door _q_, as located in Fig. 2, it can be located as at -_q’_, same figure. - -The entire plant must of course be arranged according to sanitary -regulations, especially as regards river pollution, etc. - -The sheds for sorting and storing the glue-stock should, if possible, -be in close proximity to the pits and washing drums, and be dry and -airy. In arranging his plant, the glue manufacturer must, in short, -exercise his ingenuity with a view to carrying on the business with -as little loss of material, and as much saving of time and labor as -possible. - -The work in a factory arranged in the above manner, is carried on as -follows: - -The raw materials brought by the dealer are weighed, and if in green -state, the customary percentage—generally 50 per cent.—taken off. To -facilitate future operations, and to enable the manufacturer to produce -different varieties of glue, the dry materials are sorted and stored in -different compartments of the store-shed. - -Green waste, _i. e._, such as has not been limed must be taken in hand -at once, as otherwise it would taint the air, be attacked by rats and -other animals, and suffer injurious alterations by decomposition. The -manner of operation is as follows: - -_Liming._ Prepare “milk of lime” by filling the pits, which are to -serve for the reception of the skin waste, with the required quantity -of water and dissolve in it 2 per cent. of calcium hydrate obtained by -slaking a good quality of quick lime. Stir thoroughly, and in order -that the water may become thoroughly saturated with the lime, let the -liquor stand for 8 or 10 days before placing the waste in it. The -liquor should stand about 9 inches deep over the waste in the pits. -The length of time the waste has to remain in the milk of lime varies -according to the material; calf skins requiring 15 to 20 days, sheep -skins 20 to 30 days, and heavy ox hides 30 to 40 days. The milk of lime -should be renewed once or twice a week, and thoroughly stirred. - -For the purpose of liming, the quality of the lime used is of the -utmost importance, the milk of lime being frequently quite valueless -by reason of having become carbonated or a bad quality of quick lime -having been originally employed. It should be borne in mind that only -the hydrate of lime which is present in solution in lime water is of -use, whereas in milk of lime so much carbonate and other impurities -may be present that the liquid, though thick, may be quite useless. -The value of a lime should always be tested by determining the amount -of real calcium hydroxide, Ca(OH)_{2}, contained in it. The operation -according to S. Rideal, is conducted as follows: Water free from -carbonic acid is first prepared by boiling distilled water for half an -hour in a strong, round-bottomed Bohemian or Jena flask. While steam -is still issuing, the flask is removed for an instant, closed by a -well-fitting greased cork or a rubber stopper, and allowed to cool. -When the temperature has somewhat fallen, the cooling may be cautiously -accelerated by dipping into a pail of warm water, then transferring to -the cold stream from a tap. The water may be preserved in the flask -or, preferably, a number of bottles with vase-lined stoppers should be -filled quite full and retained for use. - -From the sample of lime, well mixed, a small portion (about 0.25 -gramme) should be accurately and rapidly weighed, placed in a -wide-mouthed, stoppered bottle holding about 300 cubic centimeters, 250 -Cc. of the boiled water added, and then allowed to settle. The whole of -the calcium hydrate will now have dissolved. Fifty cubic centimeters -of the clear liquid should now be withdrawn by a pipette, transferred -to a flask, colored with an indicator—either phenol-phthalein, -methyl-orange, or litmus may be used—and its alkalinity determined by -running in decinormal hydrochloric or sulphuric acid from a burette -till the change of color occurs. Each cubic centimeter of the acid -corresponds to 0.0028 gramme of calcium oxide, or 0.0037 gramme of the -hydrate, Ca(OH)_{2}. The amount by calculation will give the percentage -of real lime present in the sample. It is well to notice that any soda -or potash present will equally neutralize the acid, and be returned -as lime, but as these are of almost equal efficiency their presence -in _small quantity_ has no disadvantage. For special work it will be -necessary to have a full analysis. As a rule the product made from -limestone, or “stone lime,” is the best article in commerce, and is -much more free from stones and clay than “gray lime” or “shell lime.” -The best stone lime contains sometimes only ½ per cent. of impurities, -and seldom more than 5 per cent., while inferior kinds of gray lime -may contain as much as 50 per cent., and would be of little use in -glue-making. - -After removal from the lime pit, the material is placed in willow -baskets or nets, and immersed in the stream to remove the greater -portion of the lime, which is generally effected in a few days. It -is still more effectively accomplished by placing the waste, after -soaking in the willow baskets, in the wash drums. After taking it from -the baskets or wash drums it is spread in the drying yard to drain and -dry, the desiccation being accelerated by turning it over with a fork -several times a day. While drying, the quick-lime is converted into -carbonate, the latter exerting no disturbing effect in the manufacture -of glue. When sufficiently dried, the material is ready for boiling, -and the crude glue thus obtained can be stored for any length of time, -until wanted for further manipulation. - -In summer it is scarcely possible to cleanse the raw material as -rapidly as it is brought to the factory, and to work it immediately -without putrefaction setting in, and for this reason it would -frequently be risky to purchase larger quantities of it, even if -offered at very favorable terms. During the colder season of the year, -drying of the cleansed raw material is such a slow operation, that -in order to prevent putrefaction, recourse would have to be had to -artificial heat. - -These drawbacks can, however, be overcome by the use of carbolic -acid, which possesses in a high degree the property of preventing -putrefaction. It is quite cheap, and as but a comparatively small -quantity of it is required, the additional cost need scarcely be taken -into consideration, since the value of glue-stock annually destroyed by -putrefaction is considerably greater than the expense for carbolic acid. - -The raw material is thoroughly cleansed, and while in a moist state -is gradually brought into a brick cistern or large vat, carbolic acid -solution being poured over each layer, so that, when the cistern or vat -is filled, it stands about an inch or two deep over the material. The -latter may be left in this state until wanted. - -The carbolic acid solution is prepared by dissolving 2 lbs. of carbolic -acid in 1000 quarts of water; the fluid thus obtained possessing a -slight odor of smoke. The washed glue-stock treated as above described -with carbolic acid remains absolutely unchanged, and when wanted needs -only be taken from the cistern and worked like fresh material. - -In plants having no running water at their disposal and depending -entirely on well water, and where the waste water has to be discharged -into rivers or creeks, water containing carbolic acid should be used -for all the washing operations, a fluid containing 1 to 2 parts of -carbolic acid in 10,000 parts of water being sufficient for this -purpose. Such an addition of carbolic acid prevents the wash-water from -becoming foul. - -Carbolic acid has the tendency of hardening the glue-stock and -imparting its odor to the glue, and among other antiseptics, -formaldehyde and boric acid have been recommended for the purpose of -preventing putrefaction for a reasonable time. Formaldehyde in weak -solution (1 part in 10,000 to 100,000 parts water) has been found -beneficial. In this small quantity it does not harden the stock nor -affect the subsequent boiling, as it is dissipated by the heat. Boric -acid and its preparations, notwithstanding their low antiseptic power, -are much in favor. A fluid containing 1 part boric acid in 200 parts -water will have to be used. - -The principal varieties of hides and leather for glue-stock may be -classed as follows: - -1. Bullock leather from old animals, highly limed, mixed with rump -pieces, also with horse leather, the latter being thin, of a dark color -and soft, and is of less value than bullock leather, because it yields -a dark glue. Fat leather is bullock’s leather from fat, stall-fed -cattle, and before use has to be freed from fat (by means of benzine). - -2. Pieces of hide from the lower parts of the limbs of cattle, not -limed and with the hair; they form excellent glue-stock, yielding a -very adhesive glue. - -3. Worn-out hinges from weavers’ looms, consisting of strongest -untanned bullock’s hide. When treated with lime they yield a very -strong glue, but are worked with difficulty. - -4. Whip leather. This is waste in the manufacture of whips, and -is derived from thick tawed bullock hide. It yields an excellent, -light-colored glue. - -5. Calf leather. Broad, thin, translucent strips, slightly limed, -yields glue of a very light color. - -6. Calves’ heads. The skin of calves’ heads, limed, without hair. They -constitute the best material for gelatine, and form a special article -of commerce. - -7. Calves’ feet. The skin from the last but one leg-joint which is cut -off from dry, unlimed, haired skins. It is the best material next to -calves’ heads. - -8. Knapsack leather. Old knapsacks of calf skin and waste in the -manufacture of new ones, tawed with the hair on with alum and common -salt. When suitably washed this yields good glue-stock. The alum and -common salt have to be completely removed by washing. The hair is no -detriment to the process of boiling, it serving as a filter for the -glue running off. To this class belong also all kinds of fur waste, -especially remnants of old fur coats (sheep skin coats), from which the -wool is removed and the skin used as glue-stock. All these materials -having been treated with alum and common salt have to be freed from -them by suitable manipulation. - -9. Hare and rabbit skins freed from their fur. They yield a -light-colored glue of little consistency. - -10. Cut rabbit skins. In depriving these skins of their fur, they are -cut by a machine into fine threads of even size. In France they are -worked into size for gilders’ use which is highly valued. - -11. Sheep and lamb leather (goat leather) limed, thin and very light, -yields but a small quantity of glue of little consistency. To this -class belongs the waste in the manufacture of kid gloves. Waste of -morocco and other varieties of similar leather, pressed into bales and -secured with wire, comes into commerce under the name of Levant leather. - -12. Waste obtained in paring kid leather and in the manufacture of -gloves. It constitutes a flocculent powder and yields very thin glue -liquor with slight adhesive power. Before boiling, the substances used -in tanning must be completely removed by washing. - -13. Surrons. These are untanned, unlimed skins of various wild animals -(antelopes, gazelles) which have been used for packing leaf tobacco and -various drugs. They form good glue stock. - - -2. BONES AND CARTILAGES. - -In addition to hides, bones are a material highly valued by the glue -boiler. Chemically speaking, the framework supporting the fleshy -tissues of the animal order, and which we call bones, is a combination -of phosphates of lime and magnesia, carbonate of lime, and alkaline -salts, united with fatty and cartilaginous matter. To the latter we -look for our yield of glue; to the fatty matter for the fat, and to the -phosphates for the basis of fertilizers. - -Bone cartilage is composed of carbon, hydrogen, oxygen and nitrogen, -the percentage composition being practically constant, whether the -cartilage be from an old or a young animal. The bones of the young -are, however, much richer in cartilage than those of the old. This is -reversed in the case of the inorganic or mineral matter, the old having -the greatest yield of phosphates. - -Then again, the fatty matters are more in evidence in full-grown -animals than in youth or age; also in the thigh and leg bones the -yield is higher than in the heads, ribs or shoulder blades, the latter -averaging 12 to 13 per cent., whilst the former runs 18 to 19 per -cent.[1] - -[1] Bone Products and Manures. By Thomas Lambert. London, 1901. - -Bones being less subject to putrefaction than skin-stock, they are -not brought into commerce in a prepared state. They are mainly bought -by contract from various dealers within easy access to the works. The -rates are generally fixed for a certain period, and cover all classes -of common bones, whether fresh butchers’ or a mixture with partly -boiled bones. Bones differ considerably in their value. A fresh bone -will yield the highest percentage of fat and glue. On the other hand, -partly boiled bones may contain only 6 per cent. fat with 30 per cent. -water. In buying bones the manufacturer should exercise great care, as -the dealer sometimes finds ways and means of including hoofs, horns, -iron, beefy matter, and even pieces of brick. Naturally they form -weight, but, excepting the horns, have no value. - -To separate the different classes of bone coming into the works, and -arrange them according to the amounts they would produce of fat and -glue, is no doubt a desirable object, but in practice it is seldom -carried out. However, if the manufacturer wishes to undertake this -tedious work, it is recommended to make the following distinctions: - -1. Bones of young animals, sheep, calves, dogs, cats, etc., being -readily disintegrated, are thrown into one pile, and also the light -bones of oxen, such as skull bones, shoulder bones, the vertebra of the -tail, etc. - -2. A second pile is made of the foot bones of goats, sheep and cattle, -provided they can be had, as is the case in the United States and -England, in sufficiently large quantities. - -3. Scraps and shavings from bucks’-horn from turners and button-makers. - -4. Thick bones of oxen, horses, etc., which must remain longer in the -lime-bath, together with waste of hard bones from turners. - -5. Where large quantities of bones are handled it is advisable to sort -out the bones of the upper thigh, as they can be more advantageously -used for the manufacture of piano-keys, handles for tooth-brushes, etc. -Hoofs, which are frequently found, should be thrown out, as they yield -no glue and can be utilized for other purposes. - -The further manipulation of the bones for the manufacture of glue -requires first of all their crushing or grinding in a stamper or mill. -By this crushing or grinding of the bones two objects are attained, -namely, they are more readily deprived of their fat and present more -points of attack to the corrosive agents to be used later on. The -crushed bones are put in a large boiler, and for a few hours subjected -to the action of steam. Leg bones, as well as horns, should not be -boiled, as they contain no fat, and would lose too much glue-yielding -substance. After boiling, the bones are placed in a lime vat for 8 to -14 days. The water used for boiling the first portion of bones may be -used for a second one. - -The extracted fat amounting to 4 or 5 per cent. of the quantity of -bones used, is taken off the surface of the cold liquor and the latter -may be utilized as a fertilizer, or fed to cattle. - -For crushing the bones, a stamping mill is generally used, it yielding, -when properly constructed, material for the manufacture of glue, as -well as granulated bones which form an excellent product for the -preparation of animal charcoal. - -Since animal charcoal in pieces of quite even size is now in -general demand, it is recommended to manipulate the bones in the -above-described manner, to sell the granules to the manufacturer of -animal charcoal, and use for boiling glue only the completely-crushed -portions and the porous bones which are not at all suitable for the -manufacture of animal charcoal. - -[Illustration: FIG. 6.] - -Fig. 6 shows a stamping mill very suitable for the crushing of bones, -the illustration showing the mill open on the left side and closed -on the right. It is furnished with 16 stamps, _D_, each stamp being -provided with a cast-iron shoe. The stamps are lifted by means of a cam -shaft in such a manner, that the height of fall of the outermost pairs -of stamps is least and that of those in the centre greatest. Between -the inner stamps is a sieve _H_ with meshes of sufficient size to allow -the largest pieces, which can be produced by granulation, to fall -through. - -Underneath the sieve is an Archimedean screw _K_ for carrying off the -pieces of bone passing through the sieve. - -[Illustration: FIG. 7.] - -[Illustration: FIG. 8.] - -The base of the stamping mill consists of iron plates so arranged -as to form steps, the plates lying towards the center of the mill -constituting the lowest steps. Every two stamps standing alongside one -another rest upon such a step. When the mill is set in motion, the -bones reaching the stamping trough from the right and left fall upon -the steps, and are crushed by the descending stamps. - -As a rule, the bones to be stamped are not brought directly into the -stamping trough, but are first passed through a crushing mill and -the coarser pieces thus obtained are subjected to the action of the -stamping mill. - -Figs. 7 and 8 show a well-constructed bone crusher. It consists -essentially of two cast-iron rollers _A_ and _B_, furnished with -case-hardened cutters. The bones are introduced through the hopper _B_, -and the rolls set in motion by means of cog-wheels _a_ and _b_. The -bearings of the roll _B_ run in a carriage which can be shifted by the -lever-construction _f i_. The object of this contrivance is to allow -of the roll _B_ giving way in case a harder material than bones, for -instance, a stone, passes between the rolls. - -[Illustration: FIG. 9.] - -The Crosskill bone mill, Fig. 9, as described by S. Rideal, is intended -to be driven by a strap from the fly wheel of a common portable -engine. It consists of a pair of strong rollers made of wrought-iron -with case-hardened cutters, and a revolving or oscillating riddle for -separation of the ground bones as they fall from the cutters; the whole -carried by a substantial cast-iron frame. The mill will grind from 6 to -16 hundred-weight per hour with a three to eight horse-power engine. - -For sorting the crushed bones into pieces of equal size, a sieve, Fig. -10, is used consisting of a drum constructed of narrow boards covered -with wire-netting of different degrees of fineness. The upper portion -_A_ of the drum consists of narrow-meshed net and through this falls -the fine meal which is conveyed by the Archimedean screw _F_ over the -frame _F G H_ into vessels serving for its reception. - -The lower section, _B_, of the drum is furnished with netting, the -meshes of which become gradually wider towards the lower end, and, -hence, the smallest particles of bone fall through the funnel, _D_, the -medium-sized ones through _E_, and the largest ones through _F_. Pieces -which cannot pass through _F_, leave the drum at _G_. - -In factories manufacturing glue as well as animal charcoal, the larger -pieces are steamed by themselves to obtain their fat, and then charred, -while the small pieces and the meal are utilized for glue. - -[Illustration: FIG. 10.] - -The lime-bath used for bones should be of the same strength as that -for skin-stock. After removal from the lime vat and washing, the bones -are put in a tank of stone or wood (brick pits should not be used) -containing cold hydrochloric acid of 70° Bé. or 1.05 specific gravity -(= 10.6 per cent. HCl) for thick bones, or half that strength for thin -bones, and are thus left to digest for 8 to 14 days, being frequently -stirred and fresh acid added. By the action of the acid the calcium -phosphate is dissolved and the bones become cartilaginous, flexible -and transparent. The phosphates can be precipitated by ammonia, or -the whole evaporated with charcoal or silica, and distilled to make -phosphorus. - -When sufficiently softened, the stock is washed in wicker baskets or a -washing drum to remove adhering acid. They are then placed for one day -in the lime liquor, again washed, and then either dried or stored away -for future use, or boiled at once to glue, while in a moist state. - -Leg bones, horns, and other soft bones which contain scarcely any fatty -matter are not steamed for the reason previously stated, but in all -other respects are treated like steamed bones. - -It is of the greatest importance that the bones should be thoroughly -freed from acid, since even the smallest quantity remaining behind -exerts an injurious effect upon the finished glue. It is therefore -recommended to test the water draining off, or the bones themselves, -with litmus. If the tincture turns red, it is a sure indication of the -presence of free acid, and the washing must be continued until the blue -color of the tincture remains constant. - -Gerland’s suggestion, to use dilute sulphurous acid in place of -hydrochloric acid for dissolving the phosphates of the bones, and -to evaporate the sulphurous acid by heating, whereby the phosphates -are precipitated in an insoluble state, has now been quite generally -introduced. - -For the preparation of gelatine from bones, Jullion and Pirie’s -process may be recommended. It requires a somewhat expensive plant, -but saves hydrochloric acid and time. The process consists essentially -in dissolving the phosphates of the bones in vacuum. A box of wood, -or better of granite, which can be closed air-tight, is required -for this purpose. The box is filled with bones, and acid of the -previously-mentioned strength poured over them. The box is then closed -and the air pumped out by water or steam power. The smallest cracks -and pores of the bones are thus freed from air, and the latter is -replaced by hydrochloric acid, which in this manner acts rapidly and is -completely exhausted. The remaining crude glue is then further worked -in the usual way. - -Bones honey-combed by putrefaction, exposure to the weather, or burial -in the ground are of little or no value to the glue-boiler, as nearly -all the glue-yielding substance has been destroyed; they should -therefore be thrown out in buying stock. The ammonia which is formed -when putrefaction sets in, colors the glue dark. - - -3. LEATHER WASTE. - -Leather tanned with a substance insoluble in water is not directly -suitable for manufacturing glue, but can be made so by a special -process, which, though somewhat tedious, nevertheless pays for the -trouble. - -In using such stock the manufacturer should make a distinction -between old and new leather. The principal materials of this kind, -large quantities of which contribute their quota to the glue-boiler’s -stock, are old shoes, straps, harness, etc., and further, waste from -shoemakers, trunk-makers, and in fact from the shops of all workers in -leather except those using alumed leather. - -Before boiling the leather waste to glue, the removal of all traces -of tannin becomes absolutely necessary, since the retention of the -smallest quantity prevents the animal tissue from dissolving in water. - -The various methods proposed for the preparation of the leather waste -differ either in the chemical solvent used, or in the mechanical -manipulation of the waste. - -The principal point in all methods is to comminute the waste as -uniformly as possible to facilitate the complete removal of the tannin. - -Various machines, some very complicated, have been proposed for the -comminution of the waste, but a rag engine or “hollander” such as is -used by paper-makers deserves preference for the purpose, as it not -only comminutes, washes and prepares the waste in a suitable manner for -the manufacture of glue, but the leather pulp when mixed with rags or -woody fibre gives a substitute for leather which is very tough and of -good appearance, and can be worked into many articles. - -After the preparation in the hollander and careful washing the waste is -treated, according to Stenhouse, under a pressure of two atmospheres in -a boiler with water to which is added 15 per cent. of the quantity of -waste to be treated at one time of slaked lime. - -By another method the extraction of the tannin is effected by boiling -the leather pulp with caustic soda of 1.025 specific gravity for from -six to twelve hours. After drawing off the water and pressing out, the -pulp is again boiled with caustic soda of the same concentration. The -next process is to carefully wash out the soda, which is best effected -in the hollander. - -By neutralizing the soda lye in the fluid drawn off after the first -boiling, it can be re-used for tanning or purposes for which tannin is -required. - -According to another method, the _modus operandi_ is as follows: - -Dissolve 1½ lbs. of oxalic acid in 3 gallons of water, pour the boiling -solution over 110 lbs. of waste, and keep the mixture in a water-bath -at a temperature of 176° to 212° F. This effects the solution of the -pulp. Then dilute the solution by adding gradually 4 gallons of water -until a uniform mass is formed. Now add 5 lbs. of lime slaked to a -thin paste, and mix the whole thoroughly. The mass becomes friable and -pulverulent. It is passed through a wire sieve and then exposed to the -air. In three to four weeks the tannin is entirely destroyed, which -is recognized by the mass assuming a lighter color. The lime is then -removed by washing with water and hydrochloric acid. If the tannin -has not been entirely destroyed by exposure to the air, add 1 lb. of -liquid ammonia and a like quantity of pyrolusite to every 110 lbs. of -leather substance when boiling it to glue. The oxygen yielded up by -the pyrolusite, which, in the presence of ammonia, exerts no injurious -effect upon the glue, destroys the last traces of tannin. Frequent -stirring with a shovel while the material is exposed to the air and -moderate heating, facilitates the destruction of the tannin. - - -4. RAW MATERIALS FOR FISH GLUE. - -The air-bladders or sounds of various fishes contain much glue-yielding -substance and on account of its purity, the product known as isinglass -obtained from them is preferably used for culinary and medicinal -purposes. The high price of the raw material excludes it from being -used by the glue-boiler, but as he manufactures substitutes for -isinglass, and should therefore have a thorough knowledge of the -article with which he has to compete, its manufacture will be included -in this treatise. Since, however, the work of the manufacturer is -finished with the preparation of the raw material, _i. e._, of the -air-bladders into crude glue, isinglass and its substitutes will be -referred to later on. - -There is a material difference between isinglass and glue manufactured -from entire fishes. The raw material is, of course, limited to certain -localities. The principal point to be observed in the manufacture of -fish-glue is the removal of the skin, which is effected by means of -dilute sulphuric acid. - -After removal of the last traces of acid, the fatty matter of the -fishes is saponified by a treatment with milk of lime frequently -renewed. After washing out the lime, the pulpy mass is placed in a -solution of sodium hyposulphite, alum, and common salt, where it -remains for a few days. The liquor is then drawn off and replaced by -a mixture of solution of alum, dilute sulphuric acid and nitric acid. -After macerating in this mixture for a few days, the mass is thoroughly -washed and boiled to glue, and the resulting product clarified with -sulphurous acid or alum solution. As will be seen, the entire process -is tedious, requires many chemicals, and besides the yield of glue, -which has no specially good qualities, is small. It is used as a -substitute for isinglass for clarifying liquids. The best proof that -the business is of but little importance is found in the fact that -no fish-glue has been exhibited at any of the late international -exhibitions. - -The scales of large fishes, such as carp, give more favorable results. -They are treated with hydrochloric acid in a similar manner to bones. -The scales do not dissolve entirely, a horny insoluble mass, giving -no glue, remaining behind after the solution of the glue-yielding -substance. - - - - -CHAPTER IV. - -MANUFACTURE OF SKIN GLUE. - - -The thorough preparation of the raw materials will materially -facilitate all succeeding operations, which may be classified as -follows: - -1. Boiling the glue. - -2. Clarifying the glue-liquor. - -3. Forming or moulding the glue. - -4. Drying the glue. - -However, before entering into the description of these operations, it -will be necessary to refer to an intermediate product, which has been -previously mentioned under the name of crude glue, and is prepared, for -instance, by tanners and manufacturers of parchment, but also forms in -some localities a special branch of industry. - -This crude glue is actually not glue, but a glue-yielding substance in -such a state of preparation that it can be directly used for the first -operation, namely, boiling. It consists of waste of skins and leather -of all kinds, completely cleansed, dried and limed, and in the case -of leather treated with agents for the extraction of the substances -used in the tanning. As will be readily understood, the operations -required for the preparation of this stock are virtually the same as -those described in the previous chapter for raw materials and need not -further be here referred to. - -The bulk of such stock is prepared by tawers and manufacturers of -parchment, though a considerable quantity of it is also derived from -waste in the manufacture of gloves. The product from the latter source -is also found in commerce under the French names _Colle franche_ or -_Brochette_. However, if such stock is used, it is best to again -immerse it in lime water, after which it should be thoroughly washed. - -The manufacture of glue from hide and leather waste differs materially -in many respects from that of bone glue, it being the more simple -process, as no other preliminary operations than the preparation of the -glue-stock are required. The first operation is - - -1. COOKING OR BOILING. - -For this operation any kind of boiler may be used, but the materials -should be supported on a perforated grid a little distance above the -bottom, so as to save them from risk of scorching. In the centre of -the grid stands a conical pipe 2 to 3¼ feet long, perforated like the -grid and communicating with the space between the grid and the bottom -of the boiler. The height of the boiler can be increased 1 to 1½ feet -by placing an annular piece upon the rim which is bent upwards for its -reception. - -The size of the boiler depends on the quantity of raw material to be -worked at one time. It is best to choose boilers holding from 110 to -440 lbs. of glue-stock, and to place two, four or more of such boilers -in one hearth. - -The manner of using such a boiler is very simple. Straw is placed upon -the false bottom in such a manner as to cover its entire surface, and -extend up the sides of the boiler at least as far as it is touched by -the flame. The object of the straw is to serve as a filter, and protect -the materials from injury by the flame. But for the production of -entirely pure gelatine or glue, straw cannot be used, as, by boiling, -it yields a yellow coloring matter, which passes into the glue. Barley -straw gives a less intense coloring matter than rye straw. - -In case straw cannot be used, the material is placed in a large bag, -previously thoroughly boiled, and suspended in the boiler so as not to -touch the sides. By this means scorching is prevented even if the fire -touches the bottom as well as the sides of the boiler. - -The boiler having been heaped with material so high as to overflow the -brim and fill the annular piece placed upon it, is filled with water -as far as touched by the fire. The fire may now be started. The hearth -in which the boiler is placed should, of course, be so constructed -that the gases are uniformly distributed and the water quickly brought -to the boiling-point. When the water commences to boil, bubbles of -steam ascend from the space beneath the grid and, passing through the -perforations of the conical pipe, penetrate the glue-stock. Thus the -first formation of glue takes place, and the stock begins to settle -down gradually as it goes into solution. The stock heaped up in the -annular piece also sinks down gradually, and being partly heated by the -hot vapors and thus prepared for solution, is finally submerged in the -boiling solution and becomes soon entirely dissolved. - -Waste of hide and horn piths are completely dissolved in five to seven -hours. No more water should be used than is absolutely required for -cooking the entire quantity of stock, because too much water renders -the solution too thin and gives a jelly of little consistency and -difficult to dry. Concentrating the glue solution by continued boiling -is bad practice, as it is detrimental to the resulting product by -reason of the glutin undergoing a gradual transformation. - -It is best to start with a slow fire to give the stock time to soften -and thus prepare it for solution. When somewhat softened, the mass is -brought to boiling and the latter kept up, gently and uniformly, until -solution is complete. Solution is promoted by careful stirring, but -care should be had not to disarrange the straw upon the grid and on the -sides of the boiler as this would interfere with proper filtration of -the glue solution. - -The duration of cooking depends on the nature of the raw materials. -Scraps of skin from young animals, antlers, sheep trotters, etc., -dissolve in three to four hours, while waste from ox and horse hides, -or bones from old animals, require six to eight hours. - -The progress of the operation is readily ascertained by pouring a -small sample of the gelatinous fluid in half an eggshell, and setting -it aside for a few minutes to cool. If a clear and consistent jelly -be obtained, boiling has been carried on to a sufficient extent, and -the liquid is drawn off. Any undissolved glue-stock remaining upon the -straw filter can be boiled by itself, and the resulting gelatinous -liquor utilized in the next boiling. - -It is evident that quick and uniform solution of the materials, which -enhances the quality of the glue, is promoted by comminuting the -glue-stock either by grinding, stamping, or mechanical means. - -The succeeding clarification of the glue is much facilitated by -removing while boiling the scum, consisting of fat, coagulated albumen, -lime-soap, accidental admixtures, and other impurities. Before drawing -off the gelatinous liquor it is advisable to withdraw the fire and -allow the contents of the boiler to rest for fifteen minutes. - -The residue remaining upon the straw filter consists of hair, -lime-soap, undissolved particles of hide and bones, lime, etc., and is -utilized, after repeated boiling, as fertilizer or for the manufacture -of gas. - -The mode of glue boiling above described is the oldest and at present -is only in use in small establishments. Fig. 11 represents a convenient -apparatus for the purpose. It consists of three boilers upon as many -different levels. The lower boiler, _b_, serves for the settling and -clarification of the glue. It communicates with the second boiler, _a_, -which contains the material to be acted on, by means of a pipe provided -with a stopcock, and is sufficiently heated by a small fire to keep -the glue liquid without allowing it to reach ebullition. The upper -boiler, _c_, which is heated by the waste heat of the chimney, serves -as an economical reservoir for hot water. The end of the discharge-pipe -of the settling boiler is provided with a filter of woven wire. As -the sides and bottom of the second boiler are lined with straw, which -acts as a preliminary filter, the glue runs off quite clear from the -settling boiler. - -When this mode of manufacture is adopted, two boilings can be made -per day, under favorable circumstances, so that, if the boiler has a -capacity of 220 lbs. of stock, which will yield from 110 to 132 lbs. -of dry glue, the daily fabrication will be about 220 lbs. of finished -product. - -[Illustration: FIG. 11.] - -In larger plants, the above described mode of extracting the glue-stock -with water has been superseded by the use of steam in a cylindrical -wrought-iron boiler, twice as high as wide, and capable of withstanding -a pressure of three atmospheres. The boiler is furnished with a -perforated false bottom underneath which terminates a steam pipe. It is -filled from above with previously softened glue-stock and the charging -hole hermetically closed. Steam is then gradually admitted and exerts -at once a dissolving influence upon the stock. A portion of the steam -condenses and forms with the dissolved glue-stock a concentrated jelly -which collects between the true and false bottoms. - -For the escape of air a cock is provided which is closed as soon as -steam commences to escape from it. - -[Illustration: FIG. 12.] - -The advantages of this process are obvious. A larger quantity of -glue-stock can be extracted than in the boiler previously described, -and there is no danger of injury by scorching and consequent damage to -the color of the glue. More highly concentrated solutions are obtained -in a shorter time, and the spoiling of the glue solution by too long -continued cooking is prevented by drawing off the solution as quickly -as formed. The escaping hot vapors may be utilized for drying the glue, -softening the raw material, etc., the entire quantity of heat being -thus utilized. A further great advantage of this method is that there -is less annoyance from badly-smelling vapors than when boiling is done -over an open fire. A number of such boilers can be arranged in one -room and supplied from a common steam boiler. - -Fig. 12 represents a boiler for extracting glue-stock with the use of -steam. It is provided with a lid, _D_, which is removed for charging -the boiler. The aperture, _E_, in front, serves for the removal of -the residue. Above the true bottom there is another false bottom, -perforated and movable, which can be covered with straw for preliminary -filtration. The steam reaches the glue-stock through a pipe which -passes through the actual and false bottoms, and is perforated above -the latter. The resulting jelly collects between the true and false -bottoms, where it is less exposed to the action of hot steam. The -escaping steam passes through the pipe, _F_, which is provided with a -stock-cock. The pressure in the boiler is indicated by the manometer, -_K_. After throwing the materials into the boiler they can be covered -with warm water, or, after the lid is closed, warm water is introduced -from a reservoir through a special pipe and distributed over the -material through a rose. - -The boiler stands upon a frame sufficiently high to allow of -conveniently placing a vessel under the pipe _G_, through which the -jelly is discharged. The vessel, when full, is conveyed to the settling -vat, or the arrangement may be such that the jelly is directly run into -the settling vat. - -In many large plants open jacketed pans heated by steam are still used -for treating the material. Fig. 13 shows an arrangement with two of -such pans; of course one, or a larger number may be used, according -to requirement. In the illustration the pan _I_ on the left is shown -in front view, and the pan _II_ on the right, in section. _K_{1}_ is -the actual pan enclosed by the jacket _K_. Steam circulates in the -space between pan and jacket, whereby the stock in the pan is heated. -_K_{1}_, in addition, is furnished with a steam coil _S_, which may, -however, be omitted. - -The steam enters through the pipe _D_, the space between pan and -jacket, passes into the coil _S_, and escapes at _b_. The water formed -by the condensation of steam in the space between pan and jacket, as -well as that which runs off at _b_ from the coil _S_, is carried away -by the pipe _A_. - -The pipe _L_ serves for conveying hot water to the pans, and the pipe -_F_ for the discharge of the finished glue liquor. The stirrer _R_, is -furnished with two paddles, and is set in motion by a transmission on -the ceiling of the room. It serves for keeping the stock in the pans -constantly agitated, solution being thus very much promoted. - -[Illustration: FIG. 13.] - -The mode of working with this apparatus is very simple. Water being -admitted into the pan through _L_, the glue-stock is introduced and the -mass brought to boiling by admitting steam. The finished glue-liquor -is from time to time drawn off through the pipe _F_ into the settling -vessel. - -It is generally preferred not to concentrate the glue-liquor in the -pans to such a degree as required to obtain a jelly, which after -cooling, can be immediately moulded, experience having shown that less -concentrated liquors can be more readily and better clarified, and -yield a lighter and more transparent glue. - -Mr. Thomas Lambert gives the following process of cooking: The skins -are taken to the glue-boiler, which is an open vessel, 8 feet in -diameter at the top and 7 feet deep, and provided with a perforated -false bottom, through the center of which passes a two-inch pipe, one -end dipping below a layer of water at the bottom, the other projecting -about half the height of the boiler, this part being covered with a -perforated hood to spray the liquor through the mass. The skins are -placed on the false bottom and the added water at the bottom of the -boiler is brought to the boil by means of a steam pipe. The steam not -being able to escape quickly through the dense mass of glue-stock -above, exerts a pressure on the water, forces it through the pipe, to -be sprayed through the mass, and ultimately works its way to the bottom -of the boiler to be forced up again. This continual circulation of the -hot liquor rapidly dissolves the gelatinous matter, and when a strength -of 18 per cent. dry glue is reached, the first run is made to the -evaporating pan, the liquor passing through a filter of fine shavings, -to remove any suspended matter. Fresh water is added to the boiler, and -the boiling renewed. Three extractions are usually made, the last being -used for size. - -In order to avoid annoyance to the neighborhood from foul odors, -Terne’s glue-boiler shown in Fig. 14 may be recommended. The lead-lined -iron boiler _A_, with manholes _B_ and _C_, on top and side, is -furnished with a false perforated bottom upon which the glue-stock is -placed. Underneath the false bottom lies the coil _E_ with valve-box -_e_. The boiler is filled through the upper manhole with glue-stock and -water admitted, steam being at the same time introduced in the coil -and in order to quickly heat the water, direct steam is also admitted -to the boiler through the pipe _F_ and cock _G_. When the water is -boiling the cocks _G_ and _F_ are closed, the coil furnishing now -sufficient heat. During boiling some steam is allowed to escape through -the partly-opened cock _L_, all badly-smelling gases being thereby -carried to the fire-box of a boiler where they are burned. When boiling -is finished, the glue liquor remains for a short time in the boiler to -allow the melted fat to separate on the surface, the cocks _K_{1}_ and -_K_{5}_ and serving for drawing off the fat. The insoluble residues of -the glue-stock remain upon the false bottom and are taken out through -the manhole _C_. - -[Illustration: FIG. 14.] - - -2. CLARIFYING THE GLUE-LIQUOR. - -The clearness of glue, _i. e._, its freedom from undissolved -substances, is by no means a criterion of its value as an agglutinant, -since pulverulent inorganic substances (white lead) are frequently -intentionally introduced into some varieties, for instance into -Russian glue, without injury to their adhesive power. But as a turbid -appearance may also be an indication of unsoundness and decomposition, -the manufacturer endeavors by all means to obtain a clear product. - -A strict distinction should be made between clearness and color. -Very dark-colored glue may be very clear, and a very pale variety -the reverse, yet both possess excellent qualities. Both properties, -clearness and light color, cannot be obtained by the same process. - -Clearness will be first referred to. If the glue-stock has been -properly prepared by rendering adhering particles of blood and fat -innoxious by liming and subsequent careful washing, the separation of -the few remaining impurities, which may have passed through the straw -filter, is readily effected by allowing the liquor to stand, care -being had to keep it liquid as long as possible to give the grease -time to rise and the flocculent and fibrous impurities to settle. This -is best effected in a wooden vat surrounded by a wooden or sheet-iron -jacket, the intermediate space between jacket and vat being filled -with a non-conductor of heat, or, if required, it may be heated by the -introduction of steam. The grease is skimmed off as it rises, and when -the solid particles have settled the liquor is drawn off through a pipe -placed a short distance above the bottom of the vat. - -The size of the clarifying vat depends on the size of the boiler. -It is, however, best to have two vats for each boiler, in order to -keep the first liquor, which is always clearer and more concentrated, -separate from the last run. To be able to draw the upper layers of -purer liquor into cooling boxes by themselves, the vats are provided -with faucets at different heights. - -To prevent putrefaction of the liquor which readily sets in during -settling at a higher temperature, the vats should be kept scrupulously -clean, and from time to time rinsed with clean, hot water. It is also -advisable to line them with sheet-iron. - -Should the above-described mechanical separation not prove sufficient, -recourse must be had to other means. Alum and sulphate of alumina have -long been used for clarifying, 1 lb. of either of them, pulverized, -added to every 300 gallons of liquor, being as a rule sufficient. -Either of these chemicals removes the albuminous and extractive -constituents of the solution, and converts the dissolved free lime into -sulphate of lime, which settles readily, and prevents putrefaction of -the glue solution while drying under unfavorable circumstances. The -quantity of alum mentioned above does not impair the quality of the -glue. - -Albumen is sometimes used for the better qualities of glue, and -generally for gelatine, but a cheaper substitute is fresh blood, which -contains albumen and fibrin. Dry albumen is dissolved in cold water, -or white of egg is used direct, if procurable. Before adding either of -these substances, the liquor is cooled to 130° F., and the clarifier -well stirred in; then the temperature is raised to about 200° F., when -coagulation occurs, and the precipitate entangles the impurities and -falls to the bottom, requiring, however, from twelve to twenty-four -hours to clear. It is said that glues clarified with albumen have a -characteristic soapy smell and show a tendency to foam. - -The precipitation of the lime might be better effected by oxalic acid, -and the organic substances removed as scum by adding to the boiling -mass some astringent matter, such as a decoction of oak bark or hops; -but the purification has, in either case, to be done at the expense of -glutin. - -A glue liquor, which does not clarify by these means, is not sound, and -is derived either from spoiled raw materials, or such as have not been -thoroughly prepared, or has been injured in boiling. - -A far more difficult matter than the removal of mechanical admixtures -is to free the liquor from the coloring substances from which -it derives its color, and to discolor it without injury to the -characteristic qualities of the glue. - -The use of animal charcoal for such large quantities of somewhat -thickly-fluid solutions, which are liable to spoil at the high -temperature at which they would have to be filtered, is very -difficult, and the result not favorable, except the solutions could be -successfully deprived of their tendency to putrefy. The use of carbolic -acid is also in this case the only means of removing the great tendency -of the liquor to putrefy, and hence, if the liquor is to be discolored -by treatment with animal charcoal, it can only be done without danger -to the glue, by mixing it with carbolic acid. - -The object is more easily effected by bleaching the raw materials -previous to boiling them to glue. - -This is accomplished by placing the glue-stock, thoroughly limed and -while still moist, in a bath of chloride of lime, not too strong, as -otherwise the solution of the materials becomes difficult. A bath of -the proper concentration is made by dissolving about 9 ozs. of chloride -of lime in sufficient water to cover 110 lbs. of glue-stock. After one -hour add sufficient hydrochloric acid to obtain an acid reaction, which -is recognized by litmus-paper dipped in the bath turning red. - -Although the glue-stock is not bleached entirely through by this -process, the thin portions and outsides of the thick material acquire -a lighter color, and the first run of glue solution will have a light -color and can then be treated further without much difficulty. - -Sulphurous acid has been successfully used for the production of -colorless glue without the necessity of boiling. - -Waste of hides and skins is the only available material for this -process. Place the waste in water until putrefaction sets in. When this -is the case wash the material in a bag or wicker basket in running -water. Then pour 2½ parts of sulphurous acid over 12 parts of wet -material, mix the whole thoroughly and let it stand in a hermetically -closed vessel for 24 hours. Now draw off the acid, and after washing -the material thoroughly repeat the operation. When the vessel -containing the mixture of material and sulphurous acid is opened for -the second time the foul odor should be entirely superseded by that of -sulphurous acid, this being a sure indication of the correct execution -of the process. Wash the material, and, after squeezing, throw it -into a vat large enough not to be filled by it more than two-thirds -full. After filling the vat with water allow the mass to digest at a -temperature of 109.4° F. for 24 hours. The result will be a gelatinous -solution, which is drawn off and converted into glue. The undissolved -residue is transformed into gelatinous solution by pouring water over -it and allowing it to stand at a somewhat higher temperature. - -For carrying out this process and that of bleaching with chloride -of lime it is best to use a vat provided with a stirring apparatus, -somewhat like a hollander used by pape-rmakers, as being most suitable -for washing, disintegrating and mixing the material. - -Glue-liquor may also be successfully bleached with sulphurous acid, and -in speaking later on of the manufacture of bone glue, a very practical -apparatus for this purpose will be described. - -Glue-liquor bleached by sulphurous acid clarifies very readily and -is protected from spoiling. The resulting glue remains, however, -quite acid, and cannot be used for all purposes, especially not in -combination with colors, chemicals, etc., upon which the acid has a -destructive effect. - - -3. FORMING OR MOULDING THE GLUE. - -After clarifying, the liquor is run into moulds of deal wood or sheet -iron, lightly joined and of a rectangular form, slightly converging -towards the bottom so as to allow the more ready detachment of their -contents. They are about 3.25 feet long, 10 inches wide at the top, and -7¾ inches at the bottom, and 5 inches deep. When very regular cakes of -glue are desired, cross grooves of the required shape are cut in the -bottoms. After being well cleansed and ranged upon a level the boxes -are filled to the brim through large funnels with strainer cloths -affixed to their barrels. It is best to place them upon perfectly clean -stone flagging slightly inclined towards a reservoir for the reception -of such portions of their contents as may run over. The apartment in -which the work is performed should be clean and airy, a dry cellar -being the best for the purpose. In place of a large number of boxes, a -shallow vessel lined with sheet-iron and capable of holding the entire -quantity of liquor is sometimes used, from which the solid jelly is cut -out in cubic masses, which are further divided. - -This arrangement can only be recommended for establishments where -but one variety of glue is produced, and the different layers in the -clarifying vat are not separated according to their clearness. Before -running the liquor into the boxes the latter should be moistened with -water, or, if made of wood, coated with oil, stearine, or paraffin to -prevent the liquor from penetrating the wood and the solidifying glue -from adhering to the sides. - -After the solidification of the glue, which generally takes place in -twelve to eighteen hours, the boxes are inverted upon a table with a -smooth top of wood or stone previously wetted, so as to prevent the -adherence of the gelatinous cake to its surface. To detach it from the -sides of the boxes the moistened blade of a large knife is generally -used. - -Cutting the cubes of glue into commercial cakes or sheets is readily -accomplished by observing the following instructions:— - -The shape of the cakes depends principally on custom. The consumer is -used to a certain variety of glue, and if it is not offered to him in -the customary shape, he might refuse it and take his custom elsewhere. -The quality of the glue is the next point to be considered. If very -dark, it is advisable to cut the glue into thin cakes, and if turbid, -into thick ones, in order to make this defect the less apparent. -Thicker cakes can also be cut if the conditions for drying them are -favorable, and thinner ones if the reverse is the case. - -The mass is first divided by a steel or brass wire stretched over a -frame, like a bow saw, into horizontal layers. The size of these layers -is regulated by guides which are placed at distances corresponding with -the desired thickness of the cake of glue. Instead of one wire, as many -as the cakes of glue to be cut, can be stretched over the frame, which -is best made of iron and provided with conical pins by means of which -the wires can be tightened, in the same manner as piano strings, when -they have become slack by use. - -The width and thickness of the cakes of glue are regulated by the -distance of the wires from each other, and the length by the width of -the box. The cakes thus formed are dexterously lifted from the block -with the moist blade of a large knife and placed upon nets. - -Instead of using wooden or sheet-iron cooling-boxes, it is recommended -to pour a layer of liquor of the desired thickness of the glue cakes -upon large polished stone slabs, and when congealed, cut it into -sheets, which are placed upon the nets to dry. The advantages of this -method are obvious. The liquor cools more quickly by being exposed in a -thin layer upon a large surface, which reduces the danger of spoiling, -and a strong evaporation of water and consequent concentration take -place. Besides, the cakes show the smooth surface of the polished -stone, and become in a short time so hard, that when placed upon the -nets, the twine will make no impression upon them. - -Liquors which in gelatinizing do not become very solid, are not run -into forming boxes, but upon glass or zinc plates, and thus spread out -in a thin layer, acquire sufficient solidity to be removed cake by cake -after being cut. The plates upon which the glue is run are placed in -frames and laid upon a table furnished with a rim about 1 inch deep. -To accelerate gelatinization of the liquor, the table is flooded with -water before placing the plates upon it. - -Where cooling-boxes are used, the jelly when completely congealed is -placed upon a table with a stone plate, by inverting the boxes, and -then cut into cakes. Figs. 15 and 16 represent the tools for cutting -the jelly into cakes. The block of glue is laid upon the surface _A_, -Fig. 15, and the frame, _B_, is gently drawn along in the grooves, _a_. -In the upright portion of the frame are fixed wires at such a distance -from each other as required for the thickness of the cakes to be cut. - -[Illustration: FIG. 15.] - -[Illustration: FIG. 16.] - -When the block of glue has been cut in this direction, it is divided -by cuts perpendicular to the former, into cakes of a size in which the -finished product is to be brought into commerce. The apparatus shown in -Fig. 16 serves for this purpose. The vertical bars, _a_, furnished with -the wire, _b b_, serve as guides. The sheets thus formed are lifted -from the block with the moist blade of a large knife, and laid upon -nets. - -The machine shown in Figs. 17 and 18 is the invention of Mr. J. -Schneible, and it is for slicing and spreading glue-jelly preparatory -to drying, and it consists in the combination of a reciprocating cutter -with the jelly-box and a traveling belt-carrying frame for receiving -the slices as cut by the knife. - -Fig. 17 is a partly sectional side view of the machine, and Fig. 18 is -a cross-section of the same. - -[Illustration: FIG. 17.] - -_A A_ are side bars of the supporting frame, fitted at the ends with -cross-shafts, _a´_, carrying pulleys, _a a_, around which are endless -belts, _b b_. _c c_ are slide-ways upon the bars, _A_, and _d d_ are -slides carrying a cross-plate, _e_, and also a plate, _f_, to which -plate _e_ is attached a knife or cutter, _g_, the cutting edge of which -is at the edge of the plate, _f_, and about the same thickness as the -slices to be cut. The cross-shaft, _h_, is fitted in boxes on bars, -_A_, and near one end thereof it is provided with cranks at its ends, -which connect by rods, _i_, to the slides, _d_. - -[Illustration: FIG. 18.] - -From the opposite ends of the slides, rods, _k_, pass to loose arms, -_l_, on the shaft at the opposite end of the machine, and the arms, -_l_, carry pawls, _l´_, that engage ratchet-wheels, _m_, fixed on -the shaft, so that the shaft, _h_, being revolved, the slides, with -plates, _e f_, are reciprocated, and at the backward movement of the -cutter the pawls engage the ratchet-wheels, and belts, _b_, are moved a -distance equal to the movement of the knife. - -The jelly-box, _n_, is fixed to side bars, _A_, by brackets at its -ends, as shown in Fig. 18, and is placed above the cutter and the -plate, _e_, so that when the plate, _f_, is drawn out from beneath the -box the plate, _e_, takes its place for holding up the block of jelly. - -In operation the block of jelly is placed in box _n_, resting on plate -_e_. A frame provided with netting—such as is used for drying glue—is -placed on belts, _b_, beneath the box, and the shaft, _h_, being -rotated by power, the cutter moves forward and cuts a slice from the -jelly. The plate, _f_, at the same time moving away, the slice passes -upon the frame, and the return movement taking place, plate _f_ is -carried beneath the jelly-block, and the belts being at the same time -moved, the frame is carried forward in position for receiving the next -slice apart from the first one. In this manner, as slice after slice -is cut, they are spread on the frame, and the frames, when filled, -are carried to the end of the machine for removal. The plate, _f_, is -adjustable, so as to vary the thickness of the slices cut. - -The box may be divided into cells of any size desired, so that each -movement of the knife will cut a slice from the bottom of each cell, -and the box extending the full width of the drying frames, all the -slices cut at once will be properly spread. - -In order to keep the plates, _e f_, moist, so as to prevent the -glue-jelly from sticking thereto, there are fitted at the sides of the -jelly-box, _n_, open-bottomed boxes, _o_, containing fibrous material -soaked with water, which, resting on plates, _e f_, keeps their -surfaces moist. - -The machine saves the troublesome and expensive work of spreading the -jelly by hand, as has been heretofore practiced. - -The knife is to be attached to plate, _e_, in any suitable manner, and -the surface of plate, _f_, may be corrugated, so as to slide on the -jelly more readily. - -[Illustration: FIG. 19.] - -The cutting apparatus patented by M. Devoulx, of Marseilles, is much -used in France. The machine stands upon a board or table, upon which -are fastened two uprights, far enough apart to allow of the passage of -a truck carrying the glue, which is cut into cakes by blades or wires -stretched between the uprights. - -[Illustration: FIG. 20.] - -Fig. 19 shows the perspective elevation of the machine with its truck. -The upper part is filled up for the reception of the glue to be cut up -into cakes. The sides are omitted in this figure in order to admit of -a better explanation of the separate parts. - -Fig. 20 gives the same view, except that the truck, the upper part of -which is closed, is between the uprights, and contains the glue to be -cut. - -Fig. 21 represents the moment the wires have passed through the glue -and cut it into cakes. In all the figures, _a_ is the wooden frame upon -which the machine rests, _b_ the table-plate fastened to the frame, -_c_ and _d_ are the uprights, between which the cutting wires are -stretched, and _f_ the truck carrying the glue. - -[Illustration: FIG. 21.] - -[Illustration: FIG. 22.] - -Figs. 22 and 23 show the truck by itself, _g_ representing the bottom, -and _h_ the back, which is provided with slight grooves, into which -the wires catch to assure the entire cutting through of the block of -jelly; _i_ is the upper part of the truck, which opens by means of a -hinge, and when closed is fastened with the pin, _k_. This upper part -of the truck is fastened to the back part of the truck by means of a -screw, which allows it to be set higher or lower, according to the size -of the block of jelly to be cut; _m_ is the bar of a rack fastened to -the truck, and serves for moving the latter. The driving gear, _n_, the -shaft of which carries a crank, _o_, catches into the rack. - -[Illustration: FIG. 23.] - -Two boards, one on each side of the truck, serve to keep the block of -jelly in position, and guide the truck. - -With this machine 120,000 to 130,000 cakes can be cut in five or six -hours. - - -3. DRYING THE CAKES OF GLUE. - -Drying the cakes is without doubt the most precarious part of the -manufacture. The jelly contains a large quantity of water which, to -prevent decomposition of the jelly before it is converted into glue, -must be evaporated as quickly as possible. In favorable weather, drying -may be accomplished either in the open air or in covered sheds. - -Drying in the open air is connected with many inconveniences, for if -the sun strikes the cakes of jelly when they still contain a large -quantity of water, they may become soft so as to run through the -meshes of the net, or they may dry so quickly as to prevent them from -contracting to their proper size without numerous cracks and fissures. -If frost supervenes, numerous cracks may be formed in the cakes from -the congelation of their water, or a shower of rain may cause much work -and damage. In consideration of all these inconveniences, it is best to -conduct the operation in a drying-room. - -To insure a constant circulation of air, which is absolutely necessary -for the expulsion of the aqueous vapor caused by the evaporation of -such a large quantity of water, the drying-room should be at least 10 -feet high, even if intended for summer use only, and the windows be -provided with Venetian blinds so as to shut out the sun, if necessary, -without disturbing the circulation of air. - -To dry the cakes in heated rooms in winter is a more difficult matter, -as provision has to be made for the removal of the aqueous vapor, and -a current of warm dry air has to be kept up at the same time. But such -a room is an absolute necessity for the manufacturer on a large scale, -who, in order to carry on his business without interruption throughout -the entire year, must be independent of the changes of wind and weather. - -[Illustration: FIG. 24.] - -The size of the drying-room should be proportional to the daily -production. Constructions are fitted up with the requisite frames for -the reception of the glue cakes, and are heated by steam pipes arranged -along the walls. In the floor in the immediate neighborhood of the -steam pipes are openings, which can be opened and shut at pleasure, -for the admission of fresh dry air. The latter on entering the room -is heated, and after passing over the frames and absorbing water from -the glue cakes, escapes through openings in the ceiling to a space -above it from which it is withdrawn by means of ventilators in the -roof. A constant change of air must be kept up. The quick drying of -the glue is of the utmost importance, as otherwise the jelly putrefies -either entirely or partially, and the glue acquires a turbid and mean -appearance. Too much heat causes the cakes to bend and crack. The -cakes are laid upon widemeshed nets of twine stretched in frames 6½ -to 8 feet long and 3¼ feet wide. Fig. 24 represents the form of nets -commonly used. The nets are placed upon frames, such as shown in Fig. -25, arranged around the drying-room in the neighborhood of the steam -pipes and air flues. As the cakes have to be occasionally turned upside -down upon the nets, the latter must be placed at convenient distances, -one above the other in the frames. - -[Illustration: FIG. 25.] - -The use of twine netting has been found to be attended with many -disadvantages, the principal ones of which are given by S. Rideal as -follows: - -1. “Being freely handled in the making, the netting is almost always -impregnated with dangerous organisms which penetrate the moist glue -cakes, and cause moulding or putrefaction. When this occurs, it is -usually attributed to a state of the atmosphere, but if the cakes are -examined, the alteration will generally be found to originate along -the lines made by the netting. The fault could be cured by sterilizing -the net for an hour at 212° to 248° F. in a hot oven, but besides the -expense, the fibre is thereby weakened. Moreover, the spores of a few -bacteria, such as _Bacillus subtilis_, which is widely distributed and -has the power of liquefying gelatine, will bear a heat of 248° F. for -over an hour, and still be capable of growing. - -2. “However smooth the fibre, the glue will stick in places, leaving -small remains, which being hygroscopic, become ’sour,’ and set up the -objectionable bacterial changes in the subsequent batches. - -3. “Owing to sagging, rotting, scouring, or wearing into holes, the -life of cotton or hemp netting is so short that the constant renewal is -a considerable item. A whole batch is frequently spoilt by the fault -of a net. In some works, heaps of old netting are found, which become -very putrid in the rain and sun, and give rise to mysterious bacterial -inroads in the factory. In others they are regularly burnt under the -boilers. - -4. “The considerable overlap or selvedge required for securing the -edges of the net involves a waste of the area, and also some difficulty -in refixing.” - -For this reason metallic netting has been largely adopted. The best -material has proved to be a heavily galvanized iron-wire netting having -no less than 15 to 25 per cent. of its weight of zinc. It can be -strengthened by longitudinal and transverse wires or ribs. It must be -examined by the microscope to see that it is perfectly free from holes -or cracks, and should last at least two years in constant use. - -The temperature of the drying-room requires careful regulation, and -should never be allowed to rise above 68° to 77° F., as otherwise the -glue would soften and run through the meshes of the net, or adhere so -firmly to the twine as to require the nets to be put in hot water for -its separation. Dryness of air is of far greater importance in the -drying process than a high temperature. To promote this dryness of air -and prevent the aqueous vapor from condensing, evaporating, and again -condensing upon the cold walls of the room, they are wainscoted. Thus -protected by a bad conductor, they acquire a higher temperature, and -the aqueous vapor, instead of being precipitated upon them, is carried -off by the air-currents. - -As the cakes placed in the immediate neighborhood of the steam pipes -and near the floor where the dry air enters, dry quickest, the nets -containing them are shifted after some time to a higher part of the -drying-room and their former places filled with cakes still wet. When -the cakes are dry, they are finally desiccated in a room at a higher -temperature, which serves to harden and improve them. - -In modern times drying-rooms have been almost entirely abandoned and -in this country long drying galleries are used, sometimes 250 feet -in length and 6 to 8 feet square, with traveling platforms on rails -carrying the sheets of glue on stout galvanized netting. Wood is found -to be a better material for the galleries than stone or brick. - -Figs. 26 to 28 show an apparatus for drying glue which is the invention -of W. A. Hoeveller. - -Fig. 26 is a plan section, and Fig. 27 a side elevation in section, of -this improved drying-alley. Fig. 28 is an end view in section. - -The form and arrangement are as follows:— - -_A B_ represent the two parts of the alley, separated by the partition -_C_, which is shorter than the alley, so as to leave a communicating -space at both ends. - -At the front of section _A_, is located a blower, _D_, actuated by a -steam-engine or other motor, _E_, also located within the walls of the -alley. The whole current from blower _D_, is directed through section -_A_ of the alley, whence it turns into section _B_, and comes back -through it, to be again drawn into and forced out of the blower into -section _A_. By this means the contained air of the alley is set in -continuous motion through the two sections successively, and as the -structure is made as air-tight as practicable in such cases, the air -remains unchanged until the doors _F_, or either of them, are opened to -discharge the vitiated air and let in the fresh. - -In sections _A_ and _B_, is placed the railway _a a_, to admit of the -convenient movement of the contents in process of drying, which are -generally set on cars or buggies. - -[Illustration: FIG. 26.] - -[Illustration: FIG. 27.] - -[Illustration: FIG. 28.] - -In section _A_, in front of blower _D_, is placed a steam or other -heating device, _G_, which may be of any form or design adapted to -allow the air from blower _D_ to pass through it and to heat such air -while passing therethrough. The inventor prefers the radiating coil -for such purpose, the steam entering at _b_, and emerging at _c_. At -the other end of the alley, which by the double construction is in -section _B_, just back of the blower and heating-coil, there is placed -a condensing-coil, _H_, of a construction similar to coil _G_, and -having inlet _d_, and outlet _e_. Through this condenser there is kept -flowing a refrigerating liquid or brine, which renders the condenser -very cold. The continuous current of air from the blower passes over -the contents of the cars or trays in the alley and takes up moisture in -its passage. After such passage the air is charged with moisture and -comes in contact with the coils of the condenser _H_, upon which the -charge of moisture is condensed, and the air emerges dry again, enters -the blower, and is again made the vehicle by which the moisture of the -glue or other contents is transported to and deposited on the condenser. - -In drying glue by this method do not use the steam-coil at the first -stage of drying a charge, as the drying should not be effected too -rapidly; but as soon as the product begins to stiffen properly, admit -the steam to the coil _G_, and thereafter the operation is continuous, -as above described. - -By doubling up the alley into two sections, as shown, the inventor is -enabled to erect the alley in a more contracted space. In a length of -ninety feet he obtains the benefit of a single alley one hundred and -eighty feet long. Section _B_ may, if desired, be located on top of -section _A_. Doors may be located wherever desired, to facilitate the -movement of the trays or cars and the placing of them in and their -removal from the alley. - -[Illustration: FIG. 29.] - -By the above apparatus the drying can be perfected in a very much -shorter time than can be done by the old alleys, and operations can be -conducted in hot weather without hindrance from the condition of the -atmosphere. - -In cases where the atmosphere is dry enough to dispense with the -heater and the condenser, the inventor can throw the doors _F_ wide -open, extend the partition _C_ out to that end of the alley, and then -preserve a continuous forced draft of sufficiently dry air in both -alleys for the purpose. As there are many days during the year fine -enough to give reasonably dry air, operations can be conducted with -the blower alone in this way, and thus economize the steam and the -refrigerating-brine. - -[Illustration: FIG. 30.] - -Figs. 29 and 30 show a longitudinal section, with upper and ground -floor plans of a modern drying-house, as given by Thomas Lambert. In -the ground floor the whole of the liquors are jellied in coolers, -and then cut into cakes by the two cutting machines in the centre. -Here a hoist, _E_, Fig. 30, is placed which carries the cut cakes on -“glasses” to the floor above. This forms the drying-floor, and is -partitioned off in three divisions, running nearly the length of the -building. The two outer divisions form the tunnels proper, and at the -ends are fixed two powerful revolving fans, driven at high speed and -drawing the air through the tunnels at a high rate. At the opposite -ends of the fans are fixed a series of 6-inch pipes, heated up by -waste steam, and the air passing between is warmed up to any desired -temperature, of necessity below 78° F. In the center passage a number -of girls are employed in transferring the cut cakes to the nets, which -are built upon a carriage running on a small railway. The carriage -with the complement of filled nets is run to the end of the division, -transferred to the lower railway, _C_, by which it is carried either -to the right or left hand tunnels as desired; the glue when dried on -the nets is run to the other end and by another lower railway brought -to the middle division, and ultimately by the hoist raised to a large -store-room, seen in section, where the glue is sorted and bagged. At -the end of the store-room is placed a grinding machine, and all the -off-color and twisted cakes are ground to a powder and sold as powdered -glue. The manufacturer by varying the size of the cake, its thickness, -and its color, may make any number of grades from the same boiling. - -Fleck proposes to accelerate the drying of glue by utilizing the -water-absorbing power of some salts, such as Epsom and Glauber’s salts, -ammonium sulphate, crystallized acid sodium sulphate, etc., for the -purpose of withdrawing water from the glue cakes. For the practical -application of this principal a shallow, water-tight, wooden box is -required. The bottom of the box is sprinkled with a layer of the -water-absorbing salt about half an inch deep, and covered with a moist -linen cloth. Upon this is placed the jelly cut into sheets and also -covered with a moist cloth, a layer of salt being finally scattered -over it. After standing for a few hours, the box is slightly inclined -and the salt solution allowed to drain off through a hole in the -bottom, the dropping ceasing in from 12 to 18 hours. If now the upper -cloth is taken off with its layer of salt, the glue beneath it will be -found so far deprived of its moisture that when placed in the sun or -exposed to other heat, it will become completely dry in a short time -without either melting or spoiling, and in winter may be laid upon -drying-floors with the same result. The salt-solution formed may be -evaporated to crystallization and the salt thus obtained be again used. - -After the treatment with the salt, the jelly contains 70 to 75 per -cent. of anhydrous glue, while the content in jelly not thus treated -varies between 7 and 28 per cent. according to the concentration of the -liquor from which it has been derived. It is claimed that the adhesive -power of the glue is not injured by this treatment. - -Commercial glue must not only be thoroughly dry, but should also -present a good appearance, showing especially lustre. However, after -drying, the glue is dull, spotted, dusty and sometimes even mouldy. To -give a good lustrous appearance the dry cakes are dipped in warm water -and replaced upon the nets to dry. - - - - -CHAPTER V. - -MANUFACTURE OF BONE-GLUE. - - -The manufacture of bone-glue differs chiefly from that of skin-glue in -the processes employed for the conversion of the glue-yielding tissues. -This conversion may be effected by boiling the bones with water, or -subjecting them to the action of steam, or by first extracting their -mineral constituents with acid, and boiling the remaining cartilaginous -mass with water until dissolved. - -When the finest quality of all varieties of glue, namely, colorless -gelatine, is to be manufactured, the bones should not be comminuted in -a stamping mill, because in consequence of the unavoidable development -of heat, they acquire a slightly empyreumatic odor which adheres to the -gelatine prepared from them, and cannot be removed. - -In factories working on a small scale, the bones are comminuted by -hand, being placed upon a grate-like support of heavy iron rods -and crushed with a wooden hammer, the face of which is studded -with big-headed nails. In larger establishments the crushing rolls -previously described are used, and in order to lessen the effect of -heating as much as possible, the crushed bones are allowed to fall -directly into a vessel filled with water. - -Fat being a very valuable constituent of bones, it should be gained -as completely as possible, by boiling or steaming the bones, or by -extracting them by means of a solvent, such as benzine or carbon -disulphide. - - -1. BOILING BONES. - -This is the older and more incomplete process of extracting the fat. -The bones are placed in a boiler, covered with water so that it -stands a few inches deep over them, and the whole is boiled over an -open fire. The melted fat collecting on the surface of the water is -skimmed off. By boiling, a portion of the glue-yielding substance is, -of course, converted into glue, and passes into the water. In order not -to lose this glue, the same water is repeatedly used for boiling fresh -quantities of bones, and is finally used for feeding pigs. By this -method 4 to 5 per cent. of fat is at the utmost obtained. - -The bone fat obtained by direct boiling of the bones, is, if entirely -fresh material has not been used, of very inferior quality. It is dark -yellow to deep brown and of a disagreeable odor. It is only fit for -certain purposes, and to be utilized in the manufacture of soap has to -undergo a special process of purification, whereby it is rendered white -and odorless. - - -2. STEAMING BONES. - -In order to obtain a larger quantity of fat than is possible by -boiling, the bones are preferably steamed, _i. e._, subjected to the -action of high-pressure steam. This is effected in a closed cylinder -of thick boiler-plate, into which steam of ½ to 1 atmosphere pressure -is admitted. The cylinder is provided with a perforated false bottom -upon which the bones are placed. By steaming for two or three hours, -all the fat is extracted from the bones and collects, together with -the condensed water formed by the steam coming in contact with the -cold bones, underneath the false bottom. However, by the continued -action of high-pressure steam upon the bones, a considerable portion -of the glue-yielding tissue is converted into glue, which passes into -the resulting liquor. This, however, is no drawback if only fat and -glue are to be obtained from the bones, since by continued steaming, a -liquor still richer in glue results, and need only be evaporated. But, -as a rule, the greater portion of the bones, especially the granulated -parts, are to be utilized in the manufacture of animal charcoal, and, -hence, great care has to be observed in steaming. - -Animal charcoal is produced by calcining bones in vessels from which -the air is excluded, whereby the glue-yielding tissue is converted -into carbon, which is distributed upon the bone-earth. Since the value -of animal charcoal depends on the quantity of carbon it contains, a -product prepared from bones highly steamed, will evidently be of little -value, as a considerable portion of the glue-yielding substance has -been converted into glue. - -If the bones are to be used for the production of animal charcoal they -should be subjected to the action of high-pressure steam only long -enough to extract the fat, but the resulting glue-liquor is very thin -and difficult to work. The watery glue-liquor is first drawn off, and -the fat which comes last is caught by itself. The thin glue-liquor is -evaporated in vacuum. - - -3. EXTRACTION OF BONES. - -To avoid the loss of glue-yielding substance which is unavoidable in -steaming bones, even if only for a short time, in many plants the -fat is now extracted by treating the bones with benzine or carbon -disulphide. No loss of glue-yielding substance being involved by this -process, bones thus treated yield the best quality of animal charcoal. - -The fat obtained by extraction with carbon disulphide has such a -disagreeable odor as to render it almost worthless. In addition this -solvent is very volatile, consequently very inflammable, and is also -very poisonous. For these reasons its use for the extraction of fat has -been almost entirely abandoned. - -Figs. 31 and 32 show an apparatus for the use of benzine which is -the invention of Messrs. Wm. Adamson and Charles F. A. Simonis, -of Philadelphia, Pa. It is for the purpose of treating animal and -vegetable substances with hydrocarbons for extracting therefrom oily, -fatty and resinous matter; and the object of this invention is to -cause hydrocarbons to trickle through such substances instead of -flooding the same, so that it will take up the oily, fatty and resinous -matter without any of the albuminous or gelatinous ingredients. - -Fig. 31 is a vertical section of apparatus wherewith this invention may -be carried into effect; Fig. 32, an inverted plan view of part of Fig. -31. - -[Illustration: FIG. 31.] - -[Illustration: FIG. 32.] - -_A_ is a vessel, preferably of cylindrical form, and containing an -upper perforated diaphragm, _a_, and lower perforated diaphragm, _b_, -the former having a central opening, through which the material to be -treated may be introduced between the two diaphragms, and this opening -having a detachable perforated cover, _d_. - -On the top of the vessel there is an opening, _e_, furnished with a -detachable cover, _f_, and at the bottom of the vessel there is an -outlet-pipe, _h_, furnished with a suitable cock or valve, _i_. - -Liquid hydrocarbon, preferable such as is of a volatile -character—benzine, benzole, or gasoline, for instance—is introduced -into the vessel above the diaphragm _a_ through a pipe, _H_, and -perforated ring, _I_, or otherwise, the hydrocarbon passing through -the diaphragm and falls in a shower on the substance contained in the -vessel. - -The hydrocarbon will trickle through the mass, taking up whatever oily, -resinous, or fatty matter it comes in contact with until it falls -through the lower diaphragm into the space _D_, whence it may be drawn -off from time to time through the outlet-pipe, _h_. - -In extracting oily, fatty, or resinous matter from vegetable or animal -substances by hydrocarbons, it has been the practice either to subject -them to hydrocarbon vapors, or to immerse or steep the substances in -hydrocarbon until the latter takes up the oily, fatty, or resinous -matter. - -The vapor plan is preferable in treating wet animal substances, such as -offal; but for dry vegetable or animal matter—seeds, for instance, or -the residuum resulting from the rendering of tallow—we prefer the plan -before described. - -The flooding or steeping of animal or vegetable matter in liquid -hydrocarbon results in a mixture or emulsion of gelatinous, albuminous, -and fatty or oily matter, combined with animal or vegetable tissues, -the whole forming an amalgamated mass; hence, whatever fatty or oily -matter is extracted is accompanied by more or less of the suspended -gelatine or albumen, either of which is more difficult to remove from -the oil or fat, and has a tendency to discolor the same. - -This difficulty, it has been found, can be obviated by preventing the -hydrocarbon from remaining in a quiescent state in contact with the -material; in other words, by causing it to trickle through the mass, -which, by this plan, retains its granular condition, and gives out its -oil or fat to the hydrocarbon without the albuminous or gelatinous -matter. - -In the apparatus before described, for instance, an occurrence of the -objectionable flooding of the material, tending to bring about the -results previously mentioned, is obviated by never permitting the -extract in the lower portion of the vessel _A_ to reach the lower -diaphragm _b_. By drawing off the extract from time to time, any -impediment to the free discharge of the hydrocarbon with such oily and -resinous matter as it has taken up, through the lower diaphragm, is -prevented, and a continuous dripping of the hydrocarbon through the -mass secured. - -The extract obtained by the trickling or filtering process is much more -concentrated than that obtained by the steeping and flooding process. - -_Adamson’s Method for Treating Substances with Hydrocarbon Vapor -for the Purpose of Extracting Oils, Fats, etc._ This improvement is -intended to prevent the fetid or other odors imparted to the vapor -from the substances treated from being recommunicated to the said -substances, and to the extracts obtained therefrom through the medium -of the vapor from the re-used hydrocarbon. The vapor is obtained from -benzine, benzole, etc. - -Fig. 33 represents, partly in section, the apparatus whereby the -invention may be carried into effect. - -_A_ is a vessel in which the substances have to be treated by -hydrocarbon vapor, the said substances being introduced into the vessel -through a manhole, _x_, and deposited on a perforated diaphragm, -_B_, the manhole being provided with a suitable cover. A steam-coil, -_D_, is placed in the vessel in a space beneath the diaphragm, and -liquid hydrocarbon is introduced into the said space, and is there -vaporized by the steam-coil. The vapor rising through the perforated -diaphragm permeates the substance upon the same, so as to extract -therefrom the oily, fatty, or resinous matter, which passes downward -through the diaphragm into the space below the same, whence it may be -drawn off from time to time through the discharge-pipe _j_. Liquid -hydrocarbon may be introduced from a tank, or from a source explained -hereafter, into the top of the vessel _A_, so that it will pass through -the material and be vaporized when it reaches the coil; the said -material being in this case subjected to a downward current of liquid -hydrocarbon and an upward current of vapor. - -Previous to this invention it was Mr. Adamson’s practice to cause the -vapor, after acting upon the substances in the vessel, to pass through -a worm in a condenser, the lower end of the worm communicating with the -vessel, _A_, beneath the diaphragm, as shown in Fig. 35, p. 85, so that -the hydrocarbon was used over and over again. But in practice this has -been found objectionable in many cases for the following reason:— - -In treating animal offal, for instance, for the extraction of fats, -fetid odors are imparted to the hydrocarbon vapor, and remain, to a -considerable extent, in the condensed vapor when the latter is restored -to the vessel _A_; hence, the fetid odors were recommunicated both to -the fatty extracts and to the material. The same objections have been -experienced in treating meat for preservation and vegetable matter for -the extraction of oil by hydrocarbon vapor. - -This difficulty is obviated in the following manner: The vapor-pipe -_D´_ communicates with a vessel _H_ at the top of the same, and the -vapor is met by numerous small jets of cold water—in the present -instance, from a perforated tubular ring, _m_, into which the water is -forced through a pipe _n_. - -Many different appliances may be used, such as roses, revolving jets, -etc., for causing a spray through which the vapor must pass, and by -which it must be condensed. The result of this will be a supply, _I_, -of tainted water on the bottom of the vessel, _H_, and a quantity, _J_, -of washed and purified hydrocarbon above the water, the latter having -taken up the fetid odors. - -The washed hydrocarbon may be drawn off through a pipe, _g_, into any -suitable vessel, and thence introduced through the pipe _h_ into the -vessel _A_, or may pass directly into the latter to be again vaporized -therein, the vapor after permeating the material and passing through -the pipe _D´_ being simultaneously condensed and washed in the vessel -_H_, preparatory to being returned in the condition of purified liquid -hydrocarbon to the vessel _A_. - -[Illustration: FIG. 33.] - -By the practice of this process, the inventor is enabled to obtain a -purer extract than heretofore, and, at the same time, the substances -acted upon are more free from noxious odors. - -Changes may be made in the apparatus shown in Fig. 33, as, for -instance, the vessel _A_ may consist of a horizontal hollow cylinder, -and the vaporizing of the hydrocarbon may be accomplished otherwise -than by a steam-coil. - -[Illustration: FIG. 34.] - -_Adamson’s Method for Treating Substances with Liquid Hydrocarbon for -the Purpose of Extracting Oils, Fats, etc._ This invention relates -to a method of treating animal and vegetable substances with liquid -hydrocarbons, such as benzene, benzole, etc., for the purpose of -extracting from such substances oils, fats, etc. - -The object of this improvement is to prevent the fetid and other odors -imparted to the liquid hydrocarbon by the substances treated from being -recommunicated to the substances and to the extracts therefrom by the -liquid hydrocarbon when re-used. - -In Fig. 34, there is shown a sectional view of apparatus whereby this -invention may be carried into effect. - -_A_ is a vessel into which the substances to be treated are introduced -through a manhole, _x_, provided with a suitable detachable cover, -and through an opening in the upper perforated diaphragm, _B_, a -detachable perforated plate, _b_, being placed over the opening after -the substances have been passed through the same, the substances being -supported by the lower perforated diaphragm, _B´_, beneath which is a -space for receiving the extract and liquid hydrocarbon after the latter -has percolated through the mass in the vessel. The extract, which -occupies the lowest position in the vessel, may be removed therefrom -from time to time prior to being purified by distillation or otherwise. -The liquid hydrocarbon is permitted to pass from time to time through a -pipe, _d_, into a vessel, _D_, where it is met by jets of water from a -pipe, _f_, the hydrocarbon and water being thoroughly agitated in the -vessel by a revolving paddle-wheel, _E_. This washing of the liquid -hydrocarbon may be accomplished by different appliances. For instance, -the paddle-wheel may be dispensed with, and water forced upward into -the vessel from below in the form of numerous small jets. The water and -hydrocarbon after this washing operation are permitted to pass into -the subsiding-vessel, _H_, the hydrocarbon being above and the water -below, the fetid and other odors divided by the hydrocarbon from the -substances in the vessel, _A_, having, during the washing operation, -been transferred to the water, which may be drawn off from time to time. - -The washed and purified hydrocarbon may be pumped directly through -a pipe, _m_, into the vessel, _A_, to be re-used for treating the -substances therein; or it may be pumped, first, into a reservoir, and -permitted to flow from the same into the said vessel, _A_. - -More or less hydrocarbon is wasted by being drawn off with the extract, -and to make up for this loss a supply may be introduced at intervals -from a tank through the pipe, _h_. - -By the practice of the process described above, the inventor is -enabled to obtain a purer extract than by the ordinary process of -treating substances with liquid hydrocarbon. At the same time the -substances treated will be much more free from noxious odors than when -the hydrocarbon is used over and over again without washing. - -It is not essential strictly to adhere to the apparatus shown in Fig. -34, as the construction of the apparatus will, in fact, depend in a -great measure on the locality in which it is to be situated. - -_Adamson’s Process for Removing Hydrocarbons from Substances which have -been treated therewith._ This process consists of washing from animal -and vegetable substances the hydrocarbon which they retain after being -treated therewith for the extraction of oils, fats, etc., and for other -purposes. - -Different apparatus may be employed for carrying out this process, and -it may be conducted in the same vessel in which the material is treated -with hydrocarbon. - -The vessel, which is shown in Fig. 35, has been found to answer well -for this purpose. - -This vessel is furnished with a suitable detachable cover, _a_, and -with two perforated or wire-gauze diaphragms, _b_ and _d_, both -extending across the interior of the vessel, one near the top and the -other near the bottom of the same. - -A steam-coil, _B_, communicating with any adjacent steam-generator, -is contained in the vessel below the lower diaphragm, to vaporize -the hydrocarbon, the vapor passing through the substance between the -two diaphragms and out through a pipe, _D_, which passes through a -condenser, _E_, the latter restoring the hydrocarbon to a liquid form, -in which it is reconveyed to the vessel through a pipe, _D´_. - -In practicing the washing process a pipe, _m_, to introduce water -into the vessel, and one or more outlet-pipes, _n n´_, two in the -present instance, are necessary. There may also be a pipe, _p_, through -which air can be introduced into the vessel, under the circumstances -explained hereafter. - -When the treatment of the material in the vessel with hydrocarbon -vapor or liquid hydrocarbon has been completed, steam is cut off from -the coil _B_, the pipes _D_ and _D´_ are closed, and the cover _a_ may -be removed. - -[Illustration: FIG. 35.] - -Water is now admitted through the pipe _m_ to the space in the vessel -below the diaphragm _d_, and the cocks of the outlet-pipes _n n′_ are -opened. - -The water permeates the material, passes upward through the same, and -carries with it the hydrocarbon, the latter having a tendency to rise -with the water. - -As the water, and whatever hydrocarbon accompanies it, pass through -the upper diaphragm, _b_, the hydrocarbon will at once rise to the -surface, and will pass through the upper outlet-pipe, _n_, into -any suitable receptacle, the water passing off through the lower -outlet-pipe. - -If this mode of separating the hydrocarbon from the water is practiced, -the admission of water to the vessel should be such in respect to the -outflow that the liquid will remain at or near a uniform level, that -is, the surface of the liquid should bear the relation shown in the -drawing to the upper outlet. - -The water and hydrocarbon, however, may be drawn off indiscriminately -into a suitable receptacle, and then separated by decantation; but it -is advisable in all cases that the water should extend above the mass -of material in the vessel, so that the hydrocarbon can at once rise to -the surface as it escapes from the substance. - -When the material is of such a character as to be closely packed -and not easily displaced by the upwardly-flowing water (and this -is especially the case with seeds which have been treated with -hydrocarbons), it is necessary to agitate the mass, so that the water -can gain access to every part thereof. This agitation the inventor -prefers to effect by air under pressure introduced through a pipe, _p_, -although mechanical appliances may be used for the purpose. - -It will be understood that the process may be conducted in a vessel -separate from which the substances have been treated with hydrocarbon. -A vessel similar to that shown, for instance, but without the coil and -pipes, _D D´_, may be used, and may be furnished with trunnions (shown -by dotted lines) and adapted to bearings, so as to be easily tilted -when its contents have to be removed; or the vessel may have an opening -near the lower diaphragm for the withdrawal of its contents, a suitable -detachable door being adapted to the opening. - -_F. Seltsam’s apparatus._ In this process the solvent is boiled with -the bones, previously coarsely crushed and the dust sifted out, in a -strong closed vessel, so as to obtain a higher temperature, greater -penetration and avoidance of loss. The vapor ascending condenses in the -pores, extracts the fat and collects under the false bottom as a layer -of solution which is subsequently distilled. The apparatus is shown -in Fig. 36. The cylinder, _A_, is capable of withstanding a pressure -of 10 atmospheres, and serves for the generation of steam and as an -extracting vessel. It is filled with bones and hermetically closed. -The required quantity of solvent is then brought by means of the pump, -_B_, from the reservoir, _C_, through the pipe, _D_, into the cylinder, -_A_, and the latter is heated. The vapors formed force the air through -the pipe, _E_, into the condenser, _F_, where any vapor which may be -carried along is condensed and passes through the pipe, _G_, back into -the reservoir, _C_. - -[Illustration: FIG. 36.] - -When all the air has been expelled from the apparatus and the pores -of the bones, the cock on the pipe, _E_, is closed. The cylinder, -_A_, is then heated so that a pressure of a few atmospheres prevails -in it. The vapors now act energetically upon the bones, the dissolved -fat collecting upon the cylinder; the cock on the pipe, _H_, is then -opened, and the superheated fluid discharged under high pressure into -the distilling apparatus, _J_, and the solvent is distilled off from -the fat by means of steam. The vapors of the solvent pass through -the pipe, _K_, into the condenser, _F_, and from there back into the -reservoir, _C_. - -When the manometer on _A_ indicates no pressure, the cock on the pipe, -_H_, is closed and the cylinder, _A_, again heated, the pipe, _E_, -being open, so that any solvent still adhering to the bones may escape -to the condenser, _F_. - -[Illustration: FIG. 37.] - -Figs. 37 and 38 illustrate Seltsam’s apparatus as improved by Th. -Richter, whereby the operation becomes entirely free from danger, the -vaporization of the solvent being effected by steam only, and the work -is carried on continuously. - -There are two extracting vessels, _A_ and _B_, of thick boiler-plate, -and provided with false bottoms, _G_, upon which the bones are placed, -steam being admitted into the space between the true and false bottoms. -The extracting vessels are surrounded by the jackets, _C_, and are -further provided with the vacuum gauges, _E_, and the air-cocks, _F_. - -There are, in addition, two other vessels, _H_ and _J_, which contain -water, a vessel, _K_, for the solvent, and an air-pump, _L_. The -operation is carried on as follows: - -[Illustration: FIG. 38.] - -The extracting vessels, _A_ and _B_, are charged with bones, all the -cocks, with the exception of _M_ and _N_ closed, and the air-pump, -_L_, is set in motion, whereby a vacuum is formed in _A_. When this is -sufficiently large, water is admitted from _H_ through the cock _O_ -into the space _P_. The water-cock is then closed and the steam-cock, -_Q_, opened. The steam entering the space, _R_, brings the water in -_P_ to the boiling-point, and the air-pump sucks off the steam formed -after the cock, _N_, is opened. The air-pump is then stopped and all -the cocks closed, except _S_. The solvent now passes from the vessel, -_K_, into the space _P_, and after closing the cock _S_, is evaporated -by the admission of steam into _R_. The water-cock is then opened and -cold water admitted into the jacket _C_, the solvent saturated with fat -being thereby condensed in _P_. The water is then discharged from _C_ -and steam introduced into _R_{1}_, whereby the solvent is evaporated -and forced into the extracting vessel _B_ by means of the air-pump, -_L_, after closing the cocks _M_ and _V_. - -The process is then repeated in _B_, after a vacuum has been created in -the same manner as in _A_. - -In the meanwhile the vacuum in _A_ is interrupted by opening the -air-cock _F_ and the fat drawn off through _P_ by opening the cock _U_. - -The bones freed from fat are removed through the manhole _D_, and _A_ -is charged with fresh material while the operation is carried on in -_B_. Thus the operation is continuous, the solvent passing without any -loss whatever from one extracting vessel to the other. - -[Illustration: FIG. 39.] - -Alfred Leuner’s apparatus. Fig. 39, works on the Soxhlet principle, -without pressure, using solvent and steam simultaneously. The bones are -placed in _A_ above the perforated false bottom _B_. _D_ is a steampipe -by means of which the bones are steamed as a preliminary, the surplus -steam escaping through the outlet pipe _E_. After steaming, water and -benzine are run in from the reservoir _F_, into the space under the -false bottom, and heated by the steam coil _P_. The vapors evolved -are condensed in the worm _K_, and at first run back over the bones -through the cock _L_, the vapor passing upwards to the worm through -_R_, and the condensed liquid being divided into separate streams by -the spreading plate _O_. After some time the cock _G_ is opened so that -the condensed liquid runs into the reservoir _F_, instead of flowing -back into _A_. When all the solvent has volatilized nothing but water -condenses in the worm, which is known by means of a sampling cock -attached to _A_, the draw-off cock _E_ is then opened and the watery -gelatinous solution and oily matter run off into a suitable separating -receptacle. The bones in _A_ are then discharged through a manhole, and -_A_ being refilled, the whole operation is repeated. - -_Extraction with hydrochloric acid._ If the bones are to be chiefly -worked for glue, extraction with hydrochloric acid, which has been -referred to in Chapter III, under “Bones and Cartilages” may be -highly recommended, the bones being thereby freed from their mineral -constituents and the glue-yielding substance remaining behind in a -pure state. The bones are allowed to remain in contact with the acid -till they are flexible and translucent. This may be readily recognized -by laying upon the material in the vat a bone split in two. When the -latter by the treatment with acid shows the characteristic appearance -of swollen cartilage, _i. e._, has become translucent, extraction may -be considered complete. - -The solution is then drawn off through a tap immediately above -the bottom of the vat into stoneware vessels, and conveyed to the -evaporating pans. The tap is then closed and enough water to cover the -cartilage is admitted into the vat, and the whole allowed to stand for -a few hours in order to extract as much as possible the solution of -bone-salts remaining in the cartilage. The fluid is then drawn off. It -is a quite concentrated solution of bone-salts and, mixed with an equal -volume of hydrochloric acid, may be used for the extraction of fresh -quantities of bones, or be mixed with the fluid first drawn off and -evaporated. - -The further washing of the cartilage is effected by repeatedly pouring -water over it, the operation being continued until the water running -off shows no acid reaction. Washing has to be done very carefully, -since glue-solution obtained from cartilage containing but a very small -quantity of acid will not congeal. It is, therefore, advisable to add -to the last wash-water 1 per cent. of soda, this quantity being quite -sufficient for the neutralization of the last traces of acid. - -_Sulphurous acid process._ In this country sulphurous acid is largely -employed in the manufacture of glue derived from bones. When ordinary -bones are treated with a current of moist sulphurous acid gas, they -absorb from 10 to 12 per cent. of their weight of the gas in the -course of 12 hours. The amount may increase to 15 or 20 per cent. -on longer treatment, but the excess will then disappear on exposure -to air. Messrs. Grillo and Schroeder of Düsseldorf, who patented -this process in 1894, believe that this is simply due to the calcium -phosphate present in the bones, and remark that an absorption of 11 to -12 per cent. on the gross weight amounts to 16 or 17 per cent. of the -inorganic constituents, and corresponds to the equation: - - Ca_{3}(PO_{4})_{2} + SO_{2} + H_{2}O = 2CaHPO_{4} + CaSO_{3}, - -the sulphurous acid simply acting in the same way as sulphuric acid -does in the manufacture of superphosphate, but being a milder acid -than sulphuric, the alteration of the organic constituents which are -available for glue-stock can be almost entirely avoided. The acid -phosphate is soluble in water, therefore the bones after treatment are -easily disintegrated by boiling water when a large portion of the lime -remains in the sediment, while the gelatine is dissolved. - -The process as commercially conducted is very similar to the well-known -sulphite method of treating paper pulp, and is carried on in iron -cylinders or better in close wooden vats lined with lead. - -[Illustration: FIG. 40.] - -The gas is usually generated in an impure form, with a large admixture -of air and carbonic acid, by combustion of pyrites and coal, of crude -sulphur, or even of only highly pyritous fuel. - -On the other hand, since it is well established that the absorption of -a diluted gas is less ready, and is more wasteful than that of a gas in -a pure state, the employment of a definite quantity of sulphur dioxide -in a concentrated state, either prepared by the regulated burning of -sulphur, or the decomposition of sulphuric acid, yields more regular -results, and a product of better quality. Liquid sulphur dioxide, -which is now obtainable at a moderate price and in quantity, has the -advantage that it yields a continuous current of pure gas of any -required rapidity by simply opening a valve, and that the exact amount -used can be ascertained by taring the containing vessel before and -after the operation (S. Rideall). - -The washed bones are brought into the above-mentioned cylinder or vat -and treated with a saturated solution of sulphurous acid. The duration -of the action of the acid varies according to the condition of the -material and can only be determined by experience. The result of the -process is a liquor almost as clear as water, which, after evaporation -in the vacuum pan, is equal as regards clearness and lustre, to the -best quality of glue prepared from waste of hide and skin. The fat -extracted from the bleached bones is lighter in color and has not the -disagreeable odor of ordinary bone fat, and consequently brings a -better price. - -For the generation of sulphurous acid Dr. Bruno Terne, of Mass., has -constructed a very simple apparatus shown in Fig. 40. The sulphur is -burned in _S_; _A_ is the escape pipe of stone; _T_, the collecting -reservoir; _P_, the steam-pump for acid; _R_, chimney for the sulphur -burner. - - -4. CONVERSION OF CARTILAGE INTO GLUE. - -The conversion into glue of the swollen cartilage obtained by treatment -with hydrochloric or sulphurous acid may be effected by continued -boiling in open pans or in an apparatus recommended by Wm. Friedberg, -and shown in Fig. 41. - -The boiler _K_ of thick boiler-plate has a diameter equal to its -height. Underneath the perforated false bottom _S_, which serves for -the support of the bones, lies a perforated steam coil _R—D_ for the -introduction of steam. To this steam coil is fitted a branch-pipe -_d_, which reaches into the upper portion of the boiler into which -also enters the water-pipe _W_. The apparatus is further fitted -with a water-gauge, an air cock, sampling cock and manhole for the -introduction of the cartilage. - -[Illustration: FIG. 41.] - -The mode of operation with this apparatus is as follows: The boiler is -filled three-quarters full with cartilage. Enough water to fill the -boiler one-quarter full is then admitted through the pipe _W_, and -the steam-cock _D_ opened. The steam passing out through the numerous -perforations in the coil _R_, is at first condensed in the water, but -soon brings the latter to the boiling-point, and from this stage on -begins the formation of glue. The glue dissolves in the water, and -a sample of the solution is from time to time drawn off through the -sampling cock and tested as to its concentration. When the solution -possesses the required concentration, the admission of steam through -_R_ is interrupted, and the cock _d_ of the branch-pipe opened, as -well as the cock of the discharge pipe _H_, the latter being opened -gradually. The discharge pipe _H_ is connected with the perforated -plate _F_, which is covered with a closely-woven cloth and thus acts -as a filter, retaining all the solid particles suspended in the glue -solution. - -By opening the cock _d_ of the branch-pipe, the steam-pressure acts -only upon the surface of the fluid, the latter being consequently -pressed with great force through the filter-cloth. - -When the hissing noise caused by escaping steam indicates that all the -fluid has been removed from the boiler, the cock _d_ of the branch-pipe -is closed, and through a rose fitted above the boiler, water is allowed -to flow upon the latter. By this cooling the greater portion of the -steam in the boiler is condensed and water may be admitted through _W_. - -[Illustration: FIG. 42.] - -The operation of glue-boiling is then commenced anew by admitting -steam into the steam coil, and continued until the cartilaginous mass -has been reduced to about one-third of its original bulk, when the -apparatus is opened, fresh material introduced, and the whole operation -repeated. - -In order to be able to replace the filter without having to empty -the entire apparatus, it has been given the shape shown in Fig. 42. -The upper portion of the discharge-pipe _A_ is connected with the -lower portion by the box-screw _H_. In the latter is inserted a short -cylinder, _C_, with a perforated bottom upon which is placed the -filter-cloth; the latter is kept in position by the ring _R_. - -[Illustration: FIG. 43.] - -For every apparatus two of the above-described filters will be -required. If, notwithstanding a full steam pressure, the glue solution -runs off sluggishly, it is indicative of the pores of the filter being -choked up. The screw-box _H_ is then removed, the filter taken out and -replaced by another one. - -The glue solution discharged from the apparatus is in most cases -sufficiently clear to allow of its being immediately evaporated. -However, for the production of a particularly fine quality of glue, -it is advisable to clarify the solution by settling. As the liquor -has to be kept warm to allow of the solid particles to settle, W. -Friedberg recommends the use of the apparatus shown in Fig. 43. It -consists of an iron cylinder with a diameter equal to one-third of its -height. The front of the cylinder is furnished with a number of cocks -placed at equal distances from each other, and also with a pipe in -the slightly conical bottom. It is surrounded by a wooden jacket, the -intermediate space being filled with a bad conductor of heat. By this -arrangement the liquor is kept warm and in a liquid state for several -hours, giving ample time for the solid bodies held in suspension to -settle on the bottom. The condition of the liquor is from time to time -tested by allowing a small quantity of it to run into a glass from the -lowest cock in front. If the sample is perfectly clear, the liquor -may be drawn off. If, however, after several hours’ standing only the -upper portions of the liquor are clear, while the lower ones are still -turbid, further clarification by this means is impossible. The upper -portions of the liquor are then used for finer qualities of glue and -the lower ones for inferior grades. - -By treating the cartilage with high-pressure steam, a liquor is -obtained which on cooling congeals to quite a solid jelly, and it might -be immediately brought into the forming-boxes, cut into cakes, and -dried. However, as the drying of the glue is one of the most difficult -operations for the glue-maker, it is of great advantage to obtain the -liquor in as high a state of concentration as possible in order to -obtain a solid jelly, which causes the least difficulty in drying. For -this purpose the liquors leaving the clarifying vat with a strength of -about 20 per cent. dry glue are evaporated down to a strength of about -32 per cent. in winter, and 35 per cent. in summer. Evaporation may be -effected in open pans or in vacuum. - -Fig. 44 shows the arrangement of an open evaporating pan. The copper -pan _P_ has the form of a shallow cylinder with a slightly conical -bottom, in the lowest point of which is the discharge pipe for the -concentrated liquor. During the operation the discharge pipe is closed -by the ball-valve _V_, which can be raised by the lever contrivance -_M_. The pan is surrounded by an iron steam-jacket; the steam passes in -at _D_, and the condensed water runs off at _A_. _H_ is a sampling cock -for taking samples to test the concentration of the liquor. - -[Illustration: FIG. 44.] - -To prevent the workroom from being filled with steam arising from the -pan, the latter is covered with a hood of wood which terminates in the -pipe _S_ projecting above the roof, and a narrow pipe _R_ branching off -from the steam pipe _D_ passes into _S_. - -When vapors commence to arise from the liquor, the cock on the pipe _R_ -is slightly opened whereby a jet of steam is blown into the pipe _S_, -the latter then acting as an exhauster, and the vapors in the hood _C_ -are carried along by the jet of steam. By this arrangement no vapor -passes into the workroom and steam is also very rapidly evolved from -the surface of the liquor. - -Sufficient steam should be admitted to the pan for the liquor to give -out an abundance of vapor without, however, being brought to the -boiling-point, as in that case foam would be formed and the liquor in -cooling yield a product full of blisters. When the liquor has acquired -the proper degree of concentration, the admission of steam to _D_ and -_R_ is interrupted and the valve _V_ having been raised the liquor is -run into the cooling-boxes. The latter are of wood lined with zinc, or -better of stout zinc or heavily galvanized iron. They hold about ½ cwt. -and are of two shapes: one deep and nearly square, another long and -shallow, for quick cooling of clear liquors. Iron should not be used, -as it readily rusts and causes discoloration of the glue. - -Cooling is effected by cold water where it is available, but often -merely by cold air, aided by fans or blowers, in a room protected from -heat or frost. According to S. Rideal, refrigerating machines are now -also employed, which, by the evaporation of liquid gases, such as -ammonia, sulphurous or carbonic acid, reduce a tank of brine to near -freezing-point. The temperature should not be allowed below 33° or 34° -F., for if frozen the jelly is hard and difficult to cut. The brine -circulates in iron pipes placed near the ceiling of the room; they must -be kept as clear as possible of ice and dirt, and the cooling house -should be scrupulously clean and sweet. - -Spiral evaporators are recommended by Thomas Lambert as forming a ready -and economical means of evaporation. The evaporator consists of a -spiral steam coil, made of copper, and 2 inches in diameter, revolving -on a centre shaft; the lower half of the coil is covered with the -glue-liquor in the trough. The shaft rests on two plummer-blocks, one -receiving the steam, and the other discharging the spent steam and -condensed water. The shaft is hollow to the first coil, and the steam -is thus conveyed to the spiral. From the last coil to the end of the -plummer-block the shaft is also hollow, and in that portion resting on -the block two openings are made. In the inside of the plummer-block, -two openings are bored to the outside, each forming a covered channel; -as the shaft revolves, all the holes directly face each other at -intervals, and thus allow any condensed water in the coils to be blown -through. From 25 to 28 coils are generally used in each spiral. The -glue-liquors are fed into the trough at one end, and have a temperature -of 75° F.; the temperature of the evaporated liquor is 85° F. In the -rather slow passage through the trough, the liquors receiving the heat -of the revolving coils are raised in strength from 20 per cent. to 32 -per cent. dry glue, at which point they are ready for jellying. - -_Vacuum pans_ are much used in this country for evaporating -glue-liquors, though there are some complaints made of the great waste -owing to spray and froth being carried off in the steam. As is well -known the boiling-point is lowered by increasing the pressure on the -surface of a fluid. By enclosing water in a vessel connected with a -constantly working air-pump, it is brought to the boiling-point by -heating to between 95° and 104° F. The construction of vacuum pans is -based upon this principle, and such apparatus is largely used in many -manufacturing processes for evaporating to a certain degree fluids, for -instance, sugar solutions, which readily become decomposed at a higher -temperature. Vacuum pans are also very suitable for the evaporation of -glue-solution, especially in plants working on a large scale. - -Fig. 45 represents an elevation of a vacuum pan for evaporating glue -and gelatine liquors as described by Thomas Lambert. The pan is built -of steel plates, and lined outside with wood work, and rests on a -floor constructed of rolled steel plates, supported on four columns, -with a stairway leading to the working platform. One half of the -lower part is shown in section, giving a view of the coils by which -the pan is heated. The various parts are as follows: _A_, the body of -the pan; _B_, the dome; _C_, exhaust pipe leading from the dome to -the condenser; _D_, condenser; _E_, air or vacuum pump; _F_, storage -tank for glue or gelatine liquors, warmed with steam coil; _G_, supply -pipe leading from storage tank to vacuum pan; _H_, discharge valve; -_I_, barometer gauge for indicating vacuum; _J_, inlet steam pipe -for supplying the coils; _K_, exhaust end of vacuum coils; _L_, iron -staircase; _M_, steel floor. - -[Illustration: FIG. 45.] - -The accessories to the pan are placed in a convenient position above -the working floor and include a steam gauge for noting the pressure in -the coils, a gauge for indicating the height of the liquor in the pan, -vacuum gauge _I_, as shown in the drawing, air-cocks and a thermometer. -The pan is also fitted with a small apparatus, by which portions of the -boiling liquor can from time to time be drawn, without disarranging the -vacuum, so that the progress of evaporation can be ascertained. - -In working the pan, the storage tank _F_ is first filled with the weak -glue liquors to be evaporated; the valve on the supply pipe _G_ is then -closed, and the vacuum pump set in motion; a few strokes are sufficient -to reduce the internal pressure, and the valve of the supply pipe is -then opened, and the liquor allowed to fill up the pan to the desired -mark on the gauge. The valve is then closed, the steam-inlet valve _J_, -supplying the coils, opened. As the heat from the coils spreads through -the liquor, the vacuum pump is kept steadily at work reducing the -inside pressure to within 2 to 2½ inches of a perfect vacuum, as seen -on the barometrical scale. In this vacuum the liquor will boil at 120° -to 130° F., and the boiling is continued until the withdrawn samples, -as tested by the glue-meter, show the desired strength. The pump is -then stopped, the vacuum broken by opening the air-cocks, and the -concentrated liquor is run through the valve _H_ into suitably arranged -receiving tanks, for supplying the trays or glasses for jellying. - -For economical working with large quantities of weak liquors, a -combination of two, three and even four vacuum pans, forming the -double, triple and quadruple effect evaporators, have been designed -for concentration purposes. The triple effect is, however, the system -mostly in use, and consists of a grouping of three cylindrical pans, -each connected by suitably arranged piping, by which the vapors of the -first pan are conveyed to and made to heat the coils of a second pan, -the resulting vapors from the second, passing on to the third pan, for -a similar purpose. All the pans are connected with powerful pumps, -producing a nearly absolute vacuum in each. The liquor is evaporated to -a given density in the first pan, and then passed on to the second, and -ultimately to the third, at which stage 80 per cent. of its water will -have been driven off. - -To obtain in all cases a product of equal concentration, it is -advisable to have an instrument which will indicate the amount of dry -glue in the solution. (Fig. 46.) - -By immersing a glass aerometer in the glue-liquor, the percentage of -glue is indicated by a scale registering from 0 to 70 per cent. with -the jelly or glue solution at a temperature of 167° F. - -To measure the temperature quickly, a thermometer is added, and for -the execution of the entire test, a sheet-iron vessel consisting of -a large and two small tubes, _a_, which when not in use, serve for -the reception of the glass instruments contained in a special case. -For testing, the small cylinder is placed in the large tube, _a_, and -filled with jelly by means of the cap which serves as a cover. The -large tube is filled with hot water to bring the jelly to the required -temperature. The two instruments are then immersed in the tubes filled -with glue-liquors to be tested, and temperature as well as percentage -can be readily read off. - -[Illustration: FIG. 46.] - -The evaporated and cooled glue-liquor is cut into cakes and dried in -the same manner as previously described. - - -5. PROCESS FOR THE SIMULTANEOUS UTILIZATION OF BONES FOR FAT, BONE-MEAL -AND GLUE. - -Manufacturers frequently sort the bones in such a way that materials of -different quality are obtained. Thick, compact bones are utilized for -the manufacture of animal charcoal, a comparatively small percentage -of bone-meal resulting in crushing such bones. - -Incompact, porous bones, on the other hand, yield not only crummy -animal charcoal of less value, but in stamping also a larger percentage -of bone-meal than compact bones. Hence they are as a rule directly -worked for fat, glue and steamed bone-meal, no attempt being made -to convert them into such granular pieces as are suitable for the -production of charcoal. - -For this purpose, the bones are first broken by a crusher or mill into -coarse pieces, and the fat extracted by a special process or together -with the glue in one operation. The latter method would seem to be the -most suitable, time and labor being thereby saved, but it must be borne -in mind that fat extracted by itself brings a much better price than -that obtained by steaming, and besides the yield of glue is larger from -steamed bones which have been previously degreased. - -The crushed bones—whether degreased or not—are subjected to the action -of high-pressure steam. The apparatus, Fig. 47, used for this purpose -consists of a cylinder of thick boiler-plate, 10 to 13 feet high and 3 -to 4 feet in diameter. _E_ and _A_ are manholes, which can be closed -steam-tight. The pipe _D_ leads to the steam-boiler and opposite to -_D_ is a short pipe, _H_. The cylinder is further fitted with the -perforated false bottom, _S_, and the bent pipe, _L_. - -As a rule, four to six, and in larger plants even more, of such -cylinders are combined to a battery. In this case the discharge pipe, -_L_, terminates in a common collecting vessel, and the steam-pipes, -_D_, branch off from a main steampipe. The battery may be enclosed by -brickwork, but is preferably placed upon a suitable foundation and -surrounded by woodwork, the intermediate space between woodwork and -cylinders being filled with sawdust. This plan offers the best means of -keeping the heat together, and the further advantage that, in case one -of the cylinders becomes defective, it can be readily taken out and -replaced by a new one. - -[Illustration: FIG. 47.] - -In order to be able to fill the cylinders rapidly and with the least -expenditure of power, it is advisable to place the bone-crusher at such -a height that the crushed bones fall directly into carriages which are -run upon a small railway over the charging holes of the cylinders, and -emptied. In front of the manholes, _A_, for discharging the bones is -also a railway, so that the crushed bones can be directly emptied into -carriages and conveyed to the stamping mill. - -The cylinder having been filled with bones, is closed steam-tight. The -cock, _H_, is then opened and steam admitted by opening the cock _D_. -The steam passing in at first, is cooled off by coming in contact -with the bones and condensed to water. However, the temperature in the -cylinder soon becomes so high that the steam is no longer condensed -and, having first expelled the air in the cylinder through the pipe -_H_, it escapes through the latter in the form of a powerful jet. When -this is the case _H_ is closed and high-pressure steam allowed to act -upon the bones. - -The fat contained in the bones melts and trickles down. On the bottom -of the cylinder collects a fluid which contains glue, is of a milky -turbidity due to admixed drops of fat, and with a quite thick layer of -fat upon its surface. From time to time—about every hour—the cock _L_ -is slightly opened. By the pressure of the steam the glue-liquor is -expelled with great force through the pipe _L_, the latter being closed -when by the peculiar noise it is noticed that only steam escapes. - -Steaming and the occasional discharge of melted fat are continued until -on testing a sample of the liquor running off, it is noticed to be free -from fat. The liquor in the cylinder is then expelled by the pressure -of steam, the steam-cock _D_ closed, the manhole _A_ opened, and steam -again admitted through _D_. By the steam-pressure the greater portion -of the bones in the cylinder is expelled through the manhole _A_. The -bones coming from the cylinder are pliable and soft, and, after drying, -are readily converted by grinding into bone-meal. - -For the manufacture of animal charcoal it is of the utmost importance -that steaming should be interrupted at the time when the bones are -completely degreased. If, however, only fat, glue and bone-meal are to -be produced, steaming may advantageously be continued for a longer time. - -The longer the bones are subjected to the action of high-pressure -steam, the more complete the conversion of glue-yielding substance into -glue will be. To be sure, the bone-meal obtained from such bones will -contain somewhat less nitrogen than the product from bones not steamed -quite so long. However, the content of phosphates will in both cases be -the same, and on this depends, in the main, the fertilizing value of -bone-meal. - -The fluid discharged from the cylinder consists of a mixture of -glue-liquor and drops of fat. It is run into a large vat, in which it -is kept warm for a few hours, when the fat rises and collects in a -coherent mass on the surface. The fat is then drawn off through cocks -in the upper portion of the vat, while the glue-liquor is discharged -from the bottom of the vat, running first upon a very fine meshed -sieve, which retains the coarser bodies held in suspension, and then -directly into the evaporator. In the latter the liquor is evaporated -to the desired strength, when it is run into the clarifying vats, and -finally into the cooling vessels. - -With the above-described process, the simultaneous utilization of the -bones for animal charcoal is only possible if the crushed steamed bones -are passed through a sieve for the purpose of sorting out the granular -pieces of suitable size. However, in the process above described, -incompact bones are, as a rule, used which give but a small percentage -of granulated pieces, and the latter yield an inferior quality of -animal charcoal. It is therefore best to use the steamed bones from -which the fat and glue have been extracted for the production of -bone-meal. - -For the manufacture of animal charcoal, the bones have to be carefully -sorted, fresh bones rich in organic substance being best for the -purpose, and the hardest and thickest pieces should be selected. -Previous to carbonization, the bones are degreased by extraction with -benzine or carbon disulphide, and then crushed. - -Carbonization was formerly effected in iron pots having a capacity of -about 25 quarts each. However, by this process a uniform product of -good quality cannot be obtained, and, besides, the total quantity of -organic substance of the bones is lost. At present carbonization is -effected in retorts, whereby large quantities of animal charcoal are -in a comparatively short time obtained, and, besides, the products -of destructive distillation can be completely utilized. An essential -product of distillation is a large quantity of inflammable gases, which -can be used for heating the retort-furnace or for illuminating the -entire plant, it being, however, best to arrange the conduits so that -the gases can be used for either purpose. - -A detailed discussion of the methods for gaining and further working -of the products of distillation is not within the scope of this work, -and only a brief description of a plant for the manufacture of animal -charcoal will here be given. - -[Illustration: FIG. 48.] - -Figs. 48 and 49 show the arrangement of a Belgian retort-furnace, Fig. -48 representing a vertical section lengthways, and Fig. 49 a horizontal -section. The illustrations, however, are given at different heights in -order to show plainly the arrangement of the fire-place and the passage -of the fire-gases. - -The cast-iron retorts—sixteen in the apparatus shown—are placed in -rows alongside and one after another, so as to be swept as uniformly -as possible by the fire. As will be seen from Fig. 49 the firing is so -arranged that only the upper portions of the retorts are touched by the -flames. _B_ is the actual fire-place, and _A_ the ash-pit, both being -furnished with closely fitting doors so that the fire may be properly -regulated, and the retorts eventually be exclusively heated with gas. - -[Illustration: FIG. 49.] - -The retorts are cylindrical in form, with one end closed. At the open -end is fixed the frame or mouth-piece, which carries the door swung on -a hinge. The door has a slight projecting rim, some two inches wide, -which, with the surface of the frame, is ground perfectly true; on -closing, the joint is made gas-tight by a lever arrangement. - -The fire-gases escaping from _B_ are distributed as uniformly as -possible by the flues, _a_, carried underneath the pans, _E_, and -finally pass out in the direction of the arrows through a chimney. - -At the time when the extraction of fat was exclusively effected by -boiling the bones, the pans _E_ served for this purpose, and the spaces -_D_, _D__{1}, _D__{2}, etc., alongside the pans, which were also heated -by the fire-gases, were used for drying the bones. However, at present, -the extraction of fat is, as a rule, effected by means of benzine or -carbon disulphide, and it is advisable to replace the pans, _E_, by a -bonekiln, and eventually to utilize any waste heat for heating the -evaporators for glue-liquor. - -Fixed to the upper portion of each retort is a pipe, and these pipes -lead into a very wide iron-pipe, _T_. The products of destructive -distillation escaping from the retorts combine in _T_, and besides -having a very large diameter, this pipe must be considerably inclined -to avoid the accumulation of products of distillation in it. To prevent -the products of distillation from depositing in a crystalline form in -_T_, the latter is covered with a bad conductor of heat. - -The pipe _T_ is connected with a series of condensing vessels, _D_, -another series of vessels being placed alongside the first one, so that -the vapors may be conducted, as desired, into either one of them. Two -batteries of such condensing vessels are required, as one of them has -from time to time to be disengaged in order to be cleansed. - -If the products of distillation would have to overcome the entire -pressure of the column of fluid in the condensing vessels, their escape -from the retorts would be very much retarded. To avoid this, plates are -arranged horizontally a few inches below the level of the fluid, and -the pipes dip into the condensing vessels only far enough to permit the -escaping vapors to pass under these plates. By this arrangement, the -vapors sweep under the plates and are absorbed by the fluids, a strong -pressure in the apparatus being thus avoided. - -The condensing batteries may of course consist of any number of -vessels, but as a rule only a sufficient number to retain all the -ammonia is employed, five being in most cases sufficient for this -purpose. The last condenser is connected with an exhaust-pump, _p p_, -which is kept in motion by a motor, _P_. - -The pump removes all the bodies remaining in the last condenser and -forces them, according to the position of the cock back of the pump, -either into a glass-bell or through the pipe _H_ and the nozzles _a_ -into the fire-place where they are burned. - -To obtain the various products of distillation, the condensing vessels -have to be filled with acid, and should therefore be constructed of -lead or at least of sheet-iron lined with lead. The products to be -obtained depend on the fluid used for filling the vessels; if filled -with dilute sulphuric acid, ammonium sulphate is obtained, which may -be utilized in the preparation of fertilizers. If hydrochloric acid is -employed for the absorption of ammonia, solution of ammonium chloride -is obtained, which may be crystallized by evaporation. - -The products evolved in the destructive distillation of bones consist -of various hydrocarbons and appear either as badly-smelling brown -liquors—bone-tar—or as illuminating gas. The vapors contain further -considerable quantities of ammonium carbonate and cyanide of ammonium. -To obtain the latter, the last condensing vessel is filled with green -vitriol solution, the cyanogen compounds remaining behind in the -solution. If the gas escaping from the last condenser is to be used for -illuminating purposes, it is freed from the greater portion of carbonic -acid contained in it by purification with lime. - -The mode of operation with Belgian retort furnaces is as follows: -The retorts having been filled with comminuted degreased bones, the -doors are closed perfectly gas-tight and firing is commenced. The pump -is set in motion until a jet of gas blows through the nozzles. When -this gas-jet burns with a luminous flame, destructive distillation of -the bones is in full blast. The pump is then run with such velocity -that the pressure in the interior of the retorts, as indicated by the -manometer, is slightly greater than the external air-pressure, and the -operation is thus continued so long as inflammable gases escape from -the pipe _H_. The pump is then stopped, and one-half of the charcoal -contained in the retorts is withdrawn to the canisters placed ready to -receive it. The lids of the canisters are then luted down with a paste -of char-dust and water, making an air-tight joint, and the charcoal is -allowed to cool. - -The retorts having been partially emptied, are at once refilled to the -brim with crushed bones and closed gas-tight. There is but little or no -loss of heat between withdrawing and charging, and distillation of the -freshly-introduced bones commences immediately after charging, and is -finished in a much shorter time than in the beginning of the operation. - -In making animal charcoal on a large scale there are obtained from 2000 -lbs. of raw material: - - Animal charcoal, 1180 to 1220 lbs. - Ammoniacal liquor, 178 to 180 lbs. - Gas, 222 to 248 cubic yards. - -However, these figures refer only to bones degreased by steaming, -whereby a considerable portion of the cartilaginous substance passes -into solution in the form of glue. In working bones degreased with -benzine, larger yields than those indicated above are as a rule -obtained. The ammoniacal liquor contains on an average 10 per cent. of -ammonia. The gas freed from carbonic acid yields 2.7 times more light -than good coal-gas. - - -6. PROCESS FOR THE SIMULTANEOUS UTILIZATION OF THE BONES FOR FAT, GLUE -AND CALCIUM PHOSPHATE. - -This process differs from the one previously described in that, in -addition to the total quantity of fat and glue-yielding substance -contained in the bones, the mineral salts are also obtained in a pure -state, and can be further utilized. - -The bones are degreased either by extraction with benzine or carbon -disulphide or steaming, the operation in the latter case being -continued so long as fat is yielded by the bones. The resulting -glue-liquor is used in place of water for boiling the cartilage. - -The bones are placed in large wooden vats furnished with well-fitting -lids, and hydrochloric acid of 12 per cent. poured over them so that -they are covered a few inches deep. With the use of acid of 1.04 -specific gravity the greater portion of the salts contained in the -bones will pass into solution in 48 to 72 hours, when the solution is -drawn off as completely as possible from the vats. - -The residue in the vats is treated with less concentrated hydrochloric -acid and left in contact with it until the bones are soft and flexible -and the thinner pieces have become translucent, this being a proof -that all the mineral salts have been extracted, and nothing but pure -cartilaginous substance remains behind. The solution is then drawn off, -and after pouring repeatedly small quantities of pure water over the -cartilage to expel the last remnants of acid liquor, it is subjected to -thorough washing until the last traces of acid have been removed. - -The resulting cartilage is white, translucent, and water-soaked. If -left in this state it would of course soon putrefy, and it is best to -work it at once, or if this cannot be done it will have to be treated -with carbolic acid in the manner previously described, or dried. - -Drying the cartilage is time-consuming work, and can properly be done -only by artificial heat in kilns. If carefully protected from moisture, -thoroughly dried cartilage may be kept without injury for any length -of time. However, before being worked to glue, such material has to -be again soaked in water previous to the actual boiling operation, -and this process requires considerable time. It is therefore best to -preserve it in carbolic acid solution, which only needs to be drawn off -when the cartilage is to be worked, and may be further utilized. - -If boiled in open vessels with water, 6 to 8 hours are required for -the complete disintegration of the cartilage. In a closed apparatus -under high pressure solution is effected in a much shorter time and the -operation progresses very smoothly. With proper attention the glue -obtained from bones degreased with benzine and freed from bone-earth by -extraction with hydrochloric acid is, as a rule, very clear, and may be -bleached with sulphurous acid. - -The extraction of the phosphates from bones may be effected in a very -suitable manner as follows: A number of vats filled with bones are -placed in terraces one above the other, and the acid is allowed to -run first into the uppermost vat. After having been for several hours -in contact with the bones it is discharged into the next vat, fresh -acid being run into the first one, and so on. By this process a highly -concentrated solution of phosphates is in a few hours obtained in the -lowest vat, solution still adhering to the bones in the other vats -being finally expelled by water. - -However, the process of extraction under decreased pressure is the -most advantageous, it requiring least time. For this purpose the bones -are brought into a vessel which can be closed air-tight and the air -is expelled. When but a slight air-pressure prevails in the vessel, -the cock of a reservoir filled with hydrochloric acid is opened, the -external air-pressure now forcing hydrochloric acid into the extracting -vessel. - -Bones, as viewed under the microscope, consist of a mass permeated -with numerous minute tubes or pores. When the air is expelled from -the vessel containing the bones, the air in the pores of the latter -is rarefied and the hollow spaces are filled with hydrochloric acid -whereby solution of the phosphates is effected. - -The yield of glue obtained from cartilage after extraction of the -mineral constituents varies according to the compactness of the bones -used. Solid and compact bones yield, on an average, 15 per cent. of -dry glue, but a comparatively large quantity of calcium phosphate. On -the other hand, porous bones rich in cartilage yield from 20 to 25 per -cent. of dry glue. The liquor obtained by treating the bones contains, -as previously mentioned, calcium phosphate, magnesium phosphate and -calcium chloride in solution, and may be utilized in the manufacture of -fertilizers or of phosphorus. - -For the first purpose which is not very remunerative, but is not -very troublesome, the liquor is treated with milk of lime until it -is slightly alkaline, whereby a finely divided precipitate of basic -calcium phosphate is obtained, whilst calcium chloride remains in -solution. The precipitate is allowed to settle, separated from the -supernatant fluid and dried. The resulting product contains, on an -average, 65 per cent. calcium phosphate, up to 20 per cent. water -and 10 to 15 per cent. calcium carbonate, quick lime and accidental -impurities. It forms an excellent fertilizer. - -If the liquor is to be utilized in the manufacture of phosphorus, it -is evaporated in shallow pans of glazed stoneware. In cooling crystals -of acid calcium phosphate are formed, which are separated from the -mother-liquor. This subject will be more fully referred to in the next -chapter. - - - - -CHAPTER VI. - -MANUFACTURE OF PHOSPHORUS. - - -In some instances the preparation of phosphorus is carried on in -conjunction with other industries, for instance, glue-boiling, the -preparation of sal ammoniac, yellow prussiate of potash, etc. Bone-ash -is the chief material used by phosphorus makers. Many manufacturers do -not burn the bones to ashes, but purchase bone-ash, large quantities -of which are brought from South America, especially from the Argentine -Republic. - -The ordinary method of preparing phosphorus includes the following -operations: - -1. Burning the bones and grinding the bone-ash to powder. - -2. Decomposition of the bone-ash by sulphuric acid, and evaporation of -the acid phosphate previously mixed with charcoal. - -3. The distillation of the phosphorus. - -4. The refining and purifying the phosphorus. - -_Burning the bones to ash._ The object of the ignition of the bones -is the complete destruction of the organic matter. The operation is -conducted in a kiln very similar to those in use for burning lime. -A layer of brush-wood having been put on the bottom of the kiln, -bones form the next stratum, and so on alternately. The wood having -been lighted, the combustion of the bones ensues. In order to carry -off the fumes, the smell of which is very offensive, a hood made of -boiler-plate is placed on the kiln, and either connected with a tall -chimney, or the smoke and gases are conducted into the fire of the -kiln and burnt. The white burnt bones are withdrawn through an opening -reserved in the wall on purpose, the kiln being kept continuously in -operation, as in the case with some lime kilns. - -This kind of kiln, however, possesses many disadvantages, and an -improved form, as proposed by Fleck, is shown in Fig. 50. - -[Illustration: FIG. 50.] - -The actual combustion chamber consists of a shaft, _A_, composed of -two inverted cones. In the lowest portion of the lower cone are four -or six apertures, _b_, which terminate in inclined channels and serve -as air-flues, as well as for withdrawing the burnt bones. Through the -aperture _a_ in the upper portion of the shaft additional bones may be -introduced. This aperture is covered with a heavy iron lid. - -As will be seen from the illustration, the shaft contracts towards the -top in the form of a retort and passes into a horizontal channel _B_ -which is provided, near its beginning, with an ordinary fire-place _d_. -The gases and fumes escaping from the burning bones must pass over the -flame of the fire-place _d_, and are thereby so completely consumed to -water, carbonic acid and free nitrogen that no odor is perceptible even -in the immediate neighborhood of the kiln. - -In order not to lose the heat yielded by the fire-place _d_ and the -burning vapors, the channel _B_ is covered with shallow pans _P_, -for the evaporation of such fluids as have to be subjected to this -treatment in the factory. - -The mode of operation with a kiln of this construction is as follows: -The shaft is filled two-thirds full with bones and dry wood split in -small pieces is placed in the channels _b_ and simultaneously ignited. -Four or six long hot flames thus strike the bones, the latter becoming -in a short time so highly heated that they commence to burn briskly and -ignite fresh portions of bones introduced through the aperture _a_. - -The white burnt bones in the lower portion of the kiln are withdrawn, -while in a glowing state, by means of iron hooks; the next layer of -bones sinks down and fresh material is introduced through _a_, the kiln -being thus kept continuously in operation. - -The quantity of substance which remains after burning the bones depends -of course on the quality of the material used. Tubular bones of old -animals contain the largest quantity of mineral substance, and give a -much more abundant yield of bone-ash than the spongy bones of younger -animals. On an average 100 parts by weight of fresh bones yield 55 -parts by weight of bone-ash. The composition of the latter is as -follows: - - Basic calcium phosphate, 80 to 84 per cent. - Basic magnesium phosphate, 2 to 3 per cent. - Calcium carbonate, } 10 to 14 per cent. - Calcium fluoride, } - -The bone-ash thus obtained is converted into a coarse powder by means -of machinery, a bone-mill being best suited for the purpose. Experience -has shown that the granules obtained by grinding should be the size of -lentils. With the use of larger pieces the acid, with which the ash is -treated later on, does not penetrate the entire thickness of the bone -mass and a portion of the latter remains undecomposed. If the granules -are too small, lumps are formed when the ash is brought together with -the acid, and the mass would have to be constantly stirred in order to, -make the action of the acid effective. - -_Decomposition of the bone-ash by sulphuric acid._ When the basic -calcium phosphate—the constituent of the bone-ash which comes here into -consideration—is brought in contact with an acid of sufficient strength -to effect its decomposition, calcium sulphate (gypsum) is formed, and -a solution of acid calcium phosphate. If the latter be mixed with -powdered charcoal, evaporated to dryness, and the mixture exposed, with -the exclusion of air, to a strong red heat, the acid calcium phosphate -is first converted into calcium metaphosphate, water being yielded. At -this high temperature the calcium metaphosphate is by the action of the -carbon decomposed to basic calcium phosphate and phosphorus; the latter -escapes in the form of vapor and may be caught in suitable condensing -vessels. - -Hence three separate processes have to be distinguished: 1. The -formation of acid calcium phosphate from the basic calcium phosphate -contained in the bone-ash. 2. The conversion of the acid calcium -phosphate into calcium metaphosphate. 3. Decomposition of the calcium -metaphosphate, phosphorus being liberated, while basic calcium -phosphate remains behind. - -Expressed in chemical symbols these processes may be embodied in the -following equations: - - I. Ca_{3}(PO_{4})_{2} + 2H_{2}SO_{4} = 2CaSO_{4} + CaH_{4}(PO_{4})_{2} - Basic calcium Sulphuric Calcium Acid Calcium - phosphate. acid. sulphate phosphate. - (gypsum). - - II. CaH_{4}(PO_{4})_{2} = 2H_{2}O + Ca(PO_{3})_{2} - Acid calcium Water. Calcium - phosphate. metaphosphate. - - III. 3Ca(PO_{3})_{2} + 10C = 10CO + Ca_{3}(PO_{4})_{2} = P_{4} - Calcium Carbon. Carbon Basic calcium - metaphosphate. monoxide. phosphate. - -If the processes mentioned under II. and III. would pass off in the -practice exactly as there stated, two-thirds, or 13.3 per cent., of -the total quantity of phosphorus contained in the basic calcium -phosphate originally present would be obtained. However, besides these -processes, others take place which cause a loss of phosphorus. By the -action of the red heat upon the acid calcium phosphate, reciprocal -action takes place between the latter, the water and carbon, so that -a portion of the water is decomposed, and in addition to carbon -monoxide, phosphoretted hydrogen is formed; the phosphorus contained -in the latter must be considered as lost. Furthermore, a portion of -the phosphorus is lost in the form of vapor, even with the use of the -best condensing contrivances. In consequence of these losses the actual -yield of phosphorus is between 8 and 11 per cent. - -The formation of acid calcium phosphate may be effected either cold or -with the assistance of heat, less time being required in the latter -case. The process without the assistance of heat is as follows: - -The bone-ash is brought into a lead-lined wooden tank, and enough -boiling water to cover it poured in. It is then thoroughly mixed with -the water by vigorous stirring with wooden rakes, and the necessary -quantity of sulphuric acid is then run in with constant stirring. When -an intimate mixture has been effected, the tank is covered with a -well-fitting lid and allowed to stand for a few hours. As heat has been -liberated by the introduction of the sulphuric acid into the mixture -prepared with hot water, the entire mass acquires a high temperature. - -Decomposition is accelerated by stirring the contents of the tank every -six hours, and the process may be supposed to be finished in 48 hours. -With the use of fresh burnt ash no special phenomena are observed, but -if the ash has been prepared for some time the caustic lime formed in -burning the bones has been completely converted into carbonate of lime, -and the carbonic acid escapes, causing a slight foaming of the mass. -In addition to carbonic acid, there also escapes a certain quantity -of hydrogen fluoride gas, which is liberated by the decomposition of -the calcium fluoride present in the ash. This gas being, even in very -small quantities, very injurious to health, the tanks should be placed -in a thoroughly ventilated room. - -When decomposition is complete, enough water is admitted for the mass -to acquire by stirring a thick milky appearance, when it is allowed to -rest until it clarifies and a perfectly clear solution of acid calcium -phosphate stands over the precipitate of gypsum. The clear solution is -drawn off, and the sediment washed with water to obtain the solution -retained by it. For this purpose the gypsum is stirred up with water, -and the thick fluid discharged into a filtering tank. Upon the bottom -of the latter is a four-inch-deep layer of coarse quartz sand; upon -this is placed a false bottom, and upon the latter is spread a linen -cloth. The liquor first running off being milky is poured back into the -tank. However, it runs off clear so soon as the pores of the filtering -cloth have become somewhat contracted by the gypsum. - -As a rule, the contents of several filtering vats are run into a common -filter, and the mass is repeatedly allowed to drain off. The dilute -solutions thus obtained are evaporated with the first liquor. A third -lixiviation of the sediment yields a fluid which is used instead of -water in a subsequent operation. - -The residue of gypsum is taken from the filtering tanks, and may be -used as a fertilizer. - -In the warm way the decomposition of the bone-ash is effected by -providing the decomposing tanks with lead pipes through which steam is -introduced, decomposition being complete in 24 hours, and the first run -of solution of acid calcium phosphate reaches the evaporating pan in a -very hot state. The lixiviation of the gypsum residue is also effected -with water heated by steam, the object of separating the acid calcium -phosphate as much as possible from the gypsum being thus obtained -more completely with a comparatively small quantity of water than is -possible by washing with cold water. - -A suitable apparatus for hot lixiviation is shown in Figs. 51 and 52 in -cross section and profile. A lead-lined tank, 13 to 16 feet in diameter -and 3½ feet deep, is fitted with a stirrer furnished with two or four -paddles, and closed by a well-fitting lid. The stirrer is kept in -motion during the entire operation. - -[Illustration: FIG. 51.] - -[Illustration: FIG. 52.] - -A lead steam pipe _D_ furnished with several narrow flat outlet -pipes placed in the direction in which the stirrer revolves, lies -about 4 inches above the bottom of the tank. _W_ is the pipe for the -admission of water, _S_ the lead pipe connected with the sulphuric -acid reservoir, and _A_ an outlet of boards for carrying off the vapor -evolved from the mass in admitting the sulphuric acid. _R_ is a wooden -hopper, which serves for the introduction of the bone-ash, and is -removed when the tank has been filled, the aperture being closed with -a well-fitting wooden lid. The bottom of the tank is furnished with a -lead discharge-cock. - -Water is run into the tank, the bone-ash being simultaneously -introduced through the hopper _R_, and the stirrer allowed to revolve -slowly to effect an intimate mixture. Sulphuric acid and steam are then -at the same time admitted. The steam heats the fluid very quickly to -the boiling-point, and assists the action of the stirrer, it passing -out from the outlet pipes in the same direction in which the stirrer -revolves. - -When the required quantity of sulphuric acid has been introduced, -the admission of steam is interrupted, the stirrer, however, being -constantly kept in motion. To keep the mass hot, steam is for a few -minutes admitted every hour. When the sulphuric acid has acted for 24 -hours, decomposition is complete, and the liquor is discharged through -the cock on the bottom of the tank. - -For the evaporation of the liquor leaden pans are used, and this -operation is continued until the fluid has attained a specific gravity -of 1.45. The pans rest upon cast-iron plates covered with a layer of -clay or sand, to prevent them from being injured by the fire gases. For -heating the pans, the fire gases escaping from the distilling furnace -or the bone kiln are utilized. - -The fluid having been evaporated to the above-mentioned specific -gravity is now mixed with charcoal powder, or rather granulated -charcoal of the size of small peas, in the proportion of 20 to 25 parts -of charcoal to 100 of liquor. The mixture is then quickly dried in -shallow cast-iron pans heated by a direct fire. Much sulphurous acid is -evolved during this operation, and provision must be made for carrying -off the vapors arising from the pans. - -When the mass has been dehydrated so far that it balls together, it -is taken from the pan by means of shovels and brought into a copper -cylinder which is furnished with a sheet-iron sieve-like bottom through -which it is forced into another pan. In this second pan the mass is -moderately heated until a sample of it still evolves slight vapors -and when pressed with the hand, after cooling somewhat, appears still -moist without, however, being sticky. The material is now ready for -distilling and 100 parts of concentrated solution of 1.45 specific -gravity and 20 to 25 parts of charcoal yield about 77 parts by weight -of so-called distilling mass. - -It is best to bring the hot mass as taken from the pan at once into -the retorts, as it is very hygroscopic and, if allowed to lie exposed -to the air, would absorb moisture and require to be again dried. If it -cannot be immediately subjected to distillation, it is advisable to -keep it in sheet-metal boxes tightly closed. - -The liquor obtained in treating bones for the manufacture of glue with -hydrochloric acid may, as mentioned in Chapter V, be advantageously -utilized in the manufacture of phosphorus. In order to obtain in -crystallized form the acid calcium phosphate contained in it, the -liquor has to be concentrated by evaporation and as during this -operation hydrochloric acid vapors constantly escape, provision must be -made for their removal from the workroom. The operation is conducted -as follows: The flue of the furnace for distilling the phosphorus, -through which the fire gases usually escape to the chimney, is made to -communicate with a long low chamber, which can be tightly closed and -connects at the other end with a high chimney. The flue is fitted with -a slide and by opening the latter, the fire gases are forced to pass -through the chamber before reaching the chimney. - -In the chamber are placed large, well-glazed, earthenware vessels which -contain the liquor to be evaporated, the vapors evolved being carried -off by the fire-gases through the chimney. Evaporation proceeds quite -rapidly, and fresh liquor is from time to time introduced through an -earthenware pipe, the operation being repeated until a sample taken -from the full vessels shows on cooling the presence of an abundance of -crystals of acid calcium phosphate. - -The admission of the fire-gases into the chamber is then interrupted, -and the contents of the vessels are brought into a wooden tank -furnished with a stirrer, which is kept in constant motion so that -when the liquor cools, only small crystals will be formed. When -crystallization is complete, the mother-liquor is drawn off and again -evaporated. By this operation more crystals of acid calcium phosphate -are obtained, which are, however, less pure than those from the first -liquor. The mother-liquor drawn off from this second yield of crystals -might, on being again evaporated, give more crystals which, however, -would be too impure to be used to advantage. - -To obtain the calcium phosphate contained in the last mother-liquor, -the latter is exactly neutralized with burnt lime, a white precipitate -of basic calcium phosphate being thereby obtained. The precipitate is -repeatedly washed in water and allowed to settle, and added in small -portions to the acid liquors obtained by extracting the bones. As these -liquors always contain a considerable quantity of hydrochloric acid in -excess, the basic calcium phosphate, being in a finely divided state, -is readily and completely dissolved. - -The crystals of acid calcium phosphate are removed from the -crystallizing tanks by means of wooden shovels and brought into baskets -covered inside with stout sack-cloth. They are left in the baskets -until no more mother-liquor drains off, when the cloths are folded -together and the crystals further freed from liquor by pressure. They -are then heated, with constant stirring, in shallow stoneware pans -until they are so dry as to crumble of their own accord. In this manner -small crystals of a mother-of-pearl lustre are obtained, which feel -like sharp quartz sand and consist of pure acid calcium phosphate. - -This mass is mixed with 25 per cent. of its weight of granulated -charcoal. The mixture is heated until it is pulverulent, and then -treated in the same manner as the distilling mass from bone-ash. - -In place of stoneware vessels, shallow lead pans may be used for -evaporating the liquor containing calcium phosphate. To prevent the -melting of the lead the pans are bricked in under a very flat arch, so -that the fire gases are forced to pass close over the liquor, the pans -being kept constantly full. When crystallization is complete the liquor -is drawn off and the pans are refilled. - -In the manufacture of phosphorus there is left after every distillation -a residue of basic calcium phosphate, and it is advisable to decompose -it with hydrochloric acid, this being effected in a vat lined with lead -or coated with paraffine. The mass is completely dissolved, and the -black sludge remaining on the bottom of the vat consists of charcoal, -which had been added to the distilling mass. - -_Distillation of the Phosphorus._—The distilling mass consists of -acid calcium phosphate, charcoal and about 4 to 6 per cent. water. By -heating in the retorts, the acid calcium phosphate is first converted -into calcium metaphosphate, water being eliminated, according to the -following equation: - -CaH_{4}(PO_{4})_{2} = Ca(PO_{3})_{2} + 2H_{2}O. - -By further heating to a white heat the calcium metaphosphate is so far -reduced as to yield two-thirds of its content of phosphorus, while -one-third remains behind as calcium phosphate, corresponding to the -following equation: - -3Ca(PO_{3})_{2} + 10C = Ca_{3}(PO_{4})_{2} + 10CO + 4P. - -The mixture of acid calcium phosphate and charcoal is distilled in -glazed fire-clay retorts, 12 to 18 of them being placed on each side of -a so-called galley-furnace. The bodies of the retorts are placed on the -side of the fire, while the necks pass through openings in the walls -of the furnace, those portions of the wall being only lightly bricked -up, as the retorts, after distillation is finished and the furnace -cooled, have to be removed in order to clear out the residue and -introduce fresh mixture. Between each pair of retorts is left a space -of 5 to 6 inches for the passage of the flames. - -[Illustration: FIG. 53.] - -Experience, however, has proved the advisability of modifying the -galley-furnace by reducing its length and increasing its height, and -placing the retorts in two or three rows, one above the other. Two -such furnaces are placed together with their narrow sides, so that the -fire-gases of both meet in a common chamber, and are conducted from -the latter under the evaporating pans. Four such furnaces may also be -arranged in the form of a cross, and their fire-gases conducted into a -common chamber. By arranging the furnace, as is most frequently done, -for three double rows of seven retorts each, it will hold 42 retorts, a -double furnace 84, and one in the form of a cross 168. The arrangement -of a double furnace is shown in Fig. 53. - -The wall _C_, which separates the two fire-places, serves for -supporting the lowest row of retorts, while the second and third rows -rest upon intermediate pieces. The fire gases pass through flues into -the space over the furnace, the top of which may be directly formed -by the evaporating pans. It is, however, more suitable to place the -evaporating pans on one side and not run the collecting chamber for -the fire gases directly into the chimney. For the introduction of the -retorts into, and their removal from, the furnace, a narrow door is -provided between each two vertical rows of retorts. After placing the -retorts in the furnace, this door is closed with stones and the joints -luted with clay. - -Every three retorts lying one above the other have a common receiver, -_p_, for the collection of the phosphorus distilled off. The necks, -_r_, of the retorts terminate in the collecting pipe, _o_. - -The galley-furnaces, previously described, require the use of a fuel -which yields a very long flame, and can, therefore, be heated only with -wood or very fat coal. - -In order to render possible the use as fuel of coal yielding a short -flame, and especially of coke, furnaces have been constructed which -hold only a small number of retorts, generally five, placed in two -rows, by twos and threes, one above the other. The retorts are -cylindrical in form, and have a capacity equal to that of several -smaller retorts. - -The _receivers_ for collecting the phosphorus distilling over from the -retorts are made of clay, and should be well glazed and smooth inside. -Each receiver consists of two parts, one of which is a cylindrical -vessel open at the top, into which the other part fits, and is fixed -by means of a rim, which is prolonged so as to form a neck, between -which and the first part is inserted a tube fitted on the neck of the -retort, while the other end of this tube dips for about 4 inches into -the receiver, the latter being filled with water. - -Under certain conditions enameled cast-iron may be used as a material -for receivers, but the enamel must be of such a nature as not to be -attacked by the phosphorus vapors, otherwise the receivers would in a -short time be destroyed. - -The retorts having been filled with the required quantity of mixture -are placed in the furnace and the brickwork is restored. The fire is -then kindled and kept up very gently for some time in order to dry -the fire clay used in joining the bricks. The receivers are filled -with water and fitted to the retorts. In each receiver a small iron -spoon is placed fastened to iron wire which serves as a stem. After -six to eight hours of firing the heat has been so much increased as to -cause the expulsion of any moisture left in the material placed in the -retorts, while quantities of hydrocarbon gases and oxide of carbon are -formed and expelled with the sulphurous acid. Subsequently other gases -are given off, and because they contain some hydrogen phosphide are -spontaneously inflammable. As soon as this phenomenon is observed the -joints of the receivers and apparatus connecting it with the retorts -are luted with clay, care being taken to leave, by the insertion of -an iron wire, a small opening for the escape of the gases, which are -as speedily as possible removed by well arranged ventilators from the -building in which the furnace is placed. The appearance of amorphous -phosphorus at the small opening indicates the commencement of the -distillation. - -The spoon is then placed in the receiver in such a direction that any -phosphorus coming over may collect in it. During the progress of the -operation, and as long as any phosphorus distils over, the evolution -of combustible gases continues, and consequently a small blue-colored -flame is observed at the opening in the lute. The water in the -receiver is kept cool during the operation. After forty-six hours, -with greatly-increased firing, a full white heat is reached, and the -quantity of phosphorus coming over has decreased so much as to make -a continuation of the ignition process wasteful. The receivers are -therefore disconnected from the retorts. - -The receivers are taken to a special room and entirely submerged -in large wooden troughs filled with water in order to drive off -inflammable gases still contained in them and to cover the phosphorus -with water. They should be opened only after this has been done, and -every manufacturer should rigidly enforce the rule of carrying on the -operation in the above-described manner. Crude phosphorus is very -inflammable, and when carelessly handled by the workmen may inflict -horrible burns and, as the phosphorus as a rule causes blood-poisoning, -such injuries generally cause death. - -The phosphorus is then removed from the receivers (always under water). -The trough in which this operation is effected should be provided, a -few inches above the actual bottom, with a perforated false bottom upon -which the receivers are placed. The larger pieces of phosphorus taken -from the receivers are collected, under water, in special vessels, -while the smaller pieces fall through the perforations of the false -bottom to the actual bottom. When all the receivers have been emptied, -the water in the trough is discharged into a large barrel in which it -remains until the particles of phosphorus have subsided. The water is -then drawn off, with the exception of a sufficient quantity to cover -the phosphorus in the barrel. - -The water from the receivers as well as from the troughs shows a quite -strong acid reaction due to phosphoric acid, which has been formed by -the combustion of phosphorus and passed into solution. In order not -to lose this phosphoric acid, the water is partly used for filling -the receivers and partly for mixing the bone-ash before adding the -sulphuric acid. - -Crude phosphorus is a mixture of crystalline (ordinary) phosphorus with -amorphous phosphorus, the reddish color of the mass being due to the -latter. It further contains phosphorus in various stages of oxidation, -free carbon, and if impure sulphuric acid has been used, arsenic in -combination with phosphorus. - -_Refining and purifying the phosphorus._ The crude phosphorus was -formerly purified by forcing it through the pores of stout wash leather -by means of a machine. The crude phosphorus contained in a tightly -tied piece of wash leather is placed on a perforated copper support -situated in a vessel filled with water at 122° to 140° F. As soon as -the phosphorus is molten, there is placed on the wash leather a wooden -plate which by the aid of a mechanical arrangement and a lever can be -forced downwards so as to cause the fluid phosphorus to pass through -the pores of the leather, the impurities being retained. The phosphorus -in the form of a slightly yellowish fluid collects on the bottom of -the vessel and is immediately moulded into the shape in which it is -brought into commerce. The residue in the wash leather consists chiefly -of charcoal dust and amorphous phosphorus. The wash leather can, as a -rule, be only used once, and only small quantities of phosphorus can be -worked at one time. - -A more suitable process of purification is as follows: Porous, unglazed -porcelain or earthenware plates are fixed in an iron cylinder connected -with a steam boiler. The cylinder having been hermetically closed is -placed in a vessel containing water at 140° F. When the phosphorus -is molten, steam of a few atmospheres’ pressure is admitted into the -cylinder, the phosphorus being thus forced through the earthenware -plates. - -The phosphorus obtained by either of these methods is free from -mechanically admixed particles of charcoal and amorphous phosphorus, -but it is by no means pure, as all the substances dissolved in it -(oxides of phosphorus) pass through the filter. The loss of phosphorus -amounts to from 5 to 6 per cent. of the weight of the crude product. -The masses taken from the filter plates are therefore collected -and subjected by themselves to distillation in order to obtain the -phosphorus contained in them. - -To obtain pure phosphorus, the crude product has to be subjected to -distillation, this operation being carried on in iron retorts of a -peculiar make, and shaped like the glass retorts used in chemical -laboratories. The necks of these retorts dip to a depth of ½ to ¾ inch -in water contained in a basin filled to the rim so that any phosphorus -which is discharged into this water causes it to overflow. The crude -phosphorus having been fused under water is next mixed with 12 to 15 -per cent. of its weight of moist sand, and this mixture placed in -the retorts, the object of the mixing with sand being to prevent the -phosphorus becoming ignited during the filling of the retorts. - -[Illustration: FIG. 54.] - -Fig. 54 shows a distilling apparatus. In consists of a cast-iron -retort, _K_, fitted with a cast-iron dome, _H_, the joint being made -tight by means of clay and screws. The dome, _A_, tapers to a cone and -terminates in a wide glass tube, _R_, bent at a right angle, and having -at the mouth a diameter of about 2⅓ inches. - -This dome, _A_, dips ¾ inch deep in water contained in the copper -gutter of the receiver filled to the brim. The copper receiver, _P_, -stands in water. It contracts below in the form of a funnel, and -terminates in a pipe closed by a cock, _G_, to which is fitted a glass -tube bent at a right angle. - -The retort having been filled with the mixture of crude phosphorus and -sand, the dome, _H_, is placed in position and the apparatus brought -into the furnace. The dome is then connected with the condensing -apparatus. - -The fire is so regulated that the retort is uniformly heated from all -sides in order to evaporate as quickly as possible the water still -adhering to the phosphorus mixture, since at a higher temperature the -water acts upon the phosphorus, and phosphoretted hydrogen is formed. -It being scarcely possible to entirely avoid the formation of the -latter, the receiver has been given the above-described form, so that -the disagreeable vapors formed by the ignition of the phosphoretted -hydrogen cannot escape into the workroom. The gas escapes through the -conical dome. _A_, and the glass pipe, _R_, into the open air, where it -burns without molesting the workmen. - -At first steam only escapes from the retort, while later on -phosphoretted hydrogen passes off. The evolution of the latter, -however, soon ceases almost entirely, and the phosphorus distils -uniformly over. Heating is continued until the retort shows a slight -red heat, all the phosphorus having by that time passed over. The -residue in the retort consists only of sand and charcoal. - -The phosphorus passing over in the various stages of distillation shows -different qualities. The portion which passes over first is perfectly -pure, and when cold presents the appearance of bleached wax; the -portions passing over later on are of a yellowish-red color, while the -last portions are colored brick-red by amorphous phosphorus, and have -to be collected by themselves. They are again brought into the retort -in the subsequent operation. - -In order to be able to separate the phosphorus passing over according -to quality, the receiver for the melted mass is fitted with a conical -bottom furnished with a glass tube which can be closed by the cock _G_. -This glass pipe leads to a tank filled with warm water, in which the -collecting vessel is immersed. The phosphorus collecting in this vessel -is from time to time allowed to run into a vessel filled with water, -another vessel being substituted when the phosphorus commences to show -a yellowish color. - -_Moulding the refined phosphorus._ It has long been the custom to -mould phosphorus into the shape of sticks formed by the aid of a glass -tube open at both ends, one of these being placed in molten phosphorus -covered by a stratum of warm water. The liquid phosphorus is sucked by -the operator into the tube until it is quite filled. The lower opening -of the tube being kept under water is closed by the finger of the -operator; the tube is instantly transferred to a vessel filled with -very cold water by which the phosphorus is solidified. It is removed -from the glass tube by pushing it out with a glass rod or iron wire -while being held under water. - -Independent of its danger, the method of moulding above described -is not suitable for the manufacture on a large scale, and various -contrivances have been introduced for this purpose; the apparatus -constructed by Seubert being much used. It consists of a copper boiler -fitted on a furnace. To the flat bottom of this boiler is fitted by -hard solder an open copper trough communicating with a water-tank. In -the boiler is fitted a copper funnel provided with a horizontal tube. -This portion of the apparatus is intended for the reception of the -phosphorus. At the end of the horizontal tube is placed a stopcock, -while the portion of the projecting mouth of the tube beyond the -cock is widened out and fitted by means of bolts and nuts, with a -flange-like copper plate, into which are inserted two glass tubes. -Into the copper trough is let a wooden partition, which serves the -purpose of supporting the glass tubes as well as of preventing the -communication of the hot water in the boiler and a portion of the -trough with the cold water of the tank and the portion of the trough -nearest to it. The phosphorus having been introduced in the boiler, the -water is gently warmed so as to cause the fusion of the phosphorus. -As the warm water reaches to the wooden partition, it is evident that -on opening and closing the cock at the end of the horizontal tube, -some phosphorus will pass through and flow out of the glass tubes, but -that remaining in these tubes will solidify, and on opening again the -cock at the end of the horizontal tube, the solid sticks of phosphorus -may be removed from the glass tubes by taking hold of the piece of -projecting phosphorus, the phosphorus being immediately immersed under -water in the tank, and kept there protected from the action of the -light. - -Notwithstanding its apparently very practical arrangement, Seubert’s -apparatus possesses many disadvantages, the principal drawback to its -use being that the phosphorus-sticks frequently stick so firmly in the -glass tubes that the operation of moulding has to be interrupted, the -tubes removed, and the phosphorus stick pushed out with a stout wire. -Furthermore, the melted phosphorus in flowing in frequently causes the -glass tubes to crack. - -Hence many factories have returned to the old method of moulding by -sucking the fused phosphorus into glass tubes. To render this operation -perfectly free from danger, the apparatus shown in Fig. 55 has been -devised, by means of which a larger quantity of phosphorus can in a -short time be moulded into sticks. - -A hollow prism, _P_, of stout sheet-iron is fitted at its lower end -with 8 to 12 short tubes. In the latter are inserted air-tight, by -means of rubber, 12 glass tubes, _G_, each about 3¼ feet long and -somewhat contracted at the lower end. Two iron rods, _E_, are fitted -to the prism and, by means of suitably-shaped pieces of cork, serve -to hold the glass tubes in their proper position. To the back of the -prism is secured a rubber tube, _L_, which communicates with a small -air-pump, and to the upper surface of the prism is fixed a handle. - -[Illustration: FIG. 55.] - -The phosphorus to be moulded is fused in a shallow vessel of such a -shape that a portion of it is covered only about 2 inches deep with -water. The glass tubes are placed in the fused phosphorus and the air -is sucked from them by means of the air-pump; the external air-pressure -forcing the fused phosphorus into the glass tube. - -The tubes are now sufficiently raised to allow of a rubber plate being -pushed under their mouths in the shallower portion of the vessel. The -rubber plate is pressed against the tubes and the entire apparatus -placed in a vessel filled with cold water. The phosphorus solidifies -very rapidly in the lower narrower portions of the tubes, and the -latter are immediately detached from the prism and replaced by others. -The phosphorus when entirely cold is pushed from the glass tubes by -means of a wire or wooden stick. - -In some factories the phosphorus is moulded in wedge-shaped sheet-metal -boxes. In packing two such wedges are laid together with their -longitudinal sides so as to form a prism. - -Phosphorus is stored either in strong sheet-iron tanks or in wooden -boxes lined with tinned sheet-iron and covered with a stratum of water -fully 1¼ inches deep. For shipping smaller quantities of phosphorus, -the sticks are packed in tinned sheet-iron boxes and the latter having -been filled up with water, the lid is soldered on. To prevent the water -from freezing in winter, it is advisable to mix it with spirits of wine. - -_Manufacture of phosphorus with the assistance of electricity._ Readman -and Parker have recently devised a process for the manufacture of -phosphorus on a large scale in a continuously working apparatus by -means of a powerful electric current, such as is yielded by a larger -dynamo. The mixture used for the operation differs from the ordinary -one of calcium phosphate and charcoal, in that it contains in addition -a slag-forming body—a flux—silicic acid (quartz sand) being at first -used for the purpose. Numerous experiments, however, have shown kaolin -or pipe clay, _i. e._, aluminium silicate, to be more suitable. - -When a mixture of calcium phosphate, charcoal and aluminium silicate -is exposed to the action of the voltaic arc the following process -takes place: By the extraordinarily high temperature prevailing in the -proximity of the arc, the reduction to phosphorus of the phosphoric -acid contained in the calcium phosphate is very rapidly effected. The -liberated calcium combines immediately with the aluminium silicate to -a calcium-aluminium-silicate, _i. e._, to a glass fusible with the -greatest difficulty which, however, at the high temperature possessed -by the voltaic arc becomes fluid like water. - -The apparatus employed is, generally speaking, similar to the electric -furnaces now in use. The mass to be treated is contained in a carbon -crucible in which the two electrodes are placed opposite to one -another, so that the electric current must pass through the mass. -However, since the phosphorus at the moment of liberation would, on -coming in contact with oxygen, immediately burn again to phosphorus -pentoxide, the apparatus has to be so arranged that the entire process -passes off in an entirely indifferent gas, and the condensation of the -phosphorus vapors takes place under the same conditions. - -Fig. 56 shows the apparatus employed for the electrolytic manufacture -of phosphorus. - -[Illustration: FIG. 56.] - -The carbon crucible, _a_, is enclosed by a clay jacket, which serves as -an insulator of heat, and is closed by a graphite cover, _c_. Through -the bottom and the cover of the crucible pass the two electrodes, _k -k_, which conduct the current, and between which the voltaic arc is -formed. To prevent the upper electrode from becoming too highly heated -during the operation, it is constantly cooled by water admitted at _g_, -and running off at _f_. Through the pipes _h_ and _l_ an indifferent -gas—as a rule, illuminating gas—is conducted into the apparatus and -escapes together with the phosphorus vapors through the pipe _d_. - -In operating with the apparatus, the reduction soon takes place, and -the phosphorus vapors escape through _d_, while a thinly-fluid slag -remains behind in the crucible. The slag is discharged through a pipe -not shown in the illustration, and a fresh charge of the mixture -brought into the crucible _a_, the process of reduction being thus -carried on without interruption. The phosphorus vapors escaping from -_d_ are conducted through a cooled pipe and condense to a liquid in -water heated to between 122° and 140° F. contained in a receiver. - -Although the electrolytic method of manufacturing phosphorus is of -quite recent origin, a considerable portion of the phosphorus brought -into commerce is now prepared in that manner, it being cheaper than the -older processes which involve a very large consumption of fuel. - - - - -CHAPTER VII. - -METHODS OF BLEACHING GLUE. - - -Many experiments have been made to bleach glue, _i. e._, to obtain -masses as colorless as possible, or at least slightly colored, the -resulting product being more valuable than the dark-colored one. - - -a. _Bleaching in the Air._ - -The principal requisite for obtaining a beautiful bleached glue is that -the unbleached product is clear, _i. e._, transparent, even if of a -dark color, this being the best criterion of well-made glue. - -Glue may be bleached whilst being prepared, or the finished cakes may -be subjected to the bleaching process. - -For the purpose of obtaining pale-colored glue from skin or cartilage -it is advisable to expose the materials in thin layers to the direct -action of the sun. Moist oxygen when acted upon by the sun is converted -into ozone, which exerts an extraordinary bleaching effect upon organic -substances. - - -b. _Bleaching with Chlorine._ - -The powerful bleaching effect of a solution of chlorine in water upon -organic matter is well known; the water is decomposed, and bleaching is -effected by the oxygen which is liberated. Hence skin and cartilage may -also be bleached by placing them in a vessel filled with weak solution -of chlorine in water and leaving them in contact with it until the -fluid shows no longer an odor of chlorine. When bleaching is finished -the materials are suspended in a certain quantity of hydrochloric acid, -which has finally to be removed by repeated treatment with water. - - -c. _Bleaching with Animal Charcoal._ - -Animal charcoal is distinguished by its great power of absorbing -coloring as well as odoriferous matter, and may also be used for -discoloring glue-liquors. This may be done by allowing the thin liquor, -as it comes from the glue-boiler, to run through a filter filled with -animal charcoal, or with the use of charcoal dust. - -In the latter case the glue-liquor is collected in a clarifying vessel -and a quantity of charcoal dust amounting to about 3 to 4 per cent. of -the weight of the glue in the liquor stirred in. The finely divided -charcoal sinks slowly down, carrying with it the solid particles -suspended in the liquor, and collects on the bottom of the clarifying -vessel in the form of a black slime. - -In order to discolor the glue-liquor as much as possible, when working -on a large scale, it is recommended to use a number of cylinders filled -with animal charcoal. These cylinders are connected one with the other -in such a manner that the glue-liquor runs into the first cylinder from -the top, passes out from the lower end of this cylinder through a pipe -into the second cylinder, traverses this from bottom to top, passes -into the third cylinder from the top, and so on. The animal charcoal -in the first cylinder loses its discoloring power first. The cylinder -is then disengaged, freshly charged and placed last in the series of -filters, the process being the same with the second cylinder, and so -on, so that after a certain time all the cylinders have alternately -occupied the first and last places in the series of filters. - -By the use of animal charcoal it is even possible to render very dark -and badly-smelling glue, entirely colorless and free from odor. The -darker the glue is, the longer it must, of course, be subjected to the -action of the animal charcoal. - - -d. _Bleaching with Sulphurous Acid._ - -Bleaching of the glue-liquor itself by means of sulphurous acid is -best effected in the clarifying vat. For this purpose, the latter is -fitted with a lead pipe reaching to the bottom and terminating in a -perforated coil. Through this pipe gaseous sulphurous acid, generated -in a suitable sulphur-burner is forced through the liquor by means of a -force-pump. - -The sulphurous acid is dissolved in the glue-liquor, the latter being -thereby bleached. When the liquor has acquired a much paler color and -a strong odor of sulphurous acid is perceptible in the air over the -vat, the introduction of gaseous sulphurous acid is interrupted and the -liquor allowed quietly to clarify, the acid dissolved in it exerting -during this time a further bleaching effect. By this means ordinary -brown joiners’ glue of good quality may be converted into a pale-yellow -product similar to the variety known as gilder’s glue. - -[Illustration: FIG. 57.] - -For bleaching finished glue, solution of sulphurous acid in water may -be used, the apparatus shown in Figs. 57 and 58 being suitable for the -purpose. - -The apparatus for the production of the acid solution consists of the -sulphur-burner _O_, the wash-vessel for the gas _W_, and the vessel _T_ -for dissolving the gas in water. - -The sulphur-burner _O_ is a small brick vault of sufficient size to -hold a vessel _S_ having a capacity of a few quarts. In front the -sulphur-burner is provided with a well-fitting door _J_, which is -furnished with a small aperture for the introduction of an iron pipe -into the burner. The lead-pipe _R_ leads from _O_ to the bottom of the -wash-vessel _W_, and from the lid of the latter rises a pipe _R_{1}_, -and runs along the bottom of the trough filled with water. This trough -is provided with a wooden lid and the cock _H_, and by means of the -latter the fluid can be discharged into the vessel _G_. - -[Illustration: FIG. 58.] - -The trough _T_ is filled with water and _W_ is also filled -three-quarters full. In the burner _O_ is placed a dish _S_ filled with -sulphur, and the latter ignited. The door is then closed and air blown -in through _A_ by means of a bellows, the joints of the door _J_ being -at the same time luted with clay. - -In contact with air, the sulphur burns to sulphur dioxide. The latter -is freed in the wash-vessel from sulphur vapor which has been carried -along, and passes from _R_{1}_ through the numerous perforations into -the water in _T_ where it is dissolved to sulphurous acid. - -Saturation with sulphurous acid of the fluid in the trough is complete -when the suffocating odor of the acid is perceptible in the proximity -of _T_. The fluid is then discharged, replaced by water, which is again -saturated with sulphuric acid, and so on. - -The cakes of glue to be bleached are placed in a trough (Fig. 58), in -which are arranged several frames, _B_, covered with linen. The cakes -of glue are placed upon these frames and the trough is filled with -sulphurous acid so that it stands a few inches deep over the uppermost -frame. The cakes of glue swell up rapidly in the solution of sulphurous -acid, and yielding up their salts become bleached. After twelve hours -the fluid is discharged through the cock, _H_, and if glue of a -particularly fine appearance is to be produced the cakes are treated -twice more with solution of sulphurous acid. - -When bleaching is finished the trough is filled with clean water, in -which the glue is allowed to remain for a few hours, when the frames -are lifted out and the cakes dried. - -By this method glue may be bleached to such an extent as to render it -fit as a substitute for gelatine for many purposes, for instance, for -the imitation of thin plates of ivory. - -Dr. Bruno Terne’s apparatus (Fig. 40), previously described, may also -be used for the generation of sulphurous acid for bleaching purposes. - - - - -CHAPTER VIII. - -DIFFERENT VARIETIES OF GLUE AND THEIR PREPARATION. - - -Besides the broadly-distinguished forms of skin-and bone-glue, the -trade recognizes a large number of varieties, distinguished either by -their value or their fitness for special purposes. - -_Joiner’s Glue._—This variety is without doubt the oldest in use and -most in demand, and its principal requisite is its great adhesive -power. It is used for joining wood, leather, paper, etc., and varies -very much in quality and price. - -The best variety is prepared from scraps of hide and skin. A light -color not being especially demanded, there existing rather a prejudice -in favor of a dark-colored article, waste of cattle and horse skins and -tendons can be used for its manufacture. - -Joiner’s glue, which is generally preferred in thin cakes, is chiefly -manufactured in regular glue factories, though to be able to compete -with the bone-glue turned out by the large establishments, the -glue-boiler generally mixes skin and bone-glue, and is thus enabled to -turn out a tolerably good quality. The price paid for the different -varieties of joiner’s glue varies very much, being generally higher in -winter than in summer, and is frequently more regulated by the external -appearance of the article than by its actual value. Glue without gloss, -very much warped and of a very dark color, may, notwithstanding its -faulty appearance, possess excellent qualities. - -Nothing need be said about the manufacture of joiner’s glue, since what -has been said about the manufacture of glue in general suffices for the -purpose. - -_How to make and use glue._ Break the glue into small pieces, put it -into an iron kettle, cover it with water, and allow it to soak twelve -hours; after soaking boil until done. Then pour into a box which can be -covered air-tight; leave the cover off until cold, then cover up tight. -As glue is required, cut out a portion and melt in the usual way. -Expose no more of the made glue to the atmosphere for any length of -time than is necessary, as the atmosphere is very destructive to made -glue. - -All glue, as received from the factory, requires the addition of water -before it will melt properly, and every addition of water (while -the glue is fresh made) will, up to a certain point, increase its -adhesiveness and elasticity. Some glues will bear more water than -others, but all will bear more water than usually falls to their share, -and that, too, with a greater improvement in the quality of the work. -For glue to be properly effective, it requires to penetrate the pores -of the wood, and the more a body of glue penetrates the wood the more -substantial the joint will remain. Glues that take the longest to dry -are to be preferred to those that dry quickly, the slow-drying glues -being always the strongest, other things being equal. Never heat made -glue in a pot that is subjected to the direct heat of the fire or a -lamp. All such methods of heating glue cannot be condemned in terms too -strong. Do not use thick glue for joints or veneering. In all cases -work it well into the wood in a manner similar to what painters do -with paint. Glue both surfaces of your work excepting in the case of -veneering. Never glue upon hot wood, as it will absorb all the water in -the glue too suddenly, and leave only a very little residue, with no -adhesiveness in it whatever. - -_Holding power of glue._ 1. Glue exerts a far greater hold on surfaces -of wood cut across the grain than on those that have been split, or cut -with the grain. - -2. When two surfaces of split wood are laid together, the hold of the -glue is the same whether the fibres are laid parallel or crosswise to -each other. - -3. The holding power of glue on different woods estimated in -kilogrammes per square centimeter (0.155 square inch) is as follows: - - Cut across the grain. Split. - Beech, 155.55 (342.21 lbs.) 78.83 (173.42 lbs.) - Hornbeam, 126.50 (278.30 lbs.) 79.16 (174.15 lbs.) - Maple, 87.66 (192.85 lbs.) 63.00 (138.6 lbs.) - Oak, 128.34 (282.34 lbs.) 55.16 (121.35 lbs.) - Fir, 110.50 (243.10 lbs.) 24.16 (53.15 lbs.) - -_Cologne glue._ The variety of glue known under this name is prepared -from selected scraps of hide and skin, and is consequently very pure, -and possesses great adhesive power. It is of a light-brown color, -and comes into commerce in short thick cakes of great hardness. It -is an excellent quality of glue, and is preferred to all others by -bookbinders, workers in leather, etc. There are many imitations of this -variety, bone-glue being frequently sold as Cologne glue. - -The genuine article is manufactured from refuse of hide, which, after -liming, is carefully bleached in a bath of chloride of lime, the -concentration of which depends on the darker or lighter color of the -glue-stock. For 220 lbs. of glue-stock, it is generally customary to -use 1 lb. of chloride of lime mixed with sufficient water to cover the -stock. - -After thorough impregnation of the glue-stock, which generally requires -about half an hour, add sufficient hydrochloric acid to impart an acid -taste to the bath of chloride of lime. To be able to mix the mass -thoroughly, it is best to use a vat provided with a stirring apparatus. -After allowing the acid to act for a quarter of an hour, remove every -trace of it by careful washing. - -To obtain a jelly as clear as possible, the gelatinous liquor is drawn -off as soon as the thin portions of the glue-stock and the outside of -the thicker ones are dissolved, they being more thoroughly bleached -than the rest. The residue is worked into darker glue. - -_Russian glue._ This variety is of a dirty white color, and, like -Cologne glue, is brought into commerce in short, thick cakes. Its color -and opaqueness are imparted to it by an addition of 4 to 8 per cent. of -white lead, chalk, zinc white, or permanent white (sulphate of baryta). -It has been claimed that the superior adhesive power of Russian glue -is due to this addition of mineral substances, but the results of many -experiments fail to substantiate this claim. In case the glue turns -out turbid, it may be of advantage to make it opaque by an addition of -coloring matter, but the quality of the glue remains unchanged. The -best time to add the coloring matter is shortly before drawing the -glue-liquor from the clarifying vats into the cooling boxes, as the -jelly is then of sufficient consistency to prevent the substances from -settling on the bottom. Skin-glue, as well as bone-glue, is sold under -the name of Russian glue. - -Quite a considerable quantity of Russian glue brought into commerce in -the form of brownish-white sheets is prepared from bones, the latter -being degreased by boiling, steaming or extraction, and the solution of -the mineral constituents effected by means of hydrochloric acid. The -treatment with acid is, however, continued only till the bones commence -to become soft and flexible. The solution of phosphates is then drawn -off, and the softened bones are washed and in the usual manner worked -to glue. - -By this incomplete treatment with hydrochloric acid, a certain quantity -of the phosphates remains in the cartilage and is inclosed in the -glue prepared from it, the finished product acquiring thereby a dirty -whitish color, which is by many considered an evidence of its quality. -This mechanical admixture of phosphates, however, does not affect the -adhesive power of the glue, neither increasing or decreasing it. Such -white and opaque glue is manufactured to answer the demand in certain -quarters of the trade, and, as above mentioned, heavy white substances -are often intentionally incorporated with skin glue, as well as bone -glue, to give it the appearance of Russian glue. These heavy powders -add to the weight of the product, though when incorporated with it in -small quantities do not injure its adhesive power, but large quantities -render the product weaker. - -_Patent glue._ This term is applied to an indefinite number of -preparations, but particularly refers to a very pure variety of bone -glue of a deep dark-brown color not showing net marks. It is very -glossy, and swells up much in water. To satisfy the demand for thick -cakes, they must be cut from very concentrated jelly to insure their -drying. - -_Gilder’s glue_ is found in commerce in very thin, pale yellow cakes -tied up in packages weighing about 2 lbs. each. It is a variety of skin -glue bleached with chloride of lime, and dissolves with difficulty in -water. The first runnings from the boiler are used for its manufacture. - -A very superior article of gilder’s glue is obtained by cutting -rabbit skins into fine shreds and boiling in water, then turning the -mixture into a basket through which the liquid passes, leaving the -refuse behind. About 100 grammes (3.52 ozs.) of sulphate of zinc and -20 grammes (0.705 oz.) of alum are then separately dissolved in pure -boiling water and poured into the first-mentioned liquid, and the whole -well stirred together while hot. The mixture is then passed through a -sieve into a rectangular box, in which the jelly remains twenty-four -hours in winter, or forty-eight in summer. The solid mass is taken from -the box, cut into slices of proper thickness, and dried upon nets. - -_Size glue and parchment glue_ are manufactured in the same manner. -Both are skin-glues, and can be readily produced by following the -directions given for the manufacture of skin-glue. - -_Paris glue_ is used for sizing. It is brown, opaque, and almost always -soft. Being very hygroscopic, and imparting a suitable flexibility to -the felt, it is better adapted for hatter’s use than any other variety. -For its manufacture only the generative organs, or the thick tendons -of the legs of cattle and horses, are used, or other waste and fleshy -parts, and substances mixed with small bones, which, if thoroughly -cleansed, might yield a good quality of glue, but are intentionally -transformed by too long-continued boiling, whereby the gelatinous -solution is largely deprived of its adhesive power, and yields a -hygroscopic product. - -_Liquid Glues._ These are chiefly combinations of glue with some -ingredients added to destroy the gelatinizing property and yet not -impair its adhesiveness. They remain for a long time clear and syrupy, -and are used for a variety of purposes. Below are given a few receipts -for such glues. - -1. Dissolve 38 parts of glue in small pieces in 100 parts of acetic -acid. Solution is promoted by exposing the vessel to the sun or placing -it in hot water. - -2. Dissolve 50 parts of light-colored glue in 50 parts by weight of -hot water, in which 14 parts of fused magnesium chloride have been -dissolved. The solution on cooling does not gelatinize, but remains -syrupy, the density varying according to the quantity of water used. In -the preparation of printing inks it can be used as a substitute for gum. - -3. Dilute 10 parts of strong phosphoric acid with an equal weight of -water, and then gradually add 4 parts of ammonium carbonate in the dry -state. When the effervescence has subsided, add a further 5 parts of -water and warm on the water-bath or steam-chest to 158° F. Now add 20 -to 40 parts of glue, according to the consistency required, and stir -until all is dissolved. Cool. - -4. Dissolve 20 parts of glue in an equal weight of hot water, then -cautiously pour in, stirring constantly, 4 parts of strong nitric -acid, warm until the nitrous fumes have been driven off, filter, if -necessary, through fine shavings, and allow to cool. - -5. Dissolve 3 parts of glue in small pieces in 12 to 15 parts of -saccharate of lime. By heating, the glue dissolves rapidly and remains -liquid, when cold, without loss of adhesive power. Any desirable -consistency can be secured by varying the amount of saccharate of lime. -Thick glue retains its muddy color, while a thin solution becomes clear -on standing. - -The saccharate of lime is prepared by dissolving 1 part of loaf sugar -in 3 parts of water, and after adding one-fourth part of the weight of -sugar of slaked lime, heating the whole to between 149° and 185° F., -and allowing it to macerate for several days, shaking it frequently. -The solution, which has the properties of mucilage, is then decanted -from the sediment. - -The solution of the glue in saccharate of lime is readily accomplished, -even old gelatine, which has become insoluble in water, dissolving -without difficulty. This variety of liquid glue possesses great -adhesive power, and admits of many uses. - -6. Dissolve 8 parts of glue in 16 parts of hot water, then add ½ to 1 -part of hydrochloric acid, and 1½ parts of sulphate of zinc. Keep the -mixture for 8 hours at 158° F., then filter through fine shavings, and -allow to cool. - -_Steam glue._ Under this name several varieties of liquid glue are -brought into commerce. They are prepared as follows:— - -1. _Russian steam-glue._ 100 parts of a good quality of glue, 100 to -110 parts of warm water, and 5.5 to 6 parts of commercial nitric acid -of 36° B. - -2. _Pale steam-glue._ 100 parts of glue, 200 of water, and 12 of nitric -acid of 36° B. - -3. _Dark steam-glue._ 100 parts of glue, 140 of water, and 16 of nitric -acid of 36° B. - -Soak the glue in cold water, then pour the necessary quantity of warm -water over it, and heat gently on a water-bath until all the glue is -dissolved. Next add gradually the nitric acid with constant stirring, -and to the Russian steam-glue 6 parts of finely pulverized sulphate of -lead, which will impart to it the white color. - -_Chrome glue._ This preparation is very permanent and durable. To -prepare it add to a moderately concentrated solution of 5 parts of -glue 1 of dissolved acid chromate of lime, this salt being considered -better for the purpose than the bichromate of potash usually used. The -glue thus prepared becomes, after exposure to the light, insoluble -in water in consequence of a partial reduction of the chromic acid. -This preparation can be used for cementing glass articles, liable to -be exposed to boiling water, the treatment being the ordinary one of -applying the glue to both surfaces of the fractured object, and then -binding them together until dry, and exposing them for a sufficient -length of time to the light, after which boiling water will have no -effect upon them. It is suggested that this preparation is better -adapted to cementing the covers on glass slides than any now in use. -The same preparation can be applied for making fabrics water-proof, -especially sails, awnings, etc., where no great flexibility is -required. Two or three applications of the glue, either by immersion -of the object in it, or by the use of the brush, will answer the -purpose. Roofing paper is also rendered impervious, even when exposed -to long-continued rains. - -_Glue for attaching leather to metal._ A method of affixing leather to -metal, so that it will split before it can be torn off, consists in -digesting a quantity of nutgalls, reduced to powder, in eight parts of -distilled water for six hours, and filtering it through a cloth; then -dissolving one part by weight of glue in the same quantity of water, -and allowing it to remain twenty-four hours. The leather is moistened -with the decoction of nutgalls and the solution of glue applied to the -metal, previously roughened and heated. The leather is then laid upon -it, and dried under pressure. - -_Glue for leather, paper, etc._ The following process affords an -unusually adhesive paste, adapted to fastening leather, paper, etc., -without the defects of glue, and if preserved from evaporation in -closed bottles will keep for years. Cover 4 parts, by weight, of glue -with 15 parts of cold water, and allow it to soak for several hours; -then warm moderately till the solution is perfectly clear, and dilute -it with 65 parts of boiling water, intimately stirred in. Next prepare -a solution of 30 parts of starch in 200 of cold water, so as to form -a thin homogeneous liquid free from lumps, and pour the boiling glue -solution into it with thorough stirring, and at the same time keeping -the mass boiling. - -_Glue for parchment paper in making sausage skins._ The supply -of intestines soon being exhausted by the enormous quantity -of pease-sausages manufactured for the German army during the -Franco-German war, the necessity arose for a substitute. This consisted -of a tube of parchment glued together. Millions of these tubes from Dr. -Jacobsen’s factory were tested by the government, and found to answer -the purpose admirably. They were even boiled for hours without either -the glued seam or the paper itself being injured by the operation. -The secret of the composition of the glue employed for fastening -the parchment paper seems to be well kept, but the one given in the -following is equal to it in all respects, if not indeed identical: -Add to one quart of a good adhesive solution of glue ¾ to 1 oz. of -finely powdered bichromate of potash. Warm the mixture slightly on a -water-bath when about to use it, and before applying it moisten the -parchment paper. The latter, when glued with this preparation, as in -the formation of the small cylinders for sausages, must be rapidly -dried on a hurdle, and then exposed to the light until the yellow glue -becomes brownish. The cylinders are then slowly boiled in a sufficient -quantity of water to which two or three per cent. of alum has been -added, until all the chromate is dissolved out, and they are then -washed in cold water and dried, and will look very inviting, especially -if white glue has been used. A similar result may be reached by using -a concentrated solution of cellulose in ammoniacal oxide of copper. -Thus if cylinders of unsized paper are formed with this paste, and -when thoroughly dry drawn through a parchmentizing solution (a cooled -mixture of 2 volumes of fuming sulphuric acid and 1 volume of water), -they will be beautifully parchmentized, and after the neutralization -of the acid, washing, etc., it will present a striking resemblance to -natural intestines. - -_Tungstic glue._ This preparation offers an acceptable substitute for -hard India rubber. It is made by mixing a thick solution of glue with -tungstate of soda and hydrochloric acid, by means of which a compound -of tungstic acid and glue is precipitated, which, at a temperature of -86° to 104° F., is sufficiently elastic to admit of being drawn out -into very thin sheets. On cooling, this mass becomes solid and brittle, -and on being heated is again soft and plastic. It can be used for all -purposes to which hard rubber is adapted. - -_Indestructible mass for the manufacture of ornaments, toys, etc._ A -mass, which is to have the hardness of horn, consists of 50 parts of -glue, 35 of wax or rosin, 15 of glycerine and the required quantity of -a metallic oxide, or mineral color. A soft mass consists of about 50 -parts of glue, 25 of wax or rosin, and 25 of glycerine. The glue is -melted in the glycerine with the assistance of steam, and the wax or -rosin added. The latter in melting mixes with the glue and glycerine, -and finally the mineral color is added. The mass is poured in a liquid -state into moulds of plaster of Paris, wood, or metal. The degree of -hardness of the mass is increased by an addition of 30 to 35 per cent. -of zinc white, or other mineral color, according to the color the -article is to have. - -_Compound for billiard balls._ Allow 80 parts of Russian glue and 10 -parts of Cologne glue to swell up in 10 parts of water; then heat over -a water-bath, and when dissolved, add 5 parts of heavy spar, 4 parts -of chalk and 1 part of boiled linseed oil. Of a portion of the mass -form small sticks, dip them in the remainder, and allow the adherent -portion to dry, and repeat this process until a crude ball has been -formed. This is placed in a dry room for three or four months, and when -thoroughly dry, it is turned. The finished ball is placed in a bath of -sulphate of alumina for one hour, dried, and polished like an ivory -ball. - -_Coloring glue._ Common black or dark glue, while possessing all the -adhesive and other essential qualities of fine colored glue, has -heretofore, owing to its color, been confined in its use to such -purposes in the arts where color was not essential. - -The object of the following process, which is the invention of G. J. -Lesser, of Frankfort, Germany, is to color such glue so that it is both -refined and tinted, and may be used for various purposes in the arts. -It is especially applicable in the manufacture of sizing and finishing -compounds for paper hangings, compounds for the manufacture of elastic -rolls, for glue and size compounds for finishing yarns, textile -fabrics of silk, cotton, etc., for the manufacture of calcimines and -wall-coverings, for glue to be used with colored woods, and for all -other purposes where a fine, strong-colored glue is required. - -For coloring common black or dark glue take a pound and a half of -liquid extract of lead and mix it into the water in which the glue has -been soaked, as follows: Thirteen pounds of glue, sixty-three and a -quarter pounds of water. Allow the glue to soak for about twenty-four -hours, then dilute it by a slow fire, and when heated gradually pour in -one and a half pounds of the extract of lead and mix it well together. - -The extract of lead is a well-known commercial article, and it is well -suited for this purpose; but the inventor does not limit himself to -this particular preparation, as there are a larger number of neutral -and basic compounds of lead that may be so modified as to produce -results similar, if not identical, with the results obtained by the -formula above given. Gelatine may be treated instead of glue. - -_Compositions for printing rollers._ All such compositions contain -gelatine or glue. The following receipts are used: - - - | I. | II. | III.| IV.| V. | VI. | VII.| VIII. --------------+-----+-----+-----+-----+-----+-----+-----+-----+ - Glue | 8 | 10 | 4 | 2 | 32 | 2 | 1 | 3 - Molasses | 12 | — | 8 | 1 | 12 | 6 | 2 | 8 - Paris white | 1 | — | — | — | — | — | — | 1 - Sugar | — | 10 | — | — | — | — | — | — - Glycerin | — | 12 | — | — | 56 | — | — | — - Isinglass | — |1½ ozs.| — | — | — | — | — | — - India rubber| — | — | — | — | 10 | — | — | — - in naphtha - - -A patent roller composition is thus made: Gelatine 32 lbs. and glue -4 lbs. are softened in cold water and melted in a glue boiler. To -this are added 4 lbs. of glucose, 72 lbs. of glycerine, and 1 oz. of -methylated spirit. The whole is then digested for four to six hours -and cast into rollers. This composition is claimed to be unaffected by -temperature, to retain its elasticity, and not to shrink. - -In practice it is found that all these compositions from the cleansing -and remelting become gradually sticky and useless. To partially -overcome this difficulty, formaldehyde is added to the roller -composition, which renders the glue insoluble in water, and thus -prolongs the life of the roller. - -_Size._ This product is simply an undried glue and is used, not -for adhesiveness, but as a body for filling porous surfaces, such -as wood or plaster, stiffening and weighting textile fabrics, in -paper manufacture, and as a foundation for oil paints and varnishes. -According to Thomas Lambert, many firms who have a good selling -connection for size, do not go to the expense of erecting clarifying -plant and drying house for treating the glue-liquors, but prefer to -stop the process half way, as it were, and marketing the resulting -product as size. Others, again, with a complete glue plant at hand, -convert only a portion of their liquors into size, to meet trade -demands, the bulk going for the manufacture of glue. Size varies -in quality to suit the requirements of different trades. Cardboard -box-makers prefer a strong skin size, which is manufactured red or -yellow as preferred. A strong yellow size made from bone is used by -calico-printers, paper-stainers, wall-paper manufacturers, and in the -straw-hat and carpet trades. - -In the preparation of skin-glue, the first and second liquors are used -for that purpose; the residual mass is then treated with water and -steam, which practically exhausts the gelatinous matter. This, the -third liquor, is used solely for size. During the boiling, samples -are taken at intervals, cooled, and the condition of the jelly noted. -The strength is also taken by the glue meter, which registers the -percentage. At a strength of 8 to 10 per cent. the liquor is run off, -passing through a filter of fine shavings or cloth, to remove any -suspended matter, into a wooden vat fitted with a steam coil, then -heated with a moderate charge of sulphurous acid to bring up the color, -and evaporated to a strength of 36 to 38 per cent., as may be desired, -and then run into casks to jelly. If skin-glue is not made, the three -runnings are used entirely for size. - -An outline of a simple process used in an English factory devoted to -making tub-size, as given by Samuel Rideal, may be interesting. - -The material is obtained from the tanyard ready limed and freed from -hair, and consists mainly of “faces” of bullocks or cows, the noses -being cut off as food for dogs. It is soaked again in weak lime water -and re-washed, then placed in coppers made of wrought-iron wielded -in one piece, and holding about 10 to 20 gallons, enclosed in outer -jackets of the same material containing water which is kept well -boiling. There are six coppers, about five feet high by three feet in -diameter. The charge of each is about ½ cwt. The material is covered -with water and well stirred with sticks for two hours, the scum and -dross being occasionally skimmed off and thrown away as useless. At the -end the size is ladled on to sieves, from which it runs into cooling -vats, and is filled while moderately hot into clean tubs. - -The liquor is clear and of a light brown color for the best XX quality, -and darker for the common. The coolers or setting-backs are of wood or -zinc, and the liquid is not kept hot longer than it can be helped, as -it is liable to turn sour. - -Bone-size is, according to Thomas Lambert, prepared as follows: The -bones are first degreased by the naphtha process, and then passed -through the cleanser direct into the glue-boilers and steamed, as in -the manufacture of glue. The resulting liquors are forced up to the -clarifying vats and partially bleached with a current of sulphurous -acid, passing through bag-filters to the evaporating troughs, and -concentrated from 30 to 38 per cent., as required, and then jellied in -casks. - -The manufacturer with no benzine or glue plant at his disposal washes -the bones in a revolving drum, and, after crushing, they are fed into -a boiler and subjected to an alternate current of steam and water, the -latter coming from a spray pipe fixed at the top of the boiler. The -liquors are generally drawn in two portions, having a strength of 14 to -16 per cent. of glue. After separating the fat, which is refined and -sold to the soap-maker, the liquors are run into a large wooden vat -about 8 × 6 × 4 feet, fitted with a steam coil, partly bleached with -liquid sulphurous acid, and then boiled down to the required strength. - -For a common size the bones are crushed but unwashed, and are fed -direct into the boiler and treated as above. The liquors are not -bleached, and boiled to a strength of about 25 per cent. glue. The -composition of the different grades may be given as follows: - - Common size. 25 per cent. glue, 75 per cent. water, etc. - Medium size. 30 per cent. glue, 70 per cent. water. - Best size. 38 per cent. glue, 62 per cent. water. - -A concentrated size is now prepared by many manufacturers. It is a -bone-size, and is sold at a Baumé strength at 122° C. - - No. 1. 15° Bé. at 122° C., 40.5 per cent. glue. - No. 2. 20° Bé. at 122° C., 44.5 per cent. glue. - No. 3. 25° Bé. at 122° C., 49 per cent. glue. - -Under the name of concentrated size also are sold a series of powdered -glues of different qualities. They are the off-color and twisted cakes, -sorted out in the warehouse, and ground to a fine condition by passing -through a mill, and their value is based on the quality of the cake -ground. - -Size rapidly ferments and becomes sour and mouldy unless some -preservative is added. Sulphate of zinc is mainly used for this purpose. - -_Bookbinders’ Size._—I. Water, 2 quarts; powdered alum, 1 oz.; Russian -isinglass, 2 ozs.; curd soap, 40 grains. Simmer one hour, strain -through linen or a fine sieve, and use while warm. - -II. Water, 2 gallons; best glue, 1 lb.; alum, 4 ozs. Prepare and use as -above. - -III. Water, 2 quarts; isinglass, 5 ozs.; alum, 240 grains. - -_Water-proof Glue._—Solution of glue by itself or mixed with pigments -is used in painting walls in distemper. A water-proof coat is obtained -as follows: Boil 1 part of powdered gall-nuts and 12 parts of water -until the mass is reduced to two-thirds of its bulk. Then strain -through a cloth and apply the solution to the dry coat of distemper -paint, the latter becoming thereby as solid and insoluble as oil-paint. -The tannin of the gall-nuts acting only upon soft glue, the solution -has to be applied so the lower layer of glue becomes thoroughly soaked -through. - -To render _wrapping paper_ water-proof the following glue-solution may -be used: Dissolve 24 parts of alum and 4 parts of white soap in 32 -parts of water in one pot, and in another 2 parts of gum arabic and 6 -parts of glue in 32 parts of water, and mix the two solutions. Heat -the mixture, immerse the wrapping paper in it, and pass it through hot -rolls, or dry upon twine stretched in frames. - -_Fabrics may be rendered water-proof_ with glue and tannin. The process -is based on the fact that by the action of tannin or bichromates, -compounds insoluble in water are formed. It is, however, of first -importance that both solutions—tannin and glue—should fully penetrate -the fabric. If the latter is dipped directly into strong solution of -glue and then of tannin, the glue will only become insoluble on the -outside, and that which has penetrated deeper into the fibre will be -unchanged, having been protected by the superficial insoluble layer. -Hence, the treatment is commenced with a very weak solution of glue, -prepared by leaving glue broken small in hundred times its weight of -water for twenty-four hours. By that time the glue will have swelled -up, and the whole is boiled, whilst being constantly stirred, so as -to get a perfectly clear solution in which the fabric is boiled for -10 to 15 minutes. This time is no more than necessary for complete -penetration. The fabric is then well wrung between two rollers placed -over the glue-bath so that excess of solution runs back into it. The -fabric is then hung up, and when nearly dry is passed through a tannin -solution. The latter may be made from tannin itself, or from a tannin -extract, or by boiling galls or oak bark in water. The tannin solution -can be used fairly strong, as only so much of it is taken up as -corresponds to the glue present, and it can be used over again as long -as it can supply the tannin required, and can then be reinforced with -more tannin as required. - -It is not necessary for the fabric to stay long in the tannin, as it -reacts quickly with the glue. The tanned material is again hung up -to dry, and when quite dry is washed in plain water to remove any -excess of tannin. The whole process from the beginning is then twice -repeated. After this second repetition there is so thick a layer of -tannate of gelatine on the fabric that the dry cloth has acquired -considerable solidity and a smoothness which recalls that of leather. -The fabric is now passed through a stronger glue solution, using three -or even four parts of glue per hundred of water, but never exceeding -the latter limit. After the glue-bath the fabric goes through the -tannin bath, whereby it becomes quite thickly coated with tannate of -gelatine. By repeatedly treating with glue and tannin alternately, -this coating can be made as thick as desired, and finally masses are -obtained in which the texture of the fabric is entirely hidden, and -especially after the fabric has been calendered under heavy pressure -after water-proofing. The color acquired by goods thus water-proofed is -a more or less dark leather-brown. - -Muratori and Landry treat the fabric with a solution made in three -separate operations: - -1. Potash alum 100 lbs. dissolved in 10 gallons of boiling water. - -2. In another vessel 100 lbs. of glue are soaked in cold water till the -glue has trebled in weight. The remaining water is poured off, and the -glue liquefied by the application of heat. When the glue is boiling, 5 -lbs. of tannin and 2 lbs. of soda water glass are put in it. - -3. The two solutions are boiled together, being stirred constantly. - -When the mixture is complete, it is allowed to cool to a jelly. To -water-proof the goods some of the jelly is boiled with water (1 gallon -to 1 lb., or a little over) for three hours, adding water to compensate -for evaporation, so as to keep the volume of the solution constant, -as shown by tests of its specific gravity with a hydrometer. The bath -is then allowed to cool to 176° F., and the fabric is soaked in it -for half an hour and then stretched out horizontally for six hours -to drain. The fabric must be kept horizontal, so that the solution -remains uniformly distributed through it. The drainings are collected -to be used over again. The fabric is then dried in the open air or in a -drying room, still in the horizontal position. If a drying room is used -the temperature of it should not exceed 122° F. - -Muzmann and Krakowitzer dissolve 10 lbs. of gelatine and 10 lbs. of -tallow soap in 30 gallons of boiling water, and mix the solution in -4 gallons of water in which 15 lbs. of alum have been dissolved. The -whole is boiled for half an hour, and then allowed to cool to 104° -F. At that temperature the fabric is thoroughly soaked in it, dried, -rinsed, again dried, and finally calendered. In this process the alum -partially decomposes the soap, forming either free fatty acid or an -acid alumina soap. The gelatine forms an insoluble compound with the -alum. The free fatty acid or acid soap is mostly carried down on the -fibre by the precipitate formed by the alum and the gelatine. - -_Glue for Joints in Leather Driving Belts._—Soak equal parts of good -hide glue and isinglass in water for 10 hours, and then boil with pure -tannin till the product becomes sticky. The surfaces to be cemented -together should be roughened and the glue applied hot. - -According to another method 2 lbs. of best glue are dissolved at a -moderate heat in 3 lbs. of water and about 3 drachms of carbolic acid -stirred into the hot solution. The mixture is poured into shallow iron -pans to congeal, when it is cut in pieces and dried in the air. For use -the glue is liquefied by adding a small quantity of vinegar and applied -with a brush to the leather. The joint is finally pressed between iron -plates at a temperature of about 77° F. - -_Hectograph Mass._—Soak a good quality of glue for 24 hours in -sufficient cold water to cover it. Then take the swelled glue from -the water and melt it in an enameled pot over a moderate fire. When -perfectly liquid add the required quantity of glycerine (see formulas -below) and intimately mix both by continued stirring. - -The vessel containing the mixture should for some time be kept hot, so -that the mass remains thinly fluid. The purpose of this is to allow -the air-bubbles formed by stirring to rise to the surface. If any scum -is formed on the surface, remove it carefully with a shallow spoon. -The composition is then ready to be poured into the vessel intended -for its reception, which may be made especially for the purpose, or a -shallow baking pan of tin may be used. When the pan is filled with the -composition place it perfectly level in a cool place free from dust and -allow to remain at least for several hours. - -_Formulas for Hectograph Masses._—I. Gilder’s glue, 100 parts; -glycerine of 28° Bé., 500. - -The glue is allowed to swell in water, as described above, then melted, -mixed with the glycerine, and evaporated to the required consistency. - -II. Gilder’s glue, 100 parts; glycerine of 28° Bé., 400; water, 200. - - - - -CHAPTER IX. - -MANUFACTURE OF GELATINE, AND PRODUCTS PREPARED FROM IT. - - -Gelatine, like glue, is produced from hides and skins, and bones. It is -distinguished by its purity, has a slight yellowish tint, and is very -hard and elastic. In cold water it softens, swells up, becomes opaque, -but does not dissolve. In hot water it dissolves completely, and on -cooling for several hours, an almost colorless, transparent and very -firm jelly results. This property of becoming jellied is in part lost -if the solution is for some time exposed to a temperature higher than -212° F. - -The chemical constitution of gelatine is entirely changed by -concentrated sulphuric or nitric acid. Concentrated acetic acid, on the -other hand, renders softened gelatine transparent, and then dissolves -it; the solution does not become viscid, but preserves its adhesive -property. Dilute acids have no appreciable effect either on the -coagulating or the adhesive power. - -Tannin is a valuable and delicate test of the presence of gelatine. -When added to a solution containing only 1/5000th part of gelatine, -nebulosity is immediately apparent. When more concentrated gelatinous -liquors are treated with tincture or infusion of nut gall, a dense, -white, caseous subsidence occurs which, on desiccation, becomes -brownish-yellow, agglutinates, and forms a hard, brittle mass easily -reduced to powder. - -Gelatine is much used for culinary and medicinal purposes, and for -fining beer, wine and other liquids. Considered medicinally, it is -emollient and demulcent, and for this end is dissolved in water or -milk, and rendered palatable by the addition of acid and sugar. In -pharmacy, it is used for the formation of capsules intended to conceal -the nauseous odor and taste of medicinal preparations inclosed in them. -It is likewise employed for coating pills. - - -SKIN GELATINE. - -But few changes have been made in the process of manufacturing skin -gelatine since the method introduced and patented, in 1839, by George -Nelson. This patent relates to the preparation of a transparent -gelatine from waste of calf skins, and of an inferior variety from -other skins freed from hair, wool, and fleshy and fatty matters. The -mode of procedure is the same in both cases, and is as follows: The -cuttings being washed are macerated in solution of caustic soda or -caustic potash at a temperature of 60° F., until they are partially -softened. Ten days is the average period required to effect this. -They are then placed in closed vessels and permitted to remain until -a thorough softening is effected. They are now washed in a revolving -cylinder, through which a current of water passes to free them from -adhering alkali; exposed in a well-closed chamber to the action of -sulphurous acid, and finally submitted to pressure to remove the -adhering water. The softened mass bleached by sulphurous acid is then -placed in a suitable vessel and subjected to the action of steam until -it is, as far as possible, dissolved. The liquor is then strained -and set aside at a temperature of 100° to 120° F. for the impurities -which may have remained to subside. The clarified solution is poured -upon slabs of slate or marble to the depth of about half an inch and -allowed to remain there till sufficiently solidified, when it is cut, -and washed to remove all traces of acid. It is subsequently redissolved -by means of a steam bath at a temperature of 95° F., finally again -solidified, and dried by exposure to dry air upon nets. - -Messrs. J. and G. Cox, of Edinburgh, patented in 1844, a process by -which a perfectly pure substance, superior to that prepared from -isinglass is obtained. Shoulders and cheeks of ox-hides are preferred -by the patentees. They are thoroughly cleansed in water, after which -they are cut into pieces by a machine similar to that used for cutting -straw, and then subjected to the action of a paper-maker’s pulp-mill. -By this process the gelatinous fibre is well washed and cleansed, as -a stream of water flows through the mill during the whole operation, -carrying off all the impurities. The comminuted material is next -pressed between rolls, mixed with fresh water, sufficient to effect its -solution, and heated to a temperature varying from 150° to 212° F. The -resulting gelatine-solution is then allowed to cool to 150° F., and -mixed with fresh bullock’s blood—1 part of the latter to 700 parts of -solution. At a somewhat increased temperature the albumen of the blood -coagulates and rises in the form of foam to the surface, or subsides -in the shape of flakes, carrying with it the impurities, and thus -clarifying the liquor. The latter is allowed to stand for some time, -when it is poured upon stone slabs and allowed to solidify. - -G. P. Swinborne’s improved patented process for the preparation of -gelatine from hides, skins and glue pieces, relates mainly to the -cleansing of the raw material. The latter is reduced by means of -suitable instruments to shavings or slices, and soaked in cold water, -which is drained off and replaced by fresh water three times a day, -until no odor or taste is perceptible. The shavings are then heated -with water, not above boiling, strained through filter cloths, and the -liquor is then run on to slate or other material to dry. - -The modern process of preparing skin gelatine is, according to Thomas -Lambert, carried out as follows: The first treatment the cleansed skins -undergo is the “steeping” process with caustic soda or milk of lime. -In some factories a mixture of caustic (slaked) lime and soda ash is -used, in the proportion of 6 lbs. soda ash and 6 lbs. slaked lime to -every hundred-weight of skins treated, the chemical change being that -the whole of the carbonate of soda (soda ash) is converted into caustic -soda by its equivalent of caustic lime, the excess of the latter -remaining as such. The equation representing this is— - - Na_{2}CO_{3} + CaH_{2}O_{2} = 2NaHO + CaCO_{3} - Soda ash. Caustic lime. Caustic soda. Carbonate of lime. - -This steeping is conducted in large wooden vats, each having a length -of 12 feet, width 8 feet, and depth 3 feet, and fixed with a slight -gradient to the overflow, which is placed at the most convenient corner -of the vat and protected by perforated boards. The skins in the vat -are nearly covered with water, and then the solution of caustic soda, -or the slaked lime mixed in water to a cream, is sprayed equally over -the mass, the whole being intimately mixed with long stirring poles. -The water is renewed twice during a period of 12 days, the time allowed -for the skins to soak. They are now removed to a chamber, in which a -moderate increase of heat facilitates the saponification of the fat and -the dissolving of the fleshy matter. The chamber is a brick building, -with a cemented floor, on which the skins are spread to a uniform depth -of about six inches and is heated by steam pipes running round the -building. At a temperature of about 70° F. the skins are exposed two -or three days, with frequent turning. They are now transferred to the -washing machine and washed until the effluent is practically free of -soda or lime. The skins then undergo a bleaching process to whiten, and -thus destroy any injurious coloring matter. For this purpose the washed -skins are removed to a number of vats fitted with folding covers, and -treated to a solution of sulphurous acid of ½° Twaddell strength for 24 -hours, each vat being well stirred at intervals to allow the “bleach” -to permeate equally the mass. - -In some factories this process is carried out with dry sulphurous -acid, the gas being generated in a sulphur burner and, after washing, -passed into a chamber containing the skins. The vats are now drained, -then filled up with water, well stirred, and the water run off. This -is repeated until the effluent is practically free of any sulphurous -smell, and the work of dissolving the gelatine is proceeded with. -The digesting of the skins is carried on in stoutly built, circular -wooden vats, each having a size, generally of 4 feet 6 inches diameter -and 6 feet deep, and fitted with 2¼ inch copper steam coil. The vats -are provided with a double wooden bottom to divide the heat. They -are arranged on the first floor of the building, the liquors running -through a shallow filter of fine copper gauze to the clarifying vats -beneath. The skins are raised by an elevator and fed direct into the -vats by suitably-arranged troughs, then covered with water, and steam -is sent through the coils. The temperature is frequently taken by the -thermometer and should never exceed 177° F. During the digestion, -any unsaponified fat and dirt comes to the surface as a scum, and is -carefully skimmed off from time to time. Samples are also drawn of the -liquors, cooled, and the appearance and strength of the jelly noted. -After five to six hours’ heating, the first liquors are run off to the -clarifying vats, at a strength of about 17 per cent. gelatine. - -The vats are refilled with water, and a second digestion made, the -liquor running to the clarifying vats at a strength of 12 per cent. -In the third digestion the temperature is raised a few degrees to -practically exhaust the gelatinous matter, and can either be clarified -to form an inferior gelatine, or concentrated for size. The exhausted -matter is taken to the manure-shed for mixing purposes. The clarifying -of the first and second liquors—and if used for gelatine the third -liquor—is done separately in the clarifying vats. The clearing agent -used is alum, to the extent of ½ per cent., or a little blood diluted -with water; both are mixed with a small portion of the hot liquors in -a bucket, and then well stirred in the vats. The liquors are raised -to 177° F. to coagulate the impurities, and then lowered to 149° F. -and allowed to stand for two hours. During this time the coagulated -matter rises to the surface, and is skimmed off. On leaving the vats, -the liquors are filtered through fine copper gauze into a receiver from -which is fed the vacuum pan. - -Gelatinous liquors being peculiarly sensitive, especially as regards -color, to high temperatures, it is found advisable to evaporate them in -vacuo; and this method is adopted by all continental makers. The three -grades of the liquors, concentrated to the required strength, are run -on to squares of glass, 4´ × 4´, fixed in a wood framing, to a depth -of ½ inch for cake and ¼ inch for leaf gelatine, then placed perfectly -level on racks for jellying. In 24 hours the jelly is firm, and can -be easily cut to the desired size of cake or leaf wanted. A very fine -gelatine is produced by cutting the jelly into small pieces, washing -well with cold water, and remelting at a temperature of 176° F., and -poured again on the glasses for jellying. - -The drying is carried on by exposing the cut cakes, on nets fixed to -a framework of wood, to a rapid current of dry air in the tunnels, as -described in the drying of glue. - - -BONE GELATINE. - -The materials used for this purpose should be of the best description, -the most suitable bones being calves’ feet, waste of turners and button -makers, the bony cores of the horns of the ox and cow. Such bones do -not require comminution, but if large bones of oxen, horses, etc., are -to be used, it is recommended to break them as small as possible by -means of a wooden mallet, and to avoid the use of iron stampers, as the -bones become heated by the heavy blows and friction to which they are -subjected during the process, and acquire an empyreumatic odor which is -retained by the gelatine. - -The next step in the process is the solution of the glue cartilage. -This was formerly effected by the use of steam and water. The crushed -bones were placed in a wire basket or cage and this inserted in a small -cast-iron cylinder and steam introduced. The apparatus is connected -with a steam boiler, and provided with an air-tight lid, and a pipe -and a rose connected with a water reservoir for pouring water over -the bones in order to promote the solution of the glue cartilage. But -this process is very slow, 20 hours being required without completely -exhausting the bones. - -The resulting gelatinous liquor is drawn off every hour, the first run, -which contains the dirt and grease, being, of course, kept separate -from the rest. - -[Illustration: FIG. 59.] - -As will be readily understood this process consumes much fuel, and -leaves a residue which, though not completely exhausted, cannot be -further utilized for the preparation of gelatine. In fact the entire -process is obsolete, but as it is still in use in some localities, -a description is here given, for the sake of completeness, of the -apparatus and improved manner of manufacture employed in the factory of -D. J. Briers, which is well known for the beautiful product turned out. - -Fig. 59 shows a longitudinal section of the entire apparatus. - -Fig. 60 is the horizontal section of the boiler. - -_a_, is the cylindrical boiler 6 meters (19.68 feet) long, and 2 -meters (6.56 feet) in diameter. It is made of strong boiler plate -doubly riveted, and capable of resisting a pressure of six or seven -atmospheres. - -_b_, is the manhole. It is closed by an oval lid secured by two iron -rods and two bolts, so that after placing the lid in position, the -boiler is hermetically closed by tightening the nuts upon the bolts. - -_c_, is a cast-iron fork with two safety valves with levers graduated -from 1 to 100 atmospheric degrees. - -[Illustration: FIG. 60.] - -_d_, is a float upon the surface of the water, and provided with a -wheel graduated from Nos. 1 to 6. Its object is to indicate during the -operation how much water is lost and how much remains in the boiler. -Care must be had not to allow the indicator of the wheel to get below -No. 1. This figure indicates that the water has reached the highest -point in the boiler exposed to the fire, which is consequently the -lowest point which the water can be allowed to reach. On the other hand -the indicator must not move above No. 6, as the water when standing -too high in the boiler and too close to the pipes conducting the steam -into the various apparatuses might mix with the steam and spoil the -operation carried on in the drum, _e_, Fig. 60. - -_f_, Fig 60, is a manometer, which indicates the degrees of pressure -exerted by the steam in the interior of the boiler. It consists of -a wrought-iron pipe bent double, and is filled with mercury 1.22 -meter (4.002 feet) high counted from its base. One end of the pipe -communicates with the boiler, while the other end is provided with a -small brass wheel. Upon the latter is a thread of twisted silk, to -the end of which is suspended an iron cylinder of somewhat smaller -circumference than the bore of the pipe, so that it can move up and -down in it without friction. This cylinder rests always upon the -mercury. To the other end of the thread is fastened an indicator of -somewhat less weight than the cylinder, which, by sliding in a groove -in a graduated board placed alongside the pipe, indicates the degrees -of steam pressure. - -_g_ is a cast-iron pipe for heating the drying room, and - -_h_ another cast-iron pipe for heating the store-room for the bones. - -_i_ is the forcing pump for feeding the boiler with water. - -_k_ is a sheet-iron reservoir placed close to the end of the boiler. -It is filled with water, which is heated by the heat lost in the -fire-place in consequence of the draught, and by allowing the smoke -to circulate under the reservoir before passing into the chimney. The -reservoir communicates with the forcing-pump by means of a pipe and -stopcock, so as to avoid feeding the boiler with cold water. - -_l_ is the fire-place, consisting of the grate, door and cast-iron -frame. - -The drum, _e_, is a spherical vessel of strong sheet-iron doubly -riveted. It is 3 meters (9.84 feet) in diameter, and capable of -resisting a pressure of six to seven atmospheres. It serves for -softening the bones with the assistance of steam passed into it from -the boiler, _a_. It is provided with a manhole similar to that of the -boiler. - -_n_ is a wrought-iron shaft passing horizontally through the drum and -revolving in the brasses, _o_. - -_g_, Fig. 61, is a gearing with a crank, by means of which the drum _e_ -is revolved. The power of the gearing must be so calculated that one -man can turn the wheels when the drum is filled with water. - -[Illustration: FIG. 61.] - -_r_ is a false bottom perforated in its entire length with holes 12 -millimeters (0.47 inch) in diameter, and is placed about 15 centimeters -(5.9 inches) above the true bottom of the drum. It consists of two -pieces, and is secured by two nuts, so that it can be easily removed -and replaced. Its object is to prevent the bones from clogging up the -pipe _s_, and the cocks _t_, _u_. - -_a_, _a_, Fig. 61, are angular iron points inside of the drum _e_. -Their object is to facilitate the shifting of the bones when the drum -is revolving. - -_x_, Fig. 59, is a cock near the manhole. It is opened about 2 -millimeters (0.079 inch) during the operation in the drum. It serves -also for the escape of the steam from the drum when the operation is -finished. - -The cocks _t_, _u_, placed in the lower part of the drum, serve for the -escape of steam condensed during the operation. - -The steam pipe _p_, Fig. 59, conducts the steam from the vessel _a_ -into the drum _e_. - -_y_, Fig. 59, is a cock graduated into eight equal parts and placed -on the steam pipe _p_, to conduct the steam from the box _z_, into the -stuffing box _a´_, and from there into the pipe _s_, then under the -false bottom _r_, into the drum _e_. - -The lid of the cast-iron box _z_, is provided with a safety valve -loaded with a weight corresponding to the pressure of one atmosphere. - -The wooden vessel or box _d_, the ground-plan of which is shown in Fig. -62, serves for boiling the comminuted bones in order to extract the -jelly. This box consists of the following parts:— - -[Illustration: FIG. 62.] - -_n_, are cast-iron steam pipes occupying the entire surface of the box, -being placed at equal distances from each other, and connected on their -ends by semicircular pieces. The steam, which is allowed to circulate -in the pipes in order to boil the liquid, enters through one of the -ends which rises up vertically and is connected with the cock _h´_, -Fig. 59. The other end is secured to the inner side of the box, which -is perforated for the admittance of the cock _o´_. Upon the steam pipes -lies a wooden framework with linen nailed upon it, the object of which -is to prevent the comminuted bone substance from falling under the -pipes. The frame must, of course, fit closely into the box. - -The cock _h´_ graduated in eight equal parts serves to admit steam into -the pipes _n´_, and is opened either entirely or half, or one-quarter, -or one-eighth, according to the stronger or gentler ebullition to be -produced. - -To prevent the steam from becoming stagnant in the steam pipes _n´_, -a small jet is allowed constantly to escape through the cock _o´_. The -latter serves also to run off the condensed steam when it no longer -possesses the heat required to keep up ebullition. - -_p´_, Fig. 62, is a cock in the bottom of the box _d´_ for drawing off -the gelatinous solution from the residue. The box _e´_, Fig. 62, a -ground-plan of which is shown in Fig. 63, serves for evaporating the -gelatinous solution, which is effected by circulating steam through -several tubular pieces of cast-iron which form the bottom of the box -and are connected in a similar manner as the pipes in the box _d´_. - -The cock _i_ is graduated and similar to _h´_. - -[Illustration: FIG. 63.] - -The cock _r´_, Fig. 63, is similar to _o´_, Figs. 59 and 62. - -_s´_, Fig. 63, is a cock for drawing off the evaporated gelatinous -solution. - -The wooden box _f´_, Fig. 59, a ground-plan of which is shown in Fig. -64, serves for the reception and settling of the evaporated gelatinous -solution. Its bottom is constructed in a manner similar to that of the -box _e´_. - -[Illustration: FIG. 64.] - -The cock _n´_, which is placed 14 millimeters (0.55 inch) above the -bottom of the box, serves for running the gelatinous solution into the -wooden cooling-boxes. - -The bones as received in the factory are sorted by throwing out the -spongy material, etc. They are then steeped in lime-water for a few -days to free them from adhering particles of flesh, after which they -are dried and stored away for future use. - -The boiler _a_, is filled two-thirds with water, and heated until the -manometer indicates a pressure of 30°. In the meanwhile the drum _e_, -is filled seven-eighths with perfectly dry bones, and steam is then -admitted from the boiler _a_, through the graduated cock _y_. The fact -that the bones in the drum are exposed to the proper temperature of -250° F. is recognized by the thermometer _b´_, placed between the cock -and the drum. - -To prevent the stagnation of the steam in the drum, _a_ small jet of -it is allowed constantly during the operation to escape through the -cock _x_. The cock must not be opened wider than is necessary to keep -the temperature at 250° F. By opening it wider, this degree would be -exceeded, and the gelatine-yielding substance would, in consequence, -undergo alteration. A quarter of an hour after admitting the steam into -the drum, the cock _t_, is opened, and again closed after allowing a -small portion of the condensed steam to escape to the cock _u_, and, -through this, into a box. This operation is repeated every quarter of -an hour. - -To change the position of the bones, the drum is revolved twice every -half hour, by means of the gearing _q_, of course closing the cock _x_ -during the operation. - -By carefully following the above rules, the bones will be thoroughly -reduced in four hours. If, for instance, steam has been introduced into -the drum at 5 o’clock a. m. the operation will be finished at 9 a. m. -The cock _y_, is then closed, and the steam allowed to escape through -the cock _x_. After the escape of the steam, the drum is emptied, by -removing the lid and turning it upside down. It is then refilled with -entirely dry bones, and the operation continued in a like manner, day -and night, if necessary. - -After the bones have been taken from the drum, they are spread out -under a shed, and, when dry, ground in a suitable mill. The resulting -flour, which contains the jelly-yielding substance, is brought into -the vessel _d´_, which, in the meanwhile, has been furnished with -sufficient water to cover the flour 65 centimeters (25.59 inches) deep. -The mixture is boiled for three-quarters of an hour, being constantly -stirred to prevent the flour from forming a heavy and dense mass -which would hinder the quick extraction of the jelly. Ebullition is -then interrupted by closing the cock _h_, and the fat floating on the -surface skimmed off. After allowing the gelatinous solution to settle, -it is drawn off by means of a faucet placed above the level of the -flour. Thirty bucketfuls of the gelatinous solution are then at once -poured into a vat and mixed with the condensed steam drawn off by means -of the cocks _t u_, during the reduction of the bones in the drum. -After allowing the mixture to cool to 160° to 155° F., 20 kilogr. (44 -lbs.) of pulverized alum are added at once and as quickly as possible. -When the gelatinous solution has become transparent, it is drawn off -into the box _e´_, and a few bucketfuls of hot water are poured upon -the sediment in the vat in order to extract the remaining jelly, which -is effected by thorough stirring and allowing to settle until the water -is entirely clear. - -After disposing of the 30 bucketfuls in the manner mentioned, -the remainder of the gelatinous solution is evaporated. This is -accomplished in the box _e´_, which is filled 8 centimeters (3.15 -inches) deep with gelatinous solution, and steam is then admitted -into the tubular bottom pieces. To promote evaporation and keep the -fluid constantly in motion, the cock _i´_ is only opened far enough -to keep up gentle ebullition. During evaporation the solution should -be frequently stirred with an implement resembling a rake. The nearer -the required degree of concentration is approached, the greater care -must be exercised to prevent the solution from boiling too strongly. -The proper degree of consistency is obtained when half a saucer full -of the solution placed in a shady place in the air acquires in a short -time such a consistency that when touched with the finger no impression -remains. The cock _i´_ is then closed, and the jelly is drawn off into -the box _d´_, which contains the 30 bucketfuls of clarified jelly, -care being had to mix the two solutions as quickly as possible. After -evaporating all the gelatinous solution and mixing it in the box _d´_, -the whole is heated to 158° F., by admitting steam through the cock -_k´_, care being had not to forget closing it as soon as the above -temperature has been reached. The solution is then thoroughly stirred -and permitted to settle for three hours to allow of the precipitation -of the lime salts decomposed by the alum. The fluid, which is now -perfectly transparent and of a beautiful dark-yellow color, is then -drawn off into wooden cooling boxes 2 to 2.5 meters (6.56 to 8.2 feet) -long, 20 centimeters (7.87 inches) wide, and 16 centimeters (6.30 -inches) deep. The following day the gelatine is cut into leaves 25 -centimeters (9.84 inches) long and 12 centimeters (4.72 inches) wide, -which are dried upon nets. When quite dry, the drying process is -finished by bringing the leaves into the drying-room which is heated by -the pipe _g_. (Fig. 59.) - -The bone flour remaining in the box _d´_ still contains much jelly, -which is extracted by pressure. This is accomplished immediately after -running off the gelatinous solution into the evaporating vessel. The -liquid which has drained through the cloth frame previously mentioned, -is drawn off by opening the cock _p´_, Fig. 62, while the residue -in the box _d´_ is placed in coarse bags and the jelly extracted by -subjecting the bags to strong pressure under an iron screw-press. -Before mixing the extracted fluid with the solution in the evaporating -vessel, it is recommended to allow it to settle, as it is always more -or less turbid. The residue remaining in the bags is an excellent -manure. - -The modern process of preparing bone gelatine, which is now almost in -general use is as follows: Clean bones are selected for the purpose, -and the operation commences with the extraction of the fat by means -of benzine, though some manufacturers prefer carbon disulphide as a -solvent, because it is claimed that by reason of its low boiling-point -it does not injure the gelatine in the same manner as benzine, and -besides it leaves no smell in the degreased bones. It is advisable -to bleach the degreased bones, spread out in thin layers and kept -constantly moist, by exposure to the action of air and light. The -bleached bones are conveyed to large vats for the purpose of extracting -their mineral constituents by digestion with hydrochloric acid. If -the gelatine is to be used as an article of food, or for medicinal -purposes, only the purest hydrochloric acid obtainable should be used, -while the ordinary article suffices for that for technical purposes. - -The vats are filled three parts full with bones and the latter covered -with a solution of hydrochloric acid of 10 per cent. strength. -Digestion is carried on until the bones become soft, flexible and -semi-transparent. The acid water is now drained off, and a supply of -fresh water added, and then discharged. This is repeated until the last -water is entirely free of acid, which is known by adding a few drops of -silver nitrate, the absence of any white precipitate indicating that -the water is entirely free of acid. - -The bones are now bleached in the manner as described under -skin-gelatine, preferably with solution of sulphurous acid, the -process with gaseous sulphurous acid being difficult to carry out and -considerable time is required for the gas to completely permeate the -cartilaginous mass. The bleached bones are then conveyed to the boiling -vats and the resulting liquors treated in the same manner as described -under skin-gelatine. - -As bone-gelatine solidifies with a larger content of water than the -product from skins, evaporation of the liquors may be early interrupted -and the resulting jelly cut into thin leaves which are finally dried. - - -COLORED GELATINE. - -Cakes or leaves not entirely colorless may be utilized for colored -gelatine which is employed for various purposes. Coloring is effected -by simply dissolving and distributing uniformly a suitable quantity -of coloring matter in the clarified gelatine liquor previous to -solidifying; of course only water-soluble coloring matter should be -used. - -Colored gelatines are frequently used by confectioners and in the -household in the preparation of jellies, and the use of poisonous -colors should under all conditions be avoided. Sufficient attention is -not paid to this, because many of the aniline colors which are now so -much used for the purpose are at least open to suspicion, while others, -especially picric acid, which yields a beautiful yellow color, are -decidedly poisonous. - -The following coloring matters are perfectly harmless and yield good -results in coloring gelatine: - -_Yellow_: Caramel or sugar color. A still more beautiful yellow is -obtained by the use of an aqueous extract of saffron. - -_Red_: Extract of cochineal. - -_Blue_: Indigo-carmine solution. - -_Green_: Mixture of indigo-carmine and caramel. - -_Violet_: Mixture of extract of cochineal and indigo-carmine. - -While gelatine colored with the above-mentioned coloring matter does -not present such a beautiful appearance as the product colored with -aniline colors, it is entirely harmless and suitable for culinary -purposes. - -Leaves of gelatine colored with aniline colors exhibit beautiful colors -and are used for many technical purposes. The following colors may be -employed: - -_Yellow_: Picric acid soluble in hot water. - -_Red_: Fuchsine or eosine. - -_Blue_: Water-soluble blue. - -_Green_: Iodine green. - -_Violet_: Methyl violet. - - -_Gelatine for Fining Purposes._ - -For fining beer, wine, etc., gelatine in leaves or in powder is brought -into commerce. For the preparation of leaves, gelatine particularly -well dried is carefully melted over a water-bath and then ladled into -sheet-metal moulds, and allowed slowly to solidify. - -The product brought into commerce under the name of _Gelatine Lainée_ -which commands a high price is in many cases nothing but thoroughly -purified bone-glue of a dark honey-yellow to brown color. - -Fining powder for wine and beer is made by grinding off-color gelatine -cakes and freeing the resulting powder from coarser pieces by sifting. -The powder is white. - -_Liquid fining gelatine._ This preparation consists of -gelatine-solution suitably prepared, and represents a colorless, or at -the utmost slightly opalescent, product just sufficiently concentrated -to remain liquid. - -Skin-liquors can only be used for the preparation of liquid gelatine, -as bone-liquors already gelatinize when they contain scarcely more than -1 per cent. of glue. The skin liquors are concentrated so far as to -remain liquid at a temperature of from 60° to 68° F. - -A product answering all demands is obtained as follows: A good quality -of gelatine of a pale color is dissolved in a sufficient quantity of -water, the solution, in case it shows a slight odor, filtered through -animal charcoal, and then brought into bottles. To prevent putrefaction -the liquid gelatine is sterilized as follows: - -The filled bottles being placed in a boiler filled to a proper depth -with water, the latter is slowly brought to boiling which is kept up -for 15 to 20 minutes. The bottles are then closed with corks previously -boiled in the water. - - -_Preparation of Gelatine from Ordinary Glue._ - -For this purpose ordinary pale-colored glue is allowed to swell up -for two days in cold strong vinegar. The vinegar is then drained off -and the glue which is now almost colorless, is placed upon a sieve and -allowed to float in a vessel filled with water for 10 to 12 hours. It -is then placed upon a linen cloth, stretched in a room heated to at -the utmost 68° F., allowed to drain and dry to such an extent that -on heating it to between 158° and 167° F., a thick clear liquid is -obtained. This liquid is carefully poured upon plates of glass or -marble, so as to avoid the formation of air bubbles and when solidified -the leaves are removed and completely dried in the air. The product -thus obtained being entirely tasteless and almost colorless may be used -in the preparation of jellies, as well as for foils for pictures, etc. - - -_Preparation of Gelatine for Photographic Printing and for Photographic -Purposes in General._ - -Gelatine suitable for this purpose should be colorless and free from -all salts, since the latter would exert a disturbing effect upon the -chemical processes which take place during the photographic operation. -For the removal of the salts the gelatine is treated as follows: -Colorless gelatine of the best quality is broken into small pieces and -covered with 10 to 12 times the quantity of water, the latter being -changed every 15 to 20 minutes until the last water shows no trace -of lime, which is known by adding to the water solution of oxalate; -the absence of turbidity indicates that the water is free from lime. -The white of an egg is now mixed with five drops of ammonia and twice -the volume of distilled water and shaken to froth in a bottle. This -quantity suffices for 6 to 8 ozs. of gelatine. The washed gelatine is -next melted in a dish and mixed with the white of egg. One part of -glacial acetic acid mixed with 250 parts of water is then added drop -by drop, stirring constantly until sensitive litmus paper shows an -acid reaction. The liquid is now rapidly brought to the boiling-point, -whilst stirring constantly, and then filtered in a warm place to avoid -gelatinization. The gelatine now contains only the salts of the white -of egg, some ammonium acetate and free acetic acid. For their removal -the solidified gelatine is cut into pieces, which are placed in water. - - -_Gelatine Capsules for Medicinal Purposes._ - -Considerable use is made of gelatine in medicine. To disguise the -disagreeable taste of some medicines they are either mixed with -gelatine solution or inclosed in gelatine capsules. To prepare the -latter, dissolve 8 parts of gelatine, 2 of sugar, and 1 of gum-arabic -in 8 of water in a water-bath, and dip the pear-shaped ends of iron -rods into the lukewarm solution. To facilitate the detaching of the -gelatine film from the rods, grease the pear-shaped ends with oil. The -capsules are dried by placing them in holes of a corresponding size -in boards. When dry they are filled with the respective medicine, and -closed with a drop of the same solution. - - -_Court Plaster._ - -Gelatine or isinglass 155 grains, alcohol 13½ fluid drachms, glycerine -15½ grains. Water, tincture of benzoin, each a sufficient quantity. -Dissolve the gelatine in a sufficient quantity of hot water to make the -solution weigh 4½ ozs. Spread one-half of this in successive layers by -means of a brush upon taffeta stretched upon a frame so as to present -a level surface, waiting after each application until the layer is -dry. For the first two applications the gelatine solution should be -warmed merely to above its congealing point, so that when spread out -it may rapidly solidify and at the same time adhere to, but not pass -through the fabric. Mix the second half of the gelatine solution with -the alcohol and glycerine, and apply it in the same manner. Then -reverse the taffeta, coat it on the back with the tincture of benzoin -and allow it to become perfectly dry. The tincture of benzoin applied -to the reverse side leaves a thin layer of resin which in a measure -renders the plaster water-proof; it is, however, advisable to repeat -this application once or twice. The addition of glycerine to the last -portion of the gelatine solution prevents the plaster from breaking, -and preserves its flexibility for a long time. When the plaster is dry -it is cut in pieces of suitable length and preserved in well-closed -vessels. - - -_Gelatine Foils._ - -Large quantities of gelatine foils, which are leaves of gelatine about -as thick as a sheet of paper, are produced in England and France where -their manufacture forms a special branch of industry. They are either -simply colored or printed with neat designs in gold or silver. - -The fabrication is quite simple. Cover pure gelatine with water, and -after swelling up, pour off the water and dissolve the jelly over a -water-bath. After allowing the solution to cool somewhat, add the -coloring matter previously dissolved in water. - -In place of pure gelatine, a solution of ordinary bone-glue may be -used. In order to clarify it add O.14 oz. of oxalic acid dissolved in -water to every 5.5 lbs. of glue. To make the foils more flexible add -also one-half pint of spirit of wine and O.28 oz. of rock candy or a -small quantity of glycerine. - -Aniline colors soluble in water are best adapted for coloring the -foils; for _red_, fuchsine, eosine or ponceau, for _blue_, _blue de -Parme_, for _green_, aldehyde green, for _yellow_, picric acid, and for -the various shades, mixtures of the above colors. - -A durable blue is also produced by indigo solution, yellow, by -decoction of saffron, green, by mixing blue and yellow, red, by a -solution of carmine in spirit of sal ammoniac, and violet, by mixing -blue and carmine. - -The gelatine solutions are poured upon ground-glass plates, previously -polished with elutriated rouge, and rubbed with Spanish chalk. The -foils are so smooth upon the glass side that when dry they can be -detached without much difficulty. If both sides are required to be -smooth, the foils are dried between two glass plates. In many respects -their manufacture resembles that of “Gelatine Veneers.” - -Gelatine foils are used for printing sacred images, visiting cards, -labels, in the manufacture of fancy articles, artificial flowers, etc. - -For the manufacture of artificial flowers very soft and flexible sheets -are made by adding ½ part of glycerine to 1 part of gelatine and mixing -intimately in dissolving the gelatine. - -Such gelatine sheets brushed over in addition with Peruvian balsam can -also be advantageously used for tying up wounds instead of gutta-percha -cloth which tears easily and rots soon. They form an air-tight bandage -which clings closely to the parts of the body, and beside the glycerine -contained in them exerts a beneficial cooling effect and acts as an -antiseptic. - - -_Gelatine Veneers._ - -Franchi, as far back as 1814, prepared artificial ivory by mixing -gelatine solution with earthy substances. This idea has been again -taken up in modern times for the manufacture of veneers imitating -not only ivory, but also avanturin, lapis lazuli, malachite, -mother-of-pearl, and tortoise shell. These imitations are much liked by -manufacturers of fancy articles, workers in leather, cabinet-makers, -etc. They are prepared as follows:— - -The process may be divided into five principal operations: 1. -Preparation of the glass and marble plates; 2. Preparation of the -glue solutions; 3. Pouring the colored solutions upon the plates; 4. -Transferring the layer of glue to the layer of gelatine; and 5. Drying -the veneers and detaching them from the plates. - -1. _Preparation of the plates._ Both marble and glass plates are used -for imitations of marble, but glass plates only for imitations of -mother-of-pearl. The glass plates must be ground, but need not exceed -O.11 to O.15 in. in thickness, and only require careful washing and -drying for imitations of mother-of-pearl. For imitations of marble -they should be rubbed with an oiled linen rag. Other glass plates, -after being washed and polished with elutriated rouge and water, are -wiped with a soft rag to remove any particle of the polishing powder. -The polished surface is then gently rubbed with a rag dipped in pure -Spanish chalk, and the excess of chalk carefully dusted off. - -2. _Preparation of the glue solutions._ For one dozen plates, each 10¾ -square feet, soak 2 lbs. of good, colorless glue in water for 24 hours, -pour off the water and melt the glue in a water-bath and stir in 3½ -ozs. of glycerine. For imitating marbles of two colors, compound 20 to -24 fluidounces of this glue solution with the quantities of thoroughly -ground mineral colors given below; the rest of the glue solution is -mixed with 6.34 ozs. of zinc white ground very fine. For imitating -marble of three colors mix 14 fluidounces of the glue solution with -one of the coloring matters and 14 fluidounces with the other coloring -matter, and the remainder with zinc white. For imitating marble with -four colors, take 10 fluidounces of the glue solution to each of the -three coloring matters, and mix the rest with 4½ ozs. of zinc white. - -The proportions by weight of the mixtures for 10 different varieties of -imitations of marble and enamel are as follows:— - -_a._ Mix 20 fluidounces of the glue solution with 1¾ ozs. of rouge and -2½ ozs. of zinc white, and the rest of the glue solution with 6⅓ ozs. -of zinc white. - -_b._ Mix 20 fluidounces of the glue solution with 1¾ ozs. of rouge, and -the rest of the glue solution with 5¼ ozs. of zinc white. - -_c._ Mix 14 fluidounces of the glue solution with 1¼ ozs. of zinc white -and 1 oz. of rouge, 14 fluidounces of the glue solution with 1 oz. of -yellow ochre, and the rest with 5¼ ozs. of zinc white. - -_d._ Mix 14 fluidounces of the glue solution with 1 oz. of rouge, 14 -fluidounces of the glue solution with ¾ oz. of sepia, and the rest with -5¼ ozs. of zinc white. - -_e._ Compound 20⅓ fluidounces of the glue solution with 1 oz. of quite -concentrated and filtered solution of aniline black, and the rest with -6⅓ ozs. of zinc white. - -_f._ Mix 10 ozs. of the glue solution with 0.8 oz. of rouge, 10 -fluidounces of the glue solution with 0.8 oz. of yellow ochre, 10 -fluidounces of the glue solution with 0.8 oz. of sepia, and the rest -with 4¼ ozs. of zinc white. - -_g._ Mix 20.3 fluidounces of the glue solution with 1.41 ozs. of -lampblack. For gray add sufficient zinc white to produce the desired -shade. The rest of the glue solution is mixed with 6⅓ ozs. of zinc -white. - -_h._ Mix 10 fluidounces of the glue solution with 0.8 oz. of umber, 10 -fluidounces of the glue solution with 0.8 oz. of bole, 10 fluidounces -of the glue solution with 0.8 oz. of ochre, and the rest with 4½ ozs. -of zinc white. - -_i._ _For enamels_ mix 20.3 fluidounces of the glue solution with 1 oz. -of ultramarine, and the rest with 6⅓ ozs. of zinc white. - -_k._ Mix 20.3 fluidounces of the glue solution with 1.41 ozs. of chrome -green, and the rest with 6⅓ ozs. of zinc white. - -For imitating mother-of-pearl veneers, 0.42 oz. of silver bronze, which -need not be genuine, is ground with a little glue solution or water and -intimately mixed with the above solution of glue. The bronze powder -must not be in a dry state when stirred into the glue, as lumps would -be formed and the veneers become spotted. In place of bronze, essence -of fish scales, which is of course far more costly, can be used.[2] The -glue solution thus prepared is then compounded with different aniline -colors according to the tint desired. - -[2] This preparation is also known by the name _Essence d’Orient_. The -material for its production is furnished by a small white fish very -common in the rivers of continental Europe. It accompanies the scales -of this fish, and is detached when the scales are triturated for a -considerable time and thrown into a vessel of water. To collect the -essence the water is poured off upon a fine hair sieve, which retains -the scales and allows the water and the product sought to pass through. -The latter sinks to the bottom, and is obtained pure by decanting the -water. A little ammonia is added to prevent decomposition. - -_a._ For yellowish veneers no coloring matter is required, or the -desired shade is obtained by an addition of some solution of picric -acid. - -_b._ For colorless veneers or those of slightly reddish tints a smaller -or greater number of drops of a concentrated solution of fuchsine are -added in order to counteract the yellowish color of the glue solution. -For these imitations of mother-of-pearl veneers, concentrated solution -of gelatine compound with 15 per cent. of glycerine can be employed, -especially when essence of fish scales is used. - -_c._ For _blue_, the glue solution is compounded with _bleu de Lyons_, -care being had not to use too much, as otherwise the imitation becomes -indistinct. The proper degree of coloring is tested by allowing a few -drops of the colored glue solution to fall upon a glass plate. - -_d._ For _red_, solution of fuchsine or carmine is used, the latter -being obtained by dissolving commercial carmine powder in alcohol. - -_e._ _Orange colors_ are produced by an addition of solution of -_chrysaniline_ generally sold under the name of Victoria orange, and -_violet_ by adding aniline violet. For these, as well as for the -solution colored with fuchsine, the plates must _not_ be rubbed with -oil, as even the smallest trace of the latter discolors these colors in -drying, or at least the veneers will show spots without color. - -3. _Pouring the colored solutions of glue upon the plates._ For -imitations of marble and enamel, the glass plates, after rubbing with -oil, are placed, rubbed surface up, in a perfectly level position. -The proper portion of the white ground-mass, after becoming somewhat -thickish, is then poured upon the plates, and the gaps left free in -pouring filled in and smoothed with a knife-shaped tool of horn or -bone. Upon this white ground the respective colored glue solutions -are then poured in a zigzag form, and in conformity with the desired -design, drawn through the ground-mass with a glass rod. If several -differently colored glue solutions are to be applied, as given, for -instance, under 2_f_, they should be poured in quick succession, so -that the succeeding color runs into the preceding, and a white strip -or spot remains between each color. The whole is then intermingled -by the glass rod, according to the design. If the latter is to have -sharply defined lines and spots, the respective colored solution of -glue is used somewhat thicker, but if, on the other hand, the design is -to be somewhat blended, the glue solutions are used somewhat warmer, -and consequently more thinly fluid. After solidification of the glue -solutions the plates are placed in a cool room for two or three hours. - -Imitations of malachite are prepared in a similar manner. Four glue -solutions of different shades of green from the darkest to the lightest -tint are prepared and poured upon a slightly greenish ground, so as -to imitate the characteristic curves and veins of malachite, which -are then further traced with a comb with teeth standing at unequal -distances from each other. - -The glass plates set aside to be used for imitation of mother-of-pearl -are now taken in hand. The solutions of glue are kept warm over a water -bath and thoroughly stirred every time before pouring them upon the -plates. The formation of a film on the surface of the glue solution -must be strictly avoided. - -For pouring out the solutions it is best to use a porcelain vessel -provided with a spout and handle, and having a capacity of about 6¾ -fluidounces. The portion of glue solution required for each plate -(1¾ flu. oz.) is then measured into one of the porcelain vessels, -and, after standing a short time, poured upon the plate and uniformly -distributed. The production of a mother-of-pearl design requires some -skill and practice. A comb with teeth set ½ inch apart is used. It is -held in a somewhat oblique position, the teeth are gently pressed upon -the glass plate, and, with frequent turnings of the comb at a right -angle, cycloidal motions executed. The operation is carried on from the -front to the back edge of the glass plate, and when the glue begins to -thicken on the edges, continued at the softer places until the desired -design is produced, care being had not to touch places which have -already acquired a certain degree of solidity, as this would mar the -pattern. After treating all the plates in this manner, they are set -aside in a cool room for two or three hours. - -4. _Transferring the layer of glue to a layer of gelatine._ For each -dozen of veneers soak 2½ ozs. of gelatine, and then melt them in a -water-bath, and after adding glycerine equal to 10 per cent. of the dry -gelatine, let the mixture settle. - -The glass plates treated with rouge and Spanish chalk are now placed in -a perfectly level position, and after pouring 5½ fl. ozs. of gelatine -solution upon each of them, the gaps left in pouring are filled in -and smoothed with the glass rod. The front edge of a plate covered -with a colored layer of glue is now, glue side down, placed upon the -front edge of a gelatine plate, while the back edge of the former is -gradually lowered until the glue plate lies firmly upon the gelatine -plate. - -It may here be remarked that the gelatine solution must only be allowed -to cool off sufficiently to prevent the melting of the glue plate on -touching it. If it is cooler the veneers will have blisters. It must -further be looked to that, before placing the first plate upon the -gelatine plate, no gelatine escapes, and that any excess only runs off -after the back edge of the glue plate touches that of the gelatine -plate. - -The plates are now allowed to rest quietly until the gelatine is -congealed, when they are removed to a cool place where they remain five -or six hours. - -Imitations of mother-of-pearl are treated in the same manner with the -exception that the gelatine solution is colored with the same coloring -matter as the glue solution. For colorless or yellowish veneers the -gelatine solution is not colored. - -After six hours the first glass plate is detached from the layer of -glue by loosening the latter around the edges with a knife blade, and -the plate gradually lifted off commencing at one corner. With some care -and skill, this operation is readily accomplished without detaching the -gelatine mass. - -5. _Drying and detaching the veneers._ The veneers with the gelatine -layer still adhering to the glass plate are now dried. This is done -in a heated room in which the veneers are arranged upon frames so -that they stand almost perpendicular. The hot air for heating the -room enters near the ceiling while the moist air is drawn away near -the floor. The temperature of the lower zone where the fresh plates -are placed should not exceed 68° F. The plates are moved up higher -every day until, on the third or fourth day, they have become entirely -dry. Before removing the veneers from the drying-room they should be -tested in regard to their dryness. They are sufficiently dry, when, on -pressing the finger nail upon the glue, no impression is made. - -After removal from the drying-room the plates are allowed to cool off -for at least two hours before detaching the veneers. The operation -begins by detaching the gelatine layer on the edges with a very thin -knife blade. The operator then takes hold of one corner of the veneer -and draws it gradually and carefully from the glass plate. After -trimming the edges the veneers are ready for use. - -If the veneers are required to resist the action of water, mix with the -solution of gelatine compounded with glycerine ⅓ fl. oz. of a solution -of 5 parts of chrome-alum in 100 of water to every plate, and immerse -the veneers for a short time after they have been detached from the -first plate, in a similar solution of chrome-alum. - -Veneers prepared by these methods can be used for various purposes in -architecture and in the manufacture of furniture. Tennessee and other -marbles have been so closely imitated, that when used for table plates, -etc., the fact of their being imitations could only be detected by the -closest scrutiny. The veneers are also much used for fancy and inlaid -work, for coating columns, etc. To prevent their blistering and coming -off, it is recommended to add one-quarter of its weight of glycerine to -the glue with which they are to be attached to the articles. - - -_Formo-Gelatine._ - -This product is used as a dressing in surgery, and, according to -Samuel Rideal, is obtained as follows: Gelatine in aqueous solution is -precipitated by formaldehyde H.COH, or CH_{2}O, as a substance which on -drying is a white powder, neutral, inodorous, and insoluble in water -and dilute chemical agents. In commerce formaldehyde is met with in -aqueous solution as “formalin” containing 40 per cent. of formaldehyde. -If 1 Cc. of formalin be added to 200 Cc. of a 5 per cent. gelatine -solution, the latter is changed into a gelatinous mass, not melted by -heat nor reduced by water. If a smaller quantity of the formalin is -added (1 in 1000; the jelly is said to be meltable, but with a higher -tenacity) when dried it becomes insoluble in warm water. Formalin in -less proportion, though it does not prevent the dried gelatine from -dissolving in warm water, is said to improve the “body” of the jelly -and its keeping qualities, and also the tenacity of the glue. The -results of investigation show that with up to 1 per cent. of formalin -the solidity of the jelly increases; above that it declines. Up to -0.02 per cent. (1 in 5,000) it redissolves in water after drying. -Even with this small proportion the firmness of the jelly is sensibly -increased. The English patent, 4,696, 1894, claims the addition of -formalin during the manufacture of size and glue in such proportion -that the product shall liquefy in warm water. - -In examining commercial sheet gelatines for printers’ and photographic -use, they were often found to contain small quantities of formalin. -It seems to improve the quality, a very small percentage increasing -the tenacity, flexibility and keeping qualities, while not affecting -the transparency or rendering the material acid. When applied to -articles that may be used as food, a strength of 1 in 50,000 in the -final prepared product is not injurious to health, but should not be -exceeded. (Rideal and Foulerton, _Public Health_, May, 1899, p. 568.) - -Zimmermann applies dilute formaldehyde mixed with glycerine, vaseline, -oil or yolks of eggs, with or without flour, to the surface of -photographic films which are claimed to be thereby rendered more -pliable and not so hard as when the formalin is applied by itself. - -It will be seen that formaldehyde in more than traces renders gelatine -insoluble; the product, moreover, is almost unaffected by water, is -more or less hard and elastic and, owing to the antiseptic properties -of the formaldehyde is nearly imperishable. - - -_Use of Gelatine in Bacteriology._ - -Gelatine fit for this purpose must be clear and bright, fairly neutral -and of high gelatinizing power. For bacteriological purposes a 10 to 20 -per cent. solution of gelatine in sheets or strips is made with meat -broth, and this nutrient jelly, which is obtained by clarification with -albumen perfectly clear and bright, forms a most useful medium for the -cultivation of micro-organisms. - - -_Artificial Silk from Gelatine._ - -For the production of textile threads, Millar utilizes the property of -gelatine solution mixed with potassium dichromate, becoming insoluble -on exposure to light. For this purpose a clear solution of gelatine is -mixed with solution of potassium dichromate in the proportion of 100 -parts of gelatine to 2 or 2½ parts of potassium dichromate. The fluid -should be of such a consistency as to allow of its being drawn out into -fine threads which on exposure to light become insoluble. Silk woven -from such threads is equal in appearance to the genuine article but of -course is not so strong. It is affected by moisture, becoming limp, but -regains its normal strength when dry.[3] - -[3] For further information on this interesting subject, the reader is -referred to “Cellulose and Cellulose Products.” By Dr. Joseph Bersch. -Henry Carey Baird & Co., Philadelphia, 1904. - - - - -CHAPTER X. - -ISINGLASS AND ITS SUBSTITUTES. - - -Isinglass is obtained from the air-bladder or sound, as it is sometimes -termed, of different kinds of fishes, especially of the sturgeon, -species _Acipenser_. It is used for culinary purposes, fining beer and -other liquids, for making court-plaster and stiffening silk, though a -good quality of gelatine is practically equal to it for these purposes. -A good quality of isinglass should be pure white, semi-transparent, -dry and horny in texture, and free from odor. It should dissolve in -water of 95° to 122° F., without leaving any residue, and, on cooling, -should yield an almost colorless jelly. From gelatine imitations it -is distinguished by soaking it in warm water and examining under -the microscope, when true isinglass will show a net-work of long, -curling fibres, while gelatine will be simply hyaline. Isinglass is -often imitated with the intestinal membranes of the calf and of the -sheep. This spurious article may be readily recognized because it does -not exhibit, like isinglass, a sort of shining appearance when held -before the eye and daylight, and because, although inodorous, it has -a saltish flavor. If it be torn asunder it will be observed that it -may be rent in all directions, while true isinglass cannot be divided -otherwise than in the direction of its fibres. If a piece of artificial -isinglass be macerated in water it swells, but instead of retaining -its shape as is the case with the genuine article, it becomes divided -into several pieces, forming a sort of curdy precipitate; and if -treated with boiling water, about one-third of its weight is left in an -insoluble state, and the liquor does not form a good jelly. Isinglass -is frequently adulterated with gelatine, which is inserted between the -leaves and rolled up with it. The best indication of this adulteration -is the amount of ash; isinglass yields only 0.9 per cent., while -gelatine yields 4 per cent., and adulterated isinglass 1.5 per cent. or -more. - -1. _Russian isinglass._ Russia produces the best and most isinglass. -It is chiefly obtained from several varieties of sturgeon, species -_Acipenser_, which inhabit the Caspian and Black Seas, and their -tributary rivers. The _Acipenser Gueldenstaedtii_, Br. yields the -finest, best and whitest isinglass. It is known by the name of -_Patriarch_, and consists of small horseshoe-shaped pieces rolled -tightly together. It is quite scarce and expensive. When the bladder is -merely dried in sheets, it constitutes _leaf isinglass_. When several -bladders are put together and folded before they are completely dry, -they form _book isinglass_. Each bladder may also be rolled up and -folded around a few pegs in the form of a horseshoe, heart, or lyre, in -which shape it is dried. The latter is the _staple isinglass_, which, -according to its dimensions, is again divided into _long and short -staple_. - -Long staple isinglass of fine quality is produced in the Oural. It is -imported in loose leaves, and at times it is twisted like ropes, this -kind being preferred, as it is inferior in quality only to Patriarch. - -_Siberian_ purse isinglass is of moderately good quality and is in -general demand. A small kind of strings in a necklace form is sometimes -imported. - -A very good sort of Russian isinglass comes into commerce in leaves -and books, and is known by the name of _Samovey_ leaf. It is obtained, -according to the statements of Russian merchants, from the common -sheath-fish (_Siluris Glanis_). The pieces are as large as a hand, -of the thickness of pasteboard, very solid, not very flexible and -of a white-yellowish color. It is inferior in quality to Astrakhan -isinglass, which is one of the best kinds. - -In _Russia_ the isinglass is generally prepared by boys under the -supervision of elder experts. The swimming bladder is first placed in -water and left there for some days with frequent changes of the water -and removal of all fatty and bloody particles. The warmer the water -the more rapidly the operation is completed. The bladders are finally -removed and cut longitudinally into sheets which are exposed to the -sun and air, being laid out to dry, with the outer face turned down, -upon boards of linden or bass wood. The inner face is pure isinglass, -which, when well dried, can with care be removed from the external -lamellæ. The finer sheets thus obtained are placed between cloths to -protect them from the flies, and are then subjected to a heavy pressure -so as to flatten them out and render them uniform. After this they -are assorted and tied up in packages. The packages composed of the -isinglass of the large sturgeon usually contain from ten to fifteen -sheets and weigh a pound and a quarter; those of the other contain -twenty-five sheets weighing a pound. Eighty of these packages are -usually sewed up in a cloth bag, or sometimes inclosed in sheet lead. - -The outer lamellæ of the air-bladder, after the isinglass has been -removed, also contain a considerable quantity of glue which, when -softened in water, is scraped off with a knife and moulded into little -tablets of about the size of a silver dollar, and then dried. - -2. _North American or New York Isinglass._ It is in thin strips -several feet long but ½ to 1½ inch wide. It is less soluble than -Russian isinglass, and yields frequently a dark-colored solution. It -is prepared, according to Dr. J. V. C. Smith’s statements, from the -air-bladder of the common hake (_Gadus merluccius_), which is macerated -in water for a short time, cut open and subjected to pressure between -iron rollers, by which it is elongated to the extent of half a yard -or more. It is then carefully dried, packed and sent to market. The -air-bladder of the common cod (_Gadus morrhua_) is prepared in a -similar manner, but yields a poorer kind of isinglass. - -3. _East India Isinglass._ It would seem that for a long time this -has been exported from _Calcutta_ to _China_, but has only lately -attracted the attention of European dealers. It is prepared from the -air-bladder of the _Polynemus plebejus_, and comes into commerce either -in the form of leaves or purses which seem to consist of the unopened -air-bladder. East Indian isinglass has a disagreeable fish odor, due -very likely to careless preparation, which makes its use impossible for -many purposes, and, of course, depreciates its commercial value. The -oval-oblong purses are about nine inches long, three and a half inches -wide, weigh about 7 ozs. and have a dark-yellow color. East India leaf -isinglass, _i. e._, the opened and dried air-bladder, consists of -yellowish-colored leaves eight to nine inches long, six to seven inches -wide, and about three-tenths of an inch thick. The leaves are sometimes -rolled out into long ribbons about one-tenth of an inch thick, the -surface of which is covered in places with a thin film of lime. - -What is known as picked East India isinglass is brought into commerce -in small shreds about two to three inches long, and tapering at the -extremities. - -A variety of isinglass very white and pure and scarcely inferior to -Samovey leaf is brought from Manila. The fish which yields it is caught -on the coast of the Philippine Islands, especially at Luzon. - -4. _Hudson Bay Isinglass._ It is brought into commerce in the purse -form. Some specimens measure twelve inches in length and three and -a half inches in diameter, and weigh one and a half ounces. It is -of light-yellow color, nearly transparent, without odor or taste. -The inner lining of the sac, which can be readily stripped off, is -insoluble in water, while the remaining portion dissolves to a slightly -colored jelly. We have been unable to ascertain from what species of -fish this isinglass is procured. - -5. _Brazilian Isinglass._ This is imported from _Para_ and _Maranham_, -and is also called _Cayenne_ isinglass. For a long time there existed -a doubt from what species of fish this isinglass was procured, but it -is now settled that it is prepared from the air-bladder of _Silurus -Parkerii_, a fish which is frequently found in the muddy waters of the -rivers in the province of Grao Para, where these waters mingle with the -sea. - -_Brazilian_ isinglass comes in the form of pipe, lump and honeycomb. -On account of its dark color it is not in much demand for ordinary -use, but is frequently employed in England for clarifying glue. When -digested in water it leaves much insoluble substance behind, being in -this respect also inferior to Russian isinglass. - -6. _German Isinglass._ Under this name we may mention the mucous -membrane of the sturgeon (_Acipenser sturio_), prepared in Hamburg. -When boiled with water it leaves 16 per cent. of insoluble substance. - -It is said that an excellent isinglass can be made from the scales of -shad and herring, which are first freed from their silvery coating. -This may furnish a useful hint to persons who are near some of the -great fishery establishments of the country, at _Gloucester, N. J._, -and _Alexandria, Va._, for instance, where thousands of shad are scaled -and salted every year. - -To give inferior qualities of isinglass a better appearance and make -them more salable, they are frequently bleached with sulphurous acid. - -_Ichthyocolle Française._ Under this name, Rohan has introduced a -substitute for isinglass. The material used for its manufacture is -blood fibrin, which, after washing in running water, is thoroughly -kneaded and, after draining, digested at 59° F. with dilute sulphuric -acid of 8° to 10° Bé. for eight days, after which the mass is freed -from acid by washing in running water. - -The fibrin freed from acid becomes transparent and gelatinous by -treating with weak soda lye of 3° to 4° Bé. at 59° F., whereby it -swells up and increases hourly in volume. After twenty-four hours -it is taken from the soda lye, and after removing the free soda by -washing, heated to 212° F, in a water-bath. The fibrin dissolves and -becomes so thinly fluid that it can be filtered. 75 to 80 per cent. of -the water is then evaporated, and the fibrin thus prepared can be used -as a substitute for isinglass for fining purposes. Ichthyocolla swells -more quickly in cold water than isinglass; 15 to 20 per cent. divided -in water forms a thickly fluid substance, which on heating dissolves to -a perfectly clear fluid. For fining beer with ichthyocolla add 2 to 10 -per cent. of pure tannin, which does not injure its power of dissolving. - -_Isinglassine._ Under this name is known an isinglass substitute -prepared from the gelatinous material from calves’ feet and other -sources. The material is reduced by machinery to a pliable homogeneous -mass, rolled out into sheets, dried, pressed and shredded. - -_Chinese isinglass_ is identical with the _Japanese Agar-Agar_, and is -obtained by cleansing and boiling certain species of algae found in -Chinese and Japanese waters. This isinglass, or gelatine, possesses the -following properties: - -Placed in cold water it softens without dissolving like gelatine, and -forms a structureless tubular mass which is not sticky. By boiling, -it dissolves more readily than isinglass, but with greater difficulty -than gelatine. A 1 to 2 per cent. solution is easily filtered through -paper or linen, and when cold forms a solid jelly clear as water and -without taste or odor. Jelly prepared with one-half per cent. of -Chinese gelatine is more solid than one prepared with 4 per cent. of -French white gelatine, retains its consistency longer, and will stand a -temperature of 86° to 122° F. before becoming liquid. Used for jellies, -or mixed with other foods, it does not impart to them a glue taste -never wanting in bone gelatine. When decomposed by long standing, it -does not acquire a disagreeable odor, while decomposed isinglass or -gelatine exhales a putrid smell. - -Agar-Agar contains, according to analyses: Cellulose, starch, gum, -dextrine, vegetable mucus, vegetable wax, resin, chlorophyll, albumen, -a peculiar acid, and several mineral substances. - -_Irish moss_ (_Chondrus crispus_) which grows on rocks of the American -and European shores of the Atlantic Ocean, yields a jelly which has -been employed as a substitute for isinglass, as a size, for thickening -colors in calico printing, and in stiffening silk. In a fresh or -softened state the plant is cartilaginous, of a brownish or purple, or -frequently yellow or green color. After washing in water and drying in -the sun it turns whitish or yellowish, and becomes somewhat translucent -and of a horny appearance. It has a slight seaweed-like odor and a -mucilaginous, somewhat saline taste. One part of it boiled with 20 -parts of water gelatinizes on cooling. - - -_Fish Glue._ - -This product, which is prepared in many localities from fishes, must -not be confounded with isinglass, though the purer varieties may serve -as substitutes for the latter or for gelatine. - -Jennings gives the following process for the preparation of fish glue. -The fishes are treated with dilute sulphuric acid until the skin can -be detached. The acid water is then drained off and replaced by milk -of lime to neutralize adhering sulphuric acid as well as to saponify -the fat. The milk of lime is several times drained off and renewed, the -mass thoroughly washed, cut up in a hollander and treated cold with -solution of sodium hyposulphite, common salt and alum. After a few days -the liquor is drawn off and replaced by a mixture of alum solution, -dilute sulphuric acid and nitric acid in which the mass is allowed -to remain for a few days. Fishes with dark skins are treated with a -mixture of hydrochloric and sulphuric acids. After washing, the skin -is removed and the fibres which have become detached from the bones -are separated by digestion in dilute solution of mercuric chloride and -alum. Adhering fatty parts are removed with warm milk of lime, the lime -is neutralized with hydrochloric acid, and the mass boiled with water -for the formation of glue. The resulting glue-liquor is clarified with -sulphurous acid and alum, and when all the impurities have subsided, -compounded with acid sodium carbonate till all the acid is neutralized. -The finished solution is concentrated so that it gelatinizes on cooling -and can be cut in cakes which are dried in the usual manner. - -Fish scales, especially those of carps, are treated in a similar -manner. The bone-earth is extracted with hydrochloric acid, the -extracted material thoroughly washed, and then boiled in soft water -till it can be readily stirred. The liquor is drawn off from the horny -sediment, clarified with alum, evaporated, and after all the impurities -have subsided, poured into moulds and treated like ordinary glue. - -Considerable quantities of fish glue are produced on the Norwegian -coast from waste obtained in the preparation of codfish. The fish when -caught are cut open and the air-bladders removed, which are dried and -brought into commerce as isinglass. The head is then cut off and the -bones detached in one piece. The flesh is dried in the air, and forms -the codfish of commerce. The heads and bones are first treated with -hydrochloric acid or directly boiled under slight pressure in water, -and the resulting liquor concentrated so that it will gelatinize. - -A substitute for isinglass, also for gelatine and glue, is prepared by -C. A. Sahlströhm, of Stockholm, according to his patent, from fish and -fish waste by treatment with bleaching powder, potassium permanganate, -and nitrous and sulphurous gases. - -For this purpose the fishes, or portions of fishes, are first well -washed in fresh water and then left for from three to four hours in a -solution of bleaching powder (in the proportion of 2 lbs. of bleaching -powder to 300 quarts of water). After washing they are treated for -about 30 minutes with a solution of potassium permanganate (in the -proportion of 1¾ ozs. of potassium permanganate to 250 or 300 quarts of -water), and then exposed to the action of the nitrous gas, produced by -heating 10 to 15 ozs. of nitric acid for every 88 lbs. of raw material. -This gas may be first absorbed by water, as in the manufacture of -sugar, or sulphur dioxide may be used instead of nitrous gas. The -former would be obtained by burning about 7 ozs. of sulphur for every -88 lbs. of raw material. - -The material, after this treatment, is washed. Those portions intended -for the production of isinglass substitute are freed from their outer -skins and dried and pressed at a gentle heat. The portions destined to -produce gelatine or glue are, on the contrary, exposed to a temperature -of from 104° to 122° F. for from ten to twelve hours, by which the -material is mainly dissolved. The mass is then forced through a -strainer or sieve, and the liquor allowed to gelatinize by standing for -some hours. The jelly is finally dried, as is usual in the manufacture -of glue or gelatine. - -_Whale glue_ is, according to Culmann, obtained in the Russian island -Jeretike from the liquor remaining in the boilers after the extraction -of the oil by means of superheated steam. By reason of the raw and -moist atmosphere which prevails in that locality, even in summer, -drying the glue is not practicable, and for this reason it is brought -into commerce in the form of a compact jelly mixed with a preservative -and packed in tin boxes. The commercial article contains 41.65 per -cent. water. It is liquefied by placing the can in boiling water, and -melts at 176° F. As shown by mechanical tests, it possesses great -tenacity, and two pieces of wood glued together lengthwise cannot be -separated at the joint but break alongside of it. - - - - -CHAPTER XI. - -TESTING GLUE AND GELATINE. - - -It is of importance that the manufacturer as well as the dealer should -know how to test the quality of a glue. This may be done by chemical -means and in a mechanical way. - -_Determination of moisture._ For this purpose a weighed quantity -of the sample, finely powdered, is for fourteen hours exposed to a -temperature of 217° to 230° F. It is then cooled under the dessicator -and reweighed. The content of moisture is then calculated from the loss -in weight. - -_Determination of ash._ The origin of a sample of glue may be traced -by examining the ash for phosphates of lime and magnesia, bone-glue -containing both, while skin-glue is free from phosphates. Reduce -a portion of the sample to a fine powder, and weigh it in a tared -constant crucible. Heat slowly over a Bunsen flame until carbonized, -then remove the crucible to the muffle, and heat to bright redness for -10 hours. Cool under the dessicator and weigh. The increase in weight -of the crucible is the ash of the sample. This will vary from 1 to 2 -per cent. in a gelatine, 2 to 3 per cent. in a good glue, 6 to 8 per -cent. in a common quality. - -_Determination of Acidity._ Kissling elsewhere determines the acidity -by suspending 30 grammes of the sample in 80 Cc. of cold water for 10 -to 12 hours in a flask connected with a condenser. The volatile acids -are then driven over by a current of steam into a graduated cylinder. -When the distillate amounts to 200 Cc., distillation is interrupted, -and the distillate treated with standard decinormal alkali. When the -distillate contains sulphurous acid, a known quantity of the standard -alkali is previously added to the cylinder. - -An undue quantity of acid may be detected by the taste. Glues may be -alkaline from the addition of excess of lime in the manufacture to -correct the sourness of the jelly. For uses where colors are concerned -the glue must be neutral to litmus; for adhesive uses this does not -matter unless the alkalinity or acidity is due to defective preparation -(Samuel Rideal). - -_Determination of Glutin._ The percentage of glutin in a glue solution -is determined by precipitating it with tannin. The dense white -precipitate formed is thrown on to a tared filter, washed with hot -water, dried and weighed. The calculation is made on the basis that the -tannate of glutin has a percentage composition of 42.74 per cent. of -glutin and 57.26 per cent. of tannin. - -Bisler-Beumat while employing the same principle prepares two -solutions: _a._ 10 grammes of pure tannin to the liter. _b._ 10 grammes -of pure isinglass and 20 grammes of alum to the liter. The ratio in -which the tannin is precipitated by the isinglass solution, which -Risler considers as pure glutin, is then determined by titration. The -tannin solution is then diluted so that exactly an equal volume of glue -solution is precipitated by it. - -In order to test a sample of glue, dissolve 10 grammes of it together -with 20 grammes of alum in a liter of water, heat being applied if -necessary. Next 10 cubic centimeters of the tannin solution are taken -to which an equal bulk of glue solution is at once added, as one may be -sure that this quantity is not sufficient for the precipitation of the -measured quantity of tannin, because no glue found in commerce is as -pure as isinglass. The vessel containing the mixed liquids being well -shaken and the precipitate having subsided, another cubic centimeter of -glue solution is added to the tannin solution which is next filtered -through a moist cotton filter. If _one_ drop of the glue solution still -produces a precipitate in the clear filtrate, another cubic centimeter -is added to the tannin solution, and then again filtered, these -operations being repeated until the filtrate is no longer rendered -turbid by the glue solution. - -With the known relation of the tannin solution to pure glue -(isinglass), a conclusion may be formed from the number of cubic -centimeters of glue solution used as to the content of glutin in the -sample examined. - -The percentage of glutin varies, of course, according to the quality -and origin of the glue. Bone glue of good quality contains from 50 to -52 per cent. and skin glue from 65 to 75 per cent. - -S. Dana Hayes analyzed two samples of American glue of best quality and -obtained the following results: - - a. b. - Water (escaping at 212° F.) 16.70 16.28 - Glue substance 79.85 80.42 - Calcium carbonate 1.42 1.33 - Calcium sulphate 0.41 0.34 - Magnesium phosphate 0.35 0.31 - Alkaline salts 0.17 0.12 - Silica, ferric oxide, etc. 0.09 0.08 - Zinc oxide 1.01 1.12 - -The chemical modes of testing glue give only the quantity of glutin -contained in it, but do not prove that the substance combined with -tannin corresponds to the actual adhesive power of the glue, for it is -possible that a glue containing a large quantity of glutin may possess -but little adhesive power, and a jelly from which the glue is formed -may contain an equal amount of glutin with the latter, but not possess -an equal power of adhesion. - -It is certain that the determination of the glutin alone is not a -criterion of the quality of glue. In the absence of a reliable method -of direct analysis, attempts have been made to deduce the quality of -glue from indirect properties. - -One of these methods consists in immersing the sample of glue in a -large quantity of water at 59° F. for a considerable time. The glue -swells up, absorbing 5 to 16 times its own weight of water. The -more consistent and elastic the glue in this state is found to be, -the greater its adhesive power, and the larger the quantity of water -absorbed the more economical the glue will be in use. This method does -not give thoroughly reliable results, and should only be employed with -bone-glue, as skin-glue does not behave in a similar manner. - -[Illustration: FIG. 65.] - -A more reliable method is to test the strength of a glue by the method -first proposed by Lipowitz, which is based on the weight-sustaining -power of a jelly of known strength and temperature. The test is -executed as follows: Soak 5 parts of the sample in water, then dissolve -it in sufficient hot water to make the weight of the solution equal -to 50 parts, and allow to stand for 12 hours at 64.4° F. in a glass -cylinder of uniform width to gelatinize. Cover the glass cylinder with -a tin cap perforated in the centre, Fig. 65. Through the perforation -is passed freely a stout iron wire, at the lower end of which is -soldered a piece of tin shaped like a saucer, the convex side of it -resting on the surface of the jelly. To the upper end of the wire, -which together with the tin saucer should weigh 5 grammes, is soldered -a funnel weighing 5 grammes, and capable of holding up to 50 grammes -of fine shot. The apparatus is gradually loaded with shot until the -saucer-shaped piece of tin is forced into the jelly. The greater the -strength of the jelly, the heavier will be the weight required. From -the determined weight of the shot used, the relative value of the glue -as to its adhesive power is determined. - -The following results have been obtained by comparative experiments -with this apparatus: - - Variety of Glue. Weight required to force - the saucer down. - - Breslau 1704 grammes = 3.74 lbs. - Russian 1446 grammes = 3.18 lbs. - Cologne 1215 grammes = 2.67 lbs. - Muhlhausen I. 727 grammes = 1.599 lbs. - Nördlingen 724 grammes = 1.592 lbs. - Muhlhausen II. 387.5 grammes = 0.85 lbs. - -The results of these experiments agree to a remarkable degree with the -market prices of the varieties of glue, which is not the case with -glues tested by the methods previously mentioned. The results of these -tests are given in the table below: - -Table Key: - -Variety of Glue. - - 1. Best White isinglass in three qualities - 2. Translucent yellowish bone glue in tablets and easily soluble - 3. Pale yellow glue similar to No. 2 - 4. Brown-reddish, brittle in fracture and soluble - 5. Clear translucent glue of medium brown color - 6. Brown-yelow glue in thick tablets and possessing but little - translucency - 7. Pale brown-yellow glue, readily soluble and elastic before breaking - 8. Pale amber-colored glue with but little translucency - 9. Brown glue, solution turbid - 10. Amber-colored glue, opalizing and readily soluble - 11. Thich tablets or dark-brown glue, solution very turbid - 12. Dark horn-like glue with little translucency - 13. Very translucent glue of a light brown color and very clean - solution - 14. Translucent dark-brown glue, giving a very clear solution - - ----+----------------+--------------+------+-------------+------------- - |Loss of water | 100 parts |Glutin| Water |A 100 per cent. - |in drying for | of glue are | per | absorbed in |solution of - |several hours at| precipitated |cent. |24 hours by 5|glue will bear - |239° to 248° F. |by tannic acid| |parts of glue|a weight of - ----+----------------+--------------+------+-------------+------------- - 1. | 20 to 21 | 74.62 | 55.69| — | - | | | | | - 2. | 13.2 | 76.2 | 56.8 | 40 |64 grammes - | | | | | (2.25 ozs.) - 3. | 13.0 | 70.0 | 52.2 | 35 |60 grammes - | | | | | (2.11 ozs.) - 4. | 10.0 | 71.0 | 52.9 | 12 |Does not - | | | | | gelatinize. - 5. | 11.0 | 71.5 | 53.3 | 20 |20 grammes - | | | | | (0.705 oz.) - 6. | 12.5 | 68.0 | 50.7 | 27 |15 grammes - | | | | | (0.52 oz.) - 7. | 13.0 | 66.6 | 49.7 | 30 |36 grammes - | | | | | (1.26 oz.) - 8. | 9.5 | 68.5 | 51.1 | 33 |60 grammes - | | | | | (2.11 oz.) - 9. | 10.0 | 82.0 | 53.7 | 30 |50 grammes - | | | | | (1.76 oz.) - 10.| 9.5 | 73.0 | 54.4 | 35 |56 grammes - | | | | | (1.97 oz.) - 11.| 13.5 | 64.0 | 47.7 | 18 |23 grammes - | | | | | (0.81 oz.) - 12.| 9.0 | 72.6 | 54.2 | 29 |12 grammes - | | | | | (0.42 oz.) - 13.| 13.5 | 70.0 | 52.2 | 30 |40 grammes - | | | | | (1.41 oz.) - 14.| 15.0 | 66.0 | 49.4 | 25 |42 grammes - | | | | | (1.48 oz.) - ----+----------------+--------------+------+-------------+------------- - -This table shows the following facts: - -1. The percentage of water in the 14 dry varieties of glue examined -varies between 9.0 and 21. The loss of water from isinglass is -surprisingly large, especially as it cannot be explained by an -artificial admixture of water, since the six varieties examined -reabsorbed the same percentage of water from the air. The percentage of -water in the other varieties of glue differs but little. - -2. The various varieties of glue required different quantities of -tannic acid for their precipitation, the amount for 100 parts of glue -varying between 66 parts and 76.2, or calculated to per cent., between -49.4 and 56.8. - -3. Placed in cold water, glue swells up and absorbs from 12 to 40 parts -of water. The behavior of the various varieties differs very much in -this respect, and in most of the experiments, with the exception of -variety No. 4, the percentage of glutin is in exact proportion to the -quantity of water absorbed. - -4. The strength of the gelatinized glue varies between 12 grammes -(185.18 grains) and 64 grammes (987.67 grains) for a 10 per cent. -solution. This property corresponds neither with the absorption of -water nor the percentage of glutin. - -Variety No. 4, in the table, contains 52 per cent. of glutin, but does -not gelatinize, its strength being therefore equal to 0, while variety -No. 14, with 49.4 per cent. of glutin, therefore less than No. 4, -shows a strength of 42. As no close connection between the properties -mentioned in the table can be recognized, it is best not to be guided -by these properties alone, but to test also the behavior of the glue in -practical use. Such test consists in estimating the adhesive power of -the glue from the weight required to tear asunder two pieces of wood -glued together and dried. But as the results obtained by this purely -practical test must necessarily vary on account of the impossibility of -having two surfaces of wood always exactly alike, and the uncertainty -of applying every time the same quantity of glue, Weidenbusch’s method -may here be given. It is based upon the principle that sticks of -plaster of Paris cast of exactly the same material and of uniform size -break under the same weight when placed upon two supports and loaded in -the centre. If now such plaster sticks be saturated with glue solutions -prepared according to the same method, but from different qualities -of glue, a greater force will be required for breaking them, and this -force will be the greater the better the quality of glue is. - -The plaster sticks are prepared as follows: Reduce pure crystallized -gypsum to a fine powder, pass the latter through a sieve having 324 -meshes per square centimeter and heat it to between 284° and 302° F. -For casting the sticks moulds of soap-stone are used. The moulds are -made by boring in a piece of soap-stone, at a distance of about 1 -centimeter from each other, holes with a diameter of 6 millimeters on -top and 7½ millimeters on the bottom. - -The gypsum is weighed off in portions of 1 gramme each, mixed with 1 -gramme water and cast in the moulds. The solidified sticks are first -dried at a moderate heat and then over calcium chloride, and kept for -use in an air-tight vessel. - -[Illustration: FIG. 66.] - -The glue solution is prepared as follows: The glue dried at 212° F. is -weighed, soaked over night in water, then melted in a small glass in -the water-bath, and finally enough water is added so that the solution -contains 10 per cent. of dry glue. - -The plaster sticks are for one or two minutes immersed in the glue -solution heated to 212° F., and then placed vertically upon a glass -plate until superficially dry, when they are completely dried at 212° -F. It is recommended to color the glue solution with indigo, the -uniform saturation of the sticks being thereby more easily recognized. - -The apparatus for testing the strength of the sticks consists of a -brass ring _a_, Fig. 66, having two notches to receive the stick, and -its diameter is divided into two equal parts by an indicator. The ring -is supported by a pin, by means of which it is secured in a stand. The -apparatus is completed by an iron or glass cup which is suspended by -three cords, _i_, and the hook _f_ to the plaster stick _b_. The hook -_f_ is placed in the position indicated by the indicator. Mercury is -now poured into the cup until the plaster stick commences to break. The -weight required is recorded and compared with a standard glue. During -the experiment the cup is suspended by the three cords _h_ to the ring -_a_, and is thus caught when the plaster stick breaks. On the lower end -of the cup is a clip for emptying the mercury into a vessel so that -none of it is lost. - -The “Artillery Werkstätte” at Spandau has adopted the severing strain -of two blocks of wood glued together. The test is executed as follows: -Three parts of glue (but not less than 250 grammes) are mixed with -6 parts of water and boiled in a steam bath until the weight of the -boiled glue amounts to only 5/9 of the original mixture. The reason for -this continued boiling is to ascertain whether the glue to be tested -retains the required adhesive power even after six hours continued -heating in a steam bath as frequently happens in the workshop. With the -glue thus prepared the following breaking test is made: - -Blocks of hard or soft wood 420 millimeters long and 40 × 40 -millimeters cross section are cut in two, so that each piece thus -obtained is 210 millimeters in length. These two pieces are then again -glued together across the grain with the glue to be tested. The -block is then placed in a dry room at a temperature of 62° to 68° F. -for 72 hours, when the joint is tested as to its resisting power. At -a distance of 180 millimeters from the joint a hole is bored in the -block. Through this hole is pushed a bolt furnished on the lower end -with a hook to which a scale is suspended. The block of wood is clamped -to a table so that the joint projects 1 centimeter beyond the edge. The -scale is at the start loaded with 25 kilograms, the load being every -five minutes increased 5 kilograms till fracture takes place. - -Two such blocks, one of hard and one of soft wood, are subjected to the -test, and a serviceable glue must stand at least an average load of 70 -kilograms. - -_Determination of adulterations._ White lead, sulphate of lead, zinc -white, or chalk in quantities varying from 4 to 8 per cent. are -frequently mixed with the melted glue to improve the appearance of the -finished product. Thus, according to analyses by A. Faisst, Russian -glues contained in 100 parts foreign admixtures as follows: - - I. II. III. IV. - Zinc white 1.66 - Chalk 2.40 2.95 3.79 2.10 - Sulphate of lead — 4.16 2.35 3.18 - —— —— —— —— - 4.06 7.08 6.14 5.28 - -The so-called patent glue which is opaque and of a white color is -produced by adding considerable quantities of white lead to ordinary -glue. - -According to Barreswil, glue is frequently mixed with lead acetate -solution to protect it from putrefaction. Such an addition, as well -as the presence of white lead or sulphate of lead, is detected by the -introduction of sulphuretted hydrogen into very dilute glue solution. -In the presence of lead acetate a black precipitate of lead sulphide -appears in the clear solution; if white lead or lead sulphate is -present, the white powder settling on the bottom is blackened by the -formation of lead sulphide. - -For the detection of other earthy additions, prepare a very dilute -solution of the glue in question and allow it to stand quietly for -a few hours. The heavy additions subside, and after decanting the -supernatant fluid is collected upon a small filter and examined by the -customary analytical methods. - -It is difficult to say what quantities of earthy constituents actually -constitute an adulteration, since it is claimed by many practical men -that a considerable content of earthy parts is of advantage as regards -the cementing power of glue. Generally speaking it may, however, be -said that a glue containing more than 6 to 8 per cent. of earthy -constituents must be considered adulterated. - -For many purposes, especially if the glue comes in contact with colored -materials as, for instance, in book-binding, a content of free acid -would exert an injurious effect upon the colors, destroying or changing -them. It is therefore advisable to test the glue with blue litmus paper -which, in the presence of free acid, is reddened. - -In testing a large number of samples of glue, Kissling obtained the -following results: - - Number Smallest Largest Average - SKIN GLUE. of samples. percentage. percentage. percentage. - - Water 15 13.4 18.1 15.7 - Ash 16 1.0 4.13 2.15 - Fat 21 0.01 0.090 0.037 - Volatile acids, free } 8 {0.084 0.238 0.178 - Volatile acids, fixed } {0.084 0.334 0.191 - - BONE GLUE. - - Water 25 11.5 17.7 13.4 - Ash 26 1.16 5.07 2.46 - Fat 5 0.047 0.217 0.113 - Volatile acids, free } 7 {0.088 1.451 0.655 - Volatile acids, fixed } {0.097 0.721 0.460 - -However, those who from their practical knowledge are most competent to -judge the commercial value of a glue, scarcely require such complicated -tests, as by taking the sample in their hand and looking at it, -they can in most cases tell its quality. Great hardness, a clear, -rattling sound when struck, and resistance to breaking are signs of -good quality, and if the cake is cut thick, it shows that the jelly -possessed great consistency. Many kinds of glues are intentionally -cut thin so that they will dry before spoiling. The derivation of -a glue from a sound jelly is recognized by the fine cutting lines. -When the jelly possesses but little gelatinizing power and is in the -first stages of decomposition or putrefaction, or formation of sugar -has already set in, it cannot be poured into moulding boxes, as it -would putrefy before it has a chance to gelatinize. Such sick jelly is -poured in thin layers upon glass or metal plates so that it may acquire -sufficient solidity to allow of its being cut up into leaves and dried -upon nets. If the edges of the glue are deeply indented and raised, the -jelly, before drying, possessed but little concentration (25 to 30 per -cent.), and if notwithstanding this, it acquired sufficient consistency -to allow of its being cut, it must have been very sound. Glues cut -thick and showing no indentations and raised edges, are derived from -excessively concentrated jellies (30-35-40 per cent.). Such jellies -lose in quality in evaporating. - -A high degree of transparency is a favorable sign as regards the purity -of a glue, substances inducing putrefaction having been eliminated. -Hence this property should be worthy of recommendation, but the -consumer having been disappointed in the use of thin glass-clear glues, -distrusts also the thick-cut transparent product, preferring a turbid, -translucent or opaque article. For this reason the manufacturer is -forced to render glass-clear glue turbid with coloring matter. - -The color of the glue is also a means of judging it. To be sure, -chemically pure glutin is a colorless substance, but glue is always -colored more or less dark brown. Although this coloration does not in -the least impair the adhesive power, the manufacturer endeavors to -produce a product of as light a color as possible, and this is best -effected by bleaching with sulphurous acid. By this means the glue not -only acquires a lighter color, but also becomes more stable, substances -inducing putrefaction being destroyed by the acid. - - - - -PART II. - -CEMENTS, PASTES, MUCILAGES. - - - - -CHAPTER XII. - -CLASSIFICATION OF CEMENTS. - - -The great variety of substances entering into the manufacture of -cements and pastes makes a division of them extremely difficult. -Stohmann divides them into the following groups: - - 1. _Oil cements._ - 2. _Resinous cements._ - 3. _Cements containing rubber or gutta percha._ - 4. _Cements containing glue, or starch paste._ - 5. _Lime cements._ - -Generally speaking, this division is correct; the only change we -would suggest is to apply the term _agglutinant_ or _paste_ to bodies -containing glue and starch paste. - -When we attempt a division of the cements according to the bodies to be -cemented, we find that the result will be a larger number of groups; -as we must take into consideration whether the articles to be cemented -have to be heated or not, whether they are to come in contact with -water or other liquids, and other circumstances which would necessitate -modifications in the composition of the cements themselves. - -According to this, we might group the cements as follows: - - 1. _Cements for glass and porcelain, for repairing broken articles, - for fastening glass letters upon show-windows, etc._ - - 2. _Cements for metals not exposed to an increase of temperature, for - instance, for tightening the joints of gas and water pipes._ - - 3. _Cements for stoves and other articles, which have to stand an - increased temperature._ - - 4. _Cements for chemical apparatus, i. e., such as will have to resist - the action of chemical agents._ - - 5. _Cements to protect vessels of glass, porcelain, or metal against - the action of fire._ - - 6. _Cements for filling hollow teeth, for microscopical preparations, - and other delicate articles._ - - 7. _Cements for special purposes, for instance, for cementing - meerschaum, tortoise shell, etc._ - -_Chemical nature of cements._ The different varieties of cement -frequently contain substances which act chemically upon each other, -or upon the bodies to be united with them. To determine the practical -availability of a variety of cement for a determined purpose, it is of -importance to know the reciprocal behavior of these substances towards -each other, as from this we are able to judge at once whether a cement -is suitable for a certain purpose or not. - -_Oil cements._ The fluid fats, commonly called oils—though there are -oils which remain solid at the ordinary temperature, as, for instance, -palm oil and cocoanut oil—may, as regards their behavior on exposure to -the air, be divided into two large groups, namely, drying and nondrying -oils. As samples of these groups may be mentioned olive oil and linseed -oil. - -If a thin layer of olive oil protected from dust is exposed to the -air, it will remain fluid for years and retain its characteristic oily -consistency. The only change it undergoes is that it becomes somewhat -more viscid and rancid, and acquires a darker color, but it never dries -up. - -Linseed oil treated in the same manner solidifies in the course of a -few weeks to a hard, tough and elastic mass, resembling, as regards its -physical qualities, resin or rubber. - -By compounding a drying oil with a small quantity of litharge, -pyrolusite, manganous borate, etc., and heating the admixture to the -boiling-point, it acquires the property of drying in a few hours when -exposed to the air in a thin layer. Oil so treated has been changed to -a varnish. - -By bringing a drying oil in contact with a body possessing strong basic -properties a peculiar process takes place; the sebacic acids contained -in the oil combine with the basic bodies to solid combinations which -are insoluble in water, and, on exposure to the air, change gradually -into masses as hard as stone. Such combinations, as regards their -chemical composition, resemble ordinary soap, and for this reason are -called insoluble soaps to distinguish them from ordinary soap which is -soluble in water. - -Burned lime, calcined magnesia, whiting, ferric oxide, litharge, and -minium possess the capacity for forming insoluble soaps on coming -in contact with drying oils and, still more quickly, with varnishes -prepared from them. - -The hardness of these soaps in time increases considerably by the oil -not saponified drying in. The oil cements are principally used for -tightening water and gas pipes, as they resist the action of water, -steam and gas. - -The only drawback connected with these cements is that they must reach -a certain age before becoming entirely hard, and that, on account of -the high price of drying oil or varnish which is absolutely required -for their preparation, they are rather expensive. The ordinary -glazier’s putty and the red lead and linseed-oil cement used in -constructing water and gas conduits belong to this group. - -_Resinous cements._ By resins are understood a number of constituents -of plants which exude in thick viscous masses through incisions made -in the trees, and on exposure to air are gradually converted into -less transparent, brittle masses. When heated they melt more or less -readily, forming a thick, ropy liquid, and brought in contact with an -ignited body they burn with a bright flame and much sooty smoke. - -By making incisions in the bark of any of the whole genus of _Pinus_ -belonging to the _Coniferæ_ family, a viscous mass of a strong odor, -called turpentine, is obtained. It consists of a solution of common -rosin in the essential oil of turpentine, and when distilled yields -from 75 to 90 per cent. of colophony or rosin, which remains in the -retort, and from 25 to 10 per cent. of the essential oil, commonly -called spirits of turpentine. Pure rosin is a brittle, tasteless, and -almost inodorous mass of a light yellow color and a smooth, shining -fracture. - -The various resins found in commerce, such as shellac, mastic, elemi, -copal, etc., are formed in a similar manner. - -The principal points of importance for our purpose are the different -degrees of hardness and brittleness and the melting-points of the -various resins. While some possess but slight hardness, for instance -elemi, others, such as copal and amber, excel in this respect and their -brittleness and high melting-point. - -To decrease the brittleness of resins, essential oils are sometimes -added, or resinous cements are mixed with oil cements or a fat drying -oil, or compounded with rubber cement. - -Resinous cements are either softened by heating or entirely melted, -or solutions of resins in volatile solvents are used, which, in -evaporating, leave the resin behind. - -The resinous cements possess great power of resistance, and are -therefore well adapted for tightening water and gas pipes, but they -have the disadvantage of not standing a high temperature and possessing -a certain degree of brittleness which renders them unfit for the -cementing of articles exposed to frequent shocks. - -Many of these cements, especially those prepared with pitch or -asphaltum, can be produced at a very low cost, and do excellent service -for water-proofing vessels, water-reservoirs, brickwork, etc. - -_Rubber and gutta-percha cements._ Caoutchouc, commonly called India -rubber, or briefly rubber, is derived from the milky juices of -certain tropical plants. It is distinguished by great elasticity and -indifference to chemical agents. - -Both these properties make it a valuable material for cement, and it -is much used for this purpose either in the form of solution or as -a constituent of other compositions. For cements which are to have -a certain degree of elasticity combined with indifference toward -chemical agents, it is absolutely indispensable, as no other known body -possesses these properties in such a high degree. - -The derivation of gutta percha is similar to that of rubber. At an -ordinary temperature it forms solid and very tenacious masses, of a -leather-like consistency, but at a somewhat higher temperature (below -the boiling-point of water) it is converted into a very plastic, soft -mass, which can be drawn into very fine threads, and rolled to very -thin plates. - -By itself or mixed with other substances it furnishes an excellent -cement, possessing the valuable properties of tenacity and pliancy -when exposed to shocks. As regards resistance to the action of water -and chemical agents it is almost equal to rubber, and, for certain -purposes, is frequently preferred to the latter. - -_Glue and starch cements._ By itself, _i. e._, converted by boiling -with water into a viscous mass which solidifies on cooling, glue cannot -be classed with the cements; the same applies to paste, _i. e._, starch -or flour swelled and boiled in water. - -But compounded with other substances both yield excellent cements, -in which a part of the properties distinguishing glue solution and -paste is preserved. They both possess the property of decreasing the -brittleness of many cements, but unfortunately the latter thereby lose -their power of resisting the action of water; for starch as well as -glue swells in water, and the latter, when moist, passes quickly into -putrefaction and destroys the cement. - -In a wider sense isinglass, compounds of glue and vinegar, of lime and -glue, etc., must be classed with the glue cements, and ordinary flour -and shoemakers’ paste with starch cements. - -_Lime Cements._ Lime possesses the property of forming insoluble -combinations with egg albumen or caseine, this being the reason why -lime cements, of which there are a great number, are generally composed -of burned lime and one or the other of the above substances. Lime -compounded with a solution of water-glass forms also very solid and -durable cements. - -Although the cements and agglutinants mentioned in the foregoing -are most frequently used, a compound of different cements is often -employed, in consequence of which the composition of many cements is -very complicated. - -In the following we give a description of the preparation of the -different kinds of cement, according to the manner of their employment. - - - - -CHAPTER XIII. - -PREPARATION OF CEMENTS, PASTES, AND MUCILAGES. - - -OIL CEMENTS. - -Oil cements, as already explained, must be considered as a variety -of soaps insoluble in water, formed by the action of drying oils or -varnish upon various basic combinations. - -The most important of this class is the cement used for securing -window-panes. Good glaziers’ putty is a product of extraordinary -durability, and, besides for puttying glass and wood, can also be used -for joining many other bodies. - -_Putty._ This is prepared by mixing fine whiting with linseed oil or -linseed-oil varnish. The whiting should be passed through a sieve of 42 -meshes to the inch. It should be perfectly dry before sifting, and be -thoroughly incorporated with the oil. - -As the work of kneading large masses with the hands or feet must be -continued for a long time in order to obtain an entirely uniform -product, and is consequently very laborious, it is recommended to use -the following contrivance: - -Two wooden rollers rest in a suitable frame, and can be brought -together or removed from each other by means of two screws. When the -mixture of whiting and linseed oil is of sufficient consistency to -allow kneading, it is fashioned into a cylinder and rolled out between -the above rollers to a long, thin band, which is caught in a vessel. -The band is balled together, the ball reformed into a cylinder, and the -latter again passed through the rollers, the operation of balling and -rolling being continued until a uniform mass is obtained. - -The finished product should be kept in oiled paper or under water. -White lead is sometimes mixed with the putty, and other pigments to -give color as desired. Hard putty may be softened by rolling between -the hands. - -_French putty._ Boil 7 lbs. of linseed oil with 4 lbs. of burnt umber -for 2 hours. Then add 10 lbs. of white lead and 5½ lbs. of chalk. - -_Soft putty._ Whiting 20 lbs., white lead 2 lbs., linseed oil and olive -oil 1 gill each. - -Mix the whiting and the white lead with the necessary quantity of -linseed oil, to render the putty of the proper consistence, the olive -oil being added to the linseed oil before kneading. The object of using -olive oil is to prevent the white lead from hardening, and it preserves -the putty in a state sufficiently soft to adhere at all times, and not, -by getting hard and cracking off, suffering the wet to enter, as is -often the case with ordinary hard putty. - -_Litharge cement._ By mixing litharge reduced to a fine powder with -linseed oil, a yellow cement is obtained which gradually solidifies to -a mass as hard as stone. - -_Red lead cement_ is made by mixing red lead with linseed oil to a -paste. It is used for cementing the joints of metal pipes. - -Lead preparations furnish excellent cements, but have the disadvantage -of great weight and a high price. For many purposes a part of the lead -combination can be suitably replaced by a substance of less weight, -such as whiting, or, still better, burned lime slacked with sufficient -water to convert it into a powder. - -The quantity of the substitute added varies very much, there being, -for instance, many varieties of so-called red lead oil cement, which -contain only about 10 per cent. of red lead. - -_Cement for wash basins._ Finely powdered glass (sifted) 2 parts, -litharge 2 parts, linseed-oil varnish 1 part. - -Wet the powders slightly with the oil, heat and gradually add the -rest. Do not use the basin for several days. Finely powdered glass or -glass meal may be made by heating glass, throwing it in cold water, -grinding the fractured pieces, and washing by stirring up in water, and -allowing the finer particles to float off into a second vessel. Collect -this fine powder when sufficient has settled in the vessel and sift it -through a very fine sieve. - -_Zinc-white cement_ is prepared similar to putty or red-lead cement. -It may, however, be made as follows: Mastic 2 parts, dammar 4 parts, -sandarac 6 parts, Venetian turpentine 8 parts, turpentine 10 parts, -benzole 12 parts, zinc white 14 parts. - -The resins are powdered, while the Venetian turpentine, ordinary -turpentine, and benzole, are put in a bottle, and then the powdered -resins put in. The whole is shaken and allowed to stand for the resins -to dissolve. The solution is filtered through cotton-wool and rubbed -up with sufficient zinc-white to form a cement. Dilute with benzine if -necessary. - -_Mastic cement, mastic or pierres de mastic._ Under this name masses -are brought into commerce which are well adapted for moulding -ornaments, such as figures, columns, etc., to be exposed to the -weather. They are comparatively cheap, and it is rather remarkable that -they are not more generally known and used for technical purposes. - -To prepare large quantities of this cement suitable mills and mixing -vessels are required, as the conversion of the materials into a -dust-like flour is an indispensable condition of the success of the -work. The materials most generally used are fine quartz sand, finely -ground calcareous sand, and varying quantities of litharge or zinc -oxides, besides as small a quantity of linseed oil as possible. - -The linseed oil combines with the litharge or zinc oxide to an -insoluble soap, which incloses the other material and forms a mass -acquiring the hardness of sandstone in thirty to fifty hours. - -After converting the materials into a fine powder, the mixing is -accomplished in barrels filled about three-quarters full and revolved -by water-power. When a thorough mixture has been effected the -pulverulent mass is placed in sheet-iron vessels and saturated with -linseed oil, and then moulded at once, as it solidifies in one or two -days. - -_French mastic._ Quartz sand 300 parts, pulverized limestone 100, -litharge 50, linseed oil 35. - -_Paget’s mastic._ Sand 315 parts, whiting 105, white lead 25, calcined -red lead 10, lead acetate solution 45, linseed oil 35. - -The mastic may be colored by adding pigments. - -_Water-proof cement._ _A._ Rubber 7 parts, oil of turpentine 140, -linseed oil 40. _B._ Turpentine 100 parts, sulphuric acid 3, zinc-white -10. - -To prepare solution _A_, place the rubber in the oil of turpentine in a -bottle. It swells very much without actually dissolving. After adding -the linseed oil, reduce the entire mass by boiling to one-half the -volume originally occupied by it. - -Solution _B_ is prepared by stirring the sulphuric acid into the -turpentine and allowing it to stand for twelve hours. To remove the -sulphuric acid, the thick mass which has been formed is then kneaded in -water in which the zinc oxide has been distributed. After drying, the -resulting mass is dissolved in the warm fluid _A_. - -_Another formula_ is as follows: Linseed oil 8 parts, litharge 12, -burnt lime 88. - -Boil the linseed oil and litharge half an hour, then stir the lime into -the hot mass, and use the mixture hot. This cement is excellent for -filling in joints between stones, for flat roofs, water reservoirs, -etc. For a better adhesion of the cement, apply a coat of linseed -oil varnish to the surfaces to be cemented. Porous stones are made -water-proof by heating the cement in a boiler and adding sufficient -linseed oil to form a mass which can be readily worked with a smoothing -board. Apply as hot as possible. - -_Serbat’s mastic._ Pyrolusite 60 parts, sulphate of lead 60, linseed -oil 10. - -After thoroughly drying the materials, mix the sulphate of lead with -the linseed oil, then add 20 parts of the pyrolusite and, after mixing -and working it thoroughly, add gradually the rest of the pyrolusite in -small portions and kneading constantly. - -_Stephenson’s oil cement._ Litharge 20 parts, unslaked lime 10 parts, -sand 10 parts, hot linseed oil 3 parts. - -_Alum cement._ Dissolve good hard soap, by heating in rain water, -dilute the thickly fluid mass and add saturated alum solution as -long as a precipitate is formed. Collect the gelatinous precipitate -of alumina soap thus formed upon a cloth, and, after draining, pour -rain water over it ten to twelve times to remove the salts as much as -possible. After washing, dry the alumina soap, and rub it to a fine -powder. - -To prepare cement rub a portion of the powder with sufficient -linseed-oil varnish to form a plastic dough, which is used for filling -in the joints. - -This cement is water-proof, resists high temperatures without being -absolutely fire-proof, and, on account of its light color, is well -adapted for joining marble plates, etc. - -_Oil cement for glass._ Litharge 30 parts, burnt lime 20, pipe-clay 10, -linseed-oil varnish 6. - -_Oil cement free from lead for steam pipes._ Graphite 12 parts, heavy -spar 16, slaked lime 6, boiled linseed oil 6. - -_Oil cements for steam pipes._ I. Litharge 25 parts, air-slaked lime -10, quartz sand 10. - -Mix the ingredients quickly with the linseed oil and work the mass -thoroughly in a hot mortar. Coat the defective places in the pipes with -linseed-oil varnish, apply the cement hot and when partially solid, -make it still tighter by heating. - -II. Boil 60 parts of graphite, 50 of air-slaked lime, 60 of elutriated -heavy spar in 35 of linseed oil, stirring constantly. Apply the mixture -hot. - -_Oil cement for marble._ Elutriated litharge 10 parts, brick dust 100, -linseed oil 20. - -Prepare in the same manner as glaziers’ putty. For various colors add -zinc white for white, red lead for red, pyrolusite for brown, etc. -Previous to applying the cement saturate the surfaces of the stones to -be cemented with linseed-oil varnish. - -_Oil cement for porcelain._ Stir 20 parts of white lead and 12 of white -pipe-clay into 10 of boiling linseed oil previously boiled and knead -the mass thoroughly. After cementing let the articles stand quietly for -several weeks. - -_Diamond cement._ Litharge 30 parts, air-slaked lime 10, whiting 20, -graphite 100, linseed oil 40. Apply hot. This is an excellent cement -for metal. - -_Hager’s diamond cement._ Whiting 16 parts, elutriated graphite 50, -litharge 16. - -Mix the pulverized ingredients with sufficient old, thick linseed oil -to form a plastic dough. - - -RESINOUS CEMENTS. - -_Resinous cement for amber_ is obtained by melting mastic in linseed -oil. Volatile copal lacquer can also be advantageously used for the -purpose. - -_Cement for turners._ Melt 1 lb. of rosin in a tin can over the fire, -and when melted add 4 ozs. of pitch; while these are boiling add brick -dust until, by dropping a little on a cold stone, you think it is hard -enough. In winter it may be found necessary to add a little tallow. - -By means of this cement a piece of wood may be fastened to the chuck, -which will hold when cool, and when the work is finished, it may be -removed by a smart blow with the tool. All traces of the cement may be -removed from the work by repeated applications of benzine. To use this -cement, chip off as much as will cover the chuck to the 1/16th of an -inch, spread it over the surface in small pieces, mixing it with ⅛ of -its bulk of gutta-percha, then heat an iron to a dull red heat, and -hold it over the chuck till the mixture and gutta-percha are melted and -liquid. Stir the cement until it is homogeneous, chuck the work, lay -on a weight to enforce contact, leave it at rest 20 minutes. - -The following cement is much employed and serviceable for the use of -turners and artisans in general. - -Reduce 1 lb. of whiting to a fine powder, and heat to redness so as to -expel all the water. When cold this is mixed with 1 lb. of black rosin -and 1 oz. of beeswax previously melted together, and the whole stirred -till of uniform consistence. - -_Cement for ivory and bone._ Melt at a moderate heat equal parts of -white wax, rosin, and oil of turpentine to form a thickly-fluid mass. -For coloring the cement add elutriated red lead, ultramarine, etc. - -_Cement for white enameled clock-faces._ Dammar resin 100 parts, copal -100, Venice turpentine 110, zinc white 60, ultramarine 3. - -Apply hot and polish when cold and hard. - -_Cements for glass._ 1. Melt carefully 60 parts of bleached shellac and -10 of turpentine. If too thick, dilute with turpentine. - -2. Shellac 20 parts, elemi 5, turpentine 10. Prepare as above. - -_Cement for glass upon glass._ Shellac 10 parts, turpentine 2, -pulverized pumice stone 10. - -_Cement for glass upon metal._ Melt together 40 parts of rosin, 20 of -rouge, 10 of wax, and 10 of turpentine. Apply hot to the surfaces to be -cemented. - -_Cement for metal letters upon glass._ Rosin 42 parts, turpentine 4, -plaster of Paris 5. - -_Cement for wood._ 100 parts of shellac and 45 of strong spirit of wine. - -This cement serves for joining wood, which, on account of exposure to -water, cannot be glued. Apply the cement to the surface of one of the -pieces, and after placing upon it a piece of tissue paper press upon it -the other piece of wood previously coated with the cement. - -_Cement for knife handles._ Melt together 20 parts of rosin, 5 of -sulphur, and 8 of iron filings. - -Pour some of the hot mixture into the handle, and then push in the -knife previously heated. - -_Cement for petroleum lamps._ Boil 12 parts of rosin in 16 of strong -lye until it is entirely dissolved and on cooling forms a tenacious -solid mass. Dilute this with 20 parts of water, and carefully work into -it 20 parts of plaster of Paris. This cement is insoluble in petroleum, -and is especially adapted for cementing the glass parts of lamps to the -metal. It is also a good material for stoppers for petroleum bottles. - -_Cement for porcelain._ Rosin, 14 parts; elemi, 7; shellac, 7; mastic, -7; sulphur, 42; brick dust, 20. - -_Cement for porcelain which is to be heated._ Heat carefully 10 parts -of amber in a large spoon, stirring constantly, until it evolves heavy -vapors of a strong odor. Rub the melted mass as finely as possible, -and after placing the powder in a bottle pour over it a mixture of -bisulphide of carbon and benzine. Close the bottle air-tight to -prevent the evaporation of the very volatile solvent. When the powder -is dissolved remove the cork and replace it by one provided with a -small brush. The application of the cement and pressing together of -the parts to be cemented must be effected as quickly as possible. -In articles properly cemented the joint can only be detected by the -closest examination. This cement holds so well that cups and saucers, -soup-tureens, etc., mended with it can be used for years. - -_Cement to withstand the action of petroleum._ Dissolve 5 parts of -shellac, 1 of turpentine in 15 of petroleum. This cement is quite -elastic. - -_Cement for mica._ A colored cement for joining sheets of mica is -prepared as follows: Soak clean gelatine in water, and when swelled -squeeze out the excess of water by pressure between a cloth, then melt -the gelatine by the heat of a water-bath, and stir in just enough proof -spirit to make it fluid. To each part of this solution add, while -stirring, ¼ oz. of gum ammoniac and 1½ ozs. of gum mastic dissolved in -4 ozs. of rectified alcohol. Put the mixture into bottles, and when -required for use stand the bottle in hot water. This cement resists -cold water. - -_Cement for horn, whalebone and tortoise shell._ Dissolve gum mastic 10 -parts and turpentine 4, in 12 of linseed oil. Apply hot. - -_Cement for terra-cotta articles._ Melt together 70 parts of rosin, -70 of wax and 16 of sulphur, and stir into the mass 8 parts of hammer -slag and 8 of quartz sand. Coat the fractured surfaces with oil of -turpentine, apply the cement as quickly as possible, and press the -surfaces together. It is advisable to heat the terra cotta previously -to 158° or 176° F. After cementing the article, smooth the joint with a -heated knife and dust very fine terra-cotta powder through a linen bag -upon the soft cement in order to give it exactly the same color as the -article itself. - -_Mastic cement for glass._ Gum mastic 15 parts, bleached shellac 10, -turpentine 5. - -This mass sufficiently diluted with hot oil of turpentine furnishes -an excellent cement for fractured glass and gems. Being colorless, -the joint can scarcely be detected, provided the cementing has been -skilfully done. - -To attach gems to glass of the same color, the cement is colored with -aniline colors dissolved in spirit of wine, care being had to give it -the same shade as the gem and the glass. - -_Stick mastic cement._ Melt together, at as low a temperature as -possible, 10 parts of mastic and one of turpentine, and pour the mass -into suitable moulds. - -For use, heat the fractured surfaces of the article strongly, so that -the cement on being rubbed over them melts, then press the surfaces -together and continue the pressure until the cement solidifies. - -_Sulphur cement for porcelain._ White pitch 18 parts, sulphur 28, -bleached shellac 4, gum mastic 8, elemi 8, glass meal 28. Melt all -together, except the glass meal and stir the latter into the melted -mass. - -_Insoluble cement for wooden vessels._ Melt together 60 parts of rosin, -20 of asphalt, and 40 of brick dust. Pour the hot mixture into the -joints. This cement resists the action of lye, quick lime, sulphuric -and hydrochloric acids. - - -RUBBER CEMENTS. - -These cements are very useful, but owing to the inflammable nature of -the components, great care should be taken to guard against fire while -preparing them. They should never be made near a naked fire, as the -benzine, carbon disulphide or chloroform used to dissolve the rubber is -very volatile, and the vapor given off permeates the air until, coming -near a source of light, the whole air becomes one vivid sheet of flame. -Vessels which are used should be closed, and if possible put out of -doors. If heat is required to assist the solvent action, use a sand or -hot-water bath, but on no account bring near a fire. - -_Cements for glass._ I. Rubber 1 part, gum mastic 12, dammar 4, -chloroform 50, benzine 10. - -II. Rubber 12 parts, chloroform 500, gum mastic 120. - -This cement adheres immediately, and possesses a high degree of -elasticity. It may be used to advantage for joining together the glass -panes of hot-houses. - -III. Dissolve, without application of heat, rubber 2 parts and gum -mastic 6, in 100 of chloroform. This cement is perfectly transparent. -It should be applied as quickly as possible, as it sets in a very short -time. - -_Soft rubber cement._ Melt 10 parts of tallow in a brass pan and -gradually add 150 parts of rubber in small pieces, and stir constantly -until all the rubber is dissolved. Keep in readiness a well-fitting -lid to be able to extinguish the flame immediately in case the rubber -catches fire. When all is melted stir in 10 parts of slaked lime. - -This cement is especially adapted for sealing bottles containing -caustic substances, such as nitric acid, etc. It remains always -tenacious, being therefore suitable for cementing bodies exposed to -repeated shocks. - -_Hard rubber cement._ Rubber, 150 parts; tallow, 10; red lead, 10. - -This cement is prepared in the same manner as the above. The addition -of red lead gives it a red color, and solidifies it in a short time to -a mass as hard as stone. - -_Elastic cement._ Carbon disulphide, 8 ozs.; fine rubber, 1 oz.; -isinglass, 4 drachms; gutta-percha, 1 oz. Dissolve the solids in the -fluid. - -This cement is used for cementing leather and rubber. For use the -leather is roughened and a thin coat of the cement applied and allowed -to dry completely; then the two surfaces to be joined are warmed and -placed together and allowed to dry. - -_Marine glue._ This cement, which is only a glue in name, is -water-proof, and can be used to cement metal, wood, glass, stone, -pasteboard, etc., and is especially adapted for caulking vessels. - -Suspend 10 parts of rubber inclosed in a bag in a vessel containing 120 -parts of refined petroleum, so that only half of the bag is immersed, -and allow it to remain ten to fourteen days in a warm place. Then melt -20 parts of asphalt in an iron boiler and add the rubber solution in a -thin jet, and heat the mixture, while constantly stirring, until it is -perfectly homogeneous. Pour it into greased metallic moulds, where it -forms into dark-brown or black plates difficult to break. In using it, -it should be melted in a kettle placed in boiling water to prevent its -burning, which it is very apt to do, as it is a bad conductor of heat. -After it has been liquefied remove the kettle from the water and place -it over a fire, where it can be heated, if necessary, to make it more -fluid, to 302° F., carefully stirring it to prevent burning. - -If possible, the surfaces to be glued together should be heated to -212° F., as the glue can then be slowly applied. The thinner the layer -of glue in cementing together smooth surfaces, the better will it -adhere. But a somewhat thicker layer is required for rough surfaces, -for instance, boards not planed, the excess of glue being forced out by -strong pressure. Generally speaking, it is best to subject all articles -cemented together with marine glue to as strong a pressure as possible -until the glue is congealed. - -Repeated experiments have shown that with the aid of this cement square -vats perfectly water-tight can be constructed of boards. Wooden pegs -dipped in the compound should be used for putting the vats together. - -_Jeffrey’s marine glue._ Dissolve 1 part of rubber in benzine, and mix -the solution with 2 parts of shellac by the assistance of heat. - -_Another formula_ is as follows: Coal naphtha 1 quart, rubber cut in -shreds 2 ozs. Macerate for 10 or 12 days and then rub smooth with a -spatula on a slab; add 2 parts by weight of shellac to 1 part of this -solution. To use the compound melt it at about 240° F. - -_Marine glue for damp walls._ Rubber 10 parts, whiting 10, oil of -turpentine 20, carbon disulphide 10, rosin 5 and asphalt 5. Dissolve -the ingredients in a suitable vessel and stand in a warm place, shaking -it frequently. - -Scrape the wall smooth and clean, and apply the glue with a broad brush -on the damp place and about 8 inches higher than the line of dampness. -Before the glue is dry lay on plain paper which will adhere tightly. On -this plain paper the wall paper can be pasted in the usual manner. If -carefully done, the wall paper will always remain dry. - - -GUTTA-PERCHA CEMENTS. - -_Cement for leather._ Gutta-percha 100 parts, pitch or asphalt 100, oil -of turpentine 15. - -This cement should be used hot. It is suitable for cementing all kinds -of substances, but adheres particularly well to leather. - -_Cement for hard rubber combs._ _A._ Prepare a very thick solution of -bleached gutta-percha in bisulphide of carbon. - -_B._ Dissolve sulphur in bisulphide of carbon. - -The cementing is effected by applying solution _A_ to the fractured -surfaces and pressing them together. When dry brush solution _B_ over -the cemented place. - -_Elastic gutta-percha cement._ Dissolve 10 parts of gutta-percha in 100 -of benzine, then pour the clear solution into a bottle containing 100 -parts of linseed-oil varnish and unite both by shaking. This cement -excels in elasticity, and is especially suitable for attaching the -soles of shoes, as it is so elastic that it will not break, no matter -how much it is bent. To make it adhere tightly roughen the leather on -the side to be cemented. - -_Cement for horses’ hoofs._ For filling cracks and fissures in horses’ -hoofs a cement is required which possesses great resistance to the -action of water combined with elasticity and solidity. A mass answering -all demands consists of 10 parts by weight of gum ammoniac and 20 to -25 of purified gutta-percha. Heat the gutta-percha to between 194° -and 212° F., and then work it with the finely powdered gum ammoniac -to a homogeneous mass. In using it, soften the cement by heating, and -after carefully cleansing the crack in the hoof, apply it with a heated -knife. The cement solidifies immediately after cooling to the ordinary -temperature, and becomes soon so hard as to allow of nails being driven -into it. - -_Cement for crockery._ Gutta-percha 1 part, shellac 1. - -Place the two ingredients in an earthenware jar, and melt the two -together by standing this jar on a vessel of boiling water, or else one -filled with hot sand, the vessel holding the water or sand being heated -over a fire or gas furnace. Stir the melted ingredients well together. -The resulting cement is one possessing great hardness and toughness, -which suits it admirably for mending crockery. Warm the edges to be -joined together, smear the cement on, join together, and hold the -article thus joined until cool. - -_Cement for leather._ Mix 10 parts of carbon disulphide with 1 part -of turpentine, and then add sufficient gutta percha to make a tough, -thickly-fluid mass. Before using this cement, free the surface to be -joined from grease. To effect this, sprinkle a little bicarbonate of -soda, carbonate of ammonia or borax on the surfaces to be joined, lay -a cloth over them, and then place a hot iron on top, and keep it there -a short time so as to cause the alkali to cut the grease, then put the -cement on both surfaces to be joined, put them together and subject to -pressure until they are cemented. - -Gutta percha dissolved in carbon disulphide to the consistency of syrup -is also a good cement for joining leather. The parts to be joined -should be well covered with cement so as to fill the pores of the -leather, then the cement is heated and the parts hammered until the -cement is cold. - - -CASEINE CEMENTS. - -_Preparation of pure caseine._ Although the caseine contained in old -cheese can be used, the other constituents, such as fat, salt, and free -acid, exert an injurious influence upon the solidity of the cement -prepared with it. It is, therefore, best to prepare pure caseine, which -is easily accomplished in the following manner: - -Put milk in a cool place, and after taking off the cream as long as any -is formed, remove the skimmed milk to a warm place to coagulate. After -heating the curd, place it upon a filter and wash the caseine remaining -upon the filter with rainwater until the water running off shows no -trace of acid. - -To remove the last traces of fat tie the washed caseine in a cloth and -after boiling it in water, spread it upon blotting paper in a warm -place to dry. It will shrivel up to a horny mass. - -When thoroughly dried pure caseine will keep for a long time without -suffering alteration. To obtain the caseine in a form suitable -for preparing cements it is only necessary to pour water over a -corresponding quantity and allow it to stand for some time. Caseine -combines with lime to a hard insoluble mass. - -Ordinary technical caseine may be readily and cheaply prepared as -follows: Skim milk is heated in a copper boiler, if necessary by the -introduction of steam, to 122° F. Then add for every 1000 quarts of -milk, 3 quarts of crude hydrochloric acid diluted with 5 to 6 times -the quantity of water. After coagulation, the whey is drained off, the -curd spread out upon an inclined table and allowed to cool. The curd is -then washed by pouring cold water over it through a rose, or stirring -it up with water in a barrel, allowing to settle, and pouring off the -supernatant water. The residue is subjected to moderate pressure. The -caseine while still moist is comminuted in a curd-mill and packed in -bags. In this state it must be worked at once, as otherwise it spoils -readily and is attacked by worms. If it is to be kept for a longer -time, it has to be dried. This is effected by spreading it out upon -linen cloths and placing it in a drying chamber. - -In this manner 8.5 per cent. of moist, or 3.5 per cent. of dry, caseine -is obtained which is brought into commerce as technical caseine or -lactarine. It being insoluble in water, 10 per cent. of an alkali—soda, -borax, or ammonia—has to be added to effect solution. Water-soluble -caseine is seldom found in commerce, the consumer preparing it, as a -rule, himself. - -A purer technical caseine is obtained according to John A. Just’s -method as follows: Dissolve, stirring constantly, in 115 quarts of -water heated to between 104° and 131° F., 17 to 26 ozs. of bicarbonate -of soda and 176 lbs. of moist, or 118 lbs. of dry, caseine, and dry the -solution upon a heated revolving metal cylinder. After each revolution -of the cylinder, the dry material is scraped off with brushes and by -being forced through a fine-meshed sieve yields soluble caseine powder. - -_Caseine cement which can be kept for a long time._ Convert into -powder, each by itself, 200 parts of caseine, 40 of burned lime, and -1 of camphor. Mix the powders intimately and keep the mixture in an -air-tight bottle. For use, mix some of the powder with the requisite -quantity of water and use the cement at once. - -_Cement for glass._ Old dry cheese 100 parts, water 50, slaked lime 20. - -Free the cheese from rind, and rub it with the water until a -homogeneous mass drawing threads is formed. Then stir in quickly the -lime powder, and use the cement at once. It unites not only glass to -glass, but can also be used for cementing metal to glass. - -_Cement for metals._ Elutriated quartz sand, 10 parts; caseine, 8; -slaked lime, 10, and sufficient water to form a cream-like mass. - -_Cement for porcelain._ Caseine dissolves readily in solution of -water-glass, and forms then one of the best cements for porcelain -known. To prepare it, fill a bottle one-quarter full with fresh -caseine, and after filling the bottle with solution of water-glass, -effect the solution of the caseine by frequent shaking. - -_Cement for meerschaum._ Dissolve caseine in water-glass, and after -stirring quickly finely-pulverized calcined magnesia into the mass, use -it at once, as it solidifies very soon. By adding, besides magnesia, -genuine meerschaum finely pulverized, a mass closely resembling -meerschaum is obtained, which can be used for manufacturing imitation -meerschaum. - -_Cement for wood, etc._ Rub 10 parts of caseine and 5 of borax -to a thick, milky mass, and use it like glue. This cement can be -advantageously used for pasting labels upon wine bottles, as it neither -moulds nor becomes detached in the cellar. - -_Another formula_ is as follows: Dissolve borax by boiling in water, -and pour the solution over fresh caseine. The result will be a clear, -thick mass of extraordinary power of adhesion, which can be kept for -any length of time without suffering decomposition. - -Applied to leather, paper, linen or cotton goods, it forms a coat of -beautiful lustre, and for this reason is much used in the manufacture -of fancy articles of paper and leather. - -_Cement for porcelain._ Dissolve 10 parts of caseine in 60 of -water-glass solution. Apply the cement quickly and dry the cemented -articles in the air. - - -WATER-GLASS AND WATER-GLASS CEMENTS. - -_Water-glass._ Water-glass (silicate of soda or soluble glass) is -found in commerce as a thickly-fluid, tenacious mass. It is generally -prepared by fusing 15 parts of quartz sand with 8 of carbonate of -soda and 1 of charcoal. The silicic acid combining with the soda -disengages the carbonic acid, the expulsion of which is facilitated by -the presence of charcoal, which converts it into carbonic oxide. It -dissolves readily in water. The solution has a strongly alkaline taste, -and possesses the property of being gradually converted, on exposure to -the air, to a gelatinous mass which finally solidifies. For this reason -water-glass should be kept in bottles hermetically closed with corks. -Glass stoppers are of no use, as they are so firmly cemented to the -bottle that on attempting to open the latter the neck breaks off. - -By combining water-glass with cement or burned lime the resulting mass -solidifies quite rapidly to a mass as hard as stone, and generally -capable of resisting chemical action. - -Water-glass by itself is only fit for cementing glass to glass, but -combined with other substances it furnishes very durable and solid -cements. - -_Cement for cracked bottles._ Select a cork which will fit the bottle -air-tight and place it loosely upon the bottle, and heat the latter -gradually to at least 212° F. Then press the cork down and apply a -thick solution of water-glass to the cracks. In cooling, the air in the -bottle contracts strongly, and the pressure of the exterior air drives -the water-glass with great force into the cracks closing them entirely -so that they cannot be detected. - -_Cement for glass and porcelain._ Stir quickly together 10 parts of -elutriated glass meal, 20 of powdered fluor spar, and 60 of water-glass -solution, and apply the homogeneous paste at once. In a few days the -cement will be so hard that the cemented vessels can be heated without -danger. - -_Cement for hydraulic works._ Finely powdered cement, and solution of -water-glass. Mix the two bodies quickly together. - -As this cement hardens very quickly, it should be used fresh. It -hardens under water, and is therefore excellent for hydraulic works. -The stones should be coated with a solution of water-glass before -applying the cement. - -_Cement for uniting metals._ A strong cement, which hardens rapidly, is -made by stirring the finest whiting in a solution of soda-glass of 33° -B., made so as to form a plastic mass. This can be readily colored to -any desired shade. The addition of sifted sulphide of antimony gives -a black cement, which by polishing acquires a metallic lustre; iron -filings render it grayish-black; zinc dust turns it green, but after -polishing, it appears like metallic zinc, and may be employed for the -permanent repair of zinc ornaments, etc. Carbonate of copper imparts a -light green shade. Other additions may be made, as oxide of chrome for -dark green, cobalt blue for blue, red lead for orange, vermilion for -scarlet, carmine for violet, etc. - -_Cement for tightening joints of pipes exposed to a red heat._ Mix 80 -parts of pyrolusite, 100 of zinc white, and 20 of water-glass. - -This cement fuses at a temperature not too high, and then forms a -glass-like mass which adheres very firmly and closely. - -_Cement for marble and alabaster._ The point of fracture of articles -cemented with the following mixture is difficult to find, and the -cemented place is much stronger than the material itself. Mix 12 -parts of Portland cement, 6 of slaked lime, 6 of fine sand, and 1 of -infusorial earth with sufficient water-glass to form a thick paste. The -article to be cemented need not be heated. It hardens in twenty-four -hours. - - -GLYCERINE AND GLYCERINE CEMENTS. - -Commercial glycerine is a yellowish or nearly colorless and more or -less viscid liquid having an intensely sweet taste. In combination with -lead oxide and intimately worked into it, by heating and stamping, -it furnishes very strong and durable cements deserving general -introduction, though thus far they have been but little used. - -For the manufacture of cements the use of pure odorless glycerine -is not required, the yellow crude article, which is much cheaper, -answering all purposes. The principal point is to use very highly -concentrated glycerine, as otherwise the cements prepared with it -solidify very slowly and besides do not possess a proper degree of -hardness and solidity. - -It is of especial importance to have the lead oxide free from water. To -accomplish this, heat it thoroughly and mix it with the glycerine while -still hot. Cement thus prepared solidifies very quickly, and can be -used for many purposes. It is an excellent material for quickly joining -the stones of submarine works. - -_Glycerine and litharge cement._ Moisten elutriated litharge with -glycerine so that a thin homogeneous paste is formed. This cement is -adapted for uniting the joints of steam pipes, cementing wood, glass, -porcelain, and also glass upon metal, etc. It solidifies to a very hard -mass in a quarter to three-quarters of an hour. Before applying the -cement coat the surfaces to be joined with pure glycerine. - - -LIME CEMENTS. - -Quick lime, slaked lime and chalk are used for this purpose. Quick -lime, which is obtained by burning limestone, combines gradually with -the fats to insoluble lime soaps. Slaked lime, which consists of a -combination of lime with water, acts in the same manner. - -For the preparation of cements the lime is slaked by placing it in a -dish and pouring as much water over it as it will absorb. Good lime, -technically called _fat lime_, should eagerly combine with water, -evolving much heat, swelling greatly, and crumbling to a light white -powder. - -Quick lime exposed to the air until, by the absorption of moisture and -carbonic acid, it is converted into a powder is called _air-slaked_. - -Cements prepared with quick lime will, as a rule, solidify more quickly -than those prepared with air-slaked lime. - -Chalk is a carbonate of lime consisting of the shells of microscopic -animals, and can be readily pulverized and elutriated. In the latter -state it is known as _whiting_. For the preparation of entirely white -cements the use of pure white lime or chalk is absolutely necessary. -Yellow or reddish lime contains oxide of iron, and furnishes cements of -the same tinge. - -_Cement for glass._ Litharge 30 parts, quick lime 20, linseed-oil -varnish 5. - -_Cement for joiners._ A cement for filling up cracks and holes is -obtained by mixing slaked lime 50 parts, flour 100, linseed-oil varnish -15. - -_Cement for cracked clay crucibles and porcelain._ By applying to the -cracks a mixture of 10 parts of slaked lime, 10 of borax, and 5 of -litharge in sufficient water to form a stiff paste, and drying after -heating the crucible, the cracked places will be united so firmly that -the crucible, when thrown to the ground, will generally break in any -other place than the cemented one. - -This cement can also be used for porcelain capable of standing a strong -heat. - -_Lime and glue cement._ Stir air-slaked lime into hot glue. This cement -is especially suitable for attaching metal to glass. It forms a very -hard yellowish-brown mass. - - -GYPSUM CEMENTS. - -Sulphate of lime in combination with water is met with in nature, both -in the form of transparent prisms of _selenite_, and in opaque and -semi-opaque masses, known as _alabaster_ and _gypsum_. By pulverizing -the latter and heating to about 302° F. it loses its water, and is -converted into anhydrous gypsum or _plaster of Paris_, which on mixing -with water recombines with it to form a mass of hydrated sulphate of -lime, the hardness of which nearly equals that of the original gypsum. -When the powder is mixed with water to a cream and poured into a mould, -the minute particles of anhydrous sulphate of lime combine with the -water to reproduce the original gypsum, and this act of combination -is attended with a slight expansion which forces the plaster into the -finest lines of the mould. - -By using a solution of alum instead of ordinary water, a plaster is -obtained which, although it takes much longer to set than the ordinary -kind, is much harder, and therefore takes a good polish. - -For preparing cements only perfectly white plaster of Paris should be -used, as the gray article possesses but little adhesive power. - -_Cement for plaster of Paris statues._ To repair plaster of Paris -statues so that the point of fracture cannot be detected, proceed in -the following manner: - -Moisten the fractured surfaces with water by means of a brush until -they absorb no more and remain moist. Mix plaster of Paris with -water to a thin cream and stir until the heat appearing at first has -ceased, which will prevent the conversion of the plaster into a solid -coherent mass. Apply quickly a thin layer of the plaster to one of the -fractured surfaces, press the other against it until the plaster has -set, and, when dry, carefully remove the excess by scraping. - -_Cement for glass and porcelain._ Mix quickly 50 parts of plaster of -Paris, 10 of quick lime, and 20 of white of egg. Use at once, as the -cement solidifies very rapidly. - -_Cement for iron and stone._ A very useful cement for securing iron -railing in stone is obtained by mixing 30 parts of plaster of Paris, 10 -of iron filings and 20 of vinegar. - -_Cements for porcelain._ I. Mix plaster of Paris with saturated -solution of alum to a cream. After moistening the fractured surfaces -apply a thin layer of the cement, press the surfaces together, wrap a -wire or cord tightly around them, and let the article stand quietly for -a few weeks. The cement is converted into a mass as hard as stone. - -II. Mix plaster of Paris with a thick, clear solution of gum arabic and -cement the articles as soon as possible. Although this cement adheres -very tightly, porcelain vessels cemented with it cannot be used for -liquids. - -_Universal plaster of Paris cement._ Mix 21 parts of plaster of Paris, -3 of iron filings, 10 of water, and 4 of white of egg. This cement is -suitable for attaching metal to glass, metal to stone, etc. - - -IRON CEMENTS. - -_Heat-resisting cement._ Clay 10 parts, iron filings 5, vinegar 2, -water 3. - -_Water and steam-proof cement._ Iron filings 100 parts, sal-ammoniac 2, -water 10. - -This cement rusts very much in a few days, and is converted into an -extremely solid mass which is perfectly steam- and water-proof. - -_Cement for iron._ Mix 65 parts of wrought-iron filings, 2.5 of sal -ammoniac, and 1.5 of flowers of sulphur, and then add 1 part of -sulphuric acid diluted with sufficient water to form a stiff paste. -This cement solidifies in two to three days, and rusts, with the parts -of iron to be cemented, to an extraordinarily durable mass. - -_Fire-proof cement for iron pipes._ Wrought-iron filings 45 parts, clay -20, fire-clay 15, common salt solution 8. - -_Cements resisting high temperatures._ 1. Iron filings 20 parts, clay -powder 45, borax 5, common salt 5, pyrolusite 10. - -Dissolve the borax and common salt in the water, add and mix quickly -the clay powder, pyrolusite, and iron filings. Apply the cement at -once. Exposed to a white heat, it hardens to a tightly adhering, glassy -mass. - -2. Mix 52 parts of pyrolusite, 25 of zinc white, and 5 of borax with -solution of water-glass to a paste, and use at once. This cement -requires to be gradually dried. It will stand the highest temperatures. - -_Cement for filling in defects in castings._ Stir 100 parts of iron -filings free from rust with sufficient water to form a thick paste, and -press the mixture into the fissures, cracks, etc. The cement becomes -solid only after the iron filings become strongly rusted. To free the -ingredients from adhering fat, wash them, before mixing, in liquid -ammonia. - -_Cement for cracked stove plates, etc._ Knead 20 parts of iron filings, -12 of iron scale, 30 of plaster of Paris, and 10 of common salt with -blood to a stiff paste, and use at once. Instead of blood, water-glass -can be used, it having the advantage of being odorless on strong -heating, while blood cement evolves a disagreeable odor. - -_Cement for iron water tanks._ Knead iron filings with vinegar to -paste. Allow the mixture to stand until it turns brown, and then force -it into the joints by means of a chisel. - -_Cement for cracked iron pots._ Knead 10 parts of iron filings and -60 of clay with linseed oil to a thick paste. Before applying it add -a little linseed oil, and allow it to dry slowly. In a few weeks the -cement will be so hard that the vessels can be used without danger. - -_Black cement for stoves._ Iron filings 10 parts, sand 12, bone black -10, slaked lime 12, glue water 5. - -_Cements for iron stoves._ 1. Pulverize as finely as possible and mix -intimately 4 to 5 parts of clay, 2 of iron filings free from rust, 1 of -pyrolusite, ½ of common salt, and ½ of borax with water to a paste, and -apply the cement quickly to the places to be cemented and allow it to -dry slowly. This cement will stand a white heat, and resist the action -of boiling water. - -2. Mix intimately and as quickly as possible 1 part of pulverized -pyrolusite, and 1 of zinc white with solution of water-glass to a -plastic mass, which solidifies quickly. The power of resistance of this -cement, it is claimed, is not inferior to No. 1, though experiments -have proved No. 1 to be preferable. - - -CEMENTS FOR CHEMICAL APPARATUS. - -Cements to be used for the above purpose must possess various -properties difficult to combine in one preparation. They must be -gas-proof, and capable of resisting the action of different vapors and -acid fluids. As regards resistance to the action of chemical agents, -there is nothing better than caoutchouc, but unfortunately it can -only be used for tightening chemical apparatus not exposed to a high -temperature. - -In chemical laboratories bran of almonds, either by itself or kneaded -with water to a thick paste, is frequently used, or rye or wheat -bran mixed with a little flour and water. These cements, though very -suitable for cementing glass distilling apparatus, are strongly acted -upon by chlorine and the vapors of nitric acid. - -For small apparatus to be used for the development of fluoric acid, -plaster of Paris mixed with a little water can be used as a cement. -To make the joint entirely gas-tight, paste a strip of paper over it. -Although this cement does not resist the action of fluoric acid for -any length of time, it suffices generally for the protection of the -Workmen during the time the development of the acid is in progress, as, -for instance, in chemical analyses, etc. - -To cement chemical apparatus exposed to a temperature not exceeding 86° -to 104° F. paraffine does excellent service; as it possesses the power -of resisting the action of the strongest acids and alkalies. - -Below will be found a few receipts for cements which have proved -reliable. - -_Linseed oil and clay cement._ Knead 10 parts of dry clay with 1 of -linseed oil to a homogeneous mass. This cement will stand heating to -the boiling-point of mercury. - -_Linseed oil, zinc and manganese cement._ Knead 10 parts of pyrolusite, -20 of zinc white, and 40 of clay with sufficient boiled linseed oil -(not exceeding 7 parts) to a plastic mass. This cement will stand a -somewhat higher temperature than the preceding one. - -_Cements resisting very high temperatures._ I. Clay 100 parts, powdered -glass 2. - -The glass melts on exposure to great heat and slags the clay to a hard -mass. The same effect is produced by adding small quantities of soda -and borax to the clay. An admixture of chalk and boric acid, as in the -following receipt, also gives excellent results. - -II. Clay 100 parts, chalk 2, boric acid 3. - -_Cement resisting acids._ Melt rubber with double the quantity of -linseed oil, and then knead in sufficient bole to form a paste. This -cement resists the action of nitric and hydrochloric acids, and can -be advantageously used for closing bottles containing them. As it -solidifies very slowly, it can readily be detached from the bottles, -and used again. - -For cement which is to solidify quickly on exposure to the air, add a -few per cent. by weight of red lead or litharge. - -_Rubber cement for chemical apparatus._ Cut 8 parts of rubber in small -pieces and throw them gradually into a mixture of 2 parts of tallow -and 16 of linseed oil previously strongly heated. After effecting an -intimate mixture of the constituents by vigorous and constant stirring, -add 3 parts of white bole. - -Although this cement does not stand a high temperature, it possesses an -extraordinary power of resisting the action of acid vapors. - -_Scheibler’s cement for chemical apparatus._ Melt together 1 part of -wax and 3 of shellac, and work into the mixture 2 parts of gutta-percha -cut up in very small pieces. This cement will bear considerable heat -without actually melting. - - -CEMENTS FOR SPECIAL PURPOSES. - -_Cement for attaching metal letters to glass, marble, wood, etc._ -Dissolve over a water-bath 5 parts of glue in a mixture of 15 parts -of copal varnish, 5 parts of boiled linseed oil, 3 parts of crude oil -of turpentine, and 2 parts of rectified oil of turpentine, and add 10 -parts of slaked lime to the mixture. - -_Cement for joints of iron pipes._ Mix 5 lbs. of coarsely powdered iron -borings, 2 ozs. of powdered sal ammoniac, and 1 oz. of sulphur with -sufficient water to form a paste. This composition hardens rapidly, but -if time can be allowed it sets more firmly without the sulphur. It must -be used as soon as mixed, and rammed tightly into the joint. - -Another receipt is as follows: - -Mix 2 ozs. of sal ammoniac, 1 oz. of sublimated sulphur and 1 lb. of -cast-iron filings or fine turnings in a mortar, and keep the powder -dry. When it is to be used, mix it with 20 times its weight of clean -iron turnings or filings and grind the whole in a mortar; then wet it -with water until it becomes of convenient consistency, when it is to be -applied to the joint. After a time it becomes as hard and strong as the -metal. - -_Steam boiler cement._ Mix 10 parts of finely-powdered litharge with -1 part of fine sand and 1 part of air-slaked lime. The mixture may be -kept for any length of time without deterioration. For use a portion -of it is made into a paste with linseed oil or, better, boiled linseed -oil. In this state it must be applied quickly, as it soon becomes hard. - -_Cement for rubber._ Powdered shellac is softened in 10 times its -weight of strong water of ammonia, whereby a transparent mass is -obtained, which becomes fluid after keeping some little time without -the use of hot water. In three to four weeks the mixture is perfectly -liquid, and when applied it will be found to soften the rubber. As soon -as the ammonia evaporates it hardens again, and thus becomes impervious -both to gases and to liquids. For cementing sheet rubber, or rubber -material in any shape, to metal, glass, and other smooth surfaces, this -cement is highly recommended. - -_Cement for tires._ 1. Isinglass 1 oz., gutta-percha 1 oz., rubber 2 -ozs., carbon disulphide 8 fluid ozs. Mix and dissolve. - -2. Shellac 4 ozs., gutta-percha 4 ozs., red lead and sulphur, each ½ -oz. Melt the shellac and gutta-percha, and add with constant stirring -the red lead and sulphur, melted. Use while hot. - -3. Crude rubber 1 oz., carbon disulphide 8 ozs. Macerate 24 hours, and -then add a solution of: - -Rosin 2 ozs., beeswax ½ oz., carbon disulphide 8 ozs. - -4. Rubber 20 parts, rosin 10, Venetian red 10, tallow 5. Melt the -rubber over a fire, then add the rosin and the tallow and finally the -Venetian red. - -_Cement for steam pipes, etc._ A cement of specially valuable -properties for steam pipes, in filling up small leaks, such as a -blow-hole in a casting, without the necessity of removing the injured -piece, is composed of 5 lbs. Paris white and 5 lbs. yellow ochre, 10 -lbs. litharge, 5 lbs. red lead and 4 lbs. black oxide of manganese. -Mix the materials thoroughly and make into a paste with a small -quantity of asbestos and boiled linseed oil. The composition, as thus -prepared, will harden in from 2 to 5 hours, and has the advantage of -not being subject to expansion and contraction to such an extent as to -cause a leakage afterwards, and its efficiency in places difficult of -access is of special importance. - -_Cement for marble._ Stir to a thick batter with silicate of soda 12 -parts of Portland cement, 6 of slaked lime, 6 of fine white lead and 1 -of infusorial earth. This is excellent for marble and alabaster. The -cemented objects need to be heated. After 24 hours the fracture is -firm, and the place can scarcely be found. - -_Cement for attaching wood, glass, etc., to metal._ Acetate of lead 23 -parts by weight, alum 23, gum arabic 38, wheat flour 250. - -Dissolve the acetate of lead and the alum in a little water and -separately dissolve the gum arabic in a fair quantity of boiling -water. Thus if the 250 parts of wheat flour represent half a pound, -the quantity of water needed will be about a pint. The gum having -dissolved, add the flour, put the whole on the fire, stir well with a -wooden stick, then add the solution of lead acetate and alum. Continue -the stirring in order to avoid the formation of lumps, then take it off -the fire without allowing it to boil. This cement is used cold, and -will not scale. It is very useful in making wood, glass, cardboard, -etc., adhere to metal, and is extremely strong. - -_Brushmakers’ cement._ Rosin 5 lbs., rosin oil or spirit 1 quart. - -Reduce the rosin to small pieces, run down in a pot, add the other -ingredient, and stir until mixed and syrupy, then run out into tins. -It is used for cementing the bristles in the stocks, also for string -binding on sash tools, etc. - -_Cement for electrical apparatus._ Mix together 1 lb. of beeswax -added to 5 lbs. of rosin, 1 lb. of red ochre, and 2 tablespoonfuls of -plaster of Paris. It will make an excellent composition for electrical -apparatus. - -A cheaper composition for cementing voltaic plates into wooden troughs -is made with 6 lbs. of plaster of Paris and ¼ pint of linseed oil. The -ochre and the plaster of Paris should be well dried and added to the -other ingredients when these are in a melted state. - -_Jewelers’ cement._ Dissolve over the water-bath 25 parts of fish glue -in a small quantity of strong spirits of wine, add 2 parts of gum -ammoniac; separately dissolve 1 part of mastic in 5 of spirits of wine. -Mix the two solutions and keep them in well-stoppered bottles. - -_American cement for jewelers._ Soak 4 ozs. of isinglass in 2 lbs. of -water for 24 hours, then evaporate in the water-bath; to 1 lb. add 1 -lb. of rectified spirits of wine, and strain. Then mix in a solution -of 2 ozs. of mastic and 1 oz. of gum ammoniac in 16 ozs. of rectified -spirit. - -_Cement for celluloid._ Shellac 2 ozs., spirits of camphor 2, 90 per -cent. alcohol 6 to 8. - -_Stratena._ This well-known household cement is said to be prepared -as follows: Dissolve 12 parts of white glue in 16 of acetic acid, and -then add this solution to one of 2 parts gelatine in 16 of water. After -mixing add 2 parts shellac varnish. - -_Cement for cloth._ Gutta-percha 16 parts, rubber 4, pitch 2, shellac -1, linseed oil 2 pints. Dissolve the whole by heat, stirring constantly. - - -HOW TO USE CEMENTS. - -It is unquestionably true that quite as much depends upon the manner in -which a cement is applied, as upon the cement itself. The best cement -that was ever compounded would prove entirely worthless improperly -applied. In the foregoing a number of cements have been given which -answer every reasonable demand when properly prepared and properly -used. Good common glue will unite two pieces of wood so firmly that -the fibres will part from each other rather than from the cementing -material; two pieces of glass can be so joined that they will part -anywhere rather than on the line of union; glass can be united to -metal, metal to metal, stone to stone, and all so strongly that the -joint will certainly not be the weakest part of the resulting mass. -What are the rules to be observed in effecting these results? - -The first point that demands attention is to bring the cement itself -into intimate contact with the surface to be united. If glue is -employed, the surface should be made so warm that the melted glue -will not be chilled before it has time to effect a thorough adhesion. -The same is more eminently true in regard to cements that are used -in a fused state, such as mixtures of resins, shellac, and similar -materials. These matters will not adhere to any substance unless the -latter has been heated to nearly or quite the fusing point of the -cement used. This fact was quite familiar to those who used sealing-wax -in the olden days of seals. When the seal was used, in succession, -rapidly so as to become heated, the sealing-wax stuck to it with -a firmness that was annoying, so much so that the impression was -generally destroyed, from the simple fact that the sealing-wax would -rather part in its own substance than at the point of adhesion to the -seal. Sealing-wax or ordinary so-called electric cement is a very good -agent for uniting metal to glass or stone, provided the masses to be -united are made so hot as to fuse the cement; but if the cement is -applied to them while they are cold, it will not stick at all. This -fact is well known to those itinerant venders of cement for uniting -earthenware. By heating two pieces of delf so that they will fuse -shellac, they are able to smear them with a little of this gum and -join them so that they will rather break at any other part than along -the line of union. But although people see the operation constantly -performed and buy liberally of the cement, it will be found that in -nine cases out of ten, the cement proves worthless in the hands of the -purchasers, simply because they do not know how to use it. They are -afraid to heat a delicate glass or porcelain vessel to a sufficient -degree, and they are apt to use too much of the material, and the -result is a failure. - -The great obstacles to the junction of any two surfaces are air and -dirt. The former is universally present, while the latter is due to -accident or carelessness. All surfaces are covered with a thin adhering -layer of air, which it is difficult to remove, and which, although -it may at first sight seem improbable, bears a relation to the outer -surface of most bodies different from that maintained by the air a few -lines away. The reality of the existence of this adhering layer of air -is well known to all who are familiar with electrotype manipulation. -It is also seen in the case of highly polished metals which may be -immersed in water without becoming wet. Unless this adhering layer -of air is displaced, the cement cannot adhere to the surface to -which it is applied because it cannot come in contact with it. The -most efficient agent in displacing this air is heat. Metals warmed -to a point a little above 203° F. become instantly and completely -wet when immersed in water. Hence, for cements that are used in a -fused condition, heat is the most efficient means of bringing them in -contact with the surfaces to which they are to be applied. Another -very important point is to use as little cement as possible. When the -surfaces are separated by a large mass of cement we have to depend -upon the strength of the cement itself and not upon its adhesion to -the surfaces which it is used to join; and, in general, cements are -comparatively brittle. - -The cement forced out of the joint by pressing the surfaces together -should be removed while the cement is in a fused state or liquid. -This can generally be effected by wiping the surplus off, while after -solidification a certain amount of force has to be used which may -frequently break the joint. - -Oil cements, which generally solidify slowly, have the advantage of -being water-proof. In cementing with oil cements, coat the surfaces to -be joined with linseed oil, or, still better, boiled linseed oil, but -in working with resinous cements apply oil of turpentine, spirit of -wine, or a fluid which will readily dissolve the cementing constituent -of the cement. - -For cleansing the surfaces from grease and dirt place the articles in -strong lye and rinse off in clean water without touching the surfaces -with the hands. For painted porcelain articles which cannot be placed -in lye, it is recommended to brush the surfaces several times with -carbon disulphide. - - -PASTES AND MUCILAGES. - -_Preparation of paste._ Ordinary paste is prepared either from flour or -starch, and according to the raw material used in its preparation, may, -therefore, be divided into starch and flour paste. - -Starch is an indispensable constituent of certain parts of plants, and -plays an important part in the nutrition of the plant. It is chiefly -manufactured from potatoes, Indian corn and grain. Examined under the -microscope, it is seen to be composed of small granules consisting of -layers placed one above the other. - -_Starch paste._ In stirring starch with water to a thin paste and -gradually heating it, it will be observed that at a temperature between -140° and 158° F. a peculiar change takes place; the thin milk-white -liquid becomes transparent, opalizes, and at the same time becomes -thickly fluid, in short, the starch is converted into paste. During -this process the separate layers of the starch granules become detached -somewhat in the same manner as an opening bud, whereby they absorb -water, and the peculiar mass, called paste, is formed. That paste is -not a solution is easily proved by the fact that on attempting to -filter starch-paste only water drains off, while the starch remains -upon the filter and gradually dries to a horny mass. - -Paste left to itself soon decomposes, especially during the hot season -of the year; it becomes sour through the formation of lactic acid, -butyric acid, acetic acid, and other substances, and loses its adhesive -power. - -In preparing paste, the following rules must be especially observed: -Divide the starch in water by constant stirring so as to form a -homogeneous, rather thinly liquid fluid, and then add boiling water -in small portions, stirring constantly. The conversion of the starch -into paste is recognized by the thickening of the entire mass and -the appearance of opalescence, when it is only necessary to add the -required quantity of water to give the paste the desired consistency. - -If white lumps are observed, it is an indication that the starch has -not been thoroughly mixed with the water, and that certain portions of -it have remained dry. Paste containing such lumps cannot be applied -with any degree of uniformity, and besides it possesses less adhesive -power. Nothing can be done to remedy the evil except diluting the -paste with a considerable quantity of water and boiling, with constant -stirring, until the mass is perfectly homogenous. - -Starch paste prepared in a proper manner possesses great adhesive -power, and, when applied in a thin layer, dries to an almost colorless -coating. Pure starch paste is used for many purposes. It serves not -only for pasting paper, wall paper, etc., but also for sizing tissues, -such as paper-muslin, linen, etc., in order to give them lustre, body, -and, under certain circumstances, greater weight. To increase the -weight of linen, white lead or heavy spar is frequently mixed with the -starch. - -_Flour paste._ The principal constituent of flour, besides starch, is -gluten. It is obtained in a pure state by tying flour in a linen bag -and kneading it under water so long as the latter is rendered turbid by -particles of starch. The gluten remaining in the bag is a light-brown, -very tenacious mass, drawing threads between the fingers, and, as -regards its chemical properties, is closely allied to albumen and -caseine. Gluten, like the last-mentioned substances, shows a tendency -to form combinations with lime which gradually solidify, and it can -therefore be used for preparing cements. Like albumen and caseine, -it speedily putrefies if exposed to the air in a moist state, and in -decomposing forms products which have a very unpleasant odor. - -Flour paste is prepared in precisely the same manner as starch paste, -but while the latter is white, flour paste, even if prepared from the -best wheat flour, has always a yellow-brown color. As regards adhesive -power it is superior to starch paste, but is less durable. - -There are many means to prevent the spoiling of paste. With paste -once dry and kept so, there is no danger of spoiling, but if it -is alternately exposed to dampness and dryness, as for instance -with wall-paper hung on walls not entirely dry, decomposition will -unavoidably take place, and the wall paper will become spotted and fall -off the wall. - -Provided either starch or flour paste is protected against drying in, -it can be kept unchanged for a long time by the addition of a small -quantity of carbolic acid. - -For hanging wall-paper an addition of alum is, generally speaking, more -suitable than carbolic acid. - -In hanging wall-paper the wall is generally first sized with -glue water. By the alum coming in contact with glue an insoluble -leather-like combination is formed, which not only resists -decomposition, but by far surpasses ordinary paste as regards adhesive -power, so that when the paper is to be removed from the wall it has -to be scraped and torn off in small pieces, while that hung without -previous sizing of the wall is readily removed in large pieces. - -But alum cannot be used for preserving a glue solution, as it would -cause it to coagulate to a flaky mass. Carbolic acid is, on the -other hand, an excellent means for the purpose, but to prevent its -characteristic empyreumatic odor from making itself too sensibly -felt, no more than about one two-thousandth of the weight of the glue -solution should be added. - -_Shoemakers’ paste._ In addition to being cheap, no other paste adheres -as well to leather as the so-called shoemakers’ paste. With it leather -can be secured not only to leather, but also to woven materials, paper, -etc. Though its preparation is very simple, it is connected with some -disagreeable features consisting chiefly in the development of a truly -terrible stench. - -The paste is prepared by stirring crushed barley with hot water to -a thick paste and adding small portions of hot water, so that the -temperature of the mass is kept at between 86° to 104° F. In a few -days the mass commences to develop gas, which shows at first no odor, -but soon the development of gas becomes stronger and an acid odor is -perceptible, which in a short time is replaced by a terrific stench -which, as before mentioned, affects the olfactory organs in a most -unpleasant manner. - -In consequence of the acid and putrid fermentation the pasty mass -gradually loses its granular condition, and is finally converted into a -homogeneous, thickly fluid mass of a brown color, which draws threads -between the fingers, and possesses great adhesive power. When this is -the case, decomposition, which otherwise would go on until nothing -remained but a watery and acid fluid, is interrupted by lowering the -temperature of the paste by ladling it from the vat or by adding a -small quantity of carbolic acid. - -To render the stench developed during the fermentation of the paste -innoxious, the vat in which it is prepared should be provided with -a well-fitting cover, in which is fitted a stovepipe passing into a -chimney connected with a kitchen range or furnace, in which a fire is -frequently burnt. - -By kneading shoemaker’s paste together with indifferent substances it -can be used as a cement for various purposes. The substances best -adapted for the purpose are burnt lime slaked to a powder, whiting, -zinc white, pipe clay, ochre, etc. - -_Gum arabic._ This gum is an exudation from certain tropical species of -acacia, and consists essentially of arabine, which has the composition -C_{12}H_{11}O_{11}. The best gum arabic is that in the form of very -pale-yellow, brittle pieces; golden-yellow to brownish pieces are not -valued as highly, though they give a solution of considerable adhesive -power. - -Gum arabic dissolves in water, but not in alcohol, and therefore can -not be employed for cements in the preparation of which solutions of -resins in spirit of wine are to be used. - -There are other products of vegetable life, which are also in commerce, -called gums, but dissolve partly in spirit of wine. To this class -belongs the gum ammoniac mentioned in some receipts for cements. As it -is rather expensive, it is seldom used by itself as a cement. - -_Dextrine_ is extensively used in place of gum arabic in printing -wall-papers, for stiffening and glazing cards and paper, for thickening -the colors of calico printers, in making mucilages, etc. It is prepared -by heating starch previously moistened with nitric acid in an oven, -and can also be produced by heating paste with malt extract or very -dilute sulphuric acid. There is a current anecdote which attributes the -discovery of dextrine to a conflagration at a starch factory where one -of the workmen who assisted in quenching the fire observed the gummy -properties of the water which had been thrown over the torrefied starch. - -Commercial dextrine forms pale-yellow to dark-brown masses. These -masses dissolve readily in water, and form solutions which, as regards -adhesive power, compare favorably with those prepared from gum arabic. -The mucilage is prepared by simply stirring the pulverized dextrine -with water to a thickly-fluid liquid. - -To preserve mucilage unchanged for any length of time, and to -prevent the disagreeable formation of mould upon its surface, it is -recommended to dissolve some salicylic acid in the water to be used for -preparing the mucilage. - -Dextrine is usually prepared on a large scale by moistening 10 parts of -starch with 3 parts of water acidulated with 1/100 part of nitric acid. -The mixture is allowed to dry, and is then spread upon trays in layers -about three-quarters of an inch deep in an oven, where it is heated for -about one hour to 239° F. Sometimes large drums revolving over a fire -are used, or, in order to keep up a uniform temperature, the starch is -placed in a copper cylinder suspended in a vessel with oil which is -heated to 356° F. The object of the addition of nitric acid is to allow -the starch to be converted into dextrine at a temperature which would -be inadequate to effect the transformation of starch alone. - -Dextrine is also frequently prepared by allowing germinated barley or -malt to act upon starch. Heat 350 to 400 parts of water to about 77° -F., and after adding 5 to 10 parts of dry malt, raise the temperature -to 140° F. Then add 100 parts of starch, and after mixing the whole -thoroughly together, raise the temperature to about 158° F. for twenty -minutes. The mass, which appears at first milky and sticky, will -gradually become as liquid as water by the conversion of the starch -into gum through the action of the malt. To prevent the conversion -of the gum into sugar by the diastase of the malt, the fluid must be -quickly brought to the boiling-point, and, after cooling, filtered -and evaporated to the consistency of syrup. In cooling, the mass -gelatinizes to a jelly, which after drying is hard and brittle. - -According to Blumenthal’s method, a drum which can be hermetically -closed, is filled two-thirds full with dry starch flour by means of a -funnel. A stirring apparatus is then set in motion, and the acid which -is contained in a graduated cylinder is sprayed into the drum by means -of a special contrivance. - -In a drum 5 feet long and 3¼ feet in diameter, 220 lbs. of potato -starch can be uniformly mixed in 5 minutes with about 9 ozs. of nitric -acid of 40° B., and the drum emptied by opening the slide. Starch thus -treated may be brought into the oven without previous drying. - -Heuzé gives the following method: Four and a half pounds of nitric -acid of 1.4 specific gravity together with 300 quarts of water are -mixed with 2,200 lbs. of starch, and boiled to form a mass which, -when exposed to the air becomes dry. It is sometimes effected at 177° -F., but it becomes a paste at 212° to 230° F. The starch changes into -dextrine in an hour or an hour and a half at the most; it is white and -soluble in water. - -_Tragacanth, or gum tragacanth_, exudes from _Astragalus verus_, a -tree indigenous to Asia. The term gum is a misnomer, as tragacanth -does not actually dissolve in water nor in spirit of wine, but merely -swells up in water to a soft gelatinous mass. Tragacanth consists of -irregular pieces of a pure white to yellowish color. It is chiefly used -for confectioner’s purposes, though sometimes as a paste for fancy -articles. This variety of gum is found, together with arabine, in the -gum which exudes from cherry, plum, almond, and apricot trees, and -gives the mucilaginous character to the watery decoctions prepared from -certain seeds, such as linseed and quince-seed, and from the root of -marshmallow. - - -PASTES AND MUCILAGES FOR SPECIAL PURPOSES. - -_Starch paste._ Corn starch 8 ozs., cold water ½ pint, boiling water 1 -gallon. - -Beat up the starch in the cold water until reduced to a creamy -consistence, then pour the mixture into the boiling water and stir -briskly until the white, semi-opaque mass, becomes transparent. Should -it fail to do so, place it over the fire, and boil until the desired -result is obtained, stirring constantly. - -_Flour paste._ Wheat flour 4 lbs., cold water 2 quarts, alum 2 ozs., -hot water ½ pint, boiling water 2 gallons. - -Work the wheat flour into a batter free from lumps with the cold -water. Dissolve the alum in the hot water. Then stir the batter into -the boiling water, and if necessary, continue boiling until the paste -thickens into a semi-transparent mucilage, after which stir in the alum -solution. This makes a very fine paste for wall-paper. - -_Strong adhesive paste._ Rye flour 2 lbs., cold water 1 quart, boiling -water 3 quarts, pulverized rosin 1 oz. - -Make the flour into a batter with the cold water, free from lumps, and -pour into the boiling water. Boil, if necessary, and while hot stir in -the pulverized rosin, a little at a time. This paste is very strong, -and will fasten heavy wall-paper or thin leather. If too thick, thin -with hot water. Never thin paste with cold water. - -_Paste that will not sour._ Allow 4 parts by weight of glue to soften -in 15 parts of cold water for some hours, and then heat moderately -till the solution becomes quite clear; then add, while stirring, 65 -parts of boiling water. In another vessel stir up 30 parts of starch -paste with 20 parts of cold water, so that a thin, milky fluid without -lumps is obtained. Into this pour the boiling glue solution, stirring -constantly, and keep the whole at the boiling temperature. After -cooling, add 5 to 10 drops of carbolic acid to the paste. Preserve the -paste in closed bottles to prevent evaporation of the water. It will -thus keep good for years. - -_Venetian paste._ White or fish glue 4 ozs., cold water ½ pint, Venice -turpentine 2 fluid ozs., rye flour 1 lb., cold water 1 pint, boiling -water 2 quarts. - -Soak the 4 ozs. of glue in the cold water for 4 hours. Dissolve over -a water-bath, and while hot stir in the Venice turpentine. Make up -the rye flour into a batter free from lumps with the pint of water, -and pour the latter into the boiling water. Stir briskly, and finally -add the glue solution. This makes a very strong paste, and it will -adhere to a painted surface, owing to the Venice turpentine in its -composition. - -_Label paste._ A good paste for attaching labels to bottles may be made -by soaking glue in strong vinegar, then heat to boiling and add flour. -This is very adhesive, and will not decompose when kept in wide-mouthed -bottles. - -_Elastic or pliable paste._ Starch 4 ozs., white dextrine 2 ozs., cold -water 10 fluid ozs., borax 1 oz., glycerine 3 fluid ozs., boiling water -2 quarts. - -Beat the starch and dextrine into paste with the cold water. Dissolve -the borax in the boiling water, then add the glycerine, and pour -the starch and dextrine mixture into the borax solution. Stir until -it becomes translucent. This paste will not crack, and, being very -pliable, is suitable for paper, cloth, leather and other material where -flexibility is required. - -_Mucilage for labels._ Macerate 5 parts of good glue in 20 parts of -water for 24 hours, and to the liquid add 9 parts of rock candy, and -3 parts of gum arabic. The mixture may be brushed upon paper while -lukewarm. It keeps well, does not stick together and adheres firmly to -bottles. - -_Mucilage._ A strong aqueous solution of dextrine forms a most adhesive -and cheap mucilage. Dilute alcohol is usually employed as the solvent -where the mucilage is to be used for gumming envelopes, postage stamps, -etc., and in order to facilitate the drying, acetic acid is added to -increase the mobility of the fluid. The strong aqueous solution is -more adhesive than that prepared with alcohol, for the reason that it -contains a greater proportion of dextrine. - -To prepare this add an excess of dextrine to boiling water, stir for -a minute or two, allow to cool and settle, and strain the liquid -through a cloth. The addition of a little powdered sugar increases the -glossiness of the dried gum. The sugar should be dissolved in the water -before the dextrine is added. - -_According to another formula_, dextrine is mixed with hot water until -a syrupy liquid is obtained. Then add a few drops of oil of cloves, and -cool for use. - -_Another formula is as follows_: Dextrine 120 parts, powdered alum 6, -sugar 30, carbolic acid 1, water 300. Mix gradually the dextrine, alum -and sugar with the water, boil to effect solution, and when cold, add -the carbolic acid. - -The solubility of dextrine may be enhanced by the addition of a calcium -salt readily soluble in water, the resulting mixture dissolving with -ease in cold water. Calcium nitrate has proved especially suitable for -the purpose. By pouring 1 quart of water over a mixture of 18 ozs. of -dextrine and 7 ozs. of calcium nitrate, a mass of great adhesive power -is immediately obtained. - -_Mucilage for postage stamps._ Dextrine 2 parts, acetic acid 1, water -5, alcohol 1. Mix all together. - -_Caseine mucilage._ Take the curd of skim milk, wash it thoroughly, and -dissolve it to saturation in a cold concentrated solution of borax. - -_Tragacanth mucilage._ Powdered tragacanth 2 drachms, glycerine 12 -drachms, water enough to make 20 ozs. - -Put the tragacanth in a mortar with the glycerine, and then add the -water. This will produce at once a mucilage of excellent quality. - -_Adhesive paste._ Steep 4 ozs. of ordinary gelatine in 16 ozs. of water -until it becomes soft, then dissolve it by the heat of a water bath, -and while still hot pour into a mixture of 2 lbs. of good flour paste -and 1 part of water. Heat the whole to boiling and when thickened -remove from the fire. While cooling add 6 drachms of silicate of soda -and stir the mixture with a wooden spatula. This preparation will keep -good for an indefinite period, and is very adhesive. The addition of 2 -drachms of oil of cloves is an improvement. - -_Fluid pastes._ I. Gum arabic 10 lbs., sugar 2 lbs., nitric acid 1¾ -ozs., water as required. - -Dissolve the gum and sugar in the water, then add the acid and heat to -the boiling-point. The resulting paste is liquid, does not mould, and -dries to a transparent layer upon paper. It is especially suitable for -flaps of envelopes, fine bookbinders’ work, etc. - -II. Potato starch 10 lbs., water 5 quarts, nitric acid 8 ozs. - -Mix the acid and water and pour it on the starch in an earthenware -basin, put the latter in a warm place, and allow it to remain 24 hours, -with occasional stirring. Then boil it until it becomes thickly-fluid -and very transparent. If necessary it should be diluted with water and -filtered through a cloth. - -_Sugar and lime paste._ Dissolve 12 parts of white sugar in 36 of -water. Heat the solution to the boiling-point and add 3 parts of slaked -lime. Allow the liquid to stand in a covered vessel for several days, -stirring frequently and, when settled, pour off the supernatant thick -fluid from the excess of lime. - -The paste thus obtained has all the properties of gum arabic solution -and dries to a lustrous mass. - -_Liquid sugar and lime paste._ Allow 3 parts of glue to swell in 10 to -15 parts of the foregoing paste. Heat the mixture to the boiling-point. -The paste thus obtained does not congeal on cooling and possesses -considerable adhesive power. - -By reason of its caustic properties, due to the content of lime, this -paste should not be used for pasting colored materials. - -_Pastes for paper and fine fancy articles._ I. Dissolve, with the -assistance of heat, 100 parts of gilder’s glue in 200 of water, and add -a solution of 2 parts of bleached shellac in 10 of alcohol. - -II. Dissolve, with the assistance of heat, 50 parts of dextrine in 50 -of water, stir solutions 1 and 2 together, strain through a cloth into -a flat prismatic mould, and allow it to congeal. For use, melt a piece -of corresponding size, and dilute the liquid, if necessary, with water. - -_Albumen paste._ This is a misnomer, as it contains no albumen. It is -partly decayed gluten from flour, washed with water and then heated to -60° or 68° F., when it ferments and becomes partly fluid. It is then -dried at 77° to 86° F., and is claimed to keep any length of time in a -dry place. Dissolved in twice its weight of water it can be used as a -paste for all purposes. - -_Glycerine paste._ Dissolve 2 ozs. of gum arabic and 4 drachms of -glycerine in 6 ozs. of boiling water. This is a good paste for office -use. - -_Paste for fixing labels on machines._ Make a paste of rye flour and -glue and add to every pound thereof ½ oz. each of boiled linseed oil -and turpentine. This paste resists damp and thus prevents printed -labels from falling off metallic surfaces. - -_Paste for mounting maps._ Stiff rye flour paste is best for this -purpose. - -_Paste for fastening paper on tin-foil._ Make a paste by dissolving rye -flour in solution of caustic soda; dilute with water, stirring all the -time. Add to this paste a few drops of Venice turpentine for each ½ lb. -of flour. - -_Paste for paper bags._ Add to 3 parts of starch 24 to 30 parts of cold -water. Stir together to a homogeneous mass of about the thickness of -syrup. Pour over this, stirring constantly, boiling water until the -paste is of the required consistency. Stir until nearly cold. Take a -portion of the paste and add to it 6 to 15 per cent. liquefied Venice -turpentine; rub together until a kind of emulsion is formed, then mix -the whole together and work thoroughly. - -_Caseine mucilage for photographer’s use._ Separate the caseine from -milk by means of a little tartaric acid, and treat the caseine while -still warm with a solution of 6 parts of borax to 100 parts water, -and warm gently while stirring which will cause the caseine to be -dissolved. Of the borax solution enough should be used to leave only a -little undissolved caseine behind. - -_Paste for scrap-books._ Rice starch 1 oz., gelatine 3 drachms, water ½ -pint. - -Heat, stirring constantly, until the milky fluid becomes thick and -gluey. When the paste is nearly thick put in a bottle closely corked. -It is well to add a few drops of oil of cloves to each bottle. - -_Paste for skins._ Pour enough boiling water over 1 lb. of rye flour in -a basin to make a stiff paste, almost as stiff as ordinary dough for -puddings. Stir and beat up well with a stick for three or four minutes, -then cover up and let it stand for two days before using, when it will -be much softer and stick better. Spread thinly and evenly on the back -of the skin with a stiff brush or pad. It will stick firmly and not -crack. - -_Strong mucilage_ capable of fastening wood or china and glass together -is made of 3½ ozs. of strong gum arabic solution, to which a solution -of 30 grains of sulphate of aluminium dissolved in ⅔ oz. of water is -added. - -_Dextrine mucilage._ I. Dissolve with the assistance of heat 60 parts -of borax in 420 parts of water, add 480 parts of pale yellow dextrine -and 50 parts of glucose, and heat carefully, stirring constantly until -solution is complete, replacing the water lost by evaporation. Strain -through flannel. - -The resulting mucilage is quite clear, has great adhesive power, and -dries very quickly. In heating the mixture, great care should be -exercised not to exceed a temperature of 194° F. and not to heat too -long, otherwise the product readily becomes brown and brittle. - -II. Dextrine 120 parts, powdered alum 6, sugar 30, carbolic acid 1, -distilled water 300. Gradually mix the dextrine, alum and sugar with -the water, effect solution by boiling and when the solution is cold, -add the carbolic acid. - -_Paste for joining leather to pasteboard._ Dissolve 50 parts of strong -glue with a little water at a gentle heat, then add a small quantity of -Venice turpentine, and next a thick paste made with 100 parts of starch -in water. Apply quickly when cold. - -_Another formula_ for a similar paste is as follows: Rye whisky 2 -pints, water 1 pint, powdered starch 4¼ ozs., good glue 1¼ ozs., Venice -turpentine 1¼ ozs. Mix the whisky and water together, then stir in the -starch and make a thick paste. Separately dissolve the glue in an equal -weight of water, and mix the Venice turpentine therein, mix thoroughly, -and then compound this mixture with the thick paste by constantly -stirring until all is well incorporated. - -_Paste for attaching labels to polished nickel._ Dissolve 400 parts by -weight of dextrine in 600 parts of water, and add 20 parts of glycerine -and 10 parts of glucose. Heat the mixture to 194° F. - -_Another formula_ is as follows: Mix 400 parts by weight of dextrine -with water, and add 200 parts of water together with 20 parts of -glucose and 10 parts of aluminium sulphate. - -_Mucilage for attaching labels to tin._ I. Shellac 8 parts, borax 4 -parts, water 60 parts. Boil until the shellac is dissolved. - -II. To 2 parts of dammar varnish add 8 parts of tragacanth mucilage. - -III. An excellent mucilage for the purpose consists of starch paste to -which a small quantity of Venice turpentine has been added. - -IV. Make a paste of corrosive sublimate 2½ parts, wheat flour 200, -absinthe 100, tansy 50, water 3000. This mucilage is useful for vessels -kept in a damp place. - -_Mucilage for office use._ Gum arabic 100 parts, aluminium sulphate -6 parts, glycerine 10, dilute acetic acid 20, distilled water 140. -Dissolve, in a wide-mouthed glass bottle, the gum arabic in cold -distilled water, stirring frequently. Let the solution stand 2 or 3 -days, then add the glycerine, later on the dilute acetic acid and -finally the aluminium sulphate. Strain through a hair sieve, allow to -clarify, and decant from the sediment. - -_Glycerine paste for office use._ Dissolve 4 ozs. of gum arabic and 8 -drachms of glycerine in 12 ozs. of boiling water. - -_Clean and durable paste._ Dissolve 5 ozs. of gum arabic in 4 quarts -of warm water, and thicken to a paste with wheat flour. Then add a -solution of alum and sugar of lead, 3 ozs. of each in water. Heat the -mixture and stir it until it is about to boil, and then cool it. If too -thick, add gum solution. - -_Banknote or mouth glue._ Dissolve by the aid of heat a fine quality -of glue or gelatine with about a quarter or one-third of its weight of -brown sugar, in as small a quantity of water as possible. Then when -perfectly liquid cast the mixture into thin cakes on a flat surface -very slightly oiled, and when cold cut up into pieces of convenient -size. When required for use moisten one end. A piece of this glue kept -in the desk will be found very convenient for many purposes. - -_Paste for cardboard._ Dissolve 3½ ozs. of best French glue in 6½ ozs. -of water by soaking and heating. Then add a solution of ½ drachm of -shellac in 3½ drachms of alcohol and stir as long as the solution is -warm. Next dissolve 2 drachms of dextrine in 1¾ ozs. of alcohol and -14 drachms of water, stir, and place the vessel in warm water until -solution is complete. Mix this solution with that of the glue, and pour -the whole into a suitable vessel, in which it may solidify. When wanted -for use cut off a small piece and liquefy it by warming. - -_Paste for attaching cloth or leather to table tops._ Wheat flour 1 -lb., powdered rosin 2 tablespoonfuls, powdered alum 1 tablespoonful. -Heat and stir to a stiff consistency. - -_Caseine mucilage._ Separate the caseine from milk with a little -tartaric acid, and treat the caseine while still warm with a solution -of 6 parts borax to 100 parts water and warm gently while stirring, -which will cause the caseine to be dissolved. Of the borax solution -enough should be used to leave only a little undissolved caseine behind. - -_Very adhesive paste which may be used for wood and parchment._ Gum -arabic 60 parts, fine wheat starch 45, sugar 15. Dissolve the gum in -as much water as is required for boiling the quantity of paste to be -made. Then add the starch and sugar and boil it in a vessel suspended -in boiling water until the mixture is clear and has the consistency of -liquid tar. Keep in a well-closed vessel protected from mould by the -addition of a few drops of oil of cloves. - -_Paste for pads._ Glue 4 parts by weight, glycerine 2, linseed oil ½, -sugar 4, aniline dye sufficient to color. Soften the glue by soaking in -cold water, then dissolve together with the sugar in the glycerine by -the aid of heat over the water-bath, then add the dye and stir in the -oil. Use the paste hot. - -_Paste for fastening paper on tin-foil._ Make a paste by dissolving -rye flour in a solution of caustic soda; dilute with water, stirring -constantly. Add to this paste a few drops of Venice turpentine for each -½ lb. flour used. This paste adheres to all kinds of metal, tin-foil, -glass, etc. - -_Paste for attaching labels to glass, porcelain, and metal._ Gum -arabic 15 parts, pulverized tragacanth 7½, glycerin 45, thymol 0.3, -alcohol 3¾, water 120. Dissolve the gum arabic in 15 parts of water and -triturate the tragacanth with 30 parts of water. Mix the two fluids and -strain. Then add the glycerine and finally the thymol dissolved in the -alcohol. - -_Preparation of arabol-gum._ Mix intimately 44 lbs. of wheat starch -with 176 lbs. of water. Bring the mass into a water-bath, mix it with -a solution of 4.4 lbs. of oxalic acid in 44 lbs. of water and heat -for four hours at 194° F., stirring frequently. The conversion of the -starch is as a rule effected during this time, but should such not be -the case, continue heating, constantly replacing the evaporated water, -until the mass is clear and liquid. While still hot, neutralize the -mass with marble dust, allow to settle, filter, and evaporate the clear -solution in a water-bath to a solid gum containing about 15 per cent. -of water. - -_Preparation of an adhesive substance from desaccharized beet-root -slices_ (German patent 96316 f. G. Eichelbaum). The insoluble -metarabin contained in the slices is converted into soluble arabin by -treating the slices under pressure with hot aqueous sulphurous acid or -with aqueous solutions of the bisulphites of the alkalies or alkaline -earths. - -According to a later patent (German patent 121422 f. Fabrik -Bettenhausen Marquart and Schulz), the insoluble metarabin is converted -into soluble arabin by heating the desaccharized beet-root slices with -phosphoric acid and water. According to a supplement to this patent -(122048), conversion is effected by heating the slices with aqueous -solutions of organic acids and phenols, or the acid salts of oxalic, -tartaric or phosphoric acids. - - - - -INDEX. - - - Acid calcium phosphate, 120 - - —— —— —— crystallization of, 125, 126 - - —— —— —— formation of, 121-124 - - —— sodium sulphate, use of, in drying glue, 72, 73 - - Acidity, determination of, in glue, 205, 206 - - Acids, dilute, effect of, on glue solution, 7 - - Adamson, Wm., method of, for removing hydrocarbons from substances - which have been treated therewith, 84-86 - - —— —— method of, for treating substances with hydro carbon vapor for - the purpose of extracting oils, fats, etc., 79-82 - - —— —— method of, for treating substances with liquid hydrocarbons for - the purpose of extracting oils, fats, etc., 82-84 - - —— —— and Simonis, Chas. F. A., apparatus of, for extracting bones - with benzine, 76-79 - - Adhesive paste, 264 - - Adulterations of glue, determination of, 214, 215 - - Agar-Agar, 12, 201, 202 - - Air-bladders, 16, 41 - - —— bleaching glue in the, 141 - - —— drying the cakes of glue in the, 64 - - Alabaster, 244 - - —— cement for, 242 - - Albumen paste, 265, 266 - - —— —— use of, for clarifying glue liquor, 54 - - Alum cement, 228 - - —— —— effect of, on glue solution, 7 - - —— —— use of, for clarifying glue liquor, 54 - - —— —— —— —— preserving paste, 257 - - Amber, resinous cement for, 229 - - American cement for jewelers, 252 - - American glue, analysis of, 207 - - Ammonium sulphate, use of, in drying glue, 72, 73 - - Animal charcoal, bleaching glue with, 142 - - —— —— bones for the manufacture of, 107 - - —— —— carbonization of bones for, 108-112 - - —— —— decolorizing glue liquor with, 55 - - —— —— manufacture of, 112, 113 - - —— —— yield of, 113 - - —— skin, constitution of, 17, 18 - - Antiseptics for the preservation of glue-stock, 30 - - Arabin, conversion of metarabin into, 271 - - Arabol-gum, preparation of, 270 - - Ash, burning bones to, 117-119 - - - Bacteriology, use of gelatine in, 194 - - Banknote glue, 269 - - Barium chloride, effect of, on glue solution, 7 - - Basic calcium phosphate, 120 - - Beet-root slices, desaccharized, preparation of an adhesive - substance from, 270, 271 - - Belgian retort-furnace for the carbonization of bones, 109-112 - - Benzine, extracting fat from bones with, 76-92 - - Billiard balls, compound for, 155, 156 - - Bleaching glue, methods of, 141-145 - - —— —— stock, 55, 56 - - Blood, fresh, use of, for clarifying glue liquor, 54 - - Blumenthal’s method of preparing dextrine, 260, 261 - - Boiler for glue boiling, 44 - - Boiling bones, 74, 75 - - —— —— duration of, 45 - - —— —— or cooking glue, 44-52 - - Bone ash, composition of, 119 - - —— —— conversion of, into a coarse powder, 119 - - —— —— decomposition of, by sulphuric acid, 119-125 - - —— —— kiln for, 117-119 - - —— —— preparation of, 117-119 - - —— —— yield of, 119 - - —— cartilage, composition of, 32 - - —— cement for, 230 - - —— crusher, 36 - - —— gelatine, 170-180 - - —— —— modern process of preparing, 179, 180 - - —— -glue, manufacture of, 74-116 - - —— meal, glue and fat, simultaneous utilization of bones for, 104-113 - - —— -mill, Crosskill, 36 - - —— raw materials, 16 - - —— size, 159, 160 - - Bones, absorption of sulphurous acid by, 92 - - —— Adamson and Simonis’ apparatus for extracting, 76-79 - - —— and cartilages, 31-39 - - —— apparatus for extracting the fat from, with benzine, 76-94 - - —— Belgian retort-furnace for the carbonization of, 109-112 - - —— boiling of, 74, 75 - - —— burning of, to ash, 117-119 - - —— buying of, 32 - - —— carbonization of, 108-112 - - —— constitution of, 32 - - —— crushed, sorting of, 36, 37 - - —— crushing or grinding of, 33-36 - - —— extraction of, 76-94 - - —— —— —— phosphates from, 115 - - —— fatty matters in, 32 - - —— for the manufacture of animal charcoal, 107 - - —— honey-combed, 39 - - —— Leuner’s apparatus for extracting, 90-92 - - —— lime bath for, 37 - - —— products obtained in the distillation of, 112 - - —— Seltsam’s apparatus for extracting, 84-86 - - —— —— apparatus for extracting, improved by Th. Richter, 88-90 - - —— simultaneous utilization of, for fat, bone-meal and glue, 104-113 - - —— —— utilization of, for fat, glue and calcium phosphate, 113-116 - - —— sorting of, 32, 33, 104, 105 - - —— sulphurous acid for extracting, 92-94 - - —— treatment of, with high pressure steam, 105-107 - - —— utilization of the liquor obtained in the treatment of, with - hydrochloric acid, 125-127 - - —— value of, 32 - - —— waste of, from the preparation of tinned provisions, 19 - - Bookbinder’s glue, 12 - - —— size, 160 - - Book isinglass, 197 - - Boric acid, preservation of glue-stock with, 30 - - Bottles, cracked, cement for, 240, 241 - - Bouillon tablets, 12 - - Brazilian isinglass, 199, 200 - - Briers, D. J., process for the preparation of bone gelatine - employed by, 171-179 - - Brochette, 43 - - Brushmaker’s cement, 251 - - Bullock’s feet, 18 - - —— hide, waste of, 18 - - —— leather, 30 - - Burning bones to ash, 117-119 - - - Cakes, cutting glue into, 57-64 - - —— drying the, 64-73 - - —— machines for cutting the jelly into, 60-64 - - —— shape of, 57, 58 - - —— tools for cutting the jelly into, 59 - - Calcium chloride, 116 - - —— metaphosphate, 120, 127 - - —— phosphate, 115 - - —— —— fat and glue, simultaneous utilization of bones for, 113-116 - - Calf leather, 30 - - —— skin waste, 18 - - Calves’ feet, 30 - - —— heads, 18, 30 - - Carbolic acid, preservation of glue-stock with, 29 - - —— —— use of, for preserving paste, 257, 258 - - Carbon disulphide, use of, for extracting bones, 76 - - Cardboard, paste for, 269 - - Cartilage, 1 - - —— conversion of, into glue, 94-104 - - —— drying of, 114 - - —— preservation of, 114 - - —— treatment of, with high-pressure steam, 98 - - —— yield of glue from, 115 - - Cartilages and bones, 31-39 - - Caseine cement which can be kept for a long time, 239 - - —— cements, 237-240 - - —— mucilage, 264 - - —— —— for photographer’s use, 266 - - —— ordinary technical, preparation of, 238, 239 - - —— pure, preparation of, 237, 238 - - Castings, cement for filling in defects in, 246 - - Cattle, pieces of hide from the lower parts of the limbs of, 30 - - Cayenne isinglass, 199, 200 - - Cellular tissue, 1 - - Celluloid, cement for, 252 - - Cement resisting acids, 248 - - —— —— —— very high temperatures, 248 - - Cements, caseine, 237-240 - - —— chemical nature of, 219 - - —— classification of, 218-223 - - —— for chemical apparatus, 247-249 - - —— —— —— —— special purposes, 249-252 - - —— glue and starch, 222, 223 - - —— glycerine, 242 - - —— gypsum, 244, 245 - - —— how to use, 252-255 - - —— iron, 245-247 - - —— lime, 223, 243, 244 - - —— oil, 219, 220, 224-229 - - —— pastes and mucilages, preparation of, 224-271 - - —— resinous, 220, 221, 229-233 - - —— resisting high temperatures, 246 - - —— rubber and gutta-percha, 222, 233-237 - - —— water glass, 240-242 - - Chalk, 243 - - Charcoal, animal, bleaching glue with, 142 - - —— —— bones for the manufacture of, 107 - - —— —— carbonization of bones for, 108-112 - - —— —— manufacture of, 112, 113 - - —— —— yield of, 113 - - —— mixing calcium phosphate with, 124 - - Chemical apparatus, cements for, 247-249 - - Chinese isinglass, 201, 202 - - Chlorbarium, soaking hides in, 20 - - Chloride of lime, bleaching glue-stock with, 55 - - Chlorine, bleaching glue with, 141 - - Chondrin, chemical composition of, 5, 6 - - —— conversion of, into glutin, 6 - - —— formation of, 3 - - —— properties of, 5 - - —— pure, preparation of, 5 - - Chrome glue, 153 - - Clarifying glue liquor, 52-56 - - —— —— —— apparatus for, 98 - - —— —— —— vats, 53 - - Clay crucibles, cracked, cement for, 243 - - Clearness of glue, definition of, 53 - - Clock faces, white enameled, cement for, 230 - - Cloth, cement for, 252 - - —— paste for attaching, to table tops, 269 - - Colle franche, 43 - - Cologne glue, 148 - - Color mixtures, glue for, 11 - - —— of glue, definition of, 53 - - Colored gelatine, 181, 182 - - Coloring glue, 156 - - —— matters for gelatine, 181, 182 - - —— substances, removal of, from glue liquor, 54-56 - - Combs, hard rubber, cement for, 236 - - Common salt, effect of, on glue solution, 7 - - Constitution of glue, 3-6 - - Conversion of cartilage into glue, 94-104 - - Cooking, duration of, 44 - - —— or boiling glue, 44-52 - - Cooling boxes, 100 - - —— glue liquor, 100 - - Corium, 1, 17 - - Court-plaster, 12, 184, 185 - - Cox, J. and G., process for the manufacture of gelatine patented - by, 166, 167 - - Crockery, cement for, 236, 237 - - Crosskill bone mill, 36 - - Crucibles, cement for, 243 - - Crude glue, definition of, 3 - - —— —— preparation of, 43 - - Culinary purposes, glue for, 12-14 - - - Dark steam glue, 152 - - Devoulx, cutting apparatus invented by, 62-64 - - Dextrine mucilage, 267 - - —— —— preparation of, 259-261 - - Diamond cement, 229 - - Distillation of crude phosphorus, 133-135 - - —— —— phosphorus, 127-132 - - Drying, acceleration of, 72, 73 - - —— cakes of glue, 64-73 - - —— galleries, 68-71 - - —— house, modern, 71, 72 - - Drying room, 65 - - —— —— regulating the temperature of the, 67, 68 - - - East India isinglass, 199 - - Elastic cement, 234 - - —— gutta-percha cement, 236 - - —— masses, glue for, 14 - - —— paste, 263 - - Electric furnace for the manufacture of phosphorus, 138-140 - - Electrical apparatus, cement for, 251, 252 - - Emery paper, use of glue in the manufacture of, 12 - - Epidermis, 17 - - Epsom salt, behavior of glue solution towards, 7 - - —— —— use of, in drying glue, 72, 73 - - Evaporating pan, open, 98-100 - - —— pans, 124 - - Evaporators, spiral, 100, 101 - - Extraction of bones, 76-94 - - - Fabrics, water-proofing of, 161-163 - - Fancy articles, fine, paste for, 265 - - Fans, gelatine veneers for, 15 - - Fat, bone meal and glue, simultaneous utilization of bones - for, 104-113 - - —— extraction of, with benzine, 76-92 - - —— —— —— hydrocarbon vapors, 79-82 - - —— —— —— liquid hydrocarbons, 82-84 - - —— glue and calcium phosphate, simultaneous utilization of - bones for, 113-116 - - Fertilizers, utilization of liquors for, 116 - - Fining, gelatine for, 182 - - Fish bladders, 1 - - —— —— glue, 202-204 - - —— —— —— points to be observed in the manufacture of, 41, 42 - - —— —— —— raw materials for, 41, 42 - - —— scales, 16, 42 - - —— —— preparation of glue from, 203 - - Fleck’s kiln for burning bones, 118, 119 - - —— process of accelerating the drying of glue, 72, 73 - - Flour paste, 256-258, 261, 262 - - Fluid pastes, 264, 265 - - Foils, gelatine, 15, 185, 186 - - Formaldehyde, preservation of glue-stock with, 29, 30 - - Forming or moulding the glue, 56-64 - - Formo-gelatine, 193, 194 - - French mastic, 227 - - —— putty, 225 - - Friedberg’s apparatus for clarifying glue liquor, 98 - - —- —— —— conversion of cartilage into glue, 94-97 - - Furnace, electric, for the manufacture of phosphorus, 138-140 - - - Galley furnace, 128, 129 - - Galvanized iron-wire netting, 66 - - Gelatin, pure, preparation of, 4 - - Gelatine and glycerine, compound of, 12 - - —— and products prepared from it, manufacture of, 165-195 - - —— artificial silk from, 195 - - —— capsules, 14, 184 - - —— colored, 181, 182 - - —— constitution of, 165 - - —— Cox’s process for the manufacture of, 166, 167 - - —— foils, 15, 185, 186 - - —— for fining purposes, 182 - - —— for photographic printing and photographic purposes in - general, 183, 184 - - —— Jullion and Pirie’s process for the preparation of, 38 - - —— Nelson’s process for the manufacture of, 166 - - —— preparation of, from ordinary glue, 182, 183 - - —— substitute for, 203, 204 - - —— Swinborne’s improved patented process for the preparation of, 167 - - —— testing of, 205-217 - - —— veneers, 15, 186-193 - - —— yielding tissues, 1 - - German isinglass, 200 - - Gilder’s glue, 150 - - Glass, cement for, 230, 233, 239, 241, 243, 245 - - —— —— for attaching metal letters to, 249 - - —— —— —— —— —— to metal, 251 - - —— mastic cement for, 232 - - —— oil cement for, 228 - - —— paper, use of glue in the manufacture of, 12 - - —— paste for attaching labels to, 270 - - —— plates, gelatinizing liquors upon, 58, 59 - - —— upon glass, cement for, 230 - - —— —— metal, cement for, 230 - - Glauber’s salt, use of, in drying glue, 72, 73 - - Gloves, waste from the manufacture of, 43 - - Glue, acceleration of the drying of, 72, 73 - - —— addition of mineral substances to, 149 - - —— American, analysis of, 207 - - —— and starch cements, 222, 223 - - —— as a binding agent, 11 - - —— —— —— joining medium, 10, 11 - - —— banknote or mouth, 269 - - —— boiler, Terne’s, 51, 52 - - —— boiling, boiler for, 44 - - —— —— convenient apparatus for, 46, 47 - - —— —— in open jacketed pans, 49, 50 - - —— —— or cooking, 44-52 - - —— —— with steam, boiler for, 47-49 - - —— chemical composition of, 8 - - —— chrome, 153 - - —— clearness of, 53 - - —— Cologne, 148 - - —— color of, 53 - - —— coloring of, 156 - - —— constitution of, 3-6 - - —— conversion of cartilage into, 94-104 - - —— cooking, process of, 51 - - —— crude, definition of, 3 - - —— —— preparation of, 43 - - —— cutting the, into cakes, 57-64 - - —— deduction of the quality of, from indirect properties, 207, 208 - - —— determination of acidity in, 205, 206 - - —— —— of adulterations of, 214, 215 - - —— —— of glutin in, 206, 207 - - —— —— of moisture in, 205 - - —— different varieties of, and their preparation, 146-164 - - —— drying cakes of, 64-73 - - —— —— room for, 65 - - —— factory, location of a, 21 - - —— —— manner of carrying on the work in a, 26-30 - - —— fat and bone-meal, simultaneous utilization of bones for, 104-113 - - —— for attaching leather to metal, 153 - - —— —— culinary and medicinal purposes, 12-14 - - —— —— elastic masses and as a partial substitute for rubber, 14 - - —— —— fancy articles, 14, 15 - - Glue joints in leather driving belts, 163 - - —— —— —— leather, paper, etc., 153, 154 - - —— —— —— parchment paper in making sausage skins, 154, 155 - - —— formation of, 6 - - —— from various materials, external characteristics of, 6, 7 - - —— gilder’s, 150 - - —— holding power of, 147, 148 - - —— how to make and use, 147 - - —— in animal organism, 2 - - —— —— sizing, 12 - - —— inferior qualities of, 12 - - —— joiner’s, 146 - - —— Kissling’s results in testing, 215 - - —— liquid, 151, 152 - - —— liquor, apparatus for clarifying, 98 - - —— —— clarifying the, 52-56 - - —— —— concentration of, 50 - - —— —— cooling of, 100 - - —— —— decolorizing of, with animal charcoal, 55 - - —— —— instrument for measuring the percentage of glue in, 103 - - —— measuring the percentage of, in glue liquor, 103, 104 - - —— methods of bleaching, 141-145 - - —— moulding or forming of, 56-64 - - —— nature of, 1-9 - - —— nets for drying, 66, 67 - - —— ordinary, preparation of gelatine from, 182, 183 - - —— parchment, 150 - - —— Paris, 150, 151 - - —— patent, 150 - - —— practical testing of, 215-217 - - —— principal substances employed as raw material for, 16 - - —— properties of, and its behavior towards other substances, 6-9 - - —— raw materials and their preparation for the manufacture of, 16-38 - - —— results obtained by comparative experiments in testing, 209, 210 - - —— Russian, 149, 150 - - —— size, 150 - - —— solution, behavior of, towards salts, 7, 8 - - —— steam, 152 - - —— stock, bleaching of, 55, 56 - - —— —— dry-limed, 19 - - —— —— dry, uncured, or salted, 19 - - —— —— green-limed, 19 - - —— —— green-salted, 19 - - —— —— influence of the age of animals on the product from, 20 - - —— —— limed, washing of, 21-26 - - —— —— notes in reference to judging, 19, 20 - - —— —— preparation of, 21-38 - - —— —— preservation of, 29 - - —— —— sheds for, 26 - - —— —— transformation in boiling the, 2 - - —— —— washer, 22-26 - - —— substitute for, 203, 204 - - —— transition stages of, 2 - - —— uses of, 10-15 - - —— testing of, 205-217 - - —— tungstic, 155 - - —— water-proof, 160 - - —— yield of, from cartilage, 115 - - —— —— —— from tannery waste, 18 - - —— -yielding substance, production of, 2 - - —— —— tissues, 1 - - Glutin, conversion of chondrin into, 6 - - —— determination of, in glue, 206, 207 - - —— formation of, 3 - - —— properties of, 4, 5 - - —— pure, preparation of, 4 - - Glycerine and glycerine cements, 242 - - —— —— litharge cement, 242 - - —— paste, 266 - - —— —— for office use, 268 - - —— properties of, 242 - - Glycocoll, 6 - - Goat leather, 31 - - Gray lime, 28 - - Green waste, liming of, 26, 27 - - Gum tragacanth, 261 - - Gutta-percha and rubber cements, 222, 233-237 - - Gypsum, 244 - - Gypsum cements, 244, 245 - - - Hager’s diamond cement, 229 - - Hard rubber cement, 234 - - —— combs, cement for, 236 - - Hare skins, 18, 31 - - Hartshorn, 1 - - Hayes, S. Dana, analysis of American glue by, 207 - - Heat-resisting cement, 245 - - Hectograph mass, 14, 163, 164 - - Heuzé’s method of preparing dextrine, 261 - - Hide, transformation in drying the, 2 - - Hides for glue-stock, classification of, 30, 31 - - —— soaking of, in chlorbarium, 20 - - Hoeveller, W. A., apparatus for drying glue invented by, 68-71 - - —— glue-stock washer of, 22-26 - - Hog skins, 18 - - Hollander, 39 - - Horn, cement for, 232 - - —— piths, 19 - - Horses’ hoofs, cement for, 236 - - Hudson Bay isinglass, 199 - - Hydraulic works, cement for, 241 - - Hydrocarbon vapors, extraction of fats, oils, etc., with, 79-82 - - Hydrocarbons, liquid, extraction of fats, oils, etc., with, 82-84 - - —— removal of, from substances, 84-86 - - Hydrochloric acid, treatment of bones with, 37 - - —— —— utilization of the liquor obtained in treating bones - with, 125-127 - - - Ichthyocolle Française, 200, 201 - - Irish moss, 202 - - Iron and stone, cement for, 245 - - —— cement for, 245, 246 - - —— cements, 245-247 - - —— pipes, fire-proof cement for, 246 - - —— pots, cracked, cement for, 246 - - —— water tanks, cement for, 246 - - Isinglass, adulteration of, 196, 197 - - —— and its substitutes, 196-204 - - —— chemical composition of, 8 - - —— preparation of, in Russia, 197, 198 - - —— sources of, 196 - - —— spurious, 196 - - —— substitute for, 203, 204 - - Isinglassine, 201 - - Ivory, cement for, 230 - - - Jeffrey’s marine glue, 235 - - Jelly, definition of, 3 - - —— effect of tannin on, 8 - - —— machines for cutting the, into cakes, 60-64 - - —— properties of, 7 - - —— tools for cutting the, into cakes, 59 - - —— transformation in boiling the, 2 - - Jennings’ method for the preparation of fish glue, 202, 203 - - Jewelers, American cement for, 252 - - —— cement, 252 - - Joiners, cement for, 243 - - —— glue, 146 - - Jullion and Pirie’s process for the preparation of gelatine, 38 - - Kid leather, waste from paring, 31 - - Kiln for burning bones, 117-119 - - Kissling’s results in testing glue, 215 - - Knapsack leather, 31 - - Knife handles, cement for, 231 - - - Label paste, 263 - - Labels, mucilage for, 263 - - —— paste for attaching, to glass, porcelain and metal, 270 - - —— —— for attaching, to polished nickel, 268 - - —— —— for attaching, to tin, 268 - - Lamb leather, 31 - - Leaf isinglass, 197 - - Leather, cement for, 235, 237 - - —— driving belts, glue for joints in, 163 - - —— for glue-stock, classification of, 30, 31 - - —— glue for, 153, 154 - - —— —— —— attaching, to metal, 153 - - —— paste for attaching, to table tops, 269 - - —— —— —— joining, to pasteboard, 267, 268 - - —— skins, actual, 17 - - —— waste, 39-42 - - —— —— comminution of, 39, 40 - - Leucine, 6 - - Leuner’s apparatus for extracting bones, 90-92 - - Lime and glue cement, 244 - - —— —— sugar paste, 265 - - —— bath for bones, 37 - - —— cements, 223, 243, 244 - - —— milk of, preparation of, 26, 27 - - —— precipitation of, by oxalic acid, 54 - - —— slaked, effect of, on glue solution, 7 - - —— testing of, 27, 28 - - Limed glue-stock, washing of, 21-26 - - Liming green waste, 26, 27 - - —— waste, 20 - - Linseed oil and clay cement, 248 - - —— —— —— manganese cement, 248 - - Lipowitz’s method of testing glue, 208, 209 - - Liquid fining gelatine, 182 - - —— glue, 151, 152 - - —— sugar and lime paste, 265 - - Litharge cement, 225 - - - Magnesium sulphate, 116 - - Manufacture of bone-glue, 74-116 - - —— —— gelatine, and products prepared from it, 165-195 - - —— —— phosphorus, 117-140 - - —— —— skin glue, 43-73 - - Maps, paste for mounting, 266 - - Marble, cement for, 242, 251 - - —— —— for attaching metal letters to, 249 - - —— oil cement for, 228, 229 - - Marine glue, 234, 235 - - Matches, use of glue in the manufacture of, 11 - - Mastic, 226, 227 - - —— cement, 226, 227 - - Medicinal purposes, glue for, 12-14 - - Meerschaum, cement for, 239 - - Meta-gelatin, 7 - - Metal, cement for attaching wood, glass, etc., to, 251 - - —— glue for attaching leather to, 153 - - —— letters upon glass, cement for, 230, 249 - - —— paste for attaching labels to, 270 - - Metals, cement for, 239 - - —— —— for uniting, 241 - - Metarabin, conversion of, into arabin, 271 - - Mica, cement for, 231, 232 - - Milk of lime, preparation of, 26, 27 - - Moisture, determination of, in glue, 205 - - Mother-of-pearl, glue imitations of, 15 - - Moulding boxes, 56 - - —— or forming the glue, 56-64 - - —— refined phosphorus, 135-137 - - Mouth glue, 269 - - Mucilage, 263, 264 - - —— caseine, 264 - - —— —— for photographers’ use, 266 - - —— dextrine, 267 - - —— for attaching labels to tin, 268 - - —— —— labels, 263 - - —— —— office use, 268 - - —— —— postage stamps, 264 - - —— preservation of, 259, 260 - - —— strong, 267 - - —— tragacanth, 264 - - Mucilages and pastes, 255-271 - - —— —— —— for special purposes, 261-271 - - —— —— pastes and cements, preparation of, 224-271 - - Muratori and Landry’s method of water-proofing fabrics, 162, 163 - - Muzmann and Krakowitzer’s method of water-proofing fabrics, 162, 163 - - - Nature of glue, 1-9 - - Nelson, G., process of, for the manufacture of gelatine, 166 - - Nets for drying glue, 66, 67 - - Netting, metallic, 66 - - —— twine, 66, 67 - - Neutral potassium tartrate, behavior of glue solution towards, 7 - - New York isinglass, 198 - - Nickel, polished, paste for attaching labels to, 268 - - North American isinglass, 198 - - - Office use, glycerine paste for, 268 - - —— —— mucilage for, 268 - - Oil cements, 219, 220, 224-229 - - Oils, extraction of, with hydrocarbon vapors, 79-82 - - —— —— —— with liquid hydrocarbons, 82-84 - - Ornaments, indestructible mass for, 155 - - Osseine, 1 - - Oxalic acid, effect of, on glue solution, 7 - - —— —— precipitation of lime by, 54 - - - Pads, paste for, 270 - - Paget’s mastic, 227 - - Pale steam glue, 152 - - Pan, open evaporating, 98-100 - - Pans, evaporating, 124 - - —— open jacketed, 49, 50 - - —— vacuum, 101-103 - - Paper bags, paste for, 266 - - —— colored, use of glue in the manufacture of, 11 - - —— glue for, 153, 154 - - —— hangings, glue in the manufacture of, 11 - - —— paste for, 265 - - —— —— —— fastening, on tin-foil, 266, 270 - - Parchment glue, 150 - - —— paper, glue for, in making sausage skins, 154, 155 - - —— scraps, 18 - - Paris glue, 150, 151 - - Paste, adhesive, 264 - - —— albumen, 265, 266 - - —— clean and durable, 268, 269 - - —— elastic or pliable, 263 - - —— fluid, 264, 265 - - —— for attaching cloth or leather to table tops, 269 - - —— —— —— labels to glass, porcelain and metal, 270 - - —— —— —— —— to polished nickel, 268 - - —— —— cardboard, 269 - - —— —— fastening paper on tin foil, 266, 270 - - —— —— joining leather to pasteboard, 267, 268 - - —— —— mounting maps, 266 - - —— —— pads, 270 - - —— —— paper and fine fancy articles, 265 - - —— —— —— bags, 266 - - —- —— scrap-books, 266, 267 - - —— —— skins, 267 - - —— glycerine, 266 - - —— —— for office use, 268 - - —— label, 263 - - —— preparation of, 255 - - —— preservatives for, 257 - - —— rules to be observed in the preparation of, 256 - - —— strong adhesive, 262 - - —— sugar and lime, 265 - - —— that will not sour, 262 - - —— Venetian, 262 - - Paste-board, paste for joining leather to, 267, 268 - - Pastes and mucilages, 255-271 - - —— —— —— for special purposes, 261-271 - - —— mucilages and cements, preparation of, 224-271 - - Patent glue, 150 - - Patriarch isinglass, 197 - - Permanent white, addition of, to glue, 149 - - Petroleum, cement to withstand the action of, 231 - - —— lamps, cement for, 231 - - Phosphates, extraction of, from bones, 115 - - Phosphorus, crude, composition of, 131, 132 - - —— —— distillation of, 133-135 - - —— —— purification of, 132 - - —— distillation of, 127-132 - - —— galley furnace for distilling, 128, 129 - - —— loss of, 132 - - —— manufacture of, 117-140 - - —— —— of, with the assistance of electricity, 138-140 - - —— operations in the preparation of, 117 - - —— refined, moulding of, 135-137 - - —— refining and purifying of, 132-135 - - —— receivers for, 129 - - —— removal of, from the receivers, 131 - - —— residue in the manufacture of, 127 - - —— sticks, mode of forming, 135-137 - - —— storing of, 138 - - Photographers, caseine mucilage for 266 - - Photographic printing, gelatine for 183, 184 - - Photo-lithography, use of glue in, 14 - - Pierres de mastic, 226, 227 - - Pipes exposed to a red heat, cement for tightening joints of, 241 - - Plaster of Paris, 244 - - —— —— —— cement, universal, 245 - - —— —— —— statues, cement for, 244, 245 - - Pliable paste, 263 - - Porcelain, cement for, 231, 239, 240, 241, 243, 245 - - —— oil cement for, 229 - - —— paste for attaching labels to, 270 - - —— sulphur cement for, 232, 233 - - Postage stamps, mucilage for, 264 - - Potassium carbonate, behavior of glue solution towards, 7 - - Printing rollers, compositions for, 157 - - Putty, 224, 225 - - - Quick lime, 243 - - - Rabbit skins, 18, 31 - - Rag-engine, 39 - - Raw materials and their preparation for the manufacture of glue, 16-38 - - —— —— collection and buying of, 16 - - —— —— division of, 16 - - Receivers for collecting phosphorus, 129 - - —— —— removal of phosphorus from the, 131 - - Red lead cement, 225 - - Resinous cements, 220, 221, 229-233 - - Retort-furnace, Belgian, for the carbonization of bones, 109-112 - - Retorts, 127, 128 - - Rochelle salts, behavior of glue solution towards, 7 - - Rubber and gutta-percha cements, 222, 233-237 - - —— cement for, 250 - - —— —— —— chemical apparatus, 248, 249 - - —— glue as a partial substitute for, 14 - - Russia, preparation of isinglass in, 197, 198 - - Russian glue, 149, 150 - - —— isinglass, 197, 198 - - —— steam glue, 152 - - - Sahlstrom’s process for preparing a substitute for isinglass, gelatine - and glue, 203, 204 - - Sal ammoniac, effect of, on glue solution, 7 - - Saltpetre, effect of, on glue solution, 7 - - Salts, behavior of glue solution towards, 7, 8 - - Samovey leaf isinglass, 197 - - Sandpaper, use of glue in the manufacture of, 12 - - Sausage skins, glue for parchment paper in making, 154, 155 - - Scheibler’s cement for chemical apparatus, 249 - - Schneible, J., machine for cutting the jelly into cakes invented - by, 60-62 - - Scrap-books, paste for, 266, 267 - - Selenite, 244 - - Seltsam’s apparatus for extracting bones, 84-86 - - —— —— for extracting bones improved by Th. Richter, 88-90 - - Serbat’s mastic, 227, 228 - - Seubert’s apparatus for moulding phosphorus, 135, 136 - - Sheds for glue-stock, 26 - - Sheep leather, 31 - - —— skin waste, 18 - - Shell lime, 28 - - Shoemakers’ paste, 258, 259 - - Siberian purse isinglass, 197 - - Sieve for sorting crushed bones, 36, 37 - - Silicate of soda, 240 - - Silk, artificial, from gelatine, 195 - - Sinews, 1 - - Size, 157-160 - - —— glue, 150 - - Sizing, glue in, 12 - - Skin gelatine, 166-170 - - —— —— modern process of preparing, 167-170 - - —— glue, classification of operations in the manufacture of, 43 - - —— —— manufacture of, 43-73 - - —— -like raw materials, 16 - - Skins, paste for, 267 - - —— steeping of, 18 - - —— used for packing, use of, for glue, 19 - - Sodium carbonate, behavior of glue solution towards, 7 - - Soft putty, 225 - - —— rubber cement, 233, 234 - - Sounds, 41 - - Spiral evaporators, 100, 101 - - Stamping mill for crushing bones, 34, 35 - - Staple isinglass, 197 - - Starch and glue cements, 222, 223 - - —— paste, 255, 256, 261 - - Steam, apparatus for boiling glue with, 47-49 - - Steam boiler cement, 250 - - —— glue, 152 - - —— high-pressure, treatment of bones with, 105-107 - - —— pipes, cement for, 250, 251 - - —— —— oil cement free from lead for, 228 - - —— —— —— cements for, 228 - - Steaming bones, 75, 76 - - Stephenson’s oil cement, 228 - - Stick mastic cement, 232 - - Stone lime, 28 - - Stove plates, cracked, cement for, 246 - - Stoves, black cement for, 246 - - Stratena, 252 - - Straw, use of, as a filter, 44 - - Sugar and lime paste, 265 - - Sulphate of alumina, use of, for clarifying glue liquor, 54 - - —— —— baryta, addition of, to glue, 149 - - Sulphuric acid, decomposition of bone ash by, 119-125 - - Sulphurous acid, absorption of, by bones, 92 - - —— —— bleaching glue with, 143-145 - - —— —— glue-stock with, 55, 56 - - —— —— dilute, treatment of bones with, 38 - - —— —— generation of, 93, 94 - - —— —— process for extracting bones, 92-94 - - —— —— solution, apparatus for the production of, 143, 144 - - Surrons, 31 - - Swinborne’s improved patented process for the preparation of - gelatine, 167 - - - Table tops, paste for attaching cloth or leather to, 269 - - Tannery waste, yield of glue from, 18 - - Tannin as a test for the presence of gelatine, 165 - - —— effect of, on glue solution, 8 - - —— removal of, from leather waste, 39-41 - - Tendons, 1 - - Terne’s apparatus for the generation of sulphurous acid, 94 - - —— glue boiler, 51, 52 - - Terra-cotta articles, cement for, 232 - - Testing glue and gelatine, 205-217 - - Tin foil, paste for fastening paper on, 266, 270 - - Tin paste for attaching labels to, 268 - - Tires, cement for, 250 - - Tools for cutting the jelly into cakes, 59 - - Tortoise shell, cement for, 232 - - —— —— glue imitations of, 15 - - Toys indestructible mass for, 155 - - Tragacanth, 261 - - —— mucilage, 264 - - Transition stages of glue, 2, 3 - - Tub-size, manufacture of, 158, 159 - - Tungstic glue, 155 - - Turners, cement for, 229, 230 - - Twine netting, objections to, 66, 67 - - - Under skin, 17 - - Uses of glue, 10-15 - - - Vacuum pans, 101-103 - - Vasa lymphatica, 1 - - Vats, clarifying, 53 - - Veneers, gelatine, 15, 186-193 - - Venetian paste, 262 - - - Walls, damp, marine glue for, 235 - - Wash basins, cement for, 225, 226 - - Washing drum, 22 - - Waste, green, liming of, 26, 27 - - —— liming of, 20 - - —— putrefaction of, 20, 21 - - Water-glass and water-glass cements, 240-242 - - —— —— constitution of, 240 - - Water-proof cement, 227 - - —— —— glue, 160 - - —— proofing fabrics, 161-163 - - —— —— wrapping paper, 160, 161 - - —— tanks, iron, cement for, 246 - - Weavers’ looms, worn-out hinges from, 30 - - Weidenbusch’s method of testing glue, 211-213 - - Whalebone, cement for, 232 - - Whale glue, 204 - - Whip leather, 30 - - White-lead, addition of, to glue, 149 - - Wood, cement for, 230, 239, 240 - - —— —— —— attaching metal letters to, 249 - - —— —— —— —— to metal, 251 - - Wooden vessels, insoluble cement for, 233 - - Wrapping paper, water-proof, 160, 161 - - - Zinc plates, gelatinizing liquors upon, 58, 59 - - —— white cement, 226 - - —— addition of, to glue, 149 - - * * * * * - -Transcriber's Notes - -Obvious typographical errors have been silently corrected. Variations -in hyphenation have been standardised but all other spelling and -punctuation remains unchanged. - -Italics are represented thus _italic_. - -Within the chemical formulae subscripted numerals are shown thus _{2}_. - -The following corrections have been made: - - Line 4516 From - III. 3Ca(PO_{3})_{2} + 10C = 10CO + Ca_{3}(PO_{4})_{2} = P_{2} - to - III. 3Ca(PO_{3})_{2} + 10C = 10CO + Ca_{3}(PO_{4})_{2} + P_{4} - - Line 4742 From - 3Ca(PO_{3})_{2} + 5Ca_{2}_ = Ca_{3}(PO_{4})_{2} + 10CO + 4P. - to - 3Ca(PO_{3})_{2} + 10C = Ca_{3}(PO_{4})_{2} + 10CO + 4P. - - - - - - -End of the Project Gutenberg EBook of Glue, Gelatine, Animal Charcoal, -Phosphorous, Cements, Pastes and, by F. 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Dawidowsky. - </title> - <link rel="coverpage" href="images/cover.jpg" /> - <style type="text/css"> - -body { - margin-left: 10%; - margin-right: 10%; -} - -h1 -{ - margin-top: 2em; margin-bottom: 2em; - text-align: center; - font-size: x-large; - font-weight: normal; - line-height: 1.6; -} - - h2,h3{ - text-align: center; - clear: both; - } -h4{ text-align: center; font-weight: normal;} - -div.chapter {page-break-before: always;} - -p -{ - margin-top: .75em; - text-align: justify; - margin-bottom: .75em; -} - - -.half-title { - margin-top: 2em; margin-bottom: 2em; - text-align: center; - font-size: x-large; - font-weight: normal; - line-height: 1.6; -} - -.spaced {margin-top: 3em; margin-bottom: 3em;} -.space-above {margin-top: 6em;} - -.hang {text-align: justify; padding-left: 1.75em; text-indent: -1.75em;} - - -hr.tb {width: 45%; margin-left: 27.5%; margin-right: 27.5%;} -hr.chap {width: 65%; margin-left: 17.5%; margin-right: 17.5%;} -hr.small {width: 25%; margin-left: 37.5%; margin-right: 37.5%;} - -ul.index { list-style-type: none; } -li.ifrst { margin-top: 1em; } -li.indx { margin-top: .5em; } - -table { - margin-left: auto; - margin-right: auto; -} - .ch {text-align: justify; text-indent: -1em; margin-left: 1em;} - .crb {text-align: right; vertical-align: bottom;} - .ct {text-align: center; vertical-align: top;} - .cc {text-align: center;} - .cl {text-align: left;} - .ccbt {text-align: center; border-top: 1px solid} - -#glues {margin: auto; font-size: small; border-bottom: 1px solid black;} -#glues th {border-top:1px solid black; - border-bottom:1px solid black;} -#glues th, -#glues td {border-right: 1px solid black;} -#glues td {vertical-align: bottom;} -#glues th.nbr, -#glues td.nbr {border-right: none;} -#glues td.top {text-align: left; vertical-align: top;} -#glues td.topnbr {text-align: right; vertical-align: top; border-right: none;} - -.pagenum { /* uncomment the next line for invisible page numbers */ - visibility: hidden; - position: absolute; - left: 92%; - font-size: smaller; - text-align: right; -} /* page numbers */ - - -.blockquote { - margin-left: 5%; - margin-right: 10%; -} - - -.center {text-align: center;} - -.right {text-align: right;} - -.smcap {font-variant: small-caps;} - -.xs {font-size: x-small;} -.small {font-size: small;} - - -/* Images */ -.figcenter {margin: 1em auto; text-align: center;} -.caption {font-size: smaller; font-weight: bold;} -img {border: none; max-width: 100%} - - -/* Footnotes */ - -.footnote {margin-left: 10%; margin-right: 10%; font-size: 0.9em;} - -.footnote .label {position: absolute; right: 84%; text-align: right;} - -.fnanchor { - vertical-align: super; - font-size: .8em; - text-decoration: none; - white-space: nowrap -} - - -/* Transcriber's notes */ -.transnote {background-color: #E6E6FA; - color: black; - font-size:smaller; - padding:0.5em; - margin-bottom:5em; - font-family:sans-serif, serif; } - </style> - </head> -<body> - - -<pre> - -The Project Gutenberg EBook of Glue, Gelatine, Animal Charcoal, -Phosphorous, Cements, Pastes and, by F. Dawidowsky - -This eBook is for the use of anyone anywhere in the United States and most -other parts of the world at no cost and with almost no restrictions -whatsoever. You may copy it, give it away or re-use it under the terms of -the Project Gutenberg License included with this eBook or online at -www.gutenberg.org. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - - - -Title: Glue, Gelatine, Animal Charcoal, Phosphorous, Cements, Pastes and Mucilages - -Author: F. Dawidowsky - -Editor: William T. Brannt - -Release Date: October 25, 2016 [EBook #53363] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK GLUE *** - - - - -Produced by deaurider, Les Galloway and the Online -Distributed Proofreading Team at http://www.pgdp.net - - - - - - -</pre> - -<hr class="chap" /> - - - -<h1> -GLUE, GELATINE, ANIMAL CHARCOAL,<br /> -PHOSPHORUS, CEMENTS, PASTES,<br /> -AND MUCILAGES,</h1> - -<p class="center xs">COMPRISING</p> - -<p class="center small">THE RAW MATERIALS AND MANUFACTURE OF SKIN AND BONE GLUE,<br /> -DIFFERENT VARIETIES OF GLUE, ANIMAL CHARCOAL, PHOSPHORUS,<br /> -GELATINE AND PRODUCTS PREPARED FROM IT; ISINGLASS AND<br /> -FISH-GLUE, METHODS OF TESTING GLUE AND GELATINE,<br /> -AND THE PREPARATION AND APPLICATION OF<br /> -CEMENTS, PASTES AND MUCILAGES FOR USE<br /> -IN THE WORKSHOP, LABORATORY,<br /> -AND OFFICE.</p> - - -<p class="center"><span class="xs">BY</span><br /> -F. DAWIDOWSKY,<br /> -<span class="xs">TECHNICAL CHEMIST.</span></p> - - -<p class="center small">EDITED FROM THE GERMAN, WITH EXTENSIVE ADDITIONS, INCLUDING -A DESCRIPTION OF THE MOST RECENT PROCESSES.</p> - -<p class="center"><span class="xs">BY</span><br /> -WILLIAM T. BRANNT,<br /> -<span class="xs">EDITOR OF “THE TECHNO-CHEMICAL RECEIPT BOOK.”</span></p> - -<p class="center small">ILLUSTRATED BY FIFTY-NINE ENGRAVINGS.</p> - -<p class="center small">SECOND EDITION, REVISED AND LARGELY RE-WRITTEN.</p> - -<hr class="small" /> - -<p class="center small space-above">PHILADELPHIA:<br /> -HENRY CAREY BAIRD & CO.,<br /> -<span class="smaller">INDUSTRIAL PUBLISHERS, BOOKSELLERS AND IMPORTERS,<br /> -<span class="smcap">810 Walnut Street</span>.</span><br /> -1905. -</p> - -<hr class="chap" /> - - -<p class="center small spaced"> -<span class="smcap">Copyright, by</span><br /> -HENRY CAREY BAIRD & CO.,<br /> -1905.</p> - -<p class="center small spaced"> -PRINTED BY THE<br /> -WICKERSHAM PRINTING CO.,<br /> -53 and 55 North Queen Street,<br /> -<span class="smcap">Lancaster, Pa., U. S. A.</span><br /> -</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_iii" id="Page_iii">[Pg iii]</a></span></p> - - - - -<h2 id="PREFACE_TO_THE_SECOND_EDITION">PREFACE TO THE SECOND EDITION.</h2> - - -<p>The first edition of this work has been out of print for -some years, but nevertheless there is a constant demand for -it, and this together with the fact that frequent inquiries -are received for information in this department of industry, -are the inducements which have led to the preparation of -the present treatise.</p> - -<p>The book is arranged in two parts, Part I. comprising -Glue, Gelatine and Allied Products, and Part II. Cements, -Pastes and Mucilages, and it is fully illustrated with engravings -of various types of apparatus.</p> - -<p>Since the appearance of the first edition much progress -has been made in the manufacture of glue and allied products. -Old and wasteful methods of working have been -replaced by more approved processes, and in the present -volume it has been endeavored to place before those interested -in these industries, a practical and comprehensive -account of modern methods of operation.</p> - -<p>In order adequately to represent this advancement and -development, the best authorities have been freely consulted -and drawn upon, special acknowledgments being due to -the following works: “Bone Products and Manures,” by -Thomas Lambert, and “Glue and Glue Testing,” by -Samuel Rideal.</p> - -<p>As the demand for phosphorus is steadily increasing, and -the manufacture of this product from bones and bone-ash -forms an important branch of the utilization of bones, it has -been deemed advisable to devote a chapter to this subject.</p> - -<p>The receipts for cements, pastes, and mucilages given in<span class="pagenum" id="Page_iv">iv</span> -Part II. have been gathered from numerous sources. They -have been critically examined, and are offered, with the -full conviction, that they will not be found wanting in -efficacy.</p> - -<p>The Table of Contents and Index have both been carefully -prepared, and being very full, will make reference to -any subject in the volume easy and satisfactory.</p> - -<p class="right"> -W. T. B.</p> - -<p><span class="smcap small">Philadelphia, Pa., August 10, 1905.</span></p> - -<hr class="chap" /> - -<p><span class="pagenum" id="Page_v">v</span></p> - - - - -<h2 id="CONTENTS">CONTENTS.</h2> - - -<div class="small"> -<div class="center"> -<table border="0" cellpadding="4" cellspacing="0" summary=""> -<tr><td class="cc" colspan="2"><big><a href="#PART_I">PART I</a>.</big></td> -</tr> -<tr> - <td class="cc" colspan="2">GLUE AND GELATINE.</td> -</tr> -<tr> - <td class="cc" colspan="2"><a href="#CHAPTER_I">CHAPTER I</a>.</td> -</tr> -<tr> - <td class="cc" colspan="2">NATURE of GLUE.</td> -</tr> -<tr> - <td class="cc" colspan="2">PAGE</td> -</tr> - -<tr> - <td class="ch">Sources of glue; Change in the animal tissues by continued boiling; Definition -of what is known as glue; Most important glue-yielding substances</td> -<td class="crb"><a href="#Page_1">1</a></td> -</tr> - -<tr> - <td class="ch">Transformations of which glue and gelatine are the products; Transition -stages of glue; Production of the glue-yielding substance of the animal -body</td> - <td class="crb"><a href="#Page_2">2</a></td> -</tr> - -<tr> - <td class="ch">Crude glue and jelly; Constitution of glue; Combinations of which glue -consists</td> - <td class="crb"><a href="#Page_3">3</a></td> -</tr> - -<tr> - <td class="ch">Preparation of pure glutin; Properties of glutin</td> - <td class="crb"><a href="#Page_4">4</a></td> -</tr> - -<tr> - <td class="ch">Preparation and properties of chondrin</td> - <td class="crb"><a href="#Page_5">5</a></td> -</tr> - -<tr> - <td class="ch">Adhesive power of glutin and of chondrin; Properties of glue and its behavior -towards other substances; Quantity of glutin in glue </td> - <td class="crb"><a href="#Page_6">6</a></td> -</tr> - -<tr> - <td class="ch">Properties of jelly before drying to glue; Absorption of ozone by the -jelly; Behavior of glue solution towards different salts; Effect of acids -upon glue; Meta-gelatin</td> - <td class="crb"><a href="#Page_7">7</a></td> -</tr> - -<tr> - <td class="ch">Combinations of tannin with the jelly; Effects of dry heat upon glue; -Chemical composition of glue and glue-yielding substance </td> - <td class="crb"><a href="#Page_8">8</a></td> -</tr> - -<tr> - <td class="cc" colspan="2"> -<a href="#CHAPTER_II">CHAPTER II</a>.</td> -</tr> - -<tr> - <td class="cc" colspan="2">USES of GLUE.</td> -</tr> - -<tr> - <td class="ch">Glue as a joining medium, and requirements for this purpose</td> - <td class="crb"><a href="#Page_10">10</a></td> -</tr> - -<tr> - <td class="ch">Glue as a binding agent; Consumption of glue in the manufacture of -matches</td> - <td class="crb"><a href="#Page_11">11</a></td> -</tr> - -<tr> - <td class="ch">Quality of glue required by bookbinders; Glue in sizing; Glue for culinary -and medicinal purposes</td> - <td class="crb"><a href="#Page_12">12</a></td> -</tr> - -<tr> - <td class="ch">Glue for clarifying and fining beer, wine and other liquids; Bouillon -tablets; Glue as a healing agent</td> - <td class="crb">13 -<span class="pagenum" id="Page_vi">vi</span></td> -</tr> - -<tr> - <td class="ch">Glue for elastic masses and a partial substitute for rubber; Use of glue in -photolithography; Hectograph mass; Glue for fancy articles</td> - <td class="crb"><a href="#Page_14">14</a></td> -</tr> - -<tr> - <td class="ch">Gelatine veneers and their uses</td> - <td class="crb"><a href="#Page_15">15</a></td> -</tr> - -<tr> - <td class="cc" colspan="2"> -<a href="#CHAPTER_III">CHAPTER III</a>.</td> -</tr> - -<tr> - <td class="cc" colspan="2">RAW MATERIALS AND THEIR PREPARATION FOR THE MANUFACTURE OF GLUE.</td> -</tr> - -<tr> - <td class="ch">Principal substances employed for the manufacture of glue; Division of -raw materials into groups</td> - <td class="crb"><a href="#Page_16">16</a></td> -</tr> - -<tr> - <td class="ch">Animal skin and its constitution</td> - <td class="crb"><a href="#Page_17">17</a></td> -</tr> - -<tr> - <td class="ch">Portion of the skin of value for the manufacture of leather and glue; -Yield of glue from tannery waste; Influence of the age of the animals -from which the skins have been derived upon the quality of the glue </td> - <td class="crb"><a href="#Page_18">18</a></td> -</tr> - -<tr> - <td class="ch">Notes in reference to judging glue-stock</td> - <td class="crb"><a href="#Page_19">19</a></td> -</tr> - -<tr> - <td class="ch">Liming of waste</td> - <td class="crb"><a href="#Page_20">20</a></td> -</tr> - -<tr> - <td class="ch">Precaution and care required when buying glue leather; Arrangements -required for the preparation of glue stock; Location of the glue factory; -Lime pits; Contrivances for washing the limed stock</td> - <td class="crb"><a href="#Page_21">21</a></td> -</tr> - -<tr> - <td class="ch">Washing drums; Pits or vats with proper arrangements for stirring, -draining and inspection; Glue stock washer invented by W. A. -Hoeveller, described and illustrated</td> - <td class="crb"><a href="#Page_22">22</a></td> -</tr> - -<tr> - <td class="ch">Sheds for storing and sorting; Mode of carrying on the work in the factory; -Liming; Preparation of milk of lime</td> - <td class="crb"><a href="#Page_26">26</a></td> -</tr> - -<tr> - <td class="ch">Importance of the quality of the lime used; Testing the value of a lime -by determining the amount of real calcium hydroxide contained in it; -Mode of conducting the operation</td> <td class="crb"><a href="#Page_27">27</a></td> -</tr> - -<tr> - <td class="ch">Washing the material after removal from the lime pit; Washing and drying</td> - <td class="crb"><a href="#Page_28">28</a></td> -</tr> - -<tr> - <td class="ch">Preservation of the glue-stock by means of carbolic acid; Preparation of -carbolic acid solution for this purpose</td> - <td class="crb"><a href="#Page_29">29</a></td> -</tr> - -<tr> - <td class="ch">Use of other antiseptics for the purpose of preventing putrefaction; Formaldehyde -and boric acid; Classification of the principal varieties of -hides and leather for glue-stock</td> - <td class="crb"><a href="#Page_30">30</a></td> -</tr> - -<tr> - <td class="ch">Bones and cartilages</td> - <td class="crb"><a href="#Page_31">31</a></td> -</tr> - -<tr> - <td class="ch">Constitution of bones; Composition of bone cartilage; Value of bones for -the manufacture of glue; Necessity of exercising care in buying bones</td> - <td class="crb"><a href="#Page_32">32</a></td> -</tr> - -<tr> - <td class="ch">Sorting the bones; Crushing or grinding the bones</td> - <td class="crb"><a href="#Page_33">33</a></td> -</tr> - -<tr> - <td class="ch">Stamping mill for crushing bones, described and illustrated</td> - <td class="crb"><a href="#Page_34">34</a></td> -</tr> - -<tr> - <td class="ch">Bone crusher, described and illustrated; Crosskill bone mill, described and -illustrated; Sieve for sorting the crushed bones, described and illustrated</td> - <td class="crb"><a href="#Page_36">36</a></td> -</tr> - -<tr> - <td class="ch">Lime bath for bones; Treatment of the bones with hydrochloric acid</td> - <td class="crb"><a href="#Page_37">37</a></td> -</tr> - -<tr> - <td class="ch">Washing the stock; Use of dilute sulphurous acid in place of hydrochloric -acid as suggested by Gerland; Jullion and Pirie’s process for -the preparation of gelatine from bones</td> -<td class="crb">38 -<span class="pagenum" id="Page_vii">vii</span></td> -</tr> - -<tr> - <td class="ch">Leather waste; Mechanical manipulation of the waste; Comminution of -the waste and use of a rag-engine or hollander for this purpose</td> - <td class="crb"><a href="#Page_39">39</a></td> -</tr> - -<tr> - <td class="ch">Various methods of extracting tannin from leather waste</td> - <td class="crb"><a href="#Page_40">40</a></td> -</tr> - -<tr> - <td class="ch">Raw materials for fish glue; Difference between isinglass and glue manufactured -from entire fishes; Principal points to be observed in the manufacture -of fish glue</td> - <td class="crb"><a href="#Page_41">41</a></td> -</tr> - -<tr> - <td class="ch">Utilization of scales of large fishes</td> - <td class="crb"><a href="#Page_42">42</a></td> -</tr> - -<tr> - <td class="cc" colspan="2"> -<a href="#CHAPTER_IV">CHAPTER IV</a>.</td> -</tr> - -<tr> - <td class="cc" colspan="2">MANUFACTURE OF SKIN GLUE.</td> -</tr> - -<tr> - <td class="ch">Classification of operations; Definition of crude glue; Derivation of the -bulk of this stock</td> - <td class="crb"><a href="#Page_43">43</a></td> -</tr> - -<tr> - <td class="ch">Cooking or boiling glue-stock; Boiler for this purpose, and manner of -using it</td> - <td class="crb"><a href="#Page_44">44</a></td> -</tr> - -<tr> - <td class="ch">Duration of boiling</td> - <td class="crb"><a href="#Page_45">45</a></td> -</tr> - -<tr> - <td class="ch">Mode of ascertaining the progress of the operation; Convenient apparatus -for glue-boiling with water, described and illustrated</td> - <td class="crb"><a href="#Page_46">46</a></td> -</tr> - -<tr> - <td class="ch">Extracting the glue stock by the use of steam</td> - <td class="crb"><a href="#Page_47">47</a></td> -</tr> - -<tr> - <td class="ch">Boiler for this purpose, described and illustrated; Use of open-jacketed -pans heated by steam, described and illustrated</td> - <td class="crb"><a href="#Page_49">49</a></td> -</tr> - -<tr> - <td class="ch">Process of cooking as described by Mr. Thomas Lambert; Terne’s glue -boiler, described and illustrated</td> - <td class="crb"><a href="#Page_51">51</a></td> -</tr> - -<tr> - <td class="ch">Clarifying the glue-liquor</td> - <td class="crb"><a href="#Page_52">52</a></td> -</tr> - -<tr> - <td class="ch">Distinction between clearness and color; Clarifying vats; Prevention of -putrefaction of the liquor</td> - <td class="crb"><a href="#Page_53">53</a></td> -</tr> - -<tr> - <td class="ch">Use of alum and other chemicals for clarifying; Freeing the liquor from -coloring substances</td> - <td class="crb"><a href="#Page_54">54</a></td> -</tr> - -<tr> - <td class="ch">Use of animal charcoal for this purpose; Bleaching the raw materials previous -to boiling them to glue; Use of chloride of lime or of sulphurous -acid for this purpose</td> - <td class="crb"><a href="#Page_55">55</a></td> -</tr> - -<tr> - <td class="ch">Forming or moulding the glue; Moulds for this purpose</td> - <td class="crb"><a href="#Page_56">56</a></td> -</tr> - -<tr> - <td class="ch">Detaching the glue from the sides of the moulding boxes; Cutting the -cubes of glue into commercial cakes or sheets; On what the shape of -the cakes depends</td> - <td class="crb"><a href="#Page_57">57</a></td> -</tr> - -<tr> - <td class="ch">Use of stone-slabs in place of cooling boxes; Use of glass or zinc plates -for liquors which in gelatinizing do not become very solid</td> - <td class="crb"><a href="#Page_58">58</a></td> -</tr> - -<tr> - <td class="ch">Tools for cutting the jelly into cakes, described and illustrated</td> - <td class="crb"><a href="#Page_59">59</a></td> -</tr> - -<tr> - <td class="ch">Machine for slicing and spreading glue-jelly preparatory to drying invented -by Mr. J. Schneible, described and illustrated</td> - <td class="crb"><a href="#Page_60">60</a></td> -</tr> - -<tr> - <td class="ch">Cutting apparatus patented by M. Devoulx, described and illustrated</td> - <td class="crb"><a href="#Page_62">62</a></td> -</tr> - -<tr> - <td class="ch">Drying the cakes of glue; Drying in the open air; Mode of conducting -the operation in a drying room</td> - <td class="crb"><a href="#Page_64">64</a></td> -</tr> - -<tr> - <td class="ch">Size of the drying room; Circulation and change of air in the drying -room</td> - <td class="crb">65 -<span class="pagenum" id="Page_viii">viii</span></td> -</tr> -<tr> - <td class="ch">Nets and frames for drying the glue; Objections to twine netting</td> - <td class="crb"><a href="#Page_66">66</a></td> -</tr> - -<tr> - <td class="ch">Metallic netting and its advantages; Regulation of the temperature of the -drying room; Means of promoting the dryness of the air </td> - <td class="crb"><a href="#Page_67">67</a></td> -</tr> - -<tr> - <td class="ch">Use of long drying galleries; Apparatus for drying glue, invented by -W. A. Hoeveller, described and illustrated</td> - <td class="crb"><a href="#Page_68">68</a></td> -</tr> - -<tr> - <td class="ch">Modern drying house, described and illustrated</td> - <td class="crb"><a href="#Page_71">71</a></td> -</tr> - -<tr> - <td class="ch">Method to accelerate the drying of glue, proposed by Fleck</td> - <td class="crb"><a href="#Page_72">72</a></td> -</tr> - -<tr> - <td class="ch">Mode of giving the dry cakes a good lustrous appearance</td> - <td class="crb"><a href="#Page_73">73</a></td> -</tr> - -<tr> - <td class="cc" colspan="2"> -<a href="#CHAPTER_V">CHAPTER V</a>.</td> -</tr> - -<tr> - <td class="cc" colspan="2">MANUFACTURE OF BONE GLUE.</td> -</tr> - -<tr> - <td class="ch">Comminution of the bones; Various methods of extracting the fat; Boiling -bones</td> - <td class="crb"><a href="#Page_74">74</a></td> -</tr> - -<tr> - <td class="ch">Steaming bones and apparatus for this purpose</td> - <td class="crb"><a href="#Page_75">75</a></td> -</tr> - -<tr> - <td class="ch">Extraction of bones with benzine or carbon disulphide; Apparatus for the -use of benzine invented by Messrs. Wm. Adamson and Charles F. A. -Simonis of Philadelphia, Pa., described and illustrated</td> - <td class="crb"><a href="#Page_76">76</a></td> -</tr> - -<tr> - <td class="ch">Adamson’s method for treating substances with hydrocarbon vapor for the -purpose of extracting oils, fats, etc., described and illustrated</td> - <td class="crb"><a href="#Page_79">79</a></td> -</tr> - -<tr> - <td class="ch">Adamson’s method for treating substances with liquid hydrocarbon for -the purpose of extracting oils, fats, etc., described and illustrated</td> - <td class="crb"><a href="#Page_82">82</a></td> -</tr> - -<tr> - <td class="ch">Adamson’s process for removing hydrocarbons from substances which -have been treated therewith, described and illustrated</td> - <td class="crb"><a href="#Page_84">84</a></td> -</tr> - -<tr> - <td class="ch">F. Seltsam’s apparatus, described and illustrated</td> - <td class="crb"><a href="#Page_86">86</a></td> -</tr> - -<tr> - <td class="ch">F. Seltsam’s apparatus as improved by Th. Richter, described and illustrated</td> - <td class="crb"><a href="#Page_88">88</a></td> -</tr> - -<tr> - <td class="ch">Alfred Leuner’s apparatus, described and illustrated</td> - <td class="crb"><a href="#Page_90">90</a></td> -</tr> - -<tr> - <td class="ch">Extraction with hydrochloric acid </td> - <td class="crb"><a href="#Page_91">91</a></td> -</tr> - -<tr> - <td class="ch">Sulphurous acid process</td> - <td class="crb"><a href="#Page_92">92</a></td> -</tr> - -<tr> - <td class="ch">Generation of sulphurous acid</td> - <td class="crb"><a href="#Page_93">93</a></td> -</tr> - -<tr> - <td class="ch">Apparatus for the generation of sulphurous acid constructed by Dr. Bruno -Terne, described and illustrated; Conversion of cartilage into glue; -Wm. Friedberg’s apparatus for this purpose, described and illustrated </td> - <td class="crb"><a href="#Page_94">94</a></td> -</tr> - -<tr> - <td class="ch">Mode of operation with this apparatus</td> - <td class="crb"><a href="#Page_95">95</a></td> -</tr> - -<tr> - <td class="ch">Construction of the filter used in connection with the apparatus </td> - <td class="crb"><a href="#Page_96">96</a></td> -</tr> - -<tr> - <td class="ch">Settling tank, described and illustrated; Arrangement of an open evaporating -pan, described and illustrated</td> - <td class="crb"><a href="#Page_98">98</a></td> -</tr> - -<tr> - <td class="ch">Cooling the glue liquor; Use of refrigerating machines for that purpose; -Spiral evaporators</td> - <td class="crb"><a href="#Page_100">100</a></td> -</tr> - -<tr> - <td class="ch">Vacuum pan for evaporating glue and gelatine liquors, described and illustrated</td> - <td class="crb"><a href="#Page_101">101</a></td> -</tr> - -<tr> - <td class="ch">Instrument which indicates the amount of dry glue in the solution, described -and illustrated</td> - <td class="crb"><a href="#Page_103">103</a></td> -</tr> - -<tr> - <td class="ch">Process for the simultaneous utilization of bones for fat, bone-meal and -glue </td> - <td class="crb">104 -<span class="pagenum" id="Page_ix">ix</span></td> -</tr> - -<tr> - <td class="ch">Crushing the bones; Apparatus for subjecting the crushed bones to the -action of high-pressure steam, described and illustrated </td> - <td class="crb"><a href="#Page_105">105</a></td> -</tr> - -<tr> - <td class="ch">Mode of operation with this apparatus </td> - <td class="crb"><a href="#Page_106">106</a></td> -</tr> - -<tr> - <td class="ch">Duration of steaming the bones for the manufacture of animal charcoal </td> - <td class="crb"><a href="#Page_107">107</a></td> -</tr> - -<tr> - <td class="ch">Sorting the bones for the manufacture of animal charcoal; Former method -of carbonization</td> - <td class="crb"><a href="#Page_108">108</a></td> -</tr> - -<tr> - <td class="ch">Arrangement of a Belgian retort-furnace, described and illustrated</td> - <td class="crb"><a href="#Page_109">109</a></td> -</tr> - -<tr> - <td class="ch">Products evolved in the destructive distillation of bones; Mode of operation -with Belgian retort-furnaces </td> - <td class="crb"><a href="#Page_112">112</a></td> -</tr> - -<tr> - <td class="ch">Products obtained in making animal charcoal on a large scale; Process -for the simultaneous utilization of the bones for fat, glue and calcium -phosphate; Degreasing the bones </td> - <td class="crb"><a href="#Page_113">113</a></td> -</tr> - -<tr> - <td class="ch">Treatment of the bones with hydrochloric acid; Preservation of the resulting -cartilage; Boiling the cartilage in open vessels </td> - <td class="crb"><a href="#Page_114">114</a></td> -</tr> - -<tr> - <td class="ch">Mode of extracting the phosphates from bones; Yield of glue obtained -from cartilage after extraction of the mineral constituents; Constituents -of the liquor obtained by treating the bones</td> - <td class="crb"><a href="#Page_115">115</a></td> -</tr> - -<tr> - <td class="ch">Utilization of the liquor in the manufacture of fertilizers</td> - <td class="crb"><a href="#Page_116">116</a></td> -</tr> - -<tr> - <td class="cc" colspan="2"> -<a href="#CHAPTER_VI">CHAPTER VI</a>.</td> -</tr> - -<tr> - <td class="cc" colspan="2">MANUFACTURE OF PHOSPHORUS.</td> -</tr> - -<tr> - <td class="ch">Operations included in the ordinary method of preparing phosphorus; -Burning the bones to ash; Kiln used for this purpose </td> - <td class="crb"><a href="#Page_117">117</a></td> -</tr> - -<tr> - <td class="ch">Improved form of kiln proposed by Fleck; Mode of operation with a kiln -of this construction </td> - <td class="crb"><a href="#Page_118">118</a></td> -</tr> - -<tr> - <td class="ch">Quantity of substance which remains after burning the bones; Composition -of bone ash; Conversion of the bone ash into a coarse powder; Decomposition -of the bone ash by sulphuric acid </td> - <td class="crb"><a href="#Page_119">119</a></td> -</tr> - -<tr> - <td class="ch">Separate processes which have to be distinguished; Embodiment of these -processes in equations </td> - <td class="crb"><a href="#Page_120">120</a></td> -</tr> - -<tr> - <td class="ch">Actual yield of phosphorus; Methods by which the formation of calcium -phosphate may be effected; Process without the assistance of heat</td> - <td class="crb"><a href="#Page_121">121</a></td> -</tr> - -<tr> - <td class="ch">Decomposition of the bone ash in the warm way </td> - <td class="crb"><a href="#Page_122">122</a></td> -</tr> - -<tr> - <td class="ch">Apparatus for hot lixiviation </td> - <td class="crb"><a href="#Page_123">123</a></td> -</tr> - -<tr> - <td class="ch">Evaporation of the liquor; Mixing the fluid with charcoal </td> - <td class="crb"><a href="#Page_124">124</a></td> -</tr> - -<tr> - <td class="ch">Yield of so-called distilling mass; Utilization of the liquor obtained in -treating bones for the manufacture of glue with hydrochloric acid; Concentration -of the liquor for crystallization</td> - <td class="crb"><a href="#Page_125">125</a></td> -</tr> - -<tr> - <td class="ch">Mode of obtaining the calcium phosphate contained in the mother-liquor; -Drying the crystals </td> - <td class="crb"><a href="#Page_126">126</a></td> -</tr> - -<tr> - <td class="ch">Mixing the crystals with charcoal; Evaporating pans; Treatment of the -residue of basic calcium phosphate left in the manufacture of phosphorus; -Distillation of the phosphorus; Conversion of the acid calcium -<span class="pagenum" id="Page_x">x</span>phosphate into calcium metaphosphate and reduction of the latter; Retorts -and furnace for distilling the mixture of acid calcium phosphate -and charcoal; The galley-furnace </td> - <td class="crb"><a href="#Page_127">127</a></td> -</tr> - -<tr> - <td class="ch">Modification of the galley-furnace, described and illustrated </td> - <td class="crb"><a href="#Page_128">128</a></td> -</tr> - -<tr> - <td class="ch">Furnaces for the use of coke as fuel; Receivers for collecting the phosphorus -distilling over</td> - <td class="crb"><a href="#Page_129">129</a></td> -</tr> - -<tr> - <td class="ch">Process of distillation; Indication of the commencement of distillation </td> - <td class="crb"><a href="#Page_130">130</a></td> -</tr> - -<tr> - <td class="ch">Removing the phosphorus from the receivers; Regaining the phosphoric -acid contained in the water from the receivers; Constitution of crude -phosphorus </td> - <td class="crb"><a href="#Page_131">131</a></td> -</tr> - -<tr> - <td class="ch">Refining and purifying the phosphorus; Various methods of purification; -Percentage of loss of phosphorus </td> - <td class="crb"><a href="#Page_132">132</a></td> -</tr> - -<tr> - <td class="ch">Distillation of the crude product in order to obtain pure phosphorus; Retorts -and distilling apparatus for this purpose, described and illustrated</td> - <td class="crb"><a href="#Page_133">133</a></td> -</tr> - -<tr> - <td class="ch">Process of distillation; Different qualities of the phosphorus passing over -in the various stages of distillation; Separation of the phosphorus passing -over according to quality</td> - <td class="crb"><a href="#Page_134">134</a></td> -</tr> - -<tr> - <td class="ch">Moulding the refined phosphorus; Seubert’s apparatus for this purpose </td> - <td class="crb"><a href="#Page_135">135</a></td> -</tr> - -<tr> - <td class="ch">Disadvantages of Seubert’s apparatus; Improved apparatus by which the -operation is rendered perfectly free from danger, described and illustrated</td> - <td class="crb"><a href="#Page_136">136</a></td> -</tr> - -<tr> - <td class="ch">Moulding the phosphorus in wedge-shaped sheet-metal boxes</td> - <td class="crb"><a href="#Page_137">137</a></td> -</tr> - -<tr> - <td class="ch">Mode of storing and shipping phosphorus; Manufacture of phosphorus -with the assistance of electricity; Mixture used for the operation </td> - <td class="crb"><a href="#Page_138">138</a></td> -</tr> - -<tr> - <td class="ch">Furnace employed for the electrolytic manufacture of phosphorus, described -and illustrated</td> - <td class="crb"><a href="#Page_139">139</a></td> -</tr> - -<tr> - <td class="ch">Mode of operating the furnace</td> - <td class="crb"><a href="#Page_140">140</a></td> -</tr> - -<tr> - <td class="cc" colspan="2"> -<a href="#CHAPTER_VII">CHAPTER VII</a>.</td> -</tr> - -<tr> - <td class="cc" colspan="2">METHODS OF BLEACHING GLUE.</td> -</tr> - -<tr> - <td class="ch">Bleaching in the air; Bleaching with chlorine</td> - <td class="crb"><a href="#Page_141">141</a></td> -</tr> - -<tr> - <td class="ch">Bleaching with animal charcoal</td> - <td class="crb"><a href="#Page_142">142</a></td> -</tr> - -<tr> - <td class="ch">Bleaching with sulphurous acid; Apparatus for the production of the -acid solution, described and illustrated</td> - <td class="crb"><a href="#Page_143">143</a></td> -</tr> - -<tr> - <td class="cc" colspan="2"> -<a href="#CHAPTER_VIII">CHAPTER VIII</a>.</td> -</tr> - -<tr> - <td class="ch">DIFFERENT VARIETIES OF GLUE AND THEIR PREPARATION.</td> -</tr> - -<tr> - <td class="ch">Joiner’s glue; Material for the best variety of joiner’s glue</td> - <td class="crb"><a href="#Page_146">146</a></td> -</tr> - -<tr> - <td class="ch">How to make and use glue; Holding power of glue</td> - <td class="crb"><a href="#Page_147">147</a></td> -</tr> - -<tr> - <td class="ch">Cologne glue</td> - <td class="crb"><a href="#Page_148">148</a></td> -</tr> - -<tr> - <td class="ch">Russian glue; Additions by means of which the color and opaqueness are -imparted to this variety of glue</td> - <td class="crb"><a href="#Page_149">149</a></td> -</tr> - -<tr> - <td class="ch">Patent glue; Gilder’s glue; Superior article of gilder’s glue; Size glue -and parchment glue; Paris glue</td> - <td class="crb">150 -<span class="pagenum" id="Page_xi">xi</span></td> -</tr> - -<tr> - <td class="ch">Liquid glues; Receipts for liquid glues</td> - <td class="crb"><a href="#Page_151">151</a></td> -</tr> - -<tr> - <td class="ch">Preparation of saccharate of lime; Steam-glue; Russian steam-glue; Pale -steam-glue; Dark steam-glue</td> - <td class="crb"><a href="#Page_152">152</a></td> -</tr> - -<tr> - <td class="ch">Chrome glue; Glue for attaching leather to metal; Glue for leather, -paper, etc.</td> - <td class="crb"><a href="#Page_153">153</a></td> -</tr> - -<tr> - <td class="ch">Glue for parchment paper in making sausage skins</td> - <td class="crb"><a href="#Page_154">154</a></td> -</tr> - -<tr> - <td class="ch">Tungstic glue; Indestructible mass for the manufacture of ornaments, -toys, etc.; Compound for billiard balls</td> - <td class="crb"><a href="#Page_155">155</a></td> -</tr> - -<tr> - <td class="ch">Coloring glue; Process for this purpose invented by G. J. Lesser</td> - <td class="crb"><a href="#Page_156">156</a></td> -</tr> - -<tr> - <td class="ch">Composition for printing rollers; Size</td> - <td class="crb"><a href="#Page_157">157</a></td> -</tr> - -<tr> - <td class="ch">Process used in an English factory for making tub-size</td> - <td class="crb"><a href="#Page_158">158</a></td> -</tr> - -<tr> - <td class="ch">Preparation of bone-size; Composition of the different grades of size</td> - <td class="crb"><a href="#Page_159">159</a></td> -</tr> - -<tr> - <td class="ch">Concentrated size; Bookbinder’s size; Water-proof glue; Glue solution -for rendering wrapping paper water-proof</td> - <td class="crb"><a href="#Page_160">160</a></td> -</tr> - -<tr> - <td class="ch">Water-proofing fabrics with glue and tannin</td> - <td class="crb"><a href="#Page_161">161</a></td> -</tr> - -<tr> - <td class="ch">Muratori and Landry’s process of water-proofing fabrics</td> - <td class="crb"><a href="#Page_162">162</a></td> -</tr> - -<tr> - <td class="ch">Muzmann and Krakowitzer’s process of water-proofing fabrics; Glue for -joints in leather driving belts; Hectograph mass</td> - <td class="crb"><a href="#Page_163">163</a></td> -</tr> - -<tr> - <td class="ch">Formulas for hectograph masses</td> - <td class="crb"><a href="#Page_164">164</a></td> -</tr> - -<tr> - <td class="cc" colspan="2"> -<a href="#CHAPTER_IX">CHAPTER IX</a>.</td> -</tr> - -<tr> - <td class="cc" colspan="2">MANUFACTURE OF GELATINE, AND PRODUCTS PREPARED FROM IT.</td> -</tr> - -<tr> - <td class="ch">Properties of gelatine; Change in the chemical constitution of gelatine -produced by concentrated sulphuric or nitric acid; Tannin as a test for -the presence of gelatine; Use of gelatine for culinary and medicinal -purposes</td> - <td class="crb"><a href="#Page_165">165</a></td> -</tr> - -<tr> - <td class="ch">Skin gelatine; Method of manufacture introduced and patented, in 1839, -by George Nelson; Process patented, in 1844, by Messrs. J. & G. -Cox of Edinburgh</td> - <td class="crb"><a href="#Page_166">166</a></td> -</tr> - -<tr> - <td class="ch">G. P. Swinborn’s improved patented process for the preparation of gelatine -from hides, skins and glue pieces; Modern process of preparing -skin gelatine; “Steeping” the skins</td> - <td class="crb"><a href="#Page_167">167</a></td> -</tr> - -<tr> - <td class="ch">Washing and bleaching the skins</td> - <td class="crb"><a href="#Page_168">168</a></td> -</tr> - -<tr> - <td class="ch">Digesting the skins; Clarifying the liquors</td> - <td class="crb"><a href="#Page_169">169</a></td> -</tr> - -<tr> - <td class="ch">Evaporation of the liquors in vacuo; Drying the cut cakes; Bone gelatine; -Materials for this purpose; Crushing the bones; Solution of the -glue cartilage</td> - <td class="crb"><a href="#Page_170">170</a></td> -</tr> - -<tr> - <td class="ch">Apparatus and improved manner of manufacture employed in the factory -of D. J. Briers, described and illustrated</td> - <td class="crb"><a href="#Page_171">171</a></td> -</tr> - -<tr> - <td class="ch">Modern process of preparing bone gelatine</td> - <td class="crb"><a href="#Page_179">179</a></td> -</tr> - -<tr> - <td class="ch">Colored gelatine; Uses of colored gelatine; Harmless coloring matters; -Colors for coloring leaves of gelatine with aniline colors for technical -purposes</td> - <td class="crb"><a href="#Page_181">181</a></td> -</tr> - -<tr> - <td class="ch"><span class="pagenum" id="Page_xii">xii</span>Gelatine for fining purposes; <i>Gelatine Lainée</i>; Fining powder for wine -and beer; Liquid fining gelatine; Preparation of gelatine from ordinary -glue</td> - <td class="crb"><a href="#Page_182">182</a></td> -</tr> - -<tr> - <td class="ch">Preparation of gelatine for photographic printing and for photographic -purposes in general; Removal of the salts from the gelatine </td> - <td class="crb"><a href="#Page_183">183</a></td> -</tr> - -<tr> - <td class="ch">Gelatine capsules for medicinal purposes; Court plaster</td> - <td class="crb"><a href="#Page_184">184</a></td> -</tr> - -<tr> - <td class="ch">Gelatine foils; Mode of coloring the foils</td> - <td class="crb"><a href="#Page_185">185</a></td> -</tr> - -<tr> - <td class="ch">Gelatine veneers; Principal operations in the manufacture of gelatine -veneers</td> - <td class="crb"><a href="#Page_186">186</a></td> -</tr> - -<tr> - <td class="ch">Preparation of the plates; Preparation of the glue solutions; Proportions -by weight of the mixtures for ten different varieties of imitations of -marble and enamel</td> - <td class="crb"><a href="#Page_187">187</a></td> -</tr> - -<tr> - <td class="ch">Imitation of mother-of-pearl veneers</td> - <td class="crb"><a href="#Page_188">188</a></td> -</tr> - -<tr> - <td class="ch">Pouring the colored solutions of glue upon the plates</td> - <td class="crb"><a href="#Page_189">189</a></td> -</tr> - -<tr> - <td class="ch">Preparation of imitations of malachite</td> - <td class="crb"><a href="#Page_190">190</a></td> -</tr> - -<tr> - <td class="ch">Transferring the layer of glue to a layer of gelatine</td> - <td class="crb"><a href="#Page_191">191</a></td> -</tr> - -<tr> - <td class="ch">Drying and detaching the veneers</td> - <td class="crb"><a href="#Page_192">192</a></td> -</tr> - -<tr> - <td class="ch">Water-proofing gelatine veneers; Uses of gelatine veneers; Formo-gelatine -and its uses</td> - <td class="crb"><a href="#Page_193">193</a></td> -</tr> - -<tr> - <td class="ch">Use of gelatine in bacteriology</td> - <td class="crb"><a href="#Page_194">194</a></td> -</tr> - -<tr> - <td class="ch">Artificial silk from gelatine</td> - <td class="crb"><a href="#Page_195">195</a></td> -</tr> - -<tr> - <td class="cc" colspan="2"> -<a href="#CHAPTER_X">CHAPTER X</a>.</td> -</tr> - -<tr> - <td class="cc" colspan="2">ISINGLASS AND ITS SUBSTITUTES.</td> -</tr> - -<tr> - <td class="ch">Sources of isinglass; Properties of a good quality of isinglass; Imitations of -isinglass and their detection; Adulteration of isinglass and its detection</td> - <td class="crb"><a href="#Page_196">196</a></td> -</tr> - -<tr> - <td class="ch">Russian isinglass; Siberian purse isinglass; Preparation of isinglass in -Russia</td> - <td class="crb"><a href="#Page_197">197</a></td> -</tr> - -<tr> - <td class="ch">North American or New York isinglass</td> - <td class="crb"><a href="#Page_198">198</a></td> -</tr> - -<tr> - <td class="ch">East India isinglass; Hudson Bay isinglass; Brazilian isinglass</td> - <td class="crb"><a href="#Page_199">199</a></td> -</tr> - -<tr> - <td class="ch">German isinglass; Isinglass from the scales of shad and herring; Bleaching -inferior qualities of isinglass; Ichthycolle Française</td> - <td class="crb"><a href="#Page_200">200</a></td> -</tr> - -<tr> - <td class="ch">Isinglassine; Chinese isinglass</td> - <td class="crb"><a href="#Page_201">201</a></td> -</tr> - -<tr> - <td class="ch">Irish moss; Fish glue; Jennings’ process for the preparation of fish glue</td> - <td class="crb"><a href="#Page_203">203</a></td> -</tr> - -<tr> - <td class="ch">Treatment of fish scales; Production of fish glue on the Norwegian coast; -Substitute for isinglass according to C. A. Sahlström’s process</td> - <td class="crb"><a href="#Page_203">203</a></td> -</tr> - -<tr> - <td class="ch">Whale glue</td> - <td class="crb"><a href="#Page_204">204</a></td> -</tr> - -<tr> - <td class="cc" colspan="2"> -<a href="#CHAPTER_XI">CHAPTER XI</a>.</td> -</tr> - -<tr> - <td class="cc" colspan="2">TESTING GLUE AND GELATINE.</td> -</tr> - -<tr> - <td class="ch">Determination of moisture; Determination of ash; Determination of acidity</td> - <td class="crb"><a href="#Page_205">205</a></td> -</tr> - -<tr> - <td class="ch">Determination of glutin; Bisler-Beumat’s method</td> - <td class="crb"><a href="#Page_206">206</a></td> -</tr> - -<tr> - <td class="ch">Analysis of samples of American glue by S. Dana Hayes; Deduction of -the quality of glue from indirect properties</td> - <td class="crb">207 -<span class="pagenum" id="Page_xiii">xiii</span></td> -</tr> - -<tr> - <td class="ch">Lipowitz’s method of testing the strength of a glue, described and illustrated</td> - <td class="crb"><a href="#Page_208">208</a></td> -</tr> - -<tr> - <td class="ch">Results obtained by comparative experiments</td> - <td class="crb"><a href="#Page_209">209</a></td> -</tr> - -<tr> - <td class="ch">Facts shown by the results</td> - <td class="crb"><a href="#Page_210">210</a></td> -</tr> - -<tr> - <td class="ch">Weidenbusch’s method of testing glue</td> - <td class="crb"><a href="#Page_211">211</a></td> -</tr> - -<tr> - <td class="ch">Preparation of the plaster of Paris stick and of the glue solution used in -this test</td> - <td class="crb"><a href="#Page_212">212</a></td> -</tr> - -<tr> - <td class="ch">Apparatus for testing the strength of the plaster of Paris sticks, described -and illustrated; Test adopted by the “Artillerie Werkstätte” at -Spandau</td> - <td class="crb"><a href="#Page_213">213</a></td> -</tr> - -<tr> - <td class="ch">Determination of adulterations</td> - <td class="crb"><a href="#Page_214">214</a></td> -</tr> - -<tr> - <td class="ch">Kissling’s results in testing a large number of samples of glue</td> - <td class="crb"><a href="#Page_215">215</a></td> -</tr> - -<tr> - <td class="ch">Practical tests of glue</td> - <td class="crb"><a href="#Page_216">216</a></td> -</tr> - -<tr> - <td class="cc" colspan="2"> -<big><a href="#PART_II">PART II.</a></big></td> -</tr> - -<tr> - <td class="cc" colspan="2">CEMENTS, PASTES, MUCILAGES.</td> -</tr> - -<tr> - <td class="cc" colspan="2"> -<a href="#CHAPTER_XII">CHAPTER XII</a>.</td> -</tr> - -<tr> - <td class="cc" colspan="2">CLASSIFICATION OF CEMENTS.</td> -</tr> - -<tr> - <td class="ch">Stohmann’s division of cements and pastes; Groups of cements</td> - <td class="crb"><a href="#Page_218">218</a></td> -</tr> - -<tr> - <td class="ch">Chemical nature of cements; Oil cements</td> - <td class="crb"><a href="#Page_219">219</a></td> -</tr> - -<tr> - <td class="ch">Resinous cements; Definition of resins</td> - <td class="crb"><a href="#Page_220">220</a></td> -</tr> - -<tr> - <td class="ch">Properties of resinous cements</td> - <td class="crb"><a href="#Page_221">221</a></td> -</tr> - -<tr> - <td class="ch">Rubber and gutta-percha cements; Glue and starch cements </td> - <td class="crb"><a href="#Page_222">222</a></td> -</tr> - -<tr> - <td class="ch">Lime cements</td> - <td class="crb"><a href="#Page_223">223</a></td> -</tr> - -<tr> - <td class="cc" colspan="2"> -<a href="#CHAPTER_XIII">CHAPTER XIII</a>.</td> -</tr> - -<tr> - <td class="cc" colspan="2">PREPARATION OF CEMENTS, PASTES, AND MUCILAGES.</td> -</tr> - -<tr> - <td class="ch">Oil cements; Putty and its preparation</td> - <td class="crb"><a href="#Page_224">224</a></td> -</tr> - -<tr> - <td class="ch">French putty; Soft putty; Litharge cement; Red lead cement; Cement -for wash basins</td> - <td class="crb"><a href="#Page_225">225</a></td> -</tr> - -<tr> - <td class="ch">Zinc-white cement; Mastic cement, mastic or <i>pierres de mastic</i> </td> - <td class="crb"><a href="#Page_226">226</a></td> -</tr> - -<tr> - <td class="ch">French mastic; Paget’s mastic; Water-proof cement; Serbat’s mastic</td> - <td class="crb"><a href="#Page_227">227</a></td> -</tr> - -<tr> - <td class="ch">Stephen’s oil cement; Oil cement for glass; Oil cement free from lead for -steam pipes; Oil cements for steam pipes; Oil cement for marble</td> - <td class="crb"><a href="#Page_228">228</a></td> -</tr> - -<tr> - <td class="ch">Oil cement for porcelain; Diamond cement; Hager’s diamond cement; -Resinous cements; Resinous cement for amber; Cement for turners</td> - <td class="crb"><a href="#Page_229">229</a></td> -</tr> - -<tr> - <td class="ch">Cement for ivory and bone; Cement for white enameled clock faces; -Cements for glass; Cement for glass upon glass; Cement for glass upon -metal; Cement for metal letters upon glass; Cement for wood</td> - <td class="crb">230 -<span class="pagenum" id="Page_xiv">xiv</span></td> -</tr> - -<tr> - <td class="ch">Cement for knife handles; Cement for petroleum lamps; Cement for -porcelain; Cement for porcelain which is to be heated; Cement to withstand -the action of petroleum; Cement for mica</td> - <td class="crb"><a href="#Page_231">231</a></td> -</tr> - -<tr> - <td class="ch">Cement for horn, whalebone and tortoise shell; Cement for terra cotta -articles; Mastic cement for glass; Stick mastic cement; Sulphur cement -for porcelain</td> - <td class="crb"><a href="#Page_232">232</a></td> -</tr> - -<tr> - <td class="ch">Insoluble cement for wooden vessels; Rubber cements; Cements for glass; -Soft rubber cement</td> - <td class="crb"><a href="#Page_233">233</a></td> -</tr> - -<tr> - <td class="ch">Hard rubber cement; Elastic cement; Marine glue</td> - <td class="crb"><a href="#Page_234">234</a></td> -</tr> - -<tr> - <td class="ch">Jeffrey’s marine glue; Marine glue for damp walls; Gutta-percha cements; -Cement for leather</td> - <td class="crb"><a href="#Page_235">235</a></td> -</tr> - -<tr> - <td class="ch">Cement for hard rubber combs; Elastic gutta-percha cement; Cement for -horses’ hoofs; Cement for crockery</td> - <td class="crb"><a href="#Page_236">236</a></td> -</tr> - -<tr> - <td class="ch">Cement for leather; Caseine cements; Preparation of pure caseine</td> - <td class="crb"><a href="#Page_237">237</a></td> -</tr> - -<tr> - <td class="ch">Preparation of ordinary technical caseine; John A. Just’s method for -obtaining a purer technical caseine</td> - <td class="crb"><a href="#Page_238">238</a></td> -</tr> - -<tr> - <td class="ch">Caseine cement which can be kept for a long time; Cement for glass; -Cement for metals; Cement for porcelain; Cement for meerschaum; -Cement for wood, etc.</td> - <td class="crb"><a href="#Page_239">239</a></td> -</tr> - -<tr> - <td class="ch">Cement for porcelain; Water-glass and water-glass cements; Water-glass -and its properties; Cement for cracked bottles</td> - <td class="crb"><a href="#Page_240">240</a></td> -</tr> - -<tr> - <td class="ch">Cement for glass and porcelain; Cement for hydraulic works; Cement for -uniting metals; Cement for tightening joints of pipes exposed to a red -heat</td> - <td class="crb"><a href="#Page_241">241</a></td> -</tr> - -<tr> - <td class="ch">Cement for marble and alabaster; Glycerine and glycerine cements; -Properties of commercial glycerine; Glycerine and litharge cement</td> - <td class="crb"><a href="#Page_242">242</a></td> -</tr> - -<tr> - <td class="ch">Lime cements; Properties of lime and chalk; Cement for glass; Cement -for joiners; Cement for cracked clay crucibles and porcelain</td> - <td class="crb"><a href="#Page_243">243</a></td> -</tr> - -<tr> - <td class="ch">Lime and glue cement; Gypsum cements; Preparation of plaster of Paris; -Cement for plaster of Paris statues</td> - <td class="crb"><a href="#Page_244">244</a></td> -</tr> - -<tr> - <td class="ch">Cement for glass and porcelain; Cement for iron and stone; Cements for -porcelain; Universal plaster of Paris cement; Iron cements; Heat-resisting -cement; Water and steam-proof cement; Cement for iron</td> - <td class="crb"><a href="#Page_245">245</a></td> -</tr> - -<tr> - <td class="ch">Fire-proof cement for iron pipes; Cements resisting high temperatures; -Cement for filling in defects in castings; Cement for cracked stove-plates, -etc.; Cement for iron water-tanks; Cement for cracked iron pots</td> - <td class="crb"><a href="#Page_246">246</a></td> -</tr> - -<tr> - <td class="ch">Black cement for stoves; Cements for chemical apparatus; Requirements -of such cements; Cement for small apparatus to be used for the development -of fluoric acid</td> - <td class="crb"><a href="#Page_247">247</a></td> -</tr> - -<tr> - <td class="ch">Linseed oil and clay cement; Linseed oil and manganese cement; Cements -resisting very high temperatures; Cement resisting acids; Rubber -cement for chemical apparatus</td> - <td class="crb"><a href="#Page_248">248</a></td> -</tr> - -<tr> - <td class="ch">Scheibler’s cement for chemical apparatus; Cements for special purposes; -Cement for attaching metal letters to glass, marble, wood, etc.; Cement -for joints of iron pipes</td> - <td class="crb"><a href="#Page_249">249</a></td> -</tr> - -<tr> - <td class="ch">Steam boiler cement; Cement for rubber; Cement for tires; Cement for -steam pipes, etc.</td> - <td class="crb">250 -<span class="pagenum" id="Page_xv">xv</span></td> -</tr> - -<tr> - <td class="ch">Cement for marble; Cement for attaching wood, glass, etc., to metal; -Brushmaker’s cement; Cement for electrical apparatus </td> - <td class="crb"><a href="#Page_251">251</a></td> -</tr> - -<tr> - <td class="ch">Jeweler’s cement; American cement for jewelers; Cement for celluloid; -Stratena; Cement for cloth; How to use cements</td> - <td class="crb"><a href="#Page_252">252</a></td> -</tr> - -<tr> - <td class="ch">Importance of bringing the cement into intimate contact with the surface -to be united</td> - <td class="crb"><a href="#Page_253">253</a></td> -</tr> - -<tr> - <td class="ch">Obstacles to the junction of any two surfaces; Importance of using as -little cement as possible</td> - <td class="crb"><a href="#Page_254">254</a></td> -</tr> - -<tr> - <td class="ch">Cleansing surfaces to be joined from grease and dirt; Paste and mucilages; -Starch paste</td> - <td class="crb"><a href="#Page_255">255</a></td> -</tr> - -<tr> - <td class="ch">Rules for preparing paste; Flour paste</td> - <td class="crb"><a href="#Page_256">256</a></td> -</tr> - -<tr> - <td class="ch">Means to prevent the spoiling of paste</td> - <td class="crb"><a href="#Page_257">257</a></td> -</tr> - -<tr> - <td class="ch">Shoemakers’ paste</td> - <td class="crb"><a href="#Page_258">258</a></td> -</tr> - -<tr> - <td class="ch">Gum arabic and its properties; Dextrine and its use in place of gum -arabic; Properties of commercial dextrine</td> - <td class="crb"><a href="#Page_259">259</a></td> -</tr> - -<tr> - <td class="ch">Preparation of dextrine; Blumenthal’s method</td> - <td class="crb"><a href="#Page_260">260</a></td> -</tr> - -<tr> - <td class="ch">Heuzé’s method; Tragacanth, or gum tragacanth; Pastes and mucilages -for special purposes; Starch paste; Flour paste</td> - <td class="crb"><a href="#Page_261">261</a></td> -</tr> - -<tr> - <td class="ch">Strong adhesive paste; Paste that will not sour; Venetian paste</td> - <td class="crb"><a href="#Page_262">262</a></td> -</tr> - -<tr> - <td class="ch">Label paste; Elastic or pliable paste; Mucilage for labels; Mucilage</td> - <td class="crb"><a href="#Page_263">263</a></td> -</tr> - -<tr> - <td class="ch">Mucilage for postage stamps; Caseine mucilage; Tragacanth mucilage; -Adhesive paste; Fluid pastes</td> - <td class="crb"><a href="#Page_264">264</a></td> -</tr> - -<tr> - <td class="ch">Sugar and lime paste; Liquid sugar and lime paste; Pastes for paper and -fine fancy articles; Albumen paste</td> - <td class="crb"><a href="#Page_265">265</a></td> -</tr> - -<tr> - <td class="ch">Glycerine paste; Paste for fixing labels on machines; Paste for mounting -maps; Paste for fastening paper on tin-foil; Paste for paper bags; -Caseine mucilage for photographer’s use; Paste for scrap books</td> - <td class="crb"><a href="#Page_266">266</a></td> -</tr> - -<tr> - <td class="ch">Paste for skins; Strong mucilage capable of fastening wood on china and -glass; Dextrine mucilage; Paste for joining leather to pasteboard</td> - <td class="crb"><a href="#Page_267">267</a></td> -</tr> - -<tr> - <td class="ch">Paste for attaching labels to polished nickel; Mucilage for attaching -labels to tin; Mucilage for office use; Glycerine paste for office use; -Clean and durable paste</td> - <td class="crb"><a href="#Page_268">268</a></td> -</tr> - -<tr> - <td class="ch">Banknote or mouth glue; Paste for cardboard; Paste for attaching cloth -or leather to table tops; Caseine mucilage; Very adhesive paste which -may be used for wood and parchment</td> - <td class="crb"><a href="#Page_269">269</a></td> -</tr> - -<tr> - <td class="ch">Paste for pads; Paste for fastening paper on tin-foil; Paste for attaching -labels to glass, porcelain and metal; Preparation of arabol-gum; Preparation -of an adhesive substance from desaccharized beet-root slices</td> - <td class="crb"><a href="#Page_270">270</a></td> -</tr> - -<tr> - <td class="ch">Index</td> - <td class="crb"><a href="#Page_273">273</a></td> -</tr> -</table></div></div> - -<hr class="chap" /> - -<p><span class="pagenum" id="Page_xvi">[Pg xvi]</span></p> -<p><span class="pagenum" id="Page_1">1</span></p> - - - - -<p class="half-title">GLUE, GELATINE, CEMENTS, PASTES.</p> - - - -<hr class="small" /> -<h2><a name="PART_I" id="PART_I">PART I.</a><br /> - -<small>GLUE AND GELATINE.</small></h2> - - - -<hr class="small" /> -<div class="chapter"></div> -<h3><a name="CHAPTER_I" id="CHAPTER_I">CHAPTER I.</a><br /> - -<small>NATURE OF GLUE.</small></h3> - - -<h4>1. SOURCES OF GLUE.</h4> - -<p>The organisms of all animals, but more especially of the -higher classes, contain tissues which are insoluble in cold, -as well as in hot, water. However, by continued boiling -they become dissolved, and yield on evaporation of the -solution a glutinous, gelatinizing mass. By further drying -this mass exhibits, according to the degree of purity of the -material, a more or less transparent and brittle substance, -which in its pure state is devoid of color as well as of smell; -it swells up in cold water and dissolves by boiling in that -liquid. This substance, <i>i. e.</i>, the product of the conversion -of the so-called glue or gelatine-yielding tissue, is what is -known in the trade as <em>glue</em>.</p> - -<p>Among the glue-yielding tissues, the following are the -most important: Cellular tissue, the corium, tendons or -sinews, the middle membrane of the vasa lymphatica and -veins, the ossein or organic matter of bones, hartshorn, -cartilage, the air bladders of many kinds of fishes, etc.</p> - -<p>Neither glue nor gelatine exists ready formed in the animal -organism, except under abnormal conditions as a -phenomenon of disease, but they are the products of various<span class="pagenum" id="Page_2">2</span> -transformations. The first of these transformations evidently -takes place in drying the hide, since the result of -boiling to glue a green hide prepared in the usual manner -by liming, etc., but not previously dried, will be an entirely -different product of less consistency than that obtained by -drying the hide after liming and then boiling. A second -transformation seems to take place in boiling the material, -and a third in drying the jelly obtained, and this may explain -the fact that the latter, which is not converted into -actual glue, differs in its behavior from glue solution. The -series of transformation does not end even with the actual -glue, for it is a well-known fact that glue dissolved in water -and boiled for some time does not gelatinize on cooling, but -remains liquid. We have here to deal with organic combinations -which are distinguished from the more solid -organic compounds by passing more readily into decomposition. -However, it is an established fact that glue is an -organic combination presenting itself in different modifications. -In the animal organism it occurs ready formed only -under abnormal conditions as a phenomenon of disease, and -hence it is only produced by first drying and then by continued -boiling of the glue-yielding substance, and finally -by evaporating and further drying the gelatinous mass obtained -by boiling.</p> - - -<h4>2. TRANSITION STAGES OF GLUE.</h4> - -<p>We therefore distinguish:</p> - -<p><i>a.</i> Glue-yielding substance.</p> - -<p><i>b.</i> Crude glue.</p> - -<p><i>c.</i> Jelly.</p> - -<p><i>d.</i> Glue.</p> - -<p><i>a.</i> The glue-yielding substance of the animal body is -produced from proteïne substances, albumen, fibrine and -caseïne, in a manner similar to that in which new substances -are formed in the ripening fruit by the transformation and -disintegration into constituent parts of others previously -present.</p> - -<p><span class="pagenum" id="Page_3">3</span></p> - -<p><i>b.</i> By <em>crude glue</em> are understood glue-yielding materials -free from all foreign matter and physically prepared by -drying. It forms an intermediate link between glue-yielding -substance and jelly.</p> - -<p>This distinction between glue-yielding substance and -crude glue is justified by experience. If, for instance, fresh -calves’ heads, such as the tanner cuts off after swelling the -skins, be carefully limed and then boiled without previous -drying, the result will be a turbid liquor containing, though -everything be dissolved, no jelly whatever, or at least, very -little.</p> - -<p><i>c.</i> <em>Jelly</em> is obtained by boiling the crude glue. Its adhesive -power is far less than that of solution of finished glue, -and it will become more quickly putrid than the latter.</p> - -<p><i>d.</i> The finished product <em>glue</em> is, in most cases, not a definite -chemical compound, but a mixture of substances, with -two of which scientific research has made us thoroughly -acquainted.</p> - - -<h4>3. CONSTITUTION OF GLUE.</h4> - -<p>Independent of impurities and accidental constituents, -glue consists of two distinctly distinguishable combinations, -namely, <em>glutin or gelatin</em> and <em>chondrin</em>, the former being -formed from the hide and osseous parts, and the latter from -young bones while still in a soft state, and the “permanent” -cartilages, such as those of the ribs and joints.</p> - -<p>The manufacturer has it, of course, in his power to allow -either of these substances to predominate in his product, -but since experiments have shown glutin or gelatin to -possess much greater adhesive power than chondrin, it is -advisable to separate as much as possible the cartilaginous -matter from other glue-yielding material.</p> - -<p>As an accurate knowledge of these constituents of glue is -of great importance to the manufacturer, brief reference will -here be made to what scientific research has made known -to us in regard to them.</p> - -<p><span class="pagenum" id="Page_4">4</span></p> - -<p>Pure glutin or gelatin is obtained by treating buckshorn, -etc., with water containing hydrochloric acid, until the -phosphate of lime which serves, so to say, as a frame for the -glue-yielding substance, is dissolved, and the organic tissue -called <em>collagen</em> or <em>ossein</em>, remains behind. After freeing the -latter from fat by steeping in milk of lime and careful washing, -it is boiled, and the resulting jelly, when cold, mechanically -distributed in cold water, in which it softens but does -not dissolve. By thoroughly stirring the mass the glutin -yields its coloring matter to the water, the latter being replaced -by fresh water until all the coloring matter is extracted. -Then pour off the water and after dissolving the -jelly in hot water, filter the solution through a cloth. By -mixing the filtered solution with an equal volume of alcohol, -a precipitate of pure glutin is obtained. By the precipitation -with alcohol, the separating glutin carries down inorganic -salts, especially phosphates, which may be present in -the solution. To free it from them, dissolve it in a small -quantity of lukewarm water, acidulate the solution with -hydrochloric acid and bring it into a dialyser. The salts -and the acids diffuse in the water which has from time to -time to be renewed, and finally a jelly of pure glutin remains -behind; this is evaporated to dryness in shallow -vessels.</p> - -<p>Pure glutin, in a dry state forms a glassy substance, -almost colorless, transparent to translucent, brittle or -slightly elastic, free from odor and taste, and remains unchanged -in the air. Its specific gravity is greater than -that of water. It is neutral, exerts no influence whatever -upon vegetable colors and is insoluble in alcohol, ether, -hydrocarbons or oils. In cold water it swells up, absorbing -as much as 40 per cent., and becomes opaque, but does not -dissolve. It dissolves in hot water and on cooling forms a -jelly even if the solution contains only 1 per cent. of glutin. -It gelatinizes at a lower temperature than chondrin.</p> - -<p>An aqueous solution of glutin is precipitated by chlorine,<span class="pagenum" id="Page_5">5</span> -platinic chloride, tannin and alcohol, but not by hydrochloric -acid, acetic acid, lead acetate, alum and ferric sulphate. -Concentrated sulphuric acid decomposes glutin, -forming, besides other products of decomposition, chiefly -glycocoll and leucine.</p> - -<p>When heated, glutin softens, swells and diffuses an odor -of burnt hartshorn. In the air, it takes fire with difficulty, -smokes, flames only for a few minutes, and leaves a bulky -charcoal difficult to incinerate, the ashes of which consist -principally of calcium phosphate.</p> - -<p>Glutin, when in the jellied state, and treated with -alcohol, undergoes dehydration, under the influence of -which it contracts greatly. It was by this means that -Gonnor succeeded in reducing in a remarkable degree the -size of a print obtained in a very hydrated film of glutin, -and transferring it, so reduced, to stone, from which he obtained -a new impression, quite similar to the first, but more -or less diminished.</p> - -<p>By taking these prints, on the contrary, with glutin very -little hydrated, and afterwards steeping them in water, a -dilatation of the plate is obtained, which enlarges the figures -with the same regularity.</p> - -<p>Pure <em>chondrin</em> is prepared by boiling for from 24 to 48 -hours the cartilages of the ribs, of the larynx with the exception -of those of the epiglot, or of the windpipe and the -bronchi.</p> - -<p>Chondrin is precipitated from its solution by alcohol. -The precipitate is redissolved in warm water, evaporated, -and dried. It forms a semi-translucent mass of a slightly -yellow color and resembles glutin as regards fracture and -all external properties, but differs from it in being precipitated -from its aqueous solution by mineral acids, acetate of -lead, alum and ferric sulphate, and also by organic acids -such as vinegar, citric and oxalic acids, none of which precipitate -glutin.</p> - -<p>As regards its chemical composition, chondrin is poorer<span class="pagenum" id="Page_6">6</span> -in nitrogen than glutin, and contains more sulphur. Its -formula approaches more closely that of albumen, which -corresponds also with the origin of chondrin, for cartilages -may be considered as transition-links between the proteïne -and glue-yielding substances.</p> - -<p>By the action of concentrated sulphuric acid upon -chondrin, leucine is only produced but no glycocoll. By -potassium hydrate chondrin is converted into glutin and -yields then, like the latter, leucine and glycocoll. By boiling -with concentrated hydrochloric acid chondrin is decomposed; -a peculiar variety of fermentable sugar, to which -the term chondroglucose has been applied, being formed.</p> - -<p>It may finally be remarked that chondrin possesses less -adhesive power than glutin and its presence in glue may -be considered detrimental. To avoid its formation, the glue -manufacturer should separate as much as possible cartilages -from bones. Chondrin, however, is useful for size.</p> - - -<h4>4. PROPERTIES OF GLUE AND ITS BEHAVIOR TOWARDS OTHER -SUBSTANCES.</h4> - -<p>The product designated by the general term glue, is -always a mixture of glutin, chondrin and other substances -not yet accurately determined. Glue is formed by evaporating -and further drying the jelly, and its properties depend -on the crude glue and glue-yielding material used for the -production of the jelly.</p> - -<p>It may here be remarked that even if the quantity of -glutin contained in the different products could not be determined -by scientific means, the glue obtained from various -materials can be readily distinguished by external characteristics. -Every manufacturer knows that hides and bones -yield a distinct quality of glue as regards adhesive power, -elasticity and fracture, and that the jelly from glue-yielding -substances of older animals is more solid and gives a larger -yield than that obtained from the tissues of younger and -weaker animals. Glue from the bladders and scales of<span class="pagenum" id="Page_7">7</span> -fishes, though consisting mainly of glutin, differs materially -from hide or bone glue.</p> - -<p>Generally speaking, the jelly, no matter whether consisting -of glutin or chondrin, possesses, before drying to glue, -different properties from glue solution. It has less adhesive -power and spoils more quickly. At a temperature of 68° -to 72.5° F., jelly putrefies inside of 24 hours, smells of -ammonia, and decomposes, while glue solution can be kept -much longer without suffering deterioration.</p> - -<p>The jelly absorbs ozone with avidity and is decomposed -by it, this being the reason why an approaching thunderstorm -may cause great damage by destroying the coagulating -power of the glue liquors, or causing the glue to turn -on the nets, <i>i. e.</i>, to lose its consistency and become liquid -and foul.</p> - -<p>The behavior of glue solution towards different salts also -deserves attention.</p> - -<p>By adding potassium or sodium carbonate, neutral potassium -tartrate, Rochelle or Epsom salts to a lukewarm fluid -containing 15 to 20 per cent. of glue, the latter coagulates -by the salt withdrawing the water from it. A lukewarm -solution saturated with common salt, sal ammoniac, saltpetre, -or barium chloride does not gelatinize.</p> - -<p>By adding to glue solution a large quantity of alum, the -glue is precipitated as a transparent mass.</p> - -<p>Glue compounded at a high temperature with dilute -acids, does not gelatinize by itself, but will do so on adding -common salt.</p> - -<p>Boiling with slaked lime deprives glue solution of its -power of gelatinizing, and, on evaporation, changes it into -a colorless gummy mass which is soluble in cold water and -in saturated solution of common salt.</p> - -<p>From a glutin solution compounded with oxalic acid, the -latter can after some time be again separated by the addition -of lime, the result being a non-gelatinizing fluid which, -however, possesses great adhesive power. This is the so-called -<em>meta-gelatin</em>.</p> - -<p><span class="pagenum" id="Page_8">8</span></p> - -<p>Glue solution also loses its property of gelatinizing by repeated -boiling and cooling (for about six days).</p> - -<p>Tannin enters with the jelly, as well as with glue solution, -into characteristic combinations which are formed even -in solutions containing only 0.005 per cent. of jelly or glue. -Glue is, therefore, an excellent agent for the detection of -tannin.</p> - -<p>When quite concentrated glue solution is treated with -tannin, a heavy, flocculent precipitate of a dirty-yellow, -caseous character is formed, which turns brown on exposure -to the air and, after drying, constitutes a hard brittle -mass, easily reduced to powder and soluble in hot potash -lye, but insoluble in water, ether and alcohol. This precipitate, -if not identical with, is closely allied to the combination -of tannin with skin, called leather.</p> - -<p>Glue exposed to a dry heat melts, diffuses a strong disagreeable -odor of burned horn and leaves behind a charcoal -which has a powerful discoloring effect like animal charcoal. -When subjected to destructive distillation, glue yields -an aqueous solution of ammonium carbonate and a thick -brown oil consisting of a mixture of ammonium carbonate, -sulphur, ammonium cyanide, etc.</p> - -<p>The chemical composition of glue is such as to bring to -mind that of starch and cellulose derived from the vegetable -kingdom. It contains:</p> - -<p> -Carbon 49.1 per cent.<br /> -Hydrogen 6.5 per cent.<br /> -Nitrogen 18.3 per cent.<br /> -Oxygen and sulphur 26.1 per cent.<br /> -</p> - -<p>which may be represented by the formula: C<sub>12</sub>H<sub>10</sub>N<sub>2</sub>O<sub>4</sub>.</p> - -<p>The composition of glue differs but little from that of the -glue-yielding substance. Isinglass is composed of:</p> - -<p> -Carbon 49.5 per cent.<br /> -Hydrogen 6.9 per cent.<br /> -Nitrogen 18.8 per cent.<br /> -Oxygen 24.8 per cent.<br /> -</p> - -<p><span class="pagenum" id="Page_9">9</span></p> - -<p>This justifies the assumption that glue in its various -transition stages does not represent different chemical combinations, -but only modifications of one and the same combination -distinguishable from each other by physical -characteristics, as is the case with starch, which without -suffering an alteration in its composition, appears as dextrine -and grape-sugar, or as with cellulose, which, without -altering its composition, can be transformed into amyloid -and grape-sugar.</p> - -<hr class="chap" /> - -<p><span class="pagenum" id="Page_10">10</span></p> - - - - -<div class="chapter"></div> -<h3><a name="CHAPTER_II" id="CHAPTER_II">CHAPTER II.</a><br /> - -<small>USES OF GLUE.</small></h3> - - -<p>An inquiry into the various technical uses of glue must -be of interest to the manufacturer so as to enable him, -when acting, as is frequently the case, as salesman, to know -to whom to offer his product; and also to learn what special -demands he has to satisfy, as not every glue is adapted to -every purpose, different qualities being required for special -uses.</p> - -<p><i>Glue as a joining medium.</i> In Chapter I, treating of the -nature of glue, special attention has been drawn to the fact, -that the adhesive power of glutin is greater than that of -chondrin; and that glutin obtained from skin and tendons -possesses still greater adhesive power than the product from -bones. This is the reason why good sound glue made from -scraps of skin is preferred by those artisans who may be -considered the principal consumers, such as cabinet-makers, -carpenters, turners, instrument-makers, wood-carvers, carriage-builders, -brush-manufacturers, bookbinders, paper-manufacturers, -etc., all of them requiring glue of the greatest -possible adhesive power. It must, however, by no -means be understood that a good quality of bone glue cannot -be used for the same purposes; because much bone -glue of excellent quality and at a low price is brought into -the market by manufacturers of animal charcoal and bone -meal, and is used in glueing wood, etc.</p> - -<p>Glue suitable as a joining medium for the above purposes -should be of an amber or brown-yellow color, transparent -or translucent, clear, dry and hard, and show a glassy fracture -which should not be brittle, but somewhat elastic.<span class="pagenum" id="Page_11">11</span> -Placed in cold water it should swell up and absorb as much -of it as possible without actually dissolving, even if it remains -there for 48 hours. The supernatant water should -be free from a putrid odor and contain but a small quantity -of foreign substances in solution. Such glue passes into -solution at 122° F., and dissolves entirely on heating to -144.5° F. Heating to a higher temperature should be -avoided.</p> - -<p><i>Glue as a binding agent.</i> Glue solution is used for bind-together -pulverulent substances, such as mineral colors in -the manufacture of colored paper and paper-hangings, in -painting in distemper, in the size of the gilder; or it is -mixed with plaster of Paris or chalk for the manufacture of -plastic masses which become hard on drying, such as -stucco-work, papier-maché, etc. Generally speaking, it is -best to use only good sound glue for these purposes, though -it may sometimes be possible to utilize defective and cheap -qualities without injurious consequences. For color mixtures, -the glue should at all events be free from acids and -alkalies, as they exert a decomposing and altering effect -upon the colors. The gilder should always use the best -quality of glue, as otherwise the work he applies later on to -the size will spoil.</p> - -<p>A very large quantity of glue is consumed <i>in the manufacture -of matches</i>, and much depends on its quality and -drying properties. The dipping composition for matches -containing phosphorus is a bath of glue of 25 to 50 per -cent. strength to which the requisite amount of an oxidizing -agent, like potassium nitrate or chlorate has been added, -kept at a temperature of 100.4° F. The phosphorus is -cautiously put in; it melts, and is stirred to an emulsion, -when the sand, glass or other friction-agent is incorporated. -The object of the glue is to protect from oxidation, -without diminishing the sensitiveness. Glue is also used -as the binding material in the heads and rubbers of safety -matches.</p> - -<p><span class="pagenum" id="Page_12">12</span></p> - -<p><i>Book binders</i> require for the better classes of work a glue -which should naturally be pale and strong, and without -marked odor. Some inferior glues which have been -chemically bleached turn almost black in the pot, owing to -the bleaching agent not having been properly removed or -neutralized.</p> - -<p>Sand, glass and emery papers and cloths are made by -coating the surface with a thin uniform layer of strong -glue, and sifting the powder evenly on.</p> - -<p><i>Glue in sizing.</i> The principal object of sizing goods is to -impart to them a certain degree of stiffness, to give them a -nice appearance and a good feel.</p> - -<p>As glue would injure the color of white goods, it cannot -be used for sizing them, but, on the other hand, much is -employed for preparing size for the use of hat and cloth -manufacturers, weavers, etc. Before the introduction of -the paper machine and invention of rosin glue, animal glue -was exclusively used for sizing paper, but at the present it -is only used for sizing paper manufactured from rags, and -for pasteboard, and also by manufacturers producing drawing -paper sized with animal substances. The paper, after -leaving the machine, is passed through a glue solution and -then dried in the air.</p> - -<p>For actual sizing purposes good and fine varieties of glue -are only used, or sometimes the manufacturers prepare their -own size by boiling to glue dried calves’ heads, or rabbit -skins deprived of their fur, scraps of parchment, etc. For -cheap woollen hats, glue is used in place of shellac. The -cloth manufacturer procures his glue mostly in the form of -a jelly. This variety of glue deserves special attention and -the mode of preparing it will be referred to later on.</p> - -<p><i>Glue for culinary and medicinal purposes.</i> The use of -glue for these purposes is based upon three properties:</p> - -<p>1: Upon its power of coagulating and inclosing while in -this state, substances mechanically dissolved and finely -divided in a fluid, which, being specifically as heavy as the<span class="pagenum" id="Page_13">13</span> -fluid itself, render the latter turbid and cannot be got rid -off by settling. The glue in this case acts as a clarifier.</p> - -<p>Large quantities of isinglass and gelatine, specially prepared -for the purpose, are used for clarifying and fining -beer, wine and other liquids, as well as for preparing -jellies. The material to be used for jellies and other culinary -purposes must, of course, be colorless and entirely free -from odor. Jellies are made palatable by flavoring with -spices, sugar, essences, etc., before congealing, A vegetable -gelatine, Agar-Agar, which will be referred to later on is -now brought from China, and being cheaper and perfectly -free from odor, has become quite a competitor with isinglass -and gelatine.</p> - -<p>Prior to the introduction of Liebig’s and other beef extracts, -bouillon tablets, consisting of a mixture of bone-jelly, -meat broth, extract of pot herbs and flour, were -largely used. One hundred and ten pounds of meat -repeatedly boiled yield five pounds of bouillon tablets. A -good meat broth, though not equal to that from Liebig’s or -other meat extracts, is obtained from these tablets by the -addition of thirty times their weight of water.</p> - -<p>If glue be dissolved in water, it gelatinizes at the ordinary -temperature, and if the solution be mixed with other -fluids, for instance, meat broth, fruit juices and essences, -which in the form of jelly are to serve as food, it effects -their solidification.</p> - -<p>Glue acts as a healing agent by preventing the access of -air to wounds. Court plaster is prepared from gelatine. -When cabinet-makers cut themselves, they apply glue to -the wound with the best success. In hospitals a compound -of gelatine and glycerine is used as the best means -of closing wounds, the same compound having also been -successfully used for preserving articles of food such as -eggs, fruit, and even meat.</p> - -<p>Every good quality of glue can be used for the above -purposes.</p> - -<p><span class="pagenum" id="Page_14">14</span></p> - -<p>Medicines of a disagreeable taste are frequently inclosed -in gelatine capsules, so that they can be taken without -causing inconvenience to the patient. The use of these -capsules has grown to such an extent as to form a special -branch of industry. The mode of manufacturing them -will be described later on.</p> - -<p><i>Glue for elastic masses and as a partial substitute for rubber.</i> -Glue mixed with glycerine forms an elastic mass resembling -rubber. The same effect can be produced by an -addition of molasses. This elastic mass, the preparation of -which will be described later on, is of great importance for -the manufacture of printers’ rollers, for moulds, etc. Some -manufacturers prepare the mass ready for use, so that the -printer or lithographer need only remelt it, and cast it in a -mould.</p> - -<p>Glue is of great importance in photolithography as, mixed -with chromium salts, it is the only known means of transferring -a photographic negative to the stone. In photography, -gelatine is used for negative pictures upon glass. -For the manufacturer of casts of plaster of Paris or cement, -this glue mass, which is generally used without an addition -of glycerine, is indispensable for making moulds which are -much undercut.</p> - -<p>Glue mixed with glycerine may be used as a substitute -for rubber in manufacturing elastic toys, such as dolls’ -heads, animals, etc. For these purposes it is advisable to -select glue which forms a very solid jelly, even if it possesses -but little adhesive power, pure bone-glue being the -best.</p> - -<p>Glue mixed with glycerine (1 part glue, 1 part glycerine) -is used as hectograph mass for the transfer of matter written -with concentrated solution of aniline color.</p> - -<p><i>Glue for fancy articles.</i> Great progress has been made in -the use of glue and gelatine in the manufacture of fancy -articles.</p> - -<p>The best known of all these products are perhaps the<span class="pagenum" id="Page_15">15</span> -gelatine foils. They form thin, transparent sheets, brilliantly -colored, and are used for printing sacred images, -visiting cards, labels, etc.</p> - -<p>Gelatine veneers were first shown at one of the Paris International -Exhibitions. They consist of sheets varying in -thickness, which have been deprived of their translucency -by an admixture of colors in imitation of various crystallization -of salts, and such stones as lazulite, malachite and -avanturine. Glue imitations of mother of pearl, tortoise -shell, and ivory were shown which closely resembled the -genuine articles. These veneers have been largely introduced -in the manufacture of fancy articles, cabinet ware, -buttons, etc. The most brilliant use to which they have -been put is in the manufacture of fans, for which ivory and -tortoise shell were formerly used, and there are perhaps few -ladies that are aware that these glittering toys are manufactured -from horse bones from the knacker’s yard.</p> - -<p>The successful introduction of gelatine veneers was soon -followed by a substitute for horn in general, and combs, -buttons, snuff-boxes, and hundreds of other fancy articles -have been manufactured from these imitations.</p> - -<p>In the foregoing statement only some of the principal -uses of glue have been enumerated, and there can be no -doubt that with an increase in the knowledge of its nature -and properties, a wide field is still open for progress in this -industry.</p> - -<hr class="chap" /> - -<p><span class="pagenum" id="Page_16">16</span></p> - - - - -<div class="chapter"></div> -<h3><a name="CHAPTER_III" id="CHAPTER_III">CHAPTER III.</a><br /> - -<small>RAW MATERIALS AND THEIR PREPARATION FOR THE -MANUFACTURE OF GLUE.</small></h3> - - -<p>The raw materials used for the manufacture of glue consist -of a variety of animal offal. The principal substances -employed are refuse from tanyards, such as scraps of ox -and other thick hides, the waste of the workshops of leather -dressers, morocco leather manufacturers, etc. The tendons -and intestines of many animals, rabbit and hare skins deprived -of their fur, cat and dog skins, scraps of parchment, -waste of turners and button makers, and offal from butcher -shops and households, help to swell the series of materials -used for the manufacture of glue.</p> - -<p>The materials are collected and sold either directly to the -glue boiler, or to dealers making a specialty of glue stock.</p> - -<p>As a thorough knowledge of these waste products is of -importance to the manufacturer, this chapter will be devoted -to their detailed description, the success of the enterprise -depending largely on the selection of the raw materials and -their careful sorting and preparation. By bearing in mind -the varied products—from the most ordinary black glue to -the colorless glassy gelatine for photographic and culinary -purposes—it will be understood that entirely different raw -materials have to be employed for the finer products than -for the ordinary qualities of glue.</p> - -<p>According to their derivation the raw materials may be -divided into three groups, namely:</p> - -<p>1. Skin-like raw materials: Skin, leather, tissues.</p> - -<p>2. Bone raw materials.</p> - -<p>3. Materials obtained from fishes: Air bladders, scales, etc.</p> - -<p><span class="pagenum" id="Page_17">17</span></p> - - -<h4>1. ANIMAL SKIN.</h4> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 1.</span></div> -<img src="images/i_p017.jpg" alt="" /> -</div> - -<p>This consists of three layers, namely: 1. The thin upper-skin—the -epidermis—which consists only of cellular tissue, -and is of no special importance for the manufacture of glue. -2. The actual leather-skin, or corium, which consists of -fibres of connective tissue and forms the actual object of the -tanner as well as of the glue boiler. Underneath the -corium lies the under-skin, which consists only of cellular -tissue contaminated with particles of flesh and fat, which -are detrimental to the manufacture of glue. Fig. 1 represents -a section of the animal skin. <i>O</i>, is the epidermis, <i>L</i>, -the corium, <i>U</i>, the under-skin. The epidermis consists of -two layers. The first, superficial one, <i>H</i>, is known as the -cuticle or lamellar layer, and the other deeper layer, <i>S</i>, as the -mucous or malpighian layer. The corium also consists of -two layers, the upper one <i>C</i>, and the lower one <i>C<sub>1</sub></i>, which is -the actual leather-skin. The under-skin, <i>U</i>, is an elastic<span class="pagenum" id="Page_18">18</span> -tissue containing many deposits of fat, <i>F</i>, and perspiratory -glands, <i>D</i>, which are connected with ducts, <i>D<sub>1</sub></i>, with the -surface of the skin.</p> - -<p>For the manufacturer of leather and glue, the corium is -the only material of value.</p> - -<p>The tanner trims the skins before steeping them in the -ooze. From sheep and calf skins he removes the head portions, -it being more advantageous to use them for glue -stock. He also cuts off the skin covering the lower part of -the thighs, and, to give the skin a neat finish, the ragged -edges of the belly part. Of bullock hides, the ears, tails -and foot pieces are utilized for glue stock, while the head -parts are tanned. Such tannery waste may yield 44 to 46 -per cent. of glue. Scarf skin of bullocks’ hides and waste -in fleshing the hide, tendons and hinder parts of cattle -yield from 30 to 35 per cent.; horse sinews from 15 to 18 -per cent.</p> - -<p>Scraps of parchment and bullocks’ feet are highly valued -as glue stock, since they are in fit condition for boiling -without further preparation. They may yield up to 62 per -cent. of their weight in glue.</p> - -<p>Calf and sheep skins yield a superior glue; that from -horse hides is usually dark and poor in quality, although -with careful working a strong product can be obtained from -the latter.</p> - -<p>Of great value to the glue boiler are the so-called calves’ -heads, which, after liming and drying, form a special article -of commerce.</p> - -<p>Skins of hogs, hares and rabbits yield a light-colored glue -of little consistency. It is, therefore, best to use these last-named -raw materials for the preparation of jelly, such as is -used in sizing, in the manufacture of paper, etc.</p> - -<p>The older the animals from which the skins have been -derived, the more solid the glue will be. In many cases, -especially where a certain quality of glue is to be produced, -it may be recommended to separate the different kinds of<span class="pagenum" id="Page_19">19</span> -skin refuse into lots, provided there is enough of each kind -to boil it separately.</p> - -<p>A considerable number of skins used for packing various -articles, such as indigo from South Africa, have been so -much damaged in transit as to render them useless for tanning, -but they form good material for glue, frequently -yielding 50 to 55 per cent.</p> - -<p>In reference to judging glue stock some valuable notes -are given in an article on glue, published by the American -Provision Co., Chicago, Ills.:</p> - -<p>“Dry, uncured or salted stock, such as raw hide or South -American, if soaked for twelve hours in cold water, gains -about 50 per cent. in weight, and still remains tough, and -the water sweet. The moisture, dirt, and salt should not -be over 10 per cent.</p> - -<p>“Green salted stock, such as hide pieces, sinews, calf -heads and pates, should have no excess of salt, nor be foul, -discolored or heated; should be tough, with the hair not -loose, and have a mild animal odor. Moisture and salt not -over 40 per cent.</p> - -<p>“Dry limed stock soaked twelve hours develops a characteristic -odor, and should be firm, fibrous, and have no -slimy pieces. The water should not be dark. Lime, sand -and dirt, not over 5 per cent.</p> - -<p>“Green limed stock should be smooth and soft, any remaining -hair being easily detachable, while the liquor -should be fairly clean, sweet, and not too alkaline.</p> - -<p>“A large quantity of waste bones accumulates in the -preparation of tinned provisions. If these have not been -overheated and are in good condition, a considerable -amount of glue can be obtained from them, the bones of -the head, ribs, and feet giving a better yield than those of -the thighs and legs.</p> - -<p>“Horn piths should not contain over 12 per cent. moisture, -and should not have been overheated in drying; they -should have been cleansed from skin and hair, which are -of little value to the glue-maker.</p> - -<p><span class="pagenum" id="Page_20">20</span></p> - -<p>“The age of the animals yielding glue stock has an important -influence on the product. While from younger -animals the product, as a rule, is of lighter color, more -abundant and more easily obtained, it contains more -chondrin, so that from solutions of equal strengths, those -from mature animals will be found to be of greater consistence -and the glue more solid.</p> - -<p>“Abroad, dry hides are often, for weighing, soaked in -chlorbarium, a solution of barium chloride, and then in a -bath of dilute sulphuric acid, 1½ per cent., which readily -soaks in, combines with the barium to form the white insoluble -powder of barium sulphate, leaving weak hydrochloric -acid in the fibre, to be afterwards neutralized in -liming, the chloride of calcium dissolving out. This treatment -affects considerably the subsequent making of glue, -as, beside the effects of the acids, the sulphate of barium -will render the liquors cloudy and difficult to clarify. Of -course if colored glues are to be made this will be no detriment.”</p> - -<p>To prevent putrefaction, which is always accompanied by -decomposition of glue-yielding substance and consequent -loss, the scraps must be carefully preserved, especially in -summer.</p> - -<p>The tanner prepares the waste by liming, <i>i. e.</i>, steeping it -during fifteen to twenty days in milk of lime which is -frequently renewed. By the action of the lime, adhering -particles of blood and flesh are dissolved and the fatty -matter is saponified. After this treatment the glue-stock -is dried.</p> - -<p>In case this work is not done carefully in the tanyard, as -is only too frequently the case, the stock is of but little -value to the glue-boiler.</p> - -<p>By allowing the refuse to lie too long in a heap, as is -sometimes done, putrid fermentation sets in, the injurious -effects of which cannot be remedied by subsequent liming, -or the lime bath has not yet been strong enough, or has not<span class="pagenum" id="Page_21">21</span> -acted sufficiently long upon the scraps to destroy the adhering -particles of blood and flesh. The lime bath, on the -other hand, may have been too strong, so as to attack the -glue-yielding substance. Frequently it is also the case that -the scraps having been dried under unfavorable circumstances, -mould has commenced to form, and finally they -may be spoiled in winter by allowing them to freeze. -Frozen glue leather yields glue of very little consistency.</p> - -<p>It will be seen from the foregoing that great precaution -and care are required when buying glue leather. The -manufacturer should especially see that it is dry and tough, -free from mould and all organic and inorganic substances, -and not too strongly limed.</p> - -<p>The glue-boiler should, in all cases, be prepared to undertake -the preparation of the glue stock himself. The following -arrangements are required for the purpose:</p> - -<p>Let us assume that the glue factory is located on a stream -of water. In the immediate neighborhood of the stream a -sufficient number of pits to prepare all the glue stock used, -each about 6½ feet deep and 6½ to 10 feet in diameter, and -lined with cement, are so arranged that their bottoms are -about 3 to 3½ feet above the level of the water. They are -supplied with water by means of a pipe line connecting one -with the other. Each pit is provided with a discharge pipe -to draw off the dirty water.</p> - -<p>As the glue-stock, before undergoing other operations, -has to be freed from the lime by washing with water, the -simplest plan is to place the limed stock in nets or wicker -baskets suspended in running water by means of a traveling -crane or other contrivance erected on the bank of the -stream. This elementary method, however, is open to several -disadvantages, as it fouls a large volume of water and -may lead to legal interference, and its very simplicity is apt -to lead to neglect of precautions, such as brushing away -solid particles of lime or softened animal matters. Further, -the great quantities of water carry off small pieces of glue<span class="pagenum" id="Page_22">22</span>-stock -and fat, if catch-basins are not provided sufficiently -large to allow fat, glue-stock, hair and lime to separate -from the water.</p> - -<p>The object is better accomplished and in a shorter time -by the use of a washing drum. This consists of a perforated -iron cylinder about 6 feet in diameter and 4 feet in length, -and open on both ends. Around the inside of the cylinder -are fixed a number of wooden shelves 6 inches broad, -which, as the cylinder revolves, carry the glue-stock partly -round, ultimately falling to the bottom again, the movement -dashing it about under a spray of water. In the -cylinder is also arranged an iron plate supported by stays -from the outside. While the washing is in operation the -plate is turned perpendicular; on completion it is brought -to a horizontal position, forming a table, on which the glue-stock -falls, and the latter is then removed to a hand-press -to squeeze out the water. The washed stock is then removed -to the drying ground, which should be in a sunny -and airy location, and provided with an inclined floor of -planks or cement so arranged as to allow of the admittance -of air from beneath.</p> - -<p>As it is well known that small quantities of liquid, frequently -renewed and thoroughly drained off each time, -effect the most complete and economical washing, and in -the shortest time, S. Rideal recommends the use of pits or -vats with proper arrangements for stirring, draining and -inspection. The lime scum from the pits can be used in -the manufacture of fertilizers.</p> - -<p>The glue-stock washer shown in Figs. 2 to 5, is the invention -of W. A. Hoeveler (American patent), and it relates -to the construction of apparatus for washing glue-stock.</p> - -<p>In apparatus for this purpose the stock is very commonly -damaged by being broken up too much, and considerable -loss results, besides, from the fact that the small particles -are allowed to escape with the wash-water. By the present -construction and arrangement these defects are remedied -and other advantages derived.</p> - -<p><span class="pagenum" id="Page_23">23</span></p> - -<p>Fig. 2 is a transverse vertical section on line x-x of Fig. 3 -of this apparatus;</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 2.</span></div> -<img src="images/i_p023-1.jpg" alt="" /> -</div> - -<p>Fig. 3 is a longitudinal vertical section of the same;</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 3.</span></div> -<img src="images/i_p023-2.jpg" alt="" /> -</div> - -<p>Fig. 4 is an enlarged plan illustrating the screen and -hinged covers, one being opened and one closed; and</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 4.</span></div> -<img src="images/i_p023-3.jpg" alt="" /> -</div> - -<p>Fig. 5 is a detail of the hub, stems and part of one paddle.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 5.</span></div> -<img src="images/i_p023-4.jpg" alt="" /> -</div> - -<p>The apparatus is constructed in the form of a rectangular -trough-like structure, with its sides and ends, <i>A</i>, substantially -water-tight by means of the double walls, <i>a a</i>. The -upper portion of the interior is occupied by the swinging<span class="pagenum" id="Page_24">24</span> -wash-box, <i>B</i>, semicircular in shape, with flat sides and -rounded bottom throughout, the bottom being perforated.</p> - -<p>Upon a transverse shaft, <i>c</i>, journaled at the axis of box, -<i>B</i>, is set a paddle-wheel composed of a suitable hub, <i>d</i>, and -adjustable paddles, each composed of the radial stem, <i>e</i>, and -the blade, <i>f</i>, or spoon. The spoons, <i>f</i> are set on the stems, -<i>e</i>, so as to be capable of being reversed or turned half-way -round, more or less. One side of the spoon, <i>f</i>, is rounded -off, so that while passing through the stock the latter will -not cling to or remain upon it. The other side of the spoon -is flat, but slightly skewed or bevelled, so that when turned -to face with the direction of motion of the wheel it not only -gathers up the stock and holds it till out of the box, <i>B</i>, but -upon further elevation causes it to roll or slide along the -paddle to a predetermined point, where it falls off gently -into a discharge-spout, <i>g</i>, which carries it off for further -treatment practically undamaged. During the operation -the box, <i>B</i>, and the body, <i>A</i>, are kept supplied by a stream -of clean or chemically-prepared water, and the wheel, <i>e f</i>, -revolves slowly in the box, the edges of the paddles sweeping -around, while the box, <i>B</i>, or its bottom, is kept oscillating, -thus preventing an injurious clogging of the perforations -in the box-bottom. After the stock is placed in the -box, <i>B</i>, and the latter filled with sufficient water, the wheel, -<i>e f</i>, is caused to slowly revolve (by motive or hand power), -with the rounded sides of the spoons, <i>f</i>, presented forward. -This operation thoroughly agitates and cleanses the stock, -while the rounded form of the spoons prevents the breaking -up of the natural condition of the stock. The inventor -gathers the finer particles as follows, after they have escaped -through the perforated bottom of the wash-box, <i>B</i>. At the -lower part of the trough, <i>A</i>, elevated on crossbars or blocks, -<i>h</i>, he places two parallel strips, <i>i</i>, and between these, which -are grooved to form ways, <i>k</i>, inside, is set a long screen, <i>l</i>, -placed on rollers, <i>m</i>, and movable thereby on the rails or -ways, <i>k</i>. To give movement to the screen, <i>l</i>, the inventor<span class="pagenum" id="Page_25">25</span> -attaches to its end a rod, <i>n</i>, which projects outwardly -through the walls, <i>a a</i>, by means of the packing-box, <i>p</i>, and -cap or door, <i>q</i>, which, when opened, allows the withdrawal -of the screen, <i>l</i>, and its burden. The shaking of the screen -is accomplished by a suitable motor applied to rod, <i>n</i>, and -is kept going during the operation as required. To the -strips, <i>i</i>, which are placed at a little distance from the side -walls, <i>a</i> (to leave a passage for the water and refuse to go -through), are hinged the two doors, <i>r</i>, which shut down -upon the rod, <i>s</i>, as a support, in which case nothing can -fall upon the screen, or which open up and rest against the -sides, <i>a a</i>, in which case the screen is exposed and the side -passages closed by the doors, <i>r</i>. During the initial or -rough-washing stage the doors, <i>r</i>, are kept closed, and the -dirty water and refuse pass freely down the side passages -and out at a suitable opening at the bottom. After this -stage it becomes desirable to catch the particles which get -detached from the stock in box, <i>B</i>, and come through the -perforations therein. Then open up the doors, <i>r</i>, thus closing -the side passages and compelling all the water and -small stock to go to the screen, <i>l</i>, which catches the remaining -stock. When sufficiently accumulated the screen may -be drawn out and the stock thereon removed. When the -main body of stock in box, <i>B</i>, has been cleansed, the paddles -or spoons, <i>f</i>, are reversed, so as to present their flat, -skewed faces to the stock, and in revolving the paddles now -gently lift the stock and discharge it into the spout or hopper, -<i>g</i>. The washing and removal of the stock when washed -are thus accomplished without further manipulation than -to reverse the paddles, which obviously could be done by a -reversing-gear on the motor, thereby reversing the direction -of movement of the paddle-wheel.</p> - -<p>Instead of the whole box <i>B</i> being oscillated back and -forth, its bottom may be set on slides or rollers and oscillated, -while the sides remain stationary.</p> - -<p>In the drawings the box <i>B</i> is shown as hung upon the<span class="pagenum" id="Page_26">26</span> -shaft <i>c</i> as a centre; but as the provision of means of reciprocating -or oscillating the box or its bottom is within the -skill of any machinist, it is not necessary to describe any -specific form. As the box with its contents will be very -heavy, the inventor prefers a special motor for it, which may -also be geared up to reciprocate the screen <i>l</i>.</p> - -<p>Instead of the door <i>q</i>, as located in Fig. 2, it can be -located as at <i>q’</i>, same figure.</p> - -<p>The entire plant must of course be arranged according -to sanitary regulations, especially as regards river pollution, -etc.</p> - -<p>The sheds for sorting and storing the glue-stock should, -if possible, be in close proximity to the pits and washing -drums, and be dry and airy. In arranging his plant, the -glue manufacturer must, in short, exercise his ingenuity -with a view to carrying on the business with as little loss of -material, and as much saving of time and labor as possible.</p> - -<p>The work in a factory arranged in the above manner, is -carried on as follows:</p> - -<p>The raw materials brought by the dealer are weighed, -and if in green state, the customary percentage—generally -50 per cent.—taken off. To facilitate future operations, -and to enable the manufacturer to produce different varieties -of glue, the dry materials are sorted and stored in different -compartments of the store-shed.</p> - -<p>Green waste, <i>i. e.</i>, such as has not been limed must be -taken in hand at once, as otherwise it would taint the air, -be attacked by rats and other animals, and suffer injurious -alterations by decomposition. The manner of operation is -as follows:</p> - -<p><i>Liming.</i> Prepare “milk of lime” by filling the pits, -which are to serve for the reception of the skin waste, with -the required quantity of water and dissolve in it 2 per cent. -of calcium hydrate obtained by slaking a good quality of -quick lime. Stir thoroughly, and in order that the water -may become thoroughly saturated with the lime, let the<span class="pagenum" id="Page_27">27</span> -liquor stand for 8 or 10 days before placing the waste in it. -The liquor should stand about 9 inches deep over the waste -in the pits. The length of time the waste has to remain in -the milk of lime varies according to the material; calf skins -requiring 15 to 20 days, sheep skins 20 to 30 days, and -heavy ox hides 30 to 40 days. The milk of lime should be -renewed once or twice a week, and thoroughly stirred.</p> - -<p>For the purpose of liming, the quality of the lime used -is of the utmost importance, the milk of lime being -frequently quite valueless by reason of having become carbonated -or a bad quality of quick lime having been originally -employed. It should be borne in mind that only the -hydrate of lime which is present in solution in lime water -is of use, whereas in milk of lime so much carbonate and -other impurities may be present that the liquid, though -thick, may be quite useless. The value of a lime should -always be tested by determining the amount of real calcium -hydroxide, Ca(OH)<sub>2</sub>, contained in it. The operation according -to S. Rideal, is conducted as follows: Water free from -carbonic acid is first prepared by boiling distilled water for -half an hour in a strong, round-bottomed Bohemian or Jena -flask. While steam is still issuing, the flask is removed for -an instant, closed by a well-fitting greased cork or a rubber -stopper, and allowed to cool. When the temperature has -somewhat fallen, the cooling may be cautiously accelerated -by dipping into a pail of warm water, then transferring to -the cold stream from a tap. The water may be preserved -in the flask or, preferably, a number of bottles with vase-lined -stoppers should be filled quite full and retained for -use.</p> - -<p>From the sample of lime, well mixed, a small portion -(about 0.25 gramme) should be accurately and rapidly -weighed, placed in a wide-mouthed, stoppered bottle holding -about 300 cubic centimeters, 250 Cc. of the boiled -water added, and then allowed to settle. The whole of the -calcium hydrate will now have dissolved. Fifty cubic<span class="pagenum" id="Page_28">28</span> -centimeters of the clear liquid should now be withdrawn -by a pipette, transferred to a flask, colored with an indicator—either -phenol-phthalein, methyl-orange, or litmus -may be used—and its alkalinity determined by running in -decinormal hydrochloric or sulphuric acid from a burette -till the change of color occurs. Each cubic centimeter of -the acid corresponds to 0.0028 gramme of calcium oxide, -or 0.0037 gramme of the hydrate, Ca(OH)<sub>2</sub>. The amount -by calculation will give the percentage of real lime present -in the sample. It is well to notice that any soda or potash -present will equally neutralize the acid, and be returned as -lime, but as these are of almost equal efficiency their -presence in <em>small quantity</em> has no disadvantage. For -special work it will be necessary to have a full analysis. -As a rule the product made from limestone, or “stone -lime,” is the best article in commerce, and is much more -free from stones and clay than “gray lime” or “shell -lime.” The best stone lime contains sometimes only ½ per -cent. of impurities, and seldom more than 5 per cent., while -inferior kinds of gray lime may contain as much as 50 per -cent., and would be of little use in glue-making.</p> - -<p>After removal from the lime pit, the material is placed -in willow baskets or nets, and immersed in the stream to -remove the greater portion of the lime, which is generally -effected in a few days. It is still more effectively accomplished -by placing the waste, after soaking in the willow -baskets, in the wash drums. After taking it from the -baskets or wash drums it is spread in the drying yard to -drain and dry, the desiccation being accelerated by turning -it over with a fork several times a day. While drying, the -quick-lime is converted into carbonate, the latter exerting -no disturbing effect in the manufacture of glue. When -sufficiently dried, the material is ready for boiling, and the -crude glue thus obtained can be stored for any length of -time, until wanted for further manipulation.</p> - -<p>In summer it is scarcely possible to cleanse the raw<span class="pagenum" id="Page_29">29</span> -material as rapidly as it is brought to the factory, and to -work it immediately without putrefaction setting in, and -for this reason it would frequently be risky to purchase -larger quantities of it, even if offered at very favorable -terms. During the colder season of the year, drying of the -cleansed raw material is such a slow operation, that in -order to prevent putrefaction, recourse would have to be -had to artificial heat.</p> - -<p>These drawbacks can, however, be overcome by the use -of carbolic acid, which possesses in a high degree the property -of preventing putrefaction. It is quite cheap, and as -but a comparatively small quantity of it is required, the -additional cost need scarcely be taken into consideration, -since the value of glue-stock annually destroyed by putrefaction -is considerably greater than the expense for carbolic -acid.</p> - -<p>The raw material is thoroughly cleansed, and while in a -moist state is gradually brought into a brick cistern or -large vat, carbolic acid solution being poured over each -layer, so that, when the cistern or vat is filled, it stands -about an inch or two deep over the material. The latter -may be left in this state until wanted.</p> - -<p>The carbolic acid solution is prepared by dissolving 2 lbs. -of carbolic acid in 1000 quarts of water; the fluid thus obtained -possessing a slight odor of smoke. The washed glue-stock -treated as above described with carbolic acid remains -absolutely unchanged, and when wanted needs only be -taken from the cistern and worked like fresh material.</p> - -<p>In plants having no running water at their disposal and -depending entirely on well water, and where the waste -water has to be discharged into rivers or creeks, water containing -carbolic acid should be used for all the washing -operations, a fluid containing 1 to 2 parts of carbolic acid -in 10,000 parts of water being sufficient for this purpose. -Such an addition of carbolic acid prevents the wash-water -from becoming foul.</p> - -<p><span class="pagenum" id="Page_30">30</span></p> - -<p>Carbolic acid has the tendency of hardening the glue-stock -and imparting its odor to the glue, and among other -antiseptics, formaldehyde and boric acid have been recommended -for the purpose of preventing putrefaction for a -reasonable time. Formaldehyde in weak solution (1 part -in 10,000 to 100,000 parts water) has been found beneficial. -In this small quantity it does not harden the stock nor -affect the subsequent boiling, as it is dissipated by the heat. -Boric acid and its preparations, notwithstanding their low -antiseptic power, are much in favor. A fluid containing 1 -part boric acid in 200 parts water will have to be used.</p> - -<p>The principal varieties of hides and leather for glue-stock -may be classed as follows:</p> - -<p>1. Bullock leather from old animals, highly limed, -mixed with rump pieces, also with horse leather, the latter -being thin, of a dark color and soft, and is of less value -than bullock leather, because it yields a dark glue. Fat -leather is bullock’s leather from fat, stall-fed cattle, and before -use has to be freed from fat (by means of benzine).</p> - -<p>2. Pieces of hide from the lower parts of the limbs of -cattle, not limed and with the hair; they form excellent -glue-stock, yielding a very adhesive glue.</p> - -<p>3. Worn-out hinges from weavers’ looms, consisting of -strongest untanned bullock’s hide. When treated with -lime they yield a very strong glue, but are worked with -difficulty.</p> - -<p>4. Whip leather. This is waste in the manufacture of -whips, and is derived from thick tawed bullock hide. It -yields an excellent, light-colored glue.</p> - -<p>5. Calf leather. Broad, thin, translucent strips, slightly -limed, yields glue of a very light color.</p> - -<p>6. Calves’ heads. The skin of calves’ heads, limed, without -hair. They constitute the best material for gelatine, -and form a special article of commerce.</p> - -<p>7. Calves’ feet. The skin from the last but one leg-joint -which is cut off from dry, unlimed, haired skins. It is the -best material next to calves’ heads.</p> - -<p><span class="pagenum" id="Page_31">31</span></p> - -<p>8. Knapsack leather. Old knapsacks of calf skin and -waste in the manufacture of new ones, tawed with the hair -on with alum and common salt. When suitably washed -this yields good glue-stock. The alum and common salt -have to be completely removed by washing. The hair is -no detriment to the process of boiling, it serving as a filter -for the glue running off. To this class belong also all -kinds of fur waste, especially remnants of old fur coats -(sheep skin coats), from which the wool is removed and the -skin used as glue-stock. All these materials having been -treated with alum and common salt have to be freed from -them by suitable manipulation.</p> - -<p>9. Hare and rabbit skins freed from their fur. They -yield a light-colored glue of little consistency.</p> - -<p>10. Cut rabbit skins. In depriving these skins of their -fur, they are cut by a machine into fine threads of even -size. In France they are worked into size for gilders’ use -which is highly valued.</p> - -<p>11. Sheep and lamb leather (goat leather) limed, thin -and very light, yields but a small quantity of glue of little -consistency. To this class belongs the waste in the manufacture -of kid gloves. Waste of morocco and other varieties -of similar leather, pressed into bales and secured with wire, -comes into commerce under the name of Levant leather.</p> - -<p>12. Waste obtained in paring kid leather and in the -manufacture of gloves. It constitutes a flocculent powder -and yields very thin glue liquor with slight adhesive power. -Before boiling, the substances used in tanning must be completely -removed by washing.</p> - -<p>13. Surrons. These are untanned, unlimed skins of various -wild animals (antelopes, gazelles) which have been -used for packing leaf tobacco and various drugs. They -form good glue stock.</p> - - -<h4>2. BONES AND CARTILAGES.</h4> - -<p>In addition to hides, bones are a material highly valued<span class="pagenum" id="Page_32">32</span> -by the glue boiler. Chemically speaking, the framework -supporting the fleshy tissues of the animal order, and which -we call bones, is a combination of phosphates of lime and -magnesia, carbonate of lime, and alkaline salts, united with -fatty and cartilaginous matter. To the latter we look for -our yield of glue; to the fatty matter for the fat, and to the -phosphates for the basis of fertilizers.</p> - -<p>Bone cartilage is composed of carbon, hydrogen, oxygen -and nitrogen, the percentage composition being practically -constant, whether the cartilage be from an old or a young -animal. The bones of the young are, however, much -richer in cartilage than those of the old. This is reversed -in the case of the inorganic or mineral matter, the old having -the greatest yield of phosphates.</p> - -<p>Then again, the fatty matters are more in evidence in -full-grown animals than in youth or age; also in the thigh -and leg bones the yield is higher than in the heads, ribs or -shoulder blades, the latter averaging 12 to 13 per cent., -whilst the former runs 18 to 19 per cent.<a name="FNanchor_1_1" id="FNanchor_1_1"></a><a href="#Footnote_1_1" class="fnanchor">[1]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_1_1" id="Footnote_1_1"></a><a href="#FNanchor_1_1"><span class="label">[1]</span></a> Bone Products and Manures. By Thomas Lambert. London, 1901.</p></div> - -<p>Bones being less subject to putrefaction than skin-stock, -they are not brought into commerce in a prepared state. -They are mainly bought by contract from various dealers -within easy access to the works. The rates are generally -fixed for a certain period, and cover all classes of common -bones, whether fresh butchers’ or a mixture with partly -boiled bones. Bones differ considerably in their value. A -fresh bone will yield the highest percentage of fat and glue. -On the other hand, partly boiled bones may contain only 6 -per cent. fat with 30 per cent. water. In buying bones the -manufacturer should exercise great care, as the dealer -sometimes finds ways and means of including hoofs, horns, -iron, beefy matter, and even pieces of brick. Naturally -they form weight, but, excepting the horns, have no value.</p> - -<p>To separate the different classes of bone coming into the<span class="pagenum" id="Page_33">33</span> -works, and arrange them according to the amounts they -would produce of fat and glue, is no doubt a desirable -object, but in practice it is seldom carried out. However, -if the manufacturer wishes to undertake this tedious work, -it is recommended to make the following distinctions:</p> - -<p>1. Bones of young animals, sheep, calves, dogs, cats, etc., -being readily disintegrated, are thrown into one pile, and -also the light bones of oxen, such as skull bones, shoulder -bones, the vertebra of the tail, etc.</p> - -<p>2. A second pile is made of the foot bones of goats, sheep -and cattle, provided they can be had, as is the case in the -United States and England, in sufficiently large quantities.</p> - -<p>3. Scraps and shavings from bucks’-horn from turners -and button-makers.</p> - -<p>4. Thick bones of oxen, horses, etc., which must remain -longer in the lime-bath, together with waste of hard bones -from turners.</p> - -<p>5. Where large quantities of bones are handled it is advisable -to sort out the bones of the upper thigh, as they can -be more advantageously used for the manufacture of piano-keys, -handles for tooth-brushes, etc. Hoofs, which are -frequently found, should be thrown out, as they yield no -glue and can be utilized for other purposes.</p> - -<p>The further manipulation of the bones for the manufacture -of glue requires first of all their crushing or grinding -in a stamper or mill. By this crushing or grinding of the -bones two objects are attained, namely, they are more -readily deprived of their fat and present more points of -attack to the corrosive agents to be used later on. The -crushed bones are put in a large boiler, and for a few hours -subjected to the action of steam. Leg bones, as well as -horns, should not be boiled, as they contain no fat, and -would lose too much glue-yielding substance. After boiling, -the bones are placed in a lime vat for 8 to 14 days. -The water used for boiling the first portion of bones may -be used for a second one.</p> - -<p><span class="pagenum" id="Page_34">34</span></p> - -<p>The extracted fat amounting to 4 or 5 per cent. of the -quantity of bones used, is taken off the surface of the cold -liquor and the latter may be utilized as a fertilizer, or fed -to cattle.</p> - -<p>For crushing the bones, a stamping mill is generally used, -it yielding, when properly constructed, material for the -manufacture of glue, as well as granulated bones which -form an excellent product for the preparation of animal -charcoal.</p> - -<p>Since animal charcoal in pieces of quite even size is now -in general demand, it is recommended to manipulate the -bones in the above-described manner, to sell the granules to -the manufacturer of animal charcoal, and use for boiling -glue only the completely-crushed portions and the porous -bones which are not at all suitable for the manufacture of -animal charcoal.</p> - -<div class="figcenter" > -<div class="caption"> <span class="smcap">Fig. 6.</span></div> -<img src="images/i_p034.jpg" alt="" /> -</div> - -<p>Fig. 6 shows a stamping mill very suitable for the crushing -of bones, the illustration showing the mill open on the -left side and closed on the right. It is furnished with 16 -stamps, <i>D</i>, each stamp being provided with a cast-iron shoe. -The stamps are lifted by means of a cam shaft in such a -manner, that the height of fall of the outermost pairs of<span class="pagenum" id="Page_35">35</span> -stamps is least and that of those in the centre greatest. -Between the inner stamps is a sieve <i>H</i> with meshes of sufficient -size to allow the largest pieces, which can be produced -by granulation, to fall through.</p> - -<p>Underneath the sieve is an Archimedean screw <i>K</i> for -carrying off the pieces of bone passing through the sieve.</p> - -<div class="center" > -<div class="caption"><span class="smcap">Fig. 7.</span></div> -<img src="images/i_p035-1.jpg" alt="" /> -</div> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 8.</span></div> -<img src="images/i_p035-2.jpg" alt="" /> -</div> - -<p>The base of the stamping mill consists of iron plates so -arranged as to form steps, the plates lying towards the -center of the mill constituting the lowest steps. Every two -stamps standing alongside one another rest upon such a -step. When the mill is set in motion, the bones reaching -the stamping trough from the right and left fall upon the -steps, and are crushed by the descending stamps.</p> - -<p>As a rule, the bones to be stamped are not brought<span class="pagenum" id="Page_36">36</span> -directly into the stamping trough, but are first passed -through a crushing mill and the coarser pieces thus obtained -are subjected to the action of the stamping mill.</p> - -<p>Figs. 7 and 8 show a well-constructed bone crusher. It -consists essentially of two cast-iron rollers <i>A</i> and <i>B</i>, furnished -with case-hardened cutters. The bones are introduced -through the hopper <i>B</i>, and the rolls set in motion by -means of cog-wheels <i>a</i> and <i>b</i>. The bearings of the roll <i>B</i> -run in a carriage which can be shifted by the lever-construction -<i>f i</i>. The object of this contrivance is to allow of -the roll <i>B</i> giving way in case a harder material than -bones, for instance, a stone, passes between the rolls.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 9.</span></div> -<img src="images/i_p036.jpg" alt="" /> -</div> - -<p>The Crosskill bone mill, Fig. 9, as described by S. Rideal, -is intended to be driven by a strap from the fly wheel of -a common portable engine. It consists of a pair of strong -rollers made of wrought-iron with case-hardened cutters, -and a revolving or oscillating riddle for separation of the -ground bones as they fall from the cutters; the whole carried -by a substantial cast-iron frame. The mill will grind -from 6 to 16 hundred-weight per hour with a three to eight -horse-power engine.</p> - -<p>For sorting the crushed bones into pieces of equal size, a -sieve, Fig. 10, is used consisting of a drum constructed of -narrow boards covered with wire-netting of different de<span class="pagenum" id="Page_37">37</span>grees -of fineness. The upper portion <i>A</i> of the drum consists -of narrow-meshed net and through this falls the fine -meal which is conveyed by the Archimedean screw <i>F</i> over -the frame <i>F G H</i> into vessels serving for its reception.</p> - -<p>The lower section, <i>B</i>, of the drum is furnished with -netting, the meshes of which become gradually wider towards -the lower end, and, hence, the smallest particles of -bone fall through the funnel, <i>D</i>, the medium-sized ones -through <i>E</i>, and the largest ones through <i>F</i>. Pieces which -cannot pass through <i>F</i>, leave the drum at <i>G</i>.</p> - -<p>In factories manufacturing glue as well as animal charcoal, -the larger pieces are steamed by themselves to obtain -their fat, and then charred, while the small pieces and the -meal are utilized for glue.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 10.</span></div> -<img src="images/i_p037.jpg" alt="" /> -</div> - -<p>The lime-bath used for bones should be of the same -strength as that for skin-stock. After removal from the -lime vat and washing, the bones are put in a tank of stone -or wood (brick pits should not be used) containing cold -hydrochloric acid of 70° Bé. or 1.05 specific gravity (= 10.6 -per cent. HCl) for thick bones, or half that strength for -thin bones, and are thus left to digest for 8 to 14 days, -being frequently stirred and fresh acid added. By the -action of the acid the calcium phosphate is dissolved and -the bones become cartilaginous, flexible and transparent. -The phosphates can be precipitated by ammonia, or the -whole evaporated with charcoal or silica, and distilled to -make phosphorus.</p> - -<p><span class="pagenum" id="Page_38">38</span></p> - -<p>When sufficiently softened, the stock is washed in wicker -baskets or a washing drum to remove adhering acid. They -are then placed for one day in the lime liquor, again -washed, and then either dried or stored away for future use, -or boiled at once to glue, while in a moist state.</p> - -<p>Leg bones, horns, and other soft bones which contain -scarcely any fatty matter are not steamed for the reason -previously stated, but in all other respects are treated like -steamed bones.</p> - -<p>It is of the greatest importance that the bones should be -thoroughly freed from acid, since even the smallest quantity -remaining behind exerts an injurious effect upon the -finished glue. It is therefore recommended to test the -water draining off, or the bones themselves, with litmus. -If the tincture turns red, it is a sure indication of the presence -of free acid, and the washing must be continued until -the blue color of the tincture remains constant.</p> - -<p>Gerland’s suggestion, to use dilute sulphurous acid in -place of hydrochloric acid for dissolving the phosphates of -the bones, and to evaporate the sulphurous acid by heating, -whereby the phosphates are precipitated in an insoluble -state, has now been quite generally introduced.</p> - -<p>For the preparation of gelatine from bones, Jullion and -Pirie’s process may be recommended. It requires a somewhat -expensive plant, but saves hydrochloric acid and -time. The process consists essentially in dissolving the -phosphates of the bones in vacuum. A box of wood, or -better of granite, which can be closed air-tight, is required -for this purpose. The box is filled with bones, and acid of -the previously-mentioned strength poured over them. The -box is then closed and the air pumped out by water or -steam power. The smallest cracks and pores of the bones -are thus freed from air, and the latter is replaced by hydrochloric -acid, which in this manner acts rapidly and is completely -exhausted. The remaining crude glue is then -further worked in the usual way.</p> - -<p><span class="pagenum" id="Page_39">39</span></p> - -<p>Bones honey-combed by putrefaction, exposure to the -weather, or burial in the ground are of little or no value to -the glue-boiler, as nearly all the glue-yielding substance has -been destroyed; they should therefore be thrown out in buying -stock. The ammonia which is formed when putrefaction -sets in, colors the glue dark.</p> - - -<h4>3. LEATHER WASTE.</h4> - -<p>Leather tanned with a substance insoluble in water is not -directly suitable for manufacturing glue, but can be made -so by a special process, which, though somewhat tedious, -nevertheless pays for the trouble.</p> - -<p>In using such stock the manufacturer should make a distinction -between old and new leather. The principal -materials of this kind, large quantities of which contribute -their quota to the glue-boiler’s stock, are old shoes, straps, -harness, etc., and further, waste from shoemakers, trunk-makers, -and in fact from the shops of all workers in leather -except those using alumed leather.</p> - -<p>Before boiling the leather waste to glue, the removal of -all traces of tannin becomes absolutely necessary, since the -retention of the smallest quantity prevents the animal tissue -from dissolving in water.</p> - -<p>The various methods proposed for the preparation of the -leather waste differ either in the chemical solvent used, or -in the mechanical manipulation of the waste.</p> - -<p>The principal point in all methods is to comminute the -waste as uniformly as possible to facilitate the complete removal -of the tannin.</p> - -<p>Various machines, some very complicated, have been -proposed for the comminution of the waste, but a rag engine -or “hollander” such as is used by paper-makers deserves -preference for the purpose, as it not only comminutes, -washes and prepares the waste in a suitable manner for the -manufacture of glue, but the leather pulp when mixed with -rags or woody fibre gives a substitute for leather which is<span class="pagenum" id="Page_40">40</span> -very tough and of good appearance, and can be worked into -many articles.</p> - -<p>After the preparation in the hollander and careful washing -the waste is treated, according to Stenhouse, under a -pressure of two atmospheres in a boiler with water to which -is added 15 per cent. of the quantity of waste to be treated -at one time of slaked lime.</p> - -<p>By another method the extraction of the tannin is effected -by boiling the leather pulp with caustic soda of 1.025 specific -gravity for from six to twelve hours. After drawing -off the water and pressing out, the pulp is again boiled with -caustic soda of the same concentration. The next process -is to carefully wash out the soda, which is best effected in -the hollander.</p> - -<p>By neutralizing the soda lye in the fluid drawn off after -the first boiling, it can be re-used for tanning or purposes -for which tannin is required.</p> - -<p>According to another method, the <i lang="la">modus operandi</i> is as -follows:</p> - -<p>Dissolve 1½ lbs. of oxalic acid in 3 gallons of water, pour -the boiling solution over 110 lbs. of waste, and keep the -mixture in a water-bath at a temperature of 176° to 212° F. -This effects the solution of the pulp. Then dilute the solution -by adding gradually 4 gallons of water until a uniform -mass is formed. Now add 5 lbs. of lime slaked to a thin -paste, and mix the whole thoroughly. The mass becomes -friable and pulverulent. It is passed through a wire sieve -and then exposed to the air. In three to four weeks the -tannin is entirely destroyed, which is recognized by the -mass assuming a lighter color. The lime is then removed -by washing with water and hydrochloric acid. If the tannin -has not been entirely destroyed by exposure to the air, -add 1 lb. of liquid ammonia and a like quantity of pyrolusite -to every 110 lbs. of leather substance when boiling it to -glue. The oxygen yielded up by the pyrolusite, which, in -the presence of ammonia, exerts no injurious effect upon the<span class="pagenum" id="Page_41">41</span> -glue, destroys the last traces of tannin. Frequent stirring -with a shovel while the material is exposed to the air and -moderate heating, facilitates the destruction of the tannin.</p> - - -<h4>4. RAW MATERIALS FOR FISH GLUE.</h4> - -<p>The air-bladders or sounds of various fishes contain much -glue-yielding substance and on account of its purity, the -product known as isinglass obtained from them is preferably -used for culinary and medicinal purposes. The high price -of the raw material excludes it from being used by the -glue-boiler, but as he manufactures substitutes for isinglass, -and should therefore have a thorough knowledge of the -article with which he has to compete, its manufacture will -be included in this treatise. Since, however, the work of -the manufacturer is finished with the preparation of the -raw material, <i>i. e.</i>, of the air-bladders into crude glue, isinglass -and its substitutes will be referred to later on.</p> - -<p>There is a material difference between isinglass and glue -manufactured from entire fishes. The raw material is, of -course, limited to certain localities. The principal point to -be observed in the manufacture of fish-glue is the removal -of the skin, which is effected by means of dilute sulphuric -acid.</p> - -<p>After removal of the last traces of acid, the fatty matter -of the fishes is saponified by a treatment with milk of lime -frequently renewed. After washing out the lime, the pulpy -mass is placed in a solution of sodium hyposulphite, alum, -and common salt, where it remains for a few days. The -liquor is then drawn off and replaced by a mixture of solution -of alum, dilute sulphuric acid and nitric acid. After -macerating in this mixture for a few days, the mass is -thoroughly washed and boiled to glue, and the resulting -product clarified with sulphurous acid or alum solution. -As will be seen, the entire process is tedious, requires many -chemicals, and besides the yield of glue, which has no -specially good qualities, is small. It is used as a substitute<span class="pagenum" id="Page_42">42</span> -for isinglass for clarifying liquids. The best proof that the -business is of but little importance is found in the fact that -no fish-glue has been exhibited at any of the late international -exhibitions.</p> - -<p>The scales of large fishes, such as carp, give more favorable -results. They are treated with hydrochloric acid in a -similar manner to bones. The scales do not dissolve entirely, -a horny insoluble mass, giving no glue, remaining -behind after the solution of the glue-yielding substance.</p> - -<hr class="chap" /> - -<p><span class="pagenum" id="Page_43">43</span></p> - - - - -<div class="chapter"></div> -<h3><a name="CHAPTER_IV" id="CHAPTER_IV">CHAPTER IV.</a><br /> - -<small>MANUFACTURE OF SKIN GLUE.</small></h3> - - -<p>The thorough preparation of the raw materials will -materially facilitate all succeeding operations, which may -be classified as follows:</p> - -<p>1. Boiling the glue.</p> - -<p>2. Clarifying the glue-liquor.</p> - -<p>3. Forming or moulding the glue.</p> - -<p>4. Drying the glue.</p> - -<p>However, before entering into the description of these -operations, it will be necessary to refer to an intermediate -product, which has been previously mentioned under the -name of crude glue, and is prepared, for instance, by -tanners and manufacturers of parchment, but also forms in -some localities a special branch of industry.</p> - -<p>This crude glue is actually not glue, but a glue-yielding -substance in such a state of preparation that it can be -directly used for the first operation, namely, boiling. It -consists of waste of skins and leather of all kinds, completely -cleansed, dried and limed, and in the case of leather -treated with agents for the extraction of the substances used -in the tanning. As will be readily understood, the operations -required for the preparation of this stock are virtually the -same as those described in the previous chapter for raw -materials and need not further be here referred to.</p> - -<p>The bulk of such stock is prepared by tawers and manufacturers -of parchment, though a considerable quantity of -it is also derived from waste in the manufacture of gloves. -The product from the latter source is also found in commerce -under the French names <i lang="fr">Colle franche</i> or <i lang="fr">Brochette</i>. -However, if such stock is used, it is best to again immerse<span class="pagenum" id="Page_44">44</span> -it in lime water, after which it should be thoroughly -washed.</p> - -<p>The manufacture of glue from hide and leather waste -differs materially in many respects from that of bone glue, -it being the more simple process, as no other preliminary -operations than the preparation of the glue-stock are required. -The first operation is</p> - - -<h4>1. COOKING OR BOILING.</h4> - -<p>For this operation any kind of boiler may be used, but -the materials should be supported on a perforated grid a -little distance above the bottom, so as to save them from -risk of scorching. In the centre of the grid stands a conical -pipe 2 to 3¼ feet long, perforated like the grid and communicating -with the space between the grid and the bottom of -the boiler. The height of the boiler can be increased 1 to -1½ feet by placing an annular piece upon the rim which is -bent upwards for its reception.</p> - -<p>The size of the boiler depends on the quantity of raw -material to be worked at one time. It is best to choose -boilers holding from 110 to 440 lbs. of glue-stock, and to -place two, four or more of such boilers in one hearth.</p> - -<p>The manner of using such a boiler is very simple. Straw -is placed upon the false bottom in such a manner as to cover -its entire surface, and extend up the sides of the boiler at -least as far as it is touched by the flame. The object of the -straw is to serve as a filter, and protect the materials from -injury by the flame. But for the production of entirely -pure gelatine or glue, straw cannot be used, as, by boiling, it -yields a yellow coloring matter, which passes into the glue. -Barley straw gives a less intense coloring matter than rye -straw.</p> - -<p>In case straw cannot be used, the material is placed in a -large bag, previously thoroughly boiled, and suspended in -the boiler so as not to touch the sides. By this means -scorching is prevented even if the fire touches the bottom -as well as the sides of the boiler.</p> - -<p><span class="pagenum" id="Page_45">45</span></p> - -<p>The boiler having been heaped with material so high as -to overflow the brim and fill the annular piece placed upon -it, is filled with water as far as touched by the fire. The -fire may now be started. The hearth in which the boiler -is placed should, of course, be so constructed that the gases -are uniformly distributed and the water quickly brought to -the boiling-point. When the water commences to boil, -bubbles of steam ascend from the space beneath the grid -and, passing through the perforations of the conical pipe, -penetrate the glue-stock. Thus the first formation of glue -takes place, and the stock begins to settle down gradually -as it goes into solution. The stock heaped up in the annular -piece also sinks down gradually, and being partly -heated by the hot vapors and thus prepared for solution, is -finally submerged in the boiling solution and becomes soon -entirely dissolved.</p> - -<p>Waste of hide and horn piths are completely dissolved in -five to seven hours. No more water should be used than is -absolutely required for cooking the entire quantity of stock, -because too much water renders the solution too thin and -gives a jelly of little consistency and difficult to dry. Concentrating -the glue solution by continued boiling is bad -practice, as it is detrimental to the resulting product by -reason of the glutin undergoing a gradual transformation.</p> - -<p>It is best to start with a slow fire to give the stock time -to soften and thus prepare it for solution. When somewhat -softened, the mass is brought to boiling and the latter kept -up, gently and uniformly, until solution is complete. Solution -is promoted by careful stirring, but care should be had -not to disarrange the straw upon the grid and on the sides -of the boiler as this would interfere with proper filtration of -the glue solution.</p> - -<p>The duration of cooking depends on the nature of the raw -materials. Scraps of skin from young animals, antlers, -sheep trotters, etc., dissolve in three to four hours, while -waste from ox and horse hides, or bones from old animals, -require six to eight hours.</p> - -<p><span class="pagenum" id="Page_46">46</span></p> - -<p>The progress of the operation is readily ascertained by -pouring a small sample of the gelatinous fluid in half an eggshell, -and setting it aside for a few minutes to cool. If a -clear and consistent jelly be obtained, boiling has been -carried on to a sufficient extent, and the liquid is drawn off. -Any undissolved glue-stock remaining upon the straw filter -can be boiled by itself, and the resulting gelatinous liquor -utilized in the next boiling.</p> - -<p>It is evident that quick and uniform solution of the -materials, which enhances the quality of the glue, is promoted -by comminuting the glue-stock either by grinding, -stamping, or mechanical means.</p> - -<p>The succeeding clarification of the glue is much facilitated -by removing while boiling the scum, consisting of -fat, coagulated albumen, lime-soap, accidental admixtures, -and other impurities. Before drawing off the gelatinous -liquor it is advisable to withdraw the fire and allow the -contents of the boiler to rest for fifteen minutes.</p> - -<p>The residue remaining upon the straw filter consists of -hair, lime-soap, undissolved particles of hide and bones, -lime, etc., and is utilized, after repeated boiling, as fertilizer -or for the manufacture of gas.</p> - -<p>The mode of glue boiling above described is the oldest and -at present is only in use in small establishments. Fig. 11 -represents a convenient apparatus for the purpose. It consists -of three boilers upon as many different levels. The lower -boiler, <i>b</i>, serves for the settling and clarification of the glue. -It communicates with the second boiler, <i>a</i>, which contains the -material to be acted on, by means of a pipe provided with -a stopcock, and is sufficiently heated by a small fire to keep -the glue liquid without allowing it to reach ebullition. The -upper boiler, <i>c</i>, which is heated by the waste heat of the -chimney, serves as an economical reservoir for hot water. -The end of the discharge-pipe of the settling boiler is provided -with a filter of woven wire. As the sides and bottom -of the second boiler are lined with straw, which acts as a<span class="pagenum" id="Page_47">47</span> -preliminary filter, the glue runs off quite clear from the -settling boiler.</p> - -<p>When this mode of manufacture is adopted, two boilings -can be made per day, under favorable circumstances, so -that, if the boiler has a capacity of 220 lbs. of stock, which -will yield from 110 to 132 lbs. of dry glue, the daily fabrication -will be about 220 lbs. of finished product.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 11.</span></div> -<img src="images/i_p047.jpg" alt="" /> -</div> - -<p>In larger plants, the above described mode of extracting -the glue-stock with water has been superseded by the use -of steam in a cylindrical wrought-iron boiler, twice as high -as wide, and capable of withstanding a pressure of three -atmospheres. The boiler is furnished with a perforated -false bottom underneath which terminates a steam pipe. It -is filled from above with previously softened glue-stock and -the charging hole hermetically closed. Steam is then -gradually admitted and exerts at once a dissolving influence -upon the stock. A portion of the steam condenses and -forms with the dissolved glue-stock a concentrated jelly -which collects between the true and false bottoms.</p> - -<p><span class="pagenum" id="Page_48">48</span></p> - -<p>For the escape of air a cock is provided which is closed -as soon as steam commences to escape from it.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 12.</span></div> -<img src="images/i_p048.jpg" alt="" /> -</div> - -<p>The advantages of this process are obvious. A larger -quantity of glue-stock can be extracted than in the boiler -previously described, and there is no danger of injury by -scorching and consequent damage to the color of the glue. -More highly concentrated solutions are obtained in a shorter -time, and the spoiling of the glue solution by too long continued -cooking is prevented by drawing off the solution as -quickly as formed. The escaping hot vapors may be utilized -for drying the glue, softening the raw material, etc., -the entire quantity of heat being thus utilized. A further -great advantage of this method is that there is less annoyance -from badly-smelling vapors than when boiling is done -over an open fire. A number of such boilers can be ar<span class="pagenum" id="Page_49">49</span>ranged -in one room and supplied from a common steam -boiler.</p> - -<p>Fig. 12 represents a boiler for extracting glue-stock with -the use of steam. It is provided with a lid, <i>D</i>, which is -removed for charging the boiler. The aperture, <i>E</i>, in front, -serves for the removal of the residue. Above the true bottom -there is another false bottom, perforated and movable, -which can be covered with straw for preliminary filtration. -The steam reaches the glue-stock through a pipe which -passes through the actual and false bottoms, and is perforated -above the latter. The resulting jelly collects between -the true and false bottoms, where it is less exposed -to the action of hot steam. The escaping steam passes -through the pipe, <i>F</i>, which is provided with a stock-cock. -The pressure in the boiler is indicated by the manometer, -<i>K</i>. After throwing the materials into the boiler they can -be covered with warm water, or, after the lid is closed, -warm water is introduced from a reservoir through a special -pipe and distributed over the material through a rose.</p> - -<p>The boiler stands upon a frame sufficiently high to allow -of conveniently placing a vessel under the pipe <i>G</i>, through -which the jelly is discharged. The vessel, when full, is -conveyed to the settling vat, or the arrangement may be -such that the jelly is directly run into the settling vat.</p> - -<p>In many large plants open jacketed pans heated by steam -are still used for treating the material. Fig. 13 shows an -arrangement with two of such pans; of course one, or a -larger number may be used, according to requirement. In -the illustration the pan <i>I</i> on the left is shown in front -view, and the pan <i>II</i> on the right, in section. <i>K<sub>1</sub></i> is the -actual pan enclosed by the jacket <i>K</i>. Steam circulates in -the space between pan and jacket, whereby the stock in the -pan is heated. <i>K<sub>1</sub></i>, in addition, is furnished with a steam -coil <i>S</i>, which may, however, be omitted.</p> - -<p>The steam enters through the pipe <i>D</i>, the space between -pan and jacket, passes into the coil <i>S</i>, and escapes at <i>b</i>.<span class="pagenum" id="Page_50">50</span> -The water formed by the condensation of steam in the space -between pan and jacket, as well as that which runs off at <i>b</i> -from the coil <i>S</i>, is carried away by the pipe <i>A</i>.</p> - -<p>The pipe <i>L</i> serves for conveying hot water to the pans, -and the pipe <i>F</i> for the discharge of the finished glue liquor. -The stirrer <i>R</i>, is furnished with two paddles, and is set in -motion by a transmission on the ceiling of the room. It -serves for keeping the stock in the pans constantly agitated, -solution being thus very much promoted.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 13.</span></div> -<img src="images/i_p050.jpg" alt="" /> -</div> - -<p>The mode of working with this apparatus is very simple. -Water being admitted into the pan through <i>L</i>, the glue-stock -is introduced and the mass brought to boiling by admitting -steam. The finished glue-liquor is from time to -time drawn off through the pipe <i>F</i> into the settling vessel.</p> - -<p>It is generally preferred not to concentrate the glue-liquor -in the pans to such a degree as required to obtain a -jelly, which after cooling, can be immediately moulded, -experience having shown that less concentrated liquors can -be more readily and better clarified, and yield a lighter and -more transparent glue.</p> - -<p><span class="pagenum" id="Page_51">51</span></p> - -<p>Mr. Thomas Lambert gives the following process of cooking: -The skins are taken to the glue-boiler, which is an -open vessel, 8 feet in diameter at the top and 7 feet deep, -and provided with a perforated false bottom, through the -center of which passes a two-inch pipe, one end dipping -below a layer of water at the bottom, the other projecting -about half the height of the boiler, this part being covered -with a perforated hood to spray the liquor through the -mass. The skins are placed on the false bottom and the -added water at the bottom of the boiler is brought to the -boil by means of a steam pipe. The steam not being able -to escape quickly through the dense mass of glue-stock -above, exerts a pressure on the water, forces it through the -pipe, to be sprayed through the mass, and ultimately works -its way to the bottom of the boiler to be forced up again. -This continual circulation of the hot liquor rapidly dissolves -the gelatinous matter, and when a strength of 18 per cent. -dry glue is reached, the first run is made to the evaporating -pan, the liquor passing through a filter of fine shavings, to -remove any suspended matter. Fresh water is added to the -boiler, and the boiling renewed. Three extractions are -usually made, the last being used for size.</p> - -<p>In order to avoid annoyance to the neighborhood from -foul odors, Terne’s glue-boiler shown in Fig. 14 may be -recommended. The lead-lined iron boiler <i>A</i>, with manholes -<i>B</i> and <i>C</i>, on top and side, is furnished with a false -perforated bottom upon which the glue-stock is placed. -Underneath the false bottom lies the coil <i>E</i> with valve-box -<i>e</i>. The boiler is filled through the upper manhole with -glue-stock and water admitted, steam being at the same -time introduced in the coil and in order to quickly heat the -water, direct steam is also admitted to the boiler through -the pipe <i>F</i> and cock <i>G</i>. When the water is boiling the -cocks <i>G</i> and <i>F</i> are closed, the coil furnishing now sufficient -heat. During boiling some steam is allowed to escape -through the partly-opened cock <i>L</i>, all badly-smelling gases<span class="pagenum" id="Page_52">52</span> -being thereby carried to the fire-box of a boiler where they -are burned. When boiling is finished, the glue liquor -remains for a short time in the boiler to allow the melted fat -to separate on the surface, the cocks <i>K<sub>1</sub></i> and <i>K<sub>5</sub></i> and serving for -drawing off the fat. The insoluble residues of the glue-stock -remain upon the false bottom and are taken out -through the manhole <i>C</i>.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 14.</span></div> -<img src="images/i_p052.jpg" alt="" /> -</div> - - -<h4>2. CLARIFYING THE GLUE-LIQUOR.</h4> - -<p>The clearness of glue, <i>i. e.</i>, its freedom from undissolved -substances, is by no means a criterion of its value as an -agglutinant, since pulverulent inorganic substances (white -lead) are frequently intentionally introduced into some -varieties, for instance into Russian glue, without injury to<span class="pagenum" id="Page_53">53</span> -their adhesive power. But as a turbid appearance may -also be an indication of unsoundness and decomposition, -the manufacturer endeavors by all means to obtain a clear -product.</p> - -<p>A strict distinction should be made between clearness and -color. Very dark-colored glue may be very clear, and a -very pale variety the reverse, yet both possess excellent -qualities. Both properties, clearness and light color, cannot -be obtained by the same process.</p> - -<p>Clearness will be first referred to. If the glue-stock has -been properly prepared by rendering adhering particles of -blood and fat innoxious by liming and subsequent careful -washing, the separation of the few remaining impurities, -which may have passed through the straw filter, is readily -effected by allowing the liquor to stand, care being had to -keep it liquid as long as possible to give the grease time to -rise and the flocculent and fibrous impurities to settle. -This is best effected in a wooden vat surrounded by a -wooden or sheet-iron jacket, the intermediate space between -jacket and vat being filled with a non-conductor of heat, or, -if required, it may be heated by the introduction of steam. -The grease is skimmed off as it rises, and when the solid -particles have settled the liquor is drawn off through a pipe -placed a short distance above the bottom of the vat.</p> - -<p>The size of the clarifying vat depends on the size of the -boiler. It is, however, best to have two vats for each -boiler, in order to keep the first liquor, which is always -clearer and more concentrated, separate from the last run. -To be able to draw the upper layers of purer liquor into -cooling boxes by themselves, the vats are provided with faucets -at different heights.</p> - -<p>To prevent putrefaction of the liquor which readily sets -in during settling at a higher temperature, the vats should -be kept scrupulously clean, and from time to time rinsed -with clean, hot water. It is also advisable to line them -with sheet-iron.</p> - -<p><span class="pagenum" id="Page_54">54</span></p> - -<p>Should the above-described mechanical separation not -prove sufficient, recourse must be had to other means. -Alum and sulphate of alumina have long been used for -clarifying, 1 lb. of either of them, pulverized, added to -every 300 gallons of liquor, being as a rule sufficient. -Either of these chemicals removes the albuminous and extractive -constituents of the solution, and converts the dissolved -free lime into sulphate of lime, which settles readily, -and prevents putrefaction of the glue solution while drying -under unfavorable circumstances. The quantity of alum -mentioned above does not impair the quality of the glue.</p> - -<p>Albumen is sometimes used for the better qualities of -glue, and generally for gelatine, but a cheaper substitute is -fresh blood, which contains albumen and fibrin. Dry -albumen is dissolved in cold water, or white of egg is used -direct, if procurable. Before adding either of these substances, -the liquor is cooled to 130° F., and the clarifier -well stirred in; then the temperature is raised to about -200° F., when coagulation occurs, and the precipitate entangles -the impurities and falls to the bottom, requiring, -however, from twelve to twenty-four hours to clear. It is -said that glues clarified with albumen have a characteristic -soapy smell and show a tendency to foam.</p> - -<p>The precipitation of the lime might be better effected by -oxalic acid, and the organic substances removed as scum by -adding to the boiling mass some astringent matter, such as -a decoction of oak bark or hops; but the purification has, -in either case, to be done at the expense of glutin.</p> - -<p>A glue liquor, which does not clarify by these means, is -not sound, and is derived either from spoiled raw materials, -or such as have not been thoroughly prepared, or has been -injured in boiling.</p> - -<p>A far more difficult matter than the removal of mechanical -admixtures is to free the liquor from the coloring substances -from which it derives its color, and to discolor it -without injury to the characteristic qualities of the glue.</p> - -<p><span class="pagenum" id="Page_55">55</span></p> - -<p>The use of animal charcoal for such large quantities of -somewhat thickly-fluid solutions, which are liable to spoil -at the high temperature at which they would have to be -filtered, is very difficult, and the result not favorable, except -the solutions could be successfully deprived of their -tendency to putrefy. The use of carbolic acid is also in -this case the only means of removing the great tendency of -the liquor to putrefy, and hence, if the liquor is to be discolored -by treatment with animal charcoal, it can only be -done without danger to the glue, by mixing it with carbolic -acid.</p> - -<p>The object is more easily effected by bleaching the raw -materials previous to boiling them to glue.</p> - -<p>This is accomplished by placing the glue-stock, thoroughly -limed and while still moist, in a bath of chloride of -lime, not too strong, as otherwise the solution of the materials -becomes difficult. A bath of the proper concentration -is made by dissolving about 9 ozs. of chloride of lime in -sufficient water to cover 110 lbs. of glue-stock. After one -hour add sufficient hydrochloric acid to obtain an acid reaction, -which is recognized by litmus-paper dipped in the -bath turning red.</p> - -<p>Although the glue-stock is not bleached entirely through -by this process, the thin portions and outsides of the thick -material acquire a lighter color, and the first run of glue -solution will have a light color and can then be treated further -without much difficulty.</p> - -<p>Sulphurous acid has been successfully used for the production -of colorless glue without the necessity of boiling.</p> - -<p>Waste of hides and skins is the only available material -for this process. Place the waste in water until putrefaction -sets in. When this is the case wash the material in a -bag or wicker basket in running water. Then pour 2½ -parts of sulphurous acid over 12 parts of wet material, mix -the whole thoroughly and let it stand in a hermetically -closed vessel for 24 hours. Now draw off the acid, and<span class="pagenum" id="Page_56">56</span> -after washing the material thoroughly repeat the operation. -When the vessel containing the mixture of material and -sulphurous acid is opened for the second time the foul odor -should be entirely superseded by that of sulphurous acid, -this being a sure indication of the correct execution of the -process. Wash the material, and, after squeezing, throw it -into a vat large enough not to be filled by it more than -two-thirds full. After filling the vat with water allow the -mass to digest at a temperature of 109.4° F. for 24 hours. -The result will be a gelatinous solution, which is drawn off -and converted into glue. The undissolved residue is transformed -into gelatinous solution by pouring water over it -and allowing it to stand at a somewhat higher temperature.</p> - -<p>For carrying out this process and that of bleaching with -chloride of lime it is best to use a vat provided with a stirring -apparatus, somewhat like a hollander used by pape-rmakers, -as being most suitable for washing, disintegrating -and mixing the material.</p> - -<p>Glue-liquor may also be successfully bleached with sulphurous -acid, and in speaking later on of the manufacture -of bone glue, a very practical apparatus for this purpose -will be described.</p> - -<p>Glue-liquor bleached by sulphurous acid clarifies very -readily and is protected from spoiling. The resulting glue -remains, however, quite acid, and cannot be used for all -purposes, especially not in combination with colors, chemicals, -etc., upon which the acid has a destructive effect.</p> - - -<h4>3. FORMING OR MOULDING THE GLUE.</h4> - -<p>After clarifying, the liquor is run into moulds of deal -wood or sheet iron, lightly joined and of a rectangular form, -slightly converging towards the bottom so as to allow the -more ready detachment of their contents. They are about -3.25 feet long, 10 inches wide at the top, and 7¾ inches at -the bottom, and 5 inches deep. When very regular cakes -of glue are desired, cross grooves of the required shape are<span class="pagenum" id="Page_57">57</span> -cut in the bottoms. After being well cleansed and ranged -upon a level the boxes are filled to the brim through large -funnels with strainer cloths affixed to their barrels. It is -best to place them upon perfectly clean stone flagging -slightly inclined towards a reservoir for the reception of -such portions of their contents as may run over. The -apartment in which the work is performed should be clean -and airy, a dry cellar being the best for the purpose. In -place of a large number of boxes, a shallow vessel lined -with sheet-iron and capable of holding the entire quantity -of liquor is sometimes used, from which the solid jelly is -cut out in cubic masses, which are further divided.</p> - -<p>This arrangement can only be recommended for establishments -where but one variety of glue is produced, and -the different layers in the clarifying vat are not separated -according to their clearness. Before running the liquor -into the boxes the latter should be moistened with water, -or, if made of wood, coated with oil, stearine, or paraffin to -prevent the liquor from penetrating the wood and the -solidifying glue from adhering to the sides.</p> - -<p>After the solidification of the glue, which generally takes -place in twelve to eighteen hours, the boxes are inverted -upon a table with a smooth top of wood or stone previously -wetted, so as to prevent the adherence of the gelatinous -cake to its surface. To detach it from the sides of the -boxes the moistened blade of a large knife is generally -used.</p> - -<p>Cutting the cubes of glue into commercial cakes or -sheets is readily accomplished by observing the following -instructions:—</p> - -<p>The shape of the cakes depends principally on custom. -The consumer is used to a certain variety of glue, and if it -is not offered to him in the customary shape, he might -refuse it and take his custom elsewhere. The quality of -the glue is the next point to be considered. If very dark, -it is advisable to cut the glue into thin cakes, and if<span class="pagenum" id="Page_58">58</span> -turbid, into thick ones, in order to make this defect the -less apparent. Thicker cakes can also be cut if the conditions -for drying them are favorable, and thinner ones if the -reverse is the case.</p> - -<p>The mass is first divided by a steel or brass wire stretched -over a frame, like a bow saw, into horizontal layers. The -size of these layers is regulated by guides which are placed -at distances corresponding with the desired thickness of the -cake of glue. Instead of one wire, as many as the cakes -of glue to be cut, can be stretched over the frame, which -is best made of iron and provided with conical pins by -means of which the wires can be tightened, in the same -manner as piano strings, when they have become slack by -use.</p> - -<p>The width and thickness of the cakes of glue are regulated -by the distance of the wires from each other, and the -length by the width of the box. The cakes thus formed -are dexterously lifted from the block with the moist blade -of a large knife and placed upon nets.</p> - -<p>Instead of using wooden or sheet-iron cooling-boxes, it is -recommended to pour a layer of liquor of the desired thickness -of the glue cakes upon large polished stone slabs, and -when congealed, cut it into sheets, which are placed upon -the nets to dry. The advantages of this method are -obvious. The liquor cools more quickly by being exposed -in a thin layer upon a large surface, which reduces the -danger of spoiling, and a strong evaporation of water and -consequent concentration take place. Besides, the cakes -show the smooth surface of the polished stone, and become -in a short time so hard, that when placed upon the nets, -the twine will make no impression upon them.</p> - -<p>Liquors which in gelatinizing do not become very solid, -are not run into forming boxes, but upon glass or zinc -plates, and thus spread out in a thin layer, acquire sufficient -solidity to be removed cake by cake after being cut. -The plates upon which the glue is run are placed in frames<span class="pagenum" id="Page_59">59</span> -and laid upon a table furnished with a rim about 1 inch -deep. To accelerate gelatinization of the liquor, the table -is flooded with water before placing the plates upon it.</p> - -<p>Where cooling-boxes are used, the jelly when completely -congealed is placed upon a table with a stone plate, by -inverting the boxes, and then cut into cakes. Figs. 15 and -16 represent the tools for cutting the jelly into cakes. The -block of glue is laid upon the surface <i>A</i>, Fig. 15, and the -frame, <i>B</i>, is gently drawn along in the grooves, <i>a</i>. In the -upright portion of the frame are fixed wires at such a distance -from each other as required for the thickness of the -cakes to be cut.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 15.</span></div> -<img src="images/i_p059-1.jpg" alt="" /> -</div> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 16.</span></div> -<img src="images/i_p059-2.jpg" alt="" /> -</div> - -<p>When the block of glue has been cut in this direction, it -is divided by cuts perpendicular to the former, into cakes -of a size in which the finished product is to be brought into -commerce. The apparatus shown in Fig. 16 serves for this -purpose. The vertical bars, <i>a</i>, furnished with the wire, -<i>b b</i>, serve as guides. The sheets thus formed are lifted from -the block with the moist blade of a large knife, and laid -upon nets.</p> - -<p><span class="pagenum" id="Page_60">60</span></p> - -<p>The machine shown in Figs. 17 and 18 is the invention -of Mr. J. Schneible, and it is for slicing and spreading glue-jelly -preparatory to drying, and it consists in the combination -of a reciprocating cutter with the jelly-box and a traveling -belt-carrying frame for receiving the slices as cut by -the knife.</p> - -<p>Fig. 17 is a partly sectional side view of the machine, -and Fig. 18 is a cross-section of the same.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 17.</span></div> -<img src="images/i_p060-1.jpg" alt="" /> -</div> - -<p><i>A A</i> are side bars of the supporting frame, fitted at the -ends with cross-shafts, <i>a´</i>, carrying pulleys, <i>a a</i>, around which -are endless belts, <i>b b</i>. <i>c c</i> are slide-ways upon the bars, <i>A</i>, -and <i>d d</i> are slides carrying a cross-plate, <i>e</i>, and also a plate, <i>f</i>, -to which plate <i>e</i> is attached a knife or cutter, <i>g</i>, the cutting -edge of which is at the edge of the plate, <i>f</i>, and about the -same thickness as the slices to be cut. The cross-shaft, <i>h</i>, -is fitted in boxes on bars, <i>A</i>, and near one end thereof it is -provided with cranks at its ends, which connect by rods, <i>i</i>, -to the slides, <i>d</i>.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 18.</span></div> -<img src="images/i_p060-2.jpg" alt="" /> -</div> - -<p>From the opposite ends of the slides, rods, <i>k</i>, pass to loose -arms, <i>l</i>, on the shaft at the opposite end of the machine, and -the arms, <i>l</i>, carry pawls, <i>l´</i>, that engage ratchet-wheels, <i>m</i>, -fixed on the shaft, so that the shaft, <i>h</i>, being revolved, the<span class="pagenum" id="Page_61">61</span> -slides, with plates, <i>e f</i>, are reciprocated, and at the backward -movement of the cutter the pawls engage the ratchet-wheels, -and belts, <i>b</i>, are moved a distance equal to the -movement of the knife.</p> - -<p>The jelly-box, <i>n</i>, is fixed to side bars, <i>A</i>, by brackets at -its ends, as shown in Fig. 18, and is placed above the cutter -and the plate, <i>e</i>, so that when the plate, <i>f</i>, is drawn out from -beneath the box the plate, <i>e</i>, takes its place for holding up -the block of jelly.</p> - -<p>In operation the block of jelly is placed in box <i>n</i>, resting -on plate <i>e</i>. A frame provided with netting—such as is used -for drying glue—is placed on belts, <i>b</i>, beneath the box, and -the shaft, <i>h</i>, being rotated by power, the cutter moves forward -and cuts a slice from the jelly. The plate, <i>f</i>, at the -same time moving away, the slice passes upon the frame, -and the return movement taking place, plate <i>f</i> is carried -beneath the jelly-block, and the belts being at the same -time moved, the frame is carried forward in position for receiving -the next slice apart from the first one. In this -manner, as slice after slice is cut, they are spread on the -frame, and the frames, when filled, are carried to the end of -the machine for removal. The plate, <i>f</i>, is adjustable, so as -to vary the thickness of the slices cut.</p> - -<p>The box may be divided into cells of any size desired, so -that each movement of the knife will cut a slice from the -bottom of each cell, and the box extending the full width -of the drying frames, all the slices cut at once will be -properly spread.</p> - -<p>In order to keep the plates, <i>e f</i>, moist, so as to prevent -the glue-jelly from sticking thereto, there are fitted at the -sides of the jelly-box, <i>n</i>, open-bottomed boxes, <i>o</i>, containing -fibrous material soaked with water, which, resting on plates, -<i>e f</i>, keeps their surfaces moist.</p> - -<p>The machine saves the troublesome and expensive work -of spreading the jelly by hand, as has been heretofore -practiced.</p> - -<p><span class="pagenum" id="Page_62">62</span></p> - -<p>The knife is to be attached to plate, <i>e</i>, in any suitable -manner, and the surface of plate, <i>f</i>, may be corrugated, so -as to slide on the jelly more readily.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 19.</span></div> -<img src="images/i_p062-1.jpg" alt="" /> -</div> - -<p>The cutting apparatus patented by M. Devoulx, of Marseilles, -is much used in France. The machine stands upon -a board or table, upon which are fastened two uprights, -far enough apart to allow of the passage of a truck carrying -the glue, which is cut into cakes by blades or wires stretched -between the uprights.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 20.</span></div> -<img src="images/i_p062-2.jpg" alt="" /> -</div> - -<p>Fig. 19 shows the perspective elevation of the machine -with its truck. The upper part is filled up for the reception -of the glue to be cut up into cakes. The sides are<span class="pagenum" id="Page_63">63</span> -omitted in this figure in order to admit of a better explanation -of the separate parts.</p> - -<p>Fig. 20 gives the same view, except that the truck, -the upper part of which is closed, is between the uprights, -and contains the glue to be cut.</p> - -<p>Fig. 21 represents the moment the wires have passed -through the glue and cut it into cakes. In all the figures, <i>a</i> -is the wooden frame upon which the machine rests, <i>b</i> the -table-plate fastened to the frame, <i>c</i> and <i>d</i> are the uprights, -between which the cutting wires are stretched, and <i>f</i> the -truck carrying the glue.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 21.</span></div> -<img src="images/i_p063-1.jpg" alt="" /> -</div> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 22.</span></div> -<img src="images/i_p063-2.jpg" alt="" /> -</div> - -<p>Figs. 22 and 23 show the truck by itself, <i>g</i> representing -the bottom, and <i>h</i> the back, which is provided with slight -grooves, into which the wires catch to assure the entire cutting -through of the block of jelly; <i>i</i> is the upper part of the -truck, which opens by means of a hinge, and when closed -is fastened with the pin, <i>k</i>. This upper part of the truck -is fastened to the back part of the truck by means of a<span class="pagenum" id="Page_64">64</span> -screw, which allows it to be set higher or lower, according -to the size of the block of jelly to be cut; <i>m</i> is the bar of a -rack fastened to the truck, and serves for moving the latter. -The driving gear, <i>n</i>, the shaft of which carries a crank, <i>o</i>, -catches into the rack.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 23.</span></div> -<img src="images/i_p064.jpg" alt="" /> -</div> - -<p>Two boards, one on each side of the truck, serve to keep -the block of jelly in position, and guide the truck.</p> - -<p>With this machine 120,000 to 130,000 cakes can be cut -in five or six hours.</p> - - -<h4>3. DRYING THE CAKES OF GLUE.</h4> - -<p>Drying the cakes is without doubt the most precarious -part of the manufacture. The jelly contains a large quantity -of water which, to prevent decomposition of the jelly -before it is converted into glue, must be evaporated as -quickly as possible. In favorable weather, drying may be -accomplished either in the open air or in covered sheds.</p> - -<p>Drying in the open air is connected with many inconveniences, -for if the sun strikes the cakes of jelly when they -still contain a large quantity of water, they may become -soft so as to run through the meshes of the net, or they may -dry so quickly as to prevent them from contracting to their -proper size without numerous cracks and fissures. If frost -supervenes, numerous cracks may be formed in the cakes -from the congelation of their water, or a shower of rain may -cause much work and damage. In consideration of all -these inconveniences, it is best to conduct the operation in -a drying-room.</p> - -<p>To insure a constant circulation of air, which is abso<span class="pagenum" id="Page_65">65</span>lutely -necessary for the expulsion of the aqueous vapor -caused by the evaporation of such a large quantity of water, -the drying-room should be at least 10 feet high, even if intended -for summer use only, and the windows be provided -with Venetian blinds so as to shut out the sun, if necessary, -without disturbing the circulation of air.</p> - -<p>To dry the cakes in heated rooms in winter is a more -difficult matter, as provision has to be made for the removal -of the aqueous vapor, and a current of warm dry air has to -be kept up at the same time. But such a room is an absolute -necessity for the manufacturer on a large scale, who, in order -to carry on his business without interruption throughout -the entire year, must be independent of the changes of wind -and weather.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 24.</span></div> -<img src="images/i_p065.jpg" alt="" /> -</div> - -<p>The size of the drying-room should be proportional to -the daily production. Constructions are fitted up with the -requisite frames for the reception of the glue cakes, and are -heated by steam pipes arranged along the walls. In the -floor in the immediate neighborhood of the steam pipes are -openings, which can be opened and shut at pleasure, for the -admission of fresh dry air. The latter on entering the -room is heated, and after passing over the frames and absorbing -water from the glue cakes, escapes through openings -in the ceiling to a space above it from which it is withdrawn -by means of ventilators in the roof. A constant -change of air must be kept up. The quick drying of the -glue is of the utmost importance, as otherwise the jelly -putrefies either entirely or partially, and the glue acquires -a turbid and mean appearance. Too much heat causes the -cakes to bend and crack. The cakes are laid upon wide<span class="pagenum" id="Page_66">66</span>meshed -nets of twine stretched in frames 6½ to 8 feet long -and 3¼ feet wide. Fig. 24 represents the form of nets -commonly used. The nets are placed upon frames, such as -shown in Fig. 25, arranged around the drying-room in the -neighborhood of the steam pipes and air flues. As the -cakes have to be occasionally turned upside down upon the -nets, the latter must be placed at convenient distances, one -above the other in the frames.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 25.</span></div> -<img src="images/i_p066.jpg" alt="" /> -</div> - -<p>The use of twine netting has been found to be attended -with many disadvantages, the principal ones of which are -given by S. Rideal as follows:</p> - -<p>1. “Being freely handled in the making, the netting is -almost always impregnated with dangerous organisms -which penetrate the moist glue cakes, and cause moulding -or putrefaction. When this occurs, it is usually attributed -to a state of the atmosphere, but if the cakes are examined, -the alteration will generally be found to originate along the -lines made by the netting. The fault could be cured by -sterilizing the net for an hour at 212° to 248° F. in a hot -oven, but besides the expense, the fibre is thereby weakened. -Moreover, the spores of a few bacteria, such as -<i>Bacillus subtilis</i>, which is widely distributed and has the -power of liquefying gelatine, will bear a heat of 248° F. for -over an hour, and still be capable of growing.</p> - -<p>2. “However smooth the fibre, the glue will stick in -places, leaving small remains, which being hygroscopic,<span class="pagenum" id="Page_67">67</span> -become ’sour,’ and set up the objectionable bacterial changes -in the subsequent batches.</p> - -<p>3. “Owing to sagging, rotting, scouring, or wearing into -holes, the life of cotton or hemp netting is so short that the -constant renewal is a considerable item. A whole batch is -frequently spoilt by the fault of a net. In some works, -heaps of old netting are found, which become very putrid -in the rain and sun, and give rise to mysterious bacterial -inroads in the factory. In others they are regularly burnt -under the boilers.</p> - -<p>4. “The considerable overlap or selvedge required for -securing the edges of the net involves a waste of the area, -and also some difficulty in refixing.”</p> - -<p>For this reason metallic netting has been largely adopted. -The best material has proved to be a heavily galvanized -iron-wire netting having no less than 15 to 25 per cent. of -its weight of zinc. It can be strengthened by longitudinal -and transverse wires or ribs. It must be examined by the -microscope to see that it is perfectly free from holes or -cracks, and should last at least two years in constant use.</p> - -<p>The temperature of the drying-room requires careful regulation, -and should never be allowed to rise above 68° to -77° F., as otherwise the glue would soften and run through -the meshes of the net, or adhere so firmly to the twine as to -require the nets to be put in hot water for its separation. -Dryness of air is of far greater importance in the drying -process than a high temperature. To promote this dryness -of air and prevent the aqueous vapor from condensing, -evaporating, and again condensing upon the cold walls of -the room, they are wainscoted. Thus protected by a bad -conductor, they acquire a higher temperature, and the -aqueous vapor, instead of being precipitated upon them, is -carried off by the air-currents.</p> - -<p>As the cakes placed in the immediate neighborhood of -the steam pipes and near the floor where the dry air enters, -dry quickest, the nets containing them are shifted after<span class="pagenum" id="Page_68">68</span> -some time to a higher part of the drying-room and their -former places filled with cakes still wet. When the cakes -are dry, they are finally desiccated in a room at a higher -temperature, which serves to harden and improve them.</p> - -<p>In modern times drying-rooms have been almost entirely -abandoned and in this country long drying galleries are -used, sometimes 250 feet in length and 6 to 8 feet square, -with traveling platforms on rails carrying the sheets of glue -on stout galvanized netting. Wood is found to be a better -material for the galleries than stone or brick.</p> - -<p>Figs. 26 to 28 show an apparatus for drying glue which -is the invention of W. A. Hoeveller.</p> - -<p>Fig. 26 is a plan section, and Fig. 27 a side elevation in -section, of this improved drying-alley. Fig. 28 is an end -view in section.</p> - -<p>The form and arrangement are as follows:—</p> - -<p><i>A B</i> represent the two parts of the alley, separated by the -partition <i>C</i>, which is shorter than the alley, so as to leave -a communicating space at both ends.</p> - -<p>At the front of section <i>A</i>, is located a blower, <i>D</i>, actuated -by a steam-engine or other motor, <i>E</i>, also located within -the walls of the alley. The whole current from blower <i>D</i>, -is directed through section <i>A</i> of the alley, whence it turns -into section <i>B</i>, and comes back through it, to be again -drawn into and forced out of the blower into section <i>A</i>. -By this means the contained air of the alley is set in continuous -motion through the two sections successively, and -as the structure is made as air-tight as practicable in such -cases, the air remains unchanged until the doors <i>F</i>, or either -of them, are opened to discharge the vitiated air and let in -the fresh.</p> - -<p>In sections <i>A</i> and <i>B</i>, is placed the railway <i>a a</i>, to admit -of the convenient movement of the contents in process of -drying, which are generally set on cars or buggies.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 26.</span></div> -<img src="images/i_p069-1.jpg" alt="" /> -</div> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 27.</span></div> -<img src="images/i_p069-2.jpg" alt="" /> -</div> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 28.</span></div> -<img src="images/i_p069.jpg" alt="" /> -</div> - -<p>In section <i>A</i>, in front of blower <i>D</i>, is placed a steam or -other heating device, <i>G</i>, which may be of any form or<span class="pagenum" id="Page_69">69</span> -design adapted to allow the air from blower <i>D</i> to pass -through it and to heat such air while passing therethrough. -The inventor prefers the radiating coil for such purpose, -the steam entering at <i>b</i>, and emerging at <i>c</i>. At the other -end of the alley, which by the double construction is in -section <i>B</i>, just back of the blower and heating-coil, there is -placed a condensing-coil, <i>H</i>, of a construction similar to coil -<i>G</i>, and having inlet <i>d</i>, and outlet <i>e</i>. Through this condenser -there is kept flowing a refrigerating liquid or brine, -which renders the condenser very cold. The continuous -current of air from the blower passes over the contents of -the cars or trays in the alley and takes up moisture in its -passage. After such passage the air is charged with moisture -and comes in contact with the coils of the condenser <i>H</i>,<span class="pagenum" id="Page_70">70</span> -upon which the charge of moisture is condensed, and the -air emerges dry again, enters the blower, and is again made -the vehicle by which the moisture of the glue or other contents -is transported to and deposited on the condenser.</p> - -<p>In drying glue by this method do not use the steam-coil -at the first stage of drying a charge, as the drying should -not be effected too rapidly; but as soon as the product -begins to stiffen properly, admit the steam to the coil <i>G</i>, -and thereafter the operation is continuous, as above described.</p> - -<p>By doubling up the alley into two sections, as shown, the -inventor is enabled to erect the alley in a more contracted -space. In a length of ninety feet he obtains the benefit of -a single alley one hundred and eighty feet long. Section -<i>B</i> may, if desired, be located on top of section <i>A</i>. Doors -may be located wherever desired, to facilitate the movement -of the trays or cars and the placing of them in and their -removal from the alley.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 29.</span></div> -<img src="images/i_p070.jpg" alt="" /> -</div> - -<p>By the above apparatus the drying can be perfected in a -very much shorter time than can be done by the old alleys, -and operations can be conducted in hot weather without -hindrance from the condition of the atmosphere.</p> - -<p>In cases where the atmosphere is dry enough to dispense -with the heater and the condenser, the inventor can throw -the doors <i>F</i> wide open, extend the partition <i>C</i> out to that -end of the alley, and then preserve a continuous forced draft -of sufficiently dry air in both alleys for the purpose. As<span class="pagenum" id="Page_71">71</span> -there are many days during the year fine enough to give -reasonably dry air, operations can be conducted with the -blower alone in this way, and thus economize the steam and -the refrigerating-brine.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 30.</span></div> -<img src="images/i_p071.jpg" alt="" /> -</div> - -<p>Figs. 29 and 30 show a longitudinal section, with upper -and ground floor plans of a modern drying-house, as given -by Thomas Lambert. In the ground floor the whole of the -liquors are jellied in coolers, and then cut into cakes by -the two cutting machines in the centre. Here a hoist, <i>E</i>, -Fig. 30, is placed which carries the cut cakes on “glasses” -to the floor above. This forms the drying-floor, and is partitioned -off in three divisions, running nearly the length of -the building. The two outer divisions form the tunnels -proper, and at the ends are fixed two powerful revolving -fans, driven at high speed and drawing the air through the -tunnels at a high rate. At the opposite ends of the fans -are fixed a series of 6-inch pipes, heated up by waste steam, -and the air passing between is warmed up to any desired -temperature, of necessity below 78° F. In the center pass<span class="pagenum" id="Page_72">72</span>age -a number of girls are employed in transferring the cut -cakes to the nets, which are built upon a carriage running -on a small railway. The carriage with the complement -of filled nets is run to the end of the division, transferred to -the lower railway, <i>C</i>, by which it is carried either to the -right or left hand tunnels as desired; the glue when dried -on the nets is run to the other end and by another lower -railway brought to the middle division, and ultimately by -the hoist raised to a large store-room, seen in section, where -the glue is sorted and bagged. At the end of the store-room -is placed a grinding machine, and all the off-color and -twisted cakes are ground to a powder and sold as powdered -glue. The manufacturer by varying the size of the cake, its -thickness, and its color, may make any number of grades -from the same boiling.</p> - -<p>Fleck proposes to accelerate the drying of glue by utilizing -the water-absorbing power of some salts, such as Epsom -and Glauber’s salts, ammonium sulphate, crystallized acid -sodium sulphate, etc., for the purpose of withdrawing water -from the glue cakes. For the practical application of this -principal a shallow, water-tight, wooden box is required. -The bottom of the box is sprinkled with a layer of the -water-absorbing salt about half an inch deep, and covered -with a moist linen cloth. Upon this is placed the jelly cut -into sheets and also covered with a moist cloth, a layer of -salt being finally scattered over it. After standing for a -few hours, the box is slightly inclined and the salt solution -allowed to drain off through a hole in the bottom, the -dropping ceasing in from 12 to 18 hours. If now the upper -cloth is taken off with its layer of salt, the glue beneath it -will be found so far deprived of its moisture that when placed -in the sun or exposed to other heat, it will become completely -dry in a short time without either melting or spoiling, -and in winter may be laid upon drying-floors with the -same result. The salt-solution formed may be evaporated -to crystallization and the salt thus obtained be again used.</p> - -<p><span class="pagenum" id="Page_73">73</span></p> - -<p>After the treatment with the salt, the jelly contains 70 -to 75 per cent. of anhydrous glue, while the content in jelly -not thus treated varies between 7 and 28 per cent. according -to the concentration of the liquor from which it has -been derived. It is claimed that the adhesive power of the -glue is not injured by this treatment.</p> - -<p>Commercial glue must not only be thoroughly dry, but -should also present a good appearance, showing especially -lustre. However, after drying, the glue is dull, spotted, -dusty and sometimes even mouldy. To give a good lustrous -appearance the dry cakes are dipped in warm water and -replaced upon the nets to dry.</p> - -<hr class="chap" /> - -<p><span class="pagenum" id="Page_74">74</span></p> - - - - -<div class="chapter"></div> -<h3><a name="CHAPTER_V" id="CHAPTER_V">CHAPTER V.</a><br /> - -<small>MANUFACTURE OF BONE-GLUE.</small></h3> - - -<p>The manufacture of bone-glue differs chiefly from that of -skin-glue in the processes employed for the conversion of -the glue-yielding tissues. This conversion may be effected -by boiling the bones with water, or subjecting them to the -action of steam, or by first extracting their mineral constituents -with acid, and boiling the remaining cartilaginous -mass with water until dissolved.</p> - -<p>When the finest quality of all varieties of glue, namely, -colorless gelatine, is to be manufactured, the bones should -not be comminuted in a stamping mill, because in consequence -of the unavoidable development of heat, they acquire -a slightly empyreumatic odor which adheres to the gelatine -prepared from them, and cannot be removed.</p> - -<p>In factories working on a small scale, the bones are comminuted -by hand, being placed upon a grate-like support -of heavy iron rods and crushed with a wooden hammer, the -face of which is studded with big-headed nails. In larger -establishments the crushing rolls previously described are -used, and in order to lessen the effect of heating as much as -possible, the crushed bones are allowed to fall directly into -a vessel filled with water.</p> - -<p>Fat being a very valuable constituent of bones, it should -be gained as completely as possible, by boiling or steaming -the bones, or by extracting them by means of a solvent, -such as benzine or carbon disulphide.</p> - - -<h4>1. BOILING BONES.</h4> - -<p>This is the older and more incomplete process of extracting -the fat. The bones are placed in a boiler, covered with<span class="pagenum" id="Page_75">75</span> -water so that it stands a few inches deep over them, and the -whole is boiled over an open fire. The melted fat collecting -on the surface of the water is skimmed off. By boiling, a -portion of the glue-yielding substance is, of course, converted -into glue, and passes into the water. In order not -to lose this glue, the same water is repeatedly used for boiling -fresh quantities of bones, and is finally used for feeding -pigs. By this method 4 to 5 per cent. of fat is at the utmost -obtained.</p> - -<p>The bone fat obtained by direct boiling of the bones, is, -if entirely fresh material has not been used, of very inferior -quality. It is dark yellow to deep brown and of a disagreeable -odor. It is only fit for certain purposes, and to -be utilized in the manufacture of soap has to undergo a -special process of purification, whereby it is rendered white -and odorless.</p> - - -<h4>2. STEAMING BONES.</h4> - -<p>In order to obtain a larger quantity of fat than is possible -by boiling, the bones are preferably steamed, <i>i. e.</i>, subjected -to the action of high-pressure steam. This is effected -in a closed cylinder of thick boiler-plate, into which steam -of ½ to 1 atmosphere pressure is admitted. The cylinder is -provided with a perforated false bottom upon which the -bones are placed. By steaming for two or three hours, all -the fat is extracted from the bones and collects, together -with the condensed water formed by the steam coming in -contact with the cold bones, underneath the false bottom. -However, by the continued action of high-pressure steam -upon the bones, a considerable portion of the glue-yielding -tissue is converted into glue, which passes into the resulting -liquor. This, however, is no drawback if only fat and glue -are to be obtained from the bones, since by continued -steaming, a liquor still richer in glue results, and need only -be evaporated. But, as a rule, the greater portion of the -bones, especially the granulated parts, are to be utilized in<span class="pagenum" id="Page_76">76</span> -the manufacture of animal charcoal, and, hence, great care -has to be observed in steaming.</p> - -<p>Animal charcoal is produced by calcining bones in vessels -from which the air is excluded, whereby the glue-yielding -tissue is converted into carbon, which is distributed -upon the bone-earth. Since the value of animal -charcoal depends on the quantity of carbon it contains, a -product prepared from bones highly steamed, will evidently -be of little value, as a considerable portion of the glue-yielding -substance has been converted into glue.</p> - -<p>If the bones are to be used for the production of animal -charcoal they should be subjected to the action of high-pressure -steam only long enough to extract the fat, but the -resulting glue-liquor is very thin and difficult to work. -The watery glue-liquor is first drawn off, and the fat which -comes last is caught by itself. The thin glue-liquor is -evaporated in vacuum.</p> - - -<h4>3. EXTRACTION OF BONES.</h4> - -<p>To avoid the loss of glue-yielding substance which is unavoidable -in steaming bones, even if only for a short time, -in many plants the fat is now extracted by treating the -bones with benzine or carbon disulphide. No loss of glue-yielding -substance being involved by this process, bones -thus treated yield the best quality of animal charcoal.</p> - -<p>The fat obtained by extraction with carbon disulphide -has such a disagreeable odor as to render it almost worthless. -In addition this solvent is very volatile, consequently -very inflammable, and is also very poisonous. For these -reasons its use for the extraction of fat has been almost entirely -abandoned.</p> - -<p>Figs. 31 and 32 show an apparatus for the use of benzine -which is the invention of Messrs. Wm. Adamson and -Charles F. A. Simonis, of Philadelphia, Pa. It is for the -purpose of treating animal and vegetable substances with -hydrocarbons for extracting therefrom oily, fatty and resin<span class="pagenum" id="Page_77">77</span>ous -matter; and the object of this invention is to cause -hydrocarbons to trickle through such substances instead of -flooding the same, so that it will take up the oily, fatty and -resinous matter without any of the albuminous or gelatinous -ingredients.</p> - -<p>Fig. 31 is a vertical section of apparatus wherewith this -invention may be carried into effect; Fig. 32, an inverted -plan view of part of Fig. 31.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 31.</span></div> -<img src="images/i_p077-1.jpg" alt="" /> -</div> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 32.</span></div> -<img src="images/i_p077-2.jpg" alt="" /> -</div> - -<p><i>A</i> is a vessel, preferably of cylindrical form, and containing -an upper perforated diaphragm, <i>a</i>, and lower perforated -diaphragm, <i>b</i>, the former having a central opening, through -which the material to be treated may be introduced between -the two diaphragms, and this opening having a detachable -perforated cover, <i>d</i>.</p> - -<p>On the top of the vessel there is an opening, <i>e</i>, furnished -with a detachable cover, <i>f</i>, and at the bottom of the vessel -there is an outlet-pipe, <i>h</i>, furnished with a suitable cock or -valve, <i>i</i>.</p> - -<p><span class="pagenum" id="Page_78">78</span></p> - -<p>Liquid hydrocarbon, preferable such as is of a volatile -character—benzine, benzole, or gasoline, for instance—is -introduced into the vessel above the diaphragm <i>a</i> through -a pipe, <i>H</i>, and perforated ring, <i>I</i>, or otherwise, the hydrocarbon -passing through the diaphragm and falls in a shower -on the substance contained in the vessel.</p> - -<p>The hydrocarbon will trickle through the mass, taking -up whatever oily, resinous, or fatty matter it comes in contact -with until it falls through the lower diaphragm into -the space <i>D</i>, whence it may be drawn off from time to time -through the outlet-pipe, <i>h</i>.</p> - -<p>In extracting oily, fatty, or resinous matter from vegetable -or animal substances by hydrocarbons, it has been -the practice either to subject them to hydrocarbon vapors, -or to immerse or steep the substances in hydrocarbon until -the latter takes up the oily, fatty, or resinous matter.</p> - -<p>The vapor plan is preferable in treating wet animal substances, -such as offal; but for dry vegetable or animal -matter—seeds, for instance, or the residuum resulting from -the rendering of tallow—we prefer the plan before described.</p> - -<p>The flooding or steeping of animal or vegetable matter in -liquid hydrocarbon results in a mixture or emulsion of -gelatinous, albuminous, and fatty or oily matter, combined -with animal or vegetable tissues, the whole forming an -amalgamated mass; hence, whatever fatty or oily matter is -extracted is accompanied by more or less of the suspended -gelatine or albumen, either of which is more difficult to remove -from the oil or fat, and has a tendency to discolor the -same.</p> - -<p>This difficulty, it has been found, can be obviated by preventing -the hydrocarbon from remaining in a quiescent -state in contact with the material; in other words, by -causing it to trickle through the mass, which, by this plan, -retains its granular condition, and gives out its oil or fat to -the hydrocarbon without the albuminous or gelatinous -matter.</p> - -<p><span class="pagenum" id="Page_79">79</span></p> - -<p>In the apparatus before described, for instance, an occurrence -of the objectionable flooding of the material, tending -to bring about the results previously mentioned, is obviated -by never permitting the extract in the lower portion of the -vessel <i>A</i> to reach the lower diaphragm <i>b</i>. By drawing off -the extract from time to time, any impediment to the free -discharge of the hydrocarbon with such oily and resinous -matter as it has taken up, through the lower diaphragm, is -prevented, and a continuous dripping of the hydrocarbon -through the mass secured.</p> - -<p>The extract obtained by the trickling or filtering process -is much more concentrated than that obtained by the steeping -and flooding process.</p> - -<p><i>Adamson’s Method for Treating Substances with Hydrocarbon -Vapor for the Purpose of Extracting Oils, Fats, etc.</i> This -improvement is intended to prevent the fetid or other odors -imparted to the vapor from the substances treated from -being recommunicated to the said substances, and to the -extracts obtained therefrom through the medium of the -vapor from the re-used hydrocarbon. The vapor is obtained -from benzine, benzole, etc.</p> - -<p>Fig. 33 represents, partly in section, the apparatus -whereby the invention may be carried into effect.</p> - -<p><i>A</i> is a vessel in which the substances have to be treated -by hydrocarbon vapor, the said substances being introduced -into the vessel through a manhole, <i>x</i>, and deposited -on a perforated diaphragm, <i>B</i>, the manhole being provided -with a suitable cover. A steam-coil, <i>D</i>, is placed in the -vessel in a space beneath the diaphragm, and liquid hydrocarbon -is introduced into the said space, and is there -vaporized by the steam-coil. The vapor rising through the -perforated diaphragm permeates the substance upon the -same, so as to extract therefrom the oily, fatty, or resinous -matter, which passes downward through the diaphragm -into the space below the same, whence it may be drawn off -from time to time through the discharge-pipe <i>j</i>. Liquid<span class="pagenum" id="Page_80">80</span> -hydrocarbon may be introduced from a tank, or from a -source explained hereafter, into the top of the vessel <i>A</i>, so -that it will pass through the material and be vaporized -when it reaches the coil; the said material being in this -case subjected to a downward current of liquid hydrocarbon -and an upward current of vapor.</p> - -<p>Previous to this invention it was Mr. Adamson’s practice -to cause the vapor, after acting upon the substances in the -vessel, to pass through a worm in a condenser, the lower -end of the worm communicating with the vessel, <i>A</i>, beneath -the diaphragm, as shown in Fig. 35, p. 85, so that -the hydrocarbon was used over and over again. But in -practice this has been found objectionable in many cases -for the following reason:—</p> - -<p>In treating animal offal, for instance, for the extraction -of fats, fetid odors are imparted to the hydrocarbon vapor, -and remain, to a considerable extent, in the condensed -vapor when the latter is restored to the vessel <i>A</i>; hence, the -fetid odors were recommunicated both to the fatty extracts -and to the material. The same objections have been experienced -in treating meat for preservation and vegetable -matter for the extraction of oil by hydrocarbon vapor.</p> - -<p>This difficulty is obviated in the following manner: The -vapor-pipe <i>D´</i> communicates with a vessel <i>H</i> at the top of -the same, and the vapor is met by numerous small jets of -cold water—in the present instance, from a perforated -tubular ring, <i>m</i>, into which the water is forced through a -pipe <i>n</i>.</p> - -<p>Many different appliances may be used, such as roses, -revolving jets, etc., for causing a spray through which the -vapor must pass, and by which it must be condensed. The -result of this will be a supply, <i>I</i>, of tainted water on the -bottom of the vessel, <i>H</i>, and a quantity, <i>J</i>, of washed and -purified hydrocarbon above the water, the latter having -taken up the fetid odors.</p> - -<p>The washed hydrocarbon may be drawn off through a<span class="pagenum" id="Page_81">81</span> -pipe, <i>g</i>, into any suitable vessel, and thence introduced -through the pipe <i>h</i> into the vessel <i>A</i>, or may pass directly -into the latter to be again vaporized therein, the vapor after -permeating the material and passing through the pipe <i>D´</i> -being simultaneously condensed and washed in the vessel -<i>H</i>, preparatory to being returned in the condition of purified -liquid hydrocarbon to the vessel <i>A</i>.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 33.</span></div> -<img src="images/i_p081.jpg" alt="" /> -</div> - - -<p>By the practice of this process, the inventor is enabled to -obtain a purer extract than heretofore, and, at the same -time, the substances acted upon are more free from noxious -odors.</p> - -<p>Changes may be made in the apparatus shown in Fig. -33, as, for instance, the vessel <i>A</i> may consist of a horizontal<span class="pagenum" id="Page_82">82</span> -hollow cylinder, and the vaporizing of the hydrocarbon -may be accomplished otherwise than by a steam-coil.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 34.</span></div> -<img src="images/i_p082.jpg" alt="" /> -</div> - -<p><i>Adamson’s Method for Treating Substances with Liquid Hydrocarbon -for the Purpose of Extracting Oils, Fats, etc.</i> This -invention relates to a method of treating animal and vegetable -substances with liquid hydrocarbons, such as benzene, -benzole, etc., for the purpose of extracting from such substances -oils, fats, etc.</p> - -<p>The object of this improvement is to prevent the fetid -and other odors imparted to the liquid hydrocarbon by the -substances treated from being recommunicated to the substances -and to the extracts therefrom by the liquid hydrocarbon -when re-used.</p> - -<p>In Fig. 34, there is shown a sectional view of apparatus -whereby this invention may be carried into effect.</p> - -<p><span class="pagenum" id="Page_83">83</span></p> - -<p><i>A</i> is a vessel into which the substances to be treated are -introduced through a manhole, <i>x</i>, provided with a suitable -detachable cover, and through an opening in the upper -perforated diaphragm, <i>B</i>, a detachable perforated plate, <i>b</i>, -being placed over the opening after the substances have -been passed through the same, the substances being supported -by the lower perforated diaphragm, <i>B´</i>, beneath -which is a space for receiving the extract and liquid hydrocarbon -after the latter has percolated through the mass in -the vessel. The extract, which occupies the lowest position -in the vessel, may be removed therefrom from time to time -prior to being purified by distillation or otherwise. The -liquid hydrocarbon is permitted to pass from time to time -through a pipe, <i>d</i>, into a vessel, <i>D</i>, where it is met by jets -of water from a pipe, <i>f</i>, the hydrocarbon and water being -thoroughly agitated in the vessel by a revolving paddle-wheel, -<i>E</i>. This washing of the liquid hydrocarbon may -be accomplished by different appliances. For instance, the -paddle-wheel may be dispensed with, and water forced upward -into the vessel from below in the form of numerous -small jets. The water and hydrocarbon after this washing -operation are permitted to pass into the subsiding-vessel, -<i>H</i>, the hydrocarbon being above and the water below, the -fetid and other odors divided by the hydrocarbon from the -substances in the vessel, <i>A</i>, having, during the washing -operation, been transferred to the water, which may be -drawn off from time to time.</p> - -<p>The washed and purified hydrocarbon may be pumped -directly through a pipe, <i>m</i>, into the vessel, <i>A</i>, to be re-used -for treating the substances therein; or it may be pumped, -first, into a reservoir, and permitted to flow from the same -into the said vessel, <i>A</i>.</p> - -<p>More or less hydrocarbon is wasted by being drawn off -with the extract, and to make up for this loss a supply may -be introduced at intervals from a tank through the pipe, <i>h</i>.</p> - -<p>By the practice of the process described above, the in<span class="pagenum" id="Page_84">84</span>ventor -is enabled to obtain a purer extract than by the -ordinary process of treating substances with liquid hydrocarbon. -At the same time the substances treated will be -much more free from noxious odors than when the hydrocarbon -is used over and over again without washing.</p> - -<p>It is not essential strictly to adhere to the apparatus -shown in Fig. 34, as the construction of the apparatus will, -in fact, depend in a great measure on the locality in which -it is to be situated.</p> - -<p><i>Adamson’s Process for Removing Hydrocarbons from Substances -which have been treated therewith.</i> This process consists -of washing from animal and vegetable substances the -hydrocarbon which they retain after being treated therewith -for the extraction of oils, fats, etc., and for other purposes.</p> - -<p>Different apparatus may be employed for carrying out -this process, and it may be conducted in the same vessel in -which the material is treated with hydrocarbon.</p> - -<p>The vessel, which is shown in Fig. 35, has been found to -answer well for this purpose.</p> - -<p>This vessel is furnished with a suitable detachable cover, -<i>a</i>, and with two perforated or wire-gauze diaphragms, <i>b</i> and -<i>d</i>, both extending across the interior of the vessel, one near -the top and the other near the bottom of the same.</p> - -<p>A steam-coil, <i>B</i>, communicating with any adjacent steam-generator, -is contained in the vessel below the lower diaphragm, -to vaporize the hydrocarbon, the vapor passing -through the substance between the two diaphragms and out -through a pipe, <i>D</i>, which passes through a condenser, <i>E</i>, -the latter restoring the hydrocarbon to a liquid form, in -which it is reconveyed to the vessel through a pipe, <i>D´</i>.</p> - -<p>In practicing the washing process a pipe, <i>m</i>, to introduce -water into the vessel, and one or more outlet-pipes, <i>n n′</i>, -two in the present instance, are necessary. There may also -be a pipe, <i>p</i>, through which air can be introduced into the -vessel, under the circumstances explained hereafter.</p> - -<p>When the treatment of the material in the vessel with<span class="pagenum" id="Page_85">85</span> -hydrocarbon vapor or liquid hydrocarbon has been completed, -steam is cut off from the coil <i>B</i>, the pipes <i>D</i> and <i>D´</i> -are closed, and the cover <i>a</i> may be removed.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 35.</span></div> -<img src="images/i_p085.jpg" alt="" /> -</div> - -<p>Water is now admitted through the pipe <i>m</i> to the space -in the vessel below the diaphragm <i>d</i>, and the cocks of the -outlet-pipes <i>n n′</i> are opened.</p> - -<p>The water permeates the material, passes upward through -the same, and carries with it the hydrocarbon, the latter -having a tendency to rise with the water.</p> - -<p>As the water, and whatever hydrocarbon accompanies it,<span class="pagenum" id="Page_86">86</span> -pass through the upper diaphragm, <i>b</i>, the hydrocarbon will -at once rise to the surface, and will pass through the upper -outlet-pipe, <i>n</i>, into any suitable receptacle, the water passing -off through the lower outlet-pipe.</p> - -<p>If this mode of separating the hydrocarbon from the -water is practiced, the admission of water to the vessel -should be such in respect to the outflow that the liquid will -remain at or near a uniform level, that is, the surface of the -liquid should bear the relation shown in the drawing to the -upper outlet.</p> - -<p>The water and hydrocarbon, however, may be drawn off -indiscriminately into a suitable receptacle, and then separated -by decantation; but it is advisable in all cases that the -water should extend above the mass of material in the vessel, -so that the hydrocarbon can at once rise to the surface -as it escapes from the substance.</p> - -<p>When the material is of such a character as to be closely -packed and not easily displaced by the upwardly-flowing -water (and this is especially the case with seeds which have -been treated with hydrocarbons), it is necessary to agitate -the mass, so that the water can gain access to every part -thereof. This agitation the inventor prefers to effect by air -under pressure introduced through a pipe, <i>p</i>, although -mechanical appliances may be used for the purpose.</p> - -<p>It will be understood that the process may be conducted -in a vessel separate from which the substances have been -treated with hydrocarbon. A vessel similar to that shown, -for instance, but without the coil and pipes, <i>D D´</i>, may be -used, and may be furnished with trunnions (shown by -dotted lines) and adapted to bearings, so as to be easily -tilted when its contents have to be removed; or the vessel -may have an opening near the lower diaphragm for the -withdrawal of its contents, a suitable detachable door being -adapted to the opening.</p> - -<p><i>F. Seltsam’s apparatus.</i> In this process the solvent is -boiled with the bones, previously coarsely crushed and the<span class="pagenum" id="Page_87">87</span> -dust sifted out, in a strong closed vessel, so as to obtain a -higher temperature, greater penetration and avoidance of -loss. The vapor ascending condenses in the pores, extracts -the fat and collects under the false bottom as a layer of -solution which is subsequently distilled. The apparatus is -shown in Fig. 36. The cylinder, <i>A</i>, is capable of withstanding -a pressure of 10 atmospheres, and serves for the -generation of steam and as an extracting vessel. It is filled -with bones and hermetically closed. The required quantity -of solvent is then brought by means of the pump, <i>B</i>, -from the reservoir, <i>C</i>, through the pipe, <i>D</i>, into the cylinder, -<i>A</i>, and the latter is heated. The vapors formed force -the air through the pipe, <i>E</i>, into the condenser, <i>F</i>, where -any vapor which may be carried along is condensed and -passes through the pipe, <i>G</i>, back into the reservoir, <i>C</i>.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 36.</span></div> -<img src="images/i_p087.jpg" alt="" /> -</div> - -<p>When all the air has been expelled from the apparatus -and the pores of the bones, the cock on the pipe, <i>E</i>, is -closed. The cylinder, <i>A</i>, is then heated so that a pressure -of a few atmospheres prevails in it. The vapors now act -energetically upon the bones, the dissolved fat collecting -upon the cylinder; the cock on the pipe, <i>H</i>, is then opened, -and the superheated fluid discharged under high pressure<span class="pagenum" id="Page_88">88</span> -into the distilling apparatus, <i>J</i>, and the solvent is distilled -off from the fat by means of steam. The vapors of the -solvent pass through the pipe, <i>K</i>, into the condenser, <i>F</i>, -and from there back into the reservoir, <i>C</i>.</p> - -<p>When the manometer on <i>A</i> indicates no pressure, the -cock on the pipe, <i>H</i>, is closed and the cylinder, <i>A</i>, again -heated, the pipe, <i>E</i>, being open, so that any solvent still -adhering to the bones may escape to the condenser, <i>F</i>.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 37.</span></div> -<img src="images/i_p088.jpg" alt="" /> -</div> - -<p>Figs. 37 and 38 illustrate Seltsam’s apparatus as improved -by Th. Richter, whereby the operation becomes -entirely free from danger, the vaporization of the solvent -being effected by steam only, and the work is carried on -continuously.</p> - -<p>There are two extracting vessels, <i>A</i> and <i>B</i>, of thick -boiler-plate, and provided with false bottoms, <i>G</i>, upon -which the bones are placed, steam being admitted into the -space between the true and false bottoms. The extracting -vessels are surrounded by the jackets, <i>C</i>, and are further -provided with the vacuum gauges, <i>E</i>, and the air-cocks, <i>F</i>.</p> - -<p><span class="pagenum" id="Page_89">89</span></p> - -<p>There are, in addition, two other vessels, <i>H</i> and <i>J</i>, which -contain water, a vessel, <i>K</i>, for the solvent, and an air-pump, -<i>L</i>. The operation is carried on as follows:</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 38.</span></div> -<img src="images/i_p089.jpg" alt="" /> -</div> - -<p>The extracting vessels, <i>A</i> and <i>B</i>, are charged with bones, -all the cocks, with the exception of <i>M</i> and <i>N</i> closed, and -the air-pump, <i>L</i>, is set in motion, whereby a vacuum is -formed in <i>A</i>. When this is sufficiently large, water is admitted -from <i>H</i> through the cock <i>O</i> into the space <i>P</i>. The -water-cock is then closed and the steam-cock, <i>Q</i>, opened. -The steam entering the space, <i>R</i>, brings the water in <i>P</i> to -the boiling-point, and the air-pump sucks off the steam -formed after the cock, <i>N</i>, is opened. The air-pump is then -stopped and all the cocks closed, except <i>S</i>. The solvent -now passes from the vessel, <i>K</i>, into the space <i>P</i>, and after -closing the cock <i>S</i>, is evaporated by the admission of steam -into <i>R</i>. The water-cock is then opened and cold water admitted -into the jacket <i>C</i>, the solvent saturated with fat -being thereby condensed in <i>P</i>. The water is then discharged -from <i>C</i> and steam introduced into <i>R<sub>1</sub></i>, whereby the -solvent is evaporated and forced into the extracting vessel -<i>B</i> by means of the air-pump, <i>L</i>, after closing the cocks <i>M</i> -and <i>V</i>.</p> - -<p>The process is then repeated in <i>B</i>, after a vacuum has -been created in the same manner as in <i>A</i>.</p> - -<p>In the meanwhile the vacuum in <i>A</i> is interrupted by -opening the air-cock <i>F</i> and the fat drawn off through <i>P</i> by -opening the cock <i>U</i>.</p> - -<p><span class="pagenum" id="Page_90">90</span></p> - -<p>The bones freed from fat are removed through the manhole -<i>D</i>, and <i>A</i> is charged with fresh material while the -operation is carried on in <i>B</i>. Thus the operation is continuous, -the solvent passing without any loss whatever from -one extracting vessel to the other.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 39.</span></div> -<img src="images/i_p090.jpg" alt="" /> -</div> - -<p>Alfred Leuner’s apparatus. Fig. 39, works on the Soxhlet -principle, without pressure, using solvent and steam simultaneously. -The bones are placed in <i>A</i> above the perforated -false bottom <i>B</i>. <i>D</i> is a steampipe by means of which the -bones are steamed as a preliminary, the surplus steam es<span class="pagenum" id="Page_91">91</span>caping -through the outlet pipe <i>E</i>. After steaming, water -and benzine are run in from the reservoir <i>F</i>, into the space -under the false bottom, and heated by the steam coil <i>P</i>. -The vapors evolved are condensed in the worm <i>K</i>, and at -first run back over the bones through the cock <i>L</i>, the vapor -passing upwards to the worm through <i>R</i>, and the condensed -liquid being divided into separate streams by the spreading -plate <i>O</i>. After some time the cock <i>G</i> is opened so that the -condensed liquid runs into the reservoir <i>F</i>, instead of flowing -back into <i>A</i>. When all the solvent has volatilized -nothing but water condenses in the worm, which is known -by means of a sampling cock attached to <i>A</i>, the draw-off -cock <i>E</i> is then opened and the watery gelatinous solution -and oily matter run off into a suitable separating receptacle. -The bones in <i>A</i> are then discharged through a manhole, -and <i>A</i> being refilled, the whole operation is repeated.</p> - -<p><i>Extraction with hydrochloric acid.</i> If the bones are to be -chiefly worked for glue, extraction with hydrochloric acid, -which has been referred to in Chapter III, under “Bones -and Cartilages” may be highly recommended, the bones -being thereby freed from their mineral constituents and the -glue-yielding substance remaining behind in a pure state. -The bones are allowed to remain in contact with the acid -till they are flexible and translucent. This may be readily -recognized by laying upon the material in the vat a bone -split in two. When the latter by the treatment with acid -shows the characteristic appearance of swollen cartilage, -<i>i. e.</i>, has become translucent, extraction may be considered -complete.</p> - -<p>The solution is then drawn off through a tap immediately -above the bottom of the vat into stoneware vessels, -and conveyed to the evaporating pans. The tap is then -closed and enough water to cover the cartilage is admitted -into the vat, and the whole allowed to stand for a few -hours in order to extract as much as possible the solution -of bone-salts remaining in the cartilage. The fluid is then<span class="pagenum" id="Page_92">92</span> -drawn off. It is a quite concentrated solution of bone-salts -and, mixed with an equal volume of hydrochloric acid, -may be used for the extraction of fresh quantities of bones, -or be mixed with the fluid first drawn off and evaporated.</p> - -<p>The further washing of the cartilage is effected by repeatedly -pouring water over it, the operation being continued -until the water running off shows no acid reaction. -Washing has to be done very carefully, since glue-solution -obtained from cartilage containing but a very small quantity -of acid will not congeal. It is, therefore, advisable to -add to the last wash-water 1 per cent. of soda, this quantity -being quite sufficient for the neutralization of the last traces -of acid.</p> - -<p><i>Sulphurous acid process.</i> In this country sulphurous acid -is largely employed in the manufacture of glue derived -from bones. When ordinary bones are treated with a current -of moist sulphurous acid gas, they absorb from 10 to -12 per cent. of their weight of the gas in the course of 12 -hours. The amount may increase to 15 or 20 per cent. on -longer treatment, but the excess will then disappear on -exposure to air. Messrs. Grillo and Schroeder of Düsseldorf, -who patented this process in 1894, believe that this is -simply due to the calcium phosphate present in the bones, -and remark that an absorption of 11 to 12 per cent. on the -gross weight amounts to 16 or 17 per cent. of the inorganic -constituents, and corresponds to the equation:</p> - -<p> -Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> + SO<sub>2</sub> + H<sub>2</sub>O = 2CaHPO<sub>4</sub> + CaSO<sub>3</sub>,<br /> -</p> - -<p>the sulphurous acid simply acting in the same way as sulphuric -acid does in the manufacture of superphosphate, but -being a milder acid than sulphuric, the alteration of the -organic constituents which are available for glue-stock can -be almost entirely avoided. The acid phosphate is soluble -in water, therefore the bones after treatment are easily disintegrated -by boiling water when a large portion of the -lime remains in the sediment, while the gelatine is dissolved.</p> - -<p><span class="pagenum" id="Page_93">93</span></p> - -<p>The process as commercially conducted is very similar to -the well-known sulphite method of treating paper pulp, and -is carried on in iron cylinders or better in close wooden vats -lined with lead.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 40.</span></div> -<img src="images/i_p093.jpg" alt="" /> -</div> - -<p>The gas is usually generated in an impure form, with a -large admixture of air and carbonic acid, by combustion of -pyrites and coal, of crude sulphur, or even of only highly -pyritous fuel.</p> - -<p>On the other hand, since it is well established that the -absorption of a diluted gas is less ready, and is more wasteful -than that of a gas in a pure state, the employment of a -definite quantity of sulphur dioxide in a concentrated state, -either prepared by the regulated burning of sulphur, or the -decomposition of sulphuric acid, yields more regular results,<span class="pagenum" id="Page_94">94</span> -and a product of better quality. Liquid sulphur dioxide, -which is now obtainable at a moderate price and in quantity, -has the advantage that it yields a continuous current -of pure gas of any required rapidity by simply opening a -valve, and that the exact amount used can be ascertained -by taring the containing vessel before and after the operation -(S. Rideall).</p> - -<p>The washed bones are brought into the above-mentioned -cylinder or vat and treated with a saturated solution of sulphurous -acid. The duration of the action of the acid varies -according to the condition of the material and can only be -determined by experience. The result of the process is a -liquor almost as clear as water, which, after evaporation in -the vacuum pan, is equal as regards clearness and lustre, to -the best quality of glue prepared from waste of hide and -skin. The fat extracted from the bleached bones is lighter -in color and has not the disagreeable odor of ordinary bone -fat, and consequently brings a better price.</p> - -<p>For the generation of sulphurous acid Dr. Bruno Terne, -of Mass., has constructed a very simple apparatus shown in -Fig. 40. The sulphur is burned in <i>S</i>; <i>A</i> is the escape pipe -of stone; <i>T</i>, the collecting reservoir; <i>P</i>, the steam-pump -for acid; <i>R</i>, chimney for the sulphur burner.</p> - - -<h4>4. CONVERSION OF CARTILAGE INTO GLUE.</h4> - -<p>The conversion into glue of the swollen cartilage obtained -by treatment with hydrochloric or sulphurous acid -may be effected by continued boiling in open pans or in an -apparatus recommended by Wm. Friedberg, and shown in -Fig. 41.</p> - -<p>The boiler <i>K</i> of thick boiler-plate has a diameter equal to -its height. Underneath the perforated false bottom <i>S</i>, which -serves for the support of the bones, lies a perforated steam -coil <i>R—D</i> for the introduction of steam. To this steam -coil is fitted a branch-pipe <i>d</i>, which reaches into the upper -portion of the boiler into which also enters the water-pipe<span class="pagenum" id="Page_95">95</span> -<i>W</i>. The apparatus is further fitted with a water-gauge, an -air cock, sampling cock and manhole for the introduction -of the cartilage.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 41.</span></div> -<img src="images/i_p095.jpg" alt="" /> -</div> - -<p>The mode of operation with this apparatus is as follows: -The boiler is filled three-quarters full with cartilage. -Enough water to fill the boiler one-quarter full is then admitted -through the pipe <i>W</i>, and the steam-cock <i>D</i> opened. -The steam passing out through the numerous perforations -in the coil <i>R</i>, is at first condensed in the water, but soon -brings the latter to the boiling-point, and from this stage on -begins the formation of glue. The glue dissolves in the -water, and a sample of the solution is from time to time -drawn off through the sampling cock and tested as to its -concentration. When the solution possesses the required -concentration, the admission of steam through <i>R</i> is interrupted, -and the cock <i>d</i> of the branch-pipe opened, as well -as the cock of the discharge pipe <i>H</i>, the latter being opened -gradually. The discharge pipe <i>H</i> is connected with the -perforated plate <i>F</i>, which is covered with a closely-woven<span class="pagenum" id="Page_96">96</span> -cloth and thus acts as a filter, retaining all the solid particles -suspended in the glue solution.</p> - -<p>By opening the cock <i>d</i> of the branch-pipe, the steam-pressure -acts only upon the surface of the fluid, the latter -being consequently pressed with great force through the -filter-cloth.</p> - -<p>When the hissing noise caused by escaping steam indicates -that all the fluid has been removed from the boiler, -the cock <i>d</i> of the branch-pipe is closed, and through a rose -fitted above the boiler, water is allowed to flow upon the -latter. By this cooling the greater portion of the steam in -the boiler is condensed and water may be admitted -through <i>W</i>.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 42.</span></div> -<img src="images/i_p096.jpg" alt="" /> -</div> - -<p>The operation of glue-boiling is then commenced anew -by admitting steam into the steam coil, and continued -until the cartilaginous mass has been reduced to about one-third -of its original bulk, when the apparatus is opened, -fresh material introduced, and the whole operation repeated.</p> - -<p>In order to be able to replace the filter without having -to empty the entire apparatus, it has been given the shape -shown in Fig. 42. The upper portion of the discharge-pipe<span class="pagenum" id="Page_97">97</span> -<i>A</i> is connected with the lower portion by the box-screw <i>H</i>. -In the latter is inserted a short cylinder, <i>C</i>, with a perforated -bottom upon which is placed the filter-cloth; the -latter is kept in position by the ring <i>R</i>.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 43.</span></div> -<img src="images/i_p097.jpg" alt="" /> -</div> - -<p>For every apparatus two of the above-described filters -will be required. If, notwithstanding a full steam pressure, -the glue solution runs off sluggishly, it is indicative of the -pores of the filter being choked up. The screw-box <i>H</i> is -then removed, the filter taken out and replaced by another -one.</p> - -<p>The glue solution discharged from the apparatus is in -most cases sufficiently clear to allow of its being immediately -evaporated. However, for the production of a particularly -fine quality of glue, it is advisable to clarify the -solution by settling. As the liquor has to be kept warm to<span class="pagenum" id="Page_98">98</span> -allow of the solid particles to settle, W. Friedberg recommends -the use of the apparatus shown in Fig. 43. It consists -of an iron cylinder with a diameter equal to one-third -of its height. The front of the cylinder is furnished with a -number of cocks placed at equal distances from each other, -and also with a pipe in the slightly conical bottom. It is -surrounded by a wooden jacket, the intermediate space -being filled with a bad conductor of heat. By this arrangement -the liquor is kept warm and in a liquid state for -several hours, giving ample time for the solid bodies held -in suspension to settle on the bottom. The condition of -the liquor is from time to time tested by allowing a small -quantity of it to run into a glass from the lowest cock in -front. If the sample is perfectly clear, the liquor may be -drawn off. If, however, after several hours’ standing only -the upper portions of the liquor are clear, while the lower -ones are still turbid, further clarification by this means is -impossible. The upper portions of the liquor are then used -for finer qualities of glue and the lower ones for inferior -grades.</p> - -<p>By treating the cartilage with high-pressure steam, a -liquor is obtained which on cooling congeals to quite a -solid jelly, and it might be immediately brought into the -forming-boxes, cut into cakes, and dried. However, as the -drying of the glue is one of the most difficult operations for -the glue-maker, it is of great advantage to obtain the liquor -in as high a state of concentration as possible in order to -obtain a solid jelly, which causes the least difficulty in drying. -For this purpose the liquors leaving the clarifying -vat with a strength of about 20 per cent. dry glue are -evaporated down to a strength of about 32 per cent. in -winter, and 35 per cent. in summer. Evaporation may be -effected in open pans or in vacuum.</p> - -<p>Fig. 44 shows the arrangement of an open evaporating -pan. The copper pan <i>P</i> has the form of a shallow cylinder -with a slightly conical bottom, in the lowest point of which<span class="pagenum" id="Page_99">99</span> -is the discharge pipe for the concentrated liquor. During -the operation the discharge pipe is closed by the ball-valve -<i>V</i>, which can be raised by the lever contrivance <i>M</i>. The -pan is surrounded by an iron steam-jacket; the steam -passes in at <i>D</i>, and the condensed water runs off at <i>A</i>. <i>H</i> -is a sampling cock for taking samples to test the concentration -of the liquor.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 44.</span></div> -<img src="images/i_p099.jpg" alt="" /> -</div> - -<p>To prevent the workroom from being filled with steam -arising from the pan, the latter is covered with a hood of -wood which terminates in the pipe <i>S</i> projecting above the -roof, and a narrow pipe <i>R</i> branching off from the steam -pipe <i>D</i> passes into <i>S</i>.</p> - -<p>When vapors commence to arise from the liquor, the -cock on the pipe <i>R</i> is slightly opened whereby a jet of steam -is blown into the pipe <i>S</i>, the latter then acting as an exhauster, -and the vapors in the hood <i>C</i> are carried along by -the jet of steam. By this arrangement no vapor passes into -the workroom and steam is also very rapidly evolved from -the surface of the liquor.</p> - -<p><span class="pagenum" id="Page_100">100</span></p> - -<p>Sufficient steam should be admitted to the pan for the -liquor to give out an abundance of vapor without, however, -being brought to the boiling-point, as in that case foam -would be formed and the liquor in cooling yield a product -full of blisters. When the liquor has acquired the proper -degree of concentration, the admission of steam to <i>D</i> and <i>R</i> -is interrupted and the valve <i>V</i> having been raised the liquor -is run into the cooling-boxes. The latter are of wood lined -with zinc, or better of stout zinc or heavily galvanized iron. -They hold about ½ cwt. and are of two shapes: one deep -and nearly square, another long and shallow, for quick -cooling of clear liquors. Iron should not be used, as it -readily rusts and causes discoloration of the glue.</p> - -<p>Cooling is effected by cold water where it is available, -but often merely by cold air, aided by fans or blowers, in a -room protected from heat or frost. According to S. Rideal, -refrigerating machines are now also employed, which, by -the evaporation of liquid gases, such as ammonia, sulphurous -or carbonic acid, reduce a tank of brine to near freezing-point. -The temperature should not be allowed below 33° -or 34° F., for if frozen the jelly is hard and difficult to cut. -The brine circulates in iron pipes placed near the ceiling of -the room; they must be kept as clear as possible of ice and -dirt, and the cooling house should be scrupulously clean -and sweet.</p> - -<p>Spiral evaporators are recommended by Thomas Lambert -as forming a ready and economical means of evaporation. -The evaporator consists of a spiral steam coil, made -of copper, and 2 inches in diameter, revolving on a centre -shaft; the lower half of the coil is covered with the glue-liquor -in the trough. The shaft rests on two plummer-blocks, -one receiving the steam, and the other discharging -the spent steam and condensed water. The shaft is hollow -to the first coil, and the steam is thus conveyed to the -spiral. From the last coil to the end of the plummer-block -the shaft is also hollow, and in that portion resting<span class="pagenum" id="Page_101">101</span> -on the block two openings are made. In the inside of the -plummer-block, two openings are bored to the outside, each -forming a covered channel; as the shaft revolves, all the -holes directly face each other at intervals, and thus allow -any condensed water in the coils to be blown through. -From 25 to 28 coils are generally used in each spiral. The -glue-liquors are fed into the trough at one end, and have a -temperature of 75° F.; the temperature of the evaporated -liquor is 85° F. In the rather slow passage through the -trough, the liquors receiving the heat of the revolving coils -are raised in strength from 20 per cent. to 32 per cent. dry -glue, at which point they are ready for jellying.</p> - -<p><i>Vacuum pans</i> are much used in this country for evaporating -glue-liquors, though there are some complaints made of -the great waste owing to spray and froth being carried off -in the steam. As is well known the boiling-point is -lowered by increasing the pressure on the surface of a fluid. -By enclosing water in a vessel connected with a constantly -working air-pump, it is brought to the boiling-point by -heating to between 95° and 104° F. The construction of -vacuum pans is based upon this principle, and such -apparatus is largely used in many manufacturing processes -for evaporating to a certain degree fluids, for instance, sugar -solutions, which readily become decomposed at a higher -temperature. Vacuum pans are also very suitable for the -evaporation of glue-solution, especially in plants working -on a large scale.</p> - -<p>Fig. 45 represents an elevation of a vacuum pan for evaporating -glue and gelatine liquors as described by Thomas -Lambert. The pan is built of steel plates, and lined outside -with wood work, and rests on a floor constructed of -rolled steel plates, supported on four columns, with a stairway -leading to the working platform. One half of the -lower part is shown in section, giving a view of the coils by -which the pan is heated. The various parts are as follows: -<i>A</i>, the body of the pan; <i>B</i>, the dome; <i>C</i>, exhaust pipe lead<span class="pagenum" id="Page_102">102</span>ing -from the dome to the condenser; <i>D</i>, condenser; <i>E</i>, air -or vacuum pump; <i>F</i>, storage tank for glue or gelatine -liquors, warmed with steam coil; <i>G</i>, supply pipe leading -from storage tank to vacuum pan; <i>H</i>, discharge valve; <i>I</i>, -barometer gauge for indicating vacuum; <i>J</i>, inlet steam pipe -for supplying the coils; <i>K</i>, exhaust end of vacuum coils; -<i>L</i>, iron staircase; <i>M</i>, steel floor.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 45.</span></div> -<img src="images/i_p102.jpg" alt="" /> -</div> - -<p>The accessories to the pan are placed in a convenient -position above the working floor and include a steam gauge -for noting the pressure in the coils, a gauge for indicating -the height of the liquor in the pan, vacuum gauge <i>I</i>, as -shown in the drawing, air-cocks and a thermometer. The -pan is also fitted with a small apparatus, by which portions -of the boiling liquor can from time to time be drawn, without -disarranging the vacuum, so that the progress of evaporation -can be ascertained.</p> - -<p>In working the pan, the storage tank <i>F</i> is first filled with -the weak glue liquors to be evaporated; the valve on the -supply pipe <i>G</i> is then closed, and the vacuum pump set in -motion; a few strokes are sufficient to reduce the internal -pressure, and the valve of the supply pipe is then opened,<span class="pagenum" id="Page_103">103</span> -and the liquor allowed to fill up the pan to the desired -mark on the gauge. The valve is then closed, the steam-inlet -valve <i>J</i>, supplying the coils, opened. As the heat -from the coils spreads through the liquor, the vacuum pump -is kept steadily at work reducing the inside pressure to -within 2 to 2½ inches of a perfect vacuum, as seen on the -barometrical scale. In this vacuum the liquor will boil at -120° to 130° F., and the boiling is continued until the withdrawn -samples, as tested by the glue-meter, show the desired -strength. The pump is then stopped, the vacuum broken -by opening the air-cocks, and the concentrated liquor is run -through the valve <i>H</i> into suitably arranged receiving tanks, -for supplying the trays or glasses for jellying.</p> - -<p>For economical working with large quantities of weak -liquors, a combination of two, three and even four vacuum -pans, forming the double, triple and quadruple effect evaporators, -have been designed for concentration purposes. -The triple effect is, however, the system mostly in use, and -consists of a grouping of three cylindrical pans, each connected -by suitably arranged piping, by which the vapors of -the first pan are conveyed to and made to heat the coils of -a second pan, the resulting vapors from the second, passing -on to the third pan, for a similar purpose. All the pans -are connected with powerful pumps, producing a nearly -absolute vacuum in each. The liquor is evaporated to a -given density in the first pan, and then passed on to the -second, and ultimately to the third, at which stage 80 per -cent. of its water will have been driven off.</p> - -<p>To obtain in all cases a product of equal concentration, -it is advisable to have an instrument which will indicate -the amount of dry glue in the solution. (Fig. 46.)</p> - -<p>By immersing a glass aerometer in the glue-liquor, the -percentage of glue is indicated by a scale registering from -0 to 70 per cent. with the jelly or glue solution at a temperature -of 167° F.</p> - -<p>To measure the temperature quickly, a thermometer is<span class="pagenum" id="Page_104">104</span> -added, and for the execution of the entire test, a sheet-iron -vessel consisting of a large and two small tubes, <i>a</i>, which -when not in use, serve for the reception of the glass instruments -contained in a special case. For testing, the small -cylinder is placed in the large tube, <i>a</i>, and filled with jelly -by means of the cap which serves as a cover. The large -tube is filled with hot water to bring the jelly to the required -temperature. The two instruments are then -immersed in the tubes filled with glue-liquors to be tested, -and temperature as well as percentage can be readily -read off.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 46.</span></div> -<img src="images/i_p104.jpg" alt="" /> -</div> - -<p>The evaporated and cooled glue-liquor is cut into cakes -and dried in the same manner as previously described.</p> - - -<h4>5. PROCESS FOR THE SIMULTANEOUS UTILIZATION OF BONES -FOR FAT, BONE-MEAL AND GLUE.</h4> - -<p>Manufacturers frequently sort the bones in such a way -that materials of different quality are obtained. Thick, -compact bones are utilized for the manufacture of animal<span class="pagenum" id="Page_105">105</span> -charcoal, a comparatively small percentage of bone-meal -resulting in crushing such bones.</p> - -<p>Incompact, porous bones, on the other hand, yield not -only crummy animal charcoal of less value, but in stamping -also a larger percentage of bone-meal than compact -bones. Hence they are as a rule directly worked for fat, -glue and steamed bone-meal, no attempt being made to -convert them into such granular pieces as are suitable for -the production of charcoal.</p> - -<p>For this purpose, the bones are first broken by a crusher -or mill into coarse pieces, and the fat extracted by a special -process or together with the glue in one operation. The -latter method would seem to be the most suitable, time and -labor being thereby saved, but it must be borne in mind -that fat extracted by itself brings a much better price than -that obtained by steaming, and besides the yield of glue is -larger from steamed bones which have been previously -degreased.</p> - -<p>The crushed bones—whether degreased or not—are subjected -to the action of high-pressure steam. The apparatus, -Fig. 47, used for this purpose consists of a cylinder of thick -boiler-plate, 10 to 13 feet high and 3 to 4 feet in diameter. -<i>E</i> and <i>A</i> are manholes, which can be closed steam-tight. -The pipe <i>D</i> leads to the steam-boiler and opposite to <i>D</i> is a -short pipe, <i>H</i>. The cylinder is further fitted with the perforated -false bottom, <i>S</i>, and the bent pipe, <i>L</i>.</p> - -<p>As a rule, four to six, and in larger plants even more, of -such cylinders are combined to a battery. In this case the -discharge pipe, <i>L</i>, terminates in a common collecting vessel, -and the steam-pipes, <i>D</i>, branch off from a main steampipe. -The battery may be enclosed by brickwork, but is -preferably placed upon a suitable foundation and surrounded -by woodwork, the intermediate space between -woodwork and cylinders being filled with sawdust. This -plan offers the best means of keeping the heat together, and -the further advantage that, in case one of the cylinders be<span class="pagenum" id="Page_106">106</span>comes -defective, it can be readily taken out and replaced -by a new one.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 47.</span></div> -<img src="images/i_p106.jpg" alt="" /> -</div> - -<p>In order to be able to fill the cylinders rapidly and with -the least expenditure of power, it is advisable to place the -bone-crusher at such a height that the crushed bones fall -directly into carriages which are run upon a small railway -over the charging holes of the cylinders, and emptied. In -front of the manholes, <i>A</i>, for discharging the bones is also a -railway, so that the crushed bones can be directly emptied -into carriages and conveyed to the stamping mill.</p> - -<p>The cylinder having been filled with bones, is closed -steam-tight. The cock, <i>H</i>, is then opened and steam admitted -by opening the cock <i>D</i>. The steam passing in at<span class="pagenum" id="Page_107">107</span> -first, is cooled off by coming in contact with the bones and -condensed to water. However, the temperature in the -cylinder soon becomes so high that the steam is no longer -condensed and, having first expelled the air in the cylinder -through the pipe <i>H</i>, it escapes through the latter in the form -of a powerful jet. When this is the case <i>H</i> is closed and -high-pressure steam allowed to act upon the bones.</p> - -<p>The fat contained in the bones melts and trickles down. -On the bottom of the cylinder collects a fluid which contains -glue, is of a milky turbidity due to admixed drops of -fat, and with a quite thick layer of fat upon its surface. -From time to time—about every hour—the cock <i>L</i> is -slightly opened. By the pressure of the steam the glue-liquor -is expelled with great force through the pipe <i>L</i>, the -latter being closed when by the peculiar noise it is noticed -that only steam escapes.</p> - -<p>Steaming and the occasional discharge of melted fat are -continued until on testing a sample of the liquor running -off, it is noticed to be free from fat. The liquor in the -cylinder is then expelled by the pressure of steam, the -steam-cock <i>D</i> closed, the manhole <i>A</i> opened, and steam -again admitted through <i>D</i>. By the steam-pressure the -greater portion of the bones in the cylinder is expelled -through the manhole <i>A</i>. The bones coming from the -cylinder are pliable and soft, and, after drying, are readily -converted by grinding into bone-meal.</p> - -<p>For the manufacture of animal charcoal it is of the -utmost importance that steaming should be interrupted at -the time when the bones are completely degreased. If, -however, only fat, glue and bone-meal are to be produced, -steaming may advantageously be continued for a longer -time.</p> - -<p>The longer the bones are subjected to the action of high-pressure -steam, the more complete the conversion of glue-yielding -substance into glue will be. To be sure, the bone-meal -obtained from such bones will contain somewhat less<span class="pagenum" id="Page_108">108</span> -nitrogen than the product from bones not steamed quite so -long. However, the content of phosphates will in both -cases be the same, and on this depends, in the main, the -fertilizing value of bone-meal.</p> - -<p>The fluid discharged from the cylinder consists of a mixture -of glue-liquor and drops of fat. It is run into a large -vat, in which it is kept warm for a few hours, when the fat -rises and collects in a coherent mass on the surface. The -fat is then drawn off through cocks in the upper portion of -the vat, while the glue-liquor is discharged from the bottom -of the vat, running first upon a very fine meshed sieve, -which retains the coarser bodies held in suspension, and -then directly into the evaporator. In the latter the liquor -is evaporated to the desired strength, when it is run into -the clarifying vats, and finally into the cooling vessels.</p> - -<p>With the above-described process, the simultaneous -utilization of the bones for animal charcoal is only possible -if the crushed steamed bones are passed through a sieve for -the purpose of sorting out the granular pieces of suitable -size. However, in the process above described, incompact -bones are, as a rule, used which give but a small percentage -of granulated pieces, and the latter yield an inferior quality -of animal charcoal. It is therefore best to use the steamed -bones from which the fat and glue have been extracted for -the production of bone-meal.</p> - -<p>For the manufacture of animal charcoal, the bones have -to be carefully sorted, fresh bones rich in organic substance -being best for the purpose, and the hardest and thickest -pieces should be selected. Previous to carbonization, the -bones are degreased by extraction with benzine or carbon -disulphide, and then crushed.</p> - -<p>Carbonization was formerly effected in iron pots having -a capacity of about 25 quarts each. However, by this -process a uniform product of good quality cannot be obtained, -and, besides, the total quantity of organic substance -of the bones is lost. At present carbonization is effected in<span class="pagenum" id="Page_109">109</span> -retorts, whereby large quantities of animal charcoal are in -a comparatively short time obtained, and, besides, the products -of destructive distillation can be completely utilized. -An essential product of distillation is a large quantity of -inflammable gases, which can be used for heating the -retort-furnace or for illuminating the entire plant, it being, -however, best to arrange the conduits so that the gases can -be used for either purpose.</p> - -<p>A detailed discussion of the methods for gaining and -further working of the products of distillation is not within -the scope of this work, and only a brief description of a -plant for the manufacture of animal charcoal will here be -given.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig.</span> 48.</div> -<img src="images/i_p109.jpg" alt="" /> -</div> - -<p>Figs. 48 and 49 show the arrangement of a Belgian -retort-furnace, Fig. 48 representing a vertical section -lengthways, and Fig. 49 a horizontal section. The illustrations, -however, are given at different heights in order to -show plainly the arrangement of the fire-place and the -passage of the fire-gases.</p> - -<p>The cast-iron retorts—sixteen in the apparatus shown—are -placed in rows alongside and one after another, so as -to be swept as uniformly as possible by the fire. As will -be seen from Fig. 49 the firing is so arranged that only the -upper portions of the retorts are touched by the flames. <i>B</i> -is the actual fire-place, and <i>A</i> the ash-pit, both being fur<span class="pagenum" id="Page_110">110</span>nished -with closely fitting doors so that the fire may be -properly regulated, and the retorts eventually be exclusively -heated with gas.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig.</span> 49.</div> -<img src="images/i_p110.jpg" alt="" /> -</div> - -<p>The retorts are cylindrical in form, with one end closed. -At the open end is fixed the frame or mouth-piece, which -carries the door swung on a hinge. The door has a slight -projecting rim, some two inches wide, which, with the surface -of the frame, is ground perfectly true; on closing, the -joint is made gas-tight by a lever arrangement.</p> - -<p>The fire-gases escaping from <i>B</i> are distributed as uniformly -as possible by the flues, <i>a</i>, carried underneath the -pans, <i>E</i>, and finally pass out in the direction of the arrows -through a chimney.</p> - -<p>At the time when the extraction of fat was exclusively -effected by boiling the bones, the pans <i>E</i> served for this -purpose, and the spaces <i>D</i>, <i>D</i><sub>1</sub>, <i>D</i><sub>2</sub>, etc., alongside the pans, -which were also heated by the fire-gases, were used for drying -the bones. However, at present, the extraction of fat -is, as a rule, effected by means of benzine or carbon disulphide, -and it is advisable to replace the pans, <i>E</i>, by a bone<span class="pagenum" id="Page_111">111</span>kiln, -and eventually to utilize any waste heat for heating -the evaporators for glue-liquor.</p> - -<p>Fixed to the upper portion of each retort is a pipe, and -these pipes lead into a very wide iron-pipe, <i>T</i>. The products -of destructive distillation escaping from the retorts -combine in <i>T</i>, and besides having a very large diameter, -this pipe must be considerably inclined to avoid the -accumulation of products of distillation in it. To prevent -the products of distillation from depositing in a crystalline -form in <i>T</i>, the latter is covered with a bad conductor of -heat.</p> - -<p>The pipe <i>T</i> is connected with a series of condensing -vessels, <i>D</i>, another series of vessels being placed alongside -the first one, so that the vapors may be conducted, as -desired, into either one of them. Two batteries of such -condensing vessels are required, as one of them has from -time to time to be disengaged in order to be cleansed.</p> - -<p>If the products of distillation would have to overcome -the entire pressure of the column of fluid in the condensing -vessels, their escape from the retorts would be very much -retarded. To avoid this, plates are arranged horizontally a -few inches below the level of the fluid, and the pipes dip -into the condensing vessels only far enough to permit the -escaping vapors to pass under these plates. By this arrangement, -the vapors sweep under the plates and are -absorbed by the fluids, a strong pressure in the apparatus -being thus avoided.</p> - -<p>The condensing batteries may of course consist of any -number of vessels, but as a rule only a sufficient number to -retain all the ammonia is employed, five being in most -cases sufficient for this purpose. The last condenser is connected -with an exhaust-pump, <i>p p</i>, which is kept in motion -by a motor, <i>P</i>.</p> - -<p>The pump removes all the bodies remaining in the last -condenser and forces them, according to the position of the -cock back of the pump, either into a glass-bell or through<span class="pagenum" id="Page_112">112</span> -the pipe <i>H</i> and the nozzles <i>a</i> into the fire-place where they -are burned.</p> - -<p>To obtain the various products of distillation, the condensing -vessels have to be filled with acid, and should -therefore be constructed of lead or at least of sheet-iron -lined with lead. The products to be obtained depend on -the fluid used for filling the vessels; if filled with dilute -sulphuric acid, ammonium sulphate is obtained, which may -be utilized in the preparation of fertilizers. If hydrochloric -acid is employed for the absorption of ammonia, solution of -ammonium chloride is obtained, which may be crystallized -by evaporation.</p> - -<p>The products evolved in the destructive distillation of -bones consist of various hydrocarbons and appear either as -badly-smelling brown liquors—bone-tar—or as illuminating -gas. The vapors contain further considerable quantities of -ammonium carbonate and cyanide of ammonium. To obtain -the latter, the last condensing vessel is filled with green -vitriol solution, the cyanogen compounds remaining behind -in the solution. If the gas escaping from the last condenser -is to be used for illuminating purposes, it is freed from the -greater portion of carbonic acid contained in it by purification -with lime.</p> - -<p>The mode of operation with Belgian retort furnaces is as -follows: The retorts having been filled with comminuted -degreased bones, the doors are closed perfectly gas-tight and -firing is commenced. The pump is set in motion until a -jet of gas blows through the nozzles. When this gas-jet -burns with a luminous flame, destructive distillation of the -bones is in full blast. The pump is then run with such -velocity that the pressure in the interior of the retorts, as -indicated by the manometer, is slightly greater than the -external air-pressure, and the operation is thus continued -so long as inflammable gases escape from the pipe <i>H</i>. The -pump is then stopped, and one-half of the charcoal contained -in the retorts is withdrawn to the canisters placed<span class="pagenum" id="Page_113">113</span> -ready to receive it. The lids of the canisters are then luted -down with a paste of char-dust and water, making an air-tight -joint, and the charcoal is allowed to cool.</p> - -<p>The retorts having been partially emptied, are at once -refilled to the brim with crushed bones and closed gas-tight. -There is but little or no loss of heat between withdrawing -and charging, and distillation of the freshly-introduced -bones commences immediately after charging, and is -finished in a much shorter time than in the beginning of -the operation.</p> - -<p>In making animal charcoal on a large scale there are -obtained from 2000 lbs. of raw material:</p> - -<p> -Animal charcoal, 1180 to 1220 lbs.<br /> -Ammoniacal liquor, 178 to 180 lbs.<br /> -Gas, 222 to 248 cubic yards.<br /> -</p> - -<p>However, these figures refer only to bones degreased by -steaming, whereby a considerable portion of the cartilaginous -substance passes into solution in the form of glue. In -working bones degreased with benzine, larger yields than -those indicated above are as a rule obtained. The ammoniacal -liquor contains on an average 10 per cent. of ammonia. -The gas freed from carbonic acid yields 2.7 times more -light than good coal-gas.</p> - - -<h4>6. PROCESS FOR THE SIMULTANEOUS UTILIZATION OF THE -BONES FOR FAT, GLUE AND CALCIUM PHOSPHATE.</h4> - -<p>This process differs from the one previously described in -that, in addition to the total quantity of fat and glue-yielding -substance contained in the bones, the mineral salts -are also obtained in a pure state, and can be further -utilized.</p> - -<p>The bones are degreased either by extraction with benzine -or carbon disulphide or steaming, the operation in the -latter case being continued so long as fat is yielded by the -bones. The resulting glue-liquor is used in place of water -for boiling the cartilage.</p> - -<p><span class="pagenum" id="Page_114">114</span></p> - -<p>The bones are placed in large wooden vats furnished -with well-fitting lids, and hydrochloric acid of 12 per cent. -poured over them so that they are covered a few inches -deep. With the use of acid of 1.04 specific gravity the -greater portion of the salts contained in the bones will pass -into solution in 48 to 72 hours, when the solution is drawn -off as completely as possible from the vats.</p> - -<p>The residue in the vats is treated with less concentrated -hydrochloric acid and left in contact with it until the bones -are soft and flexible and the thinner pieces have become -translucent, this being a proof that all the mineral salts -have been extracted, and nothing but pure cartilaginous -substance remains behind. The solution is then drawn off, -and after pouring repeatedly small quantities of pure water -over the cartilage to expel the last remnants of acid liquor, -it is subjected to thorough washing until the last traces of -acid have been removed.</p> - -<p>The resulting cartilage is white, translucent, and water-soaked. -If left in this state it would of course soon putrefy, -and it is best to work it at once, or if this cannot be done -it will have to be treated with carbolic acid in the manner -previously described, or dried.</p> - -<p>Drying the cartilage is time-consuming work, and can -properly be done only by artificial heat in kilns. If carefully -protected from moisture, thoroughly dried cartilage -may be kept without injury for any length of time. However, -before being worked to glue, such material has to be -again soaked in water previous to the actual boiling operation, -and this process requires considerable time. It is -therefore best to preserve it in carbolic acid solution, which -only needs to be drawn off when the cartilage is to be -worked, and may be further utilized.</p> - -<p>If boiled in open vessels with water, 6 to 8 hours are -required for the complete disintegration of the cartilage. -In a closed apparatus under high pressure solution is -effected in a much shorter time and the operation pro<span class="pagenum" id="Page_115">115</span>gresses -very smoothly. With proper attention the glue -obtained from bones degreased with benzine and freed from -bone-earth by extraction with hydrochloric acid is, as a -rule, very clear, and may be bleached with sulphurous acid.</p> - -<p>The extraction of the phosphates from bones may be -effected in a very suitable manner as follows: A number of -vats filled with bones are placed in terraces one above the -other, and the acid is allowed to run first into the uppermost -vat. After having been for several hours in contact -with the bones it is discharged into the next vat, fresh acid -being run into the first one, and so on. By this process a -highly concentrated solution of phosphates is in a few hours -obtained in the lowest vat, solution still adhering to the -bones in the other vats being finally expelled by water.</p> - -<p>However, the process of extraction under decreased pressure -is the most advantageous, it requiring least time. For -this purpose the bones are brought into a vessel which can -be closed air-tight and the air is expelled. When but a -slight air-pressure prevails in the vessel, the cock of a reservoir -filled with hydrochloric acid is opened, the external -air-pressure now forcing hydrochloric acid into the extracting -vessel.</p> - -<p>Bones, as viewed under the microscope, consist of a mass -permeated with numerous minute tubes or pores. When -the air is expelled from the vessel containing the bones, the -air in the pores of the latter is rarefied and the hollow -spaces are filled with hydrochloric acid whereby solution of -the phosphates is effected.</p> - -<p>The yield of glue obtained from cartilage after extraction -of the mineral constituents varies according to the compactness -of the bones used. Solid and compact bones yield, on -an average, 15 per cent. of dry glue, but a comparatively -large quantity of calcium phosphate. On the other hand, -porous bones rich in cartilage yield from 20 to 25 per cent. -of dry glue. The liquor obtained by treating the bones -contains, as previously mentioned, calcium phosphate, mag<span class="pagenum" id="Page_116">116</span>nesium -phosphate and calcium chloride in solution, and -may be utilized in the manufacture of fertilizers or of phosphorus.</p> - -<p>For the first purpose which is not very remunerative, but -is not very troublesome, the liquor is treated with milk of -lime until it is slightly alkaline, whereby a finely divided -precipitate of basic calcium phosphate is obtained, whilst -calcium chloride remains in solution. The precipitate is -allowed to settle, separated from the supernatant fluid and -dried. The resulting product contains, on an average, 65 -per cent. calcium phosphate, up to 20 per cent. water and -10 to 15 per cent. calcium carbonate, quick lime and accidental -impurities. It forms an excellent fertilizer.</p> - -<p>If the liquor is to be utilized in the manufacture of phosphorus, -it is evaporated in shallow pans of glazed stoneware. -In cooling crystals of acid calcium phosphate are formed, -which are separated from the mother-liquor. This subject -will be more fully referred to in the next chapter.</p> - -<hr class="chap" /> - -<p><span class="pagenum" id="Page_117">117</span></p> - - - - -<div class="chapter"></div> -<h3><a name="CHAPTER_VI" id="CHAPTER_VI">CHAPTER VI.</a><br /> - -<small>MANUFACTURE OF PHOSPHORUS.</small></h3> - - -<p>In some instances the preparation of phosphorus is carried -on in conjunction with other industries, for instance, -glue-boiling, the preparation of sal ammoniac, yellow prussiate -of potash, etc. Bone-ash is the chief material used by -phosphorus makers. Many manufacturers do not burn the -bones to ashes, but purchase bone-ash, large quantities of -which are brought from South America, especially from the -Argentine Republic.</p> - -<p>The ordinary method of preparing phosphorus includes -the following operations:</p> - -<p>1. Burning the bones and grinding the bone-ash to -powder.</p> - -<p>2. Decomposition of the bone-ash by sulphuric acid, and -evaporation of the acid phosphate previously mixed with -charcoal.</p> - -<p>3. The distillation of the phosphorus.</p> - -<p>4. The refining and purifying the phosphorus.</p> - -<p><i>Burning the bones to ash.</i> The object of the ignition of -the bones is the complete destruction of the organic matter. -The operation is conducted in a kiln very similar to those -in use for burning lime. A layer of brush-wood having -been put on the bottom of the kiln, bones form the next -stratum, and so on alternately. The wood having been -lighted, the combustion of the bones ensues. In order to -carry off the fumes, the smell of which is very offensive, a -hood made of boiler-plate is placed on the kiln, and either -connected with a tall chimney, or the smoke and gases are -conducted into the fire of the kiln and burnt. The white -burnt bones are withdrawn through an opening reserved in<span class="pagenum" id="Page_118">118</span> -the wall on purpose, the kiln being kept continuously in -operation, as in the case with some lime kilns.</p> - -<p>This kind of kiln, however, possesses many disadvantages, -and an improved form, as proposed by Fleck, is shown in -Fig. 50.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 50.</span></div> -<img src="images/i_p118.jpg" alt="" /> -</div> - -<p>The actual combustion chamber consists of a shaft, <i>A</i>, -composed of two inverted cones. In the lowest portion of -the lower cone are four or six apertures, <i>b</i>, which terminate -in inclined channels and serve as air-flues, as well as for -withdrawing the burnt bones. Through the aperture <i>a</i> in -the upper portion of the shaft additional bones may be introduced. -This aperture is covered with a heavy iron lid.</p> - -<p>As will be seen from the illustration, the shaft contracts -towards the top in the form of a retort and passes into a -horizontal channel <i>B</i> which is provided, near its beginning, -with an ordinary fire-place <i>d</i>. The gases and fumes escaping -from the burning bones must pass over the flame of the -fire-place <i>d</i>, and are thereby so completely consumed to -water, carbonic acid and free nitrogen that no odor is perceptible -even in the immediate neighborhood of the kiln.</p> - -<p>In order not to lose the heat yielded by the fire-place <i>d</i> -and the burning vapors, the channel <i>B</i> is covered with -shallow pans <i>P</i>, for the evaporation of such fluids as have -to be subjected to this treatment in the factory.</p> - -<p>The mode of operation with a kiln of this construction is<span class="pagenum" id="Page_119">119</span> -as follows: The shaft is filled two-thirds full with bones and -dry wood split in small pieces is placed in the channels -<i>b</i> and simultaneously ignited. Four or six long hot flames -thus strike the bones, the latter becoming in a short time so -highly heated that they commence to burn briskly and -ignite fresh portions of bones introduced through the aperture -<i>a</i>.</p> - -<p>The white burnt bones in the lower portion of the kiln -are withdrawn, while in a glowing state, by means of iron -hooks; the next layer of bones sinks down and fresh -material is introduced through <i>a</i>, the kiln being thus kept -continuously in operation.</p> - -<p>The quantity of substance which remains after burning -the bones depends of course on the quality of the material -used. Tubular bones of old animals contain the largest -quantity of mineral substance, and give a much more -abundant yield of bone-ash than the spongy bones of -younger animals. On an average 100 parts by weight of -fresh bones yield 55 parts by weight of bone-ash. The -composition of the latter is as follows:</p> - -<p> -Basic calcium phosphate, 80 to 84 per cent.<br /> -Basic magnesium phosphate, 2 to 3 per cent.<br /> -Calcium carbonate, } 10 to 14 per cent.<br /> -Calcium fluoride, }<br /> -</p> - -<p>The bone-ash thus obtained is converted into a coarse -powder by means of machinery, a bone-mill being best -suited for the purpose. Experience has shown that the -granules obtained by grinding should be the size of lentils. -With the use of larger pieces the acid, with which the ash -is treated later on, does not penetrate the entire thickness -of the bone mass and a portion of the latter remains undecomposed. -If the granules are too small, lumps are -formed when the ash is brought together with the acid, and -the mass would have to be constantly stirred in order to, -make the action of the acid effective.</p> - -<p><i>Decomposition of the bone-ash by sulphuric acid.</i> When<span class="pagenum" id="Page_120">120</span> -the basic calcium phosphate—the constituent of the bone-ash -which comes here into consideration—is brought in -contact with an acid of sufficient strength to effect its decomposition, -calcium sulphate (gypsum) is formed, and a -solution of acid calcium phosphate. If the latter be mixed -with powdered charcoal, evaporated to dryness, and the -mixture exposed, with the exclusion of air, to a strong red -heat, the acid calcium phosphate is first converted into calcium -metaphosphate, water being yielded. At this high -temperature the calcium metaphosphate is by the action of -the carbon decomposed to basic calcium phosphate and -phosphorus; the latter escapes in the form of vapor and -may be caught in suitable condensing vessels.</p> - -<p>Hence three separate processes have to be distinguished: -1. The formation of acid calcium phosphate from the basic -calcium phosphate contained in the bone-ash. 2. The conversion -of the acid calcium phosphate into calcium metaphosphate. -3. Decomposition of the calcium metaphosphate, -phosphorus being liberated, while basic calcium -phosphate remains behind.</p> - -<p>Expressed in chemical symbols these processes may be -embodied in the following equations:</p> - -<div class="center"> -<table border="0" cellpadding="4" cellspacing="0" summary=""> -<tr><td class="ct">I.</td> -<td class="ct">Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub><br /><small>Basic calcium<br />phosphate.</small></td> -<td class="ct">+</td> -<td class="ct">2H<sub>2</sub>SO<sub>4</sub><br /><small>Sulphuric<br />acid.</small></td> -<td class="ct">=</td><td class="ct">2CaSO<sub>4</sub><br /><small>Calcium<br />sulphate.</small></td> -<td class="ct">+</td> -<td class="ct">CaH<sub>4</sub>(PO<sub>4</sub>)<sub>2</sub><br /><small>Acid Calcium<br />phosphate.<br />(gypsum).</small></td> -</tr> -</table> - -<table border="0" cellpadding="4" cellspacing="0" summary=""> -<tr><td class="ct">II.</td> -<td class="ct">CaH<sub>4</sub>(PO<sub>4</sub>)<sub>2</sub><br /><small>Acid calcium<br />phosphate.</small></td> -<td class="ct">=</td><td class="ct">2H<sub>2</sub>O<br /><small>Water.</small></td> -<td class="ct">+</td><td class="ct">Ca(PO<sub>3</sub>)<sub>2</sub><br /><small>Calcium<br />metaphosphate.</small></td></tr> -</table> - -<table border="0" cellpadding="4" cellspacing="0" summary=""> -<tr><td class="ct"><a id="III"></a>III.</td> -<td class="ct">3Ca(PO<sub>3</sub>)<sub>2</sub><br /><small>Calcium<br />metaphosphate.</small></td> -<td class="ct">+</td> -<td class="ct">10C<br /><small>Carbon.</small></td> -<td class="ct">=</td> -<td class="ct">10CO<br /><small>Carbon.<br /> monoxide.</small></td> -<td class="ct">+</td> -<td class="ct">Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub><br /><small> Basic calcium<br />phosphate.</small></td> -<td class="ct">+</td> -<td class="ct">P<sub>4</sub><br /></td> -</tr> -</table></div> - -<p>If the processes mentioned under II. and III. would pass -off in the practice exactly as there stated, two-thirds, or 13.3 -per cent., of the total quantity of phosphorus contained in<span class="pagenum" id="Page_121">121</span> -the basic calcium phosphate originally present would be -obtained. However, besides these processes, others take -place which cause a loss of phosphorus. By the action of -the red heat upon the acid calcium phosphate, reciprocal -action takes place between the latter, the water and carbon, -so that a portion of the water is decomposed, and in addition -to carbon monoxide, phosphoretted hydrogen is formed; -the phosphorus contained in the latter must be considered -as lost. Furthermore, a portion of the phosphorus is lost -in the form of vapor, even with the use of the best condensing -contrivances. In consequence of these losses the actual -yield of phosphorus is between 8 and 11 per cent.</p> - -<p>The formation of acid calcium phosphate may be effected -either cold or with the assistance of heat, less time being -required in the latter case. The process without the assistance -of heat is as follows:</p> - -<p>The bone-ash is brought into a lead-lined wooden tank, and -enough boiling water to cover it poured in. It is then thoroughly -mixed with the water by vigorous stirring with -wooden rakes, and the necessary quantity of sulphuric acid -is then run in with constant stirring. When an intimate -mixture has been effected, the tank is covered with a well-fitting -lid and allowed to stand for a few hours. As heat -has been liberated by the introduction of the sulphuric acid -into the mixture prepared with hot water, the entire mass -acquires a high temperature.</p> - -<p>Decomposition is accelerated by stirring the contents of -the tank every six hours, and the process may be supposed -to be finished in 48 hours. With the use of fresh burnt -ash no special phenomena are observed, but if the ash has -been prepared for some time the caustic lime formed in -burning the bones has been completely converted into carbonate -of lime, and the carbonic acid escapes, causing a -slight foaming of the mass. In addition to carbonic acid, -there also escapes a certain quantity of hydrogen fluoride -gas, which is liberated by the decomposition of the calcium<span class="pagenum" id="Page_122">122</span> -fluoride present in the ash. This gas being, even in very -small quantities, very injurious to health, the tanks should -be placed in a thoroughly ventilated room.</p> - -<p>When decomposition is complete, enough water is admitted -for the mass to acquire by stirring a thick milky -appearance, when it is allowed to rest until it clarifies and -a perfectly clear solution of acid calcium phosphate stands -over the precipitate of gypsum. The clear solution is drawn -off, and the sediment washed with water to obtain the solution -retained by it. For this purpose the gypsum is stirred -up with water, and the thick fluid discharged into a filtering -tank. Upon the bottom of the latter is a four-inch-deep -layer of coarse quartz sand; upon this is placed a false -bottom, and upon the latter is spread a linen cloth. The -liquor first running off being milky is poured back into the -tank. However, it runs off clear so soon as the pores of the -filtering cloth have become somewhat contracted by the -gypsum.</p> - -<p>As a rule, the contents of several filtering vats are run -into a common filter, and the mass is repeatedly allowed to -drain off. The dilute solutions thus obtained are evaporated -with the first liquor. A third lixiviation of the sediment -yields a fluid which is used instead of water in a subsequent -operation.</p> - -<p>The residue of gypsum is taken from the filtering tanks, -and may be used as a fertilizer.</p> - -<p>In the warm way the decomposition of the bone-ash is -effected by providing the decomposing tanks with lead -pipes through which steam is introduced, decomposition -being complete in 24 hours, and the first run of solution -of acid calcium phosphate reaches the evaporating pan in a -very hot state. The lixiviation of the gypsum residue is -also effected with water heated by steam, the object of -separating the acid calcium phosphate as much as possible -from the gypsum being thus obtained more completely with -a comparatively small quantity of water than is possible by -washing with cold water.</p> - -<p><span class="pagenum" id="Page_123">123</span></p> - -<p>A suitable apparatus for hot lixiviation is shown in Figs. -51 and 52 in cross section and profile. A lead-lined tank, -13 to 16 feet in diameter and 3½ feet deep, is fitted with a -stirrer furnished with two or four paddles, and closed by a -well-fitting lid. The stirrer is kept in motion during the -entire operation.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 51.</span></div> -<img src="images/i_p123-1.jpg" alt="" /> -</div> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 52.</span></div> -<img src="images/i_p123-2.jpg" alt="" /> -</div> - -<p>A lead steam pipe <i>D</i> furnished with several narrow flat -outlet pipes placed in the direction in which the stirrer -revolves, lies about 4 inches above the bottom of the tank. -<i>W</i> is the pipe for the admission of water, <i>S</i> the lead pipe -connected with the sulphuric acid reservoir, and <i>A</i> an outlet -of boards for carrying off the vapor evolved from the -mass in admitting the sulphuric acid. <i>R</i> is a wooden -hopper, which serves for the introduction of the bone-ash, -and is removed when the tank has been filled, the aperture<span class="pagenum" id="Page_124">124</span> -being closed with a well-fitting wooden lid. The bottom -of the tank is furnished with a lead discharge-cock.</p> - -<p>Water is run into the tank, the bone-ash being simultaneously -introduced through the hopper <i>R</i>, and the stirrer -allowed to revolve slowly to effect an intimate mixture. -Sulphuric acid and steam are then at the same time admitted. -The steam heats the fluid very quickly to the -boiling-point, and assists the action of the stirrer, it passing -out from the outlet pipes in the same direction in which the -stirrer revolves.</p> - -<p>When the required quantity of sulphuric acid has been -introduced, the admission of steam is interrupted, the -stirrer, however, being constantly kept in motion. To keep -the mass hot, steam is for a few minutes admitted every -hour. When the sulphuric acid has acted for 24 hours, -decomposition is complete, and the liquor is discharged -through the cock on the bottom of the tank.</p> - -<p>For the evaporation of the liquor leaden pans are used, -and this operation is continued until the fluid has attained -a specific gravity of 1.45. The pans rest upon cast-iron -plates covered with a layer of clay or sand, to prevent them -from being injured by the fire gases. For heating the -pans, the fire gases escaping from the distilling furnace or -the bone kiln are utilized.</p> - -<p>The fluid having been evaporated to the above-mentioned -specific gravity is now mixed with charcoal powder, or -rather granulated charcoal of the size of small peas, in the -proportion of 20 to 25 parts of charcoal to 100 of liquor. -The mixture is then quickly dried in shallow cast-iron pans -heated by a direct fire. Much sulphurous acid is evolved -during this operation, and provision must be made for -carrying off the vapors arising from the pans.</p> - -<p>When the mass has been dehydrated so far that it balls -together, it is taken from the pan by means of shovels and -brought into a copper cylinder which is furnished with a -sheet-iron sieve-like bottom through which it is forced into<span class="pagenum" id="Page_125">125</span> -another pan. In this second pan the mass is moderately -heated until a sample of it still evolves slight vapors and -when pressed with the hand, after cooling somewhat, appears -still moist without, however, being sticky. The -material is now ready for distilling and 100 parts of concentrated -solution of 1.45 specific gravity and 20 to 25 parts -of charcoal yield about 77 parts by weight of so-called distilling -mass.</p> - -<p>It is best to bring the hot mass as taken from the pan at -once into the retorts, as it is very hygroscopic and, if allowed -to lie exposed to the air, would absorb moisture and require -to be again dried. If it cannot be immediately subjected -to distillation, it is advisable to keep it in sheet-metal boxes -tightly closed.</p> - -<p>The liquor obtained in treating bones for the manufacture -of glue with hydrochloric acid may, as mentioned in Chapter -V, be advantageously utilized in the manufacture of -phosphorus. In order to obtain in crystallized form the -acid calcium phosphate contained in it, the liquor has to -be concentrated by evaporation and as during this operation -hydrochloric acid vapors constantly escape, provision -must be made for their removal from the workroom. The -operation is conducted as follows: The flue of the furnace -for distilling the phosphorus, through which the fire gases -usually escape to the chimney, is made to communicate -with a long low chamber, which can be tightly closed and -connects at the other end with a high chimney. The flue -is fitted with a slide and by opening the latter, the fire -gases are forced to pass through the chamber before reaching -the chimney.</p> - -<p>In the chamber are placed large, well-glazed, earthenware -vessels which contain the liquor to be evaporated, the -vapors evolved being carried off by the fire-gases through -the chimney. Evaporation proceeds quite rapidly, and -fresh liquor is from time to time introduced through an -earthenware pipe, the operation being repeated until a<span class="pagenum" id="Page_126">126</span> -sample taken from the full vessels shows on cooling the -presence of an abundance of crystals of acid calcium phosphate.</p> - -<p>The admission of the fire-gases into the chamber is then -interrupted, and the contents of the vessels are brought into -a wooden tank furnished with a stirrer, which is kept in -constant motion so that when the liquor cools, only small -crystals will be formed. When crystallization is complete, -the mother-liquor is drawn off and again evaporated. By -this operation more crystals of acid calcium phosphate are -obtained, which are, however, less pure than those from the -first liquor. The mother-liquor drawn off from this second -yield of crystals might, on being again evaporated, give -more crystals which, however, would be too impure to be -used to advantage.</p> - -<p>To obtain the calcium phosphate contained in the last -mother-liquor, the latter is exactly neutralized with burnt -lime, a white precipitate of basic calcium phosphate being -thereby obtained. The precipitate is repeatedly washed in -water and allowed to settle, and added in small portions to -the acid liquors obtained by extracting the bones. As -these liquors always contain a considerable quantity of -hydrochloric acid in excess, the basic calcium phosphate, -being in a finely divided state, is readily and completely -dissolved.</p> - -<p>The crystals of acid calcium phosphate are removed from -the crystallizing tanks by means of wooden shovels and -brought into baskets covered inside with stout sack-cloth. -They are left in the baskets until no more mother-liquor -drains off, when the cloths are folded together and the -crystals further freed from liquor by pressure. They are -then heated, with constant stirring, in shallow stoneware -pans until they are so dry as to crumble of their own -accord. In this manner small crystals of a mother-of-pearl -lustre are obtained, which feel like sharp quartz sand and -consist of pure acid calcium phosphate.</p> - -<p><span class="pagenum" id="Page_127">127</span></p> - -<p>This mass is mixed with 25 per cent. of its weight of -granulated charcoal. The mixture is heated until it is -pulverulent, and then treated in the same manner as the -distilling mass from bone-ash.</p> - -<p>In place of stoneware vessels, shallow lead pans may be -used for evaporating the liquor containing calcium phosphate. -To prevent the melting of the lead the pans are -bricked in under a very flat arch, so that the fire gases are -forced to pass close over the liquor, the pans being kept -constantly full. When crystallization is complete the liquor -is drawn off and the pans are refilled.</p> - -<p>In the manufacture of phosphorus there is left after -every distillation a residue of basic calcium phosphate, and -it is advisable to decompose it with hydrochloric acid, this -being effected in a vat lined with lead or coated with paraffine. -The mass is completely dissolved, and the black -sludge remaining on the bottom of the vat consists of charcoal, -which had been added to the distilling mass.</p> - -<p><i>Distillation of the Phosphorus.</i>—The distilling mass consists -of acid calcium phosphate, charcoal and about 4 to 6 -per cent. water. By heating in the retorts, the acid calcium -phosphate is first converted into calcium metaphosphate, -water being eliminated, according to the following equation:</p> - -<p class="center">CaH<sub>4</sub>(PO<sub>4</sub>)<sub>2</sub> = Ca(PO<sub>3</sub>)<sub>2</sub> + 2H<sub>2</sub>O.</p> - -<p>By further heating to a white heat the calcium metaphosphate -is so far reduced as to yield two-thirds of its content -of phosphorus, while one-third remains behind as calcium -phosphate, corresponding to the following equation:</p> - -<p class="center"><a id="Ca"></a>3Ca(PO<sub>3</sub>)<sub>2</sub> + 10C = Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> + 10CO + 4P.</p> - -<p>The mixture of acid calcium phosphate and charcoal is -distilled in glazed fire-clay retorts, 12 to 18 of them being -placed on each side of a so-called galley-furnace. The -bodies of the retorts are placed on the side of the fire, while<span class="pagenum" id="Page_128">128</span> -the necks pass through openings in the walls of the furnace, -those portions of the wall being only lightly bricked up, as -the retorts, after distillation is finished and the furnace -cooled, have to be removed in order to clear out the residue -and introduce fresh mixture. Between each pair of retorts -is left a space of 5 to 6 inches for the passage of the flames.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 53.</span></div> -<img src="images/i_p128.jpg" alt="" /> -</div> - -<p>Experience, however, has proved the advisability of modifying -the galley-furnace by reducing its length and increasing -its height, and placing the retorts in two or three rows, -one above the other. Two such furnaces are placed together -with their narrow sides, so that the fire-gases of both meet -in a common chamber, and are conducted from the latter -under the evaporating pans. Four such furnaces may also -be arranged in the form of a cross, and their fire-gases conducted -into a common chamber. By arranging the furnace, -as is most frequently done, for three double rows of seven -retorts each, it will hold 42 retorts, a double furnace 84,<span class="pagenum" id="Page_129">129</span> -and one in the form of a cross 168. The arrangement of a -double furnace is shown in Fig. 53.</p> - -<p>The wall <i>C</i>, which separates the two fire-places, serves for -supporting the lowest row of retorts, while the second and -third rows rest upon intermediate pieces. The fire gases -pass through flues into the space over the furnace, the top -of which may be directly formed by the evaporating pans. -It is, however, more suitable to place the evaporating pans -on one side and not run the collecting chamber for the fire -gases directly into the chimney. For the introduction of -the retorts into, and their removal from, the furnace, a -narrow door is provided between each two vertical rows of -retorts. After placing the retorts in the furnace, this door -is closed with stones and the joints luted with clay.</p> - -<p>Every three retorts lying one above the other have a -common receiver, <i>p</i>, for the collection of the phosphorus -distilled off. The necks, <i>r</i>, of the retorts terminate in the -collecting pipe, <i>o</i>.</p> - -<p>The galley-furnaces, previously described, require the use -of a fuel which yields a very long flame, and can, therefore, -be heated only with wood or very fat coal.</p> - -<p>In order to render possible the use as fuel of coal yielding -a short flame, and especially of coke, furnaces have been -constructed which hold only a small number of retorts, generally -five, placed in two rows, by twos and threes, one above -the other. The retorts are cylindrical in form, and have a -capacity equal to that of several smaller retorts.</p> - -<p>The <i>receivers</i> for collecting the phosphorus distilling over -from the retorts are made of clay, and should be well glazed -and smooth inside. Each receiver consists of two parts, one -of which is a cylindrical vessel open at the top, into which -the other part fits, and is fixed by means of a rim, which is -prolonged so as to form a neck, between which and the first -part is inserted a tube fitted on the neck of the retort, while -the other end of this tube dips for about 4 inches into the -receiver, the latter being filled with water.</p> - -<p><span class="pagenum" id="Page_130">130</span></p> - -<p>Under certain conditions enameled cast-iron may be used -as a material for receivers, but the enamel must be of such -a nature as not to be attacked by the phosphorus vapors, -otherwise the receivers would in a short time be destroyed.</p> - -<p>The retorts having been filled with the required quantity -of mixture are placed in the furnace and the brickwork is -restored. The fire is then kindled and kept up very gently -for some time in order to dry the fire clay used in joining -the bricks. The receivers are filled with water and fitted -to the retorts. In each receiver a small iron spoon is placed -fastened to iron wire which serves as a stem. After six to -eight hours of firing the heat has been so much increased -as to cause the expulsion of any moisture left in the material -placed in the retorts, while quantities of hydrocarbon -gases and oxide of carbon are formed and expelled with the -sulphurous acid. Subsequently other gases are given off, -and because they contain some hydrogen phosphide are -spontaneously inflammable. As soon as this phenomenon -is observed the joints of the receivers and apparatus connecting -it with the retorts are luted with clay, care being -taken to leave, by the insertion of an iron wire, a small -opening for the escape of the gases, which are as speedily -as possible removed by well arranged ventilators from the -building in which the furnace is placed. The appearance -of amorphous phosphorus at the small opening indicates -the commencement of the distillation.</p> - -<p>The spoon is then placed in the receiver in such a direction -that any phosphorus coming over may collect in it. -During the progress of the operation, and as long as any -phosphorus distils over, the evolution of combustible gases -continues, and consequently a small blue-colored flame is -observed at the opening in the lute. The water in the -receiver is kept cool during the operation. After forty-six -hours, with greatly-increased firing, a full white heat is -reached, and the quantity of phosphorus coming over has -decreased so much as to make a continuation of the ignition<span class="pagenum" id="Page_131">131</span> -process wasteful. The receivers are therefore disconnected -from the retorts.</p> - -<p>The receivers are taken to a special room and entirely -submerged in large wooden troughs filled with water in -order to drive off inflammable gases still contained in them -and to cover the phosphorus with water. They should be -opened only after this has been done, and every manufacturer -should rigidly enforce the rule of carrying on the -operation in the above-described manner. Crude phosphorus -is very inflammable, and when carelessly handled -by the workmen may inflict horrible burns and, as the -phosphorus as a rule causes blood-poisoning, such injuries -generally cause death.</p> - -<p>The phosphorus is then removed from the receivers -(always under water). The trough in which this operation -is effected should be provided, a few inches above the actual -bottom, with a perforated false bottom upon which the -receivers are placed. The larger pieces of phosphorus -taken from the receivers are collected, under water, in -special vessels, while the smaller pieces fall through the -perforations of the false bottom to the actual bottom. -When all the receivers have been emptied, the water in the -trough is discharged into a large barrel in which it remains -until the particles of phosphorus have subsided. The -water is then drawn off, with the exception of a sufficient -quantity to cover the phosphorus in the barrel.</p> - -<p>The water from the receivers as well as from the troughs -shows a quite strong acid reaction due to phosphoric acid, -which has been formed by the combustion of phosphorus -and passed into solution. In order not to lose this phosphoric -acid, the water is partly used for filling the receivers -and partly for mixing the bone-ash before adding the sulphuric -acid.</p> - -<p>Crude phosphorus is a mixture of crystalline (ordinary) -phosphorus with amorphous phosphorus, the reddish color -of the mass being due to the latter. It further contains<span class="pagenum" id="Page_132">132</span> -phosphorus in various stages of oxidation, free carbon, and -if impure sulphuric acid has been used, arsenic in combination -with phosphorus.</p> - -<p><i>Refining and purifying the phosphorus.</i> The crude phosphorus -was formerly purified by forcing it through the -pores of stout wash leather by means of a machine. The -crude phosphorus contained in a tightly tied piece of wash -leather is placed on a perforated copper support situated in -a vessel filled with water at 122° to 140° F. As soon as -the phosphorus is molten, there is placed on the wash -leather a wooden plate which by the aid of a mechanical -arrangement and a lever can be forced downwards so as to -cause the fluid phosphorus to pass through the pores of the -leather, the impurities being retained. The phosphorus in -the form of a slightly yellowish fluid collects on the bottom -of the vessel and is immediately moulded into the shape in -which it is brought into commerce. The residue in the -wash leather consists chiefly of charcoal dust and amorphous -phosphorus. The wash leather can, as a rule, be -only used once, and only small quantities of phosphorus -can be worked at one time.</p> - -<p>A more suitable process of purification is as follows: -Porous, unglazed porcelain or earthenware plates are fixed -in an iron cylinder connected with a steam boiler. The -cylinder having been hermetically closed is placed in a -vessel containing water at 140° F. When the phosphorus -is molten, steam of a few atmospheres’ pressure is admitted -into the cylinder, the phosphorus being thus forced through -the earthenware plates.</p> - -<p>The phosphorus obtained by either of these methods is -free from mechanically admixed particles of charcoal and -amorphous phosphorus, but it is by no means pure, as all -the substances dissolved in it (oxides of phosphorus) pass -through the filter. The loss of phosphorus amounts to -from 5 to 6 per cent. of the weight of the crude product. -The masses taken from the filter plates are therefore col<span class="pagenum" id="Page_133">133</span>lected -and subjected by themselves to distillation in order -to obtain the phosphorus contained in them.</p> - -<p>To obtain pure phosphorus, the crude product has to be -subjected to distillation, this operation being carried on in -iron retorts of a peculiar make, and shaped like the glass -retorts used in chemical laboratories. The necks of these -retorts dip to a depth of ½ to ¾ inch in water contained in a -basin filled to the rim so that any phosphorus which is discharged -into this water causes it to overflow. The crude -phosphorus having been fused under water is next mixed -with 12 to 15 per cent. of its weight of moist sand, and this -mixture placed in the retorts, the object of the mixing with -sand being to prevent the phosphorus becoming ignited -during the filling of the retorts.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 54.</span></div> -<img src="images/i_p133.jpg" alt="" /> -</div> - -<p>Fig. 54 shows a distilling apparatus. In consists of a -cast-iron retort, <i>K</i>, fitted with a cast-iron dome, <i>H</i>, the joint -being made tight by means of clay and screws. The dome, -<i>A</i>, tapers to a cone and terminates in a wide glass tube, <i>R</i>, -bent at a right angle, and having at the mouth a diameter -of about 2⅓ inches.</p> - -<p>This dome, <i>A</i>, dips ¾ inch deep in water contained in the -copper gutter of the receiver filled to the brim. The copper<span class="pagenum" id="Page_134">134</span> -receiver, <i>P</i>, stands in water. It contracts below in the -form of a funnel, and terminates in a pipe closed by a cock, -<i>G</i>, to which is fitted a glass tube bent at a right angle.</p> - -<p>The retort having been filled with the mixture of crude -phosphorus and sand, the dome, <i>H</i>, is placed in position and -the apparatus brought into the furnace. The dome is then -connected with the condensing apparatus.</p> - -<p>The fire is so regulated that the retort is uniformly heated -from all sides in order to evaporate as quickly as possible -the water still adhering to the phosphorus mixture, since at -a higher temperature the water acts upon the phosphorus, -and phosphoretted hydrogen is formed. It being scarcely -possible to entirely avoid the formation of the latter, the -receiver has been given the above-described form, so that -the disagreeable vapors formed by the ignition of the phosphoretted -hydrogen cannot escape into the workroom. The -gas escapes through the conical dome. <i>A</i>, and the glass pipe, -<i>R</i>, into the open air, where it burns without molesting the -workmen.</p> - -<p>At first steam only escapes from the retort, while later -on phosphoretted hydrogen passes off. The evolution of -the latter, however, soon ceases almost entirely, and the -phosphorus distils uniformly over. Heating is continued -until the retort shows a slight red heat, all the phosphorus -having by that time passed over. The residue in the -retort consists only of sand and charcoal.</p> - -<p>The phosphorus passing over in the various stages of distillation -shows different qualities. The portion which -passes over first is perfectly pure, and when cold presents -the appearance of bleached wax; the portions passing over -later on are of a yellowish-red color, while the last portions -are colored brick-red by amorphous phosphorus, and have -to be collected by themselves. They are again brought -into the retort in the subsequent operation.</p> - -<p>In order to be able to separate the phosphorus passing -over according to quality, the receiver for the melted mass<span class="pagenum" id="Page_135">135</span> -is fitted with a conical bottom furnished with a glass tube -which can be closed by the cock <i>G</i>. This glass pipe leads -to a tank filled with warm water, in which the collecting -vessel is immersed. The phosphorus collecting in this -vessel is from time to time allowed to run into a vessel -filled with water, another vessel being substituted when the -phosphorus commences to show a yellowish color.</p> - -<p><i>Moulding the refined phosphorus.</i> It has long been the -custom to mould phosphorus into the shape of sticks formed -by the aid of a glass tube open at both ends, one of these -being placed in molten phosphorus covered by a stratum of -warm water. The liquid phosphorus is sucked by the -operator into the tube until it is quite filled. The lower -opening of the tube being kept under water is closed by the -finger of the operator; the tube is instantly transferred to a -vessel filled with very cold water by which the phosphorus -is solidified. It is removed from the glass tube by pushing -it out with a glass rod or iron wire while being held under -water.</p> - -<p>Independent of its danger, the method of moulding above -described is not suitable for the manufacture on a large scale, -and various contrivances have been introduced for this purpose; -the apparatus constructed by Seubert being much used. -It consists of a copper boiler fitted on a furnace. To the flat -bottom of this boiler is fitted by hard solder an open copper -trough communicating with a water-tank. In the boiler is -fitted a copper funnel provided with a horizontal tube. -This portion of the apparatus is intended for the reception -of the phosphorus. At the end of the horizontal tube is -placed a stopcock, while the portion of the projecting -mouth of the tube beyond the cock is widened out and fitted -by means of bolts and nuts, with a flange-like copper plate, -into which are inserted two glass tubes. Into the copper -trough is let a wooden partition, which serves the purpose -of supporting the glass tubes as well as of preventing the -communication of the hot water in the boiler and a portion<span class="pagenum" id="Page_136">136</span> -of the trough with the cold water of the tank and the portion -of the trough nearest to it. The phosphorus having -been introduced in the boiler, the water is gently warmed -so as to cause the fusion of the phosphorus. As the warm -water reaches to the wooden partition, it is evident that on -opening and closing the cock at the end of the horizontal -tube, some phosphorus will pass through and flow out of the -glass tubes, but that remaining in these tubes will solidify, -and on opening again the cock at the end of the horizontal -tube, the solid sticks of phosphorus may be removed from -the glass tubes by taking hold of the piece of projecting -phosphorus, the phosphorus being immediately immersed -under water in the tank, and kept there protected from the -action of the light.</p> - -<p>Notwithstanding its apparently very practical arrangement, -Seubert’s apparatus possesses many disadvantages, -the principal drawback to its use being that the phosphorus-sticks -frequently stick so firmly in the glass tubes that the -operation of moulding has to be interrupted, the tubes -removed, and the phosphorus stick pushed out with a stout -wire. Furthermore, the melted phosphorus in flowing in -frequently causes the glass tubes to crack.</p> - -<p>Hence many factories have returned to the old method -of moulding by sucking the fused phosphorus into glass -tubes. To render this operation perfectly free from danger, -the apparatus shown in Fig. 55 has been devised, by means -of which a larger quantity of phosphorus can in a short -time be moulded into sticks.</p> - -<p>A hollow prism, <i>P</i>, of stout sheet-iron is fitted at its lower -end with 8 to 12 short tubes. In the latter are inserted -air-tight, by means of rubber, 12 glass tubes, <i>G</i>, each about -3¼ feet long and somewhat contracted at the lower end. -Two iron rods, <i>E</i>, are fitted to the prism and, by means of -suitably-shaped pieces of cork, serve to hold the glass tubes -in their proper position. To the back of the prism is -secured a rubber tube, <i>L</i>, which communicates with a small<span class="pagenum" id="Page_137">137</span> -air-pump, and to the upper surface of the prism is fixed a -handle.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 55.</span></div> -<img src="images/i_p137.jpg" alt="" /> -</div> - -<p>The phosphorus to be moulded is fused in a shallow vessel -of such a shape that a portion of it is covered only about -2 inches deep with water. The glass tubes are placed in -the fused phosphorus and the air is sucked from them by -means of the air-pump; the external air-pressure forcing the -fused phosphorus into the glass tube.</p> - -<p>The tubes are now sufficiently raised to allow of a rubber -plate being pushed under their mouths in the shallower -portion of the vessel. The rubber plate is pressed against -the tubes and the entire apparatus placed in a vessel filled -with cold water. The phosphorus solidifies very rapidly in -the lower narrower portions of the tubes, and the latter are -immediately detached from the prism and replaced by -others. The phosphorus when entirely cold is pushed from -the glass tubes by means of a wire or wooden stick.</p> - -<p>In some factories the phosphorus is moulded in wedge-shaped -sheet-metal boxes. In packing two such wedges -are laid together with their longitudinal sides so as to form -a prism.</p> - -<p><span class="pagenum" id="Page_138">138</span></p> - -<p>Phosphorus is stored either in strong sheet-iron tanks or -in wooden boxes lined with tinned sheet-iron and covered -with a stratum of water fully 1¼ inches deep. For shipping -smaller quantities of phosphorus, the sticks are packed in -tinned sheet-iron boxes and the latter having been filled up -with water, the lid is soldered on. To prevent the water -from freezing in winter, it is advisable to mix it with spirits -of wine.</p> - -<p><i>Manufacture of phosphorus with the assistance of electricity.</i> -Readman and Parker have recently devised a process for -the manufacture of phosphorus on a large scale in a continuously -working apparatus by means of a powerful electric -current, such as is yielded by a larger dynamo. The mixture -used for the operation differs from the ordinary one of -calcium phosphate and charcoal, in that it contains in addition -a slag-forming body—a flux—silicic acid (quartz -sand) being at first used for the purpose. Numerous experiments, -however, have shown kaolin or pipe clay, <i>i. e.</i>, -aluminium silicate, to be more suitable.</p> - -<p>When a mixture of calcium phosphate, charcoal and -aluminium silicate is exposed to the action of the voltaic -arc the following process takes place: By the extraordinarily -high temperature prevailing in the proximity of -the arc, the reduction to phosphorus of the phosphoric acid -contained in the calcium phosphate is very rapidly effected. -The liberated calcium combines immediately with the aluminium -silicate to a calcium-aluminium-silicate, <i>i. e.</i>, to a -glass fusible with the greatest difficulty which, however, at -the high temperature possessed by the voltaic arc becomes -fluid like water.</p> - -<p>The apparatus employed is, generally speaking, similar to -the electric furnaces now in use. The mass to be treated is -contained in a carbon crucible in which the two electrodes -are placed opposite to one another, so that the electric current -must pass through the mass. However, since the -phosphorus at the moment of liberation would, on coming<span class="pagenum" id="Page_139">139</span> -in contact with oxygen, immediately burn again to phosphorus -pentoxide, the apparatus has to be so arranged that -the entire process passes off in an entirely indifferent gas, -and the condensation of the phosphorus vapors takes place -under the same conditions.</p> - -<p>Fig. 56 shows the apparatus employed for the electrolytic -manufacture of phosphorus.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 56.</span></div> -<img src="images/i_p139.jpg" alt="" /> -</div> - -<p>The carbon crucible, <i>a</i>, is enclosed by a clay jacket, -which serves as an insulator of heat, and is closed by a -graphite cover, <i>c</i>. Through the bottom and the cover of -the crucible pass the two electrodes, <i>k k</i>, which conduct the -current, and between which the voltaic arc is formed. To -prevent the upper electrode from becoming too highly -heated during the operation, it is constantly cooled by -water admitted at <i>g</i>, and running off at <i>f</i>. Through the -pipes <i>h</i> and <i>l</i> an indifferent gas—as a rule, illuminating<span class="pagenum" id="Page_140">140</span> -gas—is conducted into the apparatus and escapes together -with the phosphorus vapors through the pipe <i>d</i>.</p> - -<p>In operating with the apparatus, the reduction soon takes -place, and the phosphorus vapors escape through <i>d</i>, while -a thinly-fluid slag remains behind in the crucible. The -slag is discharged through a pipe not shown in the illustration, -and a fresh charge of the mixture brought into the -crucible <i>a</i>, the process of reduction being thus carried on -without interruption. The phosphorus vapors escaping -from <i>d</i> are conducted through a cooled pipe and condense -to a liquid in water heated to between 122° and 140° F. -contained in a receiver.</p> - -<p>Although the electrolytic method of manufacturing phosphorus -is of quite recent origin, a considerable portion of -the phosphorus brought into commerce is now prepared in -that manner, it being cheaper than the older processes -which involve a very large consumption of fuel.</p> - -<hr class="chap" /> - -<p><span class="pagenum" id="Page_141">141</span></p> - - - - -<div class="chapter"></div> -<h3><a name="CHAPTER_VII" id="CHAPTER_VII">CHAPTER VII.</a><br /> - -<small>METHODS OF BLEACHING GLUE.</small></h3> - - -<p>Many experiments have been made to bleach glue, <i>i. e.</i>, -to obtain masses as colorless as possible, or at least slightly -colored, the resulting product being more valuable than the -dark-colored one.</p> - - -<p class="center">a. <i>Bleaching in the Air.</i></p> - -<p>The principal requisite for obtaining a beautiful bleached -glue is that the unbleached product is clear, <i>i. e.</i>, transparent, -even if of a dark color, this being the best criterion -of well-made glue.</p> - -<p>Glue may be bleached whilst being prepared, or the -finished cakes may be subjected to the bleaching process.</p> - -<p>For the purpose of obtaining pale-colored glue from skin -or cartilage it is advisable to expose the materials in thin -layers to the direct action of the sun. Moist oxygen when -acted upon by the sun is converted into ozone, which exerts -an extraordinary bleaching effect upon organic substances.</p> - - -<p class="center">b. <i>Bleaching with Chlorine.</i></p> - -<p>The powerful bleaching effect of a solution of chlorine in -water upon organic matter is well known; the water is -decomposed, and bleaching is effected by the oxygen which -is liberated. Hence skin and cartilage may also be bleached -by placing them in a vessel filled with weak solution of -chlorine in water and leaving them in contact with it until -the fluid shows no longer an odor of chlorine. When -bleaching is finished the materials are suspended in a certain -quantity of hydrochloric acid, which has finally to be -removed by repeated treatment with water.</p> - -<p><span class="pagenum" id="Page_142">142</span></p> - - -<p class="center">c. <i>Bleaching with Animal Charcoal.</i></p> - -<p>Animal charcoal is distinguished by its great power of -absorbing coloring as well as odoriferous matter, and may -also be used for discoloring glue-liquors. This may be -done by allowing the thin liquor, as it comes from the -glue-boiler, to run through a filter filled with animal charcoal, -or with the use of charcoal dust.</p> - -<p>In the latter case the glue-liquor is collected in a clarifying -vessel and a quantity of charcoal dust amounting to -about 3 to 4 per cent. of the weight of the glue in the -liquor stirred in. The finely divided charcoal sinks slowly -down, carrying with it the solid particles suspended in the -liquor, and collects on the bottom of the clarifying vessel -in the form of a black slime.</p> - -<p>In order to discolor the glue-liquor as much as possible, -when working on a large scale, it is recommended to use a -number of cylinders filled with animal charcoal. These -cylinders are connected one with the other in such a manner -that the glue-liquor runs into the first cylinder from -the top, passes out from the lower end of this cylinder -through a pipe into the second cylinder, traverses this from -bottom to top, passes into the third cylinder from the top, -and so on. The animal charcoal in the first cylinder loses -its discoloring power first. The cylinder is then disengaged, -freshly charged and placed last in the series of -filters, the process being the same with the second cylinder, -and so on, so that after a certain time all the cylinders -have alternately occupied the first and last places in the -series of filters.</p> - -<p>By the use of animal charcoal it is even possible to -render very dark and badly-smelling glue, entirely colorless -and free from odor. The darker the glue is, the longer it -must, of course, be subjected to the action of the animal -charcoal.</p> - -<p><span class="pagenum" id="Page_143">143</span></p> - - -<p class="center">d. <i>Bleaching with Sulphurous Acid.</i></p> - -<p>Bleaching of the glue-liquor itself by means of sulphurous -acid is best effected in the clarifying vat. For this -purpose, the latter is fitted with a lead pipe reaching to the -bottom and terminating in a perforated coil. Through -this pipe gaseous sulphurous acid, generated in a suitable -sulphur-burner is forced through the liquor by means of a -force-pump.</p> - -<p>The sulphurous acid is dissolved in the glue-liquor, the latter -being thereby bleached. When the liquor has acquired -a much paler color and a strong odor of sulphurous acid is -perceptible in the air over the vat, the introduction of -gaseous sulphurous acid is interrupted and the liquor allowed -quietly to clarify, the acid dissolved in it exerting -during this time a further bleaching effect. By this means -ordinary brown joiners’ glue of good quality may be converted -into a pale-yellow product similar to the variety -known as gilder’s glue.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 57.</span></div> -<img src="images/i_p143.jpg" alt="" /> -</div> - -<p>For bleaching finished glue, solution of sulphurous acid -in water may be used, the apparatus shown in Figs. 57 and -58 being suitable for the purpose.</p> - -<p>The apparatus for the production of the acid solution -consists of the sulphur-burner <i>O</i>, the wash-vessel for the -gas <i>W</i>, and the vessel <i>T</i> for dissolving the gas in water.</p> - -<p>The sulphur-burner <i>O</i> is a small brick vault of sufficient -size to hold a vessel <i>S</i> having a capacity of a few quarts.<span class="pagenum" id="Page_144">144</span> -In front the sulphur-burner is provided with a well-fitting -door <i>J</i>, which is furnished with a small aperture for the -introduction of an iron pipe into the burner. The lead-pipe -<i>R</i> leads from <i>O</i> to the bottom of the wash-vessel <i>W</i>, -and from the lid of the latter rises a pipe <i>R<sub>1</sub></i>, and runs -along the bottom of the trough filled with water. This -trough is provided with a wooden lid and the cock <i>H</i>, and -by means of the latter the fluid can be discharged into the -vessel <i>G</i>.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 58.</span></div> -<img src="images/i_p144.jpg" alt="" /> -</div> - -<p>The trough <i>T</i> is filled with water and <i>W</i> is also filled -three-quarters full. In the burner <i>O</i> is placed a dish <i>S</i> -filled with sulphur, and the latter ignited. The door is -then closed and air blown in through <i>A</i> by means of a -bellows, the joints of the door <i>J</i> being at the same time -luted with clay.</p> - -<p>In contact with air, the sulphur burns to sulphur dioxide. -The latter is freed in the wash-vessel from sulphur vapor -which has been carried along, and passes from <i>R<sub>1</sub></i> through -the numerous perforations into the water in <i>T</i> where it is -dissolved to sulphurous acid.</p> - -<p>Saturation with sulphurous acid of the fluid in the trough -is complete when the suffocating odor of the acid is perceptible -in the proximity of <i>T</i>. The fluid is then discharged, -replaced by water, which is again saturated with -sulphuric acid, and so on.</p> - -<p>The cakes of glue to be bleached are placed in a trough -(Fig. 58), in which are arranged several frames, <i>B</i>, covered -with linen. The cakes of glue are placed upon these frames -and the trough is filled with sulphurous acid so that it<span class="pagenum" id="Page_145">145</span> -stands a few inches deep over the uppermost frame. The -cakes of glue swell up rapidly in the solution of sulphurous -acid, and yielding up their salts become bleached. After -twelve hours the fluid is discharged through the cock, <i>H</i>, -and if glue of a particularly fine appearance is to be produced -the cakes are treated twice more with solution of -sulphurous acid.</p> - -<p>When bleaching is finished the trough is filled with -clean water, in which the glue is allowed to remain for a -few hours, when the frames are lifted out and the cakes -dried.</p> - -<p>By this method glue may be bleached to such an extent -as to render it fit as a substitute for gelatine for many purposes, -for instance, for the imitation of thin plates of ivory.</p> - -<p>Dr. Bruno Terne’s apparatus (Fig. 40), previously described, -may also be used for the generation of sulphurous -acid for bleaching purposes.</p> - -<hr class="chap" /> - -<p><span class="pagenum" id="Page_146">146</span></p> - - - - -<div class="chapter"></div> -<h3><a name="CHAPTER_VIII" id="CHAPTER_VIII">CHAPTER VIII.</a><br /> - -<small>DIFFERENT VARIETIES OF GLUE AND THEIR PREPARATION.</small></h3> - - -<p>Besides the broadly-distinguished forms of skin-and -bone-glue, the trade recognizes a large number of varieties, -distinguished either by their value or their fitness for special -purposes.</p> - -<p><i>Joiner’s Glue.</i>—This variety is without doubt the oldest -in use and most in demand, and its principal requisite is -its great adhesive power. It is used for joining wood, -leather, paper, etc., and varies very much in quality and -price.</p> - -<p>The best variety is prepared from scraps of hide and -skin. A light color not being especially demanded, there -existing rather a prejudice in favor of a dark-colored article, -waste of cattle and horse skins and tendons can be used for -its manufacture.</p> - -<p>Joiner’s glue, which is generally preferred in thin cakes, -is chiefly manufactured in regular glue factories, though to -be able to compete with the bone-glue turned out by the -large establishments, the glue-boiler generally mixes skin -and bone-glue, and is thus enabled to turn out a tolerably -good quality. The price paid for the different varieties of -joiner’s glue varies very much, being generally higher in -winter than in summer, and is frequently more regulated -by the external appearance of the article than by its actual -value. Glue without gloss, very much warped and of a -very dark color, may, notwithstanding its faulty appearance, -possess excellent qualities.</p> - -<p>Nothing need be said about the manufacture of joiner’s -glue, since what has been said about the manufacture of -glue in general suffices for the purpose.</p> - -<p><span class="pagenum" id="Page_147">147</span></p> - -<p><i>How to make and use glue.</i> Break the glue into small -pieces, put it into an iron kettle, cover it with water, and -allow it to soak twelve hours; after soaking boil until done. -Then pour into a box which can be covered air-tight; leave -the cover off until cold, then cover up tight. As glue is -required, cut out a portion and melt in the usual way. -Expose no more of the made glue to the atmosphere for any -length of time than is necessary, as the atmosphere is very -destructive to made glue.</p> - -<p>All glue, as received from the factory, requires the addition -of water before it will melt properly, and every addition -of water (while the glue is fresh made) will, up to a certain -point, increase its adhesiveness and elasticity. Some glues -will bear more water than others, but all will bear more -water than usually falls to their share, and that, too, with a -greater improvement in the quality of the work. For glue -to be properly effective, it requires to penetrate the pores of -the wood, and the more a body of glue penetrates the wood -the more substantial the joint will remain. Glues that take -the longest to dry are to be preferred to those that dry -quickly, the slow-drying glues being always the strongest, -other things being equal. Never heat made glue -in a pot that is subjected to the direct heat of the fire -or a lamp. All such methods of heating glue cannot -be condemned in terms too strong. Do not use thick glue -for joints or veneering. In all cases work it well into the -wood in a manner similar to what painters do with paint. -Glue both surfaces of your work excepting in the case of -veneering. Never glue upon hot wood, as it will absorb all -the water in the glue too suddenly, and leave only a very -little residue, with no adhesiveness in it whatever.</p> - -<p><i>Holding power of glue.</i> 1. Glue exerts a far greater hold -on surfaces of wood cut across the grain than on those that -have been split, or cut with the grain.</p> - -<p>2. When two surfaces of split wood are laid together, the -hold of the glue is the same whether the fibres are laid parallel -or crosswise to each other.</p> - -<p><span class="pagenum" id="Page_148">148</span></p> - -<p>3. The holding power of glue on different woods estimated -in kilogrammes per square centimeter (0.155 square -inch) is as follows:</p> - -<div class="center"> -<table border="0" cellpadding="4" cellspacing="0" summary=""> -<tr><td align="left"></td><td align="center">Cut across the grain.</td><td align="center">Split.</td></tr> -<tr><td align="left">Beech,</td><td align="right">155.55 (342.21 lbs.)</td><td align="right">78.83 (173.42 lbs.)</td></tr> -<tr><td align="left">Hornbeam,</td><td align="right">126.50 (278.30 lbs.)</td><td align="right">79.16 (174.15 lbs.)</td></tr> -<tr><td align="left">Maple,</td><td align="right">87.66 (192.85 lbs.)</td><td align="right">63.00 (138.6 lbs.)</td></tr> -<tr><td align="left">Oak,</td><td align="right">128.34 (282.34 lbs.)</td><td align="right">55.16 (121.35 lbs.)</td></tr> -<tr><td align="left">Fir,</td><td align="right">110.50 (243.10 lbs.)</td><td align="right">24.16 ( 53.15 lbs.)</td></tr> -</table></div> - -<p><i>Cologne glue.</i> The variety of glue known under this -name is prepared from selected scraps of hide and skin, and -is consequently very pure, and possesses great adhesive -power. It is of a light-brown color, and comes into commerce -in short thick cakes of great hardness. It is an -excellent quality of glue, and is preferred to all others by -bookbinders, workers in leather, etc. There are many -imitations of this variety, bone-glue being frequently sold -as Cologne glue.</p> - -<p>The genuine article is manufactured from refuse of hide, -which, after liming, is carefully bleached in a bath of -chloride of lime, the concentration of which depends on the -darker or lighter color of the glue-stock. For 220 lbs. of -glue-stock, it is generally customary to use 1 lb. of chloride -of lime mixed with sufficient water to cover the stock.</p> - -<p>After thorough impregnation of the glue-stock, which -generally requires about half an hour, add sufficient hydrochloric -acid to impart an acid taste to the bath of chloride -of lime. To be able to mix the mass thoroughly, it is best -to use a vat provided with a stirring apparatus. After -allowing the acid to act for a quarter of an hour, remove -every trace of it by careful washing.</p> - -<p>To obtain a jelly as clear as possible, the gelatinous liquor -is drawn off as soon as the thin portions of the glue-stock -and the outside of the thicker ones are dissolved, they being -more thoroughly bleached than the rest. The residue is -worked into darker glue.</p> - -<p><span class="pagenum" id="Page_149">149</span></p> - -<p><i>Russian glue.</i> This variety is of a dirty white color, and, -like Cologne glue, is brought into commerce in short, thick -cakes. Its color and opaqueness are imparted to it by an -addition of 4 to 8 per cent. of white lead, chalk, zinc white, -or permanent white (sulphate of baryta). It has been -claimed that the superior adhesive power of Russian glue -is due to this addition of mineral substances, but the results -of many experiments fail to substantiate this claim. In -case the glue turns out turbid, it may be of advantage to -make it opaque by an addition of coloring matter, but the -quality of the glue remains unchanged. The best time to -add the coloring matter is shortly before drawing the glue-liquor -from the clarifying vats into the cooling boxes, as -the jelly is then of sufficient consistency to prevent the -substances from settling on the bottom. Skin-glue, as well -as bone-glue, is sold under the name of Russian glue.</p> - -<p>Quite a considerable quantity of Russian glue brought -into commerce in the form of brownish-white sheets is prepared -from bones, the latter being degreased by boiling, -steaming or extraction, and the solution of the mineral constituents -effected by means of hydrochloric acid. The treatment -with acid is, however, continued only till the bones -commence to become soft and flexible. The solution of -phosphates is then drawn off, and the softened bones are -washed and in the usual manner worked to glue.</p> - -<p>By this incomplete treatment with hydrochloric acid, a -certain quantity of the phosphates remains in the cartilage -and is inclosed in the glue prepared from it, the finished -product acquiring thereby a dirty whitish color, which is -by many considered an evidence of its quality. This -mechanical admixture of phosphates, however, does not -affect the adhesive power of the glue, neither increasing or -decreasing it. Such white and opaque glue is manufactured -to answer the demand in certain quarters of the trade, and, -as above mentioned, heavy white substances are often intentionally -incorporated with skin glue, as well as bone<span class="pagenum" id="Page_150">150</span> -glue, to give it the appearance of Russian glue. These -heavy powders add to the weight of the product, though -when incorporated with it in small quantities do not injure -its adhesive power, but large quantities render the product -weaker.</p> - -<p><i>Patent glue.</i> This term is applied to an indefinite number -of preparations, but particularly refers to a very pure -variety of bone glue of a deep dark-brown color not showing -net marks. It is very glossy, and swells up much in water. -To satisfy the demand for thick cakes, they must be cut -from very concentrated jelly to insure their drying.</p> - -<p><i>Gilder’s glue</i> is found in commerce in very thin, pale -yellow cakes tied up in packages weighing about 2 lbs. -each. It is a variety of skin glue bleached with chloride of -lime, and dissolves with difficulty in water. The first runnings -from the boiler are used for its manufacture.</p> - -<p>A very superior article of gilder’s glue is obtained by -cutting rabbit skins into fine shreds and boiling in water, -then turning the mixture into a basket through which the -liquid passes, leaving the refuse behind. About 100 -grammes (3.52 ozs.) of sulphate of zinc and 20 grammes -(0.705 oz.) of alum are then separately dissolved in pure -boiling water and poured into the first-mentioned liquid, -and the whole well stirred together while hot. The mixture -is then passed through a sieve into a rectangular box, -in which the jelly remains twenty-four hours in winter, or -forty-eight in summer. The solid mass is taken from the -box, cut into slices of proper thickness, and dried upon nets.</p> - -<p><i>Size glue and parchment glue</i> are manufactured in the same -manner. Both are skin-glues, and can be readily produced -by following the directions given for the manufacture -of skin-glue.</p> - -<p><i>Paris glue</i> is used for sizing. It is brown, opaque, and -almost always soft. Being very hygroscopic, and imparting -a suitable flexibility to the felt, it is better adapted for -hatter’s use than any other variety. For its manufacture<span class="pagenum" id="Page_151">151</span> -only the generative organs, or the thick tendons of the legs -of cattle and horses, are used, or other waste and fleshy -parts, and substances mixed with small bones, which, if -thoroughly cleansed, might yield a good quality of glue, -but are intentionally transformed by too long-continued -boiling, whereby the gelatinous solution is largely deprived -of its adhesive power, and yields a hygroscopic product.</p> - -<p><i>Liquid Glues.</i> These are chiefly combinations of glue -with some ingredients added to destroy the gelatinizing -property and yet not impair its adhesiveness. They remain -for a long time clear and syrupy, and are used for a variety -of purposes. Below are given a few receipts for such glues.</p> - -<p>1. Dissolve 38 parts of glue in small pieces in 100 parts -of acetic acid. Solution is promoted by exposing the vessel -to the sun or placing it in hot water.</p> - -<p>2. Dissolve 50 parts of light-colored glue in 50 parts by -weight of hot water, in which 14 parts of fused magnesium -chloride have been dissolved. The solution on cooling -does not gelatinize, but remains syrupy, the density varying -according to the quantity of water used. In the preparation -of printing inks it can be used as a substitute for gum.</p> - -<p>3. Dilute 10 parts of strong phosphoric acid with an -equal weight of water, and then gradually add 4 parts of -ammonium carbonate in the dry state. When the effervescence -has subsided, add a further 5 parts of water and warm -on the water-bath or steam-chest to 158° F. Now add 20 -to 40 parts of glue, according to the consistency required, -and stir until all is dissolved. Cool.</p> - -<p>4. Dissolve 20 parts of glue in an equal weight of hot -water, then cautiously pour in, stirring constantly, 4 parts -of strong nitric acid, warm until the nitrous fumes have -been driven off, filter, if necessary, through fine shavings, -and allow to cool.</p> - -<p>5. Dissolve 3 parts of glue in small pieces in 12 to 15 parts -of saccharate of lime. By heating, the glue dissolves rapidly -and remains liquid, when cold, without loss of adhesive<span class="pagenum" id="Page_152">152</span> -power. Any desirable consistency can be secured by varying -the amount of saccharate of lime. Thick glue retains -its muddy color, while a thin solution becomes clear on -standing.</p> - -<p>The saccharate of lime is prepared by dissolving 1 part -of loaf sugar in 3 parts of water, and after adding one-fourth -part of the weight of sugar of slaked lime, heating the whole -to between 149° and 185° F., and allowing it to macerate -for several days, shaking it frequently. The solution, which -has the properties of mucilage, is then decanted from the -sediment.</p> - -<p>The solution of the glue in saccharate of lime is readily -accomplished, even old gelatine, which has become insoluble -in water, dissolving without difficulty. This variety of -liquid glue possesses great adhesive power, and admits of -many uses.</p> - -<p>6. Dissolve 8 parts of glue in 16 parts of hot water, then -add ½ to 1 part of hydrochloric acid, and 1½ parts of sulphate -of zinc. Keep the mixture for 8 hours at 158° F., -then filter through fine shavings, and allow to cool.</p> - -<p><i>Steam glue.</i> Under this name several varieties of liquid -glue are brought into commerce. They are prepared as -follows:—</p> - -<p>1. <i>Russian steam-glue.</i> 100 parts of a good quality of -glue, 100 to 110 parts of warm water, and 5.5 to 6 parts of -commercial nitric acid of 36° B.</p> - -<p>2. <i>Pale steam-glue.</i> 100 parts of glue, 200 of water, and -12 of nitric acid of 36° B.</p> - -<p>3. <i>Dark steam-glue.</i> 100 parts of glue, 140 of water, and -16 of nitric acid of 36° B.</p> - -<p>Soak the glue in cold water, then pour the necessary -quantity of warm water over it, and heat gently on a water-bath -until all the glue is dissolved. Next add gradually -the nitric acid with constant stirring, and to the Russian -steam-glue 6 parts of finely pulverized sulphate of lead, -which will impart to it the white color.</p> - -<p><span class="pagenum" id="Page_153">153</span></p> - -<p><i>Chrome glue.</i> This preparation is very permanent and -durable. To prepare it add to a moderately concentrated -solution of 5 parts of glue 1 of dissolved acid chromate of -lime, this salt being considered better for the purpose than -the bichromate of potash usually used. The glue thus -prepared becomes, after exposure to the light, insoluble in -water in consequence of a partial reduction of the chromic -acid. This preparation can be used for cementing glass -articles, liable to be exposed to boiling water, the treatment -being the ordinary one of applying the glue to both surfaces -of the fractured object, and then binding them together -until dry, and exposing them for a sufficient length -of time to the light, after which boiling water will have no -effect upon them. It is suggested that this preparation is -better adapted to cementing the covers on glass slides than -any now in use. The same preparation can be applied for -making fabrics water-proof, especially sails, awnings, etc., -where no great flexibility is required. Two or three applications -of the glue, either by immersion of the object in it, -or by the use of the brush, will answer the purpose. Roofing -paper is also rendered impervious, even when exposed -to long-continued rains.</p> - -<p><i>Glue for attaching leather to metal.</i> A method of affixing -leather to metal, so that it will split before it can be torn -off, consists in digesting a quantity of nutgalls, reduced to -powder, in eight parts of distilled water for six hours, and -filtering it through a cloth; then dissolving one part by -weight of glue in the same quantity of water, and allowing -it to remain twenty-four hours. The leather is moistened -with the decoction of nutgalls and the solution of glue -applied to the metal, previously roughened and heated. -The leather is then laid upon it, and dried under pressure.</p> - -<p><i>Glue for leather, paper, etc.</i> The following process affords -an unusually adhesive paste, adapted to fastening leather, -paper, etc., without the defects of glue, and if preserved -from evaporation in closed bottles will keep for years.<span class="pagenum" id="Page_154">154</span> -Cover 4 parts, by weight, of glue with 15 parts of cold -water, and allow it to soak for several hours; then warm -moderately till the solution is perfectly clear, and dilute it -with 65 parts of boiling water, intimately stirred in. Next -prepare a solution of 30 parts of starch in 200 of cold water, -so as to form a thin homogeneous liquid free from lumps, -and pour the boiling glue solution into it with thorough -stirring, and at the same time keeping the mass boiling.</p> - -<p><i>Glue for parchment paper in making sausage skins.</i> The -supply of intestines soon being exhausted by the enormous -quantity of pease-sausages manufactured for the German -army during the Franco-German war, the necessity arose -for a substitute. This consisted of a tube of parchment -glued together. Millions of these tubes from Dr. Jacobsen’s -factory were tested by the government, and found to answer -the purpose admirably. They were even boiled for hours -without either the glued seam or the paper itself being injured -by the operation. The secret of the composition of -the glue employed for fastening the parchment paper seems -to be well kept, but the one given in the following is equal -to it in all respects, if not indeed identical: Add to one -quart of a good adhesive solution of glue ¾ to 1 oz. of finely -powdered bichromate of potash. Warm the mixture slightly -on a water-bath when about to use it, and before applying -it moisten the parchment paper. The latter, when glued -with this preparation, as in the formation of the small -cylinders for sausages, must be rapidly dried on a hurdle, -and then exposed to the light until the yellow glue becomes -brownish. The cylinders are then slowly boiled in -a sufficient quantity of water to which two or three per -cent. of alum has been added, until all the chromate is dissolved -out, and they are then washed in cold water and -dried, and will look very inviting, especially if white glue -has been used. A similar result may be reached by using -a concentrated solution of cellulose in ammoniacal oxide of -copper. Thus if cylinders of unsized paper are formed with<span class="pagenum" id="Page_155">155</span> -this paste, and when thoroughly dry drawn through a -parchmentizing solution (a cooled mixture of 2 volumes of -fuming sulphuric acid and 1 volume of water), they will be -beautifully parchmentized, and after the neutralization of -the acid, washing, etc., it will present a striking resemblance -to natural intestines.</p> - -<p><i>Tungstic glue.</i> This preparation offers an acceptable substitute -for hard India rubber. It is made by mixing a -thick solution of glue with tungstate of soda and hydrochloric -acid, by means of which a compound of tungstic -acid and glue is precipitated, which, at a temperature of -86° to 104° F., is sufficiently elastic to admit of being -drawn out into very thin sheets. On cooling, this mass -becomes solid and brittle, and on being heated is again soft -and plastic. It can be used for all purposes to which hard -rubber is adapted.</p> - -<p><i>Indestructible mass for the manufacture of ornaments, toys, -etc.</i> A mass, which is to have the hardness of horn, consists -of 50 parts of glue, 35 of wax or rosin, 15 of glycerine -and the required quantity of a metallic oxide, or mineral -color. A soft mass consists of about 50 parts of glue, 25 of -wax or rosin, and 25 of glycerine. The glue is melted in -the glycerine with the assistance of steam, and the wax or -rosin added. The latter in melting mixes with the glue -and glycerine, and finally the mineral color is added. The -mass is poured in a liquid state into moulds of plaster of -Paris, wood, or metal. The degree of hardness of the mass -is increased by an addition of 30 to 35 per cent. of zinc -white, or other mineral color, according to the color the -article is to have.</p> - -<p><i>Compound for billiard balls.</i> Allow 80 parts of Russian -glue and 10 parts of Cologne glue to swell up in 10 parts -of water; then heat over a water-bath, and when dissolved, -add 5 parts of heavy spar, 4 parts of chalk and 1 part of -boiled linseed oil. Of a portion of the mass form small -sticks, dip them in the remainder, and allow the adherent<span class="pagenum" id="Page_156">156</span> -portion to dry, and repeat this process until a crude ball -has been formed. This is placed in a dry room for three -or four months, and when thoroughly dry, it is turned. -The finished ball is placed in a bath of sulphate of alumina -for one hour, dried, and polished like an ivory ball.</p> - -<p><i>Coloring glue.</i> Common black or dark glue, while -possessing all the adhesive and other essential qualities of -fine colored glue, has heretofore, owing to its color, been -confined in its use to such purposes in the arts where color -was not essential.</p> - -<p>The object of the following process, which is the invention -of G. J. Lesser, of Frankfort, Germany, is to color such -glue so that it is both refined and tinted, and may be used -for various purposes in the arts. It is especially applicable -in the manufacture of sizing and finishing compounds for -paper hangings, compounds for the manufacture of elastic -rolls, for glue and size compounds for finishing yarns, -textile fabrics of silk, cotton, etc., for the manufacture of -calcimines and wall-coverings, for glue to be used with -colored woods, and for all other purposes where a fine, -strong-colored glue is required.</p> - -<p>For coloring common black or dark glue take a pound -and a half of liquid extract of lead and mix it into the -water in which the glue has been soaked, as follows: Thirteen -pounds of glue, sixty-three and a quarter pounds of -water. Allow the glue to soak for about twenty-four hours, -then dilute it by a slow fire, and when heated gradually -pour in one and a half pounds of the extract of lead and -mix it well together.</p> - -<p>The extract of lead is a well-known commercial article, -and it is well suited for this purpose; but the inventor does -not limit himself to this particular preparation, as there are -a larger number of neutral and basic compounds of lead -that may be so modified as to produce results similar, if not -identical, with the results obtained by the formula above -given. Gelatine may be treated instead of glue.</p> - -<p><span class="pagenum" id="Page_157">157</span></p> - -<p><i>Compositions for printing rollers.</i> All such compositions -contain gelatine or glue. The following receipts are used:</p> - - -<div class="center"> -<table border="1" cellpadding="4" cellspacing="0" summary=""> -<tr> - <td align="left"></td> - <td align="center">I.</td> - <td align="center">II.</td> - <td align="center">III.</td> - <td align="center">IV.</td> - <td align="center">V.</td> - <td align="center">VI.</td> - <td align="center">VII.</td> - <td align="center">VIII.</td></tr> -<tr> - <td align="left">Glue</td> - <td align="center">8</td> - <td align="center">10</td> - <td align="center">4</td> - <td align="center">2</td> - <td align="center">32</td> - <td align="center">2</td> - <td align="center">1</td> - <td align="center">3</td></tr> -<tr> - <td align="left">Molasses</td> - <td align="center">12</td> - <td align="center">—</td> - <td align="center">8</td> - <td align="center">1</td> - <td align="center">12</td> - <td align="center">6</td> - <td align="center">2</td> - <td align="center">8</td></tr> -<tr> - <td align="left">Paris white</td> - <td align="center">1</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">1</td></tr> -<tr> - <td align="left">Sugar</td> - <td align="center">—</td> - <td align="center">10</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td></tr> -<tr> - <td align="left">Glycerin</td> - <td align="center">—</td> - <td align="center">12</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">56</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td></tr> -<tr> - <td align="left">Isinglass</td> - <td align="center">—</td> - <td align="center">1½<br />ozs.</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td></tr> -<tr> - <td align="left">India rubber<br />in naphtha</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">10</td> - <td align="center">—</td> - <td align="center">—</td> - <td align="center">—</td></tr> -</table></div> - - -<p>A patent roller composition is thus made: Gelatine 32 -lbs. and glue 4 lbs. are softened in cold water and melted -in a glue boiler. To this are added 4 lbs. of glucose, 72 lbs. -of glycerine, and 1 oz. of methylated spirit. The whole is -then digested for four to six hours and cast into rollers. -This composition is claimed to be unaffected by temperature, -to retain its elasticity, and not to shrink.</p> - -<p>In practice it is found that all these compositions from -the cleansing and remelting become gradually sticky and -useless. To partially overcome this difficulty, formaldehyde -is added to the roller composition, which renders the glue -insoluble in water, and thus prolongs the life of the roller.</p> - -<p><i>Size.</i> This product is simply an undried glue and is -used, not for adhesiveness, but as a body for filling porous -surfaces, such as wood or plaster, stiffening and weighting -textile fabrics, in paper manufacture, and as a foundation -for oil paints and varnishes. According to Thomas Lambert, -many firms who have a good selling connection for -size, do not go to the expense of erecting clarifying plant -and drying house for treating the glue-liquors, but prefer<span class="pagenum" id="Page_158">158</span> -to stop the process half way, as it were, and marketing the -resulting product as size. Others, again, with a complete -glue plant at hand, convert only a portion of their liquors -into size, to meet trade demands, the bulk going for the -manufacture of glue. Size varies in quality to suit the -requirements of different trades. Cardboard box-makers -prefer a strong skin size, which is manufactured red or -yellow as preferred. A strong yellow size made from bone -is used by calico-printers, paper-stainers, wall-paper manufacturers, -and in the straw-hat and carpet trades.</p> - -<p>In the preparation of skin-glue, the first and second -liquors are used for that purpose; the residual mass is then -treated with water and steam, which practically exhausts -the gelatinous matter. This, the third liquor, is used solely -for size. During the boiling, samples are taken at intervals, -cooled, and the condition of the jelly noted. The strength -is also taken by the glue meter, which registers the percentage. -At a strength of 8 to 10 per cent. the liquor is run -off, passing through a filter of fine shavings or cloth, to -remove any suspended matter, into a wooden vat fitted -with a steam coil, then heated with a moderate charge of -sulphurous acid to bring up the color, and evaporated to a -strength of 36 to 38 per cent., as may be desired, and then -run into casks to jelly. If skin-glue is not made, the three -runnings are used entirely for size.</p> - -<p>An outline of a simple process used in an English factory -devoted to making tub-size, as given by Samuel Rideal, -may be interesting.</p> - -<p>The material is obtained from the tanyard ready limed -and freed from hair, and consists mainly of “faces” of -bullocks or cows, the noses being cut off as food for dogs. -It is soaked again in weak lime water and re-washed, then -placed in coppers made of wrought-iron wielded in one -piece, and holding about 10 to 20 gallons, enclosed in outer -jackets of the same material containing water which is kept -well boiling. There are six coppers, about five feet high<span class="pagenum" id="Page_159">159</span> -by three feet in diameter. The charge of each is about ½ -cwt. The material is covered with water and well stirred -with sticks for two hours, the scum and dross being occasionally -skimmed off and thrown away as useless. At the -end the size is ladled on to sieves, from which it runs into -cooling vats, and is filled while moderately hot into clean -tubs.</p> - -<p>The liquor is clear and of a light brown color for the -best XX quality, and darker for the common. The coolers -or setting-backs are of wood or zinc, and the liquid is not -kept hot longer than it can be helped, as it is liable to turn -sour.</p> - -<p>Bone-size is, according to Thomas Lambert, prepared as -follows: The bones are first degreased by the naphtha process, -and then passed through the cleanser direct into the -glue-boilers and steamed, as in the manufacture of glue. -The resulting liquors are forced up to the clarifying vats -and partially bleached with a current of sulphurous acid, -passing through bag-filters to the evaporating troughs, and -concentrated from 30 to 38 per cent., as required, and then -jellied in casks.</p> - -<p>The manufacturer with no benzine or glue plant at his -disposal washes the bones in a revolving drum, and, after -crushing, they are fed into a boiler and subjected to an -alternate current of steam and water, the latter coming -from a spray pipe fixed at the top of the boiler. The -liquors are generally drawn in two portions, having a -strength of 14 to 16 per cent. of glue. After separating the -fat, which is refined and sold to the soap-maker, the liquors -are run into a large wooden vat about 8 × 6 × 4 feet, fitted -with a steam coil, partly bleached with liquid sulphurous -acid, and then boiled down to the required strength.</p> - -<p>For a common size the bones are crushed but unwashed, -and are fed direct into the boiler and treated as above. The -liquors are not bleached, and boiled to a strength of about -25 per cent. glue. The composition of the different grades -may be given as follows:</p> - -<p><span class="pagenum" id="Page_160">160</span></p> - -<p> -Common size. 25 per cent. glue, 75 per cent. water, etc.<br /> -Medium size. 30 per cent. glue, 70 per cent. water.<br /> -Best size. 38 per cent. glue, 62 per cent. water.<br /> -</p> - -<p>A concentrated size is now prepared by many manufacturers. -It is a bone-size, and is sold at a Baumé strength -at 122° C.</p> - -<p> -No. 1. 15° Bé. at 122° C., 40.5 per cent. glue.<br /> -No. 2. 20° Bé. at 122° C., 44.5 per cent. glue.<br /> -No. 3. 25° Bé. at 122° C., 49 per cent. glue.<br /> -</p> - -<p>Under the name of concentrated size also are sold a -series of powdered glues of different qualities. They are -the off-color and twisted cakes, sorted out in the warehouse, -and ground to a fine condition by passing through a mill, -and their value is based on the quality of the cake ground.</p> - -<p>Size rapidly ferments and becomes sour and mouldy -unless some preservative is added. Sulphate of zinc is -mainly used for this purpose.</p> - -<p><i>Bookbinders’ Size.</i>—I. Water, 2 quarts; powdered alum, -1 oz.; Russian isinglass, 2 ozs.; curd soap, 40 grains. Simmer -one hour, strain through linen or a fine sieve, and use -while warm.</p> - -<p>II. Water, 2 gallons; best glue, 1 lb.; alum, 4 ozs. -Prepare and use as above.</p> - -<p>III. Water, 2 quarts; isinglass, 5 ozs.; alum, 240 grains.</p> - -<p><i>Water-proof Glue.</i>—Solution of glue by itself or mixed with -pigments is used in painting walls in distemper. A water-proof -coat is obtained as follows: Boil 1 part of powdered -gall-nuts and 12 parts of water until the mass is reduced to -two-thirds of its bulk. Then strain through a cloth and -apply the solution to the dry coat of distemper paint, the -latter becoming thereby as solid and insoluble as oil-paint. -The tannin of the gall-nuts acting only upon soft glue, the -solution has to be applied so the lower layer of glue becomes -thoroughly soaked through.</p> - -<p>To render <i>wrapping paper</i> water-proof the following glue-solution -may be used: Dissolve 24 parts of alum and 4<span class="pagenum" id="Page_161">161</span> -parts of white soap in 32 parts of water in one pot, and in -another 2 parts of gum arabic and 6 parts of glue in 32 -parts of water, and mix the two solutions. Heat the mixture, -immerse the wrapping paper in it, and pass it through -hot rolls, or dry upon twine stretched in frames.</p> - -<p><i>Fabrics may be rendered water-proof</i> with glue and tannin. -The process is based on the fact that by the action of tannin -or bichromates, compounds insoluble in water are formed. -It is, however, of first importance that both solutions—tannin -and glue—should fully penetrate the fabric. If the -latter is dipped directly into strong solution of glue and -then of tannin, the glue will only become insoluble on the -outside, and that which has penetrated deeper into the -fibre will be unchanged, having been protected by the -superficial insoluble layer. Hence, the treatment is commenced -with a very weak solution of glue, prepared by -leaving glue broken small in hundred times its weight of -water for twenty-four hours. By that time the glue will -have swelled up, and the whole is boiled, whilst being constantly -stirred, so as to get a perfectly clear solution in -which the fabric is boiled for 10 to 15 minutes. This time -is no more than necessary for complete penetration. The -fabric is then well wrung between two rollers placed over -the glue-bath so that excess of solution runs back into it. -The fabric is then hung up, and when nearly dry is passed -through a tannin solution. The latter may be made from -tannin itself, or from a tannin extract, or by boiling galls -or oak bark in water. The tannin solution can be used -fairly strong, as only so much of it is taken up as corresponds -to the glue present, and it can be used over again as -long as it can supply the tannin required, and can then be -reinforced with more tannin as required.</p> - -<p>It is not necessary for the fabric to stay long in the -tannin, as it reacts quickly with the glue. The tanned -material is again hung up to dry, and when quite dry is -washed in plain water to remove any excess of tannin. The<span class="pagenum" id="Page_162">162</span> -whole process from the beginning is then twice repeated. -After this second repetition there is so thick a layer of tannate -of gelatine on the fabric that the dry cloth has -acquired considerable solidity and a smoothness which -recalls that of leather. The fabric is now passed through a -stronger glue solution, using three or even four parts of -glue per hundred of water, but never exceeding the latter -limit. After the glue-bath the fabric goes through the -tannin bath, whereby it becomes quite thickly coated with -tannate of gelatine. By repeatedly treating with glue and -tannin alternately, this coating can be made as thick as -desired, and finally masses are obtained in which the -texture of the fabric is entirely hidden, and especially after -the fabric has been calendered under heavy pressure after -water-proofing. The color acquired by goods thus water-proofed -is a more or less dark leather-brown.</p> - -<p>Muratori and Landry treat the fabric with a solution -made in three separate operations:</p> - -<p>1. Potash alum 100 lbs. dissolved in 10 gallons of boiling -water.</p> - -<p>2. In another vessel 100 lbs. of glue are soaked in cold -water till the glue has trebled in weight. The remaining -water is poured off, and the glue liquefied by the application -of heat. When the glue is boiling, 5 lbs. of tannin and -2 lbs. of soda water glass are put in it.</p> - -<p>3. The two solutions are boiled together, being stirred -constantly.</p> - -<p>When the mixture is complete, it is allowed to cool to a -jelly. To water-proof the goods some of the jelly is boiled -with water (1 gallon to 1 lb., or a little over) for three -hours, adding water to compensate for evaporation, so as to -keep the volume of the solution constant, as shown by tests -of its specific gravity with a hydrometer. The bath is then -allowed to cool to 176° F., and the fabric is soaked in it for -half an hour and then stretched out horizontally for six -hours to drain. The fabric must be kept horizontal, so that<span class="pagenum" id="Page_163">163</span> -the solution remains uniformly distributed through it. The -drainings are collected to be used over again. The fabric -is then dried in the open air or in a drying room, still in -the horizontal position. If a drying room is used the temperature -of it should not exceed 122° F.</p> - -<p>Muzmann and Krakowitzer dissolve 10 lbs. of gelatine -and 10 lbs. of tallow soap in 30 gallons of boiling water, -and mix the solution in 4 gallons of water in which 15 lbs. -of alum have been dissolved. The whole is boiled for half -an hour, and then allowed to cool to 104° F. At that -temperature the fabric is thoroughly soaked in it, dried, -rinsed, again dried, and finally calendered. In this process -the alum partially decomposes the soap, forming either -free fatty acid or an acid alumina soap. The gelatine forms -an insoluble compound with the alum. The free fatty acid -or acid soap is mostly carried down on the fibre by the precipitate -formed by the alum and the gelatine.</p> - -<p><i>Glue for Joints in Leather Driving Belts.</i>—Soak equal parts -of good hide glue and isinglass in water for 10 hours, and -then boil with pure tannin till the product becomes sticky. -The surfaces to be cemented together should be roughened -and the glue applied hot.</p> - -<p>According to another method 2 lbs. of best glue are dissolved -at a moderate heat in 3 lbs. of water and about 3 -drachms of carbolic acid stirred into the hot solution. The -mixture is poured into shallow iron pans to congeal, when -it is cut in pieces and dried in the air. For use the glue is -liquefied by adding a small quantity of vinegar and applied -with a brush to the leather. The joint is finally pressed -between iron plates at a temperature of about 77° F.</p> - -<p><i>Hectograph Mass.</i>—Soak a good quality of glue for 24 -hours in sufficient cold water to cover it. Then take the -swelled glue from the water and melt it in an enameled pot -over a moderate fire. When perfectly liquid add the required -quantity of glycerine (see formulas below) and intimately -mix both by continued stirring.</p> - -<p><span class="pagenum" id="Page_164">164</span></p> - -<p>The vessel containing the mixture should for some time -be kept hot, so that the mass remains thinly fluid. The -purpose of this is to allow the air-bubbles formed by stirring -to rise to the surface. If any scum is formed on the surface, -remove it carefully with a shallow spoon. The composition -is then ready to be poured into the vessel intended -for its reception, which may be made especially for the -purpose, or a shallow baking pan of tin may be used. -When the pan is filled with the composition place it perfectly -level in a cool place free from dust and allow to -remain at least for several hours.</p> - -<p><i>Formulas for Hectograph Masses.</i>—I. Gilder’s glue, 100 -parts; glycerine of 28° Bé., 500.</p> - -<p>The glue is allowed to swell in water, as described above, -then melted, mixed with the glycerine, and evaporated to -the required consistency.</p> - -<p>II. Gilder’s glue, 100 parts; glycerine of 28° Bé., 400; -water, 200.</p> - -<hr class="chap" /> - -<p><span class="pagenum" id="Page_165">165</span></p> - - - - -<div class="chapter"></div> -<h3><a name="CHAPTER_IX" id="CHAPTER_IX">CHAPTER IX.</a><br /> - -<small>MANUFACTURE OF GELATINE, AND PRODUCTS PREPARED -FROM IT.</small></h3> - - -<p>Gelatine, like glue, is produced from hides and skins, -and bones. It is distinguished by its purity, has a slight -yellowish tint, and is very hard and elastic. In cold water -it softens, swells up, becomes opaque, but does not dissolve. -In hot water it dissolves completely, and on cooling for -several hours, an almost colorless, transparent and very -firm jelly results. This property of becoming jellied is in -part lost if the solution is for some time exposed to a temperature -higher than 212° F.</p> - -<p>The chemical constitution of gelatine is entirely changed -by concentrated sulphuric or nitric acid. Concentrated -acetic acid, on the other hand, renders softened gelatine -transparent, and then dissolves it; the solution does not become -viscid, but preserves its adhesive property. Dilute -acids have no appreciable effect either on the coagulating -or the adhesive power.</p> - -<p>Tannin is a valuable and delicate test of the presence of -gelatine. When added to a solution containing only -1/5000th part of gelatine, nebulosity is immediately apparent. -When more concentrated gelatinous liquors are treated with -tincture or infusion of nut gall, a dense, white, caseous subsidence -occurs which, on desiccation, becomes brownish-yellow, -agglutinates, and forms a hard, brittle mass easily -reduced to powder.</p> - -<p>Gelatine is much used for culinary and medicinal purposes, -and for fining beer, wine and other liquids. Considered -medicinally, it is emollient and demulcent, and for -this end is dissolved in water or milk, and rendered pala<span class="pagenum" id="Page_166">166</span>table -by the addition of acid and sugar. In pharmacy, it -is used for the formation of capsules intended to conceal the -nauseous odor and taste of medicinal preparations inclosed -in them. It is likewise employed for coating pills.</p> - - -<h4>SKIN GELATINE.</h4> - -<p>But few changes have been made in the process of manufacturing -skin gelatine since the method introduced and -patented, in 1839, by George Nelson. This patent relates -to the preparation of a transparent gelatine from waste of -calf skins, and of an inferior variety from other skins freed -from hair, wool, and fleshy and fatty matters. The mode -of procedure is the same in both cases, and is as follows: -The cuttings being washed are macerated in solution of -caustic soda or caustic potash at a temperature of 60° F., -until they are partially softened. Ten days is the average -period required to effect this. They are then placed in -closed vessels and permitted to remain until a thorough -softening is effected. They are now washed in a revolving -cylinder, through which a current of water passes to free -them from adhering alkali; exposed in a well-closed chamber -to the action of sulphurous acid, and finally submitted to -pressure to remove the adhering water. The softened mass -bleached by sulphurous acid is then placed in a suitable -vessel and subjected to the action of steam until it is, as -far as possible, dissolved. The liquor is then strained and -set aside at a temperature of 100° to 120° F. for the impurities -which may have remained to subside. The clarified -solution is poured upon slabs of slate or marble to the -depth of about half an inch and allowed to remain there till -sufficiently solidified, when it is cut, and washed to remove -all traces of acid. It is subsequently redissolved by means -of a steam bath at a temperature of 95° F., finally again -solidified, and dried by exposure to dry air upon nets.</p> - -<p>Messrs. J. and G. Cox, of Edinburgh, patented in 1844, a -process by which a perfectly pure substance, superior to<span class="pagenum" id="Page_167">167</span> -that prepared from isinglass is obtained. Shoulders and -cheeks of ox-hides are preferred by the patentees. They -are thoroughly cleansed in water, after which they are cut -into pieces by a machine similar to that used for cutting -straw, and then subjected to the action of a paper-maker’s -pulp-mill. By this process the gelatinous fibre is well -washed and cleansed, as a stream of water flows through -the mill during the whole operation, carrying off all the -impurities. The comminuted material is next pressed between -rolls, mixed with fresh water, sufficient to effect its -solution, and heated to a temperature varying from 150° to -212° F. The resulting gelatine-solution is then allowed to -cool to 150° F., and mixed with fresh bullock’s blood—1 -part of the latter to 700 parts of solution. At a somewhat -increased temperature the albumen of the blood coagulates -and rises in the form of foam to the surface, or subsides in -the shape of flakes, carrying with it the impurities, and -thus clarifying the liquor. The latter is allowed to stand -for some time, when it is poured upon stone slabs and -allowed to solidify.</p> - -<p>G. P. Swinborne’s improved patented process for the -preparation of gelatine from hides, skins and glue pieces, -relates mainly to the cleansing of the raw material. The -latter is reduced by means of suitable instruments to shavings -or slices, and soaked in cold water, which is drained -off and replaced by fresh water three times a day, until no -odor or taste is perceptible. The shavings are then heated -with water, not above boiling, strained through filter cloths, -and the liquor is then run on to slate or other material -to dry.</p> - -<p>The modern process of preparing skin gelatine is, according -to Thomas Lambert, carried out as follows: The first -treatment the cleansed skins undergo is the “steeping” -process with caustic soda or milk of lime. In some factories -a mixture of caustic (slaked) lime and soda ash is -used, in the proportion of 6 lbs. soda ash and 6 lbs. slaked<span class="pagenum" id="Page_168">168</span> -lime to every hundred-weight of skins treated, the chemical -change being that the whole of the carbonate of soda (soda -ash) is converted into caustic soda by its equivalent of -caustic lime, the excess of the latter remaining as such. -The equation representing this is—</p> - -<div class="center"> -<table border="0" cellpadding="4" cellspacing="0" summary=""> -<tr> -<td class="ct">Na<sub>2</sub>CO<sub>3</sub><br /><small>Soda ash.</small></td> -<td class="ct">+</td> -<td class="ct">CaH<sub>2</sub>O<sub>2</sub><br /><small>Caustic lime.</small></td> -<td class="ct">=</td> -<td class="ct">2NaHO<br /><small>Caustic soda.</small></td> -<td class="ct">+</td> -<td class="ct">CaCO<sub>3</sub><br /><small>Carbonate of lime.</small></td> -</tr> -</table></div> - -<p>This steeping is conducted in large wooden vats, each -having a length of 12 feet, width 8 feet, and depth 3 feet, -and fixed with a slight gradient to the overflow, which is -placed at the most convenient corner of the vat and protected -by perforated boards. The skins in the vat are -nearly covered with water, and then the solution of caustic -soda, or the slaked lime mixed in water to a cream, is -sprayed equally over the mass, the whole being intimately -mixed with long stirring poles. The water is renewed -twice during a period of 12 days, the time allowed for the -skins to soak. They are now removed to a chamber, in -which a moderate increase of heat facilitates the saponification -of the fat and the dissolving of the fleshy matter. The -chamber is a brick building, with a cemented floor, on -which the skins are spread to a uniform depth of about six -inches and is heated by steam pipes running round the building. -At a temperature of about 70° F. the skins are exposed -two or three days, with frequent turning. They are -now transferred to the washing machine and washed until -the effluent is practically free of soda or lime. The skins -then undergo a bleaching process to whiten, and thus destroy -any injurious coloring matter. For this purpose the -washed skins are removed to a number of vats fitted with -folding covers, and treated to a solution of sulphurous acid -of ½° Twaddell strength for 24 hours, each vat being well -stirred at intervals to allow the “bleach” to permeate -equally the mass.</p> - -<p>In some factories this process is carried out with dry sul<span class="pagenum" id="Page_169">169</span>phurous -acid, the gas being generated in a sulphur burner -and, after washing, passed into a chamber containing the -skins. The vats are now drained, then filled up with -water, well stirred, and the water run off. This is repeated -until the effluent is practically free of any sulphurous smell, -and the work of dissolving the gelatine is proceeded with. -The digesting of the skins is carried on in stoutly built, circular -wooden vats, each having a size, generally of 4 feet 6 -inches diameter and 6 feet deep, and fitted with 2¼ inch -copper steam coil. The vats are provided with a double -wooden bottom to divide the heat. They are arranged on -the first floor of the building, the liquors running through -a shallow filter of fine copper gauze to the clarifying vats -beneath. The skins are raised by an elevator and fed direct -into the vats by suitably-arranged troughs, then covered -with water, and steam is sent through the coils. The temperature -is frequently taken by the thermometer and should -never exceed 177° F. During the digestion, any unsaponified -fat and dirt comes to the surface as a scum, and is carefully -skimmed off from time to time. Samples are also -drawn of the liquors, cooled, and the appearance and -strength of the jelly noted. After five to six hours’ heating, -the first liquors are run off to the clarifying vats, at a -strength of about 17 per cent. gelatine.</p> - -<p>The vats are refilled with water, and a second digestion -made, the liquor running to the clarifying vats at a strength -of 12 per cent. In the third digestion the temperature is -raised a few degrees to practically exhaust the gelatinous -matter, and can either be clarified to form an inferior gelatine, -or concentrated for size. The exhausted matter is taken -to the manure-shed for mixing purposes. The clarifying of -the first and second liquors—and if used for gelatine the -third liquor—is done separately in the clarifying vats. The -clearing agent used is alum, to the extent of ½ per cent., or -a little blood diluted with water; both are mixed with a -small portion of the hot liquors in a bucket, and then well<span class="pagenum" id="Page_170">170</span> -stirred in the vats. The liquors are raised to 177° F. to -coagulate the impurities, and then lowered to 149° F. and -allowed to stand for two hours. During this time the -coagulated matter rises to the surface, and is skimmed off. -On leaving the vats, the liquors are filtered through fine -copper gauze into a receiver from which is fed the vacuum -pan.</p> - -<p>Gelatinous liquors being peculiarly sensitive, especially -as regards color, to high temperatures, it is found advisable -to evaporate them in vacuo; and this method is adopted -by all continental makers. The three grades of the liquors, -concentrated to the required strength, are run on to squares -of glass, 4´ × 4´, fixed in a wood framing, to a depth of ½ -inch for cake and ¼ inch for leaf gelatine, then placed -perfectly level on racks for jellying. In 24 hours the jelly -is firm, and can be easily cut to the desired size of cake or -leaf wanted. A very fine gelatine is produced by cutting -the jelly into small pieces, washing well with cold water, -and remelting at a temperature of 176° F., and poured -again on the glasses for jellying.</p> - -<p>The drying is carried on by exposing the cut cakes, on -nets fixed to a framework of wood, to a rapid current of dry -air in the tunnels, as described in the drying of glue.</p> - - -<h4>BONE GELATINE.</h4> - -<p>The materials used for this purpose should be of the best -description, the most suitable bones being calves’ feet, waste -of turners and button makers, the bony cores of the horns -of the ox and cow. Such bones do not require comminution, -but if large bones of oxen, horses, etc., are to be used, it is -recommended to break them as small as possible by means -of a wooden mallet, and to avoid the use of iron stampers, -as the bones become heated by the heavy blows and friction -to which they are subjected during the process, and acquire -an empyreumatic odor which is retained by the gelatine.</p> - -<p>The next step in the process is the solution of the glue<span class="pagenum" id="Page_171">171</span> -cartilage. This was formerly effected by the use of steam -and water. The crushed bones were placed in a wire -basket or cage and this inserted in a small cast-iron cylinder -and steam introduced. The apparatus is connected -with a steam boiler, and provided with an air-tight lid, and -a pipe and a rose connected with a water reservoir for pouring -water over the bones in order to promote the solution -of the glue cartilage. But this process is very slow, 20 -hours being required without completely exhausting the -bones.</p> - -<p>The resulting gelatinous liquor is drawn off every hour, -the first run, which contains the dirt and grease, being, -of course, kept separate from the rest.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 59.</span></div> -<img src="images/i_p171.jpg" alt="" /> -</div> - -<p>As will be readily understood this process consumes -much fuel, and leaves a residue which, though not completely -exhausted, cannot be further utilized for the preparation -of gelatine. In fact the entire process is obsolete, -but as it is still in use in some localities, a description is -here given, for the sake of completeness, of the apparatus -and improved manner of manufacture employed in the -factory of D. J. Briers, which is well known for the beautiful -product turned out.</p> - -<p>Fig. 59 shows a longitudinal section of the entire apparatus.</p> - -<p>Fig. 60 is the horizontal section of the boiler.</p> - -<p><span class="pagenum" id="Page_172">172</span></p> - -<p><i>a</i>, is the cylindrical boiler 6 meters (19.68 feet) long, and -2 meters (6.56 feet) in diameter. It is made of strong -boiler plate doubly riveted, and capable of resisting a pressure -of six or seven atmospheres.</p> - -<p><i>b</i>, is the manhole. It is closed by an oval lid secured -by two iron rods and two bolts, so that after placing the lid -in position, the boiler is hermetically closed by tightening -the nuts upon the bolts.</p> - -<p><i>c</i>, is a cast-iron fork with two safety valves with levers -graduated from 1 to 100 atmospheric degrees.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 60.</span></div> -<img src="images/i_p172.jpg" alt="" /> -</div> - -<p><i>d</i>, is a float upon the surface of the water, and provided -with a wheel graduated from Nos. 1 to 6. Its object is to -indicate during the operation how much water is lost and -how much remains in the boiler. Care must be had not -to allow the indicator of the wheel to get below No. 1. This -figure indicates that the water has reached the highest point -in the boiler exposed to the fire, which is consequently the -lowest point which the water can be allowed to reach. On -the other hand the indicator must not move above No. 6, as -the water when standing too high in the boiler and too -close to the pipes conducting the steam into the various<span class="pagenum" id="Page_173">173</span> -apparatuses might mix with the steam and spoil the operation -carried on in the drum, <i>e</i>, Fig. 60.</p> - -<p><i>f</i>, Fig 60, is a manometer, which indicates the degrees of -pressure exerted by the steam in the interior of the boiler. -It consists of a wrought-iron pipe bent double, and is filled -with mercury 1.22 meter (4.002 feet) high counted from its -base. One end of the pipe communicates with the boiler, -while the other end is provided with a small brass wheel. -Upon the latter is a thread of twisted silk, to the end of -which is suspended an iron cylinder of somewhat smaller -circumference than the bore of the pipe, so that it can move -up and down in it without friction. This cylinder rests -always upon the mercury. To the other end of the thread -is fastened an indicator of somewhat less weight than the -cylinder, which, by sliding in a groove in a graduated -board placed alongside the pipe, indicates the degrees of -steam pressure.</p> - -<p><i>g</i> is a cast-iron pipe for heating the drying room, and</p> - -<p><i>h</i> another cast-iron pipe for heating the store-room for -the bones.</p> - -<p><i>i</i> is the forcing pump for feeding the boiler with water.</p> - -<p><i>k</i> is a sheet-iron reservoir placed close to the end of the -boiler. It is filled with water, which is heated by the heat -lost in the fire-place in consequence of the draught, and by -allowing the smoke to circulate under the reservoir before -passing into the chimney. The reservoir communicates -with the forcing-pump by means of a pipe and stopcock, -so as to avoid feeding the boiler with cold water.</p> - -<p><i>l</i> is the fire-place, consisting of the grate, door and cast-iron -frame.</p> - -<p>The drum, <i>e</i>, is a spherical vessel of strong sheet-iron -doubly riveted. It is 3 meters (9.84 feet) in diameter, and -capable of resisting a pressure of six to seven atmospheres. -It serves for softening the bones with the assistance of steam -passed into it from the boiler, <i>a</i>. It is provided with a -manhole similar to that of the boiler.</p> - -<p><span class="pagenum" id="Page_174">174</span></p> - -<p><i>n</i> is a wrought-iron shaft passing horizontally through -the drum and revolving in the brasses, <i>o</i>.</p> - -<p><i>g</i>, Fig. 61, is a gearing with a crank, by means of which -the drum <i>e</i> is revolved. The power of the gearing must be -so calculated that one man can turn the wheels when the -drum is filled with water.</p> - -<div class="figcenter" > -<img src="images/i_p174.jpg" alt="" /> -<div class="caption"><span class="smcap">Fig. 61.</span></div> -</div> - -<p><i>r</i> is a false bottom perforated in its entire length with -holes 12 millimeters (0.47 inch) in diameter, and is placed -about 15 centimeters (5.9 inches) above the true bottom of -the drum. It consists of two pieces, and is secured by two -nuts, so that it can be easily removed and replaced. Its -object is to prevent the bones from clogging up the pipe <i>s</i>, -and the cocks <i>t</i>, <i>u</i>.</p> - -<p><i>a</i>, <i>a</i>, Fig. 61, are angular iron points inside of the drum -<i>e</i>. Their object is to facilitate the shifting of the bones -when the drum is revolving.</p> - -<p><i>x</i>, Fig. 59, is a cock near the manhole. It is opened -about 2 millimeters (0.079 inch) during the operation in -the drum. It serves also for the escape of the steam from -the drum when the operation is finished.</p> - -<p>The cocks <i>t</i>, <i>u</i>, placed in the lower part of the drum, -serve for the escape of steam condensed during the operation.</p> - -<p>The steam pipe <i>p</i>, Fig. 59, conducts the steam from the -vessel <i>a</i> into the drum <i>e</i>.</p> - -<p><i>y</i>, Fig. 59, is a cock graduated into eight equal parts and<span class="pagenum" id="Page_175">175</span> -placed on the steam pipe <i>p</i>, to conduct the steam from the -box <i>z</i>, into the stuffing box <i>a´</i>, and from there into the pipe -<i>s</i>, then under the false bottom <i>r</i>, into the drum <i>e</i>.</p> - -<p>The lid of the cast-iron box <i>z</i>, is provided with a safety -valve loaded with a weight corresponding to the pressure of -one atmosphere.</p> - -<p>The wooden vessel or box <i>d</i>, the ground-plan of which is -shown in Fig. 62, serves for boiling the comminuted bones -in order to extract the jelly. This box consists of the following -parts:—</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 62.</span></div> -<img src="images/i_p175.jpg" alt="" /> -</div> - -<p><i>n</i>, are cast-iron steam pipes occupying the entire surface -of the box, being placed at equal distances from each other, -and connected on their ends by semicircular pieces. The -steam, which is allowed to circulate in the pipes in order to -boil the liquid, enters through one of the ends which rises -up vertically and is connected with the cock <i>h´</i>, Fig. 59. -The other end is secured to the inner side of the box, which -is perforated for the admittance of the cock <i>o´</i>. Upon the -steam pipes lies a wooden framework with linen nailed -upon it, the object of which is to prevent the comminuted -bone substance from falling under the pipes. The frame -must, of course, fit closely into the box.</p> - -<p>The cock <i>h´</i> graduated in eight equal parts serves to -admit steam into the pipes <i>n´</i>, and is opened either entirely -or half, or one-quarter, or one-eighth, according to the -stronger or gentler ebullition to be produced.</p> - -<p>To prevent the steam from becoming stagnant in the<span class="pagenum" id="Page_176">176</span> -steam pipes <i>n´</i>, a small jet is allowed constantly to escape -through the cock <i>o´</i>. The latter serves also to run off the -condensed steam when it no longer possesses the heat required -to keep up ebullition.</p> - -<p><i>p´</i>, Fig. 62, is a cock in the bottom of the box <i>d´</i> for -drawing off the gelatinous solution from the residue. The -box <i>e´</i>, Fig. 62, a ground-plan of which is shown in Fig. 63, -serves for evaporating the gelatinous solution, which is -effected by circulating steam through several tubular pieces -of cast-iron which form the bottom of the box and are connected -in a similar manner as the pipes in the box <i>d´</i>.</p> - -<p>The cock <i>i</i> is graduated and similar to <i>h´</i>.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 63.</span></div> -<img src="images/i_p176.jpg" alt="" /> -</div> - -<p>The cock <i>r´</i>, Fig. 63, is similar to <i>o´</i>, Figs. 59 and 62.</p> - -<p><i>s´</i>, Fig. 63, is a cock for drawing off the evaporated -gelatinous solution.</p> - -<p>The wooden box <i>f´</i>, Fig. 59, a ground-plan of which is -shown in Fig. 64, serves for the reception and settling of -the evaporated gelatinous solution. Its bottom is constructed -in a manner similar to that of the box <i>e´</i>.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 64.</span></div> -<img src="images/i_p176-1.jpg" alt="" /> -</div> - -<p>The cock <i>n´</i>, which is placed 14 millimeters (0.55 inch) -above the bottom of the box, serves for running the gelatinous -solution into the wooden cooling-boxes.</p> - -<p><span class="pagenum" id="Page_177">177</span></p> - -<p>The bones as received in the factory are sorted by throwing -out the spongy material, etc. They are then steeped in -lime-water for a few days to free them from adhering particles -of flesh, after which they are dried and stored away -for future use.</p> - -<p>The boiler <i>a</i>, is filled two-thirds with water, and heated -until the manometer indicates a pressure of 30°. In the -meanwhile the drum <i>e</i>, is filled seven-eighths with perfectly -dry bones, and steam is then admitted from the boiler <i>a</i>, -through the graduated cock <i>y</i>. The fact that the bones in -the drum are exposed to the proper temperature of 250° F. -is recognized by the thermometer <i>b´</i>, placed between the -cock and the drum.</p> - -<p>To prevent the stagnation of the steam in the drum, <i>a</i> -small jet of it is allowed constantly during the operation to -escape through the cock <i>x</i>. The cock must not be opened -wider than is necessary to keep the temperature at 250° F. -By opening it wider, this degree would be exceeded, and -the gelatine-yielding substance would, in consequence, -undergo alteration. A quarter of an hour after admitting -the steam into the drum, the cock <i>t</i>, is opened, and again -closed after allowing a small portion of the condensed steam -to escape to the cock <i>u</i>, and, through this, into a box. This -operation is repeated every quarter of an hour.</p> - -<p>To change the position of the bones, the drum is revolved -twice every half hour, by means of the gearing <i>q</i>, of course -closing the cock <i>x</i> during the operation.</p> - -<p>By carefully following the above rules, the bones will be -thoroughly reduced in four hours. If, for instance, steam -has been introduced into the drum at 5 o’clock a. m. the -operation will be finished at 9 a. m. The cock <i>y</i>, is then -closed, and the steam allowed to escape through the cock <i>x</i>. -After the escape of the steam, the drum is emptied, by removing -the lid and turning it upside down. It is then refilled -with entirely dry bones, and the operation continued -in a like manner, day and night, if necessary.</p> - -<p><span class="pagenum" id="Page_178">178</span></p> - -<p>After the bones have been taken from the drum, they are -spread out under a shed, and, when dry, ground in a suitable -mill. The resulting flour, which contains the jelly-yielding -substance, is brought into the vessel <i>d´</i>, which, in -the meanwhile, has been furnished with sufficient water to -cover the flour 65 centimeters (25.59 inches) deep. The -mixture is boiled for three-quarters of an hour, being constantly -stirred to prevent the flour from forming a heavy -and dense mass which would hinder the quick extraction -of the jelly. Ebullition is then interrupted by closing the -cock <i>h</i>, and the fat floating on the surface skimmed off. -After allowing the gelatinous solution to settle, it is drawn -off by means of a faucet placed above the level of the flour. -Thirty bucketfuls of the gelatinous solution are then at once -poured into a vat and mixed with the condensed steam -drawn off by means of the cocks <i>t u</i>, during the reduction -of the bones in the drum. After allowing the mixture to -cool to 160° to 155° F., 20 kilogr. (44 lbs.) of pulverized -alum are added at once and as quickly as possible. When -the gelatinous solution has become transparent, it is drawn -off into the box <i>e´</i>, and a few bucketfuls of hot water are -poured upon the sediment in the vat in order to extract the -remaining jelly, which is effected by thorough stirring and -allowing to settle until the water is entirely clear.</p> - -<p>After disposing of the 30 bucketfuls in the manner mentioned, -the remainder of the gelatinous solution is evaporated. -This is accomplished in the box <i>e´</i>, which is filled 8 -centimeters (3.15 inches) deep with gelatinous solution, and -steam is then admitted into the tubular bottom pieces. To -promote evaporation and keep the fluid constantly in motion, -the cock <i>i´</i> is only opened far enough to keep up -gentle ebullition. During evaporation the solution should -be frequently stirred with an implement resembling a rake. -The nearer the required degree of concentration is approached, -the greater care must be exercised to prevent the -solution from boiling too strongly. The proper degree of<span class="pagenum" id="Page_179">179</span> -consistency is obtained when half a saucer full of the solution -placed in a shady place in the air acquires in a short -time such a consistency that when touched with the finger -no impression remains. The cock <i>i´</i> is then closed, and the -jelly is drawn off into the box <i>d´</i>, which contains the 30 -bucketfuls of clarified jelly, care being had to mix the two -solutions as quickly as possible. After evaporating all the -gelatinous solution and mixing it in the box <i>d´</i>, the whole -is heated to 158° F., by admitting steam through the cock -<i>k´</i>, care being had not to forget closing it as soon as the -above temperature has been reached. The solution is then -thoroughly stirred and permitted to settle for three hours -to allow of the precipitation of the lime salts decomposed -by the alum. The fluid, which is now perfectly transparent -and of a beautiful dark-yellow color, is then drawn off -into wooden cooling boxes 2 to 2.5 meters (6.56 to 8.2 feet) -long, 20 centimeters (7.87 inches) wide, and 16 centimeters -(6.30 inches) deep. The following day the gelatine is cut -into leaves 25 centimeters (9.84 inches) long and 12 centimeters -(4.72 inches) wide, which are dried upon nets. -When quite dry, the drying process is finished by bringing -the leaves into the drying-room which is heated by the pipe -<i>g</i>. (Fig. 59.)</p> - -<p>The bone flour remaining in the box <i>d´</i> still contains -much jelly, which is extracted by pressure. This is accomplished -immediately after running off the gelatinous solution -into the evaporating vessel. The liquid which has -drained through the cloth frame previously mentioned, is -drawn off by opening the cock <i>p´</i>, Fig. 62, while the residue -in the box <i>d´</i> is placed in coarse bags and the jelly extracted -by subjecting the bags to strong pressure under an iron -screw-press. Before mixing the extracted fluid with the -solution in the evaporating vessel, it is recommended to -allow it to settle, as it is always more or less turbid. The -residue remaining in the bags is an excellent manure.</p> - -<p>The modern process of preparing bone gelatine, which is<span class="pagenum" id="Page_180">180</span> -now almost in general use is as follows: Clean bones are -selected for the purpose, and the operation commences with -the extraction of the fat by means of benzine, though some -manufacturers prefer carbon disulphide as a solvent, because -it is claimed that by reason of its low boiling-point it -does not injure the gelatine in the same manner as benzine, -and besides it leaves no smell in the degreased bones. It -is advisable to bleach the degreased bones, spread out in -thin layers and kept constantly moist, by exposure to the -action of air and light. The bleached bones are conveyed -to large vats for the purpose of extracting their mineral -constituents by digestion with hydrochloric acid. If the -gelatine is to be used as an article of food, or for medicinal -purposes, only the purest hydrochloric acid obtainable -should be used, while the ordinary article suffices for that -for technical purposes.</p> - -<p>The vats are filled three parts full with bones and the -latter covered with a solution of hydrochloric acid of 10 per -cent. strength. Digestion is carried on until the bones -become soft, flexible and semi-transparent. The acid water -is now drained off, and a supply of fresh water added, and -then discharged. This is repeated until the last water is -entirely free of acid, which is known by adding a few drops -of silver nitrate, the absence of any white precipitate indicating -that the water is entirely free of acid.</p> - -<p>The bones are now bleached in the manner as described -under skin-gelatine, preferably with solution of sulphurous -acid, the process with gaseous sulphurous acid being difficult -to carry out and considerable time is required for the -gas to completely permeate the cartilaginous mass. The -bleached bones are then conveyed to the boiling vats and -the resulting liquors treated in the same manner as described -under skin-gelatine.</p> - -<p>As bone-gelatine solidifies with a larger content of water -than the product from skins, evaporation of the liquors may -be early interrupted and the resulting jelly cut into thin -leaves which are finally dried.</p> - -<p><span class="pagenum" id="Page_181">181</span></p> - - -<h4>COLORED GELATINE.</h4> - -<p>Cakes or leaves not entirely colorless may be utilized for -colored gelatine which is employed for various purposes. -Coloring is effected by simply dissolving and distributing -uniformly a suitable quantity of coloring matter in the -clarified gelatine liquor previous to solidifying; of course -only water-soluble coloring matter should be used.</p> - -<p>Colored gelatines are frequently used by confectioners and -in the household in the preparation of jellies, and the use of -poisonous colors should under all conditions be avoided. -Sufficient attention is not paid to this, because many of the -aniline colors which are now so much used for the purpose -are at least open to suspicion, while others, especially picric -acid, which yields a beautiful yellow color, are decidedly -poisonous.</p> - -<p>The following coloring matters are perfectly harmless and -yield good results in coloring gelatine:</p> - -<p><i>Yellow</i>: Caramel or sugar color. A still more beautiful -yellow is obtained by the use of an aqueous extract of -saffron.</p> - -<p><i>Red</i>: Extract of cochineal.</p> - -<p><i>Blue</i>: Indigo-carmine solution.</p> - -<p><i>Green</i>: Mixture of indigo-carmine and caramel.</p> - -<p><i>Violet</i>: Mixture of extract of cochineal and indigo-carmine.</p> - -<p>While gelatine colored with the above-mentioned coloring -matter does not present such a beautiful appearance as -the product colored with aniline colors, it is entirely harmless -and suitable for culinary purposes.</p> - -<p>Leaves of gelatine colored with aniline colors exhibit -beautiful colors and are used for many technical purposes. -The following colors may be employed:</p> - -<p><i>Yellow</i>: Picric acid soluble in hot water.</p> - -<p><i>Red</i>: Fuchsine or eosine.</p> - -<p><i>Blue</i>: Water-soluble blue.</p> - -<p><i>Green</i>: Iodine green.</p> - -<p><span class="pagenum" id="Page_182">182</span></p> - -<p><i>Violet</i>: Methyl violet.</p> - - -<p class="center"><i>Gelatine for Fining Purposes.</i></p> - -<p>For fining beer, wine, etc., gelatine in leaves or in powder -is brought into commerce. For the preparation of leaves, -gelatine particularly well dried is carefully melted over a -water-bath and then ladled into sheet-metal moulds, and -allowed slowly to solidify.</p> - -<p>The product brought into commerce under the name of -<i>Gelatine Lainée</i> which commands a high price is in many -cases nothing but thoroughly purified bone-glue of a dark -honey-yellow to brown color.</p> - -<p>Fining powder for wine and beer is made by grinding -off-color gelatine cakes and freeing the resulting powder -from coarser pieces by sifting. The powder is white.</p> - -<p><i>Liquid fining gelatine.</i> This preparation consists of gelatine-solution -suitably prepared, and represents a colorless, -or at the utmost slightly opalescent, product just sufficiently -concentrated to remain liquid.</p> - -<p>Skin-liquors can only be used for the preparation of -liquid gelatine, as bone-liquors already gelatinize when they -contain scarcely more than 1 per cent. of glue. The skin -liquors are concentrated so far as to remain liquid at a -temperature of from 60° to 68° F.</p> - -<p>A product answering all demands is obtained as follows: -A good quality of gelatine of a pale color is dissolved in a -sufficient quantity of water, the solution, in case it shows a -slight odor, filtered through animal charcoal, and then -brought into bottles. To prevent putrefaction the liquid -gelatine is sterilized as follows:</p> - -<p>The filled bottles being placed in a boiler filled to a -proper depth with water, the latter is slowly brought to -boiling which is kept up for 15 to 20 minutes. The bottles -are then closed with corks previously boiled in the water.</p> - - -<p class="center"><i>Preparation of Gelatine from Ordinary Glue.</i></p> - -<p>For this purpose ordinary pale-colored glue is allowed to<span class="pagenum" id="Page_183">183</span> -swell up for two days in cold strong vinegar. The vinegar -is then drained off and the glue which is now almost colorless, -is placed upon a sieve and allowed to float in a vessel -filled with water for 10 to 12 hours. It is then placed -upon a linen cloth, stretched in a room heated to at the utmost -68° F., allowed to drain and dry to such an extent -that on heating it to between 158° and 167° F., a thick -clear liquid is obtained. This liquid is carefully poured -upon plates of glass or marble, so as to avoid the formation -of air bubbles and when solidified the leaves are removed -and completely dried in the air. The product thus obtained -being entirely tasteless and almost colorless may be -used in the preparation of jellies, as well as for foils for -pictures, etc.</p> - - -<p class="center"><i>Preparation of Gelatine for Photographic Printing and for -Photographic Purposes in General.</i></p> - -<p>Gelatine suitable for this purpose should be colorless and -free from all salts, since the latter would exert a disturbing -effect upon the chemical processes which take place during -the photographic operation. For the removal of the salts -the gelatine is treated as follows: Colorless gelatine of the -best quality is broken into small pieces and covered with -10 to 12 times the quantity of water, the latter being -changed every 15 to 20 minutes until the last water shows -no trace of lime, which is known by adding to the water -solution of oxalate; the absence of turbidity indicates that -the water is free from lime. The white of an egg is now -mixed with five drops of ammonia and twice the volume of -distilled water and shaken to froth in a bottle. This quantity -suffices for 6 to 8 ozs. of gelatine. The washed gelatine -is next melted in a dish and mixed with the white of egg. -One part of glacial acetic acid mixed with 250 parts of -water is then added drop by drop, stirring constantly until -sensitive litmus paper shows an acid reaction. The liquid -is now rapidly brought to the boiling-point, whilst stirring<span class="pagenum" id="Page_184">184</span> -constantly, and then filtered in a warm place to avoid gelatinization. -The gelatine now contains only the salts of the -white of egg, some ammonium acetate and free acetic acid. -For their removal the solidified gelatine is cut into pieces, -which are placed in water.</p> - - -<p class="center"><i>Gelatine Capsules for Medicinal Purposes.</i></p> - -<p>Considerable use is made of gelatine in medicine. To -disguise the disagreeable taste of some medicines they are -either mixed with gelatine solution or inclosed in gelatine -capsules. To prepare the latter, dissolve 8 parts of gelatine, -2 of sugar, and 1 of gum-arabic in 8 of water in a water-bath, -and dip the pear-shaped ends of iron rods into the -lukewarm solution. To facilitate the detaching of the gelatine -film from the rods, grease the pear-shaped ends with -oil. The capsules are dried by placing them in holes of a -corresponding size in boards. When dry they are filled -with the respective medicine, and closed with a drop of the -same solution.</p> - - -<p class="center"><i>Court Plaster.</i></p> - -<p>Gelatine or isinglass 155 grains, alcohol 13½ fluid -drachms, glycerine 15½ grains. Water, tincture of benzoin, -each a sufficient quantity. Dissolve the gelatine in a sufficient -quantity of hot water to make the solution weigh 4½ -ozs. Spread one-half of this in successive layers by means -of a brush upon taffeta stretched upon a frame so as to present -a level surface, waiting after each application until the -layer is dry. For the first two applications the gelatine -solution should be warmed merely to above its congealing -point, so that when spread out it may rapidly solidify -and at the same time adhere to, but not pass through the -fabric. Mix the second half of the gelatine solution with -the alcohol and glycerine, and apply it in the same manner. -Then reverse the taffeta, coat it on the back with the tincture -of benzoin and allow it to become perfectly dry. The -tincture of benzoin applied to the reverse side leaves a thin<span class="pagenum" id="Page_185">185</span> -layer of resin which in a measure renders the plaster water-proof; -it is, however, advisable to repeat this application -once or twice. The addition of glycerine to the last portion -of the gelatine solution prevents the plaster from breaking, -and preserves its flexibility for a long time. When the -plaster is dry it is cut in pieces of suitable length and preserved -in well-closed vessels.</p> - - -<p class="center"><i>Gelatine Foils.</i></p> - -<p>Large quantities of gelatine foils, which are leaves of gelatine -about as thick as a sheet of paper, are produced in -England and France where their manufacture forms a special -branch of industry. They are either simply colored or -printed with neat designs in gold or silver.</p> - -<p>The fabrication is quite simple. Cover pure gelatine -with water, and after swelling up, pour off the water and -dissolve the jelly over a water-bath. After allowing the -solution to cool somewhat, add the coloring matter previously -dissolved in water.</p> - -<p>In place of pure gelatine, a solution of ordinary bone-glue -may be used. In order to clarify it add O.14 oz. of oxalic -acid dissolved in water to every 5.5 lbs. of glue. To make -the foils more flexible add also one-half pint of spirit of -wine and O.28 oz. of rock candy or a small quantity of glycerine.</p> - -<p>Aniline colors soluble in water are best adapted for coloring -the foils; for <em>red</em>, fuchsine, eosine or ponceau, for <em>blue</em>, -<em>blue de Parme</em>, for <em>green</em>, aldehyde green, for <em>yellow</em>, picric -acid, and for the various shades, mixtures of the above -colors.</p> - -<p>A durable blue is also produced by indigo solution, yellow, -by decoction of saffron, green, by mixing blue and -yellow, red, by a solution of carmine in spirit of sal ammoniac, -and violet, by mixing blue and carmine.</p> - -<p>The gelatine solutions are poured upon ground-glass -plates, previously polished with elutriated rouge, and rubbed<span class="pagenum" id="Page_186">186</span> -with Spanish chalk. The foils are so smooth upon the -glass side that when dry they can be detached without -much difficulty. If both sides are required to be smooth, -the foils are dried between two glass plates. In many respects -their manufacture resembles that of “Gelatine -Veneers.”</p> - -<p>Gelatine foils are used for printing sacred images, visiting -cards, labels, in the manufacture of fancy articles, artificial -flowers, etc.</p> - -<p>For the manufacture of artificial flowers very soft and -flexible sheets are made by adding ½ part of glycerine to -1 part of gelatine and mixing intimately in dissolving -the gelatine.</p> - -<p>Such gelatine sheets brushed over in addition with Peruvian -balsam can also be advantageously used for tying up -wounds instead of gutta-percha cloth which tears easily and -rots soon. They form an air-tight bandage which clings -closely to the parts of the body, and beside the glycerine -contained in them exerts a beneficial cooling effect and acts -as an antiseptic.</p> - - -<p class="center"><i>Gelatine Veneers.</i></p> - -<p>Franchi, as far back as 1814, prepared artificial ivory by -mixing gelatine solution with earthy substances. This -idea has been again taken up in modern times for the -manufacture of veneers imitating not only ivory, but also -avanturin, lapis lazuli, malachite, mother-of-pearl, and -tortoise shell. These imitations are much liked by manufacturers -of fancy articles, workers in leather, cabinet-makers, -etc. They are prepared as follows:—</p> - -<p>The process may be divided into five principal operations: -1. Preparation of the glass and marble plates; 2. -Preparation of the glue solutions; 3. Pouring the colored -solutions upon the plates; 4. Transferring the layer of glue -to the layer of gelatine; and 5. Drying the veneers and detaching -them from the plates.</p> - -<p><span class="pagenum" id="Page_187">187</span></p> - -<p>1. <i>Preparation of the plates.</i> Both marble and glass plates -are used for imitations of marble, but glass plates only for -imitations of mother-of-pearl. The glass plates must be -ground, but need not exceed O.11 to O.15 in. in thickness, -and only require careful washing and drying for imitations -of mother-of-pearl. For imitations of marble they should -be rubbed with an oiled linen rag. Other glass plates, -after being washed and polished with elutriated rouge -and water, are wiped with a soft rag to remove any particle -of the polishing powder. The polished surface is then -gently rubbed with a rag dipped in pure Spanish chalk, -and the excess of chalk carefully dusted off.</p> - -<p>2. <i>Preparation of the glue solutions.</i> For one dozen plates, -each 10¾ square feet, soak 2 lbs. of good, colorless glue in -water for 24 hours, pour off the water and melt the glue in -a water-bath and stir in 3½ ozs. of glycerine. For imitating -marbles of two colors, compound 20 to 24 fluidounces of -this glue solution with the quantities of thoroughly ground -mineral colors given below; the rest of the glue solution is -mixed with 6.34 ozs. of zinc white ground very fine. For -imitating marble of three colors mix 14 fluidounces of the -glue solution with one of the coloring matters and 14 -fluidounces with the other coloring matter, and the remainder -with zinc white. For imitating marble with four -colors, take 10 fluidounces of the glue solution to each of -the three coloring matters, and mix the rest with 4½ ozs. of -zinc white.</p> - -<p>The proportions by weight of the mixtures for 10 different -varieties of imitations of marble and enamel are as follows:—</p> - -<p><i>a.</i> Mix 20 fluidounces of the glue solution with 1¾ ozs. of -rouge and 2½ ozs. of zinc white, and the rest of the glue -solution with 6⅓ ozs. of zinc white.</p> - -<p><i>b.</i> Mix 20 fluidounces of the glue solution with 1¾ ozs. -of rouge, and the rest of the glue solution with 5¼ ozs. of -zinc white.</p> - -<p><span class="pagenum" id="Page_188">188</span></p> - -<p><i>c.</i> Mix 14 fluidounces of the glue solution with 1¼ ozs. -of zinc white and 1 oz. of rouge, 14 fluidounces of the -glue solution with 1 oz. of yellow ochre, and the rest with -5¼ ozs. of zinc white.</p> - -<p><i>d.</i> Mix 14 fluidounces of the glue solution with 1 oz. of -rouge, 14 fluidounces of the glue solution with ¾ oz. of -sepia, and the rest with 5¼ ozs. of zinc white.</p> - -<p><i>e.</i> Compound 20⅓ fluidounces of the glue solution with -1 oz. of quite concentrated and filtered solution of aniline -black, and the rest with 6⅓ ozs. of zinc white.</p> - -<p><i>f.</i> Mix 10 ozs. of the glue solution with 0.8 oz. of rouge, -10 fluidounces of the glue solution with 0.8 oz. of yellow -ochre, 10 fluidounces of the glue solution with 0.8 oz. of -sepia, and the rest with 4¼ ozs. of zinc white.</p> - -<p><i>g.</i> Mix 20.3 fluidounces of the glue solution with 1.41 -ozs. of lampblack. For gray add sufficient zinc white to -produce the desired shade. The rest of the glue solution is -mixed with 6⅓ ozs. of zinc white.</p> - -<p><i>h.</i> Mix 10 fluidounces of the glue solution with 0.8 oz. of -umber, 10 fluidounces of the glue solution with 0.8 oz. of -bole, 10 fluidounces of the glue solution with 0.8 oz. of -ochre, and the rest with 4½ ozs. of zinc white.</p> - -<p><i>i.</i> <i>For enamels</i> mix 20.3 fluidounces of the glue solution -with 1 oz. of ultramarine, and the rest with 6⅓ ozs. of zinc -white.</p> - -<p><i>k.</i> Mix 20.3 fluidounces of the glue solution with 1.41 ozs. -of chrome green, and the rest with 6⅓ ozs. of zinc white.</p> - -<p>For imitating mother-of-pearl veneers, 0.42 oz. of silver -bronze, which need not be genuine, is ground with a little -glue solution or water and intimately mixed with the above -solution of glue. The bronze powder must not be in a dry -state when stirred into the glue, as lumps would be formed -and the veneers become spotted. In place of bronze, essence -of fish scales, which is of course far more costly, can be -used.<a id="FNanchor_2_2" href="#Footnote_2_2" class="fnanchor">2</a> The glue solution thus prepared is then -compounded with different aniline colors according to the tint -desired.</p> - -<div class="footnote"> - -<p><a id="Footnote_2_2" href="#FNanchor_2_2" class="label">2</a> -This preparation is also known by the name <i lang="fr">Essence d’Orient</i>. The material -for its production is furnished by a small white fish very common in the -rivers of continental Europe. It accompanies the scales of this fish, and is -detached when the scales are triturated for a considerable time and thrown into -a vessel of water. To collect the essence the water is poured off upon a fine -hair sieve, which retains the scales and allows the water and the product -sought to pass through. The latter sinks to the bottom, and is obtained pure -by decanting the water. A little ammonia is added to prevent decomposition.</p> -</div> -<p><span class="pagenum" id="Page_189">189</span></p> - -<p><i>a.</i> For yellowish veneers no coloring matter is required, -or the desired shade is obtained by an addition of some -solution of picric acid.</p> - -<p><i>b.</i> For colorless veneers or those of slightly reddish tints -a smaller or greater number of drops of a concentrated solution -of fuchsine are added in order to counteract the yellowish -color of the glue solution. For these imitations of -mother-of-pearl veneers, concentrated solution of gelatine -compound with 15 per cent. of glycerine can be employed, -especially when essence of fish scales is used.</p> - -<p><i>c.</i> For <i>blue</i>, the glue solution is compounded with <i>bleu de -Lyons</i>, care being had not to use too much, as otherwise the -imitation becomes indistinct. The proper degree of coloring -is tested by allowing a few drops of the colored glue -solution to fall upon a glass plate.</p> - -<p><i>d.</i> For <i>red</i>, solution of fuchsine or carmine is used, the -latter being obtained by dissolving commercial carmine -powder in alcohol.</p> - -<p><i>e.</i> <i>Orange colors</i> are produced by an addition of solution -of <i>chrysaniline</i> generally sold under the name of Victoria -orange, and <i>violet</i> by adding aniline violet. For these, as -well as for the solution colored with fuchsine, the plates -must <i>not</i> be rubbed with oil, as even the smallest trace of -the latter discolors these colors in drying, or at least the -veneers will show spots without color.</p> - -<p>3. <i>Pouring the colored solutions of glue upon the plates.</i> -For imitations of marble and enamel, the glass plates, after -rubbing with oil, are placed, rubbed surface up, in a per<span class="pagenum" id="Page_190">190</span>fectly -level position. The proper portion of the white -ground-mass, after becoming somewhat thickish, is then -poured upon the plates, and the gaps left free in pouring -filled in and smoothed with a knife-shaped tool of horn or -bone. Upon this white ground the respective colored glue -solutions are then poured in a zigzag form, and in conformity -with the desired design, drawn through the ground-mass -with a glass rod. If several differently colored glue -solutions are to be applied, as given, for instance, under 2<i>f</i>, -they should be poured in quick succession, so that the succeeding -color runs into the preceding, and a white strip -or spot remains between each color. The whole is then intermingled -by the glass rod, according to the design. If -the latter is to have sharply defined lines and spots, the respective -colored solution of glue is used somewhat thicker, -but if, on the other hand, the design is to be somewhat -blended, the glue solutions are used somewhat warmer, and -consequently more thinly fluid. After solidification of the -glue solutions the plates are placed in a cool room for two -or three hours.</p> - -<p>Imitations of malachite are prepared in a similar manner. -Four glue solutions of different shades of green from the -darkest to the lightest tint are prepared and poured upon a -slightly greenish ground, so as to imitate the characteristic -curves and veins of malachite, which are then further -traced with a comb with teeth standing at unequal distances -from each other.</p> - -<p>The glass plates set aside to be used for imitation of -mother-of-pearl are now taken in hand. The solutions of -glue are kept warm over a water bath and thoroughly -stirred every time before pouring them upon the plates. -The formation of a film on the surface of the glue solution -must be strictly avoided.</p> - -<p>For pouring out the solutions it is best to use a porcelain -vessel provided with a spout and handle, and having a -capacity of about 6¾ fluidounces. The portion of glue<span class="pagenum" id="Page_191">191</span> -solution required for each plate (1¾ flu. oz.) is then measured -into one of the porcelain vessels, and, after standing a -short time, poured upon the plate and uniformly distributed. -The production of a mother-of-pearl design requires some -skill and practice. A comb with teeth set ½ inch apart is -used. It is held in a somewhat oblique position, the teeth -are gently pressed upon the glass plate, and, with frequent -turnings of the comb at a right angle, cycloidal motions -executed. The operation is carried on from the front to the -back edge of the glass plate, and when the glue begins to -thicken on the edges, continued at the softer places until -the desired design is produced, care being had not to touch -places which have already acquired a certain degree of -solidity, as this would mar the pattern. After treating all -the plates in this manner, they are set aside in a cool room -for two or three hours.</p> - -<p>4. <i>Transferring the layer of glue to a layer of gelatine.</i> For -each dozen of veneers soak 2½ ozs. of gelatine, and then -melt them in a water-bath, and after adding glycerine -equal to 10 per cent. of the dry gelatine, let the mixture -settle.</p> - -<p>The glass plates treated with rouge and Spanish chalk are -now placed in a perfectly level position, and after pouring -5½ fl. ozs. of gelatine solution upon each of them, the gaps -left in pouring are filled in and smoothed with the glass -rod. The front edge of a plate covered with a colored layer -of glue is now, glue side down, placed upon the front edge -of a gelatine plate, while the back edge of the former is -gradually lowered until the glue plate lies firmly upon the -gelatine plate.</p> - -<p>It may here be remarked that the gelatine solution must -only be allowed to cool off sufficiently to prevent the melting -of the glue plate on touching it. If it is cooler the -veneers will have blisters. It must further be looked to -that, before placing the first plate upon the gelatine plate, -no gelatine escapes, and that any excess only runs off after<span class="pagenum" id="Page_192">192</span> -the back edge of the glue plate touches that of the gelatine -plate.</p> - -<p>The plates are now allowed to rest quietly until the gelatine -is congealed, when they are removed to a cool place -where they remain five or six hours.</p> - -<p>Imitations of mother-of-pearl are treated in the same -manner with the exception that the gelatine solution is -colored with the same coloring matter as the glue solution. -For colorless or yellowish veneers the gelatine solution is -not colored.</p> - -<p>After six hours the first glass plate is detached from the -layer of glue by loosening the latter around the edges with -a knife blade, and the plate gradually lifted off commencing -at one corner. With some care and skill, this operation is -readily accomplished without detaching the gelatine mass.</p> - -<p>5. <i>Drying and detaching the veneers.</i> The veneers with -the gelatine layer still adhering to the glass plate are now -dried. This is done in a heated room in which the veneers -are arranged upon frames so that they stand almost perpendicular. -The hot air for heating the room enters near -the ceiling while the moist air is drawn away near the -floor. The temperature of the lower zone where the fresh -plates are placed should not exceed 68° F. The plates are -moved up higher every day until, on the third or fourth -day, they have become entirely dry. Before removing the -veneers from the drying-room they should be tested in -regard to their dryness. They are sufficiently dry, when, -on pressing the finger nail upon the glue, no impression is -made.</p> - -<p>After removal from the drying-room the plates are allowed -to cool off for at least two hours before detaching the -veneers. The operation begins by detaching the gelatine -layer on the edges with a very thin knife blade. The -operator then takes hold of one corner of the veneer and -draws it gradually and carefully from the glass plate. -After trimming the edges the veneers are ready for use.</p> - -<p><span class="pagenum" id="Page_193">193</span></p> - -<p>If the veneers are required to resist the action of water, -mix with the solution of gelatine compounded with glycerine -⅓ fl. oz. of a solution of 5 parts of chrome-alum in 100 -of water to every plate, and immerse the veneers for a short -time after they have been detached from the first plate, in -a similar solution of chrome-alum.</p> - -<p>Veneers prepared by these methods can be used for various -purposes in architecture and in the manufacture of -furniture. Tennessee and other marbles have been so -closely imitated, that when used for table plates, etc., the -fact of their being imitations could only be detected by the -closest scrutiny. The veneers are also much used for fancy -and inlaid work, for coating columns, etc. To prevent -their blistering and coming off, it is recommended to add -one-quarter of its weight of glycerine to the glue with which -they are to be attached to the articles.</p> - - -<p class="center"><i>Formo-Gelatine.</i></p> - -<p>This product is used as a dressing in surgery, and, according -to Samuel Rideal, is obtained as follows: Gelatine -in aqueous solution is precipitated by formaldehyde H.COH, -or CH<sub>2</sub>O, as a substance which on drying is a white powder, -neutral, inodorous, and insoluble in water and dilute chemical -agents. In commerce formaldehyde is met with in -aqueous solution as “formalin” containing 40 per cent. of -formaldehyde. If 1 Cc. of formalin be added to 200 Cc. of -a 5 per cent. gelatine solution, the latter is changed into a -gelatinous mass, not melted by heat nor reduced by water. -If a smaller quantity of the formalin is added (1 in 1000; -the jelly is said to be meltable, but with a higher tenacity) -when dried it becomes insoluble in warm water. Formalin -in less proportion, though it does not prevent the dried -gelatine from dissolving in warm water, is said to improve -the “body” of the jelly and its keeping qualities, and also -the tenacity of the glue. The results of investigation show -that with up to 1 per cent. of formalin the solidity of the<span class="pagenum" id="Page_194">194</span> -jelly increases; above that it declines. Up to 0.02 per cent. -(1 in 5,000) it redissolves in water after drying. Even with -this small proportion the firmness of the jelly is sensibly -increased. The English patent, 4,696, 1894, claims the addition -of formalin during the manufacture of size and glue -in such proportion that the product shall liquefy in warm -water.</p> - -<p>In examining commercial sheet gelatines for printers’ -and photographic use, they were often found to contain -small quantities of formalin. It seems to improve the quality, -a very small percentage increasing the tenacity, flexibility -and keeping qualities, while not affecting the transparency -or rendering the material acid. When applied to -articles that may be used as food, a strength of 1 in 50,000 -in the final prepared product is not injurious to health, but -should not be exceeded. (Rideal and Foulerton, <cite>Public -Health</cite>, May, 1899, p. 568.)</p> - -<p>Zimmermann applies dilute formaldehyde mixed with -glycerine, vaseline, oil or yolks of eggs, with or without -flour, to the surface of photographic films which are claimed -to be thereby rendered more pliable and not so hard as -when the formalin is applied by itself.</p> - -<p>It will be seen that formaldehyde in more than traces -renders gelatine insoluble; the product, moreover, is almost -unaffected by water, is more or less hard and elastic and, -owing to the antiseptic properties of the formaldehyde is -nearly imperishable.</p> - - -<p class="center"><i>Use of Gelatine in Bacteriology.</i></p> - -<p>Gelatine fit for this purpose must be clear and bright, -fairly neutral and of high gelatinizing power. For bacteriological -purposes a 10 to 20 per cent. solution of gelatine -in sheets or strips is made with meat broth, and this nutrient -jelly, which is obtained by clarification with albumen perfectly -clear and bright, forms a most useful medium for the -cultivation of micro-organisms.</p> - -<p><span class="pagenum" id="Page_195">195</span></p> - - -<p class="center"><i>Artificial Silk from Gelatine.</i></p> - -<p>For the production of textile threads, Millar utilizes the -property of gelatine solution mixed with potassium dichromate, -becoming insoluble on exposure to light. For this -purpose a clear solution of gelatine is mixed with solution -of potassium dichromate in the proportion of 100 parts of -gelatine to 2 or 2½ parts of potassium dichromate. The -fluid should be of such a consistency as to allow of its being -drawn out into fine threads which on exposure to light -become insoluble. Silk woven from such threads is equal -in appearance to the genuine article but of course is not so -strong. It is affected by moisture, becoming limp, but regains -its normal strength when dry.<a id="FNanchor_3_3" href="#Footnote_3_3" class="fnanchor">3</a></p> - -<div class="footnote"> - -<p><a id="Footnote_3_3" href="#FNanchor_3_3" class="label">3</a> -For further information on this interesting subject, the reader is referred -to “Cellulose and Cellulose Products.” By Dr. Joseph Bersch. Henry -Carey Baird & Co., Philadelphia, 1904.</p> -</div> -<hr class="chap" /> - -<p><span class="pagenum" id="Page_196">196</span></p> - - - - -<div class="chapter"></div> -<h3><a name="CHAPTER_X" id="CHAPTER_X">CHAPTER X.</a><br /> - -<small>ISINGLASS AND ITS SUBSTITUTES.</small></h3> - - -<p>Isinglass is obtained from the air-bladder or sound, as it -is sometimes termed, of different kinds of fishes, especially -of the sturgeon, species <i>Acipenser</i>. It is used for culinary -purposes, fining beer and other liquids, for making court-plaster -and stiffening silk, though a good quality of gelatine -is practically equal to it for these purposes. A good quality -of isinglass should be pure white, semi-transparent, dry and -horny in texture, and free from odor. It should dissolve -in water of 95° to 122° F., without leaving any residue, -and, on cooling, should yield an almost colorless jelly. -From gelatine imitations it is distinguished by soaking it -in warm water and examining under the microscope, when -true isinglass will show a net-work of long, curling fibres, -while gelatine will be simply hyaline. Isinglass is often -imitated with the intestinal membranes of the calf and of -the sheep. This spurious article may be readily recognized -because it does not exhibit, like isinglass, a sort of shining -appearance when held before the eye and daylight, and -because, although inodorous, it has a saltish flavor. If it -be torn asunder it will be observed that it may be rent in -all directions, while true isinglass cannot be divided otherwise -than in the direction of its fibres. If a piece of artificial -isinglass be macerated in water it swells, but instead -of retaining its shape as is the case with the genuine -article, it becomes divided into several pieces, forming a -sort of curdy precipitate; and if treated with boiling water, -about one-third of its weight is left in an insoluble state, -and the liquor does not form a good jelly. Isinglass is -frequently adulterated with gelatine, which is inserted<span class="pagenum" id="Page_197">197</span> -between the leaves and rolled up with it. The best indication -of this adulteration is the amount of ash; isinglass -yields only 0.9 per cent., while gelatine yields 4 per cent., -and adulterated isinglass 1.5 per cent. or more.</p> - -<p>1. <i>Russian isinglass.</i> Russia produces the best and most -isinglass. It is chiefly obtained from several varieties of -sturgeon, species <i>Acipenser</i>, which inhabit the Caspian and -Black Seas, and their tributary rivers. The <i>Acipenser -Gueldenstaedtii</i>, Br. yields the finest, best and whitest isinglass. -It is known by the name of <i>Patriarch</i>, and consists -of small horseshoe-shaped pieces rolled tightly together. -It is quite scarce and expensive. When the bladder is -merely dried in sheets, it constitutes <i>leaf isinglass</i>. When -several bladders are put together and folded before they are -completely dry, they form <i>book isinglass</i>. Each bladder -may also be rolled up and folded around a few pegs in the -form of a horseshoe, heart, or lyre, in which shape it is -dried. The latter is the <i>staple isinglass</i>, which, according -to its dimensions, is again divided into <i>long and short staple</i>.</p> - -<p>Long staple isinglass of fine quality is produced in the -Oural. It is imported in loose leaves, and at times it is -twisted like ropes, this kind being preferred, as it is inferior -in quality only to Patriarch.</p> - -<p><i>Siberian</i> purse isinglass is of moderately good quality and -is in general demand. A small kind of strings in a necklace -form is sometimes imported.</p> - -<p>A very good sort of Russian isinglass comes into commerce -in leaves and books, and is known by the name of -<i>Samovey</i> leaf. It is obtained, according to the statements of -Russian merchants, from the common sheath-fish (<i>Siluris -Glanis</i>). The pieces are as large as a hand, of the thickness -of pasteboard, very solid, not very flexible and of a -white-yellowish color. It is inferior in quality to Astrakhan -isinglass, which is one of the best kinds.</p> - -<p>In <i>Russia</i> the isinglass is generally prepared by boys -under the supervision of elder experts. The swimming<span class="pagenum" id="Page_198">198</span> -bladder is first placed in water and left there for some days -with frequent changes of the water and removal of all fatty -and bloody particles. The warmer the water the more -rapidly the operation is completed. The bladders are -finally removed and cut longitudinally into sheets which -are exposed to the sun and air, being laid out to dry, with -the outer face turned down, upon boards of linden or bass -wood. The inner face is pure isinglass, which, when well -dried, can with care be removed from the external lamellæ. -The finer sheets thus obtained are placed between cloths -to protect them from the flies, and are then subjected to a -heavy pressure so as to flatten them out and render them -uniform. After this they are assorted and tied up in packages. -The packages composed of the isinglass of the large -sturgeon usually contain from ten to fifteen sheets and -weigh a pound and a quarter; those of the other contain -twenty-five sheets weighing a pound. Eighty of these -packages are usually sewed up in a cloth bag, or sometimes -inclosed in sheet lead.</p> - -<p>The outer lamellæ of the air-bladder, after the isinglass -has been removed, also contain a considerable quantity of -glue which, when softened in water, is scraped off with a -knife and moulded into little tablets of about the size of a -silver dollar, and then dried.</p> - -<p>2. <i>North American or New York Isinglass.</i> It is in thin -strips several feet long but ½ to 1½ inch wide. It is less -soluble than Russian isinglass, and yields frequently a dark-colored -solution. It is prepared, according to Dr. J. V. C. -Smith’s statements, from the air-bladder of the common -hake (<i>Gadus merluccius</i>), which is macerated in water for a -short time, cut open and subjected to pressure between iron -rollers, by which it is elongated to the extent of half a yard -or more. It is then carefully dried, packed and sent to -market. The air-bladder of the common cod (<i>Gadus -morrhua</i>) is prepared in a similar manner, but yields a -poorer kind of isinglass.</p> - -<p><span class="pagenum" id="Page_199">199</span></p> - -<p>3. <i>East India Isinglass.</i> It would seem that for a long -time this has been exported from <i>Calcutta</i> to <i>China</i>, but has -only lately attracted the attention of European dealers. It -is prepared from the air-bladder of the <i>Polynemus plebejus</i>, -and comes into commerce either in the form of leaves or -purses which seem to consist of the unopened air-bladder. -East Indian isinglass has a disagreeable fish odor, due very -likely to careless preparation, which makes its use impossible -for many purposes, and, of course, depreciates its commercial -value. The oval-oblong purses are about nine -inches long, three and a half inches wide, weigh about 7 -ozs. and have a dark-yellow color. East India leaf isinglass, -<i>i. e.</i>, the opened and dried air-bladder, consists of -yellowish-colored leaves eight to nine inches long, six to -seven inches wide, and about three-tenths of an inch thick. -The leaves are sometimes rolled out into long ribbons about -one-tenth of an inch thick, the surface of which is covered -in places with a thin film of lime.</p> - -<p>What is known as picked East India isinglass is brought -into commerce in small shreds about two to three inches -long, and tapering at the extremities.</p> - -<p>A variety of isinglass very white and pure and scarcely -inferior to Samovey leaf is brought from Manila. The -fish which yields it is caught on the coast of the Philippine -Islands, especially at Luzon.</p> - -<p>4. <i>Hudson Bay Isinglass.</i> It is brought into commerce -in the purse form. Some specimens measure twelve inches -in length and three and a half inches in diameter, and -weigh one and a half ounces. It is of light-yellow color, -nearly transparent, without odor or taste. The inner lining -of the sac, which can be readily stripped off, is insoluble -in water, while the remaining portion dissolves to a slightly -colored jelly. We have been unable to ascertain from what -species of fish this isinglass is procured.</p> - -<p>5. <i>Brazilian Isinglass.</i> This is imported from <i>Para</i> and -<i>Maranham</i>, and is also called <i>Cayenne</i> isinglass. For a long<span class="pagenum" id="Page_200">200</span> -time there existed a doubt from what species of fish this -isinglass was procured, but it is now settled that it is prepared -from the air-bladder of <i>Silurus Parkerii</i>, a fish which -is frequently found in the muddy waters of the rivers in -the province of Grao Para, where these waters mingle with -the sea.</p> - -<p><i>Brazilian</i> isinglass comes in the form of pipe, lump and -honeycomb. On account of its dark color it is not in much -demand for ordinary use, but is frequently employed in -England for clarifying glue. When digested in water it -leaves much insoluble substance behind, being in this -respect also inferior to Russian isinglass.</p> - -<p>6. <i>German Isinglass.</i> Under this name we may mention -the mucous membrane of the sturgeon (<i>Acipenser sturio</i>), -prepared in Hamburg. When boiled with water it leaves -16 per cent. of insoluble substance.</p> - -<p>It is said that an excellent isinglass can be made from -the scales of shad and herring, which are first freed from -their silvery coating. This may furnish a useful hint to -persons who are near some of the great fishery establishments -of the country, at <i>Gloucester, N. J.</i>, and <i>Alexandria, -Va.</i>, for instance, where thousands of shad are scaled and -salted every year.</p> - -<p>To give inferior qualities of isinglass a better appearance -and make them more salable, they are frequently bleached -with sulphurous acid.</p> - -<p><i>Ichthyocolle Française.</i> Under this name, Rohan has -introduced a substitute for isinglass. The material used -for its manufacture is blood fibrin, which, after washing in -running water, is thoroughly kneaded and, after draining, -digested at 59° F. with dilute sulphuric acid of 8° to 10° -Bé. for eight days, after which the mass is freed from acid -by washing in running water.</p> - -<p>The fibrin freed from acid becomes transparent and gelatinous -by treating with weak soda lye of 3° to 4° Bé. at -59° F., whereby it swells up and increases hourly in vol<span class="pagenum" id="Page_201">201</span>ume. -After twenty-four hours it is taken from the soda -lye, and after removing the free soda by washing, heated to -212° F, in a water-bath. The fibrin dissolves and becomes -so thinly fluid that it can be filtered. 75 to 80 per cent. of -the water is then evaporated, and the fibrin thus prepared -can be used as a substitute for isinglass for fining purposes. -Ichthyocolla swells more quickly in cold water than isinglass; -15 to 20 per cent. divided in water forms a thickly -fluid substance, which on heating dissolves to a perfectly -clear fluid. For fining beer with ichthyocolla add 2 to 10 -per cent. of pure tannin, which does not injure its power of -dissolving.</p> - -<p><i>Isinglassine.</i> Under this name is known an isinglass -substitute prepared from the gelatinous material from -calves’ feet and other sources. The material is reduced by -machinery to a pliable homogeneous mass, rolled out into -sheets, dried, pressed and shredded.</p> - -<p><i>Chinese isinglass</i> is identical with the <i>Japanese Agar-Agar</i>, -and is obtained by cleansing and boiling certain species of -algae found in Chinese and Japanese waters. This isinglass, -or gelatine, possesses the following properties:</p> - -<p>Placed in cold water it softens without dissolving like -gelatine, and forms a structureless tubular mass which is -not sticky. By boiling, it dissolves more readily than isinglass, -but with greater difficulty than gelatine. A 1 to 2 -per cent. solution is easily filtered through paper or linen, -and when cold forms a solid jelly clear as water and without -taste or odor. Jelly prepared with one-half per cent. of -Chinese gelatine is more solid than one prepared with 4 per -cent. of French white gelatine, retains its consistency longer, -and will stand a temperature of 86° to 122° F. before becoming -liquid. Used for jellies, or mixed with other foods, -it does not impart to them a glue taste never wanting in -bone gelatine. When decomposed by long standing, it does -not acquire a disagreeable odor, while decomposed isinglass -or gelatine exhales a putrid smell.</p> - -<p><span class="pagenum" id="Page_202">202</span></p> - -<p>Agar-Agar contains, according to analyses: Cellulose, -starch, gum, dextrine, vegetable mucus, vegetable wax, -resin, chlorophyll, albumen, a peculiar acid, and several -mineral substances.</p> - -<p><i>Irish moss</i> (<i>Chondrus crispus</i>) which grows on rocks of the -American and European shores of the Atlantic Ocean, -yields a jelly which has been employed as a substitute for -isinglass, as a size, for thickening colors in calico printing, -and in stiffening silk. In a fresh or softened state the plant -is cartilaginous, of a brownish or purple, or frequently yellow -or green color. After washing in water and drying in -the sun it turns whitish or yellowish, and becomes somewhat -translucent and of a horny appearance. It has a -slight seaweed-like odor and a mucilaginous, somewhat -saline taste. One part of it boiled with 20 parts of water -gelatinizes on cooling.</p> - - -<p><i>Fish Glue.</i></p> - -<p>This product, which is prepared in many localities from -fishes, must not be confounded with isinglass, though the -purer varieties may serve as substitutes for the latter or for -gelatine.</p> - -<p>Jennings gives the following process for the preparation -of fish glue. The fishes are treated with dilute sulphuric -acid until the skin can be detached. The acid water is -then drained off and replaced by milk of lime to neutralize -adhering sulphuric acid as well as to saponify the fat. The -milk of lime is several times drained off and renewed, the -mass thoroughly washed, cut up in a hollander and treated -cold with solution of sodium hyposulphite, common salt -and alum. After a few days the liquor is drawn off and -replaced by a mixture of alum solution, dilute sulphuric -acid and nitric acid in which the mass is allowed to remain -for a few days. Fishes with dark skins are treated with a -mixture of hydrochloric and sulphuric acids. After washing, -the skin is removed and the fibres which have become<span class="pagenum" id="Page_203">203</span> -detached from the bones are separated by digestion in -dilute solution of mercuric chloride and alum. Adhering -fatty parts are removed with warm milk of lime, the lime -is neutralized with hydrochloric acid, and the mass boiled -with water for the formation of glue. The resulting glue-liquor -is clarified with sulphurous acid and alum, and -when all the impurities have subsided, compounded with -acid sodium carbonate till all the acid is neutralized. The -finished solution is concentrated so that it gelatinizes on -cooling and can be cut in cakes which are dried in the -usual manner.</p> - -<p>Fish scales, especially those of carps, are treated in a -similar manner. The bone-earth is extracted with hydrochloric -acid, the extracted material thoroughly washed, and -then boiled in soft water till it can be readily stirred. The -liquor is drawn off from the horny sediment, clarified with -alum, evaporated, and after all the impurities have subsided, -poured into moulds and treated like ordinary glue.</p> - -<p>Considerable quantities of fish glue are produced on the -Norwegian coast from waste obtained in the preparation of -codfish. The fish when caught are cut open and the air-bladders -removed, which are dried and brought into commerce -as isinglass. The head is then cut off and the bones -detached in one piece. The flesh is dried in the air, and -forms the codfish of commerce. The heads and bones are -first treated with hydrochloric acid or directly boiled under -slight pressure in water, and the resulting liquor concentrated -so that it will gelatinize.</p> - -<p>A substitute for isinglass, also for gelatine and glue, is -prepared by C. A. Sahlströhm, of Stockholm, according to -his patent, from fish and fish waste by treatment with -bleaching powder, potassium permanganate, and nitrous -and sulphurous gases.</p> - -<p>For this purpose the fishes, or portions of fishes, are first -well washed in fresh water and then left for from three to -four hours in a solution of bleaching powder (in the pro<span class="pagenum" id="Page_204">204</span>portion -of 2 lbs. of bleaching powder to 300 quarts of water). -After washing they are treated for about 30 minutes with a -solution of potassium permanganate (in the proportion of -1¾ ozs. of potassium permanganate to 250 or 300 quarts of -water), and then exposed to the action of the nitrous gas, -produced by heating 10 to 15 ozs. of nitric acid for every -88 lbs. of raw material. This gas may be first absorbed by -water, as in the manufacture of sugar, or sulphur dioxide -may be used instead of nitrous gas. The former would be -obtained by burning about 7 ozs. of sulphur for every 88 -lbs. of raw material.</p> - -<p>The material, after this treatment, is washed. Those portions -intended for the production of isinglass substitute are -freed from their outer skins and dried and pressed at a -gentle heat. The portions destined to produce gelatine or -glue are, on the contrary, exposed to a temperature of from -104° to 122° F. for from ten to twelve hours, by which the -material is mainly dissolved. The mass is then forced -through a strainer or sieve, and the liquor allowed to gelatinize -by standing for some hours. The jelly is finally -dried, as is usual in the manufacture of glue or gelatine.</p> - -<p><i>Whale glue</i> is, according to Culmann, obtained in the -Russian island Jeretike from the liquor remaining in the -boilers after the extraction of the oil by means of superheated -steam. By reason of the raw and moist atmosphere -which prevails in that locality, even in summer, drying the -glue is not practicable, and for this reason it is brought -into commerce in the form of a compact jelly mixed with a -preservative and packed in tin boxes. The commercial -article contains 41.65 per cent. water. It is liquefied by -placing the can in boiling water, and melts at 176° F. As -shown by mechanical tests, it possesses great tenacity, and -two pieces of wood glued together lengthwise cannot be -separated at the joint but break alongside of it.</p> - -<hr class="chap" /> - -<p><span class="pagenum" id="Page_205">205</span></p> - - - - -<div class="chapter"></div> -<h3><a name="CHAPTER_XI" id="CHAPTER_XI">CHAPTER XI.</a><br /> - -<small>TESTING GLUE AND GELATINE.</small></h3> - - -<p>It is of importance that the manufacturer as well as the -dealer should know how to test the quality of a glue. This -may be done by chemical means and in a mechanical way.</p> - -<p><i>Determination of moisture.</i> For this purpose a weighed -quantity of the sample, finely powdered, is for fourteen -hours exposed to a temperature of 217° to 230° F. It is -then cooled under the dessicator and reweighed. The content -of moisture is then calculated from the loss in weight.</p> - -<p><i>Determination of ash.</i> The origin of a sample of glue -may be traced by examining the ash for phosphates of lime -and magnesia, bone-glue containing both, while skin-glue -is free from phosphates. Reduce a portion of the sample -to a fine powder, and weigh it in a tared constant crucible. -Heat slowly over a Bunsen flame until carbonized, then -remove the crucible to the muffle, and heat to bright redness -for 10 hours. Cool under the dessicator and weigh. -The increase in weight of the crucible is the ash of the -sample. This will vary from 1 to 2 per cent. in a gelatine, -2 to 3 per cent. in a good glue, 6 to 8 per cent. in a common -quality.</p> - -<p><i>Determination of Acidity.</i> Kissling elsewhere determines the acidity -by suspending 30 grammes of the sample in 80 Cc. of cold -water for 10 to 12 hours in a flask connected with a condenser. -The volatile acids are then driven over by a current -of steam into a graduated cylinder. When the distillate -amounts to 200 Cc., distillation is interrupted, and the -distillate treated with standard decinormal alkali. When -the distillate contains sulphurous acid, a known quantity of -the standard alkali is previously added to the cylinder.</p> - -<p><span class="pagenum" id="Page_206">206</span></p> - -<p>An undue quantity of acid may be detected by the taste. -Glues may be alkaline from the addition of excess of lime -in the manufacture to correct the sourness of the jelly. For -uses where colors are concerned the glue must be neutral to -litmus; for adhesive uses this does not matter unless the -alkalinity or acidity is due to defective preparation (Samuel -Rideal).</p> - -<p><i>Determination of Glutin.</i> The percentage of glutin in a -glue solution is determined by precipitating it with tannin. -The dense white precipitate formed is thrown on to a tared -filter, washed with hot water, dried and weighed. The -calculation is made on the basis that the tannate of glutin -has a percentage composition of 42.74 per cent. of glutin -and 57.26 per cent. of tannin.</p> - -<p>Bisler-Beumat while employing the same principle prepares -two solutions: <i>a.</i> 10 grammes of pure tannin to the -liter. <i>b.</i> 10 grammes of pure isinglass and 20 grammes of -alum to the liter. The ratio in which the tannin is precipitated -by the isinglass solution, which Risler considers as -pure glutin, is then determined by titration. The tannin -solution is then diluted so that exactly an equal volume of -glue solution is precipitated by it.</p> - -<p>In order to test a sample of glue, dissolve 10 grammes of -it together with 20 grammes of alum in a liter of water, -heat being applied if necessary. Next 10 cubic centimeters -of the tannin solution are taken to which an equal bulk -of glue solution is at once added, as one may be sure -that this quantity is not sufficient for the precipitation of -the measured quantity of tannin, because no glue found in -commerce is as pure as isinglass. The vessel containing -the mixed liquids being well shaken and the precipitate -having subsided, another cubic centimeter of glue solution -is added to the tannin solution which is next filtered -through a moist cotton filter. If <em>one</em> drop of the glue solution -still produces a precipitate in the clear filtrate, another -cubic centimeter is added to the tannin solution, and then<span class="pagenum" id="Page_207">207</span> -again filtered, these operations being repeated until the filtrate -is no longer rendered turbid by the glue solution.</p> - -<p>With the known relation of the tannin solution to pure -glue (isinglass), a conclusion may be formed from the number -of cubic centimeters of glue solution used as to the content -of glutin in the sample examined.</p> - -<p>The percentage of glutin varies, of course, according to -the quality and origin of the glue. Bone glue of good -quality contains from 50 to 52 per cent. and skin glue from -65 to 75 per cent.</p> - -<p>S. Dana Hayes analyzed two samples of American glue -of best quality and obtained the following results:</p> - - -<div class="center"> -<table border="0" cellpadding="4" cellspacing="0" summary=""> -<tr> - <th align="left"></th> - <th align="center">a.</th> - <th align="center">b.</th> -</tr> -<tr> - <td align="left">Water (escaping at 212° F.)</td> - <td align="right">16.70</td> - <td align="right">16.28</td> -</tr> -<tr> - <td align="left">Glue substance</td> - <td align="right">79.85</td> - <td align="right">80.42</td> -</tr> -<tr> - <td align="left">Calcium carbonate</td> - <td align="right">1.42</td> - <td align="right">1.33</td> -</tr> -<tr> - <td align="left">Calcium sulphate</td> - <td align="right">0.41</td> - <td align="right">0.34</td> -</tr> -<tr> - <td align="left">Magnesium phosphate</td> - <td align="right">0.35</td> - <td align="right">0.31</td> -</tr> -<tr> - <td align="left">Alkaline salts</td> - <td align="right">0.17</td> - <td align="right">0.12</td> -</tr> -<tr> - <td align="left">Silica, ferric oxide, etc.</td> - <td align="right">0.09</td> - <td align="right">0.08</td> -</tr> -<tr> - <td align="left">Zinc oxide</td> - <td align="right">1.01</td> - <td align="right">1.12</td> -</tr> -</table></div> - -<p>The chemical modes of testing glue give only the quantity -of glutin contained in it, but do not prove that the substance -combined with tannin corresponds to the actual -adhesive power of the glue, for it is possible that a glue -containing a large quantity of glutin may possess but little -adhesive power, and a jelly from which the glue is formed -may contain an equal amount of glutin with the latter, but -not possess an equal power of adhesion.</p> - -<p>It is certain that the determination of the glutin alone is -not a criterion of the quality of glue. In the absence of a -reliable method of direct analysis, attempts have been made -to deduce the quality of glue from indirect properties.</p> - -<p>One of these methods consists in immersing the sample -of glue in a large quantity of water at 59° F. for a considerable -time. The glue swells up, absorbing 5 to 16 times its<span class="pagenum" id="Page_208">208</span> -own weight of water. The more consistent and elastic the -glue in this state is found to be, the greater its adhesive -power, and the larger the quantity of water absorbed the -more economical the glue will be in use. This method -does not give thoroughly reliable results, and should only -be employed with bone-glue, as skin-glue does not behave -in a similar manner.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 65.</span></div> -<img src="images/i_p208.jpg" alt="" /> -</div> - -<p>A more reliable method is to test the strength of a glue -by the method first proposed by Lipowitz, which is based -on the weight-sustaining power of a jelly of known strength -and temperature. The test is executed as follows: Soak 5 -parts of the sample in water, then dissolve it in sufficient -hot water to make the weight of the solution equal to 50 -parts, and allow to stand for 12 hours at 64.4° F. in a glass -cylinder of uniform width to gelatinize. Cover the glass -cylinder with a tin cap perforated in the centre, Fig. 65. -Through the perforation is passed freely a stout iron wire, -at the lower end of which is soldered a piece of tin shaped<span class="pagenum" id="Page_209">209</span> -like a saucer, the convex side of it resting on the surface of -the jelly. To the upper end of the wire, which together -with the tin saucer should weigh 5 grammes, is soldered a -funnel weighing 5 grammes, and capable of holding up to -50 grammes of fine shot. The apparatus is gradually -loaded with shot until the saucer-shaped piece of tin is -forced into the jelly. The greater the strength of the jelly, -the heavier will be the weight required. From the determined -weight of the shot used, the relative value of the -glue as to its adhesive power is determined.</p> - -<p>The following results have been obtained by comparative -experiments with this apparatus:</p> - - - -<div class="center"> -<table border="0" cellpadding="4" cellspacing="0" summary=""> -<tr> - <th align="left">Variety of Glue.</th> - <th align="right">Weight required to<br /> force the saucer down.</th> -</tr> -<tr><td align="left">Breslau</td><td align="right">1704 grammes = 3.74 lbs.</td></tr> -<tr><td align="left">Russian</td><td align="right">1446 grammes = 3.18 lbs.</td></tr> -<tr><td align="left">Cologne</td><td align="right">1215 grammes = 2.67 lbs.</td></tr> -<tr><td align="left">Muhlhausen I.</td><td align="right">727 grammes = 1.599 lbs.</td></tr> -<tr><td align="left">Nördlingen</td><td align="right">724 grammes = 1.592 lbs.</td></tr> -<tr><td align="left">Muhlhausen II.</td><td align="right">387.5 grammes = 0.85 lbs.</td></tr> -</table></div> - - -<p>The results of these experiments agree to a remarkable -degree with the market prices of the varieties of glue, which -is not the case with glues tested by the methods previously -mentioned. The results of these tests are given in the -table below:</p> - -<p><span class="pagenum" id="Page_210">210</span></p> - -<div class="center"> -<table id="glues" border="0" cellpadding="4" cellspacing="0" summary=""> -<col width="2%" /><col width="30%" /><col width="12%" /><col width="11%" /><col width="10%" /><col width="11%" /><col width="24%" /> -<tr> - <th colspan="2">Variety of Glue.</th> - <th>Loss of water in drying for several hours at 239° to 248° F.</th> - <th>100 parts of glue are precipitated by tannic acid</th> - <th>Glutin per cent.</th> - <th>Water absorbed in 24 hours by 5 parts of glue</th> - <th class="nbr">A 100 per cent. solution of glue will bear a weight of</th> -</tr> - -<tr> - <td class="topnbr">1.</td> - <td class="top">Best White isinglass in three qualities</td> - <td>20 to 21</td> - <td>74.62</td> - <td>55.69</td> - <td>—</td> - <td class="nbr"></td> -</tr> -<tr> - <td class="topnbr">2.</td> - <td class="top">Translucent yellowish bone glue in tablets and easily soluble</td> - <td>13.2</td> - <td>76.2</td> - <td>56.8</td> - <td>40</td> - <td class="nbr">64 grammes (2.25 ozs.)</td> -</tr> - -<tr> - <td class="topnbr">3.</td> - <td class="top">Pale yellow glue similar to No. 2</td> - <td>13.0</td> - <td>70.0</td> - <td>52.2</td> - <td>35</td> - <td class="nbr">60 grammes (2.11 ozs.)</td> -</tr> - -<tr> - <td class="topnbr">4.</td> - <td class="top">Brown-reddish, brittle in fracture and soluble</td> - <td>10.0</td> - <td>71.0</td> - <td>52.9</td> - <td>12</td> - <td class="nbr">Does not gelatinize.</td> -</tr> - -<tr> - <td class="topnbr">5.</td> - <td class="top">Clear translucent glue of medium brown color</td> - <td>11.0</td> - <td>71.5</td> - <td>53.3</td> - <td>20</td> - <td class="nbr">20 grammes (0.705 oz.)</td> -</tr> - -<tr> - <td class="topnbr">6.</td> - <td class="top">Brown-yelow glue in thick tablets and possessing but little translucency</td> - <td>12.5</td> - <td>68.0</td> - <td>50.7</td> - <td>27</td> - <td class="nbr">15 grammes (0.52 oz.)</td> -</tr> - -<tr> - <td class="topnbr">7.</td> - <td class="top">Pale brown-yellow glue, readily soluble and elastic before breaking</td> - <td>13.0</td> - <td>66.6</td> - <td>49.7</td> - <td>30</td> - <td class="nbr">36 grammes (1.26 oz.)</td> -</tr> - -<tr> - <td class="topnbr">8.</td> - <td class="top">Pale amber-colored glue with but little translucency</td> - <td>9.5</td> - <td>68.5</td> - <td>51.1</td> - <td>33</td> - <td class="nbr">60 grammes (2.11 oz.)</td> -</tr> - -<tr> - <td class="topnbr">9.</td> - <td class="top">Brown glue, solution turbid</td> - <td>10.0</td> - <td>82.0</td> - <td>53.7</td> - <td>30</td> - <td class="nbr">50 grammes (1.76 oz.)</td> -</tr> - -<tr> - <td class="topnbr">10.</td> - <td class="top">Amber-colored glue, opalizing and readily soluble</td> - <td>9.5</td> - <td>73.0</td> - <td>54.4</td> - <td>35</td> - <td class="nbr">56 grammes (1.97 oz.)</td> -</tr> - -<tr> - <td class="topnbr">11.</td> - <td class="top">Thick tablets or dark-brown glue, solution very turbid</td> - <td>13.5</td> - <td>64.0</td> - <td>47.7</td> - <td>18</td> - <td class="nbr">23 grammes (0.81 oz.)</td> -</tr> - -<tr> - <td class="topnbr">12.</td> - <td class="top">Dark horn-like glue with little translucency</td> - <td>9.0</td> - <td>72.6</td> - <td>54.2</td> - <td>29</td> - <td class="nbr">12 grammes (0.42 oz.)</td> -</tr> - -<tr> - <td class="topnbr">13.</td> - <td class="top">Very translucent glue of a light brown color and very clean solution</td> - <td>13.5</td> - <td>70.0</td> - <td>52.2</td> - <td>30</td> - <td class="nbr">40 grammes (1.41 oz.)</td> -</tr> - -<tr> - <td class="topnbr">14.</td> - <td class="top">Translucent dark-brown glue, giving a very clear solution</td> - <td>15.0</td> - <td>66.0</td> - <td>49.4</td> - <td>25</td> - <td class="nbr">42 grammes (1.48 oz.)</td> -</tr> - -</table></div> - - - -<p>This table shows the following facts:</p> - -<p>1. The percentage of water in the 14 dry varieties of glue -examined varies between 9.0 and 21. The loss of water -from isinglass is surprisingly large, especially as it cannot -be explained by an artificial admixture of water, since the -six varieties examined reabsorbed the same percentage of -water from the air. The percentage of water in the other -varieties of glue differs but little.</p> - -<p>2. The various varieties of glue required different quantities -of tannic acid for their precipitation, the amount for -100 parts of glue varying between 66 parts and 76.2, or -calculated to per cent., between 49.4 and 56.8.</p> - -<p>3. Placed in cold water, glue swells up and absorbs -from 12 to 40 parts of water. The behavior of the various -varieties differs very much in this respect, and in most of<span class="pagenum" id="Page_211">211</span> -the experiments, with the exception of variety No. 4, the -percentage of glutin is in exact proportion to the quantity -of water absorbed.</p> - -<p>4. The strength of the gelatinized glue varies between 12 -grammes (185.18 grains) and 64 grammes (987.67 grains) -for a 10 per cent. solution. This property corresponds -neither with the absorption of water nor the percentage of -glutin.</p> - -<p>Variety No. 4, in the table, contains 52 per cent. of -glutin, but does not gelatinize, its strength being therefore -equal to 0, while variety No. 14, with 49.4 per cent. of -glutin, therefore less than No. 4, shows a strength of 42. -As no close connection between the properties mentioned in -the table can be recognized, it is best not to be guided by -these properties alone, but to test also the behavior of the -glue in practical use. Such test consists in estimating the -adhesive power of the glue from the weight required to tear -asunder two pieces of wood glued together and dried. But -as the results obtained by this purely practical test must -necessarily vary on account of the impossibility of having -two surfaces of wood always exactly alike, and the uncertainty -of applying every time the same quantity of glue, -Weidenbusch’s method may here be given. It is based -upon the principle that sticks of plaster of Paris cast of -exactly the same material and of uniform size break under -the same weight when placed upon two supports and loaded -in the centre. If now such plaster sticks be saturated with -glue solutions prepared according to the same method, but -from different qualities of glue, a greater force will be -required for breaking them, and this force will be the -greater the better the quality of glue is.</p> - -<p>The plaster sticks are prepared as follows: Reduce pure -crystallized gypsum to a fine powder, pass the latter through -a sieve having 324 meshes per square centimeter and heat -it to between 284° and 302° F. For casting the sticks -moulds of soap-stone are used. The moulds are made by<span class="pagenum" id="Page_212">212</span> -boring in a piece of soap-stone, at a distance of about 1 -centimeter from each other, holes with a diameter of 6 -millimeters on top and 7½ millimeters on the bottom.</p> - -<p>The gypsum is weighed off in portions of 1 gramme each, -mixed with 1 gramme water and cast in the moulds. The -solidified sticks are first dried at a moderate heat and then -over calcium chloride, and kept for use in an air-tight -vessel.</p> - -<div class="figcenter" > -<div class="caption"><span class="smcap">Fig. 66.</span></div> -<img src="images/i_p212.jpg" alt="" /> -</div> - -<p>The glue solution is prepared as follows: The glue dried -at 212° F. is weighed, soaked over night in water, then -melted in a small glass in the water-bath, and finally -enough water is added so that the solution contains 10 per -cent. of dry glue.</p> - -<p><span class="pagenum" id="Page_213">213</span></p> - -<p>The plaster sticks are for one or two minutes immersed -in the glue solution heated to 212° F., and then placed -vertically upon a glass plate until superficially dry, when -they are completely dried at 212° F. It is recommended -to color the glue solution with indigo, the uniform saturation -of the sticks being thereby more easily recognized.</p> - -<p>The apparatus for testing the strength of the sticks consists -of a brass ring <i>a</i>, Fig. 66, having two notches to receive -the stick, and its diameter is divided into two equal -parts by an indicator. The ring is supported by a pin, by -means of which it is secured in a stand. The apparatus is -completed by an iron or glass cup which is suspended by -three cords, <i>i</i>, and the hook <i>f</i> to the plaster stick <i>b</i>. The -hook <i>f</i> is placed in the position indicated by the indicator. -Mercury is now poured into the cup until the plaster stick -commences to break. The weight required is recorded and -compared with a standard glue. During the experiment -the cup is suspended by the three cords <i>h</i> to the ring <i>a</i>, and -is thus caught when the plaster stick breaks. On the lower -end of the cup is a clip for emptying the mercury into a -vessel so that none of it is lost.</p> - -<p>The “Artillery Werkstätte” at Spandau has adopted the -severing strain of two blocks of wood glued together. The -test is executed as follows: Three parts of glue (but not less -than 250 grammes) are mixed with 6 parts of water and -boiled in a steam bath until the weight of the boiled glue -amounts to only 5/9 of the original mixture. The reason for -this continued boiling is to ascertain whether the glue to be -tested retains the required adhesive power even after six -hours continued heating in a steam bath as frequently happens -in the workshop. With the glue thus prepared the -following breaking test is made:</p> - -<p>Blocks of hard or soft wood 420 millimeters long and -40 × 40 millimeters cross section are cut in two, so that each -piece thus obtained is 210 millimeters in length. These -two pieces are then again glued together across the grain<span class="pagenum" id="Page_214">214</span> -with the glue to be tested. The block is then placed in a -dry room at a temperature of 62° to 68° F. for 72 hours, -when the joint is tested as to its resisting power. At a distance -of 180 millimeters from the joint a hole is bored in -the block. Through this hole is pushed a bolt furnished -on the lower end with a hook to which a scale is suspended. -The block of wood is clamped to a table so that the joint -projects 1 centimeter beyond the edge. The scale is at the -start loaded with 25 kilograms, the load being every five -minutes increased 5 kilograms till fracture takes place.</p> - -<p>Two such blocks, one of hard and one of soft wood, are -subjected to the test, and a serviceable glue must stand at -least an average load of 70 kilograms.</p> - -<p><i>Determination of adulterations.</i> White lead, sulphate of -lead, zinc white, or chalk in quantities varying from 4 to -8 per cent. are frequently mixed with the melted glue to -improve the appearance of the finished product. Thus, -according to analyses by A. Faisst, Russian glues contained -in 100 parts foreign admixtures as follows:</p> - -<div class="center"> -<table border="0" cellpadding="4" cellspacing="4" summary=""> -<tr> - <th></th> - <th>I.</th> - <th>II.</th> - <th>III.</th> - <th>IV.</th> -</tr> -<tr> - <td class="cl">Zinc white</td> - <td>1.66</td> -</tr> -<tr> - <td class="cl">Chalk</td> - <td>2.40</td> - <td>2.95</td> - <td>3.79</td> - <td>2.10</td> -</tr> -<tr> - <td class="cl">Sulphate of lead</td> - <td>—</td> - <td>4.16</td> - <td>2.35</td> - <td>3.18</td> -</tr> -<tr> - <td class="cl"></td> - <td class="ccbt">4.06</td> - <td class="ccbt">7.08</td> - <td class="ccbt">6.14</td> - <td class="ccbt">5.28</td> -</tr> -</table></div> - - -<p>The so-called patent glue which is opaque and of a white -color is produced by adding considerable quantities of white -lead to ordinary glue.</p> - -<p>According to Barreswil, glue is frequently mixed with -lead acetate solution to protect it from putrefaction. Such -an addition, as well as the presence of white lead or sulphate -of lead, is detected by the introduction of sulphuretted -hydrogen into very dilute glue solution. In the presence -of lead acetate a black precipitate of lead sulphide appears -in the clear solution; if white lead or lead sulphate is present, -the white powder settling on the bottom is blackened -by the formation of lead sulphide.</p> - -<p><span class="pagenum" id="Page_215">215</span></p> - -<p>For the detection of other earthy additions, prepare a -very dilute solution of the glue in question and allow it to -stand quietly for a few hours. The heavy additions subside, -and after decanting the supernatant fluid is collected -upon a small filter and examined by the customary analytical -methods.</p> - -<p>It is difficult to say what quantities of earthy constituents -actually constitute an adulteration, since it is claimed by -many practical men that a considerable content of earthy -parts is of advantage as regards the cementing power of -glue. Generally speaking it may, however, be said that -a glue containing more than 6 to 8 per cent. of earthy constituents -must be considered adulterated.</p> - -<p>For many purposes, especially if the glue comes in contact -with colored materials as, for instance, in book-binding, -a content of free acid would exert an injurious effect upon -the colors, destroying or changing them. It is therefore -advisable to test the glue with blue litmus paper which, in -the presence of free acid, is reddened.</p> - -<p>In testing a large number of samples of glue, Kissling -obtained the following results:</p> - -<div class="center"> -<table border="0" cellpadding="4" cellspacing="0" summary=""> -<tr><th><span class="smcap">Skin Glue.</span></th><th>Number<br />of samples.</th><th>Smallest<br />percentage.</th><th>Largest<br />percentage.</th><th>Average<br />percentage.</th></tr> -<tr><td class="cl">Water</td><td>15</td><td>13.4</td><td>18.1</td><td>15.7</td></tr> -<tr><td class="cl">Ash</td><td>16</td><td>1.0</td><td>4.13</td><td>2.15</td></tr> -<tr><td class="cl">Fat</td><td>21</td><td>0.01</td><td>0.090</td><td>0.037</td></tr> -<tr><td class="cl">Volatile acids, free</td><td rowspan="2">8</td><td>0.084</td><td>0.238</td><td>0.178</td></tr> -<tr><td class="cl">Volatile acids, fixed</td><td>0.084</td><td>0.334</td><td>0.191</td></tr> -<tr><th><span class="smcap">Bone Glue.</span></th></tr> -<tr><td class="cl">Water</td><td>25</td><td>11.5</td><td>17.7</td><td>13.4</td></tr> -<tr><td class="cl">Ash</td><td>26</td><td>1.16</td><td>5.07</td><td>2.46</td></tr> -<tr><td class="cl">Fat</td><td>5</td><td>0.047</td><td>0.217</td><td>0.113</td></tr> -<tr><td class="cl">Volatile acids, free</td><td rowspan="2">7</td><td>0.088</td><td>1.451</td><td>0.655</td></tr> -<tr><td class="cl">Volatile acids, fixed</td><td>0.097</td><td>0.721</td><td>0.460</td></tr> -</table></div> - -<p>However, those who from their practical knowledge are -most competent to judge the commercial value of a glue, -scarcely require such complicated tests, as by taking the<span class="pagenum" id="Page_216">216</span> -sample in their hand and looking at it, they can in most cases -tell its quality. Great hardness, a clear, rattling sound when -struck, and resistance to breaking are signs of good quality, -and if the cake is cut thick, it shows that the jelly possessed -great consistency. Many kinds of glues are intentionally -cut thin so that they will dry before spoiling. The derivation -of a glue from a sound jelly is recognized by the fine -cutting lines. When the jelly possesses but little gelatinizing -power and is in the first stages of decomposition or -putrefaction, or formation of sugar has already set in, it cannot -be poured into moulding boxes, as it would putrefy before -it has a chance to gelatinize. Such sick jelly is poured -in thin layers upon glass or metal plates so that it may -acquire sufficient solidity to allow of its being cut up into -leaves and dried upon nets. If the edges of the glue are -deeply indented and raised, the jelly, before drying, possessed -but little concentration (25 to 30 per cent.), and if -notwithstanding this, it acquired sufficient consistency to -allow of its being cut, it must have been very sound. -Glues cut thick and showing no indentations and raised -edges, are derived from excessively concentrated jellies -(30-35-40 per cent.). Such jellies lose in quality in -evaporating.</p> - -<p>A high degree of transparency is a favorable sign as regards -the purity of a glue, substances inducing putrefaction -having been eliminated. Hence this property should be -worthy of recommendation, but the consumer having been -disappointed in the use of thin glass-clear glues, distrusts -also the thick-cut transparent product, preferring a turbid, -translucent or opaque article. For this reason the manufacturer -is forced to render glass-clear glue turbid with coloring -matter.</p> - -<p>The color of the glue is also a means of judging it. To -be sure, chemically pure glutin is a colorless substance, but -glue is always colored more or less dark brown. Although -this coloration does not in the least impair the adhesive<span class="pagenum" id="Page_217">217</span> -power, the manufacturer endeavors to produce a product of -as light a color as possible, and this is best effected by -bleaching with sulphurous acid. By this means the glue -not only acquires a lighter color, but also becomes more -stable, substances inducing putrefaction being destroyed by -the acid.</p> - -<hr class="chap" /> - -<p><span class="pagenum" id="Page_218">218</span></p> - - - - -<h2><a name="PART_II" id="PART_II">PART II.</a><br /> - -<small>CEMENTS, PASTES, MUCILAGES.</small></h2> - - - -<hr class="small" /> -<div class="chapter"></div> -<h3><a name="CHAPTER_XII" id="CHAPTER_XII">CHAPTER XII.</a><br /> - -<small>CLASSIFICATION OF CEMENTS.</small></h3> - - -<p>The great variety of substances entering into the manufacture -of cements and pastes makes a division of them -extremely difficult. Stohmann divides them into the following -groups:</p> - -<p> -1. <i>Oil cements.</i><br /> -2. <i>Resinous cements.</i><br /> -3. <i>Cements containing rubber or gutta percha.</i><br /> -4. <i>Cements containing glue, or starch paste.</i><br /> -5. <i>Lime cements.</i><br /> -</p> - -<p>Generally speaking, this division is correct; the only -change we would suggest is to apply the term <em>agglutinant</em> -or <em>paste</em> to bodies containing glue and starch paste.</p> - -<p>When we attempt a division of the cements according to -the bodies to be cemented, we find that the result will be a -larger number of groups; as we must take into consideration -whether the articles to be cemented have to be heated -or not, whether they are to come in contact with water or -other liquids, and other circumstances which would necessitate -modifications in the composition of the cements -themselves.</p> - -<p>According to this, we might group the cements as follows:</p> - -<p><span class="pagenum" id="Page_219">219</span></p> - -<p class="hang">1. <i>Cements for glass and porcelain, for repairing broken -articles, for fastening glass letters upon show-windows, -etc.</i></p> - -<p>2. <i>Cements for metals not exposed to an increase of temperature, -for instance, for tightening the joints of gas and -water pipes.</i></p> - -<p class="hang">3. <i>Cements for stoves and other articles, which have to stand -an increased temperature.</i></p> - -<p class="hang">4. <i>Cements for chemical apparatus, i. e., such as will have to -resist the action of chemical agents.</i></p> - -<p class="hang">5. <i>Cements to protect vessels of glass, porcelain, or metal -against the action of fire.</i></p> - -<p class="hang">6. <i>Cements for filling hollow teeth, for microscopical preparations, -and other delicate articles.</i></p> - -<p class="hang">7. <i>Cements for special purposes, for instance, for cementing -meerschaum, tortoise shell, etc.</i></p> - -<p><i>Chemical nature of cements.</i> The different varieties of -cement frequently contain substances which act chemically -upon each other, or upon the bodies to be united with them. -To determine the practical availability of a variety of -cement for a determined purpose, it is of importance to -know the reciprocal behavior of these substances towards -each other, as from this we are able to judge at once -whether a cement is suitable for a certain purpose or not.</p> - -<p><i>Oil cements.</i> The fluid fats, commonly called oils—though -there are oils which remain solid at the ordinary -temperature, as, for instance, palm oil and cocoanut oil—may, -as regards their behavior on exposure to the air, be -divided into two large groups, namely, drying and nondrying -oils. As samples of these groups may be mentioned -olive oil and linseed oil.</p> - -<p>If a thin layer of olive oil protected from dust is exposed -to the air, it will remain fluid for years and retain its characteristic -oily consistency. The only change it undergoes -is that it becomes somewhat more viscid and rancid, and -acquires a darker color, but it never dries up.</p> - -<p>Linseed oil treated in the same manner solidifies in the<span class="pagenum" id="Page_220">220</span> -course of a few weeks to a hard, tough and elastic mass, resembling, -as regards its physical qualities, resin or rubber.</p> - -<p>By compounding a drying oil with a small quantity of -litharge, pyrolusite, manganous borate, etc., and heating -the admixture to the boiling-point, it acquires the property -of drying in a few hours when exposed to the air in a thin -layer. Oil so treated has been changed to a varnish.</p> - -<p>By bringing a drying oil in contact with a body possessing -strong basic properties a peculiar process takes place; -the sebacic acids contained in the oil combine with the -basic bodies to solid combinations which are insoluble in -water, and, on exposure to the air, change gradually into -masses as hard as stone. Such combinations, as regards -their chemical composition, resemble ordinary soap, and for -this reason are called insoluble soaps to distinguish them -from ordinary soap which is soluble in water.</p> - -<p>Burned lime, calcined magnesia, whiting, ferric oxide, -litharge, and minium possess the capacity for forming insoluble -soaps on coming in contact with drying oils and, -still more quickly, with varnishes prepared from them.</p> - -<p>The hardness of these soaps in time increases considerably -by the oil not saponified drying in. The oil cements are -principally used for tightening water and gas pipes, as they -resist the action of water, steam and gas.</p> - -<p>The only drawback connected with these cements is that -they must reach a certain age before becoming entirely hard, -and that, on account of the high price of drying oil or -varnish which is absolutely required for their preparation, -they are rather expensive. The ordinary glazier’s putty and -the red lead and linseed-oil cement used in constructing -water and gas conduits belong to this group.</p> - -<p><i>Resinous cements.</i> By resins are understood a number of -constituents of plants which exude in thick viscous masses -through incisions made in the trees, and on exposure to air -are gradually converted into less transparent, brittle masses. -When heated they melt more or less readily, forming a<span class="pagenum" id="Page_221">221</span> -thick, ropy liquid, and brought in contact with an ignited -body they burn with a bright flame and much sooty smoke.</p> - -<p>By making incisions in the bark of any of the whole -genus of <i>Pinus</i> belonging to the <i>Coniferæ</i> family, a viscous -mass of a strong odor, called turpentine, is obtained. It -consists of a solution of common rosin in the essential oil of -turpentine, and when distilled yields from 75 to 90 per -cent. of colophony or rosin, which remains in the retort, -and from 25 to 10 per cent. of the essential oil, commonly -called spirits of turpentine. Pure rosin is a brittle, tasteless, -and almost inodorous mass of a light yellow color and -a smooth, shining fracture.</p> - -<p>The various resins found in commerce, such as shellac, -mastic, elemi, copal, etc., are formed in a similar manner.</p> - -<p>The principal points of importance for our purpose are -the different degrees of hardness and brittleness and the -melting-points of the various resins. While some possess -but slight hardness, for instance elemi, others, such as copal -and amber, excel in this respect and their brittleness and -high melting-point.</p> - -<p>To decrease the brittleness of resins, essential oils are -sometimes added, or resinous cements are mixed with oil -cements or a fat drying oil, or compounded with rubber -cement.</p> - -<p>Resinous cements are either softened by heating or entirely -melted, or solutions of resins in volatile solvents are -used, which, in evaporating, leave the resin behind.</p> - -<p>The resinous cements possess great power of resistance, -and are therefore well adapted for tightening water and gas -pipes, but they have the disadvantage of not standing a -high temperature and possessing a certain degree of brittleness -which renders them unfit for the cementing of articles -exposed to frequent shocks.</p> - -<p>Many of these cements, especially those prepared with -pitch or asphaltum, can be produced at a very low cost, -and do excellent service for water-proofing vessels, water-reservoirs, -brickwork, etc.</p> - -<p><span class="pagenum" id="Page_222">222</span></p> - -<p><i>Rubber and gutta-percha cements.</i> Caoutchouc, commonly -called India rubber, or briefly rubber, is derived from the -milky juices of certain tropical plants. It is distinguished -by great elasticity and indifference to chemical agents.</p> - -<p>Both these properties make it a valuable material for -cement, and it is much used for this purpose either in the -form of solution or as a constituent of other compositions. -For cements which are to have a certain degree of elasticity -combined with indifference toward chemical agents, it is -absolutely indispensable, as no other known body possesses -these properties in such a high degree.</p> - -<p>The derivation of gutta percha is similar to that of -rubber. At an ordinary temperature it forms solid and -very tenacious masses, of a leather-like consistency, but at -a somewhat higher temperature (below the boiling-point of -water) it is converted into a very plastic, soft mass, which -can be drawn into very fine threads, and rolled to very -thin plates.</p> - -<p>By itself or mixed with other substances it furnishes an -excellent cement, possessing the valuable properties of -tenacity and pliancy when exposed to shocks. As regards -resistance to the action of water and chemical agents it is -almost equal to rubber, and, for certain purposes, is frequently -preferred to the latter.</p> - -<p><i>Glue and starch cements.</i> By itself, <i>i. e.</i>, converted by -boiling with water into a viscous mass which solidifies on -cooling, glue cannot be classed with the cements; the same -applies to paste, <i>i. e.</i>, starch or flour swelled and boiled in -water.</p> - -<p>But compounded with other substances both yield excellent -cements, in which a part of the properties distinguishing -glue solution and paste is preserved. They both -possess the property of decreasing the brittleness of many -cements, but unfortunately the latter thereby lose their -power of resisting the action of water; for starch as well as -glue swells in water, and the latter, when moist, passes -quickly into putrefaction and destroys the cement.</p> - -<p><span class="pagenum" id="Page_223">223</span></p> - -<p>In a wider sense isinglass, compounds of glue and -vinegar, of lime and glue, etc., must be classed with the -glue cements, and ordinary flour and shoemakers’ paste -with starch cements.</p> - -<p><i>Lime Cements.</i> Lime possesses the property of forming -insoluble combinations with egg albumen or caseine, this -being the reason why lime cements, of which there are a -great number, are generally composed of burned lime and -one or the other of the above substances. Lime compounded -with a solution of water-glass forms also very -solid and durable cements.</p> - -<p>Although the cements and agglutinants mentioned in -the foregoing are most frequently used, a compound of -different cements is often employed, in consequence of -which the composition of many cements is very complicated.</p> - -<p>In the following we give a description of the preparation -of the different kinds of cement, according to the manner -of their employment.</p> - -<hr class="chap" /> - -<p><span class="pagenum" id="Page_224">224</span></p> - - - - -<div class="chapter"></div> -<h3><a name="CHAPTER_XIII" id="CHAPTER_XIII">CHAPTER XIII.</a><br /> - -<small>PREPARATION OF CEMENTS, PASTES, AND MUCILAGES.</small></h3> - - -<h4>OIL CEMENTS.</h4> - -<p>Oil cements, as already explained, must be considered as -a variety of soaps insoluble in water, formed by the action -of drying oils or varnish upon various basic combinations.</p> - -<p>The most important of this class is the cement used for -securing window-panes. Good glaziers’ putty is a product -of extraordinary durability, and, besides for puttying glass -and wood, can also be used for joining many other bodies.</p> - -<p><i>Putty.</i> This is prepared by mixing fine whiting with -linseed oil or linseed-oil varnish. The whiting should be -passed through a sieve of 42 meshes to the inch. It should -be perfectly dry before sifting, and be thoroughly incorporated -with the oil.</p> - -<p>As the work of kneading large masses with the hands or -feet must be continued for a long time in order to obtain an -entirely uniform product, and is consequently very laborious, -it is recommended to use the following contrivance:</p> - -<p>Two wooden rollers rest in a suitable frame, and can be -brought together or removed from each other by means of -two screws. When the mixture of whiting and linseed oil -is of sufficient consistency to allow kneading, it is fashioned -into a cylinder and rolled out between the above rollers to -a long, thin band, which is caught in a vessel. The band -is balled together, the ball reformed into a cylinder, and -the latter again passed through the rollers, the operation of -balling and rolling being continued until a uniform mass -is obtained.</p> - -<p>The finished product should be kept in oiled paper or<span class="pagenum" id="Page_225">225</span> -under water. White lead is sometimes mixed with the -putty, and other pigments to give color as desired. Hard -putty may be softened by rolling between the hands.</p> - -<p><i>French putty.</i> Boil 7 lbs. of linseed oil with 4 lbs. of -burnt umber for 2 hours. Then add 10 lbs. of white lead -and 5½ lbs. of chalk.</p> - -<p><i>Soft putty.</i> Whiting 20 lbs., white lead 2 lbs., linseed -oil and olive oil 1 gill each.</p> - -<p>Mix the whiting and the white lead with the necessary -quantity of linseed oil, to render the putty of the proper -consistence, the olive oil being added to the linseed oil before -kneading. The object of using olive oil is to prevent the -white lead from hardening, and it preserves the putty in a -state sufficiently soft to adhere at all times, and not, by getting -hard and cracking off, suffering the wet to enter, as is -often the case with ordinary hard putty.</p> - -<p><i>Litharge cement.</i> By mixing litharge reduced to a fine -powder with linseed oil, a yellow cement is obtained which -gradually solidifies to a mass as hard as stone.</p> - -<p><i>Red lead cement</i> is made by mixing red lead with linseed -oil to a paste. It is used for cementing the joints of metal -pipes.</p> - -<p>Lead preparations furnish excellent cements, but have -the disadvantage of great weight and a high price. For -many purposes a part of the lead combination can be suitably -replaced by a substance of less weight, such as whiting, -or, still better, burned lime slacked with sufficient water to -convert it into a powder.</p> - -<p>The quantity of the substitute added varies very much, -there being, for instance, many varieties of so-called red lead -oil cement, which contain only about 10 per cent. of red lead.</p> - -<p><i>Cement for wash basins.</i> Finely powdered glass (sifted) 2 -parts, litharge 2 parts, linseed-oil varnish 1 part.</p> - -<p>Wet the powders slightly with the oil, heat and gradually -add the rest. Do not use the basin for several days. Finely -powdered glass or glass meal may be made by heating glass,<span class="pagenum" id="Page_226">226</span> -throwing it in cold water, grinding the fractured pieces, and -washing by stirring up in water, and allowing the finer -particles to float off into a second vessel. Collect this fine -powder when sufficient has settled in the vessel and sift it -through a very fine sieve.</p> - -<p><i>Zinc-white cement</i> is prepared similar to putty or red-lead -cement. It may, however, be made as follows: Mastic 2 -parts, dammar 4 parts, sandarac 6 parts, Venetian turpentine -8 parts, turpentine 10 parts, benzole 12 parts, zinc -white 14 parts.</p> - -<p>The resins are powdered, while the Venetian turpentine, -ordinary turpentine, and benzole, are put in a bottle, and -then the powdered resins put in. The whole is shaken and -allowed to stand for the resins to dissolve. The solution is -filtered through cotton-wool and rubbed up with sufficient -zinc-white to form a cement. Dilute with benzine if -necessary.</p> - -<p><i>Mastic cement, mastic or pierres de mastic.</i> Under this -name masses are brought into commerce which are well -adapted for moulding ornaments, such as figures, columns, -etc., to be exposed to the weather. They are comparatively -cheap, and it is rather remarkable that they are not more -generally known and used for technical purposes.</p> - -<p>To prepare large quantities of this cement suitable mills -and mixing vessels are required, as the conversion of the -materials into a dust-like flour is an indispensable condition -of the success of the work. The materials most generally -used are fine quartz sand, finely ground calcareous sand, -and varying quantities of litharge or zinc oxides, besides as -small a quantity of linseed oil as possible.</p> - -<p>The linseed oil combines with the litharge or zinc oxide -to an insoluble soap, which incloses the other material and -forms a mass acquiring the hardness of sandstone in thirty -to fifty hours.</p> - -<p>After converting the materials into a fine powder, the -mixing is accomplished in barrels filled about three-quarters<span class="pagenum" id="Page_227">227</span> -full and revolved by water-power. When a thorough mixture -has been effected the pulverulent mass is placed in -sheet-iron vessels and saturated with linseed oil, and then -moulded at once, as it solidifies in one or two days.</p> - -<p><i>French mastic.</i> Quartz sand 300 parts, pulverized limestone -100, litharge 50, linseed oil 35.</p> - -<p><i>Paget’s mastic.</i> Sand 315 parts, whiting 105, white lead -25, calcined red lead 10, lead acetate solution 45, linseed -oil 35.</p> - -<p>The mastic may be colored by adding pigments.</p> - -<p><i>Water-proof cement.</i> <i>A.</i> Rubber 7 parts, oil of turpentine -140, linseed oil 40. <i>B.</i> Turpentine 100 parts, sulphuric -acid 3, zinc-white 10.</p> - -<p>To prepare solution <i>A</i>, place the rubber in the oil of -turpentine in a bottle. It swells very much without -actually dissolving. After adding the linseed oil, reduce -the entire mass by boiling to one-half the volume originally -occupied by it.</p> - -<p>Solution <i>B</i> is prepared by stirring the sulphuric acid into -the turpentine and allowing it to stand for twelve hours. -To remove the sulphuric acid, the thick mass which has -been formed is then kneaded in water in which the zinc -oxide has been distributed. After drying, the resulting -mass is dissolved in the warm fluid <i>A</i>.</p> - -<p><i>Another formula</i> is as follows: Linseed oil 8 parts, litharge -12, burnt lime 88.</p> - -<p>Boil the linseed oil and litharge half an hour, then stir -the lime into the hot mass, and use the mixture hot. This -cement is excellent for filling in joints between stones, for -flat roofs, water reservoirs, etc. For a better adhesion of -the cement, apply a coat of linseed oil varnish to the surfaces -to be cemented. Porous stones are made water-proof -by heating the cement in a boiler and adding sufficient -linseed oil to form a mass which can be readily worked -with a smoothing board. Apply as hot as possible.</p> - -<p><i>Serbat’s mastic.</i> Pyrolusite 60 parts, sulphate of lead 60, -linseed oil 10.</p> - -<p><span class="pagenum" id="Page_228">228</span></p> - -<p>After thoroughly drying the materials, mix the sulphate -of lead with the linseed oil, then add 20 parts of the pyrolusite -and, after mixing and working it thoroughly, add -gradually the rest of the pyrolusite in small portions and -kneading constantly.</p> - -<p><i>Stephenson’s oil cement.</i> Litharge 20 parts, unslaked lime -10 parts, sand 10 parts, hot linseed oil 3 parts.</p> - -<p><i>Alum cement.</i> Dissolve good hard soap, by heating in -rain water, dilute the thickly fluid mass and add saturated -alum solution as long as a precipitate is formed. Collect -the gelatinous precipitate of alumina soap thus formed -upon a cloth, and, after draining, pour rain water over it -ten to twelve times to remove the salts as much as possible. -After washing, dry the alumina soap, and rub it to a fine -powder.</p> - -<p>To prepare cement rub a portion of the powder with -sufficient linseed-oil varnish to form a plastic dough, which -is used for filling in the joints.</p> - -<p>This cement is water-proof, resists high temperatures -without being absolutely fire-proof, and, on account of its -light color, is well adapted for joining marble plates, etc.</p> - -<p><i>Oil cement for glass.</i> Litharge 30 parts, burnt lime 20, -pipe-clay 10, linseed-oil varnish 6.</p> - -<p><i>Oil cement free from lead for steam pipes.</i> Graphite 12 -parts, heavy spar 16, slaked lime 6, boiled linseed oil 6.</p> - -<p><i>Oil cements for steam pipes.</i> I. Litharge 25 parts, air-slaked -lime 10, quartz sand 10.</p> - -<p>Mix the ingredients quickly with the linseed oil and -work the mass thoroughly in a hot mortar. Coat the defective -places in the pipes with linseed-oil varnish, apply -the cement hot and when partially solid, make it still -tighter by heating.</p> - -<p>II. Boil 60 parts of graphite, 50 of air-slaked lime, 60 of -elutriated heavy spar in 35 of linseed oil, stirring constantly. -Apply the mixture hot.</p> - -<p><i>Oil cement for marble.</i> Elutriated litharge 10 parts, -brick dust 100, linseed oil 20.</p> - -<p><span class="pagenum" id="Page_229">229</span></p> - -<p>Prepare in the same manner as glaziers’ putty. For -various colors add zinc white for white, red lead for red, -pyrolusite for brown, etc. Previous to applying the cement -saturate the surfaces of the stones to be cemented with linseed-oil -varnish.</p> - -<p><i>Oil cement for porcelain.</i> Stir 20 parts of white lead and -12 of white pipe-clay into 10 of boiling linseed oil previously -boiled and knead the mass thoroughly. After cementing -let the articles stand quietly for several weeks.</p> - -<p><i>Diamond cement.</i> Litharge 30 parts, air-slaked lime 10, -whiting 20, graphite 100, linseed oil 40. Apply hot. This -is an excellent cement for metal.</p> - -<p><i>Hager’s diamond cement.</i> Whiting 16 parts, elutriated -graphite 50, litharge 16.</p> - -<p>Mix the pulverized ingredients with sufficient old, thick -linseed oil to form a plastic dough.</p> - - -<h4>RESINOUS CEMENTS.</h4> - -<p><i>Resinous cement for amber</i> is obtained by melting mastic -in linseed oil. Volatile copal lacquer can also be advantageously -used for the purpose.</p> - -<p><i>Cement for turners.</i> Melt 1 lb. of rosin in a tin can over -the fire, and when melted add 4 ozs. of pitch; while these -are boiling add brick dust until, by dropping a little on a -cold stone, you think it is hard enough. In winter it may -be found necessary to add a little tallow.</p> - -<p>By means of this cement a piece of wood may be fastened -to the chuck, which will hold when cool, and when the -work is finished, it may be removed by a smart blow with -the tool. All traces of the cement may be removed from -the work by repeated applications of benzine. To use this -cement, chip off as much as will cover the chuck to the -1/16th of an inch, spread it over the surface in small pieces, -mixing it with ⅛ of its bulk of gutta-percha, then heat an -iron to a dull red heat, and hold it over the chuck till the -mixture and gutta-percha are melted and liquid. Stir the<span class="pagenum" id="Page_230">230</span> -cement until it is homogeneous, chuck the work, lay on a -weight to enforce contact, leave it at rest 20 minutes.</p> - -<p>The following cement is much employed and serviceable -for the use of turners and artisans in general.</p> - -<p>Reduce 1 lb. of whiting to a fine powder, and heat to -redness so as to expel all the water. When cold this is -mixed with 1 lb. of black rosin and 1 oz. of beeswax previously -melted together, and the whole stirred till of uniform -consistence.</p> - -<p><i>Cement for ivory and bone.</i> Melt at a moderate heat equal -parts of white wax, rosin, and oil of turpentine to form -a thickly-fluid mass. For coloring the cement add elutriated -red lead, ultramarine, etc.</p> - -<p><i>Cement for white enameled clock-faces.</i> Dammar resin 100 -parts, copal 100, Venice turpentine 110, zinc white 60, -ultramarine 3.</p> - -<p>Apply hot and polish when cold and hard.</p> - -<p><i>Cements for glass.</i> 1. Melt carefully 60 parts of bleached -shellac and 10 of turpentine. If too thick, dilute with -turpentine.</p> - -<p>2. Shellac 20 parts, elemi 5, turpentine 10. Prepare as -above.</p> - -<p><i>Cement for glass upon glass.</i> Shellac 10 parts, turpentine -2, pulverized pumice stone 10.</p> - -<p><i>Cement for glass upon metal.</i> Melt together 40 parts of -rosin, 20 of rouge, 10 of wax, and 10 of turpentine. Apply -hot to the surfaces to be cemented.</p> - -<p><i>Cement for metal letters upon glass.</i> Rosin 42 parts, turpentine -4, plaster of Paris 5.</p> - -<p><i>Cement for wood.</i> 100 parts of shellac and 45 of strong -spirit of wine.</p> - -<p>This cement serves for joining wood, which, on account -of exposure to water, cannot be glued. Apply the cement -to the surface of one of the pieces, and after placing upon -it a piece of tissue paper press upon it the other piece of -wood previously coated with the cement.</p> - -<p><span class="pagenum" id="Page_231">231</span></p> - -<p><i>Cement for knife handles.</i> Melt together 20 parts of rosin, -5 of sulphur, and 8 of iron filings.</p> - -<p>Pour some of the hot mixture into the handle, and then -push in the knife previously heated.</p> - -<p><i>Cement for petroleum lamps.</i> Boil 12 parts of rosin in 16 -of strong lye until it is entirely dissolved and on cooling -forms a tenacious solid mass. Dilute this with 20 parts of -water, and carefully work into it 20 parts of plaster of -Paris. This cement is insoluble in petroleum, and is especially -adapted for cementing the glass parts of lamps to the -metal. It is also a good material for stoppers for petroleum -bottles.</p> - -<p><i>Cement for porcelain.</i> Rosin, 14 parts; elemi, 7; shellac, -7; mastic, 7; sulphur, 42; brick dust, 20.</p> - -<p><i>Cement for porcelain which is to be heated.</i> Heat carefully -10 parts of amber in a large spoon, stirring constantly, until -it evolves heavy vapors of a strong odor. Rub the melted -mass as finely as possible, and after placing the powder in a -bottle pour over it a mixture of bisulphide of carbon and -benzine. Close the bottle air-tight to prevent the evaporation -of the very volatile solvent. When the powder is dissolved -remove the cork and replace it by one provided with -a small brush. The application of the cement and pressing -together of the parts to be cemented must be effected as -quickly as possible. In articles properly cemented the -joint can only be detected by the closest examination. -This cement holds so well that cups and saucers, soup-tureens, -etc., mended with it can be used for years.</p> - -<p><i>Cement to withstand the action of petroleum.</i> Dissolve 5 -parts of shellac, 1 of turpentine in 15 of petroleum. This -cement is quite elastic.</p> - -<p><i>Cement for mica.</i> A colored cement for joining sheets of -mica is prepared as follows: Soak clean gelatine in water, -and when swelled squeeze out the excess of water by pressure -between a cloth, then melt the gelatine by the heat of -a water-bath, and stir in just enough proof spirit to make it<span class="pagenum" id="Page_232">232</span> -fluid. To each part of this solution add, while stirring, ¼ -oz. of gum ammoniac and 1½ ozs. of gum mastic dissolved -in 4 ozs. of rectified alcohol. Put the mixture into bottles, -and when required for use stand the bottle in hot water. -This cement resists cold water.</p> - -<p><i>Cement for horn, whalebone and tortoise shell.</i> Dissolve -gum mastic 10 parts and turpentine 4, in 12 of linseed oil. -Apply hot.</p> - -<p><i>Cement for terra-cotta articles.</i> Melt together 70 parts of -rosin, 70 of wax and 16 of sulphur, and stir into the mass 8 -parts of hammer slag and 8 of quartz sand. Coat the fractured -surfaces with oil of turpentine, apply the cement as -quickly as possible, and press the surfaces together. It is -advisable to heat the terra cotta previously to 158° or 176° -F. After cementing the article, smooth the joint with a -heated knife and dust very fine terra-cotta powder through -a linen bag upon the soft cement in order to give it exactly -the same color as the article itself.</p> - -<p><i>Mastic cement for glass.</i> Gum mastic 15 parts, bleached -shellac 10, turpentine 5.</p> - -<p>This mass sufficiently diluted with hot oil of turpentine -furnishes an excellent cement for fractured glass and gems. -Being colorless, the joint can scarcely be detected, provided -the cementing has been skilfully done.</p> - -<p>To attach gems to glass of the same color, the cement is -colored with aniline colors dissolved in spirit of wine, care -being had to give it the same shade as the gem and the -glass.</p> - -<p><i>Stick mastic cement.</i> Melt together, at as low a temperature -as possible, 10 parts of mastic and one of turpentine, -and pour the mass into suitable moulds.</p> - -<p>For use, heat the fractured surfaces of the article strongly, -so that the cement on being rubbed over them melts, then -press the surfaces together and continue the pressure until -the cement solidifies.</p> - -<p><i>Sulphur cement for porcelain.</i> White pitch 18 parts, sul<span class="pagenum" id="Page_233">233</span>phur -28, bleached shellac 4, gum mastic 8, elemi 8, glass -meal 28. Melt all together, except the glass meal and stir -the latter into the melted mass.</p> - -<p><i>Insoluble cement for wooden vessels.</i> Melt together 60 parts -of rosin, 20 of asphalt, and 40 of brick dust. Pour the hot -mixture into the joints. This cement resists the action of -lye, quick lime, sulphuric and hydrochloric acids.</p> - - -<h4>RUBBER CEMENTS.</h4> - -<p>These cements are very useful, but owing to the inflammable -nature of the components, great care should be taken -to guard against fire while preparing them. They should -never be made near a naked fire, as the benzine, carbon -disulphide or chloroform used to dissolve the rubber is very -volatile, and the vapor given off permeates the air until, -coming near a source of light, the whole air becomes one -vivid sheet of flame. Vessels which are used should be -closed, and if possible put out of doors. If heat is required -to assist the solvent action, use a sand or hot-water bath, -but on no account bring near a fire.</p> - -<p><i>Cements for glass.</i> I. Rubber 1 part, gum mastic 12, -dammar 4, chloroform 50, benzine 10.</p> - -<p>II. Rubber 12 parts, chloroform 500, gum mastic 120.</p> - -<p>This cement adheres immediately, and possesses a high -degree of elasticity. It may be used to advantage for joining -together the glass panes of hot-houses.</p> - -<p>III. Dissolve, without application of heat, rubber 2 parts -and gum mastic 6, in 100 of chloroform. This cement is -perfectly transparent. It should be applied as quickly as -possible, as it sets in a very short time.</p> - -<p><i>Soft rubber cement.</i> Melt 10 parts of tallow in a brass pan -and gradually add 150 parts of rubber in small pieces, and -stir constantly until all the rubber is dissolved. Keep in -readiness a well-fitting lid to be able to extinguish the -flame immediately in case the rubber catches fire. When -all is melted stir in 10 parts of slaked lime.</p> - -<p><span class="pagenum" id="Page_234">234</span></p> - -<p>This cement is especially adapted for sealing bottles containing -caustic substances, such as nitric acid, etc. It remains -always tenacious, being therefore suitable for cementing -bodies exposed to repeated shocks.</p> - -<p><i>Hard rubber cement.</i> Rubber, 150 parts; tallow, 10; red -lead, 10.</p> - -<p>This cement is prepared in the same manner as the above. -The addition of red lead gives it a red color, and solidifies -it in a short time to a mass as hard as stone.</p> - -<p><i>Elastic cement.</i> Carbon disulphide, 8 ozs.; fine rubber, -1 oz.; isinglass, 4 drachms; gutta-percha, 1 oz. Dissolve -the solids in the fluid.</p> - -<p>This cement is used for cementing leather and rubber. -For use the leather is roughened and a thin coat of the -cement applied and allowed to dry completely; then the -two surfaces to be joined are warmed and placed together -and allowed to dry.</p> - -<p><i>Marine glue.</i> This cement, which is only a glue in name, -is water-proof, and can be used to cement metal, wood, glass, -stone, pasteboard, etc., and is especially adapted for caulking -vessels.</p> - -<p>Suspend 10 parts of rubber inclosed in a bag in a vessel -containing 120 parts of refined petroleum, so that only half -of the bag is immersed, and allow it to remain ten to fourteen -days in a warm place. Then melt 20 parts of asphalt -in an iron boiler and add the rubber solution in a thin jet, -and heat the mixture, while constantly stirring, until it is -perfectly homogeneous. Pour it into greased metallic -moulds, where it forms into dark-brown or black plates -difficult to break. In using it, it should be melted in a -kettle placed in boiling water to prevent its burning, which -it is very apt to do, as it is a bad conductor of heat. After -it has been liquefied remove the kettle from the water and -place it over a fire, where it can be heated, if necessary, to -make it more fluid, to 302° F., carefully stirring it to prevent -burning.</p> - -<p><span class="pagenum" id="Page_235">235</span></p> - -<p>If possible, the surfaces to be glued together should be -heated to 212° F., as the glue can then be slowly applied. -The thinner the layer of glue in cementing together smooth -surfaces, the better will it adhere. But a somewhat thicker -layer is required for rough surfaces, for instance, boards not -planed, the excess of glue being forced out by strong pressure. -Generally speaking, it is best to subject all articles -cemented together with marine glue to as strong a pressure -as possible until the glue is congealed.</p> - -<p>Repeated experiments have shown that with the aid of -this cement square vats perfectly water-tight can be constructed -of boards. Wooden pegs dipped in the compound -should be used for putting the vats together.</p> - -<p><i>Jeffrey’s marine glue.</i> Dissolve 1 part of rubber in benzine, -and mix the solution with 2 parts of shellac by the -assistance of heat.</p> - -<p><i>Another formula</i> is as follows: Coal naphtha 1 quart, -rubber cut in shreds 2 ozs. Macerate for 10 or 12 days and -then rub smooth with a spatula on a slab; add 2 parts by -weight of shellac to 1 part of this solution. To use the -compound melt it at about 240° F.</p> - -<p><i>Marine glue for damp walls.</i> Rubber 10 parts, whiting -10, oil of turpentine 20, carbon disulphide 10, rosin 5 and -asphalt 5. Dissolve the ingredients in a suitable vessel and -stand in a warm place, shaking it frequently.</p> - -<p>Scrape the wall smooth and clean, and apply the glue -with a broad brush on the damp place and about 8 inches -higher than the line of dampness. Before the glue is dry -lay on plain paper which will adhere tightly. On this -plain paper the wall paper can be pasted in the usual manner. -If carefully done, the wall paper will always remain -dry.</p> - - -<h4>GUTTA-PERCHA CEMENTS.</h4> - -<p><i>Cement for leather.</i> Gutta-percha 100 parts, pitch or -asphalt 100, oil of turpentine 15.</p> - -<p>This cement should be used hot. It is suitable for<span class="pagenum" id="Page_236">236</span> -cementing all kinds of substances, but adheres particularly -well to leather.</p> - -<p><i>Cement for hard rubber combs.</i> <i>A.</i> Prepare a very thick -solution of bleached gutta-percha in bisulphide of carbon.</p> - -<p><i>B.</i> Dissolve sulphur in bisulphide of carbon.</p> - -<p>The cementing is effected by applying solution <i>A</i> to the -fractured surfaces and pressing them together. When dry -brush solution <i>B</i> over the cemented place.</p> - -<p><i>Elastic gutta-percha cement.</i> Dissolve 10 parts of gutta-percha -in 100 of benzine, then pour the clear solution into -a bottle containing 100 parts of linseed-oil varnish and -unite both by shaking. This cement excels in elasticity, -and is especially suitable for attaching the soles of shoes, as -it is so elastic that it will not break, no matter how much it -is bent. To make it adhere tightly roughen the leather on -the side to be cemented.</p> - -<p><i>Cement for horses’ hoofs.</i> For filling cracks and fissures -in horses’ hoofs a cement is required which possesses great -resistance to the action of water combined with elasticity -and solidity. A mass answering all demands consists of 10 -parts by weight of gum ammoniac and 20 to 25 of purified -gutta-percha. Heat the gutta-percha to between 194° and -212° F., and then work it with the finely powdered gum -ammoniac to a homogeneous mass. In using it, soften the -cement by heating, and after carefully cleansing the crack -in the hoof, apply it with a heated knife. The cement -solidifies immediately after cooling to the ordinary temperature, -and becomes soon so hard as to allow of nails being -driven into it.</p> - -<p><i>Cement for crockery.</i> Gutta-percha 1 part, shellac 1.</p> - -<p>Place the two ingredients in an earthenware jar, and -melt the two together by standing this jar on a vessel of -boiling water, or else one filled with hot sand, the vessel -holding the water or sand being heated over a fire or gas -furnace. Stir the melted ingredients well together. The -resulting cement is one possessing great hardness and<span class="pagenum" id="Page_237">237</span> -toughness, which suits it admirably for mending crockery. -Warm the edges to be joined together, smear the cement on, -join together, and hold the article thus joined until cool.</p> - -<p><i>Cement for leather.</i> Mix 10 parts of carbon disulphide -with 1 part of turpentine, and then add sufficient gutta percha -to make a tough, thickly-fluid mass. Before using -this cement, free the surface to be joined from grease. To -effect this, sprinkle a little bicarbonate of soda, carbonate of -ammonia or borax on the surfaces to be joined, lay a cloth -over them, and then place a hot iron on top, and keep it -there a short time so as to cause the alkali to cut the grease, -then put the cement on both surfaces to be joined, put them -together and subject to pressure until they are cemented.</p> - -<p>Gutta percha dissolved in carbon disulphide to the consistency -of syrup is also a good cement for joining leather. -The parts to be joined should be well covered with cement -so as to fill the pores of the leather, then the cement is -heated and the parts hammered until the cement is cold.</p> - - -<h4>CASEINE CEMENTS.</h4> - -<p><i>Preparation of pure caseine.</i> Although the caseine contained -in old cheese can be used, the other constituents, -such as fat, salt, and free acid, exert an injurious influence -upon the solidity of the cement prepared with it. It is, -therefore, best to prepare pure caseine, which is easily -accomplished in the following manner:</p> - -<p>Put milk in a cool place, and after taking off the cream -as long as any is formed, remove the skimmed milk to a -warm place to coagulate. After heating the curd, place it -upon a filter and wash the caseine remaining upon the -filter with rainwater until the water running off shows no -trace of acid.</p> - -<p>To remove the last traces of fat tie the washed caseine in -a cloth and after boiling it in water, spread it upon blotting -paper in a warm place to dry. It will shrivel up to a -horny mass.</p> - -<p><span class="pagenum" id="Page_238">238</span></p> - -<p>When thoroughly dried pure caseine will keep for a long -time without suffering alteration. To obtain the caseine in -a form suitable for preparing cements it is only necessary -to pour water over a corresponding quantity and allow it -to stand for some time. Caseine combines with lime to a -hard insoluble mass.</p> - -<p>Ordinary technical caseine may be readily and cheaply -prepared as follows: Skim milk is heated in a copper boiler, -if necessary by the introduction of steam, to 122° F. Then -add for every 1000 quarts of milk, 3 quarts of crude hydrochloric -acid diluted with 5 to 6 times the quantity of water. -After coagulation, the whey is drained off, the curd spread -out upon an inclined table and allowed to cool. The curd -is then washed by pouring cold water over it through a -rose, or stirring it up with water in a barrel, allowing to -settle, and pouring off the supernatant water. The residue -is subjected to moderate pressure. The caseine while still -moist is comminuted in a curd-mill and packed in bags. -In this state it must be worked at once, as otherwise it -spoils readily and is attacked by worms. If it is to be kept -for a longer time, it has to be dried. This is effected by -spreading it out upon linen cloths and placing it in a drying -chamber.</p> - -<p>In this manner 8.5 per cent. of moist, or 3.5 per cent. of -dry, caseine is obtained which is brought into commerce as -technical caseine or lactarine. It being insoluble in water, -10 per cent. of an alkali—soda, borax, or ammonia—has to -be added to effect solution. Water-soluble caseine is seldom -found in commerce, the consumer preparing it, as a rule, -himself.</p> - -<p>A purer technical caseine is obtained according to John -A. Just’s method as follows: Dissolve, stirring constantly, -in 115 quarts of water heated to between 104° and 131° F., -17 to 26 ozs. of bicarbonate of soda and 176 lbs. of moist, or -118 lbs. of dry, caseine, and dry the solution upon a heated -revolving metal cylinder. After each revolution of the<span class="pagenum" id="Page_239">239</span> -cylinder, the dry material is scraped off with brushes and -by being forced through a fine-meshed sieve yields soluble -caseine powder.</p> - -<p><i>Caseine cement which can be kept for a long time.</i> Convert -into powder, each by itself, 200 parts of caseine, 40 of -burned lime, and 1 of camphor. Mix the powders intimately -and keep the mixture in an air-tight bottle. For -use, mix some of the powder with the requisite quantity -of water and use the cement at once.</p> - -<p><i>Cement for glass.</i> Old dry cheese 100 parts, water 50, -slaked lime 20.</p> - -<p>Free the cheese from rind, and rub it with the water -until a homogeneous mass drawing threads is formed. -Then stir in quickly the lime powder, and use the cement -at once. It unites not only glass to glass, but can also be -used for cementing metal to glass.</p> - -<p><i>Cement for metals.</i> Elutriated quartz sand, 10 parts; -caseine, 8; slaked lime, 10, and sufficient water to form a -cream-like mass.</p> - -<p><i>Cement for porcelain.</i> Caseine dissolves readily in solution -of water-glass, and forms then one of the best cements -for porcelain known. To prepare it, fill a bottle one-quarter -full with fresh caseine, and after filling the bottle -with solution of water-glass, effect the solution of the caseine -by frequent shaking.</p> - -<p><i>Cement for meerschaum.</i> Dissolve caseine in water-glass, -and after stirring quickly finely-pulverized calcined magnesia -into the mass, use it at once, as it solidifies very soon. -By adding, besides magnesia, genuine meerschaum finely -pulverized, a mass closely resembling meerschaum is obtained, -which can be used for manufacturing imitation -meerschaum.</p> - -<p><i>Cement for wood, etc.</i> Rub 10 parts of caseine and 5 of -borax to a thick, milky mass, and use it like glue. This -cement can be advantageously used for pasting labels upon -wine bottles, as it neither moulds nor becomes detached in -the cellar.</p> - -<p><span class="pagenum" id="Page_240">240</span></p> - -<p><i>Another formula</i> is as follows: Dissolve borax by boiling -in water, and pour the solution over fresh caseine. The -result will be a clear, thick mass of extraordinary power of -adhesion, which can be kept for any length of time without -suffering decomposition.</p> - -<p>Applied to leather, paper, linen or cotton goods, it forms -a coat of beautiful lustre, and for this reason is much used -in the manufacture of fancy articles of paper and leather.</p> - -<p><i>Cement for porcelain.</i> Dissolve 10 parts of caseine in 60 -of water-glass solution. Apply the cement quickly and dry -the cemented articles in the air.</p> - - -<h4>WATER-GLASS AND WATER-GLASS CEMENTS.</h4> - -<p><i>Water-glass.</i> Water-glass (silicate of soda or soluble -glass) is found in commerce as a thickly-fluid, tenacious -mass. It is generally prepared by fusing 15 parts of quartz -sand with 8 of carbonate of soda and 1 of charcoal. The -silicic acid combining with the soda disengages the carbonic -acid, the expulsion of which is facilitated by the presence -of charcoal, which converts it into carbonic oxide. It -dissolves readily in water. The solution has a strongly -alkaline taste, and possesses the property of being gradually -converted, on exposure to the air, to a gelatinous mass -which finally solidifies. For this reason water-glass should -be kept in bottles hermetically closed with corks. Glass -stoppers are of no use, as they are so firmly cemented to the -bottle that on attempting to open the latter the neck breaks -off.</p> - -<p>By combining water-glass with cement or burned lime -the resulting mass solidifies quite rapidly to a mass as hard -as stone, and generally capable of resisting chemical action.</p> - -<p>Water-glass by itself is only fit for cementing glass to -glass, but combined with other substances it furnishes very -durable and solid cements.</p> - -<p><i>Cement for cracked bottles.</i> Select a cork which will fit the -bottle air-tight and place it loosely upon the bottle, and heat<span class="pagenum" id="Page_241">241</span> -the latter gradually to at least 212° F. Then press the -cork down and apply a thick solution of water-glass to the -cracks. In cooling, the air in the bottle contracts strongly, -and the pressure of the exterior air drives the water-glass -with great force into the cracks closing them entirely so -that they cannot be detected.</p> - -<p><i>Cement for glass and porcelain.</i> Stir quickly together 10 -parts of elutriated glass meal, 20 of powdered fluor spar, -and 60 of water-glass solution, and apply the homogeneous -paste at once. In a few days the cement will be so hard -that the cemented vessels can be heated without danger.</p> - -<p><i>Cement for hydraulic works.</i> Finely powdered cement, and -solution of water-glass. Mix the two bodies quickly together.</p> - -<p>As this cement hardens very quickly, it should be used -fresh. It hardens under water, and is therefore excellent -for hydraulic works. The stones should be coated with -a solution of water-glass before applying the cement.</p> - -<p><i>Cement for uniting metals.</i> A strong cement, which -hardens rapidly, is made by stirring the finest whiting in a -solution of soda-glass of 33° B., made so as to form a plastic -mass. This can be readily colored to any desired shade. -The addition of sifted sulphide of antimony gives a black -cement, which by polishing acquires a metallic lustre; iron -filings render it grayish-black; zinc dust turns it green, but -after polishing, it appears like metallic zinc, and may be -employed for the permanent repair of zinc ornaments, etc. -Carbonate of copper imparts a light green shade. Other -additions may be made, as oxide of chrome for dark green, -cobalt blue for blue, red lead for orange, vermilion for -scarlet, carmine for violet, etc.</p> - -<p><i>Cement for tightening joints of pipes exposed to a red heat.</i> -Mix 80 parts of pyrolusite, 100 of zinc white, and 20 of -water-glass.</p> - -<p>This cement fuses at a temperature not too high, and -then forms a glass-like mass which adheres very firmly and -closely.</p> - -<p><span class="pagenum" id="Page_242">242</span></p> - -<p><i>Cement for marble and alabaster.</i> The point of fracture of -articles cemented with the following mixture is difficult to -find, and the cemented place is much stronger than the -material itself. Mix 12 parts of Portland cement, 6 of -slaked lime, 6 of fine sand, and 1 of infusorial earth with -sufficient water-glass to form a thick paste. The article to -be cemented need not be heated. It hardens in twenty-four -hours.</p> - - -<h4>GLYCERINE AND GLYCERINE CEMENTS.</h4> - -<p>Commercial glycerine is a yellowish or nearly colorless -and more or less viscid liquid having an intensely sweet -taste. In combination with lead oxide and intimately -worked into it, by heating and stamping, it furnishes very -strong and durable cements deserving general introduction, -though thus far they have been but little used.</p> - -<p>For the manufacture of cements the use of pure odorless -glycerine is not required, the yellow crude article, which is -much cheaper, answering all purposes. The principal -point is to use very highly concentrated glycerine, as otherwise -the cements prepared with it solidify very slowly and -besides do not possess a proper degree of hardness and -solidity.</p> - -<p>It is of especial importance to have the lead oxide free -from water. To accomplish this, heat it thoroughly and -mix it with the glycerine while still hot. Cement thus -prepared solidifies very quickly, and can be used for many -purposes. It is an excellent material for quickly joining -the stones of submarine works.</p> - -<p><i>Glycerine and litharge cement.</i> Moisten elutriated litharge -with glycerine so that a thin homogeneous paste is -formed. This cement is adapted for uniting the joints of -steam pipes, cementing wood, glass, porcelain, and also -glass upon metal, etc. It solidifies to a very hard mass in -a quarter to three-quarters of an hour. Before applying -the cement coat the surfaces to be joined with pure -glycerine.</p> - -<p><span class="pagenum" id="Page_243">243</span></p> - - -<h4>LIME CEMENTS.</h4> - -<p>Quick lime, slaked lime and chalk are used for this purpose. -Quick lime, which is obtained by burning limestone, -combines gradually with the fats to insoluble lime soaps. -Slaked lime, which consists of a combination of lime with -water, acts in the same manner.</p> - -<p>For the preparation of cements the lime is slaked by -placing it in a dish and pouring as much water over it as -it will absorb. Good lime, technically called <i>fat lime</i>, -should eagerly combine with water, evolving much heat, -swelling greatly, and crumbling to a light white powder.</p> - -<p>Quick lime exposed to the air until, by the absorption of -moisture and carbonic acid, it is converted into a powder is -called <i>air-slaked</i>.</p> - -<p>Cements prepared with quick lime will, as a rule, solidify -more quickly than those prepared with air-slaked lime.</p> - -<p>Chalk is a carbonate of lime consisting of the shells of -microscopic animals, and can be readily pulverized and -elutriated. In the latter state it is known as <i>whiting</i>. For -the preparation of entirely white cements the use of pure -white lime or chalk is absolutely necessary. Yellow or -reddish lime contains oxide of iron, and furnishes cements -of the same tinge.</p> - -<p><i>Cement for glass.</i> Litharge 30 parts, quick lime 20, linseed-oil -varnish 5.</p> - -<p><i>Cement for joiners.</i> A cement for filling up cracks and -holes is obtained by mixing slaked lime 50 parts, flour 100, -linseed-oil varnish 15.</p> - -<p><i>Cement for cracked clay crucibles and porcelain.</i> By applying -to the cracks a mixture of 10 parts of slaked lime, 10 -of borax, and 5 of litharge in sufficient water to form a stiff -paste, and drying after heating the crucible, the cracked -places will be united so firmly that the crucible, when -thrown to the ground, will generally break in any other -place than the cemented one.</p> - -<p><span class="pagenum" id="Page_244">244</span></p> - -<p>This cement can also be used for porcelain capable of -standing a strong heat.</p> - -<p><i>Lime and glue cement.</i> Stir air-slaked lime into hot glue. -This cement is especially suitable for attaching metal to -glass. It forms a very hard yellowish-brown mass.</p> - - -<h4>GYPSUM CEMENTS.</h4> - -<p>Sulphate of lime in combination with water is met with -in nature, both in the form of transparent prisms of <i>selenite</i>, -and in opaque and semi-opaque masses, known as <i>alabaster</i> -and <i>gypsum</i>. By pulverizing the latter and heating to -about 302° F. it loses its water, and is converted into -anhydrous gypsum or <i>plaster of Paris</i>, which on mixing -with water recombines with it to form a mass of hydrated -sulphate of lime, the hardness of which nearly equals that -of the original gypsum. When the powder is mixed with -water to a cream and poured into a mould, the minute particles -of anhydrous sulphate of lime combine with the -water to reproduce the original gypsum, and this act of -combination is attended with a slight expansion which -forces the plaster into the finest lines of the mould.</p> - -<p>By using a solution of alum instead of ordinary water, a -plaster is obtained which, although it takes much longer to -set than the ordinary kind, is much harder, and therefore -takes a good polish.</p> - -<p>For preparing cements only perfectly white plaster of -Paris should be used, as the gray article possesses but little -adhesive power.</p> - -<p><i>Cement for plaster of Paris statues.</i> To repair plaster of -Paris statues so that the point of fracture cannot be detected, -proceed in the following manner:</p> - -<p>Moisten the fractured surfaces with water by means of a -brush until they absorb no more and remain moist. Mix -plaster of Paris with water to a thin cream and stir until -the heat appearing at first has ceased, which will prevent -the conversion of the plaster into a solid coherent mass.<span class="pagenum" id="Page_245">245</span> -Apply quickly a thin layer of the plaster to one of the fractured -surfaces, press the other against it until the plaster -has set, and, when dry, carefully remove the excess by -scraping.</p> - -<p><i>Cement for glass and porcelain.</i> Mix quickly 50 parts of -plaster of Paris, 10 of quick lime, and 20 of white of egg. -Use at once, as the cement solidifies very rapidly.</p> - -<p><i>Cement for iron and stone.</i> A very useful cement for -securing iron railing in stone is obtained by mixing 30 -parts of plaster of Paris, 10 of iron filings and 20 of vinegar.</p> - -<p><i>Cements for porcelain.</i> I. Mix plaster of Paris with saturated -solution of alum to a cream. After moistening the -fractured surfaces apply a thin layer of the cement, press -the surfaces together, wrap a wire or cord tightly around -them, and let the article stand quietly for a few weeks. -The cement is converted into a mass as hard as stone.</p> - -<p>II. Mix plaster of Paris with a thick, clear solution of -gum arabic and cement the articles as soon as possible. -Although this cement adheres very tightly, porcelain vessels -cemented with it cannot be used for liquids.</p> - -<p><i>Universal plaster of Paris cement.</i> Mix 21 parts of plaster -of Paris, 3 of iron filings, 10 of water, and 4 of white of -egg. This cement is suitable for attaching metal to glass, -metal to stone, etc.</p> - - -<h4>IRON CEMENTS.</h4> - -<p><i>Heat-resisting cement.</i> Clay 10 parts, iron filings 5, vinegar -2, water 3.</p> - -<p><i>Water and steam-proof cement.</i> Iron filings 100 parts, sal-ammoniac -2, water 10.</p> - -<p>This cement rusts very much in a few days, and is converted -into an extremely solid mass which is perfectly -steam- and water-proof.</p> - -<p><i>Cement for iron.</i> Mix 65 parts of wrought-iron filings, -2.5 of sal ammoniac, and 1.5 of flowers of sulphur, and then -add 1 part of sulphuric acid diluted with sufficient water to<span class="pagenum" id="Page_246">246</span> -form a stiff paste. This cement solidifies in two to three -days, and rusts, with the parts of iron to be cemented, to an -extraordinarily durable mass.</p> - -<p><i>Fire-proof cement for iron pipes.</i> Wrought-iron filings 45 -parts, clay 20, fire-clay 15, common salt solution 8.</p> - -<p><i>Cements resisting high temperatures.</i> 1. Iron filings 20 -parts, clay powder 45, borax 5, common salt 5, pyrolusite -10.</p> - -<p>Dissolve the borax and common salt in the water, add -and mix quickly the clay powder, pyrolusite, and iron -filings. Apply the cement at once. Exposed to a white -heat, it hardens to a tightly adhering, glassy mass.</p> - -<p>2. Mix 52 parts of pyrolusite, 25 of zinc white, and 5 of -borax with solution of water-glass to a paste, and use at -once. This cement requires to be gradually dried. It will -stand the highest temperatures.</p> - -<p><i>Cement for filling in defects in castings.</i> Stir 100 parts of -iron filings free from rust with sufficient water to form a -thick paste, and press the mixture into the fissures, cracks, -etc. The cement becomes solid only after the iron filings -become strongly rusted. To free the ingredients from -adhering fat, wash them, before mixing, in liquid ammonia.</p> - -<p><i>Cement for cracked stove plates, etc.</i> Knead 20 parts of iron -filings, 12 of iron scale, 30 of plaster of Paris, and 10 of -common salt with blood to a stiff paste, and use at once. -Instead of blood, water-glass can be used, it having the advantage -of being odorless on strong heating, while blood -cement evolves a disagreeable odor.</p> - -<p><i>Cement for iron water tanks.</i> Knead iron filings with -vinegar to paste. Allow the mixture to stand until it turns -brown, and then force it into the joints by means of a -chisel.</p> - -<p><i>Cement for cracked iron pots.</i> Knead 10 parts of iron -filings and 60 of clay with linseed oil to a thick paste. -Before applying it add a little linseed oil, and allow it to -dry slowly. In a few weeks the cement will be so hard -that the vessels can be used without danger.</p> - -<p><span class="pagenum" id="Page_247">247</span></p> - -<p><i>Black cement for stoves.</i> Iron filings 10 parts, sand 12, -bone black 10, slaked lime 12, glue water 5.</p> - -<p><i>Cements for iron stoves.</i> 1. Pulverize as finely as possible -and mix intimately 4 to 5 parts of clay, 2 of iron filings -free from rust, 1 of pyrolusite, ½ of common salt, and ½ of -borax with water to a paste, and apply the cement quickly -to the places to be cemented and allow it to dry slowly. -This cement will stand a white heat, and resist the action -of boiling water.</p> - -<p>2. Mix intimately and as quickly as possible 1 part of -pulverized pyrolusite, and 1 of zinc white with solution of -water-glass to a plastic mass, which solidifies quickly. The -power of resistance of this cement, it is claimed, is not inferior -to No. 1, though experiments have proved No. 1 to -be preferable.</p> - - -<h4>CEMENTS FOR CHEMICAL APPARATUS.</h4> - -<p>Cements to be used for the above purpose must possess -various properties difficult to combine in one preparation. -They must be gas-proof, and capable of resisting the action -of different vapors and acid fluids. As regards resistance -to the action of chemical agents, there is nothing better -than caoutchouc, but unfortunately it can only be used for -tightening chemical apparatus not exposed to a high temperature.</p> - -<p>In chemical laboratories bran of almonds, either by itself -or kneaded with water to a thick paste, is frequently used, -or rye or wheat bran mixed with a little flour and water. -These cements, though very suitable for cementing glass -distilling apparatus, are strongly acted upon by chlorine -and the vapors of nitric acid.</p> - -<p>For small apparatus to be used for the development of -fluoric acid, plaster of Paris mixed with a little water can -be used as a cement. To make the joint entirely gas-tight, -paste a strip of paper over it. Although this cement does -not resist the action of fluoric acid for any length of time, it<span class="pagenum" id="Page_248">248</span> -suffices generally for the protection of the Workmen during -the time the development of the acid is in progress, as, for -instance, in chemical analyses, etc.</p> - -<p>To cement chemical apparatus exposed to a temperature -not exceeding 86° to 104° F. paraffine does excellent service; -as it possesses the power of resisting the action of the -strongest acids and alkalies.</p> - -<p>Below will be found a few receipts for cements which -have proved reliable.</p> - -<p><i>Linseed oil and clay cement.</i> Knead 10 parts of dry clay -with 1 of linseed oil to a homogeneous mass. This cement -will stand heating to the boiling-point of mercury.</p> - -<p><i>Linseed oil, zinc and manganese cement.</i> Knead 10 parts -of pyrolusite, 20 of zinc white, and 40 of clay with sufficient -boiled linseed oil (not exceeding 7 parts) to a plastic -mass. This cement will stand a somewhat higher temperature -than the preceding one.</p> - -<p><i>Cements resisting very high temperatures.</i> I. Clay 100 -parts, powdered glass 2.</p> - -<p>The glass melts on exposure to great heat and slags the -clay to a hard mass. The same effect is produced by adding -small quantities of soda and borax to the clay. An -admixture of chalk and boric acid, as in the following receipt, -also gives excellent results.</p> - -<p>II. Clay 100 parts, chalk 2, boric acid 3.</p> - -<p><i>Cement resisting acids.</i> Melt rubber with double the -quantity of linseed oil, and then knead in sufficient bole to -form a paste. This cement resists the action of nitric and -hydrochloric acids, and can be advantageously used for -closing bottles containing them. As it solidifies very -slowly, it can readily be detached from the bottles, and -used again.</p> - -<p>For cement which is to solidify quickly on exposure to -the air, add a few per cent. by weight of red lead or -litharge.</p> - -<p><i>Rubber cement for chemical apparatus.</i> Cut 8 parts of rub<span class="pagenum" id="Page_249">249</span>ber -in small pieces and throw them gradually into a mixture -of 2 parts of tallow and 16 of linseed oil previously -strongly heated. After effecting an intimate mixture of -the constituents by vigorous and constant stirring, add 3 -parts of white bole.</p> - -<p>Although this cement does not stand a high temperature, -it possesses an extraordinary power of resisting the action -of acid vapors.</p> - -<p><i>Scheibler’s cement for chemical apparatus.</i> Melt together 1 -part of wax and 3 of shellac, and work into the mixture 2 -parts of gutta-percha cut up in very small pieces. This -cement will bear considerable heat without actually melting.</p> - - -<h4>CEMENTS FOR SPECIAL PURPOSES.</h4> - -<p><i>Cement for attaching metal letters to glass, marble, wood, etc.</i> -Dissolve over a water-bath 5 parts of glue in a mixture of -15 parts of copal varnish, 5 parts of boiled linseed oil, 3 -parts of crude oil of turpentine, and 2 parts of rectified oil -of turpentine, and add 10 parts of slaked lime to the -mixture.</p> - -<p><i>Cement for joints of iron pipes.</i> Mix 5 lbs. of coarsely -powdered iron borings, 2 ozs. of powdered sal ammoniac, -and 1 oz. of sulphur with sufficient water to form a paste. -This composition hardens rapidly, but if time can be -allowed it sets more firmly without the sulphur. It must -be used as soon as mixed, and rammed tightly into the -joint.</p> - -<p>Another receipt is as follows:</p> - -<p>Mix 2 ozs. of sal ammoniac, 1 oz. of sublimated sulphur -and 1 lb. of cast-iron filings or fine turnings in a mortar, -and keep the powder dry. When it is to be used, mix it -with 20 times its weight of clean iron turnings or filings -and grind the whole in a mortar; then wet it with water -until it becomes of convenient consistency, when it is to be -applied to the joint. After a time it becomes as hard and -strong as the metal.</p> - -<p><span class="pagenum" id="Page_250">250</span></p> - -<p><i>Steam boiler cement.</i> Mix 10 parts of finely-powdered -litharge with 1 part of fine sand and 1 part of air-slaked -lime. The mixture may be kept for any length of time -without deterioration. For use a portion of it is made into -a paste with linseed oil or, better, boiled linseed oil. In -this state it must be applied quickly, as it soon becomes -hard.</p> - -<p><i>Cement for rubber.</i> Powdered shellac is softened in 10 -times its weight of strong water of ammonia, whereby a -transparent mass is obtained, which becomes fluid after -keeping some little time without the use of hot water. In -three to four weeks the mixture is perfectly liquid, and -when applied it will be found to soften the rubber. As -soon as the ammonia evaporates it hardens again, and thus -becomes impervious both to gases and to liquids. For -cementing sheet rubber, or rubber material in any shape, -to metal, glass, and other smooth surfaces, this cement is -highly recommended.</p> - -<p><i>Cement for tires.</i> 1. Isinglass 1 oz., gutta-percha 1 oz., -rubber 2 ozs., carbon disulphide 8 fluid ozs. Mix and dissolve.</p> - -<p>2. Shellac 4 ozs., gutta-percha 4 ozs., red lead and sulphur, -each ½ oz. Melt the shellac and gutta-percha, and -add with constant stirring the red lead and sulphur, melted. -Use while hot.</p> - -<p>3. Crude rubber 1 oz., carbon disulphide 8 ozs. Macerate -24 hours, and then add a solution of:</p> - -<p>Rosin 2 ozs., beeswax ½ oz., carbon disulphide 8 ozs.</p> - -<p>4. Rubber 20 parts, rosin 10, Venetian red 10, tallow -5. Melt the rubber over a fire, then add the rosin and the -tallow and finally the Venetian red.</p> - -<p><i>Cement for steam pipes, etc.</i> A cement of specially valuable -properties for steam pipes, in filling up small leaks, -such as a blow-hole in a casting, without the necessity of -removing the injured piece, is composed of 5 lbs. Paris -white and 5 lbs. yellow ochre, 10 lbs. litharge, 5 lbs. red<span class="pagenum" id="Page_251">251</span> -lead and 4 lbs. black oxide of manganese. Mix the materials -thoroughly and make into a paste with a small quantity -of asbestos and boiled linseed oil. The composition, as -thus prepared, will harden in from 2 to 5 hours, and has -the advantage of not being subject to expansion and contraction -to such an extent as to cause a leakage afterwards, -and its efficiency in places difficult of access is of special -importance.</p> - -<p><i>Cement for marble.</i> Stir to a thick batter with silicate of -soda 12 parts of Portland cement, 6 of slaked lime, 6 of fine -white lead and 1 of infusorial earth. This is excellent for -marble and alabaster. The cemented objects need to be -heated. After 24 hours the fracture is firm, and the place -can scarcely be found.</p> - -<p><i>Cement for attaching wood, glass, etc., to metal.</i> Acetate of -lead 23 parts by weight, alum 23, gum arabic 38, wheat -flour 250.</p> - -<p>Dissolve the acetate of lead and the alum in a little -water and separately dissolve the gum arabic in a fair -quantity of boiling water. Thus if the 250 parts of wheat -flour represent half a pound, the quantity of water needed -will be about a pint. The gum having dissolved, add the -flour, put the whole on the fire, stir well with a wooden -stick, then add the solution of lead acetate and alum. Continue -the stirring in order to avoid the formation of lumps, -then take it off the fire without allowing it to boil. This -cement is used cold, and will not scale. It is very useful -in making wood, glass, cardboard, etc., adhere to metal, -and is extremely strong.</p> - -<p><i>Brushmakers’ cement.</i> Rosin 5 lbs., rosin oil or spirit 1 -quart.</p> - -<p>Reduce the rosin to small pieces, run down in a pot, add -the other ingredient, and stir until mixed and syrupy, then -run out into tins. It is used for cementing the bristles in -the stocks, also for string binding on sash tools, etc.</p> - -<p><i>Cement for electrical apparatus.</i> Mix together 1 lb. of<span class="pagenum" id="Page_252">252</span> -beeswax added to 5 lbs. of rosin, 1 lb. of red ochre, and 2 -tablespoonfuls of plaster of Paris. It will make an excellent -composition for electrical apparatus.</p> - -<p>A cheaper composition for cementing voltaic plates into -wooden troughs is made with 6 lbs. of plaster of Paris and -¼ pint of linseed oil. The ochre and the plaster of Paris -should be well dried and added to the other ingredients -when these are in a melted state.</p> - -<p><i>Jewelers’ cement.</i> Dissolve over the water-bath 25 parts -of fish glue in a small quantity of strong spirits of wine, -add 2 parts of gum ammoniac; separately dissolve 1 part -of mastic in 5 of spirits of wine. Mix the two solutions -and keep them in well-stoppered bottles.</p> - -<p><i>American cement for jewelers.</i> Soak 4 ozs. of isinglass in -2 lbs. of water for 24 hours, then evaporate in the water-bath; -to 1 lb. add 1 lb. of rectified spirits of wine, and -strain. Then mix in a solution of 2 ozs. of mastic and 1 -oz. of gum ammoniac in 16 ozs. of rectified spirit.</p> - -<p><i>Cement for celluloid.</i> Shellac 2 ozs., spirits of camphor 2, -90 per cent. alcohol 6 to 8.</p> - -<p><i>Stratena.</i> This well-known household cement is said to -be prepared as follows: Dissolve 12 parts of white glue in -16 of acetic acid, and then add this solution to one of 2 -parts gelatine in 16 of water. After mixing add 2 parts -shellac varnish.</p> - -<p><i>Cement for cloth.</i> Gutta-percha 16 parts, rubber 4, pitch -2, shellac 1, linseed oil 2 pints. Dissolve the whole by -heat, stirring constantly.</p> - - -<h4>HOW TO USE CEMENTS.</h4> - -<p>It is unquestionably true that quite as much depends -upon the manner in which a cement is applied, as upon the -cement itself. The best cement that was ever compounded -would prove entirely worthless improperly applied. In -the foregoing a number of cements have been given which -answer every reasonable demand when properly prepared<span class="pagenum" id="Page_253">253</span> -and properly used. Good common glue will unite two -pieces of wood so firmly that the fibres will part from -each other rather than from the cementing material; two -pieces of glass can be so joined that they will part anywhere -rather than on the line of union; glass can be united -to metal, metal to metal, stone to stone, and all so strongly -that the joint will certainly not be the weakest part of the -resulting mass. What are the rules to be observed in -effecting these results?</p> - -<p>The first point that demands attention is to bring the -cement itself into intimate contact with the surface to be -united. If glue is employed, the surface should be made -so warm that the melted glue will not be chilled before it -has time to effect a thorough adhesion. The same is more -eminently true in regard to cements that are used in a fused -state, such as mixtures of resins, shellac, and similar -materials. These matters will not adhere to any substance -unless the latter has been heated to nearly or quite the -fusing point of the cement used. This fact was quite -familiar to those who used sealing-wax in the olden days -of seals. When the seal was used, in succession, rapidly so -as to become heated, the sealing-wax stuck to it with a -firmness that was annoying, so much so that the impression -was generally destroyed, from the simple fact that the -sealing-wax would rather part in its own substance than at -the point of adhesion to the seal. Sealing-wax or ordinary -so-called electric cement is a very good agent for uniting -metal to glass or stone, provided the masses to be united -are made so hot as to fuse the cement; but if the cement is -applied to them while they are cold, it will not stick at all. -This fact is well known to those itinerant venders of cement -for uniting earthenware. By heating two pieces of delf so -that they will fuse shellac, they are able to smear them -with a little of this gum and join them so that they will -rather break at any other part than along the line of union. -But although people see the operation constantly performed<span class="pagenum" id="Page_254">254</span> -and buy liberally of the cement, it will be found that in -nine cases out of ten, the cement proves worthless in the -hands of the purchasers, simply because they do not know -how to use it. They are afraid to heat a delicate glass or -porcelain vessel to a sufficient degree, and they are apt to -use too much of the material, and the result is a failure.</p> - -<p>The great obstacles to the junction of any two surfaces -are air and dirt. The former is universally present, while -the latter is due to accident or carelessness. All surfaces -are covered with a thin adhering layer of air, which it is -difficult to remove, and which, although it may at first -sight seem improbable, bears a relation to the outer surface -of most bodies different from that maintained by the air a -few lines away. The reality of the existence of this adhering -layer of air is well known to all who are familiar with -electrotype manipulation. It is also seen in the case of -highly polished metals which may be immersed in water -without becoming wet. Unless this adhering layer of air -is displaced, the cement cannot adhere to the surface to -which it is applied because it cannot come in contact with -it. The most efficient agent in displacing this air is heat. -Metals warmed to a point a little above 203° F. become -instantly and completely wet when immersed in water. -Hence, for cements that are used in a fused condition, heat -is the most efficient means of bringing them in contact with -the surfaces to which they are to be applied. Another very -important point is to use as little cement as possible. -When the surfaces are separated by a large mass of cement -we have to depend upon the strength of the cement itself -and not upon its adhesion to the surfaces which it is used -to join; and, in general, cements are comparatively brittle.</p> - -<p>The cement forced out of the joint by pressing the surfaces -together should be removed while the cement is in a -fused state or liquid. This can generally be effected by -wiping the surplus off, while after solidification a certain -amount of force has to be used which may frequently break -the joint.</p> - -<p><span class="pagenum" id="Page_255">255</span></p> - -<p>Oil cements, which generally solidify slowly, have the -advantage of being water-proof. In cementing with oil -cements, coat the surfaces to be joined with linseed oil, or, -still better, boiled linseed oil, but in working with resinous -cements apply oil of turpentine, spirit of wine, or a fluid -which will readily dissolve the cementing constituent of the -cement.</p> - -<p>For cleansing the surfaces from grease and dirt place the -articles in strong lye and rinse off in clean water without -touching the surfaces with the hands. For painted porcelain -articles which cannot be placed in lye, it is recommended -to brush the surfaces several times with carbon -disulphide.</p> - - -<h4>PASTES AND MUCILAGES.</h4> - -<p><i>Preparation of paste.</i> Ordinary paste is prepared either -from flour or starch, and according to the raw material -used in its preparation, may, therefore, be divided into -starch and flour paste.</p> - -<p>Starch is an indispensable constituent of certain parts of -plants, and plays an important part in the nutrition of the -plant. It is chiefly manufactured from potatoes, Indian -corn and grain. Examined under the microscope, it is -seen to be composed of small granules consisting of layers -placed one above the other.</p> - -<p><i>Starch paste.</i> In stirring starch with water to a thin -paste and gradually heating it, it will be observed that at a -temperature between 140° and 158° F. a peculiar change -takes place; the thin milk-white liquid becomes transparent, -opalizes, and at the same time becomes thickly fluid, -in short, the starch is converted into paste. During this -process the separate layers of the starch granules become -detached somewhat in the same manner as an opening bud, -whereby they absorb water, and the peculiar mass, called -paste, is formed. That paste is not a solution is easily -proved by the fact that on attempting to filter starch-paste<span class="pagenum" id="Page_256">256</span> -only water drains off, while the starch remains upon the -filter and gradually dries to a horny mass.</p> - -<p>Paste left to itself soon decomposes, especially during the -hot season of the year; it becomes sour through the formation -of lactic acid, butyric acid, acetic acid, and other substances, -and loses its adhesive power.</p> - -<p>In preparing paste, the following rules must be especially -observed: Divide the starch in water by constant stirring -so as to form a homogeneous, rather thinly liquid fluid, and -then add boiling water in small portions, stirring constantly. -The conversion of the starch into paste is recognized by the -thickening of the entire mass and the appearance of opalescence, -when it is only necessary to add the required quantity -of water to give the paste the desired consistency.</p> - -<p>If white lumps are observed, it is an indication that the -starch has not been thoroughly mixed with the water, and -that certain portions of it have remained dry. Paste containing -such lumps cannot be applied with any degree of -uniformity, and besides it possesses less adhesive power. -Nothing can be done to remedy the evil except diluting the -paste with a considerable quantity of water and boiling, -with constant stirring, until the mass is perfectly homogenous.</p> - -<p>Starch paste prepared in a proper manner possesses great -adhesive power, and, when applied in a thin layer, dries to -an almost colorless coating. Pure starch paste is used for -many purposes. It serves not only for pasting paper, wall -paper, etc., but also for sizing tissues, such as paper-muslin, -linen, etc., in order to give them lustre, body, and, under -certain circumstances, greater weight. To increase the -weight of linen, white lead or heavy spar is frequently -mixed with the starch.</p> - -<p><i>Flour paste.</i> The principal constituent of flour, besides -starch, is gluten. It is obtained in a pure state by tying -flour in a linen bag and kneading it under water so long -as the latter is rendered turbid by particles of starch. The<span class="pagenum" id="Page_257">257</span> -gluten remaining in the bag is a light-brown, very tenacious -mass, drawing threads between the fingers, and, as regards -its chemical properties, is closely allied to albumen and -caseine. Gluten, like the last-mentioned substances, shows -a tendency to form combinations with lime which gradually -solidify, and it can therefore be used for preparing cements. -Like albumen and caseine, it speedily putrefies if exposed -to the air in a moist state, and in decomposing forms products -which have a very unpleasant odor.</p> - -<p>Flour paste is prepared in precisely the same manner as -starch paste, but while the latter is white, flour paste, even -if prepared from the best wheat flour, has always a yellow-brown -color. As regards adhesive power it is superior to -starch paste, but is less durable.</p> - -<p>There are many means to prevent the spoiling of paste. -With paste once dry and kept so, there is no danger of -spoiling, but if it is alternately exposed to dampness and -dryness, as for instance with wall-paper hung on walls not -entirely dry, decomposition will unavoidably take place, -and the wall paper will become spotted and fall off the wall.</p> - -<p>Provided either starch or flour paste is protected against -drying in, it can be kept unchanged for a long time by the -addition of a small quantity of carbolic acid.</p> - -<p>For hanging wall-paper an addition of alum is, generally -speaking, more suitable than carbolic acid.</p> - -<p>In hanging wall-paper the wall is generally first sized -with glue water. By the alum coming in contact with glue -an insoluble leather-like combination is formed, which not -only resists decomposition, but by far surpasses ordinary -paste as regards adhesive power, so that when the paper is -to be removed from the wall it has to be scraped and torn -off in small pieces, while that hung without previous sizing -of the wall is readily removed in large pieces.</p> - -<p>But alum cannot be used for preserving a glue solution, -as it would cause it to coagulate to a flaky mass. Carbolic -acid is, on the other hand, an excellent means for the pur<span class="pagenum" id="Page_258">258</span>pose, -but to prevent its characteristic empyreumatic odor -from making itself too sensibly felt, no more than about -one two-thousandth of the weight of the glue solution should -be added.</p> - -<p><i>Shoemakers’ paste.</i> In addition to being cheap, no other -paste adheres as well to leather as the so-called shoemakers’ -paste. With it leather can be secured not only to leather, -but also to woven materials, paper, etc. Though its preparation -is very simple, it is connected with some disagreeable -features consisting chiefly in the development of a truly -terrible stench.</p> - -<p>The paste is prepared by stirring crushed barley with -hot water to a thick paste and adding small portions of hot -water, so that the temperature of the mass is kept at between -86° to 104° F. In a few days the mass commences to -develop gas, which shows at first no odor, but soon the -development of gas becomes stronger and an acid odor is -perceptible, which in a short time is replaced by a terrific -stench which, as before mentioned, affects the olfactory -organs in a most unpleasant manner.</p> - -<p>In consequence of the acid and putrid fermentation the -pasty mass gradually loses its granular condition, and is -finally converted into a homogeneous, thickly fluid mass of -a brown color, which draws threads between the fingers, -and possesses great adhesive power. When this is the case, -decomposition, which otherwise would go on until nothing -remained but a watery and acid fluid, is interrupted by -lowering the temperature of the paste by ladling it from the -vat or by adding a small quantity of carbolic acid.</p> - -<p>To render the stench developed during the fermentation -of the paste innoxious, the vat in which it is prepared -should be provided with a well-fitting cover, in which is -fitted a stovepipe passing into a chimney connected with a -kitchen range or furnace, in which a fire is frequently burnt.</p> - -<p>By kneading shoemaker’s paste together with indifferent -substances it can be used as a cement for various purposes.<span class="pagenum" id="Page_259">259</span> -The substances best adapted for the purpose are burnt lime -slaked to a powder, whiting, zinc white, pipe clay, ochre, etc.</p> - -<p><i>Gum arabic.</i> This gum is an exudation from certain -tropical species of acacia, and consists essentially of arabine, -which has the composition C<sub>12</sub>H<sub>11</sub>O<sub>11</sub>. The best gum -arabic is that in the form of very pale-yellow, brittle pieces; -golden-yellow to brownish pieces are not valued as highly, -though they give a solution of considerable adhesive power.</p> - -<p>Gum arabic dissolves in water, but not in alcohol, and -therefore can not be employed for cements in the preparation -of which solutions of resins in spirit of wine are to be -used.</p> - -<p>There are other products of vegetable life, which are also -in commerce, called gums, but dissolve partly in spirit of -wine. To this class belongs the gum ammoniac mentioned -in some receipts for cements. As it is rather expensive, it -is seldom used by itself as a cement.</p> - -<p><i>Dextrine</i> is extensively used in place of gum arabic in -printing wall-papers, for stiffening and glazing cards and -paper, for thickening the colors of calico printers, in making -mucilages, etc. It is prepared by heating starch previously -moistened with nitric acid in an oven, and can also -be produced by heating paste with malt extract or very -dilute sulphuric acid. There is a current anecdote which -attributes the discovery of dextrine to a conflagration at a -starch factory where one of the workmen who assisted in -quenching the fire observed the gummy properties of the -water which had been thrown over the torrefied starch.</p> - -<p>Commercial dextrine forms pale-yellow to dark-brown -masses. These masses dissolve readily in water, and form -solutions which, as regards adhesive power, compare favorably -with those prepared from gum arabic. The mucilage -is prepared by simply stirring the pulverized dextrine with -water to a thickly-fluid liquid.</p> - -<p>To preserve mucilage unchanged for any length of time, -and to prevent the disagreeable formation of mould upon<span class="pagenum" id="Page_260">260</span> -its surface, it is recommended to dissolve some salicylic acid -in the water to be used for preparing the mucilage.</p> - -<p>Dextrine is usually prepared on a large scale by moistening -10 parts of starch with 3 parts of water acidulated with 1/100 -part of nitric acid. The mixture is allowed to dry, and is -then spread upon trays in layers about three-quarters of an -inch deep in an oven, where it is heated for about one hour -to 239° F. Sometimes large drums revolving over a fire -are used, or, in order to keep up a uniform temperature, the -starch is placed in a copper cylinder suspended in a vessel -with oil which is heated to 356° F. The object of the addition -of nitric acid is to allow the starch to be converted -into dextrine at a temperature which would be inadequate -to effect the transformation of starch alone.</p> - -<p>Dextrine is also frequently prepared by allowing germinated -barley or malt to act upon starch. Heat 350 to 400 -parts of water to about 77° F., and after adding 5 to 10 -parts of dry malt, raise the temperature to 140° F. Then -add 100 parts of starch, and after mixing the whole thoroughly -together, raise the temperature to about 158° F. for -twenty minutes. The mass, which appears at first milky -and sticky, will gradually become as liquid as water by the -conversion of the starch into gum through the action of the -malt. To prevent the conversion of the gum into sugar by -the diastase of the malt, the fluid must be quickly brought -to the boiling-point, and, after cooling, filtered and evaporated -to the consistency of syrup. In cooling, the mass gelatinizes -to a jelly, which after drying is hard and brittle.</p> - -<p>According to Blumenthal’s method, a drum which can -be hermetically closed, is filled two-thirds full with dry -starch flour by means of a funnel. A stirring apparatus is -then set in motion, and the acid which is contained in a -graduated cylinder is sprayed into the drum by means of a -special contrivance.</p> - -<p>In a drum 5 feet long and 3¼ feet in diameter, 220 lbs. -of potato starch can be uniformly mixed in 5 minutes with<span class="pagenum" id="Page_261">261</span> -about 9 ozs. of nitric acid of 40° B., and the drum emptied -by opening the slide. Starch thus treated may be brought -into the oven without previous drying.</p> - -<p>Heuzé gives the following method: Four and a half -pounds of nitric acid of 1.4 specific gravity together with -300 quarts of water are mixed with 2,200 lbs. of starch, and -boiled to form a mass which, when exposed to the air becomes -dry. It is sometimes effected at 177° F., but it -becomes a paste at 212° to 230° F. The starch changes -into dextrine in an hour or an hour and a half at the most; -it is white and soluble in water.</p> - -<p><i>Tragacanth, or gum tragacanth</i>, exudes from <i>Astragalus -verus</i>, a tree indigenous to Asia. The term gum is a misnomer, -as tragacanth does not actually dissolve in water -nor in spirit of wine, but merely swells up in water to a soft -gelatinous mass. Tragacanth consists of irregular pieces of -a pure white to yellowish color. It is chiefly used for confectioner’s -purposes, though sometimes as a paste for fancy -articles. This variety of gum is found, together with -arabine, in the gum which exudes from cherry, plum, -almond, and apricot trees, and gives the mucilaginous character -to the watery decoctions prepared from certain seeds, -such as linseed and quince-seed, and from the root of -marshmallow.</p> - - -<h4>PASTES AND MUCILAGES FOR SPECIAL PURPOSES.</h4> - -<p><i>Starch paste.</i> Corn starch 8 ozs., cold water ½ pint, boiling -water 1 gallon.</p> - -<p>Beat up the starch in the cold water until reduced to a -creamy consistence, then pour the mixture into the boiling -water and stir briskly until the white, semi-opaque mass, -becomes transparent. Should it fail to do so, place it over -the fire, and boil until the desired result is obtained, stirring -constantly.</p> - -<p><i>Flour paste.</i> Wheat flour 4 lbs., cold water 2 quarts, -alum 2 ozs., hot water ½ pint, boiling water 2 gallons.</p> - -<p><span class="pagenum" id="Page_262">262</span></p> - -<p>Work the wheat flour into a batter free from lumps with -the cold water. Dissolve the alum in the hot water. Then -stir the batter into the boiling water, and if necessary, continue -boiling until the paste thickens into a semi-transparent -mucilage, after which stir in the alum solution. This -makes a very fine paste for wall-paper.</p> - -<p><i>Strong adhesive paste.</i> Rye flour 2 lbs., cold water 1 -quart, boiling water 3 quarts, pulverized rosin 1 oz.</p> - -<p>Make the flour into a batter with the cold water, free -from lumps, and pour into the boiling water. Boil, if -necessary, and while hot stir in the pulverized rosin, a -little at a time. This paste is very strong, and will fasten -heavy wall-paper or thin leather. If too thick, thin with -hot water. Never thin paste with cold water.</p> - -<p><i>Paste that will not sour.</i> Allow 4 parts by weight of glue -to soften in 15 parts of cold water for some hours, and then -heat moderately till the solution becomes quite clear; then -add, while stirring, 65 parts of boiling water. In another -vessel stir up 30 parts of starch paste with 20 parts of cold -water, so that a thin, milky fluid without lumps is obtained. -Into this pour the boiling glue solution, stirring constantly, -and keep the whole at the boiling temperature. After cooling, -add 5 to 10 drops of carbolic acid to the paste. Preserve -the paste in closed bottles to prevent evaporation of -the water. It will thus keep good for years.</p> - -<p><i>Venetian paste.</i> White or fish glue 4 ozs., cold water ½ -pint, Venice turpentine 2 fluid ozs., rye flour 1 lb., cold -water 1 pint, boiling water 2 quarts.</p> - -<p>Soak the 4 ozs. of glue in the cold water for 4 hours. -Dissolve over a water-bath, and while hot stir in the Venice -turpentine. Make up the rye flour into a batter free from -lumps with the pint of water, and pour the latter into the -boiling water. Stir briskly, and finally add the glue solution. -This makes a very strong paste, and it will adhere -to a painted surface, owing to the Venice turpentine in its -composition.</p> - -<p><span class="pagenum" id="Page_263">263</span></p> - -<p><i>Label paste.</i> A good paste for attaching labels to bottles -may be made by soaking glue in strong vinegar, then heat -to boiling and add flour. This is very adhesive, and will -not decompose when kept in wide-mouthed bottles.</p> - -<p><i>Elastic or pliable paste.</i> Starch 4 ozs., white dextrine 2 -ozs., cold water 10 fluid ozs., borax 1 oz., glycerine 3 fluid -ozs., boiling water 2 quarts.</p> - -<p>Beat the starch and dextrine into paste with the cold -water. Dissolve the borax in the boiling water, then add -the glycerine, and pour the starch and dextrine mixture -into the borax solution. Stir until it becomes translucent. -This paste will not crack, and, being very pliable, is suitable -for paper, cloth, leather and other material where -flexibility is required.</p> - -<p><i>Mucilage for labels.</i> Macerate 5 parts of good glue in 20 -parts of water for 24 hours, and to the liquid add 9 parts of -rock candy, and 3 parts of gum arabic. The mixture may -be brushed upon paper while lukewarm. It keeps well, -does not stick together and adheres firmly to bottles.</p> - -<p><i>Mucilage.</i> A strong aqueous solution of dextrine forms a -most adhesive and cheap mucilage. Dilute alcohol is -usually employed as the solvent where the mucilage is to -be used for gumming envelopes, postage stamps, etc., and in -order to facilitate the drying, acetic acid is added to increase -the mobility of the fluid. The strong aqueous solution -is more adhesive than that prepared with alcohol, for -the reason that it contains a greater proportion of dextrine.</p> - -<p>To prepare this add an excess of dextrine to boiling -water, stir for a minute or two, allow to cool and settle, and -strain the liquid through a cloth. The addition of a little -powdered sugar increases the glossiness of the dried gum. -The sugar should be dissolved in the water before the dextrine -is added.</p> - -<p><i>According to another formula</i>, dextrine is mixed with hot -water until a syrupy liquid is obtained. Then add a few -drops of oil of cloves, and cool for use.</p> - -<p><span class="pagenum" id="Page_264">264</span></p> - -<p><i>Another formula is as follows</i>: Dextrine 120 parts, powdered -alum 6, sugar 30, carbolic acid 1, water 300. Mix gradually -the dextrine, alum and sugar with the water, boil to -effect solution, and when cold, add the carbolic acid.</p> - -<p>The solubility of dextrine may be enhanced by the addition -of a calcium salt readily soluble in water, the resulting -mixture dissolving with ease in cold water. Calcium -nitrate has proved especially suitable for the purpose. By -pouring 1 quart of water over a mixture of 18 ozs. of dextrine -and 7 ozs. of calcium nitrate, a mass of great adhesive -power is immediately obtained.</p> - -<p><i>Mucilage for postage stamps.</i> Dextrine 2 parts, acetic acid -1, water 5, alcohol 1. Mix all together.</p> - -<p><i>Caseine mucilage.</i> Take the curd of skim milk, wash it -thoroughly, and dissolve it to saturation in a cold concentrated -solution of borax.</p> - -<p><i>Tragacanth mucilage.</i> Powdered tragacanth 2 drachms, -glycerine 12 drachms, water enough to make 20 ozs.</p> - -<p>Put the tragacanth in a mortar with the glycerine, and -then add the water. This will produce at once a mucilage -of excellent quality.</p> - -<p><i>Adhesive paste.</i> Steep 4 ozs. of ordinary gelatine in -16 ozs. of water until it becomes soft, then dissolve it by the -heat of a water bath, and while still hot pour into a mixture -of 2 lbs. of good flour paste and 1 part of water. Heat -the whole to boiling and when thickened remove from the -fire. While cooling add 6 drachms of silicate of soda and -stir the mixture with a wooden spatula. This preparation -will keep good for an indefinite period, and is very adhesive. -The addition of 2 drachms of oil of cloves is an improvement.</p> - -<p><i>Fluid pastes.</i> I. Gum arabic 10 lbs., sugar 2 lbs., nitric -acid 1¾ ozs., water as required.</p> - -<p>Dissolve the gum and sugar in the water, then add the -acid and heat to the boiling-point. The resulting paste is -liquid, does not mould, and dries to a transparent layer<span class="pagenum" id="Page_265">265</span> -upon paper. It is especially suitable for flaps of envelopes, -fine bookbinders’ work, etc.</p> - -<p>II. Potato starch 10 lbs., water 5 quarts, nitric acid 8 ozs.</p> - -<p>Mix the acid and water and pour it on the starch in an -earthenware basin, put the latter in a warm place, and -allow it to remain 24 hours, with occasional stirring. Then -boil it until it becomes thickly-fluid and very transparent. -If necessary it should be diluted with water and filtered -through a cloth.</p> - -<p><i>Sugar and lime paste.</i> Dissolve 12 parts of white sugar in -36 of water. Heat the solution to the boiling-point and -add 3 parts of slaked lime. Allow the liquid to stand in a -covered vessel for several days, stirring frequently and, -when settled, pour off the supernatant thick fluid from the -excess of lime.</p> - -<p>The paste thus obtained has all the properties of gum -arabic solution and dries to a lustrous mass.</p> - -<p><i>Liquid sugar and lime paste.</i> Allow 3 parts of glue to -swell in 10 to 15 parts of the foregoing paste. Heat the -mixture to the boiling-point. The paste thus obtained does -not congeal on cooling and possesses considerable adhesive -power.</p> - -<p>By reason of its caustic properties, due to the content of -lime, this paste should not be used for pasting colored -materials.</p> - -<p><i>Pastes for paper and fine fancy articles.</i> I. Dissolve, with -the assistance of heat, 100 parts of gilder’s glue in 200 of -water, and add a solution of 2 parts of bleached shellac in -10 of alcohol.</p> - -<p>II. Dissolve, with the assistance of heat, 50 parts of dextrine -in 50 of water, stir solutions 1 and 2 together, strain -through a cloth into a flat prismatic mould, and allow it to -congeal. For use, melt a piece of corresponding size, and -dilute the liquid, if necessary, with water.</p> - -<p><i>Albumen paste.</i> This is a misnomer, as it contains no -albumen. It is partly decayed gluten from flour, washed<span class="pagenum" id="Page_266">266</span> -with water and then heated to 60° or 68° F., when it ferments -and becomes partly fluid. It is then dried at 77° to -86° F., and is claimed to keep any length of time in a dry -place. Dissolved in twice its weight of water it can be used -as a paste for all purposes.</p> - -<p><i>Glycerine paste.</i> Dissolve 2 ozs. of gum arabic and 4 -drachms of glycerine in 6 ozs. of boiling water. This is a -good paste for office use.</p> - -<p><i>Paste for fixing labels on machines.</i> Make a paste of rye -flour and glue and add to every pound thereof ½ oz. each of -boiled linseed oil and turpentine. This paste resists damp -and thus prevents printed labels from falling off metallic -surfaces.</p> - -<p><i>Paste for mounting maps.</i> Stiff rye flour paste is best for -this purpose.</p> - -<p><i>Paste for fastening paper on tin-foil.</i> Make a paste by dissolving -rye flour in solution of caustic soda; dilute with -water, stirring all the time. Add to this paste a few drops -of Venice turpentine for each ½ lb. of flour.</p> - -<p><i>Paste for paper bags.</i> Add to 3 parts of starch 24 to 30 -parts of cold water. Stir together to a homogeneous mass -of about the thickness of syrup. Pour over this, stirring -constantly, boiling water until the paste is of the required -consistency. Stir until nearly cold. Take a portion of the -paste and add to it 6 to 15 per cent. liquefied Venice turpentine; -rub together until a kind of emulsion is formed, -then mix the whole together and work thoroughly.</p> - -<p><i>Caseine mucilage for photographer’s use.</i> Separate the -caseine from milk by means of a little tartaric acid, and -treat the caseine while still warm with a solution of 6 parts -of borax to 100 parts water, and warm gently while stirring -which will cause the caseine to be dissolved. Of the borax -solution enough should be used to leave only a little undissolved -caseine behind.</p> - -<p><i>Paste for scrap-books.</i> Rice starch 1 oz., gelatine 3 -drachms, water ½ pint.</p> - -<p><span class="pagenum" id="Page_267">267</span></p> - -<p>Heat, stirring constantly, until the milky fluid becomes -thick and gluey. When the paste is nearly thick put in a -bottle closely corked. It is well to add a few drops of oil -of cloves to each bottle.</p> - -<p><i>Paste for skins.</i> Pour enough boiling water over 1 lb. of -rye flour in a basin to make a stiff paste, almost as stiff as -ordinary dough for puddings. Stir and beat up well with -a stick for three or four minutes, then cover up and let it -stand for two days before using, when it will be much softer -and stick better. Spread thinly and evenly on the back of -the skin with a stiff brush or pad. It will stick firmly and -not crack.</p> - -<p><i>Strong mucilage</i> capable of fastening wood or china and -glass together is made of 3½ ozs. of strong gum arabic solution, -to which a solution of 30 grains of sulphate of aluminium -dissolved in ⅔ oz. of water is added.</p> - -<p><i>Dextrine mucilage.</i> I. Dissolve with the assistance of heat -60 parts of borax in 420 parts of water, add 480 parts of -pale yellow dextrine and 50 parts of glucose, and heat carefully, -stirring constantly until solution is complete, replacing -the water lost by evaporation. Strain through flannel.</p> - -<p>The resulting mucilage is quite clear, has great adhesive -power, and dries very quickly. In heating the mixture, -great care should be exercised not to exceed a temperature -of 194° F. and not to heat too long, otherwise the product -readily becomes brown and brittle.</p> - -<p>II. Dextrine 120 parts, powdered alum 6, sugar 30, carbolic -acid 1, distilled water 300. Gradually mix the dextrine, -alum and sugar with the water, effect solution by -boiling and when the solution is cold, add the carbolic acid.</p> - -<p><i>Paste for joining leather to pasteboard.</i> Dissolve 50 parts -of strong glue with a little water at a gentle heat, then add -a small quantity of Venice turpentine, and next a thick -paste made with 100 parts of starch in water. Apply -quickly when cold.</p> - -<p><i>Another formula</i> for a similar paste is as follows: Rye<span class="pagenum" id="Page_268">268</span> -whisky 2 pints, water 1 pint, powdered starch 4¼ ozs., good -glue 1¼ ozs., Venice turpentine 1¼ ozs. Mix the whisky -and water together, then stir in the starch and make a thick -paste. Separately dissolve the glue in an equal weight of -water, and mix the Venice turpentine therein, mix thoroughly, -and then compound this mixture with the thick -paste by constantly stirring until all is well incorporated.</p> - -<p><i>Paste for attaching labels to polished nickel.</i> Dissolve 400 -parts by weight of dextrine in 600 parts of water, and add -20 parts of glycerine and 10 parts of glucose. Heat the -mixture to 194° F.</p> - -<p><i>Another formula</i> is as follows: Mix 400 parts by weight -of dextrine with water, and add 200 parts of water together -with 20 parts of glucose and 10 parts of aluminium sulphate.</p> - -<p><i>Mucilage for attaching labels to tin.</i> I. Shellac 8 parts, -borax 4 parts, water 60 parts. Boil until the shellac is -dissolved.</p> - -<p>II. To 2 parts of dammar varnish add 8 parts of tragacanth -mucilage.</p> - -<p>III. An excellent mucilage for the purpose consists of -starch paste to which a small quantity of Venice turpentine -has been added.</p> - -<p>IV. Make a paste of corrosive sublimate 2½ parts, wheat -flour 200, absinthe 100, tansy 50, water 3000. This mucilage -is useful for vessels kept in a damp place.</p> - -<p><i>Mucilage for office use.</i> Gum arabic 100 parts, aluminium -sulphate 6 parts, glycerine 10, dilute acetic acid 20, distilled -water 140. Dissolve, in a wide-mouthed glass bottle, the -gum arabic in cold distilled water, stirring frequently. Let -the solution stand 2 or 3 days, then add the glycerine, later -on the dilute acetic acid and finally the aluminium sulphate. -Strain through a hair sieve, allow to clarify, and -decant from the sediment.</p> - -<p><i>Glycerine paste for office use.</i> Dissolve 4 ozs. of gum arabic -and 8 drachms of glycerine in 12 ozs. of boiling water.</p> - -<p><i>Clean and durable paste.</i> Dissolve 5 ozs. of gum arabic in<span class="pagenum" id="Page_269">269</span> -4 quarts of warm water, and thicken to a paste with wheat -flour. Then add a solution of alum and sugar of lead, -3 ozs. of each in water. Heat the mixture and stir it until -it is about to boil, and then cool it. If too thick, add gum -solution.</p> - -<p><i>Banknote or mouth glue.</i> Dissolve by the aid of heat a -fine quality of glue or gelatine with about a quarter or one-third -of its weight of brown sugar, in as small a quantity of -water as possible. Then when perfectly liquid cast the -mixture into thin cakes on a flat surface very slightly oiled, -and when cold cut up into pieces of convenient size. When -required for use moisten one end. A piece of this glue -kept in the desk will be found very convenient for many -purposes.</p> - -<p><i>Paste for cardboard.</i> Dissolve 3½ ozs. of best French glue -in 6½ ozs. of water by soaking and heating. Then add a -solution of ½ drachm of shellac in 3½ drachms of alcohol -and stir as long as the solution is warm. Next dissolve 2 -drachms of dextrine in 1¾ ozs. of alcohol and 14 drachms -of water, stir, and place the vessel in warm water until solution -is complete. Mix this solution with that of the glue, -and pour the whole into a suitable vessel, in which it may -solidify. When wanted for use cut off a small piece and -liquefy it by warming.</p> - -<p><i>Paste for attaching cloth or leather to table tops.</i> Wheat -flour 1 lb., powdered rosin 2 tablespoonfuls, powdered alum -1 tablespoonful. Heat and stir to a stiff consistency.</p> - -<p><i>Caseine mucilage.</i> Separate the caseine from milk with a -little tartaric acid, and treat the caseine while still warm -with a solution of 6 parts borax to 100 parts water and warm -gently while stirring, which will cause the caseine to be dissolved. -Of the borax solution enough should be used to -leave only a little undissolved caseine behind.</p> - -<p><i>Very adhesive paste which may be used for wood and parchment.</i> -Gum arabic 60 parts, fine wheat starch 45, sugar 15. -Dissolve the gum in as much water as is required for boil<span class="pagenum" id="Page_270">270</span>ing -the quantity of paste to be made. Then add the starch -and sugar and boil it in a vessel suspended in boiling water -until the mixture is clear and has the consistency of liquid -tar. Keep in a well-closed vessel protected from mould by -the addition of a few drops of oil of cloves.</p> - -<p><i>Paste for pads.</i> Glue 4 parts by weight, glycerine 2, linseed -oil ½, sugar 4, aniline dye sufficient to color. Soften -the glue by soaking in cold water, then dissolve together -with the sugar in the glycerine by the aid of heat over the -water-bath, then add the dye and stir in the oil. Use the -paste hot.</p> - -<p><i>Paste for fastening paper on tin-foil.</i> Make a paste by dissolving -rye flour in a solution of caustic soda; dilute with -water, stirring constantly. Add to this paste a few drops -of Venice turpentine for each ½ lb. flour used. This paste -adheres to all kinds of metal, tin-foil, glass, etc.</p> - -<p><i>Paste for attaching labels to glass, porcelain, and metal.</i> -Gum arabic 15 parts, pulverized tragacanth 7½, glycerin -45, thymol 0.3, alcohol 3¾, water 120. Dissolve the gum -arabic in 15 parts of water and triturate the tragacanth -with 30 parts of water. Mix the two fluids and strain. -Then add the glycerine and finally the thymol dissolved in -the alcohol.</p> - -<p><i>Preparation of arabol-gum.</i> Mix intimately 44 lbs. of -wheat starch with 176 lbs. of water. Bring the mass into -a water-bath, mix it with a solution of 4.4 lbs. of oxalic -acid in 44 lbs. of water and heat for four hours at 194° F., -stirring frequently. The conversion of the starch is as a -rule effected during this time, but should such not be the -case, continue heating, constantly replacing the evaporated -water, until the mass is clear and liquid. While still hot, -neutralize the mass with marble dust, allow to settle, filter, -and evaporate the clear solution in a water-bath to a solid -gum containing about 15 per cent. of water.</p> - -<p><i>Preparation of an adhesive substance from desaccharized beet-root -slices</i> (German patent 96316 f. G. Eichelbaum). The<span class="pagenum" id="Page_271">271</span> -insoluble metarabin contained in the slices is converted -into soluble arabin by treating the slices under pressure -with hot aqueous sulphurous acid or with aqueous solutions -of the bisulphites of the alkalies or alkaline earths.</p> - -<p>According to a later patent (German patent 121422 f. -Fabrik Bettenhausen Marquart and Schulz), the insoluble -metarabin is converted into soluble arabin by heating the -desaccharized beet-root slices with phosphoric acid and -water. According to a supplement to this patent (122048), -conversion is effected by heating the slices with aqueous -solutions of organic acids and phenols, or the acid salts of -oxalic, tartaric or phosphoric acids.</p> - -<hr class="chap" /> - -<p><span class="pagenum" id="Page_272">272</span></p> -<p><span class="pagenum" id="Page_273">273</span></p> - - - - -<h2 id="INDEX">INDEX.</h2> - -<div class="index"> -<ul class="index"> -<li class="ifrst">Acid calcium phosphate, <a href='#Page_120'>120</a></li> - -<li class="indx">—— —— —— crystallization of, <a href='#Page_125'>125</a>, <a href='#Page_126'>126</a></li> - -<li class="indx">—— —— —— formation of, <a href='#Page_121'>121</a>-124</li> - -<li class="indx">—— sodium sulphate, use of, in drying glue, <a href='#Page_72'>72</a>, <a href='#Page_73'>73</a></li> - -<li class="indx">Acidity, determination of, in glue, <a href='#Page_205'>205</a>, <a href='#Page_206'>206</a></li> - -<li class="indx">Acids, dilute, effect of, on glue solution, <a href='#Page_7'>7</a></li> - -<li class="indx">Adamson, Wm., method of, for removing hydrocarbons from substances which have been treated therewith, <a href='#Page_84'>84</a>-86</li> - -<li class="indx">—— —— method of, for treating substances with hydro carbon vapor for the purpose of extracting oils, fats, etc., <a href='#Page_79'>79</a>-82</li> - -<li class="indx">—— —— method of, for treating substances with liquid hydrocarbons for the purpose of extracting oils, fats, etc., <a href='#Page_82'>82</a>-84</li> - -<li class="indx">—— —— and Simonis, Chas. F. A., apparatus of, for extracting bones with benzine, <a href='#Page_76'>76</a>-79</li> - -<li class="indx">Adhesive paste, <a href='#Page_264'>264</a></li> - -<li class="indx">Adulterations of glue, determination of, <a href='#Page_214'>214</a>, <a href='#Page_215'>215</a></li> - -<li class="indx">Agar-Agar, <a href='#Page_12'>12</a>, <a href='#Page_201'>201</a>, <a href='#Page_202'>202</a></li> - -<li class="indx">Air-bladders, <a href='#Page_16'>16</a>, <a href='#Page_41'>41</a></li> - -<li class="indx">—— bleaching glue in the, <a href='#Page_141'>141</a></li> - -<li class="indx">—— drying the cakes of glue in the, <a href='#Page_64'>64</a></li> - -<li class="indx">Alabaster, <a href='#Page_244'>244</a></li> - -<li class="indx">—— cement for, <a href='#Page_242'>242</a></li> - -<li class="indx">Albumen paste, <a href='#Page_265'>265</a>, <a href='#Page_266'>266</a></li> - -<li class="indx">—— —— use of, for clarifying glue liquor, <a href='#Page_54'>54</a></li> - -<li class="indx">Alum cement, <a href='#Page_228'>228</a></li> - -<li class="indx">—— —— effect of, on glue solution, <a href='#Page_7'>7</a></li> - -<li class="indx">—— —— use of, for clarifying glue liquor, <a href='#Page_54'>54</a></li> - -<li class="indx">—— —— —— —— preserving paste, <a href='#Page_257'>257</a></li> - -<li class="indx">Amber, resinous cement for, <a href='#Page_229'>229</a></li> - -<li class="indx">American cement for jewelers, <a href='#Page_252'>252</a></li> - -<li class="indx">American glue, analysis of, <a href='#Page_207'>207</a></li> - -<li class="indx">Ammonium sulphate, use of, in drying glue, <a href='#Page_72'>72</a>, <a href='#Page_73'>73</a></li> - -<li class="indx">Animal charcoal, bleaching glue with, <a href='#Page_142'>142</a></li> - -<li class="indx">—— —— bones for the manufacture of, <a href='#Page_107'>107</a></li> - -<li class="indx">—— —— carbonization of bones for, <a href='#Page_108'>108</a>-112</li> - -<li class="indx">—— —— decolorizing glue liquor with, <a href='#Page_55'>55</a></li> - -<li class="indx">—— —— manufacture of, <a href='#Page_112'>112</a>, <a href='#Page_113'>113</a></li> - -<li class="indx">—— —— yield of, <a href='#Page_113'>113</a></li> - -<li class="indx">—— skin, constitution of, <a href='#Page_17'>17</a>, <a href='#Page_18'>18</a></li> - -<li class="indx">Antiseptics for the preservation of glue-stock, <a href='#Page_30'>30</a></li> - -<li class="indx">Arabin, conversion of metarabin into, <a href='#Page_271'>271</a></li> - -<li class="indx">Arabol-gum, preparation of, <a href='#Page_270'>270</a></li> - -<li class="indx">Ash, burning bones to, <a href='#Page_117'>117</a>-119</li> - - -<li class="ifrst">Bacteriology, use of gelatine in, <a href='#Page_194'>194</a></li> - -<li class="indx">Banknote glue, <a href='#Page_269'>269</a></li> - -<li class="indx">Barium chloride, effect of, on glue solution, <a href='#Page_7'>7</a></li> - -<li class="indx">Basic calcium phosphate, <a href='#Page_120'>120</a></li> - -<li class="indx">Beet-root slices, desaccharized, preparation of an adhesive substance from, <a href='#Page_270'>270</a>, <a href='#Page_271'>271</a></li> - -<li class="indx">Belgian retort-furnace for the carbonization of bones, <a href='#Page_109'>109</a>-112</li> - -<li class="indx">Benzine, extracting fat from bones with, <a href='#Page_76'>76</a>-92</li> - -<li class="indx">Billiard balls, compound for, <a href='#Page_155'>155</a>, <a href='#Page_156'>156</a></li> - -<li class="indx">Bleaching glue, methods of, <a href='#Page_141'>141</a>-145</li> - -<li class="indx">—— —— stock, <a href='#Page_55'>55</a>, <a href='#Page_56'>56</a></li> - -<li class="indx">Blood, fresh, use of, for clarifying glue liquor, <a href='#Page_54'>54</a></li> - -<li class="indx">Blumenthal’s method of preparing dextrine, <a href='#Page_260'>260</a>, <a href='#Page_261'>261</a></li> - -<li class="indx">Boiler for glue boiling, <a href='#Page_44'>44</a></li> - -<li class="indx">Boiling bones, <a href='#Page_74'>74</a>, <a href='#Page_75'>75</a></li> - -<li class="indx">—— —— duration of, <a href='#Page_45'>45</a></li> - -<li class="indx">—— —— or cooking glue, <a href='#Page_44'>44</a>-52</li> - -<li class="indx">Bone ash, composition of, <a href='#Page_119'>119</a></li> - -<li class="indx">—— —— conversion of, into a coarse powder, <a href='#Page_119'>119</a> -<span class="pagenum" id="Page_274">274</span></li> -<li class="indx">—— —— decomposition of, by sulphuric acid, <a href='#Page_119'>119</a>-125</li> - -<li class="indx">—— —— kiln for, <a href='#Page_117'>117</a>-119</li> - -<li class="indx">—— —— preparation of, <a href='#Page_117'>117</a>-119</li> - -<li class="indx">—— —— yield of, <a href='#Page_119'>119</a></li> - -<li class="indx">—— cartilage, composition of, <a href='#Page_32'>32</a></li> - -<li class="indx">—— cement for, <a href='#Page_230'>230</a></li> - -<li class="indx">—— crusher, <a href='#Page_36'>36</a></li> - -<li class="indx">—— gelatine, <a href='#Page_170'>170</a>-180</li> - -<li class="indx">—— —— modern process of preparing, <a href='#Page_179'>179</a>, <a href='#Page_180'>180</a></li> - -<li class="indx">—— -glue, manufacture of, <a href='#Page_74'>74</a>-116</li> - -<li class="indx">—— meal, glue and fat, simultaneous utilization of bones for, <a href='#Page_104'>104</a>-113</li> - -<li class="indx">—— -mill, Crosskill, <a href='#Page_36'>36</a></li> - -<li class="indx">—— raw materials, <a href='#Page_16'>16</a></li> - -<li class="indx">—— size, <a href='#Page_159'>159</a>, <a href='#Page_160'>160</a></li> - -<li class="indx">Bones, absorption of sulphurous acid by, <a href='#Page_92'>92</a></li> - -<li class="indx">—— Adamson and Simonis’ apparatus for extracting, <a href='#Page_76'>76</a>-79</li> - -<li class="indx">—— and cartilages, <a href='#Page_31'>31</a>-39</li> - -<li class="indx">—— apparatus for extracting the fat from, with benzine, <a href='#Page_76'>76</a>-94</li> - -<li class="indx">—— Belgian retort-furnace for the carbonization of, <a href='#Page_109'>109</a>-112</li> - -<li class="indx">—— boiling of, <a href='#Page_74'>74</a>, <a href='#Page_75'>75</a></li> - -<li class="indx">—— burning of, to ash, <a href='#Page_117'>117</a>-119</li> - -<li class="indx">—— buying of, <a href='#Page_32'>32</a></li> - -<li class="indx">—— carbonization of, <a href='#Page_108'>108</a>-112</li> - -<li class="indx">—— constitution of, <a href='#Page_32'>32</a></li> - -<li class="indx">—— crushed, sorting of, <a href='#Page_36'>36</a>, <a href='#Page_37'>37</a></li> - -<li class="indx">—— crushing or grinding of, <a href='#Page_33'>33</a>-36</li> - -<li class="indx">—— extraction of, <a href='#Page_76'>76</a>-94</li> - -<li class="indx">—— —— —— phosphates from, <a href='#Page_115'>115</a></li> - -<li class="indx">—— fatty matters in, <a href='#Page_32'>32</a></li> - -<li class="indx">—— for the manufacture of animal charcoal, <a href='#Page_107'>107</a></li> - -<li class="indx">—— honey-combed, <a href='#Page_39'>39</a></li> - -<li class="indx">—— Leuner’s apparatus for extracting, <a href='#Page_90'>90</a>-92</li> - -<li class="indx">—— lime bath for, <a href='#Page_37'>37</a></li> - -<li class="indx">—— products obtained in the distillation of, <a href='#Page_112'>112</a></li> - -<li class="indx">—— Seltsam’s apparatus for extracting, <a href='#Page_84'>84</a>-86</li> - -<li class="indx">—— —— apparatus for extracting, improved by Th. Richter, <a href='#Page_88'>88</a>-90</li> - -<li class="indx">—— simultaneous utilization of, for fat, bone-meal and glue, <a href='#Page_104'>104</a>-113</li> - -<li class="indx">—— —— utilization of, for fat, glue and calcium phosphate, <a href='#Page_113'>113</a>-116</li> - -<li class="indx">—— sorting of, <a href='#Page_32'>32</a>, <a href='#Page_33'>33</a>, <a href='#Page_104'>104</a>, <a href='#Page_105'>105</a></li> - -<li class="indx">—— sulphurous acid for extracting, <a href='#Page_92'>92</a>-94</li> - -<li class="indx">—— treatment of, with high pressure steam, <a href='#Page_105'>105</a>-107</li> - -<li class="indx">—— utilization of the liquor obtained in the treatment of, with hydrochloric acid, <a href='#Page_125'>125</a>-127</li> - -<li class="indx">—— value of, <a href='#Page_32'>32</a></li> - -<li class="indx">—— waste of, from the preparation of tinned provisions, <a href='#Page_19'>19</a></li> - -<li class="indx">Bookbinder’s glue, <a href='#Page_12'>12</a></li> - -<li class="indx">—— size, <a href='#Page_160'>160</a></li> - -<li class="indx">Book isinglass, <a href='#Page_197'>197</a></li> - -<li class="indx">Boric acid, preservation of glue-stock with, <a href='#Page_30'>30</a></li> - -<li class="indx">Bottles, cracked, cement for, <a href='#Page_240'>240</a>, <a href='#Page_241'>241</a></li> - -<li class="indx">Bouillon tablets, <a href='#Page_12'>12</a></li> - -<li class="indx">Brazilian isinglass, <a href='#Page_199'>199</a>, <a href='#Page_200'>200</a></li> - -<li class="indx">Briers, D. J., process for the preparation of bone gelatine employed by, <a href='#Page_171'>171</a>-179</li> - -<li class="indx">Brochette, <a href='#Page_43'>43</a></li> - -<li class="indx">Brushmaker’s cement, <a href='#Page_251'>251</a></li> - -<li class="indx">Bullock’s feet, <a href='#Page_18'>18</a></li> - -<li class="indx">—— hide, waste of, <a href='#Page_18'>18</a></li> - -<li class="indx">—— leather, <a href='#Page_30'>30</a></li> - -<li class="indx">Burning bones to ash, <a href='#Page_117'>117</a>-119</li> - - -<li class="ifrst">Cakes, cutting glue into, <a href='#Page_57'>57</a>-64</li> - -<li class="indx">—— drying the, <a href='#Page_64'>64</a>-73</li> - -<li class="indx">—— machines for cutting the jelly into, <a href='#Page_60'>60</a>-64</li> - -<li class="indx">—— shape of, <a href='#Page_57'>57</a>, <a href='#Page_58'>58</a></li> - -<li class="indx">—— tools for cutting the jelly into, <a href='#Page_59'>59</a></li> - -<li class="indx">Calcium chloride, <a href='#Page_116'>116</a></li> - -<li class="indx">—— metaphosphate, <a href='#Page_120'>120</a>, <a href='#Page_127'>127</a></li> - -<li class="indx">—— phosphate, <a href='#Page_115'>115</a></li> - -<li class="indx">—— —— fat and glue, simultaneous utilization of bones for, <a href='#Page_113'>113</a>-116</li> - -<li class="indx">Calf leather, <a href='#Page_30'>30</a></li> - -<li class="indx">—— skin waste, <a href='#Page_18'>18</a></li> - -<li class="indx">Calves’ feet, <a href='#Page_30'>30</a></li> - -<li class="indx">—— heads, <a href='#Page_18'>18</a>, <a href='#Page_30'>30</a></li> - -<li class="indx">Carbolic acid, preservation of glue-stock with, <a href='#Page_29'>29</a></li> - -<li class="indx">—— —— use of, for preserving paste, <a href='#Page_257'>257</a>, <a href='#Page_258'>258</a></li> - -<li class="indx">Carbon disulphide, use of, for extracting bones, <a href='#Page_76'>76</a></li> - -<li class="indx">Cardboard, paste for, <a href='#Page_269'>269</a></li> - -<li class="indx">Cartilage, <a href='#Page_1'>1</a></li> - -<li class="indx">—— conversion of, into glue, <a href='#Page_94'>94</a>-104</li> - -<li class="indx">—— drying of, <a href='#Page_114'>114</a></li> - -<li class="indx">—— preservation of, <a href='#Page_114'>114</a></li> - -<li class="indx">—— treatment of, with high-pressure steam, <a href='#Page_98'>98</a></li> - -<li class="indx">—— yield of glue from, <a href='#Page_115'>115</a></li> - -<li class="indx">Cartilages and bones, <a href='#Page_31'>31</a>-39 -<span class="pagenum" id="Page_275">275</span></li> -<li class="indx">Caseine cement which can be kept for a long time, <a href='#Page_239'>239</a></li> - -<li class="indx">—— cements, <a href='#Page_237'>237</a>-240</li> - -<li class="indx">—— mucilage, <a href='#Page_264'>264</a></li> - -<li class="indx">—— —— for photographer’s use, <a href='#Page_266'>266</a></li> - -<li class="indx">—— ordinary technical, preparation of, <a href='#Page_238'>238</a>, <a href='#Page_239'>239</a></li> - -<li class="indx">—— pure, preparation of, <a href='#Page_237'>237</a>, <a href='#Page_238'>238</a></li> - -<li class="indx">Castings, cement for filling in defects in, <a href='#Page_246'>246</a></li> - -<li class="indx">Cattle, pieces of hide from the lower parts of the limbs of, <a href='#Page_30'>30</a></li> - -<li class="indx">Cayenne isinglass, <a href='#Page_199'>199</a>, <a href='#Page_200'>200</a></li> - -<li class="indx">Cellular tissue, <a href='#Page_1'>1</a></li> - -<li class="indx">Celluloid, cement for, <a href='#Page_252'>252</a></li> - -<li class="indx">Cement resisting acids, <a href='#Page_248'>248</a></li> - -<li class="indx">—— —— —— very high temperatures, <a href='#Page_248'>248</a></li> - -<li class="indx">Cements, caseine, <a href='#Page_237'>237</a>-240</li> - -<li class="indx">—— chemical nature of, <a href='#Page_219'>219</a></li> - -<li class="indx">—— classification of, <a href='#Page_218'>218</a>-223</li> - -<li class="indx">—— for chemical apparatus, <a href='#Page_247'>247</a>-249</li> - -<li class="indx">—— —— —— —— special purposes, <a href='#Page_249'>249</a>-252</li> - -<li class="indx">—— glue and starch, <a href='#Page_222'>222</a>, <a href='#Page_223'>223</a></li> - -<li class="indx">—— glycerine, <a href='#Page_242'>242</a></li> - -<li class="indx">—— gypsum, <a href='#Page_244'>244</a>, <a href='#Page_245'>245</a></li> - -<li class="indx">—— how to use, <a href='#Page_252'>252</a>-255</li> - -<li class="indx">—— iron, <a href='#Page_245'>245</a>-247</li> - -<li class="indx">—— lime, <a href='#Page_223'>223</a>, <a href='#Page_243'>243</a>, <a href='#Page_244'>244</a></li> - -<li class="indx">—— oil, <a href='#Page_219'>219</a>, <a href='#Page_220'>220</a>, <a href='#Page_224'>224</a>-229</li> - -<li class="indx">—— pastes and mucilages, preparation of, <a href='#Page_224'>224</a>-271</li> - -<li class="indx">—— resinous, <a href='#Page_220'>220</a>, <a href='#Page_221'>221</a>, <a href='#Page_229'>229</a>-233</li> - -<li class="indx">—— resisting high temperatures, <a href='#Page_246'>246</a></li> - -<li class="indx">—— rubber and gutta-percha, <a href='#Page_222'>222</a>, <a href='#Page_233'>233</a>-237</li> - -<li class="indx">—— water glass, <a href='#Page_240'>240</a>-242</li> - -<li class="indx">Chalk, <a href='#Page_243'>243</a></li> - -<li class="indx">Charcoal, animal, bleaching glue with, <a href='#Page_142'>142</a></li> - -<li class="indx">—— —— bones for the manufacture of, <a href='#Page_107'>107</a></li> - -<li class="indx">—— —— carbonization of bones for, <a href='#Page_108'>108</a>-112</li> - -<li class="indx">—— —— manufacture of, <a href='#Page_112'>112</a>, <a href='#Page_113'>113</a></li> - -<li class="indx">—— —— yield of, <a href='#Page_113'>113</a></li> - -<li class="indx">—— mixing calcium phosphate with, <a href='#Page_124'>124</a></li> - -<li class="indx">Chemical apparatus, cements for, <a href='#Page_247'>247</a>-249</li> - -<li class="indx">Chinese isinglass, <a href='#Page_201'>201</a>, <a href='#Page_202'>202</a></li> - -<li class="indx">Chlorbarium, soaking hides in, <a href='#Page_20'>20</a></li> - -<li class="indx">Chloride of lime, bleaching glue-stock with, <a href='#Page_55'>55</a></li> - -<li class="indx">Chlorine, bleaching glue with, <a href='#Page_141'>141</a></li> - -<li class="indx">Chondrin, chemical composition of, <a href='#Page_5'>5</a>, <a href='#Page_6'>6</a></li> - -<li class="indx">—— conversion of, into glutin, <a href='#Page_6'>6</a></li> - -<li class="indx">—— formation of, <a href='#Page_3'>3</a></li> - -<li class="indx">—— properties of, <a href='#Page_5'>5</a></li> - -<li class="indx">—— pure, preparation of, <a href='#Page_5'>5</a></li> - -<li class="indx">Chrome glue, <a href='#Page_153'>153</a></li> - -<li class="indx">Clarifying glue liquor, <a href='#Page_52'>52</a>-56</li> - -<li class="indx">—— —— —— apparatus for, <a href='#Page_98'>98</a></li> - -<li class="indx">—— —— —— vats, <a href='#Page_53'>53</a></li> - -<li class="indx">Clay crucibles, cracked, cement for, <a href='#Page_243'>243</a></li> - -<li class="indx">Clearness of glue, definition of, <a href='#Page_53'>53</a></li> - -<li class="indx">Clock faces, white enameled, cement for, <a href='#Page_230'>230</a></li> - -<li class="indx">Cloth, cement for, <a href='#Page_252'>252</a></li> - -<li class="indx">—— paste for attaching, to table tops, <a href='#Page_269'>269</a></li> - -<li class="indx">Colle franche, <a href='#Page_43'>43</a></li> - -<li class="indx">Cologne glue, <a href='#Page_148'>148</a></li> - -<li class="indx">Color mixtures, glue for, <a href='#Page_11'>11</a></li> - -<li class="indx">—— of glue, definition of, <a href='#Page_53'>53</a></li> - -<li class="indx">Colored gelatine, <a href='#Page_181'>181</a>, <a href='#Page_182'>182</a></li> - -<li class="indx">Coloring glue, <a href='#Page_156'>156</a></li> - -<li class="indx">—— matters for gelatine, <a href='#Page_181'>181</a>, <a href='#Page_182'>182</a></li> - -<li class="indx">—— substances, removal of, from glue liquor, <a href='#Page_54'>54</a>-56</li> - -<li class="indx">Combs, hard rubber, cement for, <a href='#Page_236'>236</a></li> - -<li class="indx">Common salt, effect of, on glue solution, <a href='#Page_7'>7</a></li> - -<li class="indx">Constitution of glue, <a href='#Page_3'>3</a>-6</li> - -<li class="indx">Conversion of cartilage into glue, <a href='#Page_94'>94</a>-104</li> - -<li class="indx">Cooking, duration of, <a href='#Page_44'>44</a></li> - -<li class="indx">—— or boiling glue, <a href='#Page_44'>44</a>-52</li> - -<li class="indx">Cooling boxes, <a href='#Page_100'>100</a></li> - -<li class="indx">—— glue liquor, <a href='#Page_100'>100</a></li> - -<li class="indx">Corium, <a href='#Page_1'>1</a>, <a href='#Page_17'>17</a></li> - -<li class="indx">Court-plaster, <a href='#Page_12'>12</a>, <a href='#Page_184'>184</a>, <a href='#Page_185'>185</a></li> - -<li class="indx">Cox, J. and G., process for the manufacture of gelatine patented by, <a href='#Page_166'>166</a>, <a href='#Page_167'>167</a></li> - -<li class="indx">Crockery, cement for, <a href='#Page_236'>236</a>, <a href='#Page_237'>237</a></li> - -<li class="indx">Crosskill bone mill, <a href='#Page_36'>36</a></li> - -<li class="indx">Crucibles, cement for, <a href='#Page_243'>243</a></li> - -<li class="indx">Crude glue, definition of, <a href='#Page_3'>3</a></li> - -<li class="indx">—— —— preparation of, <a href='#Page_43'>43</a></li> - -<li class="indx">Culinary purposes, glue for, <a href='#Page_12'>12</a>-14</li> - - -<li class="ifrst">Dark steam glue, <a href='#Page_152'>152</a></li> - -<li class="indx">Devoulx, cutting apparatus invented by, <a href='#Page_62'>62</a>-64</li> - -<li class="indx">Dextrine mucilage, <a href='#Page_267'>267</a></li> - -<li class="indx">—— —— preparation of, <a href='#Page_259'>259</a>-261</li> - -<li class="indx">Diamond cement, <a href='#Page_229'>229</a></li> - -<li class="indx">Distillation of crude phosphorus, <a href='#Page_133'>133</a>-135</li> - -<li class="indx">—— —— phosphorus, <a href='#Page_127'>127</a>-132</li> - -<li class="indx">Drying, acceleration of, <a href='#Page_72'>72</a>, <a href='#Page_73'>73</a></li> - -<li class="indx">—— cakes of glue, <a href='#Page_64'>64</a>-73</li> - -<li class="indx">—— galleries, <a href='#Page_68'>68</a>-71</li> - -<li class="indx">—— house, modern, <a href='#Page_71'>71</a>, <a href='#Page_72'>72</a> -<span class="pagenum" id="Page_276">276</span></li> -<li class="indx">Drying room, <a href='#Page_65'>65</a></li> - -<li class="indx">—— —— regulating the temperature of the, <a href='#Page_67'>67</a>, <a href='#Page_68'>68</a></li> - - -<li class="ifrst">East India isinglass, <a href='#Page_199'>199</a></li> - -<li class="indx">Elastic cement, <a href='#Page_234'>234</a></li> - -<li class="indx">—— gutta-percha cement, <a href='#Page_236'>236</a></li> - -<li class="indx">—— masses, glue for, <a href='#Page_14'>14</a></li> - -<li class="indx">—— paste, <a href='#Page_263'>263</a></li> - -<li class="indx">Electric furnace for the manufacture of phosphorus, <a href='#Page_138'>138</a>-140</li> - -<li class="indx">Electrical apparatus, cement for, <a href='#Page_251'>251</a>, <a href='#Page_252'>252</a></li> - -<li class="indx">Emery paper, use of glue in the manufacture of, <a href='#Page_12'>12</a></li> - -<li class="indx">Epidermis, <a href='#Page_17'>17</a></li> - -<li class="indx">Epsom salt, behavior of glue solution towards, <a href='#Page_7'>7</a></li> - -<li class="indx">—— —— use of, in drying glue, <a href='#Page_72'>72</a>, <a href='#Page_73'>73</a></li> - -<li class="indx">Evaporating pan, open, <a href='#Page_98'>98</a>-100</li> - -<li class="indx">—— pans, <a href='#Page_124'>124</a></li> - -<li class="indx">Evaporators, spiral, <a href='#Page_100'>100</a>, <a href='#Page_101'>101</a></li> - -<li class="indx">Extraction of bones, <a href='#Page_76'>76</a>-94</li> - - -<li class="ifrst">Fabrics, water-proofing of, <a href='#Page_161'>161</a>-163</li> - -<li class="indx">Fancy articles, fine, paste for, <a href='#Page_265'>265</a></li> - -<li class="indx">Fans, gelatine veneers for, <a href='#Page_15'>15</a></li> - -<li class="indx">Fat, bone meal and glue, simultaneous utilization of bones for, <a href='#Page_104'>104</a>-113</li> - -<li class="indx">—— extraction of, with benzine, <a href='#Page_76'>76</a>-92</li> - -<li class="indx">—— —— —— hydrocarbon vapors, <a href='#Page_79'>79</a>-82</li> - -<li class="indx">—— —— —— liquid hydrocarbons, <a href='#Page_82'>82</a>-84</li> - -<li class="indx">—— glue and calcium phosphate, simultaneous utilization of bones for, <a href='#Page_113'>113</a>-116</li> - -<li class="indx">Fertilizers, utilization of liquors for, <a href='#Page_116'>116</a></li> - -<li class="indx">Fining, gelatine for, <a href='#Page_182'>182</a></li> - -<li class="indx">Fish bladders, <a href='#Page_1'>1</a></li> - -<li class="indx">—— —— glue, <a href='#Page_202'>202</a>-204</li> - -<li class="indx">—— —— —— points to be observed in the manufacture of, <a href='#Page_41'>41</a>, <a href='#Page_42'>42</a></li> - -<li class="indx">—— —— —— raw materials for, <a href='#Page_41'>41</a>, <a href='#Page_42'>42</a></li> - -<li class="indx">—— scales, <a href='#Page_16'>16</a>, <a href='#Page_42'>42</a></li> - -<li class="indx">—— —— preparation of glue from, <a href='#Page_203'>203</a></li> - -<li class="indx">Fleck’s kiln for burning bones, <a href='#Page_118'>118</a>, <a href='#Page_119'>119</a></li> - -<li class="indx">—— process of accelerating the drying of glue, <a href='#Page_72'>72</a>, <a href='#Page_73'>73</a></li> - -<li class="indx">Flour paste, <a href='#Page_256'>256</a>-258, <a href='#Page_261'>261</a>, <a href='#Page_262'>262</a></li> - -<li class="indx">Fluid pastes, <a href='#Page_264'>264</a>, <a href='#Page_265'>265</a></li> - -<li class="indx">Foils, gelatine, <a href='#Page_15'>15</a>, <a href='#Page_185'>185</a>, <a href='#Page_186'>186</a></li> - -<li class="indx">Formaldehyde, preservation of glue-stock with, <a href='#Page_29'>29</a>, <a href='#Page_30'>30</a></li> - -<li class="indx">Forming or moulding the glue, <a href='#Page_56'>56</a>-64</li> - -<li class="indx">Formo-gelatine, <a href='#Page_193'>193</a>, <a href='#Page_194'>194</a></li> - -<li class="indx">French mastic, <a href='#Page_227'>227</a></li> - -<li class="indx">—— putty, <a href='#Page_225'>225</a></li> - -<li class="indx">Friedberg’s apparatus for clarifying glue liquor, <a href='#Page_98'>98</a></li> - -<li class="indx">—- —— —— conversion of cartilage into glue, <a href='#Page_94'>94</a>-97</li> - -<li class="indx">Furnace, electric, for the manufacture of phosphorus, <a href='#Page_138'>138</a>-140</li> - - -<li class="ifrst">Galley furnace, <a href='#Page_128'>128</a>, <a href='#Page_129'>129</a></li> - -<li class="indx">Galvanized iron-wire netting, <a href='#Page_66'>66</a></li> - -<li class="indx">Gelatin, pure, preparation of, <a href='#Page_4'>4</a></li> - -<li class="indx">Gelatine and glycerine, compound of, <a href='#Page_12'>12</a></li> - -<li class="indx">—— and products prepared from it, manufacture of, <a href='#Page_165'>165</a>-195</li> - -<li class="indx">—— artificial silk from, <a href='#Page_195'>195</a></li> - -<li class="indx">—— capsules, <a href='#Page_14'>14</a>, <a href='#Page_184'>184</a></li> - -<li class="indx">—— colored, <a href='#Page_181'>181</a>, <a href='#Page_182'>182</a></li> - -<li class="indx">—— constitution of, <a href='#Page_165'>165</a></li> - -<li class="indx">—— Cox’s process for the manufacture of, <a href='#Page_166'>166</a>, <a href='#Page_167'>167</a></li> - -<li class="indx">—— foils, <a href='#Page_15'>15</a>, <a href='#Page_185'>185</a>, <a href='#Page_186'>186</a></li> - -<li class="indx">—— for fining purposes, <a href='#Page_182'>182</a></li> - -<li class="indx">—— for photographic printing and photographic purposes in general, <a href='#Page_183'>183</a>, <a href='#Page_184'>184</a></li> - -<li class="indx">—— Jullion and Pirie’s process for the preparation of, <a href='#Page_38'>38</a></li> - -<li class="indx">—— Nelson’s process for the manufacture of, <a href='#Page_166'>166</a></li> - -<li class="indx">—— preparation of, from ordinary glue, <a href='#Page_182'>182</a>, <a href='#Page_183'>183</a></li> - -<li class="indx">—— substitute for, <a href='#Page_203'>203</a>, <a href='#Page_204'>204</a></li> - -<li class="indx">—— Swinborne’s improved patented process for the preparation of, <a href='#Page_167'>167</a></li> - -<li class="indx">—— testing of, <a href='#Page_205'>205</a>-217</li> - -<li class="indx">—— veneers, <a href='#Page_15'>15</a>, <a href='#Page_186'>186</a>-193</li> - -<li class="indx">—— yielding tissues, <a href='#Page_1'>1</a></li> - -<li class="indx">German isinglass, <a href='#Page_200'>200</a></li> - -<li class="indx">Gilder’s glue, <a href='#Page_150'>150</a></li> - -<li class="indx">Glass, cement for, <a href='#Page_230'>230</a>, <a href='#Page_233'>233</a>, <a href='#Page_239'>239</a>, <a href='#Page_241'>241</a>, <a href='#Page_243'>243</a>, <a href='#Page_245'>245</a></li> - -<li class="indx">—— —— for attaching metal letters to, <a href='#Page_249'>249</a></li> - -<li class="indx">—— —— —— —— —— to metal, <a href='#Page_251'>251</a></li> - -<li class="indx">—— mastic cement for, <a href='#Page_232'>232</a></li> - -<li class="indx">—— oil cement for, <a href='#Page_228'>228</a></li> - -<li class="indx">—— paper, use of glue in the manufacture of, <a href='#Page_12'>12</a></li> - -<li class="indx">—— paste for attaching labels to, <a href='#Page_270'>270</a></li> - -<li class="indx">—— plates, gelatinizing liquors upon, <a href='#Page_58'>58</a>, <a href='#Page_59'>59</a> -<span class="pagenum" id="Page_277">277</span></li> -<li class="indx">—— upon glass, cement for, <a href='#Page_230'>230</a></li> - -<li class="indx">—— —— metal, cement for, <a href='#Page_230'>230</a></li> - -<li class="indx">Glauber’s salt, use of, in drying glue, <a href='#Page_72'>72</a>, <a href='#Page_73'>73</a></li> - -<li class="indx">Gloves, waste from the manufacture of, <a href='#Page_43'>43</a></li> - -<li class="indx">Glue, acceleration of the drying of, <a href='#Page_72'>72</a>, <a href='#Page_73'>73</a></li> - -<li class="indx">—— addition of mineral substances to, <a href='#Page_149'>149</a></li> - -<li class="indx">—— American, analysis of, <a href='#Page_207'>207</a></li> - -<li class="indx">—— and starch cements, <a href='#Page_222'>222</a>, <a href='#Page_223'>223</a></li> - -<li class="indx">—— as a binding agent, <a href='#Page_11'>11</a></li> - -<li class="indx">—— —— —— joining medium, <a href='#Page_10'>10</a>, <a href='#Page_11'>11</a></li> - -<li class="indx">—— banknote or mouth, <a href='#Page_269'>269</a></li> - -<li class="indx">—— boiler, Terne’s, <a href='#Page_51'>51</a>, <a href='#Page_52'>52</a></li> - -<li class="indx">—— boiling, boiler for, <a href='#Page_44'>44</a></li> - -<li class="indx">—— —— convenient apparatus for, <a href='#Page_46'>46</a>, <a href='#Page_47'>47</a></li> - -<li class="indx">—— —— in open jacketed pans, <a href='#Page_49'>49</a>, <a href='#Page_50'>50</a></li> - -<li class="indx">—— —— or cooking, <a href='#Page_44'>44</a>-52</li> - -<li class="indx">—— —— with steam, boiler for, <a href='#Page_47'>47</a>-49</li> - -<li class="indx">—— chemical composition of, <a href='#Page_8'>8</a></li> - -<li class="indx">—— chrome, <a href='#Page_153'>153</a></li> - -<li class="indx">—— clearness of, <a href='#Page_53'>53</a></li> - -<li class="indx">—— Cologne, <a href='#Page_148'>148</a></li> - -<li class="indx">—— color of, <a href='#Page_53'>53</a></li> - -<li class="indx">—— coloring of, <a href='#Page_156'>156</a></li> - -<li class="indx">—— constitution of, <a href='#Page_3'>3</a>-6</li> - -<li class="indx">—— conversion of cartilage into, <a href='#Page_94'>94</a>-104</li> - -<li class="indx">—— cooking, process of, <a href='#Page_51'>51</a></li> - -<li class="indx">—— crude, definition of, <a href='#Page_3'>3</a></li> - -<li class="indx">—— —— preparation of, <a href='#Page_43'>43</a></li> - -<li class="indx">—— cutting the, into cakes, <a href='#Page_57'>57</a>-64</li> - -<li class="indx">—— deduction of the quality of, from indirect properties, <a href='#Page_207'>207</a>, <a href='#Page_208'>208</a></li> - -<li class="indx">—— determination of acidity in, <a href='#Page_205'>205</a>, <a href='#Page_206'>206</a></li> - -<li class="indx">—— —— of adulterations of, <a href='#Page_214'>214</a>, <a href='#Page_215'>215</a></li> - -<li class="indx">—— —— of glutin in, <a href='#Page_206'>206</a>, <a href='#Page_207'>207</a></li> - -<li class="indx">—— —— of moisture in, <a href='#Page_205'>205</a></li> - -<li class="indx">—— different varieties of, and their preparation, <a href='#Page_146'>146</a>-164</li> - -<li class="indx">—— drying cakes of, <a href='#Page_64'>64</a>-73</li> - -<li class="indx">—— —— room for, <a href='#Page_65'>65</a></li> - -<li class="indx">—— factory, location of a, <a href='#Page_21'>21</a></li> - -<li class="indx">—— —— manner of carrying on the work in a, <a href='#Page_26'>26</a>-30</li> - -<li class="indx">—— fat and bone-meal, simultaneous utilization of bones for, <a href='#Page_104'>104</a>-113</li> - -<li class="indx">—— for attaching leather to metal, <a href='#Page_153'>153</a></li> - -<li class="indx">—— —— culinary and medicinal purposes, <a href='#Page_12'>12</a>-14</li> - -<li class="indx">—— —— elastic masses and as a partial substitute for rubber, <a href='#Page_14'>14</a></li> - -<li class="indx">—— —— fancy articles, <a href='#Page_14'>14</a>, <a href='#Page_15'>15</a></li> - -<li class="indx">Glue joints in leather driving belts, <a href='#Page_163'>163</a></li> - -<li class="indx">—— —— —— leather, paper, etc., <a href='#Page_153'>153</a>, <a href='#Page_154'>154</a></li> - -<li class="indx">—— —— —— parchment paper in making sausage skins, <a href='#Page_154'>154</a>, <a href='#Page_155'>155</a></li> - -<li class="indx">—— formation of, <a href='#Page_6'>6</a></li> - -<li class="indx">—— from various materials, external characteristics of, <a href='#Page_6'>6</a>, <a href='#Page_7'>7</a></li> - -<li class="indx">—— gilder’s, <a href='#Page_150'>150</a></li> - -<li class="indx">—— holding power of, <a href='#Page_147'>147</a>, <a href='#Page_148'>148</a></li> - -<li class="indx">—— how to make and use, <a href='#Page_147'>147</a></li> - -<li class="indx">—— in animal organism, <a href='#Page_2'>2</a></li> - -<li class="indx">—— —— sizing, <a href='#Page_12'>12</a></li> - -<li class="indx">—— inferior qualities of, <a href='#Page_12'>12</a></li> - -<li class="indx">—— joiner’s, <a href='#Page_146'>146</a></li> - -<li class="indx">—— Kissling’s results in testing, <a href='#Page_215'>215</a></li> - -<li class="indx">—— liquid, <a href='#Page_151'>151</a>, <a href='#Page_152'>152</a></li> - -<li class="indx">—— liquor, apparatus for clarifying, <a href='#Page_98'>98</a></li> - -<li class="indx">—— —— clarifying the, <a href='#Page_52'>52</a>-56</li> - -<li class="indx">—— —— concentration of, <a href='#Page_50'>50</a></li> - -<li class="indx">—— —— cooling of, <a href='#Page_100'>100</a></li> - -<li class="indx">—— —— decolorizing of, with animal charcoal, <a href='#Page_55'>55</a></li> - -<li class="indx">—— —— instrument for measuring the percentage of glue in, <a href='#Page_103'>103</a></li> - -<li class="indx">—— measuring the percentage of, in glue liquor, <a href='#Page_103'>103</a>, <a href='#Page_104'>104</a></li> - -<li class="indx">—— methods of bleaching, <a href='#Page_141'>141</a>-145</li> - -<li class="indx">—— moulding or forming of, <a href='#Page_56'>56</a>-64</li> - -<li class="indx">—— nature of, <a href='#Page_1'>1</a>-9</li> - -<li class="indx">—— nets for drying, <a href='#Page_66'>66</a>, <a href='#Page_67'>67</a></li> - -<li class="indx">—— ordinary, preparation of gelatine from, <a href='#Page_182'>182</a>, <a href='#Page_183'>183</a></li> - -<li class="indx">—— parchment, <a href='#Page_150'>150</a></li> - -<li class="indx">—— Paris, <a href='#Page_150'>150</a>, <a href='#Page_151'>151</a></li> - -<li class="indx">—— patent, <a href='#Page_150'>150</a></li> - -<li class="indx">—— practical testing of, <a href='#Page_215'>215</a>-217</li> - -<li class="indx">—— principal substances employed as raw material for, <a href='#Page_16'>16</a></li> - -<li class="indx">—— properties of, and its behavior towards other substances, <a href='#Page_6'>6</a>-9</li> - -<li class="indx">—— raw materials and their preparation for the manufacture of, <a href='#Page_16'>16</a>-38</li> - -<li class="indx">—— results obtained by comparative experiments in testing, <a href='#Page_209'>209</a>, <a href='#Page_210'>210</a></li> - -<li class="indx">—— Russian, <a href='#Page_149'>149</a>, <a href='#Page_150'>150</a></li> - -<li class="indx">—— size, <a href='#Page_150'>150</a></li> - -<li class="indx">—— solution, behavior of, towards salts, <a href='#Page_7'>7</a>, <a href='#Page_8'>8</a></li> - -<li class="indx">—— steam, <a href='#Page_152'>152</a></li> - -<li class="indx">—— stock, bleaching of, <a href='#Page_55'>55</a>, <a href='#Page_56'>56</a></li> - -<li class="indx">—— —— dry-limed, <a href='#Page_19'>19</a></li> - -<li class="indx">—— —— dry, uncured, or salted, <a href='#Page_19'>19</a></li> - -<li class="indx">—— —— green-limed, <a href='#Page_19'>19</a></li> - -<li class="indx">—— —— green-salted, <a href='#Page_19'>19</a></li> - -<li class="indx">—— —— influence of the age of animals on the product from, <a href='#Page_20'>20</a> -<span class="pagenum" id="Page_278">278</span></li> -<li class="indx">—— —— limed, washing of, <a href='#Page_21'>21</a>-26</li> - -<li class="indx">—— —— notes in reference to judging, <a href='#Page_19'>19</a>, <a href='#Page_20'>20</a></li> - -<li class="indx">—— —— preparation of, <a href='#Page_21'>21</a>-38</li> - -<li class="indx">—— —— preservation of, <a href='#Page_29'>29</a></li> - -<li class="indx">—— —— sheds for, <a href='#Page_26'>26</a></li> - -<li class="indx">—— —— transformation in boiling the, <a href='#Page_2'>2</a></li> - -<li class="indx">—— —— washer, <a href='#Page_22'>22</a>-26</li> - -<li class="indx">—— substitute for, <a href='#Page_203'>203</a>, <a href='#Page_204'>204</a></li> - -<li class="indx">—— transition stages of, <a href='#Page_2'>2</a></li> - -<li class="indx">—— uses of, <a href='#Page_10'>10</a>-15</li> - -<li class="indx">—— testing of, <a href='#Page_205'>205</a>-217</li> - -<li class="indx">—— tungstic, <a href='#Page_155'>155</a></li> - -<li class="indx">—— water-proof, <a href='#Page_160'>160</a></li> - -<li class="indx">—— yield of, from cartilage, <a href='#Page_115'>115</a></li> - -<li class="indx">—— —— —— from tannery waste, <a href='#Page_18'>18</a></li> - -<li class="indx">—— -yielding substance, production of, <a href='#Page_2'>2</a></li> - -<li class="indx">—— —— tissues, <a href='#Page_1'>1</a></li> - -<li class="indx">Glutin, conversion of chondrin into, <a href='#Page_6'>6</a></li> - -<li class="indx">—— determination of, in glue, <a href='#Page_206'>206</a>, <a href='#Page_207'>207</a></li> - -<li class="indx">—— formation of, <a href='#Page_3'>3</a></li> - -<li class="indx">—— properties of, <a href='#Page_4'>4</a>, <a href='#Page_5'>5</a></li> - -<li class="indx">—— pure, preparation of, <a href='#Page_4'>4</a></li> - -<li class="indx">Glycerine and glycerine cements, <a href='#Page_242'>242</a></li> - -<li class="indx">—— —— litharge cement, <a href='#Page_242'>242</a></li> - -<li class="indx">—— paste, <a href='#Page_266'>266</a></li> - -<li class="indx">—— —— for office use, <a href='#Page_268'>268</a></li> - -<li class="indx">—— properties of, <a href='#Page_242'>242</a></li> - -<li class="indx">Glycocoll, <a href='#Page_6'>6</a></li> - -<li class="indx">Goat leather, <a href='#Page_31'>31</a></li> - -<li class="indx">Gray lime, <a href='#Page_28'>28</a></li> - -<li class="indx">Green waste, liming of, <a href='#Page_26'>26</a>, <a href='#Page_27'>27</a></li> - -<li class="indx">Gum tragacanth, <a href='#Page_261'>261</a></li> - -<li class="indx">Gutta-percha and rubber cements, <a href='#Page_222'>222</a>, <a href='#Page_233'>233</a>-237</li> - -<li class="indx">Gypsum, <a href='#Page_244'>244</a></li> - -<li class="indx">Gypsum cements, <a href='#Page_244'>244</a>, <a href='#Page_245'>245</a></li> - - -<li class="ifrst">Hager’s diamond cement, <a href='#Page_229'>229</a></li> - -<li class="indx">Hard rubber cement, <a href='#Page_234'>234</a></li> - -<li class="indx">—— combs, cement for, <a href='#Page_236'>236</a></li> - -<li class="indx">Hare skins, <a href='#Page_18'>18</a>, <a href='#Page_31'>31</a></li> - -<li class="indx">Hartshorn, <a href='#Page_1'>1</a></li> - -<li class="indx">Hayes, S. Dana, analysis of American glue by, <a href='#Page_207'>207</a></li> - -<li class="indx">Heat-resisting cement, <a href='#Page_245'>245</a></li> - -<li class="indx">Hectograph mass, <a href='#Page_14'>14</a>, <a href='#Page_163'>163</a>, <a href='#Page_164'>164</a></li> - -<li class="indx">Heuzé’s method of preparing dextrine, <a href='#Page_261'>261</a></li> - -<li class="indx">Hide, transformation in drying the, <a href='#Page_2'>2</a></li> - -<li class="indx">Hides for glue-stock, classification of, <a href='#Page_30'>30</a>, <a href='#Page_31'>31</a></li> - -<li class="indx">—— soaking of, in chlorbarium, <a href='#Page_20'>20</a></li> - -<li class="indx">Hoeveller, W. A., apparatus for drying glue invented by, <a href='#Page_68'>68</a>-71</li> - -<li class="indx">—— glue-stock washer of, <a href='#Page_22'>22</a>-26</li> - -<li class="indx">Hog skins, <a href='#Page_18'>18</a></li> - -<li class="indx">Hollander, <a href='#Page_39'>39</a></li> - -<li class="indx">Horn, cement for, <a href='#Page_232'>232</a></li> - -<li class="indx">—— piths, <a href='#Page_19'>19</a></li> - -<li class="indx">Horses’ hoofs, cement for, <a href='#Page_236'>236</a></li> - -<li class="indx">Hudson Bay isinglass, <a href='#Page_199'>199</a></li> - -<li class="indx">Hydraulic works, cement for, <a href='#Page_241'>241</a></li> - -<li class="indx">Hydrocarbon vapors, extraction of fats, oils, etc., with, <a href='#Page_79'>79</a>-82</li> - -<li class="indx">Hydrocarbons, liquid, extraction of fats, oils, etc., with, <a href='#Page_82'>82</a>-84</li> - -<li class="indx">—— removal of, from substances, <a href='#Page_84'>84</a>-86</li> - -<li class="indx">Hydrochloric acid, treatment of bones with, <a href='#Page_37'>37</a></li> - -<li class="indx">—— —— utilization of the liquor obtained in treating bones with, <a href='#Page_125'>125</a>-127</li> - - -<li class="ifrst">Ichthyocolle Française, <a href='#Page_200'>200</a>, <a href='#Page_201'>201</a></li> - -<li class="indx">Irish moss, <a href='#Page_202'>202</a></li> - -<li class="indx">Iron and stone, cement for, <a href='#Page_245'>245</a></li> - -<li class="indx">—— cement for, <a href='#Page_245'>245</a>, <a href='#Page_246'>246</a></li> - -<li class="indx">—— cements, <a href='#Page_245'>245</a>-247</li> - -<li class="indx">—— pipes, fire-proof cement for, <a href='#Page_246'>246</a></li> - -<li class="indx">—— pots, cracked, cement for, <a href='#Page_246'>246</a></li> - -<li class="indx">—— water tanks, cement for, <a href='#Page_246'>246</a></li> - -<li class="indx">Isinglass, adulteration of, <a href='#Page_196'>196</a>, <a href='#Page_197'>197</a></li> - -<li class="indx">—— and its substitutes, <a href='#Page_196'>196</a>-204</li> - -<li class="indx">—— chemical composition of, <a href='#Page_8'>8</a></li> - -<li class="indx">—— preparation of, in Russia, <a href='#Page_197'>197</a>, <a href='#Page_198'>198</a></li> - -<li class="indx">—— sources of, <a href='#Page_196'>196</a></li> - -<li class="indx">—— spurious, <a href='#Page_196'>196</a></li> - -<li class="indx">—— substitute for, <a href='#Page_203'>203</a>, <a href='#Page_204'>204</a></li> - -<li class="indx">Isinglassine, <a href='#Page_201'>201</a></li> - -<li class="indx">Ivory, cement for, <a href='#Page_230'>230</a></li> - - -<li class="ifrst">Jeffrey’s marine glue, <a href='#Page_235'>235</a></li> - -<li class="indx">Jelly, definition of, <a href='#Page_3'>3</a></li> - -<li class="indx">—— effect of tannin on, <a href='#Page_8'>8</a></li> - -<li class="indx">—— machines for cutting the, into cakes, <a href='#Page_60'>60</a>-64</li> - -<li class="indx">—— properties of, <a href='#Page_7'>7</a></li> - -<li class="indx">—— tools for cutting the, into cakes, <a href='#Page_59'>59</a></li> - -<li class="indx">—— transformation in boiling the, <a href='#Page_2'>2</a></li> - -<li class="indx">Jennings’ method for the preparation of fish glue, <a href='#Page_202'>202</a>, <a href='#Page_203'>203</a></li> - -<li class="indx">Jewelers, American cement for, <a href='#Page_252'>252</a></li> - -<li class="indx">—— cement, <a href='#Page_252'>252</a></li> - -<li class="indx">Joiners, cement for, <a href='#Page_243'>243</a></li> - -<li class="indx">—— glue, <a href='#Page_146'>146</a></li> - -<li class="indx">Jullion and Pirie’s process for the preparation of gelatine, <a href='#Page_38'>38</a> - - -<span class="pagenum" id="Page_279">279</span></li> - - -<li class="ifrst">Kid leather, waste from paring, <a href='#Page_31'>31</a></li> - -<li class="indx">Kiln for burning bones, <a href='#Page_117'>117</a>-119</li> - -<li class="indx">Kissling’s results in testing glue, <a href='#Page_215'>215</a></li> - -<li class="indx">Knapsack leather, <a href='#Page_31'>31</a></li> - -<li class="indx">Knife handles, cement for, <a href='#Page_231'>231</a></li> - - -<li class="ifrst">Label paste, <a href='#Page_263'>263</a></li> - -<li class="indx">Labels, mucilage for, <a href='#Page_263'>263</a></li> - -<li class="indx">—— paste for attaching, to glass, porcelain and metal, <a href='#Page_270'>270</a></li> - -<li class="indx">—— —— for attaching, to polished nickel, <a href='#Page_268'>268</a></li> - -<li class="indx">—— —— for attaching, to tin, <a href='#Page_268'>268</a></li> - -<li class="indx">Lamb leather, <a href='#Page_31'>31</a></li> - -<li class="indx">Leaf isinglass, <a href='#Page_197'>197</a></li> - -<li class="indx">Leather, cement for, <a href='#Page_235'>235</a>, <a href='#Page_237'>237</a></li> - -<li class="indx">—— driving belts, glue for joints in, <a href='#Page_163'>163</a></li> - -<li class="indx">—— for glue-stock, classification of, <a href='#Page_30'>30</a>, <a href='#Page_31'>31</a></li> - -<li class="indx">—— glue for, <a href='#Page_153'>153</a>, <a href='#Page_154'>154</a></li> - -<li class="indx">—— —— —— attaching, to metal, <a href='#Page_153'>153</a></li> - -<li class="indx">—— paste for attaching, to table tops, <a href='#Page_269'>269</a></li> - -<li class="indx">—— —— —— joining, to pasteboard, <a href='#Page_267'>267</a>, <a href='#Page_268'>268</a></li> - -<li class="indx">—— skins, actual, <a href='#Page_17'>17</a></li> - -<li class="indx">—— waste, <a href='#Page_39'>39</a>-42</li> - -<li class="indx">—— —— comminution of, <a href='#Page_39'>39</a>, <a href='#Page_40'>40</a></li> - -<li class="indx">Leucine, <a href='#Page_6'>6</a></li> - -<li class="indx">Leuner’s apparatus for extracting bones, <a href='#Page_90'>90</a>-92</li> - -<li class="indx">Lime and glue cement, <a href='#Page_244'>244</a></li> - -<li class="indx">—— —— sugar paste, <a href='#Page_265'>265</a></li> - -<li class="indx">—— bath for bones, <a href='#Page_37'>37</a></li> - -<li class="indx">—— cements, <a href='#Page_223'>223</a>, <a href='#Page_243'>243</a>, <a href='#Page_244'>244</a></li> - -<li class="indx">—— milk of, preparation of, <a href='#Page_26'>26</a>, <a href='#Page_27'>27</a></li> - -<li class="indx">—— precipitation of, by oxalic acid, <a href='#Page_54'>54</a></li> - -<li class="indx">—— slaked, effect of, on glue solution, <a href='#Page_7'>7</a></li> - -<li class="indx">—— testing of, <a href='#Page_27'>27</a>, <a href='#Page_28'>28</a></li> - -<li class="indx">Limed glue-stock, washing of, <a href='#Page_21'>21</a>-26</li> - -<li class="indx">Liming green waste, <a href='#Page_26'>26</a>, <a href='#Page_27'>27</a></li> - -<li class="indx">—— waste, <a href='#Page_20'>20</a></li> - -<li class="indx">Linseed oil and clay cement, <a href='#Page_248'>248</a></li> - -<li class="indx">—— —— —— manganese cement, <a href='#Page_248'>248</a></li> - -<li class="indx">Lipowitz’s method of testing glue, <a href='#Page_208'>208</a>, <a href='#Page_209'>209</a></li> - -<li class="indx">Liquid fining gelatine, <a href='#Page_182'>182</a></li> - -<li class="indx">—— glue, <a href='#Page_151'>151</a>, <a href='#Page_152'>152</a></li> - -<li class="indx">—— sugar and lime paste, <a href='#Page_265'>265</a></li> - -<li class="indx">Litharge cement, <a href='#Page_225'>225</a></li> - - -<li class="ifrst">Magnesium sulphate, <a href='#Page_116'>116</a></li> - -<li class="indx">Manufacture of bone-glue, <a href='#Page_74'>74</a>-116</li> - -<li class="indx">—— —— gelatine, and products prepared from it, <a href='#Page_165'>165</a>-195</li> - -<li class="indx">—— —— phosphorus, <a href='#Page_117'>117</a>-140</li> - -<li class="indx">—— —— skin glue, <a href='#Page_43'>43</a>-73</li> - -<li class="indx">Maps, paste for mounting, <a href='#Page_266'>266</a></li> - -<li class="indx">Marble, cement for, <a href='#Page_242'>242</a>, <a href='#Page_251'>251</a></li> - -<li class="indx">—— —— for attaching metal letters to, <a href='#Page_249'>249</a></li> - -<li class="indx">—— oil cement for, <a href='#Page_228'>228</a>, <a href='#Page_229'>229</a></li> - -<li class="indx">Marine glue, <a href='#Page_234'>234</a>, <a href='#Page_235'>235</a></li> - -<li class="indx">Matches, use of glue in the manufacture of, <a href='#Page_11'>11</a></li> - -<li class="indx">Mastic, <a href='#Page_226'>226</a>, <a href='#Page_227'>227</a></li> - -<li class="indx">—— cement, <a href='#Page_226'>226</a>, <a href='#Page_227'>227</a></li> - -<li class="indx">Medicinal purposes, glue for, <a href='#Page_12'>12</a>-14</li> - -<li class="indx">Meerschaum, cement for, <a href='#Page_239'>239</a></li> - -<li class="indx">Meta-gelatin, <a href='#Page_7'>7</a></li> - -<li class="indx">Metal, cement for attaching wood, glass, etc., to, <a href='#Page_251'>251</a></li> - -<li class="indx">—— glue for attaching leather to, <a href='#Page_153'>153</a></li> - -<li class="indx">—— letters upon glass, cement for, <a href='#Page_230'>230</a>, <a href='#Page_249'>249</a></li> - -<li class="indx">—— paste for attaching labels to, <a href='#Page_270'>270</a></li> - -<li class="indx">Metals, cement for, <a href='#Page_239'>239</a></li> - -<li class="indx">—— —— for uniting, <a href='#Page_241'>241</a></li> - -<li class="indx">Metarabin, conversion of, into arabin, <a href='#Page_271'>271</a></li> - -<li class="indx">Mica, cement for, <a href='#Page_231'>231</a>, <a href='#Page_232'>232</a></li> - -<li class="indx">Milk of lime, preparation of, <a href='#Page_26'>26</a>, <a href='#Page_27'>27</a></li> - -<li class="indx">Moisture, determination of, in glue, <a href='#Page_205'>205</a></li> - -<li class="indx">Mother-of-pearl, glue imitations of, <a href='#Page_15'>15</a></li> - -<li class="indx">Moulding boxes, <a href='#Page_56'>56</a></li> - -<li class="indx">—— or forming the glue, <a href='#Page_56'>56</a>-64</li> - -<li class="indx">—— refined phosphorus, <a href='#Page_135'>135</a>-137</li> - -<li class="indx">Mouth glue, <a href='#Page_269'>269</a></li> - -<li class="indx">Mucilage, <a href='#Page_263'>263</a>, <a href='#Page_264'>264</a></li> - -<li class="indx">—— caseine, <a href='#Page_264'>264</a></li> - -<li class="indx">—— —— for photographers’ use, <a href='#Page_266'>266</a></li> - -<li class="indx">—— dextrine, <a href='#Page_267'>267</a></li> - -<li class="indx">—— for attaching labels to tin, <a href='#Page_268'>268</a></li> - -<li class="indx">—— —— labels, <a href='#Page_263'>263</a></li> - -<li class="indx">—— —— office use, <a href='#Page_268'>268</a></li> - -<li class="indx">—— —— postage stamps, <a href='#Page_264'>264</a></li> - -<li class="indx">—— preservation of, <a href='#Page_259'>259</a>, <a href='#Page_260'>260</a></li> - -<li class="indx">—— strong, <a href='#Page_267'>267</a></li> - -<li class="indx">—— tragacanth, <a href='#Page_264'>264</a></li> - -<li class="indx">Mucilages and pastes, <a href='#Page_255'>255</a>-271</li> - -<li class="indx">—— —— —— for special purposes, <a href='#Page_261'>261</a>-271</li> - -<li class="indx">—— —— pastes and cements, preparation of, <a href='#Page_224'>224</a>-271</li> - -<li class="indx">Muratori and Landry’s method of water-proofing fabrics, <a href='#Page_162'>162</a>, <a href='#Page_163'>163</a></li> - -<li class="indx">Muzmann and Krakowitzer’s method of water-proofing fabrics, <a href='#Page_162'>162</a>, <a href='#Page_163'>163</a></li> - - -<li class="ifrst">Nature of glue, <a href='#Page_1'>1</a>-9</li> - -<li class="indx">Nelson, G., process of, for the manufacture of gelatine, <a href='#Page_166'>166</a> -<span class="pagenum" id="Page_280">280</span></li> -<li class="indx">Nets for drying glue, <a href='#Page_66'>66</a>, <a href='#Page_67'>67</a></li> - -<li class="indx">Netting, metallic, <a href='#Page_66'>66</a></li> - -<li class="indx">—— twine, <a href='#Page_66'>66</a>, <a href='#Page_67'>67</a></li> - -<li class="indx">Neutral potassium tartrate, behavior of glue solution towards, <a href='#Page_7'>7</a></li> - -<li class="indx">New York isinglass, <a href='#Page_198'>198</a></li> - -<li class="indx">Nickel, polished, paste for attaching labels to, <a href='#Page_268'>268</a></li> - -<li class="indx">North American isinglass, <a href='#Page_198'>198</a></li> - - -<li class="ifrst">Office use, glycerine paste for, <a href='#Page_268'>268</a></li> - -<li class="indx">—— —— mucilage for, <a href='#Page_268'>268</a></li> - -<li class="indx">Oil cements, <a href='#Page_219'>219</a>, <a href='#Page_220'>220</a>, <a href='#Page_224'>224</a>-229</li> - -<li class="indx">Oils, extraction of, with hydrocarbon vapors, <a href='#Page_79'>79</a>-82</li> - -<li class="indx">—— —— —— with liquid hydrocarbons, <a href='#Page_82'>82</a>-84</li> - -<li class="indx">Ornaments, indestructible mass for, <a href='#Page_155'>155</a></li> - -<li class="indx">Osseine, <a href='#Page_1'>1</a></li> - -<li class="indx">Oxalic acid, effect of, on glue solution, <a href='#Page_7'>7</a></li> - -<li class="indx">—— —— precipitation of lime by, <a href='#Page_54'>54</a></li> - - -<li class="ifrst">Pads, paste for, <a href='#Page_270'>270</a></li> - -<li class="indx">Paget’s mastic, <a href='#Page_227'>227</a></li> - -<li class="indx">Pale steam glue, <a href='#Page_152'>152</a></li> - -<li class="indx">Pan, open evaporating, <a href='#Page_98'>98</a>-100</li> - -<li class="indx">Pans, evaporating, <a href='#Page_124'>124</a></li> - -<li class="indx">—— open jacketed, <a href='#Page_49'>49</a>, <a href='#Page_50'>50</a></li> - -<li class="indx">—— vacuum, <a href='#Page_101'>101</a>-103</li> - -<li class="indx">Paper bags, paste for, <a href='#Page_266'>266</a></li> - -<li class="indx">—— colored, use of glue in the manufacture of, <a href='#Page_11'>11</a></li> - -<li class="indx">—— glue for, <a href='#Page_153'>153</a>, <a href='#Page_154'>154</a></li> - -<li class="indx">—— hangings, glue in the manufacture of, <a href='#Page_11'>11</a></li> - -<li class="indx">—— paste for, <a href='#Page_265'>265</a></li> - -<li class="indx">—— —— —— fastening, on tin-foil, <a href='#Page_266'>266</a>, <a href='#Page_270'>270</a></li> - -<li class="indx">Parchment glue, <a href='#Page_150'>150</a></li> - -<li class="indx">—— paper, glue for, in making sausage skins, <a href='#Page_154'>154</a>, <a href='#Page_155'>155</a></li> - -<li class="indx">—— scraps, <a href='#Page_18'>18</a></li> - -<li class="indx">Paris glue, <a href='#Page_150'>150</a>, <a href='#Page_151'>151</a></li> - -<li class="indx">Paste, adhesive, <a href='#Page_264'>264</a></li> - -<li class="indx">—— albumen, <a href='#Page_265'>265</a>, <a href='#Page_266'>266</a></li> - -<li class="indx">—— clean and durable, <a href='#Page_268'>268</a>, <a href='#Page_269'>269</a></li> - -<li class="indx">—— elastic or pliable, <a href='#Page_263'>263</a></li> - -<li class="indx">—— fluid, <a href='#Page_264'>264</a>, <a href='#Page_265'>265</a></li> - -<li class="indx">—— for attaching cloth or leather to table tops, <a href='#Page_269'>269</a></li> - -<li class="indx">—— —— —— labels to glass, porcelain and metal, <a href='#Page_270'>270</a></li> - -<li class="indx">—— —— —— —— to polished nickel, <a href='#Page_268'>268</a></li> - -<li class="indx">—— —— cardboard, <a href='#Page_269'>269</a></li> - -<li class="indx">—— —— fastening paper on tin foil, <a href='#Page_266'>266</a>, <a href='#Page_270'>270</a></li> - -<li class="indx">—— —— joining leather to pasteboard, <a href='#Page_267'>267</a>, <a href='#Page_268'>268</a></li> - -<li class="indx">—— —— mounting maps, <a href='#Page_266'>266</a></li> - -<li class="indx">—— —— pads, <a href='#Page_270'>270</a></li> - -<li class="indx">—— —— paper and fine fancy articles, <a href='#Page_265'>265</a></li> - -<li class="indx">—— —— —— bags, <a href='#Page_266'>266</a></li> - -<li class="indx">—- —— scrap-books, <a href='#Page_266'>266</a>, <a href='#Page_267'>267</a></li> - -<li class="indx">—— —— skins, <a href='#Page_267'>267</a></li> - -<li class="indx">—— glycerine, <a href='#Page_266'>266</a></li> - -<li class="indx">—— —— for office use, <a href='#Page_268'>268</a></li> - -<li class="indx">—— label, <a href='#Page_263'>263</a></li> - -<li class="indx">—— preparation of, <a href='#Page_255'>255</a></li> - -<li class="indx">—— preservatives for, <a href='#Page_257'>257</a></li> - -<li class="indx">—— rules to be observed in the preparation of, <a href='#Page_256'>256</a></li> - -<li class="indx">—— strong adhesive, <a href='#Page_262'>262</a></li> - -<li class="indx">—— sugar and lime, <a href='#Page_265'>265</a></li> - -<li class="indx">—— that will not sour, <a href='#Page_262'>262</a></li> - -<li class="indx">—— Venetian, <a href='#Page_262'>262</a></li> - -<li class="indx">Paste-board, paste for joining leather to, <a href='#Page_267'>267</a>, <a href='#Page_268'>268</a></li> - -<li class="indx">Pastes and mucilages, <a href='#Page_255'>255</a>-271</li> - -<li class="indx">—— —— —— for special purposes, <a href='#Page_261'>261</a>-271</li> - -<li class="indx">—— mucilages and cements, preparation of, <a href='#Page_224'>224</a>-271</li> - -<li class="indx">Patent glue, <a href='#Page_150'>150</a></li> - -<li class="indx">Patriarch isinglass, <a href='#Page_197'>197</a></li> - -<li class="indx">Permanent white, addition of, to glue, <a href='#Page_149'>149</a></li> - -<li class="indx">Petroleum, cement to withstand the action of, <a href='#Page_231'>231</a></li> - -<li class="indx">—— lamps, cement for, <a href='#Page_231'>231</a></li> - -<li class="indx">Phosphates, extraction of, from bones, <a href='#Page_115'>115</a></li> - -<li class="indx">Phosphorus, crude, composition of, <a href='#Page_131'>131</a>, <a href='#Page_132'>132</a></li> - -<li class="indx">—— —— distillation of, <a href='#Page_133'>133</a>-135</li> - -<li class="indx">—— —— purification of, <a href='#Page_132'>132</a></li> - -<li class="indx">—— distillation of, <a href='#Page_127'>127</a>-132</li> - -<li class="indx">—— galley furnace for distilling, <a href='#Page_128'>128</a>, <a href='#Page_129'>129</a></li> - -<li class="indx">—— loss of, <a href='#Page_132'>132</a></li> - -<li class="indx">—— manufacture of, <a href='#Page_117'>117</a>-140</li> - -<li class="indx">—— —— of, with the assistance of electricity, <a href='#Page_138'>138</a>-140</li> - -<li class="indx">—— operations in the preparation of, <a href='#Page_117'>117</a></li> - -<li class="indx">—— refined, moulding of, <a href='#Page_135'>135</a>-137</li> - -<li class="indx">—— refining and purifying of, <a href='#Page_132'>132</a>-135</li> - -<li class="indx">—— receivers for, <a href='#Page_129'>129</a></li> - -<li class="indx">—— removal of, from the receivers, <a href='#Page_131'>131</a></li> - -<li class="indx">—— residue in the manufacture of, <a href='#Page_127'>127</a></li> - -<li class="indx">—— sticks, mode of forming, <a href='#Page_135'>135</a>-137</li> - -<li class="indx">—— storing of, <a href='#Page_138'>138</a></li> - -<li class="indx">Photographers, caseine mucilage for <a href='#Page_266'>266</a></li> - -<li class="indx">Photographic printing, gelatine for <a href='#Page_183'>183</a>, <a href='#Page_184'>184</a> -<span class="pagenum" id="Page_281">281</span></li> -<li class="indx">Photo-lithography, use of glue in, <a href='#Page_14'>14</a></li> - -<li class="indx">Pierres de mastic, <a href='#Page_226'>226</a>, <a href='#Page_227'>227</a></li> - -<li class="indx">Pipes exposed to a red heat, cement for tightening joints of, <a href='#Page_241'>241</a></li> - -<li class="indx">Plaster of Paris, <a href='#Page_244'>244</a></li> - -<li class="indx">—— —— —— cement, universal, <a href='#Page_245'>245</a></li> - -<li class="indx">—— —— —— statues, cement for, <a href='#Page_244'>244</a>, <a href='#Page_245'>245</a></li> - -<li class="indx">Pliable paste, <a href='#Page_263'>263</a></li> - -<li class="indx">Porcelain, cement for, <a href='#Page_231'>231</a>, <a href='#Page_239'>239</a>, <a href='#Page_240'>240</a>, <a href='#Page_241'>241</a>, <a href='#Page_243'>243</a>, <a href='#Page_245'>245</a></li> - -<li class="indx">—— oil cement for, <a href='#Page_229'>229</a></li> - -<li class="indx">—— paste for attaching labels to, <a href='#Page_270'>270</a></li> - -<li class="indx">—— sulphur cement for, <a href='#Page_232'>232</a>, <a href='#Page_233'>233</a></li> - -<li class="indx">Postage stamps, mucilage for, <a href='#Page_264'>264</a></li> - -<li class="indx">Potassium carbonate, behavior of glue solution towards, <a href='#Page_7'>7</a></li> - -<li class="indx">Printing rollers, compositions for, <a href='#Page_157'>157</a></li> - -<li class="indx">Putty, <a href='#Page_224'>224</a>, <a href='#Page_225'>225</a></li> - - -<li class="ifrst">Quick lime, <a href='#Page_243'>243</a></li> - - -<li class="ifrst">Rabbit skins, <a href='#Page_18'>18</a>, <a href='#Page_31'>31</a></li> - -<li class="indx">Rag-engine, <a href='#Page_39'>39</a></li> - -<li class="indx">Raw materials and their preparation for the manufacture of glue, <a href='#Page_16'>16</a>-38</li> - -<li class="indx">—— —— collection and buying of, <a href='#Page_16'>16</a></li> - -<li class="indx">—— —— division of, <a href='#Page_16'>16</a></li> - -<li class="indx">Receivers for collecting phosphorus, <a href='#Page_129'>129</a></li> - -<li class="indx">—— —— removal of phosphorus from the, <a href='#Page_131'>131</a></li> - -<li class="indx">Red lead cement, <a href='#Page_225'>225</a></li> - -<li class="indx">Resinous cements, <a href='#Page_220'>220</a>, <a href='#Page_221'>221</a>, <a href='#Page_229'>229</a>-233</li> - -<li class="indx">Retort-furnace, Belgian, for the carbonization of bones, <a href='#Page_109'>109</a>-112</li> - -<li class="indx">Retorts, <a href='#Page_127'>127</a>, <a href='#Page_128'>128</a></li> - -<li class="indx">Rochelle salts, behavior of glue solution towards, <a href='#Page_7'>7</a></li> - -<li class="indx">Rubber and gutta-percha cements, <a href='#Page_222'>222</a>, <a href='#Page_233'>233</a>-237</li> - -<li class="indx">—— cement for, <a href='#Page_250'>250</a></li> - -<li class="indx">—— —— —— chemical apparatus, <a href='#Page_248'>248</a>, <a href='#Page_249'>249</a></li> - -<li class="indx">—— glue as a partial substitute for, <a href='#Page_14'>14</a></li> - -<li class="indx">Russia, preparation of isinglass in, <a href='#Page_197'>197</a>, <a href='#Page_198'>198</a></li> - -<li class="indx">Russian glue, <a href='#Page_149'>149</a>, <a href='#Page_150'>150</a></li> - -<li class="indx">—— isinglass, <a href='#Page_197'>197</a>, <a href='#Page_198'>198</a></li> - -<li class="indx">—— steam glue, <a href='#Page_152'>152</a></li> - - -<li class="ifrst">Sahlstrom’s process for preparing a substitute for isinglass, gelatine and glue, <a href='#Page_203'>203</a>, <a href='#Page_204'>204</a></li> - -<li class="indx">Sal ammoniac, effect of, on glue solution, <a href='#Page_7'>7</a></li> - -<li class="indx">Saltpetre, effect of, on glue solution, <a href='#Page_7'>7</a></li> - -<li class="indx">Salts, behavior of glue solution towards, <a href='#Page_7'>7</a>, <a href='#Page_8'>8</a></li> - -<li class="indx">Samovey leaf isinglass, <a href='#Page_197'>197</a></li> - -<li class="indx">Sandpaper, use of glue in the manufacture of, <a href='#Page_12'>12</a></li> - -<li class="indx">Sausage skins, glue for parchment paper in making, <a href='#Page_154'>154</a>, <a href='#Page_155'>155</a></li> - -<li class="indx">Scheibler’s cement for chemical apparatus, <a href='#Page_249'>249</a></li> - -<li class="indx">Schneible, J., machine for cutting the jelly into cakes invented by, <a href='#Page_60'>60</a>-62</li> - -<li class="indx">Scrap-books, paste for, <a href='#Page_266'>266</a>, <a href='#Page_267'>267</a></li> - -<li class="indx">Selenite, <a href='#Page_244'>244</a></li> - -<li class="indx">Seltsam’s apparatus for extracting bones, <a href='#Page_84'>84</a>-86</li> - -<li class="indx">—— —— for extracting bones improved by Th. Richter, <a href='#Page_88'>88</a>-90</li> - -<li class="indx">Serbat’s mastic, <a href='#Page_227'>227</a>, <a href='#Page_228'>228</a></li> - -<li class="indx">Seubert’s apparatus for moulding phosphorus, <a href='#Page_135'>135</a>, <a href='#Page_136'>136</a></li> - -<li class="indx">Sheds for glue-stock, <a href='#Page_26'>26</a></li> - -<li class="indx">Sheep leather, <a href='#Page_31'>31</a></li> - -<li class="indx">—— skin waste, <a href='#Page_18'>18</a></li> - -<li class="indx">Shell lime, <a href='#Page_28'>28</a></li> - -<li class="indx">Shoemakers’ paste, <a href='#Page_258'>258</a>, <a href='#Page_259'>259</a></li> - -<li class="indx">Siberian purse isinglass, <a href='#Page_197'>197</a></li> - -<li class="indx">Sieve for sorting crushed bones, <a href='#Page_36'>36</a>, <a href='#Page_37'>37</a></li> - -<li class="indx">Silicate of soda, <a href='#Page_240'>240</a></li> - -<li class="indx">Silk, artificial, from gelatine, <a href='#Page_195'>195</a></li> - -<li class="indx">Sinews, <a href='#Page_1'>1</a></li> - -<li class="indx">Size, <a href='#Page_157'>157</a>-160</li> - -<li class="indx">—— glue, <a href='#Page_150'>150</a></li> - -<li class="indx">Sizing, glue in, <a href='#Page_12'>12</a></li> - -<li class="indx">Skin gelatine, <a href='#Page_166'>166</a>-170</li> - -<li class="indx">—— —— modern process of preparing, <a href='#Page_167'>167</a>-170</li> - -<li class="indx">—— glue, classification of operations in the manufacture of, <a href='#Page_43'>43</a></li> - -<li class="indx">—— —— manufacture of, <a href='#Page_43'>43</a>-73</li> - -<li class="indx">—— -like raw materials, <a href='#Page_16'>16</a></li> - -<li class="indx">Skins, paste for, <a href='#Page_267'>267</a></li> - -<li class="indx">—— steeping of, <a href='#Page_18'>18</a></li> - -<li class="indx">—— used for packing, use of, for glue, <a href='#Page_19'>19</a></li> - -<li class="indx">Sodium carbonate, behavior of glue solution towards, <a href='#Page_7'>7</a></li> - -<li class="indx">Soft putty, <a href='#Page_225'>225</a></li> - -<li class="indx">—— rubber cement, <a href='#Page_233'>233</a>, <a href='#Page_234'>234</a></li> - -<li class="indx">Sounds, <a href='#Page_41'>41</a></li> - -<li class="indx">Spiral evaporators, <a href='#Page_100'>100</a>, <a href='#Page_101'>101</a></li> - -<li class="indx">Stamping mill for crushing bones, <a href='#Page_34'>34</a>, <a href='#Page_35'>35</a></li> - -<li class="indx">Staple isinglass, <a href='#Page_197'>197</a></li> - -<li class="indx">Starch and glue cements, <a href='#Page_222'>222</a>, <a href='#Page_223'>223</a></li> - -<li class="indx">—— paste, <a href='#Page_255'>255</a>, <a href='#Page_256'>256</a>, <a href='#Page_261'>261</a></li> - -<li class="indx">Steam, apparatus for boiling glue with, <a href='#Page_47'>47</a>-49 -<span class="pagenum" id="Page_282">282</span></li> -<li class="indx">Steam boiler cement, <a href='#Page_250'>250</a></li> - -<li class="indx">—— glue, <a href='#Page_152'>152</a></li> - -<li class="indx">—— high-pressure, treatment of bones with, <a href='#Page_105'>105</a>-107</li> - -<li class="indx">—— pipes, cement for, <a href='#Page_250'>250</a>, <a href='#Page_251'>251</a></li> - -<li class="indx">—— —— oil cement free from lead for, <a href='#Page_228'>228</a></li> - -<li class="indx">—— —— —— cements for, <a href='#Page_228'>228</a></li> - -<li class="indx">Steaming bones, <a href='#Page_75'>75</a>, <a href='#Page_76'>76</a></li> - -<li class="indx">Stephenson’s oil cement, <a href='#Page_228'>228</a></li> - -<li class="indx">Stick mastic cement, <a href='#Page_232'>232</a></li> - -<li class="indx">Stone lime, <a href='#Page_28'>28</a></li> - -<li class="indx">Stove plates, cracked, cement for, <a href='#Page_246'>246</a></li> - -<li class="indx">Stoves, black cement for, <a href='#Page_246'>246</a></li> - -<li class="indx">Stratena, <a href='#Page_252'>252</a></li> - -<li class="indx">Straw, use of, as a filter, <a href='#Page_44'>44</a></li> - -<li class="indx">Sugar and lime paste, <a href='#Page_265'>265</a></li> - -<li class="indx">Sulphate of alumina, use of, for clarifying glue liquor, <a href='#Page_54'>54</a></li> - -<li class="indx">—— —— baryta, addition of, to glue, <a href='#Page_149'>149</a></li> - -<li class="indx">Sulphuric acid, decomposition of bone ash by, <a href='#Page_119'>119</a>-125</li> - -<li class="indx">Sulphurous acid, absorption of, by bones, <a href='#Page_92'>92</a></li> - -<li class="indx">—— —— bleaching glue with, <a href='#Page_143'>143</a>-145</li> - -<li class="indx">—— —— glue-stock with, <a href='#Page_55'>55</a>, <a href='#Page_56'>56</a></li> - -<li class="indx">—— —— dilute, treatment of bones with, <a href='#Page_38'>38</a></li> - -<li class="indx">—— —— generation of, <a href='#Page_93'>93</a>, <a href='#Page_94'>94</a></li> - -<li class="indx">—— —— process for extracting bones, <a href='#Page_92'>92</a>-94</li> - -<li class="indx">—— —— solution, apparatus for the production of, <a href='#Page_143'>143</a>, <a href='#Page_144'>144</a></li> - -<li class="indx">Surrons, <a href='#Page_31'>31</a></li> - -<li class="indx">Swinborne’s improved patented process for the preparation of gelatine, <a href='#Page_167'>167</a></li> - - -<li class="ifrst">Table tops, paste for attaching cloth or leather to, <a href='#Page_269'>269</a></li> - -<li class="indx">Tannery waste, yield of glue from, <a href='#Page_18'>18</a></li> - -<li class="indx">Tannin as a test for the presence of gelatine, <a href='#Page_165'>165</a></li> - -<li class="indx">—— effect of, on glue solution, <a href='#Page_8'>8</a></li> - -<li class="indx">—— removal of, from leather waste, <a href='#Page_39'>39</a>-41</li> - -<li class="indx">Tendons, <a href='#Page_1'>1</a></li> - -<li class="indx">Terne’s apparatus for the generation of sulphurous acid, <a href='#Page_94'>94</a></li> - -<li class="indx">—— glue boiler, <a href='#Page_51'>51</a>, <a href='#Page_52'>52</a></li> - -<li class="indx">Terra-cotta articles, cement for, <a href='#Page_232'>232</a></li> - -<li class="indx">Testing glue and gelatine, <a href='#Page_205'>205</a>-217</li> - -<li class="indx">Tin foil, paste for fastening paper on, <a href='#Page_266'>266</a>, <a href='#Page_270'>270</a></li> - -<li class="indx">Tin paste for attaching labels to, <a href='#Page_268'>268</a></li> - -<li class="indx">Tires, cement for, <a href='#Page_250'>250</a></li> - -<li class="indx">Tools for cutting the jelly into cakes, <a href='#Page_59'>59</a></li> - -<li class="indx">Tortoise shell, cement for, <a href='#Page_232'>232</a></li> - -<li class="indx">—— —— glue imitations of, <a href='#Page_15'>15</a></li> - -<li class="indx">Toys indestructible mass for, <a href='#Page_155'>155</a></li> - -<li class="indx">Tragacanth, <a href='#Page_261'>261</a></li> - -<li class="indx">—— mucilage, <a href='#Page_264'>264</a></li> - -<li class="indx">Transition stages of glue, <a href='#Page_2'>2</a>, <a href='#Page_3'>3</a></li> - -<li class="indx">Tub-size, manufacture of, <a href='#Page_158'>158</a>, <a href='#Page_159'>159</a></li> - -<li class="indx">Tungstic glue, <a href='#Page_155'>155</a></li> - -<li class="indx">Turners, cement for, <a href='#Page_229'>229</a>, <a href='#Page_230'>230</a></li> - -<li class="indx">Twine netting, objections to, <a href='#Page_66'>66</a>, <a href='#Page_67'>67</a></li> - - -<li class="ifrst">Under skin, <a href='#Page_17'>17</a></li> - -<li class="indx">Uses of glue, <a href='#Page_10'>10</a>-15</li> - - -<li class="ifrst">Vacuum pans, <a href='#Page_101'>101</a>-103</li> - -<li class="indx">Vasa lymphatica, <a href='#Page_1'>1</a></li> - -<li class="indx">Vats, clarifying, <a href='#Page_53'>53</a></li> - -<li class="indx">Veneers, gelatine, <a href='#Page_15'>15</a>, <a href='#Page_186'>186</a>-193</li> - -<li class="indx">Venetian paste, <a href='#Page_262'>262</a></li> - - -<li class="ifrst">Walls, damp, marine glue for, <a href='#Page_235'>235</a></li> - -<li class="indx">Wash basins, cement for, <a href='#Page_225'>225</a>, <a href='#Page_226'>226</a></li> - -<li class="indx">Washing drum, <a href='#Page_22'>22</a></li> - -<li class="indx">Waste, green, liming of, <a href='#Page_26'>26</a>, <a href='#Page_27'>27</a></li> - -<li class="indx">—— liming of, <a href='#Page_20'>20</a></li> - -<li class="indx">—— putrefaction of, <a href='#Page_20'>20</a>, <a href='#Page_21'>21</a></li> - -<li class="indx">Water-glass and water-glass cements, <a href='#Page_240'>240</a>-242</li> - -<li class="indx">—— —— constitution of, <a href='#Page_240'>240</a></li> - -<li class="indx">Water-proof cement, <a href='#Page_227'>227</a></li> - -<li class="indx">—— —— glue, <a href='#Page_160'>160</a></li> - -<li class="indx">—— proofing fabrics, <a href='#Page_161'>161</a>-163</li> - -<li class="indx">—— —— wrapping paper, <a href='#Page_160'>160</a>, <a href='#Page_161'>161</a></li> - -<li class="indx">—— tanks, iron, cement for, <a href='#Page_246'>246</a></li> - -<li class="indx">Weavers’ looms, worn-out hinges from, <a href='#Page_30'>30</a></li> - -<li class="indx">Weidenbusch’s method of testing glue, <a href='#Page_211'>211</a>-213</li> - -<li class="indx">Whalebone, cement for, <a href='#Page_232'>232</a></li> - -<li class="indx">Whale glue, <a href='#Page_204'>204</a></li> - -<li class="indx">Whip leather, <a href='#Page_30'>30</a></li> - -<li class="indx">White-lead, addition of, to glue, <a href='#Page_149'>149</a></li> - -<li class="indx">Wood, cement for, <a href='#Page_230'>230</a>, <a href='#Page_239'>239</a>, <a href='#Page_240'>240</a></li> - -<li class="indx">—— —— —— attaching metal letters to, <a href='#Page_249'>249</a></li> - -<li class="indx">—— —— —— —— to metal, <a href='#Page_251'>251</a></li> - -<li class="indx">Wooden vessels, insoluble cement for, <a href='#Page_233'>233</a></li> - -<li class="indx">Wrapping paper, water-proof, <a href='#Page_160'>160</a>, <a href='#Page_161'>161</a></li> - - -<li class="ifrst">Zinc plates, gelatinizing liquors upon, <a href='#Page_58'>58</a>, <a href='#Page_59'>59</a></li> - -<li class="indx">—— white cement, <a href='#Page_226'>226</a></li> - -<li class="indx">—— addition of, to glue, <a href='#Page_149'>149</a></li></ul> -</div> - -<hr class="tb" /> - -<div class="transnote"> -<div class="chapter"></div> -<h3>Transcriber's Notes</h3> - -<p>Obvious typographical errors have been silently corrected. Variations -in hyphenation have been standardised but all other spelling and -punctuation remains unchanged.</p> - -<p>The following corrections have been made:</p> - -<p>From<br /> -<a href="#III">III.</a> 3Ca(PO<sub>3</sub>)<sub>2</sub> + 10C = 10CO + -Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> = P<sub>2</sub><br /> -to<br /> -III. 3Ca(PO<sub>3</sub>)<sub>2</sub> + 10C = 10CO + -Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> + P<sub>4</sub></p> - -<p>From -<a href="#Ca">3Ca</a>(PO<sub>3</sub>)<sub>2</sub> + 5Ca<sub>2</sub> = Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> + 10CO + 4P.<br /> -to<br /> -3Ca(PO<sub>3</sub>)<sub>2</sub> + 10C = Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> + 10CO + 4P.</p> - -</div> - - - - - - - -<pre> - - - - - -End of the Project Gutenberg EBook of Glue, Gelatine, Animal Charcoal, -Phosphorous, Cements, Pastes and, by F. 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