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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..6833f05 --- /dev/null +++ b/.gitattributes @@ -0,0 +1,3 @@ +* text=auto +*.txt text +*.md text diff --git a/15308-8.txt b/15308-8.txt new file mode 100644 index 0000000..f7a0e56 --- /dev/null +++ b/15308-8.txt @@ -0,0 +1,10955 @@ +The Project Gutenberg EBook of Nitro-Explosives: A Practical Treatise +by P. Gerald Sanford + +This eBook is for the use of anyone anywhere 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 + + +Title: Nitro-Explosives: A Practical Treatise + +Author: P. Gerald Sanford + +Release Date: March 10, 2005 [EBook #15308] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK NITRO-EXPLOSIVES *** + + + + +Produced by Case Western Reserve University Preservation +Department, Curtis Weyant, and the Online Distributed +Proofreading Team + + + + + +NITRO-EXPLOSIVES + +[Illustration: DANGER BUILDING SHOWING PROTECTING MOUNDS. (_See page 6._)] + +NITRO-EXPLOSIVES + +A PRACTICAL TREATISE + +CONCERNING THE + +_PROPERTIES, MANUFACTURE, AND ANALYSIS OF NITRATED SUBSTANCES, INCLUDING +THE FULMINATES, SMOKELESS POWDERS, AND CELLULOID_ + +BY + +P. GERALD SANFORD, F.I.C., F.C.S. + +_Public Analyst to the Borough of Penzance; late Consulting Chemist to the +Cotton Powder Company Limited; and formerly Resident Chemist at the +Stowmarket Works of the New Explosives Company Limited, and the Hayle +Works of the National Explosive Company Limited_ + +~Second Edition, Revised and Enlarged~ + + +PREFACE. + + +In compiling the following treatise, my aim has been to give a brief but +thoroughly practical account of the properties, manufacture, and methods +of analysis of the various nitro-explosives now so largely used for mining +and blasting purposes and as propulsive agents; and it is believed that +the account given of the manufacture of nitro-glycerine and of the +gelatine dynamites will be found more complete than in any similar work +yet published in this country. + +For many of the facts and figures contained in the chapter on Smokeless +Powders I am indebted to (amongst others) the late Mr J.D. Dougall and +Messrs A.C. Ponsonby and H.M. Chapman, F.C.S.; and for details with regard +to Roburite to Messrs H.A. Krohn and W.J. Orsman, F.I.C. To these +gentlemen my cordial thanks are due. Among the authorities which have been +consulted in the general preparation of the work may be mentioned the +_Journals_ of the Chemical Society, the Society of Chemical Industry, the +United States Naval Institute, and the Royal Artillery Institution. I have +also referred to several volumes of the periodical publication _Arms and +Explosives;_ to various papers by Sir Frederick Abel, Bart., F.R.S., and +General Wardell, R.A., on Gun-Cotton; to "Modern Artillery," by Capt. +Lloyd, R.N., and A.G. Hadcock, R.A.; to the late Colonel Cundill's +"Dictionary of Explosives"; as well as to the works of Messrs Eissler, +Berthelot, and others. + +The illustrations have been prepared chiefly from my own drawings. A few, +however, have been taken (by permission) from the pages of _Arms and +Explosives_, or from other sources which are acknowledged in the text. + +P.G.S. + +THE LABORATORY, + +20 CULLUM STREET, E.C. + +_May 1896._ + + + +PREFACE TO THE SECOND EDITION. + + +In the preparation of the Second Edition of this work, I have chiefly made +use of the current technical journals, especially of the _Journal of the +Society of Chemical Industry_. The source of my information has in every +case been acknowledged. + +I am also indebted to several manufacturers of explosives for information +respecting their special products--among others the New Explosives Company +Ltd.; Messrs Curtis's and Harvey Ltd.; The Schultze Gunpowder Company +Ltd.; and Mr W.D. Borland, F.I.C., of the E.C. Powder Company Ltd. + +To my friend Mr A. Stanley Fox, F.C.S., of Faversham, my best thanks are +also due for his help in many departments, and his kindness in pointing +out several references. + +The chapter on Smokeless Powders has been considerably enlarged and (as +far as possible) brought up to date; but it has not always been possible +to give the process of manufacture or even the composition, as these +details have not, in several cases, been made public. + +P. GERALD SANFORD. + +LONDON, _June 1906._ + + + + +TABLE OF CONTENTS. + +CHAPTER I.--INTRODUCTION. + +The Nitro-Explosives--Substances that have been Nitrated--The Danger Area-- +Systems of Professors Lodge, Zenger, and Melsens for the Protection of +Buildings from Lightning, &c. + +CHAPTER II.--NITRO-GLYCERINE. + +Properties of Nitro-Glycerine--Manufacture--Nitration--Separation--Washing +and Filtering--Drying, Storing, &c.--The Waste Acids--Their Treatment-- +Nitric Acid Plants + +CHAPTER III.--NITRO-CELLULOSE, &C. + +Cellulose Properties--Discovery of Gun-Cotton--Properties of Gun-Cotton-- +Varieties of Soluble and Insoluble Gun-Cottons--Manufacture of Gun-Cotton-- +Dipping and Steeping—Whirling Out the Acid--Washing, Boiling, Pulping, +Compressing--The Waltham Abbey Process--Le Bouchet Process--Granulation of +Gun-Cotton--Collodion-Cotton--Manufacture--Acid Mixture Used--Cotton Used, +&c.--Nitrated Gun-Cotton--Tonite--Dangers in Manufacture of Gun-Cotton-- +Trench's Fire-Extinguishing Compound--Uses of Collodion-Cotton--Celluloid-- +Manufacture, &c.--Nitro-Starch, Nitro-Jute, and Nitro-Mannite + +CHAPTER IV.--DYNAMITE. + +Kieselguhr Dynamite--Classification of Dynamites--Properties and +Efficiency of Ordinary Dynamite--Other forms of Dynamite--Gelatine and +Gelatine Dynamites, Suitable Gun-Cotton for, and Treatment of--Other +Materials Used--Composition of Gelignite--Blasting Gelatine--Gelatine +Dynamite--Absorbing Materials--Wood Pulp--Potassium Nitrate, &c.-- +Manufacture, &c.--Apparatus Used--The Properties of the Gelatine Compounds + +CHAPTER V.--NITRO-BENZOL, ROBURITE, BELLITE, PICRIC ACID, &c. + +Explosives derived from Benzene--Toluene and Nitro-Benzene--Di- and +Tri-nitro-Benzene--Roburite: Properties and Manufacture--Bellite: +Properties, &c.--Securite--Tonite No. 3.--Nitro-Toluene-- +Nitro-Naphthalene--Ammonite--Sprengel's Explosives--Picric Acid-- +Picrates--Picric Powders--Melinite--Abel's Mixture--Brugère's Powders-- +The Fulminates--Composition, Formula, Preparation, Danger of, &c.-- +Detonators: Sizes, Composition, Manufacture--Fuses, &c. + +THE FULMINATES. + +Composition, Formula, Preparation, Danger of, &c.--Detonators: Sizes, +Composition, Manufacture--Fuses, &c. + +CHAPTER VI.--SMOKELESS POWDERS IN GENERAL. + +Cordite--Axite--Ballistite--U.S. Naval Powder--Schultze's E.C. Powder-- +Indurite--Vielle Poudre--Walsrode and Cooppal Powders--Amberite-- +Troisdorf--B.N. Powder--Wetterin--Normal Powder--Maximite--Picric Acid +Powders, &c. &c. + +CHAPTER VII.--ANALYSIS OF EXPLOSIVES. + +Kieselguhr Dynamite--Gelatine Compounds--Tonite--Cordite--Vaseline-- +Acetone--Scheme for Analysis of Explosives--Nitro-Cotton--Solubility Test-- +Non-Nitrated Cotton--Alkalinity--Ash and Inorganic Matter--Determination +of Nitrogen--Lungé, Champion and Pellet's, Schultze-Tieman, and Kjeldahl's +Methods--Celluloid--Picric Acid and Picrates--Resinous and Tarry Matters-- +Sulphuric Acid and Hydrochloric Acid and Oxalic Acid--Nitric Acid-- +Inorganic Impurities--General Impurities and Adulterations--Potassium +Picrate, &c.--Picrates of the Alkaloids--Analysis of Glycerine--Residue-- +Silver Test--Nitration--Total Acid Equivalent--Neutrality--Free Fatty +Acids--Combined Fatty Acids--Impurities--Oleic Acid--Sodium Chloride-- +Determination of Glycerine--Waste Acids--Sodium Nitrate--Mercury +Fulminate--Cap Composition--Table for Correction of Volumes of Gases, for +Temperature and Pressure + +CHAPTER VIII.--FIRING POINT OF EXPLOSIVES, HEAT TESTS, &C. + +Horsley's Apparatus--Table of Firing Points--The Government Heat Test +Apparatus, &c., for Dynamites, Nitro-Glycerine, Nitro-Cotton, and +Smokeless Powders--Guttmann's Heat Test--Liquefaction and Exudation Tests-- +Page's Regulator for Heat Test Apparatus--Specific Gravities of +Explosives--Will's Test for Nitro-Cellulose--Table of Temperature of +Detonation, Sensitiveness, &c. + +CHAPTER IX.--THE DETERMINATION OF THE RELATIVE STRENGTH OF EXPLOSIVES. + +Effectiveness of an Explosive--High and Low Explosives--Theoretical +Efficiency--M.M. Roux and Sarrau's Results--Abel and Noble's--Nobel's +Ballistic Test--The Mortar--Pressure or Crusher Gauge--Calculation Volume +of Gas Evolved, &c.--Lead Cylinders--The Foot-Pounds Machine--Noble's +Pressure Gauge--Lieut. Walke's Results--Calculation of Pressure Developed +by Dynamite and Gun-Cotton--McNab's and Ristori's Results of Heat +Developed by the Explosion of Various Explosives--Composition of some of +the Explosives in Common Use for Blasting, &c. + +INDEX + + + +LIST OF ILLUSTRATIONS. + +FRONTISPIECE--Danger Building showing Protecting Mounds. + 1. Section of Nitro-Glycerine Conduit + 2. Melsens System of Lightning Conductors + 3. French System + 4_a_ & 4_b_. English Government System + 5. Upper Portion of Nitrator for Nitro-Glycerine + 6. Small Nitrator + 7. Nathan's Nitrator + 8. Nitro-Glycerine Separator + 9. Nitro-Glycerine Filtering Apparatus +10. Cotton-Waste Drier +11. Dipping Tank +12. Cooling Pits +13. Steeping Pot for Gun-Cotton +14. Hydro-Extractor or Centrifugal Drier +15_a_ & 15_b_. Gun-Cotton Beater +16_a_. Poacher for Pulping Gun-Cotton +16_b_. Plan of same +16_c_. Another form of Poacher +17 & 18. Compressed Gun-Cotton +19. Hydraulic Press +20. Thomson's Apparatus--Elevation +21. Elevation Plan +22. Trench's Safety Cartridge +23. Vessel used in Nitrating Paper +24. Cage ditto--White & Schupphaus' Apparatus +25. Do. do. do. +26 & 27. Nitrating Pot for Celluloid +28 & 29. Plunge Tank in Plan and Section +30. Messrs Werner, Pfleiderer & Perkins' Mixing Machine +31. M. 'Roberts' Mixing Machine for Blasting Gelatine +32. Plan of same +33. Cartridge Machine for Gelatines +34. Cartridge fitted with Fuse and Detonator +35. Gun-Cotton Primer +36. Electric Firing Apparatus +37. Metal Drum for Winding Cordite +38. Ten-Stranding +39. Curve showing relation between Pressures of Cordite and Black Powder, + by Professor Vivian Lewes +40. Marshall's Apparatus for Moisture in Cordite +41. Lungé's Nitrometer +42. Modified do. +43. Horn's Nitrometer +44. Schultze-Tieman Apparatus for Determination of Nitrogen in Gun-Cotton +45. Decomposition Flask for Schultze-Tieman Method +46. Abel's Heat Test Apparatus +47. Apparatus for Separation of Nitro-Glycerine from Dynamite +48. Test Tube arranged for Heat Test +49. Page's Regulator +50. Do. showing Bye-Pass and Cut-off Arrangement +51. Will's Apparatus +52 & 53. Curves obtained +54. Dynamite Mortar +55. Quinan's Pressure Gauge +56. Steel Punch and Lead Cylinder for Use with Pressure Gauge +57. Micrometer Calipers for Measuring Thickness of Lead Cylinders +58. Section of Lead Cylinders before and after Explosion +59. Noble's Pressure Gauge +60. Crusher Gauge + + + + +NITRO-EXPLOSIVES. + + +CHAPTER I. + +_INTRODUCTORY._ + +The Nitro-Explosives--Substances that have been Nitrated--The Danger Area-- +Systems of Professors Lodge, Zenger, and Melsens for the Protection of +Buildings from Lightning, &c. + + +The manufacture of the various nitro-explosives has made great advances +during late years, and the various forms of nitro-compounds are gradually +replacing the older forms of explosives, both for blasting purposes and +also for propulsive agents, under the form of smokeless powders. The +nitro-explosives belong to the so-called High Explosives, and may be +defined as any chemical compound possessed of explosive properties, or +capable of combining with metals to form an explosive compound, which is +produced by the chemical action of nitric acid, either alone or mixed with +sulphuric acid, upon any carbonaceous substance, whether such compound is +mechanically mixed with other substances or not.[A] + +[Footnote A: Definition given in Order of Council, No. 1, Explosives Act, +1875.] + +The number of compounds and mixtures included under this definition is +very large, and they are of very different chemical composition. Among the +substances that have been nitrated are:--Cellulose, under various forms, +e.g., cotton, lignin, &c.; glycerine, benzene, starch, jute, sugar, +phenol, wood, straw, and even such substances as treacle and horse-dung. +Some of these are not made upon the large scale, others are but little +used. Those of most importance are nitro-glycerine and nitro-cellulose. +The former enters into the composition of all dynamites, and several +smokeless powders; and the second includes gun-cotton, collodion-cotton, +nitrated wood, and the majority of the smokeless powders, which consist +generally of nitro-cotton, nitro-lignin, nitro-jute, &c. &c., together +with metallic nitrates, or nitro-glycerine. + +The nitro-explosives consist generally of some organic substance in which +the NO_{2} group, known as nitryl, has been substituted in place of +hydrogen. + +Thus in glycerine, + + |OH +C_{3}H_{5}|OH, + |OH + +which is a tri-hydric alcohol, and which occurs very widely distributed as +the alcoholic or basic constituent of fats, the hydrogen atoms are +replaced by the NO_{2} group, to form the highly explosive compound, +nitro-glycerine. If one atom only is thus displaced, the mono-nitrate is +formed thus, + + |ONO_{2} +C_{3}H_{5}|OH; + |OH + +and if the three atoms are displaced, C_{3}H_{5}(ONO_{2})_{3}, or the tri- +nitrate, is formed, which is commercial nitro-glycerine. + +Another class, the nitro-celluloses, are formed from cellulose, +C_{6}H_{10}O_{5}, which forms the groundwork of all vegetable tissues. +Cellulose has some of the properties of the alcohols, and forms ethereal +salts when treated with nitric and sulphuric acids. The hexa-nitrate, or +gun-cotton, has the formula, C_{12}H_{14}O_{4}(ONO_{2})_{6}; and +collodion-cotton, pyroxylin, &c., form the lower nitrates, i.e., the +tetra- and penta-nitrates. These last are soluble in various solvents, +such as ether-alcohol and nitro-glycerine, in which the hexa-nitrate is +insoluble. They all dissolve, however, in acetone and acetic ether. + +The solution of the soluble varieties in ether-alcohol is known as +collodion, which finds many applications in the arts. The hydrocarbon +benzene, C_{6}H_{6}, prepared from the light oil obtained from coal-tar, +when nitrated forms nitro-benzenes, such as mono-nitro-benzene, +C_{6}H_{5}NO_{2}, and di-nitro-benzene, C_{6}H_{4}(NO_{2})_{2}, in which +one and two atoms are replaced by the NO_{2} group. The latter of these +compounds is used as an explosive, and enters into the composition of such +well-known explosives as roburite, &c. The presence of nitro groups in a +substance increases the difficulty of further nitration, and in any case +not more than three nitro groups can be introduced into an aromatic +compound, or the phenols. All aromatic compounds with the general formula, +C_{6}H_{4}X_{2}, give, however, three series. They are called ortho, meta, +or para compounds, depending upon the position of NO_{2} groups +introduced. + +Certain regularities have been observed in the formation of nitro- +compounds. If, for example, a substance contains alkyl or hydroxyl groups, +large quantities of the para compound are obtained, and very little of the +ortho. The substitution takes place, however, almost entirely in the meta +position, if a nitro, carboxyl, or aldehyde group be present. Ordinary +phenol, C_{6}H_{5}.OH, gives para- and ortho-nitro-phenol; toluene gives +para- and ortho-nitro-toluene; but nitro-benzene forms meta-di-nitro- +benzene and benzoic acid, meta-nitro-benzoic acid.[A] + +[Footnote A: "Organic Chemistry," Prof. Hjelt. Translated by J.B. Tingle, +Ph.D.] + +If the graphic formula of benzene be represented thus (No. 1), then the +positions 1 and 2 represent the ortho, 1 and 3 the meta, and 1 and 4 the +para compounds. When the body phenol, C_{6}H_{5}.OH, is nitrated, a +compound is formed known as tri-nitro-phenol, or picric acid, +C_{6}H_{2}(NO_{2})_{3}OH, which is used very extensively as an explosive, +both as picric acid and in the form of picrates. Another nitro body that +is used as an explosive is nitro-naphthalene, C_{10}H_{6}(NO_{2})_{2}, in +roburite, securite, and other explosives of this class. The hexa-nitro- +mannite, C_{6}H_{8}(ONO_{2})_{6}, is formed + +[Illustration: No. 1] + +[Illustration: META-DINITRO-BENZENE No.2] + +by treating a substance known as mannite, C_{6}H_{8}(OH)_{6}, an alcohol +formed by the lactic acid fermentation of sugar and closely related to the +sugars, with nitric and sulphuric acids. It is a solid substance, and very +explosive; it contains 18.58 per cent. of nitrogen. + +Nitro-starch has also been used for the manufacture of an explosive. +Muhlhauer has described (_Ding. Poly. Jour._, 73, 137-143) three nitric +ethers of starch, the tetra-nitro-starch, C_{12}H_{16}O_{6}(ONO_{2})_{4}, +the penta- and hexa-nitro-starch. They are formed by acting upon potato +starch dried at 100° C. with a mixture of nitric and sulphuric acids at a +temperature of 20° to 25° C. Rice starch has also been used in its +production. Muhlhauer proposes to use this body as a smokeless powder, and +to nitrate it with the spent mixed acids from the manufacture of nitro- +glycerine. This substance contains from 10.96 to 11.09 per cent. of +nitrogen. It is a white substance, very stable and soluble even in cold +nitro-glycerine. + +The explosive bodies formed by the nitration of jute have been studied by +Messrs Cross and Bevan. and also by Mühlhäuer. The former chemists give +jute the formula C_{12}H_{18}O_{9}, and believe that its conversion into a +nitro-compound takes place according to the equation-- + +C_{12}H_{18}O_{9} + 3HNO_{3} = 3H_{2}O + C_{12}H_{15}O_(6}(NO_{3})_{3}. + +This is equivalent to a gain in weight of 44 per cent. for the tri- +nitrate, and 58 per cent. for the tetra-nitrate. The formation of the +tetra-nitrate appears to be the limit of nitration of jute fibre. Messrs +Cross and Bevan say, "In other words, if we represent the ligno-cellulose +molecule by a C_{12} formula, it will contain four hydroxyl (OH) groups, +or two less than cellulose similarly represented." It contains 11.5 per +cent. of nitrogen. The jute nitrates resemble those of cellulose, and are +in all essential points nitrates of ligno-cellulose. + +Nitro-jute is used in the composition of the well-known Cooppal Smokeless +Powders. Cross and Bevan are of opinion that there is no very obvious +advantage in the use of lignified textile fibres as raw materials for +explosive nitrates, seeing that a number of raw materials containing +cellulose (chiefly as cotton) can be obtained at from £10 to £25 a ton, +and yield also 150 to 170 per cent. of explosive material when nitrated +(whereas jute only gives 154.4 per cent.), and are in many ways superior +to the products obtained from jute. Nitro-lignin, or nitrated wood, is, +however, largely used in the composition of a good many of the smokeless +powders, such as Schultze's, the Smokeless Powder Co.'s products, and +others. + +~The Danger Area.~--That portion of the works that is devoted to the +actual manufacture or mixing of explosive material is generally designated +by the term "danger area," and the buildings erected upon it are spoken of +as "danger buildings." The best material of which to construct these +buildings is of wood, as in the event of an explosion they will offer less +resistance, and will cause much less danger than brick or stone buildings. +When an explosion of nitro-glycerine or dynamite occurs in one of these +buildings, the sides are generally blown out, and the roof is raised some +considerable height, and finally descends upon the blown-out sides. If, on +the other hand, the same explosion had occurred in a strong brick or stone +building, the walls of which would offer a much larger resistance, large +pieces of brickwork would probably have been thrown for a considerable +distance, and have caused serious damage to surrounding buildings. + +It is also a very good plan to surround all danger buildings with mounds +of sand or earth, which should be covered with turf, and of such a height +as to be above the roof of the buildings that they are intended to protect +(see frontispiece).[A] These mounds are of great value in confining the +force of the explosion, and the sides of the buildings being thrown +against them are prevented from travelling any distance. In gunpowder +works it is not unusual to surround the danger buildings with trees or +dense underwood instead of mounds. This would be of no use in checking the +force of explosion of the high explosives, but has been found a very +useful precaution in the case of gunpowder. + +[Footnote A: At the Baelen Factory, Belgium, the danger buildings are +erected on a novel plan. They are circular in ground plan and lighted +entirely from the roof by means of a patent glass having wire-netting in +it, and which it is claimed will not let a splinter fall, even if badly +cracked. The mounds are then erected right up against the walls of the +building, exceeding them in height by several metres. For this method of +construction it is claimed that the force exerted by an explosion will +expand itself in a vertical direction ("Report on Visits to Certain +Explosive Factories," H.M. Inspectors, 1905).] + +In Great Britain it is necessary that all danger buildings should be a +specified distance apart; a license also must be obtained. The application +for a license must give a plan (drawn to scale) of the proposed factory or +magazine, and the site, its boundaries, and surroundings, and distance the +building will be from any other buildings or works, &c., also the +character, and construction of all the mounds, and nature of the processes +to be carried on in the factory or building.[A] + +[Footnote A: Explosives Act, 38 Vict. ch. 17.] + +[Illustration: FIG. 1.--SECTION OF NITRO-GLYCERINE CONDUIT. _a_, lid; _b_, +lead lining; _c_, cinders.] + +The selection of a site for the danger area requires some attention. The +purpose for which it is required, that is, the kind of explosive that it +is intended to manufacture, must be taken into consideration. A perfectly +level piece of ground might probably be quite suitable for the purpose of +erecting a factory for the manufacture of gun-cotton or gunpowder, and +such materials, but would be more or less unsuitable for the manufacture +of nitro-glycerine, where a number of buildings are required to be upon +different levels, in order to allow of the flow of the liquid nitro- +glycerine from one building to another through a system of conduits. These +conduits (Fig. 1), which are generally made of wood and lined with lead, +the space between the woodwork and the lead lining, which is generally +some 4 or 5 inches, being filled with cinders, connect the various +buildings, and should slope gently from one to the other. It is also +desirable that, as far as possible, they should be protected by earth-work +banks, in the same way as the danger buildings themselves. They should +also be provided with covers, which should be whitewashed in hot weather. + +A great deal of attention should be given to these conduits, and they +should be very frequently inspected. Whenever it is found that a portion +of the lead lining requires repairing, before cutting away the lead it +should be very carefully washed, for several feet on either side of the +portion that it is intended to remove, with a solution of caustic soda or +potash dissolved in methylated spirit and water, and afterwards with water +alone. This decomposes the nitro-glycerine forming glycerine and potassium +nitrate. It will be found that the mixed acids attack the lead rather +quickly, forming sulphate and nitrate of lead, but chiefly the former. It +is on this account that it has been proposed to use pipes made of +guttapercha, but the great drawback to their use is that in the case of +anything occurring inside the pipes, such as the freezing of the nitro- +glycerine in winter, it is more difficult to find it out, and the +condition of the inside cannot be seen, whereas in the case of wooden +conduits it is an easy matter to lift the lids along the whole length of +the conduit. + +The buildings which require to be connected by conduits are of course +those concerned with the manufacture of nitro-glycerine. These buildings +are--(1) The nitrating house; (2) the separating house; (3) the filter +house; (4) the secondary separator; (5) the deposit of washings; (6) the +settling or precipitation house; and each of these buildings must be on a +level lower than the preceding one, in order that the nitro-glycerine or +acids may flow easily from one building to the next. These buildings are, +as far as possible, best placed together, and away from the other danger +buildings, such as the cartridge huts and dynamite mixing houses, but this +is not essential. + +All danger buildings should be protected by a lightning conductor, or +covered with barbed wire, as suggested by Professor Sir Oliver J. Lodge, +F.R.S., Professors Zenger, of Prague, and Melsens, of Brussels, and +everything possible should be done to keep them as cool as possible in the +summer. With this object they should be made double, and the intervening +space filled with cinders. The roof also should be kept whitewashed, and +the windows painted over thinly with white paint. A thermometer should be +suspended in every house. It is very essential that the floors of all +these buildings should be washed every day before the work-people leave. +In case any nitro-glycerine is spilt upon the floors, after sponging it up +as far as possible, the floor should be washed with an alcoholic solution +of soda or potash to decompose the nitro-glycerine, which it does +according to the equation[A]-- + +C_{3}H_{5}(NO_{3})_{3} + 3KOH = C_{3}H_{8}O_{3} + 3KNO_{3}. + +[Footnote A: See also Berthelot, _Comptes Rendus_, 1900, 131[12], 519- +521.] + +Every one employed in the buildings should wear list or sewn leather +shoes, which of course must be worn in the buildings only. The various +houses should be connected by paths laid with cinders, or boarded with +planks, and any loose sand about the site of the works should be covered +over with turf or cinders, to prevent its blowing about and getting into +the buildings. It is also of importance that stand pipes should be placed +about the works with a good pressure of water, the necessary hose being +kept in certain known places where they can be at once got at in the case +of fire, such as the danger area laboratory, the foreman's office, &c. It +is also desirable that the above precautions against fire should be tested +once a week. With regard to the heating of the various buildings in the +winter, steam pipes only should be used, and should be brought from a +boiler-house outside the danger area, and should be covered with +kieselguhr or fossil meal and tarred canvas. These pipes may be supported +upon poles. A stove of some kind should be placed in the corner of each +building, but it must be entirely covered in with woodwork, and as small a +length of steam pipes should be within the building as possible. + +In the case of a factory where nitro-glycerine and dynamite are +manufactured, it is necessary that the work-people should wear different +clothes upon the danger area than usual, as they are apt to become +impregnated with nitro-glycerine, and thus not very desirable or safe to +wear outside the works. It is also necessary that these clothes should not +contain any pockets, as this lessens the chance of matches or steel +implements being taken upon the danger area. Changing houses, one for the +men, and another for the girls, should also be provided. The tools used +upon the danger area should, whenever the building is in use, or contains +explosives, be made of phosphor bronze or brass, and brass nails or wooden +pegs should be used in the construction of all the buildings. + +[Illustration: FIG. 2.--MELSENS SYSTEM OF LIGHTNING CONDUCTORS.] + +~Lightning Conductors.~--The Explosive Substances Act, 38 Vict. ch. 17, +clause 10, says, "Every factory magazine and expense magazine in a +factory, and every danger building in a magazine, shall have attached +thereto a sufficient lightning conductor, unless by reason of the +construction by excavation or the position of such magazine or building, +or otherwise, the Secretary of State considers a conductor unnecessary, +and every danger building in a factory shall, if so required by the +Secretary of State, have attached thereto a sufficient lightning +conductor." + +The exact form of lightning conductor most suitable for explosive works +and buildings has not yet been definitely settled. Lightning-rod engineers +favour what is known as the Melsens system, due to Professor Melsens, of +Brussels, and Professor Zenger, of Prague, but first suggested by the late +Professor Clerk-Maxwell. In a paper read before the British Association, +Clerk-Maxwell proposed to protect powder-magazines from the effects of +lightning by completely surrounding or encasing them with sheet metal, or +a cage of metallic conductors. There were, however, several objections to +his system as he left it. + +Professor Melsens[A] has, while using the idea, made several important +alterations. He has multiplied the terminals, the conductors, and the +earth-connections. His terminals are very numerous, and assume the form of +an aigrette or brush with five or seven points, the central point being a +little higher than the rest, which form with it an angle of 45°. He +employs for the most part galvanised-iron wire. He places all metallic +bodies, if they are of any considerable size, in communication with the +conducting system in such a manner as to form closed metallic circuits. +His system is illustrated in Fig. 2, taken from _Arms and Explosives_. + +[Footnote A: Belgian Academy of Science.] + +This system is a near approximation to J.C. Maxwell's cage. The system was +really designed for the protection of powder-magazines or store buildings +placed in very exposed situations. Zenger's system is identical with that +of Melsens, and has been extensively tried by the Austrian military +authorities, and Colonel Hess has reported upon the absolute safety of the +system. + +[Illustration: Fig. 3.--FRENCH SYSTEM OF LIGHTNING CONDUCTORS.] + +The French system of protecting powder-magazines is shown in Fig. 3, where +there are no brush terminals or aigrettes. The French military authorities +also protect magazines by erecting two or more lightning-rods on poles of +sufficient height placed close to, but not touching, the walls of the +magazine. These conductors are joined below the foundations and earthed as +usual. + +In the instructions issued by the Government, it is stated that the +lightning-rods placed upon powder-mills should be of such a height, and so +situated, that no danger is incurred in igniting the powder-dust in the +air by the lightning discharge at the pointed rod. In such a case a fork +or aigrette of five or more points should invariably be used in place of a +single point. + +[Illustration: FIG. 4_a_.--GOVERNMENT SYSTEM OF LIGHTNING CONDUCTORS FOR +LARGE BUILDINGS.] + +[Illustration: FIG. 4_b_.--GOVERNMENT SYSTEM OF LIGHTNING CONDUCTORS FOR +SMALL BUILDINGS.] + +In Fig. 4 (_a_ and _b_) is shown the Government method for protecting +buildings in which explosives are made or stored. Multiple points or +aigrettes would be better. Lord Kelvin and Professor Melsens favour +points, and it is generally admitted that lightning does not strike +buildings at a single point, but rather in a sheet; hence, in such cases, +or in the event of the globular form being assumed by the lightning, the +aigrette will constitute a much more effective protection than a single +point. As to the spacing of conductors, they may, even on the most +important buildings, be spaced at intervals of 50 feet. There will then be +no point on the building more than 25 feet from the conductor. This +"25-feet rule" can be adhered to with advantage in all overground buildings +for explosives. + +Underground magazines should, whenever possible, also be protected, +because, although less exposed than overground buildings, they frequently +contain explosives packed in metal cases, and hence would present a line +of smaller electrical resistance than the surrounding earth would offer to +the lightning. The conductor should be arranged on the same system as for +overground buildings, but be applied to the surface of the ground over the +magazines. + +In all situations where several conductors are joined in one system, the +vertical conductors should be connected both at the top and near the +ground line. The angles and the prominent portions of a building being the +most liable to be struck, the conductors should be carried over and along +these projections, and therefore along the ridges of the roof. The +conductors should be connected to any outside metal on the roofs and +walls, and specially to the foot of rain-water pipes. + +All the lightning conductors should be periodically tested, to see that +they are in working condition, at least every three months, according to +Mr Richard Anderson. The object of the test is to determine the resistance +of the earth-connection, and to localise any defective joints or parts in +the conductors. The best system of testing the conductors is to balance +the resistance of each of the earths against the remainder of the system, +from which the state of the earths may be inferred with sufficient +accuracy for all practical purposes. + +Captain Bucknill, R.E., has designed an instrument to test resistance +which is based on the Post Office pattern resistance coil, and is capable +of testing to approximate accuracy up to 200 ohms, and to measure roughly +up to 2,000 ohms. Mr R. Anderson's apparatus is also very handy, +consisting of a case containing three Leclanché cells, and a galvanometer +with a "tangent" scale and certain standard resistances. Some useful +articles on the protection of buildings from lightning will be found in +_Arms and Explosives_, July, August, and September 1892, and by Mr +Anderson, Brit. Assoc., 1878-80. + +~Nitro-Glycerine.~--One of the most powerful of modern explosive agents is +nitro-glycerine. It is the explosive contained in dynamite, and forms the +greater part of the various forms of blasting gelatines, such as gelatine +dynamite and gelignite, both of which substances consist of a mixture of +gun-cotton dissolved in nitro-glycerine, with the addition of varying +proportions of wood-pulp and saltpetre, the latter substances acting as +absorbing materials for the viscid gelatine. Nitro-glycerine is also +largely used in the manufacture of smokeless powders, such as cordite, +ballistite, and several others. + +Nitro-glycerol, or glycerol tri-nitrate, was discovered by Sobrero in the +year 1847. In a letter written to M. Pelouse, he says, "when glycerol is +poured into a mixture of sulphuric acid of a specific gravity of 1.84, and +of nitric acid of a gravity of 1.5, which has been cooled by a freezing +mixture, that an oily liquid is formed." This liquid is nitro-glycerol, or +nitro-glycerine, which for some years found no important use in the arts, +until the year 1863, when Alfred Nobel first started a factory in +Stockholm for its manufacture upon a large scale; but on account of some +serious accidents taking place, its use did not become general. + +It was not until Nobel conceived the idea (in 1866) of absorbing the +liquid in some absorbent earth, and thus forming the material that is now +known as dynamite, that the use of nitro-glycerine as an explosive became +general. + +Among those who improved the manufacture of nitro-glycerine was Mowbray, +who, by using pure glycerine and nitric acid free from nitrous acid, made +very great advances in the manufacture. Mowbray was probably the first to +use compressed air for the purpose of keeping the liquids well agitated +during the process of nitration, which he conducted in earthenware pots, +each containing a charge of 17 lbs. of the mixed acids and 2 lbs. of +glycerol. + +A few years later (1872), MM. Boutnny and Faucher, of Vonges,[A] proposed +to prepare nitro-glycerine by mixing the sulphuric acid with the +glycerine, thus forming a sulpho-glyceric acid, which was afterwards mixed +with a mixture of nitric and sulphuric acids. They claimed for this method +of procedure that the final temperature is much lower. The two mixtures +are mixed in the proportions--Glycerine, 100; nitric acid, 280; and +sulphuric acid, 600. They state that the rise of temperature upon mixing +is limited from 10° to 15° C.; but this method requires a period of +twenty-four hours to complete the nitration, which, considering the danger +of keeping the nitro-glycerine in contact with the mixed acids for so +long, probably more than compensates for the somewhat doubtful advantage +of being able to perform the nitration at such a low temperature. The +Boutnny process was in operation for some time at Pembrey Burrows in +Wales, but after a serious explosion the process was abandoned. + +[Footnote A: _Comptes Rendus_, 75; and Desortiaux, "Traité sur la Poudre," +684-686.] + +Nitro-glycerine is now generally made by adding the glycerine to a mixture +of sulphuric and nitric acids. The sulphuric acid, however, takes no part +in the reaction, but is absolutely necessary to combine with the water +that is formed by the decomposition, and thus to keep up the strength of +the nitric acid, otherwise lower nitrates of glycerine would be formed +that are soluble in water, and which would be lost in the subsequent +process of washing to which the nitro-compound is subjected, in order to +remove the excess of acids, the retention of which in the nitro-glycerol +is very dangerous. Nitro-glycerol, which was formerly considered to be a +nitro-substitution compound of glycerol, was thought to be formed thus-- + +C_{3}H_{8}O_{3} + 3HNO_{3} = C{3}H_{5}(NO_{2})_{3}O_{3} + 3H_{2}O; + +but more recent researches rather point to its being regarded as a nitric +ether of glycerol, or glycerine, and to its being formed thus-- + +C_{3}H_{8}O_{3} + 3 HNO_{3} = C{3}H_{5}(NO_{3})_{3} + 3H_{2}O. + 92 227 + + |OH +The formula of glycerine is C_{3}H_{8}O_{8}, or C_{3}H_{5}|OH + |OH + + |ONO_{2} +and that of the mono-nitrate of glycerine, C_{3}H_{5}|OH + |OH + + |ONO_{2} +and of the tri-nitrate or (nitro-glycerine), C_{3}H_{5}|ONO_{2} + |ONO_{2} + +that is, the three hydrogens of the semi-molecules of hydroxyl in the +glycerine have been replaced by the NO_{2} group. + +In the manufacture upon the large scale, a mixture of three parts by +weight of nitric acid and five parts of sulphuric acid are used. From the +above equation it will be seen that every 1 lb. of glycerol should give +2.47 lbs. of nitro-glycerol ((227+1)/92 = 2.47), but in practice the yield +is only about 2 lbs. to 2.22, the loss being accounted for by the +unavoidable formation of some of the lower nitrate, which dissolves in +water, and is thus washed away, and partly perhaps to the presence of a +little water (or other non-nitrable matter) in the glycerine, but chiefly +to the former, which is due to the acids having become too weak. + + + + +CHAPTER II. + +_MANUFACTURE OF NITRO-GLYCERINE._ + +Properties of Nitro-Glycerine--Manufacture of Nitro-Glycerine--Nitration-- +The Nathan Nitrator--Separation--Filtering and Washing--The Waste Acids-- +Treatment of the Waste Acid from the Manufacture of Nitro-Glycerine and +Gun-Cotton. + + +~Properties of Nitro-Glycerine.~--Nitro-glycerol is a heavy oily liquid of +specific gravity 1.6 at 15° C., and when quite pure is colourless. The +commercial product is a pale straw yellow, but varies much according to +the purity of the materials used in its manufacture. It is insoluble in +water, crystallises at 10.5° C., but different commercial samples behave +very differently in this respect, and minute impurities prevent or delay +crystallisation. Solid nitro-glycerol[A] melts at about 12° C., but +requires to be exposed to this temperature for some time before melting. +The specific gravity of the solid form is 1.735 at +10° C.; it contracts +one-twelfth of its volume in solidifying. Beckerheim[B] gives the specific +heat as 0.4248 between the temperatures of 9.5° and 9.8° C., and L. de +Bruyn gives the boiling point as above 200°. + +[Footnote A: Di-nitro-mono chlorhydrin, when added to nitro-glycerine up +to 20 per cent., is said to prevent its freezing.] + +[Footnote B: _Isb., Chem. Tech._, 22, 481-487. 1876.] + +Nitro-glycerine has a sweet taste, and causes great depression and +vertigo. It is soluble in ether, chloroform, benzene, glacial acetic acid, +and nitro-benzene, in 1.75 part of methylated spirit, very nearly +insoluble in water, and practically insoluble in carbon bisulphide. Its +formula is C_{3}H_{5}(NO_{3})_{3}, and molecular weight 227. When pure, it +may be kept any length of time without decomposition. Berthelot kept a +sample for ten years, and Mr G. M'Roberts, of the Ardeer Factory, for nine +years, without their showing signs of decomposition; but if it should +contain the smallest trace of free acid, decomposition is certain to be +started before long. This will generally show itself by the formation of +little green spots in the gelatine compounds, or a green ring upon the +surface of liquid nitro-glycerine. Sunlight will often cause it to +explode; in fact, a bucket containing some water that had been used to +wash nitro-glycerine, and had been left standing in the sun, has in our +experience been known to explode with considerable force. Nitro-glycerine +when pure is quite stable at ordinary temperatures, and samples have been +kept for years without any trace of decomposition. It is very susceptible +to heat, and even when quite pure will not stand a temperature of 100° C. +for a longer period than a few hours, without undergoing decomposition. Up +to a temperature of 45° C., however, properly made and purified nitro- +glycerine will remain unchanged almost indefinitely. The percentage +composition of nitroglycerine is as follows:-- + + Found. Theory for C_{3}H_{5}(N0_{2})_{3}. + +Carbon 15.62 15.86 per cent. +Hydrogen 2.40 2.20 " +Nitrogen 17.90 18.50 " +Oxygen ... 63.44 " + +The above analysis is by Beckerheim. Sauer and Adou give the nitrogen as +18.35 to 10.54 per cent. by Dumas' method; but I have never found any +difficulty in obtaining percentages as high as 18.46 by the use of Lunge's +nitrometer. The decomposition products by explosion are shown by the +following equation-- + + 2C_{3}H_{5}(NO_{3})_{3} = 6CO_{2} + 5H_{2}O + 6N + O; + +that is, it contains an excess of 3.52 per cent. of oxygen above that +required for complete combustion; 100 grms. would be converted into-- + +Carbonic Acid (CO_{2}) 58.15 per cent. +Water 19.83 " +Oxygen 3.52 per cent. +Nitrogen 18.50 " + +The volume of gases produced at 0° and 760 mm., calculated from the above, +is 714 litres per kilo, the water being taken as gaseous. Nitro-glycerine +is decomposed differently if it is ignited as dynamite (i.e., kieselguhr +dynamite), and if the gases are allowed to escape freely under a pressure +nearly equal to that of the atmosphere. Sarrau and Vieille obtained under +these conditions, for 100 volumes of gas-- + +NO 48.2 per cent. +CO 35.9 " +CO_{2} 12.7 " +H 1.6 per cent. +N 1.3 " +CH_{4} 0.3 " + +These conditions are similar to those under which a mining charge, simply +ignited by the cap, burns away slowly under a low pressure (i.e., a miss +fire). In a recent communication, P.F. Chalon (_Engineering and Mining +Journal_, 1892) says, that in practice nitro-glycerine vapour, carbon +monoxide, and nitrous oxide, are also produced as the result of +detonation, but he attributes their formation to the use of a too feeble +detonator. + +Nitro-glycerine explodes very violently by concussion. It may be burned in +an open vessel, but if heated above 250° C. it explodes. Professor C.E. +Munroe gives the firing point as 2O3°-2O5° C., and L. de Bruyn[A] states +its boiling point as 185°. He used the apparatus devised by Horsley. The +heat of formation of nitro-glycerine, as deduced from the heat of +combustion by M. Longuinine, is 432 calories for 1 grm.; and the heat of +combustion equals 1,576 cals. for 1 grm. In the case of nitro-glycerine +the heat of total combustion and the heat of complete decomposition are +interchangeable terms, since it contains an excess of oxygen. According to +Dr W.H. Perkin, F.R.S.,[B] the magnetic rotation of nitro-gylcerine is +5,407, and that of tri-methylene nitrate, 4.769 (diff. = .638). Dr Perkin +says: "Had nitro-glycerine contained its nitrogen in any other combination +with oxygen than as -O-NO_{2}, as it might if its constitution had been +represented as C_{3}H_{2}(NO_{2})_{3}(OH)_{3}, the rotation when compared +with propyl nitrate (4.085) would be abnormal." + +[Footnote A: _Jour. Soc. Chem. Ind._, June 1896, p. 471.] + +[Footnote B: _Jour. Chem. Soc._, W.H. Perkin, 1889, p. 726.] + +The solubility of nitro-glycerine in various solvents has been +investigated by A.H. Elliot; his results may be summarised as follows:-- + +_______________________________________________________________________ + | | +Solvent. | Cold. | Warm. +_____________________________|______________________|__________________ + | | +Water | Insoluble | Slightly soluble +Alcohol, absolute | Soluble | Soluble + " 93% | " | " + " 80% | Slowly soluble | " + " 50% | Insoluble | Slightly soluble +Methyl alcohol | Soluble | Soluble +Amyl " | " | " +Ether, ethylic | " | " + " acetic | " | " +Chloroform | " | " +Acetone | " | " +Sulphuric acid (1.845) | " | " +Nitric acid (1.400) | Slowly soluble | " +Hydrochloric acid (1.200) | Insoluble, decomposed| Slowly soluble +Acetic acid, glacial | Soluble | Soluble +Carbolic acid | " | " +Astral oil | Insoluble | Insoluble +Olive " | Soluble | Soluble +Stearine oil | " | " +Mineral jelly | Insoluble | Insoluble +Glycerine | " | " +Benzene | Soluble | Soluble +Nitro-benzene | " | " +Toluene | " | " +Carbon bi-sulphide | Insoluble | Slightly affected +Turpentine | " | Soluble +Petroleum naphtha, 71°-76° B.| " | Insoluble +Caustic soda (1:10 solution) | Insoluble. | Insoluble. +Borax, 5% solution | " | " +Ammonia (.980) | " | " slightly + | | affected. +Ammonium sulph-hydrate | Insoluble, sulphur | Decomposed. + | separates | +Iron sulphate solution | Slightly affected | Affected. +Iron chloride (1.4 grm. Fe | Slowly affected | Decomposed. + to 10 c.c. N_{2}O) | | +Tin chloride | Slightly affected | Affected. +_____________________________|______________________|__________________ + +Many attempts have been made to prepare nitro-glycerine explosives capable +of withstanding comparatively low temperatures without freezing, but no +satisfactory solution of the problem has been found. Among the substances +that have been proposed and used with more or less success, are nitro- +benzene, nitro-toluene, di-nitro-mono-chlorhydrine, solid nitro +derivatives of toluene,[A] are stated to lower the freezing point of +nitro-glycerine to -20°C. without altering its sensitiveness and +stability. The subject has been investigated by S. Nauckhoff,[B] who +states that nitroglycerine can be cooled to temperatures (-40° to -50° C.) +much below its true freezing point, without solidifying, by the addition +of various substances. When cooled by means of a mixture of solid carbon, +dioxide, and ether, it sets to a glassy mass, without any perceptible +crystallisation. The mass when warmed to 0°C. first rapidly liquefies and +then begins to crystallise. The true freezing point of pure nitro- +glycerine was found to be 12.3°C. The technical product, owing to the +presence of di-nitro-glycerine, freezes at 10.5° C. According to Raoult's +law, the lowering of the freezing point caused by _m_ grms. of a substance +with the molecular weight M, when dissolved in 100 grms. of the solvent, +is expressed by the formula: [Delta] = E(_m_/M), where E is a constant +characteristic for the solvent in question. The value of E for nitro- +glycerine was found to be 70.5 when calculated, according to Van't Hoff's +formula, from the melting point and the latent heat of fusion of the +substance. Determinations of the lowering of the freezing point of nitro- +glycerine by additions of benzene, nitro-benzene, di-nitro-benzene, tri- +nitro-benzene, p.-nitro-toluene, o.-nitro-toluene, di-nitro-toluene, +naphthalene, nitro-naphthalene, di-nitro-naphthalene, ethyl acetate, ethyl +nitrate, and methyl alcohol, gave results agreeing fairly well with +Raoult's formula, except in the case of methyl alcohol, for which the +calculated lowering of the freezing point was greater than that observed, +probably owing to the formation of complex molecules in the solution. The +results show that, in general, the capacity of a substance to lower the +freezing point of nitro-glycerine depends, not upon its freezing point, or +its chemical composition or constitution, but upon its molecular weight. +Nauckhoff states that a suitable substance for dissolving in nitro- +glycerine, in order to lower the freezing point of the latter, must have a +relatively low molecular weight, must not appreciably diminish the +explosive power and stability of the explosive, and must not be easily +volatile at relatively high atmospheric temperatures; it should, if +possible, be a solvent of nitro-cellulose, and in every case must not have +a prejudicial influence on the gelatinisation of the nitro-cellulose. + +[Footnote A: Eng. Pat. 25,797, November 1904.] + +[Footnote B: _Z. Angew. Chem._, 1905, 18, 11-22, 53-60.] + +~Manufacture of Nitro-Glycerine.~--Nitro-glycerine is prepared upon the +manufacturing scale by gradually adding glycerine to a mixture of nitric +and sulphuric acids of great strength. The mixed acids are contained in a +lead vessel, which is kept cool by a stream of water continually passing +through worms in the interior of the nitrating vessel, and the glycerine +is gradually added in the form of a fine stream from above. The +manufacture can be divided into three distinct operations, viz., +nitration, separation, and washing, and it will be well to describe these +operations in the above order. + +~Nitration.~--The most essential condition of nitrating is the correct +composition and strength of the mixed acids. The best proportions have +been found to be three parts by weight of nitric acid of a specific +gravity 1.525 to 1.530, and containing as small a portion of the oxides of +nitrogen as possible, to five parts by weight of sulphuric acid of a +specific gravity of 1.840 at 15° C., and about 97 per cent. of mono- +hydrate. It is of the very greatest importance that the nitric acid should +be as strong as possible. Nothing under a gravity of 1.52 should ever be +used even to mix with stronger acid, and the nitration will be +proportional to the strength of the acid used, provided the sulphuric acid +is also strong enough. It is also of great importance that the oxides of +nitrogen should be low, and that they should be kept down to as low as 1 +per cent., or even lower. It is also very desirable that the nitric acid +should contain as little chlorine as possible. The following is the +analysis of a sample of nitric acid, which gave very good results upon the +commercial scale:--Specific gravity, 1.525, N_{2}O_{4}, 1.03 per cent.; +nitric acid (HNO_{3}), 95.58 per cent. + +The amount of real nitric acid (mono-hydrate) and the amount of nitric +peroxide present in any sample should always be determined before it is +used for nitrating purposes. The specific gravity is not a sufficient +guide to the strength of the acid, as an acid having a high gravity, due +to some 3 or 4 per cent of nitric oxides in solution, will give very poor +nitration results. A tenth normal solution of sodium hydroxide (NaOH), +with phenol-phthalein as indicator, will be found the most convenient +method of determining the total acid present. The following method will be +found to be very rapid and reliable:--Weigh a 100 c.c. flask, containing a +few cubic centimetres of distilled water, and then add from a pipette 1 +c.c. of the nitric acid to be examined, and reweigh (this gives the weight +of acid taken). Now make up to 100 c.c. at 15° C.; shake well, and take +out 10 c.c. with a pipette; drain into a small Erlenmeyer flask, and add a +little of the phenol-phthalein solution, and titrate with the tenth normal +soda solution. + +The nitric peroxide can be determined with a solution of potassium +permanganate of N/10 strength, thus: Take a small conical flask, +containing about 10 c.c. of water, and add from a burette 10 to 16 c.c. of +the permanganate solution; then add 2 c.c. of the acid to be tested, and +shake gently, and continue to add permanganate solution as long as it is +decolourised, and until a faint pink colour is permanent. + +_Example._ N/10 permanganate 3.16 grms. per litre, 1 c.c. = O.0046 grm. +N_{2}O_{4}, 2 c.c. of sample of acid specific gravity 1.52 = 3.04 grms. +taken for analysis. Took 20 c.c. permanganate solution, O.0046 x 20 =.092 +grm. N_{2}O_{4}, and (.092 x 100)/3.04 = 3.02 per cent. N_{2}O_{4}. The +specific gravity should be taken with an hydrometer that gives the +specific gravity directly, or, if preferred, the 2 c.c. of acid may be +weighed. + +A very good method of rapidly determining the strength of the sulphuric +acid is as follows:--Weigh out in a small weighing bottle, as nearly as +possible, 2.45 grms. This is best done by running in 1.33 c.c. of the acid +(1.33 x 1.84 = 2.447). Wash into a large Erlenmeyer flask, carefully +washing out the bottle, and also the stopper, &c. Add a drop of phenol- +phthalein solution and titrate, with a half normal solution of sodium +hydrate (use a 100 c.c. burette). Then if 2.45 grms. exactly have been +taken, the readings on the burette will equal percentages of H_{2}SO_{4} +(mono-hydrate) if not, calculate thus:--2.444 grms. weighed, required 95.4 +c.c. NaOH. Then-- + +2.444 : 95.4 :: 2.45 : _x_ = 95.64 per cent. H_{2}SO_{4}. + +It has been proposed to free nitric acid from the oxides of nitrogen by +blowing compressed air through it, and thus driving the gases in solution +out. The acid was contained in a closed lead tank, from which the escaping +fumes were conducted into the chimney shaft, and on the bottom of which +was a lead pipe, bent in the form of a circle, and pierced with holes, +through which the compressed air was made to pass; but the process was not +found to be of a very satisfactory nature, and it is certainly better not +to allow the formation of these compounds in the manufacture of the acid +in the first instance. Another plan, however, is to heat the acid gently, +and thus drive out the nitrous gases. Both processes involve loss of +nitric acid. + +Having obtained nitric and sulphuric acids as pure as possible, the next +operation is to mix them. This is best done by weighing the carboys in +which the acids are generally stored before the acids are drawn off into +them from the condensers, and keeping their weights constantly attached to +them by means of a label. It is then a simple matter to weigh off as many +carboys of acid as may be required for any number of mixings, and subtract +the weights of the carboys. The two acids should, after being weighed, be +poured into a tank and mixed, and subsequently allowed to flow into an +acid egg or montjus, to be afterwards forced up to the nitrating house in +the danger area. The montjus or acid egg is a strong cast-iron tank, of +either an egg shape, or a cylinder with a round end. If of the former +shape, it would lie on its side, and upon the surface of the ground, and +would have a manhole at one end, upon which a lid would be strongly bolted +down; but if of the latter shape, the lid, of course, is upon the top, and +the montjus itself is let into the ground. In either case, the principle +is the same. One pipe, made of stout lead, goes to the bottom, and another +just inside to convey the compressed air, the acids flowing away as the +pressure is put on, just as blowing down one tube of an ordinary wash- +bottle forces the water up the other tube to the jet. The pressure +necessarily will, of course, vary immensely, and will depend upon the +height to which the acid has to be raised and the distance to be +traversed. + +The mixed acids having been forced up to the danger area, and to a level +higher than the position of the nitrating house, should, before being +used, be allowed to cool, and leaden tanks of sufficient capacity to hold +at least enough acid for four or five nitrations should be placed in a +wooden house upon a level at least 6 or 7 feet above the nitrating house. +In this house also should be a smaller lead tank, holding, when filled to +a certain mark, just enough of the mixed acids for one nitration. The +object of this tank is, that as soon as the man in charge knows that the +last nitration is finished, he refills this smaller tank (which contains +just enough of the mixed acids), and allows its contents to flow down into +the nitrating house and into the nitrator, ready for the next nitration. +The nitration is usually conducted in a vessel constructed of lead, some 4 +feet wide at the bottom, and rather less at the top, and about 4 feet or +so high. The size, of course, depends upon the volume of the charge it is +intended to nitrate at one operation, but it is always better that the +tank should be only two-thirds full. A good charge is 16 cwt. of the mixed +acids, in the proportion of three to five; that is, 6 cwt. of nitric acid, +and 10 cwt. of sulphuric acid, and 247 lbs. of glycerine. + +Upon reference to the equation showing the formation of nitro-glycerine, +it will be seen that for every 1 lb. of glycerine 2.47 lbs. of nitro- +glycerine should be furnished,[A] but in practice the yield is only a +little over 2 lbs., the loss being accounted for by the unavoidable +formation of some of the lower nitrate of glycerine (the mono-nitrate), +which afterward dissolves in the washing waters. The lead tank (Fig. 5) is +generally cased in woodwork, with a platform in front for the man in +charge of the nitrating to stand upon, and whence to work the various +taps. The top of the tank is closed in with a dome of lead, in which is a +small glass window, through which the progress of the nitrating operation +can be watched. From the top of this dome is a tube of lead which is +carried up through the roof of the building. It serves as a chimney to +carry off the acid fumes which are given off during the nitration. The +interior of this tank contains at least three concentric spirals of at +least 1-inch lead pipe, through which water can be made to flow during the +_whole_ operation of nitrating. Another lead pipe is carried through the +dome of the tank, as far as the bottom, where it is bent round in the form +of a circle. Through this pipe, which is pierced with small holes, about 1 +inch apart, compressed air is forced at a pressure of about 60 lbs. in +order to keep the liquids in a state of constant agitation during the +whole period of nitration. There must also be a rather wide pipe, of say 2 +inches internal diameter, carried through the dome of the tank, which will +serve to carry the mixed acid to be used in the operation into the tank. +There is still another pipe to go through the dome, viz., one to carry the +glycerine into the tank. This need not be a large bore pipe, as the +glycerine is generally added to the mixed acids in a thin stream (an +injector is often used). + +[Footnote A: Thus if 92 lbs. glycerine give 227 lbs. nitro-glycerine, +(277 x 1)/92 = 2.47 lbs.] + +[Illustration: FIG. 5.--TOP OF NITRATOR. _A_, Fume Pipe; _B_, Water Pipes +for Cooling; _C_, Acid Mixture Pipe; _E_, Compressed Air; _G_, Glycerine +Pipe and Funnel; _T_, Thermometer; _W_, Window.] + +Before the apparatus is ready for use, it requires to have two +thermometers fixed, one long one to reach to the bottom of the tank, and +one short one just long enough to dip under the surface of the acids. When +the tank contains its charge, the former gives the temperature of the +bottom, and the latter of the top of the mixture. The glycerine should be +contained in a small cistern, fixed in some convenient spot upon the wall +of the nitrating house, and should have a pipe let in flush with the +bottom, and going through the dome of the nitrating apparatus. It must of +course be provided with a tap or stop-cock, which should be placed just +above the point where the pipe goes through the lead dome. + +Some method of measuring the quantity of glycerine used must be adopted. A +gauge-tube graduated in inches is a very good plan, but it is essential +that the graduations should be clearly visible to the operator upon the +platform in front of the apparatus. A large tap made of earthenware (and +covered with lead) is fixed in the side of the nitrating tank just above +the bottom, to run off the charge after nitration. This should be so +arranged that the charge may be at option run down the conduit to the next +house or discharged into a drowning tank, which may sometimes be necessary +in cases of decomposition. The drowning tank is generally some 3 or 4 +yards long and several feet deep, lined with cement, and placed close +outside the building. + +The apparatus having received a charge of mixed acids, the water is +started running through the pipes coiled inside the tank, and a slight +pressure of compressed air is turned on,[A] to mix the acids up well +before starting. The nitration should not be commenced until the two +thermometers register a temperature of 18° C. The glycerine tap is then +partially opened, and the glycerine slowly admitted, and the compressed +air turned on full, until the contents of the apparatus are in a state of +very brisk agitation. A pressure of about 40 lbs. is about the minimum (if +247 lbs. of glycerine and 16 cwt. of acids are in the tank). If the +glycerine tube is fitted with an injector, it may be turned on almost at +once. The nitration will take about thirty minutes to complete, but the +compressed air and water should be kept on for an additional ten minutes +after this, to give time for all the glycerine to nitrate. The temperature +should be kept as low as possible (not above 18° C.). + +[Footnote A: At the Halton Factory, Germany, cylinders of compressed +carbon dioxide are connected with the air pipes so that in the event of a +failure of the air supply the stirring can be continued with this gas if +necessary.] + +The chief points to attend to during the progress of the nitration are-- + +1. The temperature registered by the two thermometers. + +2. The colour of the nitrous fumes given off (as seen through the little +window in the dome of the apparatus). + +3. The pressure of the compressed air as seen from a gauge fixed upon the +air pipe just before it enters the apparatus. + +4. The gauge showing the quantity of glycerine used. The temperature, as +shown by either of the two thermometers, should not be at any time higher +than 25° C. + +If it rises much above this point, the glycerine should be at once shut +off, and the pressure of air increased for some few minutes until the +temperature falls, and no more red fumes are given off. + +The nitration being finished, the large earthenware tap at the bottom of +the tank is opened, and the charge allowed to flow away down the conduit +to the next building, i.e., to the separator. + +The nitrating house is best built of wood, and should have a close-boarded +floor, which should be kept scrupulously clean, and free from grit and +sand. A wooden pail and a sponge should be kept in the house in order that +the workman may at once clean up any mess that may be made, and a small +broom should be handy, in order that any sand, &c., may be at once +removed. It is a good plan for the nitrator to keep a book in which he +records the time of starting each nitration, the temperature at starting +and at the finish, the time occupied, and the date and number of the +charge, as this enables the foreman of the danger area at any time to see +how many charges have been nitrated, and gives him other useful +information conducive to safe working. Edward Liebert has devised an +improvement in the treatment of nitro-glycerine. He adds ammonium sulphate +or ammonium nitrate to the mixed acids during the operation of nitrating, +which he claims destroys the nitrous acid formed according to the +equation-- + +(NH_{4})_{2}SO_{4} + 2HNO_{3} = H_{2}SO_{4} + 2N_{2} + 4H_{2}O. + +I am not aware that this modification of the process of nitration is in +use at the present time. + +The newly made charge of nitro-glycerine, upon leaving the nitrating +house, flows away down the conduit, either made of rubber pipes, or better +still, of woodwork, lined with lead and covered with lids made of wood (in +short lengths), in order that by lifting them at any point the condition +of the conduit can be examined, as this is of the greatest importance, and +the conduit requires to be frequently washed out and the sulphate of lead +removed. This sulphate always contains nitro-glycerine, and should +therefore be burnt in some spot far removed from any danger building or +magazine, as it frequently explodes with considerable violence. + +[Illustration: FIG. 6.--SMALL NITRATOR. _N_, Tap for Discharging; _P_, +Water Pipes; _T_, Thermometer; _W_, Windows; _P'_, Glycerine Pipe.] + +In works where the manufacture of nitro-glycerine is of secondary +importance, and some explosive containing only perhaps 10 per cent. of +nitroglycerine is manufactured, and where 50 or 100 lbs. of glycerine are +nitrated at one time, a very much smaller nitrating apparatus than the one +that has been already described will be probably all that is required. In +this case the form of apparatus shown in Fig. 6 will be found very +satisfactory. It should be made of stout lead (all lead used for tanks, +&c., must be "chemical lead"), and may be made to hold 50 or 100 lbs. as +found most convenient. This nitrator can very well be placed in the same +house as the separator; in fact, where such a small quantity of nitro- +glycerine is required, the whole series of operations, nitrating, +separation, and washing, &c., may very well be performed in the same +building. It will of course be necessary to place the nitrator on a higher +level than the separator, but this can easily be done by having platforms +of different heights, the nitration being performed upon the highest. The +construction of this nitrator is essentially the same as in the larger +one, the shape only being somewhat different. Two water coils will +probably be enough, and one thermometer. It will not be necessary to cover +this form in with woodwork. + +~The Nathan Nitrator.~[A]--This nitrator is the patent of Lt. Col. F.L. +Nathan and Messrs J.M. Thomson and W. Rintoul of Waltham Abbey, and will +probably before long entirely supersede all the other forms of nitrator on +account of its efficiency and economy of working. With this nitrator it is +possible to obtain from 2.21 to 2.22 parts of nitro-glycerine from every 1 +part of glycerine. The apparatus is so arranged that the nitration of the +glycerine, the separation of nitro-glycerine produced, as well as the +operation of "after-separation," are carried out in one vessel. The usual +nitrating vessel is provided with an acid inlet pipe at the bottom, and a +glass separation cylinder with a lateral exit or overflow pipe at the top. +This cylinder is covered by a glass hood or bell jar during nitration to +direct the escaping air and fumes into a fume pipe where the flow of the +latter may be assisted by an air injector. The lateral pipe in the +separation cylinder is in connection with a funnel leading to the prewash +tank. The drawing (Fig. 7) shows a vertical section of the apparatus; _a_ +is the nitrating vessel of usual construction, having at the bottom an +acid inlet pipe with three branches, one leading to the de-nitrating +plant, _c_ leading to the drowning tank, and _d_, which extends upwards +and has two branches, _e_ leading to the nitrating acids tank, and _f_ to +the waste acid tank. On the sloped bottom of the nitrating vessel _a_ lies +a coil _g_ of perforated pipe for blowing air, and there are in the vessel +several coils _h_, three shown in the drawing, for circulation of cooling +water. At the top of the vessel there is a glass cylinder _i_, having a +lateral outlet _j_ directed into the funnel mouth of a pipe _k_ leading to +the prewash tank. Over the cylinder _i_ is a glass globe _l_, into which +opens a pipe _m_ for leading off fumes which may be promoted by a +compressed air jet from a pipe _r_ operating as an injector. Into an +opening of the glass dome _l_ is inserted a vessel _n_, which is connected +by a flexible pipe _p_ to the glycerine tank, and from the bottom of _n_, +which is perforated and covered with a disc perforated with holes +registering with those through the bottom, this disc being connected by a +stem with a knob _q_ by which it can be turned so as to throttle or cut +off passage of glycerine through the bottom. _s_ is a thermometer for +indicating the temperature of the contents of the vessel. + +[Footnote A: Eng. Pat. 15,983, August 1901.] + +[Illustration: FIG. 7.--NATHAN'S NITRATOR FOR NITRO-GLYCERINE. (_a_) +Nitrating Vessel; (_b_) to Separating Vessel; (_c_) to Drowning Tank; +(_e_) Nitrating Acids enter (_f_) to the Waste Acids; (_g_) Coils for +Compressed Air; (_h_) Pipes for Cooling Water; (_i_) Glass Cylinder; (_j_) +Outlet to _k_; (_k_) leading to Prewash Tank; (_l_) Glass Dome; (_m_) Pipe +to lead off for Escape of Fumes; (_n_) Vessel; (_p_) Pipe conveying +Glycerine; (_q_) Knob to turn off Glycerine; (_r_) Compressed Air Jet; +(_s_) Thermometer.] + +In operating with this apparatus the nitrating acid is introduced into the +nitrating vessel by opening the cock of the pipe _e_. The glycerine is +then run in by introducing _n_ and opening the valve at its bottom, the +contents of the vessel being agitated by air blown through the +perforations of the pipe _g_. When the glycerine is all nitrated and the +temperature has slightly fallen, the circulation of the water through the +coils _h_ and the air-stirring are stopped, and the glycerine supply +vessel _n_ is removed. The nitro-glycerine as it separates from the acids +is raised by introducing by the pipe _f_ waste acid from a previous +charge, this displacing the nitro-glycerine upwards and causing it to flow +by the outlet, _j_ and pipe _k_ to the prewash tank. When nearly all the +nitro-glycerine has been separated in this manner the acids in the +apparatus may be run off by the pipe _b_ to an after separating vessel for +further settling, thus leaving the apparatus free for another nitration, +or the nitrating vessel itself may be used as an after separating bottle +displacing the nitro-glycerine with waste acid as it rises to the top, or +skimming off in the usual manner. When the separation of the nitro- +glycerine is complete the waste acid is run off and denitrated as usual, a +portion of it being reserved for the displacement of the nitro-glycerine +in a subsequent operation. + +In a further patent (Eng. Pat. 3,020, 1903) the authors propose with the +object of preventing the formation and separation of nitro-glycerine in +the waste acids, after the nitro-glycerine initially formed in the +nitrating vessel has been separated and removed, to add a small quantity +of water to the waste acids; this is carried out as follows. A relatively +small quantity of water is added, and this prevents all further separation +of nitro-glycerine, and at the same time the strength of the waste acids +is so slightly reduced that their separation and re-concentration are not +affected. "After-separation" is thus done away with, and the nitro- +glycerine plant simplified and its output increased. After nitration +separation is commenced at a temperature such that when all the displacing +acid has been added, and the separation of the nitro-glycerine is +complete, the temperature of the contents of the nitrating vessel shall +not be lower than 15° C. A sufficient quantity of the displacing acid is +then run off through the waste-acid cock to allow of the remaining acids +being air-stirred without splashing over the top. A small quantity of +water, from 2 to 3 per cent. according to strength of acid; if waste +consists of sulphuric acid (monohydrate), 62 per cent.; nitric acid +(anhydrous), 33 per cent. and water 5 per cent.; temperature 15° C., then +2 per cent. of water is added; if waste acids contain less than 4 per +cent. of water of temperature lower than 15° C., from 3 to 5 per cent. of +water may have to be added. The water is added slowly through the +separator cylinder, and the contents of the nitrator air-stirred, but not +cooled, the temperature being allowed to rise slowly and regularly as the +water is added--usually about 3° C. for each per cent. of water added. +When air-agitation has been stopped, the acids are kept at rest for a +short time, in order to allow of any small quantity of initially formed +nitro-glycerine adhering to the coils and sides of the vessel rising to +the top. When this has been separated by displacement, the acids are ready +for denitration, or can be safely stored without further precaution. + +~Separation.~--The nitro-glycerine, together with the mixed acids, flows +from the nitrating house to the separating house, which must be on a lower +level than the former. The separating house contains a large lead-lined +tank, closed in at the top with a wooden lid, into which a lead pipe of +large bore is fixed, and which is carried up through the roof of the +building, and acts as a chimney to carry off any fumes. A little glass +window should be fixed in this pipe in order that the colour of the +escaping fumes may be seen. The conduit conveying the nitro-glycerine +enters the building close under the roof, and discharges its contents into +the tank through the pipe G (Fig. 8). The tank is only about two-thirds +filled by the charge. There is in the side of the tank a small window of +thick plate glass, which enables the workman to see the level of the +charge, and also to observe the progress of the separation, which will +take from thirty minutes to one hour. + +The tank should be in connection with a drowning tank, as the charge +sometimes gets very dangerous in this building. It must also be connected +by a conduit with the filter house, and also to the secondary separator by +another conduit. The tank should also be fitted with a compressed air +pipe, bent in the form of a loop. It should lie upon the bottom of the +vat. The object of this is to mix up the charge in case it should get too +hot through decomposition. A thermometer should of course be fixed in the +lid of the tank, and its bulb should reach down to the middle of the +nitro-glycerine (which rests upon the surface of the mixed acids, the +specific gravity of the nitro-glycerine being 1.6, and that of the waste +acids 1.7; the composition of the acids is now 11 per cent. HNO_{3}, 67 +per cent. H_{2}SO_{4}, and 22 per cent. water), and the temperature +carefully watched. + +[Illustration: FIG. 8.--SEPARATOR. _A_, Compressed Air Pipes; _G_, Nitro- +glycerine enters from Nitrator; _N_, Nitro-glycerine to _P_; _L_, Lantern +Window; _W_, Window in Side; _S_, Waste Acids to Secondary Separator; _T_, +Tap to remove last traces of Nitro-glycerine; _P_, Lead Washing Tank; _A_, +Compressed Air; _W_, Water Pipe; _N_, Nitro-glycerine from Separator.] + +If nothing unusual occurs, and it has not been necessary to bring the +compressed air into use, and so disturb the process of separation, the +waste acids may be run away from beneath the nitro-glycerine, and allowed +to flow away to the secondary separator, where any further quantity of +nitro-glycerine that they contain separates out after resting for some +days. The nitro-glycerine itself is run into a smaller tank in the same +house, where it is washed three or four times with its own bulk of water, +containing about 3 lbs. of carbonate of soda to neutralise the remaining +acid. This smaller tank should contain a lead pipe, pierced and coiled +upon the bottom, through which compressed air may be passed, in order to +stir up the charge with the water and soda. After this preliminary +washing, the nitro-glycerine is drawn off into indiarubber buckets, and +poured down the conduit to the filter house. The wash waters may be sent +down a conduit to another building, in order to allow the small quantity +of nitro-glycerine that has been retained in the water as minute globules +to settle, if thought worth the trouble of saving. This, of course, will +depend upon the usual out-turn of nitro-glycerine in a day, and the +general scale of operations. + +[Illustration: FIG. 9.--FILTERING AND WASHING PLANT. _W_, Lead Washing +Tank; _WP_, Water Pipe; _L_, Lid; _S_, Nitro-glycerine from Separator; _A, +B, C_, Filtering Tanks; _B2_, Indiarubber Bucket.] + +~Filtering and Washing.~--The filter house (Fig. 9), which must of course +be again on a somewhat lower level than the separating house, must be a +considerably larger building than either the nitrating or separating +houses, as it is always necessary to be washing some five or six charges +at the same time. Upon the arrival of the nitro-glycerine at this house, +it first flows into a lead-lined wooden tank (W), containing a compressed +air pipe, just like the one in the small tank in the separating house. +This tank is half filled with water, and the compressed air is turned on +from half to a quarter of an hour after the introduction of the charge. +The water is then drawn off, and fresh water added. Four or five washings +are generally necessary. The nitro-glycerine is then run into the next +tank (A), the top of which is on a level with the bottom of the first one. +Across the top of this tank is stretched a frame of flannel, through which +the nitroglycerine has to filter. This removes any solid matters, such as +dirt or scum. Upon leaving this tank, it passes through a similar flannel +frame across another tank (B), and is finally drawn off by a tap in the +bottom of the tank into rubber buckets. The taps in these tanks are best +made of vulcanite. + +At this stage, a sample should be taken to the laboratory and tested. If +the sample will not pass the tests, which is often the case, the charge +must be rewashed for one hour, or some other time, according to the +judgment of the chemist in charge. In the case of an obstinate charge, it +is of much more avail to wash a large number of times with small +quantities of water, and for a short time, than to use a lot of water and +wash for half an hour. Plenty of compressed air should be used, as the +compound nitric ethers which are formed are thus got rid of. As five or +six charges are often in this house at one time, it is necessary to have +as many tanks arranged in tiers, otherwise one or two refractory charges +would stop the nitrating house and the rest of the nitro-glycerine plant. +The chief causes of the washed material not passing the heat test are, +either that the acids were not clean, or they contained objectionable +impurities, or more frequently, the quality of the glycerine used. The +glycerine used for making nitro-glycerine should conform to the following +tests, some of which, however, are of greater importance than others. The +glycerine should-- + +1. Have minimum specific gravity at 15° C. of 1.261. + +2. Should nitrify well. + +3. Separation should be sharp within half an hour, without the separation +of flocculent matter, nor should any white flocculent matter (due to fatty +acids) be formed when the nitrated glycerine is thrown into water and +neutralised with carbonate of soda. + +4. Should be free from lime and chlorine, and contain only traces of +arsenic, sulphuric acid, &c. + +5. Should not leave more than 0.25 per cent. of inorganic and organic +residue together when evaporated in a platinum dish without ebullition +(about 160° C.) or partial decomposition. + +6. Silver test fair. + +7. The glycerine, when diluted one-half, should give no deposit or +separation of fatty acids when nitric peroxide gas is passed through it. +(Nos. 1, 2, 3, and 5 are the most essential.) + +The white flocculent matter sometimes formed is a very great nuisance, and +any sample of glycerol which gives such a precipitate when tried in the +laboratory should at once be rejected, as it will give no end of trouble +in the separating house, and also in the filter house, and it will be very +difficult indeed to make the nitro-glycerine pass the heat test. The out- +turn of nitro-glycerine also will be very low. The trouble will show +itself chiefly in the separating operation. Very often 2 or 3 inches will +rise to the surface or hang about in the nitro-glycerine, and at the point +of contact between it and the mixed acids, and will afterwards be very +difficult to get rid of by filtration. The material appears to be partly +an emulsion of the glycerine, and partly due to fatty acids, and as there +appears to be no really satisfactory method of preventing its formation, +or of getting rid of it, the better plan is not to use any glycerine for +nitrating that has been found by experiment upon the laboratory scale to +give this objectionable matter. One of the most useful methods of testing +the glycerine, other than nitrating, is to dilute the sample one-half with +water, and then to pass a current of nitric peroxide gas through it, when +a flocculent precipitate of elaïdic acid (less soluble in glycerine than +the original oleic acid) will be formed. Nitrogen peroxide, N_{2}O_{4}, is +best obtained by heating dry lead nitrate (see Allen, "Commercial Organic +Analysis," vol. ii., 301). + +When a sample of nitro-glycerine is brought to the laboratory from the +filter house, it should first be examined to see that it is not acid.[A] A +weak solution of Congo red or methyl orange may be used. If it appears to +be decidedly alkaline, it should be poured into a separating funnel, and +shaken with a little distilled water. This should be repeated, and the +washings (about 400 c.c.) run into a beaker, a drop of Congo red or methyl +orange added, and a drop or so of N/2 hydrochloric acid added, when it +should give, with two or three drops at most, a blue colour with the Congo +red, or pink with the methyl orange, &c. The object of this test is to +show that the nitro-glycerine is free from any excess of soda, i.e., that +the soda has been properly washed out, otherwise the heat test will show +the sample to be better than it is. The heat test must also be applied. + +[Footnote A: A. Leroux, _Bul. Soc. Chim. de Bel._, xix., August 1905, +contends that experience does not warrant the assumption that free acid is +a source of danger in nitro-glycerine or nitro-cellulose; free alkali, he +states, promotes their decomposition.] + +Upon leaving the filter house, where it has been washed and filtered, and +has satisfactorily passed the heat test, it is drawn off from the lowest +tank in indiarubber buckets, and poured down the conduit leading to the +precipitating house, where it is allowed to stand for a day, or sometimes +longer, in order to allow the little water it still contains to rise to +the surface. In order to accomplish this, it is sufficient to allow it to +stand in covered-in tanks of a conical form, and about 3 or 4 feet high. +In many works it is previously filtered through common salt, which of +course absorbs the last traces of water. It is then of a pale yellow +colour, and should be quite clear, and can be drawn off by means of a tap +(of vulcanite), fixed at the bottom of the tanks, into rubber buckets, and +is ready for use in the preparation of dynamite, or any of the various +forms of gelatine compounds, smokeless powders, &c., such as cordite, +ballistite, and many others. + +Mikolajezak (_Chem. Zeit._, 1904, Rep. 174) states that he has prepared +mono- and di-nitro-glycerine, and believes that the latter compound will +form a valuable basis for explosives, as it is unfreezable. It is stated +to be an odourless, unfreezable oil, less sensitive to percussion, +friction, and increase of temperature, and to possess a greater solvent +power for collodion-cotton than ordinary nitro-glycerine. It can thus be +used for the preparation of explosives of high stability, which will +maintain their plastic nature even in winter. The di-nitro-glycerine is a +solvent for tri-nitro-glycerine, it can therefore be mixed with this +substance, in the various gelatine explosives in order to lower the +freezing point. + +~The Waste Acids.~--The waste acids from the separating house, from which +the nitro-glycerine has been as completely separated as possible, are run +down the conduit to the secondary separator, in order to recover the last +traces of nitro-glycerine that they contain. The composition of the waste +acids is generally somewhat as follows:--Specific gravity, 1.7075 at 15° +C.; sulphuric acid, 67.2 per cent.; nitric acid, 11.05 per cent.; and +water, 21.7 per cent., with perhaps as much as 2 per cent. of nitric +oxide, and of course varying quantities of nitro-glycerine, which must be +separated, as it is impossible to run this liquid away (unless it can be +run into the sea) or to recover the acids by distillation as long as it +contains this substance. The mixture, therefore, is generally run into +large circular lead-lined tanks, covered in, and very much like the +nitrating apparatus in construction, that is, they contain worms coiled +round inside, to allow of water being run through to keep the mixture +cool, and a compressed air pipe, in order to agitate the mixture if +necessary. The top also should contain a window, in order to allow of the +interior being seen, and should have a leaden chimney to carry off the +fumes which may arise from decomposition. It is also useful to have a +glass tube of 3 or 4 inches in diameter substituted for about a foot of +the lead chimney, in order that the man on duty can at any time see the +colour of the fumes arising from the liquid. There should also be two +thermometers, one long one reaching to the bottom of the tank, and one to +just a few inches below the surface of the liquid. + +The nitro-glycerine, of course, collects upon the surface, and can be +drawn off by a tap placed at a convenient height for the purpose. The +cover of the tank is generally conical, and is joined to a glass cylinder, +which is cemented to the top of this lead cover, and also to the lead +chimney. In this glass cylinder is a hole into which fits a ground glass +stopper, through which the nitro-glycerine can be drawn off. There will +probably never be more than an inch of nitro-glycerine at the most, and +seldom that. It should be taken to the filter house and treated along with +another charge. The acids themselves may either be run to waste, or better +treated by some denitration plant. This house probably requires more +attention than any other in the danger area, on account of the danger of +the decomposition of the small quantities of nitro-glycerine, which, as it +is mixed with such a large quantity of acids and water, is very apt to +become hot, and decomposition, which sets up in spots where a little +globule of nitro-glycerine is floating, surrounded by acids that gradually +get hot, gives off nitrous fumes, and perhaps explodes, and thus causes +the sudden explosion of the whole. The only way to prevent this is for the +workman in charge to look at the thermometers _frequently_, and at the +colour of the escaping fumes, and if he should notice a rise of +temperature or any appearance of red fumes, to turn on the water and air, +and stir up the mixture, when probably the temperature will suddenly fall, +and the fumes cease to come off. + +The cause of explosions in this building is either the non-attention of +the workmen in charge, or the bursting of one of the water pipes, by which +means, of course, the water, finding its way into the acids, causes a +sudden rise of temperature. If the latter of these two causes should +occur, the water should at once be shut off and the air turned on full, +but if it is seen that an explosion is likely to occur, the tank should at +once be emptied by allowing its contents to run away into a drowning tank +placed close outside the house, which should be about 4 feet deep, and +some 16 feet long by 6 feet wide; in fact, large enough to hold a +considerable quantity of water. But this last course should only be +resorted to as a last extremity, as it is extremely troublesome to recover +the small quantity of nitro-glycerine from the bottom of this tank, which +is generally a bricked and cemented excavation some few yards from the +house. + +It has been proposed to treat these waste acids, containing nitro- +glycerine, in Mr M. Prentice's nitric acid retort. In this case they would +be run into the retort, together with nitrate of soda, in a fine stream, +and the small quantity of nitro-glycerine, coming into contact with the +hot mixture already in the retort, would probably be at once decomposed. +This process, although not yet tried, promises to be a success. Several +processes have been used for the denitration of these acids. + +~Treatment of the Waste Acid from the Manufacture of Nitro-Glycerine and +Gun-Cotton.~--The composition of these acids is as follows:-- + + Nitro-glycerine and Gun-cotton + Waste Acid. + +Sulphuric acid 70 per cent. 78 per cent. +Nitric acid 10 " 12 " +Water 20 " 10 " + +The waste acid from the manufacture of gun-cotton is generally used direct +for the manufacture of nitric acid, as it contains a fairly large amount +of sulphuric acid, and the small amount of nitro-cellulose which it also +generally contains decomposes gradually and without explosion in the +retort. Nitric acid may be first distilled off, the resulting sulphuric +acid being then added to the equivalent amount of nitrate of soda. Nitric +acid is then distilled over and condensed in the usual way. Very often, +however, the waste acid is added direct to the charge of nitrate without +previously eliminating the nitric acid. The treatment of the waste acid +from the manufacture of nitro-glycerine is somewhat different. The small +amount of nitro-glycerine in this acid must always be eliminated. This is +effected either by allowing the waste acid to stand for at least twenty- +four hours in a big vessel with a conical top, where all the nitro- +glycerine which will have separated to the surface is removed by skimming; +or, better still, the "watering down process" of Col. Nathan may be +employed. In Nathan's nitrator every existing trace of nitro-glycerine is +separated from the acids in a few hours after the nitration, and any +further formation of nitro-glycerine is prevented by adding about 2 per +cent. of water to the waste acids, which are kept agitated during the +addition. The waste acid, now free from nitro-glycerine, but which may +still contain organic matter, is denitrated by bringing it into contact +with a jet of steam. The waste acid is passed in a small stream down +through a tower of acid-resisting stoneware (volvic stone), which is +closely packed with earthenware, and at the bottom of which is the steam +jet. Decomposition proceeds as the acid meets the steam, nitric and +nitrous acids are disengaged and are passed out at the top of the tower +through a pipe to a series of condensers and towers, where the nitric acid +is collected. The nitrous acid may be converted into nitric acid by +introducing a hot compressed air jet into the gases before they pass into +the condensers. Weak sulphuric acid of sp. gr. 1.6 collects in a saucer in +which the tower stands, and is then passed through a cooling worm. The +weak sulphuric acid, now entirely free from nitric and nitrous acids, may +be concentrated to sp. gr. 1.842 and 96 per cent. H_{2}SO_{4} by any of +the well-known processes, e.g., Kessler, Webb, Benker, Delplace, &c., and +it may be used again in the manufacture of nitro-glycerine or gun-cotton. + +Two points in the manufacture of nitro-glycerine are of the greatest +importance, viz., the purity of the glycerine used, and the strength and +purity of the acids used in the nitration. With regard to the first of +these, great care should be taken, and a complete analysis and thorough +examination, including a preliminary experimental nitration, should always +be instituted. As regards the second, the sulphuric acid should not only +be strong (96 per cent.), but as free from impurities as possible. With +the nitric acid, which is generally made at the explosive works where it +is used, care must be taken that it is as strong as possible (97 per cent. +and upwards). This can easily be obtained if the plant designed by Mr +Oscar Guttmann[A] is used. Having worked Mr Guttmann's plant for some +time, I can testify as to its value and efficiency. + +[Footnote A: "The Manufacture of Nitric Acid," _Jour. Soc. Chem. Ind._, +March 1893.] + +Another form of nitric acid plant, which promises to be of considerable +service to the manufacturer of nitric acid for the purpose of nitrating, +is the invention of the late Mr Manning Prentice, of Stowmarket. Through +the kindness of Mr Prentice, I visited his works to see the plant in +operation. It consists of a still, divided into compartments or chambers +in such a manner that the fluid may pass continuously from one to the +other. The nitric acid being continuously separated by distillation, the +contents of each division vary--the first containing the full proportion +of nitric acid, and each succeeding one less of the nitric acid, until +from the overflow of the last one the bisulphate of soda flows away +without any nitric acid. The nitrate of soda is placed in weighed +quantities in the hopper, whence it passes to the feeder. The feeder is a +miniature horizontal pug-mill, which receives the streams of sulphuric +acid and of nitrate, and after thoroughly mixing them, delivers them into +the still, where, under the influence of heat, they rapidly become a +homogeneous liquid, from which nitric acid continuously distils. + +Mr Prentice says: "I may point out that while the ordinary process of +making nitric acid is one of fractional distillation by time, mine is +fractional distillation by space." "Instead of the operation being always +at the same point of space, but differing by the successive points of +time, I arrange for the differences to take place at different points of +space, and these differences exist at one and the same points of time." It +is possible with this plant to produce the full product of nitric acid of +a gravity of 1.500, or to obtain the acid of varying strengths from the +different still-heads. One of these stills, capable of producing about 4 +tons of nitric acid per week, weighs less than 2 tons. It is claimed that +there is by their use a saving of more than two-thirds in fuel, and four- +fifths in condensing plant. Further particulars and illustrations will be +found in Mr Prentice's paper (_Journal of the Society of Chemical +Industry_, 1894, p. 323). + + + + +CHAPTER III. + +_NITRO-CELLULOSE, &c._ + +Cellulose Properties--Discovery of Gun-Cotton--Properties of Gun-Cotton-- +Varieties of Soluble and Insoluble Gun-Cottons--Manufacture of Gun-Cotton-- +Dipping and Steeping--Whirling out the Acid--Washing--Boiling--Pulping-- +Compressing--The Waltham Abbey Process--Le Bouchet Process--Granulation of +Gun-Cotton--Collodion-Cotton--Manufacture--Acid Mixture used--Cotton used, +&c.--Nitrated Gun-Cotton--Tonite--Dangers in Manufacture of Gun-Cotton-- +Trench's Fire-Extinguishing Compound--Uses of Collodion-Cotton--Celluloid-- +Manufacture, &c.--Nitro-Starch, Nitro-Jute, and Nitro-Mannite. + + +~The Nitro-Celluloses.~--The substance known as cellulose forms the +groundwork of vegetable tissues. The cellulose of the woody parts of +plants was at one time supposed to be a distinct body, and was called +lignine, but they are now regarded as identical. The formula of cellulose +is (C_{6}H_{10}O_{6})_{X}, and it is generally assumed that the molecular +formula must be represented by a multiple of the empirical formula, +C_{12}H_{20}O_{10} being often regarded as the minimum. The assumption is +based on the existence of a penta-nitrate and the insoluble and colloidal +nature of cellulose. Green (_Zeit. Farb. Text. Ind._, 1904, 3, 97) +considers these reasons insufficient, and prefers to employ the single +formula C_{6}H_{10}O_{5}. Cellulose can be extracted in the pure state, +from young and tender portions of plants by first crushing them, to +rupture the cells, and then extracting with dilute hydrochloric acid, +water, alcohol, and ether in succession, until none of these solvents +remove anything more. Fine paper or cotton wool yield very nearly pure +cellulose by similar treatment. + +Cellulose is a colourless, transparent mass, absolutely insoluble in +water, alcohol, or ether. It is, however, soluble in a solution of +cuprammoniac solution, prepared from basic carbonate or hydrate of copper +and aqueous ammonia. The specific gravity of cellulose is 1.25 to 1.45. +According to Schulze, its elementary composition is expressed by the +percentage numbers:-- + +Carbon 44.0 per cent. 44.2 per cent. +Hydrogen 6.3 " 6.4 " +Oxygen 49.7 " 49.4 " + +These numbers represent the composition of the ash free cellulose. Nearly +all forms of cellulose, however, contain a small proportion of mineral +matters, and the union of these with the organic portion of the fibre or +tissue is of such a nature that the ash left on ignition preserves the +form of the original. "It is only in the growing point of certain young +shoots that the cellulose tissue is free from mineral constituents" +(Hofmeister). + +Cellulose is a very inert body. Cold concentrated sulphuric acid causes it +to swell up, and finally dissolves it, forming a viscous solution. +Hydrochloric acid has little or no action, but nitric acid has, and forms +a series of bodies known as nitrates or nitro-celluloses. Cellulose has +some of the properties of alcohols, among them the power of forming +ethereal salts with acids. When cellulose in any form, such as cotton, is +brought into contact with strong nitric acid at a low temperature, a +nitrate or nitro product, containing nitryl, or the NO_{2} group, is +produced. The more or less complete replacement of the hydroxylic hydrogen +by NO_{2} groups depends partly on the concentration of the nitric acid +used, partly on the duration of the action. If the most concentrated +nitric and sulphuric acids are employed, and the action allowed to proceed +for some considerable time, the highest nitrate, known as hexa-nitro- +cellulose or gun-cotton, C_{12}H_{14}O_{4}(O.NO_{2})_{6}, will be formed; +but with weaker acids, and a shorter exposure to their action, the tetra +and penta and lower nitrates will be formed.[A] + +[Footnote A: The paper by Prof. Lunge, _Jour. Amer. Chem. Soc._, 1901, +23[8], 527-579, contains valuable information on this subject.] + +Besides the nitrate, A. Luck[A] has proposed to use other esters of +cellulose, such as the acetate, benzoate, or butyrate. It is found that +cellulose acetate forms with nitro-glycerine a gelatinous body without +requiring the addition of a solvent. A sporting powder is proposed +composed of 75 parts of cellulose nitrate (13 per cent. N.) mixed with 13 +parts of cellulose acetate. + +[Footnote A: Eng. Pat. 24,662, 22nd November 1898.] + +The discovery of gun-cotton is generally attributed to Schönbein (1846), +but Braconnot (in 1832) had previously nitrated starch, and six years +later Pelouse prepared nitro-cotton and various other nitro bodies, and +Dumas nitrated paper, but Schönbein was apparently the first chemist to +use a mixture of strong nitric and sulphuric acids. Many chemists, such as +Piobert in France, Morin in Russia, and Abel in England, studied the +subject; but it was in Austria, under the auspices of Baron Von Lenk, that +the greatest progress was made. Lenk used cotton in the form of yarn, made +up into hanks, which he first washed in a solution of potash, and then +with water, and after drying dipped them in the acids. The acid mixture +used consisted of 3 parts by weight of sulphuric to 1 part of nitric acid, +and were prepared some time before use. The cotton was dipped one skein at +a time, stirred for a few minutes, pressed out, steeped, and excess of +acid removed by washing with water, then with dilute potash, and finally +with water. Von Lenk's process was used in England at Faversham (Messrs +Hall's Works), but was given up on account of an explosion (1847). + +Sir Frederick Abel, working at Stowmarket and Waltham Abbey, introduced +several very important improvements into the process, the chief among +these being pulping. Having traced the cause of its instability to the +presence of substances caused by the action of the nitric acid on the +resinous or fatty substances contained in the cotton fibre, he succeeded +in eliminating them, by boiling the nitro-cotton in water, and by a +thorough washing, after pulping the cotton in poachers. + +Although gun-cottons are generally spoken of as nitro-celluloses, they are +more correctly described as cellulose nitrates, for unlike nitro bodies of +other series, they do not yield, or have not yet done so, amido bodies, on +reduction with nascent hydrogen.[A] The equation of the formation of +gun-cotton is as follows:-- + +2(C_{6}H_{10}O_{5}) + 6HNO_{3} = C_{12}H_{14}O_{4}(NO_{3})_{6} + 6OH_{2}. + Cellulose. Nitric Acid. Gun-Cotton. Water. + +The sulphuric acid used does not take part in the reaction, but its +presence is absolutely essential to combine with the water set free, and +thus to prevent the weakening of the nitric acid. The acid mixture used at +Waltham Abbey consists of 3 parts by weight of sulphuric acid of 1.84 +specific gravity, and 1 part of nitric acid of 1.52 specific gravity. The +same mixture is also used at Stowmarket (the New Explosive Company's +Works). The use of weaker acids results in the formation of collodion- +cotton and the lower nitrates generally. + +[Footnote A: "Cellulose," by Cross and Bevan, ed. by W.R. Hodgkinson, p. +9.] + +The nitrate which goes under the name of gun-cotton is generally supposed +to be the hexa-nitrate, and to contain 14.14 per cent. of nitrogen; but a +higher percentage than 13.7 has not been obtained from any sample. It is +almost impossible (at any rate upon the manufacturing scale) to make pure +hexa-nitro-cellulose or gun-cotton; it is certain to contain several per +cents. of the soluble forms, i.e., lower nitrates. It often contains as +much as 15 or 16 per cent., and only from 13.07[A] to 13.6 per cent. of +nitrogen. + +[Footnote A: Mr J.J. Sayers, in evidence before the court in the "Cordite +Case," says he found 15.2 and 16.1 per cent. soluble cotton, and 13.07 and +13.08 per cent. nitrogen in two samples of Waltham Abbey gun-cotton.] + +A whole series of nitrates of cellulose are supposed to exist, the highest +member being the hexa-nitrate, and the lowest the mono-nitrate. Gun-cotton +was at one time regarded as the tri-nitrate, and collodion-cotton as the +di-nitrate and mono-nitrate, their respective formula being given as +follows:-- + +Mono-nitro-cellulose C_{6}H_{9}(NO_{2})O_{5} = 6.763 per cent. nitrogen. +Di-nitro-cellulose C_{6}H_{8}(NO_{2})_{2}O_{5} = 11.11 " " +Tri-nitro-cellulose C_{6}H_{7}(NO_{2})_{3}O_{5} = 14.14 " " + +But gun-cotton is now regarded as the hexa-nitrate, and collodion-cotton +as a mixture of all the other nitrates. In fact, chemists are now more +inclined to divide nitro-cellulose into the soluble and insoluble forms, +the reason being that it is quite easy to make a nitro-cellulose entirely +soluble in a mixture of ether-alcohol, and yet containing as high a +percentage of nitrogen as 12.6; whereas the di-nitrate[A] should +theoretically only contain 11.11 per cent. On the other hand, it is not +possible to make gun-cotton with a higher percentage of nitrogen than +about 13.7, even when it does not contain any nitro-cotton that is soluble +in ether-alcohol.[B] The fact is that it is not at present possible to +make a nitro-cellulose which shall be either entirely soluble or entirely +insoluble, or which will contain the theoretical content of nitrogen to +suit any of the above formulæ for the cellulose nitrates. Prof. G. Lunge +gives the following list of nitration products of cellulose:-- + +[Footnote A: The penta-nitrate C_{12}H_{15}O_{5}(NO_{3})_{5} = 12.75 per +cent. nitrogen.] + +[Footnote B: In the Cordite Trial (1894) Sir F.A. Abel said, "Before 1888 +there was a broad distinction between soluble and insoluble nitro- +cellulose, collodion-cotton being soluble (in ether-alcohol) and +gun-cotton insoluble." Sir H.E. Roscoe, "That he had been unable to make a +nitro-cotton with a higher nitrogen content than 13.7." And Professor G. +Lunge said, "Gun-cotton always contained soluble cotton, and _vice +versa_." These opinions were also generally confirmed by Sir E. Frankland, +Sir W. Crookes, Dr Armstrong, and others.] + +Dodeca-nitro-cellulose C_{24}H_{28}O_{20}(NO_{2})_{12} = 14.16 per cent. + nitrogen. (= old tri-nitro-cellulose) +Endeca-nitro-cellulose C_{24}H_{29}O_{20}(NO_{2})_{11} = 13.50 per cent. + nitrogen. +Deca-nitro-cellulose C_{24}H_{30}O_{20}(NO_{2})_{10} = 12.78 per cent. + nitrogen. +Ennea-nitro-cellulose C_{24}H_{31}O_{20}(NO_{2})_{9} = 11.98 per cent. + nitrogen. +Octo-nitro-cellulose C_{24}H_{32}O_{20}(NO_{2})_{8} = 11.13 per cent. + nitrogen. (= old di-nitro-cellulose) +Hepta-nitro-cellulose C_{24}H_{33}O_{20}(NO_{2})_{7} = 10.19 per cent. + nitrogen. +Hexa-nitro-cellulose C_{24}H_{34}O_{20}(NO_{2})_{6} = 9.17 per cent. + nitrogen. +Penta-nitro-cellulose C_{24}H_{35}O_{20}(NO_{2})_{5} = 8.04 per cent. + nitrogen. +Tetra-nitro-cellulose C_{24}H_{36}O_{20}(NO_{2})_{4} = 6.77 per cent. + nitrogen. (= old mono-nitro-cellulose) + +It is not unlikely that a long series of nitrates exists. It is at any +rate certain that whatever strength of acids may be used, and whatever +temperature or other conditions may be present during the nitration, that +the product formed always consists of a mixture of the soluble and +insoluble nitro-cellulose. + +Theoretically 100 parts of cotton by weight should produce 218.4 parts of +gun-cotton, but in practice the yield is a good deal less, both in the +case of gun-cotton or collodion-cotton. In speaking of soluble and +insoluble nitro-cellulose, it is their behaviour, when treated with a +solution consisting of 2 parts ether and 1 of alcohol, that is referred +to. There is, however, another very important difference, and that is +their different solubility in nitro-glycerine. The lower nitrates or +soluble form is soluble in nitro-glycerine under the influence of heat, a +temperature of about 50° C. being required. At lower temperatures the +dissolution is very imperfect indeed; and after the materials have been +left in contact for days, the threads of the cotton can still be +distinguished. The insoluble form or gun-cotton is entirely _insoluble_ in +nitro-glycerine. It can, however, be made to dissolve[A] by the aid of +acetone or acetic ether. Both or rather all the forms of nitro-cellulose +can be dissolved in acetone or acetic ether. They also dissolve in +concentrated sulphuric acid, and the penta-nitrate in nitric acid at about +80° or 90° C. + +[Footnote A: Or rather to form a transparent jelly.] + +The penta-nitrate may be obtained in a pure state by the following +process, devised by Eder:--The gun-cotton is dissolved in concentrated +nitric acid at 90° C., and reprecipitated by the addition of concentrated +sulphuric acid. After cooling to 0° C., and mixing with a larger volume of +water, the precipitated nitrate is washed with water, then with alcohol, +dissolved in ether-alcohol, and again precipitated with water, when it is +obtained pure. This nitrate is soluble in ether-alcohol, and slightly in +acetic acid, easily in acetone, acetic ether, and methyl-alcohol, +insoluble in alcohol. Strong potash (KOH) solution converts into the +di-nitrate C_{12}H_{18}O_{8}(NO_{3})_{2}. The hexa-nitrate is not soluble +in acetic acid or methyl-alcohol. + +The lower nitrates known as the tetra- and tri-nitrates are formed +together when cellulose is treated with a mixture of weak acids, and +allowed to remain in contact with them for a very short time (twenty +minutes). They cannot be separated from one another, as they all dissolve +equally in ether-alcohol, acetic ether, acetic acid, methyl-alcohol, +acetone, amyl acetate, &c. + +As far as the manufacture of explosive bodies is concerned, the two forms +of nitro-cellulose used and manufactured are gun-cotton or the hexa- +nitrate (once regarded as tri-nitro-cellulose), which is also known as +insoluble gun-cotton, and the soluble form of gun-cotton, which is also +known as collodion, and consists of a mixture of several of the lower +nitrates. It is probable that it chiefly consists, however, of the next +highest nitrate to gun-cotton, as the theoretical percentage of nitrogen +for this body,. the penta-nitrate, is 12.75 per cent., and analyses of +commercial collodion-cotton, entirely soluble in ether-alcohol, often give +as high a percentage as 12.6. + +We shall only describe the manufacture of the two forms known as soluble +and insoluble, and shall refer to them under their better known names of +gun-cotton and collodion-cotton. The following would, however, be the +formulæ[A] and percentage of nitrogen of the complete series:-- + +Hexa-nitro-cellulose C_{12}H_{14}O_{4}(NO_{3})_{6} 14.14 per cent. + nitrogen. +Penta-nitro-cellulose C_{12}H_{15}O_{5}(NO_{3})_{5} 12.75 per cent. + nitrogen. +Tetra-nitro-cellulose C_{12}H_{16}O_{6}(NO_{3})_{4} 11.11 per cent. + nitrogen. +Tri-nitro-cellulose C_{12}H_{17}O_{7}(NO_{3})_{3} 9.13 per cent. + nitrogen. +Di-nitro-cellulose C_{12}H_{18}O_{8}(NO_{3})_{2} 7.65 per cent. + nitrogen. +Mono-nitrocellulose C_{12}H_{19}O_{9}(NO_{3}) 3.80 per cent. + nitrogen. + +[Footnote A: Berthelot takes C_{24}H_{40}O_{20} as the formula of +cellulose; and M. Vieille regards the highest nitrate as +(C_{24}H_{18}(NO_{3}H)_{11}O_{9}). _Compt. Rend._, 1882, p. 132.] + +~Properties of Gun-Cotton.~--The absolute density of gun-cotton is 1.5. +When in lumps its apparent density is 0.1; if twisted into thread, 0.25; +when subjected, in the form of pulp, to hydraulic pressure, 1.0 to 1.4. +Gun-cotton preserves the appearance of the cotton from which it is made. +It is, however, harsher to the touch; it is only slightly hygroscopic (dry +gun-cotton absorbs 2 per cent. of moisture from the air). It possesses the +property of becoming electrified by friction. It is soluble in acetic +ether, amyl acetate, and acetone, insoluble in water, alcohol, ether, +ether-alcohol, methyl-alcohol, &c. It is very explosive, and is ignited by +contact with an ignited body, or by shock, or when it is raised to a +temperature of 172° C. It burns with a yellowish flame, almost without +smoke, and leaves little or no residue. The volume of the gases formed is +large, and consists of carbonic acid, carbonic oxide, nitrogen, and water +gas. Compressed gun-cotton when ignited often explodes when previously +heated to 100° C. + +Gun-cotton kept at 80° to 100° C. decomposes slowly, and sunlight causes +it to undergo a slow decomposition. It can, however, be preserved for +years without undergoing any alteration. It is very susceptible to +explosions by influence. For instance, a torpedo, even placed at a long +distance, may explode a line of torpedoes charged with gun-cotton. The +velocity of the propagation of the explosion in metallic tubes filled with +pulverised gun-cotton has been found to be from 5,000 to 6,000 mms. per +second in tin tubes, and 4,000 in leaden tubes (Sebert). + +Gun-cotton loosely exposed in the open air burns eight times as quickly as +powder (Piobert). A thin disc of gun-cotton may be fired into from a rifle +without explosion; but if the thickness of the disc be increased, an +explosion may occur. The effect of gun-cotton in mines is very nearly the +same as that of dynamite for equal weights. It requires, however, a +stronger detonator, and it gives rise to a larger quantity of carbonic +oxide gas. Gun-cotton should be neutral to litmus, and should stand the +Government heat test--temperature of 150° F. for fifteen minutes (see page +249). In the French Navy gun-cotton is submitted to a heat test of 65° C. +(= 149° F.) for eleven minutes. It should contain as small a percentage of +soluble nitro-cotton and of non-nitrated cotton as possible. + +The products of perfectly detonated gun-cotton may be expressed by the +following equation:-- + +2C_{12}H_{14}O_{4}(NO_{3})_{6} = 18CO + 6CO_{2} + 14H_{2}O + 12N. + +It does not therefore contain sufficient oxygen for the complete +combustion of its carbon. It is for this reason that when used for mining +purposes a nitrate is generally added to supply this defect (as, for +instance, in tonite). It tends also to prevent the evolution of the +poisonous gas, carbonic oxide. The success of the various gelatine +explosives is due to this fact, viz., that the nitro-glycerine has an +excess of oxygen, and the nitro-cotton too little, and thus the two +explosives help one another. + +In practice the gases resulting from the explosion of gun-cotton are-- +Carbonic oxide, 28.55; carbonic acid, 19.11; marsh gas (CH_{4}), 11.17; +nitric oxide, 8.83; nitrogen, 8.56; water vapour, 21.93 per cent. The late +Mr E.O. Brown, of Woolwich Arsenal, discovered that perfectly wet and +uninflammable compressed gun-cotton could be easily detonated by the +detonation of a priming charge of the dry material in contact with it. +This rendered the use of gun-cotton very much safer for use as a military +or mining explosive. + +As a mining explosive, however, gun-cotton is now chiefly used under the +form of tonite, which is a mixture of half gun-cotton and half barium +nitrate. This material is sometimes spoken of as "nitrated gun-cotton." +The weight of gun-cotton required to produce an equal effect either in +heavy ordnance or in small arms is to the weight of gunpowder in the +proportion of 1 to 3, i.e., an equal weight of gun-cotton would produce +three times the effect of gunpowder. Its rapidity of combustion, however, +requires to be modified for use in firearms. Hence the lower nitrates are +generally used, or such compounds as nitro-lignose, nitrated wood, &c., +are used. + +The initial pressure produced by the explosion of gun-cotton is very +large, equal to 18,135 atmospheres, and 8,740 kilogrammes per square +centimetre for 1 kilo., the heat liberated being 1,075 calories (water +liquid), or 997.7 cals. (water gaseous), but the quantity of heat +liberated changes with the equation of decomposition. According to +Berthelot,[A] the heat of formation of collodion-cotton is 696 cals. for +1,053 grms., or 661 cals. for 1 kilo. The heat liberated in the total +combustion of gun-cotton by free oxygen at constant pressure is 2,633 +cals. for 1,143 grms., or for 1 kilo. gun-cotton 2,302 cals. (water +liquid), or 2,177 cals. (water gaseous). The heat of decomposition of gun- +cotton in a closed vessel, found by experiment at a low density of charge +(0.023), amounts to 1,071 cals. for 1 kilo. of the substance, dry and free +from ash. To obtain the maximum effect of gun-cotton it must be used in a +compressed state, for the initial pressures are thereby increased. Wet +gun-cotton s much less sensitive to shock than dry. Paraffin also reduces +its liability to explode, so also does camphor. + +[Footnote A: "Explosives and their Power," trans. by Hake and M'Nab.] + +The substance known as celluloid, a variety of nitro-cellulose nearly +corresponding to the formula C_{24}H_{24}(NO_{3}H)_{8}O_{12}, to which +camphor and various inert substances are added, so as to render it +non-sensitive to shock, may be worked with tools, and turned in the lathe +in the same manner as ivory, instead of which material celluloid is now +largely used for such articles as knife handles, combs, &c. Celluloid is +very plastic when heated towards 150° C., and tends to become very +sensitive to shock, and in large quantities might become explosive during +a fire, owing to the general heating of the mass, and the consequent +evaporation of the camphor. When kept in the air bath at 135° C., +celluloid decomposes quickly. In an experiment (made by M. Berthelot) in a +closed vessel at 135° C., and the density of the charge being 0.4, it +ended in exploding, developing a pressure of 3,000 kilos. A large package +of celluloid combs also exploded in the guard's van on one of the German +railways a few years ago. Although it is not an explosive under ordinary +circumstances, or even with a powerful detonator, considerable care should +be exercised in its manufacture. + +~The Manufacture of Gun-Cotton.~--The method used for the manufacture of +gun-cotton is that of Abel (Spec. No. 1102, 20. 4. 65). It was worked out +chiefly at Stowmarket[A] and Waltham Abbey,[B] but has in the course of +time undergone several alterations. These modifications have taken place, +however, chiefly upon the Continent, and relate more to the apparatus and +machinery used than to any alteration in the process itself. The form of +cellulose used is cotton-waste,[C] which consists of the clippings and +waste material from cotton mills. After it has been cleaned and purified +from grease, oil, and other fatty substances by treatment with alkaline +solutions, it is carefully picked over, and every piece of coloured cotton +rag or string carefully removed. The next operation to which it is +submitted has for its object the opening up of the material. For this +purpose it is put through a carding machine, and afterwards through a +cutting machine, whereby it is reduced to a state suitable for its +subsequent treatment with acids, that is, it has been cut into short +lengths, and the fibres opened up and separated from one another. + +[Footnote A: The New Explosive Co. Works.] + +[Footnote B: Royal Gunpowder Factory.] + +[Footnote C: Costs from £10 to £25 a ton. In his description of the +"Preparation of Cotton-waste for the Manufacture of Smokeless Powder," A. +Hertzog states that the German military authorities require a cotton which +when thrown into water sinks in two minutes; when nitrated, does not +disintegrate; when treated with ether, yields only 0.9 per cent. of fat; +and containing only traces of chlorine, lime, magnesia, iron, sulphuric +acid, and phosphoric acid. If the cotton is very greasy, it must be first +boiled with soda-lye under pressure, washed, bleached with chlorine, +washed, treated with sulphuric acid or HCl, again washed, centrifugated, +and dried; if very greasy indeed a preliminary treatment with lime-water +is desirable. See also "Inspection of Cotton-Waste for Use in the +Manufacture of Gun-cotton," by C.E. Munro, _Jour. Am. Chem. Soc._, 1895, +17, 783.] + +~Drying the Cotton.~--This operation is performed in either of two ways. +The cotton may either be placed upon shelves in a drying house, through +which a current of hot air circulates, or dried in steam-jacketed +cylinders. It is very essential that the cotton should be as dry as +possible before dipping in the acids, especially if a wholly "insoluble" +nitro-cellulose is to be obtained. After drying it should not contain more +than 0.5 per cent. of moisture, and less than this if possible. The more +general method of drying the cotton is in steam-jacketed tubes, i.e., +double cylinders of iron, some 5 feet long and 1-1/2 foot wide. The cotton +is placed in the central chamber (Fig. 10), while steam is made to +circulate in the surrounding jacket, and keeps the whole cylinder at a +high temperature (steam pipes may be coiled round the outside of an iron +tube, and will answer equally well). By means of a pipe which communicates +with a compressed air reservoir, a current of air enters at the bottom, +and finds its way up through the cotton, and helps to remove the moisture +that it contains. The raw cotton generally contains about 10 per cent. of +moisture and should be dried until it contains only 1/2 per cent. or less. +For this it will generally have to remain in the drying cylinder for about +five hours. At the end of that time a sample should be taken from the +_top_ of the cylinder, and dried in the water oven (100° C.[A]) for an +hour to an hour and a half, and re-weighed, and the moisture then +remaining in it calculated. + +[Footnote A: It is dried at 180° C. at Waltham Abbey, in a specially +constructed drying chamber.] + +[Illustration: FIG. 10.--COTTON DRIER.] + +It is very convenient to have a large copper water oven, containing a lot +of small separate compartments, large enough to hold about a handful of +the cotton, and each compartment numbered, and corresponding to one of the +drying cylinders. The whole apparatus should be fixed against the wall of +the laboratory, and may be heated by bringing a small steam pipe from the +boiler-house. It is useful to have a series of copper trays, about 3 +inches by 6 inches, numbered to correspond to the divisions in the steam +oven, and exactly fitting them. These trays can then be taken by a boy to +the drying cylinders, and a handful of the cotton from each placed in +them, and afterwards brought to the laboratory and weighed (a boy can do +this very well), placed in their respective divisions of the oven, and +left for one to one and a half hours, and re-weighed. + +When the cotton is found to be dry the bottom of the drying cylinder is +removed, and the cotton pushed out from the top by means of a piece of +flat wood fixed on a broom-handle. It is then packed away in galvanised- +iron air-tight cases, and is ready for the next operation. At some works +the cotton is dried upon shelves in a drying house through which hot air +circulates, the shelves being of canvas or of brass wire netting. The hot +air must pass under the shelves and through the cotton, or the process +will be a very slow one. + +~Dipping and Steeping.~--The dry cotton has now to be nitrated. This is +done by dipping it into a mixture of nitric and sulphuric acids. The acids +used must be strong, that is, the nitric acid must be at least of a +gravity of 1.53 to 1.52, and should contain as little nitric oxide as +possible. The sulphuric acid must have a specific gravity of 1.84 at 15° +C., and contain about 97 per cent. of the mono-hydrate (H_{2}SO_{4}). In +fact, the strongest acids obtainable should be used when the product +required is gun-cotton, i.e., the highest nitrate. + +The sulphuric acid takes no part in the chemical reaction involved, but is +necessary in order to combine with the water that is liberated in the +reaction, and thus to maintain the strength of the nitric acid. The +reaction which takes place is the following:-- + +2(C_{6}H_{10}O_{5}) + 6HNO_{3} = C_{12}H_{14}(NO_{3})_{6} + 6 H_{2}O. + 324 378 = 594 108. + Cellulose. Gun-Cotton. + +Theoretically,[A] therefore, 1 part of cellulose should form 1.8 part of +gun-cotton. Practically, however, this is never obtained, and 1.6 lb. from +1 lb. of cellulose is very good working. The mixture of acids used is +generally 1 to 3, or 25 per cent. nitric acid to 75 per cent. sulphuric +acid. + +[Footnote A: (594 x 1)/324= 1.83.] + +[Illustration: FIG. 11.--TANK FOR DIPPING COTTON.] + +[Illustration: FIG. 12.--THE COOLING PITS.] + +The dipping is done in cast-iron tanks (Fig. 11), a series of which is +arranged in a row, and cooled by a stream of cold water flowing round +them. The tanks hold about 12 gallons, and the cotton is dipped in +portions of 1 lb. at a time. It is thrown into the acids, and the workman +moves it about for about three minutes with an iron rabble. At the end of +that time he lifts it up on to an iron grating, just above the acids, +fixed at the back of the tank, where by means of a movable lever he gently +squeezes it, until it contains about ten times its weight of acids (the 1 +lb. weighs 10 lbs.). It is then transferred to earthenware pots to steep. + +[Illustration: FIG. 13.--COTTON STEEPING POT.] + +~Steeping.~--The nitrated cotton, when withdrawn from the dipping tanks, +and still containing an excess of acids, is put into earthenware pots of +the shape shown in Figs. 12 and 13. The lid is put on, and the pots placed +in rows in large cooling pits, about a foot deep, through which a stream +of water is constantly flowing. These pits form the floor of the steeping +house. The cotton remains in these pots for a period of forty-eight hours, +and must be kept cool. Between 18° and 19° C. is the highest temperature +desirable, but the cooler the pots are kept the better. At the end of +forty-eight hours the chemical reaction is complete, and the cotton is or +should be wholly converted into nitro-cellulose; that is, there should be +no unnitrated cotton. + +[Illustration: FIG. 14.--HYDRO-EXTRACTOR.] + +~Whirling Out the Acid.~--The next operation is to remove the excess of +acid. This is done by placing the contents of two or three or more pots +into a centrifugal hydro-extractor (Fig. 14), making 1,000 to 1,500 +revolutions per minute. The hydro-extractor consists of a machine with +both an inner cylinder and an outer one, both revolving in concert and +driving outwardly the liquid to the chamber, from which it runs away by a +discharge pipe. The wet cotton is placed around the inner cone. The +cotton, when dry, is removed, and at once thrown into a large tank of +water, and the waste acids are collected in a tank.[A] + +[Footnote A: Care must be taken in hot weather that the gun-cotton does +not fire, as it does sometimes, directly the workman goes to remove it +after the machine is stopped. It occurs more often in damp weather. Dr +Schüpphaus, of Brooklyn, U.S.A., proposes to treat the waste acids from +the nitration of cellulose by adding to them sulphuric anhydride and +nitric acid. The sulphuric anhydride added converts the water liberated +from the cellulose into sulphuric acid.] + +~Washing.~--The cotton has now to be carefully washed. This is done in a +large wooden tank filled with water. If, however, a river or canal runs +through the works, a series of wooden tanks, the sides and bottoms of +which are pierced with holes, so as to allow of the free circulation of +water, should be sunk into a wooden platform that overhangs the surface of +the river in such a way that the tanks are immersed in the water, and of +course always full. During the time that the cotton is in the water a +workman turns it over constantly with a wooden paddle. A stream of water, +in the form of a cascade, should be allowed to fall into these tanks. The +cotton may then be thrown on to this stream of water, which, falling some +height, at once carries the cotton beneath the surface of the water. This +proceeding is necessary because the cotton still retains a large excess of +strong acids, and when mixed with water gives rise to considerable heat, +especially if mixed slowly with water. After the cotton has been well +washed, it is again wrung out in a centrifugal machine, and afterwards +allowed to steep in water for some time. + +[Illustration: FIG. 15_a_.--THE BEATER FOR GUN-COTTON.] + +~Boiling.~--The washed cotton is put into large iron boilers with plenty +of water, and boiled for some time at 100° C. In some works lead-lined +tanks are used, into which a steam pipe is led. The soluble impurities of +unstable character, to which Sir F.A. Abel traced the liability of gun- +cotton to instability, are thereby removed. These impurities consist of +the products formed by the action of nitric acid on the fatty and resinous +substances contained in the cotton fibres. The water in the tanks should +be every now and again renewed, and after the first few boilings the water +should be tested with litmus paper until they are no longer found to be +acid. + +[Illustration: FIG. 15_b_.--WHEEL OF BEATER.] + +~Pulping.~--The idea of pulping is also due to Abel. By its means a very +much more uniform material is obtained. The process is carried out in an +apparatus known as a "Beater" or "Hollander" (Fig. 15, _a, b_). It +consists of a kind of wooden tank some 2 or 3 feet deep of an oblong +shape, in which a wheel carrying a series of knives is made to revolve, +the floor of the tank being sloped up so as to almost touch the revolving +wheels. This part of the floor, known as the "craw," is a solid piece of +oak, and a box of knives is fixed into it, against which the knives in the +revolving wheel are pressed. The beater is divided into two parts--the +working side, in which the cotton is cut and torn between the knife edges +in the revolving cylinder and those in the box; and the running side, into +which the cotton passes after passing under the cylinder. The wheel is +generally boxed in to prevent the cotton from being thrown out during its +revolution. The cotton is thus in constant motion, continually travelling +round, and passing between the knives in the revolving cylinder and those +in the box fixed in the wooden block beneath it. The beater is kept full +of water, and the cotton is gradually reduced to a condition of pulp. The +wheel revolves at the rate of 100 to 150 times a minute. + +[Illustration: FIG. 16_a_.--POACHER FOR WASHING GUN-COTTON.] + +[Illustration: FIG. 16_b_.--PLAN OF THE POACHER.] + +[Illustration: FIG. 16_c_.--ANOTHER FORM OF POACHER.] + +When the gun-cotton is judged to be sufficiently fine, the contents of the +beater are run into another very similar piece of machinery, known as the +"poacher" (Fig. 16, _a, b, c_), in which the gun-cotton is continuously +agitated together with a large quantity of water, which can be easily run +off and replaced as often as required. When the material is first run into +the poacher from the beater, the water with which it is then mixed is +first run away and clean water added. The paddle wheel is then set in +motion, and at intervals fresh water is added. There is a strainer at the +bottom of the poacher which enables the water to be drawn off without +disturbing the cotton pulp. After the gun-cotton has been in the poacher +for some time, a sample should be taken by holding a rather large mesh +sieve in the current for a minute or so. The pulp will thus partly pass +through and partly be caught upon the sieve, and an average sample will be +thus obtained. The sample is squeezed out by hand, bottled, and taken to +the laboratory to be tested by the heat test for purity. It first, +however, requires to be dried. This is best done by placing the sample +between coarse filter paper, and then putting it under a hand-screw press, +where it can be subjected to a tolerably severe pressure for about three +minutes. It is then rubbed up very finely with the hands, and placed upon +a paper tray, about 6 inches by 4-1/2 inches, which is then placed inside +a water oven upon a shelf of coarse wire gauze, the temperature of the +oven being kept as near as possible to 120° F. (49° C.), the gauze shelves +in the oven being kept about 3 inches apart. The sample is allowed to +remain at rest for fifteen minutes in the oven, the door of which is left +wide open. After the lapse of fifteen minutes the tray is removed and +exposed to the air of the laboratory (away from acid fumes) for two hours, +the sample being at some point within that time rubbed upon the tray with +the hand, in order to reduce it to a fine and uniform state of division. +Twenty grains (1.296 grm.) are used for the test. (See Heat Test, page +249.) + +If the gun-cotton sample removed from the poacher stands the heat test +satisfactorily, the machine is stopped, and the water drained off. The +cotton is allowed some little time to drain, and is then dug out by means +of wooden spades, and is then ready for pressing. The poachers hold about +2,000 lbs. of material, and as this represents the products of many +hundred distinct nitrating operations, a very uniform mixture is obtained. +Two per cent. of carbonate of soda is sometimes added, but it is not +really necessary if the cotton has been properly washed. + +~Compressing Gun-Cotton.~--The gun-cotton, in the state in which it is +removed from the poacher, contains from 28 to 30 per cent. of water. In +order to remove this, the cotton has to be compressed by hydraulic power. +The dry compressed gun-cotton is packed in boxes containing 2,500 lbs. of +dry material. In order to ascertain how much of the wet cotton must be put +into the press, it is necessary to determine the percentage of water. This +may be done by drying 2,000 grains upon a paper tray (previously dried at +100° C.) in the water oven at 100° C. for three hours, and re-weighing and +calculating the percentage of water. It is then easy to calculate how much +of the wet gun-cotton must be placed in the hopper of the press in order +to obtain a block of compressed cotton of the required weight. Various +forms of presses are used, and gun-cotton is sent out either as solid +blocks, compressed discs, or in the form of an almost dry powder, in zinc- +lined, air-tight cases. The discs are often soaked in water after +compression until they have absorbed 25 per cent. of moisture. + +[Illustration: FIG. 17.--OLD METHOD. 100 PIECES.] + +[Illustration: FIG. 18.--NEW METHOD. ONE SOLID BLOCK.] + +At the New Explosives Company's Stowmarket Works large solid blocks of +gun-cotton are pressed up under a new process, whereby blocks of gun- +cotton, for use in submarine mines or in torpedo warheads, are produced. +Large charges of compressed gun-cotton have hitherto been built up from a +number of suitably shaped charges of small dimensions (Fig. 17), as it has +been impossible to compress large charges in a proper manner. The +formation of large-sized blocks of gun-cotton was the invention of Mr A. +Hollings. Prior to the introduction of this method, 8 or 9 lbs. had been +the limit of weight for a block. This process has been perfected at the +Stowmarket factory, where blocks varying from the armour-piercing shell +charge of a few ounces up to blocks of compressed gun-cotton mechanically +true, weighing 4 to 5 cwts. for torpedoes or submarine mines, are now +produced. At the same time the new process ensures a uniform density +throughout the block, and permits of any required density, from 1.4 +downwards, being attained; it is also possible exactly to regulate the +percentage of moisture, and to ensure its uniform distribution. The +maximum percentage of moisture depends, of course, upon the density. By +the methods of compression gun-cotton blocks hitherto employed, blocks of +a greater thickness than 2 inches, or of a greater weight than 9 lbs., +could not be made, but with the new process blocks of any shape, size, +thickness, or weight that is likely to be required can be made readily and +safely. The advantages which are claimed for the process may be enumerated +as follows:--(1.) There is no space wasted, as in the case with built-up +charges, through slightly imperfect contact between the individual blocks, +and thus either a heavier charge--i.e., about 15 per cent. more gun- +cotton--can be got into the same space, or less space will be occupied by +a charge of a given weight. (2.) The metallic cases for solid charges may +be much lighter than for those built-up, since with the former their +function is merely to prevent the loss of moisture from wet gun-cotton, or +to prevent the absorption of moisture by dry gun-cotton. They can thus be +made lighter, as the solid charge inside will prevent deformation during +transport. With built-up charges the case must be strong enough to prevent +damage, either to itself or to the charge it contains. For many uses a +metal case, however light, may be discarded, and one of a thin waterproof +material substituted. (3.) The uniform density of charges made by this +process is very favourable to the complete and effective detonation of the +entire mass, and to the presence of the uniform amount of moisture in +every part of the charge. (4.) Any required density, from the maximum +downwards, may be obtained with ease, and any required amount of moisture +left in the charge. These points are of great importance in cases where, +like torpedo charges, it is essential to have the centre of gravity of the +charge in a predetermined position both vertically and longitudinally, and +the charge so fixed in its containing case that the centre of gravity +cannot shift. The difficulty of ensuring this with a large torpedo charge +built up from a number of discs and segments is well known. Even with +plain cylindrical or prismatic charges a marked saving in the process of +production is effected by this new system. The charges being in one block +they are more easily handled for the usual periodical examination, and +they do not break or chafe at the edges, as in the case of discs and cubes +in built-up charges. A general view of the press is given in Fig. 19. The +gun-cotton in a container is placed on a cradle fixed at an angle to the +press. The mould is swivelled round, and the charge pushed into it with a +rammer, and it is then swivelled back into position. The mould is made up +of a number of wedge pieces which close circumferentially on the enclosed +mass, which is also subjected to end pressure. Holes are provided for the +escape of water. + +[Illustration: FIG. 19.--A 4-CWT. BLOCK OF GUN-COTTON BEING TAKEN FROM +HYDRAULIC PRESS.] + +~The Waltham Abbey Process.~--At the Royal Gunpowder Factory, Waltham +Abbey, the manufacture of gun-cotton has been carried out for many years. +The process used differs but little from that used at Stowmarket. The +cotton used is of a good quality, it is sorted and picked over to remove +foreign matters, &c., and is then cut up by a kind of guillotine into +2-inch lengths. It is then dried in the following manner. The cotton is +placed upon an endless band, which conducts it to the stove, or drying +closet, a chamber heated by means of hot air and steam traps to about +180° F.; it falls upon a second endless band, placed below the first; it +travels back again the whole length of the stove, and so on until +delivered into a receptacle at the bottom of the farther end, where it is +kept dry until required for use. The speed at which the cotton travels is +6 feet per minute, and as the length of the band travelled amounts to 126 +feet, the operation of drying takes twenty-one minutes. One and a quarter +lb. are weighed out and placed in a tin box; a truck, fitted to receive a +number of these boxes, carries it along a tramway to a cool room, where it +is allowed to cool. + +~Dipping.~--Mixed acids are used in the proportion of 1 to 3, specific +gravity nitric acid 1.52, and sulphuric acid 1.84. The dipping tank is +made of cast iron, and holds 220 lbs. of mixed acids, and is surrounded on +three sides by a water space in order to keep it cool. The mixed acids are +stored in iron tanks behind the dipping tanks, and are allowed to cool +before use. During the nitration, the temperature of the mixed acids is +kept at 70° F., and the cotton is dipped in quantities of 1-1/2 lb. at a +time. It is put into a tin shoot at the back of the dipping tank, and +raked into the acids by means of a rabble. It remains in the acids for +five or six minutes, and is then removed to a grating at the back, pressed +and removed. After each charge of cotton is removed from the tank, about +14 lbs. of fresh mixed acids are added, to replace amount removed by +charge. The charge now weighs, with the acids retained by it, 15 lbs.; it +is now placed in the pots, and left to steep for at least twenty-four +hours, the temperature being kept as low as possible, to prevent the +formation of soluble cotton, and also prevent firing. The proportion of +soluble formed is likely to be higher in hot weather than cold. The pots +must be covered to prevent the absorption of moisture from the air, or the +accidental entrance of water, which would cause decomposition, and +consequent fuming off, through the heat generated by the action of the +water upon the strong acids. + +The excess of acids is now extracted by means of hydro-extractors, as at +Stowmarket. They are worked at 1,200 revolutions per minute, and whirled +for five minutes (10-1/2 lbs. of waste acids are removed from each charge +dipped). The charge is then washed in a very similar manner to that +previously described, and again wrung out in a centrifugal extractor +(1,200 revolutions per minute). The gun-cotton is now boiled by means of +steam in wooden tanks for eight hours; it is then again wrung out in the +extractors for three minutes, boiled for eight hours more, and again wrung +out; it is then sent to the beater and afterwards to the poacher. The +poachers hold 1,500 gals. each, or 18 cwt. of cotton. The cotton remains +six hours in the poachers. Before moulding, 500 gals. of water are run +into the poacher, and 500 gals. of lime water containing 9 lbs. of whiting +and 9 gals. of a caustic soda solution. This mixture is of such a strength +that it is calculated to leave in the finished gun-cotton from 1 to 2 per +cent. of alkaline matter. + +By means of vacuum pressure, the pulp is now drawn off and up into the +stuff chest--a large cylindrical iron tank, sufficiently elevated on iron +standards to allow room for the small gauge tanks and moulding apparatus +below. It holds the contents of one poacher (18 cwt.), and is provided +with revolving arms to keep the pulp stirred up, so that it may be +uniformly suspended in water. + +Recently a new process, invented by J.M. and W.T. Thomson (Eng. Pat. No. +8,278, 1903), has been introduced at the Waltham Abbey Factory. The object +of this invention is the removal of the acids of nitration from the +nitrated material after the action has been completed, and without the aid +of moving machinery, such as presses, rollers, centrifugals, and the like. +The invention consists in the manufacture of nitrated celluloses by +removing the acids from the nitrated cellulose directly by displacement +without the employment of either pressure or vacuum or mechanical +appliances of any kind, and at the same time securing the minimum dilution +of the acids. It was found that if water was carefully run on to the +surface of the acids in which the nitro-cellulose is immersed, and the +acids be slowly drawn off at the bottom of the vessel, the water displaces +the acid from the interstices of the nitro-cellulose without any +undesirable rise in temperature, and with very little dilution of the +acids. By this process almost the whole of the acid is recovered in a +condition suitable for concentration, and the amount of water required for +preliminary washing is very greatly reduced. The apparatus which is used +for the purpose consists of a cylindrical or rectangular vessel +constructed with a perforated false bottom and a cock at its lowest point +for running off the liquid. Means are also provided to enable the +displacing water to be run quietly on to the surface of the nitrating +acids.[A] + +[Footnote A: In a further patent (Eng. Pat. 7,269, 1903, F.L. Natham), +J.M. Thomson and W.T. Thomson propose by use of alcohol to replace the +water, used in washing nitro-cellulose, and afterward to remove the +alcohol by pressing and centrifuging.] + +The apparatus is shown in Fig. 2O, side elevation, and in Fig. 21 a plan +of the nitrating vessel and its accessories is given. In Fig. 20 is shown +in sectional elevation one of the trough devices for enabling liquids to +be added to those in the nitrating vessel without substantial disturbance. + +[Illustration: FIG. 20.--SECTIONAL ELEVATION OF THOMSON'S APPARATUS, _a_, +Tank; _b_, False Bottom; _c_, Bottom; _c'_, Ribs; _d_, Draining Outlet; +_e_, Grid; _f_, Troughs, with Aprons _g_; _h_, Pipe, with Branches _h'_, +leading to Troughs, _f_; _k'_, Outlet Pipe of the Sulphuric Acid Tank _k_; +_l_, Water Supply Pipe; _m_, Pipe to supply of Nitrating Acids; _o_, +Perforations of Trough _f_; _p_, Cock to remove Acid.] + +In carrying out this invention a rectangular lead-lined or earthenware +tank _a_ is employed, having a false bottom _b_, supported by ribs _c'_, +over the real bottom _c_, which slopes down to a draining outlet pipe _d_, +provided with a perforated grid or plate _e_, adapted to prevent choking +of the outlet. Suitably supported near the top of the vessel _a_ are +provided two troughs, _f_ having depending aprons _g_, a pipe _h_ has two +branches _h'_, leading to the troughs, _f_. This pipe _h_ is adapted to be +connected by a rubber pipe either to the outlet pipe _k'_ of the sulphuric +acid tank _k_ or the water supply pipe _l_. The nitrating acids are +supplied through the pipe _m_. A charge of mixed nitrating acids is +introduced into the vessel _a_ say up to the level _n_, and the dry +cellulose thrown into the acids in small quantities at a time, being +pushed under the surface in the usual way. + +[Illustration: FIG. 21.--PLAN OF THOMSON'S APPARATUS, _a_, Tank; _b_, +False Bottom; _c'_, Ribs; _e_, Grid; _f_, Troughs; _g_, Aprons; _h_ and +_h'_, Pipes to Troughs _f_; _k_, Sulphuric Acid Tank; _m_, Pipe to +Nitrating Acids Tank; _o_, Perforations of Troughs; _p_, Cock to remove +Acid.] + +A thin layer, say half an inch, of a suitable liquid, preferably sulphuric +acid, of a gravity not exceeding that of the waste acid to be produced, is +run carefully on the top of the acids by means of the troughs _f_, which +are perforated as shown at _o_, so that the sulphuric acid runs down the +aprons _g_, and floats on the nitrating acids. The whole is then allowed +to stand till nitration has been completed. Water is then supplied to the +troughs by way of the pipes _l_, _h_, and _h'_, and is allowed to float +very gently over the surface of the sulphuric acid, and when a sufficient +layer has been formed, the cock _p_ at the bottom of the apparatus is +opened, and the acid slowly drawn off, water being supplied to maintain +the level constant. It is found that the rate of displacement of the acids +is a factor which exerts a considerable influence on the properties of the +resulting nitro-cellulose, and affords a means of regulating the +temperature of displacement. A rate of displacement which has been found +suitable is about two inches in depth of the vessel per hour when treating +highly nitrated celluloses, but this rate may, in some cases, be +considerably increased. The flow of water at the top of the apparatus is +regulated so that a constant level is maintained. By this means the water +gradually and entirely displaces the acids from the interstices of the +nitro-cellulose, the line of separation between the acids and the water +being fairly sharply defined throughout. The flow of water is continued +until that issuing at the bottom is found to be free from all trace of +acid. The purification of the nitro-cellulose is then proceeded with as +usual, either in the same vessel or another. + +In the process above described, the object of the introduction of a small +layer of sulphuric acid is mainly to prevent the fuming which would +otherwise take place, and is not essential, as it is found it can be +omitted without any deleterious effect. In order to use the mixed acids in +the most economical manner, the waste acid from a previous operation may +be used for a first nitration of the cellulose; being afterwards displaced +with fresh acids which carry the nitration to the required degree before +they are in turn displaced by water. The apparatus may be used merely for +the removal of the acid, in which case the nitration is carried out in +other vessels in the usual way, and the nitro-cellulose removed to the +displacement apparatus where it is just covered with waste acid, and the +displacement then proceeded with as above described. In some cases the +process is carried out in an ordinary nitrating centrifugal, using the +latter to effect preliminary drying after acid extraction. This gives a +great advantage over the usual method of working ordinary centrifugal +nitrating apparatus, because the acid being removed before the centrifugal +is run, practically all danger of firing therein disappears, and a greater +proportion of the waste acid is recovered. + +In some cases the acids and water may be supplied by perforated pipes, +lying along the edges of the nitrating vessel, and these edges may, if +desired, be themselves made inclined, like the sides of the troughs _f_. +In the case of effecting nitration in centrifugals as above, the +displacing sulphuric acid and water may thus be supplied round the edges +of the machines, or removal troughs such as _f_ may be used. It will be +obvious that any inert liquid of suitable specific gravity may be used +instead of sulphuric acid, as a separation layer. + +~Moulding.~--By means of the small measuring tank above referred to, the +gun-cotton pulp is drawn off from the stuff chest, and run into moulds of +the shapes and sizes required. Thence a large proportion of the water is +drawn off by means of tubes connected with the vacuum engine, the moulds +having bottoms of fine wire gauze, in order to prevent the pulp from +passing through. Hydraulic pressure of about 34 lbs. on the square inch is +then applied, which has the effect of compressing the pulp into a state in +which it has sufficient consistency to enable it to be handled with care, +and also expels a portion of the remaining water. + +~Compressing.~--The moulded gun-cotton is now taken to the press house, +which is situated at some distance from the rest of the factory. Here the +moulds are subjected to powerful hydraulic pressure, from 5 to 6 tons per +square inch, and is compressed to one-third of its previous bulk. The +slabs or discs thus formed are kept under pressure for a short time, not +exceeding a minute and a half, to give the requisite density. It should, +when removed, be compact, and just sink in water, and should perceptibly +yield to the pressure of the fingers. There are perforations in the press +blocks, to allow of the escape of gases, if formed, by reason of +sufficient heat being generated. The men working the press are placed +under cover, behind strong rope mantlets having eye tubes which command a +view of the press. + +~Packing.~--The finished slabs and discs are dipped into a solution of +soda and carbolic acid, and packed in special wood metal-lined cases. When +it is to be sent abroad, the metal lining, which is made of tinned copper, +is soldered down, but both the outer wooden and inner metal cases are +fitted with air-tight screw-plugs, so that when necessary water can be +added without unfastening the cases. + +~Reworked gun-cotton~ does not make such good discs as new pulped gun- +cotton, probably because the fibrous tenacity of the gun-cotton has been +destroyed by the amount of pressure it has previously undergone, so that +when repulped it resembles fine dust, and a long time is required to press +it into any prescribed form. It is generally boiled for eight hours to +open up the fibre and remove alkali, then broken up by hand with wooden +mallets, pulped, and then used with fresh gun-cotton in the proportion of +1 to 5 parts. + +~Manufacture at Le Bouchet.~--At Le Bouchet gun-cotton was made thus:--200 +grms. of cotton were steeped for an hour in 2 litres of a mixture of 1 +volume concentrated nitric and 2 volumes sulphuric acid. The cotton was +then removed and pressed, whereby 7/10ths of the waste acids was +recovered. After this it was washed for one to one and a half hours in +running water, strongly pressed again; allowed to lie for twenty-four +hours in wood-ash lye; then well washed in running water; pressed, and +finally dried on a wide linen sheet, through which was forced air heated +to 60° C. The average yield from 100 parts of cotton was 165 parts of gun- +cotton. The strong pressings of the gun-cotton, while still impregnated +with acids, caused subsequent washings to be difficult and laborious. + +~Granulation of Gun-Cotton.~--Gun-cotton is often required in the +granulated form for use either alone or with some form of smokeless +powder. This is done under the patent of Sir Frederick Abel in the +following manner:--The gun-cotton from the poacher is placed in a +centrifugal machine, very similar to the hydro-extractors before +mentioned, and used for wringing out the acids. In this machine it loses +water until it only contains 33 per cent., and is at the same time reduced +to a more or less fibrous state. It is then taken to the granulating room, +where it is first passed through sieves or perforations, which break up +the mass into little pieces like shot. The material is then transferred to +a revolving drum made of wood or stout leather, which is kept constantly +revolving for some time. The material is occasionally sprinkled with +water. The drum in turning, of course, carries the granules partially +round with it, but the action of gravity causes them to descend constantly +to the lowest point, and thus to roll over one another continually. The +speed of the drum must not be too rapid. None of the granules must be +carried round by centrifugal force, but it must be fast enough to carry +them some little distance up the side of the drum. After removal from the +drum the granules are dried upon shelves in the drying house. + +Gun-cotton is also dissolved in acetone or acetic ether until it has taken +the form of a jelly. It is then rolled into thin sheets, and when dry cut +up into little squares. In the manufacture of smokeless powders from +nitro-cellulose, nitro-lignine, &c., the various substances are mixed with +the gun-cotton or collodion-cotton before granulating. + +~Collodion-Cotton.~--In the manufacture of collodion or soluble cotton the +finer qualities of cotton-waste are used and the acids used in the dipping +tanks are much weaker. The manufacture of collodion-cotton has become of +more importance than gun-cotton, by reason of its use for the manufacture +of the various forms of gelatine, such as gelatine dynamite, gelignite, +forcite, &c., and also on account of its extensive use in the manufacture +of many of the smokeless powders. It is also used for the manufacture of +"collodion," which is a solution of collodion-cotton in ether-alcohol; for +the preparation of celluloid, and many other purposes. It is less +explosive than gun-cotton, and consists of the lower nitrates of +cellulose. It is soluble in nitro-glycerine, and in a mixture of 2 parts +of ether and 1 of alcohol; also in acetone, acetic ether, and other +solvents. MM. Ménard and Domonte were the first to prepare a soluble gun- +cotton, and its investigation was carried on by Béchamp, who showed that +its properties and composition were different to those of gun-cotton. + +~Manufacture.~--The cotton used is cotton-waste.[A] It is thought by some +that Egyptian cotton is preferable, and especially long fibre varieties. +The strength of the acids used is, however, of more importance than the +quality of the cotton. The percentage composition of the acid mixture +which gives the best results is as follows:--Nitric acid, 23 per cent.; +sulphuric acid, 66 per cent.; and water, 11 per cent; and has a specific +gravity of 1.712 (about). It can be made by mixing sulphuric acid of +specific gravity 1.84 with nitric acid of specific gravity 1.368 in the +proportions of 66 per cent. and 34 per cent. respectively. (The production +of the penta-nitro-cellulose is aimed at if the collodion-cotton is for +use as an explosive.) If the acids are much weaker than this, or potassium +nitrate and sulphuric acid is used, the lower nitrates will be formed. The +product, while being entirely soluble in ether-alcohol or nitro-glycerine, +will have a low nitrogen content, whereas a material with as high a +nitrogen as 12 or 12.6 is to be aimed at. + +[Footnote A: Raw cotton is often used.] + +The cotton should not be allowed to remain in the dipping tanks for more +than five minutes, and the acid mixture should be kept at a temperature of +28° C. or thereabouts; and the cotton should be removed after a few +minutes, and should not be pressed out, as in the case of gun-cotton, but +at once transferred to the pots and allowed to steep for forty-eight +hours. (Some prefer twenty-four hours, but there is more chance in this +case of the product containing non-nitrated cellulose.) When the nitration +is complete, the collodion-cotton is removed from the pots, and treated in +exactly the same manner as described under gun-cotton. The produce should +be entirely soluble in ether-alcohol and nitro-glycerine, and contain as +near 12.7 per cent. of nitrogen as possible. The theoretical nitrogen is +for the penta-nitro-cellulose 12.75 per cent. This will, however, seldom +if ever be obtained. The following are some of the results I have obtained +from different samples:-- + + Nitrogen. + (1.) (2.) (3.) +German make 11.64 11.48 11.49 per cent. +Stowmarket 12.57 12.60 11.22 " +Walsrode 11.61 12.07 11.99 " +Faversham 12.14 11.70 11.60 " + +and the following was the analysis of a sample (No. 1) of German-made +collodion-cotton, which made very good blasting gelatine:-- + + _ +Soluble cotton (collodion) 99.118 per cent.| Nitrogen = 11.64 per cent. +Gun-cotton 0.642 " _| +Non-nitrated cotton 0.240 " +Total ash 0.25 " + +It should contain as little non-nitrated or unconverted cotton and as +little gun-cotton as possible, as they are both insoluble in nitro- +glycerol. The quality and composition of any sample of collodion-cotton +can be quickly inferred by determining the percentage of nitrogen by means +of the nitrometer and the use of the solubility test.[A] A high nitrogen +content coupled with a high solubility is the end to be aimed at; a high +nitrogen with a low solubility shows the presence of gun-cotton, and a low +nitrogen, together with a low solubility, the presence of unnitrated +cotton. Where complete solubility is essential and the percentage of +nitrogen less important, Dr Lunge recommends nitration with a mixture of +equal parts of sulphuric and nitric acids containing from 19 to 20 per +cent. of water. + +[Footnote A: See Analysis of Explosives.] + +Mr T.R. France claims to have invented some improvements in the +manufacture of soluble nitro-cellulose. His object has been to produce an +article as uniform as possible. His explanation of the imperfect action of +the acids is that, however uniform the mixed acids may be in strength and +proportions, and however carefully the operations of nitrating, &c., may +be conducted, there are variable elements found in different samples of +cotton. The cotton fibre has for its protection a glazed surface. It is +tubular and cellular in structure, and contains a natural semi-fluid +substance composed of oil or gum, which varies in nature according to the +nature of the soil upon which the cotton is grown. The tubes of the fibre +seem to be open at one end only when the fibre is of normal length. When, +therefore, the cotton is subjected to the action of the mixed acids, the +line of least resistance seems to be taken by them, viz., the insides of +the tubes constituting the fibre of the cotton, into which they are taken +by capillary attraction, and are subject to change as they progress, and +to the increased resistance from the oil or gum, &c., in their progress, +and therefore to modified action, the result of which is slower and slower +action, or chemical change. He also thinks it is possible that the power +of capillary attraction is balanced in the tubes by air contained therein, +after a little, sufficiently so to prevent the acids from taking full +effect. To get over this, Mr France uses his cotton in a fine state, +almost dust, in fact, and then nitrates in the usual mixture of acids at +40° to 90° F., the excess of acids being removed by pressure. He says he +does not find it necessary to wash this fine cotton dust in an alkaline +solution previous to nitration. His mixed acids consist of 8 parts HNO_{3} += 42° B., and 12 parts H_{2}SO_{4} = 66° B., and he stirs in the dipping +tank for fifteen minutes, the temperature being 50° F. to 100° F., the +temperature preferred being 75° F. + +~"Nitrated" Gun-Cotton.~--The nitrates that are or have been mixed with +gun-cotton in order to supply oxygen are potassium nitrate, ammonium +nitrate, and barium nitrate (tonite). The total combustion of gun-cotton +by potassium nitrate corresponds to the equation:-- + +10[C_{24}H_{18}(NO_{3}H)_{11}O_{9}] + 82KNO_{3} = 199CO_{2} + +41K_{2}CO_{3} + 145H_{2}O + 96N_{2}, + +or 828 grms. of nitrate for 1,143 grms. of gun-cotton, or 42 per cent. +nitrate and 58 per cent. gun-cotton. The explosive made at Faversham by +the Cotton Powder Company, and known as tonite No. 1, consists of very +nearly half gun-cotton and half barium nitrate. The relations by weight of +total combustion would be 51.6 of gun-cotton to 48.4 of barium nitrate. +The average composition of tonite I have found by analysis to be 51 per +cent. gun-cotton to 49 per cent. barium nitrate. The heat liberated is +practically the same as for an equivalent weight of KNO_{3}; but the +barium nitrate mixture weighs 2,223 grms. instead of 1,971 grms., or +one-eighth more. The advantage in mixing a nitrate with gun-cotton is that +it supplies oxygen, and by converting all the carbon into carbonic acid, +prevents the formation of the poisonous gas carbonic oxide (CO). The +nitrates of potassium and barium are also used admixed with nitro- +cellulose in several of the sporting smokeless powders. + +~The Manufacture of Tonite.~--The explosive tonite was patented by Messrs +Trench, Faure, and Mackie, and is manufactured at Faversham and Melling at +the works of the Cotton Powder Company, and at San Francisco by the Tonite +Powder Company. It consists of finely divided and macerated gun-cotton +incorporated with finely ground nitrate of barium which has been carefully +recrystallised. It is made by acting upon carbonate of barium[A] with +nitric acid. The wet and perfectly purified, finely pulped gun-cotton is +intimately mixed up between edge runners with about the same weight of +nitrate, and the mixing and grinding continued until the whole has become +an intimately mixed paste. This paste is then compressed into cartridges, +formed with a recess at one end for the purpose of inserting the +detonator. The whole is then covered with paraffined paper. + +[Footnote A: Witherite, BaCO_{3} + 2HNO_{3} = Ba(NO_{3})_{2} + CO_{2} + +H_{2}O.] + +The tonite No. 2 consisted of gun-cotton, nitrates of potash and soda, +charcoal and sulphur. Tonite No. 3[A] is composed as follows:--Gun-cotton, +19 per cent.; di-nitro-benzol, 13 per cent.; and barium nitrate, 68 per +cent. or similar proportions. It is a yellowish colour, and being slower +in its explosive action, is better adapted for blasting soft rock. + +[Footnote A: Tonite No. 1 was patented by Messrs Trench, Faure, and +Mackie, and tonite Nos. 2 and 3 by Trench alone.] + +Tonite is extensively used in torpedoes and for submarine blasting, also +for quarries, &c. Large quantities were used in the construction of the +Manchester Ship Canal. Among its advantages are, that the English railways +will take tonite on the same footing as gunpowder; it is a very dense +material; if wetted it can easily be dried in the sun; it very readily +explodes by the use of a proper detonator; while it burns very slowly and +without the least danger; the cartridges being waterproofed, it can be +employed in wet bore holes, and it can be tamped with water; and finally, +as it contains sufficient oxygen to oxidise the carbon, no carbonic oxide +(CO) gas is formed, i.e., its detonation is perfect. It is a very safe +explosive to use, being little susceptible to either blows or friction. + +Not long ago, a committee, composed of Prof. P. Bedson, Drs Drummond and +Hume, Mr T. Bell, one of H.M. Inspectors of Coal Mines, and others, in +considering the problem whether the fumes produced by the combustion of +tonite were injurious to health, carried out a series of experiments in +coal mines for this purpose. The air at the "intake" was analysed, also +the air of the "return," and the smoky air in the vicinity of the shot +holes. The cartridge was surrounded by the flame-extinguishing mixture, +and packed in a brown paper bag. During the first experiment nineteen +shots were fired (= 6.29 lbs. tonite). The "return" air showed only a +trace of carbonic oxide gas (CO). At the second experiment thirteen shots +were fired (= 4.40 lbs. tonite), and analysis of the air of the "return" +showed that CO was present in traces only, whilst the fumes contained only +1.9 to 4.8 parts per 10,000. + +~Dangers in connection with the Manufacture of Guncotton, &c.~--Of all the +nitro compounds, the least dangerous to manufacture are gun-cotton and +collodion-cotton. The fact that the Stowmarket Factory is within five +minutes' walk of the town shows how safe the manufacture of this explosive +is regarded. With the exception of the nitration and the compression into +blocks or discs, the whole process is worked with a large excess of water, +and the probability of an explosion is thus reduced to a minimum. Among +the precautions that should, however, be taken, are--first, the careful +extraction of the resinous and soluble substances from the cotton before +nitration, as it was shown many years ago by Sir F.A. Abel that the +instability of the gun-cotton first manufactured in England and Austria +was chiefly due to these compounds. They are generally removed by boiling +the cotton in a soda solution. + +The actual nitration of cotton is not a dangerous operation, but the +operations of wringing in the hydro-extractors, and washing the nitro- +cotton after it leaves the first centrifugal machine, are somewhat so. +Great care should be taken that the wrung-out nitro-cotton at once comes +in contact with a large excess of water, i.e., is at once immersed +entirely in the water, since at this stage it is especially liable to +decomposition, which, once started, is very difficult to stop. The warmer +the mixture and the less water it contains, the more liable it is to +decomposition; hence it is that on warm and damp days the centrifugal +machines are most likely to fire. The commencement of decomposition may be +at once detected by the evolution of red fumes. Directly the gun-cotton is +immersed in the large quantity of water in the beater and poacher it is +safe. + +In order that the final product may be stable and have good keeping +qualities, it is necessary that it should be washed completely free from +acid. The treatment in the beater and poacher, by causing the material to +assume the state of a fine pulp, in contact with a large quantity of +water, does a good deal to get rid of the free acid, but the boiling +process is absolutely necessary. It has been proposed to neutralise the +free acid with a dilute solution of ammonia; and Dr C.O. Weber has +published some experiments bearing upon this treatment. He found that +after treatment with ammonia, pyroxyline assumed a slightly yellowish +tinge, which was a sure sign of alkalinity. It was then removed from the +water, and roughly dried between folds of filter paper, and afterwards +dried in an oven at 70° C. After three hours, however, an explosion took +place, which entirely destroyed the strong copper oven in which the nitro- +cotton (about one oz.) had been drying. The explosion was in some respects +remarkable. The pyroxyline was the di-nitro-cellulose (or possibly the +penta-nitro?), and the temperature was below the igniting point of this +material (40° C. would have been a better temperature). Dr Weber +determined the ignition point of his di-nitro-cellulose, and found it to +be 194° to 198° C., and he is therefore of opinion that the explosion was +due to the treatment of the partially washed material with ammonia. A +certain quantity of ammonium nitrate was probably formed, and subsequently +dried upon the nitro-cellulose, in a state of very fine subdivision. The +faintest trace of acid would then be sufficient to bring about the +explosive ignition of the ammonium nitrate. + +The drying of gun-cotton or collodion-cotton is also a somewhat dangerous +operation. A temperature of 40° C. (104° F.) should not be exceeded, and +thermometers should be placed in the nitro-cotton, and the temperature +frequently observed. An electric alarm thermometer is also a useful +adjunct to the cotton drying house. Great care must also be taken that +there are no exposed hot-water pipes or stoves in the drying house, as the +fine gun-cotton dust produced by the turning or moving of the material +upon the shelves would settle upon such pipes or stoves, and becoming hot, +would be very sensitive to the least friction. The floor also should be +covered with linoleum or indiarubber. When hot currents of air are made to +pass over the surface of gun-cotton, the gun-cotton becomes electrified. +It is important, therefore, to provide some means to carry it away. Mr +W.F. Reid, F.I.C., was the first to use metal frames, carriers, and +sieves, upon which is secured the cloth holding the gun-cotton, and to +earth them. + +The compression of gun-cotton into blocks, discs, &c., is also attended +with considerable risk. Mr O. Guttmann, in an interesting paper upon "The +Dangers in the Manufacture of Explosives" (_Jour. Soc. Chem. Ind._, No. 3, +vol. xi., 1892), says: "The compression of gun-cotton into cartridges +requires far more care than that of gunpowder, as this is done in a warm +state, and gun-cotton even when cold, is more sensitive than gunpowder. +When coming out of the centrifugal machines, the gun-cotton should always +pass first through a sieve, in order to detect nails or matches which may +by chance have got into it. What has been said as to gunpowder presses +applies still more to those for gun-cotton, although the latter are always +hydraulic presses. Generally the pistons fit the mould perfectly, that is +to say, they make aspiration like the piston of a pump. But there is no +metal as yet known which for any length of time will stand the constant +friction of compression, and after some time the mould will be wider in +that part where the greatest compression takes place. The best metal for +this purpose has proved to be a special steel made by Krupp, but this also +is only relatively better; for pistons I prefer hard cast iron. If the +position of the moulds and pistons is not exactly the same in all cases, +what the Germans call 'Ecken' (English 'binding') will take place, viz., +the mould will stand obliquely to the piston, and a dangerous friction +will result." "Of course, it is necessary to protect the man working the +hydraulic valves during compression. At Waltham Abbey they have a curtain +made of ship's hawsers, which is at the same time elastic and resistant." +Mr Guttmann has found that a partition wall 12 inches thick, made of +2-inch planks, and filled with ground cinders, gives very effective +protection. A door in this partition enables the workman to get to the +press, and a conical tube penetrates the wall, enabling the man to see the +whole work from a safe standpoint. The roof, or one side of the building, +should be of glass, so as to give the explosion a direction. + +~Trench's Fire-extinguishing Compound~ is manufactured by the Cotton +Powder Company at Faversham, and is the invention of Mr George Trench, +F.C.S., the manager of the Company. The object of the invention is to +surround the cartridges of tonite, when used in coal mines, with a fire- +extinguishing compound. If a charge of tonite, dynamite, or gelatine +dynamite is put inside a few ounces of this mixture, and then fired, not +the least trace of flame can be observed, and experiments appear to show +that there is no flame at all. The compound consists of sawdust +impregnated with a mixture of alum and chlorides of sodium and ammonia. +Fig. 22 shows the manner of placing the tonite cartridge in the paper bag, +and surrounding it with the fire-extinguishing compound, _aa_. The +attachment of the fuse and detonator is also shown. + +[Illustration: FIG. 22.--TRENCH'S FIRE-EXTINGUISHING CARTRIDGE.] + +The following report (taken from the _Faversham News_, 22nd Oct. 1887) of +experiments conducted in the presence of several scientific and mining men +will show its value:--"A large wrought-iron tank, of 45 cubic feet +capacity, had been sunk level with the ground in the middle of the yard; +to this tank the gas had been laid on, for a purpose that will be +explained later on. The charges were fired by means of electricity, a +small dynamo firing machine being placed from 30 to 40 yards away from the +'mine.'" Operations were commenced by the top of the tank being covered +over and plastered down in order to make it air-tight; then a sufficient +quantity of coal gas was placed in it to make it highly inflammable and +explosive, the quantity being ascertained by a meter which had been fixed +specially for the purpose. Whilst the gas was being injected the cartridge +was prepared. + +The first experiment was to try whether a small charge of tonite--fired +without the patent extinguisher--would ignite the gas. The gas having been +turned on, a miner's lamp was placed in the "tank," but this was +extinguished before the full quantity of gas had gone through the meter. +However, the gas being in, the charge of 1-1/4 oz. tonite was placed in +the "mine," the detonator was connected by means of long wires to the +dynamo machine, and the word was given to "fire." With a tremendous +report, and a flash of fire, the covering of the mine flew in all +directions, clearly showing that the gas had exploded. The next cartridge +(a similar charge) was prepared with the patent compound. First of all a +brown paper case of about 2 inches diameter was taken, and one of the +tonite cartridges was placed in the centre of it, the intervening space +between the charge and-the case being packed with the "fire-extinguishing +compound." The mine having had another supply of gas injected, the +protected cartridge was placed inside and fired. The result was +astonishing, the explosion not being nearly so loud, whilst there was not +the least flash of fire. "Protected" and "unprotected" charges were fired +at intervals, gas being turned into the tank on each occasion. Charges of +tonite varying from 1 to 6 oz. were also used with the compound. The +report was trifling, whilst no flash could be seen. + +~Uses of Collodion-Cotton.~--The collodion or soluble gun-cotton is used +for a variety of purposes. The chief use is, however, for the manufacture +of the various explosive gelatine compounds, of which blasting gelatine is +the type. It is also very extensively used in the manufacture of smokeless +powders, both military and sporting--in fact, very few of them do not +contain it. In some, however, nitro-lignose or nitrated wood is used +instead. This, however, is chemically the same thing, viz., nitro- +cellulose, the cellulose being derived from the wood fibre. It is more +used in this connection than the higher nitrate gun-cotton. Another use to +which it has been applied very extensively, of recent years, is in the +manufacture of "celluloid." It is used in photography for the preparation +of the films on the sensitised plates, and many other purposes. Dissolved +in a solution of two parts ether and one of alcohol, it forms the solution +known as collodion, used for a variety of purposes, such as a varnish, as +a paint for signals; in surgery, for uniting the edges of wounds. + +Quite lately, Mr Alfred Nobel, the well-known inventor of dynamite, has +patented the use of nitro-cellulose, hydro- or oxy-cellulose, as an +artificial substitute for indiarubber. For this purpose it is dissolved in +a suitable non-volatile or slightly volatile "solvent," such as nitro- +naphthalene, di-nitro-benzene, nitro-toluene, or its homologues; products +are obtained varying from a gelatinous consistency to the hardness of +ebonite. The proportions will vary from about 20 per cent. of nitro- +cellulose in the finished product, forming a soft rubber, to 50 per cent. +nitrating celluloid, and the "solvent" chosen will depend on the use to +which the rubber substitute is to be put, the liquids giving a more +elastic substance, whilst mixtures of solids and liquids may be employed +when the product is to be used at high temperatures. By means of rollers +steam heated, the incorporation may be accomplished without the aid of a +volatile liquid, or the nitro-cellulose may be employed wet, the water +being removed after "solution." + +It is advisable to use the cellulose nitrated only just enough to render +it suitable, in order to reduce the inflammability of the finished +product. Mr W. Allen, M.P., of Gateshead, proposed to use celluloid for +cartridge cases, and thus to lighten ammunition, and prevent jambing, for +the case will be resolved into gases along with the powder. Extractors +will also be done away with. + +~Celluloid~ is an intimate mechanical mixture of pyroxyline (gun-cotton or +collodion-cotton) with camphor, first made by Hyatt, of Newark, U.S.A., +and obtained by adding the pyroxyline to melted camphor, or by strongly +compressing the two substances together, or by dissolving the constituents +in an appropriate solvent, e.g., alcohol or ether, and evaporating to +dryness. A combination of the two latter methods, i.e., partial solution, +with pressure, is now usually adapted. The pyroxyline employed is +generally the tetra- and penta-nitrated cellulose, the hexa-nitrate +(gun-cotton) being but seldom used on account of its explosive properties. + +Care is taken to prevent the formation of the hexa-nitrate by immersing +the cellulose in only moderately strong nitric acid, or in a warm mixture +of nitric and sulphuric acids. The paper, either in small pieces or in +sheets, is immersed for about twenty-five minutes in a mixture of 2 parts +of nitric acid and 5 parts of sulphuric acid, at a temperature of about +30° C., after which the nitrated cellulose is thoroughly washed with water +to remove the last traces of free acid, pressed, and whilst still moist, +mixed with the camphor. + +In the process of Trebouillet and De Besancele, the cellulose, which may +be in the form of paper, cotton, or linen, is twice nitrated--first in the +acid mixture employed in a previous operation; and secondly, in a fresh +mixture of 3 parts sulphuric acid of 1.83 specific gravity, and 2 parts +concentrated nitric acid containing nitrous acid. After each nitration the +mass is subjected to pressure, and is then carefully washed with water, to +which, at the last, a small quantity of ammonia or caustic soda is added +to remove the final traces of acid. The impregnation of the pyroxyline +with the camphor is effected in a variety of ways. + +The usual proportion of the constituents is 2 parts pyroxyline and 1 part +camphor. In Trebouillet and De Besancele's process, 100 parts of +pyroxyline are intimately mixed with from 40 to 50 parts camphor, and +moulded together by strong pressure in a hot press, and afterwards dried +by exposure to air, desiccated by calcium chloride or sulphuric acid. The +usual method is, however, to dissolve the camphor in the least possible +quantity of alcohol, and sprinkle the solution over the dry pyroxyline, +which is then covered with a second layer of pyroxyline, and the whole +again treated with the camphor solution, the addition of pyroxyline and +camphor solution being repeated alternately until the requisite amount of +celluloid mixture is obtained. + +The mass, which sinks together in transparent lumps, is worked for about +an hour between cold iron rollers, and then for the same period between +rollers which can be gently heated by steam. The layer of celluloid +surrounding the rollers is then cut away and again pressed, the resulting +cake, which is now about 1 cm. thick, being cut into plates of about 70 +cm. long and 30 cm. broad. These are placed one above the other, and +strongly pressed together by hydraulic pressure at a temperature of about +70° for twenty-four hours. The thick cakes are once more cut into plates +of the desired thickness, and placed in a chamber heated from 30° to 40° +for eight to fourteen days, whereby they become thoroughly dry, and are +readily made into various articles either by being moulded while warm +under pressure, cut, or turned. Occasionally other liquids, e.g., ether +and wood spirit, are used in place of alcohol as solvents for the camphor. + +Celluloid readily colours, and can be marbled for manufacturing purposes, +&c. It is highly inflammable and not explosive even under pressure, and +may be worked under the hammer or between rollers without risk. It softens +in boiling water, and may be moulded or pressed. Its specific gravity +varies slightly with its composition and with the degree of pressure it +has received. It is usually 1.35. It appears to be merely a mixture of its +components, since by treatment with appropriate solvents the camphor may +be readily extracted, and on heating the pyroxyline burns away while the +camphor volatilises. + +The manufacture of pyroxyline for the purpose of making celluloid has very +much increased during recent years, and with this increase of production +improved methods of manufacture have been invented. A series of +interesting papers upon the manufacture of pyroxyline has been published +by Mr Walter D. Field, of New York, in the _Journal of the American +Chemical Society_[A] from which the following particulars are taken:-- + +[Footnote A: Vol. xv., No. 3, 1893; Vol. xvi., No. 7, 1894; Vol. xvi., No. +8, 1894. Figs. 19, 20, 21, 22, and 23 are taken from Mr Field's paper.] + +~Selection of the Fibre.~--Cotton fibre, wood fibre, and flax fibre in the +form of raw cotton, scoured cotton, paper, and rags are most generally +used, and give the best results. As the fibres differ greatly in their +structure, they require different methods of nitrating. The cotton fibre +is a flattened hollow ribbon or collapsed cylindrical tube, twisted a +number of times, and closed at one end to form a point. The central canal +is large, and runs nearly to the apex of the fibre. Its side walls are +membraneous, and are readily penetrated by the mixed acids, and +consequently the highest nitration results. In the flax fibre the walls +are comparatively thick, the central canal small; hence it is to be +presumed that the nitration must proceed more slowly than in the case of +cotton. The New Zealand flax gives the most perfectly soluble nitrates of +any of the flaxes. Cotton gives a glutinous collodion, and calico a fluid +collodion. One of the largest manufacturers of pyroxyline in the States +uses the "Memphis Star" brand of cotton. This is an upland cotton, and its +fibres are very soft, moist, and elastic. Its colour is light creamy +white, and is retained after nitration. The staple is short, and the twist +inferior to other grades, the straight ribbon-like filaments being quite +numerous. This cotton is used carded, but not scoured. This brand of +cotton contains a large quantity of half and three-quarter ripe fibre, +which is extremely thin and transparent, distributed throughout the bulk +of the cotton (Monie., Cotton Fibre, 67). Mr Field says, "This is a +significant fact when it is known that from this cotton an extremely +soluble pyroxyline can be produced." + +Pyroxyline of an inferior grade as regards colour only can be produced +from the cotton wastes of the trade. They must be scoured before they are +fit for nitrating. Paper made from the pulps of sulphite and sulphate +processes is capable of yielding a very soluble pyroxyline. It can be +nitrated at high temperatures and still yield good results. Tissue paper +made from flax fibre is also used after being cut into squares. + +Mowbray (U.S.P., No. 443, 105, 3rd December 1890) says that a pure cotton +tissue paper less than 1/500 inch in thickness, thin as it is, takes on a +glutinous or colloid surface, and thus requires some thirty minutes to +enable the nitration to take place. With a thicker paper only the surface +would be nitrated. He therefore uses a fibre that has been saturated with +a solution of nitrate of soda, and afterwards dried slowly, claiming that +the salt crystallises in the fibre, or enters by the action termed osmose, +and opens up the fibre to the action of the acid. This process would only +be useful when the cotton is to be nitrated at a low temperature. At a +high temperature it would be unnecessary. + +Dietz and Wayne (U.S.P., No. 133, 969) use ramie, rheca, or China grass +for producing a soluble pyroxyline. That made from ramie is always of +uniform strength and solubility, and requires a smaller quantity of +solvent to dissolve it than that made from cotton. Mr Field's experience, +however, is entirely contrary to this statement. Such is the influence of +the physical form of the fibre on the process of nitration, that when flax +fibre and cotton fibre are nitrated with acid mixtures of exactly the same +strength, and at the same temperature, the solution of the first is +glutinous or thick, and the second fluid or thin. By simply nitrating at a +higher temperature than the cotton, the flax will yield a pyroxyline +giving an equally fluid collodion. + +The presence of chlorine in the fibre must be carefully avoided, as such a +fibre will yield an acid product which cannot be washed neutral. The fibre +must be dry before nitration; and this is best done, according to Mr +Field, by using the form of drier used in drying wool. + +~Nitration of the Fibre.~--Mixed cotton and flax fibre in the form of +paper, from 2/1000 to 3/1000 inch thick, and cut into 1-inch squares, is +nitrated by the Celluloid Manufacturing Company, and the same paper, left +in long strips, 1 inch wide, is used for nitration by the Xylonite +Manufacturing Company, of North Adams, Mass. (U.S.A.). + +The Celluloid Company introduce the cut paper into the mixed acids by +means of a hollow, rapidly revolving tube, flared at the lower end, and +immersed in the mixed acids. The centrifugal force of the revolving tube +throws the paper towards the sides of the vessel, leaving the centre of +the vessel ready for fresh paper. + +The Xylonite Company simply cut the paper into long strips, and introduce +it into the mixed acids by means of forks. The arrangement used by this +Company for holding the mixed acids is a cylindrical vessel divided into a +number of sections, the whole revolving like a turntable, thus allowing +the workman to nitrate successively each lot of paper at a given point. +This Company did not remove the acid from the paper after its immersion, +but plunged it immediately into the water, thus losing a large proportion +of the waste acid. The Celluloid Company, by using the paper in smaller +pieces, and more paper to a pound of acid, and wringing the mixed acid +from the paper before immersion in water, had a better process of +nitration. + +Other manufacturers use earthenware vessels, and glass or steel rods, +hooked at one end, having small pieces of rubber hose pulled over the +other end to prevent the hand from slipping. The form of vessel in general +use is that given in Fig. 23. It is large enough to nitrate 1 lb. of +cotton at a time. The hook at one end of the rod enables the workman to +pull the pyroxyline apart, and thus ensures saturation of the fibre. In +the winter the room in which the nitrating is done must be kept at a +temperature of about 70° F. in order to secure equality in the batches. + +[Illustration: FIG. 23.--VESSEL FOR NITRATING COTTON OR PAPER.] + +The nitrating apparatus of White and Schupphaus (U.S.P., No. 418, 237, 89) +Mr Field considers to be both novel and excellent. The cage (Fig. 24), +with its central perforated cylinder (Fig. 25), is intended to ensure the +rapid and perfect saturation of the tissue paper used for nitrating. The +patentees say that no stirring is required with their apparatus. This, +says Mr Field, might be true when paper is used, or even cotton, when the +temperature of nitration is from 30° to 35° C., but would not be true if +the temperature were raised to 50° to 55° C. The process is as follows:-- +The paper is nitrated in the cage (Fig. 25), the bottom of which is formed +by the flanged plate C, fastened to the bottom of the internal cylinder B. +After nitration the cage is carried to a wringer, which forms the basket, +and the acids removed. Finally, the cage is taken to a plunge tank, where +the paper is removed from the cage by simply pulling out the central +perforated cylinder B. Fig. 26 shows the nitrating pot, with its automatic +cover. The plunge tank is shown in plan and section in Figs. 28 and 29. +This apparatus is suitable for the nitration of cotton fibre in bulk at +high or low temperatures. Other methods that have been patented are +Mowbray's (U.S.P., No. 434, 287), in which it is proposed to nitrate paper +in continuous lengths, and Hyatt's (U.S.P., No. 210, 611). + +[Illustration: FIG. 24.--CENTRAL PERFORATED CYLINDER.] + +[Illustration: FIG. 25.--THE CAGE. WHITE AND SCHUPPHAUS' NITRATING +APPARATUS.] + +[Illustration: FIG. 26.--CELLULOID NITRATING POT.] + +[Illustration: FIG. 27.--ANOTHER VIEW.] + +[Illustration: FIGS. 28, 29.--PLUNGE TANK, IN PLAN AND SECTION.] + +~The Acid Mixture.~--Various formulæ have been published for producing +soluble nitro-cellulose. In many instances, although the observations were +correct for the single experiment, a dozen experiments would have produced +a dozen different products. The composition of the acids used depends upon +the substance to be nitrated, and the temperature at which the nitration +will be worked. Practically there are three formulæ in general use--the +one used by the celluloid manufacturers; another in which the cotton is +nitrated at high temperatures; and a third in which the temperature of the +immersion is low, and the time of nitration about six hours. Of the three, +the best method is the last one, or the one in which the cotton is +immersed at a low temperature, and then the reaction allowed to proceed in +pots holding from 5 to 10 lbs. of cotton. The formula used by the +celluloid manufacturers for the production of the low form of nitrated +product which they use is:-- + +Sulphuric acid 66 parts by weight. +Nitric acid 17 " " +Water 17 " " + +Temperature of immersion, 30° C. Time, twenty to thirty minutes. + +The cellulose is used in the form of tissue paper 2/1000 inch thick, 1 lb. +to 100 of acid mixture. The nitro-cellulose produced by this formula is +very insoluble in the compound ethers and other solvents of pyroxyline, +and is seemingly only converted or gelatinised by the action of the +solvent. The next formula produces a mixture of tetra-and penta-nitro- +celluloses hardly soluble in methyl-alcohol (free from acetone), but very +soluble in anhydrous compound ethers, ketones, and aldehydes:-- + +Nitric acid, sp. gr. 1.435 8 lbs. +Sulphuric acid, sp. gr. 1.83 15-3/4 lbs. +Cotton 14 oz. + +Temperature of nitration, 60° C. Time of immersion, forty-five minutes. + +The 60° of temperature is developed by mixing the acids together. The +cotton is allowed to remain in the acid until it feels "short" to the rod. + +The following table, due to Mr W.D. Field, shows very plainly the great +variation in the time of the immersion and the temperature by seemingly +very slight causes. It extends over fourteen working days, during which +time it rained four days. The formula used is that given above, except +that the specific gravity of the nitric acid is somewhat lower. The +product obtained differs only from that produced by using nitric acid of +specific gravity 1.43 in being soluble in methyl-alcohol. From 30 to 35 +lbs. of pyroxyline were produced in each of the fourteen days. + +A careful examination of this table will prove very instructive. The +increase in yield varies from 31 per cent. to nothing, and the loss runs +as high as 10 per cent., yet care was taken to make the product uniform in +quality. On the days it rained there was a loss, with the exception of the +fourth day, when there was neither a loss nor a gain. On the days it was +partly clear, as just before or after rain, the table shows a loss in +product. We can explain this fact by reason of the moisture-absorbing +qualities of the cotton. On the rainy days it would absorb the moisture +from the air until, when immersed in the acids, they were weakened, and +the fibre dissolved more or less in weakened acid, producing what is known +as "burning" in the batch. It will also be noticed that on days which show +a loss, the time of the immersion was correspondingly short, as on the +a loss, the time of the immersion was correspondingly short, as on the +tenth, twelfth, and seventh days. + + ______________________________________________________________________ +| | | | +| | Specific Gravity. | Time. | +| |_____________________|_______________________________| +| | | | | | | | +| |H_{2}S0_{4}.|HNO_{3}.|Hours.|Minutes.|Hours.|Minutes.| +|________________|____________|________|______|________|______|________| +| | | | | | | | +| 1. Clear | 1.838 | 1.4249 | ... | 20 | 4 | ... | +| 2. " | 1.837 | 1.4249 | ... | 20 | 2 | ... | +| 3. Cloudy | 1.837 | 1.4226 | ... | 45 | 2 | ... | +| 4. Rain | 1.837 | 1.420 | ... | 20 | 1 | 20 | +| 5. Clear | 1.8377 | 1.42 | 1 | 15 | 2 | ... | +| 6. Rainy | 1.8391 | 1.422 | ... | 35 | 1 | 40 | +| 7. Cloudy | 1.835 | 1.4226 | ... | 20 | ... | 35 | +| 8. Clear | 1.835 | 1.422 | ... | 35 | 1 | 10 | +| 9. Partly Clear| 1.824 | 1.4271 | ... | 20 | 1 | ... | +|10. " | 1.83 | 1.4271 | ... | 10 | ... | 25 | +|11. Cloudy | 1.832 | 1.425 | ... | 10 | ... | 50 | +|12. Rainy | 1.822 | 1.425 | ... | 10 | ... | 20 | +|13. Partly CLear| 1.8378 | 1.4257 | ... | 60 | 1 | 40 | +|14. Cloudy | 1.837 | 1.4257 | 1 | 56 | 4 | 40 | +|________________|____________|________|______|________|______|________| +| | | | +| |Temp., Deg. C. | Percentage | +| |_______________|___________________| +| | | | | | +| | From | To | Increase. | Loss. | +|________________|_______|_______|___________|_______| +| | | | | | +| 1. Clear | 57° | 62° | 31 | ... | +| 2. " | 60° | 62° | 18 | ... | +| 3. Cloudy | 60° | 62° | 7 | ... | +| 4. Rain | 60° | 63° | 0 | 0 | +| 5. Clear | 58° | 62° | 15 | ... | +| 6. Rainy | 58° | 62° | ... | 2 | +| 7. Cloudy | 62° | 65° | ... | 10 | +| 8. Clear | 60° | 62° | 5 | ... | +| 9. Partly Clear| 50° | 60° | ... | 3 | +|10. " | 58° | 60° | ... | 10 | +|11. Cloudy | 58° | 60° | 8 | ... | +|12. Rainy | 58° | 60° | ... | 10 | +|13. Partly CLear| 50° | 58° | 20 | ... | +|14. Cloudy | 50° | 60° | 16 | ... | +|________________|_______|_______|___________|_______| + +The lesson this table teaches is, that it is almost impossible to nitrate +cellulose in small quantities, and get uniform results, when the nitration +is carried on at high temperatures. As regards the solubility of +pyroxyline, Parks found that nitro-benzene, aniline, glacial acetic acid, +and camphor, dissolved in the more volatile solvents methyl-alcohol and +alcohol-ether, were much the best solvents for producing a plastic, as +they are less volatile, and develop greater solvent action under the +influence of heat. Nitro-benzene gives a solution that is granular; it +seems to merely convert the pyroxyline, and not to dissolve it; but on the +addition of alcohol, a solution is at once obtained, and the granular +appearance disappears, and the solution becomes homogeneous. The acid +mixture and the method of nitrating have much to do with the action of the +various solvents, so also has the presence of water. + +Dr Schupphaus found that propyl and isobutyl alcohols with camphor were +active solvents, and the ketones, palmitone, and stearone in alcohol +solution, also alpha- and beta-naphthol, with alcohol and anthraquinone +(diphenylene diketone) in alcoholic solution, and also iso-valeric +aldehyde and its derivatives, amyliden-dimethyl and amyliden-diethyl +ethers. + +August Sayer (U.S.P., No. 470,451) finds diethyl-ketone, dibutyl-ketone, +di-pentyl-ketone, and the mixed ketones,[A] methyl-ethyl, methyl-propyl, +methyl-butyl, methyl-amyl, and ethyl-butyl ketones are active solvents of +pyroxyline; and Paget finds that although methyl-amyl oxide is a solvent, +that ethyl-amyl oxide is not. + +[Footnote A: Ketones are derived from the fatty acids by the substitution +of the hydroxyl of the latter by a monad positive radical. They thus +resemble aldehydes in constitution. The best-known ketone is acetone +CH_{3}CO.CH_{3}. Mixed ketones are obtained by distilling together salts +of two different fatty acids. Thus potassic butyrate and potassic acetate +form propyl-methyl-ketone-- + +C(C_{2}H_{5})H_{2} +| +CO.CH_{3}] + +The solvents of pyroxyline can be divided into general classes--First, +those which are solvents without the aid of heat or solution in alcohol; +second, those that are solvents when dissolved in alcohol. These solvents +are those which also develop a solvent action when heated to their melting +point in combination with pyroxyline. + +Mr W.D. Field groups the solvents of pyroxyline into classes thus: Two of +the monohydric alcohols; compound ethers of the fatty acids with +monohydric alcohols, aldehydes; simple and mixed ketones of the fatty acid +series. These four classes include the greater number of the solvents of +pyroxyline. Those not included are as follows:--Amyl-nitrate and nitrite, +methylene-di-methyl ether, ethidene-diethyl ether, amyl-chloracetate, +nitro-benzene and di-nitro-benzene, coumarin, camphor, glacial acetic +acid, and mono-, di-, and tri-acetin. + +Richard Hale uses the following solvent:--Amyl-acetate, 4 volumes; +petroleum naphtha, 4 volumes; methyl-alcohol, 2 volumes; pyroxyline, 4 to +5 ounces to the gallon of solvent. Hale used petroleum naphtha to hasten +the drying qualities of the varnish, so that it would set on the article +to be varnished before it had a chance to run off. It is, however, the +non-hygroscopic character of the solvent that makes the varnish +successful. This formula is very largely used for the production of +pyroxyline varnish, which is used for varnishing pens, pencils, &c., also +brass-work and silver-ware. + +The body known as oxy-cellulose[A] is formed by the action of nitric acid +upon cellulose when boiled with it. The quantity formed is about 30 per +cent. of cellulose acted upon. When washed free from acid, it gelatinises. +It is then soluble in dilute alkalies, and can be reprecipitated from +solution by alcohol, acids, or saline solutions. Messrs Cross and Bevan +assign to it the formula C_{18}H_{26}O_{16}. It dissolves in concentrated +sulphuric acid, and with nitric acid forms a nitro body of the formula +C_{18}H_{23}O_{16}3(NO_{2}), which is prepared as follows:--The gelatinous +oxy-cellulose is washed with strong nitric acid until free from water, and +is then diffused through a mixture of equal volumes of strong sulphuric +and nitric acids, in which it quickly dissolves. The solution, after +standing for about an hour, is poured in a fine stream into a large volume +of water, by which the "nitro" body is precipitated as a white flocculent +mass. The product, after drying at 110° C., was found upon analysis to +contain 6.48 per cent. nitrogen. + +[Footnote A: "On the Oxidation of Cellulose," by C.F. Cross and E.J. +Bevan, _Jour. Chem. Soc._, 1883, p. 22.] + +MISCELLANEOUS NITRO-EXPLOSIVES. + +~Nitro-Starch.~--It is only recently that, by means of the process +introduced by the "Actiengesellschaft Dynamit Nobel," it has been possible +to make this explosive upon the manufacturing scale. Nitro-starch has been +known since 1883, when Braconnot discovered it, and called it xyloidine. +Its formula is C_{6}H_{8}O_{3}(NO_{3})_{2}, but Dr Otto Mühlhäusen has +lately succeeded in preparing higher nitrated compounds, viz.:-- + +(_a._) C_{6}H_{7-1/2}O_{2-1/2}(NO_{3})_{2-1/2}. + +(_b._) C_{6}H_{7}O_{4}(NO_{3})_{3}. + +Or doubling the molecule of starch:-- + + Nitrogen. + i. Tetra-nitro-starch C_{12}H_{16}O_{6}(ONO_{2})_{4} 11.11 per cent. + ii. Penta-nitro-starch C_{12}H_{15}O_{5}(ONO_{2})_{5} 12.75 " +iii. Hexa-nitro-starch C_{12}H_{14}O_{4}(ONO_{2})_{6} 14.14 " + +He regards them as true ethers (esters) of nitric acid. Thus on treatment +with sulphuric acid, these compounds yield NO_{3}H, the residue O.NO_{2} +thus appearing to be replaced by the sulphuric acid residue. On treatment +with a solution of ferrous chloride, nitric oxide and "soluble" starch are +regenerated. On shaking with sulphuric acid over mercury, all the nitrogen +is split off as NO. + +Tetra-nitro-starch is prepared upon the large scale as follows:--A +quantity of potato-starch is taken and exposed in some suitable +desiccating apparatus at a temperature of 100° C. until all the moisture +which it contains is completely driven off. It is then reduced to a fine +powder by grinding, and dissolved in nitric acid of specific gravity +1.501. The vessel in which this solution is accomplished is made of lead, +and must be provided with two jackets, cooled by means of water. It should +further be fitted with a screw-agitator, in order to keep the nitric acid +circulating freely. The charge of starch is introduced through an opening +in the cover of this digesting vessel, and the proportions of acid to +starch are 10 kilogrammes of starch to 100 kilos. of acid. The temperature +is kept within the limits 20° to 25° C. When the solution of the starch is +complete, the liquid is conducted into a precipitating apparatus, which is +also provided with a cooling jacket, for the purpose of regulating the +temperature. The bottom of this vessel is double and perforated, and here +is placed a layer of gun-cotton to act as a filter. This vessel is filled +with spent nitro-sulphuric acid obtained as a waste product from the +nitro-glycerine manufactory, and the solution of starch in nitric acid is +sprayed into it through an injector worked by compressed air, whereby the +nitro-starch is thrown down in the form of a fine-grained powdery +precipitate. + +In order to precipitate 100 kilos. of the acid solution of starch, it is +necessary to employ 500 kilos. of spent nitro-sulphuric acid. As it is +precipitated the nitro-starch collects on the gun-cotton filter, and the +acid liquor is run off through a tap placed beneath the perforated double +bottom of the vessel, and of course below the filter pad. The precipitated +starch is further cleansed from acid by repeated washings and by pressure, +until all trace of acidity has been eliminated, and the substance exhibits +a neutral reaction. The next step is to treat the nitro-starch with a 5 +per cent. solution of soda, in contact with which it is allowed to stand +for at least twenty-four hours. The product is then ground up until a sort +of "milk" or emulsion is obtained, and lastly treated with a solution of +aniline, so that when pressed into cake, it contains about 33 per cent. of +water, and 1 per cent. of aniline. + +Dr Mühlhäusen, working on these lines in the laboratory, prepared nitro- +starch which contained 10.96 and 11.09 per cent. of nitrogen. When in the +state of powder it is snow-white in colour; it becomes electrified when +rubbed; it is very stable, and soluble even in the cold in nitro- +glycerine. He has also prepared a tetra-nitro-starch containing 10.58 and +10.50 per cent. of nitrogen, by pouring water into a solution of starch in +nitric acid which had stood for several days. The substance thus produced +in the laboratory had all the properties of that prepared by the other +process. + +The production of penta-nitro-starch is effected by adding 20 grms. of +rice-starch--previously dried at a temperature of 100°C., in order to +eliminate all moisture--to a mixture of 100 grms. of nitric acid, specific +gravity 1.501, and 300 grms. of sulphuric acid, specific gravity 1.8 (some +tetra-nitro-starch is also formed at the same time). After standing in +contact with these mixed acids for one hour the starch has undergone a +change, and the mass may now be discharged into a large quantity of water, +and then washed, first with water, and finally with an aqueous solution of +soda. The yield in Dr Mühlhäusen's experiments was 147.5 per cent. + +The substance thus formed is now heated with ether-alcohol, the ether is +distilled off, and the penta-nitro-starch appears as a precipitate, whilst +the tetra-nitro-starch, which is formed simultaneously, remains in +solution in the alcohol. As obtained by this process, it contained 12.76 +and 12.98 per cent. nitrogen, whilst the soluble tetra-nitro-starch +contained 10.45 per cent. + +Hexa-nitro-starch is the product chiefly formed when 40 grms. of dry +starch are treated with 400 grms. of nitric acid, specific gravity 1.501, +and allowed to stand in contact for twenty-four hours; 200 grms. of this +mixture are then poured into 600 c.c. of sulphuric acid of 66° B. The +result of this manipulation is a white precipitate, which contains +13.52-13.23 and 13.22 per cent. nitrogen; and consists, therefore, of a +mixture of penta- and hexa-nitro-starch. + +The experiments undertaken with these substances demonstrated that those +prepared by precipitating the nitro-starch with strong sulphuric acid were +less stable in character or properties than those which were precipitated +by water or weak sulphuric acid. Dr Mühlhäusen is of opinion that possibly +in the former case a sulpho-group may be formed, which in small quantity +may occasion this instability. + +The following table shows the behaviour of these substances prepared in +different ways and under various conditions:-- + + __________________________________________________________________ +| | | +| | SAMPLES. | +| |____________________________________________| +| | | | | | | +| | A. | B. | C. | D. | E. | +| Ignition-point |175° C. |170° C. |152° C. |121° C. |155° C. | +| Stability |Stable |Stable |Unstable|Unstable|Unstable| +| Per cent. of N. | 11.02 | 10.54 | 12.87 | 12.59 | 13.52 | +| 96 per cent. alcohol| Sol. | Sol. | Insol. | Insol. | Insol. | +| Ether | Insol. | Insol. | Insol. | Insol. | Insol. | +| Ether-alcohol | Sol. | Sol. | Sol. | Sol. | Sol. | +| Acetic Ether | Sol. | Sol. | Sol. | Sol. | Sol. | +|_____________________|________|________|________|________|________| + +These samples were prepared as follows:-- + +A. From 1 part nitric acid and 2 parts sulphuric acid (containing 70 per + cent. H_{2}O). +B. From 1 part nitric acid and water. +C. From 1 part nitric and 3 parts H_{2}SO_{4} (con.). +D. From 1 part nitric and 3.5 parts con. H_{2}SO_{4}. +E. From 1 part nitric and 3 parts con. H_{2}SO_{4}. + +Dr Mühlhäusen is of opinion that these compounds may be turned to +practical account in the production of good smokeless powder. He +recommends the following proportions and method. Six grms. of nitro-jute +and 2 grms. of nitro-starch are mixed together, and moistened with acetic +ether. These ingredients are then worked together into a uniform mass, and +dried at a temperature ranging between the limits 50° to 60° C. He has +himself prepared such a smokeless powder, which proved to contain 11.54 +per cent. of nitrogen, and was very stable. Further details of Dr +Mühlhäusen's work upon nitro-starch can be found in _Dingler's +Polytechnisches Journal_, paper "Die höhren Salpetersäureäther der +Stärke," 1892, Band 284, s. 137-143, and a Bibliography up to 1892 in +_Arms and Explosives_, December 1892. + +M. Berthelot gives the heat of formation of nitro-starch as 812 cals. for +1 grm., and the heat of total combustion as equal to 706.5 cals. for 207 +grms., or for 1 grm. 3,413 cals. The heat of decomposition could only be +calculated if the products of decomposition were given, but they have not +as yet been studied, and the quantity of oxygen contained in the compound +is far from being sufficient for its complete combustion. Berthelot and +Vieille found the average velocities for nitro-starch powder, density of +charge about 1.2, in a tin tube 4 mm. external diameter, to be, in two +experiments, 5,222 m. and 5,674 m. In a tin tube 5.5 mm. external +diameter, the velocity was 5,815 m., and in lead tube 5,006 m. (density +1.1 to 1.2). The starch powder is hygroscopic, and is insoluble in water +and alcohol. When dry it is very explosive, and takes fire at about 350° +F. Mr Alfred Nobel has taken out a patent (Eng. Pat. No. 6,560, 88) for +the use of nitro-starch. His invention relates to the treatment of nitro- +starch and nitro-dextrine, for the purpose of producing an explosive +powder, to be used in place of gunpowder. He incorporates these materials +with nitro-cellulose, and dissolves the whole in acetone, which is +afterwards distilled off. A perfect incorporation of the ingredients is +thus brought about. + +~Nitro-Jute.~--It is obtained by treating jute with nitric acid. Its +properties have been studied by Messrs Cross and Bevan (_Jour. Chem. +Soc._, 1889, 199), and by Mühlhäusen. The latter used for its nitration an +acid mixture composed of equal parts of nitric and sulphuric acids, which +was allowed to act upon the jute for some time. He found that with long +exposure, i.e., from three to four hours in the acids, there was a +disintegrating of the fibre-bundles, and the nitration was attended by +secondary decomposition and conversion into products soluble in the acid +mixture. Cross and Bevan's work upon this subject leads them to conclude +that the highest yield of nitrate is represented by an increase of weight +of 51 per cent. They give jute the empirical formula C_{12}H_{18}O_{9} (C += 47 per cent. H = 6 per cent., and O = 47 per cent.), and believe its +conversion into a nitro compound to take place thus:-- + +C_{12}H_{18}O + 3HNO_{3} = C_{12}H_{15}O_{6}(NO_{3})_{3} + 3H_{2}O. + +This is equivalent to a gain in weight of 44 per cent. for the tri- +nitrate, and of 58 per cent. for the tetra-nitrate. The formation of the +tetra-nitrate appears to be the limit of nitration of jute-fibre. In other +words, if we represent the ligno-cellulose molecule by a C_{12} formula, +it will contain four hydroxyl (OH) groups, or two less than cellulose +similarly represented. The following are their nitration results:-- + +Acids used.--I. HNO_{3} sp. gr. 1.43, and H_{2}SO_{4} = 1.84 equal parts. + II. 1 vol. HNO_{3}(1.5), 1 vol. H_{2}SO_{4}(1.84). + III. 1 vol. HNO_{3}(1.5), 75 vols. H_{2}SO_{4}(1.84). + +I. = 144.4; II. = 153.3; III. = 154.4 grms.; 100 grms. of fibre being used +in all three cases. + +Duration of exposure, thirty minutes at 18° C. + +The nitrogen was determined in the products, and equalled 10.5 per cent. +Theory for C_{12}H_{15}O_{6}(NO_{3})_{3} = 9.5 per cent. and for +C_{12}H_{15}O_{6}(NO_{3})_{4} = 11.5 per cent. These nitrates resemble +those of cellulose, and are in all essential points nitrates of ligno- +cellulose. + +Mühlhäusen obtained a much lower yield, and probably, as pointed out by +Cross and Bevan, a secondary decomposition took place, and his products, +therefore, probably approximate to the derivatives of cellulose rather +than to those of ligno-cellulose, the more oxidisable, non-cellulose, or +lignone constituents having been decomposed. In fact, he regards his +product as cellulose penta-nitrate (C_{12}H_{16}O_{5}(ONO_{2})_{5}). The +_Chemiker Zeitung_, xxi., p. 163, contains a further paper by Mühlhäusen +on the explosive nitro-jute. After purifying the jute-fibre by boiling it +with a 1 per cent. solution of sodium carbonate, and washing with water, +he treated 1 part of the purified jute with 15 parts of nitro-sulphuric +acid, and obtained the following results with different proportions of +nitric to sulphuric acids:-- + + Yield Ignition Nitrogen. + per cent. Point. +Experiment I.-- 1. HNO_{3} 1. H_{2}SO_{4} 129.5 170° C. 11.96% + " II. " 2. " 132.2 167° C. 12.15% + " III. " 3. " 135.8 169° C. 11.91% + +An experiment made with fine carded jute and the same mixture of acids as +in No. II. gave 145.4 per cent. nitro-jute, which ignited at 192° C., and +contained 12 per cent. nitrogen. This explosive is not at present +manufactured upon the large scale, and Messrs Cross and Bevan are of +opinion that there is no very obvious advantage in the use of lignified +textile fibre as raw materials for explosive nitrates, seeing that a large +number of raw materials containing cellulose (chiefly as cotton) can be +obtained at a cheaper rate, and yield also 150 to 170 per cent. of +explosive material when nitrated, and are in many ways superior to the +products obtained hitherto from jute. + +~Nitro-mannite~ is formed by the action of nitric acid on mannite, a +hex-acid alcohol closely related to sugar. It occurs abundantly in manna, +which is the partly dried sap of the manna-ash (_Fraxinus ornus_). It is +formed in the lactic acid fermentation of sugar, and by the action of +nascent hydrogen on glucose and cellulose, or on invert sugar. Its formula +is C_{6}H_{8}(OH)_{6} and that of nitro-mannite C_{6}H_{8}(NO_{3})_{6}. +Mannite crystallises in needles or rhombic prisms, which are soluble in +water and alcohol, and have a sweet taste. Nitro-mannite forms white +needle-shaped crystals, insoluble in water, but soluble in ether or +alcohol. When rapidly heated, they ignite at about 374° F., and explode at +about 590° F. It is more susceptible to friction and percussion than +nitro-glycerine, and unless pure it is liable to spontaneous +decomposition. It is considered as the nitric ether of the hexatomic +alcohol mannite. It is formed by the action of a mixture of nitric and +sulphuric acids upon mannite-- + +C_{6}H_{8}(OH)_{6} + 6HNO_{3} = C_{6}H_{8}(NO_{3})_{6} + 6H_{2}O. + +Its products of explosion are as shown in the following equation:-- + +C_{6}H_{8}(OH)_{6} = 6CO_{2} + 4H_{2}O + 3N_{2} + O_{2}. + +Its percentage composition is as follows:--Carbon, 15.9 per cent.; +hydrogen, 1.8 per cent.; nitrogen, 18.6 per cent.; and oxygen, 63.7 per +cent. Its melting point is 112 to 113° C., and it solidifies at 93°. When +carefully prepared and purified by recrystallisation from alcohol, and +kept protected from sunlight, it can be kept for several years without +alteration. + +Nitro-mannite is more dangerous than nitro-glycerine, as it is more +sensitive to shock. It is intermediate in its shattering properties +between nitro-glycerine and fulminate of mercury. It explodes by the shock +of copper on iron or copper, and even of porcelain on porcelain, provided +the latter shock be violent. Its heat of formation from its elements is ++156.1 calories. It is not manufactured upon the commercial scale. + +Besides the nitro compounds already described, there are many others, but +they are of little importance, and are none of them made upon the large +scale. Among such substances are _nitro-coal_, which is made by the action +of nitric acid on coal; _nitro-colle_, a product which results from the +action of nitric acid on isinglass or gelatine, soaked in water. It is +then treated with the usual acids. + +Another method is to place strong glue in cold water until it has absorbed +the maximum amount of the latter. The mixture is solidified by the +addition of nitric acid, nitrated in the usual way, and well washed. +Abel's _Glyoxiline_ is only nitrated gun-cotton impregnated with nitro- +glycerine. Nitro-lignine is only nitro-cellulose made from wood instead of +cotton; and nitro-straw is also only nitro-cellulose. The explosive known +as _Keil's Explosive_ contains nitro-glucose. Nitro-molasses, which is a +liquid product, has also been proposed, and nitro-saccharose, the product +obtained by the nitration of sugar. It is a white, sandy, explosive +substance, soluble in alcohol and ether. When made from cane sugar, it +does not crystallise; but if made from milk sugar, it does. It has been +used in percussion caps, being stronger and quicker than nitro-glycerine. +It is, however, very sensitive and very hygroscopic, and very prone to +decomposition. Nitro-tar, made from crude tar-oil, by nitration with +nitric acid of a specific gravity of 1.53 to 1.54. Nitro-toluol is used, +mixed with nitro-glycerine. This list, however, does not exhaust the +various substances that have been nitrated and proposed as explosives. +Even such unlikely substances as horse dung have been experimented with. +None of them are very much used, and very few of them are made upon the +manufacturing scale. + + + + +CHAPTER IV. + +_DYNAMITE AND GELATINES._ + +Kieselguhr Dynamite--Classification of Dynamites--Properties and +Efficiency of Ordinary Dynamite--Other Forms of Dynamite--Gelatine and +Gelatine Dynamites, Suitable Gun-Cotton for, and Treatment of--Other +Materials used--Composition of Gelignite--Blasting Gelatine--Gelatine +Dynamite--Absorbing Materials--Wood Pulp--Potassium Nitrate, &c.-- +Manufacture and Apparatus used, and Properties of Gelatine Dynamites-- +Cordite--Composition and Manufacture. + + +~Dynamite.~--Dynamite consists of nitro-glycerine either absorbed by some +porous material, or mixed with some other substance or substances which +are either explosives or merely inert materials. Among the porous +substances used is kieselguhr, a silicious earth which consists chiefly of +the skeletons of various species of diatoms. This earth occurs in beds +chiefly in Hanover, Sweden, and Scotland. The best quality for the purpose +of manufacturing dynamite is that which contains the largest quantity of +the long tubular _bacillariæ_, and less of the round and lancet-shaped +forms, such as _pleurosigmata_ and _diclyochæ_, as the tube-shaped diatoms +absorb the nitro-glycerine better, and it becomes packed into the centre +of the silicious skeleton of the diatoms, the skeleton acting as a kind of +tamping, and increasing the intensity of the explosion. + +Dynamites are classified by the late Colonel Cundill, R.A., in his +"Dictionary of Explosives" as follows:-- + +1. Dynamites with an inert base, acting merely as an absorbent. + +2. Dynamites with an active base, i.e., an explosive base. No. 2 may be +again divided into three minor classes, which contain as base-- + +(_a._) Charcoal. + +(_b._) Gunpowder or other nitrate, or chlorate mixture. + +(_c._) Gun-cotton or other nitro compound (nitro-benzol, &c.). + +The first of these, viz., charcoal, was one of the first absorbents for +nitro-glycerine ever used; the second is represented by the well-known +Atlas powder; and the last includes the well-known and largely used +gelatine compounds, viz., gelignite and gelatine dynamite, and also tonite +No. 3, &c. + +In the year 1867 Nobel produced dynamite by absorbing the nitro-glycerine +in an inert substance, forming a plastic mass. In his patent he says: +"This invention relates to the use of nitro-glycerine in an altered +condition, which renders it far more practical and safe for use. The +altered condition of the nitro-glycerine is effected by causing it to be +absorbed in porous unexplosive substances, such as charcoal, silica, +paper, or similar materials, whereby it is converted into a powder, which +I call dynamite, or Nobel's safety powder. By the absorption of the nitro- +glycerine in some porous substance it acquires the property of being in a +high degree insensible to shocks, and it can also be burned over a fire +without exploding." + +Ordinary dynamite consists of a mixture of 75 per cent. of nitro-glycerine +and 25 per cent. of kieselguhr. The guhr as imported (Messrs A. Haake & +Co. are the chief importers) contains from 20 to 30 per cent. of water and +organic matter. The water may be very easily estimated by drying a weighed +quantity in a platinum crucible at 100° C. for some time and re-weighing, +and the organic matter by igniting the residue strongly over a Bunsen +burner. Before the guhr can be used for making dynamite it must be +calcined, in order not only to get rid of moisture, but also the organic +matter. + +A good guhr should absorb four times its weight of nitro-glycerine, and +should then form a comparatively dry mixture. It should be pale pink, red +brown, or white. The pink is generally preferred, and it should be as free +as possible from grit of all kinds, quartz particles, &c., and should have +a smooth feeling when rubbed between the finger and thumb, and should show +a large quantity of diatoms when viewed under the microscope. The +following was the analysis of a dried sample of kieselguhr:--Silica, +94.30; magnesia, 2.10; oxide of iron and alumina, 1.3; organic matter, +0.40; moisture, 1.90 per cent. + +The guhr is generally dried in a reverberatory muffle furnace. It is +spread out on the bottom to the thickness of 3 or 4 inches, and should +every now and then be turned over and raked about with an iron rabble or +hoe. The temperature should be sufficiently high to make the guhr red hot, +or the organic matter will not be burnt off. The time occupied in +calcining will depend of course upon the quality of the guhr being +operated upon. Those containing a high percentage of water and organic +matter will of course take longer than those that do not. A sample of the +calcined guhr should not contain more than 0.5 per cent. of moisture and +organic matter together. + +After the guhr is dry it requires to be sifted and crushed. The crushing +is done by passing it between iron rollers fixed at the bottom of a cone +or hopper, and revolving at a moderate speed. Beneath the rollers a fine +sieve should be placed, through which the guhr must be made to pass. + +The kieselguhr having been dried, crushed, and sifted, should be packed +away in bags, and care should be taken that it does not again absorb +moisture, as if it contains anything above about five-tenths per cent. of +water it will cause the dynamite made with it to exude. The guhr thus +prepared is taken up to the danger area, and mixed with nitro-glycerine. +The nitro-glycerine used should be quite free from water, and clear, and +should have been standing for a day or two in the precipitating house. The +guhr and nitro-glycerine are mixed in lead tanks (about 1-1/2 foot deep, +and 2 to 3 feet long), in the proportions of 75 of the nitro-glycerine to +25 of the guhr, unless the guhr is found to be too absorbent, which will +cause the dynamite to be too dry and to crumble. In this case a small +quantity of barium sulphate, say about 1 per cent., should be added to the +guhr. This will lessen its absorbing powers, or a highly absorptive sample +of guhr may be mixed with one of less absorptive power, in the proportions +found by experiment to be the best suited to make a fairly moist dynamite, +but one that will not exude. + +The mixing itself is generally performed in a separate house. In a series +of lead-lined tanks the guhr is weighed, placed in a tank, and the nitro- +glycerine poured on to it. The nitro-glycerine may be weighed out in +indiarubber buckets. The whole is then mixed by hand, and well rubbed +between the hands, and afterwards passed through a sieve. At this stage +the dynamite should be dry and powdery, and of a uniform colour. + +It is now ready to be made up into cartridges, and should be taken over to +the cartridge huts. These are small buildings surrounded with mounds, and +contain a single cartridge machine. Each hut requires three girls--one to +work the press, and two to wrap up the cartridges. The cartridge press +consists of a short cylinder of the diameter of the cartridge that it is +intended to make. Into this cylinder a piston, pointed with ivory or +lignum vitæ wood, works up and down from a spring worked by a lever. Round +the upper edge of the cylinder is fastened a canvas bag, into which the +powdery dynamite is placed by means of a wooden scoop, and the descending +piston forces the dynamite down the cylinder and out of the open end, +where the compressed dynamite can be broken off at convenient lengths. The +whole machine should be made of gun-metal, and should be upright against +the wall of the building. The two girls, who sit at tables placed on each +side of the press, wrap the cartridges in parchment paper. From these huts +the cartridges are collected by boys every ten minutes or a quarter of an +hour, and taken to the packing room, where they are packed in 5-lb. +cardboard boxes, which are then further packed in deal boxes lined with +indiarubber, and fastened down air tight. The wooden lids are then nailed +down with brass or zinc nails, and a label pasted on the outside giving +the weight and description of the contents. The boxes should then be +removed to the magazines. It is well to take a certain number of +cartridges from the packing house at different times during the day, say +three or four samples, and to test them by the heat test. A sample cut +from a cartridge, about 1 inch long, should be placed under a glass shade, +together with water (a large desiccator, in fact), and left for some days. +A good dynamite should not, under these conditions, show any signs of +exudation, even after weeks.[A] + +[Footnote A: For analysis of dynamite, see chapter on "Analysis," and +author's article in _Chem. News_, 23rd September 1892.] + +~Properties of Kieselguhr Dynamite.~--One cubic foot of dynamite weighs 76 +lbs. 4 oz. The specific gravity of 75 per cent. dynamite is, however, +1.50. It is a red or grey colour, and rather greasy to the touch. It is +much less sensitive to shock than nitro-glycerine, but explodes +occasionally with the shock of a rifle bullet, or when struck. The +addition of a few per cent. of camphor will considerably diminish its +explosive qualities to such an extent that it can be made non-explosive +except to a very strong fulminate detonator. The direct contact of water +disintegrates dynamite, separating the nitro-glycerine, hence great +caution is necessary in using it in wet places. It freezes at about 40° +Fahr. (4° C.), and remains frozen at temperatures considerably exceeding +that point. When frozen, it is comparatively useless as an explosive +agent, and must be thawed with care. This is best done by placing the +cartridges in a warming pan, which consists of a tin can, with double +sides and bottom, into which hot water (130° Fahr.) can be poured. The +dynamite will require to be left in for some considerable time before it +becomes soft. On no account must it be placed on a hot stove or near a +fire, as many serious accidents have occurred in this way. + +Frozen dynamite is a hard mass, with altered properties, and requires 1.5 +grm. of fulminate instead of 0.5 grm. to explode it. Thawing may also +cause exudation of the nitro-glycerine, which is much more sensitive to +shock, and if accidentally struck with an iron tool, may explode. It is a +dangerous thing to cut a frozen cartridge with a knife. Ramming is even +more dangerous; in fact it is not only dangerous, but wasteful, to use +dynamite when in a frozen state. + +Dynamite explodes at a temperature of 360° Fahr., and is very sensitive to +friction when hot. In hot countries it should never be exposed to the rays +of the sun. It should, however, not be kept in a damp or moist place, as +this is liable to cause exudation. Sunlight, if direct, can cause a slow +decomposition, as with all nitro and nitric compounds. Electric sparks +ignite, without exploding it, at least when operating in the open air. + +Dynamite, when made with neutral nitro-glycerine, appears to keep +indefinitely. Sodium or calcium carbonate to the extent of 1 per cent. is +often added to dynamite to ensure its being neutral. If it has commenced +to undergo change, however, it rapidly becomes acid, and sometimes +explodes spontaneously, especially if contained in resisting envelopes. +Nevertheless, neutral and well-made dynamite has been kept for years in a +magazine without loss of its explosive force. If water is brought into +contact with it, the nitro-glycerine is gradually displaced from the +silica (guhr). This action tends to render all wet dynamite dangerous. + +It has been observed that a dynamite made with wood sawdust can be +moistened and then dried without marked alteration, and from 15 to 20 per +cent. of water may be added to cellulose dynamite without depriving it of +the power of exploding by strong detonator (this is similar to wet +gun-cotton). It is, however, rendered much less sensitive to shock. With +regard to the power of No. 1 dynamite, experiments made in lead cylinders +give the relative value of No. 1 dynamite, 1.0; blasting gelatine, 1.4; +and nitro-glycerine, 1.4. The heat liberated by the sudden explosion of +dynamite is the same as its heat of combustion,[A] and proportionate to +the weight of nitro-glycerine contained in the mixture. The gases formed +are carbonic acid, water, nitrogen, and oxygen. + +[Footnote A: Berthelot, "Explosives and their Power."] + +The "explosive wave" (of Berthelot) for dynamite is about 5,000 metres per +second. At this rate the explosion of a cartridge a foot long would only +occupy 1/24000 part of a second, while a ton of dynamite cartridges about +7/8 diameter, laid end to end, and measuring one mile in length, would be +exploded in one-quarter of a second by detonating a cartridge at either +end.[A] Mr C. Napier Hake, F.I.C., the Inspector of Explosives for the +Victorian Government, in his paper, "Notes on Explosives," says: "The +theoretical efficiency of an explosive cannot in practice be realised in +useful work for several reasons, as for instance in blasting rock-- + +"1. Incomplete combustion. + +"2. Compression and chemical changes induced in surrounding material. + +"3. Energy expended in cracking and heating of the material which is not +displaced. + +"4. The escape of gas through the blast-hole and the fissures caused by +the explosion. + +"The useful work consists partly in displacing the shattered masses. The +proportion of useful work obtainable has been variously estimated at from +14 to 33 per cent. of the theoretical maximum potential." + +[Footnote A: C.N. Hake, "Notes on Explosives," _Jour. Soc. Chem. Ind._, +1889.] + +Among the various forms of dynamite that are manufactured is carbo- +dynamite, the invention of Messrs Walter F. Reid and W.D. Borland. The +base is nitro-glycerine, and the absorbent is carbon in the form of burnt +cork. It is as cheap as ordinary dynamite, and has greater explosive +force, seeing that 90 per cent. of the mixture is pure nitro-glycerine, +and the absorbent itself is highly combustible. It is also claimed that if +this dynamite becomes wet, no exudation takes place. + +Atlas powder is a dynamite, chiefly manufactured in America at the Repanno +Chemical Works, Philadelphia. It is a composition of nitro-glycerine, +wood-pulp, nitrate of soda, and carbonate of magnesia. This was the +explosive used in the outrages committed in London, by the so-called +"dynamiters." Different varieties contain from 20 to 75 per cent. of +nitro-glycerine. + +The Rhenish dynamite, considerably used in the mines of Cornwall, is +composed of 70 parts of a solution of 2 to 3 per cent. of naphthalene in +nitro-glycerine, 3 parts of chalk, 7 parts of sulphate of barium, and 20 +of kieselguhr. + +Kieselguhr dynamites are being largely given up in favour of gelatine +explosives. The late Colonel Cundill, in his "Dictionary of Explosives," +gives a list of about 125 kinds of dynamites. Many of these, however, are +not manufactured. Among the best known after the ordinary No. 1 dynamite +are forcite, ammonia dynamite, litho-fracteur, rendock, Atlas powder, +giant powder, and the various explosive gelatines. They all contain nitro- +glycerine, mixed with a variety of other substances, such as absorbent +earths, wood-pulp, nitro-cotton, carbon in some form or other, nitro- +benzol, paraffin, sulphur, nitrates, or chlorates, &c. &c. + +~Blasting Gelatine and Gelatine Dynamite.~--The gelatine explosives +chiefly in use are known under the names of blasting gelatine, gelatine +dynamite, and gelignite. They all consist of the variety of nitro- +cellulose known as collodion-cotton, i.e., a mixture of the penta- and +tetra-nitrates dissolved in nitro-glycerine, and made up with various +proportions of wood-pulp, and some nitrate, or other material of a similar +nature. As the gun-cotton contains too little oxygen for complete +combustion, and the nitro-glycerine an excess, a mixture of the two +substances is very beneficial. + +Blasting gelatine consists of collodion-cotton and nitro-glycerine without +any other substance, and was patented by Mr Alfred Nobel in 1875. It is a +clear, semi-transparent, jelly-like substance, of a specific gravity of +1.5 to 1.55, slightly elastic, resembling indiarubber, and generally +consists of 92 per cent. to 93 per cent. of nitro-glycerine, and 7 to 8 +per cent. of nitro-cotton. The cotton from which it is made should be of +good quality. The following is the analysis of a sample of nitro-cellulose +which made very good gelatine:- + +Soluble cotton 99.118 per cent. +Gun-cotton 0.642 " +Non-nitrated cotton 0.240 " +Nitrogen 11.64 " +Total ash 0.25 " + +The soluble cotton, which is a mixture of the tetra- and penta-nitrates, +is soluble in ether-alcohol, and also in nitro-glycerine, and many other +solvents, whereas the hexa-nitrate (gun-cotton), +C_{12}H_{14}O_{4}(ONO_{2})_{6}, is not soluble in the above liquids, +although it is soluble in acetone or acetic ether. It is very essential, +therefore, that the nitro-cotton used in the manufacture of the gelatine +explosives should be as free as possible from gun-cotton, otherwise little +lumps of undissolved nitro-cotton will be left in the finished gelatine. +The non-nitrated or unconverted cotton should also be very low, in fact +considerably under 1/2 per cent. + +The nitro-cotton and the nitro-glycerine used should always be tested +before use by the heat test, because if they do not separately stand this +test, it cannot be expected that the gelatine made from them will do so. +It often occurs, however, that although both the ingredients stand this +test separately before being mixed, that after the process of manufacture +one or other or both fail to do so. + +The nitro-cotton most suitable for gelatine making is that which has been +finely pulped. If it is not already fine enough, it must be passed through +a fine brass wire sieve. It will be found that it requires to be rubbed +through by hand, and will not go through at all if in the least degree +damp. It is better, therefore, to dry it first. The percentage of nitrogen +in the nitrated cotton should be over 11 per cent. It should be as free as +possible from sand or grit, and should give but little ash upon ignition, +not more than 0.25 per cent. The cotton, which is generally packed wet in +zinc-lined wooden boxes, will require to be dried, as it is very essential +indeed that none of the materials used in the manufacture of gelatine +should contain more than the slightest trace of water. If they do, the +gelatine subsequently made from them will most certainly exude, and become +dangerous and comparatively valueless. It will also be much more difficult +to make the nitro-cotton dissolve in the nitro-glycerine if either +contains water. + +In order to find out how long any sample of cotton requires to be dried, a +sample should be taken from the centre of several boxes, well mixed, and +about 1,000 grms. spread out on a paper tray, weighed, and the whole then +placed in the water oven at 100° C., and dried for an hour or so, and +again weighed, and the percentage of moisture calculated from the loss in +weight. This will be a guide to the time that the cotton will probably +require to be in the drying house. Samples generally contain from 20 to 30 +per cent. of water. After drying for a period of forty-eight hours, a +sample should be again dried in the oven at 100° C., and the moisture +determined, and so on at intervals until the bulk of the cotton is found +to be dry, i.e., to contain from 0.25 to 0.5 per cent. of moisture. It is +then ready to be sifted. During the process of removing to the sifting +house and the sifting itself, the cotton should be exposed to the air as +little as possible, as dry nitro-cotton absorbs as much as 2 per cent. of +moisture from the air at ordinary temperatures and average dryness. + +The drying house usually consists of a wooden building, the inside of +which is fitted with shelves, or rather framework to contain drawers, made +of wood, with brass or copper wire netting bottoms. A current of hot air +is made to pass through the shelves and over the surface of the cotton, +which is spread out upon them to the depth of about 2 inches. This current +of air can be obtained in any way that may be found convenient, such as by +means of a fan or Root's blower, the air being passed over hot bricks, or +hot-water pipes before entering the building. The cotton should also be +occasionally turned over by hand in order that a fresh surface may be +continually exposed to the action of the hot air. The building itself may +be heated by means of hot-water pipes, but on no account should any of the +pipes be exposed. They should all be most carefully covered over with +wood-work, because when the dry nitro-cotton is moved, as in turning it +over, very fine particles get into the air, and gradually settling on the +pipes, window ledges, &c., may become very hot, when the slightest +friction might cause explosion. It is on this account that this house +should be very carefully swept out every day. It is also very desirable +that the floor of this house should be covered with oilcloth or linoleum, +as being soft, it lessens the friction. + +List shoes should always be worn in this building, and a thermometer hung +up somewhere about the centre of the house, and one should also be kept in +one of the trays to give the temperature of the cotton, especially the +bottom of the trays. The one nearest to the hot air inlet should be +selected. If the temperature of the house is kept at about 40° C. it will +be quite high enough. The building must of course be properly ventilated, +and it will be found very useful to have the walls made double, and the +intervening space filled with cinders, and the roof covered with felt, as +this helps to prevent the loss of heat through radiation, and to preserve +a uniform temperature, which is very desirable. + +The dry cotton thus obtained, if not already fine enough, should be sifted +through a brass sieve, and packed away ready for use in zinc air-tight +cases, or in indiarubber bags. The various gelatine compounds, gelignite, +gelatine dynamite, and blasting gelatine, are manufactured in exactly the +same way. The forms known as gelatine dynamite differ from blasting +gelatine in containing certain proportions of wood-pulp and potassium +nitrate, &c. The following are analyses of some typical samples of the +three compounds:-- + + Gelatine Blasting + Gelignite. Dynamite. Gelatine. + +Nitro-glycerine 60.514 71.128 92.94 per cent. +Nitro-cellulose 4.888 7.632 7.06 " +Wood-pulp 7.178 4.259 ... " +Potassium nitrate 27.420 16.720 ... " +Water ... 0.261 ... " + +The gelignite and gelatine dynamites consist, therefore, of blasting +gelatine, thickened up with a mixture of absorbing materials. Although the +blasting gelatine is weight for weight more powerful, it is more difficult +to make than either of the other two compounds, it being somewhat +difficult to make it stand the exudation and melting tests. The higher +percentage of nitro-cotton, too, makes it expensive. + +When the dry nitro-cotton, which has been carefully weighed out in the +proportions necessary either for blasting gelatine or any of the other +gelatine explosives, is brought to the gelatine making house, it is placed +in a lead-lined trough, and the necessary quantity of pure dry nitro- +glycerine poured upon it. The whole is then well stirred up, and kept at a +temperature of from 40° to 45° C. It should not be allowed to go much +above 40° C.; but higher temperatures may be used if the nitro-cotton is +very obstinate,[A] and will not dissolve. Great caution must, however, be +observed in this case. The mixture should be constantly worked about by +the workman with a wooden paddle for at least half an hour. At a +temperature of 40° to 45° the nitro-glycerine acts upon the nitro-cotton +and forms a jelly. Without heat the gelatinisation is very imperfect +indeed, and at temperatures under 40° C. takes place very slowly. + +[Footnote A: Generally due to the nitro-cotton being damp.] + +[Illustration: FIG. 30.--WERNER, PFLEIDERER, & PERKINS' MIXING MACHINE.] + +The limit of temperature is 50° C. or thereabouts. Beyond this the jelly +should never be allowed to go, and to 50° only under exceptional +circumstances. + +The tank in which the jelly is made is double-lined, in order to allow of +the passage of hot water between its inner and outer linings. A series of +such tanks are generally built in a wooden framework, and the double +linings are made to communicate, so that the hot water can flow from one +to the other consecutively. The temperature of the water should be about +60° C. if it is intended to gelatinise at 45° C., and about 80° if at +50° C.; but this point must, of course, be found by experiment for the +particular plant used. An arrangement should be made to enable the workman +to at once cut off the supply of hot water and pass cold water through the +tanks in case the explosive becomes too hot. + +[Illustration: FIG. 31.--MR M'ROBERTS' MIXER FOR GELATINE EXPLOSIVES.] + +The best way to keep the temperature of the water constant is to have a +large tank of water raised upon a platform, some 5 or 6 feet high, outside +the building, which is automatically supplied with water, and into which +steam is turned. A thermometer stuck through a piece of cork and floated +upon the surface of the tank will give the means of regulating the +temperature. + +When the jelly in the tanks has become semi-transparent and the cotton has +entirely dissolved, the mixture should be transferred to the mixing +machine. The mixing machines are specially designed for this work, and are +built in iron, with steel or bronze kneading- and mixing-blades, according +to requirements. + +A suitable machine for the purpose is that known as the Nito-Universal +Incorporator, shown in Fig. 30, which has been specially constructed by +Messrs Werner, Pfleiderer, & Perkins, Ltd., after many years' experience +in the mixing of explosive materials, and is now almost exclusively +adopted in both Government and private factories. Mr George M'Roberts'[A] +mixing machine, however, which is shown in Fig. 31, is still used in some +factories for dynamite jelly. + +[Footnote A: See _Jour. Soc. Chem. Ind._, 1890, 267.] + +If it is intended to make gelignite, or gelatine dynamite, it is at this +point that the proper proportions of wood-pulp[A] and potassium nitrate +should be added, and the whole well mixed for at least half an hour, until +the various ingredients are thoroughly incorporated. + +[Footnote A: Most of the wood-pulp used in England is obtained from +pine-trees, but poplar, lime, birch, and beech wood are also used. It is +chiefly imported as wood-pulp. The pulp is prepared as follows:--The bark +and roots are first removed, and the logs then sawn into boards, from +which the knots are removed. The pieces of wood are afterwards put through +a machine which breaks them up into small pieces about an inch long, which +are then crushed between rollers. These fragments are finally boiled with +a solution of sodium bisulphite, under a pressure of about 90 lbs. per +square inch, the duration of the boiling being from ten to twelve hours. +Sulphurous acid has also been used. Pine-wood yields about 45 per cent. +and birch about 40 per cent. of pulp when treated by this process. The +pulp is afterwards bleached and washed, &c. + + Birch. Beech. Lime. Pine. Poplar. +Cellulose 55.52 45.47 53.09 56.99 62.77 per cent. +Resin 1.14 0.41 3.93 0.97 1.37 " +Aqueous extract 2.65 2.47 3.56 1.26 2.88 " +Water 12.48 12.57 10.10 13.87 12.10 " +Lignine 28.21 39.14 29.32 26.91 20.88 "] + +The following analysis of woods is by Dr H. Müller:--These mixing machines +can either be turned by hand, or a shaft can be brought into the house and +the machine worked by means of a belt at twenty to thirty revolutions per +minute. The bearings should be kept constantly greased and examined, and +the explosive mixture carefully excluded. When the gelatine mixture has +been thoroughly incorporated, and neither particles of nitrate or wood +meal can be detected in the mass, it should be transferred to wooden boxes +and carried away to the cartridge-making machines to be worked up into +cartridges. + +[Illustration: FIG. 32.--PLAN OF THE BOX CONTAINING THE EXPLOSIVE, IN +M'ROBERTS' MACHINE.] + +The application of heat in the manufacture of the jelly from collodion- +cotton and nitro-glycerine is absolutely necessary, unless some other +solvent is used besides the nitro-glycerine, such as acetone, acetic +ether, methyl, or ethyl-alcohol. (They are all too expensive, with the +exception of acetone and methyl-alcohol, for use upon the large scale.) +These liquids not only dissolve the nitro-cellulose in the cold, but +render the resulting gelatine compound less sensitive to concussion, and +reduce its quickness of explosion (as in cordite). They also lower the +temperature at which the nitro-glycerine becomes congealed, i.e., they +lower the freezing point[A] of the resulting gelatine. + +[Footnote A: It has been proposed to mix dynamite with amyl alcohol for +this purpose. Di-nitro-mono-chlorhydrine has also been proposed.] + +The finished gelatine paste, upon entering the cartridge huts, is at once +transferred to the cartridge-making machine, which is very like an +ordinary sausage-making machine[A] (Fig. 33). The whole thing must be made +of gun-metal or brass, and it consists of a conical case containing a +shaft and screw. The revolutions of the shaft cause the thread of the +screw to push forward the gelatine introduced by the hopper on the top to +the nozzle, the apex of the cone-shaped case, from whence the gelatine +issues as a continuous rope. The nozzle is of course of a diameter +according to the size of cartridge required. + +[Footnote A: G. M'Roberts, _Jour. Soc. Chem. Ind._, 31st March 1890, p. +266.] + +[Illustration: FIG. 33.--CARTRIDGE-MAKING MACHINE FOR GELATINE +EXPLOSIVES.] + +The issuing gelatine can of course be cut off at any length. This is best +done with a piece of hard wood planed down to a cutting edge, i.e., +wedge-shaped. Mr Trench has devised a kind of brass frame, into which the +gelatine issuing from the nozzle of the cartridge machine is forced, +finding its way along a series of grooves. When the frame is full, a +wooden frame, which is hinged to one end of the bottom frame, and fitted +with a series of brass knives, is shut down, thereby cutting the gelatine +up into lengths of about 4 inches. + +It is essential that the cartridge machines should have no metallic +contacts inside. The bearing for the screw shaft must be fixed outside the +cone containing the gelatine. One of these machines can convert from 5 to +10 cwt. of gelatine into cartridges per diem, depending upon the diameter +of the cartridges made. + +After being cut up into lengths of about 3 inches, the gelatine is rolled +up in cartridge paper. Waterproof paper is generally used. The cartridges +are then packed away in cardboard boxes, which are again packed in deal +boxes lined with indiarubber, and screwed down air tight, brass screws or +zinc or brass nails being used for the purpose. These boxes are sent to +the magazines. Before the boxes are fastened down a cartridge or so should +be removed and tested by the heat test, the liquefaction test, and the +test for liability to exudation. (Appendix, p. 6, Explosives Act, 1875.) A +cartridge also should be stored in the magazine in case of any subsequent +dispute after the bulk of the material has left the factory. + +The object of the liquefaction test is to ensure that the gelatine shall +be able to withstand a fairly high temperature (such as it might encounter +in a ship's hold) without melting or running together. The test is carried +out as follows:--A cylinder of the gelatine dynamite is cut from the +cartridge of a length equal to its diameter. The edges must be sharp. This +cylinder is to be placed on end on a flat surface (such as paper), and +secured by a pin through the centre, and exposed for 144 consecutive hours +to a temperature of 85° to 90° F., and during such time the cylinder +should not diminish in height by more than one-fourth of an inch, and the +cut edges should remain sharp. There should also be no stain of +nitroglycerine upon the paper. + +The exudation test consists in freezing and thawing the gelatine three +times in succession. Under these conditions there should be no exudation +of nitro-glycerine. All the materials used in the manufacture of gelatine +explosives should be subjected to analytical examination before use, as +success largely depends upon the purity of the raw materials. The +wood-pulp, for instance, must be examined for acidity. + +~Properties of the Gelatine Compounds.~--Blasting gelatine is generally +composed of 93 to 95 parts nitro-glycerine, and 5 to 7 parts of nitro- +cellulose, but the relative proportions of explosive base and nitro- +glycerine, &c., in the various forms of the gelatine explosives do not +always correspond to those necessary for total combustion, either because +an incomplete combustion gives rise to a greater volume of gas, or because +the rapidity of decomposition and the law of expansion varies according to +the relative proportions and the conditions of application. The various +additions to blasting gelatine generally have the effect of lowering the +strength by reducing the amount of nitro-glycerine, but this is sometimes +done in order to change a shattering agent into a propulsive force. If +this process be carried too far, we of course lose the advantages due to +the presence of nitro-glycerine. There is therefore a limit to these +additions.[A] + +[Footnote A: Mica is said to increase the rapidity of explosion when mixed +with gelatine.] + +The homogeneousness and stability of the mixture are of the highest +importance. It is highly essential that the nitro-glycerine should be +completely absorbed by the substances with which it is mixed, and that it +should not subsequently exude when subjected to heat or damp. It is also +important that there should be no excess of nitro-glycerine, as this may +diminish instead of augment the strength, owing to a difference in the +mode of the propagation of the explosive wave in the liquid, and in the +mixture. Nitro-glycerine at its freezing point has a tendency to separate +from its absorbing material, in fact to exude. When frozen, too, it +requires a more powerful detonation to explode it, but it is less +sensitive to shock. The specific gravity of blasting gelatine is 1.5 +(i.e., nearly equal to that of nitro-glycerol); that of gun-cotton (dry) +is 1.0. + +Blasting gelatine burns in the air when unconfined without explosion, at +least in small quantities and when not previously heated, but it is rather +uncertain in this respect. It can be kept at a moderately high temperature +(70° C.) without decomposition. At higher temperatures the nitro-glycerine +will partially evaporate. When slowly heated, it explodes at 204° C. If, +however, it contains as much as 10 per cent. of camphor, it burns without +exploding. According to Berthelot,[A] gelatine composed of 91.6 per cent. +nitro-glycerine and 8.4 per cent. of nitro-cellulose, which are the +proportions corresponding to total combustion, produces by explosion +177CO_{2}+ 143H_{2}O + 8N_{2}. + +[Footnote A: Berthelot, "Explosives and their Powers."] + +He takes C_{24}H_{22}(NO_{3}H)_{9}O_{11} as the formula of the nitro- +cellulose, and 51C_{3}H_{2}(NO_{3}H)_{3} + C_{24}H_{22}(NO_{3}H)_{9}O_{11} +as the formula of the gelatine itself, its equivalent weight being 12,360 +grms. The heat liberated by its explosion is equal to 19,381 calories, or +for 1 kilo. 1,535 calories. Volume of gases reduced temperature equals +8,950 litres. The relative value[A] of blasting gelatine to nitro- +glycerine is as 1.4 to 1.45, kieselguhr dynamite being taken as 1.0. + +[Footnote A: Roux and Sarran.] + + + + +CHAPTER V. + +_NITRO-BENZOL, ROBURITE, BELLITE, PICRIC ACID, &c._ + +Explosives derived from Benzene--Toluene and Nitro-Benzene--Di- and +Tri-nitro-Benzene--Roburite: Properties and Manufacture--Bellite: +Properties, &c.--Securite--Tonite No. 3.--Nitro-Toluene-- +Nitro-Naphthalene--Ammonite--Sprengel's Explosives--Picric Acid-- +Picrates--Picric Powders--Melinite--Abel's Mixture--Brugère's Powders-- +The Fulminates--Composition, Formula, Preparation, Danger of, &c.-- +Detonators: Sizes, Composition, Manufacture--Fuses, &c. + + +~The Explosives derived from Benzene.~--There is a large class of +explosives made from the nitrated hydro-carbons--benzene, C_{6}H_{6}; +toluene, C_{7}H_{8}; naphthalene, C_{10}H_{8}; and also from phenol (or +carbolic acid), C_{6}H_{5}OH. The benzene hydro-carbons are generally +colourless liquids, insoluble in water, but soluble in alcohol and ether. +They generally distil without decomposition. They burn with a smoky flame, +and have an ethereal odour. They are easily nitrated and sulphurated; +mono, di, and tri derivatives are readily prepared, according to the +strength of the acids used. It is only the H-atoms of the benzene nucleus +which enter into reaction. + +Benzene was discovered by Faraday in 1825, and detected in coal-tar by +Hofmann in 1845. It can be obtained from that portion of coal-tar which +boils at 80° to 85° by fractionating or freezing.[A] The ordinary benzene +of commerce contains thiophene (C_{4}H_{4}S), from which it may be freed +by shaking with sulphuric acid. Its boiling point is 79° C.; specific +gravity at 0° equals 0.9. It burns with a luminous smoky flame, and is a +good solvent for fats, resins, sulphur, phosphorus, &c. Toluene was +discovered in 1837, and is prepared from coal-tar. It boils at 110° C., +and is still liquid at 28° C. + +[Footnote A: It may be prepared chemically pure by distilling a mixture of +benzoic acid and lime.] + +The mono-, chloro-, bromo-, and iodo-benzenes are colourless liquids of +peculiar odour. Di-chloro-, di-bromo-benzenes, tri- and hexa-chloro- and +bromo-benzenes, are also known; and mono-chloro-, C_{6}H_{4}Cl(CH_{3}), +and bromo-toluenes, together with di derivatives in the ortho, meta, and +para modifications. The nitro-benzenes and toluenes are used as +explosives. The following summary is taken from Dr A. Bernthsen's "Organic +Chemistry":-- + + SUMMARY. + ____________________________________________________________________ +| | +| C_{6}H_{5}(N0_{2}) Nitro-benzene. Liq. B.Pt. 206° C. | +| | +| C_{6}H_{4}(NO_{2})_{2} Ortho-, meta-, and para- di-nitro-benzenes. | +| Solid. M.P. 118°, 90°, and 172° C. | +| | +| C_{6}H_{3}(NO_{3})_{3} S.-Tri-nitro-benzene. Solid. M.P. 121° C. | +|____________________________________________________________________| +| | +| C_{6}H_{4}(CH_{3})NO_{2} Ortho-, meta-, and para- nitro-toluenes. | +| B.P. 218°, 230°, and 234° C, Para compound solid. | +|____________________________________________________________________| +| | +| C_{6}H_{3}(CH_{3})_{2}NO_{2} Nitro-xylene. Liquid. | +|____________________________________________________________________| +| | +| C_{6}H_{2}(CH_{3})_{3}NO_{2} Nitro-mesitylene. Solid. | +|____________________________________________________________________| +| | +| C_{6}H_{3}(CH_{3})(NO_{2})_{2} Di-nitro-toluenes. | +|____________________________________________________________________| +| | +| C_{6}H_{4}Cl(NO_{2}) Nitro-chloro-benzenes. | +| | +| C_{6}Br_{4}(NO_{2})_{2} Tetra-bromo-di-nitrobenzene. | +|____________________________________________________________________| + +The nitro compounds are mostly pale yellow liquids, which distil +unchanged, and volatilise with water vapour, or colourless or pale yellow +needles or prisms. Some of them, however, are of an intense yellow colour. +Many of them explode upon being heated. They are heavier than water, and +insoluble in it, but mostly soluble in alcohol, ether, and glacial acetic +acid. + +Nitro-benzene, C_{6}H_{5}(NO_{2}), was discovered in 1834 by Mitscherlich. +It is a yellow liquid, with a melting point of +3° C. It has an intense +odour of bitter almonds. It solidifies in the cold. In di-nitro-benzene, +the two nitro groups may be in the meta, ortho, or para position, the meta +position being the most general (see fig., page 4). By recrystallising +from alcohol, pure meta-di-nitro-benzene may be obtained in long +colourless needles. The ortho compound crystallises in tables, and the +para in needles. They are both colourless. When toluene is nitrated, the +para and ortho are chiefly formed, and a very little of the meta compound. + +~Nitro Compounds of Benzene and Toluene.~--The preparation of the nitro +derivatives of the hydrocarbons of the benzene series is very simple. It +is only necessary to bring the hydrocarbon into contact with strong nitric +acid, when the reaction takes place, and one or more of the hydrogen atoms +of the hydrocarbon are replaced by the nitryl group (NO_{2}). Thus by the +action of nitric acid on benzene (or benzol), mono-nitro-benzene is +formed:-- + +C_{6}H_{6} + HNO_{3} = C_{6}H_{5}.NO_{2} +H_{2}O. + Mono-nitro-benzene. + +By the action of another molecule of nitric acid, the di-nitro-benzene is +formed:-- + +C_{6}H_{5}.NO_{2} + HNO_{3} = C_{6}H_{4}(NO_{2})_{2} + H_{2}O. + Di-nitro-benzene. + +These nitro bodies are not acids, nor are they ethereal salts of nitrous +acid, as nitro-glycerine is of glycerine. They are regarded as formed from +nitric acid by the replacement of hydroxyl by benzene radicals. + +~Mono-nitro Benzene~ is made by treating benzene with concentrated nitric +acid, or a mixture of nitric and sulphuric acids. The latter, as in the +case of the nitration of glycerine, takes no part in the reaction, but +only prevents the dilution of the nitric acid by the water formed in the +reaction. Small quantities may be made thus:--Take 150 c.c. of H_{2}SO_{4} +and 75 c.c. HNO_{3}, or 1 part nitric to 2 parts sulphuric acid, and put +in a beaker standing in cold water; then add 15 to 20 c.c. of benzene, +drop by drop, waiting between each addition for the completion of the +reaction, and shake well during the operation. When finished, pour +contents of beaker into about a litre of cold water; the nitro-benzol will +sink to the bottom. Decant the water, and wash the nitro-benzol two or +three times in a separating funnel with water. Finally, dry the product by +adding a little granulated calcium chloride, and allowing to stand for +some little time, it may then be distilled. Nitro-benzene is a heavy oily +liquid which boils at 205° C., has a specific gravity of 1.2, and an odour +like that of oil of bitter almonds. In the arts it is chiefly used in the +preparation of aniline. + +~Di-nitro Benzene~ is a product of the further action of nitric acid on +benzene or nitro-benzene. It crystallises in long fine needles or thin +rhombic plates, and melts at 89.9° C. It can be made thus:--The acid +mixture used consists of equal parts of nitric and sulphuric acids, say 50 +c.c. of each, and without cooling add very slowly 10 c.c. of benzene from +a pipette. After the action is over, boil the mixture for a short time, +then pour into about half a litre of water, filter off the crystals thus +produced, press between layers of filter paper, and crystallise from +alcohol. Di-nitro-benzene, or meta-di-nitro-benzene, as it is sometimes +called, enters into the composition of several explosives, such as tonite +No. 3, roburite, securite, bellite. + +Nitro-benzene is manufactured upon the large scale as follows:--Along a +bench a row of glass flasks, containing 1 gallon each (1 to 2 lbs. +benzene), are placed, and the acids added in small portions at a time, the +workmen commencing with the first, and adding a small quantity to each in +turn, until the nitration was complete. This process was a dangerous one, +and is now obsolete. The first nitro-benzene made commercially in England, +by Messrs Simpson, Maule, and Nicholson, of Kennington, in 1856, was by +this process. Now, however, vertical iron cylinders, made of cast-iron, +are used for the nitrating operation. They are about 4 feet in diameter +and 4 feet deep, and a series are generally arranged in a row, at a +convenient height from the ground, beneath a line of shafting. Each +cylinder is covered with a cast-iron lid having a raised rim all round. A +central orifice gives passage to a vertical shaft, and two or more other +conveniently arranged openings allow the benzene and the mixed acids to +flow in. Each of these openings is surrounded with a deep rim, so that the +whole top of the cylinder can be flooded with water some inches in depth, +without any of it running into the interior of the nitrator. The lid +overhangs the cylinder somewhat, and in the outer rim a number of shot- +holes or tubes allow the water to flow down all over the outside of the +cylinder into a shallow cast-iron dish, in which it stands. By means of a +good supply of cold water, the top, sides, and bottom of the whole +apparatus is thus cooled and continually flooded. The agitator consists of +cast-iron arms keyed to a vertical shaft, with fixed arms or dash-plates +secured to the sides of the cylinder. The shaft has a mitre wheel keyed on +the top, which works into a corresponding wheel on the horizontal shafting +running along the top of the converters. This latter is secured to a +clutch; and there is a feather on the shaft, so that any one of the +converters can if necessary be put either in or out of gear. This +arrangement is necessary, as riggers or belts of leather, cotton, or +indiarubber will not stand the atmosphere of the nitro-benzole house. +Above and close to each nitrator stands its acid store tank, of iron or +stoneware. + +The building in which the nitration is carried out should consist of one +story, have a light roof, walls of hard brick, and a concrete floor of 9 +to 12 inches thick, and covered with pitch, to protect its surface from +the action of the acids. The floor should be inclined to a drain, to save +any nitro-benzol spilt. Fire hydrants should be placed at convenient +places, and it should be possible to at once fill the building with steam. +A 2-inch pipe, with a cock outside the building, is advisable. The +building should also be as far as possible isolated. + +The acids are mixed beforehand, and allowed to cool before use. The nitric +acid used has a specific gravity of 1.388, and should be as free as +possible from the lower oxides of nitrogen. The sulphuric acid has a +specific gravity of 1.845, and contains from 95 to 96 per cent. of mono- +hydrate. A good mixture is 100 parts of nitric to 140 parts of sulphuric +acid, and 78 parts of benzene; or 128 parts HNO_{3}, 179 of H_{2}SO_{4}, +and 100 of benzene (C_{6}H_{6}). The benzene having been introduced into +the cylinder, the water is turned on and the apparatus cooled, the +agitators are set running, and the acid cock turned on so as to allow it +to flow in a very thin stream into the nitrator. + +Should it be necessary to check the machinery even for a moment, the +stream of acid must be stopped and the agitation continued for some time, +as the action proceeds with such vigour that if the benzene being nitrated +comes to rest and acid continues to flow, local heating occurs, and the +mixture may inflame. Accidents from this cause have been not infrequent. +The operation requires between eight to ten hours, agitation and cooling +being kept up all the time. When all the acid is added the water is shut +off, and the temperature allowed to rise a little, to about 100° C. When +it ceases to rise the agitators are thrown out of gear, and the mixture +allowed some hours to cool and settle. The acid is then drawn off, and the +nitro-benzene is well washed with water, and sometimes distilled with wet +steam, to recover a little unconverted benzene and a trace of paraffin +(about .5 per cent. together). At many English works, 100 to 200 gallons, +or 800 to 1,760 lbs., are nitrated at a time, and toluene is often used +instead of benzene, especially if the nitro-benzene is for use as essence +of myrbane. The waste acids, specific gravity 1.6 to 1.7, contain a little +nitro-benzene in solution and some oxalic acid. They are concentrated in +cast-iron pots and used over again. + +~Di-nitro Benzene~ is obtained by treating a charge of the hydrocarbon +benzene with double the quantity of mixed acids in two operations, or +rather in two stages, the second lot of acid being run in directly after +the first. The cooling water is then shut off, and the temperature allowed +to rise rapidly, or nitro-benzene already manufactured is taken and again +nitrated with acids. A large quantity of acid fumes come off, and some of +the nitro- and di-nitro-benzol produced comes off at the high temperature +which is attained, and a good condensing apparatus of stoneware must be +used to prevent loss. The product is separated from the acids, washed with +cold water and then with hot. It is slightly soluble in water, so that the +washing waters must be kept and used over again. Finally it is allowed to +settle, and run while still warm into iron trays, in which it solidifies +in masses 2 or 4 inches thick. It should not contain any nitro-benzol, nor +soil a piece of paper when laid on it, should be well crystallised, fairly +hard, and almost odourless. The chief product is meta-di-nitro-benzene, +melting point 89.8, but ortho-di-nitro-benzene, melting point 118°, and +para-di-nitro, melting point 172°, are also produced. The melting point of +the commercial product is between 85° to 87° C. + +Di-nitro-toluene is made in a similar manner. The tri-nitro-benzene can +only be made by using a very large excess of the mixed acids. Nitro- +benzene, when reduced with iron, zinc, or tin, and hydrochloric acids, +forms aniline. + +~Roburite.~--This explosive is the invention of a German chemist, Dr Carl +Roth (English patent 267A, 1887), and is now manufactured in England, at +Gathurst, near Wigan. It consists of two component parts, non-explosive in +themselves (Sprengel's principle), but which, when mixed, form a powerful +explosive. The two substances are ammonium nitrate and chlorinated +di-nitro-benzol. Nitro-naphthalene is also used. Nitrate of soda and +sulphate of ammonium are allowed to be mixed with it. The advantages +claimed for the introduction of chlorine into the nitro compound are that +chlorine exerts a loosening effect upon the NO_{2} groups, and enables the +compound to burn more rapidly than when the nitro groups alone are present. + +The formula of chloro-di-nitro-benzol is C_{6}H_{3}Cl(NO_{2})_{2}. The +theoretical percentage of nitrogen, therefore, is 13.82, and of chlorine +17.53. Dr Roth states that, from experiments he has made, the dynamic +effect is considerably increased by the introduction of chlorine into the +nitro compound. Roburite burns quickly, and is not sensitive to shock; it +must be used dry; it cannot be made to explode by concussion, pressure, +friction, fire, or lightning; it does not freeze; it does not give off +deleterious fumes, and it is to all intents and purposes flameless; and +when properly tamped and fired by electricity, can be safely used in fiery +mines, neither fine dust nor gases being ignited by it. The action is +rending and not pulverising. Compared to gunpowder, it is more powerful in +a ratio ranging from 2-1/2 to 4 to 1, according to the substance acted +upon. It is largely used in blasting, pit sinking, quarrying, &c., but +especially in coal mining. According to Dr Roth, the following is the +equation of its decomposition:-- + +C_{6}H_{3}Cl(NO_{2})_{2} + 9HN_{4}NO_{3} = 6CO_{2} + 20N + HCl. + +In appearance roburite is a brownish yellow powder, with the +characteristic smell of nitro-benzol. Its specific gravity is 1.40. The +Company's statement that the fumes of roburite were harmless having been +questioned by the miners of the Garswood Coal and Iron Works Colliery, a +scientific committee was appointed by the management and the men jointly +for the purpose of settling the question. The members of this committee +were Dr N. Hannah, Dr D.J. Mouncey, and Professor H.B. Dixon, F.R.S., of +Owens College. After a protracted investigation, a long and technical +report was issued, completely vindicating the innocuousness of roburite +when properly used. In the words of _The Iron and Coal Trades' Review_ +(May 24, 1889), "The verdict, though not on every point in favour of the +use in all circumstances of roburite in coal mines, is yet of so +pronounced a character in its favour as an explosive that it is impossible +to resist the conclusion that the claims put forward on its behalf rest on +solid grounds." + +Roburite was also one of the explosives investigated by the committee +appointed in September 1889 by the Durham Coalowners' and Miners' +Associations, for the purpose of determining whether the fumes produced by +certain explosives are injurious to health. Both owners and workmen were +represented on the committee, which elected Mr T. Bell, H.M. Inspector of +Mines, as its chairman, with Professor P.P. Bedson and Drs Drummond and +Hume as professional advisers. The problem considered was whether the +fumes produced by the combustion of certain explosives, one of which was +roburite, were injurious to health. The trial comprised the chemical +analysis of the air at the "intake," and of the vitiated air during the +firing of the shots at the "return," and also of the smoky air in the +vicinity of the shot-holes. Five pounds and a half of roburite were used +in twenty-three shots. It had been asserted that the fumes from this +explosive contained carbon-monoxide, CO, but no trace of this gas could be +discovered after the explosion. On another occasion, however, when 4.7 +lbs. of roburite were exploded in twenty-three shots, the air at the +"return" showed traces of CO gas to the extent of .042 to .019 per cent. +The medical report which Drs Hume and Drummond presented to the committee +shows that they investigated every case of suspected illness produced by +exposure to fumes, and they could find no evidence of acute illness being +caused. They say, "No case of acute illness has, throughout the inquiry, +been brought to our knowledge, and we are led to the conclusion that such +cases have not occurred." + +~Manufacture.~--As now made, roburite is a mixture of ammonium nitrate and +chlorinated di-nitro-benzol. The nitrate of ammonia is first dried and +ground, and then heated in a closed steam-jacketed vessel to a temperature +of 80° C., and the melted organic compound is added, and the whole stirred +until an intimate mixture is obtained. On cooling, the yellow powder is +ready for use, and is stored in straight canisters or made up into +cartridges. Owing to the deliquescent nature of the nitrate of ammonia, +the finished explosive must be kept out of contact with the air, and for +this reason the cartridges are waterproofed by dipping them in melted wax. +Roburite is made in Germany, at Witten, Westphalia; and also at the +English Company's extensive works at Gathurst, near Wigan, which have been +at work now for some eighteen years, having started in 1888. These works +are of considerable extent, covering 30 acres of ground, and are equal to +an output of 10 tons a day. A canal runs through the centre, separating +the chemical from the explosive portions of the works, and the Lancashire +and Yorkshire Railway runs up to the doors. Besides sending large +quantities of roburite itself abroad, the Company also export to the +various colonies the two components, as manufactured in the chemical +works, and which separately are quite non-explosive, and which, having +arrived at their destination, can be easily mixed in the proper +proportions. + +Among the special advantages claimed for roburite are:--First, that it is +impossible to explode a cartridge by percussion, fire, or electric sparks. +If a cartridge or layer be struck with a heavy hammer, the portion struck +is decomposed, owing to the large amount of heat developed by the blow. +The remaining explosive is not in the least affected, and no detonation +whatever takes place. If roburite be mixed with gunpowder, and the +gunpowder fired, the explosion simply scatters the roburite without +affecting it in the least. In fact, the only way to explode roburite is to +detonate it by means of a cap of fulminate, containing at least 1 gramme +of fulminate of mercury. Secondly, its great safety for use in coal mines. +Roburite has the great advantage of exploding by detonation at a very low +temperature, indeed so low that a very slight amount of tamping is +required when fired in the most explosive mixture of air and coal gas +possible, and not at all in a mixture of air and coal dust--a condition in +which the use of gunpowder is highly dangerous. + +Mr W.J. Orsman, F.I.C., in a paper read at the University College, +Nottingham, in 1893, gives the temperature of detonation of roburite as +below 2,100° C., and of ammonium nitrate as 1,130° C., whereas that of +blasting gelatine is as much as 3,220° C. With regard to the composition +of the fumes formed by the explosion of roburite, Mr Orsman says: "With +certain safety explosives--roburite, for instance--an excess of the +oxidising material is added, namely, nitrate of ammonia; but in this case +the excess of oxygen here causes a diminution of temperature, as the +nitrate of ammonia on being decomposed absorbs heat. This excess of oxygen +effectually prevents the formation of carbon monoxide (CO) and the oxides +of nitrogen." + +The following table (A), also from Mr Orsman's paper, gives the +composition of five prominent explosives, and shows the composition of the +gases formed on explosion. The gases were collected after detonating 10 +grms. of each in a closed strong steel cylinder, having an internal +diameter of 5 inches. + +With respect to the influence of ammonium nitrate in lowering the +temperature of explosion of the various substances to which it is added, +it was found by a French Commission that, when dry and finely powdered, +ammonium nitrate succeeds in depreciating the heat of decomposition +without reducing the power of the explosive below a useful limit. The +following table (B) shows the composition of the explosives examined, and +the temperatures which accompanied their explosion. + + A + ______________________________________________________________________ +| | | | +| | | Composition of Gases. | +| |Volume |__________________________| +| Explosive. |of Gas | | | | | +| |formed.|CO_{2}.| CO. |CH_{4}| N. | +| | | | | &H. | | +|___________________________________|_______|_______|_____|______|_____| +| | | | | | | +| | | Per | Per | Per | Per | +| | c.c. | cent. |cent.|cent. |cent.| +|Gunpowder-- | | | | | | +| Nitre 75 parts | | | | | | +| Sulphur 10 '' | 2,214 | 51.3 | 3.5| 3.5 | 41.7| +| Charcoal 15 '' | | | | | | +|Gelignite-- | | | | | | +| Nitro-glycerine 56.5 parts | | | | | | +| Nitro-cotton 3.5 '' | 4,980 | 25 | 7 | ... | 67 | +| Wood-meal 8.0 '' | | | | | | +| KNO_{3} 32.0 '' | | | | | | +|Tonite-- | | | | | | +| Nitro-Cotton | 3,750 | 30 | 8 | ... | 62 | +| Barium nitrate | | | | | | +|Roburite-- | | | | | | +| Ammonium nitrate, 86 parts | | | | | | +| Di-nitro-chloro-benzol 14 '' | 4,780 | 32 | ... | ... | 68 | +|Carbonite | | | | | | +| Nitro-glycerine 25 parts | | | | | | +| Wood-meal 40 '' | 2,100 | 19 | 15 | 26 | ... | +| Potas. nitrate 34 '' | | | | | | +|___________________________________|_______|_______|_____|______|_____| + + B + ____________________________________________________________________ +| | | | | +| | Original | Percentage | Final | +| Explosive. | Temperature |NH_{4}.NO_{3}| Temperature | +| |Co-efficient.| added. |Co-efficient.| +|__________________________|_____________|_____________|_____________| +| | | | | +|Nitro-glycerine | 3,200 | ... | ... | +|Blasting gelatine | | | | +| (8 per cent. gun-cotton)| 3,090 | 88 | 1,493 | +|Dynamite | | | | +| (25 per cent. silica)| 2,940 | 80 | 1,468 | +| | | | | +|Gun-cotton, 1 | 2,650 | ... | ... | +| | 2,060 | 90.5 | 1,450 | +| | | | | +|Ammonium nitrate | 1,130 | ... | ... | +|__________________________|_____________|_____________|_____________| + +~Bellite~ is the patent of Mr Carl Lamm, Managing Director of the Rötebro +Explosive Company, of Stockholm, and is licensed for manufacture in +England. It consists of a mixture of nitrate of ammonia with di- or +tri-nitro-benzol, it has a specific gravity of 1.2 to 1.4 in its granulated +state, and 1 litre weighs 800 to 875 grms. Heated in an open vessel, +bellite loses its consistency at 90° C., but does not commence to separate +before a temperature of 200° C. is reached, when it evaporates without +exploding. If heated suddenly, it burns with a sooty flame, somewhat like +tar, but if the source of heat is removed, it will cease burning, and +assume a caramel-like structure. It absorbs very little moisture from the +air after it has been pressed, and if the operation has been performed +while the explosive is hot, the subsequent increase of weight is only 2 +per cent. When subjected to the most powerful blow with a steel hammer +upon an iron plate, it neither explodes nor ignites. A rifle bullet fired +into it at 50 yards' distance will not explode it. Granulated bellite +explodes fully by the aid of fulminating mercury. Fifteen grms. of bellite +fired by means of fulminate, projected a shot from an ordinary mortar, +weighing 90 lbs., a distance of 75 yards, 15 grms. of gunpowder, under the +same conditions, throwing it only 12 yards. A weight of 7-1/2 lbs. falling +145 centimetres failed to explode 1 grm. of bellite. + +Various experiments and trials have been made with this explosive by +Professor P.T. Cleve, M.P.F. Chalon, C.N. Hake, and by a committee of +officers of the Swedish Royal Artillery. It is claimed that it is a very +powerful and extremely safe explosive; that it cannot be made to explode +by friction, shock, or pressure, nor by electricity, fire, lightning, &c., +and that it is specially adapted for use in coal mines, &c.; that it can +only be exploded by means of a fulminate detonator, and is perfectly safe +to handle and manufacture; that it does not freeze, can be used as a +filling for shells, and lastly, can be cheaply manufactured. + +~Securite~ consists of 26 parts of meta-di-nitro-benzol and 74 parts of +ammonium nitrate. It is a yellow powder, with an odour of nitro-benzol. It +was licensed in 1886. It sometimes contains tri-nitro-benzol, and +tri-nitro-naphthalene. The equation of its combustion is given as + +C_{6}H_{4}(NO_{2})_{2} + 10(NH_{4}NO_{3}) = 6CO_{2} + 22H_{2}O + 11N_{2} + +and, like bellite and roburite, it is claimed to be perfectly safe to use +in the presence of fire damp and coal dust.[A] The variety known as +Flameless Securite consists of a mixture of nitrate and oxalate of ammonia +and di-nitro-benzol. + +[Footnote A: See paper by S.B. Coxon, _North of Eng. Inst. Mining and +Mech. Eng._, 11, 2, 87.] + +~Kinetite.~--A few years ago an explosive called "Kinetite"[A] was +introduced, but is not manufactured in England. It was the patent of +Messrs Petry and Fallenstein, and consisted of nitro-benzol, thickened or +gelatinised by the addition of some collodion-cotton, incorporated with +finely ground chlorate of potash and precipitated sulphide of antimony. An +analysis gave the following percentages:-- + +Nitro-benzol, 19.4 per cent. +Chlorate of potash, 76.9 per cent. +Sulphide of antimony nitro-cotton, 3.7 per cent. + +[Footnote A: V. Watson Smith, _Jour. Soc. Chem. Ind._, January 1887.] + +It requires a very high temperature to ignite it, and cannot, under +ordinary circumstances, when unconfined, be exploded by the application of +heat. It is little affected by immersion in water, unless prolonged, when +the chlorate dissolves out, leaving a practical inexplosive residue.[A] It +was found to be very sensitive to combined friction and percussion, and to +be readily ignited by a glancing blow of wood upon wood. It was also +deficient in chemical stability, and has been known to ignite +spontaneously both in the laboratory and in a magazine. It is an orange- +coloured plastic mass, and smells of nitro-benzol. + +[Footnote A: Col. Cundill, R.A., "Dict. of Explosives," says: "If, +however, it be exposed to moist and dry air alternately, the chlorate +crystallises out on the surfaces, and renders the explosive very +sensitive."] + +~Tonite No. 3~ contains 10 to 14 per cent. of nitro-benzol (see Tonite). +Trench's Flameless Explosive contains 10 per cent. of di-nitro-benzol, +together with 85 per cent. of nitrate of ammonia, and 5 per cent. of a +mixture of alum, and the chlorides of sodium and ammonia. + +~Tri-nitro-Toluene.~--Toluene, C_{7}H_{8}, now chiefly obtained from coal- +tar, was formerly obtained by the dry distillation of tolu-balsam. It may +be regarded as methyl-benzene, or benzene in which one hydrogen is +replaced by methyl (CH_{3}), thus (C_{6}H_{5}CH_{3}), or as phenyl- +methane, or methane in which one hydrogen atom is replaced by the radical +phenyl (C_{6}H_{5}), thus (CH_{3}C_{6}H_{5}). Toluene is a colourless +liquid, boiling at 110° C., has a specific gravity of .8824 at 0° C., and +an aromatic odour. Tri-nitro-toluene is formed by the action of nitric +acid on toluene. According to Häussermann, it is more advantageous to +start with the ortho-para-di-nitro-toluene, which is prepared by allowing +a mixture of 75 parts of 91 to 92 per cent. nitric acid and 150 parts of +95 to 96 per cent. sulphuric acid to run in a thin stream into 100 parts +of para-nitro-toluene, while the latter is kept at a temperature between +60° to 65° C., and continually stirred. When the acid has all been run in, +this mixture is heated for half an hour to 80° C., and allowed to stand +till cold. The excess of nitric acid is then removed. The residue after +this treatment is a homogeneous crystalline mass of ortho-para-di-nitro- +toluene, of which the solidifying point is 69.5° C. To convert this mass +into tri-nitro derivative, it is dissolved by gently heating it with four +times its weight of sulphuric acid (95 to 96 per cent.), and it is then +mixed with 1-1/2 times its weight of nitric acid (90 to 92 per cent.), the +mixture being kept cool. Afterwards it is digested at 90° to 95° C., with +occasional stirring, until the evolution of gas ceases. This takes place +in about four or five hours. + +The operation is now stopped, the product allowed to cool, and the excess +of nitric acid separated from it. The residue is then washed with hot +water and very dilute soda solution, and allowed to solidify without +purification. The solidifying point is 70° C., and the mass is then white, +with a radiating crystalline structure. Bright sparkling crystals, melting +at 81.5° C. may, however, be obtained by recrystallisation from hot +alcohol. The yield is from 100 parts di-nitro-toluene, 150 parts of the +tri-nitro derivative. Häussermann states also that 1:2:4:6 tri-nitro- +toluene can be obtained from ordinary commercial di-nitro-toluene melting +at 60° to 64° C.; but when this is used, greater precautions must be +exercised, for the reactions are more violent. Moreover, 10 per cent. more +nitric acid is required, and the yield is 10 per cent. less. He also draws +attention to the slight solubility of tri-nitro-toluene in hot water, and +to the fact that it is decomposed by dilute alkalies and alkaline +carbonates--facts which must be borne in mind in washing the substance. +This material is neither difficult nor dangerous to make. It behaves as a +very stable substance when exposed to the air under varying conditions of +temperature (-10° to +50° C.) for several months. It cannot be exploded by +flame, nor by heating it in an open vessel. It is only slightly decomposed +by strong percussion on an anvil. A fulminate detonator produces the best +explosive effect with tri-nitro-toluene. It can be used in conjunction +with ammonium nitrate, but such admixture weakens the explosive power; but +even then it is stated to be stronger than an equivalent mixture of +di-nitro-benzene and ammonium nitrate. Mowbray patented a mixture of 3 +parts nitro-toluol to 7 of nitro-glycerine, also in the proportions of 1 to +3, which he states to be a very safe explosive. + +~Faversham Powder.~--One of the explosives on the permitted list (coal +mines) is extensively used, and is manufactured by the Cotton Powder Co. +Ltd. at Faversham. It is composed of tri-nitro-toluol 11 parts, ammonium +nitrate 93 parts, and moisture 1 part. This explosive must be used only +when contained in a case of an alloy of lead, tin, zinc, and antimony +thoroughly waterproof; it must be used only with a detonator or electric +detonator of not less strength than that known as No. 6. + +~Nitro-Naphthalene.~--Nitro-naphthalene is formed by the action of nitric +acid on naphthalene (C_{10}H_{8}). Its formula is C_{10}H_{7}NO_{2}, and +it forms yellow needles, melting at 61° C.; and of di-nitro-naphthalene +(C_{10}H_{6}(NO_{2})_{2}), melting point 216° C. There are also tri-nitro +and tetra-nitro and [alpha] and [beta] derivatives of nitro-naphthalene. +It is the di-nitro-naphthalene that is chiefly used in explosives. It is +contained in roburite, securite, romit, Volney's powder, &c. Fehven has +patented an explosive consisting of 10 parts of nitro-naphthalene mixed +with the crude ingredients of gunpowder as follows:--Nitro-naphthalene, 10 +parts; saltpetre, 75 parts; charcoal, 12.5 parts; and sulphur, 12.5 parts. +He states that he obtains a mono-nitro-naphthalene, containing a small +proportion of di-nitro-naphthalene, by digesting 1 part of naphthalene, +with or without heat, in 4 parts of nitric acid (specific gravity 1.40) +for five days. + +Quite lately a patent has been taken out for a mixture of nitro- +naphthalene or di-nitro-benzene with ammonium nitrate, and consists in +using a solvent for one or other or both of the ingredients, effected in a +wet state, and then evaporating off the solvent, care being taken not to +melt the hydrocarbon. In this way a more intimate mixture is ensured +between the particles of the components, and the explosive thus prepared +can be fired by a small detonator, viz., by 0.54 grms. of fulminate. +Favier's explosive also contains mono-nitro-naphthalene (8.5 parts), +together with 91.5 parts of nitrate of ammonia. This explosive is made in +England by the Miners' Safety Explosive Co. A variety of roburite contains +chloro-nitro-naphthalene. Romit consists of 100 parts ammonium nitrate and +7 parts potassium chlorate mixed with a solution of 1 part nitro- +naphthalene and 2 parts rectified paraffin oil. + +~Ammonite.~--This explosive was originally made at Vilvorde in Belgium, +under the title of the Favier Explosive, consisting of a compressed hollow +cylinder composed of 91.5 per cent. of nitrate of ammonia, and 8.5 per +cent. of mono-nitro-naphthalene filled inside with loose powder of the +same composition. The cartridges were wrapped in paper saturated with +paraffin-wax, and afterwards dipped in hot paraffin to secure their being +water-tight. The Miners' Safety Explosives Co., when making this explosive +at their factory at Stanford-le-Hope, Essex, abandoned after a short trial +the above composition, and substituted di-nitro-naphthalene 11.5 per cent. +for the mono-nitro-naphthalene, and used thin lead envelopes filled with +loose powder slightly pressed in, in place of the compressed cylinders +containing loose powder. The process of manufacture is shortly as +follows:--132-3/4 lbs. of thoroughly dried nitrate of ammonium is placed +in a mill pan, heated at the bottom with live steam, and ground for about +twenty minutes until it becomes so dry that a slight dust follows the +rollers; then 17-1/2 lbs. of thoroughly dry di-nitro-naphthalene is added, +and the grinding continued for about ten minutes. Cold water is then +circulated through the bottom of the pan until the material appears of a +lightish colour and falls to powder. (While the pan is hot the whole mass +looks slightly plastic and of a darker colour than when cold.) A slide in +the bottom of the pan is then withdrawn, the whole mass working out until +the pan is empty; it is now removed to the sifting machine, brushed +through a wire sieve of about 12 holes to the inch, and is then ready for +filling into cartridges. The hard core is returned from the sifting +machine and turned into one of the pans a few minutes before the charge is +withdrawn. + +The ammonite is filled into the metallic cartridges by means of an +archimedian screw working through a brass tube, pushing off the cartridges +as the explosive is fed into them against a slight back pressure; a cover +is screwed on, and they then go to the dipping room, where they are dipped +in hot wax to seal the ends; they are then packed in boxes of 5 lbs. each +and are ready for delivery. The di-nitro-naphthalene is made at the +factory. Mono-nitro-naphthalene is first made as follows:--12 parts of +commercial nitrate of soda are ground to a fine powder, and further ground +with the addition of 15 parts of refined naphthalene until thoroughly +incorporated; it is then placed in an earthenware pan, and 30 parts of +sulphuric acid of 66° B. added, 2 parts at a time, during forty-eight +hours (the rate of adding H_{2}SO_{4} depends on the condition of the +charge, and keeping it in a fluid state), with frequent agitation, day and +night, during the first three or four days, afterwards three or four times +a day. In all fourteen days are occupied in the nitration process. It is +then strained through an earthenware strainer, washed with warm water, +drained, and dried. For the purpose of producing this material in a +granulated condition, which is found more convenient for drying, and +further nitrification, it is placed in a tub, and live steam passed +through, until brought up to the boiling point (the tub should be about +half full), cold water is then run in whilst violently agitating the +contents until the naphthalene solidifies; it can then be easily drained +and dried. For the further treatment to make di-nitro-naphthalene, 18 +parts of nitro-naphthalene are placed in an earthenware pan, together with +39 parts of sulphuric acid of 66° B., then 15 parts of nitric acid of 40° +B. are added, in small quantities at a time, stirring the mixture +continually. This adding of nitric acid is controlled by the fuming, which +should be kept down as much as possible. The operation takes ten to twelve +days, when 100 times the above quantities, taken in kilogrammes, are +taken. At the end of the nitration the di-nitro-naphthalene is removed to +earthenware strainers, allowed to drain, washed with hot water and soda +until all acid is removed, washed with water and dried. The di-nitro- +naphthalene gives some trouble in washing, as some acid is held in the +crystals which is liable to make its appearance when crushed. To avoid +this it should be ground and washed with carbonate of soda before drying; +an excess of carbonate of soda should not, however, be used. + +~Electronite.~--This is a high explosive designed to afford safety in coal +getting. This important end has been attained by using such ingredients, +and so proportioning them, as will ensure on detonation a degree of heat +insufficient under the conditions of a "blown-out" shot, to ignite fire +damp or coal dust. It is of the nitrate of ammonium class of permitted +explosives. It contains about 75 per cent. of nitrate of ammonium, with +the addition of nitrate of barium, wood meal, and starch. The gases +resulting from detonation are chiefly water in the gaseous form, nitrogen, +and a little carbon dioxide. It is granulated with the object of +preventing missfires from ramming, to which nitrate of ammonium explosives +are somewhat susceptible. This explosive underwent some exhaustive +experiments at the experimental station near Wigan in 1895, when 8 oz. or +12 oz. charges were fired unstemmed into an admixture of coal dust and 10 +per cent. of gas, without any ignition taking place. It is manufactured by +Messrs Curtis's & Harvey Ltd. at their factory, Tonbridge, Kent. + +~Sprengel's Explosives.~--This is a large class of explosives. The +essential principle of them all is the admixture of an oxidising with a +combustible agent at the time of, or just before, being required for use, +the constituents of the mixture being very often non-explosive bodies. +This type of explosive is due to the late Dr Herman Sprengel, F.R.S. +Following up the idea that an explosion is a sudden combustion, he +submitted a variety of mixtures of oxidising and combustible agents to the +violent shock of a detonator of fulminate. These mixtures were made in +such proportions that the mutual oxidation or de-oxidation should be +theoretically complete. Among them are the following:-- + +1. One chemical equivalent of nitro-benzene to equivalents of nitric acid. + +2. Five equivalents of picric acid to 13 equivalents of nitric acid. + +3. Eighty-seven equivalents of nitro-naphthalene to 413 equivalents of +nitric acid. + +4. Porous cakes, or lumps of chlorate of potash, exploded violently with +bisulphide of carbon, nitro-benzol, carbonic acid, sulphur, benzene, and +mixtures of these substances. + +No. 1 covers the explosive known as _Hellhoffite_, and No. 2 is really +oxonite, and No. 4 resembles rack-a-rock, an explosive invented by Mr S.R. +Divine, and consisting of a mixture of chlorate of potash and nitro- +benzol. Roburite, bellite, and securite should perhaps be regarded as +belonging to the Sprengel class of explosives, otherwise this class is not +manufactured or used in England. The principal members are known as +_Hellhoffite_, consisting of a mixture of nitro-petroleum or nitro-tar +oils and nitric acid, or of meta-di-nitro-benzol and nitric acid; +_Oxonite_, consisting of picric and nitric acids; and _Panclastite_, a +name given to various mixtures, proposed by M. Turpin, such as liquid +nitric peroxide, with bisulphide of carbon, benzol, petroleum, ether, or +mineral oils. + +~Picric Acid, Tri-nitro-Phenol, or Carbazotic Acid.~--Picric acid, or a +tri-nitro-phenol (C_{6}H_{2}(NO_{2})_{3}OH)[2:4:6], is produced by the +action of nitric acid on many organic substances, such as phenol, indigo, +wool, aniline, resins, &c. At one time a yellow gum from Botany Bay +(_Xanthorrhoea hastilis_) was chiefly used. One part of phenol (carbolic +acid), C_{6}H_{5}OH, is added to 3 parts of strong fuming nitric acid, +slightly warmed, and when the violence of the reaction has subsided, +boiled till nitrous fumes are no longer evolved. The resinous mass thus +produced is boiled with water, the resulting picric acid is converted into +a sodium salt by a solution of sodium carbonate, which throws down sodium +picrate in crystals. + +Phenol-sulphuric acid is now, however, more generally used, and the +apparatus employed for producing it closely resembles that used in making +nitro-benzol. It is also made commercially by melting carbolic acid, and +mixing it with strong sulphuric acid, then diluting the "sulpho- +carbolic"[A] acid with water, and afterwards running it slowly into a +stone tank containing nitric acid. This is allowed to cool, where the +crude picric acid crystallises out, and the acid liquid (which contains +practically no picric acid, but only sulphuric acid, with some nitric +acid) being poured down the drains. The crude picric acid is then +dissolved in water by the aid of steam, and allowed to cool when most of +the picric acid recrystallises. The mother liquor is transferred to a tank +and treated with sulphuric acid, when a further crop of picric acid +crystals is obtained. The crystals of picric acid are further purified by +recrystallisation, drained, and dried at 100° F. on glazed earthenware +trays by the aid of steam. It can also be obtained by the action of nitric +acid on ortho-nitro-phenol, para-nitro-phenol, and di-nitro-phenol (2:4 +and 2:6), but not from meta-nitro-phenol, a fact which indicates its +constitution.[B] + +[Footnote A: O. and p. phenolsulphonic acids. + +C_{3}H_{4}(OH).SO_{3}H + 3HNO_{3} = C_{6}H_{2}(NO_{2})_{3}OH + H_{2}SO_{4} ++ 2H_{2}O. (Picric acid).] + +[Footnote B: Carey Lea, _Amer. Jour. Sci._, (ii.), xxxii. 180.] + +Picric acid crystallises in yellow shining prisms or laminæ having an +intensely bitter taste, and is poisonous. It melts at 122.5° C., sublimes +when cautiously heated, dissolves sparingly in cold water, more easily in +hot water, still more in alcohol. It stains the skin an intense yellow +colour, and is used as a dye for wool and silk. It is a strong acid, +forming well crystallised yellow salts, which detonate violently when +heated, some of them also by percussion. The potassium salt, +C_{6}H_{2}(NO_{2})_{3}OK, crystallises in long needles very slightly +soluble in water. The sodium, ammonium, and barium salts are, however, +easily soluble in water. Picric acid, when heated, burns with a luminous +and smoky flame, and may be burnt away in large quantity without +explosion; but the mere contact of certain metallic oxides, with picric +acid, in the presence of heat, develops powerful explosives, which are +capable of acting as detonators to an indefinite amount of the acid, wet +or dry, which is within reach of their detonative influence. The formula +of picric acid is + +C_{6}H_{2}|(NO_{2})_{3} + |OH. + +which shows its formation from phenol (C_{6}H_{5}OH.), three hydrogen +atoms being displaced by the NO_{2} group. The equation of its formation +from phenol is as follows:-- + +C_{6}H_{5}.OH + 3HNO_{3} = C_{6}H_{2}(NO_{2})_{3}OH + 3H_{2}O. + +According to Berthelot, its heat of formation from its elements equals +49.1 calories, and its heat of total combustion by free oxygen is equal to ++618.4 cals. It hardly contains more than half the oxygen necessary for +its complete combustion. + +2C_{6}H_{2}(NO_{2})_{3}OH + O_{10} = 12CO_{2} + 3H_{2} + 3N_{2}. + +The percentage composition of picric acid is--Nitrogen, 18.34; oxygen, +49.22; hydrogen, 1.00; and carbon, 31.44, equal to 60.26 per cent. of +NO_{2}. The products of decomposition are carbonic acid, carbonic oxide, +carbon, hydrogen, and nitrogen, and the heat liberated, according to +Berthelot, would be 130.6 cals., or 570 cals. per kilogramme. The reduced +volume of the gases would be 190 litres per equivalent, or 829 litres per +kilogramme. To obtain a total combustion of picric acid it is necessary +to mix with it an oxidising agent, such as a nitrate, chlorate, &c. It has +been proposed to mix picric acid (10 parts) with sodium nitrate (10 parts) +and potassium bichromate (8.3 parts). These proportions would furnish a +third of oxygen in excess of the necessary proportion. + +Picric acid was not considered to be an explosive, properly so called, for +a long time after its discovery, but the disastrous accident which +occurred at Manchester (_vide_ Gov. Rep. No. LXXXI., by Colonel (now Sir +V.D.) Majendie, C.B.), and some experiments made by Dr Duprè and Colonel +Majendie to ascertain the cause of the accident, conclusively proved that +this view was wrong. The experiments of Berthelot (_Bull. de la Soc. Chim. +de Paris_, xlix., p. 456) on the explosive decomposition of picric acid +are also deserving of attention in this connection. If a small quantity of +picric acid be heated in a moderate fire, in a crucible, or even in an +open test tube, it will melt (at 120° C. commercial acid), then give off +vapours which catch fire upon contact with air, and burn with a sooty +flame, without exploding. If the burning liquid be poured out upon a cold +slab, it will soon go out. A small quantity carefully heated in a tube, +closed at one end, can even be completely volatilised without apparent +decomposition. It is thus obvious that picric acid is much less explosive +than the nitric ethers, such as nitro-glycerol and nitro-cellulose, and +very considerably less explosive than the nitrogen compounds and +fulminates. + +It would, however, be quite erroneous to assume that picric acid cannot +explode when simply heated. On the contrary, Berthelot has proved that +this is not the case. If a glass tube be heated to redness, and a minute +quantity of picric acid crystals be then thrown in, it will explode with a +curious characteristic noise. If the quantity be increased so that the +temperature of the tube is materially reduced, no explosion will take +place at once, but the substance will volatilise and then explode, though +with much less violence than before, in the upper part of the tube. +Finally, if the amount of picric acid be still further increased under +these conditions, it will undergo partial decomposition and volatilise, +but will not even deflagrate. Nitro-benzene, di-nitrobenzene, and mono-, +di-, and tri-nitro-naphthalenes behave similarly. + +The manner in which picric acid will decompose is thus dependent upon the +initial temperature of the decomposition, and if the surrounding material +absorb heat as fast as it is produced by the decomposition, there will be +no explosion and no deflagration. If, however, the absorption is not +sufficient to prevent deflagration, this may so increase the temperature +of the surrounding materials that the deflagration will then end in +explosion. Thus, if an explosion were started in an isolated spot, it +would extend throughout the mass, and give rise to a general explosion. + +In the manufacture of picric acid the first obvious and most necessary +precaution is to isolate the substance from other chemicals with which it +might accidentally come into contact. If pure materials only are used, the +manufacture presents no danger. The finished material, however, must be +carefully kept from contact with nitrates, chlorates, or oxides. If only a +little bit of lime or plaster become accidentally mixed with it, it may +become highly dangerous. A local explosion may occur which might have the +effect of causing the explosion of the whole mass. Picric acid can be +fired by a detonator, 5-grain fulminate, and M. Turpin patented the use of +picric acid, unmixed with any other substance, in 1885. The detonation of +a small quantity of dry picric acid is sufficient to detonate a much +larger quantity containing as much as 17 per cent. of water. + +It is chiefly due to French chemists (and to Dr Sprengel) that picric acid +has come to the front as an explosive. Melinite,[A] a substance used by +the French Government for filling shells, was due to M. Turpin, and is +supposed to be little else than fused picric acid mixed with gun-cotton +dissolved in some solvent (acetone or ether-alcohol). Sir F.A. Abel has +also proposed to use picric acid, mixed with nitrate of potash (3 parts) +and picrate of ammonia (2 parts) as a filling for shells. This substance +requires a violent blow and strong confinement to explode it. I am not +aware, however, that it has ever been officially adopted in this country. +Messrs Désignolles and Brugère have introduced military powders, +consisting of mixtures of potassium and ammonium picrates with nitrate of +potassium. M. Désignolles introduced three kinds of picrate powders, +composed as follows:-- + + ___________________________________________________________________ +| | | | | +| | For Torpedoes | For Guns. | For Small | +| | and Shells. | Ordinary. Heavy. | Arms. | +|___________________|_______________|___________________|___________| +| | | | | | +| Picrate of Potash | 55-50 | 16.4- 9.6 | 9 | 28.6-22.9 | +| Saltpetre | 45-50 | 74.4-79.7 | 80 | 65.0-69.4 | +| Charcoal | ... | 9.2-10.7 | 11 | 6.4- 7.7 | +|___________________|_______________|___________|_______|___________| + +They were made much like ordinary gunpowder, 6 to 14 per cent. of moisture +being added when being milled. The advantages claimed over gunpowder are +greater strength, and consequently greater ballistic or disruptive effect, +comparative absence of smoke, and freedom from injurious action on the +bores of guns, owing to the absence of sulphur. Brugère's powder is +composed of ammonium picrate and nitre, the proportions being 54 per cent. +picrate of ammonia and 46 per cent. potassic nitrate. It is stable, safe +to manufacture and handle, but expensive. It gives good results in the +Chassepôt rifle, very little smoke, and its residue is small, and consists +of carbonate of potash. It is stated that 2.6 grms. used in a rifle gave +an effect equal to 5.5 grms. of ordinary gunpowder. + +[Footnote A: The British Lydite and the Japanese Shimose are said to be +identical with Melinite.] + +Turpin has patented various mixtures of picric acid, with gum-arabic, +oils, fats, collodion jelly, &c. When the last-named substance is diluted +in the proportion of from 3 to 5 per cent. in a mixture of ether and +alcohol, he states that the blocks of picric acid moulded with it will +explode in a closed chamber with a priming of from 1 to 3 grammes of +fulminate. He also casts picric acid into projectiles, the cast acid +having a density of about 1.6. In this state it resists the shock produced +by the firing of a cannon, when contained in a projectile, having an +initial velocity of 600 metres. It is made in the following way:--The acid +is fused in a vessel provided with a false bottom, heated to 130° to 145° +C. by a current of steam under pressure, or simply by the circulation +under the false bottom of a liquid, such as oil, chloride of zinc, +glycerine, &c., heated to the same temperature. The melted picric acid is +run into moulds of a form corresponding to that of the blocks required, or +it may be run into projectiles, which should be heated to a temperature of +about 100° C., in order to prevent too rapid solidification. + +When cresylic acid (or cresol, C_{6}H_{4}(CH_{3})OH.) is acted upon by +nitric acid it produces a series of nitro compounds very similar to those +formed by nitric acids on phenol, such as sodium di-nitro-cresylate, known +in the arts as victoria yellow. Naphthol, a phenol-like body obtained from +naphthalene, under the same conditions, produces sodium di-nitro- +naphthalic acid, C_{10}H_{6}(NO_{2})_{2}O. The explosive known as +"roburite" contains chloro-nitro-naphthalene, and romit, a Swedish +explosive, nitro-naphthalene. + +~Tri-nitro-cresol~, C_{7}H_{4}(NO_{2})_{3}OH.--A body very similar to tri- +nitro-phenol, crystallises in yellow needles, slightly soluble in cold +water, rather more so in boiling water, alcohol, and ether. It melts at +about 100° C. In France it is known as "Cresilite," and mixed with +melinite, is used for charging shells. By neutralising a boiling saturated +solution of tri-nitro-cresol with ammonia, a double salt of ammonium and +nitro-cresol crystallises out upon cooling, which is similar to ammonium +picrate. This salt is known as "Ecrasite," and has been used in Austria +for charging shells. It is a bright yellow solid, greasy to the touch, +melts at 100° C., is unaffected by moisture, heat, or cold, ignites when +brought into contact with an incandescent body or open flame, burning +harmlessly away unless strongly confined, and is insensitive to friction +or concussion. It is claimed to possess double the strength of dynamite, +and requires a special detonator (not less than 2 grms. of fulminate) to +provoke its full force. Notwithstanding the excellent properties +attributed to this explosive, Lieut. W. Walke ("Lectures on Explosives," +p. 181) says, "Several imperfectly explained and unexpected explosions +have occurred in loading shells with this substance, and have prevented +its general adoption up to the present time." + +~The Fulminates.~--The fulminates are salts of fulminic acid, +C_{2}N_{2}O_{2}H_{2}. Their constitution is not very well understood. Dr +E. Divers, F.R.S., and Mr Kawakita (_Chem. Soc. Jour._, 1884, pp. 13-19), +give the formulæ of mercury and silver fulminates as + + OC = N AgOC = N + / | \ | \ +Hg | O and | O + \ | / | / + -C = N AgC = N + +whereas Dr H.E. Armstrong, F.R.S., would prefer to write the formula of +fulminic acid + +ON.C.OH. + | + C(N.OH), + +and A.F. Holleman (_Berichte_, v. xxvi., p. 1403), assigns to mercury +fulminate the formula + + C:N.O +Hg | | + C:N.O, + +and R. Schol (_Ber._, v. xxiii., p. 3505), + + C:NO +|| Hg. + C:NO + +They are very generally regarded as iso-nitroso compounds. + +The principal compound of fulminic acid is the mercury salt commonly known +as fulminating mercury. It is prepared by dissolving mercury in nitric +acid, and then adding alcohol to the solution, 1 part of mercury and 12 +parts of nitric acid of specific gravity 1.36, and 5-1/2 parts of 90 per +cent. alcohol being used. As soon as the mixture is in violent reaction, 6 +parts more of alcohol are added slowly to moderate the action. At first +the mixture blackens from the separation of mercury, but this soon +vanishes, and is succeeded by crystalline flocks of mercury fulminate +which fall to the bottom of the vessel. During the reaction, large +quantities of volatile oxidation products of alcohol, such as aldehyde, +ethylic nitrate, &c., are evolved from the boiling liquid, whilst others, +such as glycollic acid, remain in solution. The mercury fulminate is then +crystallised from hot water. It forms white silky, delicate needles, which +are with difficulty soluble in cold water. In the dry state it is +extremely explosive, detonating on heating, or by friction or percussion, +as also on contact with concentrated sulphuric acid. The reaction that +takes place upon its decomposition is as follows:-- + +C_{2}N_{2}O_{2}Hg = Hg + 2CO + N_{2} +(284) + +According to this equation 1 grm. of the fulminate should yield 235.8 c.c. +(= 66.96 litres for 284 grms.). Berthelot and Vicille have obtained a +yield of 234.2 c.c., equal to 66.7 litres for one equivalent 284 grms. + +Dry fulminate explodes violently when struck, compressed, or touched with +sulphuric acid, or as an incandescent body. If heated slowly, it explodes +at 152° C., or if heated rapidly, at 187° C. It is often used mixed with +potassium chlorate in detonators. The reaction which takes place in this +case is 3C_{2}N_{2}O_{2}Hg + 2KClO_{3} = 3Hg + 6CO_{2} + 3N_{2} + 2KCl. + +On adding copper or zinc to a hot saturated solution of the salt, +fulminate of copper or zinc is formed. The copper salt forms highly +explosive green crystals. There is also a double fulminate of copper of +ammonia, and of copper and potassium. Silver fulminite, +C_{2}N_{2}O_{2}Ag_{2}, is prepared in a similar manner to the mercury +salt. It separates in fine white needles, which dissolve in 36 parts of +boiling water, and are with difficulty soluble in cold water. At above +100° C., or on the weakest blow, it explodes with fearful violence. Even +when covered with water it is more sensitive than the mercury salt. It +forms a very sensitive double salt with ammonia and several other metals. +With hydrogen it forms the acid fulminate of silver. It is used in +crackers and bon-bons, and other toy fireworks, in minute quantities. Gay +Lussac found it to be composed as follows:--Carbon, 7.92 per cent.; +nitrogen, 9.24 per cent.; silver, 72.19 per cent.; oxygen, 10.65 per +cent.; and he assigned to it the formula, C_{2}N_{2}Ag_{2}O_{2}. Laurent +and Gerhardt give it the formula, C_{2}N(NO_{2})Ag_{2}, and thus suppose +it to contain nitryl, NO_{2}. + +On adding potassium chloride to a boiling solution of argentic fulminate, +as long as a precipitate of argentic chloride forms, there is obtained on +evaporation brilliant white plates, of a very explosive nature, of +potassic argentic fulminate, C(NO_{2})KAg.CN, from whose aqueous solution +nitric acid precipitates a white powder of hydric argentic fulminate, +C(NO_{2})HAg.CN. All attempts to prepare fulminic acid, or nitro-aceto- +nitrile, C(NO_{2})H_{2}CN, from the fulminates have failed. There is a +fulminate of gold, which is a violently explosive buff precipitate, formed +when ammonia is added to ter-chloride of gold, and fulminate of platinum, +a black precipitate formed by the addition of ammonia to a solution of +oxide platinum, in dilute sulphuric acid. + +Fulminating silver is a compound obtained by the action of ammonia on +oxide of silver. It is a very violent explosive. Pure mercury fulminate +may be kept an indefinite length of time. Water does not affect it. It +explodes at 187° C., and on contact with an ignited body. It is very +sensitive to shock and friction, even that of wood upon wood. It is used +for discharging bullets in saloon rifles. Its inflammation is so sudden +that it scatters black powder on which it is placed without igniting it, +but it is sufficient to place it in an envelope, however weak, for +ignition to take place, and the more resisting the envelope the more +violent is the shock, a circumstance that plays an important part in caps +and detonators. The presence of 30 per cent. of water prevents +decomposition, 10 per cent. prevents explosion. This is, however, only +true for small quantities, and does not apply to silver fulminate, which +explodes under water by friction. Moist fulminates slowly decompose on +contact with the oxidisable metals. The (reduced) volume of gases obtained +from 1 kilo. is according to Berthelot, 235.6 litres. The equation of its +decomposition is C_{2}HgN_{2}O_{2} = 2CO + N_{2} + Hg. + +Fulminate of mercury is manufactured upon the large scale by two methods. +One of these, commonly known as the German method, is conducted as +follows:--One part of mercury is dissolved in 12 parts of nitric acid of a +specific gravity of 1.375, and to this solution 16.5 parts of absolute +alcohol are added by degrees, and heat is then slowly applied to the +mixture until the dense fumes first formed have disappeared, and when the +action has become more violent some more alcohol is added, equal in volume +to that which has already been added. This is added very gradually. The +product obtained, which is mercury fulminate, is 112 per cent. of the +mercury employed. Another method is to dissolve 10 parts of mercury in 100 +parts of nitric acid of a gravity of 1.4, and when the solution has +reached a temperature of 54° C, to pour it slowly through a glass funnel +into 83 parts of alcohol. When the effervescence ceases, it is filtered +through paper filters, washed, and dried over hot water, at a temperature +not exceeding 100° C. The fulminate is then carefully packed in paper +boxes, or in corked bottles. The product obtained by this process is 130 +per cent. of the mercury taken. This process is the safest, and at the +same time the cheapest. Fulminate should be kept, if possible, in a damp +state. Commercial fulminate is often adulterated with chlorate of potash. + +~Detonators~, or caps, are metallic capsules, usually of copper, and +resemble very long percussion caps. The explosive is pure fulminate of +mercury, or a mixture of that substance with nitrate or chlorate of +potash, gun-powder, or sulphur. The following is a common cap mixture:-- +100 parts of fulminate of mercury and 50 parts of potassium nitrate, or +100 parts of fulminate and 60 parts of meal powder. Silver fulminate is +also sometimes used in caps. There are eight sizes made, which vary in +dimensions and in amount of explosive contained. They are further +distinguished as singles, doubles, trebles, &c., according to their +number. Colonel Cundill, R.A. ("Dict. of Explosives"), gives the following +list:-- + +No. 1 contains 300 grms. of explosive per 1000. + " 2 " 400 " " " " " + " 3 " 540 " " " " " + " 4 " 650 " " " " " + " 5 " 800 " " " " " + " 6 " 1,000 " " " " " + " 7 " 1,500 " " " " " + " 8 " 2,000 " " " " " + +Trebles are generally used for ordinary dynamite, 5, 6, or 7 for +gun-cotton, blasting gelatine, roburite, &c. + +In the British service percussion caps, fuses, &c., are formed of 6 parts +by weight of fulminate of mercury, 6 of chlorate of potash, and 4 of +sulphide of antimony; time fuses of 4 parts of fulminate, 6 of potassium +chlorate, 4 of sulphide of antimony, the mixture being damped with a +varnish consisting of 645 grains of shellac dissolved in a pint of +methylated spirit. Abel's fuse (No. 1) consists of a mixture of sulphide +of copper, phosphide of copper, chlorate of potash, and No. 2 of a mixture +of gun-cotton and gun-powder. They are detonated by means of a platinum +wire heated to redness by means of an electric current. Bain's fuse +mixture is a mixture of subphosphide of copper, sulphide of antimony, and +chlorate of potash. + +In the manufacture of percussion caps and detonators the copper blanks are +cut from copper strips and stamped to the required shape. The blanks are +then placed in a gun-metal plate, with the concave side uppermost--a tool +composed of a plate of gun-metal, in which are inserted a number of copper +points, each of the same length, and so spaced apart as to exactly fit +each point into a cap when inverted over a plate containing the blanks. +The points are dipped into a vessel containing the cap composition, which +has been previously moistened with methylated spirit. It is then removed +and placed over the blanks, and a slight blow serves to deposit a small +portion of the cap mixture into each cap. A similar tool is then dipped +into shellac varnish, removed and placed over the caps, when a drop of +varnish from each of the copper points falls into the caps, which are then +allowed to dry. This is a very safe and efficacious method of working. + +At the works of the Cotton-Powder Company Limited, at Faversham, the +fulminate is mixed wet with a very finely ground mixture of gun-cotton and +chlorate of potash, in about the proportions of 6 parts fulminate, 1 part +gun-cotton, and 1 part chlorate. The water in which the fulminate is +usually stored is first drained off, and replaced by displacement by +methyl-alcohol. While the fulminate is moist with alcohol, the gun-cotton +and chlorate mixture is added, and well mixed with it. This mixture is +then distributed in the detonators standing in a frame, and each detonator +is put separately into a machine for the purpose of pressing the paste +into the detonator shell. + +At the eleventh annual meeting of the representatives of the Bavarian +chemical industries at Regensburg, attention was drawn to the unhealthy +nature of the process of charging percussion caps. Numerous miniature +explosions occur, and the air becomes laden with mercurial vapours, which +exercise a deleterious influence upon the health of the operatives. There +is equally just cause for apprehension in respect to the poisonous gases +which are evolved during the solution of mercury in nitric acid, and +especially during the subsequent treatment with alcohol. Many methods have +been proposed for dealing with the waste products arising during the +manufacture and manipulation of fulminate of mercury, but according to +Kæmmerer, only one of comparatively recent introduction appears to be at +all satisfactory. It is based upon the fact that mercuric fulminate, when +heated with a large volume of water under high pressure, splits up into +metallic mercury and non-explosive mercurial compounds of unknown +composition. + +In mixing the various ingredients with mercury fulminate to form cap +mixtures, they should not be too dry; in fact, they are generally more or +less wet, and mixed in small quantities at a time, in a special house, the +floors of which are covered with carpet, and the tables with felt. Felt +shoes are also worn by the workpeople employed. All the tools and +apparatus used must be kept very clean; for granulating, hair sieves are +used, and the granulated mixture is afterwards dried on light frames, with +canvas trays the bottoms of which are covered with thin paper, and the +frames fitted with indiarubber cushions, to reduce any jars they may +receive. The windows of the building should be painted white to keep out +the rays of the sun. + +Mr H. Maxim, of New York, has lately patented a composition for detonators +for use with high explosives, which can also be thrown from ordnance in +considerable quantities with safety. The composition is prepared as +follows:--Nitro-glycerine is thickened with pyroxyline to the consistency +of raw rubber. This is done by employing about 75 to 85 per cent. of +nitro-glycerine, and 15 to 25 per cent. of pyroxyline, according to the +stiffness or elasticity of the compound desired. Some solvent that +dissolves the nitro-cotton is also used. The product thus formed is a kind +of blasting gelatine, and should be in a pasty condition, in order that it +may be mixed with fulminate of mercury. The solvent used is acetone, and +the quantity of fulminate is between 75 to 85 per cent. of the entire +compound. If desired, the compound can be made less sensitive to shocks by +giving it a spongy consistency by agitating it with air while it is still +in a syrupy condition. The nitro-glycerine, especially in this latter +case, may be omitted. In some cases, when it is desirable to add a +deterring medium, nitro-benzene or some suitable gum is added. + +[Illustration: FIG. 34. METHOD OF PREPARING THE CHARGE.] + +The method of preparing a blasting charge is as follows:--A piece of +Bickford fuse of the required length is cut clean and is inserted into a +detonator until it reaches the fulminate. The upper portion of the +detonator is then squeezed round the fuse with a pair of nippers. The +object of this is not only to secure that the full power of the detonator +may be developed, but also to fix the fuse in the cap (Fig. 34). When the +detonator, &c., is to be used under water, or in a damp situation, grease +or tallow should be placed round the junction of the cap with the fuse, in +order to make a water-tight joint. A cartridge is then opened and a hole +made in its upper end, and the detonator pushed in nearly up to the top. +Gun-cotton or tonite cartridges generally have a hole already made in the +end of the charge. Small charges of dry gun-cotton, known as primers, are +generally used to explode wet gun-cotton. The detonators (which are often +fired by electrical means) are placed inside these primers (Fig. 35). + +[Illustration: FIG. 35. PRIMER.] + +One of the forms of electric exploders used is shown in Fig. 36. This +apparatus is made by Messrs John Davis & Son, and is simply a small hand +dynamo, capable of producing a current of electricity of high tension. +This firm are also makers of various forms of low tension exploders. A +charge having been prepared, as in Fig. 34, insert into the bore-hole one +or more cartridges as judged necessary, and squeeze each one down +separately with a _wooden_ rammer, so as to leave no space round the +charge, and above this insert the cartridge containing the fuse and +detonator. Now fill up the rest of the bore-hole with sand, gravel, water, +or other tamping. With gelatine dynamites a firm tamping may be used, but +with ordinary dynamite loose sand is better. The charge is now ready for +firing. + +[Illustration: FIG. 36.--ELECTRIC EXPLODER.] + + + + +CHAPTER VI. + +_SMOKELESS POWDERS._ + +Smokeless Powder in General--Cordite--Axite--Ballistite--U.S. Naval +Powder--Schultze's E.G. Powder--Indurite--Vielle Poudre--Rifleite-- +Cannonite--Walsrode--Cooppal Powders--Amberite--Troisdorf--Maximite-- +Picric Acid Powders, &c., &c. + + +The progress made in recent years in the manufacture of smokeless powders +has been very great. With a few exceptions, nearly all these powders are +nitro compounds, and chiefly consist of some form of nitro-cellulose, +either in the form of nitro-cotton or nitro-lignine; or else contain, in +addition to the above, nitro-glycerine, with very often some such +substance as camphor, which is used to reduce the sensitiveness of the +explosive. Other nitro bodies that are used, or have been proposed, are +nitro-starch, nitro-jute, nitrated paper, nitro-benzene, di-nitro-benzene, +mixed with a large number of other chemical substances, such as nitrates, +chlorates, &c. And lastly, there are the picrate powders, consisting of +picric acid, either alone or mixed with other substances. + +The various smokeless powders may be roughly divided into military and +sporting powders. But this classification is very rough; because although +some of the better known purely military powders are not suited for use in +sporting guns, nearly all the manufacturers of sporting powders also +manufacture a special variety of their particular explosive, fitted for +use in modern rifles or machine guns, and occasionally, it is claimed, for +big guns also. + +Of the purely military powders, the best known are cordite, ballistite, +and the French B.N. powder, the German smokeless (which contains nitro- +glycerine and nitro-cotton); and among the general powders, two varieties +of which are manufactured either for rifles or sporting guns, Schultze's, +the E.C. Powders, Walsrode powder, cannonite, Cooppal powder, amberite, +&c., &c. + +~Cordite~, the smokeless powder adopted by the British Government, is the +patent of the late Sir F.A. Abel and Sir James Dewar, and is somewhat +similar to blasting gelatine. It is chiefly manufactured at the Royal +Gunpowder Factory at Waltham Abbey, but also at two or three private +factories, including those of the National Explosives Company Limited, the +New Explosives Company Limited, the Cotton-Powder Company Limited, Messrs +Kynock's, &c. As first manufactured it consisted of gun-cotton 37 per +cent., nitro-glycerine 58 per cent., and vaseline 5 per cent., but the +modified cordite now made consists of 65 per cent. gun-cotton, 30 per +cent. of nitro-glycerine, and 5 per cent. of vaseline. The gun-cotton used +is composed chiefly of the hexa-nitrate,[A] which is not soluble in nitro- +glycerine. It is therefore necessary to use some solvent such as acetone, +in order to form the jelly with nitro-glycerine. The process of +manufacture of cordite is very similar, as far as the chemical part of the +process is concerned, to that of blasting gelatine, with the exception +that some solvent for the gun-cotton, other than nitro-glycerine has to be +used. Both the nitro-glycerine and the gun-cotton employed must be as dry +as possible, and the latter should not contain more than .6 per cent. of +mineral matter and not more than 10 per cent. of soluble nitro-cellulose, +and a nitrogen content of not less than 12.5 per cent. The dry gun-cotton +(about 1 per cent. of moisture) is placed in an incorporating tank, which +consists of a brass-lined box, some of the acetone is added, and the +machine (Fig. 29), is started; after some time the rest of the acetone is +added (20 per cent. in all) and the paste kneaded for three and a half +hours. At the end of this time the Vaseline is added, and the kneading +continued for a further three and a half hours. The kneading machine (Fig. +29) consists of a trough, composed of two halves of a cylinder, in each of +which is a shaft which carries a revolving blade. These blades revolve in +opposite directions, and one makes about half the number of revolutions of +the other. As the blades very nearly touch the bottom of the trough, any +material brought into the machine is divided into two parts, kneaded +against the bottom, then pushed along the blade, turned over, and +completely mixed. During kneading the acetone gradually penetrates the +mixture, and dissolves both the nitro-cellulose and nitro-glycerine, and a +uniform dough is obtained which gradually assumes a buff colour. During +kneading the mass becomes heated, and therefore cold water is passed +through the jacket of the machine to prevent heating the mixture above the +normal temperature, and consequent evaporation of the acetone. The top of +the machine is closed in with a glass door, in order to prevent as far as +possible the evaporation of the solvent. When the various ingredients are +formed into a homogeneous mass, the mixture is taken to the press house, +where in the form of a plastic mass it is placed in cylindrical moulds. +The mould is inserted in a specially designed press, and the cordite paste +forced through a die with one or more holes. The paste is pressed out by +hydraulic pressure, and the long cord is wound on a metal drum (Fig. 38), +or cut into lengths; in either case the cordite is now sent to the drying +houses, and dried at a temperature of about 100° F. from three to fourteen +days, the time varying with the size. This operation drives off the +acetone, and any moisture the cordite may still contain, and its diameter +decreases somewhat. In case of the finer cordite, such as the rifle +cordite, the next operation is blending. This process consists in mounting +ten of the metal drums on a reeling machine similar to those used for +yarns, and winding the ten cords on to one drum. This operation is known +as "ten-stranding." Furthermore, six "ten-stranded" reels are afterwards +wound upon one, and the "sixty-stranded" reel is then ready to be sent +away, This is done in order to obtain a uniform blending of the material. +With cordite of a larger diameter, the cord is cut into lengths of 12 +inches. Every lot of cordite from each manufacturer has a consecutive +number, numbers representing the size and one or more initial letters to +identify the manufacturer. These regulations do not apply to the Royal +Gunpowder Factory, Waltham Abbey. The finished cordite resembles a cord of +gutta-percha, and its colour varies from light to dark brown. It should +not look black or shrivelled, and should always possess sufficient +elasticity to return to its original form after slight bending. Cordite is +practically smokeless. On explosion a very thin vapour is produced, which +is dissipated rapidly. This smokelessness can be understood from the fact +that the products of combustion are nearly all non-condensible gases, and +contain no solid products of combustion which would cause smoke. For the +same muzzle velocity a smaller charge of cordite than gunpowder is +required owing to the greater amount of gas produced. Cordite is very slow +in burning compared to gunpowder. For firing blank cartridges cordite +chips containing no vaseline is used. The rate at which cordite explodes +depends in a measure upon the diameter of the cords, and the pressure +developed upon its mechanical state. The sizes of cordite used are given +by Colonel Barker, R.A., as follows:-- + +For the .303 rifle .0375 inch diameter. + " 12 Pr. B.L. gun .05 " + " " .075 " + " 4.7-inch Q.F. gun .100 " + " 6-inch Q.F. gun .300 " + " heavy guns .40 to .50 " + +For rifles the cordite is used in bundles of sixty strands, in field-guns +in lengths of 11 to 12 inches, and the thicker cordite is cut up into +14-inch lengths. Colonel Barker says that the effect of heat upon cordite +is not greater as regards its shooting qualities than upon black powder, +and in speaking of the effect that cordite has upon the guns in which it is +used (R.A. Inst.) said that they had at Waltham Abbey a 4.7-inch Q.F. gun +that had fired 40 rounds of black powder, and 249 rounds of cordite (58 +per cent. nitro-glycerine) and was still in excellent condition, and +showed very little sign of action, and also a 12-lb. B.L. gun that had +been much used and was in no wise injured. + +[Footnote A: The gun-cotton used contains 12 per cent. of soluble +gun-cotton, and a nitrogen content of not less than 12.8 to 13.1 per cent.] + +[Illustration: Fig. 37 Scale, 1 inch = 1 foot. Single Strand Reel.] + +[Illustration: FIG. 38.--"TEN-STRANDING."] + +In some experiments made by Captain Sir A. Noble,[A] with the old cordite +containing 58 per cent. nitro-glycerine, a charge of 5 lbs. 10 oz. of +cordite of 0.2 inch diameter was fired. The mean chamber crusher gauge +pressure was 13.3 tons per square inch (maximum 13.6, minimum 12.9), or a +mean of 2,027 atmospheres (max. 2,070, min. 1,970). The muzzle velocity +was 2,146 foot seconds, and the muzzle energy 1,437 foot tons. A gramme of +cordite generated 700 c.c. of permanent gases at 0° C. and 760 mm. +pressure. The quantity of heat developed was 1,260 gramme units. In the +case of cordite, as also with ballistite, a considerable quantity of +aqueous vapour has to be added to the permanent gases formed. A similar +trial, in which 12 lbs. of ordinary pebble powder was used, gave a +pressure of 15.9 tons per square inch, or a mean of 2,424 atmospheres. It +gave a 45-lb. projectile a mean muzzle velocity of 1,839 foot seconds, +thus developing a muzzle energy of 1,055 foot tons. A gramme of this +powder at 0° C. and 760 mm. generates 280 c.c. of permanent gases, and +develops 720 grm. units of heat. + +[Footnote A: _Proc. Roy. Soc._, vol. lii., No. 315.] + +In a series of experiments conducted by the War Office Chemical Committee +on Explosives in 1891, it was conclusively shown that considerable +quantities of cordite may be burnt away without explosion. A number of +wooden cases, containing 500 to 600 lbs. each of cordite, were placed upon +a large bonfire of wood, and burned for over a quarter of an hour without +explosion. At Woolwich in 1892 a brown paper packet containing ten cordite +cartridges was fired into with a rifle (.303) loaded with cordite, without +the explosion of a single one of them, which shows its insensibility to +shock. + +With respect to the action of cordite upon guns, Sir A. Noble points out +that the erosion caused is of a totally different kind to that of black +powder. The surface of the barrel in the case of cordite appears to be +washed away smoothly by the gases, and not pitted and eaten into as with +black powder. The erosion also extends over a shorter length of surface, +and in small arms it is said to be no greater than in the case of black +powder. Sir A. Noble says in this connection: "It is almost unnecessary to +explain that freedom from rapid erosion is of very high importance in view +of the rapid deterioration of the bores of large guns when fired with +charges developing very high energies. As might perhaps be anticipated +from the higher heat of ballistite, its erosive power is slightly greater +than that of cordite, while the erosive power of cordite is again slightly +greater than that of brown prismatic. Amide powder, on the other hand, +possesses the peculiarity of eroding very much less than any other powder +with which I have experimented, its erosive power being only one-fourth of +that of the other powders enumerated." + +TABLE GIVING SOME OF SIR. A. NOBLE'S EXPERIMENTS. + ________________________________________________________________________ +| | +| VELOCITIES OBTAINED. | +|________________________________________________________________________| +| | | | | | +| | In a 40 | In a 50 | In a 75 | In a 100 | +| | Cal. Gun.| Cal. Gun.| Cal. Gun.| Cal. Gun.| +|____________________________|__________|__________|__________|__________| +| | | | | | +| |Foot Secs.|Foot Secs.|Foot Sees.|Foot Secs.| +| | | | | | +|With cordite 0.4 in. diam. | 2,794 | 2,940 | 3,166 | 3,286 | +| " " 0.3 " | 2,469 | 2,619 | 2,811 | 2,905 | +| " ballistite 0.3 in. cubes| 2,416 | 2,537 | 2,713 | 2,806 | +| " French B.N. for | | | | | +| 6-inch guns | 2,249 | 2,360 | 2,536 | 2,616 | +| " prismatic amide | 2,218 | 2,342 | 2,511 | 2,574 | +| | | | | | +|____________________________|__________|__________|__________|__________| +| | +| ENERGIES REPRESENTED BY ABOVE VELOCITIES. | +|________________________________________________________________________| +| | | | | | +| |Foot Tons.|Foot Tons.|Foot Tons.|Foot Tons.| +| | | | | | +| Cordite 0.4 inch | 5,413 | 5,994 | 6,950 | 7,478 | +| Ballistite 0.3 inch cubes | 4,227 | 4,754 | 5,479 | 5,852 | +| French B.N. | 4,047 | 4,463 | 5,104 | 5,460 | +| Prismatic amide | 3,507 | 3,862 | 4.460 | 4,745 | +|____________________________|__________|__________|__________|__________| + +And again, in speaking of his own experiments, he says: "One 4.7-inch gun +has fired 1,219 rounds, and another 953, all with full charges of cordite, +while a 6-inch gun has fired 588 rounds with full charges, of which 355 +were cordite. In the whole of these guns, so far as I can judge, the +erosion is certainly not greater than with ordinary powder, and differs +from it remarkably in appearance. With ordinary powder a gun, when much +eroded, is deeply furrowed (these furrows having a great tendency to +develop into cracks), and presents much the appearance in miniature of a +very roughly ploughed field. With cordite, on the contrary, the surface +appears to be pretty smoothly swept away, while the length of the surface +eroded is considerably less." + +[Illustration: FIG. 39.--COMPARATIVE PRESSURE CURVES OF CORDITE AND BLACK +POWDER. _a_, Charge, 48 lbs. powder; _b_, charge, 13 lbs. 4 oz. cordite; +_c_, charge, 13 lbs. 4 oz. powder. Weight of projectile, 100 lbs. in +6-inch gun. M.V. Cordite = 1960 feet seconds.] + +The pressures given by cordite compared with those given by black powder +in the 6-inch gun will be seen upon reference to Fig. 39, which is taken +from Professor V.B. Lewes's paper, read before the Society of Arts; and +due to Dr W. Anderson, F.R.S., the Director-General of Ordnance Factories. + +It has been found that the erosive effect is in direct proportion to the +nitro-glycerine present. The cordite M.D., which contains only 30 per +cent. nitro-glycerine, gives only about half the erosive effect of the old +service cordite. With regard to the heating effect of cordite and cordite +M.D. on a rifle, Mr T.W. Jones made some experiments. He fired fifty +rounds of .303 cartridges in fifteen minutes in the service rifle. Cordite +raised the temperature of the rifle 270° F., and cordite M.D. 160° F. +only. + +With regard to the effect of heat upon cordite, there is some difference +of opinion. Dr W. Anderson, F.R.S., says that there is no doubt that the +effect of heat upon cordite is greater than upon black powder. At a +temperature of 110° F. the cordite used in the 4.7-inch gun is +considerably affected as regards pressure. + +Colonel Barker, R.A., in reply to a question raised by Colonel Trench, +R.A. (at the Royal Artillery Institution), concerning the shooting +qualities of cordite heated to a temperature of 110° F., said: "Heating +cordite and firing it hot undoubtedly does disturb its shooting qualities, +but as far as we can see, not much more than gunpowder. I fear that we +must always expect abnormal results with heated propellants, either +gunpowder or cordite; and when fired hot, the increase in pressure and +velocities will depend upon the heat above the normal or average +temperature at which firing takes place." Colonel Barker also, in +referring to experiments that had been made in foreign climates, said: +"Climatic trials have been carried out all over the world, and they have +so far proved eminently satisfactory. The Arctic cold of the winter in +Canada, with the temperature below zero, and the tropical sun of India, +have as yet failed to shake the stability of the composition, or +abnormally injure its shooting qualities." Dr Anderson is of opinion that +cordite should not be stored in naval magazines near to the boilers. +Professor Vivian B. Lewes, in his recent Cantor Lectures before the +Society of Arts, suggests that the magazines of warships should be water- +jacketed, and maintained at a temperature that does not rise above 100° F. + +~Axite.~--This powder is manufactured by Messrs Kynock Limited, at their +works at Witton, Birmingham. The main constituents of cordite are retained +although the proportions are altered; ingredients are added which impart +properties not possessed by cordite, and the methods of its manufacture +have been modified. The form has also been altered. Axite is made in the +form of a ribbon, the cross section being similar in shape to a double- +headed rail. It is claimed for this powder, that it does not corrode the +barrel in the way cordite does, that with equal pressure it gives greatly +increased velocity, and therefore flatter trajectory. That the effect of +temperature on the pressure and velocity with axite is only half that with +cordite. That the maximum flame temperature of axite is considerably less +than that of cordite, and the erosive effect is therefore considerably +less. That the deposit left in the barrel after firing axite cartridges +reduces the friction between the bullet and the barrel. It is therefore +practicable to use axite cartridges giving higher velocities than can be +employed with cordite, as with such velocities the latter would nickel the +barrel by excessive friction. It is also claimed that the accuracy is +greatly increased. The following results have been obtained with this +same time, and under the same conditions:-- + +~Axite~ Cartridges with 200-grain bullets. + Velocity 2,726 F.S. + Pressure 20.95 tons. + +~Axite~ Cartridges with 215-grain bullets. + Velocity 2,498 F.S. + Pressure 19.24 tons. + +~Axite~ Service Cartridges. + Velocity 2,179 F.S. + Pressure 15.76 tons. + +~Cordite~ Service Cartridges. + Velocity 2,010 F.S. + Pressure 15.67 tons. + +Five rounds from the Service axite and Service cordite were placed in an +oven and heated to a temperature of 110° F. for one hour, and were then +fired for pressure. The following results were obtained:-- + + ~Axite.~ ~Cordite.~ + Before heating 15.76 tons per sq. in. 15.67 tons per sq. in. + After " 16.73 " " 17.21 " " + _____ _____ + + Increase .97 = 6.1% 1.54 = 9.8% + +Average Velocities-- + Before heating 2,150 F.S. 2,030 F.S. + After " 2,180 " 2,090 " + _____ _____ + + Increase 30 F.S. = 1-1/2% 60.0 F.S. = 3% + +In order to show the accuracy given by axite, seven rounds were fired from +a machine rest at a target fixed at 100 yards from a rifle. Six of the +seven shots could be covered by a penny piece, the other being just +outside. In order to ascertain the relative heat imparted to a rifle by +the explosion of axite and cordite, ten rounds each of axite and cordite +cartridges were fired from a .303 rifle, at intervals of ten seconds, the +temperature of the rifle barrel being taken before and after each series:-- + +THE RISE IN TEMPERATURE OF THE RIFLE BARREL + +With axite was 71° F. +With cordite was 89° F. +Difference in favour of axite 18° F. = 20.2% + +The lubricating action of axite is shown by the fact that a series of +cordite cartridges fired from a .303 rifle in the ordinary way, followed +by a second series, the barrel being lubricated between each shot by +firing an axite cartridge alternately with the cordite cartridge. The mean +velocity of the first series of cordite cartridges was 1,974 ft. per +second; the mean velocity of the second series was 2,071 ft. per second; +the increased velocity due to the lubricating effect of axite therefore +was 97 ft. per second. This powder, it is evident, has very many very +excellent qualities, and considerable advantages over cordite. It is +understood that axite is at present under the consideration of the British +Government for use as the Service powder. + +~Ballistite.~--Nobel's powder, known as ballistite, originally consisted +of a camphorated blasting gelatine, and was made of 10 parts of camphor in +100 parts of nitro-glycerine, to which 200 parts of benzol were then +added, and 50 parts of nitro-cotton (soluble) were then steeped in this +mixture, which was then heated to evaporate off the benzol, and the +resulting compound afterwards passed between steam-heated rollers, and +formed into sheets, which were then finally cut up into small squares or +other shapes as convenient. The camphor contained in this substance was, +however, found to be a disadvantage, and its use discontinued. The +composition is now 50 per cent. of soluble nitro-cotton and 50 per cent. +of nitro-glycerine. As nitro-glycerine will not dissolve its own weight of +nitro-cotton (even the soluble variety), benzol is used as a solvent, but +is afterwards removed from the finished product, just as the acetone is +removed from cordite. About 1 per cent. of diphenylamine is added for the +purpose of increasing its stability. + +The colour of ballistite is a darkish brown. It burns in layers when +ignited, and emits sparks. The size of the cubes into which it is cut is a +0.2-inch cube. Its density is 1.6. It is also, by means of a special +machine, prepared in the form of sheets, after being mixed in a wooden +trough fitted with double zinc plates, and subjected to the heating +process by means of hot-water pipes. It is passed between hot rollers, and +rolled into sheets, which are afterwards put through a cutting machine and +granulated. Sir A. Nobel's experiments[A] with this powder gave the +following results:--The charge used was 5 lbs. 8 oz., the size of the +cubes being 0.2 inch. The mean crusher-gauge pressure was 14.3 tons per +square inch (maximum, 2,210; minimum, 2,142), and average pressure 2,180 +atmospheres. The muzzle velocity was 2,140 foot seconds, and the muzzle +energy 1,429 foot tons. A gramme of ballistite generates 615 c.c. of +permanent gases, and gives rise to 1,365 grm. units of heat. Ballistite is +manufactured at Ardeer in Scotland, at Chilworth in Surrey, and also in +Italy, under the name of Filite, which is in the form of cords instead of +cubes. The ballistite made in Germany contained more nitro-cellulose, and +the finished powder was coated with graphite. Its use has been +discontinued as the Service powder in Germany, but it is still the Service +powder in Italy. + +[Footnote A: _Proc. Roy. Soc._, vol. lii., p. 315.] + +~U.S. Naval Smokeless Powder.~--This powder is manufactured at the U.S. +Naval Torpedo Station for use in guns of all calibres in the U.S. Navy. It +is a nitro-cellulose powder, a mixture of insoluble and soluble nitro- +cellulose together with the nitrates of barium and potassium, and a small +percentage of calcium carbonate. The proportions in the case of the powder +for the 6-inch rapid-fire gun are as follows:--Mixed nitro-cellulose +(soluble and insoluble) 80 parts, barium nitrate 15 parts, potassium +nitrate 4 parts, and calcium carbonate 1 part. The percentage of nitrogen +contained in the insoluble nitro-cellulose must be 13.30±0.15, and in the +soluble 11.60±0.15, and the mean nitration strength of the mixture must be +12.75 per cent. of nitrogen. The solvent used in making the powder is a +mixture of ether (sp. gr. 0.720) 2 parts, and alcohol (95 per cent. by +volume) 1 part. The process of manufacture is briefly as follows:[A]--The +soluble and insoluble nitro-cellulose are dried separately at a +temperature from 38° to 41° C., until they do not contain more than 0.1 +per cent. of moisture. The calcium carbonate is also finely pulverised and +dried, and is added to the mixed nitro-celluloses after they have been +sifted through a 16-mesh sieve. The nitrates are next weighed out and +dissolved in hot water, and to this solution is added the mixture of +nitro-celluloses and calcium carbonate with constant stirring until the +entire mass becomes a homogeneous paste. This pasty mass is next spread +upon trays and re-dried at a temperature between 38° and 48° C., and when +thoroughly dry it is transferred to the kneading machine. The ether- +alcohol mixture is now added, and the process of kneading begun. It has +been found by experiment that the amount of solvent required to secure +thorough incorporation is about 500 c.c. to each 500 grms. of dried paste. +To prevent loss of solvent due to evaporation, the kneading machine is +made vapour light. The mixing or kneading is continued until the resulting +greyish-yellow paste is absolutely homogeneous so far as can be detected +by the eye, which requires from three to four hours. The paste is next +treated in a preliminary press (known as the block press and is actuated +by hydraulic power), where it is pressed into a cylindrical mass of +uniform density and of such dimensions as to fit it for the final or +powder press. The cylindrical masses from the block press are transferred +to the final press, whence they are forced out of a die under a pressure +of about 500 lbs. per square inch. As it emerges from the final press the +powder is in the form of a ribbon or sheet, the width and thickness of +which is determined by the dimensions of the powder chamber of the gun in +which the powder is to be used. On the inner surface of the die are ribs +extending in the direction of the powder as it emerges from the press, the +object of these ribs being to score the sheets or ribbons in the direction +of their length, so that the powder will yield uniformly to the pressure +of the gases generated in the gun during the combustion of the charge. The +ribbon or sheet is next cut into pieces of a width and length +corresponding to the chamber of the gun for which it is intended, the +general rule being that the thickness of the grain (when perfectly dry) +shall be fifteen one-thousandths (.015) of the calibre of the gun, and the +length equal to the length to fit the powder chamber. Thus, in case of the +6-inch rapid-fire gun the thickness of the grain (or sheet) is 0.09 of an +inch and the length 32 inches. The sheets are next thoroughly dried, first +between sheets of porous blotting-paper under moderate pressure and at a +temperature between 15° C. and 21.5° C. for three days, and then exposed +to free circulation of the air at about 21.5° C. for seven days, and +finally subjected for a week or longer to a temperature not exceeding 38° +C. until they cease to lose weight. + +[Footnote A: Lieut. W. Walke, "Lectures on Explosives," p. 330.] + +The sheets, when thoroughly dried, are of a uniform yellowish-grey colour, +and of the characteristic colloidal consistency; they possess a perfectly +smooth surface, and are free from internal blisters or cracks. The +temperature of ignition of the finished powder should not be below 172° +C., and when subjected to the heat or stability test, it is required to +resist exposure to a temperature of 71° C. for thirty minutes without +causing discoloration of the test paper. + +~W.A. Powder.~--This powder is made by the American Smokeless Powder +Company, and it was proposed for use in the United States Army and Navy. +It is made in several grades according to the ballistic conditions +required. It consists of insoluble gun-cotton and nitro-glycerine, +together with metallic nitrates and an organic substance used as a +deterrent or regulator. The details of its manufacture are very similar to +those of cordite, with the exception that the nitro-glycerine is dissolved +in a portion of the acetone, before it is added to the gun-cotton. The +powder is pressed into solid threads, or tubular cords or cylinders, +according to the calibre of the gun in which the powder is to be used. As +the threads emerge from the press they are received upon a canvas belt, +which passes over steam-heated pipes, and deposited in wire baskets. The +larger cords or cylinders are cut into the proper lengths and exposed upon +trays in the drying-house. The powder for small arms is granulated by +cutting the threads into short cylinders, which are subsequently tumbled, +dusted, and, if not perfectly dry, again placed upon trays in the drying- +house. Before being sent away from the factory, from five to ten lots of +500 lbs. each are mixed in a blending machine, in order to obtain greater +uniformity. The colour of the W.A. powder is very light grey, the grains +are very uniform in size, dry and hard. The powder for larger guns is of a +yellowish colour, almost translucent, and almost as hard as vulcanite. The +powder is said to be unaffected by atmospheric or climatic conditions, to +be stable, and to have given excellent ballistic results; it is not +sensitive to the impact of bullets, and when ignited burns quietly, unless +strongly confined. + +Turning now to the smokeless powders, in which the chief ingredient is +nitro-cellulose in some form (either gun-cotton or nitro-lignine, &c.), +one of the first of these was Prentice's gun-cotton, which consisted of +nitrated paper 15 parts, mixed with 85 parts of unconverted cellulose. It +was rolled into a cylinder. Another was Punshon's gun-cotton powder, which +consisted of gun-cotton soaked in a solution of sugar, and then mixed with +a nitrate, such as sodium or potassium nitrate. Barium nitrate was +afterwards used, and the material was granulated, and consisted of +nitrated gun-cotton. + +The explosive known as tonite, made at Faversham, was at first intended +for use as a gunpowder, but is now only used for blasting. + +~The Schultze Powder.~--One of the earliest of the successful powders +introduced into this country was Schultze's powder, the invention of +Colonel Schultze, of the Prussian Artillery, and is now manufactured by +the Schultze Gunpowder Company Limited, of London. The composition of this +powder, as given in the "Dictionary of Explosives" by the late Colonel +Cundall, is as follows:-- + +Soluble nitro-lignine 14.83 per cent. +Insoluble " 23.36 " +Lignine (unconverted) 13.14 " +Nitrates of K and Ba 32.35 " +Paraffin 3.65 " +Matters soluble in alcohol 0.11 " +Moisture 2.56 " + +This powder was the first to solve the difficulty of making a smokeless, +or nearly smokeless powder which could be used with safety and success in +small arms. Previously, gun-cotton had been tried in various forms, and in +nearly every instance disaster to the weapon had followed, owing to the +difficulty of taming the combustion to a safe degree. But about 1866 +Colonel Schultze produced, as the result of experiments, a nitrated wood +fibre which gave great promise of being more pliable and more easily +regulated in its burning than gun-cotton, and this was at once introduced +into England, and the Schultze Gunpowder Company Limited was formed to +commence its manufacture, which it did in the year 1868. During the years +from its first appearance, Schultze gunpowder has passed through various +modifications. It was first made in a small cubical grain formed by +cutting the actual fibre of timber transversely, and then breaking this +veneer into cubes. Later on improvements were introduced, and the wood +fibre so produced was crushed to a fine degree, and then reformed into +small irregular grains. Again, an advance was made in the form of the wood +fibre used, the fibre being broken down by the action of chemicals under +high temperature, and so producing an extremely pure form of woody fibre. +The next improvement was to render the grains of the powder practically +waterproof and less affected by the atmospheric influences of moisture and +dryness, and the last improvement to the process was that of hardening the +grains by means of a solvent of nitro-lignine, so as to do away with the +dust that was often formed from the rubbing of the grains during transit. + +Minor modifications have from time to time also been made, in order to +meet the gradual alteration which has taken place during this long period +in the manufacture of sporting guns and cartridge cases to be used with +this powder, but through all its evolution this Company has adhered to the +first idea of using woody fibre in preference to cotton as the basis of +their smokeless powder, as experience has confirmed the original opinion +that a powder can be thus made less sensitive to occasional differences in +loading, and more satisfactory all round than when made from the cotton +base. The powder has always been regulated so that bulk for bulk it +occupies the same measure as the best black powder, and as regards its +weight, just one half of that of black. + +The process of manufacture of this powder is briefly as follows:-- + +Wood of clean growth is treated by the well-known sulphite process for +producing pure woody fibre, which is very carefully purified, and this, +after drying, is steeped in a mixture of nitric and sulphuric acids, to +render it a nitro-compound and the explosive base of the powder. This +nitro compound is carefully purified until it stands the very high purity +requirements of the Home Office, and is then ground with oxygen-bearing +salts, &c., and the whole is formed into little irregular-shaped grains of +the desired size, which grains are dried and hardened by steeping in a +suitable solvent for the nitro compound, and after finally drying, +sifting, &c., the powder is stored in magazines for several months before +it is issued. When issued, a very large blend is made of many tons weight, +which ensures absolute uniformity in the material. + +There is in England a standard load adopted by every one for testing a +sporting powder; this charge is 42 grains of powder and 1-1/8 oz. No. 6 +shot--this shot fired from a 12-bore gun, patterns being taken at 40 +yards, the velocity at any required distance. + +The standard muzzle velocity of Schultze gunpowder is 1,220 feet per +second. + +The mean 40 yards ditto is 875 feet per second. + +The mean 20 yards ditto is 1,050 feet per second. + +The internal pressure not to exceed 3.5 tons. + +This Company also manufactures a new form of powder, known as Imperial +Schultze. It is a powder somewhat lighter in gravity; 33 grains occupies +the bulk charge, as compared with the 42 grains of the old. It follows in +its composition much the lines of the older powder, but it is quite free +from smoke, and leaves no residue whatever. + +~The E.G. Powder.~--This is one of the oldest of the nitro powders. It was +invented by Reid and Johnson in 1882. It is now manufactured by the E.G. +Powder Company Limited, at their factory near Dartford, Kent, and in +America by the Anglo-American E.G. Powder Company, at New Jersey. The +basis of this powder is a fine form of cellulose, derived from cotton, +carefully purified, and freed from all foreign substances, and carefully +nitrated. Its manufacture is somewhat as follows:--Pure nitro-cotton, in +the form of a fine powder, is rotated in a drum, sprinkled with water, and +the drum rotated until the nitro-cotton has taken the form of grains. The +grains are then dried and moistened with ether-alcohol, whereby the +moisture is gelatinised, and afterwards coloured with aurine, which gives +them an orange colour. They are then dried and put through a sieve, in +order to separate the grains which may have stuck together during the +gelatinising process. + +Since its introduction soon after 1881, E.G. powder has undergone +considerable modifications, and is now a distinctly different product from +a practical point of view. It is now and has been since 1897 what is known +as a 33-grain powder, that is to say, the old standard charge of 3 drams +by measure for a 12-bore gun weighs 33 grains, as compared with 42 grains +for the original E.G. and other nitro powders. This improvement was +effected by a reduction of the barium nitrate and the use of nitro- +cellulose of a higher degree of nitration, and also more gelatinisation in +manufacture. The granules are very hard, and resist moisture to an extent +hitherto unattainable by any "bulk" powder. + +Irregularities of pressure in loading have also a minimum effect by reason +of the hardness of the grains. The colouring matter used is aurine, and +the small quantity of nitrate used is the barium salt. The powder is +standardised for pressure velocity with Boulengé chronograph,[A] pattern +and gravimetric density by elaborate daily tests, and is continually +subjected to severe trials for stability under various conditions of +storage, the result being that it may be kept for what in practice amount +to indefinite periods of time, either in cartridges or in bulk without any +alteration being feared. The E.C. powders are used in sporting guns. No. 1 +and No. 2 E.C. are not at present manufactured, E.C. No. 3 having taken +their place entirely. Since 1890 these powders have been manufactured +under the Borland-Johnson patents, these improved powders being for some +time known as the J.B. powders. The E.C. No. 1 was superseded by the E.C. +No. 2, made under the Borland-Johnson patents, and this in its turn by the +E.C. No. 3 (in 1897). + +[Footnote A: Invented in 1869 by Major Le Boulengé, Belgian Artillery. It +is intended to record the mean velocity between any two points, and from +its simplicity and accuracy is largely employed. Other forms have been +invented by Capt. Bréger, French Artillerie de la Marine, and Capt. +Holden, R.A.] + +~Indurite~ is the invention of Professor C.E. Munroe, of the U.S. Naval +Torpedo Station. It is made from insoluble nitro-cotton, treated in a +particular manner by steam, and mixed with nitro-benzene. The _Dupont_ +powder is very similar to _Indurite_. M.E. Leonard, of the United States, +invented a powder consisting of 75 parts of nitro-glycerine, 25 parts of +gun-cotton, 5 parts of lycopodium powder, and 4 parts of urea crystals +dissolved in acetone. The French smokeless powder, Vielle poudre (poudre +B), used in the Lebel rifle, is a mixture of nitro-cellulose and tannin, +mixed with barium and potassium nitrates. It gives a very feeble report, +and very little bluish smoke. The Nobel Company is said to be perfecting a +smokeless powder in which the chief ingredients are nitro-amido- and tri- +nitro-benzene. C.O. Lundholm has patented (U.S. Pat, 701,591, 1901) a +smokeless powder containing nitro-glycerine 30, nitro-cellulose 60, diamyl +phthalate 10 (or diamyl phthalate 5, and mineral jelly 5). The diamyl +phthalate is added, with or without the mineral jelly to nitro-glycerine +and nitro-cellulose. + +~Walsrode Powder.~--The smokeless powder known as Walsrode powder consists +of absolutely pure gelatinised nitro-cellulose, grained by a chemical not +a mechanical process, consequently the grains do not need facing with +gelatine to prevent their breaking up, as is the case with many nitro +powders. For this same reason, as well as from the method of getting rid +of the solvent used, the Walsrode has no tendency whatever to absorb +moisture. In fact, it can lie in water for several days, and when taken +out and dried again at a moderate temperature will be found as good as +before. Nor is it influenced by heat, whether dry or damp, and it can be +stored for years without being in the least affected. It is claimed also +that it heats the barrels of guns much less than black powder, and does +not injure them. + +The standard charge is 30 grains, and it is claimed that with this charge +Walsrode powder will prove second to none. A large cap is necessary, as +the grains of this powder are very hard, and require a large flame to +properly ignite them. In loading cartridges for sporting purposes, an +extra felt wad is required to compensate for the small space occupied by +the charge; but for military use the powder can be left quite loose. The +gas pressure of this powder is low (in several military rifles only one- +half that of other nitros), and the recoil consequently small; and it is +claimed that with the slight increase of the charge (from 29 to 30 grs.) +both penetration and initial velocity will be largely increased, whilst +the gas pressure and recoil will not be greater. + +This powder was used at Bisley, at the National Rifle Association's +Meeting, with satisfactory results. It is made by the Walsrode Smokeless +and Waterproof Gunpowder Company. The nitro-cotton is gelatinised by means +of acetic ether, and the skin produced retards burning. The nitro-cotton +is mixed with acetic ether, and when the gelatinisation has taken place, +the plastic mass is forced through holes in a metal plate into strips, +which are then cut up into pieces the size of grains. The M.H. Walsrode +powder is a leaflet powder, light in colour, about 40 grains of which give +a muzzle velocity of 1,350 feet and a pressure of 3 tons. It is, like the +other Walsrode powders, waterproof and heat-proof. + +~Cooppal Powder~ is manufactured by Messrs Cooppal & Co. at their +extensive powder works in Belgium. It consists of nitro-jute or nitro- +cotton, with or without nitrates, treated with a solvent to form a +gelatinised mass. There are a great many varieties of this powder. One +kind is in the form of little squares; another, for use in Hotchkiss guns, +is formed into 3-millimetre cubes, and is black. Other varieties are +coloured with aniline dyes of different colours. + +~Amberite~ is a nitro-cellulose powder of the 42-grain type of sporting +gunpowders, and is manufactured by Messrs Curtis's & Harvey Limited, at +their Smokeless Powder Factory, Tonbridge, Kent. It consists of a mixture +of nitro-cellulose, paraffin, barium, nitrate, and some other ingredients. +It is claimed for this powder that it combines hard shooting with safety, +great penetration, and moderate strain on the gun. It is hard and tough in +grain, and may be loaded like black powder, and subjected to hard friction +without breaking into powder, that it is smokeless, and leaves no residue +in the gun. The charge for 12 bores is 42 grains by weight, and 1-1/8 oz. +or 1-1/16 oz. shot. The powders known as cannonite[A] and ruby powder, +also manufactured by Messrs Curtis's & Harvey Limited, are analogous +products having the same general characteristics. + +[Footnote A: For further details of cannonite, see First Edition, p. 181.] + +~Smokeless Diamond~, also manufactured by the above mentioned firm, is a +nitro-cellulose powder of the 33-grain type of sporting gunpowders. It was +invented by Mr H.M. Chapman. The manufacture of Smokeless Diamond, as +carried out at Tonbridge, is shortly as follows:--The gun-cotton, which is +the chief ingredient of this powder, is first stoved, then mixed with +certain compounds which act as moderators, and after the solvents are +added, is worked up into a homogeneous plastic condition. It then +undergoes the processes of granulation, sifting, dusting, drying, and +glazing. In order to ensure uniformity several batches are blended +together, and stored for some time before being issued for use. + +It is claimed for this powder that it is quick of ignition, the quickness +being probably due to the peculiar structure of the grains which, when +looked at under the microscope, have the appearance of coke. The charge +for a 12 bore is 33 grains and 1-1/16 oz. shot, which gives a velocity of +1,050 feet per second, and a pressure of 3 tons per square inch. + +~Greiner's Powder~ consists of nitro-cellulose, nitro-benzol, graphite, +and lampblack. + +~B.N. Powder.~--This powder is of a light grey or drab colour, perfectly +opaque, and rough to the touch. It consists of a mixture, nitro-cellulose +and the nitrates of barium and potassium. Its composition is as follows:-- + +Insoluble nitro-cellulose 29.13 parts +Soluble nitro-cellulose 41.31 " +Barium nitrate 19.00 " +Potassium nitrate 7.97 " +Sodium carbonate 2.03 " +Volatile matter 1.43 " + +This powder is a modification of the Poudre B., or Vieille's powder +invented for use in the Lebel rifle, and which consisted of a mixture of +the nitro-celluloses with paraffin. + +~Von Foster's Powder~ contains nothing but pure gelatinised nitro- +cellulose, together with a small quantity of carbonate of lime. + +The German ~Troisdorf Powder~ is a mixture of gelatinised nitro-cellulose, +with or without nitrates. + +~Maximite~ is the invention of Mr Hudson Maxim, and is a nitro-compound, +the base being gun-cotton. The exact composition and method of manufacture +are, however, kept secret. It is made by the Columbia Powder Manufacturing +Company, of New York, and in two forms--one for use as a smokeless rifle +powder, and the other for blasting purposes. + +~Wetteren Powder.~--This powder was manufactured at the Royal Gunpowder +Factory at Wetteren, and used in the Belgian service. Originally it was a +mixture of nitro-glycerine and nitro-cellulose, with amyl acetate as +solvent. Its composition has, however, been altered from time to time. One +variety consists chiefly of nitro-cellulose, with amyl acetate as solvent. +It is of a dark brown colour, and of the consistency of indiarubber. It is +rolled into sheets and finally granulated. + +~Henrite~ is a nitro-cellulose powder. + +~Normal Powder.~--The Swedish powder known as "Normal" Smokeless Powder, +and manufactured by the Swedish Powder Manufacturing Company, of +Landskrona, Sweden, and used for some years past in the Swiss Army, is +made in four forms. For field guns of 8.4 calibre, it is used in the form +of cylindrical grains of a yellow colour, of a diameter of .8 to .9 mm. +and density of .790--about 840 grains of it go to one gun. For rifles, it +is used in the form of grey squares, density .750, and 1 grm. equals about +1,014 grains. One hundred rounds of this powder, fired in eighteen +minutes, raised the temperature of the gun barrel 284° F. A nitro- +glycerine powder, fired under the same conditions, gave a temperature of +464° F. + +This powder is said to keep well--a sample kept 3-1/2 years gave as good +results as when first made--is easy to make, very stable, ignites easily, +not very sensitive to shock or friction, is very light, &c. Eight hundred +rounds fired from a heavy gun produced no injury to the interior of the +weapon. Samples kept for eleven months in the moist atmosphere of a +cellar, when fired gave a muzzle velocity of 1,450 ft. secs. and pressure +of 1,312 atmospheres, and the moisture was found to have risen from 1.2 to +1.6 per cent. After twenty-three months in the damp it contained 2 per +cent. moisture, gave a muzzle velocity of 1,478 ft. sees., and pressure of +1,356 atmospheres. In a 7.5 millimetre rifle, 13.8 grm. bullet, and charge +of 2 grms., it gives a muzzle velocity of 2,035 ft. secs. and a pressure +of 2,200 atmospheres. In the 8.4 cm. field-gun, with charge of 600 grms., +and projectile of 6.7 kilogrammes, muzzle velocity was equal to 1,640 ft. +secs. and pressure 1,750. A sample of the powder for use in the .303 M. +rifle, lately analysed by the author, gave the following result:-- + +Gun-cotton 96.21 per cent. +Soluble cotton 1.80 " +Non-nitrated cotton trace. +Resin and other matters 1.99 " + _______ + + 100.00 + +The various forms of powder invented and manufactured by Mr C.F. Hengst +are chiefly composed of nitrated straw that has been finely pulped. The +straw is treated first with acids and afterwards with alkalies, and the +result is a firm fibrous substance which is granulated. It is claimed that +this powder is entirely smokeless and flameless, that it does not foul the +gun nor heat the barrel, and is at the same time 150 per cent. stronger +than black powder. + +The German "Troisdorf" powder consists of nitro-cellulose that has been +gelatinised together with a nitrate. Kolf's powder is also gelatinised +with nitro-cellulose. The powders invented by Mr E.J. Ryves contain nitro- +glycerine, nitro-cotton, castor-oil, paper-pulp, and carbonate of +magnesia. Maxim powder contains both soluble and insoluble nitro- +cellulose, nitro-glycerine, and carbonate of soda. The smokeless powder +made by the "Dynamite Actiengesellschaft Nobel" consists of nitro-starch +70 to 99 parts, and of di- or tri-nitro-benzene 1 to 30 parts. + +An American wood powder, known as Bracket's Sporting Powder, consists of +soluble and insoluble nitro-lignine, mixed with charred lignine, humus, +and nitrate of soda. Mr F.H. Snyder, of New York, is the inventor of a +shell powder known as the "Snyder Explosive," consisting of 94 per cent. +nitro-glycerine, 6 per cent. of soluble nitro-cotton, and camphor, which +is said to be safe in use. Experiments were made with it in a 6-inch +rifled gun, fired at a target 220 yards away, composed of twelve 1-inch +steel plates welded together, and backed with 12-inch and 14-inch oak +beams, and weighing 20 tons. The shots entirely destroyed it. The charge +of explosive used was 10 lbs. in each shell. + +~Comparative Tests of Black and Nitro Powders, from "American Field."~-- +The results given in table below were obtained at the German Shooting +Association's grounds at Coepenick, Berlin. Penetration was calculated by +placing frames, each holding five cards of 1 millimetre in thickness +(equals .03937 inch), and 3 inches apart, in a bee-line, at distances of +20 inches. Velocity, pattern, and penetration were taken at 40 yards from +the muzzle of a 12-gauge choke-bore double-barrel gun. Gas pressure was +taken by a special apparatus. All shells were loaded with 1-1/8 oz. of No. +3 shot, equal to 120 pellets, and the number given below represents the +average number in the 30-inch pattern. The number of sheets passed through +gives the average penetration. One atmosphere equals pressure equal to 1 +kilogramme (2.2 lbs.) on the square centimetre, hence 1,000 atmospheres +equal 2,200 lbs. on the square centimetre. The E.C., Schultze, and +Walsrode powders were loaded in Elcy's special shells, 2-1/2 inches long. +The averages were taken from a large number of shots, and the same series +of shots fired under precisely the same conditions. + + _______________________________________________________________________ +| | | | | | +| | Gas | | | | +| | Pressure. | Velocity. | Pattern. | Penetration. | +|__________________|____________|___________|____________|______________| +| | | | | | +| |Atmospheres.| Metres. | | Sheets. | +| | | | | | +|Fine-grained black| | | | | +|powder, standard | | | | | +|charge | 514.2 | 280 | 78.6 = 66% | 19.O | +| | | | | | +|Coarse-grained | | | | | +|black powder, | | | | | +|standard charge | 473.4 | 281.4 | 78.2 = 65% | 19.4 | +| | | | | | +|Schultze powder, | | | | | +|42 grains | 921.0 | 290.0 | 64.2 = 54% | 20.2 | +| | | | | | +|Schultze powder, | | | | | +|45 grains | 1052.8 | 305.8 | 52.2 = 42% | 20.6 | +| | | | | | +|E.G. smokeless, | | | | | +|42 grains | 920.2 | 298.4 | 81.4 = 67% | 18.8 | +| | | | | | +|Walsrode, | | | | | +|29 grains | 586.4 | 280.6 | 83.0 = 69% | 19.0 | +|__________________|____________|___________|____________|______________| + +Barometer, 760 mm. Thermometer, 30° C. Hydrometer = 65. Wind, S.W. + +~Picric Powders.~--The chief of these is _Melinite_, the composition of +which is not known with certainty. It is believed to be melted picric acid +together with gun-cotton dissolved in acetone or ether-alcohol. Walke +gives the following proportions--30 parts of tri-nitro-cellulose dissolved +in 45 parts of ether-alcohol (2 to 1), and 70 parts of fused and +pulverised picric acid. The ether-alcohol mixture is allowed to evaporate +spontaneously, and the resulting cake granulated. The French claim, +however, that the original invention has been so modified and perfected +that the melinite of to-day cannot be recognised in the earlier product. +Melinite has a yellow colour, is almost without crystalline appearance, +and when ignited by a flame or heated wire, it burns with a reddish-yellow +flame, giving off copious volumes of black smoke. Melinite as at present +used is said to be a perfectly safe explosive, both as regards +manufacture, handling, and storage. + +_Lyddite_,[A] the picric acid explosive used in the British service, is +supposed to be identical with the original melinite, but its composition +has not been made public. + +[Footnote A: Schimose, the Japanese powder, is stated to be identical with +Lyddite and Melinite (_Chem. Centr._, 1906, 1, 1196).] + +Picrates are more often used than picric acid itself in powders. One of +the best known is _Brugère's Powder_, which is a mixture of 54 parts of +picrate of ammonia and 45 parts of saltpetre. It is stable and safe to +manufacture. It has been used in the Chassepôt rifle with good results, +gives little smoke, and a small residue only of carbonate of potash. + +The next in importance is _Designolle's Powder_, made at Bouchon, +consisting of picrate of potash, saltpetre, and charcoal. It was made in +three varieties, viz., for rifles, big guns, and torpedoes and shells. +These powders are made much in the same way as gunpowder. The advantages +claimed for them over gunpowder are, greater strength, comparative absence +of smoke, and freedom from injurious action on the bores of guns. + +_Emmensite_ is the invention of Dr Stephen Emmens, of the United States. +The Emmens "crystals" are produced by treating picric acid with fuming +nitric acid of specific gravity of 1.52. The acid dissolves with the +evolution of red fumes. The liquid, when cooled, deposits crystals, stated +to be different to picric acid, and lustrous flakes. These flakes, when +heated in water, separate into two new bodies. One of these enters into +solution and forms crystals unlike the first, while the other body remains +undissolved. The acid crystals are used mixed with a nitrate. + +Emmensite has been subjected to experiment by the direction of the U.S. +Secretary for War, and found satisfactory. A sample of Emmensite, in the +form of a coarse powder, was first tried in a pistol, and proved superior +in propelling power to ordinary gunpowder. When tested against explosive +gelatine, it did very good work in shattering iron plates. It is claimed +for this explosive that it enjoys the distinction of being the only high +explosive which may be used both for firearms and blasting. This view is +supported by the trials made by the American War Office authorities, and +shows Emmensite to be a useful explosive both for blasting and as a +smokeless powder. Its explosive power, as tested, is 283 tons per square +inch, and its specific gravity is 1.8. + +Abel proposed to use picric acid for filling shells. His _Picric Powder_ +consisted of 3 parts of saltpetre, and 2 of picrate of ammonia. +_Victorite_ consists of chlorate of potash, picric acid, and olive oil, +and with occasionally some charcoal. It has the form of a coarse yellowish +grey powder, and leaves an oily stain on paper, and it is very sensitive +to friction and percussion. The composition is as follows:--KClO_{3} = 80 +parts; picric acid, 110 parts; saltpetre, 10 parts; charcoal, 5 parts. It +is not manufactured in England. _Tschiner's Powder_ is very similar to +Victorite in composition, but contains resin. A list of the chief picric +powders will be found in the late Colonel J.P. Cundill, R.A.'s "Dictionary +of Explosives." + + + + +CHAPTER VII. + +_ANALYSIS OF EXPLOSIVES._ + +Kieselguhr Dynamite--Gelatine Compounds--Tonite--Cordite--Vaseline-- +Acetone--Scheme for Analysis of Explosives--Nitro-Cotton--Solubility Test-- +Non-Nitrated Cotton--Alkalinity--Ash and Inorganic Matter--Determination +of Nitrogen--Lungé, Champion and Pellet's, Schultze-Tieman, and Kjeldahl's +Methods--Celluloid--Picric Acid and Picrates--Resinous and Tarry Matters-- +Sulphuric Acid and Hydrochloric Acid and Oxalic Acid--Nitric Acid-- +Inorganic Impurities--General Impurities and Adulterations--Potassium +Picrate, &c.--Picrates of the Alkaloids--Analysis of Glycerine--Residue-- +Silver Test--Nitration--Total Acid Equivalent--Neutrality--Free Fatty +Acids--Combined Fatty Acids--Impurities--Oleic Acid--Sodium Chloride-- +Determination of Glycerine--Waste Acids--Sodium Nitrate--Mercury +Fulminate--Cap Composition--Table for Correction of Volumes of Gases, for +Temperature and Pressure + + +~Kieselguhr Dynamite.~--The material generally consists of 75 per cent. of +nitro-glycerine and 25 per cent. of the infusorial earth kieselguhr. The +analysis is very simple, and may be conducted as follows:--Weigh out about +10 grms. of the substance, and place over calcium chloride in a desiccator +for some six to eight days, and then re-weigh. The loss of weight gives +the moisture. This will generally be very small, probably never more than +1 per cent., and usually less. + +Mr James O. Handy, in order to save time, proposes to dry dynamite in the +following manner. He places 1 grm. of the material in a porcelain crucible +1 inch in diameter. The crucible is then supported at the bottom of an +extra wide-mouthed bottle of about 600 c.c. capacity. Air, which has been +dried by bubbling through strong sulphuric acid, is now drawn over the +surface of the sample for three hours by means of an ordinary aspirator. +The air should pass approximately at the rate of 10 c.c. per second. The +tube by which the dry air enters the bottle extends to within 1 inch of +the crucible containing the dynamite. An empty safety bottle is connected +with the inlet, and another with the outlet of the wide-mouthed bottle. +The first guards against the mechanical carrying over by the air current +of sulphuric acid from the acid bottle into the sample, whilst the second +prevents spasmodic outbursts of water from the exhaust from reaching the +sample. The method also gave satisfactory results with nitro-glycerine. +The dry substance may now be wrapped in filter paper, the whole weighed, +and the nitro-glycerine extracted in the Soxhlet apparatus with ether. The +ether should be distilled over at least twenty-four times. + +I have found, however, that much quicker, and quite as accurate, results +may be obtained by leaving the dynamite in contact with ether in a small +Erlenmeyer flask for twenty-four hours--leaving it overnight is better-- +and decanting, and again allowing the substance to remain in contact with +a little fresh ether for an hour, and finally filtering through a weighed +filter, drying at 100° C., and weighing. This gives the weight of the +kieselguhr. The nitro-glycerine must be obtained by difference, as it is +quite useless to evaporate down the ethereal solution to obtain it, as it +is itself volatile to a very considerable extent at the temperature of +evaporation of the ether, and the result, therefore, will always be much +too low. The dry guhr can, of course, be examined, either qualitatively or +quantitatively, for other mineral salts, such as carbonate of soda, &c. An +actual analysis of dynamite No. 1 made by the author at Hayle gave-- +Moisture, 0.92 per cent.; kieselguhr, 26.15 per cent.; and nitro- +glycerine, 72.93 per cent., the last being obtained by difference. + +~Nitro-Glycerine.~--It is sometimes desired to test an explosive substance +for nitro-glycerine. If an oily liquid is oozing from the substance, soak +a drop of it in filter paper. If it is nitro-glycerine it will make a +greasy spot. If the paper is now placed upon an iron anvil, and struck +with an iron hammer, it will explode with a sharp report, if lighted it +burns with a yellowish to greenish flame, emitting a crackling sound, and +placed upon an iron plate and heated from beneath, it explodes sharply. + +If a few drops of nitro-glycerine are placed in a test tube, and shaken up +with methyl-alcohol (previously tested with distilled water, to see that +it produces no turbidity), and filtered, on the addition of distilled +water, the solution will become milky, and the nitro-glycerine will +separate out, and finally collect at the bottom of the tube. + +If to a solution of a trace of nitro-glycerine in methyl-alcohol, a few +drops of a solution, composed of 1 volume of aniline, and 40 volumes +sulphuric acid (1.84) be added, a deep purple colour will be produced. +This colour changes to green upon the addition of water. If it is +necessary to determine the nitro-glycerine quantitatively in an explosive, +the scheme on page 213 may be followed. Ether is the best solvent to use. +Nitrogen should be determined in the nitrometer. + +~Gelatine Compounds.~--The simplest of these compounds is, of course, +blasting gelatine, as it consists of nothing but nitro-cotton and nitro- +glycerine, the nitro-cellulose being dissolved in the glycerine to form a +clear jelly, the usual proportions being about 92 per cent. of nitro- +glycerine to 8 per cent. nitro-cotton, but the cotton is found as high as +10 per cent. in some gelatines. Gelatine dynamite and gelignite are +blasting gelatines, with varying proportions of wood-pulp and saltpetre +(KNO_{3}) mixed with a thin blasting gelatine. The method of analysis is +as follows:--Weigh out 10 grms. of the substance, previously cut up into +small pieces with a platinum spatula, and place over calcium chloride in a +desiccator for some days. Reweigh. The loss equals moisture. This is +generally very small. Or Handy's method may be used. The dried sample is +then transferred to a small thistle-headed funnel which has been cut off +from its stem, and the opening plugged with a little glass wool, and round +the top rim of which a piece of fine platinum wire has been fastened, in +order that it may afterwards be easily removed from the Soxhlet tube. The +weight of this funnel and the glass wool must be accurately known. It is +then transferred to the Soxhlet tube and exhausted with ether, which +dissolves out the nitro-glycerine. The weighed residue must afterwards be +treated in a flask with ether-alcohol to dissolve out the nitro-cotton. + +But the more expeditious method, and one quite as accurate, is to transfer +the dried gelatine to a conical Erlenmeyer flask of about 500 c.c. +capacity, and add 250 c.c. of a mixture of ether-alcohol (2 ether to 1 +alcohol), and allow to stand overnight. Sometimes a further addition of +ether-alcohol is necessary. It is always better to add another 300 c.c., +and leave for twenty minutes or so after the solution has been filtered +off. The undissolved portion, which consists of wood-pulp, potassium +nitrate, and other salts, is filtered off through a linen or paper filter, +dried and weighed. + +~Solution.~--The ether-alcohol solution contains the nitro-cotton and the +nitro-glycerine in solution.[A] To this solution add excess of chloroform +(about 100 c.c. will be required), when the nitro-cellulose will be +precipitated in a gelatinous form. This should be filtered off through a +linen filter, and allowed to drain. It is useless to attempt to use a +filter pump, as it generally causes it to set solid. The precipitated +cotton should then be redissolved in ether-alcohol, and again precipitated +with chloroform (20 c.c. of ether-alcohol should be used). This precaution +is absolutely necessary, if the substance has been treated with ether- +alcohol at first instead of ether only, otherwise the results will be much +too high, owing to the gelatinous precipitate retaining very considerable +quantities of nitro-glycerine. The precipitate is then allowed to drain as +completely as possible, and finally allowed to dry in the air bath at 40° +C., until it is easily detached from the linen filter by the aid of a +spatula, and is then transferred to a weighed watch-glass, replaced in the +oven, and dried at 40° C. until constant in weight. The weight found, +calculated upon the 10 grms. taken, gives the percentage of nitro- +cellulose. + +[Footnote A: If the substance has been treated with ether alone in the +Soxhlet, the nitro-glycerine will of course be dissolved out first, and +the ether-alcohol solution will only contain the nitro-cellulose.] + +~The Residue~ left after treating the gelatine with ether-alcohol is, in +the case of blasting gelatine, very small, and will probably consist of +nothing but carbonate of soda. It should be dried at 100° C. and weighed, +but in the case of either gelignite or gelatine dynamite this residue +should be transferred to a beaker and boiled with distilled water, and the +water decanted some eight or ten times, and the residue finally +transferred to a tarred filter and washed for some time with hot water. +The residue left upon the filter is wood-pulp. This is dried at 100° C. +until constant, and weighed. The solution and washings from the wood are +evaporated down in a platinum dish, and dried at 100° C. It will consist +of the potassium nitrate, and any other mineral salts, such as carbonate +of soda, which should always be tested for by adding a few drops of nitric +acid and a little water to the residue, and again evaporating to dryness +and re-weighing. From the difference in weight the soda can be calculated, +sodium nitrate having been formed. Thus-- + +Na_{2}CO_{3} + 2HNO_{3} = 2NaNO_{3} + CO_{2} + H_{2}O. + +Mol. wt. = 106 = 170 + +(170 - 106 = 64) and _x_ = (106 x _d_)/64 + +where _x_ equals grms. of sodium carbonate in residue, and _d_ equals the +difference in weight of residue, before and after treatment with nitric +acid. + +The nitro-glycerine is best found by difference, but if desired the +solutions from the precipitation of the nitro-cellulose may be evaporated +down upon the water bath at 30° to 40° C., and finally dried over CaCl_{2} +until no smell of ether or chloroform can be detected, and the nitro- +glycerine weighed. It will, however, always be much too low. An actual +analysis of a sample of gelatine dynamite gave the following result:-- + +Nitrocellulose (collodion) 3.819 per cent. +Nitro-glycerine 66.691 " +Wood-pulp 16.290 " +KNO_{3} 12.890 " +Na_{2}CO_{3} _Nil._ +Water 0.340 " + +This sample was probably intended to contain 30 per cent. of absorbing +material to 70 per cent. of explosive substances. Many dynamites contain +other substances than the above, such as paraffin, resin, sulphur, wood, +coal-dust, charcoal, also mineral salts, such as carbonate of magnesia, +chlorate of potash, &c. In these cases the above-described methods must of +course be considerably modified. Paraffin, resin, and most of the sulphur +will be found in the ether solution if present. The solution should be +evaporated (and in this case the explosive should in the first case be +treated with ether only, and not ether-alcohol), and the residue weighed, +and then treated on the water bath with a solution of caustic soda. The +resin goes into solution, and is separated by decantation from the +residue, and precipitated by hydrochloric acid, and collected on a tarred +filter (dried at 100° C.), and dried at 100° C. and weighed. The nitro- +glycerine residue is treated with strong alcohol, decanted, and the +residue of paraffin and sulphur washed with alcohol, dried, and weighed. + +To separate the paraffin from the sulphur the residue is heated with a +solution of ammonium sulphide. After cooling the paraffin collects as a +crust upon the surface of the liquid, and by pricking a small hole through +it with a glass rod the liquid underneath can be poured off, and the +paraffin then washed with water, dried, and weighed. Sulphur is found by +difference. Mr F.W. Smith (_Jour. Amer. Chem. Soc._, 1901, 23 [8], +585-589) determines the sulphur in dynamite gelatine as follows:--About 2 +grms. are warmed in a 100 c.c. silver crucible on the water bath with an +alcoholic solution of sodium hydroxide, and where the nitro-glycerine is +decomposed, the liquid is evaporated to dryness. The residue is fused with +40 grms. of KOH and 5 grms. of potassium nitrate, the mass dissolved in +dilute acetic acid and filtered, and the sulphates precipitated in the +usual way. If camphor is present, it can be extracted with bisulphide of +carbon after the material has been treated with ether-alcohol. In that +case the sulphur, paraffin, and resin will also be dissolved. The camphor +being easily volatile, can be separated by evaporation. Let the weight of +the extract, freed from ether-alcohol before treatment with bisulphide of +carbon, equal A, and the weight of extract after treatment with CS_{2} and +evaporation of the same equal B; and weight of the residue which is left +after evaporation of the CS_{2} and the camphor in solution equal C, the +percentage of camphor will be A - B - C. The residue C may contain traces +of nitro-glycerine, resin, or sulphur. + +Camphor may be separated from nitro-glycerine by means of CS_{2}. If the +solution of camphor in nitro-glycerine be shaken with CS_{2}, the camphor +and a little of the nitro-glycerine will dissolve. The bisulphide solution +is decanted, or poured into a separating funnel and separated from the +nitro-glycerine. The two solutions are then heated on the water bath to +20° C. and then to 60° C., and afterwards in a vacuum over CaCl_{2} until +the CS_{2} has evaporated from them. The camphor evaporates, and leaves +the small quantity of nitro-glycerine which had been dissolved with it. +The other portion is the nitro-glycerine, now free from CS_{2}. The two +are weighed and their weights added together, and equals the nitro- +glycerine present. There is a loss of nitro-glycerine, it being partly +evaporated along with the CS_{2}. Captain Hess has shown that it is equal +to about 1.25 per cent. This quantity should therefore be added to that +found by analysis. Morton Liebschutz, in a paper in the _Moniteur +Scientifique_ for January 1893, very rightly observes that the variety of +dynamites manufactured is very great, all of them having a special +composition which, good or bad, is sometimes of so complicated a nature +that the determination of their elements is difficult. + +The determination of nitro-glycerine in simple dynamite No. 1 is easy; but +not so when the dynamite contains substances soluble in ether, such as +sulphur, resin, paraffin, and naphthalene. After detailing at length the +methods he employs, he concludes with the observation that the knowledge +of the use of acetic acid--in which nitro-glycerine dissolves--for the +determination of nitro-glycerine may be serviceable. Mr F.W. Smith[A] +gives the following indirect method of determining nitro-glycerine in +gelatine dynamite, &c. About 15 grms. of the sample are extracted with +chloroform in a Soxhlet apparatus, and the loss in weight determined. In a +second portion the moisture is determined. A third portion of about 2 +grms. is macerated with ether in a small beaker, the ethereal extract +filtered, and the process of extraction repeated three or four times. The +united filtrates are allowed to evaporate spontaneously, and the residue +warmed gently on the water bath with 5 c.c. of ammonium sulphide solution, +and 10 c.c. of alcohol until the nitro-glycerine is decomposed, after +which about 250 c.c. of water and sufficient hydrochloric acid to render +the liquid strongly acid, are added, and the liquid filtered. The +precipitate is washed free from acid, and then washed through the filter +with strong alcohol and chloroform into a weighed platinum dish, which is +dried to constant weight at 50° C. The contents of the dish are now +transferred to a silver crucible, and the sulphur determined. This amount +of sulphur, deducted from the weight of the contents of the platinum dish, +gives the quantity of substances soluble in chloroform with the exception +of the nitro-glycerine, moisture, and sulphur. The amount of the former +substances _plus_ the moisture and sulphur, deducted from the total loss +on extraction with chloroform, gives the quantity of nitro-glycerine. +Nitro-benzene may be detected, according to J. Marpurgo, in the following +manner:--In a porcelain basin are placed two drops of liquid phenol, three +drops of water, and a fragment of potash as large as a pea. The mixture is +boiled, and the aqueous solution to be tested then added. On prolonged +boiling nitro-benzene produces at the edge of the liquid a crimson ring, +which on the addition of a solution of bleaching powder turns emerald- +green. And nitro-glycerine in ether solution, by placing a few drops of +the suspected solution, together with a drop or two of aniline, upon a +watch-glass, evaporating off the ether, and then adding a drop of +concentrated sulphuric acid to the residue, when, if nitro-glycerine is +present, the H_{2}SO_{4} will strike a crimson colour, due to the action +of the aniline sulphate upon the nitric acid liberated from the nitro- +glycerine. + +[Footnote A: "Notes on the Analysis of Explosives," _Jour. Amer. Chem. +Soc._, 1901, 23 [8], 585-589.] + +~Tonite.~--The analysis of this explosive is a comparatively easy matter, +and can be performed as follows:--Weigh out 10 grms., or a smaller +quantity, and boil with water in a beaker, decanting the liquid four or +five times, and filter. The aqueous solution will contain the nitrate of +barium. Then put the residue on the filter, and wash two or three times +with boiling water. Evaporate the filtrate to dryness in a platinum dish. +Dry and weigh. This equals the Ba(NO_{3})_{2}. If the sample is tonite No. +3, and contains di-nitro-benzol, treat first with ether to dissolve out +this substance. Filter into a dish, and evaporate off the ether, and weigh +the di-nitro-benzol, and afterwards treat residue with water as before. +The residue is dried and weighed, and equals the gun-cotton present. It +should then be treated with a solution of ether-alcohol in a conical +flask, allowed to stand some three hours, then filtered through a weighed +filter paper, dried at 40° C., and weighed. This will give the gun-cotton, +and the difference between this last weight and the previous one will give +the collodion-cotton. A portion of the residue containing both the gun- +cotton and the soluble cotton can be tested in the nitrometer, and the +nitrogen determined. + +~Cordite.~--This explosive consists of gun-cotton (with a little +collodion-cotton in it as impurity), nitro-glycerine, and vaseline--the +proportions being given as 30 per cent. nitro-glycerine, 65 per cent. gun- +cotton, and 5 per cent. vaseline. Its analysis is performed by a +modification of the method given for gelatines. Five grms. may be +dissolved in ether-alcohol in a conical flask, allowed to stand all night, +and then filtered through a linen filter. The residue is washed with a +little ether, pressed, and dried at 40° C., and weighed. It equals the +gun-cotton. The solution contains the nitro-glycerine, soluble cotton, and +vaseline. The cotton is precipitated with chloroform, filtered off, dried, +and weighed. The two ether-alcohol solutions are mixed, and carefully +evaporated down in a platinum dish upon the water bath at a low +temperature. The residue is afterwards treated with strong 80 per cent. +acetic acid, which dissolves out any nitro-glycerine left in it. The +nitro-glycerine is then obtained by difference, or the method suggested to +me privately by Mr W.J. Williams may be used. The residue obtained by +evaporation of the ether-alcohol solution, after weighing, is treated with +alcoholic potash to decompose the nitro-glycerine, water is added and the +alcohol evaporated off. Some ether is then added, and the mixture shaken, +and the ether separated and evaporated, and the residue weighed as +vaseline. + +The moisture should, however, be determined by the method devised by Mr +Arthur Marshall, F.I.C., of the Royal Gunpowder Works, Waltham Abbey, +which is carried out as follows:--The cordite or other explosive is +prepared in the manner laid down for the Abel heat test, that is t say, it +is ground in a small mill, and that portion is selected which passes +through a sieve having holes of the size of No. 8 wire gauge, but not +through one with holes No. 14 wire gauge. + +[Illustration: FIG. 40.--MARSHALL'S APPARATUS FOR MOISTURE IN CORDITE.] + +The form of apparatus used is shown in Fig. 40. It consists of an +aluminium dish A, having the dimensions shown, and the glass cone B +weighing not more than 30 grms. Five grms. of the cordite are weighed into +the aluminium dish A. This is covered with the cone B, and the whole is +accurately weighed, and is then placed upon a metal plate heated by steam +from a water bath. It is left upon the bath until all the moisture has +been driven off, then it is allowed to cool for about half-an-hour in a +desiccator and is weighed. The loss in weight gives accurately the +moisture of the sample. For cordite of the original composition, one +hour's heating is sufficient to entirely drive off the moisture; for +modified cordite containing 65 per cent. of gun-cotton, two hours is +enough, provided that there be not more than 1.3 per cent. of moisture +present. + +If the proportion of nitro-glycerine be higher, a longer heating is +necessary. The aluminium dish must not be shallower than shown in the +figure, for if the distance between the substance and the edge of the +glass cone be less than half an inch, some nitro-glycerine will be lost. +Again, the sample must not be ground finer than stated, else some of the +moisture will be lost in the grinding and sieving operations, and the +result will be too low. In order to be able to drive off all the moisture +in the times mentioned, it is essential that the glass cone shall not fit +too closely on the aluminium dish, consequently the horizontal ledge round +the top of the dish should be bent, so as to render it slightly untrue, +and leave a clearance of about 0.02 inch in some places. If these few +simple precautions be taken, the method will be found to be very accurate. +Duplicate determinations do not differ more than 0.01 per cent.[A] + +[Footnote A: "Determination of Moisture in Nitro-glycerine Explosives," by +A. Marshall, _Jour. Soc. Chem. Ind._, Feb. 29, 1904, p. 154.] + +~The Vaseline~ (C_{16}H_{34}), or petroleum jelly, used has a flash-point +of 400° F. It must not contain more than 0.2 per cent. volatile matter +when heated for 12 hours on the water bath, and should have a specific +gravity of 0.87 at 100° F., and a melting point of 86° F. It is obtained +during the distillation of petroleum, and consists mainly of the portions +distilling above 200° C. It boils at about 278° C. + +~Acetone~ (CH_{3}CO.CH_{3}), or dimethyl ketone, is formed when iso-propyl +alcohol is oxidised with potassium bichromate and sulphuric. It is also +produced in considerable quantities during the dry distillation of wood, +and many other organic compounds. Crude wood spirit, which has been freed +from acetic acid, consists in the main of a mixture of acetone and methyl- +alcohol. The two substances may be roughly separated by the addition of +calcium chloride, which combines with the methyl-alcohol. On subsequent +distillation crude acetone passes over, and may be purified by conversion +into the bisulphite compound. + +Acetone is usually prepared, however, by the dry distillation of crude +calcium or barium acetate. + +(CH_{3}.COO)_{2}Ca = CH_{3}.CO.CH_{3} + CaCO_{3}. + +The distillate is fractionated, and the portion, boiling between 50° and +60° C., mixed with strong solution of sodium bisulphite. The crystalline +cake of acetone sodium bisulphite, which separates on standing, is well +pressed, to free it from impurities, decomposed by distillation with +dilute sodium carbonate, and the aqueous distillate of pure acetone +dehydrated over calcium chloride. Acetone is a colourless, mobile liquid +of sp. gr. .792 at 20° C., it boils at 56.5° C., has a peculiar, pleasant, +ethereal odour, and is mixible with water, alcohol, and ether in all +proportions. + +The acetone used in the manufacture of cordite should conform to the +following specification:-- + +SPECIFICATION FOR ACETONE. + +1. The acetone to be not more than 0.802 specific gravity at 60° F. When +mixed with distilled water it must show no turbidity, and must leave no +residue on evaporation at 212° F. On distillation, four-fifths by volume +of the quantity taken must distil over at a temperature not exceeding 138° +F. The residual matter left after this distillation must not contain, +besides acetone, any ingredient that is not a bye-product incidental to +the manufacture of acetone. + +2. One c.c. of 0.10 per cent. solution in distilled water of pure +permanganate of potash, added to 100 c.c. of the acetone, must retain its +distinctive colour for not less than 30 minutes. This test should be made +at a temperature of 60° F. + +3. The acetone tested by the following method must not show more than +0.005 per cent. of acid, calculated to acetic acid:-- + +To 50 c.c. of the sample diluted with 50 c.c. of distilled water, with 2 +c.c. of phenol-phthalein solution (1 gramme to 1,000 c.c. of 50 per cent. +alcohol) added as an indicator, add from a burette N/100 sodium hydrate +solution (1 c.c. 0.0006 gramme acetic acid), and calculate to acetic acid +in the usual manner. + +The water used for the dilution of the acetone must be carefully tested +for acidity, and the pipettes used for measuring should not be blown out, +as it would be possible thus to neutralise nearly 2 c.c. of the soda +solution. + +The presence of water in a sample of acetone may be detected by Schweitzer +and Lungwitz's method (_Chem. Zeit._, 1895, xix., p. 1384), which consists +in shaking together equal volumes of acetone and petroleum ether (boiling +point, 40° to 60° C.), when if present a separation of the liquid in +layers will take place. + +~Estimation of Acetone.~--Kebler (_Jour. Amer. Chem. Soc._, 1897, 19, 316- +320) has improved Squibb's modification of Robineau and Rollins' method. +The following solutions are required:-- + +(1.) A 6 per cent. solution of hydrochloric acid. + +(2.) A decinormal solution of sodium thiosulphate. + +(3.) Alkaline potassium iodide solution prepared by dissolving 250 grms. +of potassium iodide in water, made up to a litre; dissolving 257 grms. of +sodium hydroxide (by alcohol) in water, likewise made up to a litre. After +allowing the latter to stand, 800 c.c. of the clear solution are added to +the litre of KI. + +(4.) Sodium hypochlorite solution: 100 grms. of bleaching powder (35 per +cent.) are mixed with 400 c.c. of water: to this is added a hot solution +of 120 grms. of crystallised sodium carbonate in 400 c.c. of water. After +cooling, the clear liquid is decanted, the remainder filtered, and the +filtrate made up to a litre; to each litre is added 25 c.c. of sodium +hydroxide solution (sp. gr. 1.29). + +(5.) An aqueous solution of the acetone, containing 1 or 2 per cent. of +acetone. + +(6.) Bicarbonated starch solution prepared by treating 0.125 grm. of +starch with 5 c.c. of cold water, then adding 20 c.c. of boiling water, +boiling a few minutes, cooling, and adding 2 grms. of sodium bicarbonate. + +To 20 c.c. of the potassium iodide solution are added 10 c.c. of the +diluted aqueous acetone, an excess of the sodium hypochlorite solution is +then run in from a burette and well shaken for a minute. The mixture is +then acidified with the hydrochloric acid solution, and while agitated, an +excess of sodium thiosulphate solution is added, the mixture being +afterwards allowed to stand a few minutes. The starch indicator is then +added, and the excess of thiosulphate re-titrated. The relation of the +sodium hypochlorite solution to the sodium thiosulphate being known, the +percentage of acetone can be readily calculated.[A] + +[Footnote A: See "The Testing of Acetone," Conroy, _Jour. Soc. Chem. +Ind._, 31st March 1900, vol. xix.] + +Dr S.J.M. Auld has recently (_Jour. Chem. Soc._, Feb. 15, 1906, vol. xxv.) +worked out a volumetric method for the estimation of acetone, depending on +the formation of bromoform, and its subsequent hydrolysis with alcoholic +potash. The hydrolysis is probably expressed thus-- + +3CHBr_{3} + 9KOH + C_{2}H_{5}OH = 3CO + C_{2}H_{4} + 9KBr + 7H_{2}O + +as it has been shown by Hermann and Long that exactly 3 volumes of carbon +monoxide to 1 of ethylene are evolved. The residual potassium bromide is +estimated by means of standard silver nitrate solution. Bromoform is +specially suitable for this purpose for several reasons. It is very +readily formed by the action of bromine and potash on acetone, and +although very volatile in steam, it is not liable to loss due to its own +evaporation. Further, its high molecular weight and large percentage of +bromine conduce to accurate results, 58 grms. of acetone being responsible +for the formation of 357 grms. of KBr. The method of carrying out the +analysis is as follows:-- + +A known quantity of the solution to be tested, containing acetone to the +extent of 0.1 to 0.2 grm., is pipetted into a 500 c.c. round-bottom flask, +diluted with a little water, and mixed with 20 to 30 c.c. of a 10 per +cent. solution of caustic potash. The flask is connected with a long +reflex condenser, and is also fitted with a dropping funnel containing a +solution of bromine in potassium bromide (200 grms. of Br and 250 grms. of +KBr to 1 litre of water). The bromine solution is allowed to flow into the +mixture until it has acquired a faint yellow tinge, the flask and its +contents being then heated on the water bath at about 70° C. for half-an- +hour. Bromine solution is added drop by drop until the slight coloration +is permanent, excess of bromine being got rid of by boiling for a minute +or two with a little more caustic potash. The mixture is then distilled +until the distillate is free from bromoform, halogen being tested for in +the usual manner. Water is added to the contents of the flask if +necessary. It may be here observed that no acetone can be detected in the +distillate by means of the mercuric oxide test, and free bromine is also +absent. The condenser having been washed out with a little alcohol, in +order to remove any traces of bromoform which may have collected, the +distillate and washings are mixed with 50 c.c. of alcohol and sufficient +solid caustic potash to make an approximately 10 per cent. solution. The +mixture is then heated on the water bath under a reflux condenser until +the bromoform is completely decomposed. This generally occupies about +three-quarters of an hour. The liquid is allowed to cool, evaporated to +smaller bulk if necessary, and exactly neutralised with dilute nitric +acid. It is then diluted with water to 500 c.c., and an aliquot part +titrated with N/10 silver nitrate solution, using potassium chromate as +indicator; 240 parts of bromine correspond to 58 parts of acetone. The +complete analysis can be performed in one and a half to two hours. It is +imperative that the bromine used should be pure, as crude bromine +frequently contains bromoform. The method is suitable for the estimation +of acetone in wood-spirit, the spirit being diluted to 10 times its +volume, and 5 c.c. of this solution employed for the determination. For +example-- + +(1.) Three c.c. of a solution containing 9.61 per cent. acetone gave +1.7850 grm. KBr. Acetone found = 9.66 per cent. + +(2.) Ten c.c. of a solution containing 0.96 per cent. acetone gave 0.5847 +grm. KBr. Acetone found = 0.95 per cent. + +~Nitro-Cotton.~--The first thing upon opening a case of wet cotton, or in +receiving a sample from the "poacher," that requires to be determined is +the percentage of water that it contains. It is best done by weighing out +about 1,000 grms. upon a paper tray, which has been previously dried in +the oven at 100° C. for some time, and become constant in weight. The +trayful of cotton is then placed in a water oven, kept at 100° C., and +dried as long as it loses water. The loss gives the percentage of water. +It varies from 20 to 30 per cent. as a rule in "wet" cotton. + +OUTLINE SCHEME FOR THE ANALYSIS OF NITRO-EXPLOSIVES + _______________________________________________________________________ +| | +| Exhaust dried substance with Anhydrous Ether in Soxhlet's Fat | +| Extraction Apparatus. | +|_______________________________________________________________________| +| | +| _Solution_--Divide into two parts ~A.~ and ~B.~ | +|_______________________________________________________________________| +| | +| ~A.~ | +| | +| Allow ether to evaporate spontaneously. Dry residue in vacuo over | +| H_{2}SO_{4} and weigh. Equals nitro-glycerine, resin, camphor, and | +| paraffin. | +| | +| The nitro-glycerine in this residue may be decomposed by heating | +| with a solution of alcoholic potash. Water may then be added, and the | +| alcohol evaporated off on the water bath. From this solution the | +| resin may be precipitated by HCl, filtered off, dried, and weighed. | +| Solution containing the paraffin is treated with AmS solution and | +| heated. On cooling the paraffin separates, and may be separated. | +| Residue may be shaken with CS_{2} to remove camphor. | +|_______________________________________________________________________| +| | +| ~B.~ | +| | +| Add phenol-phthalein and titrate with alcoholic potash, 1 c.c. normal | +| KHO = .330 grm. _resin_, and add considerably more KHO. Evaporate, | +| dissolve residue in water, shake with ether, and separate. | +|_______________________________________________________________________| +| | +| _Ethereal Solution_ evaporated leaves paraffin. | +|_______________________________________________________________________| +| | +| _Aqueous Solution_-- | +| Add bromide, acidify with HCl, separate any resin and precipitate, | +| filtrate with BaCl_{2} BaSO_{4} x .1373 = Sulphur. | +|_______________________________________________________________________| +| | +| _Residue_-- | +| Dry, weigh, and exhaust with water preferably in Soxhlet. | +|_______________________________________________________________________| +| | | +| _Solution_-- | _Residue_-- | +| Contains metallic | Dry, weigh, and agitate an aliquot part with | +| nitrates, chlorates, | with H_{2}SO_{4} and Hg in nitrometer. If | +| soluble carbonates, | nitro-cellulose is present, treat remainder of | +| the sum of which | residue with ether-alcohol. | +| (except AmCO_{3}) |________________________________________________| +| can be determined by | | +| evaporating down at | _Solution_-- | +| 100° C. to dryness | Evaporate and weigh. Residue consists of | +| and weighing. | soluble nitro-cellulose. | +| Nitrates can be |________________________________________________| +| determined by | | +| | _Residue_-- | +| | Dry and weigh and determine hexa-nitro- | +| | cellulose in nitrometer, if present. Exhaust | +| | remainder with acetic ether. | +| |________________________________________________| +| | | | +| | _Solution_-- | _Residue_-- | +| | Hexa-nitro-cellulose | Dry and weigh, ignite | +| | (Gun cotton). | and reweigh. Loss = | +| | | _Cellulose_. | +| | |_________________________| +| | | | +| | | Residue consists of | +| | | sawdust, charcoal, | +| | | coal, chalk, guhr, | +| | | or mineral matter, &c. | +|______________________|______________________|_________________________| + +NOTE.--Camphor is found by difference. Sulphur is only partially soluble +in ether. It is better, therefore, to extract some of the original +substance with water, and treat residue with alcoholic KHO. Add bromide, +acidify, and precipitate as BaSO. + +~The Solubility Test.~--The object of this test is to ascertain, in the +case of gun-cotton, the percentage of soluble (penta and lower nitrates) +cotton that it contains, or in the case of soluble cotton, the quantity of +gun-cotton. The method of procedure is as follows:--Five grms. of the +sample which has been previously dried at 100° C., and afterwards exposed +to the air for two hours, is transferred to a conical flask, and 250 c.c. +ether-alcohol added (2 ether to 1 alcohol). The flask is then corked and +allowed to digest, with repeated shaking, for two or three hours. The +whole is then transferred to a linen filter, and when the solution has +passed through the filter, is washed with a little ether, and pressed in a +hand-screw press between folds of filter paper. The sample is then +returned to the flask, and the previous treatment repeated, but it will be +sufficient for it to digest for one hour the second time. The filter is +then again pressed first gently by hand, then in the press, and afterwards +opened up and the ether allowed to evaporate. The gun-cotton is then +removed from the filter and transferred to a watch-glass, and dried in the +water oven at 100° C. When dry it is exposed to the air for two hours and +weighed. It equals the amount of gun-cotton and unconverted cotton in the +5 grms. The unconverted cotton must be determined in a separate 5 grms. +and deducted. + +The method of determining the soluble cotton now used in the Government +laboratories is as follows:--Fifty grains of the nitro-cotton are +dissolved in 150 c.c. of ether-alcohol, and allowed to stand, with +frequent shakings, in a 200 c.c. stoppered measure for six hours; 75 c.c. +of the clear solution are then drawn off by the aid of a pipette and +evaporated in a dish on the water bath, and finally in the water oven at +120° F. (49° C.), until constant in weight. The weight found equals the +quantity of soluble cotton in the 75 c.c., which, multiplied by 4, equals +the percentage, thus: Suppose that 2.30 grains was the weight found, then + +(2.3 x 150)/75 = 4.6 in 50 = 9.20 per cent. + +A method for the determination of soluble nitro-cellulose in gun-cotton +and smokeless powder has been published by K.B. Quinan (_Jour. Amer. Chem. +Soc._, 23 [4], 258). In this method about 1 grm. of the finely divided dry +sample to be analysed is placed in an aluminium cup 1.9 inch in diameter +and 4-1/8 inch deep. It is then covered and well stirred with 50 c.c. of +alcohol, 100 c.c. of ether are then added, and the mixture is stirred for +several minutes. After removing the stirrer, the cup is lightly covered +with an aluminium lid, and is then placed in the steel cup of a +centrifugal machine, which is gradually got up to a speed of 2,000 +revolutions per minute, the total centrifugal force at the position +occupied by the cups (which become horizontal when in rapid rotation) is +about 450 lbs. They are rotated at the full speed for ten to twelve +minutes, and the machine is then gradually stopped. By this time the whole +of the insoluble matter will be at the bottom of the cup, and the +supernatant solution will be clear. It is drawn off to within a quarter of +an inch of the bottom (without disturbing the sediment), with the aid of a +pipette. + +Care must be taken that the solution thus withdrawn is perfectly clear. +About 10 to 15 c.c. of colloid solution and a film of insoluble matter +remain at the bottom of the cup; these are stirred up well, the stirrer is +rinsed with ether-alcohol, about 50 c.c. of fresh ether-alcohol are added; +the mixture is again treated in the centrifugal apparatus for about eight +minutes; the whole washing process is then repeated until all soluble +matter has been removed. This may require about seven or eight (or for +samples with much insoluble matter ten or twelve or more) washings, but as +the extraction proceeds, the period of rotation may be somewhat reduced. +After extraction is completed, the insoluble matter is transferred to a +Gooch crucible with the usual asbestos pad, dried at 100° C., and weighed. +The residue may, if wished, be dried and weighed in the aluminium cup, but +then it cannot be ignited. The whole time for an analysis exclusive of +that required for drying, is from one to two hours--average time, 1-1/4 +hour. The results are satisfactory both as to accuracy and rapidity. +Acetone-soluble nitro-cellulose may be determined by the same method. + +~The Unconverted or Non-nitrated Cotton.~--However well the cotton has +been nitrated, it is almost certain to contain a small quantity of non- +nitrated or unconverted cotton. This can be determined thus:--Five grms. +of the sample are boiled with a saturated solution of sodium sulphide, and +then allowed to stand for forty-eight hours, and afterwards filtered or +decanted, and again boiled with fresh solutions of sulphide, and again +filtered, washed first with dilute HCl and then with water, dried, and +weighed. The residue is the cellulose that was not nitrated, plus ash, &c. +It should be ignited, and the weight of the ash deducted from the previous +weight. + +Acetone, and acetic-ether (ethyl-acetate) may also be used as solvents for +the nitro-cellulose. Another process is to boil the gun-cotton, &c., in a +solution of sodium stannate made by adding caustic soda to a solution of +stannous chloride, until the precipitate first formed is just +re-dissolved. This solution dissolves the cellulose nitrates, but does not +affect the cellulose. Dr Lungé found the following process more +satisfactory in the case of the more highly nitrated products:--The +reagent is an alcoholic solution of sodium-ethylate prepared by dissolving +2 to 3 grms. of sodium in 100 c.c. of 95 per cent. alcohol, and mixing the +filtered solution with 100 c.c. of acetone. It has no effect upon +cellulose, but decomposes nitro-cellulose with the formation of a reddish +brown compound, which is soluble in water. In the determination, 5 grms. +of gun-cotton are heated to 40° or 50° C. on the water bath with 150 c.c. +of the reagent, the liquid being shaken at intervals for twenty to thirty +minutes; or the mixture may be allowed to stand for a few hours at the +ordinary temperature. The brown-red solution is decanted from the +undissolved residue, and the latter washed with alcohol and with water, by +decantation, and then on the filter with hot water, to which a little +hydrochloric acid is added for the final washings. For ordinary work this +cellulose is dried immediately and weighed, but in exact determinations it +is washed with alcohol, again treated with 50 c.c. of the reagent, and +separated and washed as before. The cellulose thus obtained, gives no +trace of gas in the nitrometer, and duplicate determinations agree within +0.1 to 0.2 per cent. when the weight of unchanged cellulose amounts to +about 0.2 grm. Gun-cotton, which is completely soluble in acetone, +contains only traces of cellulose, and when as much as 0.85 per cent. is +present it does not dissolve entirely. This method is not applicable to +the determination of cellulose in lower nitrated products, and Dr Lungé +attributes this to the fact that these being prepared with less +concentrated acid invariably contain oxy-cellulose. + +~Alkalinity.~--Five grms. of the air-dried and very finely divided sample +are taken from the centre of the slabs or discs, and digested with about +20 c.c. of N/2 hydrochloric acid, and diluted with water to about 250 +c.c., and shaken for about fifteen minutes. The liquid is then decanted, +and washed with water until the washings no longer give an acid reaction. +The solution, together with the washings, are titrated with N/4 sodium +carbonate, using litmus as indicator. + +~Ash and Inorganic Matter.~--This is best determined by mixing 2 or 3 +grms. of the nitro-cotton in a platinum crucible with shavings of +paraffin, heating sufficiently to melt the paraffin, and then allowing the +contents of the crucible to catch fire and burn away quietly. The +temperature is then raised, and the carbonaceous residue incinerated, +cooled, weighed, &c., and the percentage of ash calculated. Schjerning +proceeds in the following way:--He takes 5 grms. of the nitro-cotton in a +large platinum crucible, he then moistens it with a mixture of alcohol and +ether, in which paraffin has been dissolved to saturation, and filtered +and mixed with one-fourth of its volume of water. Some fragments of solid +paraffin are then added, and the ether set on fire. Whilst this is in +progress the crucible is kept in an oblique position, and is rotated so +that the gun-cotton may absorb the paraffin uniformly. The partially +charred residue is now rubbed down with a rounded glass rod, and the +crucible is covered and heated for from fifteen to twenty minutes over the +blow-pipe, the lid being occasionally removed. The residue is soon +converted into ash, which is weighed, and then washed out into a porcelain +basin and treated with hydrochloric acid heated to 90° C. The oxide of +iron, alumina, lime, and magnesia are thus dissolved, and the silica +remains as insoluble residue. The rest of the analysis is conducted +according to the well-known methods of separation. The percentage of ash +as a whole is generally all that is required. + +~Examination of Nitrated Celluloses with Polarised Light.~--Dr G. Lungé +(_Jour. Amer. Chem. Soc._, 1901, 23 [8], 527) has formed the following +conclusions:--The most highly nitrated products appear blue in polarised +light, but those containing between 13.9 and 13.0 per cent. of nitrogen +cannot be distinguished from each other by polarisation. As the percentage +of nitrogen rises, the blue colour becomes less intense, and here and +there grey fibres can be observed, though not in proportion to the +increase in the nitrogen. Below 12.4 per cent. of nitrogen, the fibres +show a grey lustre, which usually appears yellow when the top light is cut +off. Below 10 per cent. of nitrogen, the structure is invariably partially +destroyed and no certain observations possible. It is only possible to +distinguish with certainty, firstly any unchanged cellulose by its +flashing up in variegated (rainbow) colours; and secondly, highly nitrated +products (from 12.75 per cent. N upwards), by their flashing up less +strongly in blue colours. The purple transition stage in the fibres +containing over 11.28 per cent. of N (Chardonnet) was not observed by Dr +Lungé. + +~Determination of Nitrogen by Lungé Nitrometer.~--The determination of the +percentage of nitrogen in a sample of gun-cotton or collodion is perhaps +of more value, and affords a better idea of its purity and composition, +than any of the foregoing methods of examination, and taken in conjunction +with the solubility test, it will generally give the analyst a very fair +idea of the composition of his sample. If we regard gun-cotton as the +hexa-nitro-cellulose, the theoretical amount of nitrogen required for the +formula is 14.14 per cent., and in the same way for collodion-cotton, +which consists of the lower nitrates, chiefly, however, of the penta- +nitrate, the theoretical nitrogen is 12.75 per cent., so that if in a +sample of nitro-cotton the nitrogen falls much lower than 14 per cent., it +probably contains considerable quantities of the lower nitrates, and +perhaps some non-nitrated cellulose as well (C_{6}H_{10}O_{5})_{x}, which +of course would also lower the percentage of nitrogen. + +The most expeditious method of determining the nitrogen in these nitro +bodies is by the use of Lungé's nitrometer (Fig. 41), and the best way of +working the process is as follows:--Weigh out with the greatest care 0.6 +grm. of the previously dried substance in a small weighing bottle of about +15 c.c. capacity, and carefully add 10 c.c. of concentrated sulphuric acid +from a pipette, and allow to stand until all the cotton is dissolved. The +nitrometer should be of a capacity 150 to 200 c.c., and should contain a +bulb of 100 c.c. capacity at the top, and should be fitted with a Greiner +and Friederich's three-way tap. When the nitro-cotton has entirely +dissolved to a clear solution, raise the pressure tube of the nitrometer +so as to bring the mercury in the measuring tube close up to the tap. Open +the tap in order to allow of the escape of any air bubbles, and clean the +surface of the mercury and the inside of the cup with a small piece of +filter paper. Now close the tap, and pour the solution of the nitro-cotton +into the cup. Rinse out the bottle with 15 c.c. of sulphuric acid, +contained in a pipette, pouring a little of the acid over the stopper of +the weighing bottle in case some of the solution may be on it. Now lower +the pressure tube a little, just enough to cause the solution to flow into +the bulb of the measuring tube, when the tap is slightly opened. When the +solution has run in almost to the end, turn off the tap, wash down the +sides of the bottle, and add to the cup of the nitrometer; allow it to +flow in as before, and then wash down the sides of the cup with 10 c.c. of +sulphuric acid, adding little by little, and allowing each portion added +to flow into the bulb of the nitrometer before adding the next portion. +Great care is necessary to prevent air bubbles obtaining admission, and if +the pressure tube is lowered too far, the acid will run with a rush and +carry air along with it. + +[Illustration: FIG. 41.--ORDINARY FORM OF LUNGÉ NITROMETER.] + +The solution being all in the measuring tube, the pressure tube is again +slightly raised, and the tube containing the nitro-cotton solution shaken +for ten minutes with considerable violence. It is then replaced in the +clamp, and the pressure relieved by lowering the pressure tube, and the +whole apparatus allowed to stand for twenty minutes, in order to allow the +gas evolved to assume the temperature of the room. A thermometer should be +hung up close to the bulb of the measuring tube. At the end of the twenty +minutes, the levels of the mercury in the pressure and measuring tubes are +equalised, and the final adjustment obtained by slightly opening the tap +on the measuring tube (very slightly), after first adding a little +sulphuric acid to the cup, and observing whether the acid runs in or moves +up. This must be done with very great care. When accurately adjusted, it +should move neither way. Now read off the volume of the NO gas in cubic +centimetres from the measuring tube. Read also the thermometer suspended +near the bulb, and take the height of the barometer in millimetres. The +calculation is very simple. + +EXAMPLE--COLLODION-COTTON. + +0.6[A] grm. taken. Reading on measuring tube = 114.6 c.c. NO. Barometer-- +758 mm. Temperature--15° C. + +[Footnote A: 0.5 grm. is enough in the case of gun-cotton.] + +Since 1 c.c. NO = 0.6272 milligramme N, and correcting for temperature and +pressure by the formula + +760 x (1 + _d_^{2}) (_d_ = .003665), for temperature 15° = 801.78,[A] + +then + +(114.6 x 100 x 750 x .6272)/(801.7 x. 6) = 11.22 per cent. nitrogen. + +[Footnote A: See Table, page 244.] + +The nitrogen in nitro-glycerine may of course be determined by the +nitrometer, but in this case it is better to take a much smaller quantity +of the substance. From 0.1 to 0.2 grm. is quite sufficient. This will give +from 30 to 60 c.c. of gas, and therefore a measuring tube without a 100 +c.c. bulb must be used. + +EXAMPLE. + +0.1048 grm. nitroglycerine taken gave 32.5 c.c. NO. Barometer, 761 mm. +Temperature, 15° C. + +Therefore, + +(3.25 x 100 x 761 x .6272)/(801.78 x.1048) = 18.46 per cent. N. Theory = +18.50 per cent. + +Professor Lungé has devised another form of nitrometer (Fig. 42), very +useful in the nitrogen determination in explosives. It consists of a +measuring tube, which is widened out in the middle to a bulb, and is +graduated above and below into 1/10 c.c. The capacity of the whole +apparatus is 130 c.c.; that of each portion of the tube being 30 c.c., and +of the bulb 70 c.c. The upper portion of the graduated tube serves to +measure small volumes of gas, whilst larger volumes are read off on the +lower part. + +[Illustration: FIG. 42. FIG. 43. SOME NEW FORMS OF NITROMETER.] + +F.M. Horn (_Zeitschrift für angewandte Chemie_, 1892, p. 358) has devised +a form of nitrometer (Fig. 43) which he has found especially useful in the +examination of smokeless powders. The tap H is provided with a wide bore +through which a weighed quantity of the powder is dropped bodily into the +bulb K. From 4 to 5 c.c. of sulphuric acid which has been heated to 30° C. +are then added through the funnel T, the tap H being immediately closed. +When the powder has dissolved--a process which may be hastened by warming +the bulb very carefully--the thick solution is drawn into the nitrometer +tube N, and the bulb rinsed several times with fresh acid, after which +operation the analysis is proceeded with in the usual way. + +Dr Lungé's method of using a separate nitrometer in which to measure the +NO gas evolved to the one in which the reaction has taken place, the gas +being transferred from the one to the other by joining them by means of +indiarubber tubing, and then driving the gas over by raising the pressure +tube of the one containing the gas, the taps being open, I have found to +be a great improvement. + +1 c.c. NO gas at 0° and 760 mm. +Equals 0.6272 milligrammes (N) nitrogen. + " 1.343 " nitric oxide. + " 2.820 " (HNO_{3}) nitric acid. + " 3.805 " (NaNO_{3}) sodium nitrate. + " 4.523 " (KNO_{3}) potassium nitrate. + +~Champion and Pellet's Method.~--This method is now very little used. It +is based upon the fact that when nitro-cellulose is boiled with ferrous +chloride and hydrochloric acid, all the nitrogen is disengaged as nitric +oxide (NO). It is performed as follows:--A vacuum is made in a flask, +fitted with a funnel tube, with a glass stopper on the tube; a delivery +tube that can also be closed, and which dips under a solution of caustic +soda contained in a trough, and the end placed under a graduated tube, +also full of caustic soda. From 0.12 to 0.16 grm. cotton dissolved in 5 to +6 c.c. of sulphuric acid is allowed to flow into the flask, which contains +the ferrous chloride and hydrochloric acid, and in which a vacuum has been +formed by boiling, and then closing the taps. The solution is then heated, +the taps on the delivery tube opened, and the end placed under the +collecting tube, and the NO evolved collected. The NO gas is not evolved +until the solution has become somewhat concentrated. Eder substituted a +solution of ferrous sulphate in HCl for ferrous chloride. Care must be +taken that the flask used is strong enough to stand the pressure, or it +will burst. + +The same chemists (_Compt. Rendus_, lxxxiii. 707) also devised the +following method for determining the NO_{2} in nitro-glycerine:--A known +quantity of a solution of ferrous sulphate of previously ascertained +reducing power is placed in a flask, acidified with hydrochloric acid, and +its surface covered with a layer of petroleum oil. About .5 grm. of the +nitro-glycerine is then introduced, and the flask heated on the water +bath. When the sample is completely decomposed, the liquid is heated to +boiling to remove nitric oxide, and the excess of ferrous sulphate +ascertained by titration with standard permanganate; 56 of iron (Fe) +oxidised by the sample correspond to 23 of NO_{2} in the sample of +nitro-glycerine. + +~The Schultze-Tieman Method~ for determining nitrogen in nitro-explosives, +especially nitro-cellulose and nitro-glycerine.--The figure (No. 44) shows +the general arrangement of the apparatus. I am indebted for the following +description of the method of working it to my friend, Mr William Bate, of +Hayle. To fill the apparatus with the soda solution, the gas burette is +put on the indiarubber stopper of basin W, and firmly clamped down. Then +the taps A and C are opened, and B closed. When the burette is filled with +soda solution half-way up the funnel Y, A and C are closed, and B opened. +The arrows show the inlet and outlet for the cooling water that is kept +running through the water jacket round the nitrometer tube. To collect the +gas, raise the nitrometer off the rubber stopper, and place the gas tube +from the decomposition apparatus in the glass dish W and under the opening +of the nitrometer. + +[Illustration: Fig. 44. SCHULTZE-TIEMAN APPARATUS.] + +For the estimation of nitrogen in nitro-cellulose take .5 to .65 grm., and +place in the decomposition flask _f_ (Fig. 45), washing in with about 25 +c.c. of water by alternately opening clips D and E. The air in the flask +is driven out by boiling, whilst the air is shut off by the tube _i_ +dipping into the basin W, which is filled with the soda lye, and tube K is +placed in the test tube R, which contains a few c.c. of water. As soon as +all the air is completely driven out, clips D and E are closed, and the +gas jet is taken away. (This flask must be a strong one, or it will +burst.) Into test tube R, 25 c.c. of concentrated solution of +protochloride of iron and 10 to 15 c.c. concentrated hydrochloric acid are +poured, which are sucked up into the developing flask _f_ by opening clip +E, air being carefully kept from entering. The clip E is now closed, and +tube _i_ is put underneath the burette, and the development of NO gas is +commenced by heating the contents of the flask _f_. When the pressure of +the gas in the flask has become greater than the pressure of the +atmosphere, the connecting tube begins to swell at _i_, whereupon clip D +is opened, and the boiling continued with frequent shaking of the bulb, +until no more nitrous gas bubbles rise up into the soda lye, the +distilling over of the HCl causes a crackling noise, the clip D is closed, +and E opened. The burette is again put hermetically on the indiarubber +stopper in basin W, and the apparatus is left to cool until the water +discharged through P shows the same temperature as the water flowing +through (into the cooling jacket) Z. If the level of the soda solution in +the tube X is now put on exactly the same level as that in the burette by +lowering or elevating the tube X as required, the volume of NO obtained in +c.c. can be read off within 1/10 c.c., and the percentage of nitrogen +calculated by the usual formula. + +[Illustration: FIG. 45.--Decomposition Flask for Schultze-Tieman Method.] + +The solution of protochloride of iron is obtained by dissolving iron +nails, &c., in concentrated HCl, the iron being in excess. When the +development of hydrogen ceases, it is necessary to filter warm through a +paper filter, and acidify filtrate with a few drops of HCl. The soda +solution used has a sp. gr. of 1.210 to 1.260; equals 25° to 30° B. The +nitro-cellulose is dried in quantities of 2 grms. at 70° C. during eight +to ten hours, and then three hours in an exiccator over H_{2}SO_{4}. The +results obtained with this apparatus are very accurate. The reaction is +founded upon that of MM. Champion and Pellet's method. + +~The Kjeldahl Method of Determining Nitrogen.~--This method, which has +been so largely used by analysts for the determination of nitrogen in +organic bodies, more especially perhaps in manures, was proposed by J. +Kjeldahl,[A] of the Carlsberg Laboratory of Copenhagen. It was afterwards +modified by Jodlbauer, of Munich,[B] and applied to the analysis of nitro- +explosives by M. Chenel, of the Laboratoire Centrale des Poudres, whose +method of procedure is as follows:--0.5 grm. of the finely powdered +substance is digested in the cold with a solution of 1.2 grm. of phenol +and 0.4 grm. phosphoric anhydride in 30 c.c. of sulphuric acid. The +mixture is kept well shaken until the solution is complete. From 3 to 4 +grms. of zinc-dust is then cautiously and gradually added, the temperature +of the mass being kept down until complete reduction has been effected. +Finally, 0.7 grm. of mercury is added, and the process continued in the +usual way, according to Kjeldahl; that is, the liquid is distilled until +all the ammonia has passed over, and is absorbed in the standard acid. The +distillate is then titrated with standard ammonia. + +[Footnote A: J. Kjeldahl, _Zeitschrift Anal. Chem._, 1883, xxii., p. 366.] + +[Footnote B: Jodlbauer, _Chemisches Centralblatt_, 1886, pp. 434-484. See +also _Arms and Explosives_, 1893, p. 87.] + +The NO_{2} group is at the moment of solution fixed upon the phenol with +the production of mono-nitro-phenol, which is afterwards reduced by the +action of the zinc-dust into the amido derivative. During the subsequent +combustion, the nitrogen of the amido-phenol becomes fixed in the state of +ammonia. M. Chenel is perfectly satisfied with the results obtained, but +he points out that the success of the operation depends upon the complete +conversion of the phenol into the mono-nitro derivatives. This takes place +whenever the organic compound forms a _clear solution_ in the cold +sulphuric acid mixture. Substances like collodion or gun-cotton must be +very finely divided for successful treatment. The following table shows +some of the results obtained by M. Chenel:-- + + ______________________________________________ +| | | +| | Total Nitrogen. | +| Substances Analysed. |______________________| +| | | | +| | Calculated. | Found. | +| |_____________|________| +| | | | +| Saltpetre (KNO_{3}) | 13.86 | 13.91 | +| | | 13.82 | +| | | 13.73 | +| | | 13.96 | +| Ammonium nitrate | 35.00 | 35.31 | +| | | 34.90 | +| | | 34.96 | +| Barium nitrate | 10.72 | 10.67 | +| | | 10.62 | +| Nitro-glycerol | 18.50 | 18.45 | +| Di-nitro-benzol[A] | 16.67 | 16.78 | +| | | 16.57 | +| Para-nitro-phenol | 10.07 | 10.03 | +| Picric acid[A] | 18.34 | 18.42 | +| | | 18.43 | +| Ammonium picrate | 22.76 | 22.63 | +| | | 22.67 | +| Di-nitro-ortho-cresol | 14.14 | 14.10 | +| | | 13.98 | +| Tri-nitro-meta-cresol | 17.28 | 17.57 | +| | | 17.27 | +|_______________________|_____________|________| + +[Footnote A: Dr. Bernard Dyer obtained 18.39 per cent. for picric acid and +16.54 per cent. for di-nitro-benzol.--_Jour. Chem. Soc._, Aug. 1895.] + +When Chenel endeavoured to apply Jodlbauer's modification of Kjeldahl's +process to the examination of the tri- and tetra-nitrated naphthalenes, he +found that good results were not obtainable, because these compounds do +not dissolve completely in the cold sulphuric acid. It may, however, be +used if they are previously converted into the naphthylamines, according +to the plan proposed by D'Aguiar and Lautemann (_Bull. Soc. Chim._, vol. +iii., new series, p. 256). This is rapidly effected as follows:--Twelve +grms. of iodine are gradually added to a solution of 2 grms. of phosphorus +in about 15 or 20 c.c. of bisulphide of carbon, this solution being +contained in a flask of 250 c.c. capacity. The flask and its contents are +heated on the water bath at 100° C. with constant attention, until the +last traces of the carbon bisulphide have distilled away. It is then +cooled, and the iodide of phosphorus is detached from the sides of the +flask by shaking, but not expelled. The next step is to add about 0.5 to +0.6 grm. of the substance that is to be analysed, after which 8 grms. of +water are introduced, and the flask is agitated gently two or three times. +As soon as the reaction becomes lively, the contents of the flask are well +shaken. It is usually finished about one minute after the addition of the +water. The flask is now cooled, and 25 c.c. of sulphuric acid, together +with 0.7 grm. of mercury, are gradually added; hydriodic acid (HI) forms, +and the temperature of the flask must be raised sufficiently to expel it. +The remaining part of the operation is as in the ordinary Kjeldahl +process. + +M. Chenel has found this process the best for the analysis of the nitro- +naphthalenes, and for impervious substances like collodion or gun-cotton. +Personally, I have never been able to obtain satisfactory results with +this process in the analysis of nitro-cellulose, and I am of opinion that +the process does not possess any advantage over the nitrometer method, at +any rate for the analysis of gun-cotton. + +Table giving the Percentages of Nitrogen and Oxide of Nitrogen in Various +Substances used in or as Explosives: + + Name FORMULÆ NITROGEN NO_{2} + per cent. per cent. + +Nitroglycerine C_{3}H_{5}(ONO_{2})_{3} 18.50 = 60.70 +Hexa-nitro-cellulose C_{12}H_{14}O_{4}(ONO_{2})_{6} 14.14 = 46.42 +Penta-nitro-cellulose C_{6}H_{8}O_{5}(ONO_{2})_{5} 11.11 = 36.50 +Nitro-benzene C_{6}H_{5}NO_{2} 11.38 = 37.39 +Di-nitro-benzene C_{6}H_{4}(NO_{2})_{2} 16.67 = 54.77 +Tri-nitro-benzene C_{6}H_{3}(NO_{2})_{3} 19.24 = 63.22 +Nitro-toluene C_{7}H_{7}NO_{2} 10.21 = 33.49 +Nitro-naphthalene C_{10}H_{7}NO_{2} 8.09 = 26.53 +Di-nitro-naphthalene C_{10}H_{6}(NO_{2})_{2} 12.84 = 42.12 +Nitro-mannite C_{6}H_{7}(NO_{3})_{6} 23.59 = 77.37 +Nitro-starch C_{6}H_{8}O_{4}(HNO_{3}) 6.76 = 22.18 +Picric acid + (Tri-nitro-phenol) C_{6}H_{2}OH(NO_{2})_{3} 18.34 = 60.15 +Chloro-nitro-benzene C_{6}H_{3}Cl(NO_{2})_{2} 13.82 = 45.43 +Ammonium nitrate NH_{4}NO_{3} 35.00 = +Sodium nitrate NaNO_{3} 16.47 = +Potassium nitrate KNO_{3} 13.86 = +Nitric acid HNO_{3} 22.22 = +Barium nitrate Ba(NO_{3})_{2} 10.72 = + +~Analysis of Celluloid.~--The finely divided celluloid is well stirred, by +means of a platinum wire, with concentrated sulphuric acid in the cup of a +Lungé nitrometer, and when dissolved the nitrogen determined in the +solution in the usual way. To prevent interference from camphor, the +following treatment is suggested by H. Zaunschirm (_Chem. Zeit._, xiv., +905). Dissolve a weighed quantity of the celluloid in a mixture of ether- +alcohol, mixed with a weighed quantity of washed and ignited asbestos, or +pumice-stone, dry, and disintegrate the mass, and afterwards extract the +camphor with chloroform, dry, and weigh: then extract with absolute +methyl-alcohol, evaporate, weigh, and examine the nitro-cellulose in the +nitrometer. + +~Picric Acid and Picrates.~--Picric acid is soluble in hot water, and to +the extent of 1 part in 100 in cold water, also in ether, chloroform, +glycerine, 10 per cent. soda solution, alcohol, amylic alcohol, carbon +bisulphide, benzene, and petroleum. If a solution of picric acid be boiled +with a strong solution of potassium cyanide, a deep red liquid is +produced, owing to the formation of potassium iso-purpurate, which +crystallises in small reddish-brown plates with a beetle-green lustre. +This, by reaction with ammonium chloride, gives ammonium iso-purpurate +(NH_{4}C_{8}H_{4}N_{5}O_{6}), or artificial murexide, which dies silk and +wool a beautiful red colour. On adding barium chloride to either of the +above salts, a vermilion-red precipitate was formed, consisting of barium +iso-purpurate. With ammonio-sulphate of copper, solutions of picric acid +give a bright green precipitate. Mr A.H. Allen gives the following methods +for the assay of commercial picric acid, in his "Commercial Organic +Analysis":-- + +~Resinous and Tarry matters~ are not unfrequently present. They are left +insoluble on dissolving the sample in boiling water. The separation is +more perfect if the hot solution be exactly neutralised by caustic soda. + +~Sulphuric Acid, Hydrochloric Acid, and Oxalic Acid~, and their salts are +detected by adding to the filtered aqueous solution of the sample +solutions of the picrates of barium, silver, and calcium. These salts are +readily made by boiling picric acid with the carbonates of the respective +metals and filtering: other soluble salts of these methods may be +substituted for the picrates, but they are less satisfactory. + +~Nitric Acid~ may be detected by the red fumes evolved on warming the +sample with copper turnings. + +~Inorganic Impurities and Picrates of Potash and Sodium~, &c., leave +residues on cautious ignition. + +~General Impurities and Adulterations~ may be detected and determined by +shaking 1 grm. of the sample of acid in a graduated tube with 25 c.c. of +ether, the pure acid dissolves, while any oxalic acid, nitrates, picrates, +boric acid, alum, sugar, &c., will be left insoluble, and after removal of +the ethereal liquid, may be readily identified and determined. For the +detection and determination of water and of oxalic acid, 50 c.c. of warm +benzene may be advantageously substituted for ether. Sugar may be +separated from the other impurities by treating the residue insoluble in +ether or benzene with rectified spirit, in which sugar and boric acid +alone will dissolve. If boric acid be present, the alcoholic solution will +burn with a green flame. Mono- and di-nitrophenic acids lower the melting +point (122° C). Their calcium salts are less soluble than the picrate, and +may be approximately separated from it by fractional crystallisation, or +by precipitating the hot saturated solution of the sample with excess of +lime water. Picric acid may be determined by extracting the acidulated +aqueous solution by agitation with ether or benzene, and subsequently +removing and evaporating off the solvent. It may also be precipitated as +the potassium salt. + +~Potassium Picrate~ [KC_{6}H_{2}(NO_{2})_{3}O]. When a strong solution of +picric acid is neutralised by carbonate of potash, this salt is thrown +down in yellow crystalline needles, which require 260 parts of cold or 14 +parts of hot water for their solution. In alcohol it is much less soluble. + +~Ammonium Picrate~ is more soluble in water than the above, and sodium +picrate is readily soluble in water, but nearly insoluble in solution of +sodium carbonate. + +~Picrates of the Alkaloids.~--Picric acid forms insoluble salts with many +of the alkaloids, and picric acid may be determined in the following +manner:--To the solution of picric acid, or a picrate, add a solution of +sulphate of cinchonine acidulated with H_{2}SO_{4}. The precipitated +picrate of cinchonine [C_{20}H_{24}N_{2}O(C_{6}H_{2}N_{3}O_{7})_{2}] is +washed with cold water, rinsed off the filter into a porcelain crucible or +dish, the water evaporated on the water bath, and the residual salt +weighed. Its weight, multiplied by .6123, gives the quantity of picric +acid in the sample taken. + +~Analysis of Glycerine.~[A] Glycerine that is to be used for the +manufacture of nitro-glycerine should have a minimum specific gravity of +1.261 at 15° C. This can be determined, either by the aid of a Sartorius +specific gravity balance, or by using an ordinary specific gravity bottle. +One of 10 or 25 c.c. capacity is very convenient. + +[Footnote A: See also Sulman and Berry, _Analyst_, xi., 12-34, and Allen's +"Commercial Organic Analysis," vol. ii., part i.] + +~Residue~[A] left upon evaporation should not be more than 0.25 per cent. +To determine this, take 25 grms. of the glycerine, and evaporate it at a +temperature of about 160° C. in a platinum basin, and finish in an air +bath. Weigh until constant weight is obtained. Afterwards incinerate over +a bunsen burner, and weigh the ash. + +[Footnote A: Organic matter up to .6 per cent. is not always prejudicial +to the nitrating quantities of a glycerine.] + +~Silver Test.~ A portion of the sample of glycerine to be tested should be +put in a small weighing bottle, and a quarter of its bulk of N/10 silver +nitrate solution added to it, then shake it, and place in a dark cupboard +for fifteen minutes. It must be pronounced bad if it becomes black or dark +brown within that time (acrolein, formic, and butyric acids). + +The German official test for glycerine for pharmaceutical purposes is much +more stringent, 1 c.c. of glycerine heated to boiling with 1 c.c. of +ammonia solution and three drops of silver nitrate solution must give +neither colour or precipitate within five minutes. + +~Nitration.~ Fifty grms. of the glycerine are poured from a beaker into a +mixture of concentrated nitric acid (specific gravity 1.53) and sulphuric +acid (1.84), mixed in the proportions of 3 HNO_{3} to 5 H_{2}SO_{4} (about +400 c.c. of mixed acids). The mixed acids should be put into a rather +large beaker, and held in the right hand in a basin of water, and the +glycerine slowly poured into them from a smaller one held in the left. A +constant rotatory motion should be given to the beaker in which the +nitration is performed. When all the glycerine has been added, and the +mixture has been shaken for a few minutes longer, it is poured into a +separator, and allowed to stand for some time. It should, if the glycerine +is a good one, have separated from the mixed acids in ten minutes, and the +line of demarcation between the nitro-glycerine and the acid should be +clear and sharp, neither should there be any white flocculent matter +suspended in the liquid. The excess of acids is now drawn off, and the +nitro-glycerine shaken once or twice with a warm solution of carbonate of +soda, and afterwards with water alone. The nitro-glycerine is then drawn +off into a weighed beaker, the surface dried with a piece of filter paper, +and weighed; 100 parts of a good glycerine should yield about 230 of +nitro-glycerine. A quicker method is to take only 10 c.c. of the +glycerine, of which the specific gravity is already known, nitrate as +before, and pour into a burette, read off the volume of nitro-glycerine in +c.c. and multiply them by 1.6 (the specific gravity of nitro-glycerine), +thus: 10 grms. gave 14.5 c.c. nitro-glycerine, and 14.5 x 1.6 = 23.2 +grms., therefore 100 would give 232 grms. nitro-glycerine. The points to +be noted in the nitration of a sample of glycerine are: the separation +should be sharp, and within half an hour or less, and there should be no +white flocculent matter formed, especially when the carbonate of soda +solution is added. + +~Total Acid Equivalent.~ Mr G.E. Barton (_Jour. Amer. Chem. Soc._, 1895) +proposes to determine thus: 100 c.c. of glycerine are diluted to 300 c.c. +in a beaker, a few drops of a 1 per cent. solution of phenolphthalein and +10 c.c. of normal caustic soda solution are added; after boiling, the +liquid is titrated with normal hydrochloric acid (fatty acids are thus +indicated and roughly determined). + +~Neutrality.~ The same chemist determines the neutrality of glycerine +thus: 50 c.c. of glycerine mixed with 100 c.c. of water and a few drops of +alcoholic phenolphthalein[A] are titrated with hydrochloric acid or sodium +hydroxide; not more than 0.3 c.c. normal hydrochloric acid or normal soda +solution should be required to render the sample neutral; raw glycerines +contain from .5 to 1.0 per cent. of sodium carbonate. + +[Footnote A: Sulman and Berry prefer litmus as indicator.] + +~Determination of Free Fatty Acids.~ A weighed quantity of the glycerine +is shaken up with some neutral ether in a separating funnel, the glycerine +allowed to settle, drawn off, and the ether washed with three separate +lots of water. The water must have been recently boiled, and be quite free +from CO_{2}. All the free fatty acid is now in the ether, and no other +soluble acid. A drop of phenolphthalein is now added, a little water, and +the acidity determined by titration with deci-normal baryta solution, and +the baryta solution taken calculated as oleic acid. + +~Combined Fatty Acid.~ About 30 grms. of the glycerine are placed in a +flask, and to it is added about half a grm. of caustic soda in solution. +The mixture is heated for ten minutes at 150° C. After cooling some pure +ether is added to it, and enough dilute H_{2}SO_{4} to render it +distinctly acid. It is well shaken. All the fatty acids go into the ether. +The aqueous solution is then removed, and the ether well washed to remove +all H_{2}SO_{4}. After the addition of phenolphthalein the acid is +titrated, and the amount used calculated into oleic acid. From this total +amount of fatty acids the free fatty acid is deducted, and the quantity of +combined fatty acids thus obtained. + +~Impurities.~ The following impurities may be found in bad samples of +glycerine:--Lead, arsenic, lime, chlorine, sulphuric acid, thio-sulphates, +sulphides, cyanogen compounds, organic acids (especially oleic acid and +fatty acids[A]), rosin products, and other organic bodies. It is also said +to be adulterated with sugar and glucose dextrine. Traces of sulphuric +acid and arsenic may be allowed, also very small traces indeed of lime and +chlorine. + +[Footnote A: These substances often cause trouble in nitrating, white +flocculent matter being formed during the process of washing.] + +The organic acids, formic and butyric acids may be detected by heating a +sample of the glycerine in a test tube with alcohol and sulphuric acid, +when, if present, compound ethers, such as ethylic formate and butyrate, +the former smelling like peaches and the latter of pine-apple, will be +formed. + +~Oleic Acid~, if present in large quantity, will come down upon diluting +the sample with water, but smaller quantities may be detected by passing a +current of nitrogen peroxide, N_{2}O_{4} (obtained by heating lead +nitrate), through the diluted sample, when a white flocculent precipitate +of elaidic acid, which is less soluble than oleic acid, will be thrown +down. By agitating glycerol with chloroform, fatty acids, rosin oil, and +some other impurities are dissolved, while certain others form a turbid +layer between the chloroform and the supernatant liquid. On separating the +chloroform and evaporating it to dryness, a residue is obtained which may +be further examined. + +~Sodium Chloride~ can be determined in 100 c.c. of the glycerine by adding +a little water, neutralised with sodium carbonate, and then titrated with +a deci-normal solution of silver nitrate, using potassium chromate as +indicator. + +~Organic Impurities~ of various kinds occur in crude glycerine, and are +mostly objectionable. Their sum may be determined with fair accuracy by +Sulman and Berry's method: 50 grms. of the sample are diluted with twice +its measure of water, carefully neutralised with acetic acid, and warmed +to expel carbonic acid; when cold, a solution of basic lead acetate is +added in slight but distinct excess, and the mixture well agitated. The +formation of an abundant precipitate, which rapidly subsides, is an +indication of considerable impurity in the sample. To ascertain its +amount, the precipitate is first washed by decantation, and then collected +on a tared, or preferably a double counter-poised filter, where it is +further washed, dried at 100° to 105° C., and weighed. The precipitate and +filter paper are then ignited separately in porcelain, at a low red heat, +the residues moistened with a few drops of nitric acid and reignited; the +weight of the lead oxide deducted from that of the original precipitate +gives the weight of the organic matter precipitated by the lead. Raw +glycerines contain from 0.5 to 1.0 per cent. + +~Albuminous Matters.~ An approximate determination of the albuminous +matters may be made by precipitating with basic lead acetate as already +described, and determining the nitrogen by the Kjeldahl method; the +nitrogen multiplied by 6.25 gives the amount of albuminous matter in the +precipitate. + +~The Determination of Glycerine.~ The acetin method of Benedikt and Canton +depends upon the conversion of glycerine into triacetin, and the +saponification of the latter, and reduces the estimation of glycerine to +an acidmetric method. About 1.5 grm. of crude glycerine is heated to +boiling with 7 grms. of acetic anhydride, and 3 to 4 grms. of anhydrous +sodium acetate, under an upright condenser for one and a half hours. After +cooling, 50 c.c. of water are added, and the mixture heated until all the +triacetin has dissolved. The liquid is then filtered into a large flask, +the residue on the filter is well washed with water, the filtrate quite +cooled, phenolphthalein is added and the fluid exactly neutralised with a +dilute (2 to 3 per cent.) solution of alkali. Twenty-five c.c. of a 10 per +cent. caustic soda solution, which must be accurately standardised upon +normal acid, are then pipetted into the liquid, which is heated to boiling +for ten minutes to saponify the triacetin, and the excess of alkali is +then titrated back with normal acid. One c.c. of normal acid corresponds +to .03067 grm. of glycerine. + +~Precautions.~--The heating must be done with a reflux condenser, the +triacetin being somewhat volatile. The sodium acetate used must be quite +anhydrous, or the conversion of the glycerine to triacetyl is imperfect. +Triacetin in contact with water gradually decomposes. After acetylation is +complete, therefore, the operations must be conducted as rapidly as +possible. It is necessary to neutralise the free acetic acid very +cautiously, and with rapid agitation, so that the alkali may not be +locally in excess. + +~The Lead Oxide Method.~--Two grms. of sample are mixed with about 40 +grms. of pure litharge, and heated in an air bath to 130° C. until the +weight becomes constant, care being taken that the litharge is free from +such lead compounds and other substances as might injuriously affect the +results, and that the heating of the mixture takes place in an air bath +free from carbonic acid. The increase in weight in the litharge, minus the +weight of substance not volatilisable from 2 grms. of glycerine at 160° +C., multiplied by the factor 1.243, is taken as the weight of glycerine in +the 2 grms. of sample. The glycerine must be fairly pure, and free from +resinous substances and SO_{3}, to give good results by this process. + +~Analysis of the "Waste Acids" from the Manufacture of Nitro-Glycerine or +Gun-Cotton.~ Determine the specific gravity by the specific gravity bottle +or hydrometer, and the oxides of nitrogen by the permanganate method +described under nitro-glycerine. Now determine the total acidity of the +mixture by means of a tenth normal solution of sodium hydrate, and +calculate it as nitric acid (HNO_{3}), then determine the nitric acid by +means of Lungé nitrometer, and subtract percentage found from total +acidity, and calculate the difference into sulphuric acid, thus:-- + +Total acidity equals 97.46 per cent.--11.07 per cent. HNO_{3} = 86.39 per +cent., then (86.39 x 49)/63 = 67.20 per cent. H_{2}SO_{4}. + +Then analysis of sample will be:-- + + _ +Sulphuric acid = 67.20 per cent. | +Nitric acid = 11.07 " |- Specific gravity = 1.7075. +Water = 12.73 " _| + +This method is accurate enough for general use in the nitric acid factory. +The acid mixture may be taken by volume for determining nitric oxide in +nitrometer. Two c.c. is a convenient quantity in the above case, then 2 x +1.7075 (specific gravity) = 3.414 grms. taken, gave 145 c.c. NO (barometer += 748 mm, and temperature = 15°C.) equals 134.9 c.c. (corr.) and as 1 c.c. +NO = .0282 grm. HNO_{3} 135 x .0282 = .378 grm. = 11.07 per cent. nitric +acid. + +~Sodium Nitrate.~ Determine moisture and chlorine by the usual methods, +and the total, NaNO_{3}, by means of nitrometer--0.45 grm. is a very +convenient quantity to work on (gives about 123 c.c. gas); grind very +fine, and dissolve in a very little hot water in the cup of the +nitrometer; use about 15 c.c. concentrated H_{2}SO_{4}. One cubic cent. of +NO equals .003805 grm. of NaNO_{3}. The insoluble matter, both organic and +inorganic, should also be determined, also sulphate of soda and lime +tested for. + +~Analysis of Mercury Fulminate (Divers and Kawakita's Method).~--A weighed +quantity of mercury fulminate is added to excess, but measured quantity of +fuming hydrochloric acid contained in a retort connected with a receiver +holding water. After heating for some time, the contents of the retort and +receiver are mixed and diluted, and the mercury is precipitated by +hydrogen sulphide. By warming and exposure to the air in open vessels the +hydrogen sulphide is for the most part dissipated. The solution is then +titrated with potassium hydroxide (KOH), as well as another quantity of +hydrochloric acid, equal to that used with the fulminate. As the mercury +chloride is reconverted into hydrochloric acid by the hydrogen sulphide, +and as the hydroxylamine does not neutralise to litmus the hydrochloric +acid combined with it, there is an equal amount of hydrochloric acid free +or available in the two solutions. Any excess of acid in the one which has +received the fulminate will therefore be due to the formic acid generated +from the fulminate. Dr. Divers and M. Kawakita, working by this method, +have obtained 31.31 per cent. formic acid, instead of 32.40 required by +theory. (_Jour. Chem. Soc._, p. 17, 1884.) + +Divers and Kawakita proceed thus: 2.351 grms. dissolved, as already +described, in HCl, and afterwards diluted, gave mercury sulphide equal to +70.40 per cent. mercury. The same solution, after removal of mercury, +titrated by iodine for hydroxylamine, gave nitrogen equal to 9.85 per +cent., and when evaporated with hydroxyl ammonium chloride equal to 9.55 +per cent. A solution of 2.6665 grms. fulminate in HCl of known amount, +after removal of mercury by hydrogen sulphide, gave by titration with +potassium hydrate, formic acid equal to 8.17 per cent. of carbon. +Collecting and comparing with calculation from formula we get-- + + Calc. I. II. III. + +Mercury 70.42 70.40 ... ... +Nitrogen 9.86 9.85 9.55 ... +Carbon 8.45 ... ... 8.17 +Oxygen 11.27 ... ... ... + _______ + + 100.00 + +~The Analysis of Cap Composition.~--Messrs F.W. Jones and F.A. Willcox +(_Chem. News_, Dec. 11, 1896) have proposed the following process for the +analysis of this substance:--Cap composition usually consists of the +ingredients--potassium chlorate, antimony sulphide, and mercury fulminate, +and to estimate these substances in the presence of each other by ordinary +analytical methods is a difficult process. Since the separation of +antimony sulphide and mercury fulminate in the presence of potassium +chlorate necessitates the treatment of the mixture with hydrochloric acid, +and this produces an evolution of hydrogen sulphide from the sulphide, and +a consequent precipitation of sulphur; and potassium chlorate cannot be +separated from the other ingredients by treatment with water, owing to the +appreciable solubility of mercury fulminate in cold water. + +In the course of some experiments on the solubility of mercury fulminate +Messrs Jones and Willcox observed that this body was readily soluble in +acetone and other ethereal solvents when they were saturated with ammonia +gas, and that chlorate of potash and sulphide of antimony were insoluble +in pure acetone saturated with ammonia; these observations at once +afforded a simple method of separating the three ingredients of cap +composition. By employing this solution of acetone and ammonia an analysis +can be made in a comparatively short time, and yields results of +sufficient accuracy for all technical purposes. The following are the +details of the process:-- + +A tared filter paper is placed in a funnel to the neck of which has been +fitted a piece of rubber tubing provided with a clip. The paper is +moistened with a solution of acetone and ammonia, the cap composition is +weighed off directly on to the filter paper and is then covered with the +solution of acetone and ammonia and allowed to stand thirty-four hours. It +is then washed repeatedly with the same solution until the washings give +no coloration with ammonium sulphide, and afterwards washed with acetone +until washings give no residue on evaporation dried and weighed. The paper +is again put in the funnel and washed with water until free from potassium +chlorate, dried and weighed. + +If _c_ = weight of composition taken, + _d_ = " " filter paper, + _a_ = " after first extraction, + _b_ = " " second extraction, + then _c+d-a_ = weight of fulminate, + _c+d-a-b_ = " " KClO_{3}, + _b-d_ = " " sulphide of antimony. + +The composition should be finely ground in an agate mortar. + +The results of the analysis by this method of two mixtures of known +composition are given below-- + + ________________________________________________________________________ +| | | | +| | A | B | +| | | | +| | Percentage | Percentage | Percentage | Percentage | +| | Taken. | Found. | Taken. | Found. | +|____________________|____________|____________|____________|____________| +| | | | | | +| Antimony Sulphide | 36.47 | 36.25 | 37.34 | 37.22 | +| Potassium Chlorate | 33.25 | 33.71 | 46.03 | 46.43 | +| Mercury Fulminate | 30.27 | 30.02 | 16.61 | 16.34 | +|____________________|____________|____________|____________|____________| + +Dr. H.W. Brownsdon's (_Jour. Soc. Chem. Ind._, xxiv., April 1905) process +is as follows:--The cap composition is removed by squeezing the cap with +pliers, while held over a porcelain basin of about 200 c.c. capacity, and +removing the loosened foil and broken composition by means of a pointed +wooden chip. Composition adhering to the shell or foil is loosened by +alcohol, and washed into the dish by means of alcohol in a small wash +bottle. The shell and foil are put to one side and subsequently weighed +when dry. The composition in the dish is broken down quite fine with a +flat-headed glass rod, and the alcohol evaporated on the water bath till +the residue is moist, but not quite dry, 25 c.c. of water are then added, +and the composition well stirred from the bottom. After the addition of +0.5 grm. of pure sodium, thiosulphate, the contents of the dish, is well +stirred for two and a half minutes. One drop of methyl orange is then +added, and the solution titrated with N/20 sulphuric acid, which has been +standardised against weighings of 0.05-0.1 grm. fulminate to which 25 c.c. +of water is added in a porcelain dish, then 0.5 grm. of thiosulphate, and +after stirring for two and a half minutes, titrated with N/20 sulphuric +acid. The small amount of antimony sulphide present does not interfere +with the recognition of the end point. After titration, the solution is +filtered through a small 5-1/2 cm. filter paper, which retains the +antimony sulphide. The filter paper containing the Sb_{2}S_{3} is well +washed and then transferred to a large 6 by 1 test tube. Five c.c. of +strong hydrochloric acid are added, and the contents of the tube boiled +gently for a few seconds until the sulphide is dissolved and all the +H_{2}S driven off or decomposed: 2-3 c.c. of a saturated solution of +tartaric acid are added, and the contents of the tube washed into a 250 +c.c. Erlenmeyer flask. The solution is then nearly neutralised with sodium +carbonate, excess of bi-carbonate added, and after the addition of some +starch solution titrated with N/20 iodine solution. This method for small +quantities of stibnite is both quick and accurate, the error being about +±0.0003 grm. Sb_{2}S_{3} at the outside. + +The tendency of this method is to give slightly low figures for the +fulminate, but since these are uniform within a negligible error, it does +not affect the value of the results as a criterion of uniformity. The +following test results were obtained by Dr Brownsdon:-- + + ____________________________________________________________ +| | | | +| Fulminate Taken. | Fulminate Found. | Error. | +| Grm. | Grm. | Grm. | +| | | | +| 0.0086 | 0.0083 | -0.0003 | +| 0.0082 | 0.0081 | -0.0001 | +| 0.0074 | 0.0071 | -0.0003 | +| 0.0068 | 0.0066 | -0.0002 | +|____________________|___________________|___________________| +| | | | +| Stibnite Taken. |Sb_{2}S_{3}, Found.| Error. | +| Grm. | Grm. | Grm. | +| | | | +| 0.0085 | 0.0084 | -0.0001 | +| 0.0098 | 0.0099 | +0.0001 | +| 0.0160 | 0.0157 | -0.0003 | +| 0.0099 | 0.0100 | +0.0001 | +|____________________|___________________|___________________| + +TABLE FOR CORRECTION OF VOLUMES OF GASES FOR TEMPERATURE, GIVING THE +DIVISOR FOR THE FORMULA. + +V_{1} = V x B/(760 x (1 + dt)) (d = 0.003665) 1 + dt from 0° to 30° C. + +___________________________________________________________ + | | | | | + t. | 760x(1+dt). | t. | 760x(1+dt). | t. | 760x(1+dt). +_____|_____________|_____|_____________|_____|_____________ + | | | | | + °C. | | °C. | | °C. | + 0.0 | 750.000 | 1.7 | 764.7352 | 3.4 | 769.4704 + .1 | 760.2785 | .8 | 765.0137 | .5 | 769.7489 + .2 | 760.5571 | .9 | 765.2923 | .6 | 770.0274 + .3 | 760.8356 | 2.0 | 765.5708 | .7 | 770.3060 + .4 | 761.1142 | .1 | 765.8493 | .8 | 770.5845 + .5 | 761.3927 | .2 | 766.1279 | .9 | 770.8631 + .6 | 761.6712 | .3 | 766.4064 | 4.0 | 771.1416 + .7 | 761.9498 | .4 | 766.6850 | .1 | 771.4201 + .8 | 762.2283 | .5 | 766.9635 | .2 | 771.6987 + .9 | 762.5069 | .6 | 767.2420 | .3 | 771.9772 + 1.0 | 762.7854 | .7 | 767.5206 | .4 | 772.2558 + .1 | 763.0639 | .8 | 767.7991 | .5 | 772.5343 + .2 | 763.3425 | .9 | 768.0777 | .6 | 772.8128 + .3 | 763.6210 | 3.0 | 768.3562 | .7 | 773.0914 + .4 | 763.8996 | .1 | 768.6347 | .8 | 773.3699 + .5 | 764.1781 | .2 | 768.9133 | .9 | 773.6485 + .6 | 764.4566 | .3 | 769.1918 | 5.0 | 773.9270 +_____|_____________|_____|_____________|_____|_____________ +___________________________________________________________ + | | | | | + t. | 760x(1+dt). | t. | 760x(1+dt). | t. | 760x(1+dt). +_____|_____________|_____|_____________|_____|_____________ + | | | | | + °C. | | °C. | | °C. | + 5.1 | 774.2055 | .9 | 787.5755 | .7 | 800.9454 + .2 | 774.4841 |10.0 | 787.8540 | .8 | 801.2239 + .3 | 774.7626 | .1 | 788.1325 | .9 | 801.5025 + .4 | 775.0412 | .2 | 788.4111 |15.0 | 801.7810 + .5 | 775.3197 | .3 | 788.6896 | .1 | 802.0595 + .6 | 775.5982 | .4 | 788.9682 | .2 | 802.3381 + .7 | 775.8768 | .5 | 789.2467 | .3 | 802.6166 + .8 | 776.1553 | .6 | 789.5252 | .4 | 802.8952 + .9 | 776.4339 | .7 | 789.8038 | .5 | 803.1737 + 6.0 | 776.7124 | .8 | 790.0823 | .6 | 803.4522 + .1 | 776.9909 | .9 | 790.3609 | .7 | 803.7308 + .2 | 777.2695 |11.0 | 790.6394 | .8 | 804.0093 + .3 | 777.5480 | .1 | 790.9179 | .9 | 804.2879 + .4 | 777.8266 | .2 | 791.1965 |16.0 | 804.5664 + .5 | 778.1051 | .3 | 791.4750 | .1 | 804.8449 + .6 | 778.3836 | .4 | 791.7536 | .2 | 805.1235 + .7 | 778.6622 | .5 | 792.0321 | .3 | 805.4020 + .8 | 778.9407 | .6 | 792.3106 | .4 | 805.6806 + .9 | 779.2193 | .7 | 792.5892 | .5 | 805.9591 + 7.0 | 779.4978 | .8 | 792.8677 | .6 | 806.2376 + .1 | 779.7763 | .9 | 793.1463 | .7 | 806.5162 + .2 | 780.0549 |12.0 | 793.4248 | .8 | 806.7947 + .3 | 780.3334 | .1 | 793.7033 | .9 | 807.0733 + .4 | 780.6120 | .2 | 793.9819 |17.0 | 807.3518 + .5 | 780.8905 | .3 | 794.2604 | .1 | 807.6303 + .6 | 781.1690 | .4 | 794.5390 | .2 | 807.9089 + .7 | 781.4476 | .5 | 794.8175 | .3 | 808.1874 + .8 | 781.7261 | .6 | 795.0960 | .4 | 808.4660 + .9 | 782.0047 | .7 | 795.3746 | .5 | 808.7445 + 8.0 | 782.2832 | .8 | 795.6531 | .6 | 809.0230 + .1 | 782.5617 | .9 | 795.9317 | .7 | 809.3016 + .2 | 782.8403 |13.0 | 796.2102 | .8 | 809.5801 + .3 | 783.1188 | .1 | 796.4887 | .9 | 809.8587 + .4 | 783.3974 | .2 | 796.7673 |18.0 | 810.1372 + .5 | 783.6959 | .3 | 797.0458 | .1 | 810.4175 + .6 | 783.9544 | .4 | 797.3244 | .2 | 810.6943 + .7 | 784.2330 | .5 | 797.6029 | .3 | 810.9728 + .8 | 784.5115 | .6 | 797.8814 | .4 | 811.2514 + .9 | 784.7901 | .7 | 798.1600 | .5 | 811.5299 + 9.0 | 785.0686 | .8 | 798.4385 | .6 | 811.8084 + .1 | 785.3471 | .9 | 798.7171 | .7 | 812.0870 + .2 | 785.6257 |14.0 | 798.9956 | .8 | 812.3655 + .3 | 785.9042 | .1 | 799.2741 | .9 | 812.6441 + .4 | 786.1828 | .2 | 799.5527 |19.0 | 812.9226 + .5 | 786.4613 | .3 | 799.8312 | .1 | 813.2011 + .6 | 786.7398 | .4 | 800.1098 | .2 | 813.4797 + .7 | 787.0184 | .5 | 800.3883 | .3 | 813.7582 + .8 | 787.2969 | .6 | 800.6668 | .4 | 814.0368 +_____|_____________|_____|_____________|_____|_____________ +___________________________________________________________ + | | | | | + t. | 760x(1+dt). | t. | 760x(1+dt). | t. | 760x(1+dt). +_____|_____________|_____|_____________|_____|_____________ + | | | | | + °C. | | °C. | | °C. | +19.5 | 814.3153 |23.0 | 824.0642 | .5 | 833.8131 + .6 | 814.5938 | .1 | 824.3427 | .6 | 834.0916 + .7 | 814.8724 | .2 | 824.6213 | .7 | 834.3702 + .8 | 815.1500 | .3 | 824.8998 | .8 | 834.6487 + .9 | 815.4925 | .4 | 825.1784 | .9 | 834.9273 +20.0 | 815.7080 | .5 | 825.4569 |27.0 | 835.2058 + .1 | 815.9865 | .6 | 825.7354 | .1 | 835.4843 + .2 | 816.2651 | .7 | 826.0140 | .2 | 835.7629 + .3 | 816.5436 | .8 | 826.2925 | .3 | 836.0414 + .4 | 816.8222 | .9 | 826.5711 | .4 | 836.3200 + .5 | 817.1007 |24.0 | 826.8496 | .5 | 836.5985 + .6 | 817.3792 | .1 | 827.1281 | .6 | 836.8770 + .7 | 817.6578 | .2 | 827.4067 | .7 | 837.1556 + .8 | 817.9363 | .3 | 827.6852 | .8 | 837.4341 + .9 | 818.2149 | .4 | 827.9638 | .9 | 837.7127 +21.0 | 818.4934 | .5 | 828.2423 |28.0 | 837.9912 + .1 | 818.7719 | .6 | 828.5208 | .1 | 838.2697 + .2 | 819.0505 | .7 | 828.7994 | .2 | 838.5483 + .3 | 819.3290 | .8 | 829.0779 | .3 | 838.8268 + .4 | 819.6076 | .9 | 829.3565 | .4 | 839.1054 + .5 | 819.8861 |25.0 | 829.6350 | .5 | 839.3839 + .6 | 820.1646 | .1 | 829.9135 | .6 | 839.6624 + .7 | 820.4432 | .2 | 830.1921 | .7 | 839.9410 + .8 | 820.7217 | .3 | 830.4706 | .8 | 840.2195 + .9 | 821.0003 | .4 | 830.7492 | .9 | 840.4981 +22.0 | 821.2788 | .5 | 831.0277 |29.0 | 840.7766 + .1 | 821.5573 | .6 | 831.3062 | .1 | 841.0551 + .2 | 821.8859 | .7 | 831.5848 | .2 | 841.3337 + .3 | 822.1144 | .8 | 831.8633 | .3 | 841.6122 + .4 | 822.3930 | .9 | 832.1419 | .4 | 841.8908 + .5 | 822.6715 |26.0 | 832.4204 | .5 | 842.1693 + .6 | 822.9500 | .1 | 832.6989 | .6 | 842.4478 + .7 | 823.2286 | .2 | 832.9775 | .7 | 842.7264 + .8 | 823.5071 | .3 | 833.2560 | .8 | 843.0049 + .9 | 823.7857 | .4 | 833.5346 | .9 | 843.2835 + | | | |30.0 | 843.5620 +_____|_____________|_____|_____________|_____|_____________ + + + + +CHAPTER VIII. + +_FIRING POINT OF EXPLOSIVES, HEAT TESTS, &c._ + +Horsley's Apparatus--Table of Firing points--The Government Heat-Test +Apparatus for Dynamites--Nitro-Glycerine, Nitro-Cotton, and Smokeless +Powders--Liquefaction and Exudation Tests--Page's Regulator for Heat-Test +Apparatus--Specific Gravities of Explosives--Table of Temperature of +Detonation, Sensitiveness, &c. + + +~The Firing Point of Explosives.~--The firing point of an explosive may be +determined as follows:--A copper dish, about 3 inches deep, and 6 or more +wide, and fitted with a lid, also of copper, is required. The lid contains +several small holes, into each of which is soldered a thick copper tube +about 5 mm. in diameter, and 3 inches long, with a rather larger one in +the centre in which to place a thermometer. The dish is filled with Rose's +metal, or paraffin, according to the probable temperature required. The +firing point is then taken thus:--After putting a little piece of asbestos +felt at the bottom of the centre tube, the thermometer is inserted, and a +small quantity of the explosive to be tested is placed in the other holes; +the lid is then placed on the dish containing the melted paraffin or +metal, in such a way that the copper tubes dip below the surface of the +liquid; the temperature of the bath is now raised until the explosive +fires, and the temperature noted. The initial temperature should also be +noted. + +THE FIRING POINT OF VARIOUS EXPLOSIVES (by C. E. Munroe). +(Horsley's Apparatus used.) + +_____________________________________________________________________ + | + | °C. +Nitro-glycerine, 5 years old (a single drop taken) | 203-205 +Gun-cotton (compressed military cotton, sp. gr. 1.5) | 192-201 +Air-dried gun-cotton, stored for 4 years | 179-187 +Ditto, stored for 1 year | 187-189 +Air-dried collodion-cotton, long staple "Red Island | + cotton," 3 years old | 186-191 +Air-dried collodion, 3 years old, stored wet | 197-199 +Hydro-nitro-cellulose | 201-213 +Kieselguhr dynamite, No. 1 | 197-200 +Explosive gelatine | 203-209 +Mercury fulminate | 175-181 +Gunpowder (shell) | 278-287 +Hill's picric powder (shells) Been in store 10 years. | 273-283 +Ditto (musket) Composed of-- | 282-290 + Ammonium picrate 42.18 % | + Potassium picrate 53.79 " | + Charcoal (alder) 3.85 " | + ________ | + | + 99.82 | +Forcite, No. 1 | 187-200 +Atlas powder (75% NG) | 175-185 +Emmensite, No. 1 Sample had been stored in | 167-184 + magazine for some months in | + a wooden box. | + " No. 2 Stored in tin case. | 165-177 + " No. 5 " " | 205-217 +__________________________________________________________|__________ + | | + | °C. | +Powder used in Chassepôt rifle | 191 | By Leygue & Champion. +French gunpowder | 295 | " " +Rifle powder (picrate) | 358 | " " +Cannon | 380 | " " +__________________________________|_________|________________________ + +Horsley's apparatus consists of an iron stand with a ring support, holding +a hemispherical iron vessel or bath in which solid paraffin is put. Above +this is another movable support, from which a thermometer is suspended, +and so adjusted that its bulb is immersed in the material contained in the +iron vessel. A thin copper cartridge-case, 5/8 inch in diameter and +1-15/16 inch long, is suspended over the bath by means of a triangle, so +that the end of the case is just 1 inch below the surface of the molten +material. On beginning the experiment of determining the firing point of +any explosive, the material in the bath is heated to just above the +melting point; the thermometer is inserted in it, and a minute quantity of +the explosive is placed in the bottom of the cartridge-case. The initial +temperature is noted, and then the cartridge-case containing the explosive +is inserted in the bath. The temperature is quickly raised until the +contents of the cartridge-case flash off or explode, when the temperature +is noted as the _firing point_. + +[Illustration: FIG. 46.--HEAT TEST APPARATUS.] + +Professor C.E. Munroe, of the U.S. Torpedo Station, has determined the +firing point of several explosives by means of this apparatus. + +~The Government Heat Test (Explosives Act, 1875): Apparatus required.~--A +water bath, consisting of a spherical copper vessel _(a)_, Fig. 46, of +about 8 inches diameter, and with an aperture of about 5 inches; the bath +is filled with water to within a quarter of an inch of the edge. It has a +loose cover of sheet copper about 6 inches in diameter _(b)_ and rests on +a tripod stand about 14 inches high _(c)_, which is covered with coarse +wire gauze _(e)_, and is surrounded with a screen of thin sheet copper +_(d)_. Within the latter is placed an argand burner _(f)_ with glass +chimney. The cover _(b)_ has four holes arranged, as seen in Fig. II., No. +4 to contain a Page's[A] or Scheibler's regulator, No. 3 the thermometer, +Nos. 1 and 2 the test tubes containing the explosive to be tested. Around +the holes 1 and 2 on the under side of the cover are soldered three pieces +of brass wire with points slightly converging (Fig. III.); these act as +springs, and allow the test tubes to be easily placed in position and +removed. + +[Footnote A: See _Chem. Soc. Jour._, 1876, i. 24. F.J.M. Page.] + +~Test Tubes~, from 5-1/4 to 5-1/2 inches long, and of such a diameter that +they will hold from 20 to 22 cubic centimetres of water when filled to a +height of 5 inches; rather thick glass is preferable. Indiarubber +stoppers, fitting the test tubes, and carrying an arrangement for holding +the test papers, viz., a narrow glass tube passing through the centre of +the stopper, and terminating in a platinum wire hook. A glass rod drawn +out and the end turned up to form a hook is better. + +~The Thermometer~ should have a range from 30° to 212° F., or from 1° to +100° C. A minute clock is useful. + +~Test Paper.~--The test paper is prepared as follows:--45 grains (2.9 +grms.) of white maize starch (corn flour), previously washed with cold +water, are added to 8-1/2 oz. of water. The mixture is stirred, heated to +boiling, and kept gently boiling for ten minutes; 15 grains (1 grm.) of +pure potassium iodide (previously recrystallised from alcohol, absolutely +necessary) are dissolved in 8-1/2 oz. of distilled water. The two +solutions are thoroughly mixed and allowed to get cold. Strips or sheets +of white English filter paper, previously washed with water and re-dried, +are dipped into the solution thus prepared, and allowed to remain in it +for not less than ten seconds; they are then allowed to drain and dry in a +place free from laboratory fumes and dust. The upper and lower margins of +the strips or sheets are cut off, and the paper is preserved in well- +stoppered or corked bottles, and in the dark. The dimensions of the pieces +of test paper used are about 4/10 inch by 8/10 inch (10 mm. by 20 mm.).[A] + +[Footnote A: When the paper is freshly prepared, and as long as it remains +in good condition, a drop of diluted acetic acid put on the paper with a +glass rod produces no coloration. In process of time it will become +brownish, when treated with the acid, especially if it has been exposed to +sunlight. It is then not fit for use.] + +In Germany zinc-iodide starch paper is used, which is considered to be +more sensitive than potassium iodide. + +~Standard Tint Paper.~--A solution of caramel in water is made of such +concentration that when diluted one hundred times (10 c.c. made up to 1 +litre) the tint of this diluted solution equals the tint produced by the +Nessler test in 100 c.c. water containing .000075 grm. of ammonia, or +.00023505 grm. AmCl. With this caramel solution lines are drawn on strips +of white filter paper (previously well washed with distilled water, to +remove traces of bleaching matter, and dried) by means of a quill pen. +When the marks thus produced are dry, the paper is cut into pieces of the +same size as the test paper previously described, in such a way that each +piece has a brown line across it near the middle of its length, and only +such strips are preserved in which the brown line has a breadth varying +from 1\2 mm. to 1 mm. (1/50 of an inch to 1/25 of an inch). + +~Testing Dynamite, Blasting Gelatine, and Gelatine Dynamite.~--Nitro- +glycerine preparations, from which the nitro-glycerine can be extracted in +the manner described below, must satisfy the following test, otherwise +they will not be considered as manufactured with "thoroughly purified +nitro-glycerine," viz., fifteen minutes at 160° F. (72° C.). + +~Apparatus required.~--A funnel 2 inches across (_d_), a cylindrical +measure divided into grains (_e_), Fig. 47. + +~Mode of Operation.~--About 300 (19.4 grms.) to 400 grains (26 grms.) of +dynamite (_b_), finely divided, are placed in the funnel, which is loosely +plugged by freshly ignited asbestos (_a_). The surface is smoothed by +means of a flat-headed glass rod or stopper, and some clean washed and +dried kieselguhr (_c_) is spread over it to the depth of about 1/8 inch. +Water is then poured on from a wash bottle, and when the first portion has +been soaked up more is added; this is repeated until sufficient nitro- +glycerine has collected in the graduated measure (_e_). If any water +should have passed through, it must be removed from the nitro-glycerine by +filter paper, or the nitro-glycerine may be filtered. + +[Illustration: FIG. 47.--APPARATUS FOR SEPARATING THE NlTRO-GLYCERINE FROM +DYNAMITE.] + +[Illustration: FIG. 48.--TEST TUBE ARRANGED FOR HEAT TEST.] + +~Application of Test.~--The thermometer is fixed so as to be inserted +through the lid of the water bath into the water, which is maintained at +160° F. (72° C.), to a depth of 2-3/4 inches. Fifty grains (= 3.29 grms.) +of nitro-glycerine to be tested are weighed into the test tube, in such a +way as not to soil the sides of the tube (use a pipette). A test paper is +fixed on the hook of the glass rod, so that when inserted into the tube it +will be in a vertical position. A sufficient amount of a mixture of half +distilled water and half glycerine, to moisten the upper half of the +paper, is now applied to the upper edge of the test paper by means of a +glass rod or camel's hair pencil; the cork carrying the rod and paper is +fixed into the test tube, and the position of the paper adjusted so that +its lower edge is about half way down the tube; the latter is then +inserted through one of the holes in the cover to such a depth that the +lower margin of the moistened part of the paper is about 5/8 inch above +the surface cover. The test is complete when the faint brown line, which +after a time makes its appearance at the line of boundary between the dry +and moist part of the paper, equals in tint the brown line of the standard +tint paper. + +~Blasting Gelatine, Gelatine Dynamite, Gelignite, &c.~--Fifty grains (= +3.29 grms.) of blasting gelatine are intimately mixed with 100 grains (= +6.5 grms.) of French chalk. This is done by carefully working the two +materials together with a wooden pestle in a wooden mortar. The mixture is +then gradually introduced into the test tube, with the aid of gentle +tapping upon the table between the introduction of successive portions of +the mixture into the tube, so that when the tube contains all the mixture +it shall be filled to the extent of 1-3/4 inch of its height. The test +paper is then inserted as above described for nitro-glycerine. The sample +tested must stand a temperature of 160° F. for a period of ten minutes +before producing a discoloration of the test paper corresponding in tint +to the standard paper. + +_N.B._--Non-gelatinised nitro-glycerine preparations, from which the +nitro-glycerine cannot be expelled by water, are tested without any +previous separation of the ingredients, the temperature being as above +160° F., and the time being seven minutes. + +~Gun-Cotton, Schultze Gunpowder, E.C. Powder, &c.: A. Compressed Gun- +Cotton.~--Sufficient material to serve for two or more tests is removed +from the centre of the cartridge by gentle scraping, and if necessary, +further reduced by rubbing between the fingers. The fine powder thus +produced is spread out in a thin layer upon a paper tray 6 inches by 4-1/2 +inches, which is then placed inside a water oven, kept as nearly as +possible at 120° F. (49° C.). The wire gauze shelves of the oven should be +about 3 inches apart. The sample is allowed to remain at rest for fifteen +minutes in the oven, the door of which is left wide open. After the lapse +of fifteen minutes the tray is removed and exposed to the air of the room +for two hours, the sample being at some point within that time rubbed upon +the tray with the hand, in order to reduce it to a fine and uniform state +of division. + +The heat test is performed as before, except that the temperature of the +bath is kept at 170° F. (66° C.), and regulator set to maintain that +temperature. Twenty grains (1.296 grm.) are used, placed in the test tube, +gently pressed down until it occupies a space of as nearly as possible +1-5/10 inch in the test tube of dimensions previously specified. The fine +cotton adhering to the sides of the tube can be removed by a clean cloth +or silk handkerchief. The paper is moistened by touching the upper edge +with a drop of the 50 per cent. glycerine solution, the tube inserted in +the bath to a depth of 2-1/2 inches, measured from the cover, the +regulator and thermometer being inserted to the same depth. The test paper +is to be kept near the top of the test tube, but clear of the cork, until +the tube has been immersed for about five minutes. A ring of moisture will +about this time be deposited upon the sides of the test tube, a little +above the cover of the bath. The glass rod must then be lowered until the +lower margin of the moistened part of the paper is on a level with the +bottom of the ring of moisture in the tube. The paper is now closely +watched, The test is complete when a very faint brown coloration makes its +appearance at the line of boundary between the dry and moist parts of the +paper. It must stand the test for not less than ten minutes at 170° F. +(The time is reckoned from the first insertion of the tube in the bath +until the appearance of a discoloration of the test paper.) + +~B. Schultze Powder, E.C. Powder, Collodion-Cotton, &c.~--The sample is +dried in the oven as above for fifteen minutes, and exposed for two hours +to the air. The test as above for compressed gun-cotton is then applied. + +~C. Cordite~ must stand a temperature of 180° F. for fifteen minutes. The +sample is prepared as follows:--Pieces half an inch long are cut from one +end of every stick selected for the test: in the case of the thicker +cordites, each piece so cut is further subdivided into about four +portions. These cut pieces are then passed once through the mill, the +first portion of material which passes through being rejected on account +of the possible presence of foreign matter from the mill. The ground +material is put on the top sieve of the nest of sieves, and sifted. That +portion which has passed through the top sieve and been stopped by the +second is taken for the test. If the mill is properly set, the greater +portion of the ground material will be of the proper size. If the volatile +matter in the explosive exceeds 0.5 per cent., the sifted material should +be dried at a temperature not exceeding 140° F, until the proportion does +not exceed 0.5 per cent. After each sample has been ground, the mill must +be taken to pieces and carefully cleaned. The sieves used consist of a +nest of two sieves with holes drilled in sheet copper. The holes in the +top sieve have a diameter = 14 B.W.G., those in the second = 21 B.W.G. + +If too hard for the mill, the cordite may be softened by exposure to the +vapour of acetone,[A] or reduced, to the necessary degree of subdivision +by means of a sharp moderately-coarse rasp. Should it have become too soft +in the acetone vapour for the mill, it should be cut up into small pieces, +which may be brought to any desired degree of hardness by simple exposure +to air. Explosives which consist partly of gelatinised collodion-cotton, +and partly of ungelatinised gun-cotton, are best reduced to powder by a +rasp, or softened by exposure to mixed ether and alcohol vapour at a +temperature of 40° F. to 100° F. + +[Footnote A: Mr W. Cullen _(Jour. Soc. Chem. Ind._, Jan. 31, 1901) says:-- +"Undoubtedly the advent of the horny smokeless powders of modern times has +made it a little difficult to give the test the same scope as it had when +first introduced." As a rule a simple explanation can be found for every +apparently abnormal result, and in the accidental retention of a portion +of the solvent used in the manufacture, will frequently be found an +explanation of the trouble experienced.] + +~Ballistite.~--In the case of ballistite the treatment is the same, except +that when it is in a very finely granulated condition it need not be cut +up. + +~Guttmann's Heat Test.~--This test was proposed by Mr Oscar Guttmann in a +paper read before the Society of Chemical Industry (vol. xvi., 1897), in +the place of the potassium iodide starch paper used in the Abel test. The +filter paper used is wetted with a solution of diphenylamine[A] in +sulphuric acid. The solution is prepared as follows:--Take 0.100 grm. of +diphenylamine crystals, put them in a wide-necked flask with a ground +stopper, add 50 c.c. of dilute sulphuric acid (10 c.c. of concentrated +sulphuric acid to 40 c.c. of water), and put the flask in a water bath at +between 50° and 55° C. At this temperature the diphenylamine will melt, +and at once dissolve in the sulphuric acid, when the flask should be taken +out, well shaken, and allowed to cool. After cooling, add 50 c.c. of +Price's double distilled glycerine, shake well, and keep the solution in a +dark place. The test has to be applied in the following way:--The +explosives that have to be tested are finely subdivided, gun-cotton, +nitro-glycerine, dynamite, blasting gelatine, &c., in the same way as at +present directed by the Home Office regulations. Smokeless powders are all +to be ground in a bell-shaped coffee mill as finely as possible, and +sifted as hitherto. 1.5 grm. of the explosive (from the second sieve in +the case of smokeless powder) is to be weighed off and put into a test +tube as hitherto used. Strips of well-washed filter paper, 25 mm. wide, +are to be hung on a hooked glass rod as usual. A drop of the diphenylamine +solution is taken up by means of a clean glass rod, and the upper corners +of the filter paper are touched with it, so that when the two drops run +together about a quarter of the filter paper is moist. This is then put +into the test tube, and this again into the water bath, which has been +heated to 70° C. The heat test reaction should not show in a shorter time +than fifteen minutes. It will begin by the moist part of the paper +acquiring a greenish yellow colour, and from this moment the paper should +be carefully watched. After one or two minutes a dark blue mark will +suddenly appear on the dividing line between the wet and dry part of the +filter paper, and this is the point that should be taken. + +[Footnote A: Dr G. Spica (_Rivista_, Aug. 1897) proposes to use +hydrochloride of meta-phenylenediamine.] + +~Exudation and Liquefaction Test for Blasting Gelatine, Gelatine Dynamite, +&c.~--A cylinder of blasting gelatine, &c., is to be cut from the +cartridge to be tested, the length of the cylinder to be equal to its +diameter, and the ends being cut flat. The cylinder is to be placed on end +on a flat surface without any wrapper, and secured by a pin passing +vertically through its centre. In this condition the cylinder is to be +exposed for 144 consecutive hours (six days and nights) to a temperature +ranging from 85° to 90° F. (inclusive), and during such exposure the +cylinder shall not diminish in height by more than one-fourth of its +original height, and the upper cut surface shall retain its flatness and +the sharpness of its edge. + +~Exudation Test.~--There shall be no separation from the general mass of +the blasting gelatine or gelatine dynamite of a substance of less +consistency than the bulk of the remaining portion of the material under +any conditions of storage, transport, or use, or when the material is +subjected three times in succession to alternate freezing and thawing, or +when subjected to the liquefaction test before described. + +~Picric Acid.~--The material shall contain not more than 0.3 part of +mineral or non-combustible matter in 100 parts by weight of the material +dried at 160° F. It should not contain more than a minute trace of lead. +One hundred parts of the dry material shall not contain more than 0.3 part +of total (free and combined) sulphuric acid, of which not more than 0.1 +part shall be free sulphuric acid. Its melting point should be between +248° and 253° F. + +~Ammonite, Bellite, Roburite, and Explosives of similar Composition.~-- +These are required to stand the same heat test as compressed +nitro-cellulose, gun-cotton, &c. + +~Chlorate Mixtures.~--The material must not be too sensitive, and must +show no tendency to increase in sensitiveness in keeping. It must contain +nothing liable to reduce the chlorate. Chlorides calculated as potassium +chloride must not exceed 0.25 per cent. The material must contain no free +acid, or substance liable to produce free acid. Explosives of this class +containing nitro-compounds will be subject to the heat test. + +~Page's Regulator.~--The most convenient gas regulator to use in +connection with the heat-test apparatus is the one invented by Prof. +F.J.M. Page, B.Sc.[A] (Fig. 49). It is not affected by variations of the +barometric pressure, and is simple and easy to fit up. It consists of a +thermometer with an elongated glass bulb 5/8 inch diameter and 3 inches +long. The stem of the thermometer is 5 inches long and 1/8 inch to 3/16 +inch internal diameter. One and a half inch from the top of the stem is +fused in at right angles a piece of glass tube, 1 inch long, of the same +diameter as the stem, so as to form a T. A piece of glass tube (A), about +7/16 inch external diameter and 1-1/2 inch long, is fitted at one end with +a short, sound cork (C, Fig. 50). Through the centre of this cork a hole +is bored, so that the stem of the thermometer just fits into it. The other +end of this glass tube is closed by a tightly fitting cork, preferably of +indiarubber (I), which is pierced by a fine bradawl through the centre. +Into the hole thus made is forced a piece of fine glass tube (B) 3 inches +long, and small enough to fit loosely inside the stem of the thermometer. + +[Footnote A: _Chemical Soc. Jour._, 1876, i. 24.] + +The thermometer is filled by pouring in mercury through a small funnel +until the level of the mercury (when the thermometer is at the desired +temperature) is about 1-1/2 inch below the T. The piece of glass tube A, +closed at its upper extremity by the cork I, through which the fine glass +tube B passes into the stem of the thermometer, is now filled by means of +the perforated cork at its lower extremity on the stem of the thermometer. +The gas supply tube is attached to the top of the tube A, the burner to +the T, so that the gas passes in at the top, down the fine tube B, rises +in the space between B and the inside wall of the stem of the thermometer, +and escapes by the T. The regulator is set for any given temperature by +pushing the cork C, and consequently the tubes A and B, which are firmly +attached to it, up or down the stem of the thermometer, until the +regulator just cuts off the gas at the desired temperature. + +[Illustration: FIG. 49.--PAGE'S REGULATOR.] + +[Illustration: FIG. 50.--PAGE'S GAS REGULATOR, SHOWING BYE-PASS AND +CUT-OFF ARRANGEMENT.] + +As soon as the temperature falls, the mercury contracts, and thus opens +the end of the tube B. The gas is thus turned on, and the temperature +rises until the regulator again cuts off the gas. In order to prevent the +possible extinction of the flame by the regulator, the brass tube which +carries the gas to the regulator is connected with the tube which brings +the gas from the regulator to the burner by a small brass tap (Fig. 2). +This tap forms an adjustable bye-pass, and thus a small flame can be kept +burning, even though the regulator be completely shut off. It is obvious +that the quantity of gas supplied through the bye-pass must always be less +than that required to maintain the desired temperature. This regulator, +placed in a beaker of water on a tripod, will maintain the temperature of +the water during four or five hours within 0.2° C., and an air bath during +six weeks within 0.5° C. + +To sum up briefly the method of using the regulator:--Being filled with +mercury to about 1\2 inch below the T, attach the gas supply as in diagram +(Fig. 2), the brass tap being open, and the tube B unclosed by the +mercury. Allow the gas to completely expel the air in the apparatus. Push +down the tube A so that the end of B is well under the surface of the +mercury. Turn off the tap of the bye-pass until the smallest bead of flame +is visible. Raise A and B, and allow the temperature to rise until the +desired point is attained. Then push the tubes A and B slowly down until +the flame is just shut off. The regulator will then keep the temperature +at that point. + +~Will's Test for Nitro-Cellulose.~--The principle of Dr W. Will's test[A] +may be briefly described as follows:--The regularity with which nitro- +cellulose decomposes under conditions admitting of the removal of the +products of decomposition immediately following their formation is a +measure of its stability. As decomposing agent a sufficiently high +temperature (135° C.) is employed, the explosive being kept in a +constantly changing atmosphere of carbon dioxide, heated to the same +temperature: the oxides of nitrogen which result are swept over red-hot +copper, and are then reduced to nitrogen, and finally, the rates of +evolution of nitrogen are measured and compared. Dr Will considers that +the best definition and test of a stable nitro-cellulose is that it should +give off at a high temperature equal quantities of nitrogen in equal +times. For the purposes of manufacture, it is specially important that the +material should be purified to its limit, i.e., the point at which further +washing produces no further change in its speed of decomposition measured +in the manner described. + +[Footnote A: W. Will, _Mitt. a. d. Centrallstelle f. Wissench. Techn. +Untersuchungen Nuo-Babelsberg Berlin_, 1902 [2], 5-24.] + +The sample of gun-cotton (2.5 grms.) is packed into the decomposition tube +15 mm. wide and 10 cm. high, and heated by an oil bath to a constant +temperature, the oxides so produced are forced over ignited copper, where +they are reduced, and the nitrogen retained in the measuring tubes. Care +must be taken that the acid decomposition products do not condense in any +portion of the apparatus. The air in the whole apparatus is first +displaced by a stream of carbon dioxide issuing from a carbon dioxide +generator, or gas-holder, and passing through scrubbers, and this stream +of gas is maintained throughout the whole of the experiment, the gas being +absorbed at the end of the system by strong solution of caustic potash. To +guard against the danger of explosions, which occasionally occur, the +decomposition tube and oil bath are surrounded by a large casing with +walls composed of iron plate and strong glass. + +Dr Will's apparatus has been modified by Dr Robertson,[A] of the Royal +Gunpowder Factory, Waltham Abbey. The form of the apparatus used by him is +shown in Fig. 51. + +~CO_{2} Holders.~--Although objection has been taken to the use of +compressed CO_{2} in steel cylinders on account of the alleged large and +variable amount of air present, it has, nevertheless, been found possible +to obtain this gas with as little as 0.02 per cent. of air. Frequent +estimations of the air present in the CO_{2} of a cylinder show that even +with the commercial article, after the bulk of the CO_{2} has been +removed, the residual gas contains only a very small amount of air, which +decreases in a gradual and perfectly regular manner. For example, one +cylinder which gave 0.03 per cent. of air by volume, after three months' +constant use gave 0.02 per cent. The advantage of using CO_{2} from this +source is obvious when compared with the difficulty of evolving a stream +of gas of constant composition from a Kipps or Finkener apparatus. A +micrometer screw, in addition to the main valve of the CO_{2} cylinder, is +useful for governing the rate of flow. A blank experiment should be made +to ascertain the amount of air in the CO_{2} and the correction made in +the readings afterwards. + +[Footnote A: _Jour. Soc. Chem. Ind._, June 30, 1902, p. 819.] + +[Illustration: Fig 51.--Will's Apparatus for Testing Nitro-cellulose] + +~Measurement of Pressure and Rate of Flow.~--Great attention is paid to +the measurement of the rate of flow of gas, which is arrived at by +counting with a stop-watch the number of bubbles of gas per minute in a +small sulphuric acid wash bottle. A mercury manometer is introduced here, +and is useful for detecting a leak in the apparatus. The rate of flow that +gives the most satisfactory results is 1,000 c.c. per hour. If too rapid +it does not become sufficiently preheated in the glass spiral, and if too +slow there is a more rapid decomposition of the nitro-cellulose by the +oxides of nitrogen which are not removed. + +~Decomposition Tube.~--This is of the form and dimensions given by Dr Will +(15 mm. wide and 10 cm. high), the preheating worm being of the thinnest +hydrometer stem tubing. The ground-in exit tube is kept in position by a +small screw clamp with trunnion bearings. + +~Bath.~--To permit of two experiments being carried on simultaneously, the +bath is adapted for two decomposition tubes, and is on the principle of +Lothar Meyer's air bath, that is, the bath proper filled with a high- +flashing hydrocarbon oil, and fitted with a lid perforated with two +circular holes for the spiral tubes, is surrounded by an asbestos-covered +envelope, in the interior of which circulate the products of combustion of +numerous small gas jets. The stirrer, agitated by a water motor, or, +better still, a hot-air engine, has a series of helical blades curved to +give a thorough mixing to the oil. Great uniformity and constancy of +temperature are thus obtained. The bath is fitted also with a temperature +regulator and thermometer. + +~Reduction Tube~--This is of copper, and consists of two parts, the outer +tube and an inner reaching to nearly the bottom of the former. Into the +inner tube fits a spiral of reduced copper gauze, and into the annular +space between the tubes is fitted a tightly packed reduced copper spiral. +At the bottom the inlet tube dips into a layer of copper oxide asbestos, +on the top of which is a layer of reduced copper asbestos. Through the +indiarubber cork passes a glass tube, which leads the CO_{2} and nitrogen +out of the reduction tube. As the portion of the tube containing the +spirals is heated to redness, water jackets are provided on both inner and +outer tubes to protect the indiarubber cork. + +~Nitrogen Measuring Apparatus.~--The measuring tube with zigzag +arrangement is used, having been found very economical in potash. It is +most convenient to take readings by counterbalancing the column of potash +solution and reading off the volume of gas at atmospheric pressure. For +this purpose the tap immediately in front of the measuring tube is +momentarily closed, this having been proved to be without ill effect on +the progress of the test. In all experiments done by this test the air +correction is subtracted from each reading, and the remainder brought to +milligrams of nitrogen with the usual corrections. As objection has +frequently been taken to the test on the ground of difficulty in +interpreting the results obtained, Dr Robertson made a series of +experiments for the purpose of standardising the test, and at the same +time of arriving at the condition under which it could be applied in the +most sensitive and efficient manner. A variety of nitro-celluloses having +been tested, there were chosen as typical, of stable and unstable +products, service gun-cotton on the one hand, and an experimental gun- +cotton, Z, on the other. The first point brought out by these experiments +was the striking uniformity of service gun-cotton, first in regard to the +rectilinear nature of the curve of evolution of nitrogen, and secondly in +regard to the small range within which a large number of results is +included, 15 samples lying between 6.6 and 8.7 mgms. of nitrogen evolved +in four hours. In the case of service gun-cotton, little difference in the +rate of evolution of nitrogen evolved is obtained on altering the rate of +passage of CO_{2} gas through the wide range of 500 c.c. per hour to 2,500 +c.c. per hour. With Z gun-cotton (see Fig. 52), however, the case is very +different. Operating at a rate of 1,000 c.c. of CO_{2} per hour, a curve +of nitrogen evolution is obtained, which is bent and forms a good +representation of the inherent instability of the material as proved to +exist from other considerations. Operating at the rate of 1,500 c.c. per +hour, as recommended by Dr Will, the evolution of nitrogen is represented +by a straight line, steeper, however, than that of service gun-cotton. The +rate of passage of CO_{2} was therefore chosen at 1,000 c.c. per hour, or +two-thirds of the rate of Dr Will, and this rate, besides possessing the +advantage claimed of rendering diagnostic the manner of nitrogen evolution +in Z gun-cotton, has in other cases been useful in bringing out +relationships, which the higher rate would have entirely masked. + +[Illustration: Fig. 52.--Dr. Robertson's results.] + +[Illustration: Fig. 53.--Service Guncotton for Cordite made at a Private +Factory.] + +Readings are taken thirty minutes from the time the nitro-cellulose is +heated, and are taken at intervals of fifteen minutes for about four +hours; fresh caustic potash is added every thirty minutes or so. It is +convenient to plot the results in curves. The curves given in Fig. 53 are +from gun-cotton manufacturers in England at a private factory. The rate of +evolution of nitrogen is as follows:-- + +In 1 hour. In 2 hours. In 3 hours. In 4 hours. + N. N. N. N. in milligrammes. + 1.25 2.55 4.5 5.75 + 1.5 3.25 5.25 6.75 +These results are very satisfactory, the gun-cotton was of a very good +quality. Several hours are necessary to remove all the air from the +apparatus. Dr Will stated fifteen minutes in his original paper, but this +has not been found sufficient. It has not been satisfactorily proved that +Will's test can be applied to gelatinised nitro-cellulose powders. It is +convenient to plot the results in curves; the nitrogen is generally given +in cubic centimetres or in milligrammes, and readings taken every fifteen +minutes. The steepness of the curve is a measure of the stability of the +nitro-cellulose which is being examined. The steeper the curve the more +nitrogen is evolved per unit of time, and the less stable the nitro- +cellulose. In the case of unstable nitro-celluloses heated under the +conditions described, the separation of nitrogen is much greater at first +than at a later period. If the nitro-cellulose be very unstable, +explosions are produced. If the separation of nitrogen is uniform during +the prolonged heating, then the nitro-cellulose may be regarded as +"normal." If it be desired to determine the absolute amount of nitrogen +separated from a nitro-cellulose, the following conditions must be +observed:--(1.) Accurate weighing of the nitro-cellulose; (2.) +Determination of the amount of air in the CO_{2}, and deduction of this +from the volume of gas obtained; (3.) Reduction of the volume of the gas +to the volume at 0° C. and 760 mm. pressure.[A] + +[Footnote A: See also _Jour. Soc. Chem. Ind._, Dec. 1902, pages 1545-1555, +on the "Stability of Nitro-cellulose" and "Examination of Nitro- +cellulose," Dr Will.] + +~Bergrnann and Junk~[A] describe a test for nitro-cellulose that has been +in use in the Prussian testing station for some years. The apparatus +consists of a closed copper bath provided with a condenser and 10 +countersunk tubes of 20 cm. length. By boiling amyl-alcohol in the bath, +the tubes can be kept at a constant temperature of 132° C. The explosive +to be tested is placed in a glass tube 35 cm. long and 2 cm. wide, having +a ground neck into which an absorption bulb is fitted. The whole apparatus +is surrounded by a shield, in case of explosion. In carrying out the test, +2 grms. of the explosive are placed in the glass tube and well pressed +down. The absorption bulb is half filled with water, and fitted into the +ground neck of the glass tube, which is then placed in one of the tubes in +the bath previously brought to the boiling point (132° C.). The evolved +oxides of nitrogen are absorbed in the water in the bulb, and at the end +of two hours the tubes are removed from the bath, and on cooling, the +water from the bulb flows back and wets the explosive. The contents of the +tube are filtered and washed, the filtrate is oxidised with permanganate, +and the nitrogen determined as nitric oxide by the Schultze-Tieman method. +The authors conclude that a stable gun-cotton does not evolve more than +2.5 c.c. of nitric oxide per grm. on being heated to 132° C. for two +hours, and a stable collodion-cotton not more than 2 c.c. under the same +conditions. The percentage of moisture in the sample to be tested should +be kept as low as possible. A sample of nitro-cellulose containing 1.97% +of moisture gave an evolution of 2.6 c.c. per grm., while the same sample +with 3.4% moisture gave an evolution of over 50 c.c. per grm. Sodium +carbonate added to an unstable nitro-cellulose diminishes the rate of +decomposition, but if sodium carbonate be intimately mixed with a stable +nitro-cellulose the rate of decomposition will be increased. Calcium +carbonate and mercury chloride have no influence. If an unstable nitro- +cellulose be extracted with alcohol a stable compound is produced. The +percentage solubility of a nitro-cellulose in ether-alcohol rises on +heating to 132° C. A sample which before heating had a solubility of 4.7% +had its solubility increased to 82.5% after six hours' heating. + +[Footnote A: _Jour. Soc. Chem. Ind._, xxiii., Oct. 15, 1904, p. 953.] + +Mr A.P. Sy (_Jour. Amer. Chem. Soc._, 1903) describes a new stability test +for nitro-cellulose which he terms "The Elastic Limit of Powder Resistance +to Heat." The test consists in heating the powder on a watch glass in an +oven to a temperature of 115° C., after eight hours the watch glass and +powder are weighed and the process repeated daily for six days or less. He +claims that the powder is tested in its natural state, all the products of +decomposition are taken into account, whilst in the old tests only the +acid products are shown, and in the Will test only nitrogen, that it +affords an indication of the effect of small quantities of added +substances or foreign matters on the stability and that it is simple, and +not subject to the variations of the old tests. + +Obermüller (_Jour. Soc. Chem. Ind._, April 15, 1905) considers Bergmann +and Junk's test is too complicated and occupies too much time; he proposes +to heat gun-cotton to 140° C. _in vacuo_, and to measure continuously by +means of a mercury manometer the pressure exerted by the evolved gases, +the latter being maintained at constant volume; the rate at which the +pressure increases is a measure of the rate of decomposition of the nitro- +cellulose. + +SPECIFIC GRAVITIES OF EXPLOSIVES, &C. + +Nitro-glycerine 1.6 +Gun-cotton (dry) 1.06 + " (25 per cent. water) 1.32 +Dynamite No. 1 1.62 +Blasting gelatine 1.54 +Gelatine dynamite 1.55 +Ballistite 1.6 +Forcite 1.51 +Tonite 1.28 +Roburite 1.40 +Bellite 1.2-1.4 +Carbo-dynamite 1.5 +Turpin's cast picric acid 1.6 +Nitro-mannite 1.6 +Nitro-starch 1.5 +Emmensite 1.8 +Mono-nitro-benzene 1.2 +Meta-di-nitro-benzene 1.575 at 18° C. +Ortho-di-nitro-benzene 1.590 " +Para-di-nitro-benzene 1.625 " +British gunpowder, E.X.E. 1.80 + " " S.B.C. 1.85 +Cannonite (powder) 1.60 +Celluloid 1.35 +Cellulose 1.45 +Ammonium nitrate 1.707 +Mercury fulminate 4.42 + +TABLE OF THE TEMPERATURE OF DETONATION. + +Blasting gelatine 3220° +Nitro-glycerine 3170° +Dynamite 2940° +Gun-cotton 2650° +Tonite 2648° +Picric acid 2620° +Roburite 2100° +Ammonia nitrate 1130° + +RELATIVE SENSITIVENESS TO DETONATION (by Professor C.E. Munroe, U.S. Naval +Torpedo Station). + +__________________________________________________________________________ + | + | Maximum | + | Distance | + | at which | + | Detonation | + | occurred. | + | CM. | + | | +Gun-cotton | 10 | Nitro-glycerine 86.5 nitro-cotton + | | 9.5, camphor 4 per cent. +Explosive gelatine | 20 | NH_{4}NO_{3} 5 parts, +(camphorated) | | C_{6}H_{4}(N0_{3})_{2} 1 part. +Judson powder, R.R.P. | 25 | +Emmensite (No. 259) | 30 | +Rack-a-rock | 32 | KClO_{3} 79 parts, + | | C_{6}H_{5}(NO)_{2} 21 parts. +Bellite | 50 | +Forcite No. 1 | 61 | +Kieselguhr dynamite No. 1 | 64 | 75 per cent. nitro-gycerine. +Atlas powder No. 1 | 74 | +__________________________|____________|_________________________ + + + +CHAPTER IX. + +_DETERMINATION OF THE RELATIVE STRENGTH OF EXPLOSIVES._ + +Effectiveness of an Explosive--High and Low Explosives--Theoretical +Efficiency--MM. Roux and Sarrau's Results--Abel and Noble's--Nobel's +Ballistic Test--The Mortar, Pressure, or Crusher Gauge--Lead Cylinders-- +The Foot-Pounds Machine--Noble's Pressure Gauge--Lieutenant Walke's +Results--Calculation of Pressure Developed by Dynamite and Gun-Cotton-- +Macnab's and Ristori's Results of Heat Developed by the Explosion of +Various Explosives--Composition of some of the Explosives in Common Use +for Blasting, &c. + + +~The Determination of the Relative Strength of Explosives.~--Explosives +may be roughly divided into two divisions, viz., those which when exploded +produce a shattering force, and those which produce a propulsive force. +Explosives of the first class are generally known as the high explosives, +and consist for the most part of nitro compounds, or mixtures of nitro +compounds with other substances. Any explosive whose detonation is very +rapid is a high explosive, but the term has chiefly been applied to the +nitro-explosives. + +The effectiveness of an explosive depends upon the volume and temperature +of the gases formed, and upon the rapidity of the explosion. In the high +explosives the chemical transformation is very rapid, hence they exert a +crushing of shattering effect. Gunpowder, on the other hand, is a low +explosive, and produces a propelling or heaving effect. + +The maximum work that an explosive is capable of producing is +proportionate to the amount of heat disengaged during its chemical +transformation. This may be expressed in kilogrammetres by the formula +425Q, where Q is the number of units of heat evolved. The theoretical +efficiency of an explosive cannot, however, be expected in practice for +many reasons. + +In the case of blasting rock, for instance:[A]--1. Incomplete combustion +of the explosive. 2. Compression and chemical changes induced in the +surrounding material operated on. 3. Energy expended in the cracking and +heating of the material which is not displaced. 4. The escape of gas +through the blast-hole, and the fissures caused by the explosion. The +proportion of useful work has been estimated to be from 14 to 33 per cent. +of the theoretical maximum potential. + +[Footnote A: C.N. Hake, Government Inspector of Explosives, Victoria, +_Jour. Soc. Chem. Ind._, 1889.] + +For the purposes of comparison, manufacturers generally rely more upon the +practical than the theoretical efficiency of an explosive. These, however, +stand in the same relation to one another, as the following table of +Messrs Roux and Sarrau will show:-- + +MECHANICAL EQUIVALENT OF EXPLOSIVES. + + Theoretical Work Relative + in Kilos. Value. + +Blasting powder (62 per cent. KNO_{3}) 242,335 1.0 +Dynamite (75 per cent. nitro-glycerine) 548,250 2.26 +Blasting gelatine (92 per cent. nitro-glycerine) 766,813 3.16 +Nitro-glycerine 794,563 3.28 + +Experiments made in lead cylinders give-- + Dynamite 1.0 + Blasting gelatine 1.4 + Nitro-glycerine 1.4 + +Sir Frederick Abel and Captain W.H. Noble, R.A., have shown that the +maximum pressure exerted by gunpowder is equal to 486 foot-tons per lb. of +powder, or that when 1 kilo, of the powder gases occupy the volume of 1 +litre, the pressure is equal to 6,400 atmospheres; and Berthelot has +calculated that every gramme of nitro-glycerine exploded gives 1,320 units +of heat. MM. Roux and Sarrau, of the Depôt Centrales des Poudres, Paris, +by means of calorimetric determinations, have shown that the following +units of heat are produced by the detonation of-- + +Nitro-glycerine 1,784 heat units. +Gun-cotton 1,123 " +Potassic picrate 840 " + +which, multiplied by the mechanical equivalent per unit, gives-- + +Nitro-glycerine 778 metre tons per kilogramme. +Gun-cotton 489 " " +Picrate of potash 366 " " + +~Nobel's Ballistic Test.~--Alfred Nobel was the first to make use of the +mortar test to measure the (ballistic) power of explosives. The use of the +mortar for measuring the relative power of explosives does not give very +accurate results, but at the same time the information obtained is of +considerable value from a practical point of view. The mortar consists of +a solid cylinder of cast iron, one end of which has been bored to a depth +of 9 inches, the diameter of the bore being 4 inches. At the bottom of the +bore-hole is a steel disc 3 inches thick, in which another hole has been +bored 3 inches by 2 inches. The mortar (Fig. 54) itself is fitted with +trunnions, and firmly fixed in a very solid wooden carriage, which is +securely bolted down to the ground. The shot used should weigh 28 lbs., +and be turned accurately to fit the bore of the mortar. Down its centre is +a hole through which the fuse is put. + +The following is the method of making an experiment:--A piece of hard wood +is turned in the lathe to exactly fit the hole in the steel disc at the +bottom of the bore. This wooden cylinder itself contains a small cavity +into which the explosive is put. Ten grms. is a very convenient quantity. +Before placing in the mortar, a hole may be made in the explosive by means +of a piece of glass rod of such a size that the detonator to be used will +just fit into it. After placing the wooden cylinder containing the +explosive in the cavity at the bottom of the bore, the shot, slightly +oiled, is allowed to fall gently down on to it. A piece of fuse about a +foot long, and fitted with a detonator, is now pushed through the hole in +the centre of the shot until the detonator is embedded in the explosive. +The fuse is now lighted, and the distance to which the shot is thrown is +carefully measured. The range should be marked out with pegs into yards +and fractions of yards, especially at the end opposite to the mortar. The +mortar should be inclined at an angle of 45°. In experimenting with this +apparatus, the force and direction of the wind will be found to have +considerable influence. + +[Illustration: FIG. 54.--MORTAR FOR MEASURING THE BALLISTIC POWER OF +EXPLOSIVES. _A_, Shot; _B_, Steel Disc; _C_, Section of Mortar (Cast +Iron); _D_, Wooden Plug holding Explosive (_E_); _F_, Fuse.] + +Mr T. Johnson made some ballistic tests. He used a steel mortar and a shot +weighing 29 Ibs., and he adopted the plan of measuring the distance to +which a given charge, 5 grms., would throw the shot. He obtained the +following results:-- + + Range in Feet. + +Blasting gelatine (90 per cent. nitro-glycerine and nitro-cellulose) 392 +Ammonite (60 per cent. Am(NO_{3}) and 10 per cent. nitro-naphthalene) 310 +Gelignite (60 per cent. nitro-gelatine and gun-cotton) 306 +Roburite (AmNO_{3} and chloro-nitro-benzol) 294 +No. 1 dynamite (75 per cent. nitro-gelatine) 264 +Stonite (68 per cent. nitro-gelatine and 32 per cent. wood-meal) 253 +Gun-cotton 234 +Tonite (gun-cotton and nitrates) 223 +Carbonite (25 per cent. nitro-gelatine, 40 per cent. wood-meal, + and 30 per cent. nitrates) 198 +Securite (KNO_{3} and nitro-benzol) 183 +Gunpowder 143 + +~Calculation of the Volume of Gas Evolved in an Explosive Reaction.~--The +volume of gas evolved in an explosive reaction may be calculated, but only +when they are simple and stable products, such calculations being made at +0° and 760 mm. Let it be required, for example, to determine the volume of +gas evolved by 1 gram-molecule of nitro-glycerine. The explosive reaction +of nitro-glycerine may be represented by the equation. + +C_{3}H_{5}O_{3}(NO_{2})_{3} = 3CO_{2} + 2-1/2H_{2}O + 1-1/2N_{2} + 1/4O_{2} +By weight 227 = 132 + 45 + 42 + 8 +By volume 2 = 3 + 2-1/2 + 1-1/2 + 1/4 + +The weights of the several products of the above reactions are calculated +by multiplying their specific gravities by the weight of 1 litre of +hydrogen at 0° C. and 760 mm. (0.0896 grm). Thus, + +One litre of CO_{2} = 22 x .0896 = 1.9712 grm. + " H_{2}O = 9 x " = 0.8064 " + " N_{2} = 14 x " = 1.2544 " + " O_{2} = 16 x " = 1.4336 " + +The volume of permanent gases at 0° and 760 mm. is constant, and assuming +the gramme as the unit of mass, is found to be 22.32 litres. Thus:-- + +Volume of 44 of CO_{2}, at 0° and 760 mm. = 44/1.9712 = 22.32 litres. + 18 " H_{2}O " " = 18/0.8044 = 22.32 " + 28 " N_{2} " " = 28/1.2544 = 22.32 " + 32 " O_{2} " " = 32/1.4366 = 22.32 " + +Therefore + +132 grms. of CO_{2} at 0° C and 760 mm. = 22.32 x 3 = 66.96 litres. + 45 " H_{2}O " " = 22.32 x 2-1/2 = 55.80 " + 42 " N_{2} " " = 22.32 x 1-1/2 = 33.48 " + 8 " O_{2} " " = 22.32 x 1/4 = 5.58 " + ____________ + + 161.82 " +Therefore 1 gram-molecule or 227 grms. of nitro-glycerine when exploded, +produces 161.82 litres of gas at 0° C and 760 mm. + +To determine the volume of gas at the temperature of explosion, we simply +apply the law of Charles.[A] Thus-- + +V : V' :: T : T' or V' = VT'/T + +in which V represents the original volume. + V' " new volume. + T " original temperature on the absolute scale. + T' " new temperature of the same scale +In the present case T' = 6001°. + +Therefore substituting, we have + +V' = 161.82x6001/273 = 3557 litres + +or at the temperature of explosion 1 gram-molecule of nitro-glycerine +produces 3,557 litres of permanent gas. + +[Footnote A: According to the law of Charles, the volume of any gas varies +directly as its temperature on the absolute scale, provided the pressure +remains constant. Knowing the temperature on the centigrade scale, the +corresponding temperature on the absolute scale is obtained by adding 273 +to the degrees centigrade.] + +~Pressure or Crusher Gauge.~--There are many forms of this instrument. As +long ago as 1792 Count Rumford used a pressure gauge. The so-called +crusher gauge was, however, first used by Captain Sir Andrew Noble in his +researches on powder. Other forms are the Rodman[A] punch Uchatius +Eprouvette, and the crusher gauge of the English Commission on Explosives. +They are all based either upon the size of an indent made upon a copper +disc by a steel punch fitted to a piston, acted upon by the gases of the +explosive, or upon the crushing or flattening of copper or lead cylinders. + +[Footnote A: Invented by General Rodman, United States Engineers.] + +[Illustration: FIG. 55.--PRESSURE GAUGE.] + +Berthelot uses a cylinder of copper, as also did the English Commission, +but in the simpler form of apparatus mostly used by manufacturers lead +cylinders are used. This form of apparatus (Fig. 55) consists of a base of +iron to which four uprights _a_ are fixed, set round the circumference of +a 4-inch circle; the lead plug rests upon the steel base let into the +solid iron block. A ring _c_ holds the uprights _d_ together at the top. +The piston _b_, which rests upon the lead plug, is a cylinder of tempered +steel 4 inches in diameter and 5 inches in length; it is turned away at +the sides to lighten it as much as possible. It should move freely between +the uprights _d_. In the top of this cylinder is a cavity to hold the +charge of explosive. The weight of this piston is 12-1/4 lbs. The shot _e_ +is of tempered steel, and 4 inches in diameter and 10 inches in length, +and weighs 34-1/2 lbs. It is bored through its axis to receive a capped +fuse. + +The instrument is used in the following manner:--A plug of lead 1 inch +long and 1 inch in diameter, and of a cylindrical form, is placed upon the +steel plate between the uprights _a_, the piston placed upon it, the +carefully weighed explosive placed in the cavity, and the shot lowered +gently upon the piston. A piece of fuse, with a detonator fixed at one +end, is then pushed through the hole in the shot until it reaches the +explosive contained in the cavity in the piston. The fuse is lighted. When +the charge is exploded, the shot is thrown out, and the lead cylinder is +more or less compressed. The lead plugs must be of a uniform density and +homogeneous structure, and should be cut from lead rods that have been +drawn, and not cast separately from small masses of metal. + +[Illustration: FIG. 56.--_b_, STEEL PUNCH; _c_, LEAD CYLINDER FOR USE WITH +PRESSURE GAUGE.] + +The strength of the explosive is proportional to the work performed in +reducing the height of the lead (or copper) plug, and to get an expression +for the work done it is necessary to find the number of foot-pounds (or +kilogrammetres) required to produce the different amounts of compression. +This is done by submitting exactly similar cylinders of lead to a crushing +under weights acting without initial velocity, and measuring the reduced +heights of the cylinders; from these results a table is constructed +establishing empirical relations between the reduced heights and the +corresponding weights; the cylinders are measured both before and after +insertion in the pressure gauge by means of an instrument known as the +micrometer calipers (Fig. 57).[A] + +[Footnote A: An instrument called a "Foot-pounds Machine" has been +invented by Lieut. Quinan, U.S. Army. It consists of three boards, +connected so as to form a slide 16 feet high, in which a weight (the shot +of the pressure gauge) can fall freely. One of the boards is graduated +into feet and half feet. The horizontal board at the bottom, upon which +the others are nailed, rests upon a heavy post set deep in the ground, +upon which is placed the piston of the gauge, which in this case serves as +an anvil on which to place the lead cylinders. The shot is raised by means +of a pulley, fixed at the top of the structure, to any desired height, and +let go by releasing the clutch that holds it. The difference between the +original length and the reduced length gives the compression caused by the +blow of the shot in falling, and gives the value in foot-pounds required +to produce the different amounts of compression. (Vide _Jour. U.S. Naval +Inst._, 1892.)] + +[Illustration: FIG. 57.--MICROMETER CALIPERS FOR MEASURING DIAMETER OF +LEAD CYLINDERS.] + +~The Use of Lead Cylinders.~--The method of using lead cylinders to test +the strength of an explosive is a very simple affair, and is conducted as +follows:--A solid cast lead cylinder, of any convenient size, is bored +down the centre for some inches, generally until the bore-hole reaches to +about the centre of the block. The volume of this hole is then accurately +measured by pouring water into it from a graduated measure, and its +capacity in cubic centimetres noted. The bore-hole is then emptied and +dried, and a weighed quantity (say 10 grms.) of the explosive pressed well +down to the bottom of the hole. A hole is then made in the explosive (if +dynamite) with a piece of clean and rounded glass rod, large enough to +take the detonator. A piece of fuse, fitted with a detonator, is then +inserted into the explosive and lighted. After the explosion a large pear- +shaped cavity will be found to have been formed, the volume of which is +then measured in the same way as before. + +The results thus obtained are only relative, but are of considerable value +for comparing dynamites among themselves (or gun-cottons). Experiments in +lead cylinders gave the relative values for nitro-glycerine 1.4, blasting +gelatine 1.4, and dynamite 1.0. (Fig. 58 shows sections of lead cylinders +before and after use.) + +[Illustration: FIG. 58.--LEAD CYLINDERS BEFORE AND AFTER USE.] + +Standard regulations for the preparation of lead cylinders may be found in +the _Chem. Zeit._, 1903, 27 [74], 898. They were drawn up by the Fifth +International Congress of App. Chem., Berlin. The cylinder of lead should +be 200 mm. in height and 200 mm. in diameter. In its axis is a bore-hole, +125 mm. deep and 25 mm. in diameter. The lead used must be pure and soft, +and the cylinder used in a series of tests must be cast from the same +melt. The temperature of the cylinders should be 15° to 20° throughout. +Ten grms. of explosive should be used and wrapped in tin-foil. A detonator +with a charge of 2 grms., to be fired electrically, is placed in the midst +of the explosive. The cartridge is placed in the bore-hole, and gently +pressed against the bottom, the firing wires being kept in central +position. The bore-hole is then filled with dry quartz sand, which must +pass through a sieve of 144 meshes to the sq. cm., the wires being .35 mm. +diameter. The sand is filled in evenly, any excess being levelled off. The +charge thus prepared is then fired electrically. The lead cylinder is then +inverted, and any residues removed with a brush. The number of c.c. of +water required to fill the cavity, in excess of the original volume of the +bore-hole, is a measure of the strength of the explosive. The results are +only comparable if made with the same class of explosive. A result is to +be the mean of at least three experiments. The accuracy of the method +depends on (_a_) the uniform temperature of the lead cylinder (15° to 20° +C. 7); (_b_) on the uniformity of the quartz sand; (_c_) on the uniformity +of the measurements. + +[Illustration: FIG. 59.--NOBLE'S PRESSURE GAUGE.] + +~Noble's Pressure Gauge.~--The original explosive vessels used by Captain +Sir A. Noble in his first experiments were practically exactly similar to +those that he now employs, which consists of a steel barrel A (Fig. 59), +open at both ends, which are closed by carefully fitted screw plugs, +furnished with steel gas checks to prevent any escape past the screw. The +action of the gas checks is exactly the same as the leathers used in +hydraulic presses. The pressure of the gas acting on both sides of the +annular space presses these sides firmly against the cylinder and against +the plug, and so effectually prevents any escape. In the firing plug F is +a conical hole closed by a cone fitting with great exactness, which, when +the vessel is prepared for firing, is covered with fine tissue paper to +act as an insulator. The two firing wires GG, one in the insulated cone, +the other in the firing plug, are connected by a very fine platinum wire +passing through a glass tube filled with meal powder. The wire becomes +red-hot when connection is made with a Leclanché battery, and the charge +which has previously been inserted into the vessel is fired. The crusher +plug is fitted with a crusher gauge H for determining the pressure of the +gases at the moment of explosion, and in addition there is frequently a +second crusher gauge apparatus screwed into the cylinder. When it is +desired to allow the gases to escape for examination, the screw J is +slightly withdrawn. The gases then pass into the passage I, and can be led +to suitable apparatus in which their volume can be measured, or in which +they can be sealed for subsequent chemical analysis. + +The greatest care must be exercised in carrying out experiments with this +apparatus; it is particularly necessary to be sure that all the joints are +perfectly tight before exploding the charge. Should this not be the case, +the gases upon their generation will cut their way out, or completely blow +out the part improperly secured, in either case destroying the apparatus. +The effect produced upon the apparatus when the gas has escaped by cutting +a passage for itself is very curious. The surface of the metal where the +escape occurred presents the appearance of having been washed away in a +state of fusion by the rush of the highly heated products. + +~The Pressure Gauge.~--The pressure is found by the use of a little +instrument known as the pressure gauge which consists of a small chamber +formed of steel, inside of which is a copper cylinder, and the entrance +being closed by a screw gland, in which a piston, having a definite +sectional area, works. There is a gas check E (Fig. 60) placed in the +gland, and over the piston, which prevents the admission of gas to the +chamber. When it is desired to find the pressure in the chamber of a gun, +one or more of these crushers are made up with or inserted at the extreme +rear end of the cartridge, in order to avoid their being blown out of the +gun when fired. This, however, often takes place, in which case the gauges +are usually found a few yards in front of the muzzle. The copper cylinders +which register the pressure are made 0.5 inch long from specially selected +copper, the diameters being regulated to give a sectional area of either +1/12 or 1/24 square inch. + +[Illustration: FIG. 60.--CRUSHER GAUGE. _E_, GAS CHECK.] + +Hollow copper cylinders are manufactured with reduced sectional areas for +measuring very small pressures. It has been found that these copper +cylinders are compressed to definite lengths for certain pressures with +remarkable uniformity. Thus a copper cylinder having a sectional area of +1/12 square inch, and originally 1/2 inch long, is crushed to a length of +0.42 inch by a pressure of 10 tons per square inch. By subsequently +applying a pressure of 12 tons per square inch the cylinder is reduced to +a length of 0.393 inch. Before using the cylinders, whether for +experimenting with closed vessels or with guns, it is advisable to first +crush them by a pressure a little under that expected in the experiment. +Captain Sir A. Noble used in his experiments a modification of Rodman's +gauge. (Ordnance Dept., U.S.A., 1861.) + +~By Calculation.~--To calculate the pressure developed by the explosion of +dynamite in a bore-hole 3 centimetres in diameter, charged with 1 +kilogramme of 75 per cent. dynamite, Messrs Vieille and Sarrau employ the +following formula:-- + +P = V_{o}(1 + Q/273._c_)/(V - _v_). + +Where V_{o} = the volume (reduced to 0° and 760 mm.) of the gases produced +by a unit of weight of the explosive; Q the number of calories disengaged +by a unit of weight of the explosive; _c_ equals the specific heat at +constant volume of the gases; V the volume in cubic centimetres of a unit +of weight of the explosive; _v_ the volume occupied by the inert +materials of the explosive. The volume of gas produced by the explosion of +1 kilogramme of nitro-glycerine (at 0° and 760 mm.) is 467 litres. + +V_{o} will therefore equal 0.75 x 467 = 350.25. + +The specific heat _c_ is, according to Sarrau, .220 (_c_); and according +to Bunsen, 1 kilogramme of dynamite No. 1 disengages 1,290 (Q) calories. +The density of dynamite is equal to 1.5, therefore + +V = 1/1.5 = .666. + +If we take the volume of the kieselguhr as .1, we find from above formula +that + +P = 350(1 + 1290/(273 x .222))/(.600 - .1) = 13,900 atmospheres, + +which is equal to 14,317 kilogrammes per square centimetre. The pressure +developed by 1 kilogramme of pure nitro-glycerine equals 18,533 +atmospheres, equals 19,151 kilogrammes. Applying this formula to gun- +cotton, and taking after Berthelot, Q = 1075, and after Vieille and +Sarrau, V_{o} = 671 litres, and _c_ as .2314, and the density of the +nitro-cellulose as 1.5, we have (V = O) + +P = 671(1 + 1075/(273 x .2314))/.666 = 18,135 atmospheres. + +To convert this into pressure of kilogrammes per square centimetre, it is +necessary to multiply it by the weight of a column of mercury 0.760 m. +high, and 1 square centimetre in section, which is equal to increasing it +by 1/30. It thus becomes + +P^{k} = (1 + 1/30). + +P^{k} = 18,135 x 1.033 = 18,733 kilogrammes. + +The following tables, taken from Messrs William Macnab's and E. Ristori's +paper (_Proc. Roy. Soc._, 56, 8-19), "Researches on Modern Explosives," +are very interesting. They record the results of a large number of +experiments made to determine the amount of heat evolved, and the quantity +and composition of the gases produced when certain explosives and various +smokeless powders were fired in a closed vessel from which the air had +been previously exhausted. The explosions were carried out in a +"calorimetric bomb" of Berthelot's pattern.[A] + +[Footnote A: For description of "bomb," see "Explosives and their Power," +Berthelot, trans. by Hake and Macnab, p. 150. (Murray.)] + +Table Showing Quantity of Heat and Volume and Analysis of Gas Developed +per Gramme with Different Sporting and Military Smokeless Powders Now In +Use + +______________________________________________________________________ + | | | | | + Name of Explosive. | Calories | Permanent | Aqueous | Total Volume | + | per grm. | Gases. | Vapour. | of Gas at 0° | + | | | | and 760 mm. | +______________________|__________|___________|_________|______________| + | | cc/grm | cc/grm | cc/grm | + E.C. powder, English | 800 | 420 | 154 | 574 | + S.S. powder | 799 | 584 | 150 | 734 | + Troisdorf, German | 943 | 700 | 195 | 895 | + Rifleite, English | 864 | 766 | 159 | 925 | + B.N., French | 833 | 738 | 168 | 906 | + Cordite, English | 1253 | 647 | 235 | 882 | + Ballistite, German | 1291 | 591 | 231 | 822 | + Ballistite, Italian | 1317 | 58l | 245 | 826 | + and Spanish | | | | | +______________________|__________|___________|_________|______________| + +The figures in column headed "Co-efficient of Potential Energy" serve as a +measure of comparison of the power of the explosives, and are the products +of the number of calories by the volume of gas, the last three figures +being suppressed in order to simplify the results. + +The amounts of water found were calculated for comparison as volumes of +H_{2}O gas at 0° and 760 mm. + +E.C. powder consists principally of nitro-cellulose mixed with barium +nitrate and a small proportion of camphor. + +S.S. of nitro-lignine mixed with barium nitrate and nitro-benzene. + +Troisdorf powder is gelatinised nitro-cellulose; rifleite gelatinised +nitro-cellulose and nitro-benzene. + +Cordite contains 58 per cent. nitro-glycerine, 37 per cent. gun-cotton, +and 5 per cent. vaseline. + +Ballistite (Italian) consists of equal parts nitro-cellulose and nitro- +glycerine, and 1/2 per cent. of aniline. The German contains a higher +percentage of nitro-cellulose. + +TABLE SHOWING THE HEAT DEVELOPED BY EXPLOSIVES CONTAINING NITRO-GLYCERINE +AND NITRO-CELLULOSE IN DIFFERENT PROPORTIONS. + +______________________________________________________________________ + Composition of Explosives. | Calories per cent. +_____________________________________________|________________________ +Nitro-cellulose | | +(N = 13.3 per cent.). | Nitro-glycerine. | + | | +100 per cent. dry pulp | 0 | 1061 +100 " gelatinised | 0 | 922 + 90 " | 10 per cent. | 1044 + 80 " | 20 " | 1159 + 70 " | 30 " | 1267 + 60 " | 40 " | 1347 + 50 " | 50 " | 1410 + 40 " | 60 " | 1467 + 0 " | 100 " | 1652 +__________________________|__________________|________________________ + | | +Nitro-cellulose | | +(N=12.24 per cent.) | Nitro-glycerine. | + | | + 80 per cent. | 20 per cent. | 1062 + 60 " | 40 " | 1288 + 50 " | 50 " | 1349 + 40 " | 60 " | 1405 + | | +__________________________|__________________|________________________| +Nitro-cellulose | | +(N = 13.3 per cent.). | Nitro-glycerine. | Vaseline. + | | + 55 per cent. | 40 per cent. | 5 per cent. 1134 + 35 " | 60 " | 5 " 1280 +__________________________|__________________|________________________ + +TABLE OF RESULTS OBTAINED BY LIEUT. W. WALKE., OF THE ARTILLERY, U.S.A, +WITH QUINAN'S PRESSURE GAUGE. + +Nitro-glycerine being taken as 100. (From _U.S. Naval Inst. Jour._) + +__________________________________________________________________________ + | | | + | Compression | Order of | + Name of Explosive. | of Lead | Strength. | + | | | + | Inch. | | +Explosive gelatine | 0.585 | 106.17 | +Hellhoffite | 0.585 | 106.17 | +Nitro-glycerine | 0.551 | 100.00 | Standard, N.G. +Nobel's smokeless powder | 0.509 | 92.38 | +Nitro-glycerine | 0.509 | 92.37 | +Gun-cotton | 0.458 | 83.12 | U.S. naval torpedo + | | | gun-cotton +Gun-cotton | 0.458 | 83.12 | Stowmarket. +Nitro-glycerine | 0.451 | 81.85 | Vouges, N.G. +Gun-cotton | 0.448 | 81.31 | +Dynamite No. 1 | 0.448 | 81.31 | +Dynamite de Traul | 0.437 | 79.31 | +Emmensite | 0.429 | 77.86 | +Amide powder | 0.385 | 69.87 | +Oxonite | 0.383 | 69.51 | +Tonite | 0.376 | 68.24 | G.C. 52.5%, and + | | | Ba(NO_{3})_{2}, 47.5% +Bellite | 0.362 | 65.70 | +Rack-a-rock | 0.340 | 61.71 | +Atlas powder | 0.333 | 60.43 | +Ammonia dynamite | 0.332 | 60.25 | +Volney's powder No. 1 | 0.322 | 58.44 | Nitrated naphthalene. + " No. 2 | 0.294 | 53.18 | " " +Melinite | 0.280 | 50.82 | Picric acid 70%, and + | | | sol. nitro-cotton 30%. +Silver fulminate | 0.277 | 50.27 | +Mercury | 0.275 | 49.91 | +Mortar powder | 0.155 | 28.13 | +_________________________|_____________|___________|______________________ + +~Composition of some of the Explosives in Common Use.~ + +~Ordinary Dynamite.~ + +Nitro-Glycerine 75 per cent. +Kieselguhr 25 " + +~Amvis.~ + +Nitrate of Ammonia 90 per cent. +Chloro-di-nitro Benzene 5 " +Wood Pulp 5 " + +~Ammonia Nitrate Powder.~ + +Nitrate of Ammonia 80 per cent. +Chlorate of Potash 5 " +Nitro-Glucose 10 " +Coal Tar 5 " + +~Celtite.~ + +Nitro-Glycerine 56-59 parts. +Nitro-Cotton 2-3.5 " +KNO_{3} 17-21 " +Wood Meal 8-9 " +Ammonium Oxalate 11-13 " +Moisture 0.5-1.5 " + +~Atlas Powders.~ + +Sodium Nitrate 2.0 per cent. +Nitro-Glycerine 75.0 " +Wood Pulp 21.0 " +Magnesium Carbonate 2.0 " + +~Dauline.~ + +Nitro-Glycerine 50 per cent. +Sawdust 30 " +Nitrate of Potash 20 " + +~Vulcan Powder.~ + +Nitro-Glycerine 30 per cent. +Nitrate of Soda 52.5 " +Sulphur 7.0 " +Charcoal 10.5 " + +~Vigorite.~ + +Nitro-Glycerine 30 per cent. +Nitrate of Soda 60 " +Charcoal 5 " +Sawdust 5 " + +~Rendrock.~ + +Nitrate of Potash 40 per cent. +Nitro-Glycerine 40 " +Wood Pulp 13 " +Paraffin or Pitch 7 " + +~Ammonia Nitrate Powder.~ + +Ammonia Nitrate 80 per cent. +Potassium Chlorate 5 " +Nitro-Glucose 10 " +Coal Tar 5 " + +~Hercules Powders.~ + +Nitro-Glycerine 75 to 40 per cent. +Sugar 1 " 15.66 " +Chlorate of Potash 1.05 " 3.34 " +Nitrate of Potash 2.10 " 31.00 " +Carbonate of Magnesia 20.85 " 10.00 " + +~Carbo-Dynamite.~ + +Nitro-Glycerine 90 per cent. +Charcoal 10 " + +~Geloxite (Permitted List).~ + +Nitro-Glycerine 64-54 parts. +Nitro-Cotton 5-4 " +Nitrate of Potash 22-13 " +Ammonium Oxalate 15-12 " +Red Ochre 1-0 " +Wood Meal 7-4 " + +The Wood Meal to contain not more than 15% and not less than 5% moisture. + +~Giant Powder.~ + +Nitro-Glycerine 40 per cent. +Sodium Nitrate 40 " +Rosin 6 " +Sulphur 6 " +Guhr 8 " + +~Dynamite de Trauzel.~ + +Nitro-Glycerine 75 parts. +Gun-Cotton 25 " +Charcoal 2 " + +~Rhenish Dynamite.~ + +Solution of N.G. in Naphthalene 75 per cent. +Chalk, or Barium Sulphate 2 " +Kieselguhr 23 " + +~Ammonia Dynamite.~ + +Ammonia Nitrate 75 parts. +Paraffin 4 " +Charcoal 3 " +Nitro-Glycerine 18 " + +~Blasting Gelatine.~ + +Nitro-Glycerine 93 per cent. +Nitro-Cotton 3 to 7 " + +~Gelatine Dynamite.~ + +Nitro-Glycerine 71 per cent. +Nitro-Cotton 6 " +Wood Pulp 5 " +Potassium Nitrate 18 " + +~Gelignite.~ + +Nitro-Glycerine 60 to 61 per cent. +Nitro-Cotton 4 " 5 " +Wood Pulp 9 " 7 " +Potassium Nitrate 27 " + +~Forcite.~ + +Nitro-Glycerine 49 per cent. +Nitro-Cotton 1.0 " +Sulphur 1.5 " +Tar 10.0 " +Sodium Nitrate 38.0 " +Wood Pulp 5 " + (The N.-G., &c., varies.) + +~Tonite No. 1.~ + +Gun-Cotton 52-50 per cent. +Barium Nitrate 47-40 " + +~Tonite No. 2.~ + +Contains Charcoal also. + +~Tonite No. 3.~ + +Gun-Cotton 18 to 20 per cent. +Ba(NO_3)_2 70 " 67 " +Di-nitro-Benzol 11 " 13 " +Moisture 0.5 " 1 " + +~Carbonite.~ + +Nitro-Glycerine 17.76 per cent. +Nitro-Benzene 1.70 " +Soda 0.42 " +KNO_3 34.22 " +Ba(NO_3)_2 9.71 " +Cellulose 1.55 " +Cane Sugar 34.27 " +Moisture 0.36 " + ________ + + 99.99 + +~Roburite.~ + +Ammonium Nitrate 86 per cent. +Chloro-di-nitro-Benzol 14 " + +~Faversham Powder.~ + +Ammonium Nitrate 85 per cent. +Di-nitro-Benzol 10 " +Trench's Flame-extinguishing Compound 5 " + +~Favierite No. 1.~ + +Ammonium Nitrate 88 per cent. +Di-nitro-Naphthalene 12 " + +~Favierite No. 2.~ + +No. 1 Powder 90 per cent. +Ammon. Chloride 10 " + +~Bellite.~ + +Ammonium Nitrate 5 parts. +Meta-di-nitro-Benzol 1 " + +~Petrofacteur.~ + +Nitro-Benzene 10 per cent. +Chlorate of Potash 67 " +Nitrate of Potash 20 " +Sulphide of Antimony 3 " + +~Securite.~ + +Mixtures of Meta-di-nitro-Benzol 26 per cent. +and Nitrate of Ammonia 74 " + +~Rack-a-Rock.~ + +Potassium Chlorate 79 parts. +Mono-nitro-Benzene 21 " + +~Oxonite.~ + +Nitric Acid (sp. gr. 1.5) 54 parts. +Picric Acid 46 " + +~Emmensite.~ + +Emmens Acid 5 parts. +Ammonium Nitrate 5 " +Picric Acid 6 " + +~Brugère Powder.~ + +Ammonium Picrate 54 per cent. +Nitrate of Potash 46 " + +~Designolle's Torpedo Powders.~ + +Potassium Picrate 55 to 50 per cent. +Nitrate of Potash 45 " 50 " + +~Stowite.~ + +Nitro-Glycerine 58 to 61 parts. +Nitro-Cotton 4.5 " 5 " +Potassium Nitrate 18 " 20 " +Wood Meal 6 " 7 " +Oxalate of Ammonia 11 " 15 " + +The Wood Meal shall contain not more than 15% and not less than 5% by +weight of moisture. The explosive shall be used only when contained +in a non-water-proofed wrapper of parchment--No. 6 detonator. + +~Faversham Powder.~ + +Nitrate of Ammonium 93 to 87 +Tri-nitro-Toluol 11 " 9 +Moisture 1 " -- + +~Kynite.~ + +Nitro-Glycerine 24-26 parts. +Wood-Pulp 2.5-3.5 " +Starch 32.5-3.5 " +Barium Nitrate 31.5-34.5 " +CaCO_{3} 0-0.5 " +Moisture 3.0-6.0 " + +Must be put up only in water-proof parchment paper, and No. 6 electric +detonator used. + +~Rexite.~ + +Nitro-Glycerine 6.5-8.5 parts. +Ammonium Nitrate 64-68 " +Sodium Nitrate 13-16 " +Tri-nitro-Tolulene 6.5-8.5 " +Wood Meal 3-5 " +Moisture .5-1.4 " + +Must be contained in water-proof case (stout paper), water-proofed with +Resin and Cerasin--No. 6 detonator. + +~Withnell Powder.~ + +Ammonium Nitrate 88-92 parts. +Tri-nitro-Toluene 4-6 " +Flour (dried at 100° C.) 4-6 " +Moisture 0-15 " + +Only to be used when contained in a linen paper cartridge, water-proofed +with Carnuba Wax, Parrafin--No. 7 detonator used. + +~Phenix Powder.~ + +Nitro-Glycerine 28-31 parts. +Nitro-Cotton 0-1 " +Potassium Nitrate 30-34 " +Wood Meal 33-37 " +Moisture 2-6 " + +~SMOKELESS POWDERS.~ + +~Cordite.~ + +Nitro-Glycerine 58 per cent. +or- .75 +Nitro-Cotton 37 " +or- .65 +Vaseline 5 " +or- .25 + +~Cordite, M.D.~ + +Nitro-Glycerine 30 per cent. +or- 1 +Nitro-Cotton 65 " +or- 1 +Vaseline 5 " +or- .25 + +Analysis of-- + By W. Mancab and A.E. Leighton. + +~E.C. Powder.~ + +Nitro-Cotton 79.0 per cent. +Potassium Nitrate 4.5 " +Barium Nitrate 7.5 " +Camphor 4.1 " +Wood Meal 3.8 " +Volatile Matter 1.1 " + +~Walarode Powder.~ + +Nitro-Cotton 98.6 per cent. +Volatile Matter 1.4 " + +~Kynoch's Smokeless.~ + +Nitro-Cotton 52.1 per cent. +Di-nitro-Toluene 19.5 " +Potassium Nitrate 1.4 " +Barium Nitrate 22.2 " +Wood Meal 2.7 " +Ash 0.9 " +Volatile Matter 1.2 " + +~Schultze.~ + +Nitro-Lingin 62.1 per cent. +Potassium Nitrate 1.8 " +Barium Nitrate 26.1 " +Vaseline 4.9 " +Starch 3.5 " +Volatile Matter 1.0 " + +~Imperial Schultze.~ + +Nitro-Lignin 80.1 per cent. +Barium Nitrate 10.2 " +Vaseline 7.9 " +Volatile Matter 1.8 " + +~Cannonite.~ + +Nitro-Cotton 86.4 per cent. +Barium Nitrate 5.7 " +Vaseline 2.9 " +Lamp Black 1.3 " +Potassium Ferro-cyanide 2.4 " +Volatile Matter 1.3 " + +~Amberite.~ + +Nitro-Cotton 71.0 per cent. +Potassium Nitrate 1.3 " +Barium Nitrate 18.6 " +Wood Meal 1.4 " +Vaseline 5.8 " + +~Sporting Ballistite.~ + +Nitro-Glycerine 37.6 per cent +Nitro-Cotton 62.3 " +Volatile Matter 0.1 " + +The following is a complete List of the Permitted Explosives as Defined in +the Schedules to the Explosives in Coal Mines Orders of the 20th December +1902, of the 24th December 1903, of the 5th September 1903, and 10th +December 1903:-- + +Albionite. +Ammonal. +Ammonite. +Amvis. +Aphosite. +Arkite. +Bellite No. 1. +Bellite No. 2. +Bobbinite. +Britonite. +Cambrite. +Carbonite. +Clydite. +Coronite. +Dahmenite A. +Dragonite. +Electronite. +Faversham Powder. +Fracturite. +Geloxite. +Haylite No. 1. +Kynite. +Negro Powder. +Nobel's Ardeer Powder. +Nobel Carbonite. +Normanite. +Pit-ite. +Roburite No. 3. +Saxonite. +Stow-ite. +Thunderite. +Victorite. +Virite. +West Falite No. 1. +West Falite No. 2. + + + + +INDEX. + +Abel's, Sir Frederick, method of manufacturing gun-cotton, 57. + +Abel's heat test, 249. + +Acid mixture for nitrating nitro-glycerine, 23. + +Air pressure in nitrator, 28. + +Alkalinity in nitro-cellulose, 217. + +Amberite, 189. + +Ammonite, 149. + +Analyses of collodion-cotton, 81. + gelatine dynamites, 123. + +Analysis of explosives, 197. + acetone, 209. + blasting gelatine, 199. + cap composition, 241. + cordite, 206. + celluloid, 230. + dynamite, 197. + forcite, 202. + fulminate, 240. + glycerine, 233. + gun-cotton, 212. + nitric acid, 24. + picric acid, 230. + tonite, 205. + waste acids, 239. + +Armstrong on the constitution of the fulminates, 159. + +Atlas powder, 119. + +Auld on acetone, 211. + +Axite, 176. + + + +Ballistite, 179. + +Beater or Hollander for pulping gun-cotton, 64. + +Bedson, Prof., on roburite explosion gases, 140. + +Bellite, 142. + +Benzene, explosives derived from, 132. + +Benzene, mono-nitro- and di-nitro-benzene, 134. + +Bergmann and Junk on nitro-cellulose tests, 268. + +Bernthsen summary of nitro-benzenes, 133. + +Blasting gelatine, 119. + +Blasting charge, preparation of, 166. + +B.N. powder, 190. + +Boiling-point of N.G., 19. + +Boutnny's nitro-glycerine process, 15. + +Brown on wet gun-cotton, 56. + +Brugère's powder, 195. + +Bucknill's resistance coil, 13. + + + +Calculation of volume of gas evolved in an explosive reaction, 276. + +Cannonite, 189. + +Cellulose, 2, 47. + +Celluloid manufacture, 91. + analysis, 230. + cartridges, 91. + uses of, 90. + Field's papers on, 93. + fibre for, 94. + nitration of fibre, &c., 95. + formula of, 57. + +Champion and Pellet's method of determining nitrogen, 223. + +Chenel's modification of Kjeldahl's method, 227. + +Collodion-cotton, 79. + +Comparative tests of black and nitro-powders, 193. + +Compressing gun-cotton, 77. + +Composition of waste acids from nitro-glycerine, 43. + +Composition of some common explosives, 290. + +Conduits for nitro-glycerine, 7. + +Cooppal powder, 5, 189. + +Cordite manufacture, 169. + analysis, 206. + +Cresilite, 158. + +Cross and Bevan on nitro-jute, 107. + +Crusher gauge, 284. + +Cundill, Colonel, classification of dynamites, 112. + + + +Danger area, 5. + +Dangers in the manufacture of gun-cotton, 85. + +Decomposition of cellulose, 54. + +Definition of explosives in Order of Council (Explosives Act), 1. + +Determination of N_{2}O_{4} in nitric acid, 24. + +Determination of strength of H_{2}SO_{4}, 25. + +Determination of relative strength of explosives, 272. + +Detonators, 163. + +Di-nitro-toluene, 138. + +Dipping cotton in manufacture of gun-cotton, 60. + +Divers and Kawakita on the fulminates, 159. + +Dixon, Prof. H.B., on roburite explosions, 139. + +Drying house for gun-cotton, 122. + +Dynamite, efficiency of, 118. + frozen dynamite, 116. + gelatine dynamite, 119. + properties of kieselguhr dynamite, 116. + Reid & Borland's carbo-dynamite, 119. + Rhenish dynamite, 119. + various kinds of, 119. + + + +E.C. powder, 186. + +Electronite, 151. + +Emmensite, 195. + +Equation of formation of nitro-glycerine, 16. + +Equation of formation of nitro-cellulose, 50. + +Exploders, electric, 167. + +Explosion gases of dynamite, 19. + nitro-glycerine, 18. + gun-cotton, 55. + roburite, 139. + +Exudation test gelatines, 257. + + + +Faversham powder, 147. + +Favier's explosive, 149. + +Field on celluloid, 93, 99. + +Firing-point of explosives, 247. + +Filite, 180. + +Filtering nitre-glycerine, 37. + +Flameless explosives, 89, 138, 144. + +Formation of white matter in the nitration of N.G., 39. + +Forcite, 119. + +France, 82. + +Free fatty acid in glycerine, 39, 235. + +Freeing nitric acid from N_{2}O_{4}, 25. + +Freezing-point of N.G., 21. + +French Commission on Ammonium Nitrate, 142. + +Fulminates constitution, 159. + +Fulminate of mercury, 159, 240. + +Fulminate of silver, 161. + +Fuses, various kinds of, 166. + + + +Gases formed by the decomposition of nitro-glycerine, 18. + +Gelatine explosives, analysis of, 199. + +Glycerine, analysis of, 233. + formula of, 16. + nitration of, 23. + +Greiner's powder, 190. + +Gun-cotton, analysis of, 212. + boiling, 64. + complete series of, 52, 54. + compressing, moulding, and packing, 67, 77, 78. + dipping and steeping the cotton, 60. + drying the cotton, 58. + granulation of, 79. + manufacture of, 57. + Abel's method, 57. + Stowmarket, 57. + Waltham Abbey, 71. + products of decomposition of, 55. + properties of, 54. + pulping, 65. + washing, 63. + as a mining explosive, 56. + +Guttmann's nitric acid plant, 45. + +Guttmann's heat test, 256. + + + +Handy's method for determining moisture in dynamite, 197. + +Hannah, Dr N., on roburite explosion gases, 139. + +Heat developed by explosives containing nitro-glycerine, &c., 288. + +Heat test, Abel, 249. + +Hellhoffite, 152. + +Henrite powder, 191. + +Hollander, 65. + +Horsley's apparatus, 248. + +Hydro-extractors for wringing out gun-cotton, 62. + + + +Impurities in commercial glycerine, 39, 233. + +Impurities in fulminate, 240. + nitro-glycerine, 38. + picric acid, 231. + + + +Ketones as solvents for pyroxyline, 101. + +Kieselguhr dynamite, 112. + +Kinetite, 145. + +Kjeldahl method of determining nitrogen, 227. + + + +Le Bouchet, manufacture of gun-cotton at, 78. + +Lead cylinders for testing strength of explosives, 281. + +Lenk's improvements in gun-cotton manufacture, 49. + +Lewes on the pressure of cordite, 175. + +Leibert's treatment of nitro-glycerine, 30. + +Lightning conductors for danger buildings, 10. + +Liquefaction test for gelatine, 257. + +Lodge on lightning conductors, 8. + +Lowering of freezing-point of N.G., 21. + +Lungé's nitrometer, 219. + +Lydite, 156. + + + +Manufacture of gun-cotton, 57. + +Manufacture of nitro-glycerine, 17. + cordite, 169. + roburite, 140. + fulminates, 162. + tonite, 84. + di-nitro-benzene, 138. + nitro-starch, 103. + celluloid, 91. + +Majendie (Col. Sir V.D.), report on a picric acid explosion, 155. + +Maximite, 191. + +Maxim's detonator mixture, 165. + +M'Robert's mixing machine, 126. + +Mechanical equivalent of explosives, 273. + +Melinite, 156. + +Mono-nitro-glycerine, di-nitro-nitro-glycerine, 41. + +Moulding gun-cotton, 77. + +Mounds for protection of danger buildings, 6. + +Mortar for ballistic tests, 275. + +Mowbray on use of compressed air, 15. + +Mühlhäusen on nitro-starch, 4, 5, 103. + + + +Nathan's nitrator, 32. + +Nitric peroxide in N.G., 24. + +Nitration products of cellulose, 52, 54. + +Nitro-glycerine, analysis of, 198. + properties, 17. + nitration, 23. + separation, 35. + washing, 37. + uses of, 41. + manufacture of, 17. + +Nitro-benzene, properties and manufacture of, 132, 137. + +Nitro-cellulose, 2, 47, 60, 212. + +Nitro-jute, 5, 107. + +Nitro-mannite, 4, 109. + +Nitro-naphthalene, 148. + +Nitro-starch, 4, 103. + +Nitro-toluene, 132. + +Nitrated gun-cotton, 83. + +Nitrogen, determination of, Lungé method, 219. + Champion and Pellet's, 223. + Schultze-Tieman, 224. + Kjeldahl-Chenel's, 227. + percentages of in various explosives, 228. + +Nitrometers, Lungé, Horn's, &c., 220, 222. + +Nobel's ballistic test, 274. + +Noble's pressure gauge, 282. + experiments on cordite, 172. + +Normal powder, 191. + + + +Oleic acid in glycerine, 236. + +Orsman on roburite, 142. + +Oxonite, 152. + +Oxy-cellulose, 102. + + + +Packing gun-cotton, 78. + dynamite, 116. + +Page's regulator, 260. + +Panclastite, 152. + +Percentage composition of nitro-glycerine, 18. + +Perkin on magnetic rotation of nitro-glycerine, 19. + +Phenol, tri-nitro-phenol, 152. + +Picric acid, 152, 231. + powders, 157, 189. + +Picrates, 154, 231. + +Polarised light and nitro-cellulose, 218. + +Position of the NO_{2} group in nitro-explosives, 2, 3, 16. + +Prentice's nitric acid plant, 43. + +Pressure gauge, 282. + +Primers of gun-cotton, 166. + +Properties of dynamite, 116. + gelatine compounds, 130. + +Pulping gun-cotton, 65. + +Pyroxyline for celluloid, 96. + solvents for, 101. + + + +Quinan's foot-pound machine, 280. + + + +Raoult's law and N.G., 21. + +Reworked gun-cotton, 78. + +Rhenish dynamite, 119. + +Roburite, properties and manufacture of, 138. + Bedson's report on, 140. + Orsman on gases produced by explosion of, 142. + +Romit, 148. + + + +Sarrau and Vieille, gases obtained from ignition of dynamite, 19. + +Sayers, 50. + +Scheme for analysis of explosives, 213. + +Schultze's powder, 183. + +Schultze-Tieman method of determining nitrogen, 224. + +Securite, 144. + +Separation of nitro-glycerine from mixed acids, 35. + +Shimose, 156. + +Silver test for glycerine, 233. + +Smokeless powders, 168. + +Smokeless diamond, 190. + +Snyder's powder, 193. + +Sobrero discovered nitro-glycerine, 14. + +Sodium nitrate, analysis of, 239. + +Soluble and insoluble nitro-cellulose, 51. + +Solubility of nitro-glycerine, 20. + +Solvents for soluble gun-cotton, 52, 101. + +Solubility test for gun-cotton, 214. + +Specific gravity of explosives, 270. + +Sprengel's explosives, 151. + +Stowmarket, manufacture of gun-cotton at, 57. + +Sulphuric acid, determination of strength of, 24. + +Sy on test for nitro-cellulose, 269. + + + +Temperature of nitration of nitro-glycerine, 29. + +Thomson's patents, 73. + +Toluene, 146. + +Tonite, 84, 146. + analysis of, 205. + fumes from, 85. + +Treatment of waste acids, 43. + +Trench's fire-extinguishing compound, 88. + +Trebouillet and De Besancele on celluloid manufacture, 92. + +Tri-nitro-cresol, 158. + +Tri-nitro-toluene, 146. + +Tri-nitro-phenol, 152. + +Tri-nitro-glycerine, 2, 14. + +Troisdorf powder, 191, 192. + +Turpin's melinite, 156. + + + +U.S. naval powder, 180. + +Uses of celluloid, 91, 93, 102. + +Uses of collodion-cotton, 90. + + + +Vaseline, 208. + +Vielle poudre, 190. + +Volney's powder, 148. + +Von Foster's powder, 191. + + + +Walsrode powder, 188. + +W.A. powder, 182. + +Waltham Abbey, manufacture of gun-cotton at, 71. + manufacture of cordite at, 169. + +Walke's pressure gauge results, 289. + +War Office experiments with cordite, 173. + +Washing gun-cotton, 63. + nitro-glycerine, 37. + +Waste acids from nitro-glycerine, 41, 226. + +Weltern powder, 191. + +Werner & Pfleiderer's mixing machine, 124. + +Whirling out the acids from gun-cotton, 62. + +Will's test for nitre-cellulose, 261. + +Wood pulp, 126. + + + +Xylonite Company's process, 96. + + + +Zenger's lightning conductors, 11. + + + +_Printed at_ THE DARLEN PRESS, _Edinburgh_. + + + + + +End of the Project Gutenberg EBook of Nitro-Explosives: A Practical Treatise +by P. 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Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + +Most people start at our Web site which has the main PG search facility: + + https://www.gutenberg.org + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. + +*** END: FULL LICENSE *** + diff --git a/15308-8.zip b/15308-8.zip Binary files differnew file mode 100644 index 0000000..74352fc --- /dev/null +++ b/15308-8.zip diff --git a/15308.txt b/15308.txt new file mode 100644 index 0000000..0205038 --- /dev/null +++ b/15308.txt @@ -0,0 +1,10955 @@ +The Project Gutenberg EBook of Nitro-Explosives: A Practical Treatise +by P. Gerald Sanford + +This eBook is for the use of anyone anywhere 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 + + +Title: Nitro-Explosives: A Practical Treatise + +Author: P. Gerald Sanford + +Release Date: March 10, 2005 [EBook #15308] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK NITRO-EXPLOSIVES *** + + + + +Produced by Case Western Reserve University Preservation +Department, Curtis Weyant, and the Online Distributed +Proofreading Team + + + + + +NITRO-EXPLOSIVES + +[Illustration: DANGER BUILDING SHOWING PROTECTING MOUNDS. (_See page 6._)] + +NITRO-EXPLOSIVES + +A PRACTICAL TREATISE + +CONCERNING THE + +_PROPERTIES, MANUFACTURE, AND ANALYSIS OF NITRATED SUBSTANCES, INCLUDING +THE FULMINATES, SMOKELESS POWDERS, AND CELLULOID_ + +BY + +P. GERALD SANFORD, F.I.C., F.C.S. + +_Public Analyst to the Borough of Penzance; late Consulting Chemist to the +Cotton Powder Company Limited; and formerly Resident Chemist at the +Stowmarket Works of the New Explosives Company Limited, and the Hayle +Works of the National Explosive Company Limited_ + +~Second Edition, Revised and Enlarged~ + + +PREFACE. + + +In compiling the following treatise, my aim has been to give a brief but +thoroughly practical account of the properties, manufacture, and methods +of analysis of the various nitro-explosives now so largely used for mining +and blasting purposes and as propulsive agents; and it is believed that +the account given of the manufacture of nitro-glycerine and of the +gelatine dynamites will be found more complete than in any similar work +yet published in this country. + +For many of the facts and figures contained in the chapter on Smokeless +Powders I am indebted to (amongst others) the late Mr J.D. Dougall and +Messrs A.C. Ponsonby and H.M. Chapman, F.C.S.; and for details with regard +to Roburite to Messrs H.A. Krohn and W.J. Orsman, F.I.C. To these +gentlemen my cordial thanks are due. Among the authorities which have been +consulted in the general preparation of the work may be mentioned the +_Journals_ of the Chemical Society, the Society of Chemical Industry, the +United States Naval Institute, and the Royal Artillery Institution. I have +also referred to several volumes of the periodical publication _Arms and +Explosives;_ to various papers by Sir Frederick Abel, Bart., F.R.S., and +General Wardell, R.A., on Gun-Cotton; to "Modern Artillery," by Capt. +Lloyd, R.N., and A.G. Hadcock, R.A.; to the late Colonel Cundill's +"Dictionary of Explosives"; as well as to the works of Messrs Eissler, +Berthelot, and others. + +The illustrations have been prepared chiefly from my own drawings. A few, +however, have been taken (by permission) from the pages of _Arms and +Explosives_, or from other sources which are acknowledged in the text. + +P.G.S. + +THE LABORATORY, + +20 CULLUM STREET, E.C. + +_May 1896._ + + + +PREFACE TO THE SECOND EDITION. + + +In the preparation of the Second Edition of this work, I have chiefly made +use of the current technical journals, especially of the _Journal of the +Society of Chemical Industry_. The source of my information has in every +case been acknowledged. + +I am also indebted to several manufacturers of explosives for information +respecting their special products--among others the New Explosives Company +Ltd.; Messrs Curtis's and Harvey Ltd.; The Schultze Gunpowder Company +Ltd.; and Mr W.D. Borland, F.I.C., of the E.C. Powder Company Ltd. + +To my friend Mr A. Stanley Fox, F.C.S., of Faversham, my best thanks are +also due for his help in many departments, and his kindness in pointing +out several references. + +The chapter on Smokeless Powders has been considerably enlarged and (as +far as possible) brought up to date; but it has not always been possible +to give the process of manufacture or even the composition, as these +details have not, in several cases, been made public. + +P. GERALD SANFORD. + +LONDON, _June 1906._ + + + + +TABLE OF CONTENTS. + +CHAPTER I.--INTRODUCTION. + +The Nitro-Explosives--Substances that have been Nitrated--The Danger Area-- +Systems of Professors Lodge, Zenger, and Melsens for the Protection of +Buildings from Lightning, &c. + +CHAPTER II.--NITRO-GLYCERINE. + +Properties of Nitro-Glycerine--Manufacture--Nitration--Separation--Washing +and Filtering--Drying, Storing, &c.--The Waste Acids--Their Treatment-- +Nitric Acid Plants + +CHAPTER III.--NITRO-CELLULOSE, &C. + +Cellulose Properties--Discovery of Gun-Cotton--Properties of Gun-Cotton-- +Varieties of Soluble and Insoluble Gun-Cottons--Manufacture of Gun-Cotton-- +Dipping and Steeping--Whirling Out the Acid--Washing, Boiling, Pulping, +Compressing--The Waltham Abbey Process--Le Bouchet Process--Granulation of +Gun-Cotton--Collodion-Cotton--Manufacture--Acid Mixture Used--Cotton Used, +&c.--Nitrated Gun-Cotton--Tonite--Dangers in Manufacture of Gun-Cotton-- +Trench's Fire-Extinguishing Compound--Uses of Collodion-Cotton--Celluloid-- +Manufacture, &c.--Nitro-Starch, Nitro-Jute, and Nitro-Mannite + +CHAPTER IV.--DYNAMITE. + +Kieselguhr Dynamite--Classification of Dynamites--Properties and +Efficiency of Ordinary Dynamite--Other forms of Dynamite--Gelatine and +Gelatine Dynamites, Suitable Gun-Cotton for, and Treatment of--Other +Materials Used--Composition of Gelignite--Blasting Gelatine--Gelatine +Dynamite--Absorbing Materials--Wood Pulp--Potassium Nitrate, &c.-- +Manufacture, &c.--Apparatus Used--The Properties of the Gelatine Compounds + +CHAPTER V.--NITRO-BENZOL, ROBURITE, BELLITE, PICRIC ACID, &c. + +Explosives derived from Benzene--Toluene and Nitro-Benzene--Di- and +Tri-nitro-Benzene--Roburite: Properties and Manufacture--Bellite: +Properties, &c.--Securite--Tonite No. 3.--Nitro-Toluene-- +Nitro-Naphthalene--Ammonite--Sprengel's Explosives--Picric Acid-- +Picrates--Picric Powders--Melinite--Abel's Mixture--Brugere's Powders-- +The Fulminates--Composition, Formula, Preparation, Danger of, &c.-- +Detonators: Sizes, Composition, Manufacture--Fuses, &c. + +THE FULMINATES. + +Composition, Formula, Preparation, Danger of, &c.--Detonators: Sizes, +Composition, Manufacture--Fuses, &c. + +CHAPTER VI.--SMOKELESS POWDERS IN GENERAL. + +Cordite--Axite--Ballistite--U.S. Naval Powder--Schultze's E.C. Powder-- +Indurite--Vielle Poudre--Walsrode and Cooppal Powders--Amberite-- +Troisdorf--B.N. Powder--Wetterin--Normal Powder--Maximite--Picric Acid +Powders, &c. &c. + +CHAPTER VII.--ANALYSIS OF EXPLOSIVES. + +Kieselguhr Dynamite--Gelatine Compounds--Tonite--Cordite--Vaseline-- +Acetone--Scheme for Analysis of Explosives--Nitro-Cotton--Solubility Test-- +Non-Nitrated Cotton--Alkalinity--Ash and Inorganic Matter--Determination +of Nitrogen--Lunge, Champion and Pellet's, Schultze-Tieman, and Kjeldahl's +Methods--Celluloid--Picric Acid and Picrates--Resinous and Tarry Matters-- +Sulphuric Acid and Hydrochloric Acid and Oxalic Acid--Nitric Acid-- +Inorganic Impurities--General Impurities and Adulterations--Potassium +Picrate, &c.--Picrates of the Alkaloids--Analysis of Glycerine--Residue-- +Silver Test--Nitration--Total Acid Equivalent--Neutrality--Free Fatty +Acids--Combined Fatty Acids--Impurities--Oleic Acid--Sodium Chloride-- +Determination of Glycerine--Waste Acids--Sodium Nitrate--Mercury +Fulminate--Cap Composition--Table for Correction of Volumes of Gases, for +Temperature and Pressure + +CHAPTER VIII.--FIRING POINT OF EXPLOSIVES, HEAT TESTS, &C. + +Horsley's Apparatus--Table of Firing Points--The Government Heat Test +Apparatus, &c., for Dynamites, Nitro-Glycerine, Nitro-Cotton, and +Smokeless Powders--Guttmann's Heat Test--Liquefaction and Exudation Tests-- +Page's Regulator for Heat Test Apparatus--Specific Gravities of +Explosives--Will's Test for Nitro-Cellulose--Table of Temperature of +Detonation, Sensitiveness, &c. + +CHAPTER IX.--THE DETERMINATION OF THE RELATIVE STRENGTH OF EXPLOSIVES. + +Effectiveness of an Explosive--High and Low Explosives--Theoretical +Efficiency--M.M. Roux and Sarrau's Results--Abel and Noble's--Nobel's +Ballistic Test--The Mortar--Pressure or Crusher Gauge--Calculation Volume +of Gas Evolved, &c.--Lead Cylinders--The Foot-Pounds Machine--Noble's +Pressure Gauge--Lieut. Walke's Results--Calculation of Pressure Developed +by Dynamite and Gun-Cotton--McNab's and Ristori's Results of Heat +Developed by the Explosion of Various Explosives--Composition of some of +the Explosives in Common Use for Blasting, &c. + +INDEX + + + +LIST OF ILLUSTRATIONS. + +FRONTISPIECE--Danger Building showing Protecting Mounds. + 1. Section of Nitro-Glycerine Conduit + 2. Melsens System of Lightning Conductors + 3. French System + 4_a_ & 4_b_. English Government System + 5. Upper Portion of Nitrator for Nitro-Glycerine + 6. Small Nitrator + 7. Nathan's Nitrator + 8. Nitro-Glycerine Separator + 9. Nitro-Glycerine Filtering Apparatus +10. Cotton-Waste Drier +11. Dipping Tank +12. Cooling Pits +13. Steeping Pot for Gun-Cotton +14. Hydro-Extractor or Centrifugal Drier +15_a_ & 15_b_. Gun-Cotton Beater +16_a_. Poacher for Pulping Gun-Cotton +16_b_. Plan of same +16_c_. Another form of Poacher +17 & 18. Compressed Gun-Cotton +19. Hydraulic Press +20. Thomson's Apparatus--Elevation +21. Elevation Plan +22. Trench's Safety Cartridge +23. Vessel used in Nitrating Paper +24. Cage ditto--White & Schupphaus' Apparatus +25. Do. do. do. +26 & 27. Nitrating Pot for Celluloid +28 & 29. Plunge Tank in Plan and Section +30. Messrs Werner, Pfleiderer & Perkins' Mixing Machine +31. M. 'Roberts' Mixing Machine for Blasting Gelatine +32. Plan of same +33. Cartridge Machine for Gelatines +34. Cartridge fitted with Fuse and Detonator +35. Gun-Cotton Primer +36. Electric Firing Apparatus +37. Metal Drum for Winding Cordite +38. Ten-Stranding +39. Curve showing relation between Pressures of Cordite and Black Powder, + by Professor Vivian Lewes +40. Marshall's Apparatus for Moisture in Cordite +41. Lunge's Nitrometer +42. Modified do. +43. Horn's Nitrometer +44. Schultze-Tieman Apparatus for Determination of Nitrogen in Gun-Cotton +45. Decomposition Flask for Schultze-Tieman Method +46. Abel's Heat Test Apparatus +47. Apparatus for Separation of Nitro-Glycerine from Dynamite +48. Test Tube arranged for Heat Test +49. Page's Regulator +50. Do. showing Bye-Pass and Cut-off Arrangement +51. Will's Apparatus +52 & 53. Curves obtained +54. Dynamite Mortar +55. Quinan's Pressure Gauge +56. Steel Punch and Lead Cylinder for Use with Pressure Gauge +57. Micrometer Calipers for Measuring Thickness of Lead Cylinders +58. Section of Lead Cylinders before and after Explosion +59. Noble's Pressure Gauge +60. Crusher Gauge + + + + +NITRO-EXPLOSIVES. + + +CHAPTER I. + +_INTRODUCTORY._ + +The Nitro-Explosives--Substances that have been Nitrated--The Danger Area-- +Systems of Professors Lodge, Zenger, and Melsens for the Protection of +Buildings from Lightning, &c. + + +The manufacture of the various nitro-explosives has made great advances +during late years, and the various forms of nitro-compounds are gradually +replacing the older forms of explosives, both for blasting purposes and +also for propulsive agents, under the form of smokeless powders. The +nitro-explosives belong to the so-called High Explosives, and may be +defined as any chemical compound possessed of explosive properties, or +capable of combining with metals to form an explosive compound, which is +produced by the chemical action of nitric acid, either alone or mixed with +sulphuric acid, upon any carbonaceous substance, whether such compound is +mechanically mixed with other substances or not.[A] + +[Footnote A: Definition given in Order of Council, No. 1, Explosives Act, +1875.] + +The number of compounds and mixtures included under this definition is +very large, and they are of very different chemical composition. Among the +substances that have been nitrated are:--Cellulose, under various forms, +e.g., cotton, lignin, &c.; glycerine, benzene, starch, jute, sugar, +phenol, wood, straw, and even such substances as treacle and horse-dung. +Some of these are not made upon the large scale, others are but little +used. Those of most importance are nitro-glycerine and nitro-cellulose. +The former enters into the composition of all dynamites, and several +smokeless powders; and the second includes gun-cotton, collodion-cotton, +nitrated wood, and the majority of the smokeless powders, which consist +generally of nitro-cotton, nitro-lignin, nitro-jute, &c. &c., together +with metallic nitrates, or nitro-glycerine. + +The nitro-explosives consist generally of some organic substance in which +the NO_{2} group, known as nitryl, has been substituted in place of +hydrogen. + +Thus in glycerine, + + |OH +C_{3}H_{5}|OH, + |OH + +which is a tri-hydric alcohol, and which occurs very widely distributed as +the alcoholic or basic constituent of fats, the hydrogen atoms are +replaced by the NO_{2} group, to form the highly explosive compound, +nitro-glycerine. If one atom only is thus displaced, the mono-nitrate is +formed thus, + + |ONO_{2} +C_{3}H_{5}|OH; + |OH + +and if the three atoms are displaced, C_{3}H_{5}(ONO_{2})_{3}, or the tri- +nitrate, is formed, which is commercial nitro-glycerine. + +Another class, the nitro-celluloses, are formed from cellulose, +C_{6}H_{10}O_{5}, which forms the groundwork of all vegetable tissues. +Cellulose has some of the properties of the alcohols, and forms ethereal +salts when treated with nitric and sulphuric acids. The hexa-nitrate, or +gun-cotton, has the formula, C_{12}H_{14}O_{4}(ONO_{2})_{6}; and +collodion-cotton, pyroxylin, &c., form the lower nitrates, i.e., the +tetra- and penta-nitrates. These last are soluble in various solvents, +such as ether-alcohol and nitro-glycerine, in which the hexa-nitrate is +insoluble. They all dissolve, however, in acetone and acetic ether. + +The solution of the soluble varieties in ether-alcohol is known as +collodion, which finds many applications in the arts. The hydrocarbon +benzene, C_{6}H_{6}, prepared from the light oil obtained from coal-tar, +when nitrated forms nitro-benzenes, such as mono-nitro-benzene, +C_{6}H_{5}NO_{2}, and di-nitro-benzene, C_{6}H_{4}(NO_{2})_{2}, in which +one and two atoms are replaced by the NO_{2} group. The latter of these +compounds is used as an explosive, and enters into the composition of such +well-known explosives as roburite, &c. The presence of nitro groups in a +substance increases the difficulty of further nitration, and in any case +not more than three nitro groups can be introduced into an aromatic +compound, or the phenols. All aromatic compounds with the general formula, +C_{6}H_{4}X_{2}, give, however, three series. They are called ortho, meta, +or para compounds, depending upon the position of NO_{2} groups +introduced. + +Certain regularities have been observed in the formation of nitro- +compounds. If, for example, a substance contains alkyl or hydroxyl groups, +large quantities of the para compound are obtained, and very little of the +ortho. The substitution takes place, however, almost entirely in the meta +position, if a nitro, carboxyl, or aldehyde group be present. Ordinary +phenol, C_{6}H_{5}.OH, gives para- and ortho-nitro-phenol; toluene gives +para- and ortho-nitro-toluene; but nitro-benzene forms meta-di-nitro- +benzene and benzoic acid, meta-nitro-benzoic acid.[A] + +[Footnote A: "Organic Chemistry," Prof. Hjelt. Translated by J.B. Tingle, +Ph.D.] + +If the graphic formula of benzene be represented thus (No. 1), then the +positions 1 and 2 represent the ortho, 1 and 3 the meta, and 1 and 4 the +para compounds. When the body phenol, C_{6}H_{5}.OH, is nitrated, a +compound is formed known as tri-nitro-phenol, or picric acid, +C_{6}H_{2}(NO_{2})_{3}OH, which is used very extensively as an explosive, +both as picric acid and in the form of picrates. Another nitro body that +is used as an explosive is nitro-naphthalene, C_{10}H_{6}(NO_{2})_{2}, in +roburite, securite, and other explosives of this class. The hexa-nitro- +mannite, C_{6}H_{8}(ONO_{2})_{6}, is formed + +[Illustration: No. 1] + +[Illustration: META-DINITRO-BENZENE No.2] + +by treating a substance known as mannite, C_{6}H_{8}(OH)_{6}, an alcohol +formed by the lactic acid fermentation of sugar and closely related to the +sugars, with nitric and sulphuric acids. It is a solid substance, and very +explosive; it contains 18.58 per cent. of nitrogen. + +Nitro-starch has also been used for the manufacture of an explosive. +Muhlhauer has described (_Ding. Poly. Jour._, 73, 137-143) three nitric +ethers of starch, the tetra-nitro-starch, C_{12}H_{16}O_{6}(ONO_{2})_{4}, +the penta- and hexa-nitro-starch. They are formed by acting upon potato +starch dried at 100 deg. C. with a mixture of nitric and sulphuric acids at a +temperature of 20 deg. to 25 deg. C. Rice starch has also been used in its +production. Muhlhauer proposes to use this body as a smokeless powder, and +to nitrate it with the spent mixed acids from the manufacture of nitro- +glycerine. This substance contains from 10.96 to 11.09 per cent. of +nitrogen. It is a white substance, very stable and soluble even in cold +nitro-glycerine. + +The explosive bodies formed by the nitration of jute have been studied by +Messrs Cross and Bevan. and also by Muehlhaeuer. The former chemists give +jute the formula C_{12}H_{18}O_{9}, and believe that its conversion into a +nitro-compound takes place according to the equation-- + +C_{12}H_{18}O_{9} + 3HNO_{3} = 3H_{2}O + C_{12}H_{15}O_(6}(NO_{3})_{3}. + +This is equivalent to a gain in weight of 44 per cent. for the tri- +nitrate, and 58 per cent. for the tetra-nitrate. The formation of the +tetra-nitrate appears to be the limit of nitration of jute fibre. Messrs +Cross and Bevan say, "In other words, if we represent the ligno-cellulose +molecule by a C_{12} formula, it will contain four hydroxyl (OH) groups, +or two less than cellulose similarly represented." It contains 11.5 per +cent. of nitrogen. The jute nitrates resemble those of cellulose, and are +in all essential points nitrates of ligno-cellulose. + +Nitro-jute is used in the composition of the well-known Cooppal Smokeless +Powders. Cross and Bevan are of opinion that there is no very obvious +advantage in the use of lignified textile fibres as raw materials for +explosive nitrates, seeing that a number of raw materials containing +cellulose (chiefly as cotton) can be obtained at from L10 to L25 a ton, +and yield also 150 to 170 per cent. of explosive material when nitrated +(whereas jute only gives 154.4 per cent.), and are in many ways superior +to the products obtained from jute. Nitro-lignin, or nitrated wood, is, +however, largely used in the composition of a good many of the smokeless +powders, such as Schultze's, the Smokeless Powder Co.'s products, and +others. + +~The Danger Area.~--That portion of the works that is devoted to the +actual manufacture or mixing of explosive material is generally designated +by the term "danger area," and the buildings erected upon it are spoken of +as "danger buildings." The best material of which to construct these +buildings is of wood, as in the event of an explosion they will offer less +resistance, and will cause much less danger than brick or stone buildings. +When an explosion of nitro-glycerine or dynamite occurs in one of these +buildings, the sides are generally blown out, and the roof is raised some +considerable height, and finally descends upon the blown-out sides. If, on +the other hand, the same explosion had occurred in a strong brick or stone +building, the walls of which would offer a much larger resistance, large +pieces of brickwork would probably have been thrown for a considerable +distance, and have caused serious damage to surrounding buildings. + +It is also a very good plan to surround all danger buildings with mounds +of sand or earth, which should be covered with turf, and of such a height +as to be above the roof of the buildings that they are intended to protect +(see frontispiece).[A] These mounds are of great value in confining the +force of the explosion, and the sides of the buildings being thrown +against them are prevented from travelling any distance. In gunpowder +works it is not unusual to surround the danger buildings with trees or +dense underwood instead of mounds. This would be of no use in checking the +force of explosion of the high explosives, but has been found a very +useful precaution in the case of gunpowder. + +[Footnote A: At the Baelen Factory, Belgium, the danger buildings are +erected on a novel plan. They are circular in ground plan and lighted +entirely from the roof by means of a patent glass having wire-netting in +it, and which it is claimed will not let a splinter fall, even if badly +cracked. The mounds are then erected right up against the walls of the +building, exceeding them in height by several metres. For this method of +construction it is claimed that the force exerted by an explosion will +expand itself in a vertical direction ("Report on Visits to Certain +Explosive Factories," H.M. Inspectors, 1905).] + +In Great Britain it is necessary that all danger buildings should be a +specified distance apart; a license also must be obtained. The application +for a license must give a plan (drawn to scale) of the proposed factory or +magazine, and the site, its boundaries, and surroundings, and distance the +building will be from any other buildings or works, &c., also the +character, and construction of all the mounds, and nature of the processes +to be carried on in the factory or building.[A] + +[Footnote A: Explosives Act, 38 Vict. ch. 17.] + +[Illustration: FIG. 1.--SECTION OF NITRO-GLYCERINE CONDUIT. _a_, lid; _b_, +lead lining; _c_, cinders.] + +The selection of a site for the danger area requires some attention. The +purpose for which it is required, that is, the kind of explosive that it +is intended to manufacture, must be taken into consideration. A perfectly +level piece of ground might probably be quite suitable for the purpose of +erecting a factory for the manufacture of gun-cotton or gunpowder, and +such materials, but would be more or less unsuitable for the manufacture +of nitro-glycerine, where a number of buildings are required to be upon +different levels, in order to allow of the flow of the liquid nitro- +glycerine from one building to another through a system of conduits. These +conduits (Fig. 1), which are generally made of wood and lined with lead, +the space between the woodwork and the lead lining, which is generally +some 4 or 5 inches, being filled with cinders, connect the various +buildings, and should slope gently from one to the other. It is also +desirable that, as far as possible, they should be protected by earth-work +banks, in the same way as the danger buildings themselves. They should +also be provided with covers, which should be whitewashed in hot weather. + +A great deal of attention should be given to these conduits, and they +should be very frequently inspected. Whenever it is found that a portion +of the lead lining requires repairing, before cutting away the lead it +should be very carefully washed, for several feet on either side of the +portion that it is intended to remove, with a solution of caustic soda or +potash dissolved in methylated spirit and water, and afterwards with water +alone. This decomposes the nitro-glycerine forming glycerine and potassium +nitrate. It will be found that the mixed acids attack the lead rather +quickly, forming sulphate and nitrate of lead, but chiefly the former. It +is on this account that it has been proposed to use pipes made of +guttapercha, but the great drawback to their use is that in the case of +anything occurring inside the pipes, such as the freezing of the nitro- +glycerine in winter, it is more difficult to find it out, and the +condition of the inside cannot be seen, whereas in the case of wooden +conduits it is an easy matter to lift the lids along the whole length of +the conduit. + +The buildings which require to be connected by conduits are of course +those concerned with the manufacture of nitro-glycerine. These buildings +are--(1) The nitrating house; (2) the separating house; (3) the filter +house; (4) the secondary separator; (5) the deposit of washings; (6) the +settling or precipitation house; and each of these buildings must be on a +level lower than the preceding one, in order that the nitro-glycerine or +acids may flow easily from one building to the next. These buildings are, +as far as possible, best placed together, and away from the other danger +buildings, such as the cartridge huts and dynamite mixing houses, but this +is not essential. + +All danger buildings should be protected by a lightning conductor, or +covered with barbed wire, as suggested by Professor Sir Oliver J. Lodge, +F.R.S., Professors Zenger, of Prague, and Melsens, of Brussels, and +everything possible should be done to keep them as cool as possible in the +summer. With this object they should be made double, and the intervening +space filled with cinders. The roof also should be kept whitewashed, and +the windows painted over thinly with white paint. A thermometer should be +suspended in every house. It is very essential that the floors of all +these buildings should be washed every day before the work-people leave. +In case any nitro-glycerine is spilt upon the floors, after sponging it up +as far as possible, the floor should be washed with an alcoholic solution +of soda or potash to decompose the nitro-glycerine, which it does +according to the equation[A]-- + +C_{3}H_{5}(NO_{3})_{3} + 3KOH = C_{3}H_{8}O_{3} + 3KNO_{3}. + +[Footnote A: See also Berthelot, _Comptes Rendus_, 1900, 131[12], 519- +521.] + +Every one employed in the buildings should wear list or sewn leather +shoes, which of course must be worn in the buildings only. The various +houses should be connected by paths laid with cinders, or boarded with +planks, and any loose sand about the site of the works should be covered +over with turf or cinders, to prevent its blowing about and getting into +the buildings. It is also of importance that stand pipes should be placed +about the works with a good pressure of water, the necessary hose being +kept in certain known places where they can be at once got at in the case +of fire, such as the danger area laboratory, the foreman's office, &c. It +is also desirable that the above precautions against fire should be tested +once a week. With regard to the heating of the various buildings in the +winter, steam pipes only should be used, and should be brought from a +boiler-house outside the danger area, and should be covered with +kieselguhr or fossil meal and tarred canvas. These pipes may be supported +upon poles. A stove of some kind should be placed in the corner of each +building, but it must be entirely covered in with woodwork, and as small a +length of steam pipes should be within the building as possible. + +In the case of a factory where nitro-glycerine and dynamite are +manufactured, it is necessary that the work-people should wear different +clothes upon the danger area than usual, as they are apt to become +impregnated with nitro-glycerine, and thus not very desirable or safe to +wear outside the works. It is also necessary that these clothes should not +contain any pockets, as this lessens the chance of matches or steel +implements being taken upon the danger area. Changing houses, one for the +men, and another for the girls, should also be provided. The tools used +upon the danger area should, whenever the building is in use, or contains +explosives, be made of phosphor bronze or brass, and brass nails or wooden +pegs should be used in the construction of all the buildings. + +[Illustration: FIG. 2.--MELSENS SYSTEM OF LIGHTNING CONDUCTORS.] + +~Lightning Conductors.~--The Explosive Substances Act, 38 Vict. ch. 17, +clause 10, says, "Every factory magazine and expense magazine in a +factory, and every danger building in a magazine, shall have attached +thereto a sufficient lightning conductor, unless by reason of the +construction by excavation or the position of such magazine or building, +or otherwise, the Secretary of State considers a conductor unnecessary, +and every danger building in a factory shall, if so required by the +Secretary of State, have attached thereto a sufficient lightning +conductor." + +The exact form of lightning conductor most suitable for explosive works +and buildings has not yet been definitely settled. Lightning-rod engineers +favour what is known as the Melsens system, due to Professor Melsens, of +Brussels, and Professor Zenger, of Prague, but first suggested by the late +Professor Clerk-Maxwell. In a paper read before the British Association, +Clerk-Maxwell proposed to protect powder-magazines from the effects of +lightning by completely surrounding or encasing them with sheet metal, or +a cage of metallic conductors. There were, however, several objections to +his system as he left it. + +Professor Melsens[A] has, while using the idea, made several important +alterations. He has multiplied the terminals, the conductors, and the +earth-connections. His terminals are very numerous, and assume the form of +an aigrette or brush with five or seven points, the central point being a +little higher than the rest, which form with it an angle of 45 deg.. He +employs for the most part galvanised-iron wire. He places all metallic +bodies, if they are of any considerable size, in communication with the +conducting system in such a manner as to form closed metallic circuits. +His system is illustrated in Fig. 2, taken from _Arms and Explosives_. + +[Footnote A: Belgian Academy of Science.] + +This system is a near approximation to J.C. Maxwell's cage. The system was +really designed for the protection of powder-magazines or store buildings +placed in very exposed situations. Zenger's system is identical with that +of Melsens, and has been extensively tried by the Austrian military +authorities, and Colonel Hess has reported upon the absolute safety of the +system. + +[Illustration: Fig. 3.--FRENCH SYSTEM OF LIGHTNING CONDUCTORS.] + +The French system of protecting powder-magazines is shown in Fig. 3, where +there are no brush terminals or aigrettes. The French military authorities +also protect magazines by erecting two or more lightning-rods on poles of +sufficient height placed close to, but not touching, the walls of the +magazine. These conductors are joined below the foundations and earthed as +usual. + +In the instructions issued by the Government, it is stated that the +lightning-rods placed upon powder-mills should be of such a height, and so +situated, that no danger is incurred in igniting the powder-dust in the +air by the lightning discharge at the pointed rod. In such a case a fork +or aigrette of five or more points should invariably be used in place of a +single point. + +[Illustration: FIG. 4_a_.--GOVERNMENT SYSTEM OF LIGHTNING CONDUCTORS FOR +LARGE BUILDINGS.] + +[Illustration: FIG. 4_b_.--GOVERNMENT SYSTEM OF LIGHTNING CONDUCTORS FOR +SMALL BUILDINGS.] + +In Fig. 4 (_a_ and _b_) is shown the Government method for protecting +buildings in which explosives are made or stored. Multiple points or +aigrettes would be better. Lord Kelvin and Professor Melsens favour +points, and it is generally admitted that lightning does not strike +buildings at a single point, but rather in a sheet; hence, in such cases, +or in the event of the globular form being assumed by the lightning, the +aigrette will constitute a much more effective protection than a single +point. As to the spacing of conductors, they may, even on the most +important buildings, be spaced at intervals of 50 feet. There will then be +no point on the building more than 25 feet from the conductor. This +"25-feet rule" can be adhered to with advantage in all overground buildings +for explosives. + +Underground magazines should, whenever possible, also be protected, +because, although less exposed than overground buildings, they frequently +contain explosives packed in metal cases, and hence would present a line +of smaller electrical resistance than the surrounding earth would offer to +the lightning. The conductor should be arranged on the same system as for +overground buildings, but be applied to the surface of the ground over the +magazines. + +In all situations where several conductors are joined in one system, the +vertical conductors should be connected both at the top and near the +ground line. The angles and the prominent portions of a building being the +most liable to be struck, the conductors should be carried over and along +these projections, and therefore along the ridges of the roof. The +conductors should be connected to any outside metal on the roofs and +walls, and specially to the foot of rain-water pipes. + +All the lightning conductors should be periodically tested, to see that +they are in working condition, at least every three months, according to +Mr Richard Anderson. The object of the test is to determine the resistance +of the earth-connection, and to localise any defective joints or parts in +the conductors. The best system of testing the conductors is to balance +the resistance of each of the earths against the remainder of the system, +from which the state of the earths may be inferred with sufficient +accuracy for all practical purposes. + +Captain Bucknill, R.E., has designed an instrument to test resistance +which is based on the Post Office pattern resistance coil, and is capable +of testing to approximate accuracy up to 200 ohms, and to measure roughly +up to 2,000 ohms. Mr R. Anderson's apparatus is also very handy, +consisting of a case containing three Leclanche cells, and a galvanometer +with a "tangent" scale and certain standard resistances. Some useful +articles on the protection of buildings from lightning will be found in +_Arms and Explosives_, July, August, and September 1892, and by Mr +Anderson, Brit. Assoc., 1878-80. + +~Nitro-Glycerine.~--One of the most powerful of modern explosive agents is +nitro-glycerine. It is the explosive contained in dynamite, and forms the +greater part of the various forms of blasting gelatines, such as gelatine +dynamite and gelignite, both of which substances consist of a mixture of +gun-cotton dissolved in nitro-glycerine, with the addition of varying +proportions of wood-pulp and saltpetre, the latter substances acting as +absorbing materials for the viscid gelatine. Nitro-glycerine is also +largely used in the manufacture of smokeless powders, such as cordite, +ballistite, and several others. + +Nitro-glycerol, or glycerol tri-nitrate, was discovered by Sobrero in the +year 1847. In a letter written to M. Pelouse, he says, "when glycerol is +poured into a mixture of sulphuric acid of a specific gravity of 1.84, and +of nitric acid of a gravity of 1.5, which has been cooled by a freezing +mixture, that an oily liquid is formed." This liquid is nitro-glycerol, or +nitro-glycerine, which for some years found no important use in the arts, +until the year 1863, when Alfred Nobel first started a factory in +Stockholm for its manufacture upon a large scale; but on account of some +serious accidents taking place, its use did not become general. + +It was not until Nobel conceived the idea (in 1866) of absorbing the +liquid in some absorbent earth, and thus forming the material that is now +known as dynamite, that the use of nitro-glycerine as an explosive became +general. + +Among those who improved the manufacture of nitro-glycerine was Mowbray, +who, by using pure glycerine and nitric acid free from nitrous acid, made +very great advances in the manufacture. Mowbray was probably the first to +use compressed air for the purpose of keeping the liquids well agitated +during the process of nitration, which he conducted in earthenware pots, +each containing a charge of 17 lbs. of the mixed acids and 2 lbs. of +glycerol. + +A few years later (1872), MM. Boutnny and Faucher, of Vonges,[A] proposed +to prepare nitro-glycerine by mixing the sulphuric acid with the +glycerine, thus forming a sulpho-glyceric acid, which was afterwards mixed +with a mixture of nitric and sulphuric acids. They claimed for this method +of procedure that the final temperature is much lower. The two mixtures +are mixed in the proportions--Glycerine, 100; nitric acid, 280; and +sulphuric acid, 600. They state that the rise of temperature upon mixing +is limited from 10 deg. to 15 deg. C.; but this method requires a period of +twenty-four hours to complete the nitration, which, considering the danger +of keeping the nitro-glycerine in contact with the mixed acids for so +long, probably more than compensates for the somewhat doubtful advantage +of being able to perform the nitration at such a low temperature. The +Boutnny process was in operation for some time at Pembrey Burrows in +Wales, but after a serious explosion the process was abandoned. + +[Footnote A: _Comptes Rendus_, 75; and Desortiaux, "Traite sur la Poudre," +684-686.] + +Nitro-glycerine is now generally made by adding the glycerine to a mixture +of sulphuric and nitric acids. The sulphuric acid, however, takes no part +in the reaction, but is absolutely necessary to combine with the water +that is formed by the decomposition, and thus to keep up the strength of +the nitric acid, otherwise lower nitrates of glycerine would be formed +that are soluble in water, and which would be lost in the subsequent +process of washing to which the nitro-compound is subjected, in order to +remove the excess of acids, the retention of which in the nitro-glycerol +is very dangerous. Nitro-glycerol, which was formerly considered to be a +nitro-substitution compound of glycerol, was thought to be formed thus-- + +C_{3}H_{8}O_{3} + 3HNO_{3} = C{3}H_{5}(NO_{2})_{3}O_{3} + 3H_{2}O; + +but more recent researches rather point to its being regarded as a nitric +ether of glycerol, or glycerine, and to its being formed thus-- + +C_{3}H_{8}O_{3} + 3 HNO_{3} = C{3}H_{5}(NO_{3})_{3} + 3H_{2}O. + 92 227 + + |OH +The formula of glycerine is C_{3}H_{8}O_{8}, or C_{3}H_{5}|OH + |OH + + |ONO_{2} +and that of the mono-nitrate of glycerine, C_{3}H_{5}|OH + |OH + + |ONO_{2} +and of the tri-nitrate or (nitro-glycerine), C_{3}H_{5}|ONO_{2} + |ONO_{2} + +that is, the three hydrogens of the semi-molecules of hydroxyl in the +glycerine have been replaced by the NO_{2} group. + +In the manufacture upon the large scale, a mixture of three parts by +weight of nitric acid and five parts of sulphuric acid are used. From the +above equation it will be seen that every 1 lb. of glycerol should give +2.47 lbs. of nitro-glycerol ((227+1)/92 = 2.47), but in practice the yield +is only about 2 lbs. to 2.22, the loss being accounted for by the +unavoidable formation of some of the lower nitrate, which dissolves in +water, and is thus washed away, and partly perhaps to the presence of a +little water (or other non-nitrable matter) in the glycerine, but chiefly +to the former, which is due to the acids having become too weak. + + + + +CHAPTER II. + +_MANUFACTURE OF NITRO-GLYCERINE._ + +Properties of Nitro-Glycerine--Manufacture of Nitro-Glycerine--Nitration-- +The Nathan Nitrator--Separation--Filtering and Washing--The Waste Acids-- +Treatment of the Waste Acid from the Manufacture of Nitro-Glycerine and +Gun-Cotton. + + +~Properties of Nitro-Glycerine.~--Nitro-glycerol is a heavy oily liquid of +specific gravity 1.6 at 15 deg. C., and when quite pure is colourless. The +commercial product is a pale straw yellow, but varies much according to +the purity of the materials used in its manufacture. It is insoluble in +water, crystallises at 10.5 deg. C., but different commercial samples behave +very differently in this respect, and minute impurities prevent or delay +crystallisation. Solid nitro-glycerol[A] melts at about 12 deg. C., but +requires to be exposed to this temperature for some time before melting. +The specific gravity of the solid form is 1.735 at +10 deg. C.; it contracts +one-twelfth of its volume in solidifying. Beckerheim[B] gives the specific +heat as 0.4248 between the temperatures of 9.5 deg. and 9.8 deg. C., and L. de +Bruyn gives the boiling point as above 200 deg.. + +[Footnote A: Di-nitro-mono chlorhydrin, when added to nitro-glycerine up +to 20 per cent., is said to prevent its freezing.] + +[Footnote B: _Isb., Chem. Tech._, 22, 481-487. 1876.] + +Nitro-glycerine has a sweet taste, and causes great depression and +vertigo. It is soluble in ether, chloroform, benzene, glacial acetic acid, +and nitro-benzene, in 1.75 part of methylated spirit, very nearly +insoluble in water, and practically insoluble in carbon bisulphide. Its +formula is C_{3}H_{5}(NO_{3})_{3}, and molecular weight 227. When pure, it +may be kept any length of time without decomposition. Berthelot kept a +sample for ten years, and Mr G. M'Roberts, of the Ardeer Factory, for nine +years, without their showing signs of decomposition; but if it should +contain the smallest trace of free acid, decomposition is certain to be +started before long. This will generally show itself by the formation of +little green spots in the gelatine compounds, or a green ring upon the +surface of liquid nitro-glycerine. Sunlight will often cause it to +explode; in fact, a bucket containing some water that had been used to +wash nitro-glycerine, and had been left standing in the sun, has in our +experience been known to explode with considerable force. Nitro-glycerine +when pure is quite stable at ordinary temperatures, and samples have been +kept for years without any trace of decomposition. It is very susceptible +to heat, and even when quite pure will not stand a temperature of 100 deg. C. +for a longer period than a few hours, without undergoing decomposition. Up +to a temperature of 45 deg. C., however, properly made and purified nitro- +glycerine will remain unchanged almost indefinitely. The percentage +composition of nitroglycerine is as follows:-- + + Found. Theory for C_{3}H_{5}(N0_{2})_{3}. + +Carbon 15.62 15.86 per cent. +Hydrogen 2.40 2.20 " +Nitrogen 17.90 18.50 " +Oxygen ... 63.44 " + +The above analysis is by Beckerheim. Sauer and Adou give the nitrogen as +18.35 to 10.54 per cent. by Dumas' method; but I have never found any +difficulty in obtaining percentages as high as 18.46 by the use of Lunge's +nitrometer. The decomposition products by explosion are shown by the +following equation-- + + 2C_{3}H_{5}(NO_{3})_{3} = 6CO_{2} + 5H_{2}O + 6N + O; + +that is, it contains an excess of 3.52 per cent. of oxygen above that +required for complete combustion; 100 grms. would be converted into-- + +Carbonic Acid (CO_{2}) 58.15 per cent. +Water 19.83 " +Oxygen 3.52 per cent. +Nitrogen 18.50 " + +The volume of gases produced at 0 deg. and 760 mm., calculated from the above, +is 714 litres per kilo, the water being taken as gaseous. Nitro-glycerine +is decomposed differently if it is ignited as dynamite (i.e., kieselguhr +dynamite), and if the gases are allowed to escape freely under a pressure +nearly equal to that of the atmosphere. Sarrau and Vieille obtained under +these conditions, for 100 volumes of gas-- + +NO 48.2 per cent. +CO 35.9 " +CO_{2} 12.7 " +H 1.6 per cent. +N 1.3 " +CH_{4} 0.3 " + +These conditions are similar to those under which a mining charge, simply +ignited by the cap, burns away slowly under a low pressure (i.e., a miss +fire). In a recent communication, P.F. Chalon (_Engineering and Mining +Journal_, 1892) says, that in practice nitro-glycerine vapour, carbon +monoxide, and nitrous oxide, are also produced as the result of +detonation, but he attributes their formation to the use of a too feeble +detonator. + +Nitro-glycerine explodes very violently by concussion. It may be burned in +an open vessel, but if heated above 250 deg. C. it explodes. Professor C.E. +Munroe gives the firing point as 2O3 deg.-2O5 deg. C., and L. de Bruyn[A] states +its boiling point as 185 deg.. He used the apparatus devised by Horsley. The +heat of formation of nitro-glycerine, as deduced from the heat of +combustion by M. Longuinine, is 432 calories for 1 grm.; and the heat of +combustion equals 1,576 cals. for 1 grm. In the case of nitro-glycerine +the heat of total combustion and the heat of complete decomposition are +interchangeable terms, since it contains an excess of oxygen. According to +Dr W.H. Perkin, F.R.S.,[B] the magnetic rotation of nitro-gylcerine is +5,407, and that of tri-methylene nitrate, 4.769 (diff. = .638). Dr Perkin +says: "Had nitro-glycerine contained its nitrogen in any other combination +with oxygen than as -O-NO_{2}, as it might if its constitution had been +represented as C_{3}H_{2}(NO_{2})_{3}(OH)_{3}, the rotation when compared +with propyl nitrate (4.085) would be abnormal." + +[Footnote A: _Jour. Soc. Chem. Ind._, June 1896, p. 471.] + +[Footnote B: _Jour. Chem. Soc._, W.H. Perkin, 1889, p. 726.] + +The solubility of nitro-glycerine in various solvents has been +investigated by A.H. Elliot; his results may be summarised as follows:-- + +_______________________________________________________________________ + | | +Solvent. | Cold. | Warm. +_____________________________|______________________|__________________ + | | +Water | Insoluble | Slightly soluble +Alcohol, absolute | Soluble | Soluble + " 93% | " | " + " 80% | Slowly soluble | " + " 50% | Insoluble | Slightly soluble +Methyl alcohol | Soluble | Soluble +Amyl " | " | " +Ether, ethylic | " | " + " acetic | " | " +Chloroform | " | " +Acetone | " | " +Sulphuric acid (1.845) | " | " +Nitric acid (1.400) | Slowly soluble | " +Hydrochloric acid (1.200) | Insoluble, decomposed| Slowly soluble +Acetic acid, glacial | Soluble | Soluble +Carbolic acid | " | " +Astral oil | Insoluble | Insoluble +Olive " | Soluble | Soluble +Stearine oil | " | " +Mineral jelly | Insoluble | Insoluble +Glycerine | " | " +Benzene | Soluble | Soluble +Nitro-benzene | " | " +Toluene | " | " +Carbon bi-sulphide | Insoluble | Slightly affected +Turpentine | " | Soluble +Petroleum naphtha, 71 deg.-76 deg. B.| " | Insoluble +Caustic soda (1:10 solution) | Insoluble. | Insoluble. +Borax, 5% solution | " | " +Ammonia (.980) | " | " slightly + | | affected. +Ammonium sulph-hydrate | Insoluble, sulphur | Decomposed. + | separates | +Iron sulphate solution | Slightly affected | Affected. +Iron chloride (1.4 grm. Fe | Slowly affected | Decomposed. + to 10 c.c. N_{2}O) | | +Tin chloride | Slightly affected | Affected. +_____________________________|______________________|__________________ + +Many attempts have been made to prepare nitro-glycerine explosives capable +of withstanding comparatively low temperatures without freezing, but no +satisfactory solution of the problem has been found. Among the substances +that have been proposed and used with more or less success, are nitro- +benzene, nitro-toluene, di-nitro-mono-chlorhydrine, solid nitro +derivatives of toluene,[A] are stated to lower the freezing point of +nitro-glycerine to -20 deg.C. without altering its sensitiveness and +stability. The subject has been investigated by S. Nauckhoff,[B] who +states that nitroglycerine can be cooled to temperatures (-40 deg. to -50 deg. C.) +much below its true freezing point, without solidifying, by the addition +of various substances. When cooled by means of a mixture of solid carbon, +dioxide, and ether, it sets to a glassy mass, without any perceptible +crystallisation. The mass when warmed to 0 deg.C. first rapidly liquefies and +then begins to crystallise. The true freezing point of pure nitro- +glycerine was found to be 12.3 deg.C. The technical product, owing to the +presence of di-nitro-glycerine, freezes at 10.5 deg. C. According to Raoult's +law, the lowering of the freezing point caused by _m_ grms. of a substance +with the molecular weight M, when dissolved in 100 grms. of the solvent, +is expressed by the formula: [Delta] = E(_m_/M), where E is a constant +characteristic for the solvent in question. The value of E for nitro- +glycerine was found to be 70.5 when calculated, according to Van't Hoff's +formula, from the melting point and the latent heat of fusion of the +substance. Determinations of the lowering of the freezing point of nitro- +glycerine by additions of benzene, nitro-benzene, di-nitro-benzene, tri- +nitro-benzene, p.-nitro-toluene, o.-nitro-toluene, di-nitro-toluene, +naphthalene, nitro-naphthalene, di-nitro-naphthalene, ethyl acetate, ethyl +nitrate, and methyl alcohol, gave results agreeing fairly well with +Raoult's formula, except in the case of methyl alcohol, for which the +calculated lowering of the freezing point was greater than that observed, +probably owing to the formation of complex molecules in the solution. The +results show that, in general, the capacity of a substance to lower the +freezing point of nitro-glycerine depends, not upon its freezing point, or +its chemical composition or constitution, but upon its molecular weight. +Nauckhoff states that a suitable substance for dissolving in nitro- +glycerine, in order to lower the freezing point of the latter, must have a +relatively low molecular weight, must not appreciably diminish the +explosive power and stability of the explosive, and must not be easily +volatile at relatively high atmospheric temperatures; it should, if +possible, be a solvent of nitro-cellulose, and in every case must not have +a prejudicial influence on the gelatinisation of the nitro-cellulose. + +[Footnote A: Eng. Pat. 25,797, November 1904.] + +[Footnote B: _Z. Angew. Chem._, 1905, 18, 11-22, 53-60.] + +~Manufacture of Nitro-Glycerine.~--Nitro-glycerine is prepared upon the +manufacturing scale by gradually adding glycerine to a mixture of nitric +and sulphuric acids of great strength. The mixed acids are contained in a +lead vessel, which is kept cool by a stream of water continually passing +through worms in the interior of the nitrating vessel, and the glycerine +is gradually added in the form of a fine stream from above. The +manufacture can be divided into three distinct operations, viz., +nitration, separation, and washing, and it will be well to describe these +operations in the above order. + +~Nitration.~--The most essential condition of nitrating is the correct +composition and strength of the mixed acids. The best proportions have +been found to be three parts by weight of nitric acid of a specific +gravity 1.525 to 1.530, and containing as small a portion of the oxides of +nitrogen as possible, to five parts by weight of sulphuric acid of a +specific gravity of 1.840 at 15 deg. C., and about 97 per cent. of mono- +hydrate. It is of the very greatest importance that the nitric acid should +be as strong as possible. Nothing under a gravity of 1.52 should ever be +used even to mix with stronger acid, and the nitration will be +proportional to the strength of the acid used, provided the sulphuric acid +is also strong enough. It is also of great importance that the oxides of +nitrogen should be low, and that they should be kept down to as low as 1 +per cent., or even lower. It is also very desirable that the nitric acid +should contain as little chlorine as possible. The following is the +analysis of a sample of nitric acid, which gave very good results upon the +commercial scale:--Specific gravity, 1.525, N_{2}O_{4}, 1.03 per cent.; +nitric acid (HNO_{3}), 95.58 per cent. + +The amount of real nitric acid (mono-hydrate) and the amount of nitric +peroxide present in any sample should always be determined before it is +used for nitrating purposes. The specific gravity is not a sufficient +guide to the strength of the acid, as an acid having a high gravity, due +to some 3 or 4 per cent of nitric oxides in solution, will give very poor +nitration results. A tenth normal solution of sodium hydroxide (NaOH), +with phenol-phthalein as indicator, will be found the most convenient +method of determining the total acid present. The following method will be +found to be very rapid and reliable:--Weigh a 100 c.c. flask, containing a +few cubic centimetres of distilled water, and then add from a pipette 1 +c.c. of the nitric acid to be examined, and reweigh (this gives the weight +of acid taken). Now make up to 100 c.c. at 15 deg. C.; shake well, and take +out 10 c.c. with a pipette; drain into a small Erlenmeyer flask, and add a +little of the phenol-phthalein solution, and titrate with the tenth normal +soda solution. + +The nitric peroxide can be determined with a solution of potassium +permanganate of N/10 strength, thus: Take a small conical flask, +containing about 10 c.c. of water, and add from a burette 10 to 16 c.c. of +the permanganate solution; then add 2 c.c. of the acid to be tested, and +shake gently, and continue to add permanganate solution as long as it is +decolourised, and until a faint pink colour is permanent. + +_Example._ N/10 permanganate 3.16 grms. per litre, 1 c.c. = O.0046 grm. +N_{2}O_{4}, 2 c.c. of sample of acid specific gravity 1.52 = 3.04 grms. +taken for analysis. Took 20 c.c. permanganate solution, O.0046 x 20 =.092 +grm. N_{2}O_{4}, and (.092 x 100)/3.04 = 3.02 per cent. N_{2}O_{4}. The +specific gravity should be taken with an hydrometer that gives the +specific gravity directly, or, if preferred, the 2 c.c. of acid may be +weighed. + +A very good method of rapidly determining the strength of the sulphuric +acid is as follows:--Weigh out in a small weighing bottle, as nearly as +possible, 2.45 grms. This is best done by running in 1.33 c.c. of the acid +(1.33 x 1.84 = 2.447). Wash into a large Erlenmeyer flask, carefully +washing out the bottle, and also the stopper, &c. Add a drop of phenol- +phthalein solution and titrate, with a half normal solution of sodium +hydrate (use a 100 c.c. burette). Then if 2.45 grms. exactly have been +taken, the readings on the burette will equal percentages of H_{2}SO_{4} +(mono-hydrate) if not, calculate thus:--2.444 grms. weighed, required 95.4 +c.c. NaOH. Then-- + +2.444 : 95.4 :: 2.45 : _x_ = 95.64 per cent. H_{2}SO_{4}. + +It has been proposed to free nitric acid from the oxides of nitrogen by +blowing compressed air through it, and thus driving the gases in solution +out. The acid was contained in a closed lead tank, from which the escaping +fumes were conducted into the chimney shaft, and on the bottom of which +was a lead pipe, bent in the form of a circle, and pierced with holes, +through which the compressed air was made to pass; but the process was not +found to be of a very satisfactory nature, and it is certainly better not +to allow the formation of these compounds in the manufacture of the acid +in the first instance. Another plan, however, is to heat the acid gently, +and thus drive out the nitrous gases. Both processes involve loss of +nitric acid. + +Having obtained nitric and sulphuric acids as pure as possible, the next +operation is to mix them. This is best done by weighing the carboys in +which the acids are generally stored before the acids are drawn off into +them from the condensers, and keeping their weights constantly attached to +them by means of a label. It is then a simple matter to weigh off as many +carboys of acid as may be required for any number of mixings, and subtract +the weights of the carboys. The two acids should, after being weighed, be +poured into a tank and mixed, and subsequently allowed to flow into an +acid egg or montjus, to be afterwards forced up to the nitrating house in +the danger area. The montjus or acid egg is a strong cast-iron tank, of +either an egg shape, or a cylinder with a round end. If of the former +shape, it would lie on its side, and upon the surface of the ground, and +would have a manhole at one end, upon which a lid would be strongly bolted +down; but if of the latter shape, the lid, of course, is upon the top, and +the montjus itself is let into the ground. In either case, the principle +is the same. One pipe, made of stout lead, goes to the bottom, and another +just inside to convey the compressed air, the acids flowing away as the +pressure is put on, just as blowing down one tube of an ordinary wash- +bottle forces the water up the other tube to the jet. The pressure +necessarily will, of course, vary immensely, and will depend upon the +height to which the acid has to be raised and the distance to be +traversed. + +The mixed acids having been forced up to the danger area, and to a level +higher than the position of the nitrating house, should, before being +used, be allowed to cool, and leaden tanks of sufficient capacity to hold +at least enough acid for four or five nitrations should be placed in a +wooden house upon a level at least 6 or 7 feet above the nitrating house. +In this house also should be a smaller lead tank, holding, when filled to +a certain mark, just enough of the mixed acids for one nitration. The +object of this tank is, that as soon as the man in charge knows that the +last nitration is finished, he refills this smaller tank (which contains +just enough of the mixed acids), and allows its contents to flow down into +the nitrating house and into the nitrator, ready for the next nitration. +The nitration is usually conducted in a vessel constructed of lead, some 4 +feet wide at the bottom, and rather less at the top, and about 4 feet or +so high. The size, of course, depends upon the volume of the charge it is +intended to nitrate at one operation, but it is always better that the +tank should be only two-thirds full. A good charge is 16 cwt. of the mixed +acids, in the proportion of three to five; that is, 6 cwt. of nitric acid, +and 10 cwt. of sulphuric acid, and 247 lbs. of glycerine. + +Upon reference to the equation showing the formation of nitro-glycerine, +it will be seen that for every 1 lb. of glycerine 2.47 lbs. of nitro- +glycerine should be furnished,[A] but in practice the yield is only a +little over 2 lbs., the loss being accounted for by the unavoidable +formation of some of the lower nitrate of glycerine (the mono-nitrate), +which afterward dissolves in the washing waters. The lead tank (Fig. 5) is +generally cased in woodwork, with a platform in front for the man in +charge of the nitrating to stand upon, and whence to work the various +taps. The top of the tank is closed in with a dome of lead, in which is a +small glass window, through which the progress of the nitrating operation +can be watched. From the top of this dome is a tube of lead which is +carried up through the roof of the building. It serves as a chimney to +carry off the acid fumes which are given off during the nitration. The +interior of this tank contains at least three concentric spirals of at +least 1-inch lead pipe, through which water can be made to flow during the +_whole_ operation of nitrating. Another lead pipe is carried through the +dome of the tank, as far as the bottom, where it is bent round in the form +of a circle. Through this pipe, which is pierced with small holes, about 1 +inch apart, compressed air is forced at a pressure of about 60 lbs. in +order to keep the liquids in a state of constant agitation during the +whole period of nitration. There must also be a rather wide pipe, of say 2 +inches internal diameter, carried through the dome of the tank, which will +serve to carry the mixed acid to be used in the operation into the tank. +There is still another pipe to go through the dome, viz., one to carry the +glycerine into the tank. This need not be a large bore pipe, as the +glycerine is generally added to the mixed acids in a thin stream (an +injector is often used). + +[Footnote A: Thus if 92 lbs. glycerine give 227 lbs. nitro-glycerine, +(277 x 1)/92 = 2.47 lbs.] + +[Illustration: FIG. 5.--TOP OF NITRATOR. _A_, Fume Pipe; _B_, Water Pipes +for Cooling; _C_, Acid Mixture Pipe; _E_, Compressed Air; _G_, Glycerine +Pipe and Funnel; _T_, Thermometer; _W_, Window.] + +Before the apparatus is ready for use, it requires to have two +thermometers fixed, one long one to reach to the bottom of the tank, and +one short one just long enough to dip under the surface of the acids. When +the tank contains its charge, the former gives the temperature of the +bottom, and the latter of the top of the mixture. The glycerine should be +contained in a small cistern, fixed in some convenient spot upon the wall +of the nitrating house, and should have a pipe let in flush with the +bottom, and going through the dome of the nitrating apparatus. It must of +course be provided with a tap or stop-cock, which should be placed just +above the point where the pipe goes through the lead dome. + +Some method of measuring the quantity of glycerine used must be adopted. A +gauge-tube graduated in inches is a very good plan, but it is essential +that the graduations should be clearly visible to the operator upon the +platform in front of the apparatus. A large tap made of earthenware (and +covered with lead) is fixed in the side of the nitrating tank just above +the bottom, to run off the charge after nitration. This should be so +arranged that the charge may be at option run down the conduit to the next +house or discharged into a drowning tank, which may sometimes be necessary +in cases of decomposition. The drowning tank is generally some 3 or 4 +yards long and several feet deep, lined with cement, and placed close +outside the building. + +The apparatus having received a charge of mixed acids, the water is +started running through the pipes coiled inside the tank, and a slight +pressure of compressed air is turned on,[A] to mix the acids up well +before starting. The nitration should not be commenced until the two +thermometers register a temperature of 18 deg. C. The glycerine tap is then +partially opened, and the glycerine slowly admitted, and the compressed +air turned on full, until the contents of the apparatus are in a state of +very brisk agitation. A pressure of about 40 lbs. is about the minimum (if +247 lbs. of glycerine and 16 cwt. of acids are in the tank). If the +glycerine tube is fitted with an injector, it may be turned on almost at +once. The nitration will take about thirty minutes to complete, but the +compressed air and water should be kept on for an additional ten minutes +after this, to give time for all the glycerine to nitrate. The temperature +should be kept as low as possible (not above 18 deg. C.). + +[Footnote A: At the Halton Factory, Germany, cylinders of compressed +carbon dioxide are connected with the air pipes so that in the event of a +failure of the air supply the stirring can be continued with this gas if +necessary.] + +The chief points to attend to during the progress of the nitration are-- + +1. The temperature registered by the two thermometers. + +2. The colour of the nitrous fumes given off (as seen through the little +window in the dome of the apparatus). + +3. The pressure of the compressed air as seen from a gauge fixed upon the +air pipe just before it enters the apparatus. + +4. The gauge showing the quantity of glycerine used. The temperature, as +shown by either of the two thermometers, should not be at any time higher +than 25 deg. C. + +If it rises much above this point, the glycerine should be at once shut +off, and the pressure of air increased for some few minutes until the +temperature falls, and no more red fumes are given off. + +The nitration being finished, the large earthenware tap at the bottom of +the tank is opened, and the charge allowed to flow away down the conduit +to the next building, i.e., to the separator. + +The nitrating house is best built of wood, and should have a close-boarded +floor, which should be kept scrupulously clean, and free from grit and +sand. A wooden pail and a sponge should be kept in the house in order that +the workman may at once clean up any mess that may be made, and a small +broom should be handy, in order that any sand, &c., may be at once +removed. It is a good plan for the nitrator to keep a book in which he +records the time of starting each nitration, the temperature at starting +and at the finish, the time occupied, and the date and number of the +charge, as this enables the foreman of the danger area at any time to see +how many charges have been nitrated, and gives him other useful +information conducive to safe working. Edward Liebert has devised an +improvement in the treatment of nitro-glycerine. He adds ammonium sulphate +or ammonium nitrate to the mixed acids during the operation of nitrating, +which he claims destroys the nitrous acid formed according to the +equation-- + +(NH_{4})_{2}SO_{4} + 2HNO_{3} = H_{2}SO_{4} + 2N_{2} + 4H_{2}O. + +I am not aware that this modification of the process of nitration is in +use at the present time. + +The newly made charge of nitro-glycerine, upon leaving the nitrating +house, flows away down the conduit, either made of rubber pipes, or better +still, of woodwork, lined with lead and covered with lids made of wood (in +short lengths), in order that by lifting them at any point the condition +of the conduit can be examined, as this is of the greatest importance, and +the conduit requires to be frequently washed out and the sulphate of lead +removed. This sulphate always contains nitro-glycerine, and should +therefore be burnt in some spot far removed from any danger building or +magazine, as it frequently explodes with considerable violence. + +[Illustration: FIG. 6.--SMALL NITRATOR. _N_, Tap for Discharging; _P_, +Water Pipes; _T_, Thermometer; _W_, Windows; _P'_, Glycerine Pipe.] + +In works where the manufacture of nitro-glycerine is of secondary +importance, and some explosive containing only perhaps 10 per cent. of +nitroglycerine is manufactured, and where 50 or 100 lbs. of glycerine are +nitrated at one time, a very much smaller nitrating apparatus than the one +that has been already described will be probably all that is required. In +this case the form of apparatus shown in Fig. 6 will be found very +satisfactory. It should be made of stout lead (all lead used for tanks, +&c., must be "chemical lead"), and may be made to hold 50 or 100 lbs. as +found most convenient. This nitrator can very well be placed in the same +house as the separator; in fact, where such a small quantity of nitro- +glycerine is required, the whole series of operations, nitrating, +separation, and washing, &c., may very well be performed in the same +building. It will of course be necessary to place the nitrator on a higher +level than the separator, but this can easily be done by having platforms +of different heights, the nitration being performed upon the highest. The +construction of this nitrator is essentially the same as in the larger +one, the shape only being somewhat different. Two water coils will +probably be enough, and one thermometer. It will not be necessary to cover +this form in with woodwork. + +~The Nathan Nitrator.~[A]--This nitrator is the patent of Lt. Col. F.L. +Nathan and Messrs J.M. Thomson and W. Rintoul of Waltham Abbey, and will +probably before long entirely supersede all the other forms of nitrator on +account of its efficiency and economy of working. With this nitrator it is +possible to obtain from 2.21 to 2.22 parts of nitro-glycerine from every 1 +part of glycerine. The apparatus is so arranged that the nitration of the +glycerine, the separation of nitro-glycerine produced, as well as the +operation of "after-separation," are carried out in one vessel. The usual +nitrating vessel is provided with an acid inlet pipe at the bottom, and a +glass separation cylinder with a lateral exit or overflow pipe at the top. +This cylinder is covered by a glass hood or bell jar during nitration to +direct the escaping air and fumes into a fume pipe where the flow of the +latter may be assisted by an air injector. The lateral pipe in the +separation cylinder is in connection with a funnel leading to the prewash +tank. The drawing (Fig. 7) shows a vertical section of the apparatus; _a_ +is the nitrating vessel of usual construction, having at the bottom an +acid inlet pipe with three branches, one leading to the de-nitrating +plant, _c_ leading to the drowning tank, and _d_, which extends upwards +and has two branches, _e_ leading to the nitrating acids tank, and _f_ to +the waste acid tank. On the sloped bottom of the nitrating vessel _a_ lies +a coil _g_ of perforated pipe for blowing air, and there are in the vessel +several coils _h_, three shown in the drawing, for circulation of cooling +water. At the top of the vessel there is a glass cylinder _i_, having a +lateral outlet _j_ directed into the funnel mouth of a pipe _k_ leading to +the prewash tank. Over the cylinder _i_ is a glass globe _l_, into which +opens a pipe _m_ for leading off fumes which may be promoted by a +compressed air jet from a pipe _r_ operating as an injector. Into an +opening of the glass dome _l_ is inserted a vessel _n_, which is connected +by a flexible pipe _p_ to the glycerine tank, and from the bottom of _n_, +which is perforated and covered with a disc perforated with holes +registering with those through the bottom, this disc being connected by a +stem with a knob _q_ by which it can be turned so as to throttle or cut +off passage of glycerine through the bottom. _s_ is a thermometer for +indicating the temperature of the contents of the vessel. + +[Footnote A: Eng. Pat. 15,983, August 1901.] + +[Illustration: FIG. 7.--NATHAN'S NITRATOR FOR NITRO-GLYCERINE. (_a_) +Nitrating Vessel; (_b_) to Separating Vessel; (_c_) to Drowning Tank; +(_e_) Nitrating Acids enter (_f_) to the Waste Acids; (_g_) Coils for +Compressed Air; (_h_) Pipes for Cooling Water; (_i_) Glass Cylinder; (_j_) +Outlet to _k_; (_k_) leading to Prewash Tank; (_l_) Glass Dome; (_m_) Pipe +to lead off for Escape of Fumes; (_n_) Vessel; (_p_) Pipe conveying +Glycerine; (_q_) Knob to turn off Glycerine; (_r_) Compressed Air Jet; +(_s_) Thermometer.] + +In operating with this apparatus the nitrating acid is introduced into the +nitrating vessel by opening the cock of the pipe _e_. The glycerine is +then run in by introducing _n_ and opening the valve at its bottom, the +contents of the vessel being agitated by air blown through the +perforations of the pipe _g_. When the glycerine is all nitrated and the +temperature has slightly fallen, the circulation of the water through the +coils _h_ and the air-stirring are stopped, and the glycerine supply +vessel _n_ is removed. The nitro-glycerine as it separates from the acids +is raised by introducing by the pipe _f_ waste acid from a previous +charge, this displacing the nitro-glycerine upwards and causing it to flow +by the outlet, _j_ and pipe _k_ to the prewash tank. When nearly all the +nitro-glycerine has been separated in this manner the acids in the +apparatus may be run off by the pipe _b_ to an after separating vessel for +further settling, thus leaving the apparatus free for another nitration, +or the nitrating vessel itself may be used as an after separating bottle +displacing the nitro-glycerine with waste acid as it rises to the top, or +skimming off in the usual manner. When the separation of the nitro- +glycerine is complete the waste acid is run off and denitrated as usual, a +portion of it being reserved for the displacement of the nitro-glycerine +in a subsequent operation. + +In a further patent (Eng. Pat. 3,020, 1903) the authors propose with the +object of preventing the formation and separation of nitro-glycerine in +the waste acids, after the nitro-glycerine initially formed in the +nitrating vessel has been separated and removed, to add a small quantity +of water to the waste acids; this is carried out as follows. A relatively +small quantity of water is added, and this prevents all further separation +of nitro-glycerine, and at the same time the strength of the waste acids +is so slightly reduced that their separation and re-concentration are not +affected. "After-separation" is thus done away with, and the nitro- +glycerine plant simplified and its output increased. After nitration +separation is commenced at a temperature such that when all the displacing +acid has been added, and the separation of the nitro-glycerine is +complete, the temperature of the contents of the nitrating vessel shall +not be lower than 15 deg. C. A sufficient quantity of the displacing acid is +then run off through the waste-acid cock to allow of the remaining acids +being air-stirred without splashing over the top. A small quantity of +water, from 2 to 3 per cent. according to strength of acid; if waste +consists of sulphuric acid (monohydrate), 62 per cent.; nitric acid +(anhydrous), 33 per cent. and water 5 per cent.; temperature 15 deg. C., then +2 per cent. of water is added; if waste acids contain less than 4 per +cent. of water of temperature lower than 15 deg. C., from 3 to 5 per cent. of +water may have to be added. The water is added slowly through the +separator cylinder, and the contents of the nitrator air-stirred, but not +cooled, the temperature being allowed to rise slowly and regularly as the +water is added--usually about 3 deg. C. for each per cent. of water added. +When air-agitation has been stopped, the acids are kept at rest for a +short time, in order to allow of any small quantity of initially formed +nitro-glycerine adhering to the coils and sides of the vessel rising to +the top. When this has been separated by displacement, the acids are ready +for denitration, or can be safely stored without further precaution. + +~Separation.~--The nitro-glycerine, together with the mixed acids, flows +from the nitrating house to the separating house, which must be on a lower +level than the former. The separating house contains a large lead-lined +tank, closed in at the top with a wooden lid, into which a lead pipe of +large bore is fixed, and which is carried up through the roof of the +building, and acts as a chimney to carry off any fumes. A little glass +window should be fixed in this pipe in order that the colour of the +escaping fumes may be seen. The conduit conveying the nitro-glycerine +enters the building close under the roof, and discharges its contents into +the tank through the pipe G (Fig. 8). The tank is only about two-thirds +filled by the charge. There is in the side of the tank a small window of +thick plate glass, which enables the workman to see the level of the +charge, and also to observe the progress of the separation, which will +take from thirty minutes to one hour. + +The tank should be in connection with a drowning tank, as the charge +sometimes gets very dangerous in this building. It must also be connected +by a conduit with the filter house, and also to the secondary separator by +another conduit. The tank should also be fitted with a compressed air +pipe, bent in the form of a loop. It should lie upon the bottom of the +vat. The object of this is to mix up the charge in case it should get too +hot through decomposition. A thermometer should of course be fixed in the +lid of the tank, and its bulb should reach down to the middle of the +nitro-glycerine (which rests upon the surface of the mixed acids, the +specific gravity of the nitro-glycerine being 1.6, and that of the waste +acids 1.7; the composition of the acids is now 11 per cent. HNO_{3}, 67 +per cent. H_{2}SO_{4}, and 22 per cent. water), and the temperature +carefully watched. + +[Illustration: FIG. 8.--SEPARATOR. _A_, Compressed Air Pipes; _G_, Nitro- +glycerine enters from Nitrator; _N_, Nitro-glycerine to _P_; _L_, Lantern +Window; _W_, Window in Side; _S_, Waste Acids to Secondary Separator; _T_, +Tap to remove last traces of Nitro-glycerine; _P_, Lead Washing Tank; _A_, +Compressed Air; _W_, Water Pipe; _N_, Nitro-glycerine from Separator.] + +If nothing unusual occurs, and it has not been necessary to bring the +compressed air into use, and so disturb the process of separation, the +waste acids may be run away from beneath the nitro-glycerine, and allowed +to flow away to the secondary separator, where any further quantity of +nitro-glycerine that they contain separates out after resting for some +days. The nitro-glycerine itself is run into a smaller tank in the same +house, where it is washed three or four times with its own bulk of water, +containing about 3 lbs. of carbonate of soda to neutralise the remaining +acid. This smaller tank should contain a lead pipe, pierced and coiled +upon the bottom, through which compressed air may be passed, in order to +stir up the charge with the water and soda. After this preliminary +washing, the nitro-glycerine is drawn off into indiarubber buckets, and +poured down the conduit to the filter house. The wash waters may be sent +down a conduit to another building, in order to allow the small quantity +of nitro-glycerine that has been retained in the water as minute globules +to settle, if thought worth the trouble of saving. This, of course, will +depend upon the usual out-turn of nitro-glycerine in a day, and the +general scale of operations. + +[Illustration: FIG. 9.--FILTERING AND WASHING PLANT. _W_, Lead Washing +Tank; _WP_, Water Pipe; _L_, Lid; _S_, Nitro-glycerine from Separator; _A, +B, C_, Filtering Tanks; _B2_, Indiarubber Bucket.] + +~Filtering and Washing.~--The filter house (Fig. 9), which must of course +be again on a somewhat lower level than the separating house, must be a +considerably larger building than either the nitrating or separating +houses, as it is always necessary to be washing some five or six charges +at the same time. Upon the arrival of the nitro-glycerine at this house, +it first flows into a lead-lined wooden tank (W), containing a compressed +air pipe, just like the one in the small tank in the separating house. +This tank is half filled with water, and the compressed air is turned on +from half to a quarter of an hour after the introduction of the charge. +The water is then drawn off, and fresh water added. Four or five washings +are generally necessary. The nitro-glycerine is then run into the next +tank (A), the top of which is on a level with the bottom of the first one. +Across the top of this tank is stretched a frame of flannel, through which +the nitroglycerine has to filter. This removes any solid matters, such as +dirt or scum. Upon leaving this tank, it passes through a similar flannel +frame across another tank (B), and is finally drawn off by a tap in the +bottom of the tank into rubber buckets. The taps in these tanks are best +made of vulcanite. + +At this stage, a sample should be taken to the laboratory and tested. If +the sample will not pass the tests, which is often the case, the charge +must be rewashed for one hour, or some other time, according to the +judgment of the chemist in charge. In the case of an obstinate charge, it +is of much more avail to wash a large number of times with small +quantities of water, and for a short time, than to use a lot of water and +wash for half an hour. Plenty of compressed air should be used, as the +compound nitric ethers which are formed are thus got rid of. As five or +six charges are often in this house at one time, it is necessary to have +as many tanks arranged in tiers, otherwise one or two refractory charges +would stop the nitrating house and the rest of the nitro-glycerine plant. +The chief causes of the washed material not passing the heat test are, +either that the acids were not clean, or they contained objectionable +impurities, or more frequently, the quality of the glycerine used. The +glycerine used for making nitro-glycerine should conform to the following +tests, some of which, however, are of greater importance than others. The +glycerine should-- + +1. Have minimum specific gravity at 15 deg. C. of 1.261. + +2. Should nitrify well. + +3. Separation should be sharp within half an hour, without the separation +of flocculent matter, nor should any white flocculent matter (due to fatty +acids) be formed when the nitrated glycerine is thrown into water and +neutralised with carbonate of soda. + +4. Should be free from lime and chlorine, and contain only traces of +arsenic, sulphuric acid, &c. + +5. Should not leave more than 0.25 per cent. of inorganic and organic +residue together when evaporated in a platinum dish without ebullition +(about 160 deg. C.) or partial decomposition. + +6. Silver test fair. + +7. The glycerine, when diluted one-half, should give no deposit or +separation of fatty acids when nitric peroxide gas is passed through it. +(Nos. 1, 2, 3, and 5 are the most essential.) + +The white flocculent matter sometimes formed is a very great nuisance, and +any sample of glycerol which gives such a precipitate when tried in the +laboratory should at once be rejected, as it will give no end of trouble +in the separating house, and also in the filter house, and it will be very +difficult indeed to make the nitro-glycerine pass the heat test. The out- +turn of nitro-glycerine also will be very low. The trouble will show +itself chiefly in the separating operation. Very often 2 or 3 inches will +rise to the surface or hang about in the nitro-glycerine, and at the point +of contact between it and the mixed acids, and will afterwards be very +difficult to get rid of by filtration. The material appears to be partly +an emulsion of the glycerine, and partly due to fatty acids, and as there +appears to be no really satisfactory method of preventing its formation, +or of getting rid of it, the better plan is not to use any glycerine for +nitrating that has been found by experiment upon the laboratory scale to +give this objectionable matter. One of the most useful methods of testing +the glycerine, other than nitrating, is to dilute the sample one-half with +water, and then to pass a current of nitric peroxide gas through it, when +a flocculent precipitate of elaidic acid (less soluble in glycerine than +the original oleic acid) will be formed. Nitrogen peroxide, N_{2}O_{4}, is +best obtained by heating dry lead nitrate (see Allen, "Commercial Organic +Analysis," vol. ii., 301). + +When a sample of nitro-glycerine is brought to the laboratory from the +filter house, it should first be examined to see that it is not acid.[A] A +weak solution of Congo red or methyl orange may be used. If it appears to +be decidedly alkaline, it should be poured into a separating funnel, and +shaken with a little distilled water. This should be repeated, and the +washings (about 400 c.c.) run into a beaker, a drop of Congo red or methyl +orange added, and a drop or so of N/2 hydrochloric acid added, when it +should give, with two or three drops at most, a blue colour with the Congo +red, or pink with the methyl orange, &c. The object of this test is to +show that the nitro-glycerine is free from any excess of soda, i.e., that +the soda has been properly washed out, otherwise the heat test will show +the sample to be better than it is. The heat test must also be applied. + +[Footnote A: A. Leroux, _Bul. Soc. Chim. de Bel._, xix., August 1905, +contends that experience does not warrant the assumption that free acid is +a source of danger in nitro-glycerine or nitro-cellulose; free alkali, he +states, promotes their decomposition.] + +Upon leaving the filter house, where it has been washed and filtered, and +has satisfactorily passed the heat test, it is drawn off from the lowest +tank in indiarubber buckets, and poured down the conduit leading to the +precipitating house, where it is allowed to stand for a day, or sometimes +longer, in order to allow the little water it still contains to rise to +the surface. In order to accomplish this, it is sufficient to allow it to +stand in covered-in tanks of a conical form, and about 3 or 4 feet high. +In many works it is previously filtered through common salt, which of +course absorbs the last traces of water. It is then of a pale yellow +colour, and should be quite clear, and can be drawn off by means of a tap +(of vulcanite), fixed at the bottom of the tanks, into rubber buckets, and +is ready for use in the preparation of dynamite, or any of the various +forms of gelatine compounds, smokeless powders, &c., such as cordite, +ballistite, and many others. + +Mikolajezak (_Chem. Zeit._, 1904, Rep. 174) states that he has prepared +mono- and di-nitro-glycerine, and believes that the latter compound will +form a valuable basis for explosives, as it is unfreezable. It is stated +to be an odourless, unfreezable oil, less sensitive to percussion, +friction, and increase of temperature, and to possess a greater solvent +power for collodion-cotton than ordinary nitro-glycerine. It can thus be +used for the preparation of explosives of high stability, which will +maintain their plastic nature even in winter. The di-nitro-glycerine is a +solvent for tri-nitro-glycerine, it can therefore be mixed with this +substance, in the various gelatine explosives in order to lower the +freezing point. + +~The Waste Acids.~--The waste acids from the separating house, from which +the nitro-glycerine has been as completely separated as possible, are run +down the conduit to the secondary separator, in order to recover the last +traces of nitro-glycerine that they contain. The composition of the waste +acids is generally somewhat as follows:--Specific gravity, 1.7075 at 15 deg. +C.; sulphuric acid, 67.2 per cent.; nitric acid, 11.05 per cent.; and +water, 21.7 per cent., with perhaps as much as 2 per cent. of nitric +oxide, and of course varying quantities of nitro-glycerine, which must be +separated, as it is impossible to run this liquid away (unless it can be +run into the sea) or to recover the acids by distillation as long as it +contains this substance. The mixture, therefore, is generally run into +large circular lead-lined tanks, covered in, and very much like the +nitrating apparatus in construction, that is, they contain worms coiled +round inside, to allow of water being run through to keep the mixture +cool, and a compressed air pipe, in order to agitate the mixture if +necessary. The top also should contain a window, in order to allow of the +interior being seen, and should have a leaden chimney to carry off the +fumes which may arise from decomposition. It is also useful to have a +glass tube of 3 or 4 inches in diameter substituted for about a foot of +the lead chimney, in order that the man on duty can at any time see the +colour of the fumes arising from the liquid. There should also be two +thermometers, one long one reaching to the bottom of the tank, and one to +just a few inches below the surface of the liquid. + +The nitro-glycerine, of course, collects upon the surface, and can be +drawn off by a tap placed at a convenient height for the purpose. The +cover of the tank is generally conical, and is joined to a glass cylinder, +which is cemented to the top of this lead cover, and also to the lead +chimney. In this glass cylinder is a hole into which fits a ground glass +stopper, through which the nitro-glycerine can be drawn off. There will +probably never be more than an inch of nitro-glycerine at the most, and +seldom that. It should be taken to the filter house and treated along with +another charge. The acids themselves may either be run to waste, or better +treated by some denitration plant. This house probably requires more +attention than any other in the danger area, on account of the danger of +the decomposition of the small quantities of nitro-glycerine, which, as it +is mixed with such a large quantity of acids and water, is very apt to +become hot, and decomposition, which sets up in spots where a little +globule of nitro-glycerine is floating, surrounded by acids that gradually +get hot, gives off nitrous fumes, and perhaps explodes, and thus causes +the sudden explosion of the whole. The only way to prevent this is for the +workman in charge to look at the thermometers _frequently_, and at the +colour of the escaping fumes, and if he should notice a rise of +temperature or any appearance of red fumes, to turn on the water and air, +and stir up the mixture, when probably the temperature will suddenly fall, +and the fumes cease to come off. + +The cause of explosions in this building is either the non-attention of +the workmen in charge, or the bursting of one of the water pipes, by which +means, of course, the water, finding its way into the acids, causes a +sudden rise of temperature. If the latter of these two causes should +occur, the water should at once be shut off and the air turned on full, +but if it is seen that an explosion is likely to occur, the tank should at +once be emptied by allowing its contents to run away into a drowning tank +placed close outside the house, which should be about 4 feet deep, and +some 16 feet long by 6 feet wide; in fact, large enough to hold a +considerable quantity of water. But this last course should only be +resorted to as a last extremity, as it is extremely troublesome to recover +the small quantity of nitro-glycerine from the bottom of this tank, which +is generally a bricked and cemented excavation some few yards from the +house. + +It has been proposed to treat these waste acids, containing nitro- +glycerine, in Mr M. Prentice's nitric acid retort. In this case they would +be run into the retort, together with nitrate of soda, in a fine stream, +and the small quantity of nitro-glycerine, coming into contact with the +hot mixture already in the retort, would probably be at once decomposed. +This process, although not yet tried, promises to be a success. Several +processes have been used for the denitration of these acids. + +~Treatment of the Waste Acid from the Manufacture of Nitro-Glycerine and +Gun-Cotton.~--The composition of these acids is as follows:-- + + Nitro-glycerine and Gun-cotton + Waste Acid. + +Sulphuric acid 70 per cent. 78 per cent. +Nitric acid 10 " 12 " +Water 20 " 10 " + +The waste acid from the manufacture of gun-cotton is generally used direct +for the manufacture of nitric acid, as it contains a fairly large amount +of sulphuric acid, and the small amount of nitro-cellulose which it also +generally contains decomposes gradually and without explosion in the +retort. Nitric acid may be first distilled off, the resulting sulphuric +acid being then added to the equivalent amount of nitrate of soda. Nitric +acid is then distilled over and condensed in the usual way. Very often, +however, the waste acid is added direct to the charge of nitrate without +previously eliminating the nitric acid. The treatment of the waste acid +from the manufacture of nitro-glycerine is somewhat different. The small +amount of nitro-glycerine in this acid must always be eliminated. This is +effected either by allowing the waste acid to stand for at least twenty- +four hours in a big vessel with a conical top, where all the nitro- +glycerine which will have separated to the surface is removed by skimming; +or, better still, the "watering down process" of Col. Nathan may be +employed. In Nathan's nitrator every existing trace of nitro-glycerine is +separated from the acids in a few hours after the nitration, and any +further formation of nitro-glycerine is prevented by adding about 2 per +cent. of water to the waste acids, which are kept agitated during the +addition. The waste acid, now free from nitro-glycerine, but which may +still contain organic matter, is denitrated by bringing it into contact +with a jet of steam. The waste acid is passed in a small stream down +through a tower of acid-resisting stoneware (volvic stone), which is +closely packed with earthenware, and at the bottom of which is the steam +jet. Decomposition proceeds as the acid meets the steam, nitric and +nitrous acids are disengaged and are passed out at the top of the tower +through a pipe to a series of condensers and towers, where the nitric acid +is collected. The nitrous acid may be converted into nitric acid by +introducing a hot compressed air jet into the gases before they pass into +the condensers. Weak sulphuric acid of sp. gr. 1.6 collects in a saucer in +which the tower stands, and is then passed through a cooling worm. The +weak sulphuric acid, now entirely free from nitric and nitrous acids, may +be concentrated to sp. gr. 1.842 and 96 per cent. H_{2}SO_{4} by any of +the well-known processes, e.g., Kessler, Webb, Benker, Delplace, &c., and +it may be used again in the manufacture of nitro-glycerine or gun-cotton. + +Two points in the manufacture of nitro-glycerine are of the greatest +importance, viz., the purity of the glycerine used, and the strength and +purity of the acids used in the nitration. With regard to the first of +these, great care should be taken, and a complete analysis and thorough +examination, including a preliminary experimental nitration, should always +be instituted. As regards the second, the sulphuric acid should not only +be strong (96 per cent.), but as free from impurities as possible. With +the nitric acid, which is generally made at the explosive works where it +is used, care must be taken that it is as strong as possible (97 per cent. +and upwards). This can easily be obtained if the plant designed by Mr +Oscar Guttmann[A] is used. Having worked Mr Guttmann's plant for some +time, I can testify as to its value and efficiency. + +[Footnote A: "The Manufacture of Nitric Acid," _Jour. Soc. Chem. Ind._, +March 1893.] + +Another form of nitric acid plant, which promises to be of considerable +service to the manufacturer of nitric acid for the purpose of nitrating, +is the invention of the late Mr Manning Prentice, of Stowmarket. Through +the kindness of Mr Prentice, I visited his works to see the plant in +operation. It consists of a still, divided into compartments or chambers +in such a manner that the fluid may pass continuously from one to the +other. The nitric acid being continuously separated by distillation, the +contents of each division vary--the first containing the full proportion +of nitric acid, and each succeeding one less of the nitric acid, until +from the overflow of the last one the bisulphate of soda flows away +without any nitric acid. The nitrate of soda is placed in weighed +quantities in the hopper, whence it passes to the feeder. The feeder is a +miniature horizontal pug-mill, which receives the streams of sulphuric +acid and of nitrate, and after thoroughly mixing them, delivers them into +the still, where, under the influence of heat, they rapidly become a +homogeneous liquid, from which nitric acid continuously distils. + +Mr Prentice says: "I may point out that while the ordinary process of +making nitric acid is one of fractional distillation by time, mine is +fractional distillation by space." "Instead of the operation being always +at the same point of space, but differing by the successive points of +time, I arrange for the differences to take place at different points of +space, and these differences exist at one and the same points of time." It +is possible with this plant to produce the full product of nitric acid of +a gravity of 1.500, or to obtain the acid of varying strengths from the +different still-heads. One of these stills, capable of producing about 4 +tons of nitric acid per week, weighs less than 2 tons. It is claimed that +there is by their use a saving of more than two-thirds in fuel, and four- +fifths in condensing plant. Further particulars and illustrations will be +found in Mr Prentice's paper (_Journal of the Society of Chemical +Industry_, 1894, p. 323). + + + + +CHAPTER III. + +_NITRO-CELLULOSE, &c._ + +Cellulose Properties--Discovery of Gun-Cotton--Properties of Gun-Cotton-- +Varieties of Soluble and Insoluble Gun-Cottons--Manufacture of Gun-Cotton-- +Dipping and Steeping--Whirling out the Acid--Washing--Boiling--Pulping-- +Compressing--The Waltham Abbey Process--Le Bouchet Process--Granulation of +Gun-Cotton--Collodion-Cotton--Manufacture--Acid Mixture used--Cotton used, +&c.--Nitrated Gun-Cotton--Tonite--Dangers in Manufacture of Gun-Cotton-- +Trench's Fire-Extinguishing Compound--Uses of Collodion-Cotton--Celluloid-- +Manufacture, &c.--Nitro-Starch, Nitro-Jute, and Nitro-Mannite. + + +~The Nitro-Celluloses.~--The substance known as cellulose forms the +groundwork of vegetable tissues. The cellulose of the woody parts of +plants was at one time supposed to be a distinct body, and was called +lignine, but they are now regarded as identical. The formula of cellulose +is (C_{6}H_{10}O_{6})_{X}, and it is generally assumed that the molecular +formula must be represented by a multiple of the empirical formula, +C_{12}H_{20}O_{10} being often regarded as the minimum. The assumption is +based on the existence of a penta-nitrate and the insoluble and colloidal +nature of cellulose. Green (_Zeit. Farb. Text. Ind._, 1904, 3, 97) +considers these reasons insufficient, and prefers to employ the single +formula C_{6}H_{10}O_{5}. Cellulose can be extracted in the pure state, +from young and tender portions of plants by first crushing them, to +rupture the cells, and then extracting with dilute hydrochloric acid, +water, alcohol, and ether in succession, until none of these solvents +remove anything more. Fine paper or cotton wool yield very nearly pure +cellulose by similar treatment. + +Cellulose is a colourless, transparent mass, absolutely insoluble in +water, alcohol, or ether. It is, however, soluble in a solution of +cuprammoniac solution, prepared from basic carbonate or hydrate of copper +and aqueous ammonia. The specific gravity of cellulose is 1.25 to 1.45. +According to Schulze, its elementary composition is expressed by the +percentage numbers:-- + +Carbon 44.0 per cent. 44.2 per cent. +Hydrogen 6.3 " 6.4 " +Oxygen 49.7 " 49.4 " + +These numbers represent the composition of the ash free cellulose. Nearly +all forms of cellulose, however, contain a small proportion of mineral +matters, and the union of these with the organic portion of the fibre or +tissue is of such a nature that the ash left on ignition preserves the +form of the original. "It is only in the growing point of certain young +shoots that the cellulose tissue is free from mineral constituents" +(Hofmeister). + +Cellulose is a very inert body. Cold concentrated sulphuric acid causes it +to swell up, and finally dissolves it, forming a viscous solution. +Hydrochloric acid has little or no action, but nitric acid has, and forms +a series of bodies known as nitrates or nitro-celluloses. Cellulose has +some of the properties of alcohols, among them the power of forming +ethereal salts with acids. When cellulose in any form, such as cotton, is +brought into contact with strong nitric acid at a low temperature, a +nitrate or nitro product, containing nitryl, or the NO_{2} group, is +produced. The more or less complete replacement of the hydroxylic hydrogen +by NO_{2} groups depends partly on the concentration of the nitric acid +used, partly on the duration of the action. If the most concentrated +nitric and sulphuric acids are employed, and the action allowed to proceed +for some considerable time, the highest nitrate, known as hexa-nitro- +cellulose or gun-cotton, C_{12}H_{14}O_{4}(O.NO_{2})_{6}, will be formed; +but with weaker acids, and a shorter exposure to their action, the tetra +and penta and lower nitrates will be formed.[A] + +[Footnote A: The paper by Prof. Lunge, _Jour. Amer. Chem. Soc._, 1901, +23[8], 527-579, contains valuable information on this subject.] + +Besides the nitrate, A. Luck[A] has proposed to use other esters of +cellulose, such as the acetate, benzoate, or butyrate. It is found that +cellulose acetate forms with nitro-glycerine a gelatinous body without +requiring the addition of a solvent. A sporting powder is proposed +composed of 75 parts of cellulose nitrate (13 per cent. N.) mixed with 13 +parts of cellulose acetate. + +[Footnote A: Eng. Pat. 24,662, 22nd November 1898.] + +The discovery of gun-cotton is generally attributed to Schoenbein (1846), +but Braconnot (in 1832) had previously nitrated starch, and six years +later Pelouse prepared nitro-cotton and various other nitro bodies, and +Dumas nitrated paper, but Schoenbein was apparently the first chemist to +use a mixture of strong nitric and sulphuric acids. Many chemists, such as +Piobert in France, Morin in Russia, and Abel in England, studied the +subject; but it was in Austria, under the auspices of Baron Von Lenk, that +the greatest progress was made. Lenk used cotton in the form of yarn, made +up into hanks, which he first washed in a solution of potash, and then +with water, and after drying dipped them in the acids. The acid mixture +used consisted of 3 parts by weight of sulphuric to 1 part of nitric acid, +and were prepared some time before use. The cotton was dipped one skein at +a time, stirred for a few minutes, pressed out, steeped, and excess of +acid removed by washing with water, then with dilute potash, and finally +with water. Von Lenk's process was used in England at Faversham (Messrs +Hall's Works), but was given up on account of an explosion (1847). + +Sir Frederick Abel, working at Stowmarket and Waltham Abbey, introduced +several very important improvements into the process, the chief among +these being pulping. Having traced the cause of its instability to the +presence of substances caused by the action of the nitric acid on the +resinous or fatty substances contained in the cotton fibre, he succeeded +in eliminating them, by boiling the nitro-cotton in water, and by a +thorough washing, after pulping the cotton in poachers. + +Although gun-cottons are generally spoken of as nitro-celluloses, they are +more correctly described as cellulose nitrates, for unlike nitro bodies of +other series, they do not yield, or have not yet done so, amido bodies, on +reduction with nascent hydrogen.[A] The equation of the formation of +gun-cotton is as follows:-- + +2(C_{6}H_{10}O_{5}) + 6HNO_{3} = C_{12}H_{14}O_{4}(NO_{3})_{6} + 6OH_{2}. + Cellulose. Nitric Acid. Gun-Cotton. Water. + +The sulphuric acid used does not take part in the reaction, but its +presence is absolutely essential to combine with the water set free, and +thus to prevent the weakening of the nitric acid. The acid mixture used at +Waltham Abbey consists of 3 parts by weight of sulphuric acid of 1.84 +specific gravity, and 1 part of nitric acid of 1.52 specific gravity. The +same mixture is also used at Stowmarket (the New Explosive Company's +Works). The use of weaker acids results in the formation of collodion- +cotton and the lower nitrates generally. + +[Footnote A: "Cellulose," by Cross and Bevan, ed. by W.R. Hodgkinson, p. +9.] + +The nitrate which goes under the name of gun-cotton is generally supposed +to be the hexa-nitrate, and to contain 14.14 per cent. of nitrogen; but a +higher percentage than 13.7 has not been obtained from any sample. It is +almost impossible (at any rate upon the manufacturing scale) to make pure +hexa-nitro-cellulose or gun-cotton; it is certain to contain several per +cents. of the soluble forms, i.e., lower nitrates. It often contains as +much as 15 or 16 per cent., and only from 13.07[A] to 13.6 per cent. of +nitrogen. + +[Footnote A: Mr J.J. Sayers, in evidence before the court in the "Cordite +Case," says he found 15.2 and 16.1 per cent. soluble cotton, and 13.07 and +13.08 per cent. nitrogen in two samples of Waltham Abbey gun-cotton.] + +A whole series of nitrates of cellulose are supposed to exist, the highest +member being the hexa-nitrate, and the lowest the mono-nitrate. Gun-cotton +was at one time regarded as the tri-nitrate, and collodion-cotton as the +di-nitrate and mono-nitrate, their respective formula being given as +follows:-- + +Mono-nitro-cellulose C_{6}H_{9}(NO_{2})O_{5} = 6.763 per cent. nitrogen. +Di-nitro-cellulose C_{6}H_{8}(NO_{2})_{2}O_{5} = 11.11 " " +Tri-nitro-cellulose C_{6}H_{7}(NO_{2})_{3}O_{5} = 14.14 " " + +But gun-cotton is now regarded as the hexa-nitrate, and collodion-cotton +as a mixture of all the other nitrates. In fact, chemists are now more +inclined to divide nitro-cellulose into the soluble and insoluble forms, +the reason being that it is quite easy to make a nitro-cellulose entirely +soluble in a mixture of ether-alcohol, and yet containing as high a +percentage of nitrogen as 12.6; whereas the di-nitrate[A] should +theoretically only contain 11.11 per cent. On the other hand, it is not +possible to make gun-cotton with a higher percentage of nitrogen than +about 13.7, even when it does not contain any nitro-cotton that is soluble +in ether-alcohol.[B] The fact is that it is not at present possible to +make a nitro-cellulose which shall be either entirely soluble or entirely +insoluble, or which will contain the theoretical content of nitrogen to +suit any of the above formulae for the cellulose nitrates. Prof. G. Lunge +gives the following list of nitration products of cellulose:-- + +[Footnote A: The penta-nitrate C_{12}H_{15}O_{5}(NO_{3})_{5} = 12.75 per +cent. nitrogen.] + +[Footnote B: In the Cordite Trial (1894) Sir F.A. Abel said, "Before 1888 +there was a broad distinction between soluble and insoluble nitro- +cellulose, collodion-cotton being soluble (in ether-alcohol) and +gun-cotton insoluble." Sir H.E. Roscoe, "That he had been unable to make a +nitro-cotton with a higher nitrogen content than 13.7." And Professor G. +Lunge said, "Gun-cotton always contained soluble cotton, and _vice +versa_." These opinions were also generally confirmed by Sir E. Frankland, +Sir W. Crookes, Dr Armstrong, and others.] + +Dodeca-nitro-cellulose C_{24}H_{28}O_{20}(NO_{2})_{12} = 14.16 per cent. + nitrogen. (= old tri-nitro-cellulose) +Endeca-nitro-cellulose C_{24}H_{29}O_{20}(NO_{2})_{11} = 13.50 per cent. + nitrogen. +Deca-nitro-cellulose C_{24}H_{30}O_{20}(NO_{2})_{10} = 12.78 per cent. + nitrogen. +Ennea-nitro-cellulose C_{24}H_{31}O_{20}(NO_{2})_{9} = 11.98 per cent. + nitrogen. +Octo-nitro-cellulose C_{24}H_{32}O_{20}(NO_{2})_{8} = 11.13 per cent. + nitrogen. (= old di-nitro-cellulose) +Hepta-nitro-cellulose C_{24}H_{33}O_{20}(NO_{2})_{7} = 10.19 per cent. + nitrogen. +Hexa-nitro-cellulose C_{24}H_{34}O_{20}(NO_{2})_{6} = 9.17 per cent. + nitrogen. +Penta-nitro-cellulose C_{24}H_{35}O_{20}(NO_{2})_{5} = 8.04 per cent. + nitrogen. +Tetra-nitro-cellulose C_{24}H_{36}O_{20}(NO_{2})_{4} = 6.77 per cent. + nitrogen. (= old mono-nitro-cellulose) + +It is not unlikely that a long series of nitrates exists. It is at any +rate certain that whatever strength of acids may be used, and whatever +temperature or other conditions may be present during the nitration, that +the product formed always consists of a mixture of the soluble and +insoluble nitro-cellulose. + +Theoretically 100 parts of cotton by weight should produce 218.4 parts of +gun-cotton, but in practice the yield is a good deal less, both in the +case of gun-cotton or collodion-cotton. In speaking of soluble and +insoluble nitro-cellulose, it is their behaviour, when treated with a +solution consisting of 2 parts ether and 1 of alcohol, that is referred +to. There is, however, another very important difference, and that is +their different solubility in nitro-glycerine. The lower nitrates or +soluble form is soluble in nitro-glycerine under the influence of heat, a +temperature of about 50 deg. C. being required. At lower temperatures the +dissolution is very imperfect indeed; and after the materials have been +left in contact for days, the threads of the cotton can still be +distinguished. The insoluble form or gun-cotton is entirely _insoluble_ in +nitro-glycerine. It can, however, be made to dissolve[A] by the aid of +acetone or acetic ether. Both or rather all the forms of nitro-cellulose +can be dissolved in acetone or acetic ether. They also dissolve in +concentrated sulphuric acid, and the penta-nitrate in nitric acid at about +80 deg. or 90 deg. C. + +[Footnote A: Or rather to form a transparent jelly.] + +The penta-nitrate may be obtained in a pure state by the following +process, devised by Eder:--The gun-cotton is dissolved in concentrated +nitric acid at 90 deg. C., and reprecipitated by the addition of concentrated +sulphuric acid. After cooling to 0 deg. C., and mixing with a larger volume of +water, the precipitated nitrate is washed with water, then with alcohol, +dissolved in ether-alcohol, and again precipitated with water, when it is +obtained pure. This nitrate is soluble in ether-alcohol, and slightly in +acetic acid, easily in acetone, acetic ether, and methyl-alcohol, +insoluble in alcohol. Strong potash (KOH) solution converts into the +di-nitrate C_{12}H_{18}O_{8}(NO_{3})_{2}. The hexa-nitrate is not soluble +in acetic acid or methyl-alcohol. + +The lower nitrates known as the tetra- and tri-nitrates are formed +together when cellulose is treated with a mixture of weak acids, and +allowed to remain in contact with them for a very short time (twenty +minutes). They cannot be separated from one another, as they all dissolve +equally in ether-alcohol, acetic ether, acetic acid, methyl-alcohol, +acetone, amyl acetate, &c. + +As far as the manufacture of explosive bodies is concerned, the two forms +of nitro-cellulose used and manufactured are gun-cotton or the hexa- +nitrate (once regarded as tri-nitro-cellulose), which is also known as +insoluble gun-cotton, and the soluble form of gun-cotton, which is also +known as collodion, and consists of a mixture of several of the lower +nitrates. It is probable that it chiefly consists, however, of the next +highest nitrate to gun-cotton, as the theoretical percentage of nitrogen +for this body,. the penta-nitrate, is 12.75 per cent., and analyses of +commercial collodion-cotton, entirely soluble in ether-alcohol, often give +as high a percentage as 12.6. + +We shall only describe the manufacture of the two forms known as soluble +and insoluble, and shall refer to them under their better known names of +gun-cotton and collodion-cotton. The following would, however, be the +formulae[A] and percentage of nitrogen of the complete series:-- + +Hexa-nitro-cellulose C_{12}H_{14}O_{4}(NO_{3})_{6} 14.14 per cent. + nitrogen. +Penta-nitro-cellulose C_{12}H_{15}O_{5}(NO_{3})_{5} 12.75 per cent. + nitrogen. +Tetra-nitro-cellulose C_{12}H_{16}O_{6}(NO_{3})_{4} 11.11 per cent. + nitrogen. +Tri-nitro-cellulose C_{12}H_{17}O_{7}(NO_{3})_{3} 9.13 per cent. + nitrogen. +Di-nitro-cellulose C_{12}H_{18}O_{8}(NO_{3})_{2} 7.65 per cent. + nitrogen. +Mono-nitrocellulose C_{12}H_{19}O_{9}(NO_{3}) 3.80 per cent. + nitrogen. + +[Footnote A: Berthelot takes C_{24}H_{40}O_{20} as the formula of +cellulose; and M. Vieille regards the highest nitrate as +(C_{24}H_{18}(NO_{3}H)_{11}O_{9}). _Compt. Rend._, 1882, p. 132.] + +~Properties of Gun-Cotton.~--The absolute density of gun-cotton is 1.5. +When in lumps its apparent density is 0.1; if twisted into thread, 0.25; +when subjected, in the form of pulp, to hydraulic pressure, 1.0 to 1.4. +Gun-cotton preserves the appearance of the cotton from which it is made. +It is, however, harsher to the touch; it is only slightly hygroscopic (dry +gun-cotton absorbs 2 per cent. of moisture from the air). It possesses the +property of becoming electrified by friction. It is soluble in acetic +ether, amyl acetate, and acetone, insoluble in water, alcohol, ether, +ether-alcohol, methyl-alcohol, &c. It is very explosive, and is ignited by +contact with an ignited body, or by shock, or when it is raised to a +temperature of 172 deg. C. It burns with a yellowish flame, almost without +smoke, and leaves little or no residue. The volume of the gases formed is +large, and consists of carbonic acid, carbonic oxide, nitrogen, and water +gas. Compressed gun-cotton when ignited often explodes when previously +heated to 100 deg. C. + +Gun-cotton kept at 80 deg. to 100 deg. C. decomposes slowly, and sunlight causes +it to undergo a slow decomposition. It can, however, be preserved for +years without undergoing any alteration. It is very susceptible to +explosions by influence. For instance, a torpedo, even placed at a long +distance, may explode a line of torpedoes charged with gun-cotton. The +velocity of the propagation of the explosion in metallic tubes filled with +pulverised gun-cotton has been found to be from 5,000 to 6,000 mms. per +second in tin tubes, and 4,000 in leaden tubes (Sebert). + +Gun-cotton loosely exposed in the open air burns eight times as quickly as +powder (Piobert). A thin disc of gun-cotton may be fired into from a rifle +without explosion; but if the thickness of the disc be increased, an +explosion may occur. The effect of gun-cotton in mines is very nearly the +same as that of dynamite for equal weights. It requires, however, a +stronger detonator, and it gives rise to a larger quantity of carbonic +oxide gas. Gun-cotton should be neutral to litmus, and should stand the +Government heat test--temperature of 150 deg. F. for fifteen minutes (see page +249). In the French Navy gun-cotton is submitted to a heat test of 65 deg. C. +(= 149 deg. F.) for eleven minutes. It should contain as small a percentage of +soluble nitro-cotton and of non-nitrated cotton as possible. + +The products of perfectly detonated gun-cotton may be expressed by the +following equation:-- + +2C_{12}H_{14}O_{4}(NO_{3})_{6} = 18CO + 6CO_{2} + 14H_{2}O + 12N. + +It does not therefore contain sufficient oxygen for the complete +combustion of its carbon. It is for this reason that when used for mining +purposes a nitrate is generally added to supply this defect (as, for +instance, in tonite). It tends also to prevent the evolution of the +poisonous gas, carbonic oxide. The success of the various gelatine +explosives is due to this fact, viz., that the nitro-glycerine has an +excess of oxygen, and the nitro-cotton too little, and thus the two +explosives help one another. + +In practice the gases resulting from the explosion of gun-cotton are-- +Carbonic oxide, 28.55; carbonic acid, 19.11; marsh gas (CH_{4}), 11.17; +nitric oxide, 8.83; nitrogen, 8.56; water vapour, 21.93 per cent. The late +Mr E.O. Brown, of Woolwich Arsenal, discovered that perfectly wet and +uninflammable compressed gun-cotton could be easily detonated by the +detonation of a priming charge of the dry material in contact with it. +This rendered the use of gun-cotton very much safer for use as a military +or mining explosive. + +As a mining explosive, however, gun-cotton is now chiefly used under the +form of tonite, which is a mixture of half gun-cotton and half barium +nitrate. This material is sometimes spoken of as "nitrated gun-cotton." +The weight of gun-cotton required to produce an equal effect either in +heavy ordnance or in small arms is to the weight of gunpowder in the +proportion of 1 to 3, i.e., an equal weight of gun-cotton would produce +three times the effect of gunpowder. Its rapidity of combustion, however, +requires to be modified for use in firearms. Hence the lower nitrates are +generally used, or such compounds as nitro-lignose, nitrated wood, &c., +are used. + +The initial pressure produced by the explosion of gun-cotton is very +large, equal to 18,135 atmospheres, and 8,740 kilogrammes per square +centimetre for 1 kilo., the heat liberated being 1,075 calories (water +liquid), or 997.7 cals. (water gaseous), but the quantity of heat +liberated changes with the equation of decomposition. According to +Berthelot,[A] the heat of formation of collodion-cotton is 696 cals. for +1,053 grms., or 661 cals. for 1 kilo. The heat liberated in the total +combustion of gun-cotton by free oxygen at constant pressure is 2,633 +cals. for 1,143 grms., or for 1 kilo. gun-cotton 2,302 cals. (water +liquid), or 2,177 cals. (water gaseous). The heat of decomposition of gun- +cotton in a closed vessel, found by experiment at a low density of charge +(0.023), amounts to 1,071 cals. for 1 kilo. of the substance, dry and free +from ash. To obtain the maximum effect of gun-cotton it must be used in a +compressed state, for the initial pressures are thereby increased. Wet +gun-cotton s much less sensitive to shock than dry. Paraffin also reduces +its liability to explode, so also does camphor. + +[Footnote A: "Explosives and their Power," trans. by Hake and M'Nab.] + +The substance known as celluloid, a variety of nitro-cellulose nearly +corresponding to the formula C_{24}H_{24}(NO_{3}H)_{8}O_{12}, to which +camphor and various inert substances are added, so as to render it +non-sensitive to shock, may be worked with tools, and turned in the lathe +in the same manner as ivory, instead of which material celluloid is now +largely used for such articles as knife handles, combs, &c. Celluloid is +very plastic when heated towards 150 deg. C., and tends to become very +sensitive to shock, and in large quantities might become explosive during +a fire, owing to the general heating of the mass, and the consequent +evaporation of the camphor. When kept in the air bath at 135 deg. C., +celluloid decomposes quickly. In an experiment (made by M. Berthelot) in a +closed vessel at 135 deg. C., and the density of the charge being 0.4, it +ended in exploding, developing a pressure of 3,000 kilos. A large package +of celluloid combs also exploded in the guard's van on one of the German +railways a few years ago. Although it is not an explosive under ordinary +circumstances, or even with a powerful detonator, considerable care should +be exercised in its manufacture. + +~The Manufacture of Gun-Cotton.~--The method used for the manufacture of +gun-cotton is that of Abel (Spec. No. 1102, 20. 4. 65). It was worked out +chiefly at Stowmarket[A] and Waltham Abbey,[B] but has in the course of +time undergone several alterations. These modifications have taken place, +however, chiefly upon the Continent, and relate more to the apparatus and +machinery used than to any alteration in the process itself. The form of +cellulose used is cotton-waste,[C] which consists of the clippings and +waste material from cotton mills. After it has been cleaned and purified +from grease, oil, and other fatty substances by treatment with alkaline +solutions, it is carefully picked over, and every piece of coloured cotton +rag or string carefully removed. The next operation to which it is +submitted has for its object the opening up of the material. For this +purpose it is put through a carding machine, and afterwards through a +cutting machine, whereby it is reduced to a state suitable for its +subsequent treatment with acids, that is, it has been cut into short +lengths, and the fibres opened up and separated from one another. + +[Footnote A: The New Explosive Co. Works.] + +[Footnote B: Royal Gunpowder Factory.] + +[Footnote C: Costs from L10 to L25 a ton. In his description of the +"Preparation of Cotton-waste for the Manufacture of Smokeless Powder," A. +Hertzog states that the German military authorities require a cotton which +when thrown into water sinks in two minutes; when nitrated, does not +disintegrate; when treated with ether, yields only 0.9 per cent. of fat; +and containing only traces of chlorine, lime, magnesia, iron, sulphuric +acid, and phosphoric acid. If the cotton is very greasy, it must be first +boiled with soda-lye under pressure, washed, bleached with chlorine, +washed, treated with sulphuric acid or HCl, again washed, centrifugated, +and dried; if very greasy indeed a preliminary treatment with lime-water +is desirable. See also "Inspection of Cotton-Waste for Use in the +Manufacture of Gun-cotton," by C.E. Munro, _Jour. Am. Chem. Soc._, 1895, +17, 783.] + +~Drying the Cotton.~--This operation is performed in either of two ways. +The cotton may either be placed upon shelves in a drying house, through +which a current of hot air circulates, or dried in steam-jacketed +cylinders. It is very essential that the cotton should be as dry as +possible before dipping in the acids, especially if a wholly "insoluble" +nitro-cellulose is to be obtained. After drying it should not contain more +than 0.5 per cent. of moisture, and less than this if possible. The more +general method of drying the cotton is in steam-jacketed tubes, i.e., +double cylinders of iron, some 5 feet long and 1-1/2 foot wide. The cotton +is placed in the central chamber (Fig. 10), while steam is made to +circulate in the surrounding jacket, and keeps the whole cylinder at a +high temperature (steam pipes may be coiled round the outside of an iron +tube, and will answer equally well). By means of a pipe which communicates +with a compressed air reservoir, a current of air enters at the bottom, +and finds its way up through the cotton, and helps to remove the moisture +that it contains. The raw cotton generally contains about 10 per cent. of +moisture and should be dried until it contains only 1/2 per cent. or less. +For this it will generally have to remain in the drying cylinder for about +five hours. At the end of that time a sample should be taken from the +_top_ of the cylinder, and dried in the water oven (100 deg. C.[A]) for an +hour to an hour and a half, and re-weighed, and the moisture then +remaining in it calculated. + +[Footnote A: It is dried at 180 deg. C. at Waltham Abbey, in a specially +constructed drying chamber.] + +[Illustration: FIG. 10.--COTTON DRIER.] + +It is very convenient to have a large copper water oven, containing a lot +of small separate compartments, large enough to hold about a handful of +the cotton, and each compartment numbered, and corresponding to one of the +drying cylinders. The whole apparatus should be fixed against the wall of +the laboratory, and may be heated by bringing a small steam pipe from the +boiler-house. It is useful to have a series of copper trays, about 3 +inches by 6 inches, numbered to correspond to the divisions in the steam +oven, and exactly fitting them. These trays can then be taken by a boy to +the drying cylinders, and a handful of the cotton from each placed in +them, and afterwards brought to the laboratory and weighed (a boy can do +this very well), placed in their respective divisions of the oven, and +left for one to one and a half hours, and re-weighed. + +When the cotton is found to be dry the bottom of the drying cylinder is +removed, and the cotton pushed out from the top by means of a piece of +flat wood fixed on a broom-handle. It is then packed away in galvanised- +iron air-tight cases, and is ready for the next operation. At some works +the cotton is dried upon shelves in a drying house through which hot air +circulates, the shelves being of canvas or of brass wire netting. The hot +air must pass under the shelves and through the cotton, or the process +will be a very slow one. + +~Dipping and Steeping.~--The dry cotton has now to be nitrated. This is +done by dipping it into a mixture of nitric and sulphuric acids. The acids +used must be strong, that is, the nitric acid must be at least of a +gravity of 1.53 to 1.52, and should contain as little nitric oxide as +possible. The sulphuric acid must have a specific gravity of 1.84 at 15 deg. +C., and contain about 97 per cent. of the mono-hydrate (H_{2}SO_{4}). In +fact, the strongest acids obtainable should be used when the product +required is gun-cotton, i.e., the highest nitrate. + +The sulphuric acid takes no part in the chemical reaction involved, but is +necessary in order to combine with the water that is liberated in the +reaction, and thus to maintain the strength of the nitric acid. The +reaction which takes place is the following:-- + +2(C_{6}H_{10}O_{5}) + 6HNO_{3} = C_{12}H_{14}(NO_{3})_{6} + 6 H_{2}O. + 324 378 = 594 108. + Cellulose. Gun-Cotton. + +Theoretically,[A] therefore, 1 part of cellulose should form 1.8 part of +gun-cotton. Practically, however, this is never obtained, and 1.6 lb. from +1 lb. of cellulose is very good working. The mixture of acids used is +generally 1 to 3, or 25 per cent. nitric acid to 75 per cent. sulphuric +acid. + +[Footnote A: (594 x 1)/324= 1.83.] + +[Illustration: FIG. 11.--TANK FOR DIPPING COTTON.] + +[Illustration: FIG. 12.--THE COOLING PITS.] + +The dipping is done in cast-iron tanks (Fig. 11), a series of which is +arranged in a row, and cooled by a stream of cold water flowing round +them. The tanks hold about 12 gallons, and the cotton is dipped in +portions of 1 lb. at a time. It is thrown into the acids, and the workman +moves it about for about three minutes with an iron rabble. At the end of +that time he lifts it up on to an iron grating, just above the acids, +fixed at the back of the tank, where by means of a movable lever he gently +squeezes it, until it contains about ten times its weight of acids (the 1 +lb. weighs 10 lbs.). It is then transferred to earthenware pots to steep. + +[Illustration: FIG. 13.--COTTON STEEPING POT.] + +~Steeping.~--The nitrated cotton, when withdrawn from the dipping tanks, +and still containing an excess of acids, is put into earthenware pots of +the shape shown in Figs. 12 and 13. The lid is put on, and the pots placed +in rows in large cooling pits, about a foot deep, through which a stream +of water is constantly flowing. These pits form the floor of the steeping +house. The cotton remains in these pots for a period of forty-eight hours, +and must be kept cool. Between 18 deg. and 19 deg. C. is the highest temperature +desirable, but the cooler the pots are kept the better. At the end of +forty-eight hours the chemical reaction is complete, and the cotton is or +should be wholly converted into nitro-cellulose; that is, there should be +no unnitrated cotton. + +[Illustration: FIG. 14.--HYDRO-EXTRACTOR.] + +~Whirling Out the Acid.~--The next operation is to remove the excess of +acid. This is done by placing the contents of two or three or more pots +into a centrifugal hydro-extractor (Fig. 14), making 1,000 to 1,500 +revolutions per minute. The hydro-extractor consists of a machine with +both an inner cylinder and an outer one, both revolving in concert and +driving outwardly the liquid to the chamber, from which it runs away by a +discharge pipe. The wet cotton is placed around the inner cone. The +cotton, when dry, is removed, and at once thrown into a large tank of +water, and the waste acids are collected in a tank.[A] + +[Footnote A: Care must be taken in hot weather that the gun-cotton does +not fire, as it does sometimes, directly the workman goes to remove it +after the machine is stopped. It occurs more often in damp weather. Dr +Schuepphaus, of Brooklyn, U.S.A., proposes to treat the waste acids from +the nitration of cellulose by adding to them sulphuric anhydride and +nitric acid. The sulphuric anhydride added converts the water liberated +from the cellulose into sulphuric acid.] + +~Washing.~--The cotton has now to be carefully washed. This is done in a +large wooden tank filled with water. If, however, a river or canal runs +through the works, a series of wooden tanks, the sides and bottoms of +which are pierced with holes, so as to allow of the free circulation of +water, should be sunk into a wooden platform that overhangs the surface of +the river in such a way that the tanks are immersed in the water, and of +course always full. During the time that the cotton is in the water a +workman turns it over constantly with a wooden paddle. A stream of water, +in the form of a cascade, should be allowed to fall into these tanks. The +cotton may then be thrown on to this stream of water, which, falling some +height, at once carries the cotton beneath the surface of the water. This +proceeding is necessary because the cotton still retains a large excess of +strong acids, and when mixed with water gives rise to considerable heat, +especially if mixed slowly with water. After the cotton has been well +washed, it is again wrung out in a centrifugal machine, and afterwards +allowed to steep in water for some time. + +[Illustration: FIG. 15_a_.--THE BEATER FOR GUN-COTTON.] + +~Boiling.~--The washed cotton is put into large iron boilers with plenty +of water, and boiled for some time at 100 deg. C. In some works lead-lined +tanks are used, into which a steam pipe is led. The soluble impurities of +unstable character, to which Sir F.A. Abel traced the liability of gun- +cotton to instability, are thereby removed. These impurities consist of +the products formed by the action of nitric acid on the fatty and resinous +substances contained in the cotton fibres. The water in the tanks should +be every now and again renewed, and after the first few boilings the water +should be tested with litmus paper until they are no longer found to be +acid. + +[Illustration: FIG. 15_b_.--WHEEL OF BEATER.] + +~Pulping.~--The idea of pulping is also due to Abel. By its means a very +much more uniform material is obtained. The process is carried out in an +apparatus known as a "Beater" or "Hollander" (Fig. 15, _a, b_). It +consists of a kind of wooden tank some 2 or 3 feet deep of an oblong +shape, in which a wheel carrying a series of knives is made to revolve, +the floor of the tank being sloped up so as to almost touch the revolving +wheels. This part of the floor, known as the "craw," is a solid piece of +oak, and a box of knives is fixed into it, against which the knives in the +revolving wheel are pressed. The beater is divided into two parts--the +working side, in which the cotton is cut and torn between the knife edges +in the revolving cylinder and those in the box; and the running side, into +which the cotton passes after passing under the cylinder. The wheel is +generally boxed in to prevent the cotton from being thrown out during its +revolution. The cotton is thus in constant motion, continually travelling +round, and passing between the knives in the revolving cylinder and those +in the box fixed in the wooden block beneath it. The beater is kept full +of water, and the cotton is gradually reduced to a condition of pulp. The +wheel revolves at the rate of 100 to 150 times a minute. + +[Illustration: FIG. 16_a_.--POACHER FOR WASHING GUN-COTTON.] + +[Illustration: FIG. 16_b_.--PLAN OF THE POACHER.] + +[Illustration: FIG. 16_c_.--ANOTHER FORM OF POACHER.] + +When the gun-cotton is judged to be sufficiently fine, the contents of the +beater are run into another very similar piece of machinery, known as the +"poacher" (Fig. 16, _a, b, c_), in which the gun-cotton is continuously +agitated together with a large quantity of water, which can be easily run +off and replaced as often as required. When the material is first run into +the poacher from the beater, the water with which it is then mixed is +first run away and clean water added. The paddle wheel is then set in +motion, and at intervals fresh water is added. There is a strainer at the +bottom of the poacher which enables the water to be drawn off without +disturbing the cotton pulp. After the gun-cotton has been in the poacher +for some time, a sample should be taken by holding a rather large mesh +sieve in the current for a minute or so. The pulp will thus partly pass +through and partly be caught upon the sieve, and an average sample will be +thus obtained. The sample is squeezed out by hand, bottled, and taken to +the laboratory to be tested by the heat test for purity. It first, +however, requires to be dried. This is best done by placing the sample +between coarse filter paper, and then putting it under a hand-screw press, +where it can be subjected to a tolerably severe pressure for about three +minutes. It is then rubbed up very finely with the hands, and placed upon +a paper tray, about 6 inches by 4-1/2 inches, which is then placed inside +a water oven upon a shelf of coarse wire gauze, the temperature of the +oven being kept as near as possible to 120 deg. F. (49 deg. C.), the gauze shelves +in the oven being kept about 3 inches apart. The sample is allowed to +remain at rest for fifteen minutes in the oven, the door of which is left +wide open. After the lapse of fifteen minutes the tray is removed and +exposed to the air of the laboratory (away from acid fumes) for two hours, +the sample being at some point within that time rubbed upon the tray with +the hand, in order to reduce it to a fine and uniform state of division. +Twenty grains (1.296 grm.) are used for the test. (See Heat Test, page +249.) + +If the gun-cotton sample removed from the poacher stands the heat test +satisfactorily, the machine is stopped, and the water drained off. The +cotton is allowed some little time to drain, and is then dug out by means +of wooden spades, and is then ready for pressing. The poachers hold about +2,000 lbs. of material, and as this represents the products of many +hundred distinct nitrating operations, a very uniform mixture is obtained. +Two per cent. of carbonate of soda is sometimes added, but it is not +really necessary if the cotton has been properly washed. + +~Compressing Gun-Cotton.~--The gun-cotton, in the state in which it is +removed from the poacher, contains from 28 to 30 per cent. of water. In +order to remove this, the cotton has to be compressed by hydraulic power. +The dry compressed gun-cotton is packed in boxes containing 2,500 lbs. of +dry material. In order to ascertain how much of the wet cotton must be put +into the press, it is necessary to determine the percentage of water. This +may be done by drying 2,000 grains upon a paper tray (previously dried at +100 deg. C.) in the water oven at 100 deg. C. for three hours, and re-weighing and +calculating the percentage of water. It is then easy to calculate how much +of the wet gun-cotton must be placed in the hopper of the press in order +to obtain a block of compressed cotton of the required weight. Various +forms of presses are used, and gun-cotton is sent out either as solid +blocks, compressed discs, or in the form of an almost dry powder, in zinc- +lined, air-tight cases. The discs are often soaked in water after +compression until they have absorbed 25 per cent. of moisture. + +[Illustration: FIG. 17.--OLD METHOD. 100 PIECES.] + +[Illustration: FIG. 18.--NEW METHOD. ONE SOLID BLOCK.] + +At the New Explosives Company's Stowmarket Works large solid blocks of +gun-cotton are pressed up under a new process, whereby blocks of gun- +cotton, for use in submarine mines or in torpedo warheads, are produced. +Large charges of compressed gun-cotton have hitherto been built up from a +number of suitably shaped charges of small dimensions (Fig. 17), as it has +been impossible to compress large charges in a proper manner. The +formation of large-sized blocks of gun-cotton was the invention of Mr A. +Hollings. Prior to the introduction of this method, 8 or 9 lbs. had been +the limit of weight for a block. This process has been perfected at the +Stowmarket factory, where blocks varying from the armour-piercing shell +charge of a few ounces up to blocks of compressed gun-cotton mechanically +true, weighing 4 to 5 cwts. for torpedoes or submarine mines, are now +produced. At the same time the new process ensures a uniform density +throughout the block, and permits of any required density, from 1.4 +downwards, being attained; it is also possible exactly to regulate the +percentage of moisture, and to ensure its uniform distribution. The +maximum percentage of moisture depends, of course, upon the density. By +the methods of compression gun-cotton blocks hitherto employed, blocks of +a greater thickness than 2 inches, or of a greater weight than 9 lbs., +could not be made, but with the new process blocks of any shape, size, +thickness, or weight that is likely to be required can be made readily and +safely. The advantages which are claimed for the process may be enumerated +as follows:--(1.) There is no space wasted, as in the case with built-up +charges, through slightly imperfect contact between the individual blocks, +and thus either a heavier charge--i.e., about 15 per cent. more gun- +cotton--can be got into the same space, or less space will be occupied by +a charge of a given weight. (2.) The metallic cases for solid charges may +be much lighter than for those built-up, since with the former their +function is merely to prevent the loss of moisture from wet gun-cotton, or +to prevent the absorption of moisture by dry gun-cotton. They can thus be +made lighter, as the solid charge inside will prevent deformation during +transport. With built-up charges the case must be strong enough to prevent +damage, either to itself or to the charge it contains. For many uses a +metal case, however light, may be discarded, and one of a thin waterproof +material substituted. (3.) The uniform density of charges made by this +process is very favourable to the complete and effective detonation of the +entire mass, and to the presence of the uniform amount of moisture in +every part of the charge. (4.) Any required density, from the maximum +downwards, may be obtained with ease, and any required amount of moisture +left in the charge. These points are of great importance in cases where, +like torpedo charges, it is essential to have the centre of gravity of the +charge in a predetermined position both vertically and longitudinally, and +the charge so fixed in its containing case that the centre of gravity +cannot shift. The difficulty of ensuring this with a large torpedo charge +built up from a number of discs and segments is well known. Even with +plain cylindrical or prismatic charges a marked saving in the process of +production is effected by this new system. The charges being in one block +they are more easily handled for the usual periodical examination, and +they do not break or chafe at the edges, as in the case of discs and cubes +in built-up charges. A general view of the press is given in Fig. 19. The +gun-cotton in a container is placed on a cradle fixed at an angle to the +press. The mould is swivelled round, and the charge pushed into it with a +rammer, and it is then swivelled back into position. The mould is made up +of a number of wedge pieces which close circumferentially on the enclosed +mass, which is also subjected to end pressure. Holes are provided for the +escape of water. + +[Illustration: FIG. 19.--A 4-CWT. BLOCK OF GUN-COTTON BEING TAKEN FROM +HYDRAULIC PRESS.] + +~The Waltham Abbey Process.~--At the Royal Gunpowder Factory, Waltham +Abbey, the manufacture of gun-cotton has been carried out for many years. +The process used differs but little from that used at Stowmarket. The +cotton used is of a good quality, it is sorted and picked over to remove +foreign matters, &c., and is then cut up by a kind of guillotine into +2-inch lengths. It is then dried in the following manner. The cotton is +placed upon an endless band, which conducts it to the stove, or drying +closet, a chamber heated by means of hot air and steam traps to about +180 deg. F.; it falls upon a second endless band, placed below the first; it +travels back again the whole length of the stove, and so on until +delivered into a receptacle at the bottom of the farther end, where it is +kept dry until required for use. The speed at which the cotton travels is +6 feet per minute, and as the length of the band travelled amounts to 126 +feet, the operation of drying takes twenty-one minutes. One and a quarter +lb. are weighed out and placed in a tin box; a truck, fitted to receive a +number of these boxes, carries it along a tramway to a cool room, where it +is allowed to cool. + +~Dipping.~--Mixed acids are used in the proportion of 1 to 3, specific +gravity nitric acid 1.52, and sulphuric acid 1.84. The dipping tank is +made of cast iron, and holds 220 lbs. of mixed acids, and is surrounded on +three sides by a water space in order to keep it cool. The mixed acids are +stored in iron tanks behind the dipping tanks, and are allowed to cool +before use. During the nitration, the temperature of the mixed acids is +kept at 70 deg. F., and the cotton is dipped in quantities of 1-1/2 lb. at a +time. It is put into a tin shoot at the back of the dipping tank, and +raked into the acids by means of a rabble. It remains in the acids for +five or six minutes, and is then removed to a grating at the back, pressed +and removed. After each charge of cotton is removed from the tank, about +14 lbs. of fresh mixed acids are added, to replace amount removed by +charge. The charge now weighs, with the acids retained by it, 15 lbs.; it +is now placed in the pots, and left to steep for at least twenty-four +hours, the temperature being kept as low as possible, to prevent the +formation of soluble cotton, and also prevent firing. The proportion of +soluble formed is likely to be higher in hot weather than cold. The pots +must be covered to prevent the absorption of moisture from the air, or the +accidental entrance of water, which would cause decomposition, and +consequent fuming off, through the heat generated by the action of the +water upon the strong acids. + +The excess of acids is now extracted by means of hydro-extractors, as at +Stowmarket. They are worked at 1,200 revolutions per minute, and whirled +for five minutes (10-1/2 lbs. of waste acids are removed from each charge +dipped). The charge is then washed in a very similar manner to that +previously described, and again wrung out in a centrifugal extractor +(1,200 revolutions per minute). The gun-cotton is now boiled by means of +steam in wooden tanks for eight hours; it is then again wrung out in the +extractors for three minutes, boiled for eight hours more, and again wrung +out; it is then sent to the beater and afterwards to the poacher. The +poachers hold 1,500 gals. each, or 18 cwt. of cotton. The cotton remains +six hours in the poachers. Before moulding, 500 gals. of water are run +into the poacher, and 500 gals. of lime water containing 9 lbs. of whiting +and 9 gals. of a caustic soda solution. This mixture is of such a strength +that it is calculated to leave in the finished gun-cotton from 1 to 2 per +cent. of alkaline matter. + +By means of vacuum pressure, the pulp is now drawn off and up into the +stuff chest--a large cylindrical iron tank, sufficiently elevated on iron +standards to allow room for the small gauge tanks and moulding apparatus +below. It holds the contents of one poacher (18 cwt.), and is provided +with revolving arms to keep the pulp stirred up, so that it may be +uniformly suspended in water. + +Recently a new process, invented by J.M. and W.T. Thomson (Eng. Pat. No. +8,278, 1903), has been introduced at the Waltham Abbey Factory. The object +of this invention is the removal of the acids of nitration from the +nitrated material after the action has been completed, and without the aid +of moving machinery, such as presses, rollers, centrifugals, and the like. +The invention consists in the manufacture of nitrated celluloses by +removing the acids from the nitrated cellulose directly by displacement +without the employment of either pressure or vacuum or mechanical +appliances of any kind, and at the same time securing the minimum dilution +of the acids. It was found that if water was carefully run on to the +surface of the acids in which the nitro-cellulose is immersed, and the +acids be slowly drawn off at the bottom of the vessel, the water displaces +the acid from the interstices of the nitro-cellulose without any +undesirable rise in temperature, and with very little dilution of the +acids. By this process almost the whole of the acid is recovered in a +condition suitable for concentration, and the amount of water required for +preliminary washing is very greatly reduced. The apparatus which is used +for the purpose consists of a cylindrical or rectangular vessel +constructed with a perforated false bottom and a cock at its lowest point +for running off the liquid. Means are also provided to enable the +displacing water to be run quietly on to the surface of the nitrating +acids.[A] + +[Footnote A: In a further patent (Eng. Pat. 7,269, 1903, F.L. Natham), +J.M. Thomson and W.T. Thomson propose by use of alcohol to replace the +water, used in washing nitro-cellulose, and afterward to remove the +alcohol by pressing and centrifuging.] + +The apparatus is shown in Fig. 2O, side elevation, and in Fig. 21 a plan +of the nitrating vessel and its accessories is given. In Fig. 20 is shown +in sectional elevation one of the trough devices for enabling liquids to +be added to those in the nitrating vessel without substantial disturbance. + +[Illustration: FIG. 20.--SECTIONAL ELEVATION OF THOMSON'S APPARATUS, _a_, +Tank; _b_, False Bottom; _c_, Bottom; _c'_, Ribs; _d_, Draining Outlet; +_e_, Grid; _f_, Troughs, with Aprons _g_; _h_, Pipe, with Branches _h'_, +leading to Troughs, _f_; _k'_, Outlet Pipe of the Sulphuric Acid Tank _k_; +_l_, Water Supply Pipe; _m_, Pipe to supply of Nitrating Acids; _o_, +Perforations of Trough _f_; _p_, Cock to remove Acid.] + +In carrying out this invention a rectangular lead-lined or earthenware +tank _a_ is employed, having a false bottom _b_, supported by ribs _c'_, +over the real bottom _c_, which slopes down to a draining outlet pipe _d_, +provided with a perforated grid or plate _e_, adapted to prevent choking +of the outlet. Suitably supported near the top of the vessel _a_ are +provided two troughs, _f_ having depending aprons _g_, a pipe _h_ has two +branches _h'_, leading to the troughs, _f_. This pipe _h_ is adapted to be +connected by a rubber pipe either to the outlet pipe _k'_ of the sulphuric +acid tank _k_ or the water supply pipe _l_. The nitrating acids are +supplied through the pipe _m_. A charge of mixed nitrating acids is +introduced into the vessel _a_ say up to the level _n_, and the dry +cellulose thrown into the acids in small quantities at a time, being +pushed under the surface in the usual way. + +[Illustration: FIG. 21.--PLAN OF THOMSON'S APPARATUS, _a_, Tank; _b_, +False Bottom; _c'_, Ribs; _e_, Grid; _f_, Troughs; _g_, Aprons; _h_ and +_h'_, Pipes to Troughs _f_; _k_, Sulphuric Acid Tank; _m_, Pipe to +Nitrating Acids Tank; _o_, Perforations of Troughs; _p_, Cock to remove +Acid.] + +A thin layer, say half an inch, of a suitable liquid, preferably sulphuric +acid, of a gravity not exceeding that of the waste acid to be produced, is +run carefully on the top of the acids by means of the troughs _f_, which +are perforated as shown at _o_, so that the sulphuric acid runs down the +aprons _g_, and floats on the nitrating acids. The whole is then allowed +to stand till nitration has been completed. Water is then supplied to the +troughs by way of the pipes _l_, _h_, and _h'_, and is allowed to float +very gently over the surface of the sulphuric acid, and when a sufficient +layer has been formed, the cock _p_ at the bottom of the apparatus is +opened, and the acid slowly drawn off, water being supplied to maintain +the level constant. It is found that the rate of displacement of the acids +is a factor which exerts a considerable influence on the properties of the +resulting nitro-cellulose, and affords a means of regulating the +temperature of displacement. A rate of displacement which has been found +suitable is about two inches in depth of the vessel per hour when treating +highly nitrated celluloses, but this rate may, in some cases, be +considerably increased. The flow of water at the top of the apparatus is +regulated so that a constant level is maintained. By this means the water +gradually and entirely displaces the acids from the interstices of the +nitro-cellulose, the line of separation between the acids and the water +being fairly sharply defined throughout. The flow of water is continued +until that issuing at the bottom is found to be free from all trace of +acid. The purification of the nitro-cellulose is then proceeded with as +usual, either in the same vessel or another. + +In the process above described, the object of the introduction of a small +layer of sulphuric acid is mainly to prevent the fuming which would +otherwise take place, and is not essential, as it is found it can be +omitted without any deleterious effect. In order to use the mixed acids in +the most economical manner, the waste acid from a previous operation may +be used for a first nitration of the cellulose; being afterwards displaced +with fresh acids which carry the nitration to the required degree before +they are in turn displaced by water. The apparatus may be used merely for +the removal of the acid, in which case the nitration is carried out in +other vessels in the usual way, and the nitro-cellulose removed to the +displacement apparatus where it is just covered with waste acid, and the +displacement then proceeded with as above described. In some cases the +process is carried out in an ordinary nitrating centrifugal, using the +latter to effect preliminary drying after acid extraction. This gives a +great advantage over the usual method of working ordinary centrifugal +nitrating apparatus, because the acid being removed before the centrifugal +is run, practically all danger of firing therein disappears, and a greater +proportion of the waste acid is recovered. + +In some cases the acids and water may be supplied by perforated pipes, +lying along the edges of the nitrating vessel, and these edges may, if +desired, be themselves made inclined, like the sides of the troughs _f_. +In the case of effecting nitration in centrifugals as above, the +displacing sulphuric acid and water may thus be supplied round the edges +of the machines, or removal troughs such as _f_ may be used. It will be +obvious that any inert liquid of suitable specific gravity may be used +instead of sulphuric acid, as a separation layer. + +~Moulding.~--By means of the small measuring tank above referred to, the +gun-cotton pulp is drawn off from the stuff chest, and run into moulds of +the shapes and sizes required. Thence a large proportion of the water is +drawn off by means of tubes connected with the vacuum engine, the moulds +having bottoms of fine wire gauze, in order to prevent the pulp from +passing through. Hydraulic pressure of about 34 lbs. on the square inch is +then applied, which has the effect of compressing the pulp into a state in +which it has sufficient consistency to enable it to be handled with care, +and also expels a portion of the remaining water. + +~Compressing.~--The moulded gun-cotton is now taken to the press house, +which is situated at some distance from the rest of the factory. Here the +moulds are subjected to powerful hydraulic pressure, from 5 to 6 tons per +square inch, and is compressed to one-third of its previous bulk. The +slabs or discs thus formed are kept under pressure for a short time, not +exceeding a minute and a half, to give the requisite density. It should, +when removed, be compact, and just sink in water, and should perceptibly +yield to the pressure of the fingers. There are perforations in the press +blocks, to allow of the escape of gases, if formed, by reason of +sufficient heat being generated. The men working the press are placed +under cover, behind strong rope mantlets having eye tubes which command a +view of the press. + +~Packing.~--The finished slabs and discs are dipped into a solution of +soda and carbolic acid, and packed in special wood metal-lined cases. When +it is to be sent abroad, the metal lining, which is made of tinned copper, +is soldered down, but both the outer wooden and inner metal cases are +fitted with air-tight screw-plugs, so that when necessary water can be +added without unfastening the cases. + +~Reworked gun-cotton~ does not make such good discs as new pulped gun- +cotton, probably because the fibrous tenacity of the gun-cotton has been +destroyed by the amount of pressure it has previously undergone, so that +when repulped it resembles fine dust, and a long time is required to press +it into any prescribed form. It is generally boiled for eight hours to +open up the fibre and remove alkali, then broken up by hand with wooden +mallets, pulped, and then used with fresh gun-cotton in the proportion of +1 to 5 parts. + +~Manufacture at Le Bouchet.~--At Le Bouchet gun-cotton was made thus:--200 +grms. of cotton were steeped for an hour in 2 litres of a mixture of 1 +volume concentrated nitric and 2 volumes sulphuric acid. The cotton was +then removed and pressed, whereby 7/10ths of the waste acids was +recovered. After this it was washed for one to one and a half hours in +running water, strongly pressed again; allowed to lie for twenty-four +hours in wood-ash lye; then well washed in running water; pressed, and +finally dried on a wide linen sheet, through which was forced air heated +to 60 deg. C. The average yield from 100 parts of cotton was 165 parts of gun- +cotton. The strong pressings of the gun-cotton, while still impregnated +with acids, caused subsequent washings to be difficult and laborious. + +~Granulation of Gun-Cotton.~--Gun-cotton is often required in the +granulated form for use either alone or with some form of smokeless +powder. This is done under the patent of Sir Frederick Abel in the +following manner:--The gun-cotton from the poacher is placed in a +centrifugal machine, very similar to the hydro-extractors before +mentioned, and used for wringing out the acids. In this machine it loses +water until it only contains 33 per cent., and is at the same time reduced +to a more or less fibrous state. It is then taken to the granulating room, +where it is first passed through sieves or perforations, which break up +the mass into little pieces like shot. The material is then transferred to +a revolving drum made of wood or stout leather, which is kept constantly +revolving for some time. The material is occasionally sprinkled with +water. The drum in turning, of course, carries the granules partially +round with it, but the action of gravity causes them to descend constantly +to the lowest point, and thus to roll over one another continually. The +speed of the drum must not be too rapid. None of the granules must be +carried round by centrifugal force, but it must be fast enough to carry +them some little distance up the side of the drum. After removal from the +drum the granules are dried upon shelves in the drying house. + +Gun-cotton is also dissolved in acetone or acetic ether until it has taken +the form of a jelly. It is then rolled into thin sheets, and when dry cut +up into little squares. In the manufacture of smokeless powders from +nitro-cellulose, nitro-lignine, &c., the various substances are mixed with +the gun-cotton or collodion-cotton before granulating. + +~Collodion-Cotton.~--In the manufacture of collodion or soluble cotton the +finer qualities of cotton-waste are used and the acids used in the dipping +tanks are much weaker. The manufacture of collodion-cotton has become of +more importance than gun-cotton, by reason of its use for the manufacture +of the various forms of gelatine, such as gelatine dynamite, gelignite, +forcite, &c., and also on account of its extensive use in the manufacture +of many of the smokeless powders. It is also used for the manufacture of +"collodion," which is a solution of collodion-cotton in ether-alcohol; for +the preparation of celluloid, and many other purposes. It is less +explosive than gun-cotton, and consists of the lower nitrates of +cellulose. It is soluble in nitro-glycerine, and in a mixture of 2 parts +of ether and 1 of alcohol; also in acetone, acetic ether, and other +solvents. MM. Menard and Domonte were the first to prepare a soluble gun- +cotton, and its investigation was carried on by Bechamp, who showed that +its properties and composition were different to those of gun-cotton. + +~Manufacture.~--The cotton used is cotton-waste.[A] It is thought by some +that Egyptian cotton is preferable, and especially long fibre varieties. +The strength of the acids used is, however, of more importance than the +quality of the cotton. The percentage composition of the acid mixture +which gives the best results is as follows:--Nitric acid, 23 per cent.; +sulphuric acid, 66 per cent.; and water, 11 per cent; and has a specific +gravity of 1.712 (about). It can be made by mixing sulphuric acid of +specific gravity 1.84 with nitric acid of specific gravity 1.368 in the +proportions of 66 per cent. and 34 per cent. respectively. (The production +of the penta-nitro-cellulose is aimed at if the collodion-cotton is for +use as an explosive.) If the acids are much weaker than this, or potassium +nitrate and sulphuric acid is used, the lower nitrates will be formed. The +product, while being entirely soluble in ether-alcohol or nitro-glycerine, +will have a low nitrogen content, whereas a material with as high a +nitrogen as 12 or 12.6 is to be aimed at. + +[Footnote A: Raw cotton is often used.] + +The cotton should not be allowed to remain in the dipping tanks for more +than five minutes, and the acid mixture should be kept at a temperature of +28 deg. C. or thereabouts; and the cotton should be removed after a few +minutes, and should not be pressed out, as in the case of gun-cotton, but +at once transferred to the pots and allowed to steep for forty-eight +hours. (Some prefer twenty-four hours, but there is more chance in this +case of the product containing non-nitrated cellulose.) When the nitration +is complete, the collodion-cotton is removed from the pots, and treated in +exactly the same manner as described under gun-cotton. The produce should +be entirely soluble in ether-alcohol and nitro-glycerine, and contain as +near 12.7 per cent. of nitrogen as possible. The theoretical nitrogen is +for the penta-nitro-cellulose 12.75 per cent. This will, however, seldom +if ever be obtained. The following are some of the results I have obtained +from different samples:-- + + Nitrogen. + (1.) (2.) (3.) +German make 11.64 11.48 11.49 per cent. +Stowmarket 12.57 12.60 11.22 " +Walsrode 11.61 12.07 11.99 " +Faversham 12.14 11.70 11.60 " + +and the following was the analysis of a sample (No. 1) of German-made +collodion-cotton, which made very good blasting gelatine:-- + + _ +Soluble cotton (collodion) 99.118 per cent.| Nitrogen = 11.64 per cent. +Gun-cotton 0.642 " _| +Non-nitrated cotton 0.240 " +Total ash 0.25 " + +It should contain as little non-nitrated or unconverted cotton and as +little gun-cotton as possible, as they are both insoluble in nitro- +glycerol. The quality and composition of any sample of collodion-cotton +can be quickly inferred by determining the percentage of nitrogen by means +of the nitrometer and the use of the solubility test.[A] A high nitrogen +content coupled with a high solubility is the end to be aimed at; a high +nitrogen with a low solubility shows the presence of gun-cotton, and a low +nitrogen, together with a low solubility, the presence of unnitrated +cotton. Where complete solubility is essential and the percentage of +nitrogen less important, Dr Lunge recommends nitration with a mixture of +equal parts of sulphuric and nitric acids containing from 19 to 20 per +cent. of water. + +[Footnote A: See Analysis of Explosives.] + +Mr T.R. France claims to have invented some improvements in the +manufacture of soluble nitro-cellulose. His object has been to produce an +article as uniform as possible. His explanation of the imperfect action of +the acids is that, however uniform the mixed acids may be in strength and +proportions, and however carefully the operations of nitrating, &c., may +be conducted, there are variable elements found in different samples of +cotton. The cotton fibre has for its protection a glazed surface. It is +tubular and cellular in structure, and contains a natural semi-fluid +substance composed of oil or gum, which varies in nature according to the +nature of the soil upon which the cotton is grown. The tubes of the fibre +seem to be open at one end only when the fibre is of normal length. When, +therefore, the cotton is subjected to the action of the mixed acids, the +line of least resistance seems to be taken by them, viz., the insides of +the tubes constituting the fibre of the cotton, into which they are taken +by capillary attraction, and are subject to change as they progress, and +to the increased resistance from the oil or gum, &c., in their progress, +and therefore to modified action, the result of which is slower and slower +action, or chemical change. He also thinks it is possible that the power +of capillary attraction is balanced in the tubes by air contained therein, +after a little, sufficiently so to prevent the acids from taking full +effect. To get over this, Mr France uses his cotton in a fine state, +almost dust, in fact, and then nitrates in the usual mixture of acids at +40 deg. to 90 deg. F., the excess of acids being removed by pressure. He says he +does not find it necessary to wash this fine cotton dust in an alkaline +solution previous to nitration. His mixed acids consist of 8 parts HNO_{3} += 42 deg. B., and 12 parts H_{2}SO_{4} = 66 deg. B., and he stirs in the dipping +tank for fifteen minutes, the temperature being 50 deg. F. to 100 deg. F., the +temperature preferred being 75 deg. F. + +~"Nitrated" Gun-Cotton.~--The nitrates that are or have been mixed with +gun-cotton in order to supply oxygen are potassium nitrate, ammonium +nitrate, and barium nitrate (tonite). The total combustion of gun-cotton +by potassium nitrate corresponds to the equation:-- + +10[C_{24}H_{18}(NO_{3}H)_{11}O_{9}] + 82KNO_{3} = 199CO_{2} + +41K_{2}CO_{3} + 145H_{2}O + 96N_{2}, + +or 828 grms. of nitrate for 1,143 grms. of gun-cotton, or 42 per cent. +nitrate and 58 per cent. gun-cotton. The explosive made at Faversham by +the Cotton Powder Company, and known as tonite No. 1, consists of very +nearly half gun-cotton and half barium nitrate. The relations by weight of +total combustion would be 51.6 of gun-cotton to 48.4 of barium nitrate. +The average composition of tonite I have found by analysis to be 51 per +cent. gun-cotton to 49 per cent. barium nitrate. The heat liberated is +practically the same as for an equivalent weight of KNO_{3}; but the +barium nitrate mixture weighs 2,223 grms. instead of 1,971 grms., or +one-eighth more. The advantage in mixing a nitrate with gun-cotton is that +it supplies oxygen, and by converting all the carbon into carbonic acid, +prevents the formation of the poisonous gas carbonic oxide (CO). The +nitrates of potassium and barium are also used admixed with nitro- +cellulose in several of the sporting smokeless powders. + +~The Manufacture of Tonite.~--The explosive tonite was patented by Messrs +Trench, Faure, and Mackie, and is manufactured at Faversham and Melling at +the works of the Cotton Powder Company, and at San Francisco by the Tonite +Powder Company. It consists of finely divided and macerated gun-cotton +incorporated with finely ground nitrate of barium which has been carefully +recrystallised. It is made by acting upon carbonate of barium[A] with +nitric acid. The wet and perfectly purified, finely pulped gun-cotton is +intimately mixed up between edge runners with about the same weight of +nitrate, and the mixing and grinding continued until the whole has become +an intimately mixed paste. This paste is then compressed into cartridges, +formed with a recess at one end for the purpose of inserting the +detonator. The whole is then covered with paraffined paper. + +[Footnote A: Witherite, BaCO_{3} + 2HNO_{3} = Ba(NO_{3})_{2} + CO_{2} + +H_{2}O.] + +The tonite No. 2 consisted of gun-cotton, nitrates of potash and soda, +charcoal and sulphur. Tonite No. 3[A] is composed as follows:--Gun-cotton, +19 per cent.; di-nitro-benzol, 13 per cent.; and barium nitrate, 68 per +cent. or similar proportions. It is a yellowish colour, and being slower +in its explosive action, is better adapted for blasting soft rock. + +[Footnote A: Tonite No. 1 was patented by Messrs Trench, Faure, and +Mackie, and tonite Nos. 2 and 3 by Trench alone.] + +Tonite is extensively used in torpedoes and for submarine blasting, also +for quarries, &c. Large quantities were used in the construction of the +Manchester Ship Canal. Among its advantages are, that the English railways +will take tonite on the same footing as gunpowder; it is a very dense +material; if wetted it can easily be dried in the sun; it very readily +explodes by the use of a proper detonator; while it burns very slowly and +without the least danger; the cartridges being waterproofed, it can be +employed in wet bore holes, and it can be tamped with water; and finally, +as it contains sufficient oxygen to oxidise the carbon, no carbonic oxide +(CO) gas is formed, i.e., its detonation is perfect. It is a very safe +explosive to use, being little susceptible to either blows or friction. + +Not long ago, a committee, composed of Prof. P. Bedson, Drs Drummond and +Hume, Mr T. Bell, one of H.M. Inspectors of Coal Mines, and others, in +considering the problem whether the fumes produced by the combustion of +tonite were injurious to health, carried out a series of experiments in +coal mines for this purpose. The air at the "intake" was analysed, also +the air of the "return," and the smoky air in the vicinity of the shot +holes. The cartridge was surrounded by the flame-extinguishing mixture, +and packed in a brown paper bag. During the first experiment nineteen +shots were fired (= 6.29 lbs. tonite). The "return" air showed only a +trace of carbonic oxide gas (CO). At the second experiment thirteen shots +were fired (= 4.40 lbs. tonite), and analysis of the air of the "return" +showed that CO was present in traces only, whilst the fumes contained only +1.9 to 4.8 parts per 10,000. + +~Dangers in connection with the Manufacture of Guncotton, &c.~--Of all the +nitro compounds, the least dangerous to manufacture are gun-cotton and +collodion-cotton. The fact that the Stowmarket Factory is within five +minutes' walk of the town shows how safe the manufacture of this explosive +is regarded. With the exception of the nitration and the compression into +blocks or discs, the whole process is worked with a large excess of water, +and the probability of an explosion is thus reduced to a minimum. Among +the precautions that should, however, be taken, are--first, the careful +extraction of the resinous and soluble substances from the cotton before +nitration, as it was shown many years ago by Sir F.A. Abel that the +instability of the gun-cotton first manufactured in England and Austria +was chiefly due to these compounds. They are generally removed by boiling +the cotton in a soda solution. + +The actual nitration of cotton is not a dangerous operation, but the +operations of wringing in the hydro-extractors, and washing the nitro- +cotton after it leaves the first centrifugal machine, are somewhat so. +Great care should be taken that the wrung-out nitro-cotton at once comes +in contact with a large excess of water, i.e., is at once immersed +entirely in the water, since at this stage it is especially liable to +decomposition, which, once started, is very difficult to stop. The warmer +the mixture and the less water it contains, the more liable it is to +decomposition; hence it is that on warm and damp days the centrifugal +machines are most likely to fire. The commencement of decomposition may be +at once detected by the evolution of red fumes. Directly the gun-cotton is +immersed in the large quantity of water in the beater and poacher it is +safe. + +In order that the final product may be stable and have good keeping +qualities, it is necessary that it should be washed completely free from +acid. The treatment in the beater and poacher, by causing the material to +assume the state of a fine pulp, in contact with a large quantity of +water, does a good deal to get rid of the free acid, but the boiling +process is absolutely necessary. It has been proposed to neutralise the +free acid with a dilute solution of ammonia; and Dr C.O. Weber has +published some experiments bearing upon this treatment. He found that +after treatment with ammonia, pyroxyline assumed a slightly yellowish +tinge, which was a sure sign of alkalinity. It was then removed from the +water, and roughly dried between folds of filter paper, and afterwards +dried in an oven at 70 deg. C. After three hours, however, an explosion took +place, which entirely destroyed the strong copper oven in which the nitro- +cotton (about one oz.) had been drying. The explosion was in some respects +remarkable. The pyroxyline was the di-nitro-cellulose (or possibly the +penta-nitro?), and the temperature was below the igniting point of this +material (40 deg. C. would have been a better temperature). Dr Weber +determined the ignition point of his di-nitro-cellulose, and found it to +be 194 deg. to 198 deg. C., and he is therefore of opinion that the explosion was +due to the treatment of the partially washed material with ammonia. A +certain quantity of ammonium nitrate was probably formed, and subsequently +dried upon the nitro-cellulose, in a state of very fine subdivision. The +faintest trace of acid would then be sufficient to bring about the +explosive ignition of the ammonium nitrate. + +The drying of gun-cotton or collodion-cotton is also a somewhat dangerous +operation. A temperature of 40 deg. C. (104 deg. F.) should not be exceeded, and +thermometers should be placed in the nitro-cotton, and the temperature +frequently observed. An electric alarm thermometer is also a useful +adjunct to the cotton drying house. Great care must also be taken that +there are no exposed hot-water pipes or stoves in the drying house, as the +fine gun-cotton dust produced by the turning or moving of the material +upon the shelves would settle upon such pipes or stoves, and becoming hot, +would be very sensitive to the least friction. The floor also should be +covered with linoleum or indiarubber. When hot currents of air are made to +pass over the surface of gun-cotton, the gun-cotton becomes electrified. +It is important, therefore, to provide some means to carry it away. Mr +W.F. Reid, F.I.C., was the first to use metal frames, carriers, and +sieves, upon which is secured the cloth holding the gun-cotton, and to +earth them. + +The compression of gun-cotton into blocks, discs, &c., is also attended +with considerable risk. Mr O. Guttmann, in an interesting paper upon "The +Dangers in the Manufacture of Explosives" (_Jour. Soc. Chem. Ind._, No. 3, +vol. xi., 1892), says: "The compression of gun-cotton into cartridges +requires far more care than that of gunpowder, as this is done in a warm +state, and gun-cotton even when cold, is more sensitive than gunpowder. +When coming out of the centrifugal machines, the gun-cotton should always +pass first through a sieve, in order to detect nails or matches which may +by chance have got into it. What has been said as to gunpowder presses +applies still more to those for gun-cotton, although the latter are always +hydraulic presses. Generally the pistons fit the mould perfectly, that is +to say, they make aspiration like the piston of a pump. But there is no +metal as yet known which for any length of time will stand the constant +friction of compression, and after some time the mould will be wider in +that part where the greatest compression takes place. The best metal for +this purpose has proved to be a special steel made by Krupp, but this also +is only relatively better; for pistons I prefer hard cast iron. If the +position of the moulds and pistons is not exactly the same in all cases, +what the Germans call 'Ecken' (English 'binding') will take place, viz., +the mould will stand obliquely to the piston, and a dangerous friction +will result." "Of course, it is necessary to protect the man working the +hydraulic valves during compression. At Waltham Abbey they have a curtain +made of ship's hawsers, which is at the same time elastic and resistant." +Mr Guttmann has found that a partition wall 12 inches thick, made of +2-inch planks, and filled with ground cinders, gives very effective +protection. A door in this partition enables the workman to get to the +press, and a conical tube penetrates the wall, enabling the man to see the +whole work from a safe standpoint. The roof, or one side of the building, +should be of glass, so as to give the explosion a direction. + +~Trench's Fire-extinguishing Compound~ is manufactured by the Cotton +Powder Company at Faversham, and is the invention of Mr George Trench, +F.C.S., the manager of the Company. The object of the invention is to +surround the cartridges of tonite, when used in coal mines, with a fire- +extinguishing compound. If a charge of tonite, dynamite, or gelatine +dynamite is put inside a few ounces of this mixture, and then fired, not +the least trace of flame can be observed, and experiments appear to show +that there is no flame at all. The compound consists of sawdust +impregnated with a mixture of alum and chlorides of sodium and ammonia. +Fig. 22 shows the manner of placing the tonite cartridge in the paper bag, +and surrounding it with the fire-extinguishing compound, _aa_. The +attachment of the fuse and detonator is also shown. + +[Illustration: FIG. 22.--TRENCH'S FIRE-EXTINGUISHING CARTRIDGE.] + +The following report (taken from the _Faversham News_, 22nd Oct. 1887) of +experiments conducted in the presence of several scientific and mining men +will show its value:--"A large wrought-iron tank, of 45 cubic feet +capacity, had been sunk level with the ground in the middle of the yard; +to this tank the gas had been laid on, for a purpose that will be +explained later on. The charges were fired by means of electricity, a +small dynamo firing machine being placed from 30 to 40 yards away from the +'mine.'" Operations were commenced by the top of the tank being covered +over and plastered down in order to make it air-tight; then a sufficient +quantity of coal gas was placed in it to make it highly inflammable and +explosive, the quantity being ascertained by a meter which had been fixed +specially for the purpose. Whilst the gas was being injected the cartridge +was prepared. + +The first experiment was to try whether a small charge of tonite--fired +without the patent extinguisher--would ignite the gas. The gas having been +turned on, a miner's lamp was placed in the "tank," but this was +extinguished before the full quantity of gas had gone through the meter. +However, the gas being in, the charge of 1-1/4 oz. tonite was placed in +the "mine," the detonator was connected by means of long wires to the +dynamo machine, and the word was given to "fire." With a tremendous +report, and a flash of fire, the covering of the mine flew in all +directions, clearly showing that the gas had exploded. The next cartridge +(a similar charge) was prepared with the patent compound. First of all a +brown paper case of about 2 inches diameter was taken, and one of the +tonite cartridges was placed in the centre of it, the intervening space +between the charge and-the case being packed with the "fire-extinguishing +compound." The mine having had another supply of gas injected, the +protected cartridge was placed inside and fired. The result was +astonishing, the explosion not being nearly so loud, whilst there was not +the least flash of fire. "Protected" and "unprotected" charges were fired +at intervals, gas being turned into the tank on each occasion. Charges of +tonite varying from 1 to 6 oz. were also used with the compound. The +report was trifling, whilst no flash could be seen. + +~Uses of Collodion-Cotton.~--The collodion or soluble gun-cotton is used +for a variety of purposes. The chief use is, however, for the manufacture +of the various explosive gelatine compounds, of which blasting gelatine is +the type. It is also very extensively used in the manufacture of smokeless +powders, both military and sporting--in fact, very few of them do not +contain it. In some, however, nitro-lignose or nitrated wood is used +instead. This, however, is chemically the same thing, viz., nitro- +cellulose, the cellulose being derived from the wood fibre. It is more +used in this connection than the higher nitrate gun-cotton. Another use to +which it has been applied very extensively, of recent years, is in the +manufacture of "celluloid." It is used in photography for the preparation +of the films on the sensitised plates, and many other purposes. Dissolved +in a solution of two parts ether and one of alcohol, it forms the solution +known as collodion, used for a variety of purposes, such as a varnish, as +a paint for signals; in surgery, for uniting the edges of wounds. + +Quite lately, Mr Alfred Nobel, the well-known inventor of dynamite, has +patented the use of nitro-cellulose, hydro- or oxy-cellulose, as an +artificial substitute for indiarubber. For this purpose it is dissolved in +a suitable non-volatile or slightly volatile "solvent," such as nitro- +naphthalene, di-nitro-benzene, nitro-toluene, or its homologues; products +are obtained varying from a gelatinous consistency to the hardness of +ebonite. The proportions will vary from about 20 per cent. of nitro- +cellulose in the finished product, forming a soft rubber, to 50 per cent. +nitrating celluloid, and the "solvent" chosen will depend on the use to +which the rubber substitute is to be put, the liquids giving a more +elastic substance, whilst mixtures of solids and liquids may be employed +when the product is to be used at high temperatures. By means of rollers +steam heated, the incorporation may be accomplished without the aid of a +volatile liquid, or the nitro-cellulose may be employed wet, the water +being removed after "solution." + +It is advisable to use the cellulose nitrated only just enough to render +it suitable, in order to reduce the inflammability of the finished +product. Mr W. Allen, M.P., of Gateshead, proposed to use celluloid for +cartridge cases, and thus to lighten ammunition, and prevent jambing, for +the case will be resolved into gases along with the powder. Extractors +will also be done away with. + +~Celluloid~ is an intimate mechanical mixture of pyroxyline (gun-cotton or +collodion-cotton) with camphor, first made by Hyatt, of Newark, U.S.A., +and obtained by adding the pyroxyline to melted camphor, or by strongly +compressing the two substances together, or by dissolving the constituents +in an appropriate solvent, e.g., alcohol or ether, and evaporating to +dryness. A combination of the two latter methods, i.e., partial solution, +with pressure, is now usually adapted. The pyroxyline employed is +generally the tetra- and penta-nitrated cellulose, the hexa-nitrate +(gun-cotton) being but seldom used on account of its explosive properties. + +Care is taken to prevent the formation of the hexa-nitrate by immersing +the cellulose in only moderately strong nitric acid, or in a warm mixture +of nitric and sulphuric acids. The paper, either in small pieces or in +sheets, is immersed for about twenty-five minutes in a mixture of 2 parts +of nitric acid and 5 parts of sulphuric acid, at a temperature of about +30 deg. C., after which the nitrated cellulose is thoroughly washed with water +to remove the last traces of free acid, pressed, and whilst still moist, +mixed with the camphor. + +In the process of Trebouillet and De Besancele, the cellulose, which may +be in the form of paper, cotton, or linen, is twice nitrated--first in the +acid mixture employed in a previous operation; and secondly, in a fresh +mixture of 3 parts sulphuric acid of 1.83 specific gravity, and 2 parts +concentrated nitric acid containing nitrous acid. After each nitration the +mass is subjected to pressure, and is then carefully washed with water, to +which, at the last, a small quantity of ammonia or caustic soda is added +to remove the final traces of acid. The impregnation of the pyroxyline +with the camphor is effected in a variety of ways. + +The usual proportion of the constituents is 2 parts pyroxyline and 1 part +camphor. In Trebouillet and De Besancele's process, 100 parts of +pyroxyline are intimately mixed with from 40 to 50 parts camphor, and +moulded together by strong pressure in a hot press, and afterwards dried +by exposure to air, desiccated by calcium chloride or sulphuric acid. The +usual method is, however, to dissolve the camphor in the least possible +quantity of alcohol, and sprinkle the solution over the dry pyroxyline, +which is then covered with a second layer of pyroxyline, and the whole +again treated with the camphor solution, the addition of pyroxyline and +camphor solution being repeated alternately until the requisite amount of +celluloid mixture is obtained. + +The mass, which sinks together in transparent lumps, is worked for about +an hour between cold iron rollers, and then for the same period between +rollers which can be gently heated by steam. The layer of celluloid +surrounding the rollers is then cut away and again pressed, the resulting +cake, which is now about 1 cm. thick, being cut into plates of about 70 +cm. long and 30 cm. broad. These are placed one above the other, and +strongly pressed together by hydraulic pressure at a temperature of about +70 deg. for twenty-four hours. The thick cakes are once more cut into plates +of the desired thickness, and placed in a chamber heated from 30 deg. to 40 deg. +for eight to fourteen days, whereby they become thoroughly dry, and are +readily made into various articles either by being moulded while warm +under pressure, cut, or turned. Occasionally other liquids, e.g., ether +and wood spirit, are used in place of alcohol as solvents for the camphor. + +Celluloid readily colours, and can be marbled for manufacturing purposes, +&c. It is highly inflammable and not explosive even under pressure, and +may be worked under the hammer or between rollers without risk. It softens +in boiling water, and may be moulded or pressed. Its specific gravity +varies slightly with its composition and with the degree of pressure it +has received. It is usually 1.35. It appears to be merely a mixture of its +components, since by treatment with appropriate solvents the camphor may +be readily extracted, and on heating the pyroxyline burns away while the +camphor volatilises. + +The manufacture of pyroxyline for the purpose of making celluloid has very +much increased during recent years, and with this increase of production +improved methods of manufacture have been invented. A series of +interesting papers upon the manufacture of pyroxyline has been published +by Mr Walter D. Field, of New York, in the _Journal of the American +Chemical Society_[A] from which the following particulars are taken:-- + +[Footnote A: Vol. xv., No. 3, 1893; Vol. xvi., No. 7, 1894; Vol. xvi., No. +8, 1894. Figs. 19, 20, 21, 22, and 23 are taken from Mr Field's paper.] + +~Selection of the Fibre.~--Cotton fibre, wood fibre, and flax fibre in the +form of raw cotton, scoured cotton, paper, and rags are most generally +used, and give the best results. As the fibres differ greatly in their +structure, they require different methods of nitrating. The cotton fibre +is a flattened hollow ribbon or collapsed cylindrical tube, twisted a +number of times, and closed at one end to form a point. The central canal +is large, and runs nearly to the apex of the fibre. Its side walls are +membraneous, and are readily penetrated by the mixed acids, and +consequently the highest nitration results. In the flax fibre the walls +are comparatively thick, the central canal small; hence it is to be +presumed that the nitration must proceed more slowly than in the case of +cotton. The New Zealand flax gives the most perfectly soluble nitrates of +any of the flaxes. Cotton gives a glutinous collodion, and calico a fluid +collodion. One of the largest manufacturers of pyroxyline in the States +uses the "Memphis Star" brand of cotton. This is an upland cotton, and its +fibres are very soft, moist, and elastic. Its colour is light creamy +white, and is retained after nitration. The staple is short, and the twist +inferior to other grades, the straight ribbon-like filaments being quite +numerous. This cotton is used carded, but not scoured. This brand of +cotton contains a large quantity of half and three-quarter ripe fibre, +which is extremely thin and transparent, distributed throughout the bulk +of the cotton (Monie., Cotton Fibre, 67). Mr Field says, "This is a +significant fact when it is known that from this cotton an extremely +soluble pyroxyline can be produced." + +Pyroxyline of an inferior grade as regards colour only can be produced +from the cotton wastes of the trade. They must be scoured before they are +fit for nitrating. Paper made from the pulps of sulphite and sulphate +processes is capable of yielding a very soluble pyroxyline. It can be +nitrated at high temperatures and still yield good results. Tissue paper +made from flax fibre is also used after being cut into squares. + +Mowbray (U.S.P., No. 443, 105, 3rd December 1890) says that a pure cotton +tissue paper less than 1/500 inch in thickness, thin as it is, takes on a +glutinous or colloid surface, and thus requires some thirty minutes to +enable the nitration to take place. With a thicker paper only the surface +would be nitrated. He therefore uses a fibre that has been saturated with +a solution of nitrate of soda, and afterwards dried slowly, claiming that +the salt crystallises in the fibre, or enters by the action termed osmose, +and opens up the fibre to the action of the acid. This process would only +be useful when the cotton is to be nitrated at a low temperature. At a +high temperature it would be unnecessary. + +Dietz and Wayne (U.S.P., No. 133, 969) use ramie, rheca, or China grass +for producing a soluble pyroxyline. That made from ramie is always of +uniform strength and solubility, and requires a smaller quantity of +solvent to dissolve it than that made from cotton. Mr Field's experience, +however, is entirely contrary to this statement. Such is the influence of +the physical form of the fibre on the process of nitration, that when flax +fibre and cotton fibre are nitrated with acid mixtures of exactly the same +strength, and at the same temperature, the solution of the first is +glutinous or thick, and the second fluid or thin. By simply nitrating at a +higher temperature than the cotton, the flax will yield a pyroxyline +giving an equally fluid collodion. + +The presence of chlorine in the fibre must be carefully avoided, as such a +fibre will yield an acid product which cannot be washed neutral. The fibre +must be dry before nitration; and this is best done, according to Mr +Field, by using the form of drier used in drying wool. + +~Nitration of the Fibre.~--Mixed cotton and flax fibre in the form of +paper, from 2/1000 to 3/1000 inch thick, and cut into 1-inch squares, is +nitrated by the Celluloid Manufacturing Company, and the same paper, left +in long strips, 1 inch wide, is used for nitration by the Xylonite +Manufacturing Company, of North Adams, Mass. (U.S.A.). + +The Celluloid Company introduce the cut paper into the mixed acids by +means of a hollow, rapidly revolving tube, flared at the lower end, and +immersed in the mixed acids. The centrifugal force of the revolving tube +throws the paper towards the sides of the vessel, leaving the centre of +the vessel ready for fresh paper. + +The Xylonite Company simply cut the paper into long strips, and introduce +it into the mixed acids by means of forks. The arrangement used by this +Company for holding the mixed acids is a cylindrical vessel divided into a +number of sections, the whole revolving like a turntable, thus allowing +the workman to nitrate successively each lot of paper at a given point. +This Company did not remove the acid from the paper after its immersion, +but plunged it immediately into the water, thus losing a large proportion +of the waste acid. The Celluloid Company, by using the paper in smaller +pieces, and more paper to a pound of acid, and wringing the mixed acid +from the paper before immersion in water, had a better process of +nitration. + +Other manufacturers use earthenware vessels, and glass or steel rods, +hooked at one end, having small pieces of rubber hose pulled over the +other end to prevent the hand from slipping. The form of vessel in general +use is that given in Fig. 23. It is large enough to nitrate 1 lb. of +cotton at a time. The hook at one end of the rod enables the workman to +pull the pyroxyline apart, and thus ensures saturation of the fibre. In +the winter the room in which the nitrating is done must be kept at a +temperature of about 70 deg. F. in order to secure equality in the batches. + +[Illustration: FIG. 23.--VESSEL FOR NITRATING COTTON OR PAPER.] + +The nitrating apparatus of White and Schupphaus (U.S.P., No. 418, 237, 89) +Mr Field considers to be both novel and excellent. The cage (Fig. 24), +with its central perforated cylinder (Fig. 25), is intended to ensure the +rapid and perfect saturation of the tissue paper used for nitrating. The +patentees say that no stirring is required with their apparatus. This, +says Mr Field, might be true when paper is used, or even cotton, when the +temperature of nitration is from 30 deg. to 35 deg. C., but would not be true if +the temperature were raised to 50 deg. to 55 deg. C. The process is as follows:-- +The paper is nitrated in the cage (Fig. 25), the bottom of which is formed +by the flanged plate C, fastened to the bottom of the internal cylinder B. +After nitration the cage is carried to a wringer, which forms the basket, +and the acids removed. Finally, the cage is taken to a plunge tank, where +the paper is removed from the cage by simply pulling out the central +perforated cylinder B. Fig. 26 shows the nitrating pot, with its automatic +cover. The plunge tank is shown in plan and section in Figs. 28 and 29. +This apparatus is suitable for the nitration of cotton fibre in bulk at +high or low temperatures. Other methods that have been patented are +Mowbray's (U.S.P., No. 434, 287), in which it is proposed to nitrate paper +in continuous lengths, and Hyatt's (U.S.P., No. 210, 611). + +[Illustration: FIG. 24.--CENTRAL PERFORATED CYLINDER.] + +[Illustration: FIG. 25.--THE CAGE. WHITE AND SCHUPPHAUS' NITRATING +APPARATUS.] + +[Illustration: FIG. 26.--CELLULOID NITRATING POT.] + +[Illustration: FIG. 27.--ANOTHER VIEW.] + +[Illustration: FIGS. 28, 29.--PLUNGE TANK, IN PLAN AND SECTION.] + +~The Acid Mixture.~--Various formulae have been published for producing +soluble nitro-cellulose. In many instances, although the observations were +correct for the single experiment, a dozen experiments would have produced +a dozen different products. The composition of the acids used depends upon +the substance to be nitrated, and the temperature at which the nitration +will be worked. Practically there are three formulae in general use--the +one used by the celluloid manufacturers; another in which the cotton is +nitrated at high temperatures; and a third in which the temperature of the +immersion is low, and the time of nitration about six hours. Of the three, +the best method is the last one, or the one in which the cotton is +immersed at a low temperature, and then the reaction allowed to proceed in +pots holding from 5 to 10 lbs. of cotton. The formula used by the +celluloid manufacturers for the production of the low form of nitrated +product which they use is:-- + +Sulphuric acid 66 parts by weight. +Nitric acid 17 " " +Water 17 " " + +Temperature of immersion, 30 deg. C. Time, twenty to thirty minutes. + +The cellulose is used in the form of tissue paper 2/1000 inch thick, 1 lb. +to 100 of acid mixture. The nitro-cellulose produced by this formula is +very insoluble in the compound ethers and other solvents of pyroxyline, +and is seemingly only converted or gelatinised by the action of the +solvent. The next formula produces a mixture of tetra-and penta-nitro- +celluloses hardly soluble in methyl-alcohol (free from acetone), but very +soluble in anhydrous compound ethers, ketones, and aldehydes:-- + +Nitric acid, sp. gr. 1.435 8 lbs. +Sulphuric acid, sp. gr. 1.83 15-3/4 lbs. +Cotton 14 oz. + +Temperature of nitration, 60 deg. C. Time of immersion, forty-five minutes. + +The 60 deg. of temperature is developed by mixing the acids together. The +cotton is allowed to remain in the acid until it feels "short" to the rod. + +The following table, due to Mr W.D. Field, shows very plainly the great +variation in the time of the immersion and the temperature by seemingly +very slight causes. It extends over fourteen working days, during which +time it rained four days. The formula used is that given above, except +that the specific gravity of the nitric acid is somewhat lower. The +product obtained differs only from that produced by using nitric acid of +specific gravity 1.43 in being soluble in methyl-alcohol. From 30 to 35 +lbs. of pyroxyline were produced in each of the fourteen days. + +A careful examination of this table will prove very instructive. The +increase in yield varies from 31 per cent. to nothing, and the loss runs +as high as 10 per cent., yet care was taken to make the product uniform in +quality. On the days it rained there was a loss, with the exception of the +fourth day, when there was neither a loss nor a gain. On the days it was +partly clear, as just before or after rain, the table shows a loss in +product. We can explain this fact by reason of the moisture-absorbing +qualities of the cotton. On the rainy days it would absorb the moisture +from the air until, when immersed in the acids, they were weakened, and +the fibre dissolved more or less in weakened acid, producing what is known +as "burning" in the batch. It will also be noticed that on days which show +a loss, the time of the immersion was correspondingly short, as on the +a loss, the time of the immersion was correspondingly short, as on the +tenth, twelfth, and seventh days. + + ______________________________________________________________________ +| | | | +| | Specific Gravity. | Time. | +| |_____________________|_______________________________| +| | | | | | | | +| |H_{2}S0_{4}.|HNO_{3}.|Hours.|Minutes.|Hours.|Minutes.| +|________________|____________|________|______|________|______|________| +| | | | | | | | +| 1. Clear | 1.838 | 1.4249 | ... | 20 | 4 | ... | +| 2. " | 1.837 | 1.4249 | ... | 20 | 2 | ... | +| 3. Cloudy | 1.837 | 1.4226 | ... | 45 | 2 | ... | +| 4. Rain | 1.837 | 1.420 | ... | 20 | 1 | 20 | +| 5. Clear | 1.8377 | 1.42 | 1 | 15 | 2 | ... | +| 6. Rainy | 1.8391 | 1.422 | ... | 35 | 1 | 40 | +| 7. Cloudy | 1.835 | 1.4226 | ... | 20 | ... | 35 | +| 8. Clear | 1.835 | 1.422 | ... | 35 | 1 | 10 | +| 9. Partly Clear| 1.824 | 1.4271 | ... | 20 | 1 | ... | +|10. " | 1.83 | 1.4271 | ... | 10 | ... | 25 | +|11. Cloudy | 1.832 | 1.425 | ... | 10 | ... | 50 | +|12. Rainy | 1.822 | 1.425 | ... | 10 | ... | 20 | +|13. Partly CLear| 1.8378 | 1.4257 | ... | 60 | 1 | 40 | +|14. Cloudy | 1.837 | 1.4257 | 1 | 56 | 4 | 40 | +|________________|____________|________|______|________|______|________| +| | | | +| |Temp., Deg. C. | Percentage | +| |_______________|___________________| +| | | | | | +| | From | To | Increase. | Loss. | +|________________|_______|_______|___________|_______| +| | | | | | +| 1. Clear | 57 deg. | 62 deg. | 31 | ... | +| 2. " | 60 deg. | 62 deg. | 18 | ... | +| 3. Cloudy | 60 deg. | 62 deg. | 7 | ... | +| 4. Rain | 60 deg. | 63 deg. | 0 | 0 | +| 5. Clear | 58 deg. | 62 deg. | 15 | ... | +| 6. Rainy | 58 deg. | 62 deg. | ... | 2 | +| 7. Cloudy | 62 deg. | 65 deg. | ... | 10 | +| 8. Clear | 60 deg. | 62 deg. | 5 | ... | +| 9. Partly Clear| 50 deg. | 60 deg. | ... | 3 | +|10. " | 58 deg. | 60 deg. | ... | 10 | +|11. Cloudy | 58 deg. | 60 deg. | 8 | ... | +|12. Rainy | 58 deg. | 60 deg. | ... | 10 | +|13. Partly CLear| 50 deg. | 58 deg. | 20 | ... | +|14. Cloudy | 50 deg. | 60 deg. | 16 | ... | +|________________|_______|_______|___________|_______| + +The lesson this table teaches is, that it is almost impossible to nitrate +cellulose in small quantities, and get uniform results, when the nitration +is carried on at high temperatures. As regards the solubility of +pyroxyline, Parks found that nitro-benzene, aniline, glacial acetic acid, +and camphor, dissolved in the more volatile solvents methyl-alcohol and +alcohol-ether, were much the best solvents for producing a plastic, as +they are less volatile, and develop greater solvent action under the +influence of heat. Nitro-benzene gives a solution that is granular; it +seems to merely convert the pyroxyline, and not to dissolve it; but on the +addition of alcohol, a solution is at once obtained, and the granular +appearance disappears, and the solution becomes homogeneous. The acid +mixture and the method of nitrating have much to do with the action of the +various solvents, so also has the presence of water. + +Dr Schupphaus found that propyl and isobutyl alcohols with camphor were +active solvents, and the ketones, palmitone, and stearone in alcohol +solution, also alpha- and beta-naphthol, with alcohol and anthraquinone +(diphenylene diketone) in alcoholic solution, and also iso-valeric +aldehyde and its derivatives, amyliden-dimethyl and amyliden-diethyl +ethers. + +August Sayer (U.S.P., No. 470,451) finds diethyl-ketone, dibutyl-ketone, +di-pentyl-ketone, and the mixed ketones,[A] methyl-ethyl, methyl-propyl, +methyl-butyl, methyl-amyl, and ethyl-butyl ketones are active solvents of +pyroxyline; and Paget finds that although methyl-amyl oxide is a solvent, +that ethyl-amyl oxide is not. + +[Footnote A: Ketones are derived from the fatty acids by the substitution +of the hydroxyl of the latter by a monad positive radical. They thus +resemble aldehydes in constitution. The best-known ketone is acetone +CH_{3}CO.CH_{3}. Mixed ketones are obtained by distilling together salts +of two different fatty acids. Thus potassic butyrate and potassic acetate +form propyl-methyl-ketone-- + +C(C_{2}H_{5})H_{2} +| +CO.CH_{3}] + +The solvents of pyroxyline can be divided into general classes--First, +those which are solvents without the aid of heat or solution in alcohol; +second, those that are solvents when dissolved in alcohol. These solvents +are those which also develop a solvent action when heated to their melting +point in combination with pyroxyline. + +Mr W.D. Field groups the solvents of pyroxyline into classes thus: Two of +the monohydric alcohols; compound ethers of the fatty acids with +monohydric alcohols, aldehydes; simple and mixed ketones of the fatty acid +series. These four classes include the greater number of the solvents of +pyroxyline. Those not included are as follows:--Amyl-nitrate and nitrite, +methylene-di-methyl ether, ethidene-diethyl ether, amyl-chloracetate, +nitro-benzene and di-nitro-benzene, coumarin, camphor, glacial acetic +acid, and mono-, di-, and tri-acetin. + +Richard Hale uses the following solvent:--Amyl-acetate, 4 volumes; +petroleum naphtha, 4 volumes; methyl-alcohol, 2 volumes; pyroxyline, 4 to +5 ounces to the gallon of solvent. Hale used petroleum naphtha to hasten +the drying qualities of the varnish, so that it would set on the article +to be varnished before it had a chance to run off. It is, however, the +non-hygroscopic character of the solvent that makes the varnish +successful. This formula is very largely used for the production of +pyroxyline varnish, which is used for varnishing pens, pencils, &c., also +brass-work and silver-ware. + +The body known as oxy-cellulose[A] is formed by the action of nitric acid +upon cellulose when boiled with it. The quantity formed is about 30 per +cent. of cellulose acted upon. When washed free from acid, it gelatinises. +It is then soluble in dilute alkalies, and can be reprecipitated from +solution by alcohol, acids, or saline solutions. Messrs Cross and Bevan +assign to it the formula C_{18}H_{26}O_{16}. It dissolves in concentrated +sulphuric acid, and with nitric acid forms a nitro body of the formula +C_{18}H_{23}O_{16}3(NO_{2}), which is prepared as follows:--The gelatinous +oxy-cellulose is washed with strong nitric acid until free from water, and +is then diffused through a mixture of equal volumes of strong sulphuric +and nitric acids, in which it quickly dissolves. The solution, after +standing for about an hour, is poured in a fine stream into a large volume +of water, by which the "nitro" body is precipitated as a white flocculent +mass. The product, after drying at 110 deg. C., was found upon analysis to +contain 6.48 per cent. nitrogen. + +[Footnote A: "On the Oxidation of Cellulose," by C.F. Cross and E.J. +Bevan, _Jour. Chem. Soc._, 1883, p. 22.] + +MISCELLANEOUS NITRO-EXPLOSIVES. + +~Nitro-Starch.~--It is only recently that, by means of the process +introduced by the "Actiengesellschaft Dynamit Nobel," it has been possible +to make this explosive upon the manufacturing scale. Nitro-starch has been +known since 1883, when Braconnot discovered it, and called it xyloidine. +Its formula is C_{6}H_{8}O_{3}(NO_{3})_{2}, but Dr Otto Muehlhaeusen has +lately succeeded in preparing higher nitrated compounds, viz.:-- + +(_a._) C_{6}H_{7-1/2}O_{2-1/2}(NO_{3})_{2-1/2}. + +(_b._) C_{6}H_{7}O_{4}(NO_{3})_{3}. + +Or doubling the molecule of starch:-- + + Nitrogen. + i. Tetra-nitro-starch C_{12}H_{16}O_{6}(ONO_{2})_{4} 11.11 per cent. + ii. Penta-nitro-starch C_{12}H_{15}O_{5}(ONO_{2})_{5} 12.75 " +iii. Hexa-nitro-starch C_{12}H_{14}O_{4}(ONO_{2})_{6} 14.14 " + +He regards them as true ethers (esters) of nitric acid. Thus on treatment +with sulphuric acid, these compounds yield NO_{3}H, the residue O.NO_{2} +thus appearing to be replaced by the sulphuric acid residue. On treatment +with a solution of ferrous chloride, nitric oxide and "soluble" starch are +regenerated. On shaking with sulphuric acid over mercury, all the nitrogen +is split off as NO. + +Tetra-nitro-starch is prepared upon the large scale as follows:--A +quantity of potato-starch is taken and exposed in some suitable +desiccating apparatus at a temperature of 100 deg. C. until all the moisture +which it contains is completely driven off. It is then reduced to a fine +powder by grinding, and dissolved in nitric acid of specific gravity +1.501. The vessel in which this solution is accomplished is made of lead, +and must be provided with two jackets, cooled by means of water. It should +further be fitted with a screw-agitator, in order to keep the nitric acid +circulating freely. The charge of starch is introduced through an opening +in the cover of this digesting vessel, and the proportions of acid to +starch are 10 kilogrammes of starch to 100 kilos. of acid. The temperature +is kept within the limits 20 deg. to 25 deg. C. When the solution of the starch is +complete, the liquid is conducted into a precipitating apparatus, which is +also provided with a cooling jacket, for the purpose of regulating the +temperature. The bottom of this vessel is double and perforated, and here +is placed a layer of gun-cotton to act as a filter. This vessel is filled +with spent nitro-sulphuric acid obtained as a waste product from the +nitro-glycerine manufactory, and the solution of starch in nitric acid is +sprayed into it through an injector worked by compressed air, whereby the +nitro-starch is thrown down in the form of a fine-grained powdery +precipitate. + +In order to precipitate 100 kilos. of the acid solution of starch, it is +necessary to employ 500 kilos. of spent nitro-sulphuric acid. As it is +precipitated the nitro-starch collects on the gun-cotton filter, and the +acid liquor is run off through a tap placed beneath the perforated double +bottom of the vessel, and of course below the filter pad. The precipitated +starch is further cleansed from acid by repeated washings and by pressure, +until all trace of acidity has been eliminated, and the substance exhibits +a neutral reaction. The next step is to treat the nitro-starch with a 5 +per cent. solution of soda, in contact with which it is allowed to stand +for at least twenty-four hours. The product is then ground up until a sort +of "milk" or emulsion is obtained, and lastly treated with a solution of +aniline, so that when pressed into cake, it contains about 33 per cent. of +water, and 1 per cent. of aniline. + +Dr Muehlhaeusen, working on these lines in the laboratory, prepared nitro- +starch which contained 10.96 and 11.09 per cent. of nitrogen. When in the +state of powder it is snow-white in colour; it becomes electrified when +rubbed; it is very stable, and soluble even in the cold in nitro- +glycerine. He has also prepared a tetra-nitro-starch containing 10.58 and +10.50 per cent. of nitrogen, by pouring water into a solution of starch in +nitric acid which had stood for several days. The substance thus produced +in the laboratory had all the properties of that prepared by the other +process. + +The production of penta-nitro-starch is effected by adding 20 grms. of +rice-starch--previously dried at a temperature of 100 deg.C., in order to +eliminate all moisture--to a mixture of 100 grms. of nitric acid, specific +gravity 1.501, and 300 grms. of sulphuric acid, specific gravity 1.8 (some +tetra-nitro-starch is also formed at the same time). After standing in +contact with these mixed acids for one hour the starch has undergone a +change, and the mass may now be discharged into a large quantity of water, +and then washed, first with water, and finally with an aqueous solution of +soda. The yield in Dr Muehlhaeusen's experiments was 147.5 per cent. + +The substance thus formed is now heated with ether-alcohol, the ether is +distilled off, and the penta-nitro-starch appears as a precipitate, whilst +the tetra-nitro-starch, which is formed simultaneously, remains in +solution in the alcohol. As obtained by this process, it contained 12.76 +and 12.98 per cent. nitrogen, whilst the soluble tetra-nitro-starch +contained 10.45 per cent. + +Hexa-nitro-starch is the product chiefly formed when 40 grms. of dry +starch are treated with 400 grms. of nitric acid, specific gravity 1.501, +and allowed to stand in contact for twenty-four hours; 200 grms. of this +mixture are then poured into 600 c.c. of sulphuric acid of 66 deg. B. The +result of this manipulation is a white precipitate, which contains +13.52-13.23 and 13.22 per cent. nitrogen; and consists, therefore, of a +mixture of penta- and hexa-nitro-starch. + +The experiments undertaken with these substances demonstrated that those +prepared by precipitating the nitro-starch with strong sulphuric acid were +less stable in character or properties than those which were precipitated +by water or weak sulphuric acid. Dr Muehlhaeusen is of opinion that possibly +in the former case a sulpho-group may be formed, which in small quantity +may occasion this instability. + +The following table shows the behaviour of these substances prepared in +different ways and under various conditions:-- + + __________________________________________________________________ +| | | +| | SAMPLES. | +| |____________________________________________| +| | | | | | | +| | A. | B. | C. | D. | E. | +| Ignition-point |175 deg. C. |170 deg. C. |152 deg. C. |121 deg. C. |155 deg. C. | +| Stability |Stable |Stable |Unstable|Unstable|Unstable| +| Per cent. of N. | 11.02 | 10.54 | 12.87 | 12.59 | 13.52 | +| 96 per cent. alcohol| Sol. | Sol. | Insol. | Insol. | Insol. | +| Ether | Insol. | Insol. | Insol. | Insol. | Insol. | +| Ether-alcohol | Sol. | Sol. | Sol. | Sol. | Sol. | +| Acetic Ether | Sol. | Sol. | Sol. | Sol. | Sol. | +|_____________________|________|________|________|________|________| + +These samples were prepared as follows:-- + +A. From 1 part nitric acid and 2 parts sulphuric acid (containing 70 per + cent. H_{2}O). +B. From 1 part nitric acid and water. +C. From 1 part nitric and 3 parts H_{2}SO_{4} (con.). +D. From 1 part nitric and 3.5 parts con. H_{2}SO_{4}. +E. From 1 part nitric and 3 parts con. H_{2}SO_{4}. + +Dr Muehlhaeusen is of opinion that these compounds may be turned to +practical account in the production of good smokeless powder. He +recommends the following proportions and method. Six grms. of nitro-jute +and 2 grms. of nitro-starch are mixed together, and moistened with acetic +ether. These ingredients are then worked together into a uniform mass, and +dried at a temperature ranging between the limits 50 deg. to 60 deg. C. He has +himself prepared such a smokeless powder, which proved to contain 11.54 +per cent. of nitrogen, and was very stable. Further details of Dr +Muehlhaeusen's work upon nitro-starch can be found in _Dingler's +Polytechnisches Journal_, paper "Die hoehren Salpetersaeureaether der +Staerke," 1892, Band 284, s. 137-143, and a Bibliography up to 1892 in +_Arms and Explosives_, December 1892. + +M. Berthelot gives the heat of formation of nitro-starch as 812 cals. for +1 grm., and the heat of total combustion as equal to 706.5 cals. for 207 +grms., or for 1 grm. 3,413 cals. The heat of decomposition could only be +calculated if the products of decomposition were given, but they have not +as yet been studied, and the quantity of oxygen contained in the compound +is far from being sufficient for its complete combustion. Berthelot and +Vieille found the average velocities for nitro-starch powder, density of +charge about 1.2, in a tin tube 4 mm. external diameter, to be, in two +experiments, 5,222 m. and 5,674 m. In a tin tube 5.5 mm. external +diameter, the velocity was 5,815 m., and in lead tube 5,006 m. (density +1.1 to 1.2). The starch powder is hygroscopic, and is insoluble in water +and alcohol. When dry it is very explosive, and takes fire at about 350 deg. +F. Mr Alfred Nobel has taken out a patent (Eng. Pat. No. 6,560, 88) for +the use of nitro-starch. His invention relates to the treatment of nitro- +starch and nitro-dextrine, for the purpose of producing an explosive +powder, to be used in place of gunpowder. He incorporates these materials +with nitro-cellulose, and dissolves the whole in acetone, which is +afterwards distilled off. A perfect incorporation of the ingredients is +thus brought about. + +~Nitro-Jute.~--It is obtained by treating jute with nitric acid. Its +properties have been studied by Messrs Cross and Bevan (_Jour. Chem. +Soc._, 1889, 199), and by Muehlhaeusen. The latter used for its nitration an +acid mixture composed of equal parts of nitric and sulphuric acids, which +was allowed to act upon the jute for some time. He found that with long +exposure, i.e., from three to four hours in the acids, there was a +disintegrating of the fibre-bundles, and the nitration was attended by +secondary decomposition and conversion into products soluble in the acid +mixture. Cross and Bevan's work upon this subject leads them to conclude +that the highest yield of nitrate is represented by an increase of weight +of 51 per cent. They give jute the empirical formula C_{12}H_{18}O_{9} (C += 47 per cent. H = 6 per cent., and O = 47 per cent.), and believe its +conversion into a nitro compound to take place thus:-- + +C_{12}H_{18}O + 3HNO_{3} = C_{12}H_{15}O_{6}(NO_{3})_{3} + 3H_{2}O. + +This is equivalent to a gain in weight of 44 per cent. for the tri- +nitrate, and of 58 per cent. for the tetra-nitrate. The formation of the +tetra-nitrate appears to be the limit of nitration of jute-fibre. In other +words, if we represent the ligno-cellulose molecule by a C_{12} formula, +it will contain four hydroxyl (OH) groups, or two less than cellulose +similarly represented. The following are their nitration results:-- + +Acids used.--I. HNO_{3} sp. gr. 1.43, and H_{2}SO_{4} = 1.84 equal parts. + II. 1 vol. HNO_{3}(1.5), 1 vol. H_{2}SO_{4}(1.84). + III. 1 vol. HNO_{3}(1.5), 75 vols. H_{2}SO_{4}(1.84). + +I. = 144.4; II. = 153.3; III. = 154.4 grms.; 100 grms. of fibre being used +in all three cases. + +Duration of exposure, thirty minutes at 18 deg. C. + +The nitrogen was determined in the products, and equalled 10.5 per cent. +Theory for C_{12}H_{15}O_{6}(NO_{3})_{3} = 9.5 per cent. and for +C_{12}H_{15}O_{6}(NO_{3})_{4} = 11.5 per cent. These nitrates resemble +those of cellulose, and are in all essential points nitrates of ligno- +cellulose. + +Muehlhaeusen obtained a much lower yield, and probably, as pointed out by +Cross and Bevan, a secondary decomposition took place, and his products, +therefore, probably approximate to the derivatives of cellulose rather +than to those of ligno-cellulose, the more oxidisable, non-cellulose, or +lignone constituents having been decomposed. In fact, he regards his +product as cellulose penta-nitrate (C_{12}H_{16}O_{5}(ONO_{2})_{5}). The +_Chemiker Zeitung_, xxi., p. 163, contains a further paper by Muehlhaeusen +on the explosive nitro-jute. After purifying the jute-fibre by boiling it +with a 1 per cent. solution of sodium carbonate, and washing with water, +he treated 1 part of the purified jute with 15 parts of nitro-sulphuric +acid, and obtained the following results with different proportions of +nitric to sulphuric acids:-- + + Yield Ignition Nitrogen. + per cent. Point. +Experiment I.-- 1. HNO_{3} 1. H_{2}SO_{4} 129.5 170 deg. C. 11.96% + " II. " 2. " 132.2 167 deg. C. 12.15% + " III. " 3. " 135.8 169 deg. C. 11.91% + +An experiment made with fine carded jute and the same mixture of acids as +in No. II. gave 145.4 per cent. nitro-jute, which ignited at 192 deg. C., and +contained 12 per cent. nitrogen. This explosive is not at present +manufactured upon the large scale, and Messrs Cross and Bevan are of +opinion that there is no very obvious advantage in the use of lignified +textile fibre as raw materials for explosive nitrates, seeing that a large +number of raw materials containing cellulose (chiefly as cotton) can be +obtained at a cheaper rate, and yield also 150 to 170 per cent. of +explosive material when nitrated, and are in many ways superior to the +products obtained hitherto from jute. + +~Nitro-mannite~ is formed by the action of nitric acid on mannite, a +hex-acid alcohol closely related to sugar. It occurs abundantly in manna, +which is the partly dried sap of the manna-ash (_Fraxinus ornus_). It is +formed in the lactic acid fermentation of sugar, and by the action of +nascent hydrogen on glucose and cellulose, or on invert sugar. Its formula +is C_{6}H_{8}(OH)_{6} and that of nitro-mannite C_{6}H_{8}(NO_{3})_{6}. +Mannite crystallises in needles or rhombic prisms, which are soluble in +water and alcohol, and have a sweet taste. Nitro-mannite forms white +needle-shaped crystals, insoluble in water, but soluble in ether or +alcohol. When rapidly heated, they ignite at about 374 deg. F., and explode at +about 590 deg. F. It is more susceptible to friction and percussion than +nitro-glycerine, and unless pure it is liable to spontaneous +decomposition. It is considered as the nitric ether of the hexatomic +alcohol mannite. It is formed by the action of a mixture of nitric and +sulphuric acids upon mannite-- + +C_{6}H_{8}(OH)_{6} + 6HNO_{3} = C_{6}H_{8}(NO_{3})_{6} + 6H_{2}O. + +Its products of explosion are as shown in the following equation:-- + +C_{6}H_{8}(OH)_{6} = 6CO_{2} + 4H_{2}O + 3N_{2} + O_{2}. + +Its percentage composition is as follows:--Carbon, 15.9 per cent.; +hydrogen, 1.8 per cent.; nitrogen, 18.6 per cent.; and oxygen, 63.7 per +cent. Its melting point is 112 to 113 deg. C., and it solidifies at 93 deg.. When +carefully prepared and purified by recrystallisation from alcohol, and +kept protected from sunlight, it can be kept for several years without +alteration. + +Nitro-mannite is more dangerous than nitro-glycerine, as it is more +sensitive to shock. It is intermediate in its shattering properties +between nitro-glycerine and fulminate of mercury. It explodes by the shock +of copper on iron or copper, and even of porcelain on porcelain, provided +the latter shock be violent. Its heat of formation from its elements is ++156.1 calories. It is not manufactured upon the commercial scale. + +Besides the nitro compounds already described, there are many others, but +they are of little importance, and are none of them made upon the large +scale. Among such substances are _nitro-coal_, which is made by the action +of nitric acid on coal; _nitro-colle_, a product which results from the +action of nitric acid on isinglass or gelatine, soaked in water. It is +then treated with the usual acids. + +Another method is to place strong glue in cold water until it has absorbed +the maximum amount of the latter. The mixture is solidified by the +addition of nitric acid, nitrated in the usual way, and well washed. +Abel's _Glyoxiline_ is only nitrated gun-cotton impregnated with nitro- +glycerine. Nitro-lignine is only nitro-cellulose made from wood instead of +cotton; and nitro-straw is also only nitro-cellulose. The explosive known +as _Keil's Explosive_ contains nitro-glucose. Nitro-molasses, which is a +liquid product, has also been proposed, and nitro-saccharose, the product +obtained by the nitration of sugar. It is a white, sandy, explosive +substance, soluble in alcohol and ether. When made from cane sugar, it +does not crystallise; but if made from milk sugar, it does. It has been +used in percussion caps, being stronger and quicker than nitro-glycerine. +It is, however, very sensitive and very hygroscopic, and very prone to +decomposition. Nitro-tar, made from crude tar-oil, by nitration with +nitric acid of a specific gravity of 1.53 to 1.54. Nitro-toluol is used, +mixed with nitro-glycerine. This list, however, does not exhaust the +various substances that have been nitrated and proposed as explosives. +Even such unlikely substances as horse dung have been experimented with. +None of them are very much used, and very few of them are made upon the +manufacturing scale. + + + + +CHAPTER IV. + +_DYNAMITE AND GELATINES._ + +Kieselguhr Dynamite--Classification of Dynamites--Properties and +Efficiency of Ordinary Dynamite--Other Forms of Dynamite--Gelatine and +Gelatine Dynamites, Suitable Gun-Cotton for, and Treatment of--Other +Materials used--Composition of Gelignite--Blasting Gelatine--Gelatine +Dynamite--Absorbing Materials--Wood Pulp--Potassium Nitrate, &c.-- +Manufacture and Apparatus used, and Properties of Gelatine Dynamites-- +Cordite--Composition and Manufacture. + + +~Dynamite.~--Dynamite consists of nitro-glycerine either absorbed by some +porous material, or mixed with some other substance or substances which +are either explosives or merely inert materials. Among the porous +substances used is kieselguhr, a silicious earth which consists chiefly of +the skeletons of various species of diatoms. This earth occurs in beds +chiefly in Hanover, Sweden, and Scotland. The best quality for the purpose +of manufacturing dynamite is that which contains the largest quantity of +the long tubular _bacillariae_, and less of the round and lancet-shaped +forms, such as _pleurosigmata_ and _diclyochae_, as the tube-shaped diatoms +absorb the nitro-glycerine better, and it becomes packed into the centre +of the silicious skeleton of the diatoms, the skeleton acting as a kind of +tamping, and increasing the intensity of the explosion. + +Dynamites are classified by the late Colonel Cundill, R.A., in his +"Dictionary of Explosives" as follows:-- + +1. Dynamites with an inert base, acting merely as an absorbent. + +2. Dynamites with an active base, i.e., an explosive base. No. 2 may be +again divided into three minor classes, which contain as base-- + +(_a._) Charcoal. + +(_b._) Gunpowder or other nitrate, or chlorate mixture. + +(_c._) Gun-cotton or other nitro compound (nitro-benzol, &c.). + +The first of these, viz., charcoal, was one of the first absorbents for +nitro-glycerine ever used; the second is represented by the well-known +Atlas powder; and the last includes the well-known and largely used +gelatine compounds, viz., gelignite and gelatine dynamite, and also tonite +No. 3, &c. + +In the year 1867 Nobel produced dynamite by absorbing the nitro-glycerine +in an inert substance, forming a plastic mass. In his patent he says: +"This invention relates to the use of nitro-glycerine in an altered +condition, which renders it far more practical and safe for use. The +altered condition of the nitro-glycerine is effected by causing it to be +absorbed in porous unexplosive substances, such as charcoal, silica, +paper, or similar materials, whereby it is converted into a powder, which +I call dynamite, or Nobel's safety powder. By the absorption of the nitro- +glycerine in some porous substance it acquires the property of being in a +high degree insensible to shocks, and it can also be burned over a fire +without exploding." + +Ordinary dynamite consists of a mixture of 75 per cent. of nitro-glycerine +and 25 per cent. of kieselguhr. The guhr as imported (Messrs A. Haake & +Co. are the chief importers) contains from 20 to 30 per cent. of water and +organic matter. The water may be very easily estimated by drying a weighed +quantity in a platinum crucible at 100 deg. C. for some time and re-weighing, +and the organic matter by igniting the residue strongly over a Bunsen +burner. Before the guhr can be used for making dynamite it must be +calcined, in order not only to get rid of moisture, but also the organic +matter. + +A good guhr should absorb four times its weight of nitro-glycerine, and +should then form a comparatively dry mixture. It should be pale pink, red +brown, or white. The pink is generally preferred, and it should be as free +as possible from grit of all kinds, quartz particles, &c., and should have +a smooth feeling when rubbed between the finger and thumb, and should show +a large quantity of diatoms when viewed under the microscope. The +following was the analysis of a dried sample of kieselguhr:--Silica, +94.30; magnesia, 2.10; oxide of iron and alumina, 1.3; organic matter, +0.40; moisture, 1.90 per cent. + +The guhr is generally dried in a reverberatory muffle furnace. It is +spread out on the bottom to the thickness of 3 or 4 inches, and should +every now and then be turned over and raked about with an iron rabble or +hoe. The temperature should be sufficiently high to make the guhr red hot, +or the organic matter will not be burnt off. The time occupied in +calcining will depend of course upon the quality of the guhr being +operated upon. Those containing a high percentage of water and organic +matter will of course take longer than those that do not. A sample of the +calcined guhr should not contain more than 0.5 per cent. of moisture and +organic matter together. + +After the guhr is dry it requires to be sifted and crushed. The crushing +is done by passing it between iron rollers fixed at the bottom of a cone +or hopper, and revolving at a moderate speed. Beneath the rollers a fine +sieve should be placed, through which the guhr must be made to pass. + +The kieselguhr having been dried, crushed, and sifted, should be packed +away in bags, and care should be taken that it does not again absorb +moisture, as if it contains anything above about five-tenths per cent. of +water it will cause the dynamite made with it to exude. The guhr thus +prepared is taken up to the danger area, and mixed with nitro-glycerine. +The nitro-glycerine used should be quite free from water, and clear, and +should have been standing for a day or two in the precipitating house. The +guhr and nitro-glycerine are mixed in lead tanks (about 1-1/2 foot deep, +and 2 to 3 feet long), in the proportions of 75 of the nitro-glycerine to +25 of the guhr, unless the guhr is found to be too absorbent, which will +cause the dynamite to be too dry and to crumble. In this case a small +quantity of barium sulphate, say about 1 per cent., should be added to the +guhr. This will lessen its absorbing powers, or a highly absorptive sample +of guhr may be mixed with one of less absorptive power, in the proportions +found by experiment to be the best suited to make a fairly moist dynamite, +but one that will not exude. + +The mixing itself is generally performed in a separate house. In a series +of lead-lined tanks the guhr is weighed, placed in a tank, and the nitro- +glycerine poured on to it. The nitro-glycerine may be weighed out in +indiarubber buckets. The whole is then mixed by hand, and well rubbed +between the hands, and afterwards passed through a sieve. At this stage +the dynamite should be dry and powdery, and of a uniform colour. + +It is now ready to be made up into cartridges, and should be taken over to +the cartridge huts. These are small buildings surrounded with mounds, and +contain a single cartridge machine. Each hut requires three girls--one to +work the press, and two to wrap up the cartridges. The cartridge press +consists of a short cylinder of the diameter of the cartridge that it is +intended to make. Into this cylinder a piston, pointed with ivory or +lignum vitae wood, works up and down from a spring worked by a lever. Round +the upper edge of the cylinder is fastened a canvas bag, into which the +powdery dynamite is placed by means of a wooden scoop, and the descending +piston forces the dynamite down the cylinder and out of the open end, +where the compressed dynamite can be broken off at convenient lengths. The +whole machine should be made of gun-metal, and should be upright against +the wall of the building. The two girls, who sit at tables placed on each +side of the press, wrap the cartridges in parchment paper. From these huts +the cartridges are collected by boys every ten minutes or a quarter of an +hour, and taken to the packing room, where they are packed in 5-lb. +cardboard boxes, which are then further packed in deal boxes lined with +indiarubber, and fastened down air tight. The wooden lids are then nailed +down with brass or zinc nails, and a label pasted on the outside giving +the weight and description of the contents. The boxes should then be +removed to the magazines. It is well to take a certain number of +cartridges from the packing house at different times during the day, say +three or four samples, and to test them by the heat test. A sample cut +from a cartridge, about 1 inch long, should be placed under a glass shade, +together with water (a large desiccator, in fact), and left for some days. +A good dynamite should not, under these conditions, show any signs of +exudation, even after weeks.[A] + +[Footnote A: For analysis of dynamite, see chapter on "Analysis," and +author's article in _Chem. News_, 23rd September 1892.] + +~Properties of Kieselguhr Dynamite.~--One cubic foot of dynamite weighs 76 +lbs. 4 oz. The specific gravity of 75 per cent. dynamite is, however, +1.50. It is a red or grey colour, and rather greasy to the touch. It is +much less sensitive to shock than nitro-glycerine, but explodes +occasionally with the shock of a rifle bullet, or when struck. The +addition of a few per cent. of camphor will considerably diminish its +explosive qualities to such an extent that it can be made non-explosive +except to a very strong fulminate detonator. The direct contact of water +disintegrates dynamite, separating the nitro-glycerine, hence great +caution is necessary in using it in wet places. It freezes at about 40 deg. +Fahr. (4 deg. C.), and remains frozen at temperatures considerably exceeding +that point. When frozen, it is comparatively useless as an explosive +agent, and must be thawed with care. This is best done by placing the +cartridges in a warming pan, which consists of a tin can, with double +sides and bottom, into which hot water (130 deg. Fahr.) can be poured. The +dynamite will require to be left in for some considerable time before it +becomes soft. On no account must it be placed on a hot stove or near a +fire, as many serious accidents have occurred in this way. + +Frozen dynamite is a hard mass, with altered properties, and requires 1.5 +grm. of fulminate instead of 0.5 grm. to explode it. Thawing may also +cause exudation of the nitro-glycerine, which is much more sensitive to +shock, and if accidentally struck with an iron tool, may explode. It is a +dangerous thing to cut a frozen cartridge with a knife. Ramming is even +more dangerous; in fact it is not only dangerous, but wasteful, to use +dynamite when in a frozen state. + +Dynamite explodes at a temperature of 360 deg. Fahr., and is very sensitive to +friction when hot. In hot countries it should never be exposed to the rays +of the sun. It should, however, not be kept in a damp or moist place, as +this is liable to cause exudation. Sunlight, if direct, can cause a slow +decomposition, as with all nitro and nitric compounds. Electric sparks +ignite, without exploding it, at least when operating in the open air. + +Dynamite, when made with neutral nitro-glycerine, appears to keep +indefinitely. Sodium or calcium carbonate to the extent of 1 per cent. is +often added to dynamite to ensure its being neutral. If it has commenced +to undergo change, however, it rapidly becomes acid, and sometimes +explodes spontaneously, especially if contained in resisting envelopes. +Nevertheless, neutral and well-made dynamite has been kept for years in a +magazine without loss of its explosive force. If water is brought into +contact with it, the nitro-glycerine is gradually displaced from the +silica (guhr). This action tends to render all wet dynamite dangerous. + +It has been observed that a dynamite made with wood sawdust can be +moistened and then dried without marked alteration, and from 15 to 20 per +cent. of water may be added to cellulose dynamite without depriving it of +the power of exploding by strong detonator (this is similar to wet +gun-cotton). It is, however, rendered much less sensitive to shock. With +regard to the power of No. 1 dynamite, experiments made in lead cylinders +give the relative value of No. 1 dynamite, 1.0; blasting gelatine, 1.4; +and nitro-glycerine, 1.4. The heat liberated by the sudden explosion of +dynamite is the same as its heat of combustion,[A] and proportionate to +the weight of nitro-glycerine contained in the mixture. The gases formed +are carbonic acid, water, nitrogen, and oxygen. + +[Footnote A: Berthelot, "Explosives and their Power."] + +The "explosive wave" (of Berthelot) for dynamite is about 5,000 metres per +second. At this rate the explosion of a cartridge a foot long would only +occupy 1/24000 part of a second, while a ton of dynamite cartridges about +7/8 diameter, laid end to end, and measuring one mile in length, would be +exploded in one-quarter of a second by detonating a cartridge at either +end.[A] Mr C. Napier Hake, F.I.C., the Inspector of Explosives for the +Victorian Government, in his paper, "Notes on Explosives," says: "The +theoretical efficiency of an explosive cannot in practice be realised in +useful work for several reasons, as for instance in blasting rock-- + +"1. Incomplete combustion. + +"2. Compression and chemical changes induced in surrounding material. + +"3. Energy expended in cracking and heating of the material which is not +displaced. + +"4. The escape of gas through the blast-hole and the fissures caused by +the explosion. + +"The useful work consists partly in displacing the shattered masses. The +proportion of useful work obtainable has been variously estimated at from +14 to 33 per cent. of the theoretical maximum potential." + +[Footnote A: C.N. Hake, "Notes on Explosives," _Jour. Soc. Chem. Ind._, +1889.] + +Among the various forms of dynamite that are manufactured is carbo- +dynamite, the invention of Messrs Walter F. Reid and W.D. Borland. The +base is nitro-glycerine, and the absorbent is carbon in the form of burnt +cork. It is as cheap as ordinary dynamite, and has greater explosive +force, seeing that 90 per cent. of the mixture is pure nitro-glycerine, +and the absorbent itself is highly combustible. It is also claimed that if +this dynamite becomes wet, no exudation takes place. + +Atlas powder is a dynamite, chiefly manufactured in America at the Repanno +Chemical Works, Philadelphia. It is a composition of nitro-glycerine, +wood-pulp, nitrate of soda, and carbonate of magnesia. This was the +explosive used in the outrages committed in London, by the so-called +"dynamiters." Different varieties contain from 20 to 75 per cent. of +nitro-glycerine. + +The Rhenish dynamite, considerably used in the mines of Cornwall, is +composed of 70 parts of a solution of 2 to 3 per cent. of naphthalene in +nitro-glycerine, 3 parts of chalk, 7 parts of sulphate of barium, and 20 +of kieselguhr. + +Kieselguhr dynamites are being largely given up in favour of gelatine +explosives. The late Colonel Cundill, in his "Dictionary of Explosives," +gives a list of about 125 kinds of dynamites. Many of these, however, are +not manufactured. Among the best known after the ordinary No. 1 dynamite +are forcite, ammonia dynamite, litho-fracteur, rendock, Atlas powder, +giant powder, and the various explosive gelatines. They all contain nitro- +glycerine, mixed with a variety of other substances, such as absorbent +earths, wood-pulp, nitro-cotton, carbon in some form or other, nitro- +benzol, paraffin, sulphur, nitrates, or chlorates, &c. &c. + +~Blasting Gelatine and Gelatine Dynamite.~--The gelatine explosives +chiefly in use are known under the names of blasting gelatine, gelatine +dynamite, and gelignite. They all consist of the variety of nitro- +cellulose known as collodion-cotton, i.e., a mixture of the penta- and +tetra-nitrates dissolved in nitro-glycerine, and made up with various +proportions of wood-pulp, and some nitrate, or other material of a similar +nature. As the gun-cotton contains too little oxygen for complete +combustion, and the nitro-glycerine an excess, a mixture of the two +substances is very beneficial. + +Blasting gelatine consists of collodion-cotton and nitro-glycerine without +any other substance, and was patented by Mr Alfred Nobel in 1875. It is a +clear, semi-transparent, jelly-like substance, of a specific gravity of +1.5 to 1.55, slightly elastic, resembling indiarubber, and generally +consists of 92 per cent. to 93 per cent. of nitro-glycerine, and 7 to 8 +per cent. of nitro-cotton. The cotton from which it is made should be of +good quality. The following is the analysis of a sample of nitro-cellulose +which made very good gelatine:- + +Soluble cotton 99.118 per cent. +Gun-cotton 0.642 " +Non-nitrated cotton 0.240 " +Nitrogen 11.64 " +Total ash 0.25 " + +The soluble cotton, which is a mixture of the tetra- and penta-nitrates, +is soluble in ether-alcohol, and also in nitro-glycerine, and many other +solvents, whereas the hexa-nitrate (gun-cotton), +C_{12}H_{14}O_{4}(ONO_{2})_{6}, is not soluble in the above liquids, +although it is soluble in acetone or acetic ether. It is very essential, +therefore, that the nitro-cotton used in the manufacture of the gelatine +explosives should be as free as possible from gun-cotton, otherwise little +lumps of undissolved nitro-cotton will be left in the finished gelatine. +The non-nitrated or unconverted cotton should also be very low, in fact +considerably under 1/2 per cent. + +The nitro-cotton and the nitro-glycerine used should always be tested +before use by the heat test, because if they do not separately stand this +test, it cannot be expected that the gelatine made from them will do so. +It often occurs, however, that although both the ingredients stand this +test separately before being mixed, that after the process of manufacture +one or other or both fail to do so. + +The nitro-cotton most suitable for gelatine making is that which has been +finely pulped. If it is not already fine enough, it must be passed through +a fine brass wire sieve. It will be found that it requires to be rubbed +through by hand, and will not go through at all if in the least degree +damp. It is better, therefore, to dry it first. The percentage of nitrogen +in the nitrated cotton should be over 11 per cent. It should be as free as +possible from sand or grit, and should give but little ash upon ignition, +not more than 0.25 per cent. The cotton, which is generally packed wet in +zinc-lined wooden boxes, will require to be dried, as it is very essential +indeed that none of the materials used in the manufacture of gelatine +should contain more than the slightest trace of water. If they do, the +gelatine subsequently made from them will most certainly exude, and become +dangerous and comparatively valueless. It will also be much more difficult +to make the nitro-cotton dissolve in the nitro-glycerine if either +contains water. + +In order to find out how long any sample of cotton requires to be dried, a +sample should be taken from the centre of several boxes, well mixed, and +about 1,000 grms. spread out on a paper tray, weighed, and the whole then +placed in the water oven at 100 deg. C., and dried for an hour or so, and +again weighed, and the percentage of moisture calculated from the loss in +weight. This will be a guide to the time that the cotton will probably +require to be in the drying house. Samples generally contain from 20 to 30 +per cent. of water. After drying for a period of forty-eight hours, a +sample should be again dried in the oven at 100 deg. C., and the moisture +determined, and so on at intervals until the bulk of the cotton is found +to be dry, i.e., to contain from 0.25 to 0.5 per cent. of moisture. It is +then ready to be sifted. During the process of removing to the sifting +house and the sifting itself, the cotton should be exposed to the air as +little as possible, as dry nitro-cotton absorbs as much as 2 per cent. of +moisture from the air at ordinary temperatures and average dryness. + +The drying house usually consists of a wooden building, the inside of +which is fitted with shelves, or rather framework to contain drawers, made +of wood, with brass or copper wire netting bottoms. A current of hot air +is made to pass through the shelves and over the surface of the cotton, +which is spread out upon them to the depth of about 2 inches. This current +of air can be obtained in any way that may be found convenient, such as by +means of a fan or Root's blower, the air being passed over hot bricks, or +hot-water pipes before entering the building. The cotton should also be +occasionally turned over by hand in order that a fresh surface may be +continually exposed to the action of the hot air. The building itself may +be heated by means of hot-water pipes, but on no account should any of the +pipes be exposed. They should all be most carefully covered over with +wood-work, because when the dry nitro-cotton is moved, as in turning it +over, very fine particles get into the air, and gradually settling on the +pipes, window ledges, &c., may become very hot, when the slightest +friction might cause explosion. It is on this account that this house +should be very carefully swept out every day. It is also very desirable +that the floor of this house should be covered with oilcloth or linoleum, +as being soft, it lessens the friction. + +List shoes should always be worn in this building, and a thermometer hung +up somewhere about the centre of the house, and one should also be kept in +one of the trays to give the temperature of the cotton, especially the +bottom of the trays. The one nearest to the hot air inlet should be +selected. If the temperature of the house is kept at about 40 deg. C. it will +be quite high enough. The building must of course be properly ventilated, +and it will be found very useful to have the walls made double, and the +intervening space filled with cinders, and the roof covered with felt, as +this helps to prevent the loss of heat through radiation, and to preserve +a uniform temperature, which is very desirable. + +The dry cotton thus obtained, if not already fine enough, should be sifted +through a brass sieve, and packed away ready for use in zinc air-tight +cases, or in indiarubber bags. The various gelatine compounds, gelignite, +gelatine dynamite, and blasting gelatine, are manufactured in exactly the +same way. The forms known as gelatine dynamite differ from blasting +gelatine in containing certain proportions of wood-pulp and potassium +nitrate, &c. The following are analyses of some typical samples of the +three compounds:-- + + Gelatine Blasting + Gelignite. Dynamite. Gelatine. + +Nitro-glycerine 60.514 71.128 92.94 per cent. +Nitro-cellulose 4.888 7.632 7.06 " +Wood-pulp 7.178 4.259 ... " +Potassium nitrate 27.420 16.720 ... " +Water ... 0.261 ... " + +The gelignite and gelatine dynamites consist, therefore, of blasting +gelatine, thickened up with a mixture of absorbing materials. Although the +blasting gelatine is weight for weight more powerful, it is more difficult +to make than either of the other two compounds, it being somewhat +difficult to make it stand the exudation and melting tests. The higher +percentage of nitro-cotton, too, makes it expensive. + +When the dry nitro-cotton, which has been carefully weighed out in the +proportions necessary either for blasting gelatine or any of the other +gelatine explosives, is brought to the gelatine making house, it is placed +in a lead-lined trough, and the necessary quantity of pure dry nitro- +glycerine poured upon it. The whole is then well stirred up, and kept at a +temperature of from 40 deg. to 45 deg. C. It should not be allowed to go much +above 40 deg. C.; but higher temperatures may be used if the nitro-cotton is +very obstinate,[A] and will not dissolve. Great caution must, however, be +observed in this case. The mixture should be constantly worked about by +the workman with a wooden paddle for at least half an hour. At a +temperature of 40 deg. to 45 deg. the nitro-glycerine acts upon the nitro-cotton +and forms a jelly. Without heat the gelatinisation is very imperfect +indeed, and at temperatures under 40 deg. C. takes place very slowly. + +[Footnote A: Generally due to the nitro-cotton being damp.] + +[Illustration: FIG. 30.--WERNER, PFLEIDERER, & PERKINS' MIXING MACHINE.] + +The limit of temperature is 50 deg. C. or thereabouts. Beyond this the jelly +should never be allowed to go, and to 50 deg. only under exceptional +circumstances. + +The tank in which the jelly is made is double-lined, in order to allow of +the passage of hot water between its inner and outer linings. A series of +such tanks are generally built in a wooden framework, and the double +linings are made to communicate, so that the hot water can flow from one +to the other consecutively. The temperature of the water should be about +60 deg. C. if it is intended to gelatinise at 45 deg. C., and about 80 deg. if at +50 deg. C.; but this point must, of course, be found by experiment for the +particular plant used. An arrangement should be made to enable the workman +to at once cut off the supply of hot water and pass cold water through the +tanks in case the explosive becomes too hot. + +[Illustration: FIG. 31.--MR M'ROBERTS' MIXER FOR GELATINE EXPLOSIVES.] + +The best way to keep the temperature of the water constant is to have a +large tank of water raised upon a platform, some 5 or 6 feet high, outside +the building, which is automatically supplied with water, and into which +steam is turned. A thermometer stuck through a piece of cork and floated +upon the surface of the tank will give the means of regulating the +temperature. + +When the jelly in the tanks has become semi-transparent and the cotton has +entirely dissolved, the mixture should be transferred to the mixing +machine. The mixing machines are specially designed for this work, and are +built in iron, with steel or bronze kneading- and mixing-blades, according +to requirements. + +A suitable machine for the purpose is that known as the Nito-Universal +Incorporator, shown in Fig. 30, which has been specially constructed by +Messrs Werner, Pfleiderer, & Perkins, Ltd., after many years' experience +in the mixing of explosive materials, and is now almost exclusively +adopted in both Government and private factories. Mr George M'Roberts'[A] +mixing machine, however, which is shown in Fig. 31, is still used in some +factories for dynamite jelly. + +[Footnote A: See _Jour. Soc. Chem. Ind._, 1890, 267.] + +If it is intended to make gelignite, or gelatine dynamite, it is at this +point that the proper proportions of wood-pulp[A] and potassium nitrate +should be added, and the whole well mixed for at least half an hour, until +the various ingredients are thoroughly incorporated. + +[Footnote A: Most of the wood-pulp used in England is obtained from +pine-trees, but poplar, lime, birch, and beech wood are also used. It is +chiefly imported as wood-pulp. The pulp is prepared as follows:--The bark +and roots are first removed, and the logs then sawn into boards, from +which the knots are removed. The pieces of wood are afterwards put through +a machine which breaks them up into small pieces about an inch long, which +are then crushed between rollers. These fragments are finally boiled with +a solution of sodium bisulphite, under a pressure of about 90 lbs. per +square inch, the duration of the boiling being from ten to twelve hours. +Sulphurous acid has also been used. Pine-wood yields about 45 per cent. +and birch about 40 per cent. of pulp when treated by this process. The +pulp is afterwards bleached and washed, &c. + + Birch. Beech. Lime. Pine. Poplar. +Cellulose 55.52 45.47 53.09 56.99 62.77 per cent. +Resin 1.14 0.41 3.93 0.97 1.37 " +Aqueous extract 2.65 2.47 3.56 1.26 2.88 " +Water 12.48 12.57 10.10 13.87 12.10 " +Lignine 28.21 39.14 29.32 26.91 20.88 "] + +The following analysis of woods is by Dr H. Mueller:--These mixing machines +can either be turned by hand, or a shaft can be brought into the house and +the machine worked by means of a belt at twenty to thirty revolutions per +minute. The bearings should be kept constantly greased and examined, and +the explosive mixture carefully excluded. When the gelatine mixture has +been thoroughly incorporated, and neither particles of nitrate or wood +meal can be detected in the mass, it should be transferred to wooden boxes +and carried away to the cartridge-making machines to be worked up into +cartridges. + +[Illustration: FIG. 32.--PLAN OF THE BOX CONTAINING THE EXPLOSIVE, IN +M'ROBERTS' MACHINE.] + +The application of heat in the manufacture of the jelly from collodion- +cotton and nitro-glycerine is absolutely necessary, unless some other +solvent is used besides the nitro-glycerine, such as acetone, acetic +ether, methyl, or ethyl-alcohol. (They are all too expensive, with the +exception of acetone and methyl-alcohol, for use upon the large scale.) +These liquids not only dissolve the nitro-cellulose in the cold, but +render the resulting gelatine compound less sensitive to concussion, and +reduce its quickness of explosion (as in cordite). They also lower the +temperature at which the nitro-glycerine becomes congealed, i.e., they +lower the freezing point[A] of the resulting gelatine. + +[Footnote A: It has been proposed to mix dynamite with amyl alcohol for +this purpose. Di-nitro-mono-chlorhydrine has also been proposed.] + +The finished gelatine paste, upon entering the cartridge huts, is at once +transferred to the cartridge-making machine, which is very like an +ordinary sausage-making machine[A] (Fig. 33). The whole thing must be made +of gun-metal or brass, and it consists of a conical case containing a +shaft and screw. The revolutions of the shaft cause the thread of the +screw to push forward the gelatine introduced by the hopper on the top to +the nozzle, the apex of the cone-shaped case, from whence the gelatine +issues as a continuous rope. The nozzle is of course of a diameter +according to the size of cartridge required. + +[Footnote A: G. M'Roberts, _Jour. Soc. Chem. Ind._, 31st March 1890, p. +266.] + +[Illustration: FIG. 33.--CARTRIDGE-MAKING MACHINE FOR GELATINE +EXPLOSIVES.] + +The issuing gelatine can of course be cut off at any length. This is best +done with a piece of hard wood planed down to a cutting edge, i.e., +wedge-shaped. Mr Trench has devised a kind of brass frame, into which the +gelatine issuing from the nozzle of the cartridge machine is forced, +finding its way along a series of grooves. When the frame is full, a +wooden frame, which is hinged to one end of the bottom frame, and fitted +with a series of brass knives, is shut down, thereby cutting the gelatine +up into lengths of about 4 inches. + +It is essential that the cartridge machines should have no metallic +contacts inside. The bearing for the screw shaft must be fixed outside the +cone containing the gelatine. One of these machines can convert from 5 to +10 cwt. of gelatine into cartridges per diem, depending upon the diameter +of the cartridges made. + +After being cut up into lengths of about 3 inches, the gelatine is rolled +up in cartridge paper. Waterproof paper is generally used. The cartridges +are then packed away in cardboard boxes, which are again packed in deal +boxes lined with indiarubber, and screwed down air tight, brass screws or +zinc or brass nails being used for the purpose. These boxes are sent to +the magazines. Before the boxes are fastened down a cartridge or so should +be removed and tested by the heat test, the liquefaction test, and the +test for liability to exudation. (Appendix, p. 6, Explosives Act, 1875.) A +cartridge also should be stored in the magazine in case of any subsequent +dispute after the bulk of the material has left the factory. + +The object of the liquefaction test is to ensure that the gelatine shall +be able to withstand a fairly high temperature (such as it might encounter +in a ship's hold) without melting or running together. The test is carried +out as follows:--A cylinder of the gelatine dynamite is cut from the +cartridge of a length equal to its diameter. The edges must be sharp. This +cylinder is to be placed on end on a flat surface (such as paper), and +secured by a pin through the centre, and exposed for 144 consecutive hours +to a temperature of 85 deg. to 90 deg. F., and during such time the cylinder +should not diminish in height by more than one-fourth of an inch, and the +cut edges should remain sharp. There should also be no stain of +nitroglycerine upon the paper. + +The exudation test consists in freezing and thawing the gelatine three +times in succession. Under these conditions there should be no exudation +of nitro-glycerine. All the materials used in the manufacture of gelatine +explosives should be subjected to analytical examination before use, as +success largely depends upon the purity of the raw materials. The +wood-pulp, for instance, must be examined for acidity. + +~Properties of the Gelatine Compounds.~--Blasting gelatine is generally +composed of 93 to 95 parts nitro-glycerine, and 5 to 7 parts of nitro- +cellulose, but the relative proportions of explosive base and nitro- +glycerine, &c., in the various forms of the gelatine explosives do not +always correspond to those necessary for total combustion, either because +an incomplete combustion gives rise to a greater volume of gas, or because +the rapidity of decomposition and the law of expansion varies according to +the relative proportions and the conditions of application. The various +additions to blasting gelatine generally have the effect of lowering the +strength by reducing the amount of nitro-glycerine, but this is sometimes +done in order to change a shattering agent into a propulsive force. If +this process be carried too far, we of course lose the advantages due to +the presence of nitro-glycerine. There is therefore a limit to these +additions.[A] + +[Footnote A: Mica is said to increase the rapidity of explosion when mixed +with gelatine.] + +The homogeneousness and stability of the mixture are of the highest +importance. It is highly essential that the nitro-glycerine should be +completely absorbed by the substances with which it is mixed, and that it +should not subsequently exude when subjected to heat or damp. It is also +important that there should be no excess of nitro-glycerine, as this may +diminish instead of augment the strength, owing to a difference in the +mode of the propagation of the explosive wave in the liquid, and in the +mixture. Nitro-glycerine at its freezing point has a tendency to separate +from its absorbing material, in fact to exude. When frozen, too, it +requires a more powerful detonation to explode it, but it is less +sensitive to shock. The specific gravity of blasting gelatine is 1.5 +(i.e., nearly equal to that of nitro-glycerol); that of gun-cotton (dry) +is 1.0. + +Blasting gelatine burns in the air when unconfined without explosion, at +least in small quantities and when not previously heated, but it is rather +uncertain in this respect. It can be kept at a moderately high temperature +(70 deg. C.) without decomposition. At higher temperatures the nitro-glycerine +will partially evaporate. When slowly heated, it explodes at 204 deg. C. If, +however, it contains as much as 10 per cent. of camphor, it burns without +exploding. According to Berthelot,[A] gelatine composed of 91.6 per cent. +nitro-glycerine and 8.4 per cent. of nitro-cellulose, which are the +proportions corresponding to total combustion, produces by explosion +177CO_{2}+ 143H_{2}O + 8N_{2}. + +[Footnote A: Berthelot, "Explosives and their Powers."] + +He takes C_{24}H_{22}(NO_{3}H)_{9}O_{11} as the formula of the nitro- +cellulose, and 51C_{3}H_{2}(NO_{3}H)_{3} + C_{24}H_{22}(NO_{3}H)_{9}O_{11} +as the formula of the gelatine itself, its equivalent weight being 12,360 +grms. The heat liberated by its explosion is equal to 19,381 calories, or +for 1 kilo. 1,535 calories. Volume of gases reduced temperature equals +8,950 litres. The relative value[A] of blasting gelatine to nitro- +glycerine is as 1.4 to 1.45, kieselguhr dynamite being taken as 1.0. + +[Footnote A: Roux and Sarran.] + + + + +CHAPTER V. + +_NITRO-BENZOL, ROBURITE, BELLITE, PICRIC ACID, &c._ + +Explosives derived from Benzene--Toluene and Nitro-Benzene--Di- and +Tri-nitro-Benzene--Roburite: Properties and Manufacture--Bellite: +Properties, &c.--Securite--Tonite No. 3.--Nitro-Toluene-- +Nitro-Naphthalene--Ammonite--Sprengel's Explosives--Picric Acid-- +Picrates--Picric Powders--Melinite--Abel's Mixture--Brugere's Powders-- +The Fulminates--Composition, Formula, Preparation, Danger of, &c.-- +Detonators: Sizes, Composition, Manufacture--Fuses, &c. + + +~The Explosives derived from Benzene.~--There is a large class of +explosives made from the nitrated hydro-carbons--benzene, C_{6}H_{6}; +toluene, C_{7}H_{8}; naphthalene, C_{10}H_{8}; and also from phenol (or +carbolic acid), C_{6}H_{5}OH. The benzene hydro-carbons are generally +colourless liquids, insoluble in water, but soluble in alcohol and ether. +They generally distil without decomposition. They burn with a smoky flame, +and have an ethereal odour. They are easily nitrated and sulphurated; +mono, di, and tri derivatives are readily prepared, according to the +strength of the acids used. It is only the H-atoms of the benzene nucleus +which enter into reaction. + +Benzene was discovered by Faraday in 1825, and detected in coal-tar by +Hofmann in 1845. It can be obtained from that portion of coal-tar which +boils at 80 deg. to 85 deg. by fractionating or freezing.[A] The ordinary benzene +of commerce contains thiophene (C_{4}H_{4}S), from which it may be freed +by shaking with sulphuric acid. Its boiling point is 79 deg. C.; specific +gravity at 0 deg. equals 0.9. It burns with a luminous smoky flame, and is a +good solvent for fats, resins, sulphur, phosphorus, &c. Toluene was +discovered in 1837, and is prepared from coal-tar. It boils at 110 deg. C., +and is still liquid at 28 deg. C. + +[Footnote A: It may be prepared chemically pure by distilling a mixture of +benzoic acid and lime.] + +The mono-, chloro-, bromo-, and iodo-benzenes are colourless liquids of +peculiar odour. Di-chloro-, di-bromo-benzenes, tri- and hexa-chloro- and +bromo-benzenes, are also known; and mono-chloro-, C_{6}H_{4}Cl(CH_{3}), +and bromo-toluenes, together with di derivatives in the ortho, meta, and +para modifications. The nitro-benzenes and toluenes are used as +explosives. The following summary is taken from Dr A. Bernthsen's "Organic +Chemistry":-- + + SUMMARY. + ____________________________________________________________________ +| | +| C_{6}H_{5}(N0_{2}) Nitro-benzene. Liq. B.Pt. 206 deg. C. | +| | +| C_{6}H_{4}(NO_{2})_{2} Ortho-, meta-, and para- di-nitro-benzenes. | +| Solid. M.P. 118 deg., 90 deg., and 172 deg. C. | +| | +| C_{6}H_{3}(NO_{3})_{3} S.-Tri-nitro-benzene. Solid. M.P. 121 deg. C. | +|____________________________________________________________________| +| | +| C_{6}H_{4}(CH_{3})NO_{2} Ortho-, meta-, and para- nitro-toluenes. | +| B.P. 218 deg., 230 deg., and 234 deg. C, Para compound solid. | +|____________________________________________________________________| +| | +| C_{6}H_{3}(CH_{3})_{2}NO_{2} Nitro-xylene. Liquid. | +|____________________________________________________________________| +| | +| C_{6}H_{2}(CH_{3})_{3}NO_{2} Nitro-mesitylene. Solid. | +|____________________________________________________________________| +| | +| C_{6}H_{3}(CH_{3})(NO_{2})_{2} Di-nitro-toluenes. | +|____________________________________________________________________| +| | +| C_{6}H_{4}Cl(NO_{2}) Nitro-chloro-benzenes. | +| | +| C_{6}Br_{4}(NO_{2})_{2} Tetra-bromo-di-nitrobenzene. | +|____________________________________________________________________| + +The nitro compounds are mostly pale yellow liquids, which distil +unchanged, and volatilise with water vapour, or colourless or pale yellow +needles or prisms. Some of them, however, are of an intense yellow colour. +Many of them explode upon being heated. They are heavier than water, and +insoluble in it, but mostly soluble in alcohol, ether, and glacial acetic +acid. + +Nitro-benzene, C_{6}H_{5}(NO_{2}), was discovered in 1834 by Mitscherlich. +It is a yellow liquid, with a melting point of +3 deg. C. It has an intense +odour of bitter almonds. It solidifies in the cold. In di-nitro-benzene, +the two nitro groups may be in the meta, ortho, or para position, the meta +position being the most general (see fig., page 4). By recrystallising +from alcohol, pure meta-di-nitro-benzene may be obtained in long +colourless needles. The ortho compound crystallises in tables, and the +para in needles. They are both colourless. When toluene is nitrated, the +para and ortho are chiefly formed, and a very little of the meta compound. + +~Nitro Compounds of Benzene and Toluene.~--The preparation of the nitro +derivatives of the hydrocarbons of the benzene series is very simple. It +is only necessary to bring the hydrocarbon into contact with strong nitric +acid, when the reaction takes place, and one or more of the hydrogen atoms +of the hydrocarbon are replaced by the nitryl group (NO_{2}). Thus by the +action of nitric acid on benzene (or benzol), mono-nitro-benzene is +formed:-- + +C_{6}H_{6} + HNO_{3} = C_{6}H_{5}.NO_{2} +H_{2}O. + Mono-nitro-benzene. + +By the action of another molecule of nitric acid, the di-nitro-benzene is +formed:-- + +C_{6}H_{5}.NO_{2} + HNO_{3} = C_{6}H_{4}(NO_{2})_{2} + H_{2}O. + Di-nitro-benzene. + +These nitro bodies are not acids, nor are they ethereal salts of nitrous +acid, as nitro-glycerine is of glycerine. They are regarded as formed from +nitric acid by the replacement of hydroxyl by benzene radicals. + +~Mono-nitro Benzene~ is made by treating benzene with concentrated nitric +acid, or a mixture of nitric and sulphuric acids. The latter, as in the +case of the nitration of glycerine, takes no part in the reaction, but +only prevents the dilution of the nitric acid by the water formed in the +reaction. Small quantities may be made thus:--Take 150 c.c. of H_{2}SO_{4} +and 75 c.c. HNO_{3}, or 1 part nitric to 2 parts sulphuric acid, and put +in a beaker standing in cold water; then add 15 to 20 c.c. of benzene, +drop by drop, waiting between each addition for the completion of the +reaction, and shake well during the operation. When finished, pour +contents of beaker into about a litre of cold water; the nitro-benzol will +sink to the bottom. Decant the water, and wash the nitro-benzol two or +three times in a separating funnel with water. Finally, dry the product by +adding a little granulated calcium chloride, and allowing to stand for +some little time, it may then be distilled. Nitro-benzene is a heavy oily +liquid which boils at 205 deg. C., has a specific gravity of 1.2, and an odour +like that of oil of bitter almonds. In the arts it is chiefly used in the +preparation of aniline. + +~Di-nitro Benzene~ is a product of the further action of nitric acid on +benzene or nitro-benzene. It crystallises in long fine needles or thin +rhombic plates, and melts at 89.9 deg. C. It can be made thus:--The acid +mixture used consists of equal parts of nitric and sulphuric acids, say 50 +c.c. of each, and without cooling add very slowly 10 c.c. of benzene from +a pipette. After the action is over, boil the mixture for a short time, +then pour into about half a litre of water, filter off the crystals thus +produced, press between layers of filter paper, and crystallise from +alcohol. Di-nitro-benzene, or meta-di-nitro-benzene, as it is sometimes +called, enters into the composition of several explosives, such as tonite +No. 3, roburite, securite, bellite. + +Nitro-benzene is manufactured upon the large scale as follows:--Along a +bench a row of glass flasks, containing 1 gallon each (1 to 2 lbs. +benzene), are placed, and the acids added in small portions at a time, the +workmen commencing with the first, and adding a small quantity to each in +turn, until the nitration was complete. This process was a dangerous one, +and is now obsolete. The first nitro-benzene made commercially in England, +by Messrs Simpson, Maule, and Nicholson, of Kennington, in 1856, was by +this process. Now, however, vertical iron cylinders, made of cast-iron, +are used for the nitrating operation. They are about 4 feet in diameter +and 4 feet deep, and a series are generally arranged in a row, at a +convenient height from the ground, beneath a line of shafting. Each +cylinder is covered with a cast-iron lid having a raised rim all round. A +central orifice gives passage to a vertical shaft, and two or more other +conveniently arranged openings allow the benzene and the mixed acids to +flow in. Each of these openings is surrounded with a deep rim, so that the +whole top of the cylinder can be flooded with water some inches in depth, +without any of it running into the interior of the nitrator. The lid +overhangs the cylinder somewhat, and in the outer rim a number of shot- +holes or tubes allow the water to flow down all over the outside of the +cylinder into a shallow cast-iron dish, in which it stands. By means of a +good supply of cold water, the top, sides, and bottom of the whole +apparatus is thus cooled and continually flooded. The agitator consists of +cast-iron arms keyed to a vertical shaft, with fixed arms or dash-plates +secured to the sides of the cylinder. The shaft has a mitre wheel keyed on +the top, which works into a corresponding wheel on the horizontal shafting +running along the top of the converters. This latter is secured to a +clutch; and there is a feather on the shaft, so that any one of the +converters can if necessary be put either in or out of gear. This +arrangement is necessary, as riggers or belts of leather, cotton, or +indiarubber will not stand the atmosphere of the nitro-benzole house. +Above and close to each nitrator stands its acid store tank, of iron or +stoneware. + +The building in which the nitration is carried out should consist of one +story, have a light roof, walls of hard brick, and a concrete floor of 9 +to 12 inches thick, and covered with pitch, to protect its surface from +the action of the acids. The floor should be inclined to a drain, to save +any nitro-benzol spilt. Fire hydrants should be placed at convenient +places, and it should be possible to at once fill the building with steam. +A 2-inch pipe, with a cock outside the building, is advisable. The +building should also be as far as possible isolated. + +The acids are mixed beforehand, and allowed to cool before use. The nitric +acid used has a specific gravity of 1.388, and should be as free as +possible from the lower oxides of nitrogen. The sulphuric acid has a +specific gravity of 1.845, and contains from 95 to 96 per cent. of mono- +hydrate. A good mixture is 100 parts of nitric to 140 parts of sulphuric +acid, and 78 parts of benzene; or 128 parts HNO_{3}, 179 of H_{2}SO_{4}, +and 100 of benzene (C_{6}H_{6}). The benzene having been introduced into +the cylinder, the water is turned on and the apparatus cooled, the +agitators are set running, and the acid cock turned on so as to allow it +to flow in a very thin stream into the nitrator. + +Should it be necessary to check the machinery even for a moment, the +stream of acid must be stopped and the agitation continued for some time, +as the action proceeds with such vigour that if the benzene being nitrated +comes to rest and acid continues to flow, local heating occurs, and the +mixture may inflame. Accidents from this cause have been not infrequent. +The operation requires between eight to ten hours, agitation and cooling +being kept up all the time. When all the acid is added the water is shut +off, and the temperature allowed to rise a little, to about 100 deg. C. When +it ceases to rise the agitators are thrown out of gear, and the mixture +allowed some hours to cool and settle. The acid is then drawn off, and the +nitro-benzene is well washed with water, and sometimes distilled with wet +steam, to recover a little unconverted benzene and a trace of paraffin +(about .5 per cent. together). At many English works, 100 to 200 gallons, +or 800 to 1,760 lbs., are nitrated at a time, and toluene is often used +instead of benzene, especially if the nitro-benzene is for use as essence +of myrbane. The waste acids, specific gravity 1.6 to 1.7, contain a little +nitro-benzene in solution and some oxalic acid. They are concentrated in +cast-iron pots and used over again. + +~Di-nitro Benzene~ is obtained by treating a charge of the hydrocarbon +benzene with double the quantity of mixed acids in two operations, or +rather in two stages, the second lot of acid being run in directly after +the first. The cooling water is then shut off, and the temperature allowed +to rise rapidly, or nitro-benzene already manufactured is taken and again +nitrated with acids. A large quantity of acid fumes come off, and some of +the nitro- and di-nitro-benzol produced comes off at the high temperature +which is attained, and a good condensing apparatus of stoneware must be +used to prevent loss. The product is separated from the acids, washed with +cold water and then with hot. It is slightly soluble in water, so that the +washing waters must be kept and used over again. Finally it is allowed to +settle, and run while still warm into iron trays, in which it solidifies +in masses 2 or 4 inches thick. It should not contain any nitro-benzol, nor +soil a piece of paper when laid on it, should be well crystallised, fairly +hard, and almost odourless. The chief product is meta-di-nitro-benzene, +melting point 89.8, but ortho-di-nitro-benzene, melting point 118 deg., and +para-di-nitro, melting point 172 deg., are also produced. The melting point of +the commercial product is between 85 deg. to 87 deg. C. + +Di-nitro-toluene is made in a similar manner. The tri-nitro-benzene can +only be made by using a very large excess of the mixed acids. Nitro- +benzene, when reduced with iron, zinc, or tin, and hydrochloric acids, +forms aniline. + +~Roburite.~--This explosive is the invention of a German chemist, Dr Carl +Roth (English patent 267A, 1887), and is now manufactured in England, at +Gathurst, near Wigan. It consists of two component parts, non-explosive in +themselves (Sprengel's principle), but which, when mixed, form a powerful +explosive. The two substances are ammonium nitrate and chlorinated +di-nitro-benzol. Nitro-naphthalene is also used. Nitrate of soda and +sulphate of ammonium are allowed to be mixed with it. The advantages +claimed for the introduction of chlorine into the nitro compound are that +chlorine exerts a loosening effect upon the NO_{2} groups, and enables the +compound to burn more rapidly than when the nitro groups alone are present. + +The formula of chloro-di-nitro-benzol is C_{6}H_{3}Cl(NO_{2})_{2}. The +theoretical percentage of nitrogen, therefore, is 13.82, and of chlorine +17.53. Dr Roth states that, from experiments he has made, the dynamic +effect is considerably increased by the introduction of chlorine into the +nitro compound. Roburite burns quickly, and is not sensitive to shock; it +must be used dry; it cannot be made to explode by concussion, pressure, +friction, fire, or lightning; it does not freeze; it does not give off +deleterious fumes, and it is to all intents and purposes flameless; and +when properly tamped and fired by electricity, can be safely used in fiery +mines, neither fine dust nor gases being ignited by it. The action is +rending and not pulverising. Compared to gunpowder, it is more powerful in +a ratio ranging from 2-1/2 to 4 to 1, according to the substance acted +upon. It is largely used in blasting, pit sinking, quarrying, &c., but +especially in coal mining. According to Dr Roth, the following is the +equation of its decomposition:-- + +C_{6}H_{3}Cl(NO_{2})_{2} + 9HN_{4}NO_{3} = 6CO_{2} + 20N + HCl. + +In appearance roburite is a brownish yellow powder, with the +characteristic smell of nitro-benzol. Its specific gravity is 1.40. The +Company's statement that the fumes of roburite were harmless having been +questioned by the miners of the Garswood Coal and Iron Works Colliery, a +scientific committee was appointed by the management and the men jointly +for the purpose of settling the question. The members of this committee +were Dr N. Hannah, Dr D.J. Mouncey, and Professor H.B. Dixon, F.R.S., of +Owens College. After a protracted investigation, a long and technical +report was issued, completely vindicating the innocuousness of roburite +when properly used. In the words of _The Iron and Coal Trades' Review_ +(May 24, 1889), "The verdict, though not on every point in favour of the +use in all circumstances of roburite in coal mines, is yet of so +pronounced a character in its favour as an explosive that it is impossible +to resist the conclusion that the claims put forward on its behalf rest on +solid grounds." + +Roburite was also one of the explosives investigated by the committee +appointed in September 1889 by the Durham Coalowners' and Miners' +Associations, for the purpose of determining whether the fumes produced by +certain explosives are injurious to health. Both owners and workmen were +represented on the committee, which elected Mr T. Bell, H.M. Inspector of +Mines, as its chairman, with Professor P.P. Bedson and Drs Drummond and +Hume as professional advisers. The problem considered was whether the +fumes produced by the combustion of certain explosives, one of which was +roburite, were injurious to health. The trial comprised the chemical +analysis of the air at the "intake," and of the vitiated air during the +firing of the shots at the "return," and also of the smoky air in the +vicinity of the shot-holes. Five pounds and a half of roburite were used +in twenty-three shots. It had been asserted that the fumes from this +explosive contained carbon-monoxide, CO, but no trace of this gas could be +discovered after the explosion. On another occasion, however, when 4.7 +lbs. of roburite were exploded in twenty-three shots, the air at the +"return" showed traces of CO gas to the extent of .042 to .019 per cent. +The medical report which Drs Hume and Drummond presented to the committee +shows that they investigated every case of suspected illness produced by +exposure to fumes, and they could find no evidence of acute illness being +caused. They say, "No case of acute illness has, throughout the inquiry, +been brought to our knowledge, and we are led to the conclusion that such +cases have not occurred." + +~Manufacture.~--As now made, roburite is a mixture of ammonium nitrate and +chlorinated di-nitro-benzol. The nitrate of ammonia is first dried and +ground, and then heated in a closed steam-jacketed vessel to a temperature +of 80 deg. C., and the melted organic compound is added, and the whole stirred +until an intimate mixture is obtained. On cooling, the yellow powder is +ready for use, and is stored in straight canisters or made up into +cartridges. Owing to the deliquescent nature of the nitrate of ammonia, +the finished explosive must be kept out of contact with the air, and for +this reason the cartridges are waterproofed by dipping them in melted wax. +Roburite is made in Germany, at Witten, Westphalia; and also at the +English Company's extensive works at Gathurst, near Wigan, which have been +at work now for some eighteen years, having started in 1888. These works +are of considerable extent, covering 30 acres of ground, and are equal to +an output of 10 tons a day. A canal runs through the centre, separating +the chemical from the explosive portions of the works, and the Lancashire +and Yorkshire Railway runs up to the doors. Besides sending large +quantities of roburite itself abroad, the Company also export to the +various colonies the two components, as manufactured in the chemical +works, and which separately are quite non-explosive, and which, having +arrived at their destination, can be easily mixed in the proper +proportions. + +Among the special advantages claimed for roburite are:--First, that it is +impossible to explode a cartridge by percussion, fire, or electric sparks. +If a cartridge or layer be struck with a heavy hammer, the portion struck +is decomposed, owing to the large amount of heat developed by the blow. +The remaining explosive is not in the least affected, and no detonation +whatever takes place. If roburite be mixed with gunpowder, and the +gunpowder fired, the explosion simply scatters the roburite without +affecting it in the least. In fact, the only way to explode roburite is to +detonate it by means of a cap of fulminate, containing at least 1 gramme +of fulminate of mercury. Secondly, its great safety for use in coal mines. +Roburite has the great advantage of exploding by detonation at a very low +temperature, indeed so low that a very slight amount of tamping is +required when fired in the most explosive mixture of air and coal gas +possible, and not at all in a mixture of air and coal dust--a condition in +which the use of gunpowder is highly dangerous. + +Mr W.J. Orsman, F.I.C., in a paper read at the University College, +Nottingham, in 1893, gives the temperature of detonation of roburite as +below 2,100 deg. C., and of ammonium nitrate as 1,130 deg. C., whereas that of +blasting gelatine is as much as 3,220 deg. C. With regard to the composition +of the fumes formed by the explosion of roburite, Mr Orsman says: "With +certain safety explosives--roburite, for instance--an excess of the +oxidising material is added, namely, nitrate of ammonia; but in this case +the excess of oxygen here causes a diminution of temperature, as the +nitrate of ammonia on being decomposed absorbs heat. This excess of oxygen +effectually prevents the formation of carbon monoxide (CO) and the oxides +of nitrogen." + +The following table (A), also from Mr Orsman's paper, gives the +composition of five prominent explosives, and shows the composition of the +gases formed on explosion. The gases were collected after detonating 10 +grms. of each in a closed strong steel cylinder, having an internal +diameter of 5 inches. + +With respect to the influence of ammonium nitrate in lowering the +temperature of explosion of the various substances to which it is added, +it was found by a French Commission that, when dry and finely powdered, +ammonium nitrate succeeds in depreciating the heat of decomposition +without reducing the power of the explosive below a useful limit. The +following table (B) shows the composition of the explosives examined, and +the temperatures which accompanied their explosion. + + A + ______________________________________________________________________ +| | | | +| | | Composition of Gases. | +| |Volume |__________________________| +| Explosive. |of Gas | | | | | +| |formed.|CO_{2}.| CO. |CH_{4}| N. | +| | | | | &H. | | +|___________________________________|_______|_______|_____|______|_____| +| | | | | | | +| | | Per | Per | Per | Per | +| | c.c. | cent. |cent.|cent. |cent.| +|Gunpowder-- | | | | | | +| Nitre 75 parts | | | | | | +| Sulphur 10 '' | 2,214 | 51.3 | 3.5| 3.5 | 41.7| +| Charcoal 15 '' | | | | | | +|Gelignite-- | | | | | | +| Nitro-glycerine 56.5 parts | | | | | | +| Nitro-cotton 3.5 '' | 4,980 | 25 | 7 | ... | 67 | +| Wood-meal 8.0 '' | | | | | | +| KNO_{3} 32.0 '' | | | | | | +|Tonite-- | | | | | | +| Nitro-Cotton | 3,750 | 30 | 8 | ... | 62 | +| Barium nitrate | | | | | | +|Roburite-- | | | | | | +| Ammonium nitrate, 86 parts | | | | | | +| Di-nitro-chloro-benzol 14 '' | 4,780 | 32 | ... | ... | 68 | +|Carbonite | | | | | | +| Nitro-glycerine 25 parts | | | | | | +| Wood-meal 40 '' | 2,100 | 19 | 15 | 26 | ... | +| Potas. nitrate 34 '' | | | | | | +|___________________________________|_______|_______|_____|______|_____| + + B + ____________________________________________________________________ +| | | | | +| | Original | Percentage | Final | +| Explosive. | Temperature |NH_{4}.NO_{3}| Temperature | +| |Co-efficient.| added. |Co-efficient.| +|__________________________|_____________|_____________|_____________| +| | | | | +|Nitro-glycerine | 3,200 | ... | ... | +|Blasting gelatine | | | | +| (8 per cent. gun-cotton)| 3,090 | 88 | 1,493 | +|Dynamite | | | | +| (25 per cent. silica)| 2,940 | 80 | 1,468 | +| | | | | +|Gun-cotton, 1 | 2,650 | ... | ... | +| | 2,060 | 90.5 | 1,450 | +| | | | | +|Ammonium nitrate | 1,130 | ... | ... | +|__________________________|_____________|_____________|_____________| + +~Bellite~ is the patent of Mr Carl Lamm, Managing Director of the Roetebro +Explosive Company, of Stockholm, and is licensed for manufacture in +England. It consists of a mixture of nitrate of ammonia with di- or +tri-nitro-benzol, it has a specific gravity of 1.2 to 1.4 in its granulated +state, and 1 litre weighs 800 to 875 grms. Heated in an open vessel, +bellite loses its consistency at 90 deg. C., but does not commence to separate +before a temperature of 200 deg. C. is reached, when it evaporates without +exploding. If heated suddenly, it burns with a sooty flame, somewhat like +tar, but if the source of heat is removed, it will cease burning, and +assume a caramel-like structure. It absorbs very little moisture from the +air after it has been pressed, and if the operation has been performed +while the explosive is hot, the subsequent increase of weight is only 2 +per cent. When subjected to the most powerful blow with a steel hammer +upon an iron plate, it neither explodes nor ignites. A rifle bullet fired +into it at 50 yards' distance will not explode it. Granulated bellite +explodes fully by the aid of fulminating mercury. Fifteen grms. of bellite +fired by means of fulminate, projected a shot from an ordinary mortar, +weighing 90 lbs., a distance of 75 yards, 15 grms. of gunpowder, under the +same conditions, throwing it only 12 yards. A weight of 7-1/2 lbs. falling +145 centimetres failed to explode 1 grm. of bellite. + +Various experiments and trials have been made with this explosive by +Professor P.T. Cleve, M.P.F. Chalon, C.N. Hake, and by a committee of +officers of the Swedish Royal Artillery. It is claimed that it is a very +powerful and extremely safe explosive; that it cannot be made to explode +by friction, shock, or pressure, nor by electricity, fire, lightning, &c., +and that it is specially adapted for use in coal mines, &c.; that it can +only be exploded by means of a fulminate detonator, and is perfectly safe +to handle and manufacture; that it does not freeze, can be used as a +filling for shells, and lastly, can be cheaply manufactured. + +~Securite~ consists of 26 parts of meta-di-nitro-benzol and 74 parts of +ammonium nitrate. It is a yellow powder, with an odour of nitro-benzol. It +was licensed in 1886. It sometimes contains tri-nitro-benzol, and +tri-nitro-naphthalene. The equation of its combustion is given as + +C_{6}H_{4}(NO_{2})_{2} + 10(NH_{4}NO_{3}) = 6CO_{2} + 22H_{2}O + 11N_{2} + +and, like bellite and roburite, it is claimed to be perfectly safe to use +in the presence of fire damp and coal dust.[A] The variety known as +Flameless Securite consists of a mixture of nitrate and oxalate of ammonia +and di-nitro-benzol. + +[Footnote A: See paper by S.B. Coxon, _North of Eng. Inst. Mining and +Mech. Eng._, 11, 2, 87.] + +~Kinetite.~--A few years ago an explosive called "Kinetite"[A] was +introduced, but is not manufactured in England. It was the patent of +Messrs Petry and Fallenstein, and consisted of nitro-benzol, thickened or +gelatinised by the addition of some collodion-cotton, incorporated with +finely ground chlorate of potash and precipitated sulphide of antimony. An +analysis gave the following percentages:-- + +Nitro-benzol, 19.4 per cent. +Chlorate of potash, 76.9 per cent. +Sulphide of antimony nitro-cotton, 3.7 per cent. + +[Footnote A: V. Watson Smith, _Jour. Soc. Chem. Ind._, January 1887.] + +It requires a very high temperature to ignite it, and cannot, under +ordinary circumstances, when unconfined, be exploded by the application of +heat. It is little affected by immersion in water, unless prolonged, when +the chlorate dissolves out, leaving a practical inexplosive residue.[A] It +was found to be very sensitive to combined friction and percussion, and to +be readily ignited by a glancing blow of wood upon wood. It was also +deficient in chemical stability, and has been known to ignite +spontaneously both in the laboratory and in a magazine. It is an orange- +coloured plastic mass, and smells of nitro-benzol. + +[Footnote A: Col. Cundill, R.A., "Dict. of Explosives," says: "If, +however, it be exposed to moist and dry air alternately, the chlorate +crystallises out on the surfaces, and renders the explosive very +sensitive."] + +~Tonite No. 3~ contains 10 to 14 per cent. of nitro-benzol (see Tonite). +Trench's Flameless Explosive contains 10 per cent. of di-nitro-benzol, +together with 85 per cent. of nitrate of ammonia, and 5 per cent. of a +mixture of alum, and the chlorides of sodium and ammonia. + +~Tri-nitro-Toluene.~--Toluene, C_{7}H_{8}, now chiefly obtained from coal- +tar, was formerly obtained by the dry distillation of tolu-balsam. It may +be regarded as methyl-benzene, or benzene in which one hydrogen is +replaced by methyl (CH_{3}), thus (C_{6}H_{5}CH_{3}), or as phenyl- +methane, or methane in which one hydrogen atom is replaced by the radical +phenyl (C_{6}H_{5}), thus (CH_{3}C_{6}H_{5}). Toluene is a colourless +liquid, boiling at 110 deg. C., has a specific gravity of .8824 at 0 deg. C., and +an aromatic odour. Tri-nitro-toluene is formed by the action of nitric +acid on toluene. According to Haeussermann, it is more advantageous to +start with the ortho-para-di-nitro-toluene, which is prepared by allowing +a mixture of 75 parts of 91 to 92 per cent. nitric acid and 150 parts of +95 to 96 per cent. sulphuric acid to run in a thin stream into 100 parts +of para-nitro-toluene, while the latter is kept at a temperature between +60 deg. to 65 deg. C., and continually stirred. When the acid has all been run in, +this mixture is heated for half an hour to 80 deg. C., and allowed to stand +till cold. The excess of nitric acid is then removed. The residue after +this treatment is a homogeneous crystalline mass of ortho-para-di-nitro- +toluene, of which the solidifying point is 69.5 deg. C. To convert this mass +into tri-nitro derivative, it is dissolved by gently heating it with four +times its weight of sulphuric acid (95 to 96 per cent.), and it is then +mixed with 1-1/2 times its weight of nitric acid (90 to 92 per cent.), the +mixture being kept cool. Afterwards it is digested at 90 deg. to 95 deg. C., with +occasional stirring, until the evolution of gas ceases. This takes place +in about four or five hours. + +The operation is now stopped, the product allowed to cool, and the excess +of nitric acid separated from it. The residue is then washed with hot +water and very dilute soda solution, and allowed to solidify without +purification. The solidifying point is 70 deg. C., and the mass is then white, +with a radiating crystalline structure. Bright sparkling crystals, melting +at 81.5 deg. C. may, however, be obtained by recrystallisation from hot +alcohol. The yield is from 100 parts di-nitro-toluene, 150 parts of the +tri-nitro derivative. Haeussermann states also that 1:2:4:6 tri-nitro- +toluene can be obtained from ordinary commercial di-nitro-toluene melting +at 60 deg. to 64 deg. C.; but when this is used, greater precautions must be +exercised, for the reactions are more violent. Moreover, 10 per cent. more +nitric acid is required, and the yield is 10 per cent. less. He also draws +attention to the slight solubility of tri-nitro-toluene in hot water, and +to the fact that it is decomposed by dilute alkalies and alkaline +carbonates--facts which must be borne in mind in washing the substance. +This material is neither difficult nor dangerous to make. It behaves as a +very stable substance when exposed to the air under varying conditions of +temperature (-10 deg. to +50 deg. C.) for several months. It cannot be exploded by +flame, nor by heating it in an open vessel. It is only slightly decomposed +by strong percussion on an anvil. A fulminate detonator produces the best +explosive effect with tri-nitro-toluene. It can be used in conjunction +with ammonium nitrate, but such admixture weakens the explosive power; but +even then it is stated to be stronger than an equivalent mixture of +di-nitro-benzene and ammonium nitrate. Mowbray patented a mixture of 3 +parts nitro-toluol to 7 of nitro-glycerine, also in the proportions of 1 to +3, which he states to be a very safe explosive. + +~Faversham Powder.~--One of the explosives on the permitted list (coal +mines) is extensively used, and is manufactured by the Cotton Powder Co. +Ltd. at Faversham. It is composed of tri-nitro-toluol 11 parts, ammonium +nitrate 93 parts, and moisture 1 part. This explosive must be used only +when contained in a case of an alloy of lead, tin, zinc, and antimony +thoroughly waterproof; it must be used only with a detonator or electric +detonator of not less strength than that known as No. 6. + +~Nitro-Naphthalene.~--Nitro-naphthalene is formed by the action of nitric +acid on naphthalene (C_{10}H_{8}). Its formula is C_{10}H_{7}NO_{2}, and +it forms yellow needles, melting at 61 deg. C.; and of di-nitro-naphthalene +(C_{10}H_{6}(NO_{2})_{2}), melting point 216 deg. C. There are also tri-nitro +and tetra-nitro and [alpha] and [beta] derivatives of nitro-naphthalene. +It is the di-nitro-naphthalene that is chiefly used in explosives. It is +contained in roburite, securite, romit, Volney's powder, &c. Fehven has +patented an explosive consisting of 10 parts of nitro-naphthalene mixed +with the crude ingredients of gunpowder as follows:--Nitro-naphthalene, 10 +parts; saltpetre, 75 parts; charcoal, 12.5 parts; and sulphur, 12.5 parts. +He states that he obtains a mono-nitro-naphthalene, containing a small +proportion of di-nitro-naphthalene, by digesting 1 part of naphthalene, +with or without heat, in 4 parts of nitric acid (specific gravity 1.40) +for five days. + +Quite lately a patent has been taken out for a mixture of nitro- +naphthalene or di-nitro-benzene with ammonium nitrate, and consists in +using a solvent for one or other or both of the ingredients, effected in a +wet state, and then evaporating off the solvent, care being taken not to +melt the hydrocarbon. In this way a more intimate mixture is ensured +between the particles of the components, and the explosive thus prepared +can be fired by a small detonator, viz., by 0.54 grms. of fulminate. +Favier's explosive also contains mono-nitro-naphthalene (8.5 parts), +together with 91.5 parts of nitrate of ammonia. This explosive is made in +England by the Miners' Safety Explosive Co. A variety of roburite contains +chloro-nitro-naphthalene. Romit consists of 100 parts ammonium nitrate and +7 parts potassium chlorate mixed with a solution of 1 part nitro- +naphthalene and 2 parts rectified paraffin oil. + +~Ammonite.~--This explosive was originally made at Vilvorde in Belgium, +under the title of the Favier Explosive, consisting of a compressed hollow +cylinder composed of 91.5 per cent. of nitrate of ammonia, and 8.5 per +cent. of mono-nitro-naphthalene filled inside with loose powder of the +same composition. The cartridges were wrapped in paper saturated with +paraffin-wax, and afterwards dipped in hot paraffin to secure their being +water-tight. The Miners' Safety Explosives Co., when making this explosive +at their factory at Stanford-le-Hope, Essex, abandoned after a short trial +the above composition, and substituted di-nitro-naphthalene 11.5 per cent. +for the mono-nitro-naphthalene, and used thin lead envelopes filled with +loose powder slightly pressed in, in place of the compressed cylinders +containing loose powder. The process of manufacture is shortly as +follows:--132-3/4 lbs. of thoroughly dried nitrate of ammonium is placed +in a mill pan, heated at the bottom with live steam, and ground for about +twenty minutes until it becomes so dry that a slight dust follows the +rollers; then 17-1/2 lbs. of thoroughly dry di-nitro-naphthalene is added, +and the grinding continued for about ten minutes. Cold water is then +circulated through the bottom of the pan until the material appears of a +lightish colour and falls to powder. (While the pan is hot the whole mass +looks slightly plastic and of a darker colour than when cold.) A slide in +the bottom of the pan is then withdrawn, the whole mass working out until +the pan is empty; it is now removed to the sifting machine, brushed +through a wire sieve of about 12 holes to the inch, and is then ready for +filling into cartridges. The hard core is returned from the sifting +machine and turned into one of the pans a few minutes before the charge is +withdrawn. + +The ammonite is filled into the metallic cartridges by means of an +archimedian screw working through a brass tube, pushing off the cartridges +as the explosive is fed into them against a slight back pressure; a cover +is screwed on, and they then go to the dipping room, where they are dipped +in hot wax to seal the ends; they are then packed in boxes of 5 lbs. each +and are ready for delivery. The di-nitro-naphthalene is made at the +factory. Mono-nitro-naphthalene is first made as follows:--12 parts of +commercial nitrate of soda are ground to a fine powder, and further ground +with the addition of 15 parts of refined naphthalene until thoroughly +incorporated; it is then placed in an earthenware pan, and 30 parts of +sulphuric acid of 66 deg. B. added, 2 parts at a time, during forty-eight +hours (the rate of adding H_{2}SO_{4} depends on the condition of the +charge, and keeping it in a fluid state), with frequent agitation, day and +night, during the first three or four days, afterwards three or four times +a day. In all fourteen days are occupied in the nitration process. It is +then strained through an earthenware strainer, washed with warm water, +drained, and dried. For the purpose of producing this material in a +granulated condition, which is found more convenient for drying, and +further nitrification, it is placed in a tub, and live steam passed +through, until brought up to the boiling point (the tub should be about +half full), cold water is then run in whilst violently agitating the +contents until the naphthalene solidifies; it can then be easily drained +and dried. For the further treatment to make di-nitro-naphthalene, 18 +parts of nitro-naphthalene are placed in an earthenware pan, together with +39 parts of sulphuric acid of 66 deg. B., then 15 parts of nitric acid of 40 deg. +B. are added, in small quantities at a time, stirring the mixture +continually. This adding of nitric acid is controlled by the fuming, which +should be kept down as much as possible. The operation takes ten to twelve +days, when 100 times the above quantities, taken in kilogrammes, are +taken. At the end of the nitration the di-nitro-naphthalene is removed to +earthenware strainers, allowed to drain, washed with hot water and soda +until all acid is removed, washed with water and dried. The di-nitro- +naphthalene gives some trouble in washing, as some acid is held in the +crystals which is liable to make its appearance when crushed. To avoid +this it should be ground and washed with carbonate of soda before drying; +an excess of carbonate of soda should not, however, be used. + +~Electronite.~--This is a high explosive designed to afford safety in coal +getting. This important end has been attained by using such ingredients, +and so proportioning them, as will ensure on detonation a degree of heat +insufficient under the conditions of a "blown-out" shot, to ignite fire +damp or coal dust. It is of the nitrate of ammonium class of permitted +explosives. It contains about 75 per cent. of nitrate of ammonium, with +the addition of nitrate of barium, wood meal, and starch. The gases +resulting from detonation are chiefly water in the gaseous form, nitrogen, +and a little carbon dioxide. It is granulated with the object of +preventing missfires from ramming, to which nitrate of ammonium explosives +are somewhat susceptible. This explosive underwent some exhaustive +experiments at the experimental station near Wigan in 1895, when 8 oz. or +12 oz. charges were fired unstemmed into an admixture of coal dust and 10 +per cent. of gas, without any ignition taking place. It is manufactured by +Messrs Curtis's & Harvey Ltd. at their factory, Tonbridge, Kent. + +~Sprengel's Explosives.~--This is a large class of explosives. The +essential principle of them all is the admixture of an oxidising with a +combustible agent at the time of, or just before, being required for use, +the constituents of the mixture being very often non-explosive bodies. +This type of explosive is due to the late Dr Herman Sprengel, F.R.S. +Following up the idea that an explosion is a sudden combustion, he +submitted a variety of mixtures of oxidising and combustible agents to the +violent shock of a detonator of fulminate. These mixtures were made in +such proportions that the mutual oxidation or de-oxidation should be +theoretically complete. Among them are the following:-- + +1. One chemical equivalent of nitro-benzene to equivalents of nitric acid. + +2. Five equivalents of picric acid to 13 equivalents of nitric acid. + +3. Eighty-seven equivalents of nitro-naphthalene to 413 equivalents of +nitric acid. + +4. Porous cakes, or lumps of chlorate of potash, exploded violently with +bisulphide of carbon, nitro-benzol, carbonic acid, sulphur, benzene, and +mixtures of these substances. + +No. 1 covers the explosive known as _Hellhoffite_, and No. 2 is really +oxonite, and No. 4 resembles rack-a-rock, an explosive invented by Mr S.R. +Divine, and consisting of a mixture of chlorate of potash and nitro- +benzol. Roburite, bellite, and securite should perhaps be regarded as +belonging to the Sprengel class of explosives, otherwise this class is not +manufactured or used in England. The principal members are known as +_Hellhoffite_, consisting of a mixture of nitro-petroleum or nitro-tar +oils and nitric acid, or of meta-di-nitro-benzol and nitric acid; +_Oxonite_, consisting of picric and nitric acids; and _Panclastite_, a +name given to various mixtures, proposed by M. Turpin, such as liquid +nitric peroxide, with bisulphide of carbon, benzol, petroleum, ether, or +mineral oils. + +~Picric Acid, Tri-nitro-Phenol, or Carbazotic Acid.~--Picric acid, or a +tri-nitro-phenol (C_{6}H_{2}(NO_{2})_{3}OH)[2:4:6], is produced by the +action of nitric acid on many organic substances, such as phenol, indigo, +wool, aniline, resins, &c. At one time a yellow gum from Botany Bay +(_Xanthorrhoea hastilis_) was chiefly used. One part of phenol (carbolic +acid), C_{6}H_{5}OH, is added to 3 parts of strong fuming nitric acid, +slightly warmed, and when the violence of the reaction has subsided, +boiled till nitrous fumes are no longer evolved. The resinous mass thus +produced is boiled with water, the resulting picric acid is converted into +a sodium salt by a solution of sodium carbonate, which throws down sodium +picrate in crystals. + +Phenol-sulphuric acid is now, however, more generally used, and the +apparatus employed for producing it closely resembles that used in making +nitro-benzol. It is also made commercially by melting carbolic acid, and +mixing it with strong sulphuric acid, then diluting the "sulpho- +carbolic"[A] acid with water, and afterwards running it slowly into a +stone tank containing nitric acid. This is allowed to cool, where the +crude picric acid crystallises out, and the acid liquid (which contains +practically no picric acid, but only sulphuric acid, with some nitric +acid) being poured down the drains. The crude picric acid is then +dissolved in water by the aid of steam, and allowed to cool when most of +the picric acid recrystallises. The mother liquor is transferred to a tank +and treated with sulphuric acid, when a further crop of picric acid +crystals is obtained. The crystals of picric acid are further purified by +recrystallisation, drained, and dried at 100 deg. F. on glazed earthenware +trays by the aid of steam. It can also be obtained by the action of nitric +acid on ortho-nitro-phenol, para-nitro-phenol, and di-nitro-phenol (2:4 +and 2:6), but not from meta-nitro-phenol, a fact which indicates its +constitution.[B] + +[Footnote A: O. and p. phenolsulphonic acids. + +C_{3}H_{4}(OH).SO_{3}H + 3HNO_{3} = C_{6}H_{2}(NO_{2})_{3}OH + H_{2}SO_{4} ++ 2H_{2}O. (Picric acid).] + +[Footnote B: Carey Lea, _Amer. Jour. Sci._, (ii.), xxxii. 180.] + +Picric acid crystallises in yellow shining prisms or laminae having an +intensely bitter taste, and is poisonous. It melts at 122.5 deg. C., sublimes +when cautiously heated, dissolves sparingly in cold water, more easily in +hot water, still more in alcohol. It stains the skin an intense yellow +colour, and is used as a dye for wool and silk. It is a strong acid, +forming well crystallised yellow salts, which detonate violently when +heated, some of them also by percussion. The potassium salt, +C_{6}H_{2}(NO_{2})_{3}OK, crystallises in long needles very slightly +soluble in water. The sodium, ammonium, and barium salts are, however, +easily soluble in water. Picric acid, when heated, burns with a luminous +and smoky flame, and may be burnt away in large quantity without +explosion; but the mere contact of certain metallic oxides, with picric +acid, in the presence of heat, develops powerful explosives, which are +capable of acting as detonators to an indefinite amount of the acid, wet +or dry, which is within reach of their detonative influence. The formula +of picric acid is + +C_{6}H_{2}|(NO_{2})_{3} + |OH. + +which shows its formation from phenol (C_{6}H_{5}OH.), three hydrogen +atoms being displaced by the NO_{2} group. The equation of its formation +from phenol is as follows:-- + +C_{6}H_{5}.OH + 3HNO_{3} = C_{6}H_{2}(NO_{2})_{3}OH + 3H_{2}O. + +According to Berthelot, its heat of formation from its elements equals +49.1 calories, and its heat of total combustion by free oxygen is equal to ++618.4 cals. It hardly contains more than half the oxygen necessary for +its complete combustion. + +2C_{6}H_{2}(NO_{2})_{3}OH + O_{10} = 12CO_{2} + 3H_{2} + 3N_{2}. + +The percentage composition of picric acid is--Nitrogen, 18.34; oxygen, +49.22; hydrogen, 1.00; and carbon, 31.44, equal to 60.26 per cent. of +NO_{2}. The products of decomposition are carbonic acid, carbonic oxide, +carbon, hydrogen, and nitrogen, and the heat liberated, according to +Berthelot, would be 130.6 cals., or 570 cals. per kilogramme. The reduced +volume of the gases would be 190 litres per equivalent, or 829 litres per +kilogramme. To obtain a total combustion of picric acid it is necessary +to mix with it an oxidising agent, such as a nitrate, chlorate, &c. It has +been proposed to mix picric acid (10 parts) with sodium nitrate (10 parts) +and potassium bichromate (8.3 parts). These proportions would furnish a +third of oxygen in excess of the necessary proportion. + +Picric acid was not considered to be an explosive, properly so called, for +a long time after its discovery, but the disastrous accident which +occurred at Manchester (_vide_ Gov. Rep. No. LXXXI., by Colonel (now Sir +V.D.) Majendie, C.B.), and some experiments made by Dr Dupre and Colonel +Majendie to ascertain the cause of the accident, conclusively proved that +this view was wrong. The experiments of Berthelot (_Bull. de la Soc. Chim. +de Paris_, xlix., p. 456) on the explosive decomposition of picric acid +are also deserving of attention in this connection. If a small quantity of +picric acid be heated in a moderate fire, in a crucible, or even in an +open test tube, it will melt (at 120 deg. C. commercial acid), then give off +vapours which catch fire upon contact with air, and burn with a sooty +flame, without exploding. If the burning liquid be poured out upon a cold +slab, it will soon go out. A small quantity carefully heated in a tube, +closed at one end, can even be completely volatilised without apparent +decomposition. It is thus obvious that picric acid is much less explosive +than the nitric ethers, such as nitro-glycerol and nitro-cellulose, and +very considerably less explosive than the nitrogen compounds and +fulminates. + +It would, however, be quite erroneous to assume that picric acid cannot +explode when simply heated. On the contrary, Berthelot has proved that +this is not the case. If a glass tube be heated to redness, and a minute +quantity of picric acid crystals be then thrown in, it will explode with a +curious characteristic noise. If the quantity be increased so that the +temperature of the tube is materially reduced, no explosion will take +place at once, but the substance will volatilise and then explode, though +with much less violence than before, in the upper part of the tube. +Finally, if the amount of picric acid be still further increased under +these conditions, it will undergo partial decomposition and volatilise, +but will not even deflagrate. Nitro-benzene, di-nitrobenzene, and mono-, +di-, and tri-nitro-naphthalenes behave similarly. + +The manner in which picric acid will decompose is thus dependent upon the +initial temperature of the decomposition, and if the surrounding material +absorb heat as fast as it is produced by the decomposition, there will be +no explosion and no deflagration. If, however, the absorption is not +sufficient to prevent deflagration, this may so increase the temperature +of the surrounding materials that the deflagration will then end in +explosion. Thus, if an explosion were started in an isolated spot, it +would extend throughout the mass, and give rise to a general explosion. + +In the manufacture of picric acid the first obvious and most necessary +precaution is to isolate the substance from other chemicals with which it +might accidentally come into contact. If pure materials only are used, the +manufacture presents no danger. The finished material, however, must be +carefully kept from contact with nitrates, chlorates, or oxides. If only a +little bit of lime or plaster become accidentally mixed with it, it may +become highly dangerous. A local explosion may occur which might have the +effect of causing the explosion of the whole mass. Picric acid can be +fired by a detonator, 5-grain fulminate, and M. Turpin patented the use of +picric acid, unmixed with any other substance, in 1885. The detonation of +a small quantity of dry picric acid is sufficient to detonate a much +larger quantity containing as much as 17 per cent. of water. + +It is chiefly due to French chemists (and to Dr Sprengel) that picric acid +has come to the front as an explosive. Melinite,[A] a substance used by +the French Government for filling shells, was due to M. Turpin, and is +supposed to be little else than fused picric acid mixed with gun-cotton +dissolved in some solvent (acetone or ether-alcohol). Sir F.A. Abel has +also proposed to use picric acid, mixed with nitrate of potash (3 parts) +and picrate of ammonia (2 parts) as a filling for shells. This substance +requires a violent blow and strong confinement to explode it. I am not +aware, however, that it has ever been officially adopted in this country. +Messrs Designolles and Brugere have introduced military powders, +consisting of mixtures of potassium and ammonium picrates with nitrate of +potassium. M. Designolles introduced three kinds of picrate powders, +composed as follows:-- + + ___________________________________________________________________ +| | | | | +| | For Torpedoes | For Guns. | For Small | +| | and Shells. | Ordinary. Heavy. | Arms. | +|___________________|_______________|___________________|___________| +| | | | | | +| Picrate of Potash | 55-50 | 16.4- 9.6 | 9 | 28.6-22.9 | +| Saltpetre | 45-50 | 74.4-79.7 | 80 | 65.0-69.4 | +| Charcoal | ... | 9.2-10.7 | 11 | 6.4- 7.7 | +|___________________|_______________|___________|_______|___________| + +They were made much like ordinary gunpowder, 6 to 14 per cent. of moisture +being added when being milled. The advantages claimed over gunpowder are +greater strength, and consequently greater ballistic or disruptive effect, +comparative absence of smoke, and freedom from injurious action on the +bores of guns, owing to the absence of sulphur. Brugere's powder is +composed of ammonium picrate and nitre, the proportions being 54 per cent. +picrate of ammonia and 46 per cent. potassic nitrate. It is stable, safe +to manufacture and handle, but expensive. It gives good results in the +Chassepot rifle, very little smoke, and its residue is small, and consists +of carbonate of potash. It is stated that 2.6 grms. used in a rifle gave +an effect equal to 5.5 grms. of ordinary gunpowder. + +[Footnote A: The British Lydite and the Japanese Shimose are said to be +identical with Melinite.] + +Turpin has patented various mixtures of picric acid, with gum-arabic, +oils, fats, collodion jelly, &c. When the last-named substance is diluted +in the proportion of from 3 to 5 per cent. in a mixture of ether and +alcohol, he states that the blocks of picric acid moulded with it will +explode in a closed chamber with a priming of from 1 to 3 grammes of +fulminate. He also casts picric acid into projectiles, the cast acid +having a density of about 1.6. In this state it resists the shock produced +by the firing of a cannon, when contained in a projectile, having an +initial velocity of 600 metres. It is made in the following way:--The acid +is fused in a vessel provided with a false bottom, heated to 130 deg. to 145 deg. +C. by a current of steam under pressure, or simply by the circulation +under the false bottom of a liquid, such as oil, chloride of zinc, +glycerine, &c., heated to the same temperature. The melted picric acid is +run into moulds of a form corresponding to that of the blocks required, or +it may be run into projectiles, which should be heated to a temperature of +about 100 deg. C., in order to prevent too rapid solidification. + +When cresylic acid (or cresol, C_{6}H_{4}(CH_{3})OH.) is acted upon by +nitric acid it produces a series of nitro compounds very similar to those +formed by nitric acids on phenol, such as sodium di-nitro-cresylate, known +in the arts as victoria yellow. Naphthol, a phenol-like body obtained from +naphthalene, under the same conditions, produces sodium di-nitro- +naphthalic acid, C_{10}H_{6}(NO_{2})_{2}O. The explosive known as +"roburite" contains chloro-nitro-naphthalene, and romit, a Swedish +explosive, nitro-naphthalene. + +~Tri-nitro-cresol~, C_{7}H_{4}(NO_{2})_{3}OH.--A body very similar to tri- +nitro-phenol, crystallises in yellow needles, slightly soluble in cold +water, rather more so in boiling water, alcohol, and ether. It melts at +about 100 deg. C. In France it is known as "Cresilite," and mixed with +melinite, is used for charging shells. By neutralising a boiling saturated +solution of tri-nitro-cresol with ammonia, a double salt of ammonium and +nitro-cresol crystallises out upon cooling, which is similar to ammonium +picrate. This salt is known as "Ecrasite," and has been used in Austria +for charging shells. It is a bright yellow solid, greasy to the touch, +melts at 100 deg. C., is unaffected by moisture, heat, or cold, ignites when +brought into contact with an incandescent body or open flame, burning +harmlessly away unless strongly confined, and is insensitive to friction +or concussion. It is claimed to possess double the strength of dynamite, +and requires a special detonator (not less than 2 grms. of fulminate) to +provoke its full force. Notwithstanding the excellent properties +attributed to this explosive, Lieut. W. Walke ("Lectures on Explosives," +p. 181) says, "Several imperfectly explained and unexpected explosions +have occurred in loading shells with this substance, and have prevented +its general adoption up to the present time." + +~The Fulminates.~--The fulminates are salts of fulminic acid, +C_{2}N_{2}O_{2}H_{2}. Their constitution is not very well understood. Dr +E. Divers, F.R.S., and Mr Kawakita (_Chem. Soc. Jour._, 1884, pp. 13-19), +give the formulae of mercury and silver fulminates as + + OC = N AgOC = N + / | \ | \ +Hg | O and | O + \ | / | / + -C = N AgC = N + +whereas Dr H.E. Armstrong, F.R.S., would prefer to write the formula of +fulminic acid + +ON.C.OH. + | + C(N.OH), + +and A.F. Holleman (_Berichte_, v. xxvi., p. 1403), assigns to mercury +fulminate the formula + + C:N.O +Hg | | + C:N.O, + +and R. Schol (_Ber._, v. xxiii., p. 3505), + + C:NO +|| Hg. + C:NO + +They are very generally regarded as iso-nitroso compounds. + +The principal compound of fulminic acid is the mercury salt commonly known +as fulminating mercury. It is prepared by dissolving mercury in nitric +acid, and then adding alcohol to the solution, 1 part of mercury and 12 +parts of nitric acid of specific gravity 1.36, and 5-1/2 parts of 90 per +cent. alcohol being used. As soon as the mixture is in violent reaction, 6 +parts more of alcohol are added slowly to moderate the action. At first +the mixture blackens from the separation of mercury, but this soon +vanishes, and is succeeded by crystalline flocks of mercury fulminate +which fall to the bottom of the vessel. During the reaction, large +quantities of volatile oxidation products of alcohol, such as aldehyde, +ethylic nitrate, &c., are evolved from the boiling liquid, whilst others, +such as glycollic acid, remain in solution. The mercury fulminate is then +crystallised from hot water. It forms white silky, delicate needles, which +are with difficulty soluble in cold water. In the dry state it is +extremely explosive, detonating on heating, or by friction or percussion, +as also on contact with concentrated sulphuric acid. The reaction that +takes place upon its decomposition is as follows:-- + +C_{2}N_{2}O_{2}Hg = Hg + 2CO + N_{2} +(284) + +According to this equation 1 grm. of the fulminate should yield 235.8 c.c. +(= 66.96 litres for 284 grms.). Berthelot and Vicille have obtained a +yield of 234.2 c.c., equal to 66.7 litres for one equivalent 284 grms. + +Dry fulminate explodes violently when struck, compressed, or touched with +sulphuric acid, or as an incandescent body. If heated slowly, it explodes +at 152 deg. C., or if heated rapidly, at 187 deg. C. It is often used mixed with +potassium chlorate in detonators. The reaction which takes place in this +case is 3C_{2}N_{2}O_{2}Hg + 2KClO_{3} = 3Hg + 6CO_{2} + 3N_{2} + 2KCl. + +On adding copper or zinc to a hot saturated solution of the salt, +fulminate of copper or zinc is formed. The copper salt forms highly +explosive green crystals. There is also a double fulminate of copper of +ammonia, and of copper and potassium. Silver fulminite, +C_{2}N_{2}O_{2}Ag_{2}, is prepared in a similar manner to the mercury +salt. It separates in fine white needles, which dissolve in 36 parts of +boiling water, and are with difficulty soluble in cold water. At above +100 deg. C., or on the weakest blow, it explodes with fearful violence. Even +when covered with water it is more sensitive than the mercury salt. It +forms a very sensitive double salt with ammonia and several other metals. +With hydrogen it forms the acid fulminate of silver. It is used in +crackers and bon-bons, and other toy fireworks, in minute quantities. Gay +Lussac found it to be composed as follows:--Carbon, 7.92 per cent.; +nitrogen, 9.24 per cent.; silver, 72.19 per cent.; oxygen, 10.65 per +cent.; and he assigned to it the formula, C_{2}N_{2}Ag_{2}O_{2}. Laurent +and Gerhardt give it the formula, C_{2}N(NO_{2})Ag_{2}, and thus suppose +it to contain nitryl, NO_{2}. + +On adding potassium chloride to a boiling solution of argentic fulminate, +as long as a precipitate of argentic chloride forms, there is obtained on +evaporation brilliant white plates, of a very explosive nature, of +potassic argentic fulminate, C(NO_{2})KAg.CN, from whose aqueous solution +nitric acid precipitates a white powder of hydric argentic fulminate, +C(NO_{2})HAg.CN. All attempts to prepare fulminic acid, or nitro-aceto- +nitrile, C(NO_{2})H_{2}CN, from the fulminates have failed. There is a +fulminate of gold, which is a violently explosive buff precipitate, formed +when ammonia is added to ter-chloride of gold, and fulminate of platinum, +a black precipitate formed by the addition of ammonia to a solution of +oxide platinum, in dilute sulphuric acid. + +Fulminating silver is a compound obtained by the action of ammonia on +oxide of silver. It is a very violent explosive. Pure mercury fulminate +may be kept an indefinite length of time. Water does not affect it. It +explodes at 187 deg. C., and on contact with an ignited body. It is very +sensitive to shock and friction, even that of wood upon wood. It is used +for discharging bullets in saloon rifles. Its inflammation is so sudden +that it scatters black powder on which it is placed without igniting it, +but it is sufficient to place it in an envelope, however weak, for +ignition to take place, and the more resisting the envelope the more +violent is the shock, a circumstance that plays an important part in caps +and detonators. The presence of 30 per cent. of water prevents +decomposition, 10 per cent. prevents explosion. This is, however, only +true for small quantities, and does not apply to silver fulminate, which +explodes under water by friction. Moist fulminates slowly decompose on +contact with the oxidisable metals. The (reduced) volume of gases obtained +from 1 kilo. is according to Berthelot, 235.6 litres. The equation of its +decomposition is C_{2}HgN_{2}O_{2} = 2CO + N_{2} + Hg. + +Fulminate of mercury is manufactured upon the large scale by two methods. +One of these, commonly known as the German method, is conducted as +follows:--One part of mercury is dissolved in 12 parts of nitric acid of a +specific gravity of 1.375, and to this solution 16.5 parts of absolute +alcohol are added by degrees, and heat is then slowly applied to the +mixture until the dense fumes first formed have disappeared, and when the +action has become more violent some more alcohol is added, equal in volume +to that which has already been added. This is added very gradually. The +product obtained, which is mercury fulminate, is 112 per cent. of the +mercury employed. Another method is to dissolve 10 parts of mercury in 100 +parts of nitric acid of a gravity of 1.4, and when the solution has +reached a temperature of 54 deg. C, to pour it slowly through a glass funnel +into 83 parts of alcohol. When the effervescence ceases, it is filtered +through paper filters, washed, and dried over hot water, at a temperature +not exceeding 100 deg. C. The fulminate is then carefully packed in paper +boxes, or in corked bottles. The product obtained by this process is 130 +per cent. of the mercury taken. This process is the safest, and at the +same time the cheapest. Fulminate should be kept, if possible, in a damp +state. Commercial fulminate is often adulterated with chlorate of potash. + +~Detonators~, or caps, are metallic capsules, usually of copper, and +resemble very long percussion caps. The explosive is pure fulminate of +mercury, or a mixture of that substance with nitrate or chlorate of +potash, gun-powder, or sulphur. The following is a common cap mixture:-- +100 parts of fulminate of mercury and 50 parts of potassium nitrate, or +100 parts of fulminate and 60 parts of meal powder. Silver fulminate is +also sometimes used in caps. There are eight sizes made, which vary in +dimensions and in amount of explosive contained. They are further +distinguished as singles, doubles, trebles, &c., according to their +number. Colonel Cundill, R.A. ("Dict. of Explosives"), gives the following +list:-- + +No. 1 contains 300 grms. of explosive per 1000. + " 2 " 400 " " " " " + " 3 " 540 " " " " " + " 4 " 650 " " " " " + " 5 " 800 " " " " " + " 6 " 1,000 " " " " " + " 7 " 1,500 " " " " " + " 8 " 2,000 " " " " " + +Trebles are generally used for ordinary dynamite, 5, 6, or 7 for +gun-cotton, blasting gelatine, roburite, &c. + +In the British service percussion caps, fuses, &c., are formed of 6 parts +by weight of fulminate of mercury, 6 of chlorate of potash, and 4 of +sulphide of antimony; time fuses of 4 parts of fulminate, 6 of potassium +chlorate, 4 of sulphide of antimony, the mixture being damped with a +varnish consisting of 645 grains of shellac dissolved in a pint of +methylated spirit. Abel's fuse (No. 1) consists of a mixture of sulphide +of copper, phosphide of copper, chlorate of potash, and No. 2 of a mixture +of gun-cotton and gun-powder. They are detonated by means of a platinum +wire heated to redness by means of an electric current. Bain's fuse +mixture is a mixture of subphosphide of copper, sulphide of antimony, and +chlorate of potash. + +In the manufacture of percussion caps and detonators the copper blanks are +cut from copper strips and stamped to the required shape. The blanks are +then placed in a gun-metal plate, with the concave side uppermost--a tool +composed of a plate of gun-metal, in which are inserted a number of copper +points, each of the same length, and so spaced apart as to exactly fit +each point into a cap when inverted over a plate containing the blanks. +The points are dipped into a vessel containing the cap composition, which +has been previously moistened with methylated spirit. It is then removed +and placed over the blanks, and a slight blow serves to deposit a small +portion of the cap mixture into each cap. A similar tool is then dipped +into shellac varnish, removed and placed over the caps, when a drop of +varnish from each of the copper points falls into the caps, which are then +allowed to dry. This is a very safe and efficacious method of working. + +At the works of the Cotton-Powder Company Limited, at Faversham, the +fulminate is mixed wet with a very finely ground mixture of gun-cotton and +chlorate of potash, in about the proportions of 6 parts fulminate, 1 part +gun-cotton, and 1 part chlorate. The water in which the fulminate is +usually stored is first drained off, and replaced by displacement by +methyl-alcohol. While the fulminate is moist with alcohol, the gun-cotton +and chlorate mixture is added, and well mixed with it. This mixture is +then distributed in the detonators standing in a frame, and each detonator +is put separately into a machine for the purpose of pressing the paste +into the detonator shell. + +At the eleventh annual meeting of the representatives of the Bavarian +chemical industries at Regensburg, attention was drawn to the unhealthy +nature of the process of charging percussion caps. Numerous miniature +explosions occur, and the air becomes laden with mercurial vapours, which +exercise a deleterious influence upon the health of the operatives. There +is equally just cause for apprehension in respect to the poisonous gases +which are evolved during the solution of mercury in nitric acid, and +especially during the subsequent treatment with alcohol. Many methods have +been proposed for dealing with the waste products arising during the +manufacture and manipulation of fulminate of mercury, but according to +Kaemmerer, only one of comparatively recent introduction appears to be at +all satisfactory. It is based upon the fact that mercuric fulminate, when +heated with a large volume of water under high pressure, splits up into +metallic mercury and non-explosive mercurial compounds of unknown +composition. + +In mixing the various ingredients with mercury fulminate to form cap +mixtures, they should not be too dry; in fact, they are generally more or +less wet, and mixed in small quantities at a time, in a special house, the +floors of which are covered with carpet, and the tables with felt. Felt +shoes are also worn by the workpeople employed. All the tools and +apparatus used must be kept very clean; for granulating, hair sieves are +used, and the granulated mixture is afterwards dried on light frames, with +canvas trays the bottoms of which are covered with thin paper, and the +frames fitted with indiarubber cushions, to reduce any jars they may +receive. The windows of the building should be painted white to keep out +the rays of the sun. + +Mr H. Maxim, of New York, has lately patented a composition for detonators +for use with high explosives, which can also be thrown from ordnance in +considerable quantities with safety. The composition is prepared as +follows:--Nitro-glycerine is thickened with pyroxyline to the consistency +of raw rubber. This is done by employing about 75 to 85 per cent. of +nitro-glycerine, and 15 to 25 per cent. of pyroxyline, according to the +stiffness or elasticity of the compound desired. Some solvent that +dissolves the nitro-cotton is also used. The product thus formed is a kind +of blasting gelatine, and should be in a pasty condition, in order that it +may be mixed with fulminate of mercury. The solvent used is acetone, and +the quantity of fulminate is between 75 to 85 per cent. of the entire +compound. If desired, the compound can be made less sensitive to shocks by +giving it a spongy consistency by agitating it with air while it is still +in a syrupy condition. The nitro-glycerine, especially in this latter +case, may be omitted. In some cases, when it is desirable to add a +deterring medium, nitro-benzene or some suitable gum is added. + +[Illustration: FIG. 34. METHOD OF PREPARING THE CHARGE.] + +The method of preparing a blasting charge is as follows:--A piece of +Bickford fuse of the required length is cut clean and is inserted into a +detonator until it reaches the fulminate. The upper portion of the +detonator is then squeezed round the fuse with a pair of nippers. The +object of this is not only to secure that the full power of the detonator +may be developed, but also to fix the fuse in the cap (Fig. 34). When the +detonator, &c., is to be used under water, or in a damp situation, grease +or tallow should be placed round the junction of the cap with the fuse, in +order to make a water-tight joint. A cartridge is then opened and a hole +made in its upper end, and the detonator pushed in nearly up to the top. +Gun-cotton or tonite cartridges generally have a hole already made in the +end of the charge. Small charges of dry gun-cotton, known as primers, are +generally used to explode wet gun-cotton. The detonators (which are often +fired by electrical means) are placed inside these primers (Fig. 35). + +[Illustration: FIG. 35. PRIMER.] + +One of the forms of electric exploders used is shown in Fig. 36. This +apparatus is made by Messrs John Davis & Son, and is simply a small hand +dynamo, capable of producing a current of electricity of high tension. +This firm are also makers of various forms of low tension exploders. A +charge having been prepared, as in Fig. 34, insert into the bore-hole one +or more cartridges as judged necessary, and squeeze each one down +separately with a _wooden_ rammer, so as to leave no space round the +charge, and above this insert the cartridge containing the fuse and +detonator. Now fill up the rest of the bore-hole with sand, gravel, water, +or other tamping. With gelatine dynamites a firm tamping may be used, but +with ordinary dynamite loose sand is better. The charge is now ready for +firing. + +[Illustration: FIG. 36.--ELECTRIC EXPLODER.] + + + + +CHAPTER VI. + +_SMOKELESS POWDERS._ + +Smokeless Powder in General--Cordite--Axite--Ballistite--U.S. Naval +Powder--Schultze's E.G. Powder--Indurite--Vielle Poudre--Rifleite-- +Cannonite--Walsrode--Cooppal Powders--Amberite--Troisdorf--Maximite-- +Picric Acid Powders, &c., &c. + + +The progress made in recent years in the manufacture of smokeless powders +has been very great. With a few exceptions, nearly all these powders are +nitro compounds, and chiefly consist of some form of nitro-cellulose, +either in the form of nitro-cotton or nitro-lignine; or else contain, in +addition to the above, nitro-glycerine, with very often some such +substance as camphor, which is used to reduce the sensitiveness of the +explosive. Other nitro bodies that are used, or have been proposed, are +nitro-starch, nitro-jute, nitrated paper, nitro-benzene, di-nitro-benzene, +mixed with a large number of other chemical substances, such as nitrates, +chlorates, &c. And lastly, there are the picrate powders, consisting of +picric acid, either alone or mixed with other substances. + +The various smokeless powders may be roughly divided into military and +sporting powders. But this classification is very rough; because although +some of the better known purely military powders are not suited for use in +sporting guns, nearly all the manufacturers of sporting powders also +manufacture a special variety of their particular explosive, fitted for +use in modern rifles or machine guns, and occasionally, it is claimed, for +big guns also. + +Of the purely military powders, the best known are cordite, ballistite, +and the French B.N. powder, the German smokeless (which contains nitro- +glycerine and nitro-cotton); and among the general powders, two varieties +of which are manufactured either for rifles or sporting guns, Schultze's, +the E.C. Powders, Walsrode powder, cannonite, Cooppal powder, amberite, +&c., &c. + +~Cordite~, the smokeless powder adopted by the British Government, is the +patent of the late Sir F.A. Abel and Sir James Dewar, and is somewhat +similar to blasting gelatine. It is chiefly manufactured at the Royal +Gunpowder Factory at Waltham Abbey, but also at two or three private +factories, including those of the National Explosives Company Limited, the +New Explosives Company Limited, the Cotton-Powder Company Limited, Messrs +Kynock's, &c. As first manufactured it consisted of gun-cotton 37 per +cent., nitro-glycerine 58 per cent., and vaseline 5 per cent., but the +modified cordite now made consists of 65 per cent. gun-cotton, 30 per +cent. of nitro-glycerine, and 5 per cent. of vaseline. The gun-cotton used +is composed chiefly of the hexa-nitrate,[A] which is not soluble in nitro- +glycerine. It is therefore necessary to use some solvent such as acetone, +in order to form the jelly with nitro-glycerine. The process of +manufacture of cordite is very similar, as far as the chemical part of the +process is concerned, to that of blasting gelatine, with the exception +that some solvent for the gun-cotton, other than nitro-glycerine has to be +used. Both the nitro-glycerine and the gun-cotton employed must be as dry +as possible, and the latter should not contain more than .6 per cent. of +mineral matter and not more than 10 per cent. of soluble nitro-cellulose, +and a nitrogen content of not less than 12.5 per cent. The dry gun-cotton +(about 1 per cent. of moisture) is placed in an incorporating tank, which +consists of a brass-lined box, some of the acetone is added, and the +machine (Fig. 29), is started; after some time the rest of the acetone is +added (20 per cent. in all) and the paste kneaded for three and a half +hours. At the end of this time the Vaseline is added, and the kneading +continued for a further three and a half hours. The kneading machine (Fig. +29) consists of a trough, composed of two halves of a cylinder, in each of +which is a shaft which carries a revolving blade. These blades revolve in +opposite directions, and one makes about half the number of revolutions of +the other. As the blades very nearly touch the bottom of the trough, any +material brought into the machine is divided into two parts, kneaded +against the bottom, then pushed along the blade, turned over, and +completely mixed. During kneading the acetone gradually penetrates the +mixture, and dissolves both the nitro-cellulose and nitro-glycerine, and a +uniform dough is obtained which gradually assumes a buff colour. During +kneading the mass becomes heated, and therefore cold water is passed +through the jacket of the machine to prevent heating the mixture above the +normal temperature, and consequent evaporation of the acetone. The top of +the machine is closed in with a glass door, in order to prevent as far as +possible the evaporation of the solvent. When the various ingredients are +formed into a homogeneous mass, the mixture is taken to the press house, +where in the form of a plastic mass it is placed in cylindrical moulds. +The mould is inserted in a specially designed press, and the cordite paste +forced through a die with one or more holes. The paste is pressed out by +hydraulic pressure, and the long cord is wound on a metal drum (Fig. 38), +or cut into lengths; in either case the cordite is now sent to the drying +houses, and dried at a temperature of about 100 deg. F. from three to fourteen +days, the time varying with the size. This operation drives off the +acetone, and any moisture the cordite may still contain, and its diameter +decreases somewhat. In case of the finer cordite, such as the rifle +cordite, the next operation is blending. This process consists in mounting +ten of the metal drums on a reeling machine similar to those used for +yarns, and winding the ten cords on to one drum. This operation is known +as "ten-stranding." Furthermore, six "ten-stranded" reels are afterwards +wound upon one, and the "sixty-stranded" reel is then ready to be sent +away, This is done in order to obtain a uniform blending of the material. +With cordite of a larger diameter, the cord is cut into lengths of 12 +inches. Every lot of cordite from each manufacturer has a consecutive +number, numbers representing the size and one or more initial letters to +identify the manufacturer. These regulations do not apply to the Royal +Gunpowder Factory, Waltham Abbey. The finished cordite resembles a cord of +gutta-percha, and its colour varies from light to dark brown. It should +not look black or shrivelled, and should always possess sufficient +elasticity to return to its original form after slight bending. Cordite is +practically smokeless. On explosion a very thin vapour is produced, which +is dissipated rapidly. This smokelessness can be understood from the fact +that the products of combustion are nearly all non-condensible gases, and +contain no solid products of combustion which would cause smoke. For the +same muzzle velocity a smaller charge of cordite than gunpowder is +required owing to the greater amount of gas produced. Cordite is very slow +in burning compared to gunpowder. For firing blank cartridges cordite +chips containing no vaseline is used. The rate at which cordite explodes +depends in a measure upon the diameter of the cords, and the pressure +developed upon its mechanical state. The sizes of cordite used are given +by Colonel Barker, R.A., as follows:-- + +For the .303 rifle .0375 inch diameter. + " 12 Pr. B.L. gun .05 " + " " .075 " + " 4.7-inch Q.F. gun .100 " + " 6-inch Q.F. gun .300 " + " heavy guns .40 to .50 " + +For rifles the cordite is used in bundles of sixty strands, in field-guns +in lengths of 11 to 12 inches, and the thicker cordite is cut up into +14-inch lengths. Colonel Barker says that the effect of heat upon cordite +is not greater as regards its shooting qualities than upon black powder, +and in speaking of the effect that cordite has upon the guns in which it is +used (R.A. Inst.) said that they had at Waltham Abbey a 4.7-inch Q.F. gun +that had fired 40 rounds of black powder, and 249 rounds of cordite (58 +per cent. nitro-glycerine) and was still in excellent condition, and +showed very little sign of action, and also a 12-lb. B.L. gun that had +been much used and was in no wise injured. + +[Footnote A: The gun-cotton used contains 12 per cent. of soluble +gun-cotton, and a nitrogen content of not less than 12.8 to 13.1 per cent.] + +[Illustration: Fig. 37 Scale, 1 inch = 1 foot. Single Strand Reel.] + +[Illustration: FIG. 38.--"TEN-STRANDING."] + +In some experiments made by Captain Sir A. Noble,[A] with the old cordite +containing 58 per cent. nitro-glycerine, a charge of 5 lbs. 10 oz. of +cordite of 0.2 inch diameter was fired. The mean chamber crusher gauge +pressure was 13.3 tons per square inch (maximum 13.6, minimum 12.9), or a +mean of 2,027 atmospheres (max. 2,070, min. 1,970). The muzzle velocity +was 2,146 foot seconds, and the muzzle energy 1,437 foot tons. A gramme of +cordite generated 700 c.c. of permanent gases at 0 deg. C. and 760 mm. +pressure. The quantity of heat developed was 1,260 gramme units. In the +case of cordite, as also with ballistite, a considerable quantity of +aqueous vapour has to be added to the permanent gases formed. A similar +trial, in which 12 lbs. of ordinary pebble powder was used, gave a +pressure of 15.9 tons per square inch, or a mean of 2,424 atmospheres. It +gave a 45-lb. projectile a mean muzzle velocity of 1,839 foot seconds, +thus developing a muzzle energy of 1,055 foot tons. A gramme of this +powder at 0 deg. C. and 760 mm. generates 280 c.c. of permanent gases, and +develops 720 grm. units of heat. + +[Footnote A: _Proc. Roy. Soc._, vol. lii., No. 315.] + +In a series of experiments conducted by the War Office Chemical Committee +on Explosives in 1891, it was conclusively shown that considerable +quantities of cordite may be burnt away without explosion. A number of +wooden cases, containing 500 to 600 lbs. each of cordite, were placed upon +a large bonfire of wood, and burned for over a quarter of an hour without +explosion. At Woolwich in 1892 a brown paper packet containing ten cordite +cartridges was fired into with a rifle (.303) loaded with cordite, without +the explosion of a single one of them, which shows its insensibility to +shock. + +With respect to the action of cordite upon guns, Sir A. Noble points out +that the erosion caused is of a totally different kind to that of black +powder. The surface of the barrel in the case of cordite appears to be +washed away smoothly by the gases, and not pitted and eaten into as with +black powder. The erosion also extends over a shorter length of surface, +and in small arms it is said to be no greater than in the case of black +powder. Sir A. Noble says in this connection: "It is almost unnecessary to +explain that freedom from rapid erosion is of very high importance in view +of the rapid deterioration of the bores of large guns when fired with +charges developing very high energies. As might perhaps be anticipated +from the higher heat of ballistite, its erosive power is slightly greater +than that of cordite, while the erosive power of cordite is again slightly +greater than that of brown prismatic. Amide powder, on the other hand, +possesses the peculiarity of eroding very much less than any other powder +with which I have experimented, its erosive power being only one-fourth of +that of the other powders enumerated." + +TABLE GIVING SOME OF SIR. A. NOBLE'S EXPERIMENTS. + ________________________________________________________________________ +| | +| VELOCITIES OBTAINED. | +|________________________________________________________________________| +| | | | | | +| | In a 40 | In a 50 | In a 75 | In a 100 | +| | Cal. Gun.| Cal. Gun.| Cal. Gun.| Cal. Gun.| +|____________________________|__________|__________|__________|__________| +| | | | | | +| |Foot Secs.|Foot Secs.|Foot Sees.|Foot Secs.| +| | | | | | +|With cordite 0.4 in. diam. | 2,794 | 2,940 | 3,166 | 3,286 | +| " " 0.3 " | 2,469 | 2,619 | 2,811 | 2,905 | +| " ballistite 0.3 in. cubes| 2,416 | 2,537 | 2,713 | 2,806 | +| " French B.N. for | | | | | +| 6-inch guns | 2,249 | 2,360 | 2,536 | 2,616 | +| " prismatic amide | 2,218 | 2,342 | 2,511 | 2,574 | +| | | | | | +|____________________________|__________|__________|__________|__________| +| | +| ENERGIES REPRESENTED BY ABOVE VELOCITIES. | +|________________________________________________________________________| +| | | | | | +| |Foot Tons.|Foot Tons.|Foot Tons.|Foot Tons.| +| | | | | | +| Cordite 0.4 inch | 5,413 | 5,994 | 6,950 | 7,478 | +| Ballistite 0.3 inch cubes | 4,227 | 4,754 | 5,479 | 5,852 | +| French B.N. | 4,047 | 4,463 | 5,104 | 5,460 | +| Prismatic amide | 3,507 | 3,862 | 4.460 | 4,745 | +|____________________________|__________|__________|__________|__________| + +And again, in speaking of his own experiments, he says: "One 4.7-inch gun +has fired 1,219 rounds, and another 953, all with full charges of cordite, +while a 6-inch gun has fired 588 rounds with full charges, of which 355 +were cordite. In the whole of these guns, so far as I can judge, the +erosion is certainly not greater than with ordinary powder, and differs +from it remarkably in appearance. With ordinary powder a gun, when much +eroded, is deeply furrowed (these furrows having a great tendency to +develop into cracks), and presents much the appearance in miniature of a +very roughly ploughed field. With cordite, on the contrary, the surface +appears to be pretty smoothly swept away, while the length of the surface +eroded is considerably less." + +[Illustration: FIG. 39.--COMPARATIVE PRESSURE CURVES OF CORDITE AND BLACK +POWDER. _a_, Charge, 48 lbs. powder; _b_, charge, 13 lbs. 4 oz. cordite; +_c_, charge, 13 lbs. 4 oz. powder. Weight of projectile, 100 lbs. in +6-inch gun. M.V. Cordite = 1960 feet seconds.] + +The pressures given by cordite compared with those given by black powder +in the 6-inch gun will be seen upon reference to Fig. 39, which is taken +from Professor V.B. Lewes's paper, read before the Society of Arts; and +due to Dr W. Anderson, F.R.S., the Director-General of Ordnance Factories. + +It has been found that the erosive effect is in direct proportion to the +nitro-glycerine present. The cordite M.D., which contains only 30 per +cent. nitro-glycerine, gives only about half the erosive effect of the old +service cordite. With regard to the heating effect of cordite and cordite +M.D. on a rifle, Mr T.W. Jones made some experiments. He fired fifty +rounds of .303 cartridges in fifteen minutes in the service rifle. Cordite +raised the temperature of the rifle 270 deg. F., and cordite M.D. 160 deg. F. +only. + +With regard to the effect of heat upon cordite, there is some difference +of opinion. Dr W. Anderson, F.R.S., says that there is no doubt that the +effect of heat upon cordite is greater than upon black powder. At a +temperature of 110 deg. F. the cordite used in the 4.7-inch gun is +considerably affected as regards pressure. + +Colonel Barker, R.A., in reply to a question raised by Colonel Trench, +R.A. (at the Royal Artillery Institution), concerning the shooting +qualities of cordite heated to a temperature of 110 deg. F., said: "Heating +cordite and firing it hot undoubtedly does disturb its shooting qualities, +but as far as we can see, not much more than gunpowder. I fear that we +must always expect abnormal results with heated propellants, either +gunpowder or cordite; and when fired hot, the increase in pressure and +velocities will depend upon the heat above the normal or average +temperature at which firing takes place." Colonel Barker also, in +referring to experiments that had been made in foreign climates, said: +"Climatic trials have been carried out all over the world, and they have +so far proved eminently satisfactory. The Arctic cold of the winter in +Canada, with the temperature below zero, and the tropical sun of India, +have as yet failed to shake the stability of the composition, or +abnormally injure its shooting qualities." Dr Anderson is of opinion that +cordite should not be stored in naval magazines near to the boilers. +Professor Vivian B. Lewes, in his recent Cantor Lectures before the +Society of Arts, suggests that the magazines of warships should be water- +jacketed, and maintained at a temperature that does not rise above 100 deg. F. + +~Axite.~--This powder is manufactured by Messrs Kynock Limited, at their +works at Witton, Birmingham. The main constituents of cordite are retained +although the proportions are altered; ingredients are added which impart +properties not possessed by cordite, and the methods of its manufacture +have been modified. The form has also been altered. Axite is made in the +form of a ribbon, the cross section being similar in shape to a double- +headed rail. It is claimed for this powder, that it does not corrode the +barrel in the way cordite does, that with equal pressure it gives greatly +increased velocity, and therefore flatter trajectory. That the effect of +temperature on the pressure and velocity with axite is only half that with +cordite. That the maximum flame temperature of axite is considerably less +than that of cordite, and the erosive effect is therefore considerably +less. That the deposit left in the barrel after firing axite cartridges +reduces the friction between the bullet and the barrel. It is therefore +practicable to use axite cartridges giving higher velocities than can be +employed with cordite, as with such velocities the latter would nickel the +barrel by excessive friction. It is also claimed that the accuracy is +greatly increased. The following results have been obtained with this +same time, and under the same conditions:-- + +~Axite~ Cartridges with 200-grain bullets. + Velocity 2,726 F.S. + Pressure 20.95 tons. + +~Axite~ Cartridges with 215-grain bullets. + Velocity 2,498 F.S. + Pressure 19.24 tons. + +~Axite~ Service Cartridges. + Velocity 2,179 F.S. + Pressure 15.76 tons. + +~Cordite~ Service Cartridges. + Velocity 2,010 F.S. + Pressure 15.67 tons. + +Five rounds from the Service axite and Service cordite were placed in an +oven and heated to a temperature of 110 deg. F. for one hour, and were then +fired for pressure. The following results were obtained:-- + + ~Axite.~ ~Cordite.~ + Before heating 15.76 tons per sq. in. 15.67 tons per sq. in. + After " 16.73 " " 17.21 " " + _____ _____ + + Increase .97 = 6.1% 1.54 = 9.8% + +Average Velocities-- + Before heating 2,150 F.S. 2,030 F.S. + After " 2,180 " 2,090 " + _____ _____ + + Increase 30 F.S. = 1-1/2% 60.0 F.S. = 3% + +In order to show the accuracy given by axite, seven rounds were fired from +a machine rest at a target fixed at 100 yards from a rifle. Six of the +seven shots could be covered by a penny piece, the other being just +outside. In order to ascertain the relative heat imparted to a rifle by +the explosion of axite and cordite, ten rounds each of axite and cordite +cartridges were fired from a .303 rifle, at intervals of ten seconds, the +temperature of the rifle barrel being taken before and after each series:-- + +THE RISE IN TEMPERATURE OF THE RIFLE BARREL + +With axite was 71 deg. F. +With cordite was 89 deg. F. +Difference in favour of axite 18 deg. F. = 20.2% + +The lubricating action of axite is shown by the fact that a series of +cordite cartridges fired from a .303 rifle in the ordinary way, followed +by a second series, the barrel being lubricated between each shot by +firing an axite cartridge alternately with the cordite cartridge. The mean +velocity of the first series of cordite cartridges was 1,974 ft. per +second; the mean velocity of the second series was 2,071 ft. per second; +the increased velocity due to the lubricating effect of axite therefore +was 97 ft. per second. This powder, it is evident, has very many very +excellent qualities, and considerable advantages over cordite. It is +understood that axite is at present under the consideration of the British +Government for use as the Service powder. + +~Ballistite.~--Nobel's powder, known as ballistite, originally consisted +of a camphorated blasting gelatine, and was made of 10 parts of camphor in +100 parts of nitro-glycerine, to which 200 parts of benzol were then +added, and 50 parts of nitro-cotton (soluble) were then steeped in this +mixture, which was then heated to evaporate off the benzol, and the +resulting compound afterwards passed between steam-heated rollers, and +formed into sheets, which were then finally cut up into small squares or +other shapes as convenient. The camphor contained in this substance was, +however, found to be a disadvantage, and its use discontinued. The +composition is now 50 per cent. of soluble nitro-cotton and 50 per cent. +of nitro-glycerine. As nitro-glycerine will not dissolve its own weight of +nitro-cotton (even the soluble variety), benzol is used as a solvent, but +is afterwards removed from the finished product, just as the acetone is +removed from cordite. About 1 per cent. of diphenylamine is added for the +purpose of increasing its stability. + +The colour of ballistite is a darkish brown. It burns in layers when +ignited, and emits sparks. The size of the cubes into which it is cut is a +0.2-inch cube. Its density is 1.6. It is also, by means of a special +machine, prepared in the form of sheets, after being mixed in a wooden +trough fitted with double zinc plates, and subjected to the heating +process by means of hot-water pipes. It is passed between hot rollers, and +rolled into sheets, which are afterwards put through a cutting machine and +granulated. Sir A. Nobel's experiments[A] with this powder gave the +following results:--The charge used was 5 lbs. 8 oz., the size of the +cubes being 0.2 inch. The mean crusher-gauge pressure was 14.3 tons per +square inch (maximum, 2,210; minimum, 2,142), and average pressure 2,180 +atmospheres. The muzzle velocity was 2,140 foot seconds, and the muzzle +energy 1,429 foot tons. A gramme of ballistite generates 615 c.c. of +permanent gases, and gives rise to 1,365 grm. units of heat. Ballistite is +manufactured at Ardeer in Scotland, at Chilworth in Surrey, and also in +Italy, under the name of Filite, which is in the form of cords instead of +cubes. The ballistite made in Germany contained more nitro-cellulose, and +the finished powder was coated with graphite. Its use has been +discontinued as the Service powder in Germany, but it is still the Service +powder in Italy. + +[Footnote A: _Proc. Roy. Soc._, vol. lii., p. 315.] + +~U.S. Naval Smokeless Powder.~--This powder is manufactured at the U.S. +Naval Torpedo Station for use in guns of all calibres in the U.S. Navy. It +is a nitro-cellulose powder, a mixture of insoluble and soluble nitro- +cellulose together with the nitrates of barium and potassium, and a small +percentage of calcium carbonate. The proportions in the case of the powder +for the 6-inch rapid-fire gun are as follows:--Mixed nitro-cellulose +(soluble and insoluble) 80 parts, barium nitrate 15 parts, potassium +nitrate 4 parts, and calcium carbonate 1 part. The percentage of nitrogen +contained in the insoluble nitro-cellulose must be 13.30+-0.15, and in the +soluble 11.60+-0.15, and the mean nitration strength of the mixture must be +12.75 per cent. of nitrogen. The solvent used in making the powder is a +mixture of ether (sp. gr. 0.720) 2 parts, and alcohol (95 per cent. by +volume) 1 part. The process of manufacture is briefly as follows:[A]--The +soluble and insoluble nitro-cellulose are dried separately at a +temperature from 38 deg. to 41 deg. C., until they do not contain more than 0.1 +per cent. of moisture. The calcium carbonate is also finely pulverised and +dried, and is added to the mixed nitro-celluloses after they have been +sifted through a 16-mesh sieve. The nitrates are next weighed out and +dissolved in hot water, and to this solution is added the mixture of +nitro-celluloses and calcium carbonate with constant stirring until the +entire mass becomes a homogeneous paste. This pasty mass is next spread +upon trays and re-dried at a temperature between 38 deg. and 48 deg. C., and when +thoroughly dry it is transferred to the kneading machine. The ether- +alcohol mixture is now added, and the process of kneading begun. It has +been found by experiment that the amount of solvent required to secure +thorough incorporation is about 500 c.c. to each 500 grms. of dried paste. +To prevent loss of solvent due to evaporation, the kneading machine is +made vapour light. The mixing or kneading is continued until the resulting +greyish-yellow paste is absolutely homogeneous so far as can be detected +by the eye, which requires from three to four hours. The paste is next +treated in a preliminary press (known as the block press and is actuated +by hydraulic power), where it is pressed into a cylindrical mass of +uniform density and of such dimensions as to fit it for the final or +powder press. The cylindrical masses from the block press are transferred +to the final press, whence they are forced out of a die under a pressure +of about 500 lbs. per square inch. As it emerges from the final press the +powder is in the form of a ribbon or sheet, the width and thickness of +which is determined by the dimensions of the powder chamber of the gun in +which the powder is to be used. On the inner surface of the die are ribs +extending in the direction of the powder as it emerges from the press, the +object of these ribs being to score the sheets or ribbons in the direction +of their length, so that the powder will yield uniformly to the pressure +of the gases generated in the gun during the combustion of the charge. The +ribbon or sheet is next cut into pieces of a width and length +corresponding to the chamber of the gun for which it is intended, the +general rule being that the thickness of the grain (when perfectly dry) +shall be fifteen one-thousandths (.015) of the calibre of the gun, and the +length equal to the length to fit the powder chamber. Thus, in case of the +6-inch rapid-fire gun the thickness of the grain (or sheet) is 0.09 of an +inch and the length 32 inches. The sheets are next thoroughly dried, first +between sheets of porous blotting-paper under moderate pressure and at a +temperature between 15 deg. C. and 21.5 deg. C. for three days, and then exposed +to free circulation of the air at about 21.5 deg. C. for seven days, and +finally subjected for a week or longer to a temperature not exceeding 38 deg. +C. until they cease to lose weight. + +[Footnote A: Lieut. W. Walke, "Lectures on Explosives," p. 330.] + +The sheets, when thoroughly dried, are of a uniform yellowish-grey colour, +and of the characteristic colloidal consistency; they possess a perfectly +smooth surface, and are free from internal blisters or cracks. The +temperature of ignition of the finished powder should not be below 172 deg. +C., and when subjected to the heat or stability test, it is required to +resist exposure to a temperature of 71 deg. C. for thirty minutes without +causing discoloration of the test paper. + +~W.A. Powder.~--This powder is made by the American Smokeless Powder +Company, and it was proposed for use in the United States Army and Navy. +It is made in several grades according to the ballistic conditions +required. It consists of insoluble gun-cotton and nitro-glycerine, +together with metallic nitrates and an organic substance used as a +deterrent or regulator. The details of its manufacture are very similar to +those of cordite, with the exception that the nitro-glycerine is dissolved +in a portion of the acetone, before it is added to the gun-cotton. The +powder is pressed into solid threads, or tubular cords or cylinders, +according to the calibre of the gun in which the powder is to be used. As +the threads emerge from the press they are received upon a canvas belt, +which passes over steam-heated pipes, and deposited in wire baskets. The +larger cords or cylinders are cut into the proper lengths and exposed upon +trays in the drying-house. The powder for small arms is granulated by +cutting the threads into short cylinders, which are subsequently tumbled, +dusted, and, if not perfectly dry, again placed upon trays in the drying- +house. Before being sent away from the factory, from five to ten lots of +500 lbs. each are mixed in a blending machine, in order to obtain greater +uniformity. The colour of the W.A. powder is very light grey, the grains +are very uniform in size, dry and hard. The powder for larger guns is of a +yellowish colour, almost translucent, and almost as hard as vulcanite. The +powder is said to be unaffected by atmospheric or climatic conditions, to +be stable, and to have given excellent ballistic results; it is not +sensitive to the impact of bullets, and when ignited burns quietly, unless +strongly confined. + +Turning now to the smokeless powders, in which the chief ingredient is +nitro-cellulose in some form (either gun-cotton or nitro-lignine, &c.), +one of the first of these was Prentice's gun-cotton, which consisted of +nitrated paper 15 parts, mixed with 85 parts of unconverted cellulose. It +was rolled into a cylinder. Another was Punshon's gun-cotton powder, which +consisted of gun-cotton soaked in a solution of sugar, and then mixed with +a nitrate, such as sodium or potassium nitrate. Barium nitrate was +afterwards used, and the material was granulated, and consisted of +nitrated gun-cotton. + +The explosive known as tonite, made at Faversham, was at first intended +for use as a gunpowder, but is now only used for blasting. + +~The Schultze Powder.~--One of the earliest of the successful powders +introduced into this country was Schultze's powder, the invention of +Colonel Schultze, of the Prussian Artillery, and is now manufactured by +the Schultze Gunpowder Company Limited, of London. The composition of this +powder, as given in the "Dictionary of Explosives" by the late Colonel +Cundall, is as follows:-- + +Soluble nitro-lignine 14.83 per cent. +Insoluble " 23.36 " +Lignine (unconverted) 13.14 " +Nitrates of K and Ba 32.35 " +Paraffin 3.65 " +Matters soluble in alcohol 0.11 " +Moisture 2.56 " + +This powder was the first to solve the difficulty of making a smokeless, +or nearly smokeless powder which could be used with safety and success in +small arms. Previously, gun-cotton had been tried in various forms, and in +nearly every instance disaster to the weapon had followed, owing to the +difficulty of taming the combustion to a safe degree. But about 1866 +Colonel Schultze produced, as the result of experiments, a nitrated wood +fibre which gave great promise of being more pliable and more easily +regulated in its burning than gun-cotton, and this was at once introduced +into England, and the Schultze Gunpowder Company Limited was formed to +commence its manufacture, which it did in the year 1868. During the years +from its first appearance, Schultze gunpowder has passed through various +modifications. It was first made in a small cubical grain formed by +cutting the actual fibre of timber transversely, and then breaking this +veneer into cubes. Later on improvements were introduced, and the wood +fibre so produced was crushed to a fine degree, and then reformed into +small irregular grains. Again, an advance was made in the form of the wood +fibre used, the fibre being broken down by the action of chemicals under +high temperature, and so producing an extremely pure form of woody fibre. +The next improvement was to render the grains of the powder practically +waterproof and less affected by the atmospheric influences of moisture and +dryness, and the last improvement to the process was that of hardening the +grains by means of a solvent of nitro-lignine, so as to do away with the +dust that was often formed from the rubbing of the grains during transit. + +Minor modifications have from time to time also been made, in order to +meet the gradual alteration which has taken place during this long period +in the manufacture of sporting guns and cartridge cases to be used with +this powder, but through all its evolution this Company has adhered to the +first idea of using woody fibre in preference to cotton as the basis of +their smokeless powder, as experience has confirmed the original opinion +that a powder can be thus made less sensitive to occasional differences in +loading, and more satisfactory all round than when made from the cotton +base. The powder has always been regulated so that bulk for bulk it +occupies the same measure as the best black powder, and as regards its +weight, just one half of that of black. + +The process of manufacture of this powder is briefly as follows:-- + +Wood of clean growth is treated by the well-known sulphite process for +producing pure woody fibre, which is very carefully purified, and this, +after drying, is steeped in a mixture of nitric and sulphuric acids, to +render it a nitro-compound and the explosive base of the powder. This +nitro compound is carefully purified until it stands the very high purity +requirements of the Home Office, and is then ground with oxygen-bearing +salts, &c., and the whole is formed into little irregular-shaped grains of +the desired size, which grains are dried and hardened by steeping in a +suitable solvent for the nitro compound, and after finally drying, +sifting, &c., the powder is stored in magazines for several months before +it is issued. When issued, a very large blend is made of many tons weight, +which ensures absolute uniformity in the material. + +There is in England a standard load adopted by every one for testing a +sporting powder; this charge is 42 grains of powder and 1-1/8 oz. No. 6 +shot--this shot fired from a 12-bore gun, patterns being taken at 40 +yards, the velocity at any required distance. + +The standard muzzle velocity of Schultze gunpowder is 1,220 feet per +second. + +The mean 40 yards ditto is 875 feet per second. + +The mean 20 yards ditto is 1,050 feet per second. + +The internal pressure not to exceed 3.5 tons. + +This Company also manufactures a new form of powder, known as Imperial +Schultze. It is a powder somewhat lighter in gravity; 33 grains occupies +the bulk charge, as compared with the 42 grains of the old. It follows in +its composition much the lines of the older powder, but it is quite free +from smoke, and leaves no residue whatever. + +~The E.G. Powder.~--This is one of the oldest of the nitro powders. It was +invented by Reid and Johnson in 1882. It is now manufactured by the E.G. +Powder Company Limited, at their factory near Dartford, Kent, and in +America by the Anglo-American E.G. Powder Company, at New Jersey. The +basis of this powder is a fine form of cellulose, derived from cotton, +carefully purified, and freed from all foreign substances, and carefully +nitrated. Its manufacture is somewhat as follows:--Pure nitro-cotton, in +the form of a fine powder, is rotated in a drum, sprinkled with water, and +the drum rotated until the nitro-cotton has taken the form of grains. The +grains are then dried and moistened with ether-alcohol, whereby the +moisture is gelatinised, and afterwards coloured with aurine, which gives +them an orange colour. They are then dried and put through a sieve, in +order to separate the grains which may have stuck together during the +gelatinising process. + +Since its introduction soon after 1881, E.G. powder has undergone +considerable modifications, and is now a distinctly different product from +a practical point of view. It is now and has been since 1897 what is known +as a 33-grain powder, that is to say, the old standard charge of 3 drams +by measure for a 12-bore gun weighs 33 grains, as compared with 42 grains +for the original E.G. and other nitro powders. This improvement was +effected by a reduction of the barium nitrate and the use of nitro- +cellulose of a higher degree of nitration, and also more gelatinisation in +manufacture. The granules are very hard, and resist moisture to an extent +hitherto unattainable by any "bulk" powder. + +Irregularities of pressure in loading have also a minimum effect by reason +of the hardness of the grains. The colouring matter used is aurine, and +the small quantity of nitrate used is the barium salt. The powder is +standardised for pressure velocity with Boulenge chronograph,[A] pattern +and gravimetric density by elaborate daily tests, and is continually +subjected to severe trials for stability under various conditions of +storage, the result being that it may be kept for what in practice amount +to indefinite periods of time, either in cartridges or in bulk without any +alteration being feared. The E.C. powders are used in sporting guns. No. 1 +and No. 2 E.C. are not at present manufactured, E.C. No. 3 having taken +their place entirely. Since 1890 these powders have been manufactured +under the Borland-Johnson patents, these improved powders being for some +time known as the J.B. powders. The E.C. No. 1 was superseded by the E.C. +No. 2, made under the Borland-Johnson patents, and this in its turn by the +E.C. No. 3 (in 1897). + +[Footnote A: Invented in 1869 by Major Le Boulenge, Belgian Artillery. It +is intended to record the mean velocity between any two points, and from +its simplicity and accuracy is largely employed. Other forms have been +invented by Capt. Breger, French Artillerie de la Marine, and Capt. +Holden, R.A.] + +~Indurite~ is the invention of Professor C.E. Munroe, of the U.S. Naval +Torpedo Station. It is made from insoluble nitro-cotton, treated in a +particular manner by steam, and mixed with nitro-benzene. The _Dupont_ +powder is very similar to _Indurite_. M.E. Leonard, of the United States, +invented a powder consisting of 75 parts of nitro-glycerine, 25 parts of +gun-cotton, 5 parts of lycopodium powder, and 4 parts of urea crystals +dissolved in acetone. The French smokeless powder, Vielle poudre (poudre +B), used in the Lebel rifle, is a mixture of nitro-cellulose and tannin, +mixed with barium and potassium nitrates. It gives a very feeble report, +and very little bluish smoke. The Nobel Company is said to be perfecting a +smokeless powder in which the chief ingredients are nitro-amido- and tri- +nitro-benzene. C.O. Lundholm has patented (U.S. Pat, 701,591, 1901) a +smokeless powder containing nitro-glycerine 30, nitro-cellulose 60, diamyl +phthalate 10 (or diamyl phthalate 5, and mineral jelly 5). The diamyl +phthalate is added, with or without the mineral jelly to nitro-glycerine +and nitro-cellulose. + +~Walsrode Powder.~--The smokeless powder known as Walsrode powder consists +of absolutely pure gelatinised nitro-cellulose, grained by a chemical not +a mechanical process, consequently the grains do not need facing with +gelatine to prevent their breaking up, as is the case with many nitro +powders. For this same reason, as well as from the method of getting rid +of the solvent used, the Walsrode has no tendency whatever to absorb +moisture. In fact, it can lie in water for several days, and when taken +out and dried again at a moderate temperature will be found as good as +before. Nor is it influenced by heat, whether dry or damp, and it can be +stored for years without being in the least affected. It is claimed also +that it heats the barrels of guns much less than black powder, and does +not injure them. + +The standard charge is 30 grains, and it is claimed that with this charge +Walsrode powder will prove second to none. A large cap is necessary, as +the grains of this powder are very hard, and require a large flame to +properly ignite them. In loading cartridges for sporting purposes, an +extra felt wad is required to compensate for the small space occupied by +the charge; but for military use the powder can be left quite loose. The +gas pressure of this powder is low (in several military rifles only one- +half that of other nitros), and the recoil consequently small; and it is +claimed that with the slight increase of the charge (from 29 to 30 grs.) +both penetration and initial velocity will be largely increased, whilst +the gas pressure and recoil will not be greater. + +This powder was used at Bisley, at the National Rifle Association's +Meeting, with satisfactory results. It is made by the Walsrode Smokeless +and Waterproof Gunpowder Company. The nitro-cotton is gelatinised by means +of acetic ether, and the skin produced retards burning. The nitro-cotton +is mixed with acetic ether, and when the gelatinisation has taken place, +the plastic mass is forced through holes in a metal plate into strips, +which are then cut up into pieces the size of grains. The M.H. Walsrode +powder is a leaflet powder, light in colour, about 40 grains of which give +a muzzle velocity of 1,350 feet and a pressure of 3 tons. It is, like the +other Walsrode powders, waterproof and heat-proof. + +~Cooppal Powder~ is manufactured by Messrs Cooppal & Co. at their +extensive powder works in Belgium. It consists of nitro-jute or nitro- +cotton, with or without nitrates, treated with a solvent to form a +gelatinised mass. There are a great many varieties of this powder. One +kind is in the form of little squares; another, for use in Hotchkiss guns, +is formed into 3-millimetre cubes, and is black. Other varieties are +coloured with aniline dyes of different colours. + +~Amberite~ is a nitro-cellulose powder of the 42-grain type of sporting +gunpowders, and is manufactured by Messrs Curtis's & Harvey Limited, at +their Smokeless Powder Factory, Tonbridge, Kent. It consists of a mixture +of nitro-cellulose, paraffin, barium, nitrate, and some other ingredients. +It is claimed for this powder that it combines hard shooting with safety, +great penetration, and moderate strain on the gun. It is hard and tough in +grain, and may be loaded like black powder, and subjected to hard friction +without breaking into powder, that it is smokeless, and leaves no residue +in the gun. The charge for 12 bores is 42 grains by weight, and 1-1/8 oz. +or 1-1/16 oz. shot. The powders known as cannonite[A] and ruby powder, +also manufactured by Messrs Curtis's & Harvey Limited, are analogous +products having the same general characteristics. + +[Footnote A: For further details of cannonite, see First Edition, p. 181.] + +~Smokeless Diamond~, also manufactured by the above mentioned firm, is a +nitro-cellulose powder of the 33-grain type of sporting gunpowders. It was +invented by Mr H.M. Chapman. The manufacture of Smokeless Diamond, as +carried out at Tonbridge, is shortly as follows:--The gun-cotton, which is +the chief ingredient of this powder, is first stoved, then mixed with +certain compounds which act as moderators, and after the solvents are +added, is worked up into a homogeneous plastic condition. It then +undergoes the processes of granulation, sifting, dusting, drying, and +glazing. In order to ensure uniformity several batches are blended +together, and stored for some time before being issued for use. + +It is claimed for this powder that it is quick of ignition, the quickness +being probably due to the peculiar structure of the grains which, when +looked at under the microscope, have the appearance of coke. The charge +for a 12 bore is 33 grains and 1-1/16 oz. shot, which gives a velocity of +1,050 feet per second, and a pressure of 3 tons per square inch. + +~Greiner's Powder~ consists of nitro-cellulose, nitro-benzol, graphite, +and lampblack. + +~B.N. Powder.~--This powder is of a light grey or drab colour, perfectly +opaque, and rough to the touch. It consists of a mixture, nitro-cellulose +and the nitrates of barium and potassium. Its composition is as follows:-- + +Insoluble nitro-cellulose 29.13 parts +Soluble nitro-cellulose 41.31 " +Barium nitrate 19.00 " +Potassium nitrate 7.97 " +Sodium carbonate 2.03 " +Volatile matter 1.43 " + +This powder is a modification of the Poudre B., or Vieille's powder +invented for use in the Lebel rifle, and which consisted of a mixture of +the nitro-celluloses with paraffin. + +~Von Foster's Powder~ contains nothing but pure gelatinised nitro- +cellulose, together with a small quantity of carbonate of lime. + +The German ~Troisdorf Powder~ is a mixture of gelatinised nitro-cellulose, +with or without nitrates. + +~Maximite~ is the invention of Mr Hudson Maxim, and is a nitro-compound, +the base being gun-cotton. The exact composition and method of manufacture +are, however, kept secret. It is made by the Columbia Powder Manufacturing +Company, of New York, and in two forms--one for use as a smokeless rifle +powder, and the other for blasting purposes. + +~Wetteren Powder.~--This powder was manufactured at the Royal Gunpowder +Factory at Wetteren, and used in the Belgian service. Originally it was a +mixture of nitro-glycerine and nitro-cellulose, with amyl acetate as +solvent. Its composition has, however, been altered from time to time. One +variety consists chiefly of nitro-cellulose, with amyl acetate as solvent. +It is of a dark brown colour, and of the consistency of indiarubber. It is +rolled into sheets and finally granulated. + +~Henrite~ is a nitro-cellulose powder. + +~Normal Powder.~--The Swedish powder known as "Normal" Smokeless Powder, +and manufactured by the Swedish Powder Manufacturing Company, of +Landskrona, Sweden, and used for some years past in the Swiss Army, is +made in four forms. For field guns of 8.4 calibre, it is used in the form +of cylindrical grains of a yellow colour, of a diameter of .8 to .9 mm. +and density of .790--about 840 grains of it go to one gun. For rifles, it +is used in the form of grey squares, density .750, and 1 grm. equals about +1,014 grains. One hundred rounds of this powder, fired in eighteen +minutes, raised the temperature of the gun barrel 284 deg. F. A nitro- +glycerine powder, fired under the same conditions, gave a temperature of +464 deg. F. + +This powder is said to keep well--a sample kept 3-1/2 years gave as good +results as when first made--is easy to make, very stable, ignites easily, +not very sensitive to shock or friction, is very light, &c. Eight hundred +rounds fired from a heavy gun produced no injury to the interior of the +weapon. Samples kept for eleven months in the moist atmosphere of a +cellar, when fired gave a muzzle velocity of 1,450 ft. secs. and pressure +of 1,312 atmospheres, and the moisture was found to have risen from 1.2 to +1.6 per cent. After twenty-three months in the damp it contained 2 per +cent. moisture, gave a muzzle velocity of 1,478 ft. sees., and pressure of +1,356 atmospheres. In a 7.5 millimetre rifle, 13.8 grm. bullet, and charge +of 2 grms., it gives a muzzle velocity of 2,035 ft. secs. and a pressure +of 2,200 atmospheres. In the 8.4 cm. field-gun, with charge of 600 grms., +and projectile of 6.7 kilogrammes, muzzle velocity was equal to 1,640 ft. +secs. and pressure 1,750. A sample of the powder for use in the .303 M. +rifle, lately analysed by the author, gave the following result:-- + +Gun-cotton 96.21 per cent. +Soluble cotton 1.80 " +Non-nitrated cotton trace. +Resin and other matters 1.99 " + _______ + + 100.00 + +The various forms of powder invented and manufactured by Mr C.F. Hengst +are chiefly composed of nitrated straw that has been finely pulped. The +straw is treated first with acids and afterwards with alkalies, and the +result is a firm fibrous substance which is granulated. It is claimed that +this powder is entirely smokeless and flameless, that it does not foul the +gun nor heat the barrel, and is at the same time 150 per cent. stronger +than black powder. + +The German "Troisdorf" powder consists of nitro-cellulose that has been +gelatinised together with a nitrate. Kolf's powder is also gelatinised +with nitro-cellulose. The powders invented by Mr E.J. Ryves contain nitro- +glycerine, nitro-cotton, castor-oil, paper-pulp, and carbonate of +magnesia. Maxim powder contains both soluble and insoluble nitro- +cellulose, nitro-glycerine, and carbonate of soda. The smokeless powder +made by the "Dynamite Actiengesellschaft Nobel" consists of nitro-starch +70 to 99 parts, and of di- or tri-nitro-benzene 1 to 30 parts. + +An American wood powder, known as Bracket's Sporting Powder, consists of +soluble and insoluble nitro-lignine, mixed with charred lignine, humus, +and nitrate of soda. Mr F.H. Snyder, of New York, is the inventor of a +shell powder known as the "Snyder Explosive," consisting of 94 per cent. +nitro-glycerine, 6 per cent. of soluble nitro-cotton, and camphor, which +is said to be safe in use. Experiments were made with it in a 6-inch +rifled gun, fired at a target 220 yards away, composed of twelve 1-inch +steel plates welded together, and backed with 12-inch and 14-inch oak +beams, and weighing 20 tons. The shots entirely destroyed it. The charge +of explosive used was 10 lbs. in each shell. + +~Comparative Tests of Black and Nitro Powders, from "American Field."~-- +The results given in table below were obtained at the German Shooting +Association's grounds at Coepenick, Berlin. Penetration was calculated by +placing frames, each holding five cards of 1 millimetre in thickness +(equals .03937 inch), and 3 inches apart, in a bee-line, at distances of +20 inches. Velocity, pattern, and penetration were taken at 40 yards from +the muzzle of a 12-gauge choke-bore double-barrel gun. Gas pressure was +taken by a special apparatus. All shells were loaded with 1-1/8 oz. of No. +3 shot, equal to 120 pellets, and the number given below represents the +average number in the 30-inch pattern. The number of sheets passed through +gives the average penetration. One atmosphere equals pressure equal to 1 +kilogramme (2.2 lbs.) on the square centimetre, hence 1,000 atmospheres +equal 2,200 lbs. on the square centimetre. The E.C., Schultze, and +Walsrode powders were loaded in Elcy's special shells, 2-1/2 inches long. +The averages were taken from a large number of shots, and the same series +of shots fired under precisely the same conditions. + + _______________________________________________________________________ +| | | | | | +| | Gas | | | | +| | Pressure. | Velocity. | Pattern. | Penetration. | +|__________________|____________|___________|____________|______________| +| | | | | | +| |Atmospheres.| Metres. | | Sheets. | +| | | | | | +|Fine-grained black| | | | | +|powder, standard | | | | | +|charge | 514.2 | 280 | 78.6 = 66% | 19.O | +| | | | | | +|Coarse-grained | | | | | +|black powder, | | | | | +|standard charge | 473.4 | 281.4 | 78.2 = 65% | 19.4 | +| | | | | | +|Schultze powder, | | | | | +|42 grains | 921.0 | 290.0 | 64.2 = 54% | 20.2 | +| | | | | | +|Schultze powder, | | | | | +|45 grains | 1052.8 | 305.8 | 52.2 = 42% | 20.6 | +| | | | | | +|E.G. smokeless, | | | | | +|42 grains | 920.2 | 298.4 | 81.4 = 67% | 18.8 | +| | | | | | +|Walsrode, | | | | | +|29 grains | 586.4 | 280.6 | 83.0 = 69% | 19.0 | +|__________________|____________|___________|____________|______________| + +Barometer, 760 mm. Thermometer, 30 deg. C. Hydrometer = 65. Wind, S.W. + +~Picric Powders.~--The chief of these is _Melinite_, the composition of +which is not known with certainty. It is believed to be melted picric acid +together with gun-cotton dissolved in acetone or ether-alcohol. Walke +gives the following proportions--30 parts of tri-nitro-cellulose dissolved +in 45 parts of ether-alcohol (2 to 1), and 70 parts of fused and +pulverised picric acid. The ether-alcohol mixture is allowed to evaporate +spontaneously, and the resulting cake granulated. The French claim, +however, that the original invention has been so modified and perfected +that the melinite of to-day cannot be recognised in the earlier product. +Melinite has a yellow colour, is almost without crystalline appearance, +and when ignited by a flame or heated wire, it burns with a reddish-yellow +flame, giving off copious volumes of black smoke. Melinite as at present +used is said to be a perfectly safe explosive, both as regards +manufacture, handling, and storage. + +_Lyddite_,[A] the picric acid explosive used in the British service, is +supposed to be identical with the original melinite, but its composition +has not been made public. + +[Footnote A: Schimose, the Japanese powder, is stated to be identical with +Lyddite and Melinite (_Chem. Centr._, 1906, 1, 1196).] + +Picrates are more often used than picric acid itself in powders. One of +the best known is _Brugere's Powder_, which is a mixture of 54 parts of +picrate of ammonia and 45 parts of saltpetre. It is stable and safe to +manufacture. It has been used in the Chassepot rifle with good results, +gives little smoke, and a small residue only of carbonate of potash. + +The next in importance is _Designolle's Powder_, made at Bouchon, +consisting of picrate of potash, saltpetre, and charcoal. It was made in +three varieties, viz., for rifles, big guns, and torpedoes and shells. +These powders are made much in the same way as gunpowder. The advantages +claimed for them over gunpowder are, greater strength, comparative absence +of smoke, and freedom from injurious action on the bores of guns. + +_Emmensite_ is the invention of Dr Stephen Emmens, of the United States. +The Emmens "crystals" are produced by treating picric acid with fuming +nitric acid of specific gravity of 1.52. The acid dissolves with the +evolution of red fumes. The liquid, when cooled, deposits crystals, stated +to be different to picric acid, and lustrous flakes. These flakes, when +heated in water, separate into two new bodies. One of these enters into +solution and forms crystals unlike the first, while the other body remains +undissolved. The acid crystals are used mixed with a nitrate. + +Emmensite has been subjected to experiment by the direction of the U.S. +Secretary for War, and found satisfactory. A sample of Emmensite, in the +form of a coarse powder, was first tried in a pistol, and proved superior +in propelling power to ordinary gunpowder. When tested against explosive +gelatine, it did very good work in shattering iron plates. It is claimed +for this explosive that it enjoys the distinction of being the only high +explosive which may be used both for firearms and blasting. This view is +supported by the trials made by the American War Office authorities, and +shows Emmensite to be a useful explosive both for blasting and as a +smokeless powder. Its explosive power, as tested, is 283 tons per square +inch, and its specific gravity is 1.8. + +Abel proposed to use picric acid for filling shells. His _Picric Powder_ +consisted of 3 parts of saltpetre, and 2 of picrate of ammonia. +_Victorite_ consists of chlorate of potash, picric acid, and olive oil, +and with occasionally some charcoal. It has the form of a coarse yellowish +grey powder, and leaves an oily stain on paper, and it is very sensitive +to friction and percussion. The composition is as follows:--KClO_{3} = 80 +parts; picric acid, 110 parts; saltpetre, 10 parts; charcoal, 5 parts. It +is not manufactured in England. _Tschiner's Powder_ is very similar to +Victorite in composition, but contains resin. A list of the chief picric +powders will be found in the late Colonel J.P. Cundill, R.A.'s "Dictionary +of Explosives." + + + + +CHAPTER VII. + +_ANALYSIS OF EXPLOSIVES._ + +Kieselguhr Dynamite--Gelatine Compounds--Tonite--Cordite--Vaseline-- +Acetone--Scheme for Analysis of Explosives--Nitro-Cotton--Solubility Test-- +Non-Nitrated Cotton--Alkalinity--Ash and Inorganic Matter--Determination +of Nitrogen--Lunge, Champion and Pellet's, Schultze-Tieman, and Kjeldahl's +Methods--Celluloid--Picric Acid and Picrates--Resinous and Tarry Matters-- +Sulphuric Acid and Hydrochloric Acid and Oxalic Acid--Nitric Acid-- +Inorganic Impurities--General Impurities and Adulterations--Potassium +Picrate, &c.--Picrates of the Alkaloids--Analysis of Glycerine--Residue-- +Silver Test--Nitration--Total Acid Equivalent--Neutrality--Free Fatty +Acids--Combined Fatty Acids--Impurities--Oleic Acid--Sodium Chloride-- +Determination of Glycerine--Waste Acids--Sodium Nitrate--Mercury +Fulminate--Cap Composition--Table for Correction of Volumes of Gases, for +Temperature and Pressure + + +~Kieselguhr Dynamite.~--The material generally consists of 75 per cent. of +nitro-glycerine and 25 per cent. of the infusorial earth kieselguhr. The +analysis is very simple, and may be conducted as follows:--Weigh out about +10 grms. of the substance, and place over calcium chloride in a desiccator +for some six to eight days, and then re-weigh. The loss of weight gives +the moisture. This will generally be very small, probably never more than +1 per cent., and usually less. + +Mr James O. Handy, in order to save time, proposes to dry dynamite in the +following manner. He places 1 grm. of the material in a porcelain crucible +1 inch in diameter. The crucible is then supported at the bottom of an +extra wide-mouthed bottle of about 600 c.c. capacity. Air, which has been +dried by bubbling through strong sulphuric acid, is now drawn over the +surface of the sample for three hours by means of an ordinary aspirator. +The air should pass approximately at the rate of 10 c.c. per second. The +tube by which the dry air enters the bottle extends to within 1 inch of +the crucible containing the dynamite. An empty safety bottle is connected +with the inlet, and another with the outlet of the wide-mouthed bottle. +The first guards against the mechanical carrying over by the air current +of sulphuric acid from the acid bottle into the sample, whilst the second +prevents spasmodic outbursts of water from the exhaust from reaching the +sample. The method also gave satisfactory results with nitro-glycerine. +The dry substance may now be wrapped in filter paper, the whole weighed, +and the nitro-glycerine extracted in the Soxhlet apparatus with ether. The +ether should be distilled over at least twenty-four times. + +I have found, however, that much quicker, and quite as accurate, results +may be obtained by leaving the dynamite in contact with ether in a small +Erlenmeyer flask for twenty-four hours--leaving it overnight is better-- +and decanting, and again allowing the substance to remain in contact with +a little fresh ether for an hour, and finally filtering through a weighed +filter, drying at 100 deg. C., and weighing. This gives the weight of the +kieselguhr. The nitro-glycerine must be obtained by difference, as it is +quite useless to evaporate down the ethereal solution to obtain it, as it +is itself volatile to a very considerable extent at the temperature of +evaporation of the ether, and the result, therefore, will always be much +too low. The dry guhr can, of course, be examined, either qualitatively or +quantitatively, for other mineral salts, such as carbonate of soda, &c. An +actual analysis of dynamite No. 1 made by the author at Hayle gave-- +Moisture, 0.92 per cent.; kieselguhr, 26.15 per cent.; and nitro- +glycerine, 72.93 per cent., the last being obtained by difference. + +~Nitro-Glycerine.~--It is sometimes desired to test an explosive substance +for nitro-glycerine. If an oily liquid is oozing from the substance, soak +a drop of it in filter paper. If it is nitro-glycerine it will make a +greasy spot. If the paper is now placed upon an iron anvil, and struck +with an iron hammer, it will explode with a sharp report, if lighted it +burns with a yellowish to greenish flame, emitting a crackling sound, and +placed upon an iron plate and heated from beneath, it explodes sharply. + +If a few drops of nitro-glycerine are placed in a test tube, and shaken up +with methyl-alcohol (previously tested with distilled water, to see that +it produces no turbidity), and filtered, on the addition of distilled +water, the solution will become milky, and the nitro-glycerine will +separate out, and finally collect at the bottom of the tube. + +If to a solution of a trace of nitro-glycerine in methyl-alcohol, a few +drops of a solution, composed of 1 volume of aniline, and 40 volumes +sulphuric acid (1.84) be added, a deep purple colour will be produced. +This colour changes to green upon the addition of water. If it is +necessary to determine the nitro-glycerine quantitatively in an explosive, +the scheme on page 213 may be followed. Ether is the best solvent to use. +Nitrogen should be determined in the nitrometer. + +~Gelatine Compounds.~--The simplest of these compounds is, of course, +blasting gelatine, as it consists of nothing but nitro-cotton and nitro- +glycerine, the nitro-cellulose being dissolved in the glycerine to form a +clear jelly, the usual proportions being about 92 per cent. of nitro- +glycerine to 8 per cent. nitro-cotton, but the cotton is found as high as +10 per cent. in some gelatines. Gelatine dynamite and gelignite are +blasting gelatines, with varying proportions of wood-pulp and saltpetre +(KNO_{3}) mixed with a thin blasting gelatine. The method of analysis is +as follows:--Weigh out 10 grms. of the substance, previously cut up into +small pieces with a platinum spatula, and place over calcium chloride in a +desiccator for some days. Reweigh. The loss equals moisture. This is +generally very small. Or Handy's method may be used. The dried sample is +then transferred to a small thistle-headed funnel which has been cut off +from its stem, and the opening plugged with a little glass wool, and round +the top rim of which a piece of fine platinum wire has been fastened, in +order that it may afterwards be easily removed from the Soxhlet tube. The +weight of this funnel and the glass wool must be accurately known. It is +then transferred to the Soxhlet tube and exhausted with ether, which +dissolves out the nitro-glycerine. The weighed residue must afterwards be +treated in a flask with ether-alcohol to dissolve out the nitro-cotton. + +But the more expeditious method, and one quite as accurate, is to transfer +the dried gelatine to a conical Erlenmeyer flask of about 500 c.c. +capacity, and add 250 c.c. of a mixture of ether-alcohol (2 ether to 1 +alcohol), and allow to stand overnight. Sometimes a further addition of +ether-alcohol is necessary. It is always better to add another 300 c.c., +and leave for twenty minutes or so after the solution has been filtered +off. The undissolved portion, which consists of wood-pulp, potassium +nitrate, and other salts, is filtered off through a linen or paper filter, +dried and weighed. + +~Solution.~--The ether-alcohol solution contains the nitro-cotton and the +nitro-glycerine in solution.[A] To this solution add excess of chloroform +(about 100 c.c. will be required), when the nitro-cellulose will be +precipitated in a gelatinous form. This should be filtered off through a +linen filter, and allowed to drain. It is useless to attempt to use a +filter pump, as it generally causes it to set solid. The precipitated +cotton should then be redissolved in ether-alcohol, and again precipitated +with chloroform (20 c.c. of ether-alcohol should be used). This precaution +is absolutely necessary, if the substance has been treated with ether- +alcohol at first instead of ether only, otherwise the results will be much +too high, owing to the gelatinous precipitate retaining very considerable +quantities of nitro-glycerine. The precipitate is then allowed to drain as +completely as possible, and finally allowed to dry in the air bath at 40 deg. +C., until it is easily detached from the linen filter by the aid of a +spatula, and is then transferred to a weighed watch-glass, replaced in the +oven, and dried at 40 deg. C. until constant in weight. The weight found, +calculated upon the 10 grms. taken, gives the percentage of nitro- +cellulose. + +[Footnote A: If the substance has been treated with ether alone in the +Soxhlet, the nitro-glycerine will of course be dissolved out first, and +the ether-alcohol solution will only contain the nitro-cellulose.] + +~The Residue~ left after treating the gelatine with ether-alcohol is, in +the case of blasting gelatine, very small, and will probably consist of +nothing but carbonate of soda. It should be dried at 100 deg. C. and weighed, +but in the case of either gelignite or gelatine dynamite this residue +should be transferred to a beaker and boiled with distilled water, and the +water decanted some eight or ten times, and the residue finally +transferred to a tarred filter and washed for some time with hot water. +The residue left upon the filter is wood-pulp. This is dried at 100 deg. C. +until constant, and weighed. The solution and washings from the wood are +evaporated down in a platinum dish, and dried at 100 deg. C. It will consist +of the potassium nitrate, and any other mineral salts, such as carbonate +of soda, which should always be tested for by adding a few drops of nitric +acid and a little water to the residue, and again evaporating to dryness +and re-weighing. From the difference in weight the soda can be calculated, +sodium nitrate having been formed. Thus-- + +Na_{2}CO_{3} + 2HNO_{3} = 2NaNO_{3} + CO_{2} + H_{2}O. + +Mol. wt. = 106 = 170 + +(170 - 106 = 64) and _x_ = (106 x _d_)/64 + +where _x_ equals grms. of sodium carbonate in residue, and _d_ equals the +difference in weight of residue, before and after treatment with nitric +acid. + +The nitro-glycerine is best found by difference, but if desired the +solutions from the precipitation of the nitro-cellulose may be evaporated +down upon the water bath at 30 deg. to 40 deg. C., and finally dried over CaCl_{2} +until no smell of ether or chloroform can be detected, and the nitro- +glycerine weighed. It will, however, always be much too low. An actual +analysis of a sample of gelatine dynamite gave the following result:-- + +Nitrocellulose (collodion) 3.819 per cent. +Nitro-glycerine 66.691 " +Wood-pulp 16.290 " +KNO_{3} 12.890 " +Na_{2}CO_{3} _Nil._ +Water 0.340 " + +This sample was probably intended to contain 30 per cent. of absorbing +material to 70 per cent. of explosive substances. Many dynamites contain +other substances than the above, such as paraffin, resin, sulphur, wood, +coal-dust, charcoal, also mineral salts, such as carbonate of magnesia, +chlorate of potash, &c. In these cases the above-described methods must of +course be considerably modified. Paraffin, resin, and most of the sulphur +will be found in the ether solution if present. The solution should be +evaporated (and in this case the explosive should in the first case be +treated with ether only, and not ether-alcohol), and the residue weighed, +and then treated on the water bath with a solution of caustic soda. The +resin goes into solution, and is separated by decantation from the +residue, and precipitated by hydrochloric acid, and collected on a tarred +filter (dried at 100 deg. C.), and dried at 100 deg. C. and weighed. The nitro- +glycerine residue is treated with strong alcohol, decanted, and the +residue of paraffin and sulphur washed with alcohol, dried, and weighed. + +To separate the paraffin from the sulphur the residue is heated with a +solution of ammonium sulphide. After cooling the paraffin collects as a +crust upon the surface of the liquid, and by pricking a small hole through +it with a glass rod the liquid underneath can be poured off, and the +paraffin then washed with water, dried, and weighed. Sulphur is found by +difference. Mr F.W. Smith (_Jour. Amer. Chem. Soc._, 1901, 23 [8], +585-589) determines the sulphur in dynamite gelatine as follows:--About 2 +grms. are warmed in a 100 c.c. silver crucible on the water bath with an +alcoholic solution of sodium hydroxide, and where the nitro-glycerine is +decomposed, the liquid is evaporated to dryness. The residue is fused with +40 grms. of KOH and 5 grms. of potassium nitrate, the mass dissolved in +dilute acetic acid and filtered, and the sulphates precipitated in the +usual way. If camphor is present, it can be extracted with bisulphide of +carbon after the material has been treated with ether-alcohol. In that +case the sulphur, paraffin, and resin will also be dissolved. The camphor +being easily volatile, can be separated by evaporation. Let the weight of +the extract, freed from ether-alcohol before treatment with bisulphide of +carbon, equal A, and the weight of extract after treatment with CS_{2} and +evaporation of the same equal B; and weight of the residue which is left +after evaporation of the CS_{2} and the camphor in solution equal C, the +percentage of camphor will be A - B - C. The residue C may contain traces +of nitro-glycerine, resin, or sulphur. + +Camphor may be separated from nitro-glycerine by means of CS_{2}. If the +solution of camphor in nitro-glycerine be shaken with CS_{2}, the camphor +and a little of the nitro-glycerine will dissolve. The bisulphide solution +is decanted, or poured into a separating funnel and separated from the +nitro-glycerine. The two solutions are then heated on the water bath to +20 deg. C. and then to 60 deg. C., and afterwards in a vacuum over CaCl_{2} until +the CS_{2} has evaporated from them. The camphor evaporates, and leaves +the small quantity of nitro-glycerine which had been dissolved with it. +The other portion is the nitro-glycerine, now free from CS_{2}. The two +are weighed and their weights added together, and equals the nitro- +glycerine present. There is a loss of nitro-glycerine, it being partly +evaporated along with the CS_{2}. Captain Hess has shown that it is equal +to about 1.25 per cent. This quantity should therefore be added to that +found by analysis. Morton Liebschutz, in a paper in the _Moniteur +Scientifique_ for January 1893, very rightly observes that the variety of +dynamites manufactured is very great, all of them having a special +composition which, good or bad, is sometimes of so complicated a nature +that the determination of their elements is difficult. + +The determination of nitro-glycerine in simple dynamite No. 1 is easy; but +not so when the dynamite contains substances soluble in ether, such as +sulphur, resin, paraffin, and naphthalene. After detailing at length the +methods he employs, he concludes with the observation that the knowledge +of the use of acetic acid--in which nitro-glycerine dissolves--for the +determination of nitro-glycerine may be serviceable. Mr F.W. Smith[A] +gives the following indirect method of determining nitro-glycerine in +gelatine dynamite, &c. About 15 grms. of the sample are extracted with +chloroform in a Soxhlet apparatus, and the loss in weight determined. In a +second portion the moisture is determined. A third portion of about 2 +grms. is macerated with ether in a small beaker, the ethereal extract +filtered, and the process of extraction repeated three or four times. The +united filtrates are allowed to evaporate spontaneously, and the residue +warmed gently on the water bath with 5 c.c. of ammonium sulphide solution, +and 10 c.c. of alcohol until the nitro-glycerine is decomposed, after +which about 250 c.c. of water and sufficient hydrochloric acid to render +the liquid strongly acid, are added, and the liquid filtered. The +precipitate is washed free from acid, and then washed through the filter +with strong alcohol and chloroform into a weighed platinum dish, which is +dried to constant weight at 50 deg. C. The contents of the dish are now +transferred to a silver crucible, and the sulphur determined. This amount +of sulphur, deducted from the weight of the contents of the platinum dish, +gives the quantity of substances soluble in chloroform with the exception +of the nitro-glycerine, moisture, and sulphur. The amount of the former +substances _plus_ the moisture and sulphur, deducted from the total loss +on extraction with chloroform, gives the quantity of nitro-glycerine. +Nitro-benzene may be detected, according to J. Marpurgo, in the following +manner:--In a porcelain basin are placed two drops of liquid phenol, three +drops of water, and a fragment of potash as large as a pea. The mixture is +boiled, and the aqueous solution to be tested then added. On prolonged +boiling nitro-benzene produces at the edge of the liquid a crimson ring, +which on the addition of a solution of bleaching powder turns emerald- +green. And nitro-glycerine in ether solution, by placing a few drops of +the suspected solution, together with a drop or two of aniline, upon a +watch-glass, evaporating off the ether, and then adding a drop of +concentrated sulphuric acid to the residue, when, if nitro-glycerine is +present, the H_{2}SO_{4} will strike a crimson colour, due to the action +of the aniline sulphate upon the nitric acid liberated from the nitro- +glycerine. + +[Footnote A: "Notes on the Analysis of Explosives," _Jour. Amer. Chem. +Soc._, 1901, 23 [8], 585-589.] + +~Tonite.~--The analysis of this explosive is a comparatively easy matter, +and can be performed as follows:--Weigh out 10 grms., or a smaller +quantity, and boil with water in a beaker, decanting the liquid four or +five times, and filter. The aqueous solution will contain the nitrate of +barium. Then put the residue on the filter, and wash two or three times +with boiling water. Evaporate the filtrate to dryness in a platinum dish. +Dry and weigh. This equals the Ba(NO_{3})_{2}. If the sample is tonite No. +3, and contains di-nitro-benzol, treat first with ether to dissolve out +this substance. Filter into a dish, and evaporate off the ether, and weigh +the di-nitro-benzol, and afterwards treat residue with water as before. +The residue is dried and weighed, and equals the gun-cotton present. It +should then be treated with a solution of ether-alcohol in a conical +flask, allowed to stand some three hours, then filtered through a weighed +filter paper, dried at 40 deg. C., and weighed. This will give the gun-cotton, +and the difference between this last weight and the previous one will give +the collodion-cotton. A portion of the residue containing both the gun- +cotton and the soluble cotton can be tested in the nitrometer, and the +nitrogen determined. + +~Cordite.~--This explosive consists of gun-cotton (with a little +collodion-cotton in it as impurity), nitro-glycerine, and vaseline--the +proportions being given as 30 per cent. nitro-glycerine, 65 per cent. gun- +cotton, and 5 per cent. vaseline. Its analysis is performed by a +modification of the method given for gelatines. Five grms. may be +dissolved in ether-alcohol in a conical flask, allowed to stand all night, +and then filtered through a linen filter. The residue is washed with a +little ether, pressed, and dried at 40 deg. C., and weighed. It equals the +gun-cotton. The solution contains the nitro-glycerine, soluble cotton, and +vaseline. The cotton is precipitated with chloroform, filtered off, dried, +and weighed. The two ether-alcohol solutions are mixed, and carefully +evaporated down in a platinum dish upon the water bath at a low +temperature. The residue is afterwards treated with strong 80 per cent. +acetic acid, which dissolves out any nitro-glycerine left in it. The +nitro-glycerine is then obtained by difference, or the method suggested to +me privately by Mr W.J. Williams may be used. The residue obtained by +evaporation of the ether-alcohol solution, after weighing, is treated with +alcoholic potash to decompose the nitro-glycerine, water is added and the +alcohol evaporated off. Some ether is then added, and the mixture shaken, +and the ether separated and evaporated, and the residue weighed as +vaseline. + +The moisture should, however, be determined by the method devised by Mr +Arthur Marshall, F.I.C., of the Royal Gunpowder Works, Waltham Abbey, +which is carried out as follows:--The cordite or other explosive is +prepared in the manner laid down for the Abel heat test, that is t say, it +is ground in a small mill, and that portion is selected which passes +through a sieve having holes of the size of No. 8 wire gauge, but not +through one with holes No. 14 wire gauge. + +[Illustration: FIG. 40.--MARSHALL'S APPARATUS FOR MOISTURE IN CORDITE.] + +The form of apparatus used is shown in Fig. 40. It consists of an +aluminium dish A, having the dimensions shown, and the glass cone B +weighing not more than 30 grms. Five grms. of the cordite are weighed into +the aluminium dish A. This is covered with the cone B, and the whole is +accurately weighed, and is then placed upon a metal plate heated by steam +from a water bath. It is left upon the bath until all the moisture has +been driven off, then it is allowed to cool for about half-an-hour in a +desiccator and is weighed. The loss in weight gives accurately the +moisture of the sample. For cordite of the original composition, one +hour's heating is sufficient to entirely drive off the moisture; for +modified cordite containing 65 per cent. of gun-cotton, two hours is +enough, provided that there be not more than 1.3 per cent. of moisture +present. + +If the proportion of nitro-glycerine be higher, a longer heating is +necessary. The aluminium dish must not be shallower than shown in the +figure, for if the distance between the substance and the edge of the +glass cone be less than half an inch, some nitro-glycerine will be lost. +Again, the sample must not be ground finer than stated, else some of the +moisture will be lost in the grinding and sieving operations, and the +result will be too low. In order to be able to drive off all the moisture +in the times mentioned, it is essential that the glass cone shall not fit +too closely on the aluminium dish, consequently the horizontal ledge round +the top of the dish should be bent, so as to render it slightly untrue, +and leave a clearance of about 0.02 inch in some places. If these few +simple precautions be taken, the method will be found to be very accurate. +Duplicate determinations do not differ more than 0.01 per cent.[A] + +[Footnote A: "Determination of Moisture in Nitro-glycerine Explosives," by +A. Marshall, _Jour. Soc. Chem. Ind._, Feb. 29, 1904, p. 154.] + +~The Vaseline~ (C_{16}H_{34}), or petroleum jelly, used has a flash-point +of 400 deg. F. It must not contain more than 0.2 per cent. volatile matter +when heated for 12 hours on the water bath, and should have a specific +gravity of 0.87 at 100 deg. F., and a melting point of 86 deg. F. It is obtained +during the distillation of petroleum, and consists mainly of the portions +distilling above 200 deg. C. It boils at about 278 deg. C. + +~Acetone~ (CH_{3}CO.CH_{3}), or dimethyl ketone, is formed when iso-propyl +alcohol is oxidised with potassium bichromate and sulphuric. It is also +produced in considerable quantities during the dry distillation of wood, +and many other organic compounds. Crude wood spirit, which has been freed +from acetic acid, consists in the main of a mixture of acetone and methyl- +alcohol. The two substances may be roughly separated by the addition of +calcium chloride, which combines with the methyl-alcohol. On subsequent +distillation crude acetone passes over, and may be purified by conversion +into the bisulphite compound. + +Acetone is usually prepared, however, by the dry distillation of crude +calcium or barium acetate. + +(CH_{3}.COO)_{2}Ca = CH_{3}.CO.CH_{3} + CaCO_{3}. + +The distillate is fractionated, and the portion, boiling between 50 deg. and +60 deg. C., mixed with strong solution of sodium bisulphite. The crystalline +cake of acetone sodium bisulphite, which separates on standing, is well +pressed, to free it from impurities, decomposed by distillation with +dilute sodium carbonate, and the aqueous distillate of pure acetone +dehydrated over calcium chloride. Acetone is a colourless, mobile liquid +of sp. gr. .792 at 20 deg. C., it boils at 56.5 deg. C., has a peculiar, pleasant, +ethereal odour, and is mixible with water, alcohol, and ether in all +proportions. + +The acetone used in the manufacture of cordite should conform to the +following specification:-- + +SPECIFICATION FOR ACETONE. + +1. The acetone to be not more than 0.802 specific gravity at 60 deg. F. When +mixed with distilled water it must show no turbidity, and must leave no +residue on evaporation at 212 deg. F. On distillation, four-fifths by volume +of the quantity taken must distil over at a temperature not exceeding 138 deg. +F. The residual matter left after this distillation must not contain, +besides acetone, any ingredient that is not a bye-product incidental to +the manufacture of acetone. + +2. One c.c. of 0.10 per cent. solution in distilled water of pure +permanganate of potash, added to 100 c.c. of the acetone, must retain its +distinctive colour for not less than 30 minutes. This test should be made +at a temperature of 60 deg. F. + +3. The acetone tested by the following method must not show more than +0.005 per cent. of acid, calculated to acetic acid:-- + +To 50 c.c. of the sample diluted with 50 c.c. of distilled water, with 2 +c.c. of phenol-phthalein solution (1 gramme to 1,000 c.c. of 50 per cent. +alcohol) added as an indicator, add from a burette N/100 sodium hydrate +solution (1 c.c. 0.0006 gramme acetic acid), and calculate to acetic acid +in the usual manner. + +The water used for the dilution of the acetone must be carefully tested +for acidity, and the pipettes used for measuring should not be blown out, +as it would be possible thus to neutralise nearly 2 c.c. of the soda +solution. + +The presence of water in a sample of acetone may be detected by Schweitzer +and Lungwitz's method (_Chem. Zeit._, 1895, xix., p. 1384), which consists +in shaking together equal volumes of acetone and petroleum ether (boiling +point, 40 deg. to 60 deg. C.), when if present a separation of the liquid in +layers will take place. + +~Estimation of Acetone.~--Kebler (_Jour. Amer. Chem. Soc._, 1897, 19, 316- +320) has improved Squibb's modification of Robineau and Rollins' method. +The following solutions are required:-- + +(1.) A 6 per cent. solution of hydrochloric acid. + +(2.) A decinormal solution of sodium thiosulphate. + +(3.) Alkaline potassium iodide solution prepared by dissolving 250 grms. +of potassium iodide in water, made up to a litre; dissolving 257 grms. of +sodium hydroxide (by alcohol) in water, likewise made up to a litre. After +allowing the latter to stand, 800 c.c. of the clear solution are added to +the litre of KI. + +(4.) Sodium hypochlorite solution: 100 grms. of bleaching powder (35 per +cent.) are mixed with 400 c.c. of water: to this is added a hot solution +of 120 grms. of crystallised sodium carbonate in 400 c.c. of water. After +cooling, the clear liquid is decanted, the remainder filtered, and the +filtrate made up to a litre; to each litre is added 25 c.c. of sodium +hydroxide solution (sp. gr. 1.29). + +(5.) An aqueous solution of the acetone, containing 1 or 2 per cent. of +acetone. + +(6.) Bicarbonated starch solution prepared by treating 0.125 grm. of +starch with 5 c.c. of cold water, then adding 20 c.c. of boiling water, +boiling a few minutes, cooling, and adding 2 grms. of sodium bicarbonate. + +To 20 c.c. of the potassium iodide solution are added 10 c.c. of the +diluted aqueous acetone, an excess of the sodium hypochlorite solution is +then run in from a burette and well shaken for a minute. The mixture is +then acidified with the hydrochloric acid solution, and while agitated, an +excess of sodium thiosulphate solution is added, the mixture being +afterwards allowed to stand a few minutes. The starch indicator is then +added, and the excess of thiosulphate re-titrated. The relation of the +sodium hypochlorite solution to the sodium thiosulphate being known, the +percentage of acetone can be readily calculated.[A] + +[Footnote A: See "The Testing of Acetone," Conroy, _Jour. Soc. Chem. +Ind._, 31st March 1900, vol. xix.] + +Dr S.J.M. Auld has recently (_Jour. Chem. Soc._, Feb. 15, 1906, vol. xxv.) +worked out a volumetric method for the estimation of acetone, depending on +the formation of bromoform, and its subsequent hydrolysis with alcoholic +potash. The hydrolysis is probably expressed thus-- + +3CHBr_{3} + 9KOH + C_{2}H_{5}OH = 3CO + C_{2}H_{4} + 9KBr + 7H_{2}O + +as it has been shown by Hermann and Long that exactly 3 volumes of carbon +monoxide to 1 of ethylene are evolved. The residual potassium bromide is +estimated by means of standard silver nitrate solution. Bromoform is +specially suitable for this purpose for several reasons. It is very +readily formed by the action of bromine and potash on acetone, and +although very volatile in steam, it is not liable to loss due to its own +evaporation. Further, its high molecular weight and large percentage of +bromine conduce to accurate results, 58 grms. of acetone being responsible +for the formation of 357 grms. of KBr. The method of carrying out the +analysis is as follows:-- + +A known quantity of the solution to be tested, containing acetone to the +extent of 0.1 to 0.2 grm., is pipetted into a 500 c.c. round-bottom flask, +diluted with a little water, and mixed with 20 to 30 c.c. of a 10 per +cent. solution of caustic potash. The flask is connected with a long +reflex condenser, and is also fitted with a dropping funnel containing a +solution of bromine in potassium bromide (200 grms. of Br and 250 grms. of +KBr to 1 litre of water). The bromine solution is allowed to flow into the +mixture until it has acquired a faint yellow tinge, the flask and its +contents being then heated on the water bath at about 70 deg. C. for half-an- +hour. Bromine solution is added drop by drop until the slight coloration +is permanent, excess of bromine being got rid of by boiling for a minute +or two with a little more caustic potash. The mixture is then distilled +until the distillate is free from bromoform, halogen being tested for in +the usual manner. Water is added to the contents of the flask if +necessary. It may be here observed that no acetone can be detected in the +distillate by means of the mercuric oxide test, and free bromine is also +absent. The condenser having been washed out with a little alcohol, in +order to remove any traces of bromoform which may have collected, the +distillate and washings are mixed with 50 c.c. of alcohol and sufficient +solid caustic potash to make an approximately 10 per cent. solution. The +mixture is then heated on the water bath under a reflux condenser until +the bromoform is completely decomposed. This generally occupies about +three-quarters of an hour. The liquid is allowed to cool, evaporated to +smaller bulk if necessary, and exactly neutralised with dilute nitric +acid. It is then diluted with water to 500 c.c., and an aliquot part +titrated with N/10 silver nitrate solution, using potassium chromate as +indicator; 240 parts of bromine correspond to 58 parts of acetone. The +complete analysis can be performed in one and a half to two hours. It is +imperative that the bromine used should be pure, as crude bromine +frequently contains bromoform. The method is suitable for the estimation +of acetone in wood-spirit, the spirit being diluted to 10 times its +volume, and 5 c.c. of this solution employed for the determination. For +example-- + +(1.) Three c.c. of a solution containing 9.61 per cent. acetone gave +1.7850 grm. KBr. Acetone found = 9.66 per cent. + +(2.) Ten c.c. of a solution containing 0.96 per cent. acetone gave 0.5847 +grm. KBr. Acetone found = 0.95 per cent. + +~Nitro-Cotton.~--The first thing upon opening a case of wet cotton, or in +receiving a sample from the "poacher," that requires to be determined is +the percentage of water that it contains. It is best done by weighing out +about 1,000 grms. upon a paper tray, which has been previously dried in +the oven at 100 deg. C. for some time, and become constant in weight. The +trayful of cotton is then placed in a water oven, kept at 100 deg. C., and +dried as long as it loses water. The loss gives the percentage of water. +It varies from 20 to 30 per cent. as a rule in "wet" cotton. + +OUTLINE SCHEME FOR THE ANALYSIS OF NITRO-EXPLOSIVES + _______________________________________________________________________ +| | +| Exhaust dried substance with Anhydrous Ether in Soxhlet's Fat | +| Extraction Apparatus. | +|_______________________________________________________________________| +| | +| _Solution_--Divide into two parts ~A.~ and ~B.~ | +|_______________________________________________________________________| +| | +| ~A.~ | +| | +| Allow ether to evaporate spontaneously. Dry residue in vacuo over | +| H_{2}SO_{4} and weigh. Equals nitro-glycerine, resin, camphor, and | +| paraffin. | +| | +| The nitro-glycerine in this residue may be decomposed by heating | +| with a solution of alcoholic potash. Water may then be added, and the | +| alcohol evaporated off on the water bath. From this solution the | +| resin may be precipitated by HCl, filtered off, dried, and weighed. | +| Solution containing the paraffin is treated with AmS solution and | +| heated. On cooling the paraffin separates, and may be separated. | +| Residue may be shaken with CS_{2} to remove camphor. | +|_______________________________________________________________________| +| | +| ~B.~ | +| | +| Add phenol-phthalein and titrate with alcoholic potash, 1 c.c. normal | +| KHO = .330 grm. _resin_, and add considerably more KHO. Evaporate, | +| dissolve residue in water, shake with ether, and separate. | +|_______________________________________________________________________| +| | +| _Ethereal Solution_ evaporated leaves paraffin. | +|_______________________________________________________________________| +| | +| _Aqueous Solution_-- | +| Add bromide, acidify with HCl, separate any resin and precipitate, | +| filtrate with BaCl_{2} BaSO_{4} x .1373 = Sulphur. | +|_______________________________________________________________________| +| | +| _Residue_-- | +| Dry, weigh, and exhaust with water preferably in Soxhlet. | +|_______________________________________________________________________| +| | | +| _Solution_-- | _Residue_-- | +| Contains metallic | Dry, weigh, and agitate an aliquot part with | +| nitrates, chlorates, | with H_{2}SO_{4} and Hg in nitrometer. If | +| soluble carbonates, | nitro-cellulose is present, treat remainder of | +| the sum of which | residue with ether-alcohol. | +| (except AmCO_{3}) |________________________________________________| +| can be determined by | | +| evaporating down at | _Solution_-- | +| 100 deg. C. to dryness | Evaporate and weigh. Residue consists of | +| and weighing. | soluble nitro-cellulose. | +| Nitrates can be |________________________________________________| +| determined by | | +| | _Residue_-- | +| | Dry and weigh and determine hexa-nitro- | +| | cellulose in nitrometer, if present. Exhaust | +| | remainder with acetic ether. | +| |________________________________________________| +| | | | +| | _Solution_-- | _Residue_-- | +| | Hexa-nitro-cellulose | Dry and weigh, ignite | +| | (Gun cotton). | and reweigh. Loss = | +| | | _Cellulose_. | +| | |_________________________| +| | | | +| | | Residue consists of | +| | | sawdust, charcoal, | +| | | coal, chalk, guhr, | +| | | or mineral matter, &c. | +|______________________|______________________|_________________________| + +NOTE.--Camphor is found by difference. Sulphur is only partially soluble +in ether. It is better, therefore, to extract some of the original +substance with water, and treat residue with alcoholic KHO. Add bromide, +acidify, and precipitate as BaSO. + +~The Solubility Test.~--The object of this test is to ascertain, in the +case of gun-cotton, the percentage of soluble (penta and lower nitrates) +cotton that it contains, or in the case of soluble cotton, the quantity of +gun-cotton. The method of procedure is as follows:--Five grms. of the +sample which has been previously dried at 100 deg. C., and afterwards exposed +to the air for two hours, is transferred to a conical flask, and 250 c.c. +ether-alcohol added (2 ether to 1 alcohol). The flask is then corked and +allowed to digest, with repeated shaking, for two or three hours. The +whole is then transferred to a linen filter, and when the solution has +passed through the filter, is washed with a little ether, and pressed in a +hand-screw press between folds of filter paper. The sample is then +returned to the flask, and the previous treatment repeated, but it will be +sufficient for it to digest for one hour the second time. The filter is +then again pressed first gently by hand, then in the press, and afterwards +opened up and the ether allowed to evaporate. The gun-cotton is then +removed from the filter and transferred to a watch-glass, and dried in the +water oven at 100 deg. C. When dry it is exposed to the air for two hours and +weighed. It equals the amount of gun-cotton and unconverted cotton in the +5 grms. The unconverted cotton must be determined in a separate 5 grms. +and deducted. + +The method of determining the soluble cotton now used in the Government +laboratories is as follows:--Fifty grains of the nitro-cotton are +dissolved in 150 c.c. of ether-alcohol, and allowed to stand, with +frequent shakings, in a 200 c.c. stoppered measure for six hours; 75 c.c. +of the clear solution are then drawn off by the aid of a pipette and +evaporated in a dish on the water bath, and finally in the water oven at +120 deg. F. (49 deg. C.), until constant in weight. The weight found equals the +quantity of soluble cotton in the 75 c.c., which, multiplied by 4, equals +the percentage, thus: Suppose that 2.30 grains was the weight found, then + +(2.3 x 150)/75 = 4.6 in 50 = 9.20 per cent. + +A method for the determination of soluble nitro-cellulose in gun-cotton +and smokeless powder has been published by K.B. Quinan (_Jour. Amer. Chem. +Soc._, 23 [4], 258). In this method about 1 grm. of the finely divided dry +sample to be analysed is placed in an aluminium cup 1.9 inch in diameter +and 4-1/8 inch deep. It is then covered and well stirred with 50 c.c. of +alcohol, 100 c.c. of ether are then added, and the mixture is stirred for +several minutes. After removing the stirrer, the cup is lightly covered +with an aluminium lid, and is then placed in the steel cup of a +centrifugal machine, which is gradually got up to a speed of 2,000 +revolutions per minute, the total centrifugal force at the position +occupied by the cups (which become horizontal when in rapid rotation) is +about 450 lbs. They are rotated at the full speed for ten to twelve +minutes, and the machine is then gradually stopped. By this time the whole +of the insoluble matter will be at the bottom of the cup, and the +supernatant solution will be clear. It is drawn off to within a quarter of +an inch of the bottom (without disturbing the sediment), with the aid of a +pipette. + +Care must be taken that the solution thus withdrawn is perfectly clear. +About 10 to 15 c.c. of colloid solution and a film of insoluble matter +remain at the bottom of the cup; these are stirred up well, the stirrer is +rinsed with ether-alcohol, about 50 c.c. of fresh ether-alcohol are added; +the mixture is again treated in the centrifugal apparatus for about eight +minutes; the whole washing process is then repeated until all soluble +matter has been removed. This may require about seven or eight (or for +samples with much insoluble matter ten or twelve or more) washings, but as +the extraction proceeds, the period of rotation may be somewhat reduced. +After extraction is completed, the insoluble matter is transferred to a +Gooch crucible with the usual asbestos pad, dried at 100 deg. C., and weighed. +The residue may, if wished, be dried and weighed in the aluminium cup, but +then it cannot be ignited. The whole time for an analysis exclusive of +that required for drying, is from one to two hours--average time, 1-1/4 +hour. The results are satisfactory both as to accuracy and rapidity. +Acetone-soluble nitro-cellulose may be determined by the same method. + +~The Unconverted or Non-nitrated Cotton.~--However well the cotton has +been nitrated, it is almost certain to contain a small quantity of non- +nitrated or unconverted cotton. This can be determined thus:--Five grms. +of the sample are boiled with a saturated solution of sodium sulphide, and +then allowed to stand for forty-eight hours, and afterwards filtered or +decanted, and again boiled with fresh solutions of sulphide, and again +filtered, washed first with dilute HCl and then with water, dried, and +weighed. The residue is the cellulose that was not nitrated, plus ash, &c. +It should be ignited, and the weight of the ash deducted from the previous +weight. + +Acetone, and acetic-ether (ethyl-acetate) may also be used as solvents for +the nitro-cellulose. Another process is to boil the gun-cotton, &c., in a +solution of sodium stannate made by adding caustic soda to a solution of +stannous chloride, until the precipitate first formed is just +re-dissolved. This solution dissolves the cellulose nitrates, but does not +affect the cellulose. Dr Lunge found the following process more +satisfactory in the case of the more highly nitrated products:--The +reagent is an alcoholic solution of sodium-ethylate prepared by dissolving +2 to 3 grms. of sodium in 100 c.c. of 95 per cent. alcohol, and mixing the +filtered solution with 100 c.c. of acetone. It has no effect upon +cellulose, but decomposes nitro-cellulose with the formation of a reddish +brown compound, which is soluble in water. In the determination, 5 grms. +of gun-cotton are heated to 40 deg. or 50 deg. C. on the water bath with 150 c.c. +of the reagent, the liquid being shaken at intervals for twenty to thirty +minutes; or the mixture may be allowed to stand for a few hours at the +ordinary temperature. The brown-red solution is decanted from the +undissolved residue, and the latter washed with alcohol and with water, by +decantation, and then on the filter with hot water, to which a little +hydrochloric acid is added for the final washings. For ordinary work this +cellulose is dried immediately and weighed, but in exact determinations it +is washed with alcohol, again treated with 50 c.c. of the reagent, and +separated and washed as before. The cellulose thus obtained, gives no +trace of gas in the nitrometer, and duplicate determinations agree within +0.1 to 0.2 per cent. when the weight of unchanged cellulose amounts to +about 0.2 grm. Gun-cotton, which is completely soluble in acetone, +contains only traces of cellulose, and when as much as 0.85 per cent. is +present it does not dissolve entirely. This method is not applicable to +the determination of cellulose in lower nitrated products, and Dr Lunge +attributes this to the fact that these being prepared with less +concentrated acid invariably contain oxy-cellulose. + +~Alkalinity.~--Five grms. of the air-dried and very finely divided sample +are taken from the centre of the slabs or discs, and digested with about +20 c.c. of N/2 hydrochloric acid, and diluted with water to about 250 +c.c., and shaken for about fifteen minutes. The liquid is then decanted, +and washed with water until the washings no longer give an acid reaction. +The solution, together with the washings, are titrated with N/4 sodium +carbonate, using litmus as indicator. + +~Ash and Inorganic Matter.~--This is best determined by mixing 2 or 3 +grms. of the nitro-cotton in a platinum crucible with shavings of +paraffin, heating sufficiently to melt the paraffin, and then allowing the +contents of the crucible to catch fire and burn away quietly. The +temperature is then raised, and the carbonaceous residue incinerated, +cooled, weighed, &c., and the percentage of ash calculated. Schjerning +proceeds in the following way:--He takes 5 grms. of the nitro-cotton in a +large platinum crucible, he then moistens it with a mixture of alcohol and +ether, in which paraffin has been dissolved to saturation, and filtered +and mixed with one-fourth of its volume of water. Some fragments of solid +paraffin are then added, and the ether set on fire. Whilst this is in +progress the crucible is kept in an oblique position, and is rotated so +that the gun-cotton may absorb the paraffin uniformly. The partially +charred residue is now rubbed down with a rounded glass rod, and the +crucible is covered and heated for from fifteen to twenty minutes over the +blow-pipe, the lid being occasionally removed. The residue is soon +converted into ash, which is weighed, and then washed out into a porcelain +basin and treated with hydrochloric acid heated to 90 deg. C. The oxide of +iron, alumina, lime, and magnesia are thus dissolved, and the silica +remains as insoluble residue. The rest of the analysis is conducted +according to the well-known methods of separation. The percentage of ash +as a whole is generally all that is required. + +~Examination of Nitrated Celluloses with Polarised Light.~--Dr G. Lunge +(_Jour. Amer. Chem. Soc._, 1901, 23 [8], 527) has formed the following +conclusions:--The most highly nitrated products appear blue in polarised +light, but those containing between 13.9 and 13.0 per cent. of nitrogen +cannot be distinguished from each other by polarisation. As the percentage +of nitrogen rises, the blue colour becomes less intense, and here and +there grey fibres can be observed, though not in proportion to the +increase in the nitrogen. Below 12.4 per cent. of nitrogen, the fibres +show a grey lustre, which usually appears yellow when the top light is cut +off. Below 10 per cent. of nitrogen, the structure is invariably partially +destroyed and no certain observations possible. It is only possible to +distinguish with certainty, firstly any unchanged cellulose by its +flashing up in variegated (rainbow) colours; and secondly, highly nitrated +products (from 12.75 per cent. N upwards), by their flashing up less +strongly in blue colours. The purple transition stage in the fibres +containing over 11.28 per cent. of N (Chardonnet) was not observed by Dr +Lunge. + +~Determination of Nitrogen by Lunge Nitrometer.~--The determination of the +percentage of nitrogen in a sample of gun-cotton or collodion is perhaps +of more value, and affords a better idea of its purity and composition, +than any of the foregoing methods of examination, and taken in conjunction +with the solubility test, it will generally give the analyst a very fair +idea of the composition of his sample. If we regard gun-cotton as the +hexa-nitro-cellulose, the theoretical amount of nitrogen required for the +formula is 14.14 per cent., and in the same way for collodion-cotton, +which consists of the lower nitrates, chiefly, however, of the penta- +nitrate, the theoretical nitrogen is 12.75 per cent., so that if in a +sample of nitro-cotton the nitrogen falls much lower than 14 per cent., it +probably contains considerable quantities of the lower nitrates, and +perhaps some non-nitrated cellulose as well (C_{6}H_{10}O_{5})_{x}, which +of course would also lower the percentage of nitrogen. + +The most expeditious method of determining the nitrogen in these nitro +bodies is by the use of Lunge's nitrometer (Fig. 41), and the best way of +working the process is as follows:--Weigh out with the greatest care 0.6 +grm. of the previously dried substance in a small weighing bottle of about +15 c.c. capacity, and carefully add 10 c.c. of concentrated sulphuric acid +from a pipette, and allow to stand until all the cotton is dissolved. The +nitrometer should be of a capacity 150 to 200 c.c., and should contain a +bulb of 100 c.c. capacity at the top, and should be fitted with a Greiner +and Friederich's three-way tap. When the nitro-cotton has entirely +dissolved to a clear solution, raise the pressure tube of the nitrometer +so as to bring the mercury in the measuring tube close up to the tap. Open +the tap in order to allow of the escape of any air bubbles, and clean the +surface of the mercury and the inside of the cup with a small piece of +filter paper. Now close the tap, and pour the solution of the nitro-cotton +into the cup. Rinse out the bottle with 15 c.c. of sulphuric acid, +contained in a pipette, pouring a little of the acid over the stopper of +the weighing bottle in case some of the solution may be on it. Now lower +the pressure tube a little, just enough to cause the solution to flow into +the bulb of the measuring tube, when the tap is slightly opened. When the +solution has run in almost to the end, turn off the tap, wash down the +sides of the bottle, and add to the cup of the nitrometer; allow it to +flow in as before, and then wash down the sides of the cup with 10 c.c. of +sulphuric acid, adding little by little, and allowing each portion added +to flow into the bulb of the nitrometer before adding the next portion. +Great care is necessary to prevent air bubbles obtaining admission, and if +the pressure tube is lowered too far, the acid will run with a rush and +carry air along with it. + +[Illustration: FIG. 41.--ORDINARY FORM OF LUNGE NITROMETER.] + +The solution being all in the measuring tube, the pressure tube is again +slightly raised, and the tube containing the nitro-cotton solution shaken +for ten minutes with considerable violence. It is then replaced in the +clamp, and the pressure relieved by lowering the pressure tube, and the +whole apparatus allowed to stand for twenty minutes, in order to allow the +gas evolved to assume the temperature of the room. A thermometer should be +hung up close to the bulb of the measuring tube. At the end of the twenty +minutes, the levels of the mercury in the pressure and measuring tubes are +equalised, and the final adjustment obtained by slightly opening the tap +on the measuring tube (very slightly), after first adding a little +sulphuric acid to the cup, and observing whether the acid runs in or moves +up. This must be done with very great care. When accurately adjusted, it +should move neither way. Now read off the volume of the NO gas in cubic +centimetres from the measuring tube. Read also the thermometer suspended +near the bulb, and take the height of the barometer in millimetres. The +calculation is very simple. + +EXAMPLE--COLLODION-COTTON. + +0.6[A] grm. taken. Reading on measuring tube = 114.6 c.c. NO. Barometer-- +758 mm. Temperature--15 deg. C. + +[Footnote A: 0.5 grm. is enough in the case of gun-cotton.] + +Since 1 c.c. NO = 0.6272 milligramme N, and correcting for temperature and +pressure by the formula + +760 x (1 + _d_^{2}) (_d_ = .003665), for temperature 15 deg. = 801.78,[A] + +then + +(114.6 x 100 x 750 x .6272)/(801.7 x. 6) = 11.22 per cent. nitrogen. + +[Footnote A: See Table, page 244.] + +The nitrogen in nitro-glycerine may of course be determined by the +nitrometer, but in this case it is better to take a much smaller quantity +of the substance. From 0.1 to 0.2 grm. is quite sufficient. This will give +from 30 to 60 c.c. of gas, and therefore a measuring tube without a 100 +c.c. bulb must be used. + +EXAMPLE. + +0.1048 grm. nitroglycerine taken gave 32.5 c.c. NO. Barometer, 761 mm. +Temperature, 15 deg. C. + +Therefore, + +(3.25 x 100 x 761 x .6272)/(801.78 x.1048) = 18.46 per cent. N. Theory = +18.50 per cent. + +Professor Lunge has devised another form of nitrometer (Fig. 42), very +useful in the nitrogen determination in explosives. It consists of a +measuring tube, which is widened out in the middle to a bulb, and is +graduated above and below into 1/10 c.c. The capacity of the whole +apparatus is 130 c.c.; that of each portion of the tube being 30 c.c., and +of the bulb 70 c.c. The upper portion of the graduated tube serves to +measure small volumes of gas, whilst larger volumes are read off on the +lower part. + +[Illustration: FIG. 42. FIG. 43. SOME NEW FORMS OF NITROMETER.] + +F.M. Horn (_Zeitschrift fuer angewandte Chemie_, 1892, p. 358) has devised +a form of nitrometer (Fig. 43) which he has found especially useful in the +examination of smokeless powders. The tap H is provided with a wide bore +through which a weighed quantity of the powder is dropped bodily into the +bulb K. From 4 to 5 c.c. of sulphuric acid which has been heated to 30 deg. C. +are then added through the funnel T, the tap H being immediately closed. +When the powder has dissolved--a process which may be hastened by warming +the bulb very carefully--the thick solution is drawn into the nitrometer +tube N, and the bulb rinsed several times with fresh acid, after which +operation the analysis is proceeded with in the usual way. + +Dr Lunge's method of using a separate nitrometer in which to measure the +NO gas evolved to the one in which the reaction has taken place, the gas +being transferred from the one to the other by joining them by means of +indiarubber tubing, and then driving the gas over by raising the pressure +tube of the one containing the gas, the taps being open, I have found to +be a great improvement. + +1 c.c. NO gas at 0 deg. and 760 mm. +Equals 0.6272 milligrammes (N) nitrogen. + " 1.343 " nitric oxide. + " 2.820 " (HNO_{3}) nitric acid. + " 3.805 " (NaNO_{3}) sodium nitrate. + " 4.523 " (KNO_{3}) potassium nitrate. + +~Champion and Pellet's Method.~--This method is now very little used. It +is based upon the fact that when nitro-cellulose is boiled with ferrous +chloride and hydrochloric acid, all the nitrogen is disengaged as nitric +oxide (NO). It is performed as follows:--A vacuum is made in a flask, +fitted with a funnel tube, with a glass stopper on the tube; a delivery +tube that can also be closed, and which dips under a solution of caustic +soda contained in a trough, and the end placed under a graduated tube, +also full of caustic soda. From 0.12 to 0.16 grm. cotton dissolved in 5 to +6 c.c. of sulphuric acid is allowed to flow into the flask, which contains +the ferrous chloride and hydrochloric acid, and in which a vacuum has been +formed by boiling, and then closing the taps. The solution is then heated, +the taps on the delivery tube opened, and the end placed under the +collecting tube, and the NO evolved collected. The NO gas is not evolved +until the solution has become somewhat concentrated. Eder substituted a +solution of ferrous sulphate in HCl for ferrous chloride. Care must be +taken that the flask used is strong enough to stand the pressure, or it +will burst. + +The same chemists (_Compt. Rendus_, lxxxiii. 707) also devised the +following method for determining the NO_{2} in nitro-glycerine:--A known +quantity of a solution of ferrous sulphate of previously ascertained +reducing power is placed in a flask, acidified with hydrochloric acid, and +its surface covered with a layer of petroleum oil. About .5 grm. of the +nitro-glycerine is then introduced, and the flask heated on the water +bath. When the sample is completely decomposed, the liquid is heated to +boiling to remove nitric oxide, and the excess of ferrous sulphate +ascertained by titration with standard permanganate; 56 of iron (Fe) +oxidised by the sample correspond to 23 of NO_{2} in the sample of +nitro-glycerine. + +~The Schultze-Tieman Method~ for determining nitrogen in nitro-explosives, +especially nitro-cellulose and nitro-glycerine.--The figure (No. 44) shows +the general arrangement of the apparatus. I am indebted for the following +description of the method of working it to my friend, Mr William Bate, of +Hayle. To fill the apparatus with the soda solution, the gas burette is +put on the indiarubber stopper of basin W, and firmly clamped down. Then +the taps A and C are opened, and B closed. When the burette is filled with +soda solution half-way up the funnel Y, A and C are closed, and B opened. +The arrows show the inlet and outlet for the cooling water that is kept +running through the water jacket round the nitrometer tube. To collect the +gas, raise the nitrometer off the rubber stopper, and place the gas tube +from the decomposition apparatus in the glass dish W and under the opening +of the nitrometer. + +[Illustration: Fig. 44. SCHULTZE-TIEMAN APPARATUS.] + +For the estimation of nitrogen in nitro-cellulose take .5 to .65 grm., and +place in the decomposition flask _f_ (Fig. 45), washing in with about 25 +c.c. of water by alternately opening clips D and E. The air in the flask +is driven out by boiling, whilst the air is shut off by the tube _i_ +dipping into the basin W, which is filled with the soda lye, and tube K is +placed in the test tube R, which contains a few c.c. of water. As soon as +all the air is completely driven out, clips D and E are closed, and the +gas jet is taken away. (This flask must be a strong one, or it will +burst.) Into test tube R, 25 c.c. of concentrated solution of +protochloride of iron and 10 to 15 c.c. concentrated hydrochloric acid are +poured, which are sucked up into the developing flask _f_ by opening clip +E, air being carefully kept from entering. The clip E is now closed, and +tube _i_ is put underneath the burette, and the development of NO gas is +commenced by heating the contents of the flask _f_. When the pressure of +the gas in the flask has become greater than the pressure of the +atmosphere, the connecting tube begins to swell at _i_, whereupon clip D +is opened, and the boiling continued with frequent shaking of the bulb, +until no more nitrous gas bubbles rise up into the soda lye, the +distilling over of the HCl causes a crackling noise, the clip D is closed, +and E opened. The burette is again put hermetically on the indiarubber +stopper in basin W, and the apparatus is left to cool until the water +discharged through P shows the same temperature as the water flowing +through (into the cooling jacket) Z. If the level of the soda solution in +the tube X is now put on exactly the same level as that in the burette by +lowering or elevating the tube X as required, the volume of NO obtained in +c.c. can be read off within 1/10 c.c., and the percentage of nitrogen +calculated by the usual formula. + +[Illustration: FIG. 45.--Decomposition Flask for Schultze-Tieman Method.] + +The solution of protochloride of iron is obtained by dissolving iron +nails, &c., in concentrated HCl, the iron being in excess. When the +development of hydrogen ceases, it is necessary to filter warm through a +paper filter, and acidify filtrate with a few drops of HCl. The soda +solution used has a sp. gr. of 1.210 to 1.260; equals 25 deg. to 30 deg. B. The +nitro-cellulose is dried in quantities of 2 grms. at 70 deg. C. during eight +to ten hours, and then three hours in an exiccator over H_{2}SO_{4}. The +results obtained with this apparatus are very accurate. The reaction is +founded upon that of MM. Champion and Pellet's method. + +~The Kjeldahl Method of Determining Nitrogen.~--This method, which has +been so largely used by analysts for the determination of nitrogen in +organic bodies, more especially perhaps in manures, was proposed by J. +Kjeldahl,[A] of the Carlsberg Laboratory of Copenhagen. It was afterwards +modified by Jodlbauer, of Munich,[B] and applied to the analysis of nitro- +explosives by M. Chenel, of the Laboratoire Centrale des Poudres, whose +method of procedure is as follows:--0.5 grm. of the finely powdered +substance is digested in the cold with a solution of 1.2 grm. of phenol +and 0.4 grm. phosphoric anhydride in 30 c.c. of sulphuric acid. The +mixture is kept well shaken until the solution is complete. From 3 to 4 +grms. of zinc-dust is then cautiously and gradually added, the temperature +of the mass being kept down until complete reduction has been effected. +Finally, 0.7 grm. of mercury is added, and the process continued in the +usual way, according to Kjeldahl; that is, the liquid is distilled until +all the ammonia has passed over, and is absorbed in the standard acid. The +distillate is then titrated with standard ammonia. + +[Footnote A: J. Kjeldahl, _Zeitschrift Anal. Chem._, 1883, xxii., p. 366.] + +[Footnote B: Jodlbauer, _Chemisches Centralblatt_, 1886, pp. 434-484. See +also _Arms and Explosives_, 1893, p. 87.] + +The NO_{2} group is at the moment of solution fixed upon the phenol with +the production of mono-nitro-phenol, which is afterwards reduced by the +action of the zinc-dust into the amido derivative. During the subsequent +combustion, the nitrogen of the amido-phenol becomes fixed in the state of +ammonia. M. Chenel is perfectly satisfied with the results obtained, but +he points out that the success of the operation depends upon the complete +conversion of the phenol into the mono-nitro derivatives. This takes place +whenever the organic compound forms a _clear solution_ in the cold +sulphuric acid mixture. Substances like collodion or gun-cotton must be +very finely divided for successful treatment. The following table shows +some of the results obtained by M. Chenel:-- + + ______________________________________________ +| | | +| | Total Nitrogen. | +| Substances Analysed. |______________________| +| | | | +| | Calculated. | Found. | +| |_____________|________| +| | | | +| Saltpetre (KNO_{3}) | 13.86 | 13.91 | +| | | 13.82 | +| | | 13.73 | +| | | 13.96 | +| Ammonium nitrate | 35.00 | 35.31 | +| | | 34.90 | +| | | 34.96 | +| Barium nitrate | 10.72 | 10.67 | +| | | 10.62 | +| Nitro-glycerol | 18.50 | 18.45 | +| Di-nitro-benzol[A] | 16.67 | 16.78 | +| | | 16.57 | +| Para-nitro-phenol | 10.07 | 10.03 | +| Picric acid[A] | 18.34 | 18.42 | +| | | 18.43 | +| Ammonium picrate | 22.76 | 22.63 | +| | | 22.67 | +| Di-nitro-ortho-cresol | 14.14 | 14.10 | +| | | 13.98 | +| Tri-nitro-meta-cresol | 17.28 | 17.57 | +| | | 17.27 | +|_______________________|_____________|________| + +[Footnote A: Dr. Bernard Dyer obtained 18.39 per cent. for picric acid and +16.54 per cent. for di-nitro-benzol.--_Jour. Chem. Soc._, Aug. 1895.] + +When Chenel endeavoured to apply Jodlbauer's modification of Kjeldahl's +process to the examination of the tri- and tetra-nitrated naphthalenes, he +found that good results were not obtainable, because these compounds do +not dissolve completely in the cold sulphuric acid. It may, however, be +used if they are previously converted into the naphthylamines, according +to the plan proposed by D'Aguiar and Lautemann (_Bull. Soc. Chim._, vol. +iii., new series, p. 256). This is rapidly effected as follows:--Twelve +grms. of iodine are gradually added to a solution of 2 grms. of phosphorus +in about 15 or 20 c.c. of bisulphide of carbon, this solution being +contained in a flask of 250 c.c. capacity. The flask and its contents are +heated on the water bath at 100 deg. C. with constant attention, until the +last traces of the carbon bisulphide have distilled away. It is then +cooled, and the iodide of phosphorus is detached from the sides of the +flask by shaking, but not expelled. The next step is to add about 0.5 to +0.6 grm. of the substance that is to be analysed, after which 8 grms. of +water are introduced, and the flask is agitated gently two or three times. +As soon as the reaction becomes lively, the contents of the flask are well +shaken. It is usually finished about one minute after the addition of the +water. The flask is now cooled, and 25 c.c. of sulphuric acid, together +with 0.7 grm. of mercury, are gradually added; hydriodic acid (HI) forms, +and the temperature of the flask must be raised sufficiently to expel it. +The remaining part of the operation is as in the ordinary Kjeldahl +process. + +M. Chenel has found this process the best for the analysis of the nitro- +naphthalenes, and for impervious substances like collodion or gun-cotton. +Personally, I have never been able to obtain satisfactory results with +this process in the analysis of nitro-cellulose, and I am of opinion that +the process does not possess any advantage over the nitrometer method, at +any rate for the analysis of gun-cotton. + +Table giving the Percentages of Nitrogen and Oxide of Nitrogen in Various +Substances used in or as Explosives: + + Name FORMULAE NITROGEN NO_{2} + per cent. per cent. + +Nitroglycerine C_{3}H_{5}(ONO_{2})_{3} 18.50 = 60.70 +Hexa-nitro-cellulose C_{12}H_{14}O_{4}(ONO_{2})_{6} 14.14 = 46.42 +Penta-nitro-cellulose C_{6}H_{8}O_{5}(ONO_{2})_{5} 11.11 = 36.50 +Nitro-benzene C_{6}H_{5}NO_{2} 11.38 = 37.39 +Di-nitro-benzene C_{6}H_{4}(NO_{2})_{2} 16.67 = 54.77 +Tri-nitro-benzene C_{6}H_{3}(NO_{2})_{3} 19.24 = 63.22 +Nitro-toluene C_{7}H_{7}NO_{2} 10.21 = 33.49 +Nitro-naphthalene C_{10}H_{7}NO_{2} 8.09 = 26.53 +Di-nitro-naphthalene C_{10}H_{6}(NO_{2})_{2} 12.84 = 42.12 +Nitro-mannite C_{6}H_{7}(NO_{3})_{6} 23.59 = 77.37 +Nitro-starch C_{6}H_{8}O_{4}(HNO_{3}) 6.76 = 22.18 +Picric acid + (Tri-nitro-phenol) C_{6}H_{2}OH(NO_{2})_{3} 18.34 = 60.15 +Chloro-nitro-benzene C_{6}H_{3}Cl(NO_{2})_{2} 13.82 = 45.43 +Ammonium nitrate NH_{4}NO_{3} 35.00 = +Sodium nitrate NaNO_{3} 16.47 = +Potassium nitrate KNO_{3} 13.86 = +Nitric acid HNO_{3} 22.22 = +Barium nitrate Ba(NO_{3})_{2} 10.72 = + +~Analysis of Celluloid.~--The finely divided celluloid is well stirred, by +means of a platinum wire, with concentrated sulphuric acid in the cup of a +Lunge nitrometer, and when dissolved the nitrogen determined in the +solution in the usual way. To prevent interference from camphor, the +following treatment is suggested by H. Zaunschirm (_Chem. Zeit._, xiv., +905). Dissolve a weighed quantity of the celluloid in a mixture of ether- +alcohol, mixed with a weighed quantity of washed and ignited asbestos, or +pumice-stone, dry, and disintegrate the mass, and afterwards extract the +camphor with chloroform, dry, and weigh: then extract with absolute +methyl-alcohol, evaporate, weigh, and examine the nitro-cellulose in the +nitrometer. + +~Picric Acid and Picrates.~--Picric acid is soluble in hot water, and to +the extent of 1 part in 100 in cold water, also in ether, chloroform, +glycerine, 10 per cent. soda solution, alcohol, amylic alcohol, carbon +bisulphide, benzene, and petroleum. If a solution of picric acid be boiled +with a strong solution of potassium cyanide, a deep red liquid is +produced, owing to the formation of potassium iso-purpurate, which +crystallises in small reddish-brown plates with a beetle-green lustre. +This, by reaction with ammonium chloride, gives ammonium iso-purpurate +(NH_{4}C_{8}H_{4}N_{5}O_{6}), or artificial murexide, which dies silk and +wool a beautiful red colour. On adding barium chloride to either of the +above salts, a vermilion-red precipitate was formed, consisting of barium +iso-purpurate. With ammonio-sulphate of copper, solutions of picric acid +give a bright green precipitate. Mr A.H. Allen gives the following methods +for the assay of commercial picric acid, in his "Commercial Organic +Analysis":-- + +~Resinous and Tarry matters~ are not unfrequently present. They are left +insoluble on dissolving the sample in boiling water. The separation is +more perfect if the hot solution be exactly neutralised by caustic soda. + +~Sulphuric Acid, Hydrochloric Acid, and Oxalic Acid~, and their salts are +detected by adding to the filtered aqueous solution of the sample +solutions of the picrates of barium, silver, and calcium. These salts are +readily made by boiling picric acid with the carbonates of the respective +metals and filtering: other soluble salts of these methods may be +substituted for the picrates, but they are less satisfactory. + +~Nitric Acid~ may be detected by the red fumes evolved on warming the +sample with copper turnings. + +~Inorganic Impurities and Picrates of Potash and Sodium~, &c., leave +residues on cautious ignition. + +~General Impurities and Adulterations~ may be detected and determined by +shaking 1 grm. of the sample of acid in a graduated tube with 25 c.c. of +ether, the pure acid dissolves, while any oxalic acid, nitrates, picrates, +boric acid, alum, sugar, &c., will be left insoluble, and after removal of +the ethereal liquid, may be readily identified and determined. For the +detection and determination of water and of oxalic acid, 50 c.c. of warm +benzene may be advantageously substituted for ether. Sugar may be +separated from the other impurities by treating the residue insoluble in +ether or benzene with rectified spirit, in which sugar and boric acid +alone will dissolve. If boric acid be present, the alcoholic solution will +burn with a green flame. Mono- and di-nitrophenic acids lower the melting +point (122 deg. C). Their calcium salts are less soluble than the picrate, and +may be approximately separated from it by fractional crystallisation, or +by precipitating the hot saturated solution of the sample with excess of +lime water. Picric acid may be determined by extracting the acidulated +aqueous solution by agitation with ether or benzene, and subsequently +removing and evaporating off the solvent. It may also be precipitated as +the potassium salt. + +~Potassium Picrate~ [KC_{6}H_{2}(NO_{2})_{3}O]. When a strong solution of +picric acid is neutralised by carbonate of potash, this salt is thrown +down in yellow crystalline needles, which require 260 parts of cold or 14 +parts of hot water for their solution. In alcohol it is much less soluble. + +~Ammonium Picrate~ is more soluble in water than the above, and sodium +picrate is readily soluble in water, but nearly insoluble in solution of +sodium carbonate. + +~Picrates of the Alkaloids.~--Picric acid forms insoluble salts with many +of the alkaloids, and picric acid may be determined in the following +manner:--To the solution of picric acid, or a picrate, add a solution of +sulphate of cinchonine acidulated with H_{2}SO_{4}. The precipitated +picrate of cinchonine [C_{20}H_{24}N_{2}O(C_{6}H_{2}N_{3}O_{7})_{2}] is +washed with cold water, rinsed off the filter into a porcelain crucible or +dish, the water evaporated on the water bath, and the residual salt +weighed. Its weight, multiplied by .6123, gives the quantity of picric +acid in the sample taken. + +~Analysis of Glycerine.~[A] Glycerine that is to be used for the +manufacture of nitro-glycerine should have a minimum specific gravity of +1.261 at 15 deg. C. This can be determined, either by the aid of a Sartorius +specific gravity balance, or by using an ordinary specific gravity bottle. +One of 10 or 25 c.c. capacity is very convenient. + +[Footnote A: See also Sulman and Berry, _Analyst_, xi., 12-34, and Allen's +"Commercial Organic Analysis," vol. ii., part i.] + +~Residue~[A] left upon evaporation should not be more than 0.25 per cent. +To determine this, take 25 grms. of the glycerine, and evaporate it at a +temperature of about 160 deg. C. in a platinum basin, and finish in an air +bath. Weigh until constant weight is obtained. Afterwards incinerate over +a bunsen burner, and weigh the ash. + +[Footnote A: Organic matter up to .6 per cent. is not always prejudicial +to the nitrating quantities of a glycerine.] + +~Silver Test.~ A portion of the sample of glycerine to be tested should be +put in a small weighing bottle, and a quarter of its bulk of N/10 silver +nitrate solution added to it, then shake it, and place in a dark cupboard +for fifteen minutes. It must be pronounced bad if it becomes black or dark +brown within that time (acrolein, formic, and butyric acids). + +The German official test for glycerine for pharmaceutical purposes is much +more stringent, 1 c.c. of glycerine heated to boiling with 1 c.c. of +ammonia solution and three drops of silver nitrate solution must give +neither colour or precipitate within five minutes. + +~Nitration.~ Fifty grms. of the glycerine are poured from a beaker into a +mixture of concentrated nitric acid (specific gravity 1.53) and sulphuric +acid (1.84), mixed in the proportions of 3 HNO_{3} to 5 H_{2}SO_{4} (about +400 c.c. of mixed acids). The mixed acids should be put into a rather +large beaker, and held in the right hand in a basin of water, and the +glycerine slowly poured into them from a smaller one held in the left. A +constant rotatory motion should be given to the beaker in which the +nitration is performed. When all the glycerine has been added, and the +mixture has been shaken for a few minutes longer, it is poured into a +separator, and allowed to stand for some time. It should, if the glycerine +is a good one, have separated from the mixed acids in ten minutes, and the +line of demarcation between the nitro-glycerine and the acid should be +clear and sharp, neither should there be any white flocculent matter +suspended in the liquid. The excess of acids is now drawn off, and the +nitro-glycerine shaken once or twice with a warm solution of carbonate of +soda, and afterwards with water alone. The nitro-glycerine is then drawn +off into a weighed beaker, the surface dried with a piece of filter paper, +and weighed; 100 parts of a good glycerine should yield about 230 of +nitro-glycerine. A quicker method is to take only 10 c.c. of the +glycerine, of which the specific gravity is already known, nitrate as +before, and pour into a burette, read off the volume of nitro-glycerine in +c.c. and multiply them by 1.6 (the specific gravity of nitro-glycerine), +thus: 10 grms. gave 14.5 c.c. nitro-glycerine, and 14.5 x 1.6 = 23.2 +grms., therefore 100 would give 232 grms. nitro-glycerine. The points to +be noted in the nitration of a sample of glycerine are: the separation +should be sharp, and within half an hour or less, and there should be no +white flocculent matter formed, especially when the carbonate of soda +solution is added. + +~Total Acid Equivalent.~ Mr G.E. Barton (_Jour. Amer. Chem. Soc._, 1895) +proposes to determine thus: 100 c.c. of glycerine are diluted to 300 c.c. +in a beaker, a few drops of a 1 per cent. solution of phenolphthalein and +10 c.c. of normal caustic soda solution are added; after boiling, the +liquid is titrated with normal hydrochloric acid (fatty acids are thus +indicated and roughly determined). + +~Neutrality.~ The same chemist determines the neutrality of glycerine +thus: 50 c.c. of glycerine mixed with 100 c.c. of water and a few drops of +alcoholic phenolphthalein[A] are titrated with hydrochloric acid or sodium +hydroxide; not more than 0.3 c.c. normal hydrochloric acid or normal soda +solution should be required to render the sample neutral; raw glycerines +contain from .5 to 1.0 per cent. of sodium carbonate. + +[Footnote A: Sulman and Berry prefer litmus as indicator.] + +~Determination of Free Fatty Acids.~ A weighed quantity of the glycerine +is shaken up with some neutral ether in a separating funnel, the glycerine +allowed to settle, drawn off, and the ether washed with three separate +lots of water. The water must have been recently boiled, and be quite free +from CO_{2}. All the free fatty acid is now in the ether, and no other +soluble acid. A drop of phenolphthalein is now added, a little water, and +the acidity determined by titration with deci-normal baryta solution, and +the baryta solution taken calculated as oleic acid. + +~Combined Fatty Acid.~ About 30 grms. of the glycerine are placed in a +flask, and to it is added about half a grm. of caustic soda in solution. +The mixture is heated for ten minutes at 150 deg. C. After cooling some pure +ether is added to it, and enough dilute H_{2}SO_{4} to render it +distinctly acid. It is well shaken. All the fatty acids go into the ether. +The aqueous solution is then removed, and the ether well washed to remove +all H_{2}SO_{4}. After the addition of phenolphthalein the acid is +titrated, and the amount used calculated into oleic acid. From this total +amount of fatty acids the free fatty acid is deducted, and the quantity of +combined fatty acids thus obtained. + +~Impurities.~ The following impurities may be found in bad samples of +glycerine:--Lead, arsenic, lime, chlorine, sulphuric acid, thio-sulphates, +sulphides, cyanogen compounds, organic acids (especially oleic acid and +fatty acids[A]), rosin products, and other organic bodies. It is also said +to be adulterated with sugar and glucose dextrine. Traces of sulphuric +acid and arsenic may be allowed, also very small traces indeed of lime and +chlorine. + +[Footnote A: These substances often cause trouble in nitrating, white +flocculent matter being formed during the process of washing.] + +The organic acids, formic and butyric acids may be detected by heating a +sample of the glycerine in a test tube with alcohol and sulphuric acid, +when, if present, compound ethers, such as ethylic formate and butyrate, +the former smelling like peaches and the latter of pine-apple, will be +formed. + +~Oleic Acid~, if present in large quantity, will come down upon diluting +the sample with water, but smaller quantities may be detected by passing a +current of nitrogen peroxide, N_{2}O_{4} (obtained by heating lead +nitrate), through the diluted sample, when a white flocculent precipitate +of elaidic acid, which is less soluble than oleic acid, will be thrown +down. By agitating glycerol with chloroform, fatty acids, rosin oil, and +some other impurities are dissolved, while certain others form a turbid +layer between the chloroform and the supernatant liquid. On separating the +chloroform and evaporating it to dryness, a residue is obtained which may +be further examined. + +~Sodium Chloride~ can be determined in 100 c.c. of the glycerine by adding +a little water, neutralised with sodium carbonate, and then titrated with +a deci-normal solution of silver nitrate, using potassium chromate as +indicator. + +~Organic Impurities~ of various kinds occur in crude glycerine, and are +mostly objectionable. Their sum may be determined with fair accuracy by +Sulman and Berry's method: 50 grms. of the sample are diluted with twice +its measure of water, carefully neutralised with acetic acid, and warmed +to expel carbonic acid; when cold, a solution of basic lead acetate is +added in slight but distinct excess, and the mixture well agitated. The +formation of an abundant precipitate, which rapidly subsides, is an +indication of considerable impurity in the sample. To ascertain its +amount, the precipitate is first washed by decantation, and then collected +on a tared, or preferably a double counter-poised filter, where it is +further washed, dried at 100 deg. to 105 deg. C., and weighed. The precipitate and +filter paper are then ignited separately in porcelain, at a low red heat, +the residues moistened with a few drops of nitric acid and reignited; the +weight of the lead oxide deducted from that of the original precipitate +gives the weight of the organic matter precipitated by the lead. Raw +glycerines contain from 0.5 to 1.0 per cent. + +~Albuminous Matters.~ An approximate determination of the albuminous +matters may be made by precipitating with basic lead acetate as already +described, and determining the nitrogen by the Kjeldahl method; the +nitrogen multiplied by 6.25 gives the amount of albuminous matter in the +precipitate. + +~The Determination of Glycerine.~ The acetin method of Benedikt and Canton +depends upon the conversion of glycerine into triacetin, and the +saponification of the latter, and reduces the estimation of glycerine to +an acidmetric method. About 1.5 grm. of crude glycerine is heated to +boiling with 7 grms. of acetic anhydride, and 3 to 4 grms. of anhydrous +sodium acetate, under an upright condenser for one and a half hours. After +cooling, 50 c.c. of water are added, and the mixture heated until all the +triacetin has dissolved. The liquid is then filtered into a large flask, +the residue on the filter is well washed with water, the filtrate quite +cooled, phenolphthalein is added and the fluid exactly neutralised with a +dilute (2 to 3 per cent.) solution of alkali. Twenty-five c.c. of a 10 per +cent. caustic soda solution, which must be accurately standardised upon +normal acid, are then pipetted into the liquid, which is heated to boiling +for ten minutes to saponify the triacetin, and the excess of alkali is +then titrated back with normal acid. One c.c. of normal acid corresponds +to .03067 grm. of glycerine. + +~Precautions.~--The heating must be done with a reflux condenser, the +triacetin being somewhat volatile. The sodium acetate used must be quite +anhydrous, or the conversion of the glycerine to triacetyl is imperfect. +Triacetin in contact with water gradually decomposes. After acetylation is +complete, therefore, the operations must be conducted as rapidly as +possible. It is necessary to neutralise the free acetic acid very +cautiously, and with rapid agitation, so that the alkali may not be +locally in excess. + +~The Lead Oxide Method.~--Two grms. of sample are mixed with about 40 +grms. of pure litharge, and heated in an air bath to 130 deg. C. until the +weight becomes constant, care being taken that the litharge is free from +such lead compounds and other substances as might injuriously affect the +results, and that the heating of the mixture takes place in an air bath +free from carbonic acid. The increase in weight in the litharge, minus the +weight of substance not volatilisable from 2 grms. of glycerine at 160 deg. +C., multiplied by the factor 1.243, is taken as the weight of glycerine in +the 2 grms. of sample. The glycerine must be fairly pure, and free from +resinous substances and SO_{3}, to give good results by this process. + +~Analysis of the "Waste Acids" from the Manufacture of Nitro-Glycerine or +Gun-Cotton.~ Determine the specific gravity by the specific gravity bottle +or hydrometer, and the oxides of nitrogen by the permanganate method +described under nitro-glycerine. Now determine the total acidity of the +mixture by means of a tenth normal solution of sodium hydrate, and +calculate it as nitric acid (HNO_{3}), then determine the nitric acid by +means of Lunge nitrometer, and subtract percentage found from total +acidity, and calculate the difference into sulphuric acid, thus:-- + +Total acidity equals 97.46 per cent.--11.07 per cent. HNO_{3} = 86.39 per +cent., then (86.39 x 49)/63 = 67.20 per cent. H_{2}SO_{4}. + +Then analysis of sample will be:-- + + _ +Sulphuric acid = 67.20 per cent. | +Nitric acid = 11.07 " |- Specific gravity = 1.7075. +Water = 12.73 " _| + +This method is accurate enough for general use in the nitric acid factory. +The acid mixture may be taken by volume for determining nitric oxide in +nitrometer. Two c.c. is a convenient quantity in the above case, then 2 x +1.7075 (specific gravity) = 3.414 grms. taken, gave 145 c.c. NO (barometer += 748 mm, and temperature = 15 deg.C.) equals 134.9 c.c. (corr.) and as 1 c.c. +NO = .0282 grm. HNO_{3} 135 x .0282 = .378 grm. = 11.07 per cent. nitric +acid. + +~Sodium Nitrate.~ Determine moisture and chlorine by the usual methods, +and the total, NaNO_{3}, by means of nitrometer--0.45 grm. is a very +convenient quantity to work on (gives about 123 c.c. gas); grind very +fine, and dissolve in a very little hot water in the cup of the +nitrometer; use about 15 c.c. concentrated H_{2}SO_{4}. One cubic cent. of +NO equals .003805 grm. of NaNO_{3}. The insoluble matter, both organic and +inorganic, should also be determined, also sulphate of soda and lime +tested for. + +~Analysis of Mercury Fulminate (Divers and Kawakita's Method).~--A weighed +quantity of mercury fulminate is added to excess, but measured quantity of +fuming hydrochloric acid contained in a retort connected with a receiver +holding water. After heating for some time, the contents of the retort and +receiver are mixed and diluted, and the mercury is precipitated by +hydrogen sulphide. By warming and exposure to the air in open vessels the +hydrogen sulphide is for the most part dissipated. The solution is then +titrated with potassium hydroxide (KOH), as well as another quantity of +hydrochloric acid, equal to that used with the fulminate. As the mercury +chloride is reconverted into hydrochloric acid by the hydrogen sulphide, +and as the hydroxylamine does not neutralise to litmus the hydrochloric +acid combined with it, there is an equal amount of hydrochloric acid free +or available in the two solutions. Any excess of acid in the one which has +received the fulminate will therefore be due to the formic acid generated +from the fulminate. Dr. Divers and M. Kawakita, working by this method, +have obtained 31.31 per cent. formic acid, instead of 32.40 required by +theory. (_Jour. Chem. Soc._, p. 17, 1884.) + +Divers and Kawakita proceed thus: 2.351 grms. dissolved, as already +described, in HCl, and afterwards diluted, gave mercury sulphide equal to +70.40 per cent. mercury. The same solution, after removal of mercury, +titrated by iodine for hydroxylamine, gave nitrogen equal to 9.85 per +cent., and when evaporated with hydroxyl ammonium chloride equal to 9.55 +per cent. A solution of 2.6665 grms. fulminate in HCl of known amount, +after removal of mercury by hydrogen sulphide, gave by titration with +potassium hydrate, formic acid equal to 8.17 per cent. of carbon. +Collecting and comparing with calculation from formula we get-- + + Calc. I. II. III. + +Mercury 70.42 70.40 ... ... +Nitrogen 9.86 9.85 9.55 ... +Carbon 8.45 ... ... 8.17 +Oxygen 11.27 ... ... ... + _______ + + 100.00 + +~The Analysis of Cap Composition.~--Messrs F.W. Jones and F.A. Willcox +(_Chem. News_, Dec. 11, 1896) have proposed the following process for the +analysis of this substance:--Cap composition usually consists of the +ingredients--potassium chlorate, antimony sulphide, and mercury fulminate, +and to estimate these substances in the presence of each other by ordinary +analytical methods is a difficult process. Since the separation of +antimony sulphide and mercury fulminate in the presence of potassium +chlorate necessitates the treatment of the mixture with hydrochloric acid, +and this produces an evolution of hydrogen sulphide from the sulphide, and +a consequent precipitation of sulphur; and potassium chlorate cannot be +separated from the other ingredients by treatment with water, owing to the +appreciable solubility of mercury fulminate in cold water. + +In the course of some experiments on the solubility of mercury fulminate +Messrs Jones and Willcox observed that this body was readily soluble in +acetone and other ethereal solvents when they were saturated with ammonia +gas, and that chlorate of potash and sulphide of antimony were insoluble +in pure acetone saturated with ammonia; these observations at once +afforded a simple method of separating the three ingredients of cap +composition. By employing this solution of acetone and ammonia an analysis +can be made in a comparatively short time, and yields results of +sufficient accuracy for all technical purposes. The following are the +details of the process:-- + +A tared filter paper is placed in a funnel to the neck of which has been +fitted a piece of rubber tubing provided with a clip. The paper is +moistened with a solution of acetone and ammonia, the cap composition is +weighed off directly on to the filter paper and is then covered with the +solution of acetone and ammonia and allowed to stand thirty-four hours. It +is then washed repeatedly with the same solution until the washings give +no coloration with ammonium sulphide, and afterwards washed with acetone +until washings give no residue on evaporation dried and weighed. The paper +is again put in the funnel and washed with water until free from potassium +chlorate, dried and weighed. + +If _c_ = weight of composition taken, + _d_ = " " filter paper, + _a_ = " after first extraction, + _b_ = " " second extraction, + then _c+d-a_ = weight of fulminate, + _c+d-a-b_ = " " KClO_{3}, + _b-d_ = " " sulphide of antimony. + +The composition should be finely ground in an agate mortar. + +The results of the analysis by this method of two mixtures of known +composition are given below-- + + ________________________________________________________________________ +| | | | +| | A | B | +| | | | +| | Percentage | Percentage | Percentage | Percentage | +| | Taken. | Found. | Taken. | Found. | +|____________________|____________|____________|____________|____________| +| | | | | | +| Antimony Sulphide | 36.47 | 36.25 | 37.34 | 37.22 | +| Potassium Chlorate | 33.25 | 33.71 | 46.03 | 46.43 | +| Mercury Fulminate | 30.27 | 30.02 | 16.61 | 16.34 | +|____________________|____________|____________|____________|____________| + +Dr. H.W. Brownsdon's (_Jour. Soc. Chem. Ind._, xxiv., April 1905) process +is as follows:--The cap composition is removed by squeezing the cap with +pliers, while held over a porcelain basin of about 200 c.c. capacity, and +removing the loosened foil and broken composition by means of a pointed +wooden chip. Composition adhering to the shell or foil is loosened by +alcohol, and washed into the dish by means of alcohol in a small wash +bottle. The shell and foil are put to one side and subsequently weighed +when dry. The composition in the dish is broken down quite fine with a +flat-headed glass rod, and the alcohol evaporated on the water bath till +the residue is moist, but not quite dry, 25 c.c. of water are then added, +and the composition well stirred from the bottom. After the addition of +0.5 grm. of pure sodium, thiosulphate, the contents of the dish, is well +stirred for two and a half minutes. One drop of methyl orange is then +added, and the solution titrated with N/20 sulphuric acid, which has been +standardised against weighings of 0.05-0.1 grm. fulminate to which 25 c.c. +of water is added in a porcelain dish, then 0.5 grm. of thiosulphate, and +after stirring for two and a half minutes, titrated with N/20 sulphuric +acid. The small amount of antimony sulphide present does not interfere +with the recognition of the end point. After titration, the solution is +filtered through a small 5-1/2 cm. filter paper, which retains the +antimony sulphide. The filter paper containing the Sb_{2}S_{3} is well +washed and then transferred to a large 6 by 1 test tube. Five c.c. of +strong hydrochloric acid are added, and the contents of the tube boiled +gently for a few seconds until the sulphide is dissolved and all the +H_{2}S driven off or decomposed: 2-3 c.c. of a saturated solution of +tartaric acid are added, and the contents of the tube washed into a 250 +c.c. Erlenmeyer flask. The solution is then nearly neutralised with sodium +carbonate, excess of bi-carbonate added, and after the addition of some +starch solution titrated with N/20 iodine solution. This method for small +quantities of stibnite is both quick and accurate, the error being about ++-0.0003 grm. Sb_{2}S_{3} at the outside. + +The tendency of this method is to give slightly low figures for the +fulminate, but since these are uniform within a negligible error, it does +not affect the value of the results as a criterion of uniformity. The +following test results were obtained by Dr Brownsdon:-- + + ____________________________________________________________ +| | | | +| Fulminate Taken. | Fulminate Found. | Error. | +| Grm. | Grm. | Grm. | +| | | | +| 0.0086 | 0.0083 | -0.0003 | +| 0.0082 | 0.0081 | -0.0001 | +| 0.0074 | 0.0071 | -0.0003 | +| 0.0068 | 0.0066 | -0.0002 | +|____________________|___________________|___________________| +| | | | +| Stibnite Taken. |Sb_{2}S_{3}, Found.| Error. | +| Grm. | Grm. | Grm. | +| | | | +| 0.0085 | 0.0084 | -0.0001 | +| 0.0098 | 0.0099 | +0.0001 | +| 0.0160 | 0.0157 | -0.0003 | +| 0.0099 | 0.0100 | +0.0001 | +|____________________|___________________|___________________| + +TABLE FOR CORRECTION OF VOLUMES OF GASES FOR TEMPERATURE, GIVING THE +DIVISOR FOR THE FORMULA. + +V_{1} = V x B/(760 x (1 + dt)) (d = 0.003665) 1 + dt from 0 deg. to 30 deg. C. + +___________________________________________________________ + | | | | | + t. | 760x(1+dt). | t. | 760x(1+dt). | t. | 760x(1+dt). +_____|_____________|_____|_____________|_____|_____________ + | | | | | + deg.C. | | deg.C. | | deg.C. | + 0.0 | 750.000 | 1.7 | 764.7352 | 3.4 | 769.4704 + .1 | 760.2785 | .8 | 765.0137 | .5 | 769.7489 + .2 | 760.5571 | .9 | 765.2923 | .6 | 770.0274 + .3 | 760.8356 | 2.0 | 765.5708 | .7 | 770.3060 + .4 | 761.1142 | .1 | 765.8493 | .8 | 770.5845 + .5 | 761.3927 | .2 | 766.1279 | .9 | 770.8631 + .6 | 761.6712 | .3 | 766.4064 | 4.0 | 771.1416 + .7 | 761.9498 | .4 | 766.6850 | .1 | 771.4201 + .8 | 762.2283 | .5 | 766.9635 | .2 | 771.6987 + .9 | 762.5069 | .6 | 767.2420 | .3 | 771.9772 + 1.0 | 762.7854 | .7 | 767.5206 | .4 | 772.2558 + .1 | 763.0639 | .8 | 767.7991 | .5 | 772.5343 + .2 | 763.3425 | .9 | 768.0777 | .6 | 772.8128 + .3 | 763.6210 | 3.0 | 768.3562 | .7 | 773.0914 + .4 | 763.8996 | .1 | 768.6347 | .8 | 773.3699 + .5 | 764.1781 | .2 | 768.9133 | .9 | 773.6485 + .6 | 764.4566 | .3 | 769.1918 | 5.0 | 773.9270 +_____|_____________|_____|_____________|_____|_____________ +___________________________________________________________ + | | | | | + t. | 760x(1+dt). | t. | 760x(1+dt). | t. | 760x(1+dt). +_____|_____________|_____|_____________|_____|_____________ + | | | | | + deg.C. | | deg.C. | | deg.C. | + 5.1 | 774.2055 | .9 | 787.5755 | .7 | 800.9454 + .2 | 774.4841 |10.0 | 787.8540 | .8 | 801.2239 + .3 | 774.7626 | .1 | 788.1325 | .9 | 801.5025 + .4 | 775.0412 | .2 | 788.4111 |15.0 | 801.7810 + .5 | 775.3197 | .3 | 788.6896 | .1 | 802.0595 + .6 | 775.5982 | .4 | 788.9682 | .2 | 802.3381 + .7 | 775.8768 | .5 | 789.2467 | .3 | 802.6166 + .8 | 776.1553 | .6 | 789.5252 | .4 | 802.8952 + .9 | 776.4339 | .7 | 789.8038 | .5 | 803.1737 + 6.0 | 776.7124 | .8 | 790.0823 | .6 | 803.4522 + .1 | 776.9909 | .9 | 790.3609 | .7 | 803.7308 + .2 | 777.2695 |11.0 | 790.6394 | .8 | 804.0093 + .3 | 777.5480 | .1 | 790.9179 | .9 | 804.2879 + .4 | 777.8266 | .2 | 791.1965 |16.0 | 804.5664 + .5 | 778.1051 | .3 | 791.4750 | .1 | 804.8449 + .6 | 778.3836 | .4 | 791.7536 | .2 | 805.1235 + .7 | 778.6622 | .5 | 792.0321 | .3 | 805.4020 + .8 | 778.9407 | .6 | 792.3106 | .4 | 805.6806 + .9 | 779.2193 | .7 | 792.5892 | .5 | 805.9591 + 7.0 | 779.4978 | .8 | 792.8677 | .6 | 806.2376 + .1 | 779.7763 | .9 | 793.1463 | .7 | 806.5162 + .2 | 780.0549 |12.0 | 793.4248 | .8 | 806.7947 + .3 | 780.3334 | .1 | 793.7033 | .9 | 807.0733 + .4 | 780.6120 | .2 | 793.9819 |17.0 | 807.3518 + .5 | 780.8905 | .3 | 794.2604 | .1 | 807.6303 + .6 | 781.1690 | .4 | 794.5390 | .2 | 807.9089 + .7 | 781.4476 | .5 | 794.8175 | .3 | 808.1874 + .8 | 781.7261 | .6 | 795.0960 | .4 | 808.4660 + .9 | 782.0047 | .7 | 795.3746 | .5 | 808.7445 + 8.0 | 782.2832 | .8 | 795.6531 | .6 | 809.0230 + .1 | 782.5617 | .9 | 795.9317 | .7 | 809.3016 + .2 | 782.8403 |13.0 | 796.2102 | .8 | 809.5801 + .3 | 783.1188 | .1 | 796.4887 | .9 | 809.8587 + .4 | 783.3974 | .2 | 796.7673 |18.0 | 810.1372 + .5 | 783.6959 | .3 | 797.0458 | .1 | 810.4175 + .6 | 783.9544 | .4 | 797.3244 | .2 | 810.6943 + .7 | 784.2330 | .5 | 797.6029 | .3 | 810.9728 + .8 | 784.5115 | .6 | 797.8814 | .4 | 811.2514 + .9 | 784.7901 | .7 | 798.1600 | .5 | 811.5299 + 9.0 | 785.0686 | .8 | 798.4385 | .6 | 811.8084 + .1 | 785.3471 | .9 | 798.7171 | .7 | 812.0870 + .2 | 785.6257 |14.0 | 798.9956 | .8 | 812.3655 + .3 | 785.9042 | .1 | 799.2741 | .9 | 812.6441 + .4 | 786.1828 | .2 | 799.5527 |19.0 | 812.9226 + .5 | 786.4613 | .3 | 799.8312 | .1 | 813.2011 + .6 | 786.7398 | .4 | 800.1098 | .2 | 813.4797 + .7 | 787.0184 | .5 | 800.3883 | .3 | 813.7582 + .8 | 787.2969 | .6 | 800.6668 | .4 | 814.0368 +_____|_____________|_____|_____________|_____|_____________ +___________________________________________________________ + | | | | | + t. | 760x(1+dt). | t. | 760x(1+dt). | t. | 760x(1+dt). +_____|_____________|_____|_____________|_____|_____________ + | | | | | + deg.C. | | deg.C. | | deg.C. | +19.5 | 814.3153 |23.0 | 824.0642 | .5 | 833.8131 + .6 | 814.5938 | .1 | 824.3427 | .6 | 834.0916 + .7 | 814.8724 | .2 | 824.6213 | .7 | 834.3702 + .8 | 815.1500 | .3 | 824.8998 | .8 | 834.6487 + .9 | 815.4925 | .4 | 825.1784 | .9 | 834.9273 +20.0 | 815.7080 | .5 | 825.4569 |27.0 | 835.2058 + .1 | 815.9865 | .6 | 825.7354 | .1 | 835.4843 + .2 | 816.2651 | .7 | 826.0140 | .2 | 835.7629 + .3 | 816.5436 | .8 | 826.2925 | .3 | 836.0414 + .4 | 816.8222 | .9 | 826.5711 | .4 | 836.3200 + .5 | 817.1007 |24.0 | 826.8496 | .5 | 836.5985 + .6 | 817.3792 | .1 | 827.1281 | .6 | 836.8770 + .7 | 817.6578 | .2 | 827.4067 | .7 | 837.1556 + .8 | 817.9363 | .3 | 827.6852 | .8 | 837.4341 + .9 | 818.2149 | .4 | 827.9638 | .9 | 837.7127 +21.0 | 818.4934 | .5 | 828.2423 |28.0 | 837.9912 + .1 | 818.7719 | .6 | 828.5208 | .1 | 838.2697 + .2 | 819.0505 | .7 | 828.7994 | .2 | 838.5483 + .3 | 819.3290 | .8 | 829.0779 | .3 | 838.8268 + .4 | 819.6076 | .9 | 829.3565 | .4 | 839.1054 + .5 | 819.8861 |25.0 | 829.6350 | .5 | 839.3839 + .6 | 820.1646 | .1 | 829.9135 | .6 | 839.6624 + .7 | 820.4432 | .2 | 830.1921 | .7 | 839.9410 + .8 | 820.7217 | .3 | 830.4706 | .8 | 840.2195 + .9 | 821.0003 | .4 | 830.7492 | .9 | 840.4981 +22.0 | 821.2788 | .5 | 831.0277 |29.0 | 840.7766 + .1 | 821.5573 | .6 | 831.3062 | .1 | 841.0551 + .2 | 821.8859 | .7 | 831.5848 | .2 | 841.3337 + .3 | 822.1144 | .8 | 831.8633 | .3 | 841.6122 + .4 | 822.3930 | .9 | 832.1419 | .4 | 841.8908 + .5 | 822.6715 |26.0 | 832.4204 | .5 | 842.1693 + .6 | 822.9500 | .1 | 832.6989 | .6 | 842.4478 + .7 | 823.2286 | .2 | 832.9775 | .7 | 842.7264 + .8 | 823.5071 | .3 | 833.2560 | .8 | 843.0049 + .9 | 823.7857 | .4 | 833.5346 | .9 | 843.2835 + | | | |30.0 | 843.5620 +_____|_____________|_____|_____________|_____|_____________ + + + + +CHAPTER VIII. + +_FIRING POINT OF EXPLOSIVES, HEAT TESTS, &c._ + +Horsley's Apparatus--Table of Firing points--The Government Heat-Test +Apparatus for Dynamites--Nitro-Glycerine, Nitro-Cotton, and Smokeless +Powders--Liquefaction and Exudation Tests--Page's Regulator for Heat-Test +Apparatus--Specific Gravities of Explosives--Table of Temperature of +Detonation, Sensitiveness, &c. + + +~The Firing Point of Explosives.~--The firing point of an explosive may be +determined as follows:--A copper dish, about 3 inches deep, and 6 or more +wide, and fitted with a lid, also of copper, is required. The lid contains +several small holes, into each of which is soldered a thick copper tube +about 5 mm. in diameter, and 3 inches long, with a rather larger one in +the centre in which to place a thermometer. The dish is filled with Rose's +metal, or paraffin, according to the probable temperature required. The +firing point is then taken thus:--After putting a little piece of asbestos +felt at the bottom of the centre tube, the thermometer is inserted, and a +small quantity of the explosive to be tested is placed in the other holes; +the lid is then placed on the dish containing the melted paraffin or +metal, in such a way that the copper tubes dip below the surface of the +liquid; the temperature of the bath is now raised until the explosive +fires, and the temperature noted. The initial temperature should also be +noted. + +THE FIRING POINT OF VARIOUS EXPLOSIVES (by C. E. Munroe). +(Horsley's Apparatus used.) + +_____________________________________________________________________ + | + | deg.C. +Nitro-glycerine, 5 years old (a single drop taken) | 203-205 +Gun-cotton (compressed military cotton, sp. gr. 1.5) | 192-201 +Air-dried gun-cotton, stored for 4 years | 179-187 +Ditto, stored for 1 year | 187-189 +Air-dried collodion-cotton, long staple "Red Island | + cotton," 3 years old | 186-191 +Air-dried collodion, 3 years old, stored wet | 197-199 +Hydro-nitro-cellulose | 201-213 +Kieselguhr dynamite, No. 1 | 197-200 +Explosive gelatine | 203-209 +Mercury fulminate | 175-181 +Gunpowder (shell) | 278-287 +Hill's picric powder (shells) Been in store 10 years. | 273-283 +Ditto (musket) Composed of-- | 282-290 + Ammonium picrate 42.18 % | + Potassium picrate 53.79 " | + Charcoal (alder) 3.85 " | + ________ | + | + 99.82 | +Forcite, No. 1 | 187-200 +Atlas powder (75% NG) | 175-185 +Emmensite, No. 1 Sample had been stored in | 167-184 + magazine for some months in | + a wooden box. | + " No. 2 Stored in tin case. | 165-177 + " No. 5 " " | 205-217 +__________________________________________________________|__________ + | | + | deg.C. | +Powder used in Chassepot rifle | 191 | By Leygue & Champion. +French gunpowder | 295 | " " +Rifle powder (picrate) | 358 | " " +Cannon | 380 | " " +__________________________________|_________|________________________ + +Horsley's apparatus consists of an iron stand with a ring support, holding +a hemispherical iron vessel or bath in which solid paraffin is put. Above +this is another movable support, from which a thermometer is suspended, +and so adjusted that its bulb is immersed in the material contained in the +iron vessel. A thin copper cartridge-case, 5/8 inch in diameter and +1-15/16 inch long, is suspended over the bath by means of a triangle, so +that the end of the case is just 1 inch below the surface of the molten +material. On beginning the experiment of determining the firing point of +any explosive, the material in the bath is heated to just above the +melting point; the thermometer is inserted in it, and a minute quantity of +the explosive is placed in the bottom of the cartridge-case. The initial +temperature is noted, and then the cartridge-case containing the explosive +is inserted in the bath. The temperature is quickly raised until the +contents of the cartridge-case flash off or explode, when the temperature +is noted as the _firing point_. + +[Illustration: FIG. 46.--HEAT TEST APPARATUS.] + +Professor C.E. Munroe, of the U.S. Torpedo Station, has determined the +firing point of several explosives by means of this apparatus. + +~The Government Heat Test (Explosives Act, 1875): Apparatus required.~--A +water bath, consisting of a spherical copper vessel _(a)_, Fig. 46, of +about 8 inches diameter, and with an aperture of about 5 inches; the bath +is filled with water to within a quarter of an inch of the edge. It has a +loose cover of sheet copper about 6 inches in diameter _(b)_ and rests on +a tripod stand about 14 inches high _(c)_, which is covered with coarse +wire gauze _(e)_, and is surrounded with a screen of thin sheet copper +_(d)_. Within the latter is placed an argand burner _(f)_ with glass +chimney. The cover _(b)_ has four holes arranged, as seen in Fig. II., No. +4 to contain a Page's[A] or Scheibler's regulator, No. 3 the thermometer, +Nos. 1 and 2 the test tubes containing the explosive to be tested. Around +the holes 1 and 2 on the under side of the cover are soldered three pieces +of brass wire with points slightly converging (Fig. III.); these act as +springs, and allow the test tubes to be easily placed in position and +removed. + +[Footnote A: See _Chem. Soc. Jour._, 1876, i. 24. F.J.M. Page.] + +~Test Tubes~, from 5-1/4 to 5-1/2 inches long, and of such a diameter that +they will hold from 20 to 22 cubic centimetres of water when filled to a +height of 5 inches; rather thick glass is preferable. Indiarubber +stoppers, fitting the test tubes, and carrying an arrangement for holding +the test papers, viz., a narrow glass tube passing through the centre of +the stopper, and terminating in a platinum wire hook. A glass rod drawn +out and the end turned up to form a hook is better. + +~The Thermometer~ should have a range from 30 deg. to 212 deg. F., or from 1 deg. to +100 deg. C. A minute clock is useful. + +~Test Paper.~--The test paper is prepared as follows:--45 grains (2.9 +grms.) of white maize starch (corn flour), previously washed with cold +water, are added to 8-1/2 oz. of water. The mixture is stirred, heated to +boiling, and kept gently boiling for ten minutes; 15 grains (1 grm.) of +pure potassium iodide (previously recrystallised from alcohol, absolutely +necessary) are dissolved in 8-1/2 oz. of distilled water. The two +solutions are thoroughly mixed and allowed to get cold. Strips or sheets +of white English filter paper, previously washed with water and re-dried, +are dipped into the solution thus prepared, and allowed to remain in it +for not less than ten seconds; they are then allowed to drain and dry in a +place free from laboratory fumes and dust. The upper and lower margins of +the strips or sheets are cut off, and the paper is preserved in well- +stoppered or corked bottles, and in the dark. The dimensions of the pieces +of test paper used are about 4/10 inch by 8/10 inch (10 mm. by 20 mm.).[A] + +[Footnote A: When the paper is freshly prepared, and as long as it remains +in good condition, a drop of diluted acetic acid put on the paper with a +glass rod produces no coloration. In process of time it will become +brownish, when treated with the acid, especially if it has been exposed to +sunlight. It is then not fit for use.] + +In Germany zinc-iodide starch paper is used, which is considered to be +more sensitive than potassium iodide. + +~Standard Tint Paper.~--A solution of caramel in water is made of such +concentration that when diluted one hundred times (10 c.c. made up to 1 +litre) the tint of this diluted solution equals the tint produced by the +Nessler test in 100 c.c. water containing .000075 grm. of ammonia, or +.00023505 grm. AmCl. With this caramel solution lines are drawn on strips +of white filter paper (previously well washed with distilled water, to +remove traces of bleaching matter, and dried) by means of a quill pen. +When the marks thus produced are dry, the paper is cut into pieces of the +same size as the test paper previously described, in such a way that each +piece has a brown line across it near the middle of its length, and only +such strips are preserved in which the brown line has a breadth varying +from 1\2 mm. to 1 mm. (1/50 of an inch to 1/25 of an inch). + +~Testing Dynamite, Blasting Gelatine, and Gelatine Dynamite.~--Nitro- +glycerine preparations, from which the nitro-glycerine can be extracted in +the manner described below, must satisfy the following test, otherwise +they will not be considered as manufactured with "thoroughly purified +nitro-glycerine," viz., fifteen minutes at 160 deg. F. (72 deg. C.). + +~Apparatus required.~--A funnel 2 inches across (_d_), a cylindrical +measure divided into grains (_e_), Fig. 47. + +~Mode of Operation.~--About 300 (19.4 grms.) to 400 grains (26 grms.) of +dynamite (_b_), finely divided, are placed in the funnel, which is loosely +plugged by freshly ignited asbestos (_a_). The surface is smoothed by +means of a flat-headed glass rod or stopper, and some clean washed and +dried kieselguhr (_c_) is spread over it to the depth of about 1/8 inch. +Water is then poured on from a wash bottle, and when the first portion has +been soaked up more is added; this is repeated until sufficient nitro- +glycerine has collected in the graduated measure (_e_). If any water +should have passed through, it must be removed from the nitro-glycerine by +filter paper, or the nitro-glycerine may be filtered. + +[Illustration: FIG. 47.--APPARATUS FOR SEPARATING THE NlTRO-GLYCERINE FROM +DYNAMITE.] + +[Illustration: FIG. 48.--TEST TUBE ARRANGED FOR HEAT TEST.] + +~Application of Test.~--The thermometer is fixed so as to be inserted +through the lid of the water bath into the water, which is maintained at +160 deg. F. (72 deg. C.), to a depth of 2-3/4 inches. Fifty grains (= 3.29 grms.) +of nitro-glycerine to be tested are weighed into the test tube, in such a +way as not to soil the sides of the tube (use a pipette). A test paper is +fixed on the hook of the glass rod, so that when inserted into the tube it +will be in a vertical position. A sufficient amount of a mixture of half +distilled water and half glycerine, to moisten the upper half of the +paper, is now applied to the upper edge of the test paper by means of a +glass rod or camel's hair pencil; the cork carrying the rod and paper is +fixed into the test tube, and the position of the paper adjusted so that +its lower edge is about half way down the tube; the latter is then +inserted through one of the holes in the cover to such a depth that the +lower margin of the moistened part of the paper is about 5/8 inch above +the surface cover. The test is complete when the faint brown line, which +after a time makes its appearance at the line of boundary between the dry +and moist part of the paper, equals in tint the brown line of the standard +tint paper. + +~Blasting Gelatine, Gelatine Dynamite, Gelignite, &c.~--Fifty grains (= +3.29 grms.) of blasting gelatine are intimately mixed with 100 grains (= +6.5 grms.) of French chalk. This is done by carefully working the two +materials together with a wooden pestle in a wooden mortar. The mixture is +then gradually introduced into the test tube, with the aid of gentle +tapping upon the table between the introduction of successive portions of +the mixture into the tube, so that when the tube contains all the mixture +it shall be filled to the extent of 1-3/4 inch of its height. The test +paper is then inserted as above described for nitro-glycerine. The sample +tested must stand a temperature of 160 deg. F. for a period of ten minutes +before producing a discoloration of the test paper corresponding in tint +to the standard paper. + +_N.B._--Non-gelatinised nitro-glycerine preparations, from which the +nitro-glycerine cannot be expelled by water, are tested without any +previous separation of the ingredients, the temperature being as above +160 deg. F., and the time being seven minutes. + +~Gun-Cotton, Schultze Gunpowder, E.C. Powder, &c.: A. Compressed Gun- +Cotton.~--Sufficient material to serve for two or more tests is removed +from the centre of the cartridge by gentle scraping, and if necessary, +further reduced by rubbing between the fingers. The fine powder thus +produced is spread out in a thin layer upon a paper tray 6 inches by 4-1/2 +inches, which is then placed inside a water oven, kept as nearly as +possible at 120 deg. F. (49 deg. C.). The wire gauze shelves of the oven should be +about 3 inches apart. The sample is allowed to remain at rest for fifteen +minutes in the oven, the door of which is left wide open. After the lapse +of fifteen minutes the tray is removed and exposed to the air of the room +for two hours, the sample being at some point within that time rubbed upon +the tray with the hand, in order to reduce it to a fine and uniform state +of division. + +The heat test is performed as before, except that the temperature of the +bath is kept at 170 deg. F. (66 deg. C.), and regulator set to maintain that +temperature. Twenty grains (1.296 grm.) are used, placed in the test tube, +gently pressed down until it occupies a space of as nearly as possible +1-5/10 inch in the test tube of dimensions previously specified. The fine +cotton adhering to the sides of the tube can be removed by a clean cloth +or silk handkerchief. The paper is moistened by touching the upper edge +with a drop of the 50 per cent. glycerine solution, the tube inserted in +the bath to a depth of 2-1/2 inches, measured from the cover, the +regulator and thermometer being inserted to the same depth. The test paper +is to be kept near the top of the test tube, but clear of the cork, until +the tube has been immersed for about five minutes. A ring of moisture will +about this time be deposited upon the sides of the test tube, a little +above the cover of the bath. The glass rod must then be lowered until the +lower margin of the moistened part of the paper is on a level with the +bottom of the ring of moisture in the tube. The paper is now closely +watched, The test is complete when a very faint brown coloration makes its +appearance at the line of boundary between the dry and moist parts of the +paper. It must stand the test for not less than ten minutes at 170 deg. F. +(The time is reckoned from the first insertion of the tube in the bath +until the appearance of a discoloration of the test paper.) + +~B. Schultze Powder, E.C. Powder, Collodion-Cotton, &c.~--The sample is +dried in the oven as above for fifteen minutes, and exposed for two hours +to the air. The test as above for compressed gun-cotton is then applied. + +~C. Cordite~ must stand a temperature of 180 deg. F. for fifteen minutes. The +sample is prepared as follows:--Pieces half an inch long are cut from one +end of every stick selected for the test: in the case of the thicker +cordites, each piece so cut is further subdivided into about four +portions. These cut pieces are then passed once through the mill, the +first portion of material which passes through being rejected on account +of the possible presence of foreign matter from the mill. The ground +material is put on the top sieve of the nest of sieves, and sifted. That +portion which has passed through the top sieve and been stopped by the +second is taken for the test. If the mill is properly set, the greater +portion of the ground material will be of the proper size. If the volatile +matter in the explosive exceeds 0.5 per cent., the sifted material should +be dried at a temperature not exceeding 140 deg. F, until the proportion does +not exceed 0.5 per cent. After each sample has been ground, the mill must +be taken to pieces and carefully cleaned. The sieves used consist of a +nest of two sieves with holes drilled in sheet copper. The holes in the +top sieve have a diameter = 14 B.W.G., those in the second = 21 B.W.G. + +If too hard for the mill, the cordite may be softened by exposure to the +vapour of acetone,[A] or reduced, to the necessary degree of subdivision +by means of a sharp moderately-coarse rasp. Should it have become too soft +in the acetone vapour for the mill, it should be cut up into small pieces, +which may be brought to any desired degree of hardness by simple exposure +to air. Explosives which consist partly of gelatinised collodion-cotton, +and partly of ungelatinised gun-cotton, are best reduced to powder by a +rasp, or softened by exposure to mixed ether and alcohol vapour at a +temperature of 40 deg. F. to 100 deg. F. + +[Footnote A: Mr W. Cullen _(Jour. Soc. Chem. Ind._, Jan. 31, 1901) says:-- +"Undoubtedly the advent of the horny smokeless powders of modern times has +made it a little difficult to give the test the same scope as it had when +first introduced." As a rule a simple explanation can be found for every +apparently abnormal result, and in the accidental retention of a portion +of the solvent used in the manufacture, will frequently be found an +explanation of the trouble experienced.] + +~Ballistite.~--In the case of ballistite the treatment is the same, except +that when it is in a very finely granulated condition it need not be cut +up. + +~Guttmann's Heat Test.~--This test was proposed by Mr Oscar Guttmann in a +paper read before the Society of Chemical Industry (vol. xvi., 1897), in +the place of the potassium iodide starch paper used in the Abel test. The +filter paper used is wetted with a solution of diphenylamine[A] in +sulphuric acid. The solution is prepared as follows:--Take 0.100 grm. of +diphenylamine crystals, put them in a wide-necked flask with a ground +stopper, add 50 c.c. of dilute sulphuric acid (10 c.c. of concentrated +sulphuric acid to 40 c.c. of water), and put the flask in a water bath at +between 50 deg. and 55 deg. C. At this temperature the diphenylamine will melt, +and at once dissolve in the sulphuric acid, when the flask should be taken +out, well shaken, and allowed to cool. After cooling, add 50 c.c. of +Price's double distilled glycerine, shake well, and keep the solution in a +dark place. The test has to be applied in the following way:--The +explosives that have to be tested are finely subdivided, gun-cotton, +nitro-glycerine, dynamite, blasting gelatine, &c., in the same way as at +present directed by the Home Office regulations. Smokeless powders are all +to be ground in a bell-shaped coffee mill as finely as possible, and +sifted as hitherto. 1.5 grm. of the explosive (from the second sieve in +the case of smokeless powder) is to be weighed off and put into a test +tube as hitherto used. Strips of well-washed filter paper, 25 mm. wide, +are to be hung on a hooked glass rod as usual. A drop of the diphenylamine +solution is taken up by means of a clean glass rod, and the upper corners +of the filter paper are touched with it, so that when the two drops run +together about a quarter of the filter paper is moist. This is then put +into the test tube, and this again into the water bath, which has been +heated to 70 deg. C. The heat test reaction should not show in a shorter time +than fifteen minutes. It will begin by the moist part of the paper +acquiring a greenish yellow colour, and from this moment the paper should +be carefully watched. After one or two minutes a dark blue mark will +suddenly appear on the dividing line between the wet and dry part of the +filter paper, and this is the point that should be taken. + +[Footnote A: Dr G. Spica (_Rivista_, Aug. 1897) proposes to use +hydrochloride of meta-phenylenediamine.] + +~Exudation and Liquefaction Test for Blasting Gelatine, Gelatine Dynamite, +&c.~--A cylinder of blasting gelatine, &c., is to be cut from the +cartridge to be tested, the length of the cylinder to be equal to its +diameter, and the ends being cut flat. The cylinder is to be placed on end +on a flat surface without any wrapper, and secured by a pin passing +vertically through its centre. In this condition the cylinder is to be +exposed for 144 consecutive hours (six days and nights) to a temperature +ranging from 85 deg. to 90 deg. F. (inclusive), and during such exposure the +cylinder shall not diminish in height by more than one-fourth of its +original height, and the upper cut surface shall retain its flatness and +the sharpness of its edge. + +~Exudation Test.~--There shall be no separation from the general mass of +the blasting gelatine or gelatine dynamite of a substance of less +consistency than the bulk of the remaining portion of the material under +any conditions of storage, transport, or use, or when the material is +subjected three times in succession to alternate freezing and thawing, or +when subjected to the liquefaction test before described. + +~Picric Acid.~--The material shall contain not more than 0.3 part of +mineral or non-combustible matter in 100 parts by weight of the material +dried at 160 deg. F. It should not contain more than a minute trace of lead. +One hundred parts of the dry material shall not contain more than 0.3 part +of total (free and combined) sulphuric acid, of which not more than 0.1 +part shall be free sulphuric acid. Its melting point should be between +248 deg. and 253 deg. F. + +~Ammonite, Bellite, Roburite, and Explosives of similar Composition.~-- +These are required to stand the same heat test as compressed +nitro-cellulose, gun-cotton, &c. + +~Chlorate Mixtures.~--The material must not be too sensitive, and must +show no tendency to increase in sensitiveness in keeping. It must contain +nothing liable to reduce the chlorate. Chlorides calculated as potassium +chloride must not exceed 0.25 per cent. The material must contain no free +acid, or substance liable to produce free acid. Explosives of this class +containing nitro-compounds will be subject to the heat test. + +~Page's Regulator.~--The most convenient gas regulator to use in +connection with the heat-test apparatus is the one invented by Prof. +F.J.M. Page, B.Sc.[A] (Fig. 49). It is not affected by variations of the +barometric pressure, and is simple and easy to fit up. It consists of a +thermometer with an elongated glass bulb 5/8 inch diameter and 3 inches +long. The stem of the thermometer is 5 inches long and 1/8 inch to 3/16 +inch internal diameter. One and a half inch from the top of the stem is +fused in at right angles a piece of glass tube, 1 inch long, of the same +diameter as the stem, so as to form a T. A piece of glass tube (A), about +7/16 inch external diameter and 1-1/2 inch long, is fitted at one end with +a short, sound cork (C, Fig. 50). Through the centre of this cork a hole +is bored, so that the stem of the thermometer just fits into it. The other +end of this glass tube is closed by a tightly fitting cork, preferably of +indiarubber (I), which is pierced by a fine bradawl through the centre. +Into the hole thus made is forced a piece of fine glass tube (B) 3 inches +long, and small enough to fit loosely inside the stem of the thermometer. + +[Footnote A: _Chemical Soc. Jour._, 1876, i. 24.] + +The thermometer is filled by pouring in mercury through a small funnel +until the level of the mercury (when the thermometer is at the desired +temperature) is about 1-1/2 inch below the T. The piece of glass tube A, +closed at its upper extremity by the cork I, through which the fine glass +tube B passes into the stem of the thermometer, is now filled by means of +the perforated cork at its lower extremity on the stem of the thermometer. +The gas supply tube is attached to the top of the tube A, the burner to +the T, so that the gas passes in at the top, down the fine tube B, rises +in the space between B and the inside wall of the stem of the thermometer, +and escapes by the T. The regulator is set for any given temperature by +pushing the cork C, and consequently the tubes A and B, which are firmly +attached to it, up or down the stem of the thermometer, until the +regulator just cuts off the gas at the desired temperature. + +[Illustration: FIG. 49.--PAGE'S REGULATOR.] + +[Illustration: FIG. 50.--PAGE'S GAS REGULATOR, SHOWING BYE-PASS AND +CUT-OFF ARRANGEMENT.] + +As soon as the temperature falls, the mercury contracts, and thus opens +the end of the tube B. The gas is thus turned on, and the temperature +rises until the regulator again cuts off the gas. In order to prevent the +possible extinction of the flame by the regulator, the brass tube which +carries the gas to the regulator is connected with the tube which brings +the gas from the regulator to the burner by a small brass tap (Fig. 2). +This tap forms an adjustable bye-pass, and thus a small flame can be kept +burning, even though the regulator be completely shut off. It is obvious +that the quantity of gas supplied through the bye-pass must always be less +than that required to maintain the desired temperature. This regulator, +placed in a beaker of water on a tripod, will maintain the temperature of +the water during four or five hours within 0.2 deg. C., and an air bath during +six weeks within 0.5 deg. C. + +To sum up briefly the method of using the regulator:--Being filled with +mercury to about 1\2 inch below the T, attach the gas supply as in diagram +(Fig. 2), the brass tap being open, and the tube B unclosed by the +mercury. Allow the gas to completely expel the air in the apparatus. Push +down the tube A so that the end of B is well under the surface of the +mercury. Turn off the tap of the bye-pass until the smallest bead of flame +is visible. Raise A and B, and allow the temperature to rise until the +desired point is attained. Then push the tubes A and B slowly down until +the flame is just shut off. The regulator will then keep the temperature +at that point. + +~Will's Test for Nitro-Cellulose.~--The principle of Dr W. Will's test[A] +may be briefly described as follows:--The regularity with which nitro- +cellulose decomposes under conditions admitting of the removal of the +products of decomposition immediately following their formation is a +measure of its stability. As decomposing agent a sufficiently high +temperature (135 deg. C.) is employed, the explosive being kept in a +constantly changing atmosphere of carbon dioxide, heated to the same +temperature: the oxides of nitrogen which result are swept over red-hot +copper, and are then reduced to nitrogen, and finally, the rates of +evolution of nitrogen are measured and compared. Dr Will considers that +the best definition and test of a stable nitro-cellulose is that it should +give off at a high temperature equal quantities of nitrogen in equal +times. For the purposes of manufacture, it is specially important that the +material should be purified to its limit, i.e., the point at which further +washing produces no further change in its speed of decomposition measured +in the manner described. + +[Footnote A: W. Will, _Mitt. a. d. Centrallstelle f. Wissench. Techn. +Untersuchungen Nuo-Babelsberg Berlin_, 1902 [2], 5-24.] + +The sample of gun-cotton (2.5 grms.) is packed into the decomposition tube +15 mm. wide and 10 cm. high, and heated by an oil bath to a constant +temperature, the oxides so produced are forced over ignited copper, where +they are reduced, and the nitrogen retained in the measuring tubes. Care +must be taken that the acid decomposition products do not condense in any +portion of the apparatus. The air in the whole apparatus is first +displaced by a stream of carbon dioxide issuing from a carbon dioxide +generator, or gas-holder, and passing through scrubbers, and this stream +of gas is maintained throughout the whole of the experiment, the gas being +absorbed at the end of the system by strong solution of caustic potash. To +guard against the danger of explosions, which occasionally occur, the +decomposition tube and oil bath are surrounded by a large casing with +walls composed of iron plate and strong glass. + +Dr Will's apparatus has been modified by Dr Robertson,[A] of the Royal +Gunpowder Factory, Waltham Abbey. The form of the apparatus used by him is +shown in Fig. 51. + +~CO_{2} Holders.~--Although objection has been taken to the use of +compressed CO_{2} in steel cylinders on account of the alleged large and +variable amount of air present, it has, nevertheless, been found possible +to obtain this gas with as little as 0.02 per cent. of air. Frequent +estimations of the air present in the CO_{2} of a cylinder show that even +with the commercial article, after the bulk of the CO_{2} has been +removed, the residual gas contains only a very small amount of air, which +decreases in a gradual and perfectly regular manner. For example, one +cylinder which gave 0.03 per cent. of air by volume, after three months' +constant use gave 0.02 per cent. The advantage of using CO_{2} from this +source is obvious when compared with the difficulty of evolving a stream +of gas of constant composition from a Kipps or Finkener apparatus. A +micrometer screw, in addition to the main valve of the CO_{2} cylinder, is +useful for governing the rate of flow. A blank experiment should be made +to ascertain the amount of air in the CO_{2} and the correction made in +the readings afterwards. + +[Footnote A: _Jour. Soc. Chem. Ind._, June 30, 1902, p. 819.] + +[Illustration: Fig 51.--Will's Apparatus for Testing Nitro-cellulose] + +~Measurement of Pressure and Rate of Flow.~--Great attention is paid to +the measurement of the rate of flow of gas, which is arrived at by +counting with a stop-watch the number of bubbles of gas per minute in a +small sulphuric acid wash bottle. A mercury manometer is introduced here, +and is useful for detecting a leak in the apparatus. The rate of flow that +gives the most satisfactory results is 1,000 c.c. per hour. If too rapid +it does not become sufficiently preheated in the glass spiral, and if too +slow there is a more rapid decomposition of the nitro-cellulose by the +oxides of nitrogen which are not removed. + +~Decomposition Tube.~--This is of the form and dimensions given by Dr Will +(15 mm. wide and 10 cm. high), the preheating worm being of the thinnest +hydrometer stem tubing. The ground-in exit tube is kept in position by a +small screw clamp with trunnion bearings. + +~Bath.~--To permit of two experiments being carried on simultaneously, the +bath is adapted for two decomposition tubes, and is on the principle of +Lothar Meyer's air bath, that is, the bath proper filled with a high- +flashing hydrocarbon oil, and fitted with a lid perforated with two +circular holes for the spiral tubes, is surrounded by an asbestos-covered +envelope, in the interior of which circulate the products of combustion of +numerous small gas jets. The stirrer, agitated by a water motor, or, +better still, a hot-air engine, has a series of helical blades curved to +give a thorough mixing to the oil. Great uniformity and constancy of +temperature are thus obtained. The bath is fitted also with a temperature +regulator and thermometer. + +~Reduction Tube~--This is of copper, and consists of two parts, the outer +tube and an inner reaching to nearly the bottom of the former. Into the +inner tube fits a spiral of reduced copper gauze, and into the annular +space between the tubes is fitted a tightly packed reduced copper spiral. +At the bottom the inlet tube dips into a layer of copper oxide asbestos, +on the top of which is a layer of reduced copper asbestos. Through the +indiarubber cork passes a glass tube, which leads the CO_{2} and nitrogen +out of the reduction tube. As the portion of the tube containing the +spirals is heated to redness, water jackets are provided on both inner and +outer tubes to protect the indiarubber cork. + +~Nitrogen Measuring Apparatus.~--The measuring tube with zigzag +arrangement is used, having been found very economical in potash. It is +most convenient to take readings by counterbalancing the column of potash +solution and reading off the volume of gas at atmospheric pressure. For +this purpose the tap immediately in front of the measuring tube is +momentarily closed, this having been proved to be without ill effect on +the progress of the test. In all experiments done by this test the air +correction is subtracted from each reading, and the remainder brought to +milligrams of nitrogen with the usual corrections. As objection has +frequently been taken to the test on the ground of difficulty in +interpreting the results obtained, Dr Robertson made a series of +experiments for the purpose of standardising the test, and at the same +time of arriving at the condition under which it could be applied in the +most sensitive and efficient manner. A variety of nitro-celluloses having +been tested, there were chosen as typical, of stable and unstable +products, service gun-cotton on the one hand, and an experimental gun- +cotton, Z, on the other. The first point brought out by these experiments +was the striking uniformity of service gun-cotton, first in regard to the +rectilinear nature of the curve of evolution of nitrogen, and secondly in +regard to the small range within which a large number of results is +included, 15 samples lying between 6.6 and 8.7 mgms. of nitrogen evolved +in four hours. In the case of service gun-cotton, little difference in the +rate of evolution of nitrogen evolved is obtained on altering the rate of +passage of CO_{2} gas through the wide range of 500 c.c. per hour to 2,500 +c.c. per hour. With Z gun-cotton (see Fig. 52), however, the case is very +different. Operating at a rate of 1,000 c.c. of CO_{2} per hour, a curve +of nitrogen evolution is obtained, which is bent and forms a good +representation of the inherent instability of the material as proved to +exist from other considerations. Operating at the rate of 1,500 c.c. per +hour, as recommended by Dr Will, the evolution of nitrogen is represented +by a straight line, steeper, however, than that of service gun-cotton. The +rate of passage of CO_{2} was therefore chosen at 1,000 c.c. per hour, or +two-thirds of the rate of Dr Will, and this rate, besides possessing the +advantage claimed of rendering diagnostic the manner of nitrogen evolution +in Z gun-cotton, has in other cases been useful in bringing out +relationships, which the higher rate would have entirely masked. + +[Illustration: Fig. 52.--Dr. Robertson's results.] + +[Illustration: Fig. 53.--Service Guncotton for Cordite made at a Private +Factory.] + +Readings are taken thirty minutes from the time the nitro-cellulose is +heated, and are taken at intervals of fifteen minutes for about four +hours; fresh caustic potash is added every thirty minutes or so. It is +convenient to plot the results in curves. The curves given in Fig. 53 are +from gun-cotton manufacturers in England at a private factory. The rate of +evolution of nitrogen is as follows:-- + +In 1 hour. In 2 hours. In 3 hours. In 4 hours. + N. N. N. N. in milligrammes. + 1.25 2.55 4.5 5.75 + 1.5 3.25 5.25 6.75 +These results are very satisfactory, the gun-cotton was of a very good +quality. Several hours are necessary to remove all the air from the +apparatus. Dr Will stated fifteen minutes in his original paper, but this +has not been found sufficient. It has not been satisfactorily proved that +Will's test can be applied to gelatinised nitro-cellulose powders. It is +convenient to plot the results in curves; the nitrogen is generally given +in cubic centimetres or in milligrammes, and readings taken every fifteen +minutes. The steepness of the curve is a measure of the stability of the +nitro-cellulose which is being examined. The steeper the curve the more +nitrogen is evolved per unit of time, and the less stable the nitro- +cellulose. In the case of unstable nitro-celluloses heated under the +conditions described, the separation of nitrogen is much greater at first +than at a later period. If the nitro-cellulose be very unstable, +explosions are produced. If the separation of nitrogen is uniform during +the prolonged heating, then the nitro-cellulose may be regarded as +"normal." If it be desired to determine the absolute amount of nitrogen +separated from a nitro-cellulose, the following conditions must be +observed:--(1.) Accurate weighing of the nitro-cellulose; (2.) +Determination of the amount of air in the CO_{2}, and deduction of this +from the volume of gas obtained; (3.) Reduction of the volume of the gas +to the volume at 0 deg. C. and 760 mm. pressure.[A] + +[Footnote A: See also _Jour. Soc. Chem. Ind._, Dec. 1902, pages 1545-1555, +on the "Stability of Nitro-cellulose" and "Examination of Nitro- +cellulose," Dr Will.] + +~Bergrnann and Junk~[A] describe a test for nitro-cellulose that has been +in use in the Prussian testing station for some years. The apparatus +consists of a closed copper bath provided with a condenser and 10 +countersunk tubes of 20 cm. length. By boiling amyl-alcohol in the bath, +the tubes can be kept at a constant temperature of 132 deg. C. The explosive +to be tested is placed in a glass tube 35 cm. long and 2 cm. wide, having +a ground neck into which an absorption bulb is fitted. The whole apparatus +is surrounded by a shield, in case of explosion. In carrying out the test, +2 grms. of the explosive are placed in the glass tube and well pressed +down. The absorption bulb is half filled with water, and fitted into the +ground neck of the glass tube, which is then placed in one of the tubes in +the bath previously brought to the boiling point (132 deg. C.). The evolved +oxides of nitrogen are absorbed in the water in the bulb, and at the end +of two hours the tubes are removed from the bath, and on cooling, the +water from the bulb flows back and wets the explosive. The contents of the +tube are filtered and washed, the filtrate is oxidised with permanganate, +and the nitrogen determined as nitric oxide by the Schultze-Tieman method. +The authors conclude that a stable gun-cotton does not evolve more than +2.5 c.c. of nitric oxide per grm. on being heated to 132 deg. C. for two +hours, and a stable collodion-cotton not more than 2 c.c. under the same +conditions. The percentage of moisture in the sample to be tested should +be kept as low as possible. A sample of nitro-cellulose containing 1.97% +of moisture gave an evolution of 2.6 c.c. per grm., while the same sample +with 3.4% moisture gave an evolution of over 50 c.c. per grm. Sodium +carbonate added to an unstable nitro-cellulose diminishes the rate of +decomposition, but if sodium carbonate be intimately mixed with a stable +nitro-cellulose the rate of decomposition will be increased. Calcium +carbonate and mercury chloride have no influence. If an unstable nitro- +cellulose be extracted with alcohol a stable compound is produced. The +percentage solubility of a nitro-cellulose in ether-alcohol rises on +heating to 132 deg. C. A sample which before heating had a solubility of 4.7% +had its solubility increased to 82.5% after six hours' heating. + +[Footnote A: _Jour. Soc. Chem. Ind._, xxiii., Oct. 15, 1904, p. 953.] + +Mr A.P. Sy (_Jour. Amer. Chem. Soc._, 1903) describes a new stability test +for nitro-cellulose which he terms "The Elastic Limit of Powder Resistance +to Heat." The test consists in heating the powder on a watch glass in an +oven to a temperature of 115 deg. C., after eight hours the watch glass and +powder are weighed and the process repeated daily for six days or less. He +claims that the powder is tested in its natural state, all the products of +decomposition are taken into account, whilst in the old tests only the +acid products are shown, and in the Will test only nitrogen, that it +affords an indication of the effect of small quantities of added +substances or foreign matters on the stability and that it is simple, and +not subject to the variations of the old tests. + +Obermueller (_Jour. Soc. Chem. Ind._, April 15, 1905) considers Bergmann +and Junk's test is too complicated and occupies too much time; he proposes +to heat gun-cotton to 140 deg. C. _in vacuo_, and to measure continuously by +means of a mercury manometer the pressure exerted by the evolved gases, +the latter being maintained at constant volume; the rate at which the +pressure increases is a measure of the rate of decomposition of the nitro- +cellulose. + +SPECIFIC GRAVITIES OF EXPLOSIVES, &C. + +Nitro-glycerine 1.6 +Gun-cotton (dry) 1.06 + " (25 per cent. water) 1.32 +Dynamite No. 1 1.62 +Blasting gelatine 1.54 +Gelatine dynamite 1.55 +Ballistite 1.6 +Forcite 1.51 +Tonite 1.28 +Roburite 1.40 +Bellite 1.2-1.4 +Carbo-dynamite 1.5 +Turpin's cast picric acid 1.6 +Nitro-mannite 1.6 +Nitro-starch 1.5 +Emmensite 1.8 +Mono-nitro-benzene 1.2 +Meta-di-nitro-benzene 1.575 at 18 deg. C. +Ortho-di-nitro-benzene 1.590 " +Para-di-nitro-benzene 1.625 " +British gunpowder, E.X.E. 1.80 + " " S.B.C. 1.85 +Cannonite (powder) 1.60 +Celluloid 1.35 +Cellulose 1.45 +Ammonium nitrate 1.707 +Mercury fulminate 4.42 + +TABLE OF THE TEMPERATURE OF DETONATION. + +Blasting gelatine 3220 deg. +Nitro-glycerine 3170 deg. +Dynamite 2940 deg. +Gun-cotton 2650 deg. +Tonite 2648 deg. +Picric acid 2620 deg. +Roburite 2100 deg. +Ammonia nitrate 1130 deg. + +RELATIVE SENSITIVENESS TO DETONATION (by Professor C.E. Munroe, U.S. Naval +Torpedo Station). + +__________________________________________________________________________ + | + | Maximum | + | Distance | + | at which | + | Detonation | + | occurred. | + | CM. | + | | +Gun-cotton | 10 | Nitro-glycerine 86.5 nitro-cotton + | | 9.5, camphor 4 per cent. +Explosive gelatine | 20 | NH_{4}NO_{3} 5 parts, +(camphorated) | | C_{6}H_{4}(N0_{3})_{2} 1 part. +Judson powder, R.R.P. | 25 | +Emmensite (No. 259) | 30 | +Rack-a-rock | 32 | KClO_{3} 79 parts, + | | C_{6}H_{5}(NO)_{2} 21 parts. +Bellite | 50 | +Forcite No. 1 | 61 | +Kieselguhr dynamite No. 1 | 64 | 75 per cent. nitro-gycerine. +Atlas powder No. 1 | 74 | +__________________________|____________|_________________________ + + + +CHAPTER IX. + +_DETERMINATION OF THE RELATIVE STRENGTH OF EXPLOSIVES._ + +Effectiveness of an Explosive--High and Low Explosives--Theoretical +Efficiency--MM. Roux and Sarrau's Results--Abel and Noble's--Nobel's +Ballistic Test--The Mortar, Pressure, or Crusher Gauge--Lead Cylinders-- +The Foot-Pounds Machine--Noble's Pressure Gauge--Lieutenant Walke's +Results--Calculation of Pressure Developed by Dynamite and Gun-Cotton-- +Macnab's and Ristori's Results of Heat Developed by the Explosion of +Various Explosives--Composition of some of the Explosives in Common Use +for Blasting, &c. + + +~The Determination of the Relative Strength of Explosives.~--Explosives +may be roughly divided into two divisions, viz., those which when exploded +produce a shattering force, and those which produce a propulsive force. +Explosives of the first class are generally known as the high explosives, +and consist for the most part of nitro compounds, or mixtures of nitro +compounds with other substances. Any explosive whose detonation is very +rapid is a high explosive, but the term has chiefly been applied to the +nitro-explosives. + +The effectiveness of an explosive depends upon the volume and temperature +of the gases formed, and upon the rapidity of the explosion. In the high +explosives the chemical transformation is very rapid, hence they exert a +crushing of shattering effect. Gunpowder, on the other hand, is a low +explosive, and produces a propelling or heaving effect. + +The maximum work that an explosive is capable of producing is +proportionate to the amount of heat disengaged during its chemical +transformation. This may be expressed in kilogrammetres by the formula +425Q, where Q is the number of units of heat evolved. The theoretical +efficiency of an explosive cannot, however, be expected in practice for +many reasons. + +In the case of blasting rock, for instance:[A]--1. Incomplete combustion +of the explosive. 2. Compression and chemical changes induced in the +surrounding material operated on. 3. Energy expended in the cracking and +heating of the material which is not displaced. 4. The escape of gas +through the blast-hole, and the fissures caused by the explosion. The +proportion of useful work has been estimated to be from 14 to 33 per cent. +of the theoretical maximum potential. + +[Footnote A: C.N. Hake, Government Inspector of Explosives, Victoria, +_Jour. Soc. Chem. Ind._, 1889.] + +For the purposes of comparison, manufacturers generally rely more upon the +practical than the theoretical efficiency of an explosive. These, however, +stand in the same relation to one another, as the following table of +Messrs Roux and Sarrau will show:-- + +MECHANICAL EQUIVALENT OF EXPLOSIVES. + + Theoretical Work Relative + in Kilos. Value. + +Blasting powder (62 per cent. KNO_{3}) 242,335 1.0 +Dynamite (75 per cent. nitro-glycerine) 548,250 2.26 +Blasting gelatine (92 per cent. nitro-glycerine) 766,813 3.16 +Nitro-glycerine 794,563 3.28 + +Experiments made in lead cylinders give-- + Dynamite 1.0 + Blasting gelatine 1.4 + Nitro-glycerine 1.4 + +Sir Frederick Abel and Captain W.H. Noble, R.A., have shown that the +maximum pressure exerted by gunpowder is equal to 486 foot-tons per lb. of +powder, or that when 1 kilo, of the powder gases occupy the volume of 1 +litre, the pressure is equal to 6,400 atmospheres; and Berthelot has +calculated that every gramme of nitro-glycerine exploded gives 1,320 units +of heat. MM. Roux and Sarrau, of the Depot Centrales des Poudres, Paris, +by means of calorimetric determinations, have shown that the following +units of heat are produced by the detonation of-- + +Nitro-glycerine 1,784 heat units. +Gun-cotton 1,123 " +Potassic picrate 840 " + +which, multiplied by the mechanical equivalent per unit, gives-- + +Nitro-glycerine 778 metre tons per kilogramme. +Gun-cotton 489 " " +Picrate of potash 366 " " + +~Nobel's Ballistic Test.~--Alfred Nobel was the first to make use of the +mortar test to measure the (ballistic) power of explosives. The use of the +mortar for measuring the relative power of explosives does not give very +accurate results, but at the same time the information obtained is of +considerable value from a practical point of view. The mortar consists of +a solid cylinder of cast iron, one end of which has been bored to a depth +of 9 inches, the diameter of the bore being 4 inches. At the bottom of the +bore-hole is a steel disc 3 inches thick, in which another hole has been +bored 3 inches by 2 inches. The mortar (Fig. 54) itself is fitted with +trunnions, and firmly fixed in a very solid wooden carriage, which is +securely bolted down to the ground. The shot used should weigh 28 lbs., +and be turned accurately to fit the bore of the mortar. Down its centre is +a hole through which the fuse is put. + +The following is the method of making an experiment:--A piece of hard wood +is turned in the lathe to exactly fit the hole in the steel disc at the +bottom of the bore. This wooden cylinder itself contains a small cavity +into which the explosive is put. Ten grms. is a very convenient quantity. +Before placing in the mortar, a hole may be made in the explosive by means +of a piece of glass rod of such a size that the detonator to be used will +just fit into it. After placing the wooden cylinder containing the +explosive in the cavity at the bottom of the bore, the shot, slightly +oiled, is allowed to fall gently down on to it. A piece of fuse about a +foot long, and fitted with a detonator, is now pushed through the hole in +the centre of the shot until the detonator is embedded in the explosive. +The fuse is now lighted, and the distance to which the shot is thrown is +carefully measured. The range should be marked out with pegs into yards +and fractions of yards, especially at the end opposite to the mortar. The +mortar should be inclined at an angle of 45 deg.. In experimenting with this +apparatus, the force and direction of the wind will be found to have +considerable influence. + +[Illustration: FIG. 54.--MORTAR FOR MEASURING THE BALLISTIC POWER OF +EXPLOSIVES. _A_, Shot; _B_, Steel Disc; _C_, Section of Mortar (Cast +Iron); _D_, Wooden Plug holding Explosive (_E_); _F_, Fuse.] + +Mr T. Johnson made some ballistic tests. He used a steel mortar and a shot +weighing 29 Ibs., and he adopted the plan of measuring the distance to +which a given charge, 5 grms., would throw the shot. He obtained the +following results:-- + + Range in Feet. + +Blasting gelatine (90 per cent. nitro-glycerine and nitro-cellulose) 392 +Ammonite (60 per cent. Am(NO_{3}) and 10 per cent. nitro-naphthalene) 310 +Gelignite (60 per cent. nitro-gelatine and gun-cotton) 306 +Roburite (AmNO_{3} and chloro-nitro-benzol) 294 +No. 1 dynamite (75 per cent. nitro-gelatine) 264 +Stonite (68 per cent. nitro-gelatine and 32 per cent. wood-meal) 253 +Gun-cotton 234 +Tonite (gun-cotton and nitrates) 223 +Carbonite (25 per cent. nitro-gelatine, 40 per cent. wood-meal, + and 30 per cent. nitrates) 198 +Securite (KNO_{3} and nitro-benzol) 183 +Gunpowder 143 + +~Calculation of the Volume of Gas Evolved in an Explosive Reaction.~--The +volume of gas evolved in an explosive reaction may be calculated, but only +when they are simple and stable products, such calculations being made at +0 deg. and 760 mm. Let it be required, for example, to determine the volume of +gas evolved by 1 gram-molecule of nitro-glycerine. The explosive reaction +of nitro-glycerine may be represented by the equation. + +C_{3}H_{5}O_{3}(NO_{2})_{3} = 3CO_{2} + 2-1/2H_{2}O + 1-1/2N_{2} + 1/4O_{2} +By weight 227 = 132 + 45 + 42 + 8 +By volume 2 = 3 + 2-1/2 + 1-1/2 + 1/4 + +The weights of the several products of the above reactions are calculated +by multiplying their specific gravities by the weight of 1 litre of +hydrogen at 0 deg. C. and 760 mm. (0.0896 grm). Thus, + +One litre of CO_{2} = 22 x .0896 = 1.9712 grm. + " H_{2}O = 9 x " = 0.8064 " + " N_{2} = 14 x " = 1.2544 " + " O_{2} = 16 x " = 1.4336 " + +The volume of permanent gases at 0 deg. and 760 mm. is constant, and assuming +the gramme as the unit of mass, is found to be 22.32 litres. Thus:-- + +Volume of 44 of CO_{2}, at 0 deg. and 760 mm. = 44/1.9712 = 22.32 litres. + 18 " H_{2}O " " = 18/0.8044 = 22.32 " + 28 " N_{2} " " = 28/1.2544 = 22.32 " + 32 " O_{2} " " = 32/1.4366 = 22.32 " + +Therefore + +132 grms. of CO_{2} at 0 deg. C and 760 mm. = 22.32 x 3 = 66.96 litres. + 45 " H_{2}O " " = 22.32 x 2-1/2 = 55.80 " + 42 " N_{2} " " = 22.32 x 1-1/2 = 33.48 " + 8 " O_{2} " " = 22.32 x 1/4 = 5.58 " + ____________ + + 161.82 " +Therefore 1 gram-molecule or 227 grms. of nitro-glycerine when exploded, +produces 161.82 litres of gas at 0 deg. C and 760 mm. + +To determine the volume of gas at the temperature of explosion, we simply +apply the law of Charles.[A] Thus-- + +V : V' :: T : T' or V' = VT'/T + +in which V represents the original volume. + V' " new volume. + T " original temperature on the absolute scale. + T' " new temperature of the same scale +In the present case T' = 6001 deg.. + +Therefore substituting, we have + +V' = 161.82x6001/273 = 3557 litres + +or at the temperature of explosion 1 gram-molecule of nitro-glycerine +produces 3,557 litres of permanent gas. + +[Footnote A: According to the law of Charles, the volume of any gas varies +directly as its temperature on the absolute scale, provided the pressure +remains constant. Knowing the temperature on the centigrade scale, the +corresponding temperature on the absolute scale is obtained by adding 273 +to the degrees centigrade.] + +~Pressure or Crusher Gauge.~--There are many forms of this instrument. As +long ago as 1792 Count Rumford used a pressure gauge. The so-called +crusher gauge was, however, first used by Captain Sir Andrew Noble in his +researches on powder. Other forms are the Rodman[A] punch Uchatius +Eprouvette, and the crusher gauge of the English Commission on Explosives. +They are all based either upon the size of an indent made upon a copper +disc by a steel punch fitted to a piston, acted upon by the gases of the +explosive, or upon the crushing or flattening of copper or lead cylinders. + +[Footnote A: Invented by General Rodman, United States Engineers.] + +[Illustration: FIG. 55.--PRESSURE GAUGE.] + +Berthelot uses a cylinder of copper, as also did the English Commission, +but in the simpler form of apparatus mostly used by manufacturers lead +cylinders are used. This form of apparatus (Fig. 55) consists of a base of +iron to which four uprights _a_ are fixed, set round the circumference of +a 4-inch circle; the lead plug rests upon the steel base let into the +solid iron block. A ring _c_ holds the uprights _d_ together at the top. +The piston _b_, which rests upon the lead plug, is a cylinder of tempered +steel 4 inches in diameter and 5 inches in length; it is turned away at +the sides to lighten it as much as possible. It should move freely between +the uprights _d_. In the top of this cylinder is a cavity to hold the +charge of explosive. The weight of this piston is 12-1/4 lbs. The shot _e_ +is of tempered steel, and 4 inches in diameter and 10 inches in length, +and weighs 34-1/2 lbs. It is bored through its axis to receive a capped +fuse. + +The instrument is used in the following manner:--A plug of lead 1 inch +long and 1 inch in diameter, and of a cylindrical form, is placed upon the +steel plate between the uprights _a_, the piston placed upon it, the +carefully weighed explosive placed in the cavity, and the shot lowered +gently upon the piston. A piece of fuse, with a detonator fixed at one +end, is then pushed through the hole in the shot until it reaches the +explosive contained in the cavity in the piston. The fuse is lighted. When +the charge is exploded, the shot is thrown out, and the lead cylinder is +more or less compressed. The lead plugs must be of a uniform density and +homogeneous structure, and should be cut from lead rods that have been +drawn, and not cast separately from small masses of metal. + +[Illustration: FIG. 56.--_b_, STEEL PUNCH; _c_, LEAD CYLINDER FOR USE WITH +PRESSURE GAUGE.] + +The strength of the explosive is proportional to the work performed in +reducing the height of the lead (or copper) plug, and to get an expression +for the work done it is necessary to find the number of foot-pounds (or +kilogrammetres) required to produce the different amounts of compression. +This is done by submitting exactly similar cylinders of lead to a crushing +under weights acting without initial velocity, and measuring the reduced +heights of the cylinders; from these results a table is constructed +establishing empirical relations between the reduced heights and the +corresponding weights; the cylinders are measured both before and after +insertion in the pressure gauge by means of an instrument known as the +micrometer calipers (Fig. 57).[A] + +[Footnote A: An instrument called a "Foot-pounds Machine" has been +invented by Lieut. Quinan, U.S. Army. It consists of three boards, +connected so as to form a slide 16 feet high, in which a weight (the shot +of the pressure gauge) can fall freely. One of the boards is graduated +into feet and half feet. The horizontal board at the bottom, upon which +the others are nailed, rests upon a heavy post set deep in the ground, +upon which is placed the piston of the gauge, which in this case serves as +an anvil on which to place the lead cylinders. The shot is raised by means +of a pulley, fixed at the top of the structure, to any desired height, and +let go by releasing the clutch that holds it. The difference between the +original length and the reduced length gives the compression caused by the +blow of the shot in falling, and gives the value in foot-pounds required +to produce the different amounts of compression. (Vide _Jour. U.S. Naval +Inst._, 1892.)] + +[Illustration: FIG. 57.--MICROMETER CALIPERS FOR MEASURING DIAMETER OF +LEAD CYLINDERS.] + +~The Use of Lead Cylinders.~--The method of using lead cylinders to test +the strength of an explosive is a very simple affair, and is conducted as +follows:--A solid cast lead cylinder, of any convenient size, is bored +down the centre for some inches, generally until the bore-hole reaches to +about the centre of the block. The volume of this hole is then accurately +measured by pouring water into it from a graduated measure, and its +capacity in cubic centimetres noted. The bore-hole is then emptied and +dried, and a weighed quantity (say 10 grms.) of the explosive pressed well +down to the bottom of the hole. A hole is then made in the explosive (if +dynamite) with a piece of clean and rounded glass rod, large enough to +take the detonator. A piece of fuse, fitted with a detonator, is then +inserted into the explosive and lighted. After the explosion a large pear- +shaped cavity will be found to have been formed, the volume of which is +then measured in the same way as before. + +The results thus obtained are only relative, but are of considerable value +for comparing dynamites among themselves (or gun-cottons). Experiments in +lead cylinders gave the relative values for nitro-glycerine 1.4, blasting +gelatine 1.4, and dynamite 1.0. (Fig. 58 shows sections of lead cylinders +before and after use.) + +[Illustration: FIG. 58.--LEAD CYLINDERS BEFORE AND AFTER USE.] + +Standard regulations for the preparation of lead cylinders may be found in +the _Chem. Zeit._, 1903, 27 [74], 898. They were drawn up by the Fifth +International Congress of App. Chem., Berlin. The cylinder of lead should +be 200 mm. in height and 200 mm. in diameter. In its axis is a bore-hole, +125 mm. deep and 25 mm. in diameter. The lead used must be pure and soft, +and the cylinder used in a series of tests must be cast from the same +melt. The temperature of the cylinders should be 15 deg. to 20 deg. throughout. +Ten grms. of explosive should be used and wrapped in tin-foil. A detonator +with a charge of 2 grms., to be fired electrically, is placed in the midst +of the explosive. The cartridge is placed in the bore-hole, and gently +pressed against the bottom, the firing wires being kept in central +position. The bore-hole is then filled with dry quartz sand, which must +pass through a sieve of 144 meshes to the sq. cm., the wires being .35 mm. +diameter. The sand is filled in evenly, any excess being levelled off. The +charge thus prepared is then fired electrically. The lead cylinder is then +inverted, and any residues removed with a brush. The number of c.c. of +water required to fill the cavity, in excess of the original volume of the +bore-hole, is a measure of the strength of the explosive. The results are +only comparable if made with the same class of explosive. A result is to +be the mean of at least three experiments. The accuracy of the method +depends on (_a_) the uniform temperature of the lead cylinder (15 deg. to 20 deg. +C. 7); (_b_) on the uniformity of the quartz sand; (_c_) on the uniformity +of the measurements. + +[Illustration: FIG. 59.--NOBLE'S PRESSURE GAUGE.] + +~Noble's Pressure Gauge.~--The original explosive vessels used by Captain +Sir A. Noble in his first experiments were practically exactly similar to +those that he now employs, which consists of a steel barrel A (Fig. 59), +open at both ends, which are closed by carefully fitted screw plugs, +furnished with steel gas checks to prevent any escape past the screw. The +action of the gas checks is exactly the same as the leathers used in +hydraulic presses. The pressure of the gas acting on both sides of the +annular space presses these sides firmly against the cylinder and against +the plug, and so effectually prevents any escape. In the firing plug F is +a conical hole closed by a cone fitting with great exactness, which, when +the vessel is prepared for firing, is covered with fine tissue paper to +act as an insulator. The two firing wires GG, one in the insulated cone, +the other in the firing plug, are connected by a very fine platinum wire +passing through a glass tube filled with meal powder. The wire becomes +red-hot when connection is made with a Leclanche battery, and the charge +which has previously been inserted into the vessel is fired. The crusher +plug is fitted with a crusher gauge H for determining the pressure of the +gases at the moment of explosion, and in addition there is frequently a +second crusher gauge apparatus screwed into the cylinder. When it is +desired to allow the gases to escape for examination, the screw J is +slightly withdrawn. The gases then pass into the passage I, and can be led +to suitable apparatus in which their volume can be measured, or in which +they can be sealed for subsequent chemical analysis. + +The greatest care must be exercised in carrying out experiments with this +apparatus; it is particularly necessary to be sure that all the joints are +perfectly tight before exploding the charge. Should this not be the case, +the gases upon their generation will cut their way out, or completely blow +out the part improperly secured, in either case destroying the apparatus. +The effect produced upon the apparatus when the gas has escaped by cutting +a passage for itself is very curious. The surface of the metal where the +escape occurred presents the appearance of having been washed away in a +state of fusion by the rush of the highly heated products. + +~The Pressure Gauge.~--The pressure is found by the use of a little +instrument known as the pressure gauge which consists of a small chamber +formed of steel, inside of which is a copper cylinder, and the entrance +being closed by a screw gland, in which a piston, having a definite +sectional area, works. There is a gas check E (Fig. 60) placed in the +gland, and over the piston, which prevents the admission of gas to the +chamber. When it is desired to find the pressure in the chamber of a gun, +one or more of these crushers are made up with or inserted at the extreme +rear end of the cartridge, in order to avoid their being blown out of the +gun when fired. This, however, often takes place, in which case the gauges +are usually found a few yards in front of the muzzle. The copper cylinders +which register the pressure are made 0.5 inch long from specially selected +copper, the diameters being regulated to give a sectional area of either +1/12 or 1/24 square inch. + +[Illustration: FIG. 60.--CRUSHER GAUGE. _E_, GAS CHECK.] + +Hollow copper cylinders are manufactured with reduced sectional areas for +measuring very small pressures. It has been found that these copper +cylinders are compressed to definite lengths for certain pressures with +remarkable uniformity. Thus a copper cylinder having a sectional area of +1/12 square inch, and originally 1/2 inch long, is crushed to a length of +0.42 inch by a pressure of 10 tons per square inch. By subsequently +applying a pressure of 12 tons per square inch the cylinder is reduced to +a length of 0.393 inch. Before using the cylinders, whether for +experimenting with closed vessels or with guns, it is advisable to first +crush them by a pressure a little under that expected in the experiment. +Captain Sir A. Noble used in his experiments a modification of Rodman's +gauge. (Ordnance Dept., U.S.A., 1861.) + +~By Calculation.~--To calculate the pressure developed by the explosion of +dynamite in a bore-hole 3 centimetres in diameter, charged with 1 +kilogramme of 75 per cent. dynamite, Messrs Vieille and Sarrau employ the +following formula:-- + +P = V_{o}(1 + Q/273._c_)/(V - _v_). + +Where V_{o} = the volume (reduced to 0 deg. and 760 mm.) of the gases produced +by a unit of weight of the explosive; Q the number of calories disengaged +by a unit of weight of the explosive; _c_ equals the specific heat at +constant volume of the gases; V the volume in cubic centimetres of a unit +of weight of the explosive; _v_ the volume occupied by the inert +materials of the explosive. The volume of gas produced by the explosion of +1 kilogramme of nitro-glycerine (at 0 deg. and 760 mm.) is 467 litres. + +V_{o} will therefore equal 0.75 x 467 = 350.25. + +The specific heat _c_ is, according to Sarrau, .220 (_c_); and according +to Bunsen, 1 kilogramme of dynamite No. 1 disengages 1,290 (Q) calories. +The density of dynamite is equal to 1.5, therefore + +V = 1/1.5 = .666. + +If we take the volume of the kieselguhr as .1, we find from above formula +that + +P = 350(1 + 1290/(273 x .222))/(.600 - .1) = 13,900 atmospheres, + +which is equal to 14,317 kilogrammes per square centimetre. The pressure +developed by 1 kilogramme of pure nitro-glycerine equals 18,533 +atmospheres, equals 19,151 kilogrammes. Applying this formula to gun- +cotton, and taking after Berthelot, Q = 1075, and after Vieille and +Sarrau, V_{o} = 671 litres, and _c_ as .2314, and the density of the +nitro-cellulose as 1.5, we have (V = O) + +P = 671(1 + 1075/(273 x .2314))/.666 = 18,135 atmospheres. + +To convert this into pressure of kilogrammes per square centimetre, it is +necessary to multiply it by the weight of a column of mercury 0.760 m. +high, and 1 square centimetre in section, which is equal to increasing it +by 1/30. It thus becomes + +P^{k} = (1 + 1/30). + +P^{k} = 18,135 x 1.033 = 18,733 kilogrammes. + +The following tables, taken from Messrs William Macnab's and E. Ristori's +paper (_Proc. Roy. Soc._, 56, 8-19), "Researches on Modern Explosives," +are very interesting. They record the results of a large number of +experiments made to determine the amount of heat evolved, and the quantity +and composition of the gases produced when certain explosives and various +smokeless powders were fired in a closed vessel from which the air had +been previously exhausted. The explosions were carried out in a +"calorimetric bomb" of Berthelot's pattern.[A] + +[Footnote A: For description of "bomb," see "Explosives and their Power," +Berthelot, trans. by Hake and Macnab, p. 150. (Murray.)] + +Table Showing Quantity of Heat and Volume and Analysis of Gas Developed +per Gramme with Different Sporting and Military Smokeless Powders Now In +Use + +______________________________________________________________________ + | | | | | + Name of Explosive. | Calories | Permanent | Aqueous | Total Volume | + | per grm. | Gases. | Vapour. | of Gas at 0 deg. | + | | | | and 760 mm. | +______________________|__________|___________|_________|______________| + | | cc/grm | cc/grm | cc/grm | + E.C. powder, English | 800 | 420 | 154 | 574 | + S.S. powder | 799 | 584 | 150 | 734 | + Troisdorf, German | 943 | 700 | 195 | 895 | + Rifleite, English | 864 | 766 | 159 | 925 | + B.N., French | 833 | 738 | 168 | 906 | + Cordite, English | 1253 | 647 | 235 | 882 | + Ballistite, German | 1291 | 591 | 231 | 822 | + Ballistite, Italian | 1317 | 58l | 245 | 826 | + and Spanish | | | | | +______________________|__________|___________|_________|______________| + +The figures in column headed "Co-efficient of Potential Energy" serve as a +measure of comparison of the power of the explosives, and are the products +of the number of calories by the volume of gas, the last three figures +being suppressed in order to simplify the results. + +The amounts of water found were calculated for comparison as volumes of +H_{2}O gas at 0 deg. and 760 mm. + +E.C. powder consists principally of nitro-cellulose mixed with barium +nitrate and a small proportion of camphor. + +S.S. of nitro-lignine mixed with barium nitrate and nitro-benzene. + +Troisdorf powder is gelatinised nitro-cellulose; rifleite gelatinised +nitro-cellulose and nitro-benzene. + +Cordite contains 58 per cent. nitro-glycerine, 37 per cent. gun-cotton, +and 5 per cent. vaseline. + +Ballistite (Italian) consists of equal parts nitro-cellulose and nitro- +glycerine, and 1/2 per cent. of aniline. The German contains a higher +percentage of nitro-cellulose. + +TABLE SHOWING THE HEAT DEVELOPED BY EXPLOSIVES CONTAINING NITRO-GLYCERINE +AND NITRO-CELLULOSE IN DIFFERENT PROPORTIONS. + +______________________________________________________________________ + Composition of Explosives. | Calories per cent. +_____________________________________________|________________________ +Nitro-cellulose | | +(N = 13.3 per cent.). | Nitro-glycerine. | + | | +100 per cent. dry pulp | 0 | 1061 +100 " gelatinised | 0 | 922 + 90 " | 10 per cent. | 1044 + 80 " | 20 " | 1159 + 70 " | 30 " | 1267 + 60 " | 40 " | 1347 + 50 " | 50 " | 1410 + 40 " | 60 " | 1467 + 0 " | 100 " | 1652 +__________________________|__________________|________________________ + | | +Nitro-cellulose | | +(N=12.24 per cent.) | Nitro-glycerine. | + | | + 80 per cent. | 20 per cent. | 1062 + 60 " | 40 " | 1288 + 50 " | 50 " | 1349 + 40 " | 60 " | 1405 + | | +__________________________|__________________|________________________| +Nitro-cellulose | | +(N = 13.3 per cent.). | Nitro-glycerine. | Vaseline. + | | + 55 per cent. | 40 per cent. | 5 per cent. 1134 + 35 " | 60 " | 5 " 1280 +__________________________|__________________|________________________ + +TABLE OF RESULTS OBTAINED BY LIEUT. W. WALKE., OF THE ARTILLERY, U.S.A, +WITH QUINAN'S PRESSURE GAUGE. + +Nitro-glycerine being taken as 100. (From _U.S. Naval Inst. Jour._) + +__________________________________________________________________________ + | | | + | Compression | Order of | + Name of Explosive. | of Lead | Strength. | + | | | + | Inch. | | +Explosive gelatine | 0.585 | 106.17 | +Hellhoffite | 0.585 | 106.17 | +Nitro-glycerine | 0.551 | 100.00 | Standard, N.G. +Nobel's smokeless powder | 0.509 | 92.38 | +Nitro-glycerine | 0.509 | 92.37 | +Gun-cotton | 0.458 | 83.12 | U.S. naval torpedo + | | | gun-cotton +Gun-cotton | 0.458 | 83.12 | Stowmarket. +Nitro-glycerine | 0.451 | 81.85 | Vouges, N.G. +Gun-cotton | 0.448 | 81.31 | +Dynamite No. 1 | 0.448 | 81.31 | +Dynamite de Traul | 0.437 | 79.31 | +Emmensite | 0.429 | 77.86 | +Amide powder | 0.385 | 69.87 | +Oxonite | 0.383 | 69.51 | +Tonite | 0.376 | 68.24 | G.C. 52.5%, and + | | | Ba(NO_{3})_{2}, 47.5% +Bellite | 0.362 | 65.70 | +Rack-a-rock | 0.340 | 61.71 | +Atlas powder | 0.333 | 60.43 | +Ammonia dynamite | 0.332 | 60.25 | +Volney's powder No. 1 | 0.322 | 58.44 | Nitrated naphthalene. + " No. 2 | 0.294 | 53.18 | " " +Melinite | 0.280 | 50.82 | Picric acid 70%, and + | | | sol. nitro-cotton 30%. +Silver fulminate | 0.277 | 50.27 | +Mercury | 0.275 | 49.91 | +Mortar powder | 0.155 | 28.13 | +_________________________|_____________|___________|______________________ + +~Composition of some of the Explosives in Common Use.~ + +~Ordinary Dynamite.~ + +Nitro-Glycerine 75 per cent. +Kieselguhr 25 " + +~Amvis.~ + +Nitrate of Ammonia 90 per cent. +Chloro-di-nitro Benzene 5 " +Wood Pulp 5 " + +~Ammonia Nitrate Powder.~ + +Nitrate of Ammonia 80 per cent. +Chlorate of Potash 5 " +Nitro-Glucose 10 " +Coal Tar 5 " + +~Celtite.~ + +Nitro-Glycerine 56-59 parts. +Nitro-Cotton 2-3.5 " +KNO_{3} 17-21 " +Wood Meal 8-9 " +Ammonium Oxalate 11-13 " +Moisture 0.5-1.5 " + +~Atlas Powders.~ + +Sodium Nitrate 2.0 per cent. +Nitro-Glycerine 75.0 " +Wood Pulp 21.0 " +Magnesium Carbonate 2.0 " + +~Dauline.~ + +Nitro-Glycerine 50 per cent. +Sawdust 30 " +Nitrate of Potash 20 " + +~Vulcan Powder.~ + +Nitro-Glycerine 30 per cent. +Nitrate of Soda 52.5 " +Sulphur 7.0 " +Charcoal 10.5 " + +~Vigorite.~ + +Nitro-Glycerine 30 per cent. +Nitrate of Soda 60 " +Charcoal 5 " +Sawdust 5 " + +~Rendrock.~ + +Nitrate of Potash 40 per cent. +Nitro-Glycerine 40 " +Wood Pulp 13 " +Paraffin or Pitch 7 " + +~Ammonia Nitrate Powder.~ + +Ammonia Nitrate 80 per cent. +Potassium Chlorate 5 " +Nitro-Glucose 10 " +Coal Tar 5 " + +~Hercules Powders.~ + +Nitro-Glycerine 75 to 40 per cent. +Sugar 1 " 15.66 " +Chlorate of Potash 1.05 " 3.34 " +Nitrate of Potash 2.10 " 31.00 " +Carbonate of Magnesia 20.85 " 10.00 " + +~Carbo-Dynamite.~ + +Nitro-Glycerine 90 per cent. +Charcoal 10 " + +~Geloxite (Permitted List).~ + +Nitro-Glycerine 64-54 parts. +Nitro-Cotton 5-4 " +Nitrate of Potash 22-13 " +Ammonium Oxalate 15-12 " +Red Ochre 1-0 " +Wood Meal 7-4 " + +The Wood Meal to contain not more than 15% and not less than 5% moisture. + +~Giant Powder.~ + +Nitro-Glycerine 40 per cent. +Sodium Nitrate 40 " +Rosin 6 " +Sulphur 6 " +Guhr 8 " + +~Dynamite de Trauzel.~ + +Nitro-Glycerine 75 parts. +Gun-Cotton 25 " +Charcoal 2 " + +~Rhenish Dynamite.~ + +Solution of N.G. in Naphthalene 75 per cent. +Chalk, or Barium Sulphate 2 " +Kieselguhr 23 " + +~Ammonia Dynamite.~ + +Ammonia Nitrate 75 parts. +Paraffin 4 " +Charcoal 3 " +Nitro-Glycerine 18 " + +~Blasting Gelatine.~ + +Nitro-Glycerine 93 per cent. +Nitro-Cotton 3 to 7 " + +~Gelatine Dynamite.~ + +Nitro-Glycerine 71 per cent. +Nitro-Cotton 6 " +Wood Pulp 5 " +Potassium Nitrate 18 " + +~Gelignite.~ + +Nitro-Glycerine 60 to 61 per cent. +Nitro-Cotton 4 " 5 " +Wood Pulp 9 " 7 " +Potassium Nitrate 27 " + +~Forcite.~ + +Nitro-Glycerine 49 per cent. +Nitro-Cotton 1.0 " +Sulphur 1.5 " +Tar 10.0 " +Sodium Nitrate 38.0 " +Wood Pulp 5 " + (The N.-G., &c., varies.) + +~Tonite No. 1.~ + +Gun-Cotton 52-50 per cent. +Barium Nitrate 47-40 " + +~Tonite No. 2.~ + +Contains Charcoal also. + +~Tonite No. 3.~ + +Gun-Cotton 18 to 20 per cent. +Ba(NO_3)_2 70 " 67 " +Di-nitro-Benzol 11 " 13 " +Moisture 0.5 " 1 " + +~Carbonite.~ + +Nitro-Glycerine 17.76 per cent. +Nitro-Benzene 1.70 " +Soda 0.42 " +KNO_3 34.22 " +Ba(NO_3)_2 9.71 " +Cellulose 1.55 " +Cane Sugar 34.27 " +Moisture 0.36 " + ________ + + 99.99 + +~Roburite.~ + +Ammonium Nitrate 86 per cent. +Chloro-di-nitro-Benzol 14 " + +~Faversham Powder.~ + +Ammonium Nitrate 85 per cent. +Di-nitro-Benzol 10 " +Trench's Flame-extinguishing Compound 5 " + +~Favierite No. 1.~ + +Ammonium Nitrate 88 per cent. +Di-nitro-Naphthalene 12 " + +~Favierite No. 2.~ + +No. 1 Powder 90 per cent. +Ammon. Chloride 10 " + +~Bellite.~ + +Ammonium Nitrate 5 parts. +Meta-di-nitro-Benzol 1 " + +~Petrofacteur.~ + +Nitro-Benzene 10 per cent. +Chlorate of Potash 67 " +Nitrate of Potash 20 " +Sulphide of Antimony 3 " + +~Securite.~ + +Mixtures of Meta-di-nitro-Benzol 26 per cent. +and Nitrate of Ammonia 74 " + +~Rack-a-Rock.~ + +Potassium Chlorate 79 parts. +Mono-nitro-Benzene 21 " + +~Oxonite.~ + +Nitric Acid (sp. gr. 1.5) 54 parts. +Picric Acid 46 " + +~Emmensite.~ + +Emmens Acid 5 parts. +Ammonium Nitrate 5 " +Picric Acid 6 " + +~Brugere Powder.~ + +Ammonium Picrate 54 per cent. +Nitrate of Potash 46 " + +~Designolle's Torpedo Powders.~ + +Potassium Picrate 55 to 50 per cent. +Nitrate of Potash 45 " 50 " + +~Stowite.~ + +Nitro-Glycerine 58 to 61 parts. +Nitro-Cotton 4.5 " 5 " +Potassium Nitrate 18 " 20 " +Wood Meal 6 " 7 " +Oxalate of Ammonia 11 " 15 " + +The Wood Meal shall contain not more than 15% and not less than 5% by +weight of moisture. The explosive shall be used only when contained +in a non-water-proofed wrapper of parchment--No. 6 detonator. + +~Faversham Powder.~ + +Nitrate of Ammonium 93 to 87 +Tri-nitro-Toluol 11 " 9 +Moisture 1 " -- + +~Kynite.~ + +Nitro-Glycerine 24-26 parts. +Wood-Pulp 2.5-3.5 " +Starch 32.5-3.5 " +Barium Nitrate 31.5-34.5 " +CaCO_{3} 0-0.5 " +Moisture 3.0-6.0 " + +Must be put up only in water-proof parchment paper, and No. 6 electric +detonator used. + +~Rexite.~ + +Nitro-Glycerine 6.5-8.5 parts. +Ammonium Nitrate 64-68 " +Sodium Nitrate 13-16 " +Tri-nitro-Tolulene 6.5-8.5 " +Wood Meal 3-5 " +Moisture .5-1.4 " + +Must be contained in water-proof case (stout paper), water-proofed with +Resin and Cerasin--No. 6 detonator. + +~Withnell Powder.~ + +Ammonium Nitrate 88-92 parts. +Tri-nitro-Toluene 4-6 " +Flour (dried at 100 deg. C.) 4-6 " +Moisture 0-15 " + +Only to be used when contained in a linen paper cartridge, water-proofed +with Carnuba Wax, Parrafin--No. 7 detonator used. + +~Phenix Powder.~ + +Nitro-Glycerine 28-31 parts. +Nitro-Cotton 0-1 " +Potassium Nitrate 30-34 " +Wood Meal 33-37 " +Moisture 2-6 " + +~SMOKELESS POWDERS.~ + +~Cordite.~ + +Nitro-Glycerine 58 per cent. +or- .75 +Nitro-Cotton 37 " +or- .65 +Vaseline 5 " +or- .25 + +~Cordite, M.D.~ + +Nitro-Glycerine 30 per cent. +or- 1 +Nitro-Cotton 65 " +or- 1 +Vaseline 5 " +or- .25 + +Analysis of-- + By W. Mancab and A.E. Leighton. + +~E.C. Powder.~ + +Nitro-Cotton 79.0 per cent. +Potassium Nitrate 4.5 " +Barium Nitrate 7.5 " +Camphor 4.1 " +Wood Meal 3.8 " +Volatile Matter 1.1 " + +~Walarode Powder.~ + +Nitro-Cotton 98.6 per cent. +Volatile Matter 1.4 " + +~Kynoch's Smokeless.~ + +Nitro-Cotton 52.1 per cent. +Di-nitro-Toluene 19.5 " +Potassium Nitrate 1.4 " +Barium Nitrate 22.2 " +Wood Meal 2.7 " +Ash 0.9 " +Volatile Matter 1.2 " + +~Schultze.~ + +Nitro-Lingin 62.1 per cent. +Potassium Nitrate 1.8 " +Barium Nitrate 26.1 " +Vaseline 4.9 " +Starch 3.5 " +Volatile Matter 1.0 " + +~Imperial Schultze.~ + +Nitro-Lignin 80.1 per cent. +Barium Nitrate 10.2 " +Vaseline 7.9 " +Volatile Matter 1.8 " + +~Cannonite.~ + +Nitro-Cotton 86.4 per cent. +Barium Nitrate 5.7 " +Vaseline 2.9 " +Lamp Black 1.3 " +Potassium Ferro-cyanide 2.4 " +Volatile Matter 1.3 " + +~Amberite.~ + +Nitro-Cotton 71.0 per cent. +Potassium Nitrate 1.3 " +Barium Nitrate 18.6 " +Wood Meal 1.4 " +Vaseline 5.8 " + +~Sporting Ballistite.~ + +Nitro-Glycerine 37.6 per cent +Nitro-Cotton 62.3 " +Volatile Matter 0.1 " + +The following is a complete List of the Permitted Explosives as Defined in +the Schedules to the Explosives in Coal Mines Orders of the 20th December +1902, of the 24th December 1903, of the 5th September 1903, and 10th +December 1903:-- + +Albionite. +Ammonal. +Ammonite. +Amvis. +Aphosite. +Arkite. +Bellite No. 1. +Bellite No. 2. +Bobbinite. +Britonite. +Cambrite. +Carbonite. +Clydite. +Coronite. +Dahmenite A. +Dragonite. +Electronite. +Faversham Powder. +Fracturite. +Geloxite. +Haylite No. 1. +Kynite. +Negro Powder. +Nobel's Ardeer Powder. +Nobel Carbonite. +Normanite. +Pit-ite. +Roburite No. 3. +Saxonite. +Stow-ite. +Thunderite. +Victorite. +Virite. +West Falite No. 1. +West Falite No. 2. + + + + +INDEX. + +Abel's, Sir Frederick, method of manufacturing gun-cotton, 57. + +Abel's heat test, 249. + +Acid mixture for nitrating nitro-glycerine, 23. + +Air pressure in nitrator, 28. + +Alkalinity in nitro-cellulose, 217. + +Amberite, 189. + +Ammonite, 149. + +Analyses of collodion-cotton, 81. + gelatine dynamites, 123. + +Analysis of explosives, 197. + acetone, 209. + blasting gelatine, 199. + cap composition, 241. + cordite, 206. + celluloid, 230. + dynamite, 197. + forcite, 202. + fulminate, 240. + glycerine, 233. + gun-cotton, 212. + nitric acid, 24. + picric acid, 230. + tonite, 205. + waste acids, 239. + +Armstrong on the constitution of the fulminates, 159. + +Atlas powder, 119. + +Auld on acetone, 211. + +Axite, 176. + + + +Ballistite, 179. + +Beater or Hollander for pulping gun-cotton, 64. + +Bedson, Prof., on roburite explosion gases, 140. + +Bellite, 142. + +Benzene, explosives derived from, 132. + +Benzene, mono-nitro- and di-nitro-benzene, 134. + +Bergmann and Junk on nitro-cellulose tests, 268. + +Bernthsen summary of nitro-benzenes, 133. + +Blasting gelatine, 119. + +Blasting charge, preparation of, 166. + +B.N. powder, 190. + +Boiling-point of N.G., 19. + +Boutnny's nitro-glycerine process, 15. + +Brown on wet gun-cotton, 56. + +Brugere's powder, 195. + +Bucknill's resistance coil, 13. + + + +Calculation of volume of gas evolved in an explosive reaction, 276. + +Cannonite, 189. + +Cellulose, 2, 47. + +Celluloid manufacture, 91. + analysis, 230. + cartridges, 91. + uses of, 90. + Field's papers on, 93. + fibre for, 94. + nitration of fibre, &c., 95. + formula of, 57. + +Champion and Pellet's method of determining nitrogen, 223. + +Chenel's modification of Kjeldahl's method, 227. + +Collodion-cotton, 79. + +Comparative tests of black and nitro-powders, 193. + +Compressing gun-cotton, 77. + +Composition of waste acids from nitro-glycerine, 43. + +Composition of some common explosives, 290. + +Conduits for nitro-glycerine, 7. + +Cooppal powder, 5, 189. + +Cordite manufacture, 169. + analysis, 206. + +Cresilite, 158. + +Cross and Bevan on nitro-jute, 107. + +Crusher gauge, 284. + +Cundill, Colonel, classification of dynamites, 112. + + + +Danger area, 5. + +Dangers in the manufacture of gun-cotton, 85. + +Decomposition of cellulose, 54. + +Definition of explosives in Order of Council (Explosives Act), 1. + +Determination of N_{2}O_{4} in nitric acid, 24. + +Determination of strength of H_{2}SO_{4}, 25. + +Determination of relative strength of explosives, 272. + +Detonators, 163. + +Di-nitro-toluene, 138. + +Dipping cotton in manufacture of gun-cotton, 60. + +Divers and Kawakita on the fulminates, 159. + +Dixon, Prof. H.B., on roburite explosions, 139. + +Drying house for gun-cotton, 122. + +Dynamite, efficiency of, 118. + frozen dynamite, 116. + gelatine dynamite, 119. + properties of kieselguhr dynamite, 116. + Reid & Borland's carbo-dynamite, 119. + Rhenish dynamite, 119. + various kinds of, 119. + + + +E.C. powder, 186. + +Electronite, 151. + +Emmensite, 195. + +Equation of formation of nitro-glycerine, 16. + +Equation of formation of nitro-cellulose, 50. + +Exploders, electric, 167. + +Explosion gases of dynamite, 19. + nitro-glycerine, 18. + gun-cotton, 55. + roburite, 139. + +Exudation test gelatines, 257. + + + +Faversham powder, 147. + +Favier's explosive, 149. + +Field on celluloid, 93, 99. + +Firing-point of explosives, 247. + +Filite, 180. + +Filtering nitre-glycerine, 37. + +Flameless explosives, 89, 138, 144. + +Formation of white matter in the nitration of N.G., 39. + +Forcite, 119. + +France, 82. + +Free fatty acid in glycerine, 39, 235. + +Freeing nitric acid from N_{2}O_{4}, 25. + +Freezing-point of N.G., 21. + +French Commission on Ammonium Nitrate, 142. + +Fulminates constitution, 159. + +Fulminate of mercury, 159, 240. + +Fulminate of silver, 161. + +Fuses, various kinds of, 166. + + + +Gases formed by the decomposition of nitro-glycerine, 18. + +Gelatine explosives, analysis of, 199. + +Glycerine, analysis of, 233. + formula of, 16. + nitration of, 23. + +Greiner's powder, 190. + +Gun-cotton, analysis of, 212. + boiling, 64. + complete series of, 52, 54. + compressing, moulding, and packing, 67, 77, 78. + dipping and steeping the cotton, 60. + drying the cotton, 58. + granulation of, 79. + manufacture of, 57. + Abel's method, 57. + Stowmarket, 57. + Waltham Abbey, 71. + products of decomposition of, 55. + properties of, 54. + pulping, 65. + washing, 63. + as a mining explosive, 56. + +Guttmann's nitric acid plant, 45. + +Guttmann's heat test, 256. + + + +Handy's method for determining moisture in dynamite, 197. + +Hannah, Dr N., on roburite explosion gases, 139. + +Heat developed by explosives containing nitro-glycerine, &c., 288. + +Heat test, Abel, 249. + +Hellhoffite, 152. + +Henrite powder, 191. + +Hollander, 65. + +Horsley's apparatus, 248. + +Hydro-extractors for wringing out gun-cotton, 62. + + + +Impurities in commercial glycerine, 39, 233. + +Impurities in fulminate, 240. + nitro-glycerine, 38. + picric acid, 231. + + + +Ketones as solvents for pyroxyline, 101. + +Kieselguhr dynamite, 112. + +Kinetite, 145. + +Kjeldahl method of determining nitrogen, 227. + + + +Le Bouchet, manufacture of gun-cotton at, 78. + +Lead cylinders for testing strength of explosives, 281. + +Lenk's improvements in gun-cotton manufacture, 49. + +Lewes on the pressure of cordite, 175. + +Leibert's treatment of nitro-glycerine, 30. + +Lightning conductors for danger buildings, 10. + +Liquefaction test for gelatine, 257. + +Lodge on lightning conductors, 8. + +Lowering of freezing-point of N.G., 21. + +Lunge's nitrometer, 219. + +Lydite, 156. + + + +Manufacture of gun-cotton, 57. + +Manufacture of nitro-glycerine, 17. + cordite, 169. + roburite, 140. + fulminates, 162. + tonite, 84. + di-nitro-benzene, 138. + nitro-starch, 103. + celluloid, 91. + +Majendie (Col. Sir V.D.), report on a picric acid explosion, 155. + +Maximite, 191. + +Maxim's detonator mixture, 165. + +M'Robert's mixing machine, 126. + +Mechanical equivalent of explosives, 273. + +Melinite, 156. + +Mono-nitro-glycerine, di-nitro-nitro-glycerine, 41. + +Moulding gun-cotton, 77. + +Mounds for protection of danger buildings, 6. + +Mortar for ballistic tests, 275. + +Mowbray on use of compressed air, 15. + +Muehlhaeusen on nitro-starch, 4, 5, 103. + + + +Nathan's nitrator, 32. + +Nitric peroxide in N.G., 24. + +Nitration products of cellulose, 52, 54. + +Nitro-glycerine, analysis of, 198. + properties, 17. + nitration, 23. + separation, 35. + washing, 37. + uses of, 41. + manufacture of, 17. + +Nitro-benzene, properties and manufacture of, 132, 137. + +Nitro-cellulose, 2, 47, 60, 212. + +Nitro-jute, 5, 107. + +Nitro-mannite, 4, 109. + +Nitro-naphthalene, 148. + +Nitro-starch, 4, 103. + +Nitro-toluene, 132. + +Nitrated gun-cotton, 83. + +Nitrogen, determination of, Lunge method, 219. + Champion and Pellet's, 223. + Schultze-Tieman, 224. + Kjeldahl-Chenel's, 227. + percentages of in various explosives, 228. + +Nitrometers, Lunge, Horn's, &c., 220, 222. + +Nobel's ballistic test, 274. + +Noble's pressure gauge, 282. + experiments on cordite, 172. + +Normal powder, 191. + + + +Oleic acid in glycerine, 236. + +Orsman on roburite, 142. + +Oxonite, 152. + +Oxy-cellulose, 102. + + + +Packing gun-cotton, 78. + dynamite, 116. + +Page's regulator, 260. + +Panclastite, 152. + +Percentage composition of nitro-glycerine, 18. + +Perkin on magnetic rotation of nitro-glycerine, 19. + +Phenol, tri-nitro-phenol, 152. + +Picric acid, 152, 231. + powders, 157, 189. + +Picrates, 154, 231. + +Polarised light and nitro-cellulose, 218. + +Position of the NO_{2} group in nitro-explosives, 2, 3, 16. + +Prentice's nitric acid plant, 43. + +Pressure gauge, 282. + +Primers of gun-cotton, 166. + +Properties of dynamite, 116. + gelatine compounds, 130. + +Pulping gun-cotton, 65. + +Pyroxyline for celluloid, 96. + solvents for, 101. + + + +Quinan's foot-pound machine, 280. + + + +Raoult's law and N.G., 21. + +Reworked gun-cotton, 78. + +Rhenish dynamite, 119. + +Roburite, properties and manufacture of, 138. + Bedson's report on, 140. + Orsman on gases produced by explosion of, 142. + +Romit, 148. + + + +Sarrau and Vieille, gases obtained from ignition of dynamite, 19. + +Sayers, 50. + +Scheme for analysis of explosives, 213. + +Schultze's powder, 183. + +Schultze-Tieman method of determining nitrogen, 224. + +Securite, 144. + +Separation of nitro-glycerine from mixed acids, 35. + +Shimose, 156. + +Silver test for glycerine, 233. + +Smokeless powders, 168. + +Smokeless diamond, 190. + +Snyder's powder, 193. + +Sobrero discovered nitro-glycerine, 14. + +Sodium nitrate, analysis of, 239. + +Soluble and insoluble nitro-cellulose, 51. + +Solubility of nitro-glycerine, 20. + +Solvents for soluble gun-cotton, 52, 101. + +Solubility test for gun-cotton, 214. + +Specific gravity of explosives, 270. + +Sprengel's explosives, 151. + +Stowmarket, manufacture of gun-cotton at, 57. + +Sulphuric acid, determination of strength of, 24. + +Sy on test for nitro-cellulose, 269. + + + +Temperature of nitration of nitro-glycerine, 29. + +Thomson's patents, 73. + +Toluene, 146. + +Tonite, 84, 146. + analysis of, 205. + fumes from, 85. + +Treatment of waste acids, 43. + +Trench's fire-extinguishing compound, 88. + +Trebouillet and De Besancele on celluloid manufacture, 92. + +Tri-nitro-cresol, 158. + +Tri-nitro-toluene, 146. + +Tri-nitro-phenol, 152. + +Tri-nitro-glycerine, 2, 14. + +Troisdorf powder, 191, 192. + +Turpin's melinite, 156. + + + +U.S. naval powder, 180. + +Uses of celluloid, 91, 93, 102. + +Uses of collodion-cotton, 90. + + + +Vaseline, 208. + +Vielle poudre, 190. + +Volney's powder, 148. + +Von Foster's powder, 191. + + + +Walsrode powder, 188. + +W.A. powder, 182. + +Waltham Abbey, manufacture of gun-cotton at, 71. + manufacture of cordite at, 169. + +Walke's pressure gauge results, 289. + +War Office experiments with cordite, 173. + +Washing gun-cotton, 63. + nitro-glycerine, 37. + +Waste acids from nitro-glycerine, 41, 226. + +Weltern powder, 191. + +Werner & Pfleiderer's mixing machine, 124. + +Whirling out the acids from gun-cotton, 62. + +Will's test for nitre-cellulose, 261. + +Wood pulp, 126. + + + +Xylonite Company's process, 96. + + + +Zenger's lightning conductors, 11. + + + +_Printed at_ THE DARLEN PRESS, _Edinburgh_. + + + + + +End of the Project Gutenberg EBook of Nitro-Explosives: A Practical Treatise +by P. 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