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+The Project Gutenberg EBook of The Handbook of Soap Manufacture, by 
+W. H. Simmons and H. A. Appleton
+
+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: The Handbook of Soap Manufacture
+
+Author: W. H. Simmons
+        H. A. Appleton
+
+Release Date: June 7, 2007 [EBook #21724]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK THE HANDBOOK OF SOAP MANUFACTURE ***
+
+
+
+
+Produced by Ben Beasley, Richard Prairie, Josephine Paolucci
+and the Online Distributed Proofreading Team at
+https://www.pgdp.net. (This file was produced from images
+generously made available by The Internet Archive/Million
+Book Project.)
+
+
+
+
+
+
+
+
+
+THE HANDBOOK OF
+
+SOAP MANUFACTURE
+
+BY
+
+W. H. SIMMONS, B.Sc. (LOND.), F.C.S.
+
+AND
+
+H. A. APPLETON
+
+_WITH TWENTY-SEVEN ILLUSTRATIONS_
+
+LONDON
+SCOTT, GREENWOOD & SON
+"THE OIL AND COLOUR TRADES JOURNAL" OFFICES
+8 BROADWAY, LUDGATE HILL, E.C.
+1908
+[_All rights reserved_]
+
+Transcriber's note:
+
+For text: A word surrounded by a cedilla such as ~this~ signifies that
+the word is bolded in the text. A word surrounded by underscores like
+_this_ signifies the word is italics in the text. Greek letters
+are translated into English and are in brackets, e.g. [alpha].
+
+For numbers and equations: Parentheses have been added to clarify
+fractions. Underscores before bracketed numbers/letters in equations
+denote a subscript.
+
+Footnotes have been moved to the end of the chapter and minor typos have
+been corrected.
+
+
+
+
+PREFACE
+
+
+In the general advance of technical knowledge and research during the
+last decade, the Soap Industry has not remained stationary. While there
+has not perhaps been anything of a very revolutionary character, steady
+progress has still been made in practically all branches, and the aim of
+the present work is to describe the manufacture of Household and Toilet
+Soaps as carried out to-day in an up-to-date and well-equipped factory.
+
+In the more scientific portions of the book, an acquaintance with the
+principles of elementary chemistry is assumed, and in this we feel
+justified, as in these days of strenuous competition, no soap-maker can
+hope to compete successfully with his rivals unless he has a sound
+theoretical as well as practical knowledge of the nature of the raw
+materials he uses, and the reactions taking place in the pan, or at
+other stages of the manufacture. We also venture to hope that the work
+may prove useful to Works' Chemists and other Analysts consulted in
+connection with this Industry.
+
+At the same time, in the greater part of the book no chemical knowledge
+is necessary, the subject being treated in such a way that it is hoped
+those who are not directly engaged in the manufacture of soap, but who
+desire a general idea of the subject, will find it of value.
+
+In the sections dealing with the composition and analysis of materials,
+temperatures are expressed in degrees Centigrade, these being now almost
+invariably used in scientific work. In the rest of the book, however,
+they are given in degrees Fahrenheit (the degrees Centigrade being also
+added in brackets), as in the majority of factories these are still
+used.
+
+As regards strengths of solution, in some factories the use of Baumé
+degrees is preferred, whilst in others Twaddell degrees are the custom,
+and we have therefore given the two figures in all cases.
+
+In the chapter dealing with Oils and Fats, their Saponification
+Equivalents are given in preference to Saponification Values, as it has
+been our practice for some years to express our results in this way, as
+suggested by Allen in _Commercial Organic Analysis_, and all our
+records, from which most of the figures for the chief oils and fats are
+taken, are so stated.
+
+For the illustrations, the authors are indebted to Messrs. E. Forshaw &
+Son, Ltd., H. D. Morgan, and W. J. Fraser & Co., Ltd.
+
+W. H. S.
+H. A. A.
+
+LONDON, _September_, 1908.
+
+
+
+
+CONTENTS
+
+
+                                                                       PAGE
+
+CHAPTER I.
+
+INTRODUCTION.                                                             1
+
+Definition of Soap--Properties--Hydrolysis--Detergent Action.
+
+
+CHAPTER II.
+
+CONSTITUTION OF OILS AND FATS, AND THEIR SAPONIFICATION                   6
+
+Researches of Chevreul and Berthelot--Mixed Glycerides--Modern Theories
+of Saponification--Hydrolysis accelerated by (1) HEAT OR ELECTRICITY,
+(2) FERMENTS, Castor-seed Ferment, Steapsin, Emulsin, and (3) CHEMICAL
+REAGENTS, Sulphuric Acid, Twitchell's Reagent, Hydrochloric Acid, Lime,
+Magnesia, Zinc Oxide, Soda and Potash.
+
+
+CHAPTER III.
+
+RAW MATERIALS USED IN SOAP-MAKING                                        24
+
+Fats and Oils--Waste Fats--Fatty Acids--Less-known Oils and Fats of Limited
+Use--Various New Fats and Oils Suggested for Soap-making--Rosin--Alkali
+(Caustic and Carbonated)--Water--Salt--Soap-stock.
+
+
+CHAPTER IV.
+
+BLEACHING AND TREATMENT OF RAW MATERIALS INTENDED FOR
+  SOAP-MAKING                                                            41
+
+Palm Oil--Cotton-seed Oil--Cotton-seed "Foots"--Vegetable Oils--Animal
+Fats--Bone Fat--Rosin.
+
+
+CHAPTER V.
+
+SOAP-MAKING                                                              45
+
+Classification of Soaps--Direct combination of Fatty Acids with
+Alkali--Cold Process Soaps--Saponification under Increased or Diminished
+Pressure--Soft Soap--Marine Soap--Hydrated Soaps, Smooth and
+Marbled--Pasting or Saponification--Graining Out--Boiling on
+Strength--Fitting--Curd Soaps--Curd Mottled--Blue and Grey Mottled
+Soaps--Milling Base--Yellow Household Soaps--Resting of Pans and
+Settling of Soap--Utilisation of Nigres--Transparent soaps--Saponifying
+Mineral Oil--Electrical Production of Soap.
+
+
+CHAPTER VI.
+
+TREATMENT OF SETTLED SOAP                                                60
+
+Cleansing--Crutching--Liquoring of Soaps--Filling--Neutralising,
+Colouring and Perfuming--Disinfectant
+Soaps--Framing--Slabbing--Barring--Open and Close
+Piling--Drying--Stamping--Cooling.
+
+
+CHAPTER VII.
+
+TOILET, TEXTILE AND MISCELLANEOUS SOAPS                                  77
+
+Toilet Soaps--Cold Process soaps--Settled Boiled Soaps--Remelted
+Soaps--Milled Soaps--Drying--Milling and Incorporating Colour, Perfume,
+or Medicament--Perfume--Colouring matter--Neutralising and Superfatting
+Material--Compressing--Cutting--Stamping--Medicated Soaps--Ether
+Soap--Floating Soaps--Shaving Soaps--Textile Soaps--Soaps for Woollen,
+Cotton and Silk Industries--Patent Textile Soaps--Miscellaneous Soaps.
+
+
+CHAPTER VIII.
+
+SOAP PERFUMES                                                            95
+
+Essential Oils--Source and Preparation--Properties--Artificial and
+Synthetic Perfumes.
+
+
+CHAPTER IX.
+
+GLYCERINE MANUFACTURE AND PURIFICATION                                  111
+
+Treatment of Lyes--Evaporation to Crude
+Glycerine--Distillation--Distilled and Dynamite Glycerine--Chemically
+Pure Glycerine--Animal Charcoal for Decolorisation--Glycerine obtained
+by other methods of Saponification--Yield of Glycerine from Fats and
+Oils.
+
+
+CHAPTER X.
+
+ANALYSIS OF RAW MATERIALS, SOAP, AND GLYCERINE                          117
+
+Fats and Oils--Alkalies and Alkali Salts--Essential Oils--Soap--Lyes--Crude
+Glycerine.
+
+
+CHAPTER XI.
+
+STATISTICS OF THE SOAP INDUSTRY                                         140
+
+
+APPENDIX A.
+
+COMPARISON OF DEGREES, TWADDELL AND BAUMÉ, WITH ACTUAL DENSITIES        147
+
+
+APPENDIX B.
+
+COMPARISON OF DIFFERENT THERMOMETRIC SCALES                             148
+
+
+APPENDIX C.
+
+TABLE OF THE SPECIFIC GRAVITIES OF SOLUTIONS OF CAUSTIC SODA            149
+
+
+APPENDIX D.
+
+TABLE OF STRENGTH OF CAUSTIC POTASH SOLUTIONS AT 60° F.                 151
+
+
+INDEX                                                                   153
+
+
+
+
+CHAPTER I.
+
+INTRODUCTION.
+
+     _Definition of Soap--Properties--Hydrolysis--Detergent Action._
+
+
+It has been said that the use of soap is a gauge of the civilisation of
+a nation, but though this may perhaps be in a great measure correct at
+the present day, the use of soap has not always been co-existent with
+civilisation, for according to Pliny (_Nat. Hist._, xxviii., 12, 51)
+soap was first introduced into Rome from Germany, having been discovered
+by the Gauls, who used the product obtained by mixing goats' tallow and
+beech ash for giving a bright hue to the hair. In West Central Africa,
+moreover, the natives, especially the Fanti race, have been accustomed
+to wash themselves with soap prepared by mixing crude palm oil and water
+with the ashes of banana and plantain skins. The manufacture of soap
+seems to have flourished during the eighth century in Italy and Spain,
+and was introduced into France some five hundred years later, when
+factories were established at Marseilles for the manufacture of
+olive-oil soap. Soap does not appear to have been made in England until
+the fourteenth century, and the first record of soap manufacture in
+London is in 1524. From this time till the beginning of the nineteenth
+century the manufacture of soap developed very slowly, being essentially
+carried on by rule-of-thumb methods, but the classic researches of
+Chevreul on the constitution of fats at once placed the industry upon a
+scientific basis, and stimulated by Leblanc's discovery of a process for
+the commercial manufacture of caustic soda from common salt, the
+production of soap has advanced by leaps and bounds until it is now one
+of the most important of British industries.
+
+_Definition of Soap_.--The word soap (Latin _sapo_, which is cognate
+with Latin _sebum_, tallow) appears to have been originally applied to
+the product obtained by treating tallow with ashes. In its strictly
+chemical sense it refers to combinations of fatty acids with metallic
+bases, a definition which includes not only sodium stearate, oleate and
+palmitate, which form the bulk of the soaps of commerce, but also the
+linoleates of lead, manganese, etc., used as driers, and various
+pharmaceutical preparations, _e.g._, mercury oleate (_Hydrargyri
+oleatum_), zinc oleate and lead plaster, together with a number of other
+metallic salts of fatty acids. Technically speaking, however, the
+meaning of the term soap is considerably restricted, being generally
+limited to the combinations of fatty acids and alkalies, obtained by
+treating various animal or vegetable fatty matters, or the fatty acids
+derived therefrom, with soda or potash, the former giving hard soaps,
+the latter soft soaps.
+
+The use of ammonia as an alkali for soap-making purposes has often been
+attempted, but owing to the ease with which the resultant soap is
+decomposed, it can scarcely be looked upon as a product of much
+commercial value.
+
+H. Jackson has, however, recently patented (Eng. Pat. 6,712, 1906) the
+use of ammonium oleate for laundry work. This detergent is prepared in
+the wash-tub at the time of use, and it is claimed that goods are
+cleansed by merely immersing them in this solution for a short time and
+rinsing in fresh water.
+
+Neither of the definitions given above includes the sodium and potassium
+salts of rosin, commonly called rosin soap, for the acid constituents of
+rosin have been shown to be aromatic, but in view of the analogous
+properties of these resinates to true soap, they are generally regarded
+as legitimate constituents of soap, having been used in Great Britain
+since 1827, and receiving legislative sanction in Holland in 1875.
+
+Other definitions of soap have been given, based not upon its
+composition, but upon its properties, among which may be mentioned that
+of Kingzett, who says that "Soap, considered commercially, is a body
+which on treatment with water liberates alkali," and that of Nuttall,
+who defines soap as "an alkaline or unctuous substance used in washing
+and cleansing".
+
+_Properties of Soap._--Both soda and potash soaps are readily soluble in
+either alcohol or hot water. In cold water they dissolve more slowly,
+and owing to slight decomposition, due to hydrolysis (_vide infra_), the
+solution becomes distinctly turbid. Sodium oleate is peculiar in not
+undergoing hydrolysis except in very dilute solution and at a low
+temperature. On cooling a hot soap solution, a jelly of more or less
+firm consistence results, a property possessed by colloidal bodies, such
+as starch and gelatine, in contradistinction to substances which under
+the same conditions deposit crystals, due to diminished solubility of
+the salt at a lower temperature.
+
+Krafft (_Journ. Soc. Chem. Ind._, 1896, 206, 601; 1899, 691; and 1902,
+1301) and his collaborators, Wiglow, Strutz and Funcke, have
+investigated this property of soap solutions very fully, the researches
+extending over several years. In the light of their more recent work,
+the molecules, or definite aggregates of molecules, of solutions which
+become gelatinous on cooling move much more slowly than the molecules in
+the formation of a crystal, but there is a definite structure, although
+arranged differently to that of a crystal. In the case of soda soaps the
+colloidal character increases with the molecular weight of the fatty
+acids.
+
+Soda soaps are insoluble in concentrated caustic lyes, and, for the most
+part, in strong solutions of sodium chloride, hence the addition of
+caustic soda or brine to a solution of soda soap causes the soap to
+separate out and rise to the surface. Addition of brine to a solution of
+potash soap, on the other hand, merely results in double decomposition,
+soda soap and potassium chloride being formed, thus:--
+
+    C_{17}H_{35}COOK + NaCl   =  C_{17}H_{35}COONa + KCl
+      potassium       sodium       sodium          potassium
+      stearate       chloride     stearate         chloride
+
+The solubility of the different soaps in salt solution varies very
+considerably. Whilst sodium stearate is insoluble in a 5 per cent.
+solution of sodium chloride, sodium laurate requires a 17 per cent.
+solution to precipitate it, and sodium caproate is not thrown out of
+solution even by a saturated solution.
+
+_Hydrolysis of Soap_.--The term "hydrolysis" is applied to any
+resolution of a body into its constituents where the decomposition is
+brought about by the action of water, hence when soap is treated with
+_cold_ water, it is said to undergo hydrolysis, the reaction taking
+place being represented in its simplest form by the equation:--
+
+    2NaC_{18}H_{35}O_{2} + H_{2}O  =  NaOH +   HNa(C_{18}H_{35}O_{2})_{2}
+    sodium                  water    caustic      acid sodium
+    stearate                         soda         stearate
+
+The actual reaction which occurs has been the subject of investigation
+by many chemists, and very diverse conclusions have been arrived at.
+Chevreul, the pioneer in the modern chemistry of oils and fats, found
+that a small amount of alkali was liberated, as appears in the above
+equation, together with the formation of an acid salt, a very minute
+quantity of free fatty acid remaining in solution. Rotondi (_Journ. Soc.
+Chem. Ind._, 1885, 601), on the other hand, considered that a neutral
+soap, on being dissolved in water, was resolved into a basic and an acid
+salt, the former readily soluble in both hot and cold water, the latter
+insoluble in cold water, and only slightly soluble in hot water. He
+appears, however, to have been misled by the fact that sodium oleate is
+readily soluble in cold water, and his views have been shown to be
+incorrect by Krafft and Stern (_Ber. d. Chem. Ges._, 1894, 1747 and
+1755), who from experiments with pure sodium palmitate and stearate
+entirely confirm the conclusions arrived at by Chevreul.
+
+The extent of dissociation occurring when a soap is dissolved in water
+depends upon the nature of the fatty acids from which the soap is made,
+and also on the concentration of the solution. The sodium salts of
+cocoa-nut fatty acids (capric, caproic and caprylic acids) are by far
+the most easily hydrolysed, those of oleic acid and the fatty acids from
+cotton-seed oil being dissociated more readily than those of stearic
+acid and tallow fatty acids. The decomposition increases with the amount
+of water employed.
+
+The hydrolytic action of water on soap is affected very considerably by
+the presence of certain substances dissolved in the water, particularly
+salts of calcium and magnesium. Caustic soda exerts a marked retarding
+effect on the hydrolysis, as do also ethyl and amyl alcohols and
+glycerol.
+
+_Detergent Action of Soap._--The property possessed by soap of removing
+dirt is one which it is difficult to satisfactorily explain. Many
+theories, more or less complicated, have been suggested, but even now
+the question cannot be regarded as solved.
+
+The explanation commonly accepted is that the alkali liberated by
+hydrolysis attacks any greasy matter on the surface to be cleansed, and,
+as the fat is dissolved, the particles of dirt are loosened and easily
+washed off. Berzelius held this view, and considered that the value of a
+soap depended upon the ease with which it yielded free alkali on
+solution in water.
+
+This theory is considered by Hillyer (_Journ. Amer. Chem. Soc._, 1903,
+524), however, to be quite illogical, for, as he points out, the
+liberated alkali would be far more likely to recombine with the acid or
+acid salt from which it has been separated, than to saponify a neutral
+glyceride, while, further, unsaponifiable greasy matter is removed by
+soap as easily as saponifiable fat, and there can be no question of any
+chemical action of the free alkali in its case. Yet another argument
+against the theory is that hydrolysis is greater in cold and dilute
+solutions, whereas hot concentrated soap solutions are generally
+regarded as having the best detergent action.
+
+Rotondi (_Journ. Soc. Chem. Ind._, 1885, 601) was of the opinion that
+the basic soap, which he believed to be formed by hydrolysis, was alone
+responsible for the detergent action of soap, this basic soap dissolving
+fatty matter by saponification, but, as already pointed out, his theory
+of the formation of a basic soap is now known to be incorrect, and his
+conclusions are therefore invalid.
+
+Several explanations have been suggested, based on the purely physical
+properties of soap solutions. Most of these are probably, at any rate in
+part, correct, and there can be little doubt that the ultimate solution
+of the problem lies in this direction, and that the detergent action of
+soap will be found to depend on many of these properties, together with
+other factors not yet known.
+
+Jevons in 1878 in some researches on the "Brownian movement" or
+"pedesis" of small particles, a movement of the particles which is
+observed to take place when clay, iron oxide, or other finely divided
+insoluble matter is suspended in water, found that the pedetic action
+was considerably increased by soap and sodium silicate, and suggested
+that to this action of soap might be attributed much of its cleansing
+power.
+
+Alder Wright considered that the alkali liberated by hydrolysis in some
+way promoted contact of the water with the substance to be cleansed, and
+Knapp regarded the property of soap solutions themselves to facilitate
+contact of the water with the dirt, as one of the chief causes of the
+efficacy of soap as a detergent.
+
+Another way in which it has been suggested that soap acts as a cleanser
+is that the soap itself or the alkali set free by hydrolysis serves as a
+lubricant, making the dirt less adherent, and thus promoting its
+removal.
+
+The most likely theory yet advanced is that based on the emulsifying
+power of soap solutions. The fact that these will readily form emulsions
+with oils has long been known, and the detergent action of soap has
+frequently been attributed to it, the explanation given being that the
+alkali set free by the water emulsifies the fatty matter always adhering
+to dirt, and carries it away in suspension with the other impurities.
+Experiments by Hillyer (_loc. cit._) show, however, that while N/10
+solution of alkali will readily emulsify a cotton-seed oil containing
+free acidity, no emulsion is produced with an oil from which all the
+acidity has been removed, or with kerosene, whereas a N/10 solution of
+sodium oleate will readily give an emulsion with either, thus proving
+that the emulsification is due to the soap itself, and not to the
+alkali.
+
+Plateau (_Pogg. Ann._, 141, 44) and Quincke (_Wiedmann's. Ann._, 35,
+592) have made very complete researches on the emulsification and
+foaming of liquids and on the formation of bubbles. The former considers
+that there are two properties of a liquid which play an important part
+in the phenomenon, (1) it must have considerable viscosity, and (2) its
+surface tension must be low. Quincke holds similar views, but considers
+that no pure liquid will foam.
+
+Soap solution admirably fulfils Plateau's second condition, its surface
+tension being only about 40 per cent. of that of water, while its
+cohesion is also very small; and it is doubtless to this property that
+its emulsifying power is chiefly due. So far as viscosity is concerned,
+this can have but little influence, for a 1 per cent. solution of sodium
+oleate, which has a viscosity very little different from that of pure
+water, is an excellent emulsifying agent.
+
+Hillyer, to whose work reference has already been made, investigated the
+whole question of detergent action very exhaustively, and, as the result
+of a very large number of experiments, concludes that the cleansing
+power of soap is largely or entirely to be explained by the power which
+it has of emulsifying oily substances, of wetting and penetrating into
+oily textures, and of lubricating texture and impurities so that these
+may be removed easily. It is thought that all these properties may be
+explained by taking into account the low cohesion of the soap solutions,
+and their strong attraction or affinity to oily matter, which together
+cause the low surface tension between soap solution and oil.
+
+
+
+
+CHAPTER II.
+
+CONSTITUTION OF OILS AND FATS, AND THEIR SAPONIFICATION.
+
+     _Researches of Chevreul and Berthelot--Mixed Glycerides--Modern
+     Theories of Saponification--Hydrolysis accelerated by (1) Heat
+     or Electricity, (2) Ferments; Castor-seed Ferment, Steapsin,
+     Emulsin, and (3) Chemical Reagents; Sulphuric Acid, Twitchell's
+     Reagent, Hydrochloric Acid, Lime, Magnesia, Zinc Oxide, Soda
+     and Potash._
+
+
+The term oil is of very wide significance, being applied to substances
+of vastly different natures, both organic and inorganic, but so far as
+soap-making materials are concerned, it may be restricted almost
+entirely to the products derived from animal and vegetable sources,
+though many attempts have been made during the last few years to also
+utilise mineral oils for the preparation of soap. Fats readily become
+oils on heating beyond their melting points, and may be regarded as
+frozen oils.
+
+Although Scheele in 1779 discovered that in the preparation of lead
+plaster glycerol is liberated, soap at that time was regarded as a mere
+mechanical mixture, and the constitution of oils and fats was not
+properly understood. It was Chevreul who showed that the manufacture of
+soap involved a definite chemical decomposition of the oil or fat into
+fatty acid and glycerol, the fatty acid combining with soda, potash, or
+other base, to form the soap, and the glycerol remaining free. The
+reactions with stearin and palmitin (of which tallow chiefly consists)
+and with olein (found largely in olive and cotton-seed oils) are as
+follows:--
+
+          CH_{2}OOC_{18}H_{35}                             CH_{2}OH
+          |                                                |
+          CHOOC_{18}H_{35} + 3NaOH = 3NaOOC_{18}H_{35} +   CHOH
+          |                                                |
+          CH_{2}OOC_{18}H_{35}                             CH_{2}OH
+
+            stearin         sodium       sodium            glycerol
+                           hydroxide     stearate
+
+
+          CH_{2}OOC_{16}H_{31}                             CH_{2}OH
+          |                                                |
+          CHOOC_{16}H_{31} + 3NaOH = 3NaOOC_{16}H_{31} +   CHOH
+          |                                                |
+          CH_{2}OOC_{16}H_{31}                             CH_{2}OH
+
+             palmitin        sodium      sodium            glycerol
+                            hydroxide    palmitate
+
+          CH_{2}OOC_{18}H_{33}                           CH_{2}OH
+          |                                              |
+          CHOOC_{18}H_{33} + 3NaOH = 3NaOOC_{18}H_{33} + CHOH
+          |                                              |
+          CH_{2}OOC_{18}H_{33}                           CH_{2}OH
+
+          olein              sodium    sodium            glycerol
+                            hydroxide  oleate
+
+Berthelot subsequently confirmed Chevreul's investigations by directly
+synthesising the fats from fatty acids and glycerol, the method he
+adopted consisting in heating the fatty acids with glycerol in sealed
+tubes. Thus, for example:--
+
+  3C_{18}H_{35}O_{2}H + C_{3}H_{5}(OH)_{3} = C_{3}H_{5}(C_{18}H_{35}O_{2})_{3}
+  stearic acid           glycerol              tristearin
+
+Since glycerol is a trihydric alcohol, _i.e._, contains three hydroxyl
+(OH) groups, the hydrogen atoms of which are displaceable by acid
+radicles, the above reaction may be supposed to take place in three
+stages. Thus, we may have:--
+
+    (1) C_{18}H_{35}O_{2}H + C_{3}H_{5}(OH)_{3} =
+           C_{3}H_{5}(OH)_{2}C_{18}H_{35}O_{2} + H_{2}O
+                                            monostearin
+
+    (2) C_{18}H_{35}O_{2}H + C_{3}H_{5}(OH)_{2}C_{18}H_{35}O_{2} =
+           C_{3}H_{5}(OH)(C_{18}H_{35}O_{2})_{2} + H_{2}O
+                                            distearin
+
+    (3) C_{18}H_{35}O_{2}H + C_{3}H_{5}(OH)(C_{18}H_{35}O_{2})_{2} =
+           C_{3}H_{5}(C_{18}H_{35}O_{2})_{3} + H_{2}O
+                                            tristearin
+
+There are two possible forms of monoglyceride and diglyceride, according
+to the relative position of the acid radicle, these being termed alpha
+and beta respectively, and represented by the following formulæ, where R
+denotes the acid radicle:--
+
+_Monoglyceride_:--
+
+                   CH_{2}OR                     CH_{2}OH
+                   |                            |
+          (alpha)  CHOH           and (beta)    CHOR
+                   |                            |
+                   CH_{2}OH                     CH_{2}OH
+
+_Diglyceride_:--
+
+                   CH_{2}OR                     CH_{2}OR
+                   |                            |
+          (alpha)  CHOH           and (beta)    CHOR
+                   |                            |
+                   CH_{2}OR                     CH_{2}OH
+
+According to the relative proportions of fatty acid and glycerol used,
+and the temperature to which they were heated, Berthelot succeeded in
+preparing mono-, di- and triglycerides of various fatty acids.
+
+Practically all the oils and fats used in soap-making consist of
+mixtures of these compounds of glycerol with fatty acids, which
+invariably occur in nature in the form of triglycerides.
+
+It was formerly considered that the three acid radicles in any naturally
+occurring glyceride were identical, corresponding to the formula--
+
+          CH_{2}OR
+          |
+          CHOR
+          |
+          CH_{2}OR
+
+where R denotes the acid radicle. Recent work, however, has shown the
+existence of several so-called _mixed glycerides_, in which the
+hydroxyls of the same molecule of glycerol are displaced by two or
+sometimes three different acid radicles.
+
+The first mixed glyceride to be discovered was oleodistearin,
+C_{3}H_{5}(OC_{18}H_{35}O)(OC_{18}H_{35}O)_{2}, obtained by Heise in 1896
+Mkani fat. Hansen has since found that tallow contains oleodipalmitin,
+from C_{3}H_{5}(OC_{18}H_{35}O)(OC_{16}H_{31}O), stearodipalmitin,
+C_{3}H_{5}(OC_{18}H_{35}O)(OC_{16}H_{31}O), oleopalmitostearin,
+C_{3}H_{5}(OC_{18}H_{33}O)(OC_{16}H_{31}O)(OC_{18}H_{35}O) and
+palmitodistearin, CH(OC_{16}H_{31}O)(OC_{18}H_{35}O)_{2}, the latter of
+which has also been obtained by Kreis and Hafner from lard, while Holde
+and Stange have shown that olive oil contains from 1 to 2 per cent. of
+oleodidaturin, C_{3}H_{5}(OC_{18}H_{33}O)(OC_{17}H_{33}O)_{2}, and
+Hehner and Mitchell have obtained indications of mixed glycerides in
+linseed oil (which they consider contains a compound of glycerol with
+two radicles of linolenic acid and one radicle of oleic acid), also in
+cod-liver, cod, whale and shark oils.
+
+In some cases the fatty acids are combined with other bases than
+glycerol. As examples may be cited beeswax, containing myricin or
+myricyl palmitate, and spermaceti, consisting chiefly of cetin or cetyl
+palmitate, and herein lies the essential difference between fats and
+waxes, but as these substances are not soap-making materials, though
+sometimes admixed with soap to accomplish some special object, they do
+not require further consideration.
+
+The principal pure triglycerides, with their formulæ and chief
+constants, are given in the following table:--
+
+[Transcriber's note: Table split to fit on page better.]
+
+---------------------------------------------------------------------
+Glyceride. |          Formula.                   | Chief Occurrence.
+---------------------------------------------------------------------
+Butyrin    | C_{3}H_{5}(O.C_{4}H_{7}O)_{3}       |   Butter fat
+---------------------------------------------------------------------
+Isovalerin | C_{3}H_{5}(O.C_{5}H_{9}O)_{3}       |  Porpoise, dolphin
+---------------------------------------------------------------------
+Caproin    | C_{3}H_{5}(O.C_{6}H_{11}O)_{3}      |   Cocoa-nut and
+           |                                     |    palm-nut oils
+---------------------------------------------------------------------
+Caprylin   | C_{3}H_{5}(O.C_{8}H_{15}O)_{3}      |     Do. do.
+---------------------------------------------------------------------
+Caprin     | C_{3}H_{5}(O.C_{10}H_{19}O)_{3}     |     Do.  do.
+---------------------------------------------------------------------
+Laurin     | C_{3}H_{5}(O.C_{12}H_{23}O)_{3}     |     Do.  do.
+---------------------------------------------------------------------
+Myristin   | C_{3}H_{5}(O.C_{14}H_{27}O)_{3}     |   Nutmeg butter
+---------------------------------------------------------------------
+Palmitin   | C_{3}H_{5}(O.C_{16}H_{31}O)_{3}     |   Palm oil, lard
+---------------------------------------------------------------------
+Stearin    | C_{3}H_{5}(O.C_{18}H_{35}O)_{3}     |   Tallow, lard,
+           |                                     |   cacao butter
+---------------------------------------------------------------------
+Olein      | C_{3}H_{5}(O.C_{18}H_{33}O)_{3}     |   Olive and
+           |                                     |   almond oils
+---------------------------------------------------------------------
+Ricinolein | C_{3}H_{5}(O.C_{18}H_{33}O_{2})_{3} |   Castor oil
+---------------------------------------------------------------------
+
+---------------------------------------------------------------------
+Glyceride.  |   Melting         | Refractive       |  Saponification
+            |  Point, °C.       | Index at 60° C.  |    Equivalent.
+---------------------------------------------------------------------
+Butyrin     |  Liquid at -60    |   1.42015        |     100.7
+---------------------------------------------------------------------
+Isovalerin  |   ...             |     ...          |     114.7
+---------------------------------------------------------------------
+Caproin     |   -25             |   1.42715        |     128.7
+---------------------------------------------------------------------
+Caprylin    |   -8.3            |   1.43316        |     156.7
+---------------------------------------------------------------------
+Caprin      |    31.1           |   1.43697        |     184.7
+---------------------------------------------------------------------
+Laurin      |    45             |   1.44039        |     212.7
+---------------------------------------------------------------------
+Myristin    |    56.5           |   1.44285        |     240.7
+---------------------------------------------------------------------
+Palmitin    |    63-64          |     ...          |     268.7
+---------------------------------------------------------------------
+Stearin     |    71.6           |     ...          |     296.7
+---------------------------------------------------------------------
+Olein       |  Solidifies at -6 |   ...            |     294.7
+---------------------------------------------------------------------
+Ricinolein  |      ...          |   ...            |     310.7
+---------------------------------------------------------------------
+
+Of the above the most important from a soap-maker's point of view are
+stearin, palmitin, olein and laurin, as these predominate in the fats
+and oils generally used in that industry. The presence of stearin and
+palmitin, which are solid at the ordinary temperature, gives firmness to
+a fat; the greater the percentage present, the harder the fat and the
+higher will be the melting point, hence tallows and palm oils are solid,
+firm fats. Where olein, which is liquid, is the chief constituent, we
+have softer fats, such as lard, and liquid oils, as almond, olive and
+cotton-seed.
+
+_Stearin_ (Tristearin) can be prepared from tallow by crystallisation
+from a solution in ether, forming small crystals which have a bright
+pearly lustre. The melting point of stearin appears to undergo changes
+and suggests the existence of distinct modifications. When heated to 55°
+C. stearin liquefies; with increase of temperature it becomes solid, and
+again becomes liquid at 71.6° C. If this liquid be further heated to 76°
+C., and allowed to cool, it will not solidify until 55° C. is reached,
+but if the liquid at 71.6° C. be allowed to cool, solidification will
+occur at 70° C.
+
+_Palmitin_ (Tripalmitin) may be obtained by heating together palmitic
+acid and glycerol, repeatedly boiling the resulting product with strong
+alcohol, and allowing it to crystallise. Palmitin exists in scales,
+which have a peculiar pearly appearance, and are greasy to the touch.
+After melting and solidifying, palmitin shows no crystalline fracture;
+when heated to 46° C. it melts to a liquid which becomes solid on
+further heating, again liquefying when 61.7° C. is reached, and becoming
+cloudy, with separation of crystalline particles. At 63° C. it is quite
+clear, and this temperature is taken as the true melting point. It has
+been suggested that the different changes at the temperatures mentioned
+are due to varying manipulation, such as rate at which the temperature
+is raised, and the initial temperature of the mass when previously cool.
+
+_Olein_ (Triolein) is an odourless, colourless, tasteless oil, which
+rapidly absorbs oxygen and becomes rancid. It has been prepared
+synthetically by heating glycerol and oleic acid together, and may be
+obtained by submitting olive oil to a low temperature for several days,
+when the liquid portion may be further deprived of any traces of stearin
+and palmitin by dissolving in alcohol. Olein may be distilled _in vacuo_
+without decomposition taking place.
+
+_Laurin_ (Trilaurin) may be prepared synthetically from glycerol and
+lauric acid. It crystallises in needles, melting at 45°-46° C., which
+are readily soluble in ether, but only slightly so in cold absolute
+alcohol. Scheij gives its specific gravity, _d_60°/4° = 0.8944. Laurin
+is the chief constituent of palm-kernel oil, and also one of the
+principal components of cocoa-nut oil.
+
+_Fatty Acids._--When a fat or oil is saponified with soda or potash, the
+resulting soap dissolved in hot water, and sufficient dilute sulphuric
+acid added to decompose the soap, an oily layer gradually rises to the
+surface of the liquid, which, after clarifying by warming and washing
+free from mineral acid, is soluble in alcohol and reddens blue litmus
+paper. This oily layer consists of the "fatty acids" or rather those
+insoluble in water, acids like acetic, propionic, butyric, caproic,
+caprylic and capric, which are all more or less readily soluble in
+water, remaining for the most part dissolved in the aqueous portion. All
+the acids naturally present in oils and fats, whether free or combined,
+are monobasic in character, that is to say, contain only one
+carboxyl--CO.OH group. The more important fatty acids may be classified
+according to their chemical constitution into five homologous series,
+having the general formulæ:--
+
+            I. Stearic series     C_{n}H_{2n+1}COOH
+           II. Oleic series       C_{n}H_{2n-1}COOH
+          III. Linolic series     C_{n}H_{2n-3}COOH
+           IV. Linolenic series   C_{n}H_{2n-5}COOH
+            V. Ricinoleic series  C_{n}H_{2n-7}COOH
+
+I. _Stearic Series._--The principal acids of this series, together with
+their melting points and chief sources, are given in the following
+table:--
+
+-------------------------------------------------------------------------------
+Acid.          | Formula.          | Melting | Found in
+               |                   | Point,  |
+               |                   | °C.     |
+-------------------------------------------------------------------------------
+Acetic         | CH_{3}COOH        | 17      | Macassar oil.
+------------------------------------------------------------------------------
+Butyric        | C_{3}H_{7}COOH    |  ...    | Butter, Macassar oil.
+------------------------------------------------------------------------------
+Isovaleric     | C_{4}H_{9}COOH    |  ...    | Porpoise and dolphin oils.
+------------------------------------------------------------------------------
+Caproic        | C_{5}H_{11}COOH   |  ...    | Butter, cocoa-nut oil.
+------------------------------------------------------------------------------
+Caprylic       | C_{7}H_{15}COOH   | 15      | Butter, cocoa-nut oil,
+               |                   |         | Limburg cheese.
+------------------------------------------------------------------------------
+Capric         | C_{9}H_{19}COOH   | 30      | Butter, cocoa-nut oil.
+------------------------------------------------------------------------------
+Lauric         | C_{11}H_{23}COOH  | 44      | Cocoa-nut oil, palm-kernel oil.
+------------------------------------------------------------------------------
+Ficocerylic    | C_{12}H_{25}COOH  |   ...   | Pisang wax.
+------------------------------------------------------------------------------
+Myristic       | C_{13}H_{27}COOH  | 54      | Nutmeg butter, liver fat,
+               |                   |         | cocoa-nut oil, dika fat,
+               |                   |         | croton oil.
+------------------------------------------------------------------------------
+Palmitic       | C_{15}H_{31}COOH  | 62.5    | Palm oil, most animal fats.
+------------------------------------------------------------------------------
+Daturic        | C_{16}H_{33}COOH  |         | Oil of Datura Stramonium.
+------------------------------------------------------------------------------
+Stearic        | C_{17}H_{35}COOH  | 69      | Tallow, lard, most solid
+               |                   |         | animal fats.
+------------------------------------------------------------------------------
+Arachidic      | C_{19}H_{39}COOH  | 75      | Arachis or earth-nut oil,
+               |                   |         | rape and mustard-seed oils.
+------------------------------------------------------------------------------
+Behenic        | C_{21}H_{43}COOH  |  ...    | Ben oil, black mustard-seed
+               |                   |         | oil, rape oil.
+------------------------------------------------------------------------------
+Lignoceric     | C_{23}H_{47}COOH  | 80.5    | Arachis oil.
+------------------------------------------------------------------------------
+Carnaubic      | C_{23}H_{47}COOH  |  ...    | Carnauba wax.
+------------------------------------------------------------------------------
+Pisangcerylic  | C_{23}H_{47}COOH  |  ...    | Pisang wax.
+------------------------------------------------------------------------------
+Hyænic         | C_{24}H_{49}COOH  |  ...    | Hyæna fat.
+------------------------------------------------------------------------------
+Cerotic        | C_{25}H_{51}COOH  | 78      | Beeswax, China wax, spermaceti.
+------------------------------------------------------------------------------
+Melissic       | C_{29}H_{59}COOH  | 89      | Beeswax.
+------------------------------------------------------------------------------
+Psyllostearylic| C_{32}H_{65}COOH  |  ...    | Psylla wax.
+------------------------------------------------------------------------------
+Theobromic     | C_{63}H_{127}COOH |  ...    | Cacao butter
+------------------------------------------------------------------------------
+
+Medullic and margaric acids, which were formerly included in this
+series, have now been shown to consist of mixtures of stearic and
+palmitic, and stearic palmitic and oleic acids respectively.
+
+The acids of this group are saturated compounds, and will not combine
+directly with iodine or bromine. The two first are liquid at ordinary
+temperatures, distil without decomposition, and are miscible with water
+in all proportions; the next four are more or less soluble in water and
+distil unchanged in the presence of water, as does also lauric acid,
+which is almost insoluble in cold water, and only slightly dissolved by
+boiling water. The higher acids of the series are solid, and are
+completely insoluble in water. All these acids are soluble in warm
+alcohol, and on being heated with solid caustic alkali undergo no
+change.
+
+II. _Oleic Series:_--
+
+--------------------------------------------------------------------------
+Acid.       | Formula.          | Melting |   Found in
+            |                   | Point,  |
+            |                   | °C.     |
+--------------------------------------------------------------------------
+Tiglic      | C_{4}H_{7}COOH    | 64.5    |   Croton oil.
+--------------------------------------------------------------------------
+Moringic    | C_{14}H_{27}COOH  |  0      |   Ben oil.
+--------------------------------------------------------------------------
+Physetoleic | C_{15}H_{29}COOH  | 30      |   Sperm oil.
+--------------------------------------------------------------------------
+Hypogæic    | C_{15}H_{29}COOH  | 33      |   Arachis and maize oils.
+--------------------------------------------------------------------------
+Oleic       | C_{17}H_{33}COOH  | 14      |   Most oils and fats.
+--------------------------------------------------------------------------
+Rapic       | C_{17}H_{33}COOH  | ...     |   Rape oil.
+--------------------------------------------------------------------------
+Doeglic     | C_{18}H_{35}COOH  | ...     |   Bottle-nose oil.
+--------------------------------------------------------------------------
+Erucic      | C_{21}H_{41}COOH  | 34      |   Mustard oils, marine animal
+            |                   |         |     oils, rape oil.
+--------------------------------------------------------------------------
+
+The unsaturated nature of these acids renders their behaviour with
+various reagents entirely different from that of the preceding series.
+Thus, they readily combine with bromine or iodine to form addition
+compounds, and the lower members of the series are at once reduced, on
+treatment with sodium amalgam in alkaline solution, to the corresponding
+saturated acids of Series I. Unfortunately, this reaction does not apply
+to the higher acids such as oleic acid, but as the conversion of the
+latter into solid acids is a matter of some technical importance from
+the point of view of the candle-maker, a number of attempts have been
+made to effect this by other methods.
+
+De Wilde and Reychler have shown that by heating oleic acid with 1 per
+cent. of iodine in autoclaves up to 270°-280° C., about 70 per cent. is
+converted into stearic acid, and Zürer has devised (German Patent
+62,407) a process whereby the oleic acid is first converted by the
+action of chlorine into the dichloride, which is then reduced with
+nascent hydrogen. More recently Norman has secured a patent (English
+Patent 1,515, 1903) for the conversion of unsaturated fatty acids of
+Series II. into the saturated compounds of Series I., by reduction with
+hydrogen or water-gas in the presence of finely divided nickel, cobalt
+or iron. It is claimed that by this method oleic acid is completely
+transformed into stearic acid, and that the melting point of tallow
+fatty acids is raised thereby about 12° C.
+
+Another method which has been proposed is to run the liquid olein over
+a series of electrically charged plates, which effects its reduction to
+stearin.
+
+Stearic acid is also formed by treating oleic acid with fuming hydriodic
+acid in the presence of phosphorus, while other solid acids are obtained
+by the action of sulphuric acid or zinc chloride on oleic acid.
+
+Acids of Series II. may also be converted into saturated acids by
+heating to 300°C. with solid caustic potash, which decomposes them into
+acids of the stearic series with liberation of hydrogen. This reaction,
+with oleic acid, for example, is generally represented by the equation--
+
+  C_{18}H_{34}O_{2} + 2KOH = KC_{2}H_{3}O_{2} + KC_{16}H_{31}O_{2} + H_{2},
+
+though it must be really more complex than this indicates, for, as Edmed
+has pointed out, oxalic acid is also formed in considerable quantity.
+The process on a commercial scale has now been abandoned.
+
+One of the most important properties of this group of acids is the
+formation of isomeric acids of higher melting point on treatment with
+nitrous acid, generally termed the _elaidin reaction_. Oleic acid, for
+example, acted upon by nitrous acid, yields elaidic acid, melting at
+45°, and erucic acid gives brassic acid, melting at 60°C. This reaction
+also occurs with the neutral glycerides of these acids, olein being
+converted into elaidin, which melts at 32°C.
+
+The lead salts of the acids of this series are much more soluble in
+ether, and the lithium salts more soluble in alcohol than those of the
+stearic series, upon both of which properties processes have been based
+for the separation of the solid from the liquid fatty acids.
+
+III. _Linolic Series:_--
+
+--------------------------------------------------------------------------
+Acid.        |  Formula.        | Melting    | Found in
+             |                  | Point,     |
+             |                  | °C.        |
+--------------------------------------------------------------------------
+Elæomargaric | C_{16}H_{29}COOH |  ...       |  Chinese-wood oil.
+--------------------------------------------------------------------------
+Elæostearic  | C_{16}H_{29}COOH |  71        |  Chinese-wood oil.
+--------------------------------------------------------------------------
+Linolic      | C_{17}H_{31}COOH |  Fluid     |  Linseed, cotton-seed and
+             |                  |            |  maize oils.
+--------------------------------------------------------------------------
+Tariric      | C_{17}H_{31}COOH |  50.5      |  Tariri-seed oil.
+--------------------------------------------------------------------------
+Telfairic    | C_{17}H_{31}COOH |  Fluid     |  Telfairia oil.
+--------------------------------------------------------------------------
+
+These acids readily combine with bromine, iodine, or oxygen. They are
+unaffected by nitrous acid, and their lead salts are soluble in ether.
+
+IV. _Linolenic Series:_--
+
+--------------------------------------------------------------------
+Acid.        |  Formula.         | Found in
+--------------------------------------------------------------------
+Linolenic    |  C_{17}H_{29}COOH | Linseed oil.
+--------------------------------------------------------------------
+Isolinolenic |  C_{17}H_{29}COOH | Linseed oil.
+--------------------------------------------------------------------
+Jecoric      |  C_{17}H_{29}COOH | Cod-liver and marine animal oils.
+--------------------------------------------------------------------
+
+These acids are similar in properties to those of Class III., but
+combine with six atoms of bromine or iodine, whereas the latter combine
+with only four atoms.
+
+V. _Ricinoleic Series:_--
+
+ -----------------------------------------------------------
+|            |                      |         |             |
+|    Acid.   |        Formula.      | Melting |  Found in   |
+|            |                      |  Point, |             |
+|            |                      |   °C.   |             |
+|------------|----------------------|---------|-------------|
+|            |                      |         |             |
+| Ricinoleic | C_{17}H_{22}(OH)COOH |   4-5   | Castor oil. |
+ -----------------------------------------------------------
+
+This acid combines with two atoms of bromine or iodine, and is converted
+by nitrous acid into the isomeric ricinelaidic acid, which melts at
+52°-53° C. Pure ricinoleic acid, obtained from castor oil, is optically
+active, its rotation being [alpha]_{d} +6° 25'.
+
+_Hydrolysis or Saponification of Oils and Fats._--The decomposition of a
+triglyceride, brought about by caustic alkalies in the formation of
+soap, though generally represented by the equation already given (pp. 6
+and 7)--
+
+    C_{3}H_{5}(OR) + 3NaOH = C_{3}H_{5}(OH)_{3} + 3RONa,
+
+is not by any means such a simple reaction.
+
+In the first place, though in this equation no water appears, the
+presence of the latter is found to be indispensable for saponification
+to take place; in fact, the water must be regarded as actually
+decomposing the oil or fat, caustic soda or potash merely acting as a
+catalytic agent. Further, since in the glycerides there are three acid
+radicles to be separated from glycerol, their saponification can be
+supposed to take place in three successive stages, which are the
+converse of the formation of mono- and diglycerides in the synthesis of
+triglycerides from fatty acids and glycerine. Thus, the above equation
+may be regarded as a summary of the following three:--
+
+                           _                        _
+                          | OR                     | OH
+          (i.) C_{3}H_{5} | OR + NaOH = C_{3}H_{5} | OR + RONa
+                          |_OR                     |_OR
+                            _                        _
+                           | OH                     | OH
+          (ii.) C_{3}H_{5} | OR + NaOH = C_{3}H_{5} | OR + RONa
+                           |_OR                     |_OH
+                             _                        _
+                            | OH                     | OH
+          (iii.) C_{3}H_{5} | OR + NaOH = C_{3}H_{5} | OH + RONa
+                            |_OH                     |_OH
+
+Geitel and Lewkowitsch, who have studied this question from the physical
+and chemical point of view respectively, are of opinion that when an
+oil or fat is saponified, these three reactions do actually occur side
+by side, the soap-pan containing at the same time unsaponified
+triglyceride, diglyceride, monoglyceride, glycerol and soap.
+
+This theory is not accepted, however, by all investigators. Balbiano and
+Marcusson doubt the validity of Lewkowitsch's conclusions, and Fanto,
+experimenting on the saponification of olive oil with caustic potash, is
+unable to detect the intermediate formation of any mono- or diglyceride,
+and concludes that in homogeneous solution the saponification is
+practically quadrimolecular. Kreeman, on the other hand, from
+physico-chemical data, supports the view of Geitel and Lewkowitsch that
+saponification is bimolecular, and though the evidence seems to favour
+this theory, the matter cannot be regarded as yet definitely settled.
+
+Hydrolysis can be brought about by water alone, if sufficient time is
+allowed, but as the process is extremely slow, it is customary in
+practice to accelerate the reaction by the use of various methods, which
+include (i.) the application of heat or electricity, (ii.) action of
+enzymes, and (iii.) treatment with chemicals; the accelerating effect of
+the two latter methods is due to their emulsifying power.
+
+The most usual method adopted in the manufacture of soap is to hydrolyse
+the fat or oil by caustic soda or potash, the fatty acids liberated at
+the same time combining with the catalyst, _i.e._, soda or potash, to
+form soap. Hitherto the other processes of hydrolysis have been employed
+chiefly for the preparation of material for candles, for which purpose
+complete separation of the glycerol in the first hydrolysis is not
+essential, since the fatty matter is usually subjected to a second
+treatment with sulphuric acid to increase the proportion of solid fatty
+acids. The colour of the resulting fatty acids is also of no importance,
+as they are always subjected to distillation.
+
+During the last few years, however, there has been a growing attempt to
+first separate the glycerol from the fatty acids, and then convert the
+latter into soap by treatment with the carbonates of soda or potash,
+which are of course considerably cheaper than the caustic alkalies, but
+cannot be used in the actual saponification of a neutral fat. The two
+processes chiefly used for this purpose are those in which the reaction
+is brought about by enzymes or by Twitchell's reagent.
+
+I. _Application of Heat or Electricity._--Up to temperatures of 150° C.
+the effect of water on oils and fats is very slight, but by passing
+superheated steam through fatty matter heated to 200°-300° C. the
+neutral glycerides are completely decomposed into glycerol and fatty
+acids according to the equation--
+
+    C_{3}H_{5}(OR)_{3} + 3H.OH = C_{3}H_{5}(OH)_{3} + 3ROH.
+
+The fatty acids and glycerol formed distil over with the excess of
+steam, and by arranging a series of condensers, the former, which
+condense first, are obtained almost alone in the earlier ones, and an
+aqueous solution of glycerine in the later ones. This method of
+preparation of fatty acids is extensively used in France for the
+production of stearine for candle-manufacture, but the resulting
+product is liable to be dark coloured, and to yield a dark soap. To
+expose the acids to heat for a minimum of time, and so prevent
+discoloration, Mannig has patented (Germ. Pat. 160,111) a process
+whereby steam under a pressure of 8 to 10 atmospheres is projected
+against a baffle plate mounted in a closed vessel, where it mixes with
+the fat or oil in the form of a spray, the rate of hydrolysis being
+thereby, it is claimed, much increased.
+
+Simpson (Fr. Pat. 364,587) has attempted to accelerate further the
+decomposition by subjecting oils or fats to the simultaneous action of
+heat and electricity. Superheated steam is passed into the oil, in which
+are immersed the two electrodes connected with a dynamo or battery, the
+temperature not being allowed to exceed 270° C.
+
+II. _Action of Enzymes._--It was discovered by Muntz in 1871 (_Annales
+de Chemie_, xxii.) that during germination of castor seeds a quantity of
+fatty acid was developed in the seeds, which he suggested might be due
+to the decomposition of the oil by the embryo acting as a ferment.
+Schutzenberger in 1876 showed that when castor seeds are steeped in
+water, fatty acids and glycerol are liberated, and attributed this to
+the hydrolytic action of an enzyme present in the seeds. No evidence of
+the existence of such a ferment was adduced, however, till 1890, when
+Green (_Roy. Soc. Proc._, 48, 370) definitely proved the presence in the
+seeds of a ferment capable of splitting up the oil into fatty acid and
+glycerol.
+
+The first experimenters to suggest any industrial application of this
+enzymic hydrolysis were Connstein, Hoyer and Wartenburg, who
+(_Berichte_, 1902, 35, pp. 3988-4006) published the results of a lengthy
+investigation of the whole subject. They found that tallow, cotton-seed,
+palm, olive, almond, and many other oils, were readily hydrolysed by the
+castor-seed ferment in the presence of dilute acid, but that cocoa-nut
+and palm-kernel oils only decomposed with difficulty. The presence of
+acidity is essential for the hydrolysis to take place, the most suitable
+strength being one-tenth normal, and the degree of hydrolysis is
+proportional to the quantity of ferment present. Sulphuric, phosphoric,
+acetic or butyric acids, or sodium bisulphate, may be used without much
+influence on the result. Butyric acid is stated to be the best, but in
+practice is too expensive, and acetic acid is usually adopted. The
+emulsified mixture should be allowed to stand for twenty-four hours, and
+the temperature should not exceed 40° C.; at 50° C. the action is
+weakened, and at 100° C. ceases altogether.
+
+Several investigators have since examined the hydrolysing power of
+various other seeds, notably Braun and Behrendt (_Berichte_, 1903, 36,
+1142-1145, 1900-1901, and 3003-3005), who, in addition to confirming
+Connstein, Hoyer and Wartenburg's work with castor seeds, have made
+similar experiments with jequirity seeds (_Abrus peccatorius_)
+containing the enzyme abrin, emulsin from crushed almonds, the leaves of
+_Arctostaphylos Uva Ursi_, containing the glucoside arbutin, myrosin
+from black mustard-seed, gold lac (_Cheirantus cheiri_) and crotin from
+croton seeds. Jequirity seeds were found to have a stronger decomposing
+action on lanoline and carnauba wax than the castor seed, but only
+caused decomposition of castor oil after the initial acidity was first
+neutralised with alkali. Neither emulsin, arbutin nor crotin have any
+marked hydrolytic action on castor oil, but myrosin is about half as
+active as castor seeds, except in the presence of potassium myronate,
+when no decomposition occurs.
+
+S. Fokin (_J. russ. phys. chem. Ges._, 35, 831-835, and _Chem. Rev.
+Fett. u. Harz. Ind._, 1904, 30 _et seq._) has examined the hydrolytic
+action of a large number of Russian seeds, belonging to some thirty
+different families, but although more than half of these brought about
+the hydrolysis of over 10 per cent. of fat, he considers that in only
+two cases, _viz._, the seeds of _Chelidonium majus_ and _Linaria
+vulgaris_, is the action due to enzymes, these being the only two seeds
+for which the yield of fatty acids is proportional to the amount of seed
+employed, while in many instances hydrolysis was not produced when the
+seeds were old. The seeds of _Chelidonium majus_ were found to have as
+great, and possibly greater, enzymic activity than castor seeds, but
+those of _Linaria_ are much weaker, twenty to thirty parts having only
+the same lipolytic activity as four to five parts of castor seeds.
+
+The high percentage of free acids found in rice oil has led C. A. Brown,
+jun. (_Journ. Amer. Chem. Soc._, 1903, 25, 948-954), to examine the rice
+bran, which proves to have considerable enzymic activity, and rapidly
+effects the hydrolysis of glycerides.
+
+The process for the utilisation of enzymic hydrolysis in the separation
+of fatty acids from glycerine on the industrial scale, as originally
+devised by Connstein and his collaborators, consisted in rubbing a
+quantity of the coarsely crushed castor seeds with part of the oil or
+fat, then adding the rest of the oil, together with acidified water
+(N/10 acetic acid). The quantities employed were 6-1/2 parts of
+decorticated castor beans for every 100 parts of oil or fat, and 50 to
+60 parts of acetic acid. After stirring until an emulsion is formed, the
+mixture is allowed to stand for twenty-four hours, during which
+hydrolysis takes place. The temperature is then raised to 70°-80° C.,
+which destroys the enzyme, and a 25 per cent. solution of sulphuric
+acid, equal in amount to one-fiftieth of the total quantity of fat
+originally taken, added to promote separation of the fatty acids. In
+this way three layers are formed, the one at the top consisting of the
+clear fatty acids, the middle one an emulsion containing portions of the
+seeds, fatty acids and glycerine, and the bottom one consisting of the
+aqueous glycerine. The intermediate layer is difficult to treat
+satisfactorily; it is generally washed twice with water, the washings
+being added to glycerine water, and the fatty mixture saponified and the
+resultant soap utilised.
+
+The process has been the subject of a considerable amount of
+investigation, numerous attempts having been made to actually separate
+the active fat-splitting constituent of the seeds, or to obtain it in a
+purer and more concentrated form than is furnished by the seeds
+themselves. Nicloux (_Comptes Rendus_, 1904, 1112, and _Roy. Soc.
+Proc._, 1906, 77 B, 454) has shown that the hydrolytic activity of
+castor seeds is due entirely to the cytoplasm, which it is possible to
+separate by mechanical means from the aleurone grains and all other
+cellular matter. This active substance, which he terms "lipaseidine," is
+considered to be not an enzyme, though it acts as such, following the
+ordinary laws of enzyme action; its activity is destroyed by contact
+with water in the absence of oil. This observer has patented (Eng. Pat.
+8,304, 1904) the preparation of an "extract" by triturating crushed
+castor or other seeds with castor oil, filtering the oily extract, and
+subjecting it to centrifugal force. The deposit consists of aleurone and
+the active enzymic substance, together with about 80 per cent. of oil,
+and one part of it will effect nearly complete hydrolysis of 100 parts
+of oil in twenty-four hours. In a subsequent addition to this patent,
+the active agent is separated from the aleurone by extraction with
+benzene and centrifugal force. By the use of such an extract, the
+quantity of albuminoids brought into contact with the fat is reduced to
+about 10 per cent. of that in the original seeds, and the middle layer
+between the glycerine solution and fatty acids is smaller and can be
+saponified directly for the production of curd soap, while the glycerine
+solution also is purer.
+
+In a further patent Nicloux (Fr. Pat. 349,213, 1904) states that the use
+of an acid medium is unnecessary, and claims that even better results
+are obtained by employing a neutral solution of calcium sulphate
+containing a small amount of magnesium sulphate, the proportion of salts
+not exceeding 0.5 per cent. of the fat, while in yet another patent,
+jointly with Urbain (Fr. Pat. 349,942, 1904), it is claimed that the
+process is accelerated by the removal of acids from the oil or fat to be
+treated, which may be accomplished by either washing first with
+acidulated water, then with pure water, or preferably by neutralising
+with carbonate of soda and removing the resulting soap.
+
+Lombard (Fr. Pat. 350,179, 1904) claims that acids act as stimulating
+agents in the enzymic hydrolysis of oils, and further that a simple
+method of obtaining the active product is to triturate oil cake with its
+own weight of water, allow the mixture to undergo spontaneous
+proteolytic hydrolysis at 40° C. for eight days, and then filter, the
+filtrate obtained being used in place of water in the enzymic process.
+
+Hoyer, who has made a large number of experiments in the attempt to
+isolate the lipolytic substance from castor seeds, has obtained a
+product of great activity, which he terms "ferment-oil," by extracting
+the crushed seeds with a solvent for oils.
+
+The Verein Chem. Werke have extended their original patent (addition
+dated 11th December, 1905, to Fr. Pat. 328,101, Oct., 1902), which now
+covers the use of vegetable ferments in the presence of water and
+manganese sulphate or other metallic salt. It is further stated that
+acetic acid may be added at the beginning of the operation, or use may
+be made of that formed during the process, though in the latter case
+hydrolysis is somewhat slower.
+
+Experiments have been carried out by Lewkowitsch and Macleod (_Journ.
+Soc. Chem. Ind._, 1903, 68, and _Proc. Roy. Soc._, 1903, 31) with
+ferments derived from animal sources, _viz._, lipase from pig's liver,
+and steapsin from the pig or ox pancreas. The former, although it has
+been shown by Kastle and Loevenhart (_Amer. Chem. Journ._, 1900, 49) to
+readily hydrolyse ethyl butyrate, is found to have very little
+fat-splitting power, but with steapsin more favourable results have been
+obtained, though the yield of fatty acids in this case is considerably
+inferior to that given by castor seeds. With cotton-seed oil, 83-86 per
+cent. of fatty acids were liberated as a maximum after fifty-six days,
+but with lard only 46 per cent. were produced in the same time. Addition
+of dilute acid or alkali appeared to exert no influence on the
+decomposition of the cotton-seed oil, but in the case of the lard,
+dilute alkali seemed at first to promote hydrolysis, though afterwards
+to retard it.
+
+Fokin (_Chem. Rev. Fett. u. Harz. Ind._, 1904, 118-120 _et seq._) has
+attempted to utilise the pancreatic juice on a technical scale, but the
+process proved too slow and too costly to have any practical use.
+
+_Rancidity._--The hydrolysing power of enzymes throws a good deal of
+light on the development of rancidity in oils and fats, which is now
+generally regarded as due to the oxidation by air in the presence of
+light and moisture of the free fatty acids contained by the oil or fat.
+It has long been known that whilst recently rendered animal fats are
+comparatively free from acidity, freshly prepared vegetable oils
+invariably contain small quantities of free fatty acid, and there can be
+no doubt that this must be attributed to the action of enzymes contained
+in the seeds or fruit from which the oils are expressed, hence the
+necessity for separating oils and fats from adhering albuminous matters
+as quickly as possible.
+
+_Decomposition of Fats by Bacteria._--Though this subject is not of any
+practical interest in the preparation of fatty acids for soap-making, it
+may be mentioned, in passing, that some bacteria readily hydrolyse fats.
+Schriber (_Arch. f. Hyg._, 41, 328-347) has shown that in the presence
+of air many bacteria promote hydrolysis, under favourable conditions as
+to temperature and access of oxygen, the process going beyond the simple
+splitting up into fatty acid and glycerol, carbon dioxide and water
+being formed. Under anærobic conditions, however, only a slight primary
+hydrolysis was found to take place, though according to Rideal (_Journ.
+Soc. Chem. Ind._, 1903, 69) there is a distinct increase in the amount
+of free fatty acids in a sewage after passage through a septic tank.
+
+Experiments have also been made on this subject by Rahn (_Centralb.
+Bakteriol_, 1905, 422), who finds that _Penicillium glaucum_ and other
+penicillia have considerable action on fats, attacking the glycerol and
+lower fatty acids, though not oleic acid. A motile bacillus, producing
+a green fluorescent colouring matter, but not identified, had a marked
+hydrolytic action and decomposed oleic acid. The name "lipobacter" has
+been proposed by De Kruyff for bacteria which hydrolyse fats.
+
+III. _Use of Chemical Reagents._--Among the chief accelerators employed
+in the hydrolysis of oils are sulphuric acid and Twitchell's reagent
+(benzene- or naphthalene-stearosulphonic acid), while experiments have
+also been made with hydrochloric acid (_Journ. Soc. Chem. Ind._, 1903,
+67) with fairly satisfactory results, and the use of sulphurous acid, or
+an alkaline bisulphite as catalyst, has been patented in Germany. To
+this class belong also the bases, lime, magnesia, zinc oxide, ammonia,
+soda and potash, though these latter substances differ from the former
+in that they subsequently combine with the fatty acids liberated to form
+soaps.
+
+_Sulphuric Acid._--The hydrolysing action of concentrated sulphuric acid
+upon oils and fats has been known since the latter part of the
+eighteenth century, but was not applied on a practical scale till 1840
+when Gwynne patented a process in which sulphuric acid was used to
+liberate the fatty acids, the latter being subsequently purified by
+steam distillation. By this method, sulpho-compounds of the glyceride
+are first formed, which readily emulsify with water, and, on treatment
+with steam, liberate fatty acids, the glycerol remaining partly in the
+form of glycero-sulphuric acid. The process has been investigated by
+Fremy, Geitel, and more recently by Lewkowitsch (_J. Soc. of Arts_,
+"Cantor Lectures," 1904, 795 _et seq._), who has conducted a series of
+experiments on the hydrolysis of tallow with 4 per cent. of sulphuric
+acid of varying strengths, containing from 58 to 90 per cent. sulphuric
+acid, H_{2}SO_{4}. Acid of 60 per cent. or less appears to be
+practically useless as a hydrolysing agent, while with 70 per cent. acid
+only 47.7 per cent. fatty acids were developed after twenty-two hours'
+steaming, and with 80 and 85 per cent. acid, the maximum of 89.9 per
+cent. of fatty acids was only reached after fourteen and fifteen hours'
+steaming respectively. Using 98 per cent. acid, 93 per cent. of fatty
+acids were obtained after nine hours' steaming, and after another seven
+hours, only 0.6 per cent. more fatty acids were produced. Further
+experiments have shown that dilute sulphuric acid has also scarcely any
+action on cotton-seed, whale, and rape oils.
+
+According to Lant Carpenter, some 75 per cent. of solid fatty acids may
+be obtained from tallow by the sulphuric acid process, owing to the
+conversion of a considerable quantity of oleic acid into isoleic acid
+(_vide_ p. 12), but in the process a considerable proportion of black
+pitch is obtained. C. Dreymann has recently patented (Eng. Pat. 10,466,
+1904) two processes whereby the production of any large amount of
+hydrocarbons is obviated. In the one case, after saponification with
+sulphuric acid, the liberated fatty acids are washed with water and
+treated with an oxide, carbonate, or other acid-fixing body, _e.g._,
+sodium carbonate, prior to distillation. In this way the distillate is
+much clearer than by the ordinary process, and is almost odourless,
+while the amount of unsaponifiable matter is only about 1.2 per cent.
+The second method claimed consists in the conversion of the fatty acids
+into their methyl esters by treatment with methyl alcohol and
+hydrochloric acid gas, and purification of the esters by steam
+distillation, the pure esters being subsequently decomposed with
+superheated steam, in an autoclave, with or without the addition of an
+oxide, _e.g._, 0.1 per cent. zinc oxide, to facilitate their
+decomposition.
+
+_Twitchell's Reagent._--In Twitchell's process use is made of the
+important discovery that aqueous solutions of fatty aromatic sulphuric
+acids, such as benzene- or naphthalene-stearosulphonic acid, readily
+dissolve fatty bodies, thereby facilitating their dissociation into
+fatty acids and glycerol. These compounds are stable at 100° C., and are
+prepared by treating a mixture of benzene or naphthalene and oleic acid
+with an excess of sulphuric acid, the following reaction taking place:--
+
+    C_{6}H_{6} + C_{18}H_{34}O_{2} + H_{2}SO_{4} =
+        C_{6}H_{4}(SO_{3}H)C_{18}H_{35}O + H_{2}O.
+
+On boiling the resultant product with water two layers separate, the
+lower one consisting of a clear aqueous solution of sulphuric acid and
+whatever benzene-sulphonic acid has been formed, while the upper layer,
+which is a viscous oil, contains the benzene-stearosulphonic acid. This,
+after washing first with hydrochloric acid and then rapidly with
+petroleum ether, and drying at 100° C. is then ready for use; the
+addition of a small quantity of this reagent to a mixture of fat
+(previously purified) and water, agitated by boiling with open steam,
+effects almost complete separation of the fatty acid from glycerol.
+
+The process is generally carried out in two wooden vats, covered with
+closely fitting lids, furnished with the necessary draw-off cocks, the
+first vat containing a lead coil and the other a brass steam coil.
+
+In the first vat, the fat or oil is prepared by boiling with 1 or 2 per
+cent. of sulphuric acid (141° Tw. or 60° B.) for one or two hours and
+allowed to rest, preferably overnight; by this treatment the fat is
+deprived of any dirt, lime or other impurity present. After withdrawing
+the acid liquor, the fat or oil is transferred to the other vat, where
+it is mixed with one-fifth of its bulk of water (condensed or
+distilled), and open steam applied. As soon as boiling takes place, the
+requisite amount of reagent is washed into the vat by the aid of a
+little hot water through a glass funnel, and the whole is boiled
+continuously for twelve or even twenty-four hours, until the free fatty
+acids amount to 85-90 per cent. The amount of reagent used varies with
+the grade of material, the smaller the amount consistent with efficient
+results, the better the colour of the finished product; with good
+material, from 1/2 to 3/4 per cent. is sufficient, but for materials of
+lower grade proportionately more up to 2 per cent. is required. The
+reaction appears to proceed better with materials containing a fair
+quantity of free acidity.
+
+When the process has proceeded sufficiently far, the boiling is stopped
+and free steam allowed to fill the vat to obviate any discoloration of
+the fatty acids by contact with the air, whilst the contents of the vat
+settle.
+
+The settled glycerine water, which should amount in bulk to 50 or 60 per
+cent. of the fatty matter taken, and have a density of 7-1/2° Tw. (5°
+B.), is removed to a receptacle for subsequent neutralisation with milk
+of lime, and, after the separation of sludge, is ready for
+concentration.
+
+The fatty acids remaining in the vat are boiled with a small quantity
+(0.05 per cent., or 1/10 of the Twitchell reagent requisite) of
+commercial barium carbonate, previously mixed with a little water; the
+boiling may be prolonged twenty or thirty minutes, and at the end of
+that period the contents of the vat are allowed to rest; the water
+separated should be neutral to methyl-orange indicator.
+
+It is claimed that fatty acids so treated are not affected by the air,
+and may be stored in wooden packages.
+
+_Hydrochloric Acid._--Lewkowitsch (_Journ. Soc. Chem. Ind._, 1903, 67)
+has carried out a number of experiments on the accelerating influence of
+hydrochloric acid upon the hydrolysis of oils and fats, which show that
+acid of a specific gravity of 1.16 has a very marked effect on most
+oils, cocoa-nut, cotton-seed, whale and rape oils, tallow and lard being
+broken up into fatty acid and glycerol to the extent of some 82-96 per
+cent. after boiling 100 grams of the oil or fat with 100 c.c. of acid
+for twenty-four hours. The maximum amount of hydrolysis was attained
+with cocoa-nut oil, probably owing to its large proportion of the
+glycerides of volatile fatty acids. Castor oil is abnormal in only
+undergoing about 20 per cent. hydrolysis, but this is attributed to the
+different constitution of its fatty acids, and the ready formation of
+polymerisation products. Experiments were also made as to whether the
+addition of other catalytic agents aided the action of the hydrochloric
+acid; mercury, copper sulphate, mercury oxide, zinc, zinc dust,
+aluminium chloride, nitrobenzene and aniline being tried, in the
+proportion of 1 per cent. The experiments were made on neutral lard and
+lard containing 5 per cent. of free fatty acids, but in no case was any
+appreciable effect produced.
+
+So far this process has not been adopted on the practical scale, its
+chief drawback being the length of time required for saponification.
+Undoubtedly the hydrolysis would be greatly facilitated if the oil and
+acid could be made to form a satisfactory emulsion, but although saponin
+has been tried for the purpose, no means of attaining this object has
+yet been devised.
+
+_Sulphurous Acid or Bisulphite._--The use of these substances has been
+patented by Stein, Berge and De Roubaix (Germ. Pat. 61,329), the fat
+being heated in contact with the reagent for about nine hours at
+175°-180° C. under a pressure of some 18 atmospheres, but the process
+does not appear to be of any considerable importance.
+
+_Lime._--The use of lime for the saponification of oils and fats was
+first adopted on the technical scale for the production of candle-making
+material, by De Milly in 1831. The insoluble lime soap formed is
+decomposed by sulphuric acid, and the fatty acids steam distilled.
+
+The amount of lime theoretically necessary to hydrolyse a given quantity
+of a triglyceride, ignoring for the moment any catalytic influence, can
+be readily calculated; thus with stearin the reaction may be represented
+by the equation:--
+
+     CH_{2}OOC_{18}H_{35}                                        CH_{2}OH
+     |                                                           |
+    2CHOOC_{18}H_{35} + 3Ca(OH)_{2} = 3Ca(OOC_{18}H_{35})_{2} + 2CHOH
+     |                                                           |
+     CH_{2}OOC_{18}H_{35}                                        CH_{2}OH
+      stearin           milk of lime    calcium stearate         glycerol
+
+In this instance, since the molecular weight of stearin is 890 and that
+of milk of lime is 74, it is at once apparent that for every 1,780 parts
+of stearin, 222 parts of milk of lime or 168 parts of quick-lime, CaO,
+would be required. It is found in practice, however, that an excess of
+3-5 per cent. above the theoretical quantity of lime is necessary to
+complete the hydrolysis of a fat when carried on in an open vessel at
+100°-105° C., but that if the saponification be conducted under pressure
+in autoclaves the amount of lime necessary to secure almost perfect
+hydrolysis is reduced to 2-3 per cent. on the fat, the treatment of fats
+with 3 per cent. of lime under a pressure of 10 atmospheres producing a
+yield of 95 per cent. of fatty acids in seven hours. The lower the
+pressure in the autoclave, the lighter will be the colour of the
+resultant fatty acids.
+
+_Magnesia._--It has been proposed to substitute magnesia for lime in the
+process of saponification under pressure, but comparative experiments
+with lime and magnesia, using 3 per cent. of lime and 2.7 per cent. of
+magnesia (_Journ. Soc. Chem. Ind._, xii., 163), show that saponification
+by means of magnesia is less complete than with lime, and, moreover, the
+reaction requires a higher temperature and therefore tends to darken the
+product.
+
+_Zinc Oxide._--The use of zinc oxide as accelerating agent has been
+suggested by two or three observers. Poullain and Michaud, in 1882, were
+granted a patent for this process, the quantity of zinc oxide
+recommended to be added to the oil or fat being 0.2 to 0.5 per cent.
+Rost, in 1903, obtained a French patent for the saponification of oils
+and fats by steam under pressure in the presence of finely divided
+metals or metallic oxides, and specially mentions zinc oxide for the
+purpose.
+
+It has also been proposed to use zinc oxide in conjunction with lime in
+the autoclave to obviate to some extent the discoloration of the fatty
+acids.
+
+Other catalytic agents have been recommended from time to time,
+including strontianite, lead oxide, caustic baryta, aluminium hydrate,
+but none of these is of any practical importance.
+
+_Soda and Potash._--Unlike the preceding bases, the soaps formed by soda
+and potash are soluble in water, and constitute the soap of commerce.
+These reagents are always used in sufficient quantity to combine with
+the whole of the fatty acids contained in an oil or fat, though
+doubtless, by the use of considerably smaller quantities, under
+pressure, complete resolution of the fatty matter into fatty acids and
+glycerol could be accomplished. They are, by far, the most important
+saponifying agents from the point of view of the present work, and their
+practical use is fully described in Chapter V.
+
+
+
+
+CHAPTER III.
+
+RAW MATERIALS USED IN SOAP-MAKING.
+
+     _Fats and Oils--Waste Fats--Fatty Acids--Less-known Oils and
+     Fats of Limited Use--Various New Fats and Oils Suggested for
+     Soap-making--Rosin--Alkali (Caustic and
+     Carbonated)--Water--Salt--Soap-stock._
+
+
+_Fats and Oils._--All animal and vegetable oils and fats intended for
+soap-making should be as free as possible from unsaponifiable matter, of
+a good colour and appearance, and in a sweet, fresh condition. The
+unsaponifiable matter naturally present as cholesterol, or phytosterol,
+ranges in the various oils and fats from 0.2 to 2.0 per cent. All oils
+and fats contain more or less free acidity; but excess of acidity,
+though it may be due to the decomposition of the glyceride, and does not
+always denote rancidity, is undesirable in soap-making material.
+Rancidity of fats and oils is entirely due to oxidation, in addition to
+free acid, aldehydes and ketones being formed, and it has been proposed
+to estimate rancidity by determining the amount of these latter
+produced. It is scarcely necessary to observe how very important it is
+that the sampling of fats and oils should be efficiently performed, so
+that the sample submitted to the chemist may be a fairly representative
+average of the parcel.
+
+In the following short description of the materials used, we give, under
+each heading, figures for typical samples of the qualities most suitable
+for soap-making.
+
+_Tallows._--Most of the imported tallow comes from America, Australia
+and New Zealand. South American mutton tallow is usually of good
+quality; South American beef tallow is possessed of a deep yellow colour
+and rather strong odour, but makes a bright soap of a good body and
+texture. North American tallows are, as a general rule, much paler in
+colour than those of South America, but do not compare with them in
+consistence. Most of the Australasian tallows are of very uniform
+quality and much in demand.
+
+Great Britain produces large quantities of tallow which comes into the
+market as town and country tallow, or home melt. Owing to the increasing
+demand for edible fat, much of the rough fat is carefully selected,
+rendered separately, and the product sold for margarine-making.
+Consequently the melted tallow for soap-making is of secondary
+importance to the tallow melter.
+
+The following are typical samples of tallow:--
+
+ _______________________________________________________________________
+|                                 |                |           |        |
+|                                 |                |  Acidity  |        |
+|                                 | Saponification | (as Oleic | Titre, |
+|                                 |   Equivalent.  |   Acid)   |   °C.  |
+|                                 |                | Per Cent. |        |
+|_________________________________|________________|___________|________|
+|                                 |                |           |        |
+| Australian mutton               |     285        |   0.85    |  45    |
+| Australian mutton               |     284.4      |   0.48    |  48.3  |
+| Australian beef                 |     284.2      |   1.68    |  43.9  |
+| Australian beef                 |     283.6      |   0.85    |  42.6  |
+| Australian mixed                |     285.1      |   3.52    |  44    |
+| Australian mixed                |     284.6      |   1.89    |  43.5  |
+| South American mutton           |     284.5      |   1.11    |  47    |
+| South American mutton           |     285        |   0.90    |  47.4  |
+| South American beef             |     284.7      |   0.81    |  45    |
+| South American beef             |     284        |   0.94    |  44    |
+| North American mutton           |     284.3      |   1.32    |  44    |
+| North American mutton           |      85        |   2.18    |  43.2  |
+| North American beef, fine       |     284.5      |   1.97    |  41.5  |
+| North American beef, good       |     283.8      |   4.30    |  42    |
+| North American ordinary         |     285.2      |   5.07    |  41.75 |
+| North American prime city       |     286        |   1.01    |  41.2  |
+| Selected English mutton         |     283.9      |   1.45    |  47    |
+| Selected English beef           |     284.2      |   2.40    |  44    |
+| Home-rendered or country tallow |     284.6      |   5.1     |  43    |
+| Town tallow                     |     285.3      |   7.4     |  42.5  |
+|_________________________________|________________|___________|________|
+
+Tallow should absorb from 39 to 44 per cent. iodine.
+
+_Lard._--Lard is largely imported into this country from the United
+States of America. The following is a typical sample of American hog's
+fat offered for soap-making:--
+
+ ________________________________________________________
+|                |                 |        |            |
+| Saponification |     Acidity     | Titre, | Refractive |
+|  Equivalent.   | (as Oleic Acid) |   °C.  |   Index    |
+|                |    Per Cent.    |        |  at 60° C. |
+|________________|_________________|________|____________|
+|                |                 |        |            |
+|      286       |       0.5       |  37.5  |   1.4542   |
+|________________|_________________|________|____________|
+
+Lard should absorb 59 to 63 per cent. iodine.
+
+_Cocoa-nut Oil._--The best known qualities are Cochin and Ceylon oils,
+which are prepared in Cochin (Malabar) or the Philippine Islands and
+Ceylon respectively.
+
+The dried kernels of the cocoa-nut are exported to various ports in
+Europe, and the oil obtained comes on the market as Continental Coprah
+Oil, with the prefix of the particular country or port where it has been
+crushed, _e.g._, Belgian, French and Marseilles Coprah Oil. Coprah is
+also imported into England, and the oil expressed from it is termed
+English Pressed Coprah.
+
+The following are typical examples from bulk:--
+
+ _________________________________________________________________________
+|                |                |                 |        |            |
+|                | Saponification |     Acidity     | Titre, | Refractive |
+|                |   Equivalent.  | (as Oleic Acid) |   °C.  |    Index   |
+|                |                |    Per Cent.    |        | at 25° C.  |
+|________________|________________|_________________|________|____________|
+|                |                |                 |        |            |
+| Cochin oil     |      215.5     |       1.5       |  23.5  |   1.4540   |
+| Cochin oil     |      214.3     |       2.6       |  22.1  |   1.4541   |
+| Ceylon oil     |      214.6     |       5.47      |  23    |   1.4535   |
+| Ceylon oil     |      216       |       3.95      |  22.75 |   1.4535   |
+| Belgian coprah |      214.2     |       1.65      |  23    |   1.4541   |
+| Belgian coprah |      215       |       2.60      |  22.1  |   1.4540   |
+| French coprah  |      214.2     |       6.55      |  23    |   1.4535   |
+| French coprah  |      214.8     |       7.42      |  22    |   1.4540   |
+| Pressed coprah |      215.8     |       7.45      |  22.2  |   1.4542   |
+| Pressed coprah |      216       |       9.41      |  22    |   1.4555   |
+|________________|________________|_________________|________|____________|
+
+Cocoa-nut oil should absorb 8.9 to 9.3 per cent. iodine.
+
+_Palm-nut Oil._--The kernels of the palm-tree fruit are exported from
+the west coast of Africa to Europe, and this oil obtained from them.
+Typical samples of English and Hamburg oils tested:--
+
+ _________________________________________________________
+|                |                 |        |            |
+| Saponification |     Acidity     | Titre, | Refractive |
+|   Equivalent.  | (as Oleic Acid) |   °C.  |    Index   |
+|                |    Per Cent.    |        | at 25° C.  |
+|________________|_________________|________|____________|
+|                |                 |        |            |
+|       225      |       4.4       |  24    |   1.4553   |
+|       227      |       7.7       |  23.8  |   1.4553   |
+|________________|_________________|________|____________|
+
+Palm-nut oil should absorb 10 to 13 per cent. iodine.
+
+_Olive Oil._--The olive is extensively grown in Southern Europe and in
+portions of Asia and Africa bordering the Mediterranean Sea. The fruit
+of this tree yields the oil.
+
+The free fatty acid content of olive oil varies very considerably. Very
+fine oils contain less than 1 per cent. acidity; commercial oils may be
+graded according to their free acidity, _e.g._, under 5 per cent., under
+10 per cent., etc., and it entirely depends upon the desired price of
+the resultant soap as to what grade would be used. The following is a
+typical sample for use in the production of high-class toilet soap:--
+
+_________________________________________________________
+|                |                 |        |            |
+| Saponification |     Acidity     | Titre, | Refractive |
+|   Equivalent.  | (as Oleic Acid) |   °C.  |    Index   |
+|                |    Per Cent.    |        | at 15° C.  |
+|________________|_________________|________|____________|
+|                |                 |        |            |
+|      288       |       1.8       |  21    |   1.4704   |
+|________________|_________________|________|____________|
+
+Olive oil should absorb 80 to 83 per cent. iodine.
+
+_Olive-kernel oil_, more correctly termed _Sulphur olive oil_.
+
+The amount of free fatty acids is always high and ranges from 40-70 per
+cent., and, of course, its glycerol content is proportionately variable.
+The free acidity increases very rapidly, and is, doubtless, due to the
+decomposition of the neutral oil by the action of hydrolytic ferment.
+
+A representative sample of a parcel tested:--
+
+ _______________________________________________
+|                |                 |            |
+| Saponification |     Acidity     | Refractive |
+|   Equivalent.  | (as Oleic Acid) |    Index   |
+|                |    Per Cent.    | at 20° C.  |
+|________________|_________________|____________|
+|                |                 |            |
+|       298      |      40.96      |   1.4666   |
+|________________|_________________|____________|
+
+_Palm oil_ is produced from the fruit of palm trees, which abound along
+the west coast of Africa. Lagos is the best quality, whilst Camaroons,
+Bonny, Old Calabar and New Calabar oils are in good request for
+bleaching purposes.
+
+Analysis of typical samples of crude palm oil has given:--
+
+ _________________________________________________________
+|                |                 |        |             |
+| Saponification |     Acidity     | Titre, |  Water and  |
+|   Equivalent.  | (as Oleic Acid) |   °C.  | Impurities, |
+|                |    Per Cent.    |        |  Per Cent.  |
+|________________|_________________|________|_____________|
+|                |                 |        |             |
+|       278      |      10.7       |  45    |     1.6     |
+|       280      |      31.2       |  44.5  |     2.8     |
+|________________|_________________|________|_____________|
+
+Palm oil should absorb 51 to 56 per cent. iodine.
+
+In the lower qualities we have examples of the result of hydrolytic
+decomposition by enzymes, the free acidity often amounting to 70 per
+cent.
+
+_Cotton-seed Oil._--This oil is expressed from the seeds separated from
+the "wool" of the various kinds of cotton tree largely cultivated in
+America and Egypt.
+
+In its crude state cotton-seed oil is a dark fluid containing
+mucilaginous and colouring matter, and is not applicable for
+soap-making. The following figures are representative of well-refined
+cotton-seed oils:--
+
+ _________________________________________________________________________
+|           |                |                 |        |            |
+| Specific  | Saponification |     Acidity     | Titre, | Refractive |
+| Gravity   |   Equivalent.  | (as Oleic Acid) |   °C.  |    Index   |
+| at 15° C. |                |    Per Cent.    |        | at 20° C.  |
+|___________|________________|_________________|________|____________|
+|           |                |                 |        |            |
+|  0.9229   |       290      |       0.24      |  33.6  |   1.4721   |
+|  0.924    |       299      |       0.39      |  35    |   1.4719   |
+|___________|________________|_________________|________|____________|
+
+Cotton-seed oil should absorb 104 to 110 per cent. iodine.
+
+_Cotton-seed Stearine._--The product obtained by pressing the deposit
+which separates on chilling refined cotton-seed oil.
+
+A typical sample tested:--
+
+ ___________________________________________
+|                |                 |        |
+| Saponification |     Acidity     | Titre, |
+|   Equivalent.  | (as Oleic Acid) |   °C.  |
+|                |    Per Cent.    |        |
+|________________|_________________|________|
+|                |                 |        |
+|     285.1      |      0.05       |  38    |
+|________________|_________________|________|
+
+_Arachis Oil._--The earth-nut or ground-nut, from which arachis oil is
+obtained, is extensively cultivated in North America, India and Western
+Africa. Large quantities are exported to Marseilles where the oil is
+expressed. Arachis oil enters largely into the composition of Marseilles
+White Soaps.
+
+Representative samples of commercial and refined oils tested:--
+
+ ______________________________________________________________________
+|            |           |           |           |        |            |
+|            | Specific  |  Saponi-  |  Acidity  |        | Refractive |
+|            | Gravity   | fication  | (as Oleic | Titre, |    Index   |
+|            | at 15° C. |  Equi-    |   Acid)   |   °C.  | at 20° C.  |
+|            |           |  valent   | Per Cent. |        |            |
+|____________|___________|___________|___________|________|____________|
+|            |           |           |           |        |            |
+| Commercial |   0.9184  |    298    |    2.6    |  28.6  |            |
+| Refined    |   0.9205  |    285    |    0.22   |  24.0  |   1.4712   |
+|____________|___________|___________|___________|________|____________|
+
+Arachis oil should absorb 90 to 98 per cent. iodine.
+
+_Maize Oil._--America (U.S.) produces very large quantities of maize
+oil.
+
+Typical samples of crude and refined oil gave these figures:--
+
+ ______________________________________________________________________
+|            |           |           |           |        |            |
+|            | Specific  |  Saponi-  |  Acidity  |        | Refractive |
+|            | Gravity   | fication  | (as Oleic | Titre, |    Index   |
+|            | at 15° C. |  Equi-    |   Acid)   |   °C.  | at 20° C.  |
+|            |           |  valent   | Per Cent. |        |            |
+|____________|___________|___________|___________|________|____________|
+|            |           |           |           |        |            |
+| Crude      |   0.9246  |    294    |    1.41   |  15    |            |
+| Refined    |   0.9248  |    294.1  |    0.40   |  17.2  |   1.4766   |
+|____________|___________|___________|___________|________|____________|
+
+Maize oil should absorb 120 to 128 per cent. iodine.
+
+_Sesame Oil._--Sesame oil is very largely pressed in Southern France
+from the seeds of the sesame plant which is cultivated in the Levant,
+India, Japan and Western Africa.
+
+A fairly representative sample of French expressed oil tested:--
+
+ ____________________________________________________________________
+|           |                |                 |        |            |
+| Specific  | Saponification |     Acidity     | Titre, | Refractive |
+| Gravity   |   Equivalent.  | (as Oleic Acid) |   °C.  |    Index   |
+| at 15° C. |                |    Per Cent.    |        | at 20° C.  |
+|___________|________________|_________________|________|____________|
+|           |                |                 |        |            |
+|   0.9227  |      295.2     |       1.84      |  22.8  |   1.4731   |
+|___________|________________|_________________|________|____________|
+
+Sesame oil should absorb 108 to 110 per cent. iodine.
+
+_Linseed Oil._--Russia, India, and Argentine Republic are the principal
+countries which extensively grow the flax plant, from the seeds of which
+linseed oil is pressed. It is used to a limited extent in soft-soap
+making.
+
+A good sample gave on analysis:--
+
+ ____________________________________________________________________
+|           |                |                 |        |            |
+| Specific  | Saponification |     Acidity     | Titre, | Refractive |
+| Gravity   |   Equivalent.  | (as Oleic Acid) |   °C.  |    Index   |
+| at 15° C. |                |    Per Cent.    |        | at 15° C.  |
+|___________|________________|_________________|________|____________|
+|           |                |                 |        |            |
+|   0.935   |      292       |       1.2       |  20    |   1.4840   |
+|___________|________________|_________________|________|____________|
+
+Linseed oil should absorb 170 to 180 per cent. iodine.
+
+_Hemp-seed oil_ is produced from the seeds of the hemp plant which grows
+in Russia. This oil is used in soft soap-making, more particularly on
+the Continent.
+
+A typical sample gave the following figures:--
+
+ __________________________________________________
+|           |                |        |            |
+| Specific  | Saponification | Titre, |            |
+| Gravity   |   Equivalent.  |   °C.  | Iodine No. |
+| at 15° C. |                |        |            |
+|___________|________________|________|____________|
+|           |                |        |            |
+|   0.926   |     292.6      |  15.8  |    143     |
+|___________|________________|________|____________|
+
+_Sunflower oil_ is produced largely in Russia.
+
+A specimen tested:--
+
+ ____________________________________________________________________
+|           |                |                 |        |            |
+| Specific  | Saponification |     Acidity     | Titre, |            |
+| Gravity   |   Equivalent.  | (as Oleic Acid) |   °C.  | Iodine No. |
+| at 15° C. |                |    Per Cent.    |        |            |
+|___________|________________|_________________|________|____________|
+|           |                |                 |        |            |
+|   0.9259  |     290.7      |       0.81      |   17   |   126.2    |
+|___________|________________|_________________|________|____________|
+
+_Castor Oil._--The castor oil plant is really a native of India, but it
+is also cultivated in the United States (Illinois) and Egypt.
+
+A typical commercial sample tested:--
+
+ ________________________________________________________________________
+|           |           |        |            |             |            |
+|  Saponi-  |  Acidity  |        |            |   Optical   | Refractive |
+| fication  | (as Oleic | Titre, | Iodine No. |  Rotation   |    Index   |
+|  Equi-    |   Acid)   |   °C.  |            | [alpha]_{D} | at 25° C.  |
+|  valent   | Per Cent. |        |            |             |            |
+|___________|___________|________|____________|_____________|____________|
+|           |           |        |            |             |            |
+|    310    |    1.5    |  2.8   |    84.1    |   + 4° 50'  |   1.4787   |
+|___________|___________|________|____________|_____________|____________|
+
+_Fish and Marine Animal Oils._--Various oils of this class have, until
+recently, entered largely into the composition of soft soaps, but a
+demand has now arisen for soft soaps made from vegetable oils.
+
+We quote a few typical analyses of these oils:--
+
+ _________________________________________________________________________
+|                  |          |          |           |        |           |
+|                  | Specific |  Saponi- |  Acidity  |        | Unsaponi- |
+|                  | Gravity  | fication | (as Oleic | Titre, |  fiable   |
+|                  | at 15°C. |  Equi-   |   Acid)   |   °C.  |   Matter  |
+|                  |          |  valent  | Per Cent. |        | Per Cent. |
+|__________________|__________|__________|___________|________|___________|
+|                  |          |          |           |        |           |
+| Pale seal oil    |   0.9252 |    289   |   0.947   |  15.5  |   0.8     |
+| Straw seal oil   |   0.9231 |    288   |   4.77    |  15.8  |   1.2     |
+| Brown seal oil   |   0.9253 |    291   |  16.38    |  16.2  |   1.9     |
+| Whale oil        |   0.9163 |    297   |   1.49    |  16.1  |   1.8     |
+| Dark whale oil   |   0.9284 |    303   |  12.60    |  21.8  |   2.4     |
+| Japan fish oil   |   0.9336 |    296   |   4.79    |  26    |   0.67    |
+| Japan fish oil   |   0.9325 |    302   |  10.43    |  28    |   1.55    |
+| Brown cod oil    |   0.9260 |    313   |  14.91    |  21.8  |   1.9     |
+| Pure herring oil |   0.9353 |    288   |  11.39    |  21.6  |   1.5     |
+| Kipper oil       |   0.9271 |    297   |   5.14    |  22.7  |   3.25    |
+|__________________|__________|__________|___________|________|___________|
+
+_Waste Fats._--Under this classification may be included marrow fat,
+skin greases, bone fats, animal grease, melted stuff from hotel and
+restaurant refuse, and similar fatty products. The following is a fair
+typical selection:--
+
+ _______________________________________________________________
+|                   |                |                 |        |
+|                   | Saponification |     Acidity     | Titre, |
+|                   |   Equivalent.  | (as Oleic Acid) |   °C.  |
+|                   |                |    Per Cent.    |        |
+|___________________|________________|_________________|________|
+|                   |                |                 |        |
+| Marrow fat        |      283.3     |       3.6       |  38.7  |
+| White skin grease |      287.2     |       4.3       |  36.4  |
+| Pale skin grease  |      286.3     |       9.87      |  35.7  |
+| Pale bone fat     |      289.7     |       8.8       |  40.7  |
+| Brown bone fat    |      289.1     |      11.0       |  41    |
+| Brown bone fat    |      292       |      20.5       |  40.2  |
+| Animal grease     |      289.4     |      38.1       |  40.4  |
+| Melted stuff      |      286.3     |      12.8       |  37.7  |
+|___________________|________________|_________________|________|
+
+The materials in the above class require to be carefully examined for
+the presence of unsaponifiable matter, lime salts and other impurities.
+
+_Fatty Acids._--We have already described the various methods of
+liberating fatty acids by hydrolysis or saponification.
+
+Under this heading should also be included stearines produced by
+submitting distilled fat to hydraulic pressure, the distillates from e
+from unsaponifiable matter, cocoa-nut oleine, a bye-product from the
+manufacture of edible cocoa-nut butter and consisting largely of free
+acids, and palm-nut oleine obtained in a similar manner from palm-nut
+oil.
+
+These are all available for soap-making.
+
+
+LESS-KNOWN OILS AND FATS OF LIMITED USE.
+
+_Shea Butter._--Shea butter is extracted from the kernels of the _Bassia
+Parkii_ and exported from Africa and Eastern India. This fat is somewhat
+tough and sticky, and the amount of unsaponifiable matter present is
+sometimes considerable. Samples examined by us gave the following
+data:--
+
+ _______________________________________________________________
+|                |                 |        |                   |
+| Saponification |     Acidity     | Titre, |    Refractive     |
+|   Equivalent.  | (as Oleic Acid) |   °C.  |       Index       |
+|                |    Per Cent.    |        |    at 60° C.      |
+|________________|_________________|________|___________________|
+|                |                 |        |                   |
+|       313      |       8.2       |  53.2  | 1.4566            |
+|       303      |       7.33      |  53    | 1.4558            |
+|                |                 |        | 1.4471 (F. Acids) |
+|________________|_________________|________|___________________|
+
+_Mowrah-seed Oil._--The mowrah-seed oil now offered for soap-making is
+derived from the seeds of _Bassia longifolia_ and _Bassia latifolia_. It
+is largely exported from India to Belgium, France and England. The
+following are the results of some analyses made by us:--
+
+ _________________________________________________________
+|                |                 |        |            |
+| Saponification |     Acidity     | Titre, | Refractive |
+|   Equivalent.  | (as Oleic Acid) |   °C.  |    Index   |
+|                |    Per Cent.    |        | at 60° C.  |
+|________________|_________________|________|____________|
+|                |                 |        |            |
+|       291      |      10         |  43.4  |   1.4518   |
+|       291.5    |       7.1       |  42.7  |            |
+|       291.2    |       9.9       |  43.8  |            |
+|       292      |      11.26      |  40.5  |            |
+|________________|_________________|________|____________|
+
+_Chinese vegetable tallow_ is the name given to the fat which is found
+coating the seeds of the "tallow tree" (_Stillingia sebifera_) which is
+indigenous to China and has been introduced to India where it
+flourishes. The following is a typical sample:--
+
+ _____________________________________
+|                |           |        |
+| Saponification |  Acidity  | Titre, |
+|   Equivalent   | Per Cent. |  °C.   |
+|________________|___________|________|
+|                |           |        |
+|     280.2      |   5.24    |  52.5  |
+|________________|___________|________|
+
+The seeds of the "tallow tree" yield an oil (stillingia oil) having
+drying properties.
+
+_Borneo Tallow._--The kernels of several species of _Hopea_ (or
+_Dipterocarpus_), which flourish in the Malayan Archipelago, yield a fat
+known locally as Tangawang fat. This fat is moulded (by means of bamboo
+canes) into the form of rolls about 3 inches thick, and exported to
+Europe as Borneo Tallow.
+
+A sample tested by one of us gave the following data:--
+
+ ___________________________________________
+|                |                 |        |
+| Saponification |     Acidity     | Titre, |
+|   Equivalent.  | (as Oleic Acid) |   °C.  |
+|                |    Per Cent.    |        |
+|________________|_________________|________|
+|                |                 |        |
+|      292       |       36        |  50.8  |
+|________________|_________________|________|
+
+_Kapok oil_ is produced from a tree which is extensively grown in the
+East and West Indies. The Dutch have placed it on the market and the
+figures given by Henriques (_Chem. Zeit._, 17, 1283) and Philippe
+(_Monit. Scient._, 1902, 730), although varying somewhat, show the oil
+to be similar to cotton-seed oil.
+
+
+VARIOUS NEW FATS AND OILS SUGGESTED FOR SOAP-MAKING.
+
+_Carapa_ or _Andiroba oil_, derived from the seeds of a tree (_Carapa
+Guianensis_) grown in West Indies and tropical America, has been
+suggested as suitable for soap-making. Deering (_Imperial Institute
+Journ._, 1898, 313) gives the following figures:--
+
+ ____________________________________________
+|                |           |               |
+| Saponification |  Acidity  | Melting Point |
+|   Equivalent   | Per Cent. |   of Fatty    |
+|                |           |   Acids, °C.  |
+|________________|___________|_______________|
+|                |           |               |
+|      287       |    12     |      89       |
+|________________|___________|_______________|
+
+Another observer (_Rev. Chem. Ind._, 13, 116) gives the setting point of
+the fatty acids as 56.4° C.
+
+_Candle-nut oil_ obtained from the seeds of a tree flourishing in India
+and also the South Sea Islands.
+
+The following figures have been published:--
+
+ _____________________________________________________________________________
+|           |       |            |            |
+| Saponi-   |       |            |            |
+| fication  | Titre,| Iodine No. |  Observers.| References.
+| Equiv-    |       |            |            |
+| alent.[1] |   °C. |            |            |
+|___________|_______|____________|____________|_______________________________
+|           |       |            |            |
+| 299-304.9 |  13   | 136.3-139.3| De Negri   |_Chem. Centr._, 1898, p. 493.
+|    291    |       |    163.7   | Lewkowitsch|_Chem. Revue_, 1901, p. 156.
+|    296    |  12.5 |    152.8   | Kassler    |_Farben-Zeitung_, 1903, p. 359.
+|___________|_______|____________|____________|_______________________________
+
+_Curcas oil_ is produced in Portugal from the seeds of the "purging nut
+tree," which is similar to the castor oil plant, and is cultivated in
+Cape Verde Islands and other Portuguese Colonies.
+
+The following data have been observed:--
+
+______________________________________________________________________________
+|           |       |            |            |
+| Saponi-   |       |            |            |
+| fication  | Titre,| Iodine No. |  Observers.| References.
+| Equiv-    |       |            |            |
+| alent.[2] |   °C. |            |            |
+|___________|_______|____________|____________|_______________________________
+|           |       |            |            |
+|  291.4    | 0.36  |    99.5    | Archbut    |_J. S. C. Ind._, 1898, p. 1010.
+|  290.3    | 4.46  |    98.3    | Lewkowitsch|_Chem. Revue_, 1898, p. 211.
+|  283.1    | 0.68  |   107.9    | Klein      |_Zeits. angew. Chem._,
+|           |       |            |            |   1898, p. 1012.
+|___________|_______|____________|____________|_______________________________
+
+The titre is quoted by Lewkowitsch as 28.6° C.
+
+_Goa butter_ or _Kokum butter_ is a solid fat obtained from the seeds of
+_Garcinia indica_, which flourishes in India and the East Indies.
+Crossley and Le Sueur (_Journ. Soc. Chem. Industry_, 1898, p. 993)
+during an investigation of Indian oils obtained these results:--
+
+ _________________________________________
+|                |           |            |
+| Saponification |  Acidity  | Iodine No. |
+| Equivalent.[3] | Per Cent. |            |
+|________________|___________|____________|
+|                |           |            |
+|      300       |    7.1    |   34.2     |
+|________________|___________|____________|
+
+_Safflower oil_ is extracted from the seeds of the _Carthamus
+tinctorius_, which, although indigenous to India and the East Indies, is
+extensively cultivated in Southern Russia (Saratowa) and German East
+Africa. Its use has been suggested for soft-soap making. The following
+figures have been published:--
+
+ ____________________________________________________________________________
+|         |         |        |             |
+|         | Saponi  |        |             |
+|         |fication | Iodine |  Observers. | References.
+|         | Equiv-  | No.    |             |
+|         |alent.[4]|        |             |
+|_________|_________|________|_____________|_________________________________
+|         |         |        |             |
+| Average |  295.5  | 141.29 | Crossley and| _J. S. C. Ind._, 1898, p. 992;
+|   of    |         |        |   Le Sueur  |   _J. S. C. Ind._, 1900, p. 104.
+| Twelve  |  287.1  | 141.6  | Shukoff     |_Chem. Revue_, 1901, p. 250.
+| Samples |  289.2  | 130    | Tylaikow    |_Chem. Revue_, 1902, p. 106.
+|         |  293.7  | 142.2  | Fendler     |_Chem. Zeitung_, 1904, p. 867.
+|_________|_________|________|_____________|_________________________________
+
+_Maripa fat_ is obtained from the kernels of a palm tree flourishing in
+the West Indies, but, doubtless, the commercial fat is obtained from
+other trees of the same family. It resembles cocoa-nut oil and gives the
+following figures:--
+
+ ___________________________________________________________________________
+|          |        |           |           |
+| Saponi-  |        | Melting   |           |
+| fication |        | Point     |           |
+| Equiv-   | Iodine | of Fatty  |           |
+| alent.[5]| No.    | Acids, °C.| Observer. | Reference.
+|__________|________|___________|___________|_______________________________
+|          |        |           |           |
+|  217     | 9.49   |   25      | Bassière  |_J. S. C. Ind._, 1903, p. 1137.
+|__________|________|___________|___________|_______________________________
+
+_Niam fat_, obtained from the seeds of _Lophira alata_, which are found
+extensively in the Soudan. The fat, as prepared by natives, has been
+examined by Lewkowitsch, and more recently Edie has published the
+results of an analysis. The figures are as follows:--
+
+__________________________________________________________________________
+|           |       |        |            |
+| Saponi-   |       |        |            |
+| fication  | Titre,| Iodine |  Observers.| References.
+| Equiv-    |       | No.    |            |
+| alent.[6] |   °C. |        |            |
+|___________|_______|________|____________|_______________________________
+|           |       |        |            |
+|  295.1    | 78.12 |  42.5  | Lewkowitsch|_J. S. C. Ind._, 1907, p. 1266.
+|  287.7    | 75.3  |        | Edïe.      |_Quart. J. Inst. Comm.
+|           |       |        |            |   Research in Tropics._
+|___________|_______|________|____________|_______________________________
+
+
+_Cohune-nut oil_ is produced from the nuts of the cohune palm, which
+flourishes in British Honduras. This oil closely resembles cocoa-nut and
+palm-nut oils and is stated to saponify readily and yield a soap free
+from odour. The following figures, obtained in the Laboratory of the
+Imperial Institute, are recorded in the official _Bulletin_, 1903, p.
+25:--
+
+ ________________________________________________
+|                |            |                  |
+| Saponification | Iodine No. | Melting Point of |
+|  Equivalent.   |            | Fatty Acids, °C. |
+|________________|____________|__________________|
+|                |            |                  |
+|  253.9-255.3   |  12.9-13.6 |      27-30       |
+|________________|____________|__________________|
+
+_Mafoureira_ or _Mafura tallow_ from the nuts of the mafoureira tree,
+which grows wild in Portuguese East Africa. The following figures are
+published:--
+
+______________________________________________________________________________
+|             |                |           |
+| Saponi-     |                |           |
+|  fication   |                | Iodine    | References.
+| Equi-       |                |     No.   |
+| valent.     |                |           |
+|_____________|________________|___________|___________________________________
+|             | Titre, °C.     |           |
+|   253.8     |   44-48        |  46.14    | De Negri and Fabris, _Annal. del
+|             |                |           |  Lab. Chim. Delle Gabelle_,
+|             |                |           |  1891-2, p. 271.
+|             | Acidity        |           |
+|             | (as Oleic Acid)|           |
+|             | Per Cent.      |           | _Bulletin Imp. Inst._,
+| 232.8-233.7 |  21.26         | 47.8-55.8 |   1903, p. 27.
+|_____________|________________|___________|___________________________________
+
+_Pongam oil_, obtained from the beans of the pongam tree, which
+flourishes in East India, has been suggested as available for the soap
+industry, but the unsaponifiable matter present would militate against
+its use. Lewkowitsch (_Analyst_, 1903, pp. 342-44) quotes these
+results:--
+
+
+ _____________________________________________________________________
+|                 |            |        |           |                 |
+|                 |  Saponi-   |        |           |                 |
+|                 | fication   | Iodine | Acidity,  | Unsaponifiable, |
+|                 |  Equi-     |   No.  | Per Cent. |    Per Cent.    |
+|                 | valent.[7] |        |           |                 |
+|_________________|____________|________|___________|_________________|
+|                 |            |        |           |                 |
+| Oil extracted   |    315     |  94    |   3.05    |       9.22      |
+|  in laboratory  |            |        |           |                 |
+| Indian specimen |    306     |  89.4  |   0.5     |       6.96      |
+|_________________|____________|________|___________|_________________|
+
+_Margosa oil_ is obtained from the seeds of _Melia azedarach_, a tree
+which is found in most parts of India and Burma.
+
+Lewkowitsch (_Analyst_, 1903, pp. 342-344) gives these figures:--
+
+ __________________________________
+|                |        |        |
+| Saponification | Iodine | Titre, |
+| Equivalent.[8] |   No.  |   °C.  |
+|________________|________|________|
+|                |        |        |
+|     284.9      |  69.6  |   42   |
+|________________|________|________|
+
+_Dika fat_ or _Wild Mango oil_ is obtained from the seed kernels of
+various kinds of _Irvingia_ by boiling with water. Lemarié (_Bulletin
+Imp. Inst._, 1903, p. 206) states that this fat is used in the place of
+cocoa-nut oil in the manufacture of soap. Lewkowitsch (_Analyst_, 1905,
+p. 395) examined a large sample of dika fat obtained from seeds of
+_Irvingia bateri_ (South Nigeria) and gives the following data:--
+
+ ____________________________________________________
+|                |        |        |                 |
+| Saponification | Iodine | Titre, | Unsaponifiable, |
+| Equivalent.[9] |   No.  |  °C.   |   Per Cent.     |
+|________________|________|________|_________________|
+|                |        |        |                 |
+|     229.4      |   5.2  |  34.8  |      0.73       |
+|________________|________|________|_________________|
+
+_Baobab-seed Oil._--Balland (_Journ. Pharm. Chem._, 1904, p. 529,
+abstracted in _Journ. Soc. Chem. Ind._, 1905, p. 34) states that the
+natives of Madagascar extract, by means of boiling water, from the seeds
+of the baobab tree, a whitish solid oil, free from rancidity, and
+possessed of an odour similar to Tunisian olive oil. He suggests that it
+may, with advantage, replace cocoa-nut oil in soap manufacture.
+
+_Persimmon-seed Oil._--Lane (_J. S. C. Ind._, 1905, p. 390) gives
+constants for this oil which he describes as semi-drying, of brownish
+yellow colour, and having taste and odour like pea-nut (arachis) oil.
+The following are taken from Lane's figures:--
+
+ ___________________________________
+|                 |        |        |
+| Saponification  | Iodine | Titre, |
+| Equivalent.[10] |   No.  |  °C.   |
+|_________________|________|________|
+|                 |        |        |
+|     298.4       | 115.6  |  20.2  |
+|_________________|________|________|
+
+_Wheat oil_, extracted from the wheat germ by means of solvents, has
+been suggested as applicable for soap-making (H. Snyder, abstr. _J. S.
+C. Ind._, 1905, p. 1074). The following figures have been published:--
+
+_______________________________________________________________________________
+|           |         |        |        |             |
+| Saponi-   |         |        |        |             |
+|  fication | Acidity,| Iodine | Titre, | Observers.  | References.
+| Equiv-    | Per     |  No.   |        |             |
+| alent.[11]| Cent.   |        |   °C.  |             |
+|___________|_________|________|________|_____________|________________________
+|           |         |        |        |             |
+|  306      |   5.65  | 115.17 |  29.7  | De Negri.   | _Chem. Zeit._, 1898
+|           |         |        |        |             |  (abstr. _J. S. C. I._,
+|           |         |        |        |             |  1898, p. 1155).
+|  297      |  20     | 115.64 |        | Frankforter | _J. Amer. C. Soc._,
+|           |         |        |        | & Harding   |  1899, 758-769 (abstr.
+|           |         |        |        |             |  in _J. S. C. I._,
+|           |         |        |        |             |  1899, p. 1030).
+|___________|_________|________|________|_____________|________________________
+
+_Tangkallah fat_, from the seeds of a tree growing in Java and the
+neighbouring islands, is suitable for soap-making. Schroeder (_Arch.
+Pharm._, 1905, 635-640, abstracted in _J. S. C. Ind._, 1906, p. 128)
+gives these values:--
+
+ _______________________________________________________
+|                |           |        |                 |
+| Saponification | Acidity,  | Iodine | Unsaponifiable, |
+| Equivalent.[12]| Per Cent. |   No.  |    Per Cent.    |
+|________________|___________|________|_________________|
+|                |           |        |                 |
+|      209       |    1.67   |  2.28  |      1.44       |
+|________________|___________|________|_________________|
+
+It is a hard fat, nearly white, possessing neither taste nor
+characteristic odour and solidifying at about 27° C.
+
+_Oil of Inoy-kernel._--(_Bulletin Imp. Inst._, 1906, p. 201). The seeds
+of Poga oleosa from West Africa yield on extraction an oil which gives
+the figures quoted below, and is suggested as a soap-maker's material:--
+
+ __________________________________
+|                |        |        |
+| Saponification | Iodine | Titre, |
+| Equivalent.    |   No.  |   °C.  |
+|________________|________|________|
+|                |        |        |
+|      304       | 89.75  |   22   |
+|________________|________|________|
+
+
+ROSIN.
+
+Rosin is the residuum remaining after distillation of spirits of
+turpentine from the crude oleo-resin exuded by several species of the
+pine, which abound in America, particularly in North Carolina, and also
+flourish in France and Spain. The gigantic forests of the United States
+consist principally of the long-leaved pine, _Pinus palustris
+(Australis)_, whilst the French and Spanish oleo-resin is chiefly
+obtained from _Pinus pinaster_, which is largely cultivated.
+
+Rosin is a brittle, tasteless, transparent substance having a smooth
+shining fracture and melting at about 135° C. (275° F.). The American
+variety possesses a characteristic aromatic odour, which is lacking in
+those from France and Spain. It is graded by samples taken out of the
+top of every barrel, and cut into 7/8 of an inch cubes, which must be
+uniform in size--the shade of colour of the cube determines its grade
+and value.
+
+The grades are as follows:--
+
+          W. W.  (Water white.)
+          W. G.  (Window glass.)
+          N.     (Extra pale.)
+          M.     (Pale.)
+          K.     (Low pale.)
+          I.     (Good No. 1.)
+          H.     (No. 1.)
+          G.     (Low No. 1.)
+          F.     (Good No. 2.)
+          E.     (No. 2.)
+          D.     (Good strain.)
+          C.     (Strain.)
+          B.     (Common strain.)
+          A.     (Common.)
+
+Unsaponifiable matter is present in rosin in varying amounts.
+
+Below are a few typical figures taken from a large number of collated
+determinations:--
+
+ ________________________________________________________________
+|                |                |          |          |        |
+|                | Saponification |  Total   |   Free   | Iodine |
+|                |  Equivalent.   | Acid No. | Acid No. |   No.  |
+|________________|________________|__________|__________|________|
+|                |                |          |          |        |
+| American W. W. |     330.5      |  169.7   |  119.1   | 126.9  |
+| American N.    |     312.3      |  179.6   |  161.4   | 137.8  |
+| French         |     320.5      |  175     |  168     | 120.7  |
+| Spanish        |     313.4      |  179     |  160     | 129.8  |
+|________________|________________|__________|__________|________|
+
+
+ALKALI (CAUSTIC AND CARBONATED).
+
+The manufacture of alkali was at one time carried on in conjunction with
+soap-making, but of late years it has become more general for the soap
+manufacturer to buy his caustic soda or carbonated alkali from the
+alkali-maker.
+
+Although there are some alkali-makers who invoice caustic soda and soda
+ash in terms of actual percentage of sodium oxide (Na_{2}O), it is the
+trade custom to buy and sell on what is known as the English degree,
+which is about 1 per cent. higher than this.
+
+The English degree is a survival of the time when the atomic weight of
+sodium was believed to be twenty-four instead of twenty-three, and,
+since the error on 76 per cent. Na_{2}O due to this amounts to about 1
+per cent., may be obtained by adding this figure to the sodium oxide
+really present.
+
+_Caustic soda_ (sodium hydrate) comes into commerce in a liquid form as
+90° Tw. (and even as high as 106° Tw.), and other degrees of dilution,
+and also in a solid form in various grades as 60°, 70°, 76-77°, 77-78°.
+These degrees represent the percentage of sodium oxide (Na_{2}O) present
+plus the 1 per cent. The highest grade, containing as it does more
+available caustic soda and less impurities, is much more advantageous in
+use.
+
+_Carbonate of soda_ or _soda ash_, 58°, also termed "light ash," and
+"refined alkali". This is a commercially pure sodium carbonate
+containing about 0.5 per cent. salt (NaCl). The 58° represents the
+English degrees and corresponds to 99 per cent. sodium carbonate
+(Na_{2}CO_{3}).
+
+_Soda ash_, 48°, sometimes called "caustic soda ash," often contains
+besides carbonate of soda, 4 per cent. caustic soda (sodium hydrate),
+and 10 per cent. salt (sodium chloride), together with water and
+impurities.
+
+The 48 degrees refers to the amount of alkali present in terms of sodium
+oxide (Na_{2}O), but expressed as English degrees.
+
+_Caustic potash_ (potassium hydrate) is offered as a liquid of 50-52° B.
+(98-103° Tw.) strength, and also in solid form as 75-80° and 88-92°. The
+degrees in the latter case refer to the percentage of potassium hydrate
+(KHO) actually present.
+
+_Carbonate of Potash._--The standard for refined carbonate of potash is
+90-92 per cent. of actual potassium carbonate (K_{2}CO_{3}) present,
+although it can be obtained testing 95-98 per cent.
+
+
+OTHER MATERIALS.
+
+_Water._--Water intended for use in soap-making should be as soft as
+possible. If the water supply is hard, it should be treated chemically;
+the softening agents may be lime and soda ash together, soda ash alone,
+or caustic soda. There are many excellent plants in vogue for water
+softening, which are based on similar principles and merely vary in
+mechanical arrangement. The advantages accruing from the softening of
+hard water intended for steam-raising are sufficiently established and
+need not be detailed here.
+
+_Salt_ (sodium chloride or common salt, NaCl) is a very important
+material to the soap-maker, and is obtainable in a very pure state.
+
+Brine, or a saturated solution of salt, is very convenient in
+soap-making, and, if the salt used is pure, will contain 26.4 per cent.
+sodium chloride and have a density of 41.6° Tw. (24.8° B.).
+
+The presence of sulphates alters the density, and of course the sodium
+chloride content.
+
+Salt produced during the recovery of glycerine from the spent lyes often
+contains sulphates, and the density of the brine made from this salt
+ranges higher than 42° Tw. (25° B.).
+
+_Soapstock._--This substance is largely imported from America, where it
+is produced from the dark-coloured residue, termed mucilage, obtained
+from the refining of crude cotton-seed oil. Mucilage consists of
+cotton-seed oil soap, together with the colouring and resinous
+principles separated during the treatment of the crude oil. The
+colouring matter is removed by boiling the mucilage with water and
+graining well with salt; this treatment is repeated several times until
+the product is free from excess of colour, when it is converted into
+soap and a nigre settled out from it.
+
+Soapstock is sold on a fatty acid basis; the colour is variable.
+
+FOOTNOTES:
+
+[1] Calculated by us from saponification value.
+
+[2] Calculated by us from saponification value.
+
+[3] Calculated by us from saponification value.
+
+[4] Calculated by us from saponification value.
+
+[5] Calculated by us from saponification value.
+
+[6] Calculated by us from saponification value.
+
+[7] Calculated by us from saponification value.
+
+[8] Calculated by us from saponification value.
+
+[9] Calculated by us from saponification value.
+
+[10] Calculated by us from saponification value.
+
+[11] Calculated by us from saponification value.
+
+[12] Calculated by us from saponification value.
+
+
+
+
+CHAPTER IV.
+
+BLEACHING AND TREATMENT OF RAW MATERIALS INTENDED FOR SOAP-MAKING.
+
+     _Palm Oil--Cotton-seed Oil--Cotton-seed "Foots"--Vegetable
+     Oils--Animal Fats--Bone Fat--Rosin._
+
+
+Having described the most important and interesting oils and fats used
+or suggested for use in the manufacture of soap, let us now consider
+briefly the methods of bleaching and treating the raw materials, prior
+to their transference to the soap-pan.
+
+_Crude Palm Oil._--Of the various methods suggested for bleaching palm
+oil, the bichromate process originated by Watts is undoubtedly the best.
+The reaction may be expressed by the following equation, though in
+practice it is necessary to use twice the amount of acid required by
+theory:--
+
+    K_{2}Cr_{2}O_{7} + 14HCl = 2KCl + Cr_{2}Cl_{6} + 7H_{2}O + 6Cl.
+
+    6Cl + 3H_{2}O = 6HCl + 3O.
+
+The palm oil, freed from solid impurities by melting and subsidence, is
+placed in the bleaching tank, and washed with water containing a little
+hydrochloric acid. Having allowed it to rest, and drawn off the liquor
+and sediment (chiefly sand), the palm oil is ready for treatment with
+the bleaching reagent, which consists of potassium bichromate and
+commercial muriatic acid. For every ton of oil, 22 to 28 lb. potassium
+bichromate and 45 to 60 lb. acid will be found sufficient to produce a
+good bleached oil.
+
+The best procedure is to act upon the colouring matter of the oil three
+successive times, using in the first two treatments one-third of the
+average of the figures just given, and in the final treatment an
+appropriate quantity which can be easily gauged by the appearance of a
+cooled sample of the oil.
+
+The potassium bichromate is dissolved in hot water and added to the
+crude palm oil, previously heated to 125° F. (52° C.), the requisite
+amount of muriatic acid being then run in and the whole well agitated by
+means of air. The bright red colour of the oil gradually changes to dark
+brown, and soon becomes green. The action having proceeded for a few
+minutes, agitation is stopped, and, after allowing to settle, the green
+liquor is withdrawn.
+
+When sufficiently bleached the oil is finally washed (without further
+heating) with hot water (which may contain salt), to remove the last
+traces of chrome liquor.
+
+If the above operation is carried out carefully, the colouring matter
+will be completely oxidised.
+
+It is important, however, that the temperature should not be allowed to
+rise above 130° F. (54° C.) during the bleaching of palm oil, otherwise
+the resultant oil on saponification is apt to yield a soap of a "foxy"
+colour. The bleached oil retains the characteristic violet odour of the
+original oil.
+
+It has been suggested to use dilute sulphuric acid, or a mixture of this
+and common salt, in the place of muriatic acid in the above process.
+
+_Crude Cotton-seed Oil._--The deep colouring matter of crude cotton-seed
+oil, together with the mucilaginous and resinous principles, are removed
+by refining with caustic soda lye.
+
+The chief aim of the refiner is to remove these impurities without
+saponifying any of the neutral oil. The percentage of free fatty acids
+in the oil will determine the quantity of caustic lye required, which
+must only be sufficient to remove this acidity.
+
+Having determined the amount of free acidity, the quantity of caustic
+soda lye necessary to neutralise it is diluted with water to 12° or 15°
+Tw. (8° or 10° B.), and the refining process carried out in three
+stages. The oil is placed in a suitable tank and heated by means of a
+closed steam coil to 100° F. (38° C.), a third of the necessary weak
+caustic soda lye added in a fine stream or by means of a sprinkler, and
+the whole well agitated with a mechanical agitator or by blowing a
+current of air through a pipe laid on the bottom of the tank.
+
+Prolonged agitation with air has a tendency to oxidise the oil, which
+increases its specific gravity and refractive index, and will be found
+in the soap-pan to produce a reddish soap. As the treatment proceeds,
+the temperature may be carefully raised, by means of the steam coil, to
+120° F. (49° C.).
+
+The first treatment having proceeded fifteen minutes, the contents of
+the tank are allowed to rest; the settling should be prolonged as much
+as possible, say overnight, to allow the impurities to precipitate well,
+and carry down the least amount of entangled oil. Having withdrawn these
+coloured "foots," the second portion of the weak caustic soda solution
+is agitated with the partially refined oil, and, when the latter is
+sufficiently treated, it is allowed to rest and the settled coloured
+liquor drawn off as before. The oil is now ready for the final
+treatment, which is performed in the same manner as the two previous
+ones. On settling, a clear yellow oil separates.
+
+If desired, the oil may be brightened and filtered, after refining to
+produce a marketable article, but if it is being refined for own use in
+the soap-house, this may be omitted.
+
+The residue or "foots" produced during the refining of crude
+cotton-seed oil, known in the trade as "mucilage," may be converted into
+"soapstock" as mentioned in the preceding chapter, or decomposed by a
+mineral acid and made into "black grease" ready for distillation by
+superheated steam.
+
+_Vegetable Oils._--The other vegetable oils come to the soap-maker's
+hand in a refined condition; occasionally, however, it is desirable to
+remove a portion of the free fatty acids, which treatment also causes
+the colouring matter to be preciptated. This is effected by bringing the
+oil and a weak solution of caustic lye into intimate contact. Cocoa-nut
+oil is often treated in this manner. Sometimes it is only necessary to
+well agitate the oil with 1-1/2 per cent. of its weight of a 12° Tw. (8°
+B.) solution of caustic soda and allow to settle. The foots are utilised
+in the soap-pan.
+
+_Animal Fats._--Tallows are often greatly improved by the above alkaline
+treatment at 165° F. (73° C.). It is one of the best methods and
+possesses advantages over acid processes--the caustic soda removes the
+free acid and bodies of aldehyde nature, which are most probably the
+result of oxidation or polymerisation, whereas the neutral fat is not
+attacked, and further, the alkaline foots can be used in the production
+of soap.
+
+_Bone fat_ often contains calcium (lime) salts, which are very
+objectionable substances in a soap-pan. These impurities must be removed
+by a treatment with hydrochloric or sulphuric acid. The former acid is
+preferable, as the lime salt formed is readily soluble and easily
+removed. The fat is agitated with a weak solution of acid in a
+lead-lined tank by blowing in steam, and when the treatment is complete
+and the waste liquor withdrawn, the last traces of acid are well washed
+out of the liquid fat with hot water.
+
+_Rosin._--Several methods have been suggested for bleaching rosin; in
+some instances the constitution of the rosin is altered, and in others
+the cost is too great or the process impracticable.
+
+The aim of these processes must necessarily be the elimination of the
+colouring matter without altering the original properties of the
+substance. This is best carried out by converting the rosin into a
+resinate of soda by boiling it with a solution of either caustic soda or
+carbonated alkali. The process is commenced by heating 37 cwt. of 17°
+Tw. (11° B.) caustic soda lye, and adding 20 cwt. of rosin, broken into
+pieces, and continuing the boiling until all the resinate is
+homogeneous, when an addition of 1-1/2 cwt. of salt is made and the
+boiling prolonged a little. On resting, the coloured liquor rises to the
+surface of the resinate, and may be siphoned off (or pumped away through
+a skimmer pipe) and the resinate further washed with water containing a
+little salt.
+
+The treatment with carbonated alkali is performed in a similar manner. A
+solution, consisting of 2-3/4 cwt. of soda ash (58°), in about four
+times its weight of water, is heated and 20 cwt. of rosin, broken into
+small pieces, added. The whole is heated by means of the open steam
+coil, and care must be taken to avoid boiling over. Owing to the
+liberation of CO_{2} gas, frothing takes place. A large number of
+patents have been granted for the preparation of resinate of soda, and
+many methods devised to obviate the boiling over. Some suggest mixing
+the rosin and soda ash (or only a portion of the soda ash) prior to
+dissolving in water; others saponify in a boiler connected with a trap
+which returns the resinate to the pan and allows the carbonic-acid gas
+to escape or to be collected.
+
+With due precaution the method can be easily worked in open vessels,
+and, using the above proportions, there will be sufficient uncombined
+rosin remaining to allow the resultant product to be pumped into the
+soap with which it is intended to intermix it, where it will be finally
+saponified thoroughly.
+
+The salt required, which, in the example given, would be 1-1/2 cwt., may
+be added to the solution prior to the addition of rosin or sprinkled in
+towards the finish of the boiling. When the whole has been sufficiently
+boiled and allowed to rest, the liquor containing the colouring matter
+will float over the resinate, and, after removal, may be replaced by
+another washing.
+
+Many other methods have been suggested for the bleaching, refining and
+treatment of materials intended for saponification, but the above
+practical processes are successfully employed.
+
+All fats and oils after being melted by the aid of steam must be allowed
+to thoroughly settle, and the condensed water and impurities withdrawn
+through a trap arrangement for collecting the fatty matter. The molten
+settled fatty materials _en route_ to the soap-pan should be passed
+through sieves sufficiently fine to free them from suspended matter.
+
+
+
+
+CHAPTER V.
+
+SOAP-MAKING.
+
+     _Classification of Soaps--Direct Combination of Fatty Acids
+     with Alkali--Cold Process Soaps--Saponification under Increased
+     or Diminished Pressure--Soft Soap--Marine Soap--Hydrated Soaps,
+     Smooth and Marbled--Pasting or Saponification--Graining
+     Out--Boiling on Strength--Fitting--Curd Soaps--Curd
+     Mottled--Blue and Grey Mottled Soaps--Milling Base--Yellow
+     Household Soaps--Resting of Pans and Settling of
+     Soap--Utilisation of Nigres--Transparent Soaps--Saponifying
+     Mineral Oil--Electrical Production of Soap._
+
+
+Soaps are generally divided into two classes and designated "hard," and
+"soft," the former being the soda salts, and the latter potash salts, of
+the fatty acids contained in the material used.
+
+According to their methods of manufacture, soaps may, however, be more
+conveniently classified, thus:--
+
+(A) Direct combination of fatty acids with alkali.
+
+(B) Treatment of fat with definite amount of alkali and no separation of
+waste lye.
+
+(C) Treatment of fat with indefinite amount of alkali and no separation
+of waste lye.
+
+(D) Treatment of fat with indefinite amount of alkali and separation of
+waste lye.
+
+(A) _Direct Combination of Fatty Acids with Alkali._--This method
+consists in the complete saturation of fatty acids with alkali, and
+permits of the use of the deglycerised products mentioned in chapter
+ii., section 2, and of carbonated alkalies or caustic soda or potash.
+Fatty acids are readily saponified with caustic soda or caustic potash
+of all strengths.
+
+The saponification by means of carbonated alkali may be performed in an
+open vat containing a steam coil, or in a pan provided with a removable
+agitator.
+
+It is usual to take soda ash (58°), amounting to 19 per cent. of the
+weight of fatty acids to be saponified, and dissolve it in water by the
+aid of steam until the density of the solution is 53° Tw. (30° B.); then
+bring to the boil, and, whilst boiling, add the molten fatty acids
+slowly, but not continuously.
+
+Combination takes place immediately with evolution of carbonic acid gas,
+which causes the contents of the vat or pan to swell, and frequently to
+boil over. The use of the agitator, or the cessation of the flow of
+fatty acids, will sometimes tend to prevent the boiling over. It is
+imperative that the steam should not be checked but boiling continued
+as vigorously as possible until all the alkali has been absorbed and the
+gas driven off.
+
+The use of air to replace steam in expelling the carbonic acid gas has
+been patented (Fr. Pat. 333,974, 1903).
+
+A better method of procedure, however, is to commence with a solution of
+64° Tw. (35° B.) density, made from half the requisite soda ash (9-1/2
+per cent.), and when this amount of alkali has all been taken up by the
+fatty acids (which have been added gradually and with continuous
+boiling), the remaining quantity of soda ash is added in a dry state,
+being sprinkled over each further addition of fatty acid.
+
+This allows the process to be more easily controlled and boiling over is
+avoided.
+
+It is essential that the boiling by steam should be well maintained
+throughout the process until all carbonic acid gas has been thoroughly
+expelled; when that point is reached, the steam may be lessened and the
+contents of the vat or pan gently boiled "on strength" with a little
+caustic lye until it ceases to absorb caustic alkali, the soap being
+finished in the manner described under (D).
+
+It is extremely difficult to prevent discoloration of fatty acids, hence
+the products of saponification in this way do not compare favourably in
+appearance with those produced from the original neutral oil or fat.
+
+(B) _Treatment of Fat with Definite Amount of Alkali and no Separation
+of Waste Lye._--Cold-process soap is a type of this class, and its
+method of production is based upon the characteristic property which the
+glycerides of the lower fatty acids (members of the cocoa-nut-oil class)
+possess of readily combining with a strong caustic soda solution at a
+low temperature, and evolving sufficient heat to complete the
+saponification.
+
+Sometimes tallow, lard, cotton-seed oil, palm oil and even castor oil
+are used in admixture with cocoa-nut oil. The process for such soap is
+the same as when cocoa-nut oil is employed alone, with the slight
+alteration in temperature necessary to render the fats liquid, and the
+amount of caustic lye required will be less. Soaps made of these blends
+closely resemble, in appearance, milled toilet soaps. In such mixtures
+the glycerides of the lower fatty acids commence the saponification, and
+by means of the heat generated induce the other materials, which alone
+would saponify with difficulty or only with the application of heat, to
+follow suit.
+
+It is necessary to use high grade materials; the oils and fats should be
+free from excess of acidity, to which many of the defects of
+cold-process soaps may be traced. Owing to the rapidity with which free
+acidity is neutralised by caustic soda, granules of soap are formed,
+which in the presence of strong caustic lye are "grained out" and
+difficult to remove without increasing the heat; the soap will thus tend
+to become thick and gritty and sometimes discoloured.
+
+The caustic lye should be made from the purest caustic soda, containing
+as little carbonate as possible; the water used for dissolving or
+diluting the caustic soda should be soft (_i.e._, free from calcium and
+magnesium salts), and all the materials carefully freed from particles
+of dirt and fibre by straining.
+
+The temperature, which, of course, must vary with the season, should be
+as low as is consistent with fluidity, and for cocoa-nut oil alone may
+be 75° F. (24° C.), but in mixtures containing tallow 100° to 120° F.
+(38° to 49° C.).
+
+The process is generally carried out as follows:--
+
+The fluid cocoa-nut oil is stirred in a suitable vessel with half its
+weight of 71.4° Tw. (38° B.) caustic soda lye at the same temperature,
+and, when thoroughly mixed, the pan is covered and allowed to rest. It
+is imperative that the oils and fats and caustic lye should be
+intimately incorporated or emulsified. The agitating may be done
+mechanically, there being several machines specially constructed for the
+purpose. In one of the latest designs the caustic lye is delivered
+through a pipe which rotates with the stirring gear, and the whole is
+driven by means of a motor.
+
+The agitation being complete, chemical action takes place with the
+generation of heat, and finally results in the saponification of the
+fats.
+
+At first the contents of the pan are thin, but in a few hours they
+become a solid mass. As the process advances the edges of the soap
+become more transparent, and when the transparency has extended to the
+whole mass, the soap is ready, after perfuming, to be framed and
+crutched.
+
+The admixture of a little caustic potash with the caustic soda greatly
+improves the appearance of the resultant product, which is smoother and
+milder.
+
+The glycerine liberated during the saponification is retained in the
+soap.
+
+Although it is possible, with care, to produce neutral soaps of good
+appearance and firm touch by this method, cold-process soaps are very
+liable to contain both free alkali and unsaponified fat, and have now
+fallen considerably into disrepute.
+
+_Saponification under Increased or Diminished Pressure._--Soaps made by
+boiling fats and oils, under pressure and _in vacuo_, with the exact
+quantity of caustic soda necessary for complete combination, belong also
+to this class. Amongst the many attempts which have at various times
+been made to shorten the process of soap-making may be mentioned
+Haywood's Patent No. 759, 1901, and Jourdan's French Patent No. 339,154,
+1903.
+
+In the former, saponification is carried out in a steam-jacketed vacuum
+chamber provided with an elaborate arrangement of stirrers; in the other
+process fat is allowed to fall in a thin stream into the amount of lye
+required for saponification, previously placed in the saponification
+vessel, which is provided with stirring gear.
+
+When the quantities have been added, steam is admitted and
+saponification proceeds.
+
+(C) _Treatment of Fat with Indefinite Amount of Alkali and no Separation
+of Waste Lye._--_Soft soap_ is representative of this class. The
+vegetable fluid oils (linseed, olive, cotton-seed, maize) are for the
+most part used in making this soap, though occasionally bone fats and
+tallow are employed. Rosin is sometimes added, the proportion ranging,
+according to the grade of soap required, from 5 to 15 per cent. of the
+fatty matter.
+
+The Soft Soap Manufacturers' Convention of Holland stipulate that the
+materials used in soft-soap making must not contain more than 5 per
+cent. rosin; it is also interesting to note that a patent has been
+granted (Eng. Pat. 17,278, 1900) for the manufacture of soft soap from
+material containing 50 per cent. rosin.
+
+Fish or marine animal oils--whale, seal, etc., once largely used as raw
+material for soft soap, have been superseded by vegetable oils.
+
+The materials must be varied according to the season; during hot
+weather, more body with a less tendency to separate is given by the
+introduction of oils and fats richer in stearine; these materials also
+induce "figging".
+
+The most important material, however, is the caustic potash lye which
+should average 40° Tw. (24° B.), _i.e._, if a weak solution is used to
+commence saponification, a stronger lye must be afterwards employed to
+avoid excess of water in the soap, and these average 40° Tw. (24° B.).
+The potash lye must contain carbonates, which help to give transparency
+to the resultant soap. If the lye is somewhat deficient in carbonates,
+they may be added in the form of a solution of refined pearl ash
+(potassium carbonate).
+
+Caustic soda lye is sometimes admixed, to the extent of one-fourth, with
+potash lye to keep the soap firmer during hot weather, but it requires
+great care, as a slight excess of soda gives soft soap a bad appearance
+and a tendency to separate.
+
+The process is commenced by running fatty matter and weak potash lyes
+into the pan or copper, and boiling together, whilst the introduction of
+oil and potash lye is continued.
+
+The saponification commences when an emulsion forms, and the lye is then
+run in more quickly to prevent the mass thickening.
+
+Having added sufficient "strength" for complete saponification, the
+boiling is continued until the soap becomes clear.
+
+The condition of the soap is judged by observing the behaviour of a
+small sample taken from the pan and dropped on glass or iron. If the
+soap is satisfactory it will set firm, have a short texture and slightly
+opaque edge, and be quite clear when held towards the light. If the
+cooled sample draws out in threads, there is an excess of water present.
+If an opaque edge appears and vanishes, the soap requires more lye. If
+the sample is turbid and somewhat white, the soap is too alkaline and
+needs more oil.
+
+The glycerine liberated during saponification is contained in the soap
+and no doubt plays a part in the production of transparency.
+
+_Hydrated soaps_, both smooth and marbled, are included in this
+classification, but are _soda_ soaps. Soap made from cocoa-nut oil and
+palm-kernel oil will admit of the incorporation of large quantities of a
+solution of either salt, carbonate of soda, or silicate of soda, without
+separation, and will retain its firmness. These materials are,
+therefore, particularly adapted for the manufacture of marine soaps,
+which often contain as much as 80 per cent. of water, and, being soluble
+in brine, are capable of use in sea-water. For the same reason,
+cocoa-nut oil enters largely into the constitution of hydrated soaps,
+but the desired yield or grade of soap allows of a variation in the
+choice of materials. Whilst marine soap, for example, is usually made
+from cocoa-nut oil or palm-kernel oil only, a charge of 2/3 cocoa-nut
+oil and 1/3 tallow, or even 2/3 tallow and 1/3 cocoa-nut oil, will
+produce a paste which can carry the solutions of silicate, carbonate,
+and salt without separation, and yield a smooth, firm soap.
+
+The fatty materials, carefully strained and freed from particles of dirt
+and fibre, are boiled with weak caustic soda lye until combination has
+taken place. Saponification being complete, the solution of salt is
+added, then the carbonate of soda solution, and finally the silicate of
+soda solution, after which the soap is boiled. When thoroughly mixed,
+steam is shut off, and the soap is ready for framing.
+
+The marbled hydrated soap is made from cocoa-nut oil or a mixture of
+palm-kernel oil and cocoa-nut oil with the aid of caustic soda lye
+32-1/2° Tw. (20° B.). As soon as saponification is complete, the brine
+and carbonate of soda solution are added, and the pan allowed to rest.
+
+The soap is then carefully tasted as to its suitability for marbling by
+taking samples and mixing with the colouring solution (ultramarine mixed
+with water or silicate of soda solution). If the sample becomes blue
+throughout, the soap is too alkaline; if the colour is precipitated, the
+soap is deficient in alkali. The right point has been reached when the
+marbling is distributed evenly. Having thus ascertained the condition of
+the pan, and corrected it if necessary, the colour, mixed in water or in
+silicate of soda solution, is added and the soap framed.
+
+(D) _Treatment of Fat with Indefinite Amount of Alkali and Separation of
+Waste Lye._--This is the most general method of soap-making. The various
+operations are:--
+
+          (_a_) Pasting or saponification.
+          (_b_) Graining out or separation.
+          (_c_) Boiling on strength.
+
+And in the case of milling soap base and household soaps,
+
+          (_d_) Fitting.
+
+(_a_) _Pasting or Saponification._--The melted fats and oils are
+introduced into the soap-pan and boiled by means of open steam with a
+caustic soda lye 14° to 23.5° Tw. (10° to 15° B.). Whether the fatty
+matters and alkali are run into the pan simultaneously or separately is
+immaterial, provided the alkali is not added in sufficient excess to
+retard the union.
+
+The commencement of the saponification is denoted by the formation of an
+emulsion. Sometimes it is difficult to start the saponification; the
+presence of soap will often assist this by emulsifying the fat and thus
+bringing it into intimate contact with the caustic soda solution.
+
+When the action has started, caustic soda lye of a greater density, 29°
+to 33° Tw. (18° to 20° B.), is frequently added, with continued boiling,
+in small quantities as long as it is being absorbed, which is
+ascertained by taking out samples from time to time and examining them.
+
+There should be no greasiness in the sample, but when pressed between
+finger and thumb it must be firm and dry.
+
+Boiling is continued until the faint caustic taste on applying the
+cooled sample to the tongue is permanent, when it is ready for "graining
+out". The pasty mass now consists of the soda salts of the fat (as
+imperfect soap, probably containing emulsified diglycerides and
+monoglycerides), together with water, in which is dissolved the
+glycerine formed by the union of the liberated glyceryl radicle from the
+fat with the hydroxyl radicle of the caustic soda, and any slight excess
+of caustic soda and carbonates. The object of the next operation is to
+separate this water (spent lye) from the soap.
+
+(_b_) _Graining Out or Separation._--This is brought about by the use of
+common salt, in a dry form or in solution as brine, or by caustic soda
+lye. Whilst the soap is boiling, the salt is spread uniformly over its
+surface, or brine 40° Tw. (24° B.) is run in, and the whole well boiled
+together. The soap must be thoroughly boiled after each addition of
+salt, and care taken that too large a quantity is not added at once.
+
+As the soap is gradually thrown out of solution, it loses its smooth
+transparent appearance, and becomes opaque and granular.
+
+When a sample, taken out on a wooden trowel, consists of distinct grains
+of soap and a liquid portion, which will easily separate, sufficient
+salt or brine has been added; the boiling is stopped and the spent lye
+allowed to settle out, whilst the soap remains on the surface as a more
+or less thick mass.
+
+The separated spent lye consists of a solution of common salt,
+glycerine, and alkaline salts; the preparation of crude glycerine
+therefrom is considered in chapter ix.
+
+The degree of separation of water (spent lye) depends upon the amount of
+precipitant used. The aim is to obtain a maximum amount of spent lye
+separated by the use of a minimum quantity of salt.
+
+The amount of salt required for "graining out" varies with the raw
+material used. A tallow soap is the most easily grained, more salt is
+required for cotton-seed oil soap, whereas soaps made from cocoa-nut and
+palm-kernel oils require very large amounts of salt to grain out
+thoroughly. Owing to the solubility in weak brine of these latter soaps,
+it is preferable to grain them with caustic soda lye. This is effected
+by adding, during boiling, sufficient caustic lye (32-1/2° Tw., 20° B.)
+to produce the separation of the granules of soap. The whole is allowed
+to rest; the separated half-spent lye is withdrawn and may be used for
+the pasting of fresh materials.
+
+After the removal of the settled lye, the grained mass is boiled with
+sufficient water to dissolve the grain and make it smooth ("close" it),
+and is now ready for the next operation of "boiling on strength".
+
+(_c_) _Boiling on Strength or Clear Boiling._--This is the most
+important operation and is often termed "making the soap". The object is
+to harden the soap and to ensure complete saponification.
+
+Caustic soda lye (32-1/2° Tw., 20° B.) is gradually added until the soap
+is again opened or grained, and boiling continued by the use of the dry
+steam coil. As soon as the caustic soda lye is absorbed, another portion
+is slowly added, and this is continued until the caustic soda or
+"strength" remains permanent and the soapy mass, refusing to absorb
+more, is thrown out of solution and grained. The granular mass will boil
+steadily, and the boiling should be prolonged, as the last traces of
+neutral oil are difficult to completely saturate with alkali. Thorough
+saponification takes place gradually, and the operation cannot be
+hurried; special care has to be bestowed upon this operation to effect
+the complete combination of fat and alkali.
+
+After resting for several hours, half-spent lye settles to the bottom of
+the pan. In the case of yellow soaps or milling bases the settled lye is
+removed to a suitable receptacle and reserved for use in the
+saponification of other material, and the soap is then ready for the
+final operation of "fitting".
+
+(_d_) _Fitting._--If the operations just described have been properly
+performed, the fitting should present no difficulty. The soap is boiled
+with open steam, and water added until the desired degree of closing is
+attained. As the water is thoroughly intermixed throughout the mass the
+thick paste gradually becomes reduced to a smooth, thin consistence.
+Samples are tested from time to time as to their behaviour in dropping
+off a hot trowel held sideways; the thin layer should drop off in two or
+three flakes and leave the surface of the trowel clean and dry. The soap
+is then in a condition to allow the impurities to gravitate. According
+to the required soap, the fit may be "coarse" ("open") when the flakes
+drop off the trowel readily, or "fine" ("close") when the flakes only
+leave the trowel with difficulty.
+
+If the dilution with water has been allowed to proceed too far, and too
+fine a fit is produced, which would be denoted by the layer of soap not
+leaving the trowel, a little caustic lye or brine may be very carefully
+added and the whole well boiled until the desired condition is obtained.
+
+A good pressure of steam is now applied to the pan, causing the contents
+to swell as high as possible, this greatly facilitating the settling of
+impurities; steam is then turned off, the pan covered, and the boil
+allowed to rest for several days.
+
+The art of fitting consists in leaving the contents of the pan in such a
+condition that, on standing, all the impurities precipitate, and the
+settled soap, containing the correct amount of water, is clear and
+bright.
+
+The above is a general practical outline of the ordinary soap-boiling
+process. It may be modified or slightly altered according to the fancy
+of the individual soap-maker or the particular material it is desired to
+use. Fats and oils not only vary in the amount of alkali they absorb
+during saponification, but also differ in the strength of the alkali
+they require. Tallow and palm oil require lye of a density of 15° to 18°
+Tw. (10° to 12° B.), but cocoa-nut oil alone would not saponify unless
+the lye was more concentrated, 33° to 42° Tw. (20° to 25° B.).
+Cotton-seed oil requires weak lyes for saponification, and, being
+difficult to saponify alone even with prolonged boiling, is generally
+mixed with animal fat.
+
+When fats are mixed together, however, their varying alkali requirements
+become modified, and once the saponification is begun with weak lye,
+other materials are induced to take up alkali of a strength with which
+alone they would not combine.
+
+It is considered the best procedure to commence the pasting or
+saponification with weak lye.
+
+In order to economise tank space, it is the general practice to store
+strong caustic lye (60° to 70° Tw., 33° to 37° B.) and to dilute it as
+it is being added to the soap-pan by the simultaneous addition of water.
+
+Many manufacturers give all their soap a "brine wash" to remove the last
+traces of glycerine and free the soap from carbonates. This operation
+takes place prior to "fitting"; sufficient water is added to the boiling
+soap to "close" it and then brine is run in to "grain" it.
+
+After resting, the liquor is withdrawn.
+
+Having described the necessary operations in general, we will now
+consider their application to the preparation of various kinds of hard
+soap.
+
+_Curd Soaps._--Tallow is largely used in the manufacture of white curd
+soaps, but cocoa-nut oil sometimes enters into their composition.
+
+The first three operations above described, _viz._, pasting, graining
+out, and boiling on strength, are proceeded with; the clear boiling by
+means of a closed steam coil is continued until the "head" is boiled out
+and the soap is free from froth. A sample taken and cooled should be
+hard. Boiling is then stopped, and, after covering, the pan is allowed
+to rest for eight to ten hours, when the soap is ready for filling into
+frames, where it is crutched until perfectly smooth.
+
+_Curd mottled_ is usually made from melted kitchen stuff and bone
+grease.
+
+Its preparation is substantially the same as for curd soap, but the
+clear boiling is not carried so far. The art of curd mottled soap-making
+lies in the boiling. If boiled too long the mottling will not form
+properly, and, on the other hand, insufficient boiling will cause the
+soap to contain an excess of entangled lye. Having boiled it to its
+correct concentration the pan is allowed to rest about two hours, after
+which the soap is ready for framing, which should be done expeditiously
+and the frames covered up.
+
+Some lye, containing the impurities from the fats used, remains in the
+interstices of the curd, unable to sink, and as the soap cools it is
+enclosed and forms the mottling. The mottling may, therefore, be
+considered as a crystallisation of the soap, in which the impurity forms
+the colour.
+
+_Blue and Grey Mottled Soaps._--These are silicated or liquored soaps in
+which the natural mottling, due to the impure materials used in the
+early days of soap-making, is imitated by artificial mottling, and are,
+consequently, entirely different to curd mottled soaps.
+
+The materials employed in making mottled soap comprise bleached palm
+oil, tallow, bone fat, cocoa-nut oil, palm-kernel oil, cotton-seed oil,
+and, in some instances, rosin.
+
+The choice of a charge will naturally depend upon the cost; the property
+of absorbing a large amount of liquor, which is characteristic of soaps
+made from cocoa-nut oil and palm-kernel oil, is taken advantage of, as
+are also the physical properties of the various fats and oils, with a
+view to the crystallisation of the resultant soap and the development of
+the mottle. The fat is saponified, grained and boiled on strength, as
+previously described. After withdrawing the half-spent lye, the soap is
+just closed by boiling with water, and is then ready for the silicate or
+other saline additions.
+
+Soap intended to be liquored with silicate of soda should be distinctly
+strong in free alkali; the crystalline nature of the soap is increased
+thereby, and the mottled effect intensified. Some makers, however, fit
+the soap coarsely and allow a nigre to deposit; then, after removing the
+nigre, or transferring the settled soap to another copper, containing
+scraps of mottled soap, get the soap into a condition for mottling, and
+add the silicate of soda solution. To every 1 cwt. of soap, 28 lb. of
+silicate of soda solution, 32-1/2° Tw. (20° B.) is added, whilst
+boiling; the strength of the silicate solution, however, will depend
+upon the proportion of cocoa-nut oil and palm-kernel oil present in the
+charge. Many soap-makers use 20° Tw. (13° B.) (cold) silicate solution,
+whilst others prefer 140° Tw. (59.5° B.), with the gradual addition of
+water to the soap, kept boiling, until the product is in the correct
+mottling condition, and others, again, use bleach liquor, soda crystals,
+pearl ash, and salt, together with silicate solution.
+
+Considerable skill and experience is necessary to discern when the soap
+acquires the correct mottling state. It should drop off the spatula in
+large thick flakes, take considerable time to set, and the surface
+should not be glossy.
+
+When this mottling condition has been obtained, the colouring matter,
+which would be ultramarine for the blue mottled and manganese dioxide
+for the grey mottled soap (3-4 lb. ultramarine or 1-3 lb. manganese
+dioxide being sufficient for 1 ton of soap), is mixed with a little
+water and added to the boiling soap--the boiling is continued until all
+is thoroughly amalgamated, and when the steam is shut off the contents
+of the pan are ready for cleansing.
+
+Mottled soap is run into wooden frames, which, when full, are covered
+over and allowed to cool very gradually. On cooling slowly, large
+crystals are produced which result in a distinct bold mottle; if the
+cooling is too rapid, a small crystal is obtained and the mottle is not
+distributed, resulting in either a small mottle, or no mottle at all,
+and merely a general coloration. In fact, the entire art of mottling
+soap consists in properly balancing the saline solutions and colouring
+matter, so that the latter is properly distributed throughout the soap,
+and does not either separate in coloured masses at the bottom of the
+frame, or uniformly colour the whole mass.
+
+A sample of the soap should test 45 per cent. fatty acids, and the
+amount of salt would range from 1/2 to 1 per cent.
+
+Some of the English mottled soaps, especially those made from materials
+which give a yellow-coloured ground, are bleached by soaking in brine,
+or pickling in brine containing 2 per cent. of bleach liquor. The
+resultant soap has a white ground and is firm. The bleach liquor may be
+made by mixing 1 cwt. bleaching powder with 10 cwts. of soda ash
+solution (15° Tw., 10° B.), allowing to settle, and using the clear
+liquid, or by mixing 2 parts soda ash solution with 1 part of bleaching
+powder solution, both solutions being 30° Tw. (18.8° B.).
+
+_Milling-base._--The materials generally used are tallows and cocoa-nut
+oils of the finest quality. The tallow is thoroughly saponified first,
+and the graining is performed by the aid of caustic soda lye in
+preference to salt. The half-spent lyes are withdrawn, and the cocoa-nut
+oil added to the pan. This is saponified, and when the saponification is
+complete, "boiling-on-strength" is proceeded with. Special care should
+be devoted to the "boiling-on-strength" operation--its value in good
+soap-making cannot be over-rated--and perfect saponification must be
+ensured. The half-spent lyes are allowed to deposit during the night,
+and the soap must be carefully examined next morning to ascertain if any
+alkali has been absorbed. If the caustic taste is permanent the
+strengthening operation is complete, but should any caustic have been
+absorbed, further addition of alkali must be made and the boiling
+continued. These remarks apply equally to all soaps.
+
+The soap, when ready, is fitted.
+
+Bleached palm oil, olive oil, castor oil and lard are also employed in
+the production of special milling soap bases, a palm oil soap being
+specially suitable for the production of a violet-scented toilet soap.
+
+_Yellow Household Soaps._ (_a_) _Bar Soaps._--These are made from tallow
+with an admixture of from 15-25 per cent. rosin. The best quality is
+known in the South and West of England as Primrose Soap, but is
+designated in the North of England by such names as Golden Pale,
+Imperial Pale, Gold Medal Pale, etc. Tallow alone produces a very hard
+soap of inferior lathering qualities; but rosin combines with alkali to
+form a soft body, which, although not a soap in the strict sense of the
+term, is readily soluble in water, and in admixture with the durable
+tallow soap renders it more soluble in water and thereby increases its
+lathering properties.
+
+The rosin may be added to the soap-pan after a previous partial
+saponification with soda ash, and removal of colouring matter, and
+finally saponified with caustic soda lye, or, as is more generally
+adopted, as a rosin change. The pan is opened with caustic soda lye and
+saturation of the rosin takes place rapidly; when completely saponified
+it is grained with salt, and the coloured lye allowed to deposit and
+finally withdrawn.
+
+The four operations already detailed apply to this soap.
+
+Cheaper pale soaps may be made from lower grades of tallow and rosin and
+are generally silicated.
+
+(_b_) _Tablet or Washer Type._--A demand has arisen for soap of free
+lathering qualities, which has become very popular for general household
+use. This soap is usually made from a mixture of cotton-seed oil,
+tallow, and cocoa-nut oil, with a varying amount of rosin. The tallow
+yields firmness and durability whilst the other constituents all assist
+in the more ready production of a copious lather.
+
+As to what amount of rosin can be used to yield a finished soap of
+sufficient body and satisfactory colour, this naturally depends upon the
+grade of raw material at the soap-makers' disposal. Those fats and oils
+which yield firm soaps, will, of course, allow a greater proportion of
+rosin to be incorporated with them than materials producing soaps of
+less body. Rosin imparts softness to a soap, and also colour.
+
+This is a fitted soap and full details of manufacture have already been
+given.
+
+Cheaper soaps are produced from lower grade materials hardened with
+alkaline solutions.
+
+_Resting of Pans and Settling of Soap._--The fitted soap is allowed to
+settle from four to six days. The period allowed for resting is
+influenced, however, not only by the size of the boil, and the season,
+but also by the composition of the soap, for if the base has been made
+from firm stock it is liable to cool quicker than a soap produced from
+soft-bodied materials.
+
+On subsidence, the contents of the pan will have divided into the
+following:--
+
+First. On top, a thin crust of soap, with perhaps a little light
+coloured fob, which is returned to the pan after the removal of the good
+soap.
+
+Second. The good settled soap, testing 62-63 per cent. fatty acids. The
+subject of removing and treatment of this layer is fully dealt with in
+the next chapter.
+
+Third. A layer of darker weak soap, termed "nigre," which on an average
+tests 33 per cent. fatty acids, and, according to the particular fit
+employed, will amount to from 15-20 per cent. of the total quantity of
+soap in the pan.
+
+The quantity of nigre may vary not only with the amount of water added
+during finishing, but is also influenced by the amount of caustic alkali
+remaining in the soap paste prior to fitting. If the free caustic
+alkali-content is high, the soap will require a large amount of water to
+attain the desired fit. This water renders the caustic into a lye
+sufficiently weak to dissolve a quantity of soap, consequently, as the
+"nigre" is a weak solution of soap together with any excess of alkali
+(caustic or carbonate) and salt which gravitates during the settling,
+the quantity is increased.
+
+Fourth. A solution containing alkaline salts, mostly carbonates and
+chlorides, with a little caustic.
+
+The amount of the layer is very variable, and doubtless, under certain
+physical conditions, this liquor has separated from the nigre.
+
+_Utilisation of Nigres._--The nigres are boiled and the liquor separated
+by graining with salt. Nigre may be utilised in various ways.
+
+(1) It may be used several times with new materials. This particularly
+refers to soaps of the "Washer" type. The colour of the nigre will
+determine the number of times it can be employed.
+
+(2) It may be incorporated with a soap of a lower grade than the one
+from which it was obtained. In this case a system is generally adopted;
+for example, soap of the best quality is made in a clean pan, the nigre
+remaining is worked up with fresh material for soap of the next quality,
+the nigre from that boil, in its turn, is admixed with a charge to
+produce a batch of third quality, and the deposited nigre from this is
+again used for a fourth quality soap--the nigre obtained from this
+latter boil would probably be transferred into the cheapened "washer" or
+perhaps if it was dark in colour into the brown soap-pan.
+
+(3) The nigre may be fitted and produce a soap similar to the original
+soap from which it was deposited. It is advisable to saponify a little
+fat with it.
+
+(4) Nigres from several boils of the same kind of soap can be collected,
+boiled, and fitted. The settled portion may be incorporated with a new
+charging to keep the resultant soap uniform in colour--unless this is
+done, the difference in colour between boils from new materials alone,
+and those containing nigre, is very noticeable. The nigre settled from
+this fitted nigre boil would be utilised in brown soap.
+
+(5) According to its colour, and consistence, a nigre may be suitable
+for the production of disinfectant, or cold-water soaps.
+
+(6) Nigre may be bleached by treatment with a 20 per cent. solution of
+stannous chloride--1 cwt. of this solution (previously heated) is
+sufficient to bleach 20 tons of nigre.
+
+_Transparent Soaps._--The production of transparent soaps has recently
+been fully studied, from a theoretical point of view, by Richardson
+(_J. Amer. Chem. Soc._, 1908, pp. 414-20), who concludes that the
+function of substances inducing transparency, is to produce a jelly and
+retard crystallisation.
+
+The old-fashioned transparent soap is prepared by dissolving, previously
+dried, genuine yellow soap in alcohol, and allowing the insoluble saline
+impurities to be deposited and removed. The alcoholic soap solution is
+then placed in a distillation apparatus, or the pan containing the
+solution is attached by means of a still head to a condenser, and the
+alcohol distilled, condensed and regained. The remaining liquid soap,
+which may be coloured and perfumed, is run into frames and allowed to
+solidify.
+
+The resultant mass is somewhat turbid, but after storage in a room at
+95° F. (35° C.) for several months, becomes transparent.
+
+The formation of the transparency is sometimes assisted and hastened by
+the addition of glycerine or a solution of cane-sugar.
+
+A patent has been granted to A. Ruch (Fr. Pat. 327,293, 1902) for the
+manufacture of transparent glycerine soap by heating in a closed vessel
+fatty acids together with the requisite quantity of alcoholic caustic
+soda solution necessary for saponification, and cooling the resultant
+soap. It is also proposed to add sugar solution.
+
+Cheaper qualities of transparent soaps are made by the cold process with
+or without the aid of alcohol and castor oil, and with the assistance of
+glycerine or cane-sugar.
+
+With the continual demand for cheaper production, sugar solution has
+gradually, in conjunction with castor oil, which produces transparency,
+superseded the use of alcohol and glycerine.
+
+For a small batch, 56 lb. Cochin cocoa-nut oil and 56 lb. sweet edible
+tallow may be taken, melted at 130° F. (54° C.), and carefully strained
+into a small steam-jacketed pan. It is imperative that the materials
+should be of the highest quality and perfectly clean. Twenty-three lb.
+of pure glycerine and 56 lb. of bright caustic soda solution made from
+high grade caustic and having a density of 72° Tw. (38° B.) are crutched
+into the fat; the alcohol, which would be 45 lb. in this example, is
+then added. The whole must be most intimately incorporated, and the pan
+covered and allowed to rest for one hour or one and a half hours.
+Saponification should ensue.
+
+To produce a transparent glycerine soap with the aid of castor oil, and
+with or without the use of alcohol, the following is the procedure:--
+
+Cochin cocoa-nut oil, sweet edible tallow, and castor oil, of each 56
+lb. are taken, warmed to 130° F. (54° C.), and carefully strained into
+the jacketed pan. If it is desired to use glycerine and cane sugar
+solution, and no alcohol, the glycerine (25 lb.) is now stirred into the
+fats together with the requisite (83 lb.) caustic soda solution 72° Tw.
+(38° B.). If it is intended to use alcohol and sugar, and no glycerine,
+the latter is replaced by 47 lb. of alcohol, and added after the
+incorporation of the caustic soda lye.
+
+The whole being thoroughly crutched, the pan is covered and
+saponification allowed to proceed for one hour or one and a half hours.
+Should the saponification for some reason be retarded, a little steam
+may be very cautiously admitted to the jacket of the pan, the mass well
+crutched until the reaction commences, and the whole allowed to rest the
+specified time.
+
+Whilst saponification is proceeding, the "sugar solution" is prepared by
+dissolving 50 lb. cane sugar in 50 lb. water, at 168° F. (76° C.), to
+which may be added 5 lb. soda crystals, and any necessary colouring
+matter. The water used for this solution should be as soft as possible,
+as hard water is liable to produce opaque streaks of lime soap.
+
+It is absolutely necessary before proceeding further to ensure that
+saponification is complete. A greasy, soft feel and the presence of
+"strength" (caustic) would denote incomplete saponification--this can
+only be remedied by further heating and crutching. Deficiency of caustic
+alkali should also be avoided, and, if more lye is required, great care
+must be exercised in its addition.
+
+Saponification being completed, the sugar solution is carefully and
+gradually crutched into the soap; when the contents of the pan have
+become a homogeneous and syrupy mass, the crutching is discontinued, and
+the pan is covered for one hour. The heat of the soap in the pan should
+not exceed 170° F. (77° C.).
+
+Having rested the necessary period, the soap will have a slight froth on
+the surface, but will be clear underneath and appear dark. Samples may
+now be withdrawn, cooled, and examined prior to framing. If the process
+has been successfully performed the soap will be firm and transparent,
+of uniform colour, and possess only a faintly alkaline taste.
+
+If the sample be firm but opaque, more sugar solution is required; this
+should be added very carefully whilst crutching, an excess being
+specially guarded against. If the sample be soft, although transparent,
+and the alkaline taste not too pronounced, the soap evidently contains
+an excess of water, which may be remedied by the addition of a small
+quantity of soda ash; too much soda ash (carbonates) must be avoided,
+lest it should produce efflorescence.
+
+Having examined the soap and found it to be correct, or having remedied
+its defects, the soap in the pan is allowed to cool to 145° F. (63° C.)
+and perfume added. The soap is now quickly filled into narrow frames and
+allowed to cool rapidly.
+
+The blocks of soap should not be stripped until quite cold throughout,
+and they should be allowed to stand open for a while before slabbing.
+When freshly cut into tablets, the soap may appear somewhat turbid, but
+the brightness comes with the exposure it will receive prior to stamping
+and wrapping.
+
+_Saponifying Mineral Oil._--This sounds somewhat incongruous, as mineral
+oil is entirely unsaponifiable. Most of the suggestions for this purpose
+consist of the incorporation of mineral oil, or mineral oil emulsified
+by aid of Quillaia bark, with a cocoa-nut oil soap, and in all these
+instances the hydrocarbon merely exists in suspension.
+
+G. Reale (Fr. Pat. 321,510, 1902), however, proposes to heat mineral oil
+together with spermaceti and strong alkali, and states that he
+transforms the hydrocarbons into alcohols, and these, absorbing oxygen,
+become fatty acids, which are converted into soap by means of the
+alkali.
+
+In this connection may be quoted the interesting work of Zelinsky
+(_Russ. Phys. Chem. Ges. Zeits. Angew. Chem._, 1903, 37). He obtained
+substances, by acting with carbon dioxide upon magnesia compounds of
+chlorinated fractions of petroleum, which when decomposed by dilute
+sulphuric acid, yielded various organic acids. One of these acids on
+heating with glycerine formed tri-octin, which had the properties of a
+fat.
+
+Dr. Engler, in confirmation of the theory of the animal origin of some
+petroleums, obtained what might be described as petroleum (for it
+contained almost all the hydrocarbons present in the natural mineral
+oil) by distilling animal fats and oils under pressure.
+
+_Electrical Production of Soap._--Attempts have been made to produce
+soap electrically by Messrs. Nodon, Brettonneau and Shee (Eng. Pat.
+22,129, 1897), and also by Messrs. Merry and Noble (Eng. Pat. 2,372,
+1900).
+
+In the former patent, a mixture of soda-lye and fat is agitated by
+electricity at a temperature of 194°-212° F. (90°-100° C.), while in the
+latter caustic alkali is electrolytically produced from brine, and
+deposited on wire-netting in the presence of fat, which is thereby
+saponified.
+
+
+
+
+CHAPTER VI.
+
+TREATMENT OF SETTLED SOAP.
+
+     _Cleansing--Crutching--Liquoring of
+     Soaps--Filling--Neutralising, Colouring and
+     Perfuming--Disinfectant Soaps--Framing--Slabbing--Barring--Open
+     and Close Piling--Drying--Stamping--Cooling._
+
+
+_Cleansing._--After completion of saponification, and allowing the
+contents of the pan to settle into the various layers, as described in
+the preceding chapter, the actual soap, forming the second layer, is now
+transferred to the frames, this being generally termed "cleansing" the
+soap. The thin crust or layer at the top of the pan is gently removed,
+and the soap may be either ladled out and conveyed to the frames, or
+withdrawn by the aid of a pump from above the nigre through a skimmer
+(Fig. 1), and pipe, attached by means of a swivel joint (Fig. 2) (which
+allows the skimmer pipe to be raised or lowered at will by means of a
+winch, Fig. 3), to a pipe fitted in the side of the pan as fully shown
+in Fig. 4, or the removal may be performed by gravitation through some
+mechanical device from the side of the copper.
+
+[Illustration: FIG. 1.--Skimmer, with flange for attachment to
+skimmer-pipe.]
+
+Every precaution is taken to avoid the presence of nigre in the soap
+being cleansed.
+
+[Illustration: FIG. 2.--Swivel-joint.]
+
+The temperature at which soap may be cleansed depends on the particular
+grade--soaps requiring to be liquored should not be cleansed too hot or
+a separation will take place, 150° F. (66° C.) may be taken as a
+suitable temperature for this class of soap; in the case of firm soaps,
+such as milling base, where cooling is liable to take place in the pan
+(and thus affect the yield), the temperature may be 165°-170° F.
+(74°-77° C.). This latter class of soap is generally run direct to the
+frames and crutched by hand, or, to save manual labour, it may be run
+into a power-driven crutching pan (neutralising material being added if
+necessary) and stirred a few times before framing.
+
+[Illustration: FIG. 3.--Winch.]
+
+[Illustration: FIG. 4.--Soap-boiling pan, showing skimmer pipe, swivel
+and winch.]
+
+[Illustration: FIG. 5.--Hand crutch.]
+
+[Illustration: FIG. 6.--Mechanical crutcher.]
+
+_Crutching._--This consists of stirring the hot soap in the frames by
+hand crutches (Fig. 5) until the temperature is sufficiently lowered and
+the soap begins to assume a "ropiness". Crutching may also be performed
+mechanically. There are various types of mechanical crutchers,
+stationary and travelling. They may be cylindrical pans, jacketed or
+otherwise, in the centre of which is rotated an agitator, consisting of
+a vertical or horizontal shaft carrying several blades (Fig. 6) or the
+agitator may take the form of an Archimedean screw working in a cylinder
+(Fig. 7).
+
+[Illustration: FIG. 7.--Mechanical crutcher.]
+
+The kind of soap to be crutched, whether thin or stiff, will determine
+the most suitable type for the purpose. The former class includes
+"washer" soap which is generally neutralised, and coloured and perfumed,
+if necessary, in these crutching pans, and in that case they are merely
+used for mixing the liquids with the hot soap prior to its passage along
+wooden spouts (Fig. 8) provided with outlets over the frames, in which
+the crutching is continued by hand. In the case of stiff soaps requiring
+complete incorporation of liquor, the screw type is preferable, the soap
+being forced upwards by the screw, and descending between the cylinder
+and the sides of the pan, while the reverse action can also be brought
+into play. The completion of crutching is indicated by the smoothness
+and stiffness of the soap when moved with a trowel, and a portion taken
+out at this point and cooled should present a rounded appearance. When
+well mixed the resultant product is emptied directly into wheel-frames
+placed underneath the outlet of the pan. It is important that the blades
+or worm of the agitating gear be covered with soap to avoid the
+occlusion of air and to prevent the soap becoming soft and spongy.
+
+[Illustration: FIG. 8.--Wooden soap spout.]
+
+_Liquoring of Soaps._--This consists of the addition of various alkaline
+solutions to soap to produce different qualities, and is best performed
+in the crutching machines, although it is in some instances carried out
+in the frames. In the history of soap-making a large number and variety
+of substances have been suggested for the purpose of accomplishing some
+real or supposed desirable effect when added to soap. Many of these have
+had only a very short existence, and others have gradually fallen out of
+use.
+
+Amongst the more practical additions most frequently adopted may be
+mentioned carbonate of soda, silicate of soda, and pearl ash (impure
+carbonate of potash). The carbonate of soda may be used in the form of
+"soda crystals," which, containing 62.9 per cent. of water, dissolves in
+its own water of crystallisation on heating, and is in that manner added
+to the hot soap. In the case of weak-bodied soap, this addition gives
+firmness and tends to increase the detergent qualities.
+
+The soda carbonate may also be added to soap as a solution of soda ash
+(58° alkali) either concentrated, 62° Tw. (34° B.), or of various
+strengths from 25° Tw. (16° B.) upwards. This solution stiffens and
+hardens soap, and the addition, which must not be excessive, or
+efflorescence will occur, is generally made at a temperature of 140° F.
+(60° C.). Care should always be taken in the choice of solutions for
+liquoring. Strong soda ash solution with a firm soap will result in a
+brittle product, whereas the texture of a weak soap would be greatly
+improved by such addition.
+
+A slight addition of a weak solution of pearl ash, 4°-8° Tw. (2.7-5.4°
+B.), improves the appearance of many soaps intended for household
+purposes.
+
+For yellow soaps, containing a low percentage of fatty acids, solutions
+of silicate of soda of varying strengths are generally used.
+
+It is always advisable to have a test sample made with the soap to
+ascertain what proportion and what strength of sodium silicate solution
+is best suited for the grade of soap it is desired to produce. It is
+important that the soap to be "silicated" should be distinctly alkaline
+(_i.e._, have a distinct caustic taste), or the resultant soap is liable
+to become like stone with age. The alkaline silicate of soda (140° Tw.,
+59.5° B.) is the quality most convenient for yellow soaps; this may be
+diluted to the desired gravity by boiling with water. For a reduction of
+3-4 per cent. fatty acids content, a solution of 6° Tw. (4° B.)
+(boiling) is most suitable, and if the reduction desired is greater, the
+density of the silicate solution should be increased; for example, to
+effect a reduction of 20 per cent. fatty acids content, a solution of
+18° Tw. (12° B.) (boiling) would probably be found to answer.
+
+In some instances 140° Tw. (59.5° B.) silicate may be added; experiment
+alone will demonstrate the amount which can be satisfactorily
+incorporated without the soap becoming "open," but 1/10 of the quantity
+of soap taken is practically a limit, and it will be found that the
+temperature should be low; the same quantity of silicate at different
+temperatures does not produce the same result. Various other strengths
+of sodium silicate are employed, depending upon the composition and body
+of the soap base--neutral silicate 75° Tw. (39.4° B.) also finds favour
+with some soap-makers. Mixtures of soda crystals or soda ash solution
+with silicate of soda solution are used for a certain grade of soap,
+which is crutched until smooth and stiff. Glauber's salt (sodium
+sulphate) produces a good smooth surface when added to soap, but, owing
+to its tendency to effloresce more quickly than soda carbonate, it is
+not so much used as formerly.
+
+Common salt sometimes forms an ingredient in liquoring mixtures.
+Potassium chloride and potassium silicate find a limited use for
+intermixing with soft soaps.
+
+It will be readily understood that hard and fast rules cannot be laid
+down for "liquoring" soap, and the correct solution to be employed can
+only be ascertained by experiment and experience, but the above
+suggestions will prove useful as a guide towards good results. A smooth,
+firm soap of clear, bright, glossy appearance is what should be aimed
+at.
+
+_Filling._--Some low-grade soaps contain filling, which serves no useful
+purpose beyond the addition of weight. Talc is the most frequently used
+article of this description. It consists of hydrated silicate of
+magnesium and, when finely ground, is white and greasy to the touch. The
+addition of this substance to the hot soap is made by suspending it in
+silicate of soda solution.
+
+Whatever filling material is used, it is important that the appearance
+of the soap should not be materially altered.
+
+_Neutralising, Colouring and Perfuming._--The free caustic alkali in
+soap, intended for toilet or laundry purposes, is usually neutralised
+during the cleansing, although some soap manufacturers prefer to
+accomplish this during the milling operation. Various materials have
+been recommended for the purpose, those in most general use being sodium
+bicarbonate, boric acid, cocoa-nut oil, stearic acid, and oleic acid.
+
+The best method is the addition of an exact quantity of sodium
+bicarbonate (acid sodium carbonate), which converts the caustic alkali
+into carbonate. The reaction may be expressed by the equation:--
+
+          NaOH  +      NaHCO_{3}     =   Na_{2}CO_{3}    + H_{2}O
+    Caustic soda  Bicarbonate of soda  Carbonate of soda    Water
+
+Boric acid in aqueous or glycerine solutions, and borax (biborate of
+soda) are sometimes used, but care is necessary in employing these
+substances, as any excess is liable to decompose the soap.
+
+The addition of cocoa-nut oil is unsatisfactory, the great objection
+being that complete saponification is difficult to ensure, and, further,
+there is always the liability of rancidity developing. Stearic and oleic
+acids are more suitable for the purpose, but oleic acid has the
+disadvantage that oleates are very liable to go rancid.
+
+A large number of other substances have been proposed, and in many
+instances patented, for neutralising the free caustic alkali. Among
+these may be mentioned--Alder Wright's method of using an ammoniacal
+salt, the acid radicle of which neutralises the caustic alkali, ammonia
+being liberated; the use of sodium and potassium bibasic phosphate (Eng.
+Pat. 25,357, 1899); a substance formed by treating albumen with formalin
+(Eng. Pat., 8,582, 1900); wheat glutenin "albuminoses" (albumen after
+acid or alkaline treatment); malt extract; and egg, milk, or vegetable
+albumen.
+
+The colouring matter used may be of either vegetable or coal-tar origin,
+and is dissolved in the most suitable medium (lye, water, or fat). The
+older types of colouring matter--such as cadmium yellow, ochres,
+vermilion, umbers--have been superseded.
+
+In the production of washer household soaps, a small quantity of perfume
+is sometimes added.
+
+_Disinfectant Soaps._--To the soap base, which must be strong to taste,
+is added from 3 to 4 per cent. of coal-tar derivatives, such as carbolic
+acid, cresylic acid, creosote, naphthalene, or compounds containing
+carbolic acid and its homologues. The incorporation is made in the
+crutching pan, and further crutching may be given by hand in the frames.
+
+_Framing._--The object of framing is to allow the soap to solidify into
+blocks. The frames intended for mottled soaps, which require slow
+cooling, are constructed of wood, often with a well in the base to allow
+excess of lye to accumulate--for other soaps, iron frames are in general
+use. The frame manufactured by H. D. Morgan of Liverpool is shown in
+Fig. 9.
+
+As soon as the frame is filled, or as soon as the crutching in the frame
+is finished, the soap is smoothed by means of a trowel, leaving in the
+centre a heap which slopes towards the sides. Next day the top of the
+soap is straightened or flattened with a wooden mallet, this treatment
+assisting in the consolidation.
+
+[Illustration: FIG. 9.--Soap frame.]
+
+[Illustration: FIG. 10.--Slabbing machine.]
+
+The length of time the soap should remain in frames is dependent on the
+quality, quantity, and season or temperature, and varies usually from
+three to seven days. When the requisite period has elapsed, the sides
+and ends of the frames are removed, and there remains a solid block of
+soap weighing from 10 to 15 cwt. according to the size of frame used.
+The blocks, after scraping and trimming, are ready for cutting into
+slabs.
+
+_Slabbing._--This may be done mechanically by pushing the block of soap
+through a framework containing pianoforte wires fixed at equi-distances
+(Fig. 10, which shows a machine designed by E. Forshaw & Son, Ltd.), or
+the soap may be out by hand by pulling a looped wire through the mass
+horizontally along lines previously scribed, or, for a standard sized
+slab, the wire may be a fixture in a box-like arrangement, which is
+passed along the top of the soap, and the distance of the wire from the
+top of the box will be the thickness of the slab (Fig. 11).
+
+[Illustration: FIG. 11.--Banjo slabber.]
+
+All tallow soaps should be slabbed whilst still warm, cut into bars, and
+open-piled immediately; if this type of soap is cold when slabbed its
+appearance will be very much altered.
+
+_Barring._--The slabs are out transversely into bars by means of the
+looped wire, or more usually by a machine (Fig. 12), the lower framework
+of which, containing wires, is drawn through the soap placed on the
+base-board; the framework is raised, and the bars fall upon the shelf,
+ready for transference into piles. It has long been the custom in
+England to cut bars of soap 15 inches long, and weighing 3 lb. each, or
+37-1/2 bars of soap to the cwt., but in recent years a demand has arisen
+for bars of so many various weights that it must be sometimes a
+difficult matter to know what sizes to stock.
+
+In another type of barring machine, portions of the slab, previously cut
+to size, are pushed against a framework carrying wires, and the bars
+slide along a table ready for handling (Fig. 13).
+
+In cutting machines, through which "washer" household soap is being
+passed, the bar is pushed at right angles through another frame
+containing wires, which divides it into tablets; these may be received
+upon racks and are ready for drying and stamping. It is needless to say
+that the slabs and tablets are cut with a view to reducing the amount of
+waste to the lowest possible limit. Such a machine, made by E. Forshaw &
+Son, Ltd., is shown in Fig. 14.
+
+[Illustration: FIG. 12.--Barring machine.]
+
+[Illustration: FIG. 13.--Bar-cutting machine.]
+
+[Illustration: FIG. 14.--Tablet-cutting machine.]
+
+_Open- and Close-piling._--As remarked previously, tallow soaps should
+be cut whilst warm, and the bars "open-piled," or stacked across each
+other in such a way that air has free access to each bar for a day. The
+bar of soap will skin or case-harden, and next day may be "close-piled,"
+or placed in the storage bins, where they should remain for two or three
+weeks, when they will be in perfect condition for packing into boxes
+ready for distribution.
+
+[Illustration: FIG. 15.--Soap stamp.]
+
+_Drying._--"Oil soaps," as soaps of the washer type are termed, do not
+skin sufficiently by the open-piling treatment, and are generally
+exposed on racks to a current of hot air in a drying chamber in order to
+produce the skin, which prevents evaporation of water, and allows of an
+impression being given by the stamp without the soap adhering to the
+dies. It is of course understood that heavily liquored soaps are, as a
+rule, unsuitable for the drying treatment, as the bars become unshapely,
+and lose water rapidly.
+
+_Stamping._--Bar soaps are usually stamped by means of a hand-stamp
+containing removable or fixed brass letters (Fig. 15), with a certain
+brand or designation of quality and the name of the manufacturer or
+vendor, and are now ready for packing into boxes.
+
+A very large bulk of the soap trade consists of the household quality in
+tablet form, readily divided into two cakes. These are stamped in the
+ordinary box moulds with two dies--top and bottom impressions--the
+die-plates, being removable, allow the impressions to be changed. This
+type of mould (Fig. 16) can be adjusted for the compression of tablets
+of varying thickness, the box preventing the escape of soap. We are
+indebted to E. Forshaw & Son, Ltd., for this illustration.
+
+[Illustration: FIG. 16.--Box mould.]
+
+The stamping machine may be worked by hand (Fig. 17) or power driven.
+Where large quantities of a particular tablet have to be stamped, one of
+the many automatic mechanical stampers in existence may be employed, the
+tablets being conveyed to and from the dies by means of endless belts.
+Such a machine is shown in the accompanying illustration (Fig. 18).
+
+If necessary, the soap is transferred to racks and exposed to the air,
+after which it is ready for wrapping, which is generally performed by
+manual labour, although in some instances automatic wrapping machines
+are in use.
+
+Cardboard cartons are also used for encasing the wrapped tablets, the
+object being that these are more conveniently handled by tradesmen and
+may be advantageously used to form an attractive window display.
+
+_Cooling._--Many attempts have been made to shorten the time required
+for the framing and finishing of soap, by cooling the liquid soap as it
+leaves the pan.
+
+[Illustration: FIG. 17.--Soap-stamping machine, showing box mould.]
+
+With milling base, this is successfully accomplished in the
+Cressonnières' plant, by allowing the hot soap to fall upon the
+periphery of a revolving drum which can be cooled internally by means of
+water.
+
+[Illustration: FIG. 18.--Automatic stamper.]
+
+In the case of household soaps, where the resultant product must be of
+good appearance and have a firm texture, the difficulty is to produce a
+bar fit for sale after the cooling has been performed, as soap which has
+been suddenly chilled lacks the appearance of that treated in the
+ordinary way. Several patents have been granted for various methods of
+moulding into bars in tubes, where the hot soap is cooled by being
+either surrounded by running water in a machine of similar construction
+to a candle machine, or rotated through a cooling medium; and numerous
+claims have been made both for mechanical appliances and for methods of
+removing or discharging the bars after cooling. In many instances these
+have proved unsatisfactory, owing to fracture of the crystalline
+structure. Moreover, in passing through some of the devices for
+solidification after chilling, the soap is churned by means of a worm or
+screw, and this interferes with the firmness of the finished bar, for,
+as is well known, soap which has been handled too much, does not regain
+its former firmness, and its appearance is rendered unsatisfactory.
+
+A form of apparatus which is now giving satisfactory results is the
+Leimdoerfer continuous cooler (Fig. 19). This consists of a fixed
+charging hopper, A, a portable tank, B, containing tubes, and a
+detachable box, C, which can be raised or lowered by means of a screw,
+D. The bottom of the hopper is fitted with holes corresponding with the
+cooling tubes, _e_, and closed by plugs _c_, attached to a frame _b_,
+which terminates above in a screw spindle _a_, by means of which the
+frame and plugs can be raised and lowered so as to permit or stop the
+outflow of soap into the cooling tubes. The tubes are closed at the
+bottom by slides _d_, and the box B, in which they are mounted, is
+carried on a truck running on rails. The charging hopper can be
+connected with the soap-pan by a pipe, and when the hopper is filled
+with liquid soap the plugs _c_ are raised and the air in the box C
+exhausted, thus causing the soap to descend into the cooling tubes.
+
+[Illustration: FIG. 19.--Leimdoerfer cooler.]
+
+The slides _d_ are closed, the screw D released, and the box B moved
+away to make room for another. At the end of the rail track is an
+ejecting device which pushes the cooled soap out of the tubes, and the
+truck is run back on a side track to the machine for use over again. In
+this way the apparatus can be worked continuously, the soap being
+received from the cooling pipes on a suitable arrangement for transport
+to the press or store room.
+
+A similar idea has been made the subject of a patent by Holoubek (Eng.
+Pat. 24,440, 1904, Fig. 20). The soap is run into frames or moulds
+having open sides, which are closed by being clamped with screws and
+pressure plates between cooling tubes through which water circulates.
+
+[Illustration: FIG. 20.--Holoubek's cooler.]
+
+
+
+
+CHAPTER VII.
+
+TOILET, TEXTILE AND MISCELLANEOUS SOAPS.
+
+     _Toilet Soaps--Cold Process Soaps--Settled Boiled
+     Soaps--Remelted Soaps--Milled Soaps--Drying--Milling and
+     Incorporating Colour, Perfume, or
+     Medicament--Perfume--Colouring Matter--Neutralising and
+     Superfatting
+     Material--Compressing--Cutting--Stamping--Medicated
+     Soaps--Ether Soap--Floating Soaps--Shaving Soaps--Textile
+     Soaps--Soaps for Woollen, Cotton and Silk Industries--Patent
+     Textile Soaps--Miscellaneous Soaps._
+
+
+_Toilet Soaps._--By the term "toilet soap" is inferred a soap specially
+adapted for toilet use by reason not only of its good detergent and
+lathering qualities, but also on account of its freedom from caustic
+alkali and any other ingredient likely to cause irritation or injury to
+the skin.
+
+Toilet soaps may be simply classified according to their method of
+preparation into the following four classes:--
+
+          (1) Cold process soaps.
+          (2) Settled boiled soaps.
+          (3) Remelted soaps.
+          (4) Milled soaps.
+
+Soaps of the first class are of comparatively trifling importance,
+having been superseded by the other qualities. Details of the "cold
+process" have already been given on page 46; it is only necessary to add
+the desired perfume and colouring matter to the soap.
+
+The second class consists of good quality settled soaps, direct from the
+copper, to which have been added, prior to framing, suitable perfume and
+colouring matter, also, if necessary, dealkalising materials.
+
+The third class is represented by soaps made by the old English method
+of remelting, which are often termed "perfumers'," or "little pan"
+soaps. The soap-base or mixture of various kinds of soap is remelted in
+a steam-jacketed pan, or pan provided with steam coils, and agitated.
+The agitation must not be too vigorous or lengthy, or the soap will
+become aerated. When all the soap is molten, additions of pearl ash
+solution are made to give it a finer and smoother texture, render it
+more transparent, and increase its lathering properties. The necessary
+colour, in a soluble form, is well incorporated, and lastly the perfume.
+Owing to volatilisation, much of the perfume is lost when added to hot
+soap, and it is necessary to add a large quantity to get the desired
+odour; hence the cheaper essential oils have to be used, so that the
+perfume of this class of soap is not so delicate as that of milled
+soaps, although it is quite possible to produce remelted soaps as free
+from uncombined alkali as a milled toilet soap.
+
+Palm-oil soap often forms the basis for yellow and brown toilet soaps of
+this class. The old-fashioned Brown Windsor soap was originally a curd
+soap that with age and frequent remelting had acquired a brown tint by
+oxidation of the fatty acids--the oftener remelted the better the
+resultant soap.
+
+Medicaments are sometimes added to these soaps, _e.g._, camphor, borax,
+coal-tar, or carbolic. Oatmeal and bran have been recommended in
+combination with soap for toilet purposes, and a patent (Eng. Pat.
+26,396, 1896) has been granted for the use of these substances together
+with wood-fibre impregnated with boric acid.
+
+After cooling in small frames, the soap is slabbed, and cut into blocks,
+and finally into portions suitable for stamping in a press (hand or
+steam driven) with a design or lettering on each side.
+
+_Milled Toilet Soaps._--Practically all high-class soaps now on the
+market pass through the French or milling process. This treatment, as
+its name implies, was first practised by the French who introduced it to
+this country, and consists briefly of (i.) drying, (ii.) milling and
+incorporating colour, perfume or medicament, (iii.) compressing, and
+(iv.) cutting and stamping.
+
+The advantages of milled soap over toilet soap produced by other methods
+are that the former, containing less water and more actual soap, is more
+economical in use, possesses a better appearance, and more elegant
+finish, does not shrink or lose its shape, is more uniform in
+composition, and essential oils and delicate perfumes may be
+incorporated without fear of loss or deterioration.
+
+Only soap made from best quality fats is usually milled, a suitable base
+being that obtained by saponifying a blend of the finest white tallow
+with a proportion, not exceeding 25 per cent., of cocoa-nut oil, and
+prepared as described in Chapter V.
+
+The first essential of a milling base is that the saponification should
+be thorough and complete; if this is not ensured, rancidity is liable to
+occur and a satisfactory toilet soap cannot be produced. The soap must
+not be short in texture or brittle and liable to split, but of a firm
+and somewhat plastic consistency.
+
+(i.) _Drying._--The milling-base, after solidification in the frames,
+contains almost invariably from 28 to 30 per cent. of water, and this
+quantity must be reduced to rather less than half before the soap can be
+satisfactorily milled. Cutting the soap into bars or strips and open
+piling greatly facilitates the drying, which is usually effected by
+chipping the soap and exposing it on trays to a current of hot air at
+95-105° F. (35-40° C.).
+
+There are several forms of drying chambers in which the trays of chips
+are placed upon a series of racks one above another, and warm air
+circulated through, and Fig. 21 shows a soap drying apparatus with fan
+made by W. J. Fraser & Co., Ltd., London.
+
+The older method of heating the air by allowing it to pass over a pipe
+or flue through which the products of combustion from a coke or coal
+fire are proceeding under the floor of the drying chamber to a small
+shaft, has been superseded by steam heat. The air is either drawn or
+forced by means of quickly revolving fans through a cylinder placed in a
+horizontal position and containing steam coils, or passed over
+steam-pipes laid under the iron grating forming the floor of the
+chamber.
+
+[Illustration: FIG. 21.--Soap-drying apparatus.]
+
+It will be readily understood that in the case of a bad conductor of
+heat, like soap-chippings, it is difficult to evaporate moisture
+without constantly moving them and exposing fresh surfaces to the
+action of heat.
+
+In the Cressonnières' system, where the shavings of chilled soap are
+dried by being carried through a heated chamber upon a series of endless
+bands (the first discharging the contents on to a lower belt which
+projects at the end, and is moving in the opposite direction, and so
+on), this is performed by intercepting milling rollers in the system of
+belts (Eng. Pat. 4,916, 1898) whereby the surfaces exposed to the drying
+are altered, and it is claimed that the formation of hardened crust is
+prevented.
+
+In the ordinary methods of drying, the chips are frequently moved by
+hand to assist uniform evaporation.
+
+The degree of saturation of the air with moisture must be taken into
+consideration in regulating the temperature and flow of air through the
+drying chamber, and for this purpose the use of a hygrometer is
+advantageous.
+
+It is very important that the correct amount of moisture should be left
+in the soap, not too much, nor too little; the exact point can only be
+determined by judgment and experience, and depends to a considerable
+extent upon the nature of the soap, and also on the amount of perfume or
+medicament to be added, but speaking generally, a range of 11 to 14 per
+cent. gives good results. If the soap contains less than this amount it
+is liable to crumble during the milling, will not compress
+satisfactorily, and the finished tablet may have a tendency to crack and
+contain gritty particles so objectionable in use. If, on the other hand,
+the soap is left too moist, it is apt to stick to the rollers and mill
+with difficulty, and during compression the surface assumes a blistered
+and sticky appearance.
+
+(ii.) _Milling and Incorporation of Colour, Perfume or Medicament._--The
+object of milling is to render the soap perfectly homogeneous, and to
+reduce it to a state in which colour, perfume, or any necessary
+neutralising material or other substance may be thoroughly incorporated.
+The milling machine consists of smooth granite rollers, fitted with
+suitable gearing and working in an iron framework (Fig. 22). The rollers
+are connected in such a manner that they rotate at different speeds, and
+this increases the efficiency of the milling, and ensures that the
+action of the rollers is one of rubbing rather than crushing.
+
+By means of suitably arranged screws the pressure of the rollers on one
+another can be adjusted to give the issuing soap any desired thickness;
+care should be taken that the sheets of soap are not unnecessarily thick
+or the colour and odour will not be uniform.
+
+The soap, in the form of chips, is introduced on to the rollers through
+a hopper, and after one passage through the mill, from bottom to top,
+one of the serrated knife edges is applied and the ribbons of the soap
+are delivered into the top of the hopper where the colour, perfume, and
+any other desired admixture is added, and the milling operation repeated
+three or four times. When the incorporation is complete the other
+scraper is fixed against the top roller and the soap ribbon passed into
+the receptacle from which it is conveyed to the compressor. A better
+plan, however, especially in the case of the best grade soaps, where the
+perfumes added are necessarily more delicate and costly, is to make the
+addition of the perfume when the colour has been thoroughly mixed
+throughout the mass. Another method is to mill once and transfer the
+mass to a rotary mixing machine, fitted with internal blades, of a
+peculiar form, which revolve in opposite directions one within the other
+as the mixer is rotated. The perfume, colouring matter, etc., are added
+and the mixer closed and set in motion, when, after a short time, the
+soap is reduced to a fine granular condition, with the colour and
+perfume evenly distributed throughout the whole. By the use of such
+machines, the loss of perfume by evaporation, which during milling is
+quite appreciable, is reduced to a minimum, and the delicacy of the
+aroma is preserved unimpaired.
+
+[Illustration: FIG. 22.--Milling machine.]
+
+Prolonged milling, especially with a suitable soap base, tends to
+produce a semi-transparent appearance, which is admired by some, but the
+increased cost of production by the repeated milling is not accompanied
+by any real improvement in the soap.
+
+_Perfume._--The materials used in perfuming soap will be dealt with
+fully in the next chapter. The quantity necessary to be added varies
+considerably with the nature of the essential oils, and also the price
+at which the soap is intended to be sold. In the cheaper grades of
+milled soaps the quantity will range from 10-30 fluid ozs. per cwt., and
+but rarely exceeds 18-20 ozs., whereas in more costly soaps as much as
+40-50 fluid ozs. are sometimes added to the cwt.
+
+_Colouring Matter._--During recent years an outcry has been made against
+highly coloured soaps, and the highest class soaps have been
+manufactured either colourless or at the most with only a very delicate
+tint. It is obvious that a white soap guarantees the use of only the
+highest grade oils and fats, and excludes the introduction of any rosin,
+and, so far, the desire for a white soap is doubtless justified. Many
+perfumes, however, tend to quickly discolour a soap, hence the advantage
+of giving it a slight tint. For this purpose a vegetable colouring
+matter is preferable, and chlorophyll is very suitable.
+
+[Illustration: FIG. 23.--Compressor.]
+
+A demand still exists for brightly coloured soaps, and this is usually
+met by the use of coal-tar dyes. The quantity required is of course
+extremely small, so that no harm or disagreeable result could possibly
+arise from their use.
+
+_Neutralising and Superfatting Material._--If desired, the final
+neutralisation of free alkali can be carried out during the milling
+process, any superfatting material being added at the same time. The
+chief neutralising reagents have already been mentioned in Chapter VI.
+
+With regard to superfatting material, the quantity of this should be
+very small, not exceeding 6-8 ozs. per cwt: The most suitable materials
+are vaseline, lanoline, or spermaceti.
+
+[Illustration: FIG. 24--Hand soap-stamping press.]
+
+(iii.) _Compressing._--The next stage is the compression and binding of
+the soap ribbons into a solid bar suitable for stamping, and the plant
+used (Fig. 23) for this purpose is substantially the same in all
+factories. The soap is fed through a hopper into a strong metal
+conical-shaped tube like a cannon, which tapers towards the nozzle, and
+in which a single or twin screw is moving, and the soap is thereby
+forced through a perforated metallic disc, subjected to great pressure,
+and compressed. The screws must be kept uniformly covered with shavings
+during compression to obviate air bubbles in the soap.
+
+[Illustration: FIG. 25.--Screw press.]
+
+The soap finally emerges through the nozzle (to which is attached a
+cutter of suitable shape and size according to the form it is intended
+the final tablet to take) as a long, polished, solid bar, which is cut
+with a knife or wire into lengths of 2 or 3 feet, and if of satisfactory
+appearance, is ready for cutting and stamping. The nozzle of the plodder
+is heated by means of a Bunsen burner to about 120° or 130° F. (49°-55°
+C.) to allow the soap to be easily forced out, and this also imparts a
+good gloss and finish to the ejected bar--if the nozzle is too hot,
+however, the soap will be blistered, whereas insufficient heat will
+result in streaky soap of a poor and dull appearance.
+
+(iv.) _Cutting and Stamping._--In cutting the soap into sections for
+stamping, the cutter should shape it somewhat similar to the required
+finished tablet.
+
+Many manufacturers cut the soap into sections having concave ends, and
+in stamping, the corners are forced into the concavity, with the result
+that unsightly markings are produced at each end of the tablet. It is
+preferable to have a cutter with convex ends, and if the stamping is to
+be done in a pin mould the shape should be a trifle larger than the
+exact size of the desired tablet.
+
+[Illustration: FIG. 26--Pin mould.]
+
+The stamping may be performed by a hand stamper (Fig. 24), a screw press
+(Fig. 25), or by a steam stamper. The screw press works very
+satisfactorily for toilet soaps.
+
+There are two kinds of moulds in use for milled soaps:--
+
+(_a_) _Pin Moulds_ in which tablets of one size and shape only can be
+produced (Fig. 25). The edges of the mould meet very exactly, the upper
+part of the die carries two pins attached to the shoulder, and these are
+received into two holes in the shoulder of the bottom plate. The
+superfluous soap is forced out as the dies meet.
+
+(_b_) _Band or Collar Moulds._--In this form (Fig, 27) the mould may be
+adjusted to stamp various sized tablets, say from 2 ozs. to 5-1/3 ozs.
+and different impressions given by means of removable die plates. The
+band or collar prevents the soap squeezing out sideways. We are indebted
+to R. Forehaw & Son, Ltd., for the loan of this illustration.
+
+It is usual to moisten the soap or mould with a dilute solution of
+glycerine if it should have a tendency to stick to the die plates.
+
+The soap is then ready for final trimming, wrapping, and boxing.
+
+[Illustration: FIG. 27--Band Mould.]
+
+
+MEDICATED SOAPS.
+
+The inherent cleansing power of soap renders it invaluable in combating
+disease, while it also has distinct germicidal properties, a 2 per cent.
+solution proving fatal to B. coli communis in less than six hours, and
+even a 1 per cent. solution having a marked action on germs in fifteen
+minutes.
+
+Many makers, however, seek more or less successfully to still further
+increase the value of soap in this direction by the incorporation of
+various drugs and chemicals; and the number of medicated soaps on the
+market is now very large. Such soaps may consist of either hard or soft
+soaps to which certain medicaments have been added, and can be roughly
+divided into two classes, (_a_) those which contain a specific for
+various definite diseases, the intention being that the remedy should be
+absorbed by the pores of the skin and thus penetrate the system, and
+(_b_) those impregnated with chemicals intended to act as antiseptics or
+germicides, or, generally, as disinfectants.
+
+The preparation of medicinal soaps appears to have been first taken up
+in a scientific manner by Unna of Hamburg in 1886, who advocated the use
+of soap in preference to plasters as a vehicle for the application of
+certain remedies.
+
+Theoretically, he considered a soap-stock made entirely from beef tallow
+the most suitable for the purpose, but in practice found that the best
+results were obtained by using a superfatted soap made from a blend of
+one part of olive oil with eight parts of beef tallow, saponified with a
+mixture of two parts of soda to one part of potash, sufficient fat being
+employed to leave an excess of 3 or 4 per cent. unsaponified. Recent
+researches have shown, however, that even if a superfatted soap-base is
+beneficial for the preparation of toilet soaps (a point which is open to
+doubt), it is quite inadmissible for the manufacture of germicidal and
+disinfectant soaps, the bactericidal efficiency of which is much
+restricted by the presence of free fat.
+
+Many of the medicaments added to soaps require special methods of
+incorporation therein, as they otherwise react with the soap and
+decompose it, forming comparatively inert compounds. This applies
+particularly to salts of mercury, such as _corrosive sublimate_ or
+mercuric chloride, and _biniodide of mercury_, both of which have very
+considerable germicidal power, and are consequently frequently added to
+soaps. If simply mixed with the soap in the mill, reaction very quickly
+takes place between the mercury salt and the soap, with formation of the
+insoluble mercury compounds of the fatty acids, a change which can be
+readily seen to occur in such a soap by the rapid development on
+keeping, of a dull slaty-green appearance. Numerous processes have been
+suggested, and in some cases patented, to overcome this difficulty. In
+the case of corrosive sublimate, Geissler suggested that the soap to
+which this reagent is to be added should contain an excess of fatty
+acids, and would thereby be rendered stable. This salt has also been
+incorporated with milled soap in a dry state in conjunction with
+ammonio-mercuric chloride, [beta]-naphthol, methyl salicylate, and
+eucalyptol. It is claimed that these bodies are present in an unchanged
+condition, and become active when the soap is added to water as in
+washing. Ehrhardt (Eng. Pat. 2,407, 1898) patented a method of making
+antiseptic mercury soap by using mercury albuminate--a combination of
+mercuric chloride and casein, which is soluble in alkali, and added to
+the soap in an alkaline solution.
+
+With biniodide of mercury the interaction can be readily obviated by
+adding to the biniodide of mercury an equal weight of potassium iodide.
+This process, devised and patented by J. Thomson in 1886, has been
+worked since that time with extremely satisfactory results. Strengths of
+1/2, 1, and 3 per cent. biniodide are sold, but owing to the readiness
+with which it is absorbed by the skin a soap containing more than 1/2
+per cent. should only be used under medical advice.
+
+A similar combination of _bromide of mercury_ with potassium, sodium, or
+ammonium bromide has recently been patented by Cooke for admixture with
+liquid, hard, or soft soaps.
+
+_Zinc and other Metallic Salts._--At various times salts of metals other
+than mercury have been added to soap, but, owing to their insolubility
+in water, their efficiency as medicaments is very trifling or nil.
+Compounds have been formed of metallic oxides and other salts with oleic
+said, and mixtures made with vaseline and lanoline, and incorporated
+with soap, but they have not met with much success.
+
+Another chemical commonly added to soap is _Borax_. In view of its
+alkaline reaction to litmus, turning red litmus blue, this salt is no
+doubt generally regarded as alkaline, and, as such, without action on
+soap. On the contrary, however, it is an acid salt containing an excess
+of boric acid over the soda present, hence when it is added to soap,
+fatty acids are necessarily liberated, causing the soap to quickly
+become rancid. As a remedy for this it has been proposed to add
+sufficient alkali to convert the borax into neutral mono-borate of soda
+which is then added to the soap. This process is patented and the name
+"Kastilis" has been given to the neutral salt. The incorporation of
+borax with the addition of gum tragasol forms the subject of two patents
+(Eng. Pats. 4,415, 1904; and 25,425, 1905); increased detergent and
+lasting properties are claimed for the soap. Another patented process
+(Eng. Pat. 17,218, 1904) consists of coating the borax with a protective
+layer of fat or wax before adding to the soap with the idea that
+reaction will not take place until required. _Boric acid_ possesses the
+defects of borax in a greater degree, and would, of course, simply form
+sodium borate with liberation of fatty acids, so should never be added
+to a neutral soap.
+
+_Salicylic Acid_ is often recommended for certain skin diseases, and
+here again the addition of the acid to soap under ordinary conditions
+results in the formation of sodium salicylate and free fatty acids.
+
+To overcome this a process has recently been patented for rubbing the
+acid up with vaseline before addition to soap, but the simplest way
+appears to be to add the soda salt of the acid to soap.
+
+Amongst the more common milled medicated toilet soaps may be mentioned,
+in addition to the above:--
+
+_Birch Tar Soap_, containing 5 or 10 per cent. birch tar, which has a
+characteristic pungent odour and is recommended as a remedy for eczema
+and psoriasis.
+
+_Carbolic Soap._--A toilet soap should not contain more than 3 per cent.
+of pure phenol, for with larger quantities irritation is likely to be
+experienced by susceptible skins.
+
+_Coal Tar._--These soaps contain, in addition to carbolic acid and its
+homologues, naphthalene and other hydrocarbons derived from coal,
+naphthol, bases, etc. Various blends of different fractions of coal tar
+are used, but the most valuable constituents from a disinfectant point
+of view are undoubtedly the phenols, or tar acids, though in this case
+as with carbolic and cresylic soaps, the amount of phenols should not
+exceed 3 per cent. in a toilet soap. An excess of naphthalene should
+also be avoided, since, on account of its strong odour, soaps containing
+much of it are unpopular. The odour of coal tar is considerably modified
+by and blends well with a perfume containing oils of cassia, lavender,
+spike, and red thyme.
+
+_Formaldehyde._--This substance is one of the most powerful
+disinfectants known, and it may be readily introduced into soap without
+undergoing any decomposition, by milling in 2-3 per cent. of formalin, a
+40 per cent. aqueous solution of formaldehyde, which is a gas. White
+soaps containing this chemical retain their whiteness almost
+indefinitely.
+
+New combinations of formaldehyde with other bodies are constantly being
+brought forward as disinfectants. Among others the compound resulting
+from heating lanoline with formaldehyde has been patented (Eng. Pat.
+7,169, 1898), and is recommended as an antiseptic medicament for
+incorporation with soap.
+
+_Glycerine._--Nearly all soaps contain a small quantity of this body
+which is not separated in the lyes. In some cases, however, a much
+larger quantity is desired, up to some 6 or 8 per cent. To mill this in
+requires great care, otherwise the soap tends to blister during
+compression. The best way is to dry the soap somewhat further than
+usual, till it contains say only 9 or 10 per cent. moisture and then
+mill in the glycerine.
+
+_Ichthyol_ or _Ammonium-Ichthyol-Sulphonate_ is prepared by treating
+with sulphuric acid, and afterwards with ammonia, the hydrocarbon oil
+containing sulphur obtained by the dry distillation of the fossil
+remains of fish and sea-animals, which form a bituminous mineral deposit
+in Germany. This product has been admixed with soap for many years, the
+quantity generally used being about 5 per cent.; the resultant soap is
+possessed of a characteristic empyreumatic smell, very dark colour, and
+is recommended for rosacea and various skin diseases, and also as an
+anti-rheumatic. Ichthyol has somewhat changed its character during
+recent years, being now almost completely soluble in water, and stronger
+in odour than formerly.
+
+_Iodine._--A soap containing iodine is sometimes used in scrofulous skin
+diseases. It should contain some 3 per cent. iodine, while potassium
+iodide should also be added to render the iodine soluble.
+
+_Lysol._--This name is applied to a soap solution of cresol, "Lysol
+Soap" being simply another form of coal-tar soap. The usual strength is
+10 per cent. lysol, and constitutes a patented article (Fr. Pat.
+359,061, 1905).
+
+_Naphthol._--[beta]-Naphthol, also a coal-tar derivative, is a good
+germicide, and, incorporated in soap to the extent of 3 per cent.
+together with sulphur, is recommended for scabies, eczema and many other
+cutaneous affections.
+
+_Sulphur._--Since sulphur is insoluble in water, its action when used in
+conjunction with soap can be but very slow and slight. Sulphur soaps
+are, however, very commonly sold, and 10 per cent. is the strength
+usually advocated, though many so-called sulphur soaps actually contain
+very little sulphur. They are said to be efficacious for acne and
+rosacea.
+
+Sulphur soaps, when dissolved in water, gradually generate sulphuretted
+hydrogen, which, although characteristic, makes their use disagreeable
+and lessens their popular estimation.
+
+_Terebene._--The addition of this substance to soap, though imparting a
+very refreshing and pleasant odour, does not materially increase the
+disinfectant value of the soap. A suitable strength is 5 per cent.
+
+_Thymol._--This furnishes a not unpleasant, and very useful antiseptic
+soap, recommended especially for the cleansing of ulcerated wounds and
+restoring the skin to a healthy state. The normal strength is 3 per
+cent. It is preferable to replace part of the thymol with red thyme oil,
+the thymene of which imparts a sweeter odour to the soap than if
+produced with thymol alone. A suitable blend is 2-1/2 per cent. of
+thymol crystals and 1-1/2 per cent. of a good red thyme oil.
+
+Of the vast number of less known proposed additions to toilet soaps,
+mention may be made in passing of:--
+
+_Fluorides._--These have been somewhat popular during recent years for
+the disinfection of breweries, etc., and also used to some extent as
+food preservatives. Of course only neutral fluorides are available for
+use in soap, acid fluorides and soap being obviously incompatible. In
+the authors' experience, however, sodium fluoride appears to have little
+value as a germicide when added to soap, such soaps being found to
+rapidly become rancid and change colour.
+
+_Albumen._--The use of albumen--egg, milk, and vegetable--in soap has
+been persistently advocated in this country during the past few years.
+The claims attributed to albumen are, that it neutralises free alkali,
+causes the soap to yield a more copious lather, and helps to bind it
+more closely, and a further inducement held out is that it allows more
+water to be left in the soap without affecting its firmness. Experiments
+made by the authors did not appear to justify any enthusiasm on the
+subject, and the use of albumen for soap-making in this country appears
+to be very slight, however popular it may be on the Continent. Numerous
+other substances have been proposed for addition to soaps, including
+yeast, tar from peat (sphagnol), Swedish wood tar, permanganate of
+potash, perborates and percarbonates of soda and ammonia, chlorine
+compounds, but none of these has at present come much into favour, and
+some had only ephemeral existence. Of the many drugs that it has been
+suggested to admix in soap for use in allaying an irritable condition of
+the skin, the majority are obviously better applied in the form of
+ointments, and we need not consider them further.
+
+_Ether Soap._--Another form of medicated soap made by a few firms is a
+liquid ether soap containing mercuric iodide, and intended for surgeons'
+use. This, as a rule, consists of a soap made from olive oil and potash,
+dissolved in alcohol and mixed with ether, the mercuric iodide being
+dissolved in a few drops of water containing an equal weight of
+potassium iodide, and this solution added to the alcohol-ether soap.
+
+_Floating Soaps._--Attempts have been made to produce tablets of soap
+that will float upon the surface of water, by inserting cork, or floats,
+or a metallic plate in such a manner that there is an air space between
+the metal and the soap. The more usual method is to incorporate into
+hot soap sufficient air, by means of a specially designed self-contained
+jacketed crutcher, in which two shafts carrying small blades or paddles
+rotate in opposite directions, to reduce the density of the soap below
+that of water and so enable the compressed tablet to float. The
+difference in weight of a tablet of the same size before and after
+aerating amounts to 10 per cent.
+
+Ordinary milling soap is used as a basis for this soap; the settled soap
+direct from the copper at 170° F. (77° C.) is carefully neutralised with
+bicarbonate of sodium, oleic or stearic acids, or boro-glyceride,
+perfumed and aerated.
+
+Floating soap, which is usually white (some are of a cream tint), cannot
+be recommended as economical, whilst its deficiency in lathering
+properties, owing to occluded air, is a serious drawback to its
+popularity as a toilet detergent.
+
+_Shaving Soaps._--The first essential of a shaving soap, apart from its
+freedom from caustic alkali or any substance exerting an irritating
+effect upon the skin, is the quick production of a profuse creamy lather
+which is lasting. Gum tragacanth is used in some cases to give lasting
+power or durability, but is not necessary, as this property is readily
+attained by the use of a suitable proportion of potash soap. The best
+shaving soaps are mixtures of various proportions of neutral soda and
+potash soaps, produced by the combination of ordinary milling base with
+a white potash soap, either melted or milled together. Glycerine is
+sometimes added, and is more satisfactorily milled in.
+
+Every precaution should be taken to ensure thorough saponification of
+the soaps intended for blending in shaving soap, otherwise there will be
+a tendency to become discoloured and develop rancidity with age. Shaving
+soaps are delicately perfumed, and are placed on the market either in
+the form of sticks which are cut from the bar of soap as it leaves the
+compressor, or stamped in flat cakes.
+
+Shaving creams and pastes are of the same nature as shaving soaps, but
+usually contain a larger proportion of superfatting material and
+considerably more water.
+
+
+TEXTILE SOAPS.
+
+In the woollen, cloth, and silk textile industries, the use of soap for
+detergent and emulsifying purposes is necessary in several of the
+processes, and the following is a brief description of the kinds of soap
+successfully employed in the various stages.
+
+1. _Woollen Industry._--The scouring of wool is the most important
+operation--it is the first treatment raw wool is subjected to, and if it
+is not performed in an efficient manner, gives rise to serious
+subsequent troubles to manufacturer, dyer, and finisher.
+
+The object of scouring wool is to remove the wool-fat and wool
+perspiration (exuded from the skin of sheep), consisting of cholesterol
+and isocholesterol, and potassium salts of fatty acids, together with
+other salts, such as sulphates, chlorides, and phosphates. This is
+effected by washing in a warm dilute soap solution, containing in the
+case of low quality wool, a little carbonate of soda; the fatty matter
+is thereby emulsified and easily removed.
+
+Soap, to be suitable for the purpose, must be free from uncombined
+caustic alkali, unsaponified fat, silicates, and rosin.
+
+Wool can be dissolved in a moderately dilute solution of caustic soda,
+and the presence of this latter in soap, even in small quantities, is
+therefore liable to injure the fibres and make the resultant fabric
+possess a harsh "feel," and be devoid of lustre.
+
+Unsaponified fat denotes badly made soap--besides reducing the
+emulsifying power of the liberated alkali, this fat may be absorbed by
+the fibres and not only induce rancidity but also cause trouble in
+dyeing.
+
+Soaps containing silicates may have a deleterious action upon the
+fibres, causing them to become damaged and broken.
+
+By general consent soaps containing rosin are unsuitable for use by
+woollen manufacturers, as they produce sticky insoluble lime and
+magnesia compounds which are deposited upon the fibres, and give rise to
+unevenness in the dyeing.
+
+A neutral olive-oil soft soap is undoubtedly the best for the purpose of
+wool scouring, as, owing to its ready solubility in water, it quickly
+penetrates the fibres, is easily washed out, and produces a good "feel"
+so essential in the best goods, and tends to preserve the lustre and
+pliability of the fibre.
+
+The high price of olive-oil soap, however, renders its use prohibitive
+for lower class goods, and in such cases no better soap can be suggested
+than the old-fashioned curd mottled or curd soaps (boiled very dry), as
+free as possible from uncombined caustic alkali. The raw wool, after
+this cleansing operation, is oiled with olive oil or oleine, prior to
+spinning; after spinning and weaving, the fabric, in the form of yarn or
+cloth, has to be scoured to free it from oil. The soap in most general
+use for scouring woollen fabrics is neutral oleine-soda soap. Some
+manufacturers prefer a cheap curd soap, such as is generally termed
+"second curd," and in cases where lower grades of wools are handled, the
+user is often willing to have soap containing rosin (owing to its
+cheapness) and considers a little alkalinity desirable to assist in
+removing the oil.
+
+Another operation in which soap is used, is that of milling or fulling,
+whereby the fabric is made to shrink and thus becomes more compact and
+closer in texture. The fabric is thoroughly cleansed, for which purpose
+the soap should be neutral and free from rosin and silicates, otherwise
+a harsh feeling or stickiness will be produced. Curd soaps or
+finely-fitted soaps made from tallow or bleached palm oil, with or
+without the addition of cocoa-nut oil, give the best results. All traces
+of soap must be carefully removed if the fabric is to be dyed.
+
+The woollen dyer uses soap on the dyed pieces to assist the milling,
+and finds that a good soap, made from either olive oil, bleached palm
+oil, or tallow, is preferable, and, although it is generally specified
+to be free from alkali, a little alkalinity is not of consequence, for
+the woollen goods are, as a rule, acid after dyeing, and this alkalinity
+would be instantly neutralised.
+
+2. _Cotton Industry._--Cotton fibres are unacted upon by caustic alkali,
+so that the soap used in cleaning and preparing cotton goods for dyeing
+need not be neutral, in fact alkalinity is a distinct advantage in order
+to assist the cleansing.
+
+Any curd soap made from tallow, with or without the addition of a small
+quantity of cocoa-nut oil, may be advantageously used for removing the
+natural oil.
+
+In cotton dyeing, additions of soap are often made to the bath, and in
+such cases the soap must be of good odour and neutral, lest the colours
+should be acted upon and tints altered. Soaps made from olive oil and
+palm oil are recommended. The same kind of soap is sometimes used for
+soaping the dyed cotton goods.
+
+The calico-printer uses considerable quantities of soap for cleansing
+the printed-cloths. The soap not only cleanses by helping to remove the
+gummy and starchy constituents of the adhering printing paste, but also
+plays an important part in fixing and brightening the colours. Soaps
+intended for this class of work must be quite neutral (to obviate any
+possible alteration in colour by the action of free alkali), free from
+objectionable odour and rosin, and readily soluble in water. These
+qualities are possessed by olive-oil soaps, either soft or hard. A
+neutral olive-oil soft soap, owing to its solubility in cold water, may
+be used for fibres coloured with most delicate dyes, which would be
+fugitive in hot soap solutions, and this soap is employed for the most
+expensive work.
+
+Olive-oil curd (soda) soaps are in general use; those made from palm oil
+are also recommended, although they are not so soluble as the olive-oil
+soaps. Tallow curd soaps are sometimes used, but the difficulty with
+which they dissolve is a drawback, and renders them somewhat unsuitable.
+
+3. _Silk Industry._--Silk is secured to remove the sericin or silk-glue
+and adhering matter from the raw silk, producing thereby lustre on the
+softened fibre and thus preparing it for the dyer.
+
+The very best soap for the purpose is an olive-oil soft soap; olive-oil
+and oleine hard soaps may also be used. The soap is often used in
+conjunction with carbonate of soda to assist the removal of the sericin,
+but, whilst carbonates are permissible, it is necessary to avoid an
+excess of caustic soda.
+
+Tallow soaps are so slowly soluble that they are not applicable to the
+scouring of silk.
+
+The dyer of silk requires soap, which is neutral and of a pleasant
+odour. The preference is given to neutral olive-oil soft soap, but hard
+soaps (made from olive oil, oleine, or palm oil) are used chiefly on
+account of cheapness. It is essential, however, that the soap should be
+free from rosin on account of its frequent use and consequent
+decomposition in the acid dye bath, when any liberated rosin acids would
+cling to the silk fibres and produce disagreeable results.
+
+_Patent Textile Soaps._--Stockhausen (Eng. Pat. 24,868, 1897) makes
+special claim for a soap, termed Monopole Soap, to be used in place of
+Turkey-red oils in the dyeing and printing of cotton goods and finishing
+of textile fabrics. The soap is prepared by heating the sulphonated oil
+(obtained on treatment of castor oil with sulphuric acid) with alkali,
+and it is stated that the product is not precipitated when used in the
+dye-bath as is ordinary soap, nor is it deposited upon the fibres.
+
+Another patent (Eng. Pat. 16,382, 1897), has for its object the
+obviating of the injurious effects upon wool, of alkali liberated from a
+solution of soap. It is proposed to accomplish this by sulphonating part
+of the fat used in making the soap.
+
+_Miscellaneous Soaps._--Under this heading may be classed soaps intended
+for special purposes and consisting essentially of ordinary boiled soap
+to which additions of various substances have been made.
+
+With additions of naphtha, fractions of petroleum, and turpentine, the
+detergent power of the soap is increased by the action of these
+substances in removing grease.
+
+Amongst the many other additions may be mentioned: ox-gall or
+derivatives therefrom (for carpet-cleaning soap), alkali sulphides (for
+use of lead-workers), aniline colours (for home-dyeing soaps), pumice
+and tripoli (motorists' soaps), pine-needle oil, in some instances
+together with lanoline (for massage soaps), pearl-ash (for soap intended
+to remove oil and tar stains), magnesia, rouge, ammonium carbonate,
+chalk (silversmiths' soap), powdered orris, precipitated chalk,
+magnesium carbonate (tooth soaps).
+
+Soap powders or dry soaps are powdered mixtures of soap, soda ash, or
+soda crystals, and other chemicals, whilst polishing soaps often contain
+from 85 to 90 per cent. siliceous matter, and can scarcely be termed
+soap.
+
+
+
+
+CHAPTER VIII.
+
+SOAP PERFUMES.
+
+     _Essential Oils--Source and Preparation--Properties--Artificial
+     and Synthetic Perfumes._
+
+
+The number of raw materials, both natural and artificial, at the
+disposal of the perfumer, has increased so enormously during recent
+years that the scenting of soaps has now become an art requiring very
+considerable skill, and a thorough knowledge of the products to be
+handled. Not only does the all-important question of odour come into
+consideration, but the action of the perfumes on the soap, and on each
+other, has also to be taken into account. Thus, many essential oils and
+synthetic perfumes cause the soap to darken rapidly on keeping, _e.g._,
+clove oil, cassia oil, heliotropin, vanillin. Further, some odoriferous
+substances, from their chemical nature, are incompatible with soap, and
+soon decompose any soap to which they are added, while in a few cases,
+the blending of two unsuitable perfumes results, by mutual reaction, in
+the effect of each being lost. In the case of oils like bergamot oil,
+the odour value of which depends chiefly on their ester content, it is
+very important that these should not be added to soaps containing much
+free alkali, as these esters are readily decomposed thereby. Some
+perfumes possess the property of helping the soap to retain other and
+more delicate odours considerably longer than would otherwise be
+possible. Such perfumes are known as "fixing agents" or "fixateurs," and
+among the most important of these may be mentioned musk, both natural
+and artificial, civet, the oils of Peru balsam, sandalwood, and
+patchouli, and benzyl benzoate.
+
+The natural perfumes employed for addition to soaps are almost entirely
+of vegetable origin, and consist of essential oils, balsams, and resins,
+animal perfumes such as musk, civet, and ambergris being reserved
+principally for the preparation of "extraits".
+
+As would be expected with products of such diverse character, the
+methods employed for the preparation of essential oils vary
+considerably. Broadly speaking, however, the processes may be divided
+into three classes--(1) _expression_, used for orange, lemon, and lime
+oils; (2) _distillation_, employed for otto of rose, geranium,
+sandalwood, and many other oils; and (3) _extraction_, including
+_enfleurage_, by which the volatile oil from the flowers is either first
+absorbed by a neutral fat such as lard, and then extracted therefrom by
+maceration in alcohol, or directly extracted from the flowers by means
+of a volatile solvent such as benzene, petroleum ether, or chloroform.
+The last process undoubtedly furnishes products most nearly resembling
+the natural floral odours, and is the only one which does not destroy
+the delicate fragrance of the violet and jasmine. The yield, however, is
+extremely small, and concrete perfumes prepared in this way are
+therefore somewhat costly.
+
+The essential oils used are derived from upwards of twenty different
+botanical families, and are obtained from all parts of the world. Thus,
+from Africa we have geranium and clove oils; from America, bay, bois de
+rose, Canadian snake root, cedarwood, linaloe, peppermint, petitgrain,
+and sassafras; from Asia, camphor, cassia, cinnamon, patchouli,
+sandalwood, star anise, ylang-ylang, and the grass oils, _viz._,
+citronella, lemongrass, palmarosa, and vetivert; from Australia,
+eucalyptus; while in Europe there are the citrus oils, bergamot, lemon,
+and orange, produced by Sicily, aspic, lavender, neroli, petitgrain, and
+rosemary by France, caraway and clove by Holland, anise by Russia, and
+otto of rose by Bulgaria.
+
+Attempts have been made to classify essential oils either on a botanical
+basis or according to their chemical composition, but neither method is
+very satisfactory, and, in describing the chief constituents and
+properties of the more important oils, we have preferred therefore to
+arrange them alphabetically, as being simpler for reference.
+
+It is a matter of some difficulty to judge the purity of essential oils,
+not only because of their complex nature, but owing to the very great
+effect upon their properties produced by growing the plants in different
+soils and under varying climatic conditions, and still more to the
+highly scientific methods of adulteration adopted by unscrupulous
+vendors. The following figures will be found, however, to include all
+normal oils.
+
+_Anise Stell_, or _Star Anise_, from the fruit of Illicium verum,
+obtained from China. Specific gravity at 15° C., 0.980-0.990; optical
+rotation, faintly dextro- or lævo-rotatory, +0° 30' to -2°; refractive
+index at 20° C., 1.553-1.555; solidifying point, 14°-17° C.; solubility
+in 90 per cent. alcohol, 1 in 3 or 4.
+
+The chief constituents of the oil are anethol, methyl chavicol,
+d-pinene, l-phellandrene, and in older oils, the oxidation products of
+anethol, _viz._ anisic aldehyde and anisic acid. Since anethol is the
+most valuable constituent, and the solidifying point of the oil is
+roughly proportional to its anethol content, oils with a higher
+solidifying point are the best.
+
+_Aspic oil_, from the flowers of Lavandula spica, obtained from France
+and Spain, and extensively employed in perfuming household and cheap
+toilet soaps; also frequently found as an adulterant in lavender oil.
+Specific gravity at 15° C., 0.904-0.913; optical rotation, French,
+dextro-rotatory up to +4°, rarely up to +7°, Spanish, frequently
+slightly lævo-rotatory to -2°, or dextro-rotatory up to +7°; esters,
+calculated as linalyl acetate, 2 to 6 per cent.; most oils are soluble
+in 65 per cent. alcohol 1 in 4, in no case should more than 2.5 volumes
+of 70 per cent. alcohol be required for solution.
+
+The chief constituents of the oil are: linalol, cineol, borneol,
+terpineol, geraniol, pinene, camphene and camphor.
+
+_Bay oil_, distilled from the leaves of Pimenta acris, and obtained from
+St. Thomas and other West Indian Islands. It is used to some extent as a
+perfume for shaving soaps, but chiefly in the Bay Rhum toilet
+preparation. Specific gravity at 15° C., 0.965-0.980; optical rotation,
+slightly lævo-rotatory up to -3°; phenols, estimated by absorption with
+5 per cent. caustic potash solution, from 45 to 60 per cent.; the oil is
+generally insoluble in 90 per cent. alcohol, though when freshly
+distilled it dissolves in its own volume of alcohol of this strength.
+
+The oil contains eugenol, myrcene, chavicol, methyl eugenol, methyl
+chavicol, phellandrene, and citral.
+
+_Bergamot oil_, obtained by expression from the fresh peel of the fruit
+of Citrus Bergamia, and used very largely for the perfuming of toilet
+soaps. Specific gravity at 15° C., 0.880-0.886; optical rotation, +10°
+to +20°; esters, calculated as linalyl acetate, 35-40 per cent., and
+occasionally as high as 42-43 per cent.; frequently soluble in 1.5 parts
+of 80 per cent. alcohol, or failing that, should dissolve in one volume
+of 82.5 or 85 per cent. alcohol. When evaporated on the water-bath the
+oil should not leave more than 5-6 per cent. residue.
+
+Among the constituents of this oil are: linalyl acetate, limonene,
+dipentene, linalol, and bergaptene.
+
+_Bitter Almond Oil._--The volatile oil obtained from the fruit of
+_Amygdalus communis_. Specific gravity at 15° C., 1.045-1.06; optically
+inactive; refractive index at 20° C., 1.544-1.545; boiling point,
+176-177° C.; soluble in 1 or 1.5 volumes of 70 per cent. alcohol.
+
+The oil consists almost entirely of benzaldehyde which may be estimated
+by absorption with a hot saturated solution of sodium bisulphite. The
+chief impurity is prussic acid, which is not always completely removed.
+This may be readily detected by adding to a small quantity of the oil
+two or three drops of caustic soda solution, and a few drops of ferrous
+sulphate solution containing ferric salt. After thoroughly shaking,
+acidulate with dilute hydrochloric acid, when a blue coloration will be
+produced if prussic acid is present.
+
+The natural oil may frequently be differentiated from artificial
+benzaldehyde by the presence of chlorine in the latter. As there is now
+on the market, however, artificial oil free from chlorine, it is no
+longer possible, by chemical means, to distinguish with certainty
+between the natural and the artificial product. To test for chlorine in
+a sample, a small coil of filter paper, loosely rolled, is saturated
+with the oil, and burnt in a small porcelain dish, covered with an
+inverted beaker, the inside of which is moistened with distilled water.
+When the paper is burnt, the beaker is rinsed with water, filtered, and
+the filtrate tested for chloride with silver nitrate solution.
+
+_Canada snake root oil_, from the root of Asarum canadense. Specific
+gravity at 15° C., 0.940-0.962; optical rotation, slightly lævo-rotatory
+up to -4°; refractive index at 20° C., 1.485-1.490; saponification
+number, 100-115; soluble in 3 or 4 volumes of 70 per cent. alcohol.
+
+The principal constituents of the oil are a terpene, asarol alcohol,
+another alcohol, and methyl eugenol. The oil is too expensive to be used
+in other than high-class toilet soaps.
+
+_Cananga_ or _Kananga oil_, the earlier distillate from the flowers of
+Cananga odorata, obtained chiefly from the Philippine Islands. Specific
+gravity at 15° C., 0.910-0.940; optical rotation, -17° to -30°;
+refractive index at 20° C., 1.4994-1.5024; esters, calculated as linalyl
+benzoate, 8-15 per cent.; soluble in 1.5 to 2 volumes of 95 per cent.
+alcohol, but becoming turbid on further addition.
+
+The oil is qualitatively similar in composition to Ylang-Ylang oil, and
+contains linalyl benzoate and acetate, esters of geraniol, cadinene, and
+methyl ester of p-cresol.
+
+_Caraway oil_, distilled from the seeds of Carum carui. Specific gravity
+at 15° C., 0.907-0.915; optical rotation, +77° to +79°; refractive index
+at 20° C., 1.485-1.486; soluble in 3 to 8 volumes of 80 per cent.
+alcohol. The oil should contain 50-60 per cent. of carvone, which is
+estimated by absorption with a saturated solution of neutral sodium
+sulphite. The remainder of the oil consists chiefly of limonene.
+
+_Cassia oil_, distilled from the leaves of Cinnamomum cassia, and
+shipped to this country from China in lead receptacles. Specific gravity
+at 15° C., 1.060-1.068; optical rotation, slightly dextro-rotatory up to
++3° 30'; refractive index at 20° C., 1.6014-1.6048; soluble in 3 volumes
+of 70 per cent. alcohol as a general rule, but occasionally requires 1
+to 2 volumes of 80 per cent. alcohol.
+
+The value of the oil depends upon its aldehyde content, the chief
+constituent being cinnamic aldehyde. This is determined by absorption
+with a hot saturated solution of sodium bisulphite. Three grades are
+usually offered, the best containing 80-85 per cent. aldehydes, the
+second quality, 75-80 per cent., and the lowest grade, 70-75 per cent.
+
+Other constituents of the oil are cinnamyl acetate and cinnamic acid.
+This oil gives the characteristic odour to Brown Windsor soap, and is
+useful for sweetening coal-tar medicated soaps.
+
+_Cedarwood oil_, distilled from the wood of Juniperus virginiana.
+Specific gravity at 15° C., 0.938-0.960; optical rotation, -35° to -45°;
+refractive index at 20° C., 1.5013-1.5030. The principal constituents
+are cedrene and cedrol.
+
+_Cinnamon oil_, distilled from the bark of Cinnamomum zeylanicum.
+Specific gravity at 15° C., 1.00-1.035; optical rotation, lævo-rotatory
+up to -2°; usually soluble in 2 to 3 volumes of 70 per cent. alcohol,
+but sometimes requires 1 volume of 80 per cent. alcohol for solution;
+aldehydes, by absorption with sodium bisulphite solution, 55-75 per
+cent.; and phenols, as measured by absorption with 5 per cent. potash,
+not exceeding 12 per cent.
+
+The value of this oil is not determined entirely by its aldehyde content
+as is the case with cassia oil, and any oil containing more than 75 per
+cent. aldehydes must be regarded with suspicion, being probably admixed
+with either cassia oil or artificial cinnamic aldehyde. The addition of
+cinnamon leaf oil which has a specific gravity at 15° C. of 1.044-1.065
+is detected by causing a material rise in the proportion of phenols.
+Besides cinnamic aldehyde the oil contains eugenol and phellandrene.
+
+_Citronella Oil._--This oil is distilled from two distinct Andropogon
+grasses, the Lana Batu and the Maha pangiri, the former being the source
+of the bulk of Ceylon oil, and the latter being cultivated in the
+Straits Settlements and Java. The oils from these three localities show
+well-defined chemical differences.
+
+_Ceylon Citronella oil_ has the specific gravity at 15° C., 0.900-0.920;
+optical rotation, lævo-rotatory up to -12°; refractive index at 20° C.,
+1.480-1.484; soluble in 1 volume of 80 per cent. alcohol; total
+acetylisable constituents, calculated as geraniol, 54-70 per cent.
+
+_Singapore Citronella Oil._--Specific gravity at 15° C., 0.890-0.899;
+optical rotation, usually slightly lævo-rotatory up to -3°; refractive
+index at 20° C., 1.467-1.471; soluble in 1 to 1.5 volumes of 80 per
+cent. alcohol; total acetylisable constituents, calculated as geraniol,
+80-90 per cent.
+
+_Java Citronella Oil._--Specific gravity at 15° C., 0.890-0.901; optical
+rotation, -1° to -6°; total acetylisable constituents, calculated as
+geraniol, 75-90 per cent.; soluble in 1-2 volumes of 80 per cent.
+alcohol.
+
+The chief constituents of the oil are geraniol, citronellal, linalol,
+borneol, methyl eugenol, camphene, limonene, and dipentene. It is very
+largely used for perfuming cheap soaps, and also serves as a source for
+the production of geraniol.
+
+_Bois de Rose Femelle oil_, or _Cayenne linaloe oil_, distilled from
+wood of trees of the Burseraceæ species. Specific gravity at 15° C.,
+0.874-0.880; optical rotation, -11° 30' to -16°; refractive index at 20°
+C., 1.4608-1.4630; soluble in 1.5 to 2 volumes of 70 per cent. alcohol.
+
+The oil consists almost entirely of linalol, with traces of saponifiable
+bodies, but appears to be free from methyl heptenone, found by Barbier
+and Bouveault in Mexican linaloe oil. This oil is distinctly finer in
+odour than the Mexican product.
+
+_Clove oil_, distilled from the unripe blossoms of Eugenia
+caryophyllata, the chief source of which is East Africa (Zanzibar and
+Pemba). Specific gravity at 15° C., 1.045-1.061; optical rotation,
+slightly lævo-rotatory up to -1° 30'; phenols, estimated by absorption
+with 5 per cent. potash solution, 86-92 per cent.; refractive index at
+20° C., 1.5300-1.5360; soluble in 1 to 2 volumes of 70 per cent.
+alcohol.
+
+The principal constituent of the oil is eugenol, together with
+caryophyllene and acet-eugenol. While within certain limits the value of
+this oil is determined by its eugenol content, oils containing more than
+93 per cent. phenols are usually less satisfactory in odour, the high
+proportion of phenols being obtained at the expense of the decomposition
+of some of the sesquiterpene. Oils with less than 88 per cent. phenols
+will be found somewhat weak in odour. This oil is extensively used in
+the cheaper toilet soaps and is an important constituent of carnation
+soaps. As already mentioned, however, it causes the soap to darken in
+colour somewhat rapidly, and must not therefore be used in any quantity,
+except in coloured soaps.
+
+_Concrete orris oil_, a waxy substance obtained by steam distillation of
+Florentine orris root.
+
+Melting point, 35-45° C., usually 40-45° C.; free acidity, calculated as
+myristic acid, 50-80 per cent.; ester, calculated as combined myristic
+acid, 4-10 per cent.
+
+The greater part of the product consists of the inodorous myristic acid,
+the chief odour-bearing constituent being irone. The high price of the
+oil renders its use only possible in the very best quality soaps.
+
+_Eucalyptus Oil._--Though there are some hundred or more different oils
+belonging to this class, only two are of much importance to the
+soap-maker. These are:--
+
+(i.) Eucalyptus citriodora. Specific gravity at 15° C., 0.870-0.905;
+optical rotation, slightly dextro-rotatory up to +2°; soluble in 4-5
+volumes of 70 per cent. alcohol.
+
+The oil consists almost entirely of citronellic aldehyde, and on
+absorption with saturated solution of sodium bisulphite should leave
+very little oil unabsorbed.
+
+(ii.) Eucalyptus globulus, the oil used in pharmacy, and containing
+50-65 per cent. cineol. Specific gravity at 15° C., 0.910-0.930; optical
+rotation, +1° to +10°; soluble in 2 to 3 parts of 70 per cent. alcohol;
+cineol (estimated by combination with phosphoric acid, pressing,
+decomposing with hot water, and measuring the liberated cineol), not
+less than 50 per cent. Besides cineol, the oil contains d-pinene, and
+valeric, butyric, and caproic aldehydes. It is chiefly used in medicated
+soaps.
+
+_Fennel (sweet) oil_, obtained from the fruit of Foeniculum vulgare,
+grown in Germany, Roumania, and other parts of Europe. Specific gravity
+at 15° C., 0.965-0.985; optical rotation, +6° to +25°; refractive index
+at 20° C., 1.515-1.548; usually soluble in 2-6 parts 80 per cent.
+alcohol, but occasionally requires 1 part of 90 per cent. alcohol.
+
+The chief constituents of the oil are anethol, fenchone, d-pinene, and
+dipentene.
+
+_Geranium oils_, distilled from plants of the Pelargonium species.
+There are three principal kinds of this oil on the market--the African,
+obtained from Algeria and the neighbourhood, the Bourbon, distilled
+principally in the Island of Réunion, and the Spanish. The oil is also
+distilled from plants grown in the South of France, but this oil is not
+much used by soap-makers. A specially fine article is sold by a few
+essential oil firms under the name of "Geranium-sur-Rose," which as its
+name implies, is supposed to be geranium oil distilled over roses. This
+is particularly suitable for use in high-class soaps. The following are
+the general properties of these oils. It will be seen that the limits
+for the figures overlap to a considerable extent.
+
+ _________________________________________________________________________
+|                         |           |           |           |           |
+|                         |  African. |  Bourbon. |  Spanish. |  French.  |
+|_________________________|___________|___________|___________|___________|
+|                         |           |           |           |           |
+| Specific gravity        |           |           |           |           |
+|   at 15° C.             | .890-.900 | .888-.895 | .895-.898 | .897-.900 |
+| Optical rotation.       |-6° to -10°|-9° to -18°|-8° to -11°|-8° to -11°|
+| Esters, calculated as   |   20-27   |   27-32   |   20-27   |   18-23   |
+|   geranyl tiglate       | per cent. | per cent. | per cent. | per cent. |
+| Total alcohols, as      |   68-75   |   70-80   |   65-75   |   66-75   |
+|   geraniol.             | per cent. | per cent. | per cent. | per cent. |
+| Solubility in 70 per    |           |           |           |           |
+|   cent. alcohol.        | 1 in 1.5-2| 1 in 1.5-2| 1 in 2-3  | 1 in 1.5-2|
+|_________________________|___________|___________|___________|___________|
+
+The oil contains geraniol and citronellol, both free, and combined with
+tiglic, valeric, butyric, and acetic acids; also l-menthone. The African
+and Bourbon varieties are the two most commonly used for
+soap-perfurmery, the Spanish oil being too costly for extensive use.
+
+_Ginger-grass oil_, formerly regarded as an inferior kind of palma-rosa
+but now stated to be from an entirely different source. Specific gravity
+at 15° C., 0.889-0.897; optical rotation, +15°.
+
+The oil contains a large amount of geraniol, together with di-hydrocumin
+alcohol, d-phellandrene, d-limonene, dipentene, and l-carvone.
+
+_Guaiac wood oil_, distilled from the wood of Bulnesia sarmienti.
+Specific gravity at 30° C., 0.967-0.975; optical rotation, -4° 30' to
+-7°; refractive index at 20° C., 1.506-1.507; soluble in 3 to 5 volumes
+of 70 per cent. alcohol.
+
+The principal constituent of the oil is guaiac alcohol, or gusiol. This
+oil, which has what is generally termed a "tea-rose odour," is
+occasionally used as an adulterant for otto of rose.
+
+_Lavender oil_, distilled from the flowers of Lavandula vera, grown in
+England, France, Italy and Spain. The English oil is considerably the
+most expensive, and is seldom, if ever, used in soap. The French and
+Italian oils are the most common, the Spanish oil being a comparatively
+new article, of doubtful botanical origin, and more closely resembling
+aspic oil.
+
+English Oil.--Specific gravity at 15° C., 0.883-0.900; optical rotation,
+-4° to -10°; esters, calculated as linalyl acetate, 5-10 per cent.;
+soluble in 3 volumes of 70 per cent. alcohol.
+
+French and Italian Oils.--Specific gravity at 15° C., 0.885-0.900;
+optical rotation, -2° to -9°; refractive index at 20° C., 1.459-1.464;
+esters, calculated as linalyl acetate, 20-40 per cent., occasionally
+higher; soluble in 1.5-3 volumes of 70 per cent. alcohol.
+
+There was at one time a theory that the higher the proportion of ester
+the better the oil, but this theory has now to a very large extent
+become discredited, and there is no doubt that some of the finest oils
+contain less than 30 per cent. of esters.
+
+Spanish Oil.--Specific gravity at 15° C., 0.900-0.915; optical rotation,
+-2° to +7°; esters, calculated as linalyl acetate, 2-6 per cent.;
+soluble in 1-2 volumes of 70 per cent. alcohol.
+
+The chief constituents of lavender oil are linalyl acetate, linalol,
+geraniol, and linalyl butyrate, while the English oil also contains a
+distinct amount of cineol.
+
+_Lemon oil_, prepared by expressing the peel of the nearly ripe fruit of
+Citrus limonum, and obtained almost entirely from Sicily and Southern
+Italy. Specific gravity at 15° C., 0.856-0.860; optical rotation, +58°
+to +63°; refractive index at 20° C., 1.4730-1.4750; aldehydes (citral),
+2.5 to 4 per cent.
+
+The principal constituents of the oil are limonene and citral, together
+with small quantities of pinene, phellandrene, octyl and nonyl
+aldehydes, citronellal, geraniol, geranyl acetate, and the stearopten,
+citraptene.
+
+_Lemon-grass_ (so-called _verbena_) oil, distilled from the grass
+Andropogon citratus, which is grown in India and, more recently, in the
+West Indies. The oils from these two sources differ somewhat in their
+properties, and also in value, the former being preferred on account of
+its greater solubility in alcohol.
+
+East Indian.--Specific gravity at 15° C., 0.898-0.906; optical rotation,
+-0° 30' to -6°; aldehydes, by absorption with bisulphite of soda
+solution, 65 to 78 per cent.; refractive index at 20° C., 1.485-1.487;
+soluble in 2-3 volumes of 70 per cent. alcohol.
+
+West Indian.--Specific gravity at 15° C., 0.886-0.893; optical rotation,
+faintly lævo-gyrate; refractive index at 20° C., 1.4855-1.4876; soluble
+in 0.5 volume of 90 per cent. alcohol.
+
+_Lime oil_, obtained by expression or distillation of the peel of the
+fruit of Citrus medica, and produced principally in the West Indies.
+
+Expressed Oil.--Specific gravity at 15° C., 0.870-0.885; optical
+rotation, +38° to +50°. Its most important constituent is citral.
+
+Distilled Oil.--This is entirely different in character to the expressed
+oil. Its specific gravity at 15° C. is 0.854-0.870; optical rotation,
++38° to +54°; soluble in 5-8 volumes of 90 per cent. alcohol.
+
+_Linaloe oil_, distilled from the wood of trees of the Burseraceæ
+family, and obtained from Mexico. Specific gravity at 15° C.,
+0.876-0.892; optical rotation, usually lævo-rotatory, -3° to -13°, but
+occasionally dextro-rotatory up to +5° 30'; esters, calculated as
+linalyl acetate, 1-8 per cent.; total alcohols as linalol, determined by
+acetylation, 54-66 per cent.; soluble in 1-2 volumes of 70 per cent.
+alcohol.
+
+This oil consists mainly of linalol, together with small quantities of
+methyl heptenone, geraniol, and d-terpineol.
+
+_Marjoram oil_, distilled from Origanum majoranoides, and obtained
+entirely from Cyprus. Specific gravity at 15° C., 0.966; phenols,
+chiefly carvacrol, estimated by absorption with 5 per cent. caustic
+potash solution, 80-82 per cent.; soluble in 2-3 volumes of 70 per cent.
+alcohol.
+
+This oil is used in soap occasionally in place of red thyme oil.
+
+_Neroli Bigarade oil_, distilled from the fresh blossoms of the bitter
+orange, Citrus bigaradia. Specific gravity at 15° C., 0.875-0.882;
+optical rotation, +0° 40' to +10°, and occasionally much higher;
+refractive index at 20° C., 1.468-1.470; esters, calculated as linalyl
+acetate, 10-18 per cent.; soluble in 0.75-1.75 volumes of 80 per cent.
+alcohol, becoming turbid on further addition of alcohol.
+
+The chief constituents of the oil are limonene, linalol, linalyl
+acetate, geraniol, methyl anthranilate, indol, and neroli camphor.
+
+_Orange (sweet) oil_, expressed from the peel of Citrus aurantium.
+Specific gravity at 15° C., 0.849-0.852; optical rotation, +95° to +99°;
+refractive index at 20° C., 1.4726-1.4732.
+
+The oil contains some 90 per cent. limonene, together with nonyl
+alcohol, d-linalol, d-terpineol, citral, citronellal, decyl aldehyde,
+and methyl anthranilate.
+
+_Palmarosa_, or _East Indian geranium oil_, distilled from Andropogon
+Schoenanthus, a grass widely grown in India. Specific gravity at 15°
+C., 0.888-0.895; optical rotation, +1° to -3°; refractive index at 20°
+C., 1.472-1.476; esters, calculated as linalyl acetate, 7-14 per cent.;
+total alcohols, as geraniol, 75-93 per cent.; solubility in 70 per cent.
+alcohol, 1 in 3.
+
+The oil consists chiefly of geraniol, free, and combined with acetic and
+caproic acids, and dipentene. It is largely used in cheap toilet soaps,
+particularly in rose soaps. It is also a favourite adulterant for otto
+of rose, and is used as a source of geraniol.
+
+_Patchouli oil_, distilled from the leaves of Pogostemon patchouli, a
+herb grown in India and the Straits Settlements. Specific gravity at 15°
+C., 0.965-0.990; optical rotation, -45° to -63°; refractive index at 20°
+C., 1.504-1.511; saponification number, up to 12; sometimes soluble in
+0.5 to 1 volume of 90 per cent. alcohol, becoming turbid on further
+addition. The solubility of the oil in alcohol increases with age. The
+oil consists to the extent of 97 per cent. of patchouliol and cadinene,
+which have little influence on its odour, and the bodies responsible for
+its persistent and characteristic odour have not yet been isolated.
+
+_Peppermint oil_, distilled from herbs of the Mentha family, the
+European and American from Mentha piperita, and the Japanese being
+generally supposed to be obtained from Mentha arvensis. The locality in
+which the herb is grown has a considerable influence on the resulting
+oil, as the following figures show:--
+
+English.--Specific gravity at 15° C., 0.900-0.910; optical rotation,
+-22° to -33°; total menthol, 55-66 per cent.; free menthol, 50-60 per
+cent.; soluble in 3-5 volumes of 70 per cent. alcohol.
+
+American.--Specific gravity at 15° C., 0.906-0.920; optical rotation,
+-20° to -33°; total menthol, 50-60 per cent.; free menthol, 40-50 per
+cent. The Michigan oil is soluble in 3-5 volumes of 70 per cent.
+alcohol, but the better Wayne County oil usually requires 1-2 volumes of
+80 per cent. alcohol, and occasionally 0.5 volume of 90 per cent.
+alcohol.
+
+French.--Specific gravity at 15° C., 0.917-0.925; optical rotation, -6°
+to -10°; total menthol, 45-55 per cent.; free menthol, 35-45 per cent.;
+soluble in 1 to 1.5 volumes of 80 per cent.
+
+Japanese.--Specific gravity at 25° C., 0.895-0.900; optical rotation,
+lævo-rotatory up to -43°; solidifies at 17 to 27° C.; total menthol,
+70-90 per cent., of which 65-85 per cent. is free; soluble in 3-5
+volumes of 70 per cent. alcohol.
+
+The dementholised oil is fluid at ordinary temperatures, has a specific
+gravity of 0.900-0.906 at 15° C., and contains 50-60 per cent. total
+menthol.
+
+Some twenty different constituents have been found in American
+peppermint oil, including menthol, menthone, menthyl acetate, cineol,
+amyl alcohol, pinene, l-limonene, phellandrene, dimethyl sulphide,
+menthyl isovalerianate, isovalerianic aldehyde, acetaldehyde, acetic
+acid, and isovalerianic acid.
+
+_Peru balsam oil_, the oily portion (so-called "cinnamein") obtained
+from Peru balsam. Specific gravity at 15° C., 1.100-1.107; optical
+rotation, slightly dextro-rotatory up to +2°; refractive index at 20°
+C., 1.569 to 1.576; ester, calculated as benzyl benzoate, 80-87 per
+cent.; soluble in 1 volume of 90 per cent. alcohol.
+
+The oil consists chiefly of benzyl benzoate and cinnamate, together with
+styracin, or cinnamyl cinnamate, and a small quantity of free benzoic
+and cinnamic acids.
+
+_Petitgrain oil_, obtained by distillation of the twigs and unripe fruit
+of Citrus bigaradia. There are two varieties of the oil, the French and
+the South American, the former being the more valuable. Specific gravity
+at 15° C., 0.886-0.900; optical rotation, -3° to +6°; refractive index
+at 20° C., 1.4604-1.4650; esters, calculated as linalyl acetate, 40-55
+per cent., for the best qualities usually above 50 per cent.; soluble as
+a rule in 2-3 volumes of 70 per cent. alcohol, but occasionally requires
+1-2 volumes of 80 per cent. alcohol.
+
+Among its constituents are limonene, linalyl acetate, geraniol and
+geranyl acetate.
+
+_Pimento oil_ (allspice), distilled from the fruit of Pimenta
+officinalis, which is found in the West Indies and Central America.
+Specific gravity at 15° C., 1.040-1.060; optical rotation, slightly
+lævo-rotatory up to -4°; refractive index at 20° C., 1.529-1.536;
+phenols, estimated by absorption with 5 per cent. potash solution,
+68-86 per cent.; soluble in 1-2 volumes of 70 per cent. alcohol.
+
+The oil contains eugenol, methyl eugenol, cineol, phellandrene, and
+caryophyllene.
+
+_Rose oil (otto of rose)_, distilled from the flowers of Rosa damascena,
+though occasionally the white roses (Rosa alba) are employed. The
+principal rose-growing district is in Bulgaria, but a small quantity of
+rose oil is prepared from roses grown in Anatolia, Asia Minor. An
+opinion as to the purity of otto of rose can only be arrived at after a
+very full chemical analysis, supplemented by critical examination of its
+odour by an expert. The following figures, however, will be found to
+include most oils which can be regarded as genuine. Specific gravity at
+30° C., 0.850-0.858; optical rotation at 30° C., -1° 30' to -3°;
+refractive index at 20° C., 1.4600-1.4645; saponification value, 7-11;
+solidifying point, 19-22° C.; iodine number, 187-194; stearopten
+content, 14-20 per cent.; melting point of stearopten, about 32° C.
+
+A large number of constituents have been isolated from otto of rose,
+many of which are, however, only present in very small quantities. The
+most important are geraniol, citronellol, phenyl ethyl alcohol, together
+with nerol, linalol, citral, nonylic aldehyde, eugenol, a sesquiterpene
+alcohol, and the paraffin stearopten.
+
+_Rosemary oil_, distilled from the herb Rosemarinus officinalis, and
+obtained from France, Dalmatia, and Spain. The herb is also grown in
+England, but the oil distilled therefrom is rarely met with in commerce.
+The properties of the oils vary with their source, and also with the
+parts of the plant distilled, distillation of the stalks as well as the
+leaves tending to reduce the specific gravity and borneol content, and
+increase the proportion of the lævo-rotatory constituent (lævo-pinene).
+The following figures may be taken as limits for pure oils:--
+
+French and Dalmatian.--Specific gravity at 15° C., 0.900-0.916; optical
+rotation, usually dextro-rotatory, up to +15°, but may occasionally be
+lævo-rotatory, especially if stalks have been distilled with the leaves;
+ester, calculated as bornyl acetate, 1-6 per cent.; total borneol, 12-18
+per cent.; usually soluble in 1-2 volumes of 82.5 per cent. alcohol.
+
+Spanish.--The properties of the Spanish oil are similar to the others,
+except that it is more frequently lævo-rotatory.
+
+Rosemary oil contains pinene, camphene, cineol, borneol, and camphor.
+
+_Sandalwood oil_, obtained by distillation of the wood of Santalum album
+(East Indian), Santalum cygnorum (West Australian), and Amyris
+balsamifera (West Indian). The oils obtained from these three different
+sources differ very considerably in value, the East Indian being by far
+the best.
+
+East Indian.--Specific gravity at 15° C., 0.975-0.980; optical rotation,
+-14° to -20°; refractive index at 20° C., 1.5045-1.5060; santalol,
+92-97 per cent.; usually soluble in 4-6 volumes of 70 per cent. alcohol,
+though, an old oil occasionally is insoluble in 70 per cent. alcohol.
+
+West Australian.--Specific gravity at 15° C., 0.950-0.968; optical
+rotation, +5° to +7°; alcohols, calculated as santalol, 73-75 per cent.;
+insoluble in 70 per cent. alcohol, but readily dissolves in 1-2 volumes
+of 80 per cent. alcohol.
+
+West Indian.--Specific gravity at 15° C., 0.948-0.967; optical rotation,
++13° 30' to +30°; insoluble in 70 per cent. alcohol.
+
+In addition to free santalol, the oil contains esters of santalol and
+santalal.
+
+_Sassafras oil_, distilled from the bark of Sassafras officinalis, and
+obtained chiefly from America. Specific gravity at 15° C., 1.06-1.08;
+optical rotation, +1° 50' to +4°; refractive index at 20° C.,
+1.524-1.532; soluble in, 6-10 volumes of 85 per cent. alcohol,
+frequently soluble in 10-15 volumes of 80 per cent. alcohol.
+
+The chief constituents are safrol, pinene, eugenol, camphor, and
+phellandrene. The removal of safrol, either intentionally or by
+accident, owing to cooling of the oil and consequent deposition of the
+safrol, is readily detected by the reduction of the specific gravity
+below 1.06.
+
+_Thyme oil, red and white_, distilled from the green or dried herb,
+Thymus vulgaris, both French and Spanish oils being met with. These oils
+are entirely different in character.
+
+French.--Specific gravity at 15° C., 0.91-0.933; slightly lævo-rotatory
+up to -4°, but usually too dark to observe; phenols, by absorption with
+10 per cent. aqueous caustic potash, 25-55 per cent.; refractive index
+at 20° C., 1.490-1.500; soluble in 1-1.5 volumes of 80 per cent.
+alcohol.
+
+Spanish.--Specific gravity at 15° C., 0.955-0.966; optical rotation,
+slightly lævo-gyrate; phenols, 70-80 per cent.; refractive index at 20°
+C.; 1.5088-1.5122; soluble in 2-3 volumes of 70 per cent. alcohol.
+
+In addition to the phenols, thymol or carvacrol, these oils contain
+cymene, thymene and pinene.
+
+The white thyme oil is produced by rectifying the red oil, which is
+generally effected at the expense of a considerable reduction in phenol
+content, and hence in real odour value of the oil.
+
+_Verbena Oil._--The oil usually sold under this name is really
+lemon-grass oil (which see _supra_). The true verbena oil or French
+verveine is, however, occasionally met with. This is distilled in France
+from the verbena officinalis, and has the following properties: Specific
+gravity at 15° C., 0.891-0.898; optical rotation, slightly dextro- or
+lævo-rotatory; aldehydes, 70-75 per cent.; soluble in 2 volumes of 70
+per cent. alcohol.
+
+The oil contains citral.
+
+_Vetivert oil_, distilled from the grass, Andropogon muricatus, or Cus
+Cus, and grown in the East Indies.
+
+Specific gravity at 15° C., 1.01-1.03; optical rotation, +20° to +26°;
+saponification number, 15-30; refractive index at 20° C., 1.521-1.524;
+soluble in 2 volumes of 80 per cent. alcohol.
+
+The price of this oil makes its use prohibitive except in the highest
+class soaps.
+
+_Wintergreen Oil._--There are two natural sources of this oil, the
+Gaultheria procumbens and the Betula lenta. Both oils consist almost
+entirely of methyl salicylate and are practically identical in
+properties, the chief difference being that the former has a slight
+lævo-rotation, while the latter is inactive.
+
+Specific gravity at 15° C., 1.180-1.187; optical rotation, Gaultheria
+oil, up to -1°, Betula oil, inactive; ester as methyl salicylate, at
+least 98 per cent.; refractive index at 20° C., 1.5354-1.5364; soluble
+in 2-6 volumes of 70 per cent. alcohol.
+
+Besides methyl salicylate, the oil contains triaconitane, an aldehyde or
+ketone, and an alcohol.
+
+_Ylang-ylang oil_, distilled from the flowers of Cananga odorata, the
+chief sources being the Philippine Islands and Java. Specific gravity at
+15° C., 0.924-0.950; optical rotation, -30° to -60°, and occasionally
+higher; refractive index at 20° C., 1.496-1.512; ester, calculated as
+linalyl benzoate, 27-45 per cent., occasionally up to 50 per cent.;
+usually soluble in 1/2 volume of 90 per cent. alcohol.
+
+The composition of the oil is qualitatively the same as that of Cananga
+oil, but it is considerably more expensive and therefore can only be
+used in the highest grade soaps.
+
+
+_Artificial and Synthetic Perfumes._
+
+During the past few years the constitution of essential oils has been
+studied by a considerable number of chemists, and the composition of
+many oils has been so fully determined that very good imitations can
+often be made at cheaper prices than those of the genuine oils,
+rendering it possible to produce cheap soaps having perfumes which were
+formerly only possible in the more expensive article.
+
+There is a considerable distinction, however, often lost sight of,
+between an _artificial_ and a _synthetic_ oil. An artificial oil may be
+produced by separating various constituents from certain natural oils,
+and so blending these, with or without the addition of other substances,
+as to produce a desired odour, the perfume being, at any rate in part,
+obtained from natural oils. A synthetic perfume, on the other hand, is
+entirely the product of the chemical laboratory, no natural oil or
+substance derived therefrom entering into its composition.
+
+The following are among the most important bodies of this class:--
+
+_Amyl salicylate_, the ester prepared from amyl alcohol and salicylic
+acid, sometimes known as "Orchidée" or "Trèfle". This is much used for
+the production of a clover-scented soap. It has the specific gravity at
+15° C., 1.052-1.054; optical rotation, +1° 16' to +1° 40'; refractive
+index at 20° C., 1.5056; and should contain not less than 97 per cent.
+ester, calculated as amyl salicylate.
+
+_Anisic aldehyde_, or _aubépine_, prepared by oxidation of anethol, and
+possessing a pleasant, hawthorn odour. This has the specific gravity at
+15° C., 1.126; refractive index at 20° C., 1.5693; is optically
+inactive, and dissolves readily in one volume of 70 per cent. alcohol.
+
+_Benzyl Acetate_, the ester obtained from benzyl alcohol and acetic
+acid. This has a very strong and somewhat coarse, penetrating odour,
+distinctly resembling jasmine. Its specific gravity at 15° C. is
+1.062-1.065; refractive index at 20° C., 1.5020; and it should contain
+at least 97-98 per cent. ester, calculated as benzyl acetate.
+
+_Citral_, the aldehyde occurring largely in lemon-grass and verbena
+oils, also to a less extent in lemon and orange oils, and possessing an
+intense lemon-like odour. It has a specific gravity at 15° C.,
+0.896-0.897, is optically inactive, and should be entirely absorbed by a
+hot saturated solution of sodium bisulphite.
+
+_Citronellal_, an aldehyde possessing the characteristic odour of
+citronella oil, in which it occurs to the extent of about 20 per cent.,
+and constituting considerably over 90 per cent. of eucalyptus citriodora
+oil. Its specific gravity at 15° C. is 0.862; refractive index at 20°
+C., 1.447; optical rotation, +8° to +12°; and it should be entirely
+absorbed by a hot saturated solution of sodium bisulphite.
+
+_Coumarin_, a white crystalline product found in Tonka beans, and
+prepared synthetically from salicylic acid. It has an odour resembling
+new-mown hay, and melts at 67° C.
+
+_Geraniol_, a cyclic alcohol, occurring largely in geranium, palma-rosa,
+and citronella oils. Its specific gravity at 15° C. is 0.883-0.885;
+refractive index at 20° C., 1.4762-1.4770; it is optically inactive, and
+boils at 218°-225° C.
+
+_Heliotropin_, which possesses the characteristic odour of heliotrope,
+is prepared artificially from safrol. It crystallises in small prisms
+melting at 86° C.
+
+_Hyacinth._--Most of the articles sold under this name are secret blends
+of the different makers. Styrolene has an odour very much resembling
+hyacinth, and probably forms the basis of most of these preparations,
+together with terpineol, and other artificial bodies. The properties of
+the oil vary considerably for different makes.
+
+_Ionone_, a ketone first prepared by Tiemann, and having when diluted a
+pronounced violet odour. It is prepared by treating a mixture of citral
+and acetone with barium hydrate, and distilling in vacuo. Two isomeric
+ketones, [alpha]-ionone and [beta]-ionone, are produced, the article
+of commerce being usually a mixture of both. The two ketones have the
+following properties:--
+
+Alpha-ionone.--Specific gravity at 15° C., 0.9338; refractive index at
+16.5 C., 1.50048 (Chuit); optically it is inactive.
+
+Beta-ionone.--Specific gravity at 15° C., 0.9488; refractive index at
+16.8° C., 1.52070 (Chuit); optically it is inactive also.
+
+The product is usually sold in 10 or 20 per cent. alcoholic solution
+ready for use.
+
+_Jasmine._--This is one of the few cases in which the artificial oil is
+probably superior to that obtained from the natural flowers, possibly
+due to the extreme delicacy of the odour, and its consequent slight
+decomposition during preparation from the flowers. The chemical
+composition of the floral perfume has been very exhaustively studied,
+and the artificial article now on the market may be described as a
+triumph of synthetical chemistry. Among its constituents are benzyl
+acetate, linalyl acetate, benzyl alcohol, indol, methyl anthranilate,
+and a ketone jasmone.
+
+_Linalol_, the alcohol forming the greater part of linaloe and bois de
+rose oils, and found also in lavender, neroli, petitgrain, bergamot, and
+many other oils. The article has the specific gravity at 15° C.,
+0.870-0.876; optical rotation, -12° to -14°; refractive index at 20° C.,
+1.463-1.464; and when estimated by acetylation, yields about 70 per
+cent. of alcohols.
+
+_Linalyl acetate_, or _artificial bergamot oil_, is the ester formed
+when linalol is treated with acetic anhydride. It possesses a
+bergamot-like odour, but it is doubtful whether its value is
+commensurate with its greatly increased price over that of ordinary
+bergamot oil. It has the specific gravity at 15° C., 0.912.
+
+_Musk (Artificial)._--Several forms of this are to be obtained,
+practically all of which are nitro-derivatives of aromatic hydrocarbons.
+The original patent of Baur, obtained in 1889, covered the
+tri-nitro-derivative of tertiary butyl xylene. The melting point of the
+pure article usually lies between 108° and 112° C., and the solubility
+in 95 per cent. alcohol ranges from 1 in 120 to 1 in 200, though more
+soluble forms are also made.
+
+An important adulterant, which should always be tested for, is
+acetanilide (antifebrin), which may be detected by the characteristic
+isocyanide odour produced when musk containing this substance is boiled
+with alcoholic potash, and a few drops of chloroform added. Acetanilide
+also increases the solubility in 95 per cent. alcohol.
+
+_Neroli Oil (Artificial)._--Like jasmine oil, the chemistry of neroli
+oil is now very fully known, and it is therefore possible to prepare an
+artificial product which is a very good approximation to the natural
+oil, and many such are now on the market, which, on account of their
+comparative cheapness, commend themselves to the soap-perfumer. These
+consist chiefly of linalol, geraniol, linalyl acetate, methyl
+anthranilate, and citral.
+
+_Mirbane Oil_ or _Nitrobenzene._--This is a cheap substitute for oil of
+bitter almonds, or benzaldehyde, and is a very coarse, irritating
+perfume, only suitable for use in the very cheapest soaps. It is
+prepared by the action of a mixture of nitric and sulphuric acids on
+benzene at a temperature not exceeding 40° C. Its specific gravity is
+1.205-1.206; refractive index at 20° C., 1.550; and boiling point, 206°
+C.
+
+_Niobe oil_, or _ethyl benzoate_, the ester obtained from ethyl alcohol
+and benzoic acid, and having the specific gravity at 15° C.,
+1.094-1.095; refractive index at 20° C., 1.5167; boiling point,
+196.5°-198° C.; soluble in 1.5 volumes of 70 per cent. alcohol.
+
+_Oeillet_ is a combination possessed of a sweet carnation-like odour and
+having as a basis, eugenol or isoeugenol. Its properties vary with the
+source of supply.
+
+_Rose Oil (Artificial)._--Several good and fairly cheap artificial rose
+oils are now obtainable, consisting chiefly of citronellol, geraniol,
+linalol, phenyl ethyl alcohol, and citral. In some cases stearopten or
+other wax is added, to render the oil more similar in appearance to the
+natural article, but as these are inodorous, no advantage is gained in
+this way, and there is, further, the inconvenience in cold weather of
+having to first melt the oil before use.
+
+_Safrol_, an ether which is the chief constituent of sassafras oil, and
+also found in considerable quantity in camphor oil. It is sold as an
+artificial sassafras oil, and is very much used in perfuming cheap
+toilet or household soaps. Its specific gravity at 15° C. is
+1.103-1.106; refractive index at 20° C., 1.5373; and it dissolves in
+fifteen volumes of 80 per cent. alcohol.
+
+_Santalol_, the alcohol or mixture of alcohols obtained from sandalwood
+oil. Its specific gravity at 15° C. is 0.9795; optical rotation, -18°;
+and refractive index at 20° C., 1.507.
+
+_Terebene_, a mixture of dipentene and other hydrocarbons prepared from
+turpentine oil by treatment with concentrated sulphuric acid, is used
+chiefly in medicated soaps. Its specific gravity at 15° C. is
+0.862-0.868; the oil is frequently slightly dextro- or lævo-rotatory;
+the refractive index at 20° C., 1.470-1.478.
+
+_Terpineol_, an alcohol also prepared from turpentine oil by the action
+of sulphuric acid, terpene hydrate being formed as an intermediate
+substance. It has a distinctly characteristic lilac odour, and on
+account of its cheapness is much used in soap perfumery, especially for
+a lilac or lily soap. Its specific gravity at 15° C. is 0.936-0.940;
+refractive index at 20° C., 1.4812-1.4835; and boiling point about
+210°-212° C. It is optically inactive, and readily soluble in 1.5
+volumes of 70 per cent. alcohol.
+
+_Vanillin_, a white crystalline solid, melting at 80°-82° C. and
+prepared by the oxidation of isoeugenol. It has a strong characteristic
+odour, and occurs, associated with traces of benzoic acid and
+heliotropin, in the vanilla bean. It can only be used in small quantity
+in light-coloured soaps, as it quickly tends to darken the colour of the
+soap.
+
+
+
+
+CHAPTER IX.
+
+GLYCERINE MANUFACTURE AND PURIFICATION.
+
+     _Treatment of Lyes--Evaporation to Crude
+     Glycerine--Distillation--Distilled and Dynamite
+     Glycerine--Chemically Pure Glycerine--Animal Charcoal for
+     Decolorisation--Glycerine obtained by other Methods of
+     Saponification--Yield of Glycerine from Fats and Oils._
+
+
+As pointed out in Chapter II. the fatty acids, which, combined with soda
+or potash, form soap, occur in nature almost invariably in the form of
+glycerides, _i.e._, compounds of fatty acids with glycerol, and as the
+result of saponification of a fat or oil glycerine is set free.
+
+In Chapter V. processes of soap-making are described in which (1) the
+glycerine is retained in the finished soap, and (2) the glycerine is
+contained in the lyes, in very dilute solution, contaminated with salt
+and other impurities. These lyes, though now constituting the chief
+source of profit in the manufacture of cheap soaps, were till early in
+last century simply run down the drains as waste liquor.
+
+Much attention has been devoted to the purification and concentration of
+glycerine lyes; and elaborate plant of various forms has been devised
+for the purpose.
+
+_Treatment of Lyes._--The spent lyes withdrawn from the soap-pans are
+cooled, and the soap, which has separated during the cooling, is
+carefully removed and returned to the soap-house for utilisation in the
+manufacture of brown soap. Spent lyes may vary in their content of
+glycerol from 3 to 8 per cent., and this depends not only upon the
+system adopted in the working of the soap-pans, but also upon the
+materials used. Although, in these days of pure caustic soda, spent lyes
+are more free from impurities than formerly, the presence of sulphides
+and sulphites should be carefully avoided, if it is desired to produce
+good glycerine.
+
+The lyes are transferred to a lead-lined tank of convenient size, and
+treated with commercial hydrochloric acid and aluminium sulphate,
+sufficient being added of the former to neutralise the free alkali, and
+render the liquor faintly acid, and of the latter to completely
+precipitate the fatty acids. The acid should be run in slowly, and the
+point when enough has been added, is indicated by blue litmus paper
+being slightly reddened by the lyes.
+
+The whole is then agitated with air, when a sample taken from the tank
+and filtered should give a clear filtrate.
+
+Having obtained this clear solution, agitation is stopped, and the
+contents of the tank passed through a filter press. The scum, which
+accumulates on the treatment tank, may be transferred to a perforated
+box suspended over the tank, and the liquor allowed to drain from it.
+The filtered liquor is now rendered slightly alkaline by the addition of
+caustic soda or carbonate, and, after filtering, is ready for
+evaporation.
+
+The acid and alum salt used in the above treatment must be carefully
+examined for the presence of arsenic, and any deliveries of either
+article, which contain that impurity, rejected.
+
+Lime, bog ore, and various metallic salts, such as ferric chloride,
+barium chloride, and copper sulphate have been suggested, and in some
+instances are used instead of aluminium sulphate, but the latter is
+generally employed.
+
+_Evaporation to Crude Glycerine._--The clear treated lyes, being now
+free from fatty, resinous, and albuminous matter, and consisting
+practically of an aqueous solution of common salt (sodium chloride) and
+glycerine, is converted into crude glycerine by concentration, which
+eliminates the water and causes most of the salt to be deposited.
+
+This concentration was originally performed in open pans heated by fire
+or waste combustible gases. In the bottom of each pan was placed a dish
+in which the salt deposited, and this dish was lifted out periodically
+by the aid of an overhead crane and the contents emptied and washed.
+Concentration was continued until the temperature of the liquor was 300°
+F. (149° C.), when it was allowed to rest before storing.
+
+This liquor on analysis gave 80 per cent. glycerol and from 9 to 10-1/2
+per cent. salts (ash); hence the present standard for crude glycerine.
+
+Concentration in open pans has now been superseded by evaporation _in
+vacuo_. The subject of the gradual development of the modern efficient
+evaporating plant from the vacuum pan, originated and successfully
+applied by Howard in 1813 in the sugar industry, is too lengthy to
+detail here, suffice it to say that the multiple effects now in vogue
+possess distinct advantages--the greatest of these being increased
+efficiency combined with economy.
+
+The present type of evaporator consists of one or more vessels, each
+fitted with a steam chamber through which are fixed vertical hollow
+tubes. The steam chamber of the first vessel is heated with direct
+steam, or with exhaust steam (supplied from the exhaust steam receiver
+into which passes the waste steam of the factory); the treated lyes
+circulating through the heated tubes is made to boil at a lower
+temperature, with the reduced pressure, than is possible by heating in
+open pans.
+
+The vapour given off by the boiling liquor is conveyed through large
+pipes into the steam chamber of the second vessel, where its latent heat
+is utilised in producing evaporation, the pressure being further
+reduced, as this second vessel is under a greater vacuum than No. 1.
+Thus we get a "double effect," as the plant consisting of two pans is
+termed. The vapours discharged from the second vessel during boiling are
+passed through pipes to the steam chamber of the third vessel (in a
+"triple effect"), and there being condensed, create a partial vacuum in
+the second vessel. The third vessel may also be heated by means of live
+steam. The vapours arising from the last vessel of the evaporating
+plant, or in the case of a "single effect" from the vessel, are conveyed
+into a condenser and condensed by injection water, which is drawn off by
+means of the pump employed for maintaining a vacuum of 28 inches in the
+vessel.
+
+In the most recent designs of large evaporative installations, the
+vapours generated from the last vessel are drawn through a device
+consisting of a number of tubes enclosed in a casing, and the latent
+heat raises the temperature of the treated lyes proceeding through the
+tubes to supply the evaporator.
+
+It will thus be observed that the object of multiple effects is to
+utilise all the available heat in performing the greatest possible
+amount of work. Special devices are attached to the plant for
+automatically removing the condensed water from the steam chambers
+without the loss of useful heat, and as a precaution against splashing
+over and subsequent loss of glycerine through conveyance to the steam
+chamber, dash plates and "catch-alls" or "save-alls" of various designs
+are fitted on each vessel.
+
+In working the plant, the liquor in each vessel is kept at a fairly
+constant level by judicious feeding from one to the other; the first
+vessel is, of course, charged with treated lyes. As the liquor acquires
+a density of 42° Tw. (25° B.) salt begins to deposit, and may be
+withdrawn into one of the many patented appliances, in which it is freed
+from glycerine, washed and dried ready for use at the soap pans.
+Difficulty is sometimes experienced with the tubes becoming choked with
+salt, thereby diminishing and retarding evaporation. It may be necessary
+to dissolve the encrusted salt with lyes or water, but with careful
+working the difficulty can be obviated by washing out with weak lyes
+after each batch of crude glycerine has been run away, or by increasing
+the circulation.
+
+It is claimed that by the use of the revolving heater designed by
+Lewkowitsch, the salting up of tubes is prevented.
+
+The salt having been precipitated and removed, evaporation is continued
+until a sample taken from the last vessel has a density of 60° Tw. (33.3
+B.) at 60° F. (15.5° C.). When this point is reached, the crude
+glycerine is ready to be withdrawn into a tank, and, after allowing the
+excess of salt to deposit, may be transferred to the storage tank.
+
+The colour of crude glycerine varies from light brown to dark brown,
+almost black, and depends largely on the materials used for soap-making.
+The organic matter present in good crude glycerine is small in amount,
+often less than 1 per cent.; arsenic, sulphides and sulphites should be
+absent. Crude glycerine is refined in some cases by the producers
+themselves; others sell it to firms engaged more particularly in the
+refined glycerine trade.
+
+_Distillation._--Crude glycerine is distilled under vacuum with the aid
+of superheated steam. The still is heated directly with a coal or coke
+fire, and in this fire space is the superheater, which consists of a
+coil of pipes through which high pressure steam from the boiler is
+superheated.
+
+The distillation is conducted at a temperature of 356°F. (180° C.). To
+prevent the deposition and burning of salt on the still-bottom during
+the distillation, a false bottom is supported about 1 foot from the base
+of the still. With the same object in view, it has been suggested to
+rotate the contents with an agitator fixed in the still.
+
+Every care is taken that the still does not become overheated; this
+precaution not only prevents loss of glycerine through carbonisation,
+but also obviates the production of tarry and other bodies which might
+affect the colour, taste, and odour of the distilled glycerine. The
+vacuum to be used will, of course, depend upon the heat of the fire and
+still, but as a general rule good results are obtained with an 18 inch
+vacuum.
+
+There are quite a large number of designs for still heads, and
+"catch-alls," having for their object the prevention of loss of
+glycerine.
+
+The distillate passes into a row of condensers, to each of which is
+attached a receptacle or receiver. It is needless to state that the
+condensing capacity should be in excess of theoretical requirements. The
+fractions are of varying strengths and quality; that portion, with a
+density less than 14° Tw. (19.4° B.), is returned to the treated-lyes
+tank. The other portion of the distillate is concentrated by means of a
+dry steam coil in a suitable vessel under a 28 inch vacuum.
+
+When sufficiently concentrated the glycerine may be decolorised, if
+necessary, by treating with 1 per cent. animal charcoal and passing
+through a filter press, from which it issues as "dynamite glycerine".
+
+The residue in the still, consisting of 50-60 per cent. glycerine and
+varying proportions of various sodium salts--_e.g._ acetate, chloride,
+sulphate, and combinations with non-volatile organic acids--is generally
+boiled with water and treated with acid.
+
+The tar, which is separated, floats on the surface as the liquor is
+cooling, and may be removed by ladles, or the whole mixed with waste
+charcoal, and filtered.
+
+The filtrate is then evaporated, when the volatile organic acids are
+driven off; the concentrated liquor is finally mixed with crude
+glycerine which is ready for distillation, or it may be distilled
+separately.
+
+_Distilled Glycerine._--This class of commercial glycerine, although of
+limited use in various other branches of industry, finds its chief
+outlet in the manufacture of explosives.
+
+Specifications are usually given in contracts drawn up between buyers
+and sellers, to which the product must conform.
+
+The chief stipulation for dynamite glycerine is its behaviour in the
+nitration test. When glycerine is gradually added to a cold mixture of
+strong nitric and sulphuric acids, it is converted into nitro-glycerine,
+which separates as an oily layer on the surface of the acid. The more
+definite and rapid the separation, the more suitable is the glycerine
+for dynamite-making.
+
+Dynamite glycerine should be free from arsenic, lime, chlorides, and
+fatty acids, the inorganic matter should not amount to more than 0.1 per
+cent., and a portion diluted and treated with nitrate of silver solution
+should give no turbidity or discoloration in ten minutes. The specific
+gravity should be 1.262 at 15° C. (59° F.) and the colour somewhat
+yellow.
+
+_Chemically pure glycerine_ or double distilled glycerine is produced by
+redistilling "once distilled" glycerine. Every care is taken to avoid
+all fractions which do not withstand the nitrate of silver test. The
+distillation is very carefully performed under strict supervision.
+
+The distillate is concentrated and after treatment with animal charcoal
+and filtration should conform to the requirements of the British
+Pharmacopoeia. These are specified as follows: Specific gravity at
+15.5° C., 1.260. It should yield no characteristic reaction with the
+tests for lead, copper, arsenium, iron, calcium, potassium, sodium,
+ammonium, chlorides, or sulphates. It should contain no sugars and leave
+no residue on burning.
+
+_Animal Charcoal for Decolorisation._--The application of animal
+charcoal for decolorising purposes dates back a century, and various are
+the views that have been propounded to explain its action. Some
+observers base it upon the physical condition of the so-called carbon
+present, and no doubt this is an important factor, coupled with the
+porosity. Others consider that the nitrogen, which is present in all
+animal charcoal and extremely difficult to remove, is essential to the
+action. Animal charcoal should be freed from gypsum (sulphate of lime),
+lest in the burning, sulphur compounds be formed which would pass into
+the glycerine and contaminate it.
+
+The "char" should be well boiled with water, then carbonate of soda or
+caustic soda added in sufficient quantity to give an alkaline reaction,
+and again well boiled. The liquor is withdrawn and the charcoal washed
+until the washings are no longer alkaline. The charcoal is then
+separated from the liquor and treated with hydrochloric acid; opinions
+differ as to the amount of acid to be used. Some contend that phosphate
+of lime plays such an important part in decolorising that it should not
+be removed, but it has, however, been demonstrated that this substance
+after exposure to heat has very little decolorising power.
+
+Animal charcoal boiled with four times its weight of a mixture
+consisting of equal parts of commercial hydrochloric acid (free from
+arsenic) and water for twelve hours, then washed free from acid, dried,
+and burned in closed vessels gives a product possessed of great
+decolorising power for use with glycerines.
+
+A good animal charcoal will have a dull appearance, and be of a deep
+colour; it should be used in fine grains and not in the form of a
+powder.
+
+The charcoal from the filter presses is washed free from glycerine
+(which is returned to the treated lyes), cleansed from foreign
+substances by the above treatment and revivified by carefully heating in
+closed vessels for twelve hours.
+
+_Glycerine obtained by other Methods of Saponification._--French
+saponification or "candle crude" glycerine is the result of
+concentration of "sweet water" produced in the manufacture of stearine
+and by the autoclave process. It contains 85-90 per cent. glycerol,
+possesses a specific gravity of 1.240-1.242, and may be readily
+distinguished from the soap-crude glycerine by the absence of salt
+(sodium chloride). This glycerine is easily refined by treatment with
+charcoal.
+
+The glycerine water resulting from acid saponification methods requires
+to be rendered alkaline by the addition of lime--the sludge is
+separated, and the liquor evaporated to crude. The concentration may be
+performed in two stages--first to a density of 32° Tw. (20° B.), when
+the calcium sulphate is allowed to deposit, and the separated liquor
+concentrated to 48° Tw. (28° B.) glycerine, testing 85 per cent.
+glycerol and upwards.
+
+_Yield of Glycerine from Fats and Oils._--The following represent
+practicable results which should be obtained from the various
+materials:--
+
+    Tallow                 9 per cent. of 80 per cent. Glycerol.
+    Cotton-seed oil       10    "
+    Cocoa-nut oil         12    "
+    Palm-kernel oil       18    "
+    Olive oil             10    "
+    Palm oil               6    "
+    Greases (Bone fats)  6-8    "
+
+The materials vary in glycerol content with the methods of preparation;
+especially is this the case with tallows and greases.
+
+Every care should be taken that the raw materials are fresh and they
+should be carefully examined to ascertain if any decomposition has taken
+place in the glycerides--this would be denoted by the presence of an
+excess of free acidity, and the amount of glycerol obtainable from such
+a fat would be correspondingly reduced.
+
+
+
+
+CHAPTER X.
+
+ANALYSIS OF RAW MATERIALS, SOAP, AND GLYCERINE.
+
+     _Fats and Oils--Alkalies and Alkali Salts--Essential
+     Oils--Soap--Lyes--Crude Glycerine._
+
+
+_Raw Materials._--Average figures have already been given in Chapters
+III. and VIII. for the more important physical and chemical
+characteristics of fats and oils, also of essential oils; the following
+is an outline of the processes usually adopted in their determination.
+For fuller details, text-books dealing exhaustively with the respective
+subjects should be consulted.
+
+
+FATS AND OILS.
+
+It is very undesirable that any of these materials should be allowed to
+enter the soap pan without an analysis having first been made, as the
+oil may not only have become partially hydrolysed, involving a loss of
+glycerine, or contain albuminous matter rendering the soap liable to
+develop rancidity, but actual sophistication may have taken place. Thus
+a sample of tallow recently examined by the authors contained as much as
+40 per cent. of an unsaponifiable wax, which would have led to disaster
+in the soap pan, had the bulk been used without examination. After
+observing the appearance, colour, and odour of the sample, noting any
+characteristic feature, the following physical and chemical data should
+be determined.
+
+_Specific Gravity at 15° C._ This may be taken by means of a Westphal
+balance, or by using a picnometer of either the ordinary gravity bottle
+shape, with perforated stopper, or the Sprengel U-tube. The picnometer
+should be calibrated with distilled water at 15° C. The specific gravity
+of solid fats may be taken at an elevated temperature, preferably that
+of a boiling water bath.
+
+_Free acidity_ is estimated by weighing out from 2 to 5 grammes of the
+fat or oil, dissolving in neutral alcohol (purified methylated spirit)
+with gentle heat, and titrating with a standard aqueous or alcoholic
+solution of caustic soda or potash, using phenol-phthalein as indicator.
+
+The contents of the flask are well shaken after each addition of alkali,
+and the reaction is complete when the slight excess of alkali causes a
+permanent pink coloration with the indicator. The standard alkali may be
+N/2, N/5, or N/10.
+
+It is usual to calculate the result in terms of oleic acid (1 c.c. N/10
+alkali = 0.0282 gramme oleic acid), and express in percentage on the fat
+or oil.
+
+_Example._--1.8976 grammes were taken, and required 5.2 c.c. of N/10 KOH
+solution for neutralisation.
+
+          5.2 × 0.0282 × 100
+          ------------------ = 7.72 per cent. free fatty acids,
+                1.8976                expressed as oleic acid.
+
+The free acidity is sometimes expressed as _acid value_, which is the
+amount of KOH in milligrammes necessary to neutralise the free acid in 1
+gramme of fat or oil.
+
+In the above example:--
+
+          5.2 × 5.61
+          ---------- = 15.3 acid value.
+            1.8976
+
+The _saponification equivalent_ is determined by weighing 2-4 grammes of
+fat or oil into a wide-necked flask (about 250 c.c. capacity), adding 30
+c.c. neutral alcohol, and warming under a reflux condenser on a steam or
+water-bath. When boiling, the flask is disconnected, 50 c.c. of an
+approximately semi-normal alcoholic potash solution carefully added from
+a burette, together with a few drops of phenol-phthalein solution, and
+the boiling under a reflux condenser continued, with frequent agitation,
+until saponification is complete (usually from 30-60 minutes) which is
+indicated by the absence of fatty globules. The excess of alkali is
+titrated with N/1 hydrochloric or sulphuric acid.
+
+The value of the approximately N/2 alkali solution is ascertained by
+taking 50 c.c. together with 30 c.c. neutral alcohol in a similar flask,
+boiling for the same length of time as the fat, and titrating with N/1
+hydrochloric or sulphuric acid. The "saponification equivalent" is the
+amount of fat or oil in grammes saponified by 1 equivalent or 56.1
+grammes of caustic potash.
+
+_Example._--1.8976 grammes fat required 18.95 c.c. N/1 acid to
+neutralise the unabsorbed alkali.
+
+Fifty c.c. approximately N/2 alcoholic potash solution required 25.6
+c.c. N/ acid..
+
+          25.6 - 18.95 = 6.65 c.c. N/1 KOH required by fat.
+
+          1.8976 × 1000 / 6.65 = 285.3 Saponification Equivalent.
+
+The result of this test is often expressed as the "Saponification
+Value," which is the number of milligrammes of KOH required for the
+saponification of 1 gramme of fat. This may be found by dividing 56,100
+by the saponification equivalent or by multiplying the number of c.c. of
+N/1 alkali absorbed, by 56.1 and dividing by the quantity of fat taken.
+Thus, in the above example:--
+
+          6.65 × 56.1 / 1.8976 = 196.6 Saponification Value.
+
+The _ester_ or _ether value_, or number of milligrammes of KOH required
+for the saponification of the neutral esters or glycerides in 1 gramme
+of fat, is represented by the difference between the saponification and
+acid values. In the example given, the ester value would be 196.6 - 15.3
+= 181.3.
+
+_Unsaponifiable Matter._--The usual method adopted is to saponify about
+5 grammes of the fat or oil with 50 c.c. of approximately N/2 alcoholic
+potash solution by boiling under a reflux condenser with frequent
+agitation for about 1 hour. The solution is then evaporated to dryness
+in a porcelain basin over a steam or water-bath, and the resultant soap
+dissolved in about 200 c.c. hot water. When sufficiently cool, the soap
+solution is transferred to a separating funnel, 50 c.c. of ether added,
+the whole well shaken, and allowed to rest. The ethereal layer is
+removed to another separator, more ether being added to the aqueous soap
+solution, and again separated. The two ethereal extracts are then washed
+with water to deprive them of any soap, separated, transferred to a
+flask, and the ether distilled off upon a water-bath. The residue, dried
+in the oven at 100° C. until constant, is the "unsaponifiable matter,"
+which is calculated to per cent. on the oil.
+
+In this method, it is very frequently most difficult to obtain a
+distinct separation of ether and aqueous soap solution--an intermediate
+layer of emulsion remaining even after prolonged standing, and various
+expedients have been recommended to overcome this, such as addition of
+alcohol (when petroleum ether is used), glycerine, more ether, water, or
+caustic potash solution, or by rotatory agitation.
+
+A better plan is to proceed as in the method above described as far as
+dissolving the resulting soap in 200 c.c. water, and then boil for
+twenty or thirty minutes. Slightly cool and acidify with dilute
+sulphuric acid (1 to 3), boil until the fatty acids are clear, wash with
+hot water free from mineral acid, and dry by filtering through a hot
+water funnel.
+
+Two grammes of the fatty acids are now dissolved in neutral alcohol
+saturated with some solvent, preferably a light fraction of benzoline, a
+quantity of the solvent added to take up the unsaponifiable matter, and
+the whole boiled under a reflux condenser. After cooling, the liquid is
+titrated with N/2 aqueous KOH solution, using phenol-phthalein as
+indicator, this figure giving the amount of the total fatty acids
+present. The whole is then poured into a separating funnel, when
+separation immediately takes place. The alcoholic layer is withdrawn,
+the benzoline washed with warm water (about 32° C.) followed by neutral
+alcohol (previously saturated with the solvent), and transferred to a
+tared flask, which is attached to a condenser, and the benzoline
+distilled off. The last traces of solvent remaining in the flask are
+removed by gently warming in the water-oven, and the flask cooled and
+weighed, thus giving the amount of unsaponifiable matter.
+
+_Constitution of the Unsaponifiable Matter._--Unsaponifiable matter may
+consist of cholesterol, phytosterol, solid alcohols (cetyl and ceryl
+alcohols), or hydrocarbons (mineral oil). Cholesterol is frequently
+found in animal fats, and phytosterol is a very similar substance
+present in vegetable fats. Solid alcohols occur naturally in sperm oil,
+but hydrocarbons, which may be generally recognised by the fluorescence
+or bloom they give to the oil, are not natural constituents of animal or
+vegetable oils and fats.
+
+The presence of cholesterol and phytosterol may be detected by
+dissolving a small portion of the unsaponifiable matter in acetic
+anhydride, and adding a drop of the solution to one drop of 50 per cent.
+sulphuric acid on a spot plate, when a characteristic blood red to
+violet coloration is produced. It has been proposed to differentiate
+between cholesterol and phytosterol by their melting points, but it is
+more reliable to compare the crystalline forms, the former crystallising
+in laminæ, while the latter forms groups of needle-shaped tufts. Another
+method is to convert the substance into acetate, and take its melting
+point, cholesterol acetate melting at 114.3-114.8° C., and phytosterol
+acetate at 125.6°-137° C.
+
+Additional tests for cholesterol have been recently proposed by
+Lifschütz (_Ber. Deut. Chem. Ges._, 1908, 252-255), and Golodetz (_Chem.
+Zeit._, 1908, 160). In that due to the former, which depends on the
+oxidation of cholesterol to oxycholesterol ester and oxycholesterol, a
+few milligrammes of the substance are dissolved in 2-3 c.c. glacial
+acetic acid, a little benzoyl peroxide added, and the solution boiled,
+after which four drops of strong sulphuric acid are added, when a
+violet-blue or green colour is produced, if cholesterol is present, the
+violet colour being due to oxycholesterol ester, the green to
+oxycholesterol. Two tests are suggested by Golodetz (1) the addition of
+one or two drops of a reagent consisting of five parts of concentrated
+sulphuric acid and three parts of formaldehyde solution, which colours
+cholesterol a blackish-brown, and (2) the addition of one drop of 30 per
+cent. formaldehyde solution to a solution of the substance in
+trichloracetic acid, when with cholesterol an intense blue coloration is
+produced.
+
+_Water._--From 5 to 20 grammes of the fat or oil are weighed into a
+tared porcelain or platinum dish, and stirred with a thermometer, whilst
+being heated over a gas flame at 100° C. until bubbling or cracking has
+ceased, and reweighed, the loss in weight representing the water. In
+cases of spurting a little added alcohol will carry the water off
+quietly.
+
+To prevent loss by spurting, Davis (_J. Amer. Chem. Soc._, 23, 487) has
+suggested that the fat or oil should be added to a previously dried and
+tared coil of filter paper contained in a stoppered weighing bottle,
+which is then placed in the oven and dried at 100° C. until constant in
+weight. Of course, this method is not applicable to oils or fats liable
+to oxidation on heating.
+
+_Dregs, Dirt, Adipose Tissue, Fibre, etc._--From 10 to 15 grammes of the
+fat are dissolved in petroleum ether with frequent stirring, and passed
+through a tared filter paper. The residue retained by the filter paper
+is washed with petroleum ether until free from fat, dried in the
+water-oven at 100° C. and weighed.
+
+If the amount of residue is large, it may be ignited, and the proportion
+and nature of the ash determined.
+
+The amount of impurities may also be estimated by Tate's method, which
+is performed by weighing 5 grammes of fat into a separating funnel,
+dissolving in ether, and allowing the whole to stand to enable the water
+to deposit. After six hours' rest the water is withdrawn, the tube of
+the separator carefully dried, and the ethereal solution filtered
+through a dried tared filter paper into a tared flask. Well wash the
+filter with ether, and carefully dry at 100° C. The ether in the flask
+is recovered, and the flask dried until all ether is expelled, and its
+weight is constant. The amount of fat in the flask gives the quantity of
+actual fat in the sample taken; the loss represents the water and other
+impurities, and these latter may be obtained from the increase of weight
+of the filter paper.
+
+_Starch_ may be detected by the blue coloration it gives with iodine
+solution, and confirmed by microscopical examination, or it may be
+converted into glucose by inversion, and the glucose estimated by means
+of Fehling's solution.
+
+_Iodine Absorption._--This determination shows the amount of iodine
+absorbed by a fat or oil, and was devised by Hübl, the reagents required
+being as follows:--
+
+(1) Solution of 25 grammes iodine in 500 c.c. absolute alcohol; (2)
+solution of 30 grammes mercuric chloride in 500 c.c. absolute alcohol,
+these two solutions being mixed together and allowed to stand at least
+twelve hours before use; (3) a freshly prepared 10 per cent. aqueous
+solution of potassium iodide; and (4) a N/10 solution of sodium
+thiosulphate, standardised just prior to use by titrating a weighed
+quantity of resublimed iodine dissolved in potassium iodide solution.
+
+In the actual determination, 0.2 to 0.5 gramme of fat or fatty acids is
+carefully weighed into a well-fitting stoppered 250 c.c. bottle,
+dissolved in 10 c.c. chloroform, and 25 c.c. of the Hübl reagent added,
+the stopper being then moistened with potassium iodide solution and
+placed firmly in the bottle, which is allowed to stand at rest in a dark
+place for four hours. A blank experiment is also performed, using the
+same quantities of chloroform and Hübl reagent, and allowing to stand
+for the same length of time.
+
+After the expiration of four hours 20 c.c. of 10 per cent. solution of
+potassium iodide and 150 c.c. water are added to the contents of the
+bottle, and the excess of iodine titrated with N/10 sodium thiosulphate
+solution, the whole being well agitated during the titration, which is
+finished with starch paste as indicator. The blank experiment is
+titrated in the same manner, and from the amount of thiosulphate
+required in the blank experiment is deducted the number of c.c. required
+by the unabsorbed iodine in the other bottle; this figure multiplied by
+the iodine equivalent of 1 c.c. of the thiosulphate solution and by 100,
+dividing the product by the weight of fat taken, gives the "Iodine
+Number".
+
+_Example._--1 c.c. of the N/10 sodium thiosulphate solution is found
+equal to 0.0126 gramme iodine.
+
+0.3187 gramme of fat taken. Blank requires 48.5 c.c. thiosulphate.
+
+Bottle containing oil requires 40.0 c.c. thiosulphate.
+
+48.5 - 40.0 = 8.5, and the iodine absorption of the fat is--
+
+          8.5 × 0.0126 × 100
+          ------------------ = 33.6.
+                0.3187
+
+Wijs showed that by the employment of a solution of iodine monochloride
+in glacial acetic acid reliable iodine figures are obtained in a much
+shorter time, thirty minutes being sufficient, and this method is now in
+much more general use than the Hübl. Wijs' iodine reagent is made by
+dissolving 13 grammes iodine in 1 litre of glacial acetic acid and
+passing chlorine into the solution until the iodine is all converted
+into iodine monochloride. The process is carried out in exactly the same
+way as with the Hübl solution except that the fat is preferably
+dissolved in carbon tetrachloride instead of in chloroform.
+
+_Bromine absorption_ has now been almost entirely superseded by the
+iodine absorption, although there are several good methods. The
+gravimetric method of Hehner (_Analyst_, 1895, 49) was employed by one
+of us for many years with very good results, whilst the bromine-thermal
+test of Hehner and Mitchell (_Analyst_, 1895, 146) gives rapid and
+satisfactory results. More recently MacIlhiney (_Jour. Amer. Chem.
+Soc._, 1899, 1084-1089) drew attention to bromine absorption methods and
+tried to rewaken interest in them.
+
+The _Refractive index_ is sometimes useful for discriminating between
+various oils and fats, and, in conjunction with other physical and
+chemical data, affords another means of detecting adulteration.
+
+Where a great number of samples have to be tested expeditiously, the
+Abbé refractometer or the Zeiss butyro-refractometer may be recommended
+on account of the ease with which they are manipulated. The most usual
+temperature of observations is 60° C.
+
+The _Titre_ or setting point of the fatty acids was devised by Dalican,
+and is generally accepted in the commercial valuation of solid fats as a
+gauge of firmness, and in the case of tallow has a considerable bearing
+on the market value.
+
+One ounce of the fat is melted in a shallow porcelain dish, and 30 c.c.
+of a 25 per cent. caustic soda solution added, together with 50 c.c. of
+redistilled methylated spirit. The whole is stirred down on the water
+bath until a pasty soap is obtained, when another 50 c.c. of methylated
+spirit is added, which redissolves the soap, and the whole again stirred
+down to a solid soap. This is then dissolved in distilled water, a
+slight excess of dilute sulphuric acid added to liberate the fatty
+acids, and the whole warmed until the fatty acids form a clear liquid
+on the surface. The water beneath the fatty acids is then syphoned off,
+more distilled water added to wash out any trace of mineral acid
+remaining, and again syphoned off, this process being repeated until the
+washings are no longer acid to litmus paper, when the fatty acids are
+poured on to a dry filter paper, which is inserted in a funnel resting
+on a beaker, and the latter placed on the water-bath, where it is left
+until the clear fatty acids have filtered through.
+
+About 10-15 grammes of the pure fatty acids are now transferred to a
+test tube, 6" × 1", warmed until molten, and the tube introduced through
+a hole in the cork into a flask or wide-mouthed bottle. A very accurate
+thermometer, graduated into fifths of a degree Centigrade (previously
+standardised), is immersed in the fatty acids, so that the bulb is as
+near the centre as possible, and when the fatty acids just begin to
+solidify at the bottom of the tube, the thermometer is stirred round
+slowly. The mercury will descend, and stirring is continued until it
+ceases to fall further, at which point the thermometer is very carefully
+observed. It will be found that the temperature will rise rapidly and
+finally remain stationary for a short time, after which it will again
+begin to drop until the temperature of the room is reached. The maximum
+point to which the temperature rises is known as the "titre" of the
+sample.
+
+
+ALKALIES AND ALKALI SALTS.
+
+Care should be bestowed upon the sampling of solid caustic soda or
+potash as the impurities during the solidification always accumulate in
+the centre of the drum, and an excess of that portion must be avoided or
+the sample will not be sufficiently representative. The sampling should
+be performed expeditiously to prevent carbonating, and portions placed
+in a stoppered bottle. The whole should be slightly broken in a mortar,
+and bright crystalline portions taken for analysis, using a stoppered
+weighing bottle.
+
+_Caustic Soda and Caustic Potash._--These substances are valued
+according to the alkali present in the form of caustic (hydrate) and
+carbonate.
+
+About 2 grammes of the sample are dissolved in 50 c.c. distilled water,
+and titrated with N/1 sulphuric acid, using phenol-phthalein as
+indicator, the alkalinity so obtained representing all the caustic
+alkali and one-half the carbonate, which latter is converted into
+bicarbonate. One c.c. N/1 acid = 0.031 gramme Na_{2}O or 0.040 gramme
+NaOH and 0.047 gramme K_{2}O, or 0.056 gramme KOH.
+
+After this first titration, the second half of the carbonate may be
+determined in one of two ways, either:--
+
+(1) By adding from 3-5 c.c. of N/10 acid, and well boiling for five
+minutes to expel carbonic-acid gas, after which the excess of acid is
+titrated with N/10 soda solution; or
+
+(2) After adding two drops of methyl orange solution, N/10 acid is run
+in until the solution acquires a faint pink tint.
+
+In the calculation of the caustic alkali, the number of c.c. of acid
+required in the second titration, divided by 10, is subtracted from that
+used in the first, and this difference multiplied by 0.031, or 0.047
+gives the amount of Na_{2}O or K_{2}O respectively in the weight of
+sample taken, whence the percentage may be readily calculated.
+
+The proportion of carbonate is calculated by multiplying the amount of
+N/10 acid required in the second titration by 2, and then by either
+0.0031 or 0.0047 to give the amount of carbonate present, expressed as
+Na_{2}O or K_{2}O respectively.
+
+An alternative method is to determine the alkalinity before and after
+the elimination of carbonate by chloride of barium.
+
+About 7-8 grammes of the sample are dissolved in water, and made up to
+100 c.c., and the total alkalinity determined by titrating 20 c.c. with
+N/1 acid, using methyl orange as indicator. To another 20 c.c. is added
+barium chloride solution (10 per cent.) until it ceases to give a
+precipitate, the precipitate allowed to settle, and the clear
+supernatant liquid decanted off, the precipitate transferred to a filter
+paper and well washed, and the filtrate titrated with N/1 acid, using
+phenol-phthalein as indicator. The second titration gives the amount of
+caustic alkali present, and the difference between the two the
+proportion of carbonate.
+
+When methyl orange solution is used as indicator, titrations must be
+carried out cold.
+
+Reference has already been made (p. 39) to the manner in which the
+alkali percentage is expressed in English degrees in the case of caustic
+soda.
+
+_Chlorides_ are estimated by titrating the neutral solution with N/10
+silver nitrate solution, potassium chromate being used as indicator. One
+c.c. N/10 AgNO_{3} solution = 0.00585 gramme sodium chloride.
+
+The amount of acid necessary for exact neutralisation having already
+been ascertained, it is recommended to use the equivalent quantity of
+N/10 nitric acid to produce the neutral solution.
+
+_Sulphides_ may be tested for, qualitatively, with lead acetate
+solution.
+
+_Aluminates_ are determined gravimetrically in the usual manner; 2
+grammes are dissolved in water, rendered acid with HCl, excess of
+ammonia added, and the gelatinous precipitate of aluminium hydrate
+collected on a filter paper, washed, burnt, and weighed.
+
+       *       *       *       *       *
+
+_Carbonated Alkali (Soda Ash)._--The total or available alkali is, of
+course, the chief factor to be ascertained, and for this purpose it is
+convenient to weigh out 3.1 grammes of the sample, dissolve in 50 c.c.
+water, and titrate with N/1 sulphuric or hydrochloric acid, using methyl
+orange as indicator. Each c.c. of N/1 acid required represents 1 per
+cent. Na_{2}O in the sample under examination.
+
+A more complete analysis of soda ash would comprise:--
+
+_Insoluble matter_, remaining after 10 grammes are dissolved in warm
+water. This is washed on to a filter-paper, dried, ignited, and weighed.
+
+The filtrate is made up to 200 c.c., and in it may be determined:--
+
+_Caustic soda_, by titrating with N/1 acid the filtrate resulting from
+the treatment of 20 c.c. (equal to 1 gramme) with barium chloride
+solution.
+
+_Carbonate._--Titrate 20 c.c. with N/1 acid, and deduct the amount of
+acid required for the Caustic.
+
+_Chlorides._--Twenty c.c. are exactly neutralised with nitric acid,
+titrated with N/10 AgNO_{3} solution, using potassium chromate as
+indicator.
+
+_Sulphates._--Twenty c.c. are acidulated with HCl, and the sulphates
+precipitated with barium chloride; the precipitate is collected on a
+filter paper, washed, dried, ignited, and weighed, the result being
+calculated to Na_{2}SO_{4}.
+
+_Sulphides and Sulphites._--The presence of these compounds is denoted
+by the evolution of sulphuretted hydrogen and sulphurous acid
+respectively when the sample is acidulated. Sulphides may also be tested
+for, qualitatively, with lead acetate solution, or test-paper of sodium
+nitro-prusside.
+
+The total quantity of these compounds may be ascertained by acidulating
+with acetic acid, and titrating with N/10 iodine solution, using starch
+paste as indicator. One c.c. N/10 iodine solution = 0.0063 gramme
+Na_{2}SO_{3}.
+
+The amount of sulphides may be estimated by titrating the hot soda
+solution, to which ammonia has been added, with an ammoniacal silver
+nitrate solution, 1 c.c. of which corresponds to 0.005 gramme Na_{2}S.
+As the titration proceeds, the precipitate is filtered off, and the
+addition of ammoniacal silver solution to the filtrate continued until a
+drop produces only a slight opacity. The presence of chloride, sulphate,
+hydrate, or carbonate does not interfere with the accuracy of this
+method. The ammoniacal silver nitrate solution is prepared by dissolving
+13.345 grammes of pure silver in pure nitric acid, adding 250 c.c.
+liquor ammoniæ fortis, and diluting to 1 litre.
+
+_Carbonate of Potash (Pearl Ash)._--The total or available alkali may be
+estimated by taking 6.9 grammes of the sample, and titrating with N/1
+acid directly, or adding 100 c.c. N/1 sulphuric acid, boiling for a few
+minutes, and titrating the excess of acid with N/1 caustic soda
+solution, using litmus as indicator. In this case each c.c. N/1 acid
+required, is equivalent, in the absence of Na_{2}CO_{3}, to 1 per cent.
+K_{2}CO_{3}.
+
+Carbonate of potash may be further examined for the following:--
+
+_Moisture._--From 2-3 grammes are heated for thirty minutes in a
+crucible over a gas flame, and weighed when cold, the loss in weight
+representing the moisture.
+
+_Insoluble residue_, remaining after solution in water, filtering and
+well washing.
+
+_Potassium_ may be determined by precipitation as potassium
+platino-chloride thus:--Dissolve 0.5 gramme in a small quantity (say 10
+c.c.) of water, and carefully acidulate with hydrochloric acid,
+evaporate the resultant liquor to dryness in a tared platinum basin, and
+heat the residue gradually to dull redness. Cool in a desicator, weigh,
+and express the result as "mixed chlorides," _i.e._ chlorides of soda
+and potash. To the mixed chlorides add 10 c.c. water, and platinic
+chloride in excess (the quantity may be three times the amount of the
+mixed chlorides) and evaporate nearly to dryness; add 15 c.c. alcohol
+and allow to stand three hours covered with a watch-glass, giving the
+dish a gentle rotatory movement occasionally. The clear liquid is
+decanted through a tared filter, and the precipitate well washed with
+alcohol by decantation, and finally transferred to the filter, dried and
+weighed. From the weight of potassium platino-chloride, K_{2}PtCl_{6},
+is calculated the amount of potassium oxide K_{2}O by the use of the
+factor 94/488.2 or 0.19254.
+
+_Chlorides_, determined with N/10 silver nitrate solution, and
+calculated to KCl.
+
+_Sulphates_, estimated as barium sulphate, and calculated to
+K_{2}SO_{4}.
+
+_Sodium Carbonate_, found by deducting the K_{2}CO_{3} corresponding to
+the actual potassium as determined above, from the total alkali.
+
+_Iron_, precipitated with excess of ammonia, filtered, ignited, and
+weighed as Fe_{2}O_{3}.
+
+
+SODIUM CHLORIDE (COMMON SALT).
+
+This should be examined for the following:--
+
+_Actual Chloride_, either titrated with N/10 silver nitrate solution,
+using neutral potassium chromate solution as indicator, or, preferably,
+estimated gravimetrically as silver chloride by precipitation with
+silver nitrate solution, the precipitate transferred to a tared filter
+paper, washed, dried and weighed.
+
+_Insoluble matter_, remaining on dissolving 5 grammes in water, and
+filtering. This is washed, dried, ignited and weighed.
+
+_Moisture._--5 grammes are weighed into a platinum crucible, and heat
+gently applied. The temperature is gradually increased to a dull red
+heat, which is maintained for a few minutes, the dish cooled in a
+desicator, and weighed.
+
+_Sulphates_ are estimated by precipitation as barium sulphate and
+calculated to Na_{2}SO_{4}.
+
+_Sodium._--This may be determined by converting the salt into sodium
+sulphate by the action of concentrated sulphuric acid, igniting to drive
+off hydrochloric and sulphuric acids, and fusing the mass until constant
+in weight, weighing finally as Na_{2}SO_{4}.
+
+
+POTASSIUM CHLORIDE.
+
+This should be examined, in the same way as sodium chloride, for
+chloride, insoluble matter, moisture, and sulphate. The potassium may be
+determined as potassium platino-chloride, as described under carbonate
+of potash.
+
+
+SILICATES OF SODA AND POTASH.
+
+The most important determinations for these are total alkali and silica.
+
+_Total alkali_ is estimated by dissolving 2 grammes in distilled water,
+and titrating when cold, with N/1 acid, using methyl orange as
+indicator.
+
+_Silica_ may be determined by dissolving 1 gramme in distilled water,
+rendering the solution acid with HCl, and evaporating to complete
+dryness on the water-bath, after which the residue is moistened with HCl
+and again evaporated, this operation being repeated a third time. The
+residue is then heated to about 150° C., extracted with hot dilute HCl,
+filtered, thoroughly washed, dried, ignited in a tared platinum
+crucible, and weighed as SiO_{2}.
+
+
+ESSENTIAL OILS.
+
+As already stated, these are very liable to adulteration, and an
+examination of all kinds of oil is desirable, while in the case of the
+more expensive varieties it should never be omitted.
+
+_Specific Gravity._--As with fats and oils, this is usually taken at 15°
+C., and compared with water at the same temperature. In the case of otto
+of rose and guaiac wood oil, however, which are solid at this
+temperature, it is generally observed at 30° C. compared with water at
+15° C.
+
+The specific gravity is preferably taken in a bottle or U-tube, but if
+sufficient of the oil is available and a high degree of accuracy is not
+necessary, it may be taken either with a Westphal balance, or by means
+of a hydrometer.
+
+_Optical Rotation._--For this purpose a special instrument, known as a
+polarimeter, is required, details of the construction and use of which
+would be out of place here. Suffice it to mention that temperature plays
+an important part in the determination of the optical activity of
+certain essential oils, notably in the case of lemon and orange oils.
+For these Gildemeister and Hoffmann give the following corrections:--
+
+Lemon oil, below 20° C. subtract 9' for each degree below, above 20° C.
+add 8' for each degree above.
+
+Orange oil, below 20° C. subtract 14' for each degree below, above 20°
+C. add 13' for each degree above.
+
+_Refractive Index._--This figure is occasionally useful, and is best
+determined with an Abbé refractometer, at 20° C.
+
+_Solubility in Alcohol._--This is found by running alcohol of the
+requisite strength from a burette into a measured volume of the oil with
+constant agitation, until the oil forms a clear solution with the
+alcohol. Having noted the quantity of alcohol added, it is well to run
+in a small further quantity of alcohol, and observe whether any
+opalescence or cloudiness appears.
+
+_Acid_, _ester_, and _saponification values_ are determined exactly as
+described under fats and oils. Instead of expressing the result as
+saponification value or number, the percentage of ester, calculated in
+the form of the most important ester present, may be obtained by
+multiplying the number of c.c. of N/1 alkali absorbed in the
+saponification by the molecular weight of the ester. Thus, to find the
+percentage as linalyl acetate, the number of c.c. absorbed would be
+multiplied by 0.196 and by 100, and divided by the weight of oil taken.
+
+_Alcohols._--For the estimation of these, if the oil contains much ester
+it must first be saponified with alcoholic potash, to liberate the
+combined alcohols, and after neutralising the excess of alkali with
+acid, the oil is washed into a separating funnel with water, separated,
+dried with anhydrous sodium sulphate, and is then ready for the alcohol
+determination.
+
+If there is only a small quantity of ester present, this preliminary
+saponification is unnecessary.
+
+The alcohols are estimated by conversion into their acetic esters, which
+are then saponified with standard alcoholic potash, thereby furnishing a
+measure of the amount of alcohol esterified.
+
+Ten c.c. of the oil is placed in a flask with an equal volume of acetic
+anhydride, and 2 grammes of anhydrous sodium acetate, and gently boiled
+for an hour to an hour and a half. After cooling, water is added, and
+the contents of the flask heated on the water-bath for fifteen to thirty
+minutes, after which they are cooled, transferred to a separating
+funnel, and washed with a brine solution until the washings cease to
+give an acid reaction with litmus paper. The oil is now dried with
+anhydrous sodium sulphate, filtered, and 1-2 grammes weighed into a
+flask and saponified with alcoholic potash as in the determination of
+ester or saponification value.
+
+The calculation is a little complicated, but an example may perhaps
+serve to make it clear.
+
+A geranium oil containing 26.9 per cent. of ester, calculated as geranyl
+tiglate, was acetylated, after saponification, to liberate the combined
+geraniol, and 2.3825 grammes of the acetylated oil required 9.1 c.c. of
+N/1 alkali for its saponification.
+
+Now every 196 grammes of geranyl acetate present in the acetylated oil
+correspond to 154 grammes of geraniol, so that for every 196 grammes of
+ester now present in the oil, 42 grammes have been added to its weight,
+and it is therefore necessary to make a deduction from the weight of oil
+taken for the final saponification to allow for this, and since each
+c.c. of N/1 alkali absorbed corresponds to 0.196 gramme of geranyl
+acetate, the amount to be deducted is found by multiplying the number of
+c.c. absorbed by 0.042 gramme, the formula for the estimation of total
+alcohols thus becoming in the example given:--
+
+                                    9.1 × 0.154 × 100
+          Per cent. of geraniol = ---------------------- = 70.2
+                                  2.3825 - (9.1 × 0.042)
+
+The percentage of combined alcohols can be calculated from the amount of
+ester found, and by subtracting this from the percentage of total
+alcohols, that of the free alcohols is obtained.
+
+In the example quoted, the ester corresponds to 17.6 per cent. geraniol,
+and this, deducted from the total alcohols, gives 52.6 per cent. free
+alcohols, calculated as geraniol.
+
+This process gives accurate results with geraniol, borneol, and menthol,
+but with linalol and terpineol the figures obtained are only
+comparative, a considerable quantity of these alcohols being decomposed
+during the acetylation. The aldehyde citronellal is converted by acetic
+anhydride into isopulegol acetate, so that this is also included in the
+determination of graniol in citronella oil.
+
+_Phenols._--These bodies are soluble in alkalies, and may be estimated
+by measuring 5 c.c. or 10 c.c. of the oil into a Hirschsohn flask (a
+flask of about 100 c.c. capacity with a long narrow neck holding 10
+c.c., graduated in tenths of a c.c.), adding 25 c.c. of a 5 per cent.
+aqueous caustic potash solution, and warming in the water-bath, then
+adding another 25 c.c., and after one hour in the water-bath filling the
+flask with the potash solution until the unabsorbed oil rises into the
+neck of the flask, the volume of this oil being read off when it has
+cooled down to the temperature of the laboratory. From the volume of oil
+dissolved the percentage of phenols is readily calculated.
+
+_Aldehydes._--In the estimation of these substances, use is made of
+their property of combining with sodium bisulphite to form compounds
+soluble in hot water. From 5-10 c.c. of the oil is measured into a
+Hirschsohn flask, about 30 c.c. of a hot saturated solution of sodium
+bisulphite added, and the flask immersed in a boiling water bath, and
+thoroughly shaken at frequent intervals. Further quantities of the
+bisulphite solution are gradually added, until, after about one hour,
+the unabsorbed oil rises into the neck of the flask, where, after
+cooling, its volume is read off, and the percentage of absorbed oil, or
+aldehydes, calculated.
+
+In the case of lemon oil, where the proportion of aldehydes, though of
+great importance, is relatively very small, it is necessary to first
+concentrate the aldehydes before determining them. For this purpose, 100
+c.c. of the oil is placed in a Ladenburg fractional distillation flask,
+and 90 c.c. distilled off under a pressure of not more than 40 mm., and
+the residue steam distilled. The oil so obtained is separated from the
+condensed water, measured, dried, and 5 c.c. assayed for aldehydes
+either by the process already described, or by the following process
+devised by Burgess (_Analyst_, 1904, 78):--
+
+Five c.c. of the oil are placed in the Hirschsohn flask, about 20 c.c.
+of a saturated solution of neutral sodium sulphite added, together with
+a few drops of rosolic acid solution as indicator, and the flask placed
+in a boiling water-bath and continually agitated. The contents of the
+flask soon become red owing to the liberation of free alkali by the
+combination of the aldehyde with part of the sodium sulphite, and this
+coloration is just discharged by the addition of sufficient 10 per
+cent. acetic-acid solution. The flask is again placed in the water-bath,
+the shaking continued, and any further alkali liberated neutralised by
+more acetic acid, the process being continued in this way until no
+further red colour is produced. The flask is then filled with the sodium
+sulphite solution, the volume of the cooled unabsorbed oil read off, and
+the percentage of aldehydes calculated as before.
+
+_Solidifying Point, or Congealing Point._--This is of some importance in
+the examination of anise and fennel oils, and is also useful in the
+examination of otto of rose. A suitable apparatus may be made by
+obtaining three test tubes, of different sizes, which will fit one
+inside the other, and fixing them together in this way through corks.
+The innermost tube is then filled with the oil, and a sensitive
+thermometer, similar to that described under the Titre test for fats,
+suspended with its bulb completely immersed in the oil. With anise and
+fennel, the oil is cooled down with constant stirring until it just
+starts crystallising, when the stirring is interrupted, and the maximum
+temperature to which the mercury rises noted. This is the solidifying
+point.
+
+In the case of otto of rose, the otto is continually stirred, and the
+point at which the first crystal is observed is usually regarded as the
+congealing point.
+
+_Melting Point._--This is best determined by melting some of the solid
+oil, or crystals, and sucking a small quantity up into a capillary tube,
+which is then attached by a rubber band to the bulb of the thermometer,
+immersed in a suitable bath (water, glycerine, oil, etc.) and the
+temperature of the bath gradually raised until the substance in the tube
+is sufficiently melted to rise to the surface, the temperature at which
+this takes place being the melting point.
+
+The melting point of otto of rose is usually taken in a similar tube to
+the setting point, and is considered to be the point at which the last
+crystal disappears.
+
+_Iodine Absorption._--In the authors' opinion, this is of some value in
+conjunction with other data in judging of the purity of otto of rose. It
+is determined by Hübl's process as described under Fats and Oils, except
+that only 0.1 to 0.2 gramme is taken, and instead of 10 c.c. of
+chloroform, 10 c.c. of pure alcohol are added. The rest of the process
+is identical.
+
+
+SOAP.
+
+In the analysis of soap, it is a matter of considerable importance that
+all the determinations should be made on a uniform and average sample of
+the soap, otherwise very misleading and unreliable figures are obtained.
+Soap very rapidly loses its moisture on the surface, while the interior
+of the bar or cake may be comparatively moist, and the best way is to
+carefully remove the outer edges and take the portions for analysis from
+the centre. In the case of a household or unmilled toilet soap, it is
+imperative that the quantities for analysis should all be weighed out as
+quickly after each other as possible.
+
+_Fatty Acids._--Five grammes of the soap are rapidly weighed into a
+small beaker, distilled water added, and the beaker heated on the water
+bath until the soap is dissolved.
+
+A slight excess of mineral acid is now added, and the whole heated until
+the separated fatty acids are perfectly clear, when they are collected
+on a tared filter paper, well washed with hot water and dried until
+constant in weight. The result multiplied by 20 gives the percentage of
+fatty acids in the sample.
+
+A quicker method, and one which gives accurate results when care is
+bestowed upon it, is to proceed in the manner described above as far as
+the decomposition with mineral acid, and to then add 5 or 10 grammes of
+stearic acid or beeswax to the contents of the beaker and heat until a
+clear layer of fatty matter collects upon the acid liquor.
+
+Cool the beaker, and when the cake is sufficiently hard, remove it
+carefully by means of a spatula and dry on a filtering paper, add the
+portions adhering to the sides of the beaker to the cake, and weigh.
+
+The weight, less the amount of stearic acid or beeswax added, multiplied
+by 20 gives the percentage of fatty acids.
+
+Care must be taken that the cake does not contain enclosed water.
+
+The results of these methods are returned as fatty acids, but are in
+reality insoluble fatty acids, the soluble fatty acids being generally
+disregarded. However in soaps made from cocoa-nut and palm-kernel oils
+(which contain an appreciable quantity of soluble fatty acids) the acid
+liquor is shaken with ether, and, after evaporation of the ethereal
+extract, the amount of fatty matter left is added to the result already
+obtained as above, or the ether method described below may be
+advantageously employed.
+
+Where the soap under examination contains mineral matter, the separated
+fatty acids may be dissolved in ether. This is best performed in an
+elongated, graduated, stoppered tube, the total volume of the ether,
+after subsidence, carefully read, and an aliquot part taken and
+evaporated to dryness in a tared flask, which is placed in the oven at
+100° C. until the weight is constant.
+
+In a complete analysis, the figure for fatty acids should be converted
+into terms of fatty anhydrides by multiplying by the factor 0.9875.
+
+In this test the resin acids contained in the soap are returned as fatty
+acids, but the former can be estimated, as described later, and deducted
+from the total.
+
+_Total Alkali._--The best method is to incinerate 5 grammes of the soap
+in a platinum dish, dissolve the residue in water, boil and filter,
+making the volume of filtrate up to 250 c.c., the solution being
+reserved for the subsequent determination of salt, silicates, and
+sulphates, as detailed below.
+
+Fifty c.c. of the solution are titrated with N/1 acid, to methyl orange,
+and the result expressed in terms of Na_{2}O.
+
+Number of c.c. required × 0.031 × 100 = per cent. Na_{2}O.
+
+The total alkali may also be estimated in the filtrate from the
+determination of fatty acids, if the acid used for decomposing the soap
+solution has been measured and its strength known, by titrating back the
+excess of acid with normal soda solution, when the difference will equal
+the amount of total alkali in the quantity taken.
+
+The total alkali is usually expressed in the case of hard soaps as
+Na_{2}O, and in soft soaps as K_{2}O.
+
+_Free caustic alkali_ is estimated by dissolving 2 grammes of the soap,
+in neutral pure alcohol, with gentle heat, filtering, well washing the
+filter with hot neutral spirit, and titrating the filtrate with N/10
+acid, to phenol-phthalein.
+
+Number of c.c. required × 0.0031 × 50 = per cent. free alkali Na_{2}O,
+as caustic.
+
+_Free Carbonated Alkali._--The residue on the filter paper from the
+above determination is washed with hot water, and the aqueous filtrate
+titrated with N/10 acid, using methyl orange as indicator. The result is
+generally expressed in terms of Na_{2}O.
+
+Number of c.c. required × 0.0031 × 50 = per cent. free alkali Na_{2}O,
+as carbonate.
+
+_Free Alkali._--Some analysts determine the alkalinity to
+phenol-phthalein of the alcoholic soap solution without filtering, and
+express it as free alkali (caustic, carbonates, or any salt having an
+alkaline reaction).
+
+_Combined Alkali._--The difference between total alkali and free alkali
+(caustic and carbonate together) represents the alkali combined with
+fatty acids. This figure may also be directly determined by titrating,
+with N/2 acid, the alcoholic solution of soap after the free caustic
+estimation, using lacmoid as indicator.
+
+The potash and soda in soaps may be separated by the method described
+for the estimation of potassium in _Pearl ash_ (page 126).
+
+The potassium platino-chloride (K_{2}PtCl_{6}) is calculated to
+potassium chloride (KCl) by using the factor 0.3052, and this figure
+deducted from the amount of mixed chlorides found, gives the amount of
+sodium chloride (NaCl), from which the sodium oxide (Na_{2}O) is
+obtained by multiplying by 0.52991.
+
+The potassium chloride (KCl) is converted into terms of potassium oxide
+(K_{2}O) by the use of the factor 0.63087.
+
+_Salt_ may be determined in 50 c.c. of the filtered aqueous extract of
+the incinerated soap, by exactly neutralising with normal acid and
+titrating with N/10 silver nitrate solution, using a neutral solution of
+potassium chromate as indicator. The final reaction is more distinctly
+observed if a little bicarbonate of soda is added to the solution.
+
+Number of c.c. required × 0.00585 × 100 = per cent. of common salt,
+NaCl.
+
+Chlorides may also be estimated by Volhard's method, the aqueous extract
+being rendered slightly acid with nitric acid, a measured volume of N/10
+silver nitrate solution added, and the excess titrated back with N/10
+ammonium thiocyanate solution, using iron alum as indicator.
+
+_Silicates._--These are estimated by evaporating 50 c.c. of the filtered
+extract from the incinerated soap, in a platinum dish with hydrochloric
+acid twice to complete dryness, heating to 150° C., adding hot water,
+and filtering through a tared filter paper.
+
+The residue is well washed, ignited, and weighed as SiO_{2}, and from
+this silica is calculated the sodium silicate.
+
+_Sulphates_ may be determined in the filtrate from the silica estimation
+by precipitation with barium chloride solution, and weighing the barium
+sulphate, after filtering, and burning, expressing the result in terms
+of Na_{2}SO_{4} by the use of the factor 0.6094.
+
+_Moisture._--This is simply estimated by taking a weighed portion in
+small shavings in a tared dish, and drying in the oven at 105° C. until
+it ceases to lose weight. From the loss thus found is calculated the
+moisture percentage.
+
+_Free or Uncombined Fat._--This is usually determined by repeated
+extraction of an aqueous solution of the soap with petroleum ether; the
+ethereal solution, after washing with water to remove traces of soap, is
+evaporated to dryness and the residue weighed.
+
+A good method, which can be recommended for employment where many
+determinations have to be performed, is to dissolve 10 grammes of soap
+in 50 c.c. neutral alcohol and titrate to phenol-phthalein with N/1
+acid. Add 3-5 drops HCl and boil to expel carbonic acid, neutralise with
+alcoholic KOH solution and add exactly 10 c.c. in excess, boil for
+fifteen minutes under a reflux condenser and titrate with N/1 acid. The
+difference between this latter figure and the amount required for a
+blank test with 10 c.c. alcoholic KOH, denotes the amount of alkali
+absorbed by the uncombined fat.
+
+_Examination of the fatty acids_ as a guide to the probable composition
+of the soap:--
+
+From the data obtained by estimating the "titre," iodine number, and
+saponification equivalent of the mixed fatty and rosin acids, and the
+rosin content, a fairly good idea of the constitution of the soap may be
+deduced.
+
+The titre, iodine number, and saponification equivalent are determined
+in exactly the same manner as described under Fats and Oils.
+
+The presence of rosin may be detected by the Liebermann-Storch reaction,
+which consists in dissolving a small quantity of the fatty acids in
+acetic anhydride, and adding to a few drops of this solution 1 drop of
+50 per cent. sulphuric acid. A violet coloration is produced with rosin
+acids. The amount of rosin may be estimated by the method devised by
+Twitchell (_Journ. Soc. Chem. Ind._, 1891, 804) which is carried out
+thus:--
+
+Two grammes of the mixed fatty and rosin acids are dissolved in 20 c.c.
+absolute alcohol, and dry hydrochloric acid gas passed through until no
+more is absorbed, the flask being kept cool by means of cold water to
+prevent the rosin acids being acted upon. The flask, after
+disconnecting, is allowed to stand one hour to ensure complete
+combination, when its contents are transferred to a Philips' beaker,
+well washed out with water so that the volume is increased about five
+times, and boiled until the acid solution is clear, a fragment of
+granulated zinc being added to prevent bumping. The heat is removed, and
+the liquid allowed to cool, when it is poured into a separator, and the
+beaker thoroughly rinsed out with ether. After shaking, the acid liquor
+is withdrawn, and the ethereal layer washed with water until free from
+acid. Fifty c.c. neutral alcohol are added, and the solution titrated
+with N/1 KOH or NaOH solution, the percentage of rosin being calculated
+from its combining weight. Twitchell suggests 346 as the combining
+weight of rosin, but 330 is a closer approximation.
+
+The method may be also carried out gravimetrically, in which case
+petroleum ether, boiling at 74° C. is used for washing out the beaker
+into the separator. The acid liquor is run off, and the petroleum ether
+layer washed first with water and then with a solution of 1/2 gramme KOH
+and 5 c.c. alcohol in 50 c.c. water, and agitated. The rosin is thus
+saponified and separated. The resinate solution is withdrawn, acidified,
+and the resin acids collected, dried and weighed.
+
+_Halphen's Reaction._--This is a special test to determine the presence
+or absence of cotton-seed oil fatty acids in mixtures. Equal parts of
+the fatty acids, amyl alcohol, and a 1 per cent. solution of sulphur in
+carbon bisulphide, are heated in a test-tube placed in a water-bath
+until effervescence ceases, then in boiling brine for one hour or longer
+when only small quantities are present. The presence of cotton-seed oil
+is denoted by a pink coloration. The reaction is rendered much more
+rapid, according to Rupp (_Z. Untersuch. Nahr. Genussm._, 1907, 13, 74),
+by heating in a stoppered flask.
+
+Other bodies which it is occasionally necessary to test for or determine
+in soap include:--
+
+_Carbolic acid._--Fifty grammes of the soap are dissolved in water and
+20 c.c. of 10 per cent. caustic potash added. The solution is treated
+with an excess of brine, the supernatant liquor separated, and the
+precipitate washed with brine, the washings being added to the liquor
+withdrawn. This is then evaporated to a small bulk, placed in a Muter's
+graduated tube, and acidified with mineral acid.
+
+The volume of separated phenols is observed and stated in percentage on
+the soap taken.
+
+Or the alkaline layer may be rendered acid and steam distilled; the
+distillate is made up to a known volume, and a portion titrated by the
+Koppeschaar method with standard bromine water.
+
+_Glycerine._--Five grammes of soap are dissolved in water, decomposed
+with dilute sulphuric acid, and the clear fatty acids filtered and
+washed. The filtrate is neutralised with barium carbonate, evaporated
+to 50 c.c., and the glycerol estimated by the bichromate method detailed
+under Crude Glycerine.
+
+_Starch_ or _gum_ may be detected by dissolving the soap in alcohol,
+filtering, and examining the residue on the filter paper. Starch is
+readily recognised by the blue coloration it gives with a solution of
+iodine in potassium iodide.
+
+_Sugars_ are tested for by means of Fehlings' solution, in the liquor
+separated from the fatty acids, after first boiling with dilute acid to
+invert any cane sugar.
+
+_Mercury_ will be revealed by a black precipitate produced when
+sulphuretted hydrogen is added to the liquor separated from the fatty
+acids, and may be estimated by filtering off this precipitate on a tared
+Gooch's crucible, which is then dried and weighed.
+
+_Borax or borates_ are tested for in the residue insoluble in alcohol.
+This is dissolved in water, rendered faintly acid with dilute
+hydrochloric acid, and a strip of turmeric paper immersed for a few
+minutes in the liquid. This is then dried in the water-oven, when if any
+boric acid compound is present, a bright reddish-pink stain is produced
+on the paper, which is turned blue on moistening with dilute alkali.
+
+The amount of the boric acid radicle may be determined by incinerating
+5-10 grammes of soap, extracting with hot dilute acid, filtering,
+neutralising this solution to methyl orange, and boiling to expel carbon
+dioxide. After cooling, sufficient pure neutralised glycerine is added
+to form one-third of the total volume, and the liquid titrated with N/2
+caustic soda solution, using phenol-phthalein as indicator. Each c.c. of
+N/2 NaOH solution corresponds to 0.031 gramme crystallised boric acid,
+H_{3}BO_{3} or 0.0477 gramme crystallised borax,
+Na_{2}B_{4}O_{7}·10H_{2}O.
+
+
+LYES.
+
+The amounts of caustic alkali (if any), carbonated alkali, and salt
+present are determined in the manner already described under Alkali and
+Alkali Salts. The glycerol content is ascertained by taking 2.5 grammes,
+adding lead subacetate solution, and filtering without increasing the
+bulk more than is absolutely necessary; the solution is concentrated to
+about 25 c.c., and the oxidation with bichromate and sulphuric acid
+conducted as described in the examination of Crude Glycerine. The
+solution, after oxidation, is made up to 250 c.c., and titrated against
+standard ferrous ammonium sulphate solution, the formula for the
+calculation being:--
+
+                                  {0.25 - 2.5}
+          Per cent. of glycerol = {       ---} × 40
+                                  {        n }
+
+where n equals the number of c.c. of oxidised lyes required to oxidise
+the ferrous ammonium sulphate solution.
+
+The estimation of actual glycerol in this is necessarily a matter of
+considerable importance, and a very large number of processes, which are
+constantly being added to, have been suggested for the purpose.
+Hitherto, however, only two methods have been generally adopted, _viz._
+the acetin and the bichromate processes. Unfortunately the results
+obtained by these do not invariably agree, the latter, which includes
+all oxidisable matter as glycerol, giving sometimes considerably higher
+results, and it has been suggested that a determination should be made
+by both methods, and the average of the two results considered the true
+value. This involves a considerable amount of time and trouble, and it
+will generally be found sufficient in a works laboratory to determine
+the glycerol by one method only in the ordinary course, reserving the
+other process for use as a check in case of dispute or doubt.
+
+_Acetin Method._--This consists in converting the glycerol into its
+ester with acetic acid, the acetic triglyceride, or triacetin being
+formed. This is then saponified with a known volume of standard alkali,
+the excess of which is titrated with acid, and the percentage of
+glycerol calculated from the amount of alkali absorbed.
+
+From 1 to 1.5 grammes of the glycerine is weighed into a conical flask
+of about 150 c.c. capacity, 7 or 8 c.c. of acetic anhydride added,
+together with about 3 grammes of anhydrous sodium acetate, and the whole
+boiled on a sand-bath under a reflux condenser for one to one and a half
+hours, after which it is allowed to cool, 50 c.c. water added, and the
+ester dissolved by shaking, and gently warming, the reflux condenser
+still being attached as the acetin is very volatile. The solution is
+then filtered from a white flocculent precipitate, which contains most
+of the impurities, into a larger conical flask, of some 500-600 c.c.
+capacity, and after cooling, rendered just neutral to phenol-phthalein
+by means of N/2 caustic soda solution, the exact point being reached
+when the solution acquires a reddish-yellow tint; 25 c.c. of a strong
+caustic soda solution is then added, and the liquid boiled for about
+fifteen minutes, the excess of alkali being titrated after cooling, with
+N/1 or N/2 hydrochloric acid. A blank experiment is carried out
+simultaneously, with another 25 c.c. of the soda solution, and the
+difference in the amounts of acid required by the two, furnishes a
+measure of the alkali required to saponify the acetin formed, and hence
+the amount of glycerol in the crude glycerine may be calculated.
+
+_Example._--1.4367 grammes crude glycerine, after treatment with acetic
+anhydride, and neutralising, was saponified with 25 c.c. of a 10 per
+cent. caustic soda solution.
+
+       The blank experiment required 111.05 c.c. N/1 hydrochloric acid.
+       Flask containing acetin  "     75.3  c.c.   "        "
+                                      -----
+                                      35.75 c.c.   "        "
+
+Hence, the acetin formed from the glycerol present in 1.4367 grammes of
+the crude glycerine required 35.75 c.c. N/1 caustic alkali for its
+saponification, so that the percentage of glycerol may be calculated
+from the following formula:--
+
+                                35.75 × 0.03067 × 100
+          Per cent. glycerol =  --------------------- = 76.3.
+                                        1.4367
+
+_Bichromate Method._--This process was originally devised by Hehner
+(_Journ. Soc. Chem. Ind._, 1889, 4-9), but the modification suggested by
+Richardson and Jaffe (_ibid._, 1898, 330) is preferred by the authors,
+and has been practised by them for several years with perfectly
+satisfactory results.
+
+Twenty-five grammes of the crude glycerine are weighed out in a beaker,
+washed into a 250 c.c. stoppered flask, and made up to the graduation
+mark with water. Twenty-five c.c. of this solution are then measured
+from a burette into a small beaker, a slight excess of basic lead
+acetate solution added to precipitate organic matter, the precipitate
+allowed to settle, and the supernatant liquid poured through a filter
+paper into another 250 c.c. flask. The precipitate is washed by
+decantation until the flask is nearly full, then transferred to the
+filter, and allowed to drain, a few drops of dilute sulphuric acid being
+added to precipitate the slight excess of basic lead acetate solution,
+and the contents of the flask made up with water to 250 c.c. This
+solution is filtered, 20 c.c. measured from a burette into a conical
+flask of about 150 c.c. capacity, 25 c.c. of a standard potassium
+bichromate solution containing 74.86 grammes bichromate per litre added,
+together with 50 c.c. of 50 per cent. sulphuric acid, and the whole
+placed in a boiling water-bath for one hour, after which it is allowed
+to cool, diluted with water to 250 c.c., and this solution run in to 20
+c.c. of a 3 per cent. ferrous ammonium sulphate solution until the
+latter is completely oxidised, as shown by no blue coloration being
+produced when one drop is brought into contact with one drop of a
+freshly prepared solution of potassium ferricyanide on a spot-plate. The
+ferrous ammonium sulphate solution is previously standardised by
+titration with a potassium bichromate solution of one-tenth the above
+strength, made by diluting 10 c.c. of the strong solution to 100 c.c.
+with water.
+
+The reaction taking place in the oxidation may be represented by the
+equation:--
+
+    3C_{3}H_{5}(OH)_{3} + 7K_{2}Cr_{2}O_{7} + 28H_{2}SO_{4} =
+        9CO_{2} + 40H_{2}O + 7K_{2}SO_{4} + 7Cr_{2}(SO_{4})_{3}.
+
+Now the strong potassium bichromate solution above mentioned is of such
+a strength that 1 c.c. will oxidise 0.01 gramme glycerine, and 20 c.c.
+of the ferrous ammonium sulphate solution should require about 10 c.c.
+of the one-tenth strength bichromate in the blank experiment. If it
+requires more or less than this, then the amount of ferrous ammonium
+sulphate solution which would require exactly 10 c.c. (corresponding to
+0.01 gramme glycerine) is calculated, and the oxidised glycerine
+solution run into this until oxidation is complete.
+
+The formula for the calculation of the percentage of glycerol then
+becomes:--
+
+                                  {0.25 -(250 × 0.01)}
+          Per cent. of glycerol = {       ---------- } × 500,
+                                  {            n     }
+
+where n equals the number of c.c. of oxidised glycerine solution
+required to oxidise the ferrous ammonium sulphate solution.
+
+Example:--
+
+In the blank experiment 20 c.c. ferrous ammonium sulphate solution
+required 9.8 c.c. one-tenth strength bichromate solution, so that 20.4
+c.c. ferrous solution would equal 10 c.c. bichromate.
+
+20.4 c.c. ferrous solution required 27.8 c.c. of oxidised glycerine
+solution before it ceased to give a blue coloration with potassium
+ferricyanide.
+                                        {0.25 - (250 × 0.01)}
+    Therefore, per cent. of glycerol = {       ------------} × 500
+                                       {           27.8    }
+
+                                     = 80.04 per cent.
+
+Other methods have been suggested for the preliminary purification,
+_e.g._, silver oxide, silver carbonate and lead subacetate, and copper
+sulphate and caustic potash, but the lead subacetate alone with care
+gives satisfactory results.
+
+Other determinations include those of specific gravity, alkalinity,
+proportion of salts and chloride, and tests for metals, arsenic, sulphur
+compounds, sugar, and fatty acids.
+
+_Specific gravity_ is determined at 15° C., and may be taken in specific
+gravity bottle, or with a Westphal balance or hydrometer It usually
+ranges from 1.3 to 1.31.
+
+_Alkalinity_, which is usually sodium carbonate, and may be somewhat
+considerable if the soap has been grained with caustic alkali, is
+determined after dilution with water by titrating with N/2 acid, using
+methyl orange as indicator.
+
+_Salts._--These may be determined by gently incinerating 5-6 grammes of
+the glycerine, extracting the carbonaceous mass with distilled water,
+filtering, and evaporating the filtrate on the water bath. The dried
+residue represents the salts in the weight taken.
+
+_Chloride of sodium_ (common salt) may be estimated by dissolving the
+total salts in water, adding potassium chromate, and titrating with N/10
+silver nitrate solution.
+
+_Copper_, _lead_, _iron_, _magnesium_, and _calcium_ may also be tested
+for in the salts, by ordinary reactions.
+
+_Arsenic_ is best tested for by the Gutzeit method. About 5 c.c. is
+placed in a test-tube, a few fragments of granulated zinc free from
+arsenic, and 10 c.c. dilute hydrochloric acid added, and the mouth of
+the tube covered with a small filter paper, moistened three successive
+times with an alcoholic solution of mercury bichloride and dried. After
+thirty minutes the filter paper is examined, when a yellow stain will be
+observed if arsenic is present.
+
+_Sulphates._--These may be precipitated with barium chloride in acid
+solution, in the usual way, dried, ignited, and weighed.
+
+_Sulphites_ give with barium chloride a precipitate soluble in
+hydrochloric acid. If the precipitate is well washed with hot water, and
+a few drops of iodine solution together with starch paste added, the
+presence of sulphites is proved by the gradual disappearance of the blue
+starch-iodine compound first formed.
+
+_Thiosulphates_ are detected by precipitating any sulphite and sulphate
+with barium chloride, filtering, acidifying, and adding a few drops of
+potassium permanganate solution, when in the presence of a mere trace of
+thiosulphate, the solution becomes cloudy.
+
+_Sulphides._--Lewkowitsch recommends testing for these by replacing the
+mercury bichloride with lead acetate paper in the Gutzeit arsenic test.
+Any sulphide causes a blackening of the lead acetate paper.
+
+_Sugars_ may be tested for both before and after inversion, by boiling
+with Fehlings' solution, when no reduction should take place, if pure.
+
+_Fatty acids_ are detected by the turbidity they produce when the
+diluted glycerine is acidified.
+
+
+
+
+CHAPTER XI.
+
+STATISTICS OF THE SOAP INDUSTRY.
+
+
+Until the year 1853 the amount of soap produced annually in this country
+was readily obtainable from the official returns collected for the
+purpose of levying the duty, and the following figures, taken at
+intervals of ten years for the half century prior to that date, show the
+steady development of the industry during that period:--
+
+ _______________________________________________________________
+|       |               |           |           |               |
+| Year. | Manufactured. | Consumed. | Exported. | Duty per Ton. |
+|_______|_______________|___________|___________|_______________|
+|       |               |           |           |               |
+|       |     Cwts.     |   Cwts.   |   Cwts.   |      £        |
+| 1801  |     509,980   |   482,140 |   26,790  |      21       |
+| 1811  |     678,570   |   651,780 |   26,790  |      21       |
+| 1821  |     875,000   |   839,290 |   35,710  |      28       |
+| 1831  |   1,098,210   |   955,360 |  142,850  |      28       |
+| 1841  |   1,776,790   | 1,517,860 |  258,930  |      14       |
+| 1851  |   1,937,500   | 1,741,070 |  196,430  |      14       |
+|_______|_______________|___________|___________|_______________|
+
+Since the repeal of the soap duty, the revenue from which had reached
+about £1,000,000 per annum, no accurate means of gauging the production
+exists, but it is estimated that it has nearly quadrupled during the
+last fifty-five years, being now some 7,000,000 or 8,000,000 cwt. per
+annum.
+
+The number of soap manufacturers in the United Kingdom is nearly 300,
+and the amount of capital invested in the industry is roughly estimated
+to approach £20,000,000 sterling.
+
+Official figures are still available for the amount and value of soap
+annually imported and exported to and from the United Kingdom, the
+returns for the last eight years being:--
+
+_Imports._
+_________________________________________________________________________
+|       |                     |                     |                     |
+|       |       Household.    |         Toilet.     |       Total.[13]    |
+|       |_____________________|_____________________|_____________________|
+| Year. |           |         |           |         |           |         |
+|       | Quantity. |  Value. | Quantity. |  Value. | Quantity. |  Value  |
+|_______|___________|_________|___________|_________|___________|_________|
+|       |           |         |           |         |           |         |
+|       |   Cwts.   |    £    |   Cwts.   |    £    |   Cwts.   |    £    |
+|  1900 |    ...    |   ...   |    ...    |   ...   |  191,233  | 244,345 |
+|  1901 |    ...    |   ...   |    ...    |   ...   |  302,555  | 315,026 |
+|  1902 |    ...    |   ...   |    ...    |   ...   |  361,851  | 429,300 |
+|  1903 |  273,542  | 284,376 |  25,749   |  98,032 |  462,959  | 499,407 |
+|  1904 |  254,425  | 268,408 |  17,962   |  81,162 |  383,122  | 438,966 |
+|  1905 |  274,238  | 279,044 |  19,631   |  98,507 |  473,067  | 500,430 |
+|  1906 |  309,975  | 311,114 |  18,554   | 101,243 |  399,070  | 468,086 |
+|  1907 |  228,035  | 263,965 |  18,244   |  99,432 |  504,710  | 545,385 |
+|_______|___________|_________|___________|_________|___________|_________|
+
+Household and toilet soaps were not given separately prior to 1903.
+
+The imports during the last three years for which complete figures are
+obtainable, came from the following sources:--
+
+_Household Soap._
+ ______________________________________________________________
+|                                |         |         |         |
+|                                |   1904. |   1905. |   1906. |
+|________________________________|_________|_________|_________|
+|                                |         |         |         |
+|                                |    £    |    £    |    £    |
+| From Netherlands               |   4,315 |   3,620 |   3,368 |
+|      France                    |  14,339 |  17,783 |  24,747 |
+|      Italy                     |  24,209 |  18,129 |  32,972 |
+|      United States             | 218,740 | 235,612 | 242,294 |
+|      Other Foreign Countries   |   6,785 |   3,873 |   7,448 |
+|                                |_________|_________|_________|
+|                                |         |         |         |
+| Total from Foreign Countries   | 268,388 | 279,017 | 310,829 |
+| Total from British Possessions |      20 |      27 |     285 |
+|                                |_________|_________|_________|
+|                                |         |         |         |
+| Total                          | 268,408 | 279,044 | 311,114 |
+|________________________________|_________|_________|_________|
+
+
+_Toilet Soap._
+ ______________________________________________________________
+|                                |         |         |         |
+|                                |   1904. |   1905. |   1906. |
+|________________________________|_________|_________|_________|
+|                                |         |         |         |
+|                                |    £    |    £    |    £    |
+|  From Germany                  |   3,509 |   3,516 |   3,001 |
+|       Netherlands              |   5,937 |   5,773 |   5,919 |
+|       Belgium                  |   1,568 |   1,861 |   3,145 |
+|       France                   |   7,120 |   7,633 |   5,794 |
+|       Italy                    |   1,176 |     255 |   1,233 |
+|       United States            |  59,863 |  74,516 |  78,382 |
+|       Other Foreign Countries  |     166 |     147 |     196 |
+|                                |_________|_________|_________|
+|                                |         |         |         |
+| Total from Foreign Countries   |  79,339 |  93,701 |  97,670 |
+| Total from British Possessions |   1,823 |   4,411 |   3,225 |
+|                                |_________|_________|_________|
+|                                |         |         |         |
+| Total                          |  81,162 |  98,112 | 100,895 |
+|________________________________|_________|_________|_________|
+
+
+_Exports._
+
+The exports from the United Kingdom during the past eight years have
+been as follows:--
+
+ _________________________________________________________________________
+|     |                       |                    |                      |
+|     |        Household.     |       Toilet.      |       Total.[14]     |
+|     |_______________________|____________________|______________________|
+|Year.|           |           |          |         |           |          |
+|     | Quantity. |   Value.  | Quantity.|  Value. | Quantity. |  Value.  |
+|_____|___________|___________|__________|_________|___________|__________|
+|     |           |           |          |         |           |          |
+|     |   Cwts.   |     £     |   Cwts.  |    £    |   Cwts.   |     £    |
+| 1900|    ...    |    ...    |    ...   |   ...   |   874,214 |   939,510|
+| 1901|    ...    |    ...    |    ...   |   ...   |   947,485 |   999,524|
+| 1902|    ...    |    ...    |    ...   |   ...   | 1,051,624 | 1,126,657|
+| 1903|   998,995 |   900,814 |   38,372 | 217,928 | 1,057,164 | 1,143,661|
+| 1904| 1,049,022 |   955,774 |   40,406 | 228,574 | 1,108,174 | 1,208,712|
+| 1905| 1,167,976 | 1,013,837 |   43,837 | 248,425 | 1,230,310 | 1,284,727|
+| 1906| 1,131,294 | 1,009,653 |   46,364 | 261,186 | 1,210,598 | 1,309,556|
+| 1907| 1,114,624 | 1,095,170 |   50,655 | 280,186 | 1,240,805 | 1,459,113|
+|_____|___________|___________|__________|_________|___________|__________|
+
+Household and toilet soaps were not given separately prior to 1903.
+
+The exports for the last three years for which complete figures are
+available, consisted of the following:--
+
+_Household Soap._
+
++----------------------------------------+----------+----------+-----------+
+|                                        |   1904.  |   1905.  |    1906.  |
++----------------------------------------+----------+----------+-----------+
+|                                        |    £     |    £     |     £     |
+|To Sweden                               |   3,027  |   2,911  |    3,677  |
+|   Norway                               |   4,173  |   3,921  |    6,005  |
+|   Netherlands                          |  39,420  |  41,197  |   48,601  |
+|   Dutch Possessions in the Indian Seas |   8,586  |  10,293  |    7,746  |
+|   Belgium                              |  73,996  |  51,583  |    7,729  |
+|   France                               |  11,741  |  12,222  |   22,907  |
+|   Portuguese East Africa               |  28,987  |  42,981  |   40,478  |
+|   Canary Islands                       |  24,763  |  27,864  |   27,579  |
+|   Italy                                |   2,842  |   3,187  |    3,962  |
+|   Turkey                               |   6,974  |   7,858  |    5,897  |
+|   Egypt                                |  12,110  |   9,467  |   12,035  |
+|   China (exclusive of Hong-Kong and    |          |          |           |
+|     Macao)                             |  49,235  | 114,156  |   89,169  |
+|   United States                        |   3,885  |   1,975  |    3,924  |
+|   Columbia                             |   3,601  |     501  |    1,364  |
+|   Ecuador                              |   3,075  |   3,096  |    6,861  |
+|   Chili                                |   5,972  |   4,865  |    9,203  |
+|   Brazil                               |  35,197  |  28,198  |   31,726  |
+|   Argentine Republic                   |   7,802  |   8,954  |   13,084  |
+|   Other Foreign Countries              |  40,058  |  53,914  |   77,687  |
+|                                        +----------+----------+-----------+
+|Total to Foreign Countries              | 365,444  | 429,143  |  419,634  |
+|                                        +---------------------------------+
+|To Channel Islands                      |   5,301  |   8,328  |    7,968  |
+|   Gibraltar                            |  13,272  |  13,868  |   12,661  |
+|   British West Africa--                |          |          |           |
+|     Gold Coast                         |   22,598 |   18,513 |   23,423  |
+|     Lagos                              |    7,751 |    8,032 |    9,518  |
+|     Nigerian Protectorate              |   14,942 |   15,299 |   20,951  |
+|   Cape of Good Hope                    |  158,517 |  143,750 |  136,388  |
+|   Natal                                |   74,848 |   71,874 |   46,771  |
+|   British India                        |          |          |           |
+|     Bombay (including Kurachi)         |   59,406 |   68,945 |   77,867  |
+|     Madras                             |    6,364 |    6,697 |   10,355  |
+|     Bengal, Eastern Bengal and Assam.  |   26,534 |   23,087 |   22,648  |
+|     Burmah                             |   26,389 |   35,727 |   37,103  |
+|   Straits Settlements and Dependencies |   26,516 |   32,214 |   39,749  |
+|   Hong-Kong                            |   14,119 |   15,153 |   15,685  |
+|   British West India Islands           |   74,069 |   58,881 |   67,331  |
+|   British Guiana                       |   12,661 |   12,023 |   11,557  |
+|   Other British Possessions            |   47,043 |   52,303 |   50,044  |
+|                                        +----------+----------+-----------+
+|Total to British Possessions            |  590,330 |  584,694 |  590,019  |
+|                                        +----------+----------+-----------+
+|                 Total                  |  955,774 |1,013,837 |1,009,653  |
+|----------------------------------------+---------+-----------+-----------+
+
+_Toilet Soap._
+ ________________________________________________________________
+|                                  |         |         |         |
+|                                  |   1904. |   1905. |   1906. |
+|__________________________________|_________|_________|_________|
+|                                  |         |         |         |
+|                                  |    £    |    £    |    £    |
+| To Germany                       |   5,051 |   6,322 |   6,620 |
+|    Belgium                       |   3,730 |   3,265 |   3,355 |
+|    France                        |   7,903 |   8,988 |   9,324 |
+|    Portuguese East Africa        |   2,215 |   3,973 |   4,658 |
+|    Egypt                         |   2,302 |   3,350 |   3,525 |
+|    China (exclusive of           |         |         |         |
+|      Hong-Kong and Macao)        |   3,096 |   3,115 |   3,645 |
+|    Japan (including Formosa)     |   3,300 |   4,649 |   3,382 |
+|    United States                 |  50,043 |  50,668 |  52,124 |
+|    Brazil                        |   1,879 |   2,241 |   2,292 |
+|    Other Foreign Countries       |  22,002 |  26,081 |  29,214 |
+|                                  |_________|_________|_________|
+|                                  |         |         |         |
+| Total to Foreign Countries       | 101,521 | 112,652 | 118,139 |
+|                                  |_________|_________|_________|
+|                                  |         |         |         |
+| To Cape of Good Hope             |  14,094 |  14,815 |  14,988 |
+|    Natal                         |   8,897 |  11,913 |   7,280 |
+|    British India--               |         |         |         |
+|      Bombay (including Kurachi)  |  24,665 |  24,672 |  28,316 |
+|      Madras                      |   4,333 |   5,851 |   6,624 |
+|      Bengal, Eastern Bengal      |         |         |         |
+|        and Assam                 |  14,129 |  16,021 |  15,969 |
+|      Burmah                      |   3,299 |   3,400 |   4,667 |
+|    Straits Settlements and       |         |         |         |
+|      Dependencies                |   3,590 |   5,092 |   4,798 |
+|    Ceylon and Dependencies       |  12,210 |  11,118 |  12,854 |
+|    Australia--                   |         |         |         |
+|      Western Australia           |   1,549 |   1,394 |   1,137 |
+|      South Australia, (including |         |         |         |
+|        Northern Territory)       |     895 |     644 |     637 |
+|      Victoria                    |  11,989 |  13,614 |  12,774 |
+|      New South Wales             |   3,920 |   4,278 |   4,139 |
+|      Queensland                  |     957 |   1,097 |   1,108 |
+|      Tasmania                    |     482 |     315 |     547 |
+|    New Zealand                   |   5,093 |   4,498 |   5,503 |
+|    Canada                        |   6,382 |   6,196 |   8,185 |
+|    Other British Possessions     |  11,069 |  10,855 |  13,521 |
+|                                  |_________|_________|_________|
+|                                  |         |         |         |
+| Total to British Possessions     | 127,053 | 135,773 | 143,047 |
+|                                  |_________|_________|_________|
+|                                  |         |         |         |
+|                  Total           | 228,574 | 248,425 | 261,186 |
+|__________________________________|_________|_________|_________|
+
+The following statistics extracted from official consular reports, etc.,
+show the extent of the soap industry in other parts of the world.
+
+_United States._--According to the _Oil, Paint and Drug Report_ the
+total production of soap in the United States during 1905, exclusive of
+soap products to the value of $1,437,118 made in establishments engaged
+primarily in the manufacture of other products, reached a value of
+$68,274,700, made up in the following manner:--
+
++------------------------------------+--------------+-------------+
+|                                    |   Quantity.  |     Value.  |
++------------------------------------+--------------+-------------+
+|                                    |      Lbs.    |       $     |
+|Hard soaps                          |      ...     |  56,878,486 |
+|Tallow soap                         | 846,753,798  |  32,610,850 |
+|Olein soap                          |  29,363,376  |   1,363,636 |
+|Foots soap                          |  85,000,133  |   3,090,312 |
+|Toilet soaps, including medicated,  |              |             |
+|  shaving, and other special soaps  | 130,225,417  |   9,607,276 |
+|Powdered soaps, sold as such        | 120,624,968  |   4,358,682 |
+|All other soaps                     | 143,390,957  |   6,097,670 |
+|Soft soap                           |  33,613,416  |     667,064 |
+|Special soap articles               |     ...      |     554,881 |
++------------------------------------+--------------+-------------+
+
+_France_.--This country exported common soap during 1906 to the value of
+£556,000, or £8,000 more than in 1905.
+
+The chief centre of the soap industry is Marseilles, which, with about
+fifty soap factories, produces annually some 3,000,000 cwts.
+
+_Germany_ imported in 1905 soap and perfumery to the value of £3,032,
+that exported amounting to £15,364.
+
+In Saxony there are eighty soap factories.
+
+_Russia._--There are fifty large soap factories in Russia, the annual
+output from which is about 2,250,000 cwt.
+
+_Roumania._--This country possesses about 230 small and eighteen large
+soap and candle factories, most of which produce only common soap, there
+being only one firm--in Bucharest--which makes milled soaps.
+
+_Denmark._--In this country there are some 200 small soap factories.
+
+_Australia._--According to a Board of Trade report, there were
+ninety-eight soap and candle factories in Australia in 1905, employing
+1,568 hands, and producing 495,036 cwt. of soap.
+
+_Queensland._--In 1905 this country contained twenty-one soap and candle
+works, in which 142 hands were employed, and having an output valued at
+£86,324.
+
+_Hong-Kong._--There are about twenty-four soap factories on this island.
+
+_Japan._--A Swiss consular report states that in Japan there are now
+some fifty soap works, producing about 15,000,000 tablets monthly.
+
+_Fiji Islands._--These possess only one soap factory, the output from
+which is 9 cwt. daily.
+
+The following table, compiled from various consular and other official
+returns, shows the quantity and value of soap imported into different
+countries and places during the years 1905-7:--
+
+ _______________________________________________________________________________
+                  |                   |                    |
+                  |     Household.    |        Toilet.     |       Total.
+                  |___________________|____________________|____________________
+ Place and Date.  |          |        |         |          |         |
+                  | Quantity.| Value. |Quantity.|  Value.  |Quantity.|  Value.
+__________________|__________|________|_________|__________|_________|__________
+                  |          |        |         |          |         |
+_Europe_--        |          |        |         |          |         |
+ Cyprus, 1905     |   ...    |  ...   |   ...   |   ...    |   ...   |    £9,983
+ Iceland, 1906    |   ...    |  ...   |   ...   |   ...    |   ...   |    £6,423
+ Switzerland,     |   ...    |  ...   |   ...   |   ...    |1,702,800|     ...
+   1906           |          |        |         |          |  kilos. |     ...
+ Turkey           |   ...    |  ...   |   ...   |   ...    |   About |     ...
+                  |          |        |         |          |1,800,000|     ...
+                  |          |        |         |          | lb. per |
+                  |          |        |         |          |  annum  |
+_Africa_--        |          |        |         |          |         |
+  Algeria, 1906   |  13,609  |£228,640|   ...   |   ...    |    ...  |     ...
+                  |   tons   |        |         |          |         |
+  Cape Colony,    |15,897,800|£145,000| 427,600 |   ...    |    ...  |     ...
+    1906          |    lb.   |        |   lb.   |          |         |
+  Gold Coast, 1906|   ...    |  ...   |    ...  |   ...    |    ...  |   £23,987
+  Lourenço,       | 357,638  | £4,293 |  36,000 |  £2,195  |    ...  |     ...
+     Marques, 1906|    lb.   |        |    lb.  |          |         |
+  Natal, 1906     |4,263,000 |  ...   |   9,870 |   ...    |    ...  |     ...
+                  |   lb.    |        |    lb.  |          |         |
+  Orange River    | 2,382,000| £23,000|1,748 lb.|   ...    |    ...  |     ...
+    Colony, 1906  |    lb.   |        |         |          |         |
+  Pemba, 1905     |   ...    |  ...   |   ...   |   ...    |    ...  |    £1,092
+  Rhodesia, 1906  |  257,600 |  ...   |2,909 lb.|   ...    |    ...  |     ...
+                  |     lb.  |        |         |          |         |
+  Southern        |          |        |         |          |         |
+     Nigeria, 1905|   ...    |  ...   |   ...   |   ...    |    ...  |   £11,990
+  Tangier         |   ...    |  ...   |   ...   |   ...    |    ...  |    £4,554
+  Transvaal, 1906 | 4,407,000| £81,000| 202,200 |   ...    |    ...  |     ...
+                  |    lb.   |        |    lb.  |          |         |
+  Tripoli, 1905   |   ...    |  ...   |   ...   |   ...    |    ...  |    £6,080
+  Tunis, 1906     |   ...    |  ...   |   ...   |   ...    |  1,539  |   £23,727
+                  |          |        |         |          |   tons  |
+  Zanzibar, 1906  |   ...    |  ...   |   ...   |   ...    |    ...  |    £6,102
+                  |          |        |         |          |         |
+_America_--       |          |        |         |          |         |
+  Bahia, 1906     |   ...    |  ...   |   ...   |   ...    |   1,031 |   606,046
+                  |          |        |         |          |    tons |   milreis
+  Brazil, 1906    |   ...    |  ...   |   ...   |   ...    |   1,782 |     ...
+                  |          |        |         |          |    tons |
+                  |          |        |         |          |from U.K.|
+  British Guiana, |          |        |         |          |         |
+    1906-7        |   ...    |  ...   |   ...   |   ...    |   ...   |   £13,733
+  Canada, 1906-7  |   ...    |  ...   |   ...   |   ...    |   ...   |  $600,999
+  Columbia, 1906--|          |        |         |          |         |
+    Cartagena     |   ...    |  ...   |   ...   |   ...    |  65,991 |     ...
+                  |          |        |         |          |   tons  |
+    Barranquilla  |   ...    |  ...   |   ...   |   ...    | 814,671 |   $14,712
+                  |          |        |         |          |    lb.  |
+  Costa Rica, 1906|   ...    |  ...   |   ...   |   ...    |   ...   |    £1,269
+                  |          |        |         |          |         | from U.K.
+                  |          |        |         |          |         |
+  Ecuador, 1904   |   ...    |  ...   |   ...   |   ...    | 759,034 |     ...
+                  |          |        |         |          |  kilos. |
+  Granada, 1905   |   ...    |  ...   |   ...   |   ...    |   ...   |    £3,867
+  Guatemala, 1906 |   ...    |  £900  |   ...   |   ...    |   ...   |     ...
+  Martinique, 1906|  693,269 | £6,955 |   ...   |   ...    |   ...   |     ...
+                  |   kilos. |        |         |          |         |
+  Mexico, 1905-6  |   ...    | £5,982 |   ...   |   ...    |   ...   |     ...
+  San Domingo,    |   ...    |  ...   |   ...   |   ...    | 754,587 |
+    1906          |          |        |         |          |    lb.  |     ...
+  St. Vincent,    |          |        |         |          |         |
+    1905-6        |   ...    |  ...   |   ...   |   ...    |   ...   |    £1,375
+  Surinam, 1906   |   ...    | £3,905 |   1,142 |   ...    |   ...   |     ...
+                  |          |        |    tons |          |         |
+  Trinidad, 1906-7|   ...    |  ...   |   ...   |   ...    |   ...   |   £29,967
+  United States,  |          |        |         |          |         |
+    1905          |   ...    |$399,797|   ...   |$1,071,446|   ...   |$1,471,243
+__________________|__________|________|_________|__________|_________|____________
+
+________________________________________________________________________________
+                  |                  |                 |
+                  |    Household.    |      Toilet.    |       Total
+                  |__________________|_________________|________________________
+ Place and Date.  |          |       | Quan- |         |  Quan- |
+                  | Quantity.| Value.| tity. |  Value. |  tity  |   Value.
+__________________|__________|_______|_______|_________|________|_______________
+                  |          |       |       |         |        |
+_Asia_--          |          |       |       |         |        |
+  Ceylon, 1906    |    ...   |  ...  |  ...  |   ...   |  ...   | 423,700 rupees
+  China, 1906     |    ...   |  ...  |  ...  |   ...   |  ...   |£216,042
+  Hangchow, 1906  |    ...   |  ...  |  ...  |   ...   |  ...   |  £5,888
+  India, 1906-7   |    ...   |   ... |  ...  |   ...   | 183,998| £215,210
+                  |          |       |       |         |   cwts.|
+  Kiungchow, 1905 |    ...   |  £575 |  ...  |    ...  |  ...   |  ...
+  Shanghai, 1905  |    ...   |   ... |  ...  |    ...  |  ...   | £93,256
+  Smyrna, 1906    |    ...   |   ... |  ...  |    ...  |261 tons|  ...
+                  |          |       |       |         |        |
+_Australasia_--   |          |       |       |         |        |
+  Australia, 1906 |    ...   |  ...  |891,117| £65,840 |  ...   |  ...
+                  |          |       |   lb. |         |        |
+  Fiji, 1906      |    ...   |  ...  |  ...  |  ...    |  ...   |  £1,760
+  New Zealand,    |          |       |       |         |        |
+    1905          |    ...   |  ...  |  ...  |  ...    |  ...   | £36,843
+  Philippine      |          |       |       |         |        |
+    Islands, 1905 |    ...   |  ...  |  ...  |   ...   |  ...   |  £9,137
+__________________|__________|_______|_______|_________|________|________
+
+
+_Exports._
+________________________________________________________________________________
+                   |                   |                  |
+                   |     Household.    |       Toilet.    |      Total
+                   |___________________|__________________|_____________________
+  Place and Date.  |          |        | Quan- |          | Quan- |
+                   | Quantity.| Value. | tity. |  Value.  | tity. |  Value
+___________________|__________|________|_______|__________|_______|_____________
+                   |          |        |       |          |       |
+_Europe_--         |          |        |       |          |       |
+  Candia, Crete,   |   ...    |   ...  |  ...  |    ...   | 2,200 |   £34,000
+    1906           |          |        |       |          | tons. |
+  Greece           |   ...    |   ...  |  ...  |    ...   |  ...  |    About
+                   |          |        |       |          |       |  500,000 Fr.
+                   |          |        |       |          |       |  per annum.
+  Italy, 1907      | 3,992,800| £95,840|  ...  |    ...   |  ...  |    ...
+                   |   kilos. |        |       |          |       |
+  Leghorn, 1906    |    ...   |   ...  |  ...  |    ...   | 1,521 |   £37,065
+                   |          |        |       |          | tons. |
+  Spain, 1905      | 4,750,996| £98,840|  ...  |    ...   |  ...  |     ...
+                   |   kilos. |        |       |          |       |
+  Switzerland, 1906|    ...   |   ...  |  ...  |    ...   | 77,300|     ...
+                   |          |        |       |          | kilos.|
+_Africa_--         |          |        |       |          |       |
+  Cape Colony, 1906|  200 lb. |   ...  |  ...  |    ...   |  ...  |     ...
+  Natal, 1906      |75,225 lb.|   ...  |  ...  |    ...   |  ...  |     ...
+  Seychelles, 1906 |    ...   |   ...  |  ...  |    ...   |419,329|   129,590
+                   |          |        |       |          | kilos.|     Rs.
+_America_--        |          |        |       |          |       |
+  New Orleans,     |    ...   |   ...  |  ...  |    ...   |  ...  |    £55,534
+    1906           |          |        |       |          |       |
+  Perambuco, 1906  |    ...   |   ...  |  ...  |    ...   | 3,582 |1,087,797,150
+                   |          |        |       |          |  tons.|     rei
+  United States,   |44,110,949|   ...  |  ...  |$1,042,185|  ...  |     ...
+    1905           |    lb.   |        |       |          |       |
+                   |          |        |       |          |       |
+_Asia_--           |          |        |       |          |       |
+  Japan, 1906      |    ...   |   ...  |  ...  |    ...   |  ...  |   £83,877
+  Smyrna, 1906     |    ...   |   ...  |  ...  |    ...   |  322  |     ...
+                   |          |        |       |          | tons. |
+___________________|__________|________|_______|__________|_______|_____________
+
+FOOTNOTES:
+
+[13] Including soap powder and soap stock.
+
+[14] Including soap powder and soap stock.
+
+
+
+
+APPENDIX A.
+
+COMPARISON OF DEGREES, TWADDELL AND BAUMÉ, WITH ACTUAL DENSITIES.
+
+
+ _______________________________________________
+|     |      |          |     |      |          |
+| Tw. |   B. | Density. | Tw. |   B. | Density. |
+|_____|______|__________|_____|______|__________|
+|     |      |          |     |      |          |
+|   0 |    0 |   1.000  |  44 | 26.0 |   1.220  |
+|   1 |  0.7 |   1.005  |  45 | 26.4 |   1.225  |
+|   2 |  1.4 |   1.010  |  46 | 26.9 |   1.230  |
+|   3 |  2.1 |   1.015  |  47 | 27.4 |   1.235  |
+|   4 |  2.7 |   1.020  |  48 | 27.9 |   1.240  |
+|   5 |  3.4 |   1.025  |  49 | 28.4 |   1.245  |
+|   6 |  4.1 |   1.030  |  50 | 28.8 |   1.250  |
+|   7 |  4.7 |   1.035  |  51 | 29.3 |   1.255  |
+|   8 |  5.4 |   1.040  |  52 | 29.7 |   1.260  |
+|   9 |  6.0 |   1.045  |  53 | 30.2 |   1.265  |
+|  10 |  6.7 |   1.050  |  54 | 30.6 |   1.270  |
+|  11 |  7.4 |   1.055  |  55 | 31.1 |   1.275  |
+|  12 |  8.0 |   1.060  |  56 | 31.5 |   1.280  |
+|  13 |  8.7 |   1.065  |  57 | 32.0 |   1.285  |
+|  14 |  9.4 |   1.070  |  58 | 32.4 |   1.290  |
+|  15 | 10.0 |   1.075  |  59 | 32.8 |   1.295  |
+|  16 | 10.6 |   1.080  |  60 | 33.3 |   1.300  |
+|  17 | 11.2 |   1.085  |  61 | 33.7 |   1.305  |
+|  18 | 11.9 |   1.090  |  62 | 34.2 |   1.310  |
+|  19 | 12.4 |   1.095  |  63 | 34.6 |   1.315  |
+|  20 | 13.0 |   1.100  |  64 | 35.0 |   1.320  |
+|  21 | 13.6 |   1.105  |  65 | 35.4 |   1.325  |
+|  22 | 14.2 |   1.110  |  66 | 35.8 |   1.330  |
+|  23 | 14.9 |   1.115  |  67 | 36.2 |   1.335  |
+|  24 | 15.4 |   1.120  |  68 | 36.6 |   1.340  |
+|  25 | 16.0 |   1.125  |  69 | 37.0 |   1.345  |
+|  26 | 16.5 |   1.130  |  70 | 37.4 |   1.350  |
+|  27 | 17.1 |   1.135  |  71 | 37.8 |   1.355  |
+|  28 | 17.7 |   1.140  |  72 | 38.2 |   1.360  |
+|  29 | 18.3 |   1.145  |  73 | 38.6 |   1.365  |
+|  30 | 18.8 |   1.150  |  74 | 39.0 |   1.370  |
+|  31 | 19.3 |   1.155  |  75 | 39.4 |   1.375  |
+|  32 | 19.8 |   1.160  |  76 | 39.8 |   1.380  |
+|  33 | 20.3 |   1.165  |  77 | 40.1 |   1.385  |
+|  34 | 20.9 |   1.170  |  78 | 40.5 |   1.390  |
+|  35 | 21.4 |   1.175  |  79 | 40.8 |   1.395  |
+|  36 | 22.0 |   1.180  |  80 | 41.2 |   1.400  |
+|  37 | 22.5 |   1.185  |  81 | 41.6 |   1.405  |
+|  38 | 23.0 |   1.190  |  82 | 42.0 |   1.410  |
+|  39 | 23.5 |   1.195  |  83 | 42.3 |   1.415  |
+|  40 | 24.0 |   1.200  |  84 | 42.7 |   1.420  |
+|  41 | 24.5 |   1.205  |  85 | 43.1 |   1.425  |
+|  42 | 25.0 |   1.210  |  86 | 43.4 |   1.430  |
+|  43 | 25.5 |   1.215  |  87 | 48.8 |   1.435  |
+|_____|______|__________|_____|______|__________|
+
+ _______________________________________________
+|     |      |          |     |      |          |
+| Tw. |   B. | Density. | Tw. |   B. | Density. |
+|_____|______|__________|_____|______|__________|
+|     |      |          |     |      |          |
+|  88 | 44.1 |   1.440  | 131 | 57.1 |   1.655  |
+|  89 | 44.4 |   1.445  | 132 | 57.4 |   1.660  |
+|  90 | 44.8 |   1.450  | 133 | 57.7 |   1.665  |
+|  91 | 45.1 |   1.455  | 134 | 57.9 |   1.670  |
+|  92 | 45.4 |   1.460  | 135 | 58.2 |   1.675  |
+|  93 | 45.8 |   1.465  | 136 | 58.4 |   1.680  |
+|  94 | 46.1 |   1.470  | 137 | 58.7 |   1.685  |
+|  95 | 46.4 |   1.475  | 138 | 58.9 |   1.690  |
+|  96 | 46.8 |   1.480  | 139 | 59.2 |   1.695  |
+|  97 | 47.1 |   1.485  | 140 | 59.5 |   1.700  |
+|  98 | 47.4 |   1.490  | 141 | 59.7 |   1.705  |
+|  99 | 47.8 |   1.495  | 142 | 60.0 |   1.710  |
+| 100 | 48.1 |   1.500  | 143 | 60.2 |   1.715  |
+| 101 | 48.4 |   1.505  | 144 | 60.4 |   1.720  |
+| 102 | 48.7 |   1.510  | 145 | 60.6 |   1.725  |
+| 103 | 49.0 |   1.515  | 146 | 60.9 |   1.730  |
+| 104 | 49.4 |   1.520  | 147 | 61.1 |   1.735  |
+| 105 | 49.7 |   1.525  | 148 | 61.4 |   1.740  |
+| 106 | 50.0 |   1.530  | 149 | 61.6 |   1.745  |
+| 107 | 50.3 |   1.535  | 150 | 61.8 |   1.750  |
+| 108 | 50.6 |   1.540  | 151 | 62.1 |   1.755  |
+| 109 | 50.9 |   1.545  | 152 | 62.3 |   1.760  |
+| 110 | 51.2 |   1.550  | 153 | 62.5 |   1.765  |
+| 111 | 51.5 |   1.555  | 154 | 62.8 |   1.770  |
+| 112 | 51.8 |   1.560  | 155 | 63.0 |   1.775  |
+| 113 | 52.1 |   1.565  | 156 | 63.2 |   1.780  |
+| 114 | 52.4 |   1.570  | 157 | 63.5 |   1.785  |
+| 115 | 52.7 |   1.575  | 158 | 63.7 |   1.790  |
+| 116 | 53.0 |   1.580  | 159 | 64.0 |   1.795  |
+| 117 | 53.3 |   1.585  | 160 | 64.2 |   1.800  |
+| 118 | 53.6 |   1.590  | 161 | 64.4 |   1.805  |
+| 119 | 53.9 |   1.595  | 162 | 64.6 |   1.810  |
+| 120 | 54.1 |   1.600  | 163 | 64.8 |   1.815  |
+| 121 | 54.4 |   1.605  | 164 | 65.0 |   1.820  |
+| 122 | 54.7 |   1.610  | 165 | 65.2 |   1.825  |
+| 123 | 55.0 |   1.615  | 166 | 65.5 |   1.830  |
+| 124 | 55.2 |   1.620  | 167 | 65.7 |   1.835  |
+| 125 | 55.5 |   1.625  | 168 | 65.9 |   1.840  |
+| 126 | 55.8 |   1.630  | 169 | 66.1 |   1.845  |
+| 127 | 56.0 |   1.635  | 170 | 66.3 |   1.850  |
+| 128 | 56.3 |   1.640  | 171 | 66.5 |   1.855  |
+| 129 | 56.6 |   1.645  | 172 | 66.7 |   1.860  |
+| 130 | 56.9 |   1.650  | 173 | 67.0 |   1.865  |
+|_____|______|__________|_____|______|__________|
+
+(From _The Oil and Colour Trades Journal_ Diary.)
+
+
+
+
+APPENDIX B.
+
+COMPARISON OF DIFFERENT THERMOMETRIC SCALES.
+
+
+ _______________________________________________________________
+|       |       |       |       |       |       |       |       |
+| Cent. | Fahr. | Cent. | Fahr. | Cent. | Fahr. | Cent. | Fahr. |
+|_______|_______|_______|_______|_______|_______|_______|_______|
+|       |       |       |       |       |       |       |       |
+|   -40 | -40   |     2 |  35.6 |    44 | 111.2 |    86 | 186.8 |
+|    39 |  38.2 |     3 |  87.4 |    45 | 113   |    87 | 188.6 |
+|    38 |  36.4 |     4 |  39.2 |    46 | 114.8 |    88 | 190.4 |
+|    37 |  34.6 |     5 |  41   |    47 | 116.6 |    89 | 192.2 |
+|    36 |  32.8 |     6 |  42.8 |    48 | 118.4 |    90 | 194   |
+|    35 |  31   |     7 |  44.6 |    49 | 120.2 |    91 | 195.8 |
+|    34 |  29.2 |     8 |  46.4 |    50 | 122   |    92 | 197.6 |
+|    33 |  27.4 |     9 |  48.2 |    51 | 123.8 |    93 | 199.4 |
+|    32 |  25.6 |    10 |  50   |    52 | 125.6 |    94 | 201.2 |
+|    31 |  23.8 |    11 |  51.8 |    53 | 127.4 |    95 | 203   |
+|    30 |  22   |    12 |  58.6 |    54 | 129.2 |    96 | 204.8 |
+|    29 |  20.2 |    13 |  55.4 |    55 | 131   |    97 | 206.6 |
+|    28 |  18.4 |    14 |  57.2 |    56 | 132.8 |    98 | 208.4 |
+|    27 |  16.6 |    15 |  59   |    57 | 134.6 |    99 | 210.2 |
+|    26 |  14.8 |    16 |  60.8 |    58 | 136.4 |   100 | 212   |
+|    25 |  13   |    17 |  62.6 |    59 | 138.2 |   101 | 213.8 |
+|    24 |  11.2 |    18 |  64.4 |    60 | 140   |   102 | 215.6 |
+|    23 |   9.4 |    19 |  66.2 |    61 | 141.8 |  +103 |+217.4 |
+|    22 |   7.6 |    20 |  68   |    62 | 143.6 |   104 | 219.2 |
+|    21 |   5.8 |    21 |  69.8 |    63 | 145.4 |   105 | 221   |
+|    20 |   4   |    22 |  71.6 |    64 | 147.2 |   106 | 222.8 |
+|    19 |   2.2 |    23 |  73.4 |    65 | 149   |   107 | 224.6 |
+|    18 |   0.4 |    24 |  75.2 |    66 | 150.8 |   108 | 226.4 |
+|    17 |  +1.4 |    25 |  77   |    67 | 152.6 |   109 | 228.2 |
+|    16 |   3.2 |    26 |  78.8 |   +68 |+154.4 |  +110 |+230   |
+|    15 |   5   |    27 |  80.6 |    69 | 156.2 |   111 | 231.8 |
+|    14 |   6.8 |    28 |  82.4 |    70 | 158   |   112 | 283.6 |
+|    13 |   8.6 |    29 |  84.2 |    71 | 159.8 |   113 | 235.4 |
+|    12 |  10.4 |    30 |  86   |    72 | 161.6 |   114 | 237.2 |
+|    11 |  12.2 |    31 |  87.8 |    73 | 163.4 |   115 | 239   |
+|    10 |  14   |   +32 | +89.6 |    74 | 165.2 |  +116 |+240.8 |
+|     9 |  15.8 |    33 |  91.4 |    75 | 167   |   117 | 242.6 |
+|     8 |  17.6 |    34 |  93.2 |    76 | 168.8 |   118 | 244.4 |
+|     7 |  19.4 |    35 |  95   |    77 | 170.6 |   119 | 246.2 |
+|     6 |  21.2 |    36 |  96.8 |    78 | 172.4 |   120 | 248   |
+|     5 |  23   |    37 |  98.6 |    79 | 174.2 |   121 | 249.8 |
+|    -4 |  24.8 |    49 | 100.4 |    80 | 176   |  +122 |+251.6 |
+|     3 |  26.6 |    39 | 102.2 |    81 | 177.8 |   123 | 253.4 |
+|     2 |  28.4 |    40 | 104   |    82 | 179.6 |   124 | 255.2 |
+|     1 |  30.2 |    41 | 105.8 |    83 | 181.4 |   125 | 257   |
+|     0 |  32   |    42 | 107.6 |    84 | 183.2 |   126 | 258.8 |
+|    +1 |  33.8 |    43 | 109.4 |    85 | 185   |   127 | 260.6 |
+|_______|_______|_______|_______|_______|_______|_______|_______|
+
+(From _Soaps_, by G. H. Hurst, published by Scott, Greenwood & Son.)
+
+
+
+
+APPENDIX C.
+
+TABLE OF THE SPECIFIC GRAVITIES OF SOLUTIONS OF CAUSTIC SODA.
+
+
+ _________________________________________________________________________
+|           |          |                   |                              |
+|           |          |   Per cent. by    | Lb. of actual NaOH contained |
+|           |          |   weight of       | in 1 gallon of lye made from |
+|           |          |                   | commercial caustic of        |
+|  Degrees  | Specific |___________________|______________________________|
+| Twaddell. | gravity. |          |        |         |         |          |
+|           |          | Na_{2}O. |  NaOH. |  77 per |  74 per |  70 per  |
+|           |          |          |        |   cent. |   cent. |   cent.  |
+|___________|__________|__________|________|_________|_________|__________|
+|           |          |          |        |         |         |          |
+|     1     |   1.005  |   0.368  |  0.474 |  0.048  |  0.046  |   0.043  |
+|     2     |   1.010  |   0.742  |  0.957 |  0.097  |  0.092  |   0.087  |
+|     3     |   1.015  |   1.114  |  1.436 |  0.146  |  0.131  |   0.129  |
+|     4     |   1.020  |   1.480  |  1.909 |  0.194  |  0.185  |   0.180  |
+|     5     |   1.025  |   1.834  |  2.365 |  0.243  |  0.231  |   0.219  |
+|     6     |   1.030  |   2.194  |  2.830 |  0.291  |  0.278  |   0.262  |
+|     7     |   1.035  |   2.521  |  3.252 |  0.335  |  0.320  |   0.303  |
+|     8     |   1.040  |   2.964  |  3.746 |  0.389  |  0.371  |   0.350  |
+|     9     |   1.045  |   3.244  |  4.184 |  0.438  |  0.417  |   0.393  |
+|    10     |   1.050  |   3.590  |  4.631 |  0.486  |  0.461  |   0.438  |
+|    11     |   1.055  |   3.943  |  5.086 |  0.536  |  0.510  |   0.483  |
+|    12     |   1.060  |   4.292  |  5.536 |  0.586  |  0.558  |   0.528  |
+|    13     |   1.065  |   4.638  |  5.982 |  0.636  |  0.607  |   0.573  |
+|    14     |   1.070  |   4.972  |  6.413 |  0.680  |  0.653  |   0.617  |
+|    15     |   1.075  |   5.311  |  6.911 |  0.742  |  0.707  |   0.668  |
+|    16     |   1.080  |   5.648  |  7.285 |  0.786  |  0.749  |   0.709  |
+|    17     |   1.085  |   5.981  |  7.715 |  0.836  |  0.798  |   0.755  |
+|    18     |   1.090  |   6.311  |  8.140 |  0.886  |  0.845  |   0.800  |
+|    19     |   1.095  |   6.639  |  8.564 |  0.937  |  0.894  |   0.846  |
+|    20     |   1.100  |   6.954  |  8.970 |  0.986  |  0.941  |   0.890  |
+|    21     |   1.105  |   7.276  |  9.386 |  1.037  |  0.989  |   0.938  |
+|    22     |   1.110  |   7.594  |  9.796 |  1.087  |  1.037  |   0.981  |
+|    23     |   1.115  |   7.910  | 10.203 |  1.137  |  1.123  |   1.026  |
+|    24     |   1.120  |   8.223  | 10.607 |  1.187  |  1.175  |   1.071  |
+|    25     |   1.125  |   8.583  | 11.107 |  1.238  |  1.181  |   1.117  |
+|    26     |   1.130  |   8.893  | 11.471 |  1.296  |  1.237  |   1.170  |
+|    27     |   1.135  |   9.251  | 11.933 |  1.354  |  1.292  |   1.122  |
+|    28     |   1.140  |   9.614  | 12.401 |  1.413  |  1.350  |   1.277  |
+|    29     |   1.145  |   9.965  | 12.844 |  1.470  |  1.413  |   1.337  |
+|    30     |   1.150  |  10.313  | 13.303 |  1.529  |  1.460  |   1.381  |
+|    31     |   1.155  |  10.666  | 13.859 |  1.600  |  1.528  |   1.445  |
+|    32     |   1.160  |  11.008  | 14.190 |  1.646  |  1.541  |   1.456  |
+|    33     |   1.165  |  11.347  | 14.637 |  1.705  |  1.627  |   1.539  |
+|    34     |   1.170  |  11.691  | 15.081 |  1.764  |  1.684  |   1.593  |
+|    35     |   1.175  |  12.025  | 15.512 |  1.822  |  1.739  |   1.645  |
+|    36     |   1.180  |  12.356  | 16.139 |  1.904  |  1.817  |   1.719  |
+|    37     |   1.185  |  12.692  | 16.372 |  1.942  |  1.853  |   1.753  |
+|    38     |   1.190  |  13.016  | 16.794 |  1.998  |  1.887  |   1.804  |
+|    39     |   1.195  |  13.339  | 17.203 |  2.055  |  1.962  |   1.856  |
+|    40     |   1.200  |  13.660  | 17.629 |  2.122  |  2.026  |   1.916  |
+|    41     |   1.205  |  14.058  | 18.133 |  2.185  |  2.085  |   1.973  |
+|    42     |   1.210  |  14.438  | 18.618 |  2.252  |  2.147  |   2.033  |
+|    43     |   1.215  |  14.823  | 19.121 |  2.323  |  2.221  |   2.097  |
+|    44     |   1.220  |  15.124  | 19.613 |  2.392  |  2.280  |   2.161  |
+|    45     |   1.225  |  15.502  | 19.997 |  2.444  |  2.338  |   2.206  |
+|    46     |   1.230  |  15.959  | 20.586 |  2.562  |  2.417  |   2.285  |
+|    47     |   1.235  |  16.299  | 20.996 |  2.593  |  2.475  |   2.341  |
+|    48     |   1.240  |  16.692  | 21.532 |  2.669  |  2.548  |   2.410  |
+|___________|__________|__________|________|_________|_________|__________|
+
+ _________________________________________________________________________
+|           |          |                   |                              |
+|           |          |   Per cent. by    | Lb. of actual NaOH contained |
+|           |          |   weight of       | in 1 gallon of lye made from |
+|           |          |                   | commercial caustic of        |
+|  Degrees  | Specific |___________________|______________________________|
+| Twaddell. | gravity. |          |        |         |         |          |
+|           |          | Na_{2}O. |  NaOH. |  77 per |  74 per |  70 per  |
+|           |          |          |        |   cent. |   cent. |   cent.  |
+|___________|__________|__________|________|_________|_________|__________|
+|           |          |          |        |         |         |          |
+|    49     |   1.245  |  17.060  | 22.008 |  2.739  |  2.615  |   2.474  |
+|    50     |   1.250  |  17.424  | 22.476 |  2.809  |  2.681  |   2.536  |
+|    51     |   1.255  |  17.800  | 22.962 |  2.881  |  2.750  |   2.602  |
+|    52     |   1.260  |  18.166  | 23.433 |  2.952  |  2.818  |   2.666  |
+|    53     |   1.265  |  18.529  | 23.901 |  3.020  |  2.886  |   2.730  |
+|    54     |   1.270  |  18.897  | 24.376 |  3.095  |  2.955  |   2.795  |
+|    55     |   1.275  |  19.255  | 24.858 |  3.171  |  3.027  |   2.863  |
+|    56     |   1.280  |  19.609  | 25.295 |  3.237  |  3.090  |   2.932  |
+|    57     |   1.285  |  19.961  | 25.750 |  3.308  |  3.158  |   2.988  |
+|    58     |   1.290  |  20.318  | 26.210 |  3.381  |  3.227  |   3.053  |
+|    59     |   1.295  |  20.655  | 26.658 |  3.452  |  3.364  |   3.117  |
+|    60     |   1.300  |  21.156  | 27.110 |  3.524  |  3.394  |   3.182  |
+|    61     |   1.305  |  21.405  | 27.611 |  3.603  |  3.439  |   3.253  |
+|    62     |   1.310  |  21.785  | 28.105 |  3.682  |  3.514  |   3.224  |
+|    63     |   1.315  |  22.168  | 28.595 |  3.760  |  3.593  |   3.395  |
+|    64     |   1.320  |  22.556  | 29.161 |  3.849  |  3.674  |   3.475  |
+|    65     |   1.325  |  22.926  | 29.574 |  3.919  |  3.742  |   3.539  |
+|    66     |   1.330  |  23.310  | 30.058 |  3.997  |  3.816  |   3.610  |
+|    67     |   1.335  |  23.670  | 30.535 |  4.072  |  3.891  |   3.681  |
+|    68     |   1.340  |  24.046  | 31.018 |  4.156  |  3.967  |   3.754  |
+|    69     |   1.345  |  24.410  | 31.490 |  4.232  |  4.042  |   3.824  |
+|    70     |   1.350  |  24.765  | 31.948 |  4.312  |  4.116  |   3.894  |
+|    71     |   1.355  |  25.152  | 32.446 |  4.396  |  4.196  |   3.970  |
+|    72     |   1.360  |  25.526  | 32.930 |  4.478  |  4.274  |   4.043  |
+|    73     |   1.365  |  25.901  | 33.415 |  4.561  |  4.354  |   4.109  |
+|    74     |   1.370  |  26.285  | 33.905 |  4.645  |  4.434  |   4.194  |
+|    75     |   1.375  |  26.650  | 34.382 |  4.728  |  4.513  |   4.269  |
+|    76     |   1.380  |  27.021  | 34.855 |  4.810  |  4.592  |   4.344  |
+|    77     |   1.385  |  27.385  | 35.328 |  4.893  |  4.670  |   4.418  |
+|    78     |   1.390  |  27.745  | 35.795 |  4.975  |  4.794  |   4.493  |
+|    79     |   1.395  |  28.110  | 36.258 |  5.058  |  4.828  |   4.567  |
+|    80     |   1.400  |  28.465  | 36.720 |  5.141  |  4.907  |   4.642  |
+|    81     |   1.405  |  28.836  | 37.203 |  5.227  |  4.989  |   4.720  |
+|    82     |   1.410  |  29.203  | 37.674 |  5.312  |  5.071  |   4.797  |
+|    83     |   1.415  |  29.570  | 38.146 |  5.397  |  5.135  |   4.873  |
+|    84     |   1.420  |  29.930  | 38.610 |  5.482  |  5.233  |   4.950  |
+|    85     |   1.425  |  30.285  | 39.071 |  5.567  |  5.314  |   5.027  |
+|    86     |   1.430  |  30.645  | 39.530 |  5.653  |  5.396  |   5.104  |
+|    87     |   1.435  |  30.995  | 39.986 |  5.738  |  5.467  |   5.181  |
+|    88     |   1.440  |  31.349  | 40.435 |  5.823  |  5.558  |   5.258  |
+|    89     |   1.445  |  31.700  | 40.882 |  5.908  |  5.640  |   5.335  |
+|    90     |   1.450  |  32.043  | 41.335 |  5.923  |  5.721  |   5.412  |
+|    91     |   1.455  |  32.460  | 41.875 |  6.093  |  5.816  |   5.502  |
+|    92     |   1.460  |  32.870  | 42.400 |  6.191  |  5.909  |   5.608  |
+|    93     |   1.465  |  33.283  | 42.935 |  6.290  |  6.004  |   5.679  |
+|    94     |   1.470  |  33.695  | 43.467 |  6.389  |  6.009  |   5.769  |
+|    95     |   1.475  |  34.092  | 43.980 |  6.487  |  6.193  |   5.856  |
+|    96     |   1.480  |  34.500  | 44.505 |  6.586  |  6.287  |   5.948  |
+|    97     |   1.485  |  34.899  | 45.013 |  6.685  |  6.381  |   6.035  |
+|    98     |   1.490  |  35.245  | 45.530 |  6.784  |  6.476  |   6.126  |
+|    99     |   1.495  |  35.691  | 46.041 |  6.884  |  6.571  |   6.216  |
+|   100     |   1.500  |  36.081  | 46.545 |  6.982  |  6.665  |   6.303  |
+|___________|__________|__________|________|_________|_________|__________|
+
+(From _Soaps_, by G. H. Hurst, published by Scott, Greenwood & Son.)
+
+
+
+
+APPENDIX D.
+
+TABLE OF STRENGTH OF CAUSTIC POTASH SOLUTIONS AT 60° F.
+
+
+ _______________________________________________
+|          |           |           |            |
+| Specific |  Degrees  | Per cent. | Lb. of KOH |
+| gravity. | Twaddell. |    KOH.   | per gal.   |
+|__________|___________|___________|____________|
+|          |           |           |            |
+|   1.060  |     12    |    5.59   |    0.59    |
+|   1.110  |     22    |   11.31   |    1.25    |
+|   1.150  |     30    |   15.48   |    1.77    |
+|   1.190  |     38    |   19.29   |    2.21    |
+|   1.230  |     46    |   23.22   |    2.84    |
+|   1.280  |     56    |   27.87   |    3.56    |
+|   1.330  |     66    |   31.32   |    4.16    |
+|   1.360  |     72    |   35.01   |    4.76    |
+|   1.390  |     78    |   38.59   |    5.36    |
+|   1.420  |     84    |   40.97   |    5.81    |
+|   1.440  |     88    |   43.83   |    6.31    |
+|   1.470  |     94    |   47.16   |    6.93    |
+|   1.520  |    104    |   51.09   |    7.76    |
+|   1.600  |    112    |   55.62   |    8.89    |
+|   1.680  |    136    |   60.98   |   10.24    |
+|   1.780  |    156    |   67.65   |   12.04    |
+|   1.880  |    176    |   75.74   |   14.23    |
+|   2.000  |    200    |   86.22   |   17.24    |
+|__________|___________|___________|____________|
+
+(From _Soaps_, by G. H. Hurst, published by Scott, Greenwood & Son.)
+
+
+THE END.
+
+
+
+
+INDEX.
+
+
+A.
+
+Acetic Acid, 10
+
+Acid, Acetic, 10
+
+---- Arachidic, 10
+
+---- Behenic, 10
+
+---- Butyric, 10
+
+---- Capric, 10
+
+---- Caproic, 10
+
+---- Caprylic, 10
+
+---- Carnaubic, 10
+
+---- Cerotic, 10
+
+---- Daturic, 10
+
+---- Doeglic, 11
+
+---- Elæomargaric, 12
+
+---- Elæostearic, 12
+
+---- Erucic, 11
+
+---- Ficocerylic, 10
+
+---- Hyænic, 10
+
+---- Hypogæic, 11
+
+---- Isolinolenic, 12
+
+---- Isovaleric, 10
+
+---- Jecoric, 12
+
+---- Lauric, 10
+
+---- Lignoceric, 10
+
+---- Linolenic, 12
+
+---- Linolic, 12
+
+---- Margaric, 10
+
+---- Medullic, 10
+
+---- Melissic, 10
+
+---- Moringic, 11
+
+---- Myristic, 10
+
+---- Oleic, 11
+
+---- Palmitic, 10
+
+---- Physetoleic, 11
+
+---- Pisangcerylic, 10
+
+---- Psyllostearylic, 10
+
+---- Rapic, 11
+
+---- Ricinoleic, 13
+
+---- Saponification, 19-21
+
+---- Stearic, 10
+
+---- Tariric, 12
+
+---- Telfairic, 12
+
+---- Theobromic, 10
+
+---- Tiglic, 11
+
+---- value, 118, 128
+
+Acids, Classification of fatty, 10
+
+---- Fatty, 9-13
+
+---- ---- Combination with Alkali, 45, 46
+
+Acids, Fatty, Preparation by acid process, 19-21
+
+----    ----    ---- by ferment process, 16
+
+----    ----    ---- by Twitchell's process, 20
+
+---- Saturated fatty, 11
+
+---- Unsaturated fatty, 11
+
+Albumen in soap, 90
+
+Alcohols, Estimation of, 128
+
+Aldehydes, Estimation of, 129
+
+Alkali, Caustic and carbonated, 38, 39, 123-126
+
+Alkali in soap, Determination of, 131, 132
+
+Amyl salicylate, 107
+
+Andiroba oil, 32
+
+Animal charcoal, 115
+
+---- fats, Treatment of, 43
+
+Anise (star) oil, 96
+
+Anisic aldehyde, 108
+
+Arachidic acid, 10
+
+Arachis oil, 28
+
+Artificial perfumes, 107-110
+
+Ash, Soda, 39, 124, 125
+
+Aspic oil, 96
+
+Aqueous saponification, 14
+
+Aubépine, 108
+
+
+B.
+
+Bacteria, Decomposition of fats by, 18
+
+Baobab-seed oil, 36
+
+Bar soap, 54, 55
+
+Barring soap, 68
+
+Bay oil, 97
+
+Behenic acid, 10
+
+Benzyl acetate, 108
+
+Bergamot oil, 97
+
+---- ---- (artificial), 109
+
+Biniodide soaps, 87
+
+Birch-tar soap, 88
+
+Bitter almond oil, 97
+
+Bleaching palm oil, 41
+
+---- rosin, 43
+
+Boiling-on-strength, 51
+
+Bois de Rose Femelle oil, 99
+
+Bone-fat, 30
+
+---- ---- treatment of, 43
+
+Borax in soap, 88
+
+Boric acid in soap, 88
+
+Boric acid in soap, Determination of, 135
+
+Borneo tallow, 32
+
+Brine, 39
+
+Bromine absorption of oils and fats, 122
+
+Brown Windsor soap, 78, 98
+
+Butter goa, 33
+
+---- kokum, 33
+
+---- shea, 31
+
+Butyric acid, 10
+
+Butyrin, 8
+
+
+C.
+
+Calico-printer's soap, 93
+
+Cananga oil, 98
+
+Candle-nut oil, 33
+
+Capric acid, 10
+
+Caprin, 8
+
+Caproic acid, 10
+
+Caproin, 8
+
+Caprylic acid, 10
+
+Caprylin, 8
+
+Carapa oil, 32
+
+Caraway oil, 98
+
+Carbolic acid in soap, Determination of, 134
+
+Carbolic soap, 88
+
+Carbonate potash, 39, 125, 126
+
+---- soda, 39, 124, 125
+
+Carnaubic acid, 10
+
+Cassia oil, 98
+
+Castor oil, 30
+
+Caustic potash, 39, 123
+
+---- soda, 39, 123
+
+Cayenne linaloe oil, 99
+
+Cedarwood oil, 98
+
+Cerotic acid, 10
+
+Charcoal, Animal, 115
+
+Chinese vegetable tallow, 31
+
+Cholesterol in unsaponified matter, 120
+
+Cinnamon oil, 98
+
+Citral, 108
+
+Citronella oil, 99
+
+Citronellal, 108
+
+Cleansing soap, 60, 61
+
+Close-piling soap, 71
+
+Clove oil, 99
+
+Coal tar soaps, 88
+
+Cocoa-nut oil, 25, 26
+
+Cohune-nut oil, 34
+
+Cold process soap-making, 46, 47
+
+Colouring soap, 66, 80, 82
+
+Compressing soap, 83, 85
+
+Concrete orris oil, 100
+
+Constitution of oils and fats, 6, 7
+
+Conversion of oleic acid into solid acids, 11, 12
+
+Cooling soap, 74, 76
+
+Coprah oil, 25, 26
+
+Cotton-seed oil, 27, 42
+
+---- ---- Refining, 42
+
+---- soapstock, 40
+
+---- stearine, 28
+
+Coumarin, 108
+
+Crude glycerine, 113, 136-139
+
+Crutching soap, 63
+
+Curcas oil, 33
+
+Curd mottled soap, 52, 53
+
+Curd soaps, 52
+
+Cutting and stamping toilet soap, 85
+
+
+D.
+
+Daturic acid, 10
+
+Decolorisation, Glycerine, 115
+
+Decomposition of fats by bacteria, 18
+
+Detergent action of soap, 4, 5
+
+Diglycerides, 7
+
+Dika fat, 36
+
+Disinfectant soaps, 66
+
+Distearine, 7
+
+Distillation, glycerine, 114
+
+Distilled glycerine, 114
+
+Doeglic acid, 11
+
+Double distilled glycerine, 115
+
+Dregs in fats and oils, Determination of, 120, 121
+
+Drying soap, 71, 78-80
+
+Dynamite glycerine, 115
+
+
+E.
+
+Elaidin reaction, 12
+
+Electrical production of soap, 59
+
+Elæomargaric acid, 12
+
+Elæostearic acid, 12
+
+Enzymes, Action of, 15-18
+
+Erucic acid, 11
+
+Essential oils, 96-107
+
+---- ---- Examination of, 127-130
+
+Ester value, 119, 128
+
+Ether soap, 90
+
+Eucalyptus oil, 100
+
+Evaporation to crude glycerine, 112, 113
+
+
+F.
+
+Fat, Bone, 30
+
+---- Dika, 36
+
+---- Maripa, 34
+
+---- Marrow, 30
+
+---- Niam, 34
+
+---- Tangkallah, 37
+
+---- Treatment of bone, 43
+
+Fats, Decomposition by bacteria of, 18
+
+---- Treatment of animal, 43
+
+---- Waste, 30
+
+Fats and oils, Determination of acid value of, 118
+
+---- ---- ---- of bromine absorption of, 122
+
+---- ---- ---- of dregs, etc., in, 120, 121
+
+---- ---- ---- of free acidity of, 117
+
+---- ---- ---- of iodine absorption of, 121, 122
+
+---- ---- ---- of saponification
+
+---- ---- ---- equivalents of, 118
+
+---- ---- ---- of saponification value, 118
+
+---- ---- ---- of specific gravity of, 117 of titre of, 122, 123
+
+---- ---- ---- of unsaponifiable matter in, 119
+
+---- ---- ---- of water in, 120
+
+---- ---- ---- Yield of glycerine from, 116
+
+Fatty acids, 9-13, 31
+
+---- ---- Classification of, 10
+
+---- ---- Direct combination with alkali of, 45, 46
+
+---- ---- in soap, Determination of, 131
+
+---- ---- ---- Examination of, 133, 134
+
+---- ---- Preparation by acid process, 19-21
+
+---- ---- ---- by ferment process, 16
+
+---- ---- ---- by Twitchell's process, 20
+
+---- ---- Saturated, 11
+
+---- ---- Unsaturated, 11
+
+Fennel oil, 100
+
+Ferment process for preparation of fatty acids, 16
+
+Ferments, action of, 15-18
+
+Ficocerylic acid, 10
+
+Filling soap, 65
+
+Fish oils, 30
+
+"Fitting," 51
+
+Floating soap, 90, 91
+
+Fluorides in soap, 88
+
+Formaldehyde soap, 88
+
+Framing soap, 66
+
+Free alkali in soap, Estimation of, 132
+
+---- caustic in soap, Neutralising, 66
+
+---- fat in soap, Determination of, 133
+
+---- fatty acids, Determination of, 117
+
+
+G.
+
+Geraniol, 108
+
+Geranium oils, 101
+
+Geranium-sur-rose oil, 101
+
+Ginger-grass oil, 101
+
+Glycerides, 7, 8
+
+Glycerine, Chemically pure, 115
+
+---- Crude, 113, 136-139
+
+---- decolorisation, 115
+
+---- distillation, 114
+
+---- Distilled, 114
+
+---- dynamite, 115
+
+---- in soap, Determination of, 134, 135
+
+---- manufacture, 111-114
+
+---- saponification, 116
+
+---- soaps, 89
+
+---- Yield of, from fats and oils, 116
+
+Glycerol determination, acetin method, 136
+
+---- ---- bichromate method, 137, 138
+
+---- in lyes, Estimation of, 135
+
+Goa-butter, 33
+
+"Graining-out," 50
+
+Grease, Animal, 30
+
+---- Bone, 30
+
+---- Kitchen, 30
+
+---- Skin, 30
+
+Guaiac wood oil, 101
+
+
+H.
+
+Halphen's reaction, 134
+
+Heliotropin, 108
+
+Hemp-seed oil, 29
+
+Hyacinth, 108
+
+Hyænic acid, 10
+
+Hydrated soaps, 48, 49
+
+Hydrolysis accelerated by heat and electricity, 14, 15
+
+---- accelerated by use of chemical reagents,  19-23
+
+---- accelerated with acid, 19, 21
+
+---- Enzymic, 15-18
+
+---- of oils and fats, 13-23
+
+---- of soap, 3
+
+Hypogæic acid, 11
+
+
+I.
+
+Ichthyol soap, 89
+
+Inoy-kernel oil, 37
+
+Iodine absorption of rose oil, 130
+
+---- absorption of oils and fats, 121,122:
+
+---- soap, 89
+
+Ionone, 108
+
+Isolinolenic acid, 12
+
+Isovaleric acid, 10
+
+Isovalerin, 8
+
+
+J.
+
+Jasmine, 109
+
+Jecoric acid, 12
+
+
+K.
+
+Kananga oil, 98
+
+Kapok oil, 32
+
+"Kastilis," 88
+
+Kokum butter, 33
+
+
+L.
+
+Lard, 25
+
+Lauric acid, 10
+
+Laurin, 8
+
+Lavender oils, 101
+
+Lemon-grass oil, 102
+
+Lemon oil, 102
+
+Lignoceric acid, 10
+
+Lime oil, 102
+
+---- saponification, 22
+
+Linaloe oil, 102
+
+Linalol, 109
+
+Linalyl acetate, 109
+
+Linolenic acid, 12
+
+Linolic acid, 12
+
+Linseed oil, 29
+
+Lipase, 18
+
+Liquoring of soaps, 64
+
+Lyes, analysis of, 135
+
+---- Determination of glycerol in, 135
+
+---- Evaporation of, 112
+
+---- Treatment of, 111, 112
+
+Lysol soap, 89
+
+
+M.
+
+Mafura tallow, 35
+
+Magnesia, Hydrolysis by, 22
+
+Maize oil, 28
+
+Margaric acid, 10
+
+Margosa oil, 35
+
+Marine animal oils, 30
+
+---- soap, 49
+
+Maripa fat, 34
+
+Marjoram oil, 103
+
+Medicated soaps, 86-90
+
+Medullic acid, 10
+
+Melissic acid, 10
+
+Melting point, 130
+
+Mercury soaps, 87
+
+Milled toilet soaps, 78
+
+Milling soap, 80, 81
+
+---- soap-base, 54, 78
+
+Mineral oil, saponifying, 58, 59
+
+Mirbane oil or nitrobenzene, 109
+
+Mixed glycerides, 8
+
+Monoglycerides, 7
+
+Monostearin, 7
+
+Moringic acid, 11
+
+Mottled soaps, 52, 53
+
+---- ---- Pickling, 54
+
+Moulds, Soap, 72, 85, 86
+
+Mowrah-seed oil, 31
+
+Musk (artificial), 109
+
+Myristic acid, 8
+
+Myristin, 8
+
+
+N.
+
+Naphthol soap, 89
+
+Neroli Bigarade oil, 103
+
+---- oil (artificial), 109
+
+Neutralising free caustic in soap, 66, 80
+
+Niam fat, 34
+
+Nigre, 56
+
+Nigres, Utilisation of, 56
+
+Niobe oil or ethyl benzoate, 110
+
+Nitrobenzene, 109
+
+
+O.
+
+Oeillet, 10
+
+Oil, Andiroba, 32
+
+---- Arachis, 28
+
+---- Aspic (lavender spike), 96
+
+---- Baobab-seed, 36
+
+---- Bay, 97
+
+---- Bergamot, 97
+
+---- Bitter almond, 97
+
+---- Bleaching palm, 41
+
+---- Bois de Rose Femelle, 99
+
+---- Cananga, 98
+
+---- Candle-nut, 33
+
+---- Carapa, 32
+
+---- Caraway, 98
+
+---- Cassia, 98
+
+---- Castor, 30
+
+---- Cayenne linaloe, 99
+
+---- Cedarwood, 98
+
+---- Cinnamon, 98
+
+---- Citronella, 99
+
+---- Clove, 99
+
+---- Cocoa-nut, 25, 26
+
+---- Cohune-nut, 34, 35
+
+---- Concrete orris, 100
+
+---- Coprah, 25, 26
+
+---- Cotton-seed, 27, 42
+
+---- Curcas, 33
+
+---- Eucalyptus, 100
+
+---- Fennel, 100
+
+---- Geranium, 101
+
+---- Ginger-grass, 101
+
+---- Guaiac-wood, 101
+
+---- Hemp-seed, 29
+
+---- Inoy-kernel, 37
+
+---- Kananga, 98
+
+---- Kapok, 32
+
+---- Lemon, 102
+
+---- Lemon-grass, 102
+
+---- Lime, 102
+
+---- Linaloe, 102
+
+---- Linseed, 29
+
+---- Maize, 28
+
+---- Margosa, 35
+
+---- Marjoram, 103
+
+---- Mowrah-seed, 31
+
+---- Neroli Bigarade, 103
+
+---- Olive, 26
+
+---- Olive-kernel, 27
+
+---- Orange, 163
+
+---- Palm, 27, 41
+
+---- Palm-nut, 26
+
+---- Palmarosa, 103
+
+---- Patchouli, 103
+
+---- Peppermint, 103, 104
+
+---- Persimmon-seed, 36
+
+---- Peru-balsam, 104
+
+---- Petit-grain, 104
+
+---- Pongam, 35
+
+---- Refining cotton-seed, 42
+
+---- Rose, 105
+
+---- Rosemary, 105
+
+---- Safflower, 33, 34
+
+---- Sandalwood, 105, 106
+
+---- Saponifying mineral, 58, 59
+
+---- Sassafras, 106
+
+---- Sesame, 28, 29
+
+---- Star-anise, 96
+
+---- Sunflower, 29
+
+---- Thyme, 106
+
+---- Verbena, 106
+
+---- Vetivert, 106-107
+
+---- Wheat, 36
+
+---- Wild mango, 36
+
+---- Wintergreen, 107
+
+---- Ylang-ylang, 107
+
+Oils and fats, Constitution of, 6, 7
+
+---- ---- Examination of, 117-123
+
+---- ---- Hydrolysis of, 13-22
+
+---- Fish and marine animal, 30
+
+---- Lavender, 101
+
+---- Refractive Index of, 122
+
+---- treatment of vegetable, 43
+
+Oleic acid, 11
+
+---- ---- into solid acids, Conversion of, 11, 12
+
+Olein, 8, 9, 31
+
+---- Cocoa-nut, 31
+
+---- Palm-nut, 31
+
+Oleodidaturin, 8
+
+Oleodipalmitin, 8
+
+Oleodistearin, 8
+
+Oleopaimitostearin, 8
+
+Olive-kernel oil, 27
+
+Olive oil, 26
+
+Open-piling soap, 71
+
+Optical rotation, 127
+
+Orange oil, 103
+
+Orchidée, 107
+
+Orris oil, concrete, 100
+
+
+P.
+
+Palm oil, 27, 41
+
+---- ---- Bleaching, 41
+
+Palmarosa oil, 103
+
+Palmitic acid, 10
+
+Palmitin, 8
+
+Palmitodistearin, 8
+
+Palm-nut oil, 26
+
+Pasting or saponification, 49
+
+Patchouli oil, 103
+
+Patent textile soaps, 94
+
+Pearl-ash, Analysis of, 125, 126
+
+Peppermint oil, 103, 104
+
+Perfumer's soaps, 77, 78
+
+Perfumes, Artificial and synthetic, 107-110
+
+---- Soap, 95-110
+
+Perfuming soaps, 94
+
+Persimmon seed oil, 36
+
+Peru-balsam oil, 104
+
+Petit-grain oil, 104
+
+Phenols, Determination of, 129
+
+Physetoleic acid, 11
+
+Phytosterol in unsaponifiable matter, 120
+
+Pickling mottled soap, 54
+
+Pisangcerylic acid, 10
+
+Polishing soaps, 94
+
+Pongam oil, 35
+
+Potash, Carbonate, 39, 125, 126
+
+---- Caustic, 89, 123
+
+Potassium chloride, 126
+
+---- Determination of, 126, 132
+
+Powders, Soap, 94
+
+Psyllostearylic acid, 10
+
+
+R.
+
+Rancidity, 18, 24
+
+Rapic acid, 11
+
+Refining cotton-seed oil, 42
+
+Refractive index of oils and fats, 122
+
+Remelted soaps, 77, 78
+
+Resinate of soda, 43, 44
+
+Ricinoleic acid, 13
+
+Ricinolein, 8
+
+Rose oil, 105
+
+---- ---- (artificial), 110
+
+Rosemary oil, 105
+
+Rosin, 37, 38, 43, 44, 55
+
+---- Bleaching, 43
+
+---- Determination of, 133, 134
+
+---- treatment, 43, 44
+
+
+S.
+
+Safflower oil, 33, 34
+
+Safrol, 110
+
+Salt, 39, 126
+
+---- Determination of, 124, 125, 126, 132
+
+Sandalwood oil, 105, 106
+
+Santalol, 110
+
+Saponification, 13-22, 49
+
+---- accelerated by heat and electricity, 14, 15
+
+---- accelerated by use of chemical reagents, 19, 23
+
+---- accelerated with Twitchell's reagent, 20
+
+---- Acid, 19, 21
+
+---- Aqueous, 14
+
+---- by ferment process, 20
+
+---- equivalent, 118
+
+---- Glycerine, 116
+
+---- Lime, 22
+
+---- under pressure, 47
+
+---- value, 118, 128
+
+Saponifying mineral oil, 58, 59
+
+Sassafras oil, 106
+
+Saturated acids, 11
+
+Scouring soaps, 92, 93
+
+Sesame oil, 28, 29
+
+Settled soap, Treatment of, 60-76
+
+Shaving soaps, 91
+
+Shea butter, 31
+
+Silicate of soda in soap, 65
+
+Silicates of soda and potash, 127, 138
+
+Silk scouring soaps, 93
+
+---- dyer's soap, 93, 94
+
+Slabbing soap, 68
+
+Soap, Albumen in, 90
+
+---- Analysis of, 130-35
+
+---- Bar, 54, 55
+
+---- Barring, 68
+
+---- -base, Milling, 54, 78
+
+---- Biniodide, 87
+
+---- Birch-tar, 88
+
+---- Borax, 88
+
+---- Boric acid in, 88
+
+---- ---- ---- ---- Determination, 135
+
+---- Carbolic, 88
+
+---- Classification of, 45
+
+---- Cleansing, 60, 61
+
+---- Coal-tar, 88
+
+---- Cold process, 46, 47
+
+---- Compressing, 83, 85
+
+---- Cooling, 74-76
+
+---- Crutching, 63
+
+---- Curd, 52
+
+---- Curd mottled, 53
+
+---- Definition of, 1, 2
+
+---- Detergent action of, 4, 5
+
+---- Determination of carbolic acid in, 134
+
+---- ---- of fatty acids in, 131
+
+---- ---- of free alkali in, 132
+
+---- ---- of free fat in, 133
+
+---- ---- of glycerine in, 134, 135
+
+---- ---- of total alkali in, 131
+
+---- ---- of water in, 133
+
+---- Drying, 71, 78-80
+
+---- Electrical production of, 59
+
+---- Ether, 90
+
+---- Examination of fatty acids 133, 134
+
+---- Filling, 65
+
+---- Fluorides in, 90
+
+---- formaldehyde, 88
+
+---- frame, 66
+
+---- framing, 66
+
+---- from fatty acids, 45, 46
+
+---- Glycerine, 89
+
+---- Hydrated, 48, 49
+
+---- Hydrolysis of, 3
+
+---- Ichthyol, 89
+
+---- Iodine, 89
+
+---- Lysol, 89
+
+---- Marine, 49
+
+---- Milling, 80, 81
+
+---- Monopole, 94
+
+---- Mottled, 52, 53
+
+---- moulds, 72, 85, 86
+
+---- Naphthol, 89
+
+---- Neutralising, colouring and perfuming, 66, 80, 82
+
+---- Open and close piling, 71
+
+---- perfumes, 95-110
+
+---- Pickling mottled, 54
+
+---- powders, 94
+
+---- Properties of, 2
+
+---- Salicylic acid, 88
+
+---- Settling of, 55
+
+---- Slabbing, 68
+
+---- Soft, 41
+
+---- Stamping, 71, 72, 85, 86
+
+---- Sulphur, 89
+
+---- Terebene, 90
+
+---- Thymol, 90
+
+---- Transparent, 57, 58
+
+---- Treatment of settled, 60-76
+
+---- Yellow household, 54, 55
+
+Soap-making, 45-59
+
+---- ---- Blue and grey mottled, 53
+
+---- ---- "Boiling-on-strength," 51
+
+---- ---- Cold process, 46, 47
+
+---- ---- Combination of fatty acids with alkali, 45, 46
+
+---- ---- Curd, 52
+
+---- ---- Curd, Mottled, 53
+
+---- ---- "Fitting," 51
+
+---- ---- "Graining-out" or separation, 50
+
+---- ---- Hydrated, 49
+
+---- ---- "Pasting" or saponification, 49
+
+---- ---- Soft, 48
+
+---- ---- Transparent, 57, 58
+
+---- ---- under pressure, 47
+
+Soaps, Calico-printer's, 93
+
+---- Disinfectant, 66
+
+---- Floating, 90, 91
+
+---- Liquoring of, 64, 65
+
+---- Medicated, 86-90
+
+---- Milled toilet, 78
+
+---- Miscellaneous, 94
+
+---- Perfumer's, 77, 78
+
+---- Polishing, 94
+
+---- Remelted, 77, 78
+
+---- Scouring, 92
+
+---- Shaving, 91
+
+---- Silicating, 65
+
+---- Silk dyer's, 93, 94
+
+---- Textile, 91-94
+
+---- Toilet, 77, 78
+
+---- Woollen dyer's, 92
+
+Soap-stock, 40
+
+Soda ash, 39, 124, 125
+
+---- ---- Caustic, 39, 125
+
+---- Carbonate, 39, 124, 125
+
+---- Caustic, 39, 123
+
+---- Resinate, 43, 44
+
+Soft soap-making, 48
+
+Solidifying-point, 130
+
+Specific gravity, Determination of, 117, 127
+
+Stamping soap, 71, 72, 85, 86
+
+Starch, Detection of, 121, 135
+
+Steapsin, 18
+
+Stearic acid, 10
+
+Stearin, 8, 9
+
+Stearine, Cotton-seed, 28
+
+Stearodipalmitin, 8
+
+Sulphides and sulphites, Determination of, 125
+
+Sulphur soap, 89
+
+Sunflower oil, 29
+
+Superfatting material, 83
+
+Synthetic perfumes, 107-110
+
+
+T.
+
+Table of caustic potash solutions, 151
+
+---- of caustic soda solutions, 149, 150
+
+---- of comparative densities, 147
+
+---- of thermometric equivalents, 148
+
+Tablet soap, 55
+
+Talc, 65
+
+Tallow, 24
+
+---- Borneo, 32
+
+---- Chinese vegetable, 31
+
+---- Mafura, 35
+
+Tangkallah fat, 37
+
+Tariric acid, 12
+
+Telfairic acid, 12
+
+Terebene, 110
+
+---- soap, 90
+
+Terpineol, 110
+
+Textile soaps, 91-94
+
+---- ---- Patent, 94
+
+Theobromic acid, 10
+
+Thyme oil, 106
+
+Thymol soap, 90
+
+Tiglic acid, 11
+
+Titre test, 122, 123
+
+Toilet soaps, 77, 78
+
+---- ---- Compressing, 83, 85
+
+---- ---- Milled, 78
+
+---- ---- Milling, 80, 81
+
+---- ---- Stamping, 85, 86
+
+Transparent soaps, 57, 58
+
+Treatment of animal fats, 43
+
+---- ---- bone fat, 43
+
+---- ---- lyes, 111, 112
+
+---- ---- rosin, 43
+
+---- ---- settled soap, 60-76
+
+---- ---- Vegetable oils, 43
+
+Trèfle, 107
+
+Triglycerides, 7, 8
+
+Trilaurin, 9
+
+Triolein, 9
+
+Tripalmitin, 9
+
+Tristearin, 7, 9
+
+Twitchell's process, 22
+
+
+U.
+
+Unsaponifiable matter, Constitution of, 119, 120
+
+---- ---- Determination of, 119
+
+Unsaturated acids, 11
+
+Utilisation of nigres, 56
+
+
+V.
+
+Vanillin, 110
+
+Vegetable oils, Treatment of, 43
+
+---- tallow, Chinese, 31
+
+Verbena oil, 106
+
+Vetivert oil, 106
+
+Violet soap, 54
+
+Volhard's method for chloride determination, 132
+
+
+W.
+
+Waste fats, 30
+
+Water, 39
+
+---- ---- in fats, Determination of, 120
+
+---- ---- in soap, Determination of, 133
+
+Wheat oil, 36
+
+Wild mango oil, 36
+
+Wintergreen oil, 107
+
+Wool scouring soaps, 92
+
+Woollen dyer's soap, 92
+
+
+Y.
+
+Ylang-ylang oil, 107
+
+
+Z.
+
+Zinc oxide, Hydrolysis by, 22
+
+---- soap, 87
+
+THE ABERDEEN UNIVERSITY PRESS LIMITED
+
+
+
+
+          STEVENSON & HOWELL'S
+
+          SPECIALITIES FOR
+
+          Soapmakers & Wholesale Perfumers.
+
+
+          ESSENTIAL OILS
+
+          OF GUARANTEED PURITY.
+
+
+          Almonds, Bay Leaves, Bergamot, Caraway,
+          Cananga, Camomile, Cascarilla, Cassia,
+          Cedar Wood, Cinnamon, Citronella, Cloves,
+          Coriander, Eucalyptus Globulus, Fennel, Sweet,
+          Geranium -- _Algerian_, _Bourbon_, _East Indian_,
+          _French_, _Spanish_ & _Turkish_,
+          Kuromoji, Lavender, Lemon, Lemon-Grass,
+          Limes, Neroli, Myrbane, Orange Sweet & Bitter,
+          Otto of Rose, Patchouli, Palmarosa, Pimento,
+          Petit-Grain, Rosemary, Sandal Wood, Sage,
+          Sassafras, Spearmint, Thyme, Wintergreen
+          Ylang-Ylang., &c.
+
+
+          TOILET SOAP PERFUMES
+
+          FINEST QUALITY
+
+          Almond, Bay Rum, Brown Windsor, Cologne,
+          Florida, Frangipanni, Heliotrope, Hyacinth, Lilac,
+          Lily of Valley, Oriental, Parisian, Walnut Leaf,
+          Wood Violet, &c.
+
+
+          ARTIFICIAL PERFUMES.
+
+          Aubepine, Cuir de Russiè, Coumarin, Crategine,
+          Heliotropine, Lilac, Musk, Nerolin, Terpineol,
+          Vanillin, Yara-Yara, &c.
+
+          SOAP COLOURS, Dark Blue, Rose Pink,
+          Indian Brown, Carbolic Pink & Red, Manchester Yellow.
+          &c. &c.
+
+          _SPECIALITY_:--RELIABLE CHLORPHYL.
+
+          STANDARD WORKS
+
+          SOUTHWARK ST. LONDON. S. E.
+
+          GLASGOW OFFICE         128, HOPE ST.
+
+
+
+
+           ___________________________________________________
+          |                                                   |
+          |                FASTEST AND STRONGEST              |
+          |                                                   |
+          |                   COLOURS FOR SOAP                |
+          |                                                   |
+          |            In all shades, alkali-proof.           |
+          |                                                   |
+          |            OIL SOLUBLE COLOURS FOR                |
+          |                 OIL AND BENZINE SOAPS.            |
+          |                                                   |
+          |                        BLACKS                     |
+          |                                                   |
+          | And all colours soluble in Oil, Wax and Turps for |
+          |                                                   |
+          |                     BOOT POLISH.                  |
+          |                                                   |
+          |  ===============================================  |
+          |                                                   |
+          |          WILLIAMS BROS. & CO., HOUNSLOW.          |
+          |___________________________________________________|
+
+                             TEXTILE
+
+                          SOAPS AND OILS.
+
+           Handbook on the Preparation, Properties and Analysis
+           of the Soaps and Oils used in Textile Manufacturing,
+                          Dyeing and Printing.
+
+                                   BY
+                         GEORGE H. HURST, F.C.S.,
+
+           Author of "Soaps," "Lubricating Oils, Fats and Greases," etc.
+
+                                CONTENTS.
+
+              Methods of Making Soaps--Special Textile Soaps--Relation of Soap
+              to Water for Industrial Purposes--Soap Analysis--Fat in
+              Soap--Animal and Vegetable Oils and Fats--Vegetable Soap, Oils
+              and Fats--Glycerine--Textile Oils.
+
+          Price 5s. net (Post Free, 5s. 4d. Home; 5s. 6d. Abroad).
+
+          Published by
+
+          SCOTT, GREENWOOD & SON,
+          8 BROADWAY, LUDGATE HILL, LONDON, E.C.
+
+
+
+
+
+          WILLIAM TULLOCH & CO.,
+
+          30 George Square, Glasgow,
+          And at 9 Great Tower Street, London, E.C.,
+          14 No. Corridor, Royal Exchange, Manchester.
+
+          GLYCERINE,
+
+          CRUDE, DYNAMITE, INDUSTRIAL, CHEMICALLY PURE.
+
+          All Kinds of Chemicals for Soap and Explosives Makers.
+
+          NITRATE OF LEAD, FARINAS, STARCHES, GUMS.
+
+          TWITCHELL PROCESS OF
+          GLYCERINE EXTRACTION.
+
+          HIGHEST
+
+          Degree of Decomposition.
+
+          LOWEST
+
+          Cost for Installation and Working.
+
+          BEST
+
+          Qualities of Fatty Acids, Glycerine, Stearine and Soap.
+
+          For Samples and information, apply to
+
+          WM. TULLOCH & CO.,
+
+          30 GEORGE SQUARE, GLASGOW.
+          General Representatives for United Kingdom and Colonies.
+
+          SUDFELDT & CO., MELLE (HANOVER, GERMANY).
+
+          JOSLIN SCHMIDT & CO.,
+
+          CINCINNATI, OHIO, U.S.A.
+
+
+
+
+          THE CHEMISTRY OF
+
+          Essential Oils
+
+          AND
+
+          Artificial Perfumes.
+
+          BY
+
+          ERNEST J. PARRY, B.Sc. (Lond.), F.I.C., F.C.S.
+
+          552 Pages. Second Edition, Revised and Enlarged. Demy 8vo. 1908.
+
+     CONTENTS.
+
+     Chapters I. ~The General Properties of Essential Oils.~ Physical
+     Properties, Optical Properties, Table of Specific Gravities,
+     Refractive Indices and Rotation.--II. ~Compounds occurring in
+     Essential Oils.~ (I.) 1. TERPENES--Pinene, Camphene, Limonene,
+     Dipentene, Fenchene, Sylvestrene, Carvestrene, Phellandrene,
+     Terpinolene, Terpinene and Thujene. 2.
+     SESQUITERPENES--Cadinene, Caryophellene, Cedrene, Clovene,
+     Humulene, Ledene, Patchoulene, and Sesquiterpene from Oils of
+     Cannabis Indica, Table, b.p., sp.-gr., opt. Rot., etc., of
+     same. (II.) THE CAMPHOR SERIES--Borneol, Isoborneol, Camphor,
+     Fenchyl Alcohol, Fenchone, Thujyl Alcohol, Thujone, Terpineol,
+     Cineol, etc., etc. (III.) THE GERANIOL AND CITRONELLOL
+     GROUP--Coriandrol, Nerolol, Rhodinol, Geraniol, Linalol,
+     Citrenellol, etc., Table, b.p., sp.-gr., Ref. Index, etc. (IV.)
+     BENZENE COMPOUNDS--Cymene, Phenols and their Derivatives,
+     Phenols with Nine Carbon Atoms, Phenols with Ten Carbon Atoms,
+     Alcohols, Aldehydes, Ketones, Acids, etc. (V.) ALIPHATIC
+     COMPOUNDS--Alcohols, Acids, Aldehydes, Sulphur Compounds,
+     etc.--III. ~The Preparation of Essential Oils.~ Expression,
+     Distillation, Extraction, Table of Percentages.--IV. ~The
+     Analysis of Essential Oils.~ Specific Gravity, Sprengel Tube
+     Method, Optical Methods, Melting and Solidifying Points,
+     Boiling Point and Distillation, Quantitative Estimations of
+     Constituents, the Determination of Free Alcohols, Absorption
+     Processes.--V. ~Systematic Study of the Essential Oils.~ Oils of
+     the Gymnosperms, Tabulated Angiosperms. (I.) WOOD OILS.--Cedar
+     Oils, Oils of Turpentine, American Turpentine, French Oil of
+     Turpentine, German, Russian, and Swedish ditto, Table of
+     Activities of same, Juniper Wood Oil. (II.) FRUIT
+     OILS.--Juniper Berry Oil, Fir Cone Oils. (III.) LEAF
+     OILS.--Thuja Oil, Oil of Savin, Cedar Leaf Oil, Pine Needle
+     Oil, Cypress Leaf Oil, Table of Pine Oils (after Schimmel).
+     OILS OF THE ANGIOSPERMS--(I.) MONOCOTYLEDONS. (II.)
+     DICOTYLEDONS: (_a_) MONOCHLAMYDEÆ--(_b_) GAMOPETALÆ--(_c_)
+     POLYPETALÆ--VI. ~Terpeneless Oils.~ Terpeneless Oil of Lemon,
+     Tables of sp.-gr. and Rotn. of several Terpeneless Oils,
+     Terpeneless Oil of Orange, Ditto of Caraway, of Lavender, Table
+     of sp.-gr. and Rotn. of Commercial Samples of Oils.--VII. ~The
+     Chemistry of Artificial Perfumes.~ Vanillin, Coumarin,
+     Heliotropin, Aubepine or Hawthorn, Ionone, Specification of
+     Patents for Preparation of Ionone, for Artificial Violet Oil,
+     Artificial Musk, Specification of Patent of Musk Substitute,
+     Artificial Neroli, Artificial Lilac, Artificial Hyacinth,
+     Artificial Lemon Oil, Artificial Rose Oil, Niobe Oil,
+     Bergamiol, Artificial Jasmin Oil, Artificial Cognac
+     Oil.--~Appendix.~ Table on Constants of the more Important
+     Essential Oils.--~Index.~
+
+          Price 12s. 6d. net (Post Free, 13s. Home;
+          13s. 6d. Abroad).
+
+          PUBLISHED BY
+
+          ~SCOTT, GREENWOOD & SON,~
+
+          ~8 BROADWAY, LUDGATE HILL, LONDON E.C.~
+
+
+
+
+
+
+End of the Project Gutenberg EBook of The Handbook of Soap Manufacture, by 
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