3ltt;ara, Sfem fork 
 
Cornell University Library 
 
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Cornell University 
 Library 
 
 The original of tliis book is in 
 tine Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31924031231610 
 
A 
 
 TEEATISE ON THE MANUFACTUEE 
 
 OF 
 
 SOAP AND CANDLES, 
 
 LUBRICANTS AND GLYCEEIN. 
 
TREATISE ON THE MANUFACTURE 
 
 OF 
 
 SOAP AND CANDLES, 
 
 LUBKICANTS AND GLYCEEIN. 
 
 BY 
 
 Wm. LANT CAEPENTEE, B.A., B.Sc, 
 
 FELLOW OP THE CHEMICAL AND PHYSICAL SOCIETIES; " 
 
 MEMBER OF THE PUBLICATION COMMITTEE OF THE JOURNAL OF THE SOCIETY OF 
 
 CHEMICAL industry; 
 
 LECTURER FOB THE GILCHRIST EDUCATIONAL TRUST. 
 
 AUTHOR OF ' ENERGY IN NATURE,' ETC. 
 
 87 ILLUSTRATIONS. 
 
 E. & F. N. SPON, 125, STRAND, LONDON. 
 
 NEW YORE; 35, MUERAT STREET. 
 
 1885. 
 
PEEFACK 
 
 The substance of many, of .the following pages has appeared 
 in various articles under their respective headings in Spons' 
 Encyclopsedia of Manufactures and Eaw Materials, published 
 in 1882, — articles to which the present writer largely contri- 
 buted, and for one of which (" Soap, Eailway-grease, and 
 Glycerine ") he is solely responsible. 
 
 In the present work, however, the whole subject-matter 
 has been re-arranged and very carefully revised. Great pains 
 have been taken to incorporate the latest trustworthy results 
 obtained in the various branches of which the text treats, 
 and some new illustrations have been added. 
 
 The aim of the writer, who was practically engaged in 
 these industries for several years, has been, throughout, to 
 make the work as complete and reliable a guide as possible 
 to them, and to indicate briefly but clearly the scientific 
 basis upon which alone they can be successfully conducted. 
 In the chapter upon Theoretical Principles a certain 
 acquaintance with the elements of chemistry and with 
 the language of symbols is assumed, since what is there 
 stated is intended to serve the purpose of a useful summary, 
 rather than to be a complete exposition of the theory of 
 saponification. 
 
 The author desires to express his thanks to several friends 
 for assistance rendered to him during the production of the 
 
VI PREFACE. 
 
 book, and especially to Mr. A. H. Allen, to Mr. Calderwood, 
 to his brother Mr. E. Forbes Carpenter, to Mr. C. P. Cross, 
 Mr. Leopold Field, Dr. Perkin, Mr. P. J. Worsley, and 
 Dr. C. E. A. "Wright for their kindness in revising the 
 proofs of certain chapters. Finally he is much indebted 
 to Mr. C. G. Warnford Look, editor of Spons' Encyolo- 
 psedia, for compiling the list of patents and bibliography 
 in the concluding chapters, for indexing the volume, and 
 for seeing it through the press. 
 
 Wm. lant caepentee. 
 
 36, Craven Park, 
 
 Hablesden, London, N.W. 
 May, 1885. 
 
CONTENTS. 
 
 INTEODUOTOEY NOTE. 
 
 PAGR 
 
 Historical Epitome and Eefebences .. .. . .. I 
 
 GHAPTEE I. 
 Theobetioal Pktnciples .. .. 3 
 
 , CHAPTEE II. 
 
 Eaw Materials, — Their Sources and Preparation .. .. 14 
 
 CHAPTEE III. 
 
 Raw Materials; — Eeeining, Clarifying, and Bleaching .. 70 
 
 CHAPTEE IV. 
 
 Raw Materials; — Their Proximate Analysis .. .. .. 82 
 
 CHAPTEE V. 
 Caustic Alkali, — and other Mineral Salts .. .. .. 106 
 
 CHAPTEE VI. 
 
 Manufacture of Household Soaps ; — The Process of Saponi- 
 fication .. .. .. .. .. .. .. .. 144 
 
 CHAPTEE VII. 
 
 Treatment of Soap after its Removal from the Soap Copper ; — 
 
 Household, Manufacturers', and Toilet Soaps .. .. 174 
 
Till CONTENTS. 
 
 CHAPTEE VIII. 
 
 FACE 
 
 Theoet of the Action op Soap ; — Its Valuation and Analysis. 
 
 DiSTEIBUTION AND POSITION OP THE TEADE .. .. .■ 207 
 
 CHAPTEE IX. 
 
 Lubrioatins Oils, Railway and Wasgon Grease, &o. . . . . 229 
 
 CHAPTEE X. 
 
 Candles; — Raw Materials, their Soukces and Preliminary 
 
 Treatment .. .. .. .. .. .. .. .. 237 
 
 CHAPTEE XL 
 
 Processes foe the Conversion of Neutral Fats into Fatty 
 
 Acids. — The Manufacture of Commebcial Steaein .. 253 
 
 CHAPTEE XII. 
 
 The Manufacture op Candles and Night-lights ; — Their Value 
 
 AS Illuminants .. .. .. .. .. .. .. 273 
 
 CHAPTEE XIII. 
 Glycerin .. .. .. .. ., .. .. .. 294 
 
 CHAPTEE XIV. 
 
 Summary op Patents .. .. ,. .. ,. .. .. 309 
 
 CHAPTEE XV. 
 Bibliography .. .. .. .. .. .. .. .. 330 
 
 linJEX 333 
 
SOAP AND CANDLES, 
 
 LUBRICANTS AND GLYCERIN. 
 
 SOAP. — Inteodtjctoet Note. 
 
 From the remotest times of whioli we have any record, the 
 art of softening water, and of using some substance with it, 
 for the purposes of washing and cleansing, appears to have 
 been known and adopted. The elder Pliny, who died a.d. 79, 
 gives us the earliest account of soap, as having been first 
 manufactured by the Gauls, the caustic alkali being produced, 
 from wood ashes and natural earths, presumably lime. He 
 also states that it was usually made from tallow and ashes, 
 the best being made from goats' suet and beechwood ashes ; 
 he was further acquainted with a lead soap or plaster, and its 
 use in the healing art.* The remains of a soap-factory, with 
 soap in a state of perfect preservation, are still shown in 
 Pompeii, and some of the lime from it is in possession of 
 the writer. The process of making an alkaline lye was 
 mentioned by Aristophanes (434 b.c), and by Plato (348 B.C.). 
 Moreover in the Sacred Scriptures, in Jeremiah ii. 22, we 
 read " For though thou wash thee with nitre and take thee 
 much sope." The Hebrew word borith used in this passage is 
 stated by authorities to refer to vegetable, i. e. pot-ash, lye, but 
 
 ' The quotations from Pliny are thus given by Mr. 0. P. Cross in 
 his lecture on Soap, at the Health Exhibition in Loudon in 1884 : — " Fit 
 ex sebo et cinere. Optimus £agmo et caprine ; duobos modis, spissos ac 
 liquidus." — " Molybdaena ooota cum oleo, jeoinoris colorem trahit. . . . 
 Compositio ejus est libiis tribus, et cerae libra uua, olei tribus heminis." 
 
 B 
 
^ SOAP. 
 
 in MalacH iii. 2, where reference is made to " fullers' sope," 
 the Hebrew word nether is there believed to apply to a mineral 
 lye, i. e. to soda in some form. Soap is mentioned by Geber in 
 the second century, and at a later period is frequently referred 
 to by Arab writers as being not only used for detergent 
 purposes, but also for external application. No advance was 
 made in its manufacture until the early part of the present 
 century, when the researches of Chevreul into the constitution 
 of fatty bodies, and the manufacture of soda from common 
 salt by Leblanc, established the scientific and practical basis 
 upon which the soap industry is now carried on ; these two 
 men may therefore be regarded as its founders. 
 
( 3 ) 
 
 CHAPTEE I. 
 
 THEOEETICAL PEINCIPLES. 
 
 Although soap has heen made and used for so many centuries, 
 
 the principles which should guide its manufacture harve, as 
 
 already indicated, only been discovered in quite recent times- 
 
 A proper comprehension of these principles is indispensable 
 
 to every one who would become a successful manufacturer, 
 
 because soap-making is essentially a chemical operation ; but 
 
 as they can only be dealt with very briefly here, the reader 
 
 unacquainted with them is recommended to consult any 
 
 good modern work on chemistry, or still better, and most 
 
 certainly if he intends to become a practical soap-maker, he 
 
 is advised to study the science practically, and to attend a 
 
 course of illustrated lectures on the industry. 
 
 Although, in ordinary parlance, the term " soap " denotes 
 
 simply that combination of fatty matter with alkali which, 
 
 by its detergent properties, aids in the removal of grease and 
 
 dirt in washing (in which sense alone will it be used in this 
 
 work), it is highly important to remember that " soaps " as a 
 
 class are, strictly speaking, " salts," using that term in the 
 
 chemical sense. Every salt is formed from an acid and a 
 
 base, which have opposite' properties, producing by their 
 
 iinion a third substan,ce differing from either. Thus nitre, 
 
 nitrate of potash, or potassium nitrate (all are synonymous), 
 
 may, in the presence of water,* be regarded as a compound 
 
 of nitric acid and potash, or 
 
 Salt = Acid + Base, 
 Nitre = Nitric acid + Potash, 
 
 * These words are added, hecause nitre, as such^ cannot, strictly 
 speaking, be said to contain (and therefore to be composed of) oitric acid 
 and potash. When, however, the elements of water are present, these two 
 bodies may be obtained from it, or "nitre + water = nitric acid + potash, 
 KNO, + HjO = HNO3 + KHO. 
 
 B 2 
 
4 , SOAP. 
 
 because if nitric acid and potash be mixed, nitre and water 
 are formed, and tbey may be separated from each other by 
 heat, or by allowing the nitre to crystallize. 
 
 All the neutral fats of commerce which are used in soap- 
 making, such as tallow, palm-oil, coco-nut- oil, cotton-seed-oil, 
 and many kinds of grease, are also, from a chemical point of 
 view, "salts" of which the "base" is(not potash but) glycerin, 
 and the " acid " (not nitric but) a mixture of various " fatty 
 acids," which by proper means, may, if desired, be separated 
 from each other, and prepared in a state of greater or less 
 purity. Hence (as before, in presence of water), — 
 
 Salt = Acid + Base. 
 
 Neutral fat (e. g. tallow) = Various fatty acids + Glycerin. 
 
 Theoretically, soap-making is nothing more than turning 
 out the base glycerin from neutral fats by a strong mineral 
 base, or alkali, such as potash or soda, the whole operation 
 being performed in presence of a considerable quantity of 
 water. Hence, — 
 
 Neutral fat -,- ^o^^- ^^ = { ^^^y .acid| +^Alkali, } ^ ^,^^^^_ 
 
 As, however, certain oils much used by the soap-maker 
 are already fatty acids, and contain no glycerin (e. g. oleic 
 acid, sometimes erroneously called olein, a bye-product of 
 the candle-factory, to be hereafter described), or, strictly 
 speaking, do not contain that group of elements which, 
 associated with water, produce glycerin, the formation of 
 soap from them is simply a direct combination of fatty 
 acids with the proper proportion of alkali, as in the case 
 of the formation of nitre above described. This process will 
 be dealt with in describing special soaps (Chap. VI.). 
 
 While, therefore, chemically speaking, any combination of 
 fatty acids with a mineral base may be regarded as a " soap," 
 in practice no commercial soaps are made except with potash, 
 or soda, as only those soaps are soluble in water ; all others, 
 such as those formed by the union of fatty acids with lime, 
 
THEORETICAL PRINCIPLES. 5 
 
 baryta, and magnesia, or even with the oxides of the inetals> 
 as lead, copper, ziac, &c., are insoluble in water, though some 
 of them are used in pharmacy : a " plaster," for instance, is 
 usually a soap from the fatty acids of soft oUs, with lead- 
 oxide as a base, and chemically speaking, is an oleate of lead. 
 A farther acquaintance with the theopy of salts will make 
 it clear that, in the case of mineral acids and bases there is 
 a certain definite proportion peculiar to each, in which (or in 
 simple multiples of which) they combine with each other. 
 Thus, to take the lowest proportional whole-numbers, 31 
 parts by weight of pure sodium oxide require 49 parts by 
 weight of pure sulphuric acid to form the neutral salt 
 sodium sulphate; and in the operation, 9 parts by weight 
 of water are formed, the hydrogen of which is derived from 
 the acid, and the oxygen from the base.* The combined 
 weight of the products is of course exactly equal to the sum 
 of the weights of the constituents, or, — 
 
 31 parts soda + 49 parts sulphuric acid = 71 parts sodium sulphate + 
 y parts water. 
 
 This number, called the "combining proportion" or 
 " equivalent " of each substance, is determined by chemical 
 research. Its relation to the atomic weight of the substance 
 cannot be discussed here, but it can scarcely be too strongly 
 insisted on that the fatty acids have their equivalents also • 
 thus the determination of the quantity of soda necessary for 
 their saponification is a matter of calculation, and hence the 
 varying equivalents of the different fatty acids is one part of 
 the real explanation of the fact, well known to manufacturers, 
 that the " yield " of soap is so different from various fats. 
 
 " In actual piaetioe, it would be very difficult to use tlie above weights 
 of pure sodiuTO oxide and pure sulphuric ekcid, since each of them would 
 absorb water from the air while being weighed-out. Instead of these pure 
 substances, commercial or laboratory products containing known percent- 
 ages thereof would be employed, as, for example, caustic soda and oil of 
 vitriol, and the necessary proportion of each would have to be calculated 
 on the above basis from the known composition of the substance used 
 The extra quantity of water in the caustic soda and in the oil of vitriol 
 would aot affect the result. 
 
6 SOAP. 
 
 To revert for a moment to the combination of sulphimc 
 acid fnth soda, — oonsideraUe heat is evolved in the process, 
 which has its parallel in saponification ; further, if either 
 constituent had been in excess, there would have resulted a 
 mixture of neutral sodium sulphate with the remainder of 
 whichever constituent was in excess. The fatty acids are 
 remarkable in this respect, that their combining proportions 
 or equivalents are much higher than those of mineral acids. 
 Thus to combine with 31 parts of pure soda, 284 parts of 
 stearic acid are required, 282 parts of oleic acid, 256 parts 
 of palmitic acid, and only 200 parts of lauric acid, one 
 of the chief fatty acids of coco-nut-oil. Hence, while 
 taUow gives the least "yield" of anhydrous or dry soap, 
 among the fats usually employed, coco-nut-oil gives the 
 most, and palm-oil occupies an intermediate position. 
 
 What has been said above with regard to 31 parts of soda, 
 applies with equal force to potash, replacing 31 by 47, which 
 is the lowest proportional number for potash. 
 
 From the explanation above given, it is easy to calculate 
 the quantity of soda or potash necessary to completely 
 saponify, — 
 
 100 lb. of Pure Soda. Pure Potash. 
 
 Tallow 10-50 lb. 15-92 lb. 
 
 Palm-oil ll-OO „ 16-67 „ 
 
 Cooo-nut-oil 12-44: „ 18-86 „ 
 
 Oleic add 10-52,, 15-95 „ 
 
 It is obvious that the proportion of alkaline lye * to be 
 used must be regulated by its strength ; thus, if lye contain- 
 ing 20-0 per cent, or ^ its weight of pure soda be used, 
 5 times the weights above given must be used for 100 lb. 
 fatty material. 
 
 It will be convenient here to explain briefly the causes of 
 the differences in the combining proportions of the various 
 
 * This word is variously written and pronounced, ley, lye, lie, leys, 
 lyes, lee, lees. The form lye in the singular number is obviously the 
 correct one, each of the other forms having altogether another meaning as 
 properly applied. — 0. G. W. L. 
 
THEOEETIOAL PBINCIPLES. 7 
 
 fats. Their fatty acids are all composed of the three elements, 
 carbon, hydrogen, and oxygen, comhined in different propor- 
 tions of the two first-named, hut nearly all containing the 
 same quantity of oxygen. Most of them may he arranged 
 in a series, known as the acetic, or sometimes as the fatty 
 series, of which the lowest term, formic acid, contains 
 12 parts by weight of carhon, 2 parts hydrogen, and 32 
 parts oxygen. The other terms of the series differ from 
 each other by 12 parts carbon and 2 parts hydrogen. 
 The table on p. 8 gives some of the principal terms 
 of this series, 0„Hj„02, from which it is clear that the 
 differences in their equivalents are due to the differences in 
 the quantities of carbon and hydrogen entering into their 
 composition, which also affect their melting- and boiling- 
 points. 
 
 The fatty acid of the fluid constituent of most natural fats 
 and oils, called oleic acid, belongs to another series, C„H2o_202, 
 known as the " acrylic," of which only a few terms are known ; 
 its formula is C13H34O2, and its equivalent is 282. Another 
 term of this series is brassic acid, C22H42O2, one of the chief 
 constituents of rape-oil. 
 
 A slight acquaintance with the theory of salts in mineral 
 chemistry shows that there are certain acids, such as phos- 
 phoric acid, which require three equivalents of base to every 
 one of acid to completely saturate them, and to form a neutral 
 salt. Such acids are called Tribasic. In like manner, it will 
 shortly be shown that three equivalents of a fatty acid are 
 required to form a neutral fat with one equivalent of glycerin, 
 which may therefore be called a " Tri-acid base." This being 
 so, the process of the saponification of a neutral fat by caustic 
 soda may be represented thus : — 
 
 . .g 03H,(C.,H„0,).+3NaHO = 3(C,3H,ANa)-|-C5H,(OH), , ^ 
 
 ■S ^ € "^ Tristearin. Caustic soda. Sodium stearate Glycerin. .S ^'r^ 
 g,^.^| or soap. g.gg 
 
 $«.§§ 890 -I- 120 = 918+92 CM 
 
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 ooooooo 
 
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 T!f<COQOrHCOTjitOI>a)Oi-i(N'*iOCO)-t»« 
 
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THEOBETIOAL PRINCIPLES. » 
 
 It will he noticed that in this decomposition, the elements 
 of water are taken up, so as to form glycerin. So also 
 where a soap is decomposed hy any mineral acid, the hydro- 
 gen replaces the alkaline metal (usually sodium), and water 
 again takes part in the reaction. Hence (as seen in the 
 table on p. 11), the sum of the fatty acids and glycerin ob- 
 tained from a neutral fat considerably exceeds the original 
 weight of the fat. The term hydrolysis is now often applied 
 to such decompositions of neutral oils. 
 
 It has been said that neutral fats may be regarded chemi- 
 cally as " salts," in which glycerin is the base, and a series 
 of complex fatty acids, the acid, and that the process called 
 saponification consists in displacing the base glycerin by the 
 stronger base soda or potash. There is, however, another 
 point of view from which neutral fats may be considered, 
 viz. as the compound ethers of the trivalent alcohol, 
 glycerin. This point will be best illustrated by a reference 
 to the relations between ordinary alcohol and its compound 
 ethers. For example, when alcohol is saturated with hydro- 
 chloric acid gas, and the product is distilled, a colour- 
 less ethereous liquid is condensed, known as hydrochloric 
 ether, chloride of ethyl, or ethyl chloride. The reaction may 
 be thus expressed, — 
 
 Alcohol 4- Hydioehlorio acid = Hydroohlorio ether -1- Water 
 CjHsCHO) + HCl = CjHsCl +HjO, 
 
 from which it will be seen that the difference between 
 alcohol and hydrochloric ether consists in the replacement 
 of the group (HO) by the element chlorine, CI. It will be 
 observed that in this alcohol there is only one (HO) which 
 can thus be replaced, and hence only one such compound 
 ether can be formed from ordinary alcohol and hydrochloric 
 acid. 
 
 If, however, glycerin be similarly treated with hydro- 
 chloric acid gas, it will be found possible to replace three 
 successive groups of (HO) with three successive portions 
 of chlorine, and to form three different compounds, whose 
 
10 SOAP. 
 
 boiling points are some distance apart, as is shown in the 
 following table. 
 
 Glycerin. Water. Boiling point. 
 
 C3H5(OH)3+ HC1= H^O+OsHsCOBOjClorChlorhydrin 440^° F. (227° 0.) 
 CjHs(0H)3+ 2HC1 = 2HjO+ CaHsCOH)^, or Dichlorhydrin 352^° F. (178° 0.) 
 03H5(OH)3 + 3HCl=3H20+C3H5Cl3 or TriolilorhydrmSll °F.(155°C.) 
 
 Glycerin; therefore, as a trivalent alcohol, forms three dis- 
 tinct classes of ethers, just as the tribasic phosphoric acid 
 forms three distinct classes of salts, with three different 
 proportions of the same base, or even with three different 
 
 Similarly, if acetic acid, one of the lowest terms of the 
 series of acids to which it gives its name (p. 8), be made to 
 react on glycerin, we have the three compounds, — 
 
 C3Hs(OH)3-l- C^HjOi, = HjO + G,li^(OH\, G^Bifi^ Monacetin. 
 C3H,(OH)3 + 2G,Il,0^ = 2H,0 + G,n,(PH.), 202H30j Diacetin. 
 C3H5(OH)8 + SOjHiOj = 3H2O-I-O3H5, 3O2H3O2 Triaoetin. 
 
 Now it has been shown by Berthelot that if the higher 
 terms of the fatty acid series be allowed to react upon 
 glycerin under suitable conditions, a precisely similar series 
 of compounds may be formed in exactly the same way. 
 Hence if glycerin be regarded as an alcohol containing the 
 trivalent radicle C3H5, and stearic acid be taken as an 
 example, the relationship between glycerin and mono-, di-, 
 and tri-stearin may be thus expressed, — 
 
 Glycerin. Monostearin. Distearin. Tristearin. 
 
 c3Ha}03 c:|:a}o3 2&3|30,jo3 3a:5aA}°'- 
 
 Although the first two terms of this series, whatever be 
 the fatty acid employed, are merely chemical curiosities, 
 interesting from their constitution alone, the third term in 
 each case is very important commercially, inasmuch as 
 nearly all neutral fats are built up on the lines indicated 
 in that term, or in other words, tallow is mainly composed 
 of tristearin and triolein, and so on for other fats and oils. 
 
THEOBETICAL PEINCIPLES. 11 
 
 The following short table gives the formulae, on this view, of 
 some of the more important and illustrative memhers of the 
 series, — 
 
 Products of 
 
 SapoQiiication of 
 
 100 parts. 
 
 Molecular Fatty rn™™-- 
 weight. acid. Gly«nn- 
 
 Tristearin CJl^(,OCuB,fi\ Tallow 890 95-73 10-34 
 
 Triolein CsHsCOCijHjjO), „ 884 95-70 10-40 
 
 Tripalmitin CaHsCOCuHjiOX Palm-oil 806 95-28 10-74 
 
 Tririoinolein CaHjCOCisHjsOjjCastor-oa 932 
 
 Trilinolein CaHsCOCiaH^O^a Linseed-oil 794 
 
 Tributyrin OsHjCOC, H, 0), Butter 302 
 
 Triacetin OjHsCOO^ Hj O), Cod-liver-oil 218 
 
 It must he borne in mind therefore, that the object of the 
 soap-maker is to replace the whole of the glycerin in the 
 tristearin, triolein, &c., of natural fats, by the proper com- 
 bining proportion or equivalent of either soda or potash, 
 according to the kind of soap desired, and that the more 
 perfectly and the more accurately this can be done, the 
 purer and the more satisfactory will be the ultimate com- 
 mercial product. 
 
 It may be convenient here to point out that for the pro- 
 duction of a large class of soaps, and in particular of that 
 known as Yellow, or Household soap, rosin, or colophony, is 
 largely employed. Chemically speaking, rosin is a mixture 
 of acids (pinic, sylvic, colophonic, and pimaric) whose 
 general formula is CjoHgoOj, and their combining pro- 
 portion (with 31 parts pure soda) is 302. According to 
 another authority, ordinary commercial rosin is said to 
 consist chiefly of abietic anhydride, C44H52O4, from which 
 sylvic acid may be obtained by acting upon it with 
 sulphuric acid. The difiSculty, however, of isolating and 
 analysing these complex acids is very great, and the whole 
 subject will well repay a careful investigator. Eosin de- 
 composes alkaline carbonates, and combines instantly with 
 caustic alkalies, forming in each case a so-called rosin soap, 
 which, when soda is employed, is a thick, slimy, brown mass, 
 containing 15 "8 per cent, of pure soda; its attraction for 
 
10 SOAP, ( 
 
 / 
 
 boiling points are some distance apart, as is shown in the 
 following table. 
 
 Glycerin. Water. BoUing point. 
 
 C3H,(0H),+ HC1= H3O+C3H5(OH)201orChlorhydrm 440i° F. (227° C.) 
 C3H5(OH),+2HCl=2H20+CaH5(OH)GljOrDiohlorhydrin352|°P.(178°0.) 
 C3H5(OH)3+3HCl=3H,O+C3H50l3 or TriolxlorhydimSll °F. (155°0.) 
 
 Glycerin, therefore, as a trivalent alcohol, forms three dis- 
 tinct classes of ethers, just as the tribasic phosphoric acid 
 forms three distinct classes of salts, with three different 
 proportions of the same base, or even with three different 
 bases. 
 
 Similarly, if acetic acid, one of the lowest terms of the 
 series of acids to which it gives its name (p. 8), be made to 
 react on glycerin, we have the three compounds, — 
 
 C3H5(OH)3+ C^HjOj = HjO + 03H5(OH)2, C^HaOj Monacetin. 
 G3H,(0H)3 + 20jH,02 = 2H2O + CsHsCOH), 2C2H30j Diacetin. 
 CjHsCOHX + 3CjH,02 = 3H2O + O3H5, 302H30j Triaeetin. 
 
 Now it has been shown by Berthelot that if the higher 
 terms of the fatty acid series be allowed to react upon 
 glycerin under suitable conditions, a precisely similar series 
 of compounds may be formed in exactly the same way. 
 Hence if glycerin be regarded as an alcohol containing the 
 trivalent radicle C3H5, and stearic acid be taken as an 
 example, the relationship between glycerin and mono-, di-, 
 and tri-stearin may be thus expressed, — 
 
 Glycerin. Monostearin. Distearin. Tristearin. 
 
 C3fj03 o:|:a}o3 2o:3|:a[o3 sqLhu}^- 
 
 Although the first two terms of this series, whatever be 
 the fatty acid employed, are merely chemical curiosities, 
 interesting from their constitution alone, the third term in 
 each case is very important commercially, inasmuch as 
 nearly all neutral fats are built up on the lines indicated 
 in that term, or in other words, tallow is mainly composed 
 of tristearin and triolein, and so on for other fats and oils. 
 
THEORETICAL PEINCIPLES. 11 
 
 The following short table gives the formulffi, on this view, of 
 some of the more important and illustrative members of the 
 series, — 
 
 Products of 
 
 Saponification of 
 
 100 parts. 
 
 Molecniar Fatty r'i„„.„-„ 
 weight. acid. Glyccnn. 
 
 Tristearin C^a^iOGigB^fi), Tallow 890 95-73 10-34 
 
 Triolein CaHjCOOigHajO), „ 884 95-70 10-40 
 
 Tripalmitin CaHsfOCuH^O), Palm-oa 806 95-28 10-74 
 
 Triricinolein CaHsCOCigHjjOj), Castor-oil 932 
 
 Trilinolein OaHsCOCieHj^O), Linseed-oU 794 
 
 Tributyrin CsHsCOC, H, 0)3 Butter 302 
 
 Triacetin CaHsCOOj H3 O)^ Cod-Uver-oil 218 
 
 It must he borne in mind therefore, that the object of the 
 soap-maker is to replace the whole of the glycerin, in the 
 tristearin, triolein, &c., of natural fats, by the proper com- 
 bining proportion or equivalent of either soda or potash, 
 according to the kind of soap desired, and that the more 
 perfectly and the more accurately this can be done, the 
 purer and the more satisfactory will be the ultimate com- 
 mercial product. 
 
 It may be convenient here to point out that for the pro- 
 duction of a large class of soaps, and in particular of that 
 known as Yellow, or Household soap, rosin, or colophony, is 
 largely employed. Chemically speaking, rosin is a mixture 
 of acids (pinic, sylvio, colophonic, and pimario) whose 
 general formula is CjoHajOj, and their combining pro- 
 portion (with 31 parts pure soda) is 302. According to 
 another authority, ordinary commercial rosin is said to 
 consist chiefly of abietic anhydride, GiJ3.^2^^, from which 
 sylvic acid may be obtained by acting upon it with 
 sulphuric acid. The difficulty, however, of isolating and 
 analysing these complex acids is very great, and the whole 
 subject will well repay a careful investigator. Bosin de- 
 composes alkaline carbonates, and combines instantly with 
 caustic alkalies, forming in each case a so-called rosin soap, 
 which, when soda is employed, is a thick, sUmy, brown mass, 
 containing 15 '8 per cent, of pure soda; its attraction for 
 
12 SOAP. 
 
 water is so great as to cause it to become semi-liquid on 
 exposure to air, even though previously dried artificially. 
 
 It is well known that when many substances, whether 
 elements or compounds, pass from the liquid to the solid 
 state, they assume a more or less crystalline form, charac- 
 teristic of each substance. Thus metals crystallize from a 
 state of fusion, and most salts from a state of solution. 
 The same is true, to a greater extent than is generally 
 supposed, in the case of the alkaline salts of the acetic series 
 of acids, i. e. both in hard and soft soaps. The appearances 
 known as " grain " or " strike " in a hard soap, and " fig " 
 in a soft soap, are due to the crystalline character of soap, 
 and are largely influenced by the quantity of water present. 
 Ordinary salts, when crystallizing, take up a certain quantity 
 of water, which is definite, invariable, and necessary to 
 the crystalline structure of the salt. When they lose this 
 water of crystallization in either dry or warm air, they lose 
 also their crystalline structure, and usually become amorphous. 
 The same thing happens, to a less extent, with soap ; but 
 owing to the peculiar state of aggregation of the soap- 
 crystals, the loss of water does not appear to be attended by 
 any change in structure. 
 
 , This difference in their behaviour to water, between the 
 potash and soda soaps of the same fatty acids, is very re- 
 markable, and lies at the root of the distinction between hard 
 (or soda), and soft (or potash) soaps. The soda salt, on ex- 
 posure to air, will gradually lose nearly all its water, at a 
 rate depending upon the dryness and temperature of the air. 
 The potash salt, on the other hand, never becomes thus dry, 
 but retains enough water to form a soft slimy jelly, and if it 
 is artificially desiccated, it absorbs large quantities of water 
 from the air, often amounting to half as much again as the 
 weight of the dry soap. This difference is best seen in the 
 case of the salts of pure fatty acids thus : — 
 
 100 parts dry potasaium oleate absorb 162 parts water from the air. 
 100 „ „ potaBsium palmitate „ 35 „ „ 
 
 100 „ „ sodium stearate „ 7i „ „ 
 
THEORETICAL PRINCIPLES. 13 
 
 It will be oonTenient here to consider another physico- 
 chemical property of soaps, of great practical importance to 
 the soap-boiler. The property referred to is the behaviour 
 of soap to various saline solutions, and although not instru- 
 mental in saponification, it is almost essential in separating 
 the foreign matter which would otherwise render hard 
 soap impure ; it is also influential in controlling the amount 
 of water therein. Although soda soaps are soluble in water, 
 they are not soluble in a solution of common salt, nor of caustic 
 soda. If, therefore, common salt be added to a solution of 
 soap (or even of partially saponified fat) in water, the salt 
 dissolves, and turns the soap out from its state of solution, 
 in the form of small flakes which collect together and float 
 on the surface of the salt solution, by virtue of their less 
 sp. gr. The same thing happens when a strong solution of 
 caustic soda is added to soap in an aqueous solution, or, more 
 gradually when a solution of soap in water containing excess 
 of caustic soda, or some amount of sodium chloride, is con- 
 centrated by the evaporation of its water, as when a soap- 
 copper is boiled by fire or close steam. The addition of salt 
 (or of strong lye), therefore, to soap containing an excess 
 of water, removes the superfluous water, and, in chemical 
 language, precipitates the soap from it. Soap so precipitated 
 contains 35—40 per cent, of water. When the fatty matter 
 employed contains coco-nut- or palm-kemel-oils, more salt 
 (or soda lye) is required for this operation than when those 
 oils are not used. 
 
 It may also be noted here that if common salt, i. e. sodium 
 chloride, be added to a potash soap in solution, an interchange 
 of acids and bases takes place, soda soap being formed, and 
 potassium chloride left in the solution. This process has 
 been actually used for the fabrication of hard soaps in 
 Germany, where potash salts have at times been very 
 abundant. 
 
 The chemical principles which are involved in the pre- 
 paration of the lye, or solution of caustic soda or potash, for 
 use in soap making, will form the subject of Chap. V. 
 
16 
 
 SOAP. 
 
 Pig. 1. 
 
 animal tissue whicli contains them is usually termed " render- 
 ing," as applied to the fats themselves. These fatty matters 
 are contained in animal tissue, into whose composition water 
 largely enters. The simplest method of separating them, from 
 each other is by heating the fat in an open pan over a fire, at 
 a temperature considerably above the boiling-point of water, 
 
 212° r. (100° C), con- 
 stantly stirring the mass, 
 whereupon the animal tis- 
 sue dries and cracks, al- 
 lowing the pure fat to run 
 out, and become separable 
 by mere straining. This 
 process, however, requires 
 careful watching, as the 
 tallow is apt to be dis- 
 coloured by overheating, 
 and unless the fat be very 
 new, it is certain to evolve 
 noxious odours. 
 
 The methods employed 
 on a large scale may be 
 divided into two, according 
 as it is desired to save the 
 animal tissue in a solid 
 form, or not. If it be so 
 desired, a very suitable 
 apparatus is that used by 
 Dole, of Bristol, and made 
 by Miles, engineer, Brisiiol, 
 shown in Pig. 1. The apparatus consists of a strong iron 
 cylinder a, provided above vnth a charging-hole 6, closed 
 by a sliding cover ; a man-hole near the bottom, for the 
 discharge of solid refuse ; 2 taps c for drawing off pure 
 fat; water feed-valves d; steam feed-valves e; and water 
 draw-off valve/. Steam at a pressure of 60-80 lb. is intro- 
 duced at e, and circulates in the coil g below the perforated 
 
 I 
 
 a 
 
BAW MATERIALS. 17 
 
 false bottom h, d supplying water wlien necessary. The vent- 
 tap * regulates the pressure, and permits the blowing off of 
 steam. The apparatus heing charged, steam is introduced 
 for 6-8 hours. With a heavy charge, the fat can be drawn 
 off by the upper of the taps c, being floated to that level if 
 necessary by letting in water. With a light charge, it is con- 
 sidered better to draw off all liquids together by the lower 
 tap c, and skim off the fat when cold. The apparatus is 
 strengthened by a stay-bolt h, and has a stage at I, 
 
 When it is desired to obtain the very finest and purest 
 tallow, for the manufacture of toilet soaps of the first 
 quality, some modification of one of the three following 
 methods, which are used in the early stages of the manufac- 
 ture of butterine, may be adopted with advantage. The 
 residual matters, however, in all cases contain some amount 
 of inferior tallow, and they should therefore be subsequently 
 " rendered " by one of the ordinary processes. 
 
 A method which is very extensively employed in the 
 United States consists in thoroughly washing the picked beef- 
 suet in water, and placing it in a steam-jacketed pan ; the 
 contents are never allowed to experience a temperature exceed- 
 ing 120° F. (49° C). The pure fat that runs off is « seeded " 
 (i. e. allowed to cool very slowly, which facilitates the 
 mechanical separation of the stearin) and pressed. The 
 resulting stearin may be sold for candle-making purposes, 
 while the liquid portion (oleomargarin) is fit for the manu- 
 facture of butterine, or for any purpose for which a very pure 
 fat is required. 
 
 Another arrangement is adopted by W. Cook and S. Hall, 
 of the East London Soap-works, Bow. The freshest beef-su^t 
 is first thoroughly disintegrated and reduced almost to a pulp. 
 A wooden chamber is provided, of sufficient height to accom- 
 modate a workman, and with a passage up the centre. At 
 the two sides, are inclined racks ; upon these, shallow iron 
 trays are slid in from the outside, and rest with a slight 
 slope towards the central passage. Along the lower free 
 edge of each row, is an open iron gutter, leading to a receiver 
 
 
 
 / 
 
18 SOAP. 
 
 outside. Tlie comminuted fat is laid in ttiil layers upon 
 the trays, and tke temperature of the chamber is raised by 
 steam-pipes to such a degree as will just suffice (and no more) 
 to liquefy the fat, which then escapes by the gutters to the 
 receiver, leaving behind such shreds and portions of tissue 
 as are not liquefied by the heat. The temperature should 
 never exceed 130°-135° F. (54°-57° C), and a much lower 
 degree will be equally effective if sufficient time be allowed. 
 
 The third process originated from a surmise of the emiaent 
 French chemist Mege-Mouries, that the formation of butter 
 contained in milk was due to the absorption of fat contained 
 in the animal tissues. This led to the experimental splitting- 
 up of animal fats, with the result that a process was devised 
 by which the olein and margarin contained in the fat could 
 be almost completely separated on a commercial scale from 
 the stearin. This process consists in heating finely-minced 
 beef-suet with water, potassium carbonate, and finely-chopped 
 fresh sheep's-stomachs, at a temperature of 113° F. (45° C), 
 when the combined influence of the pepsine of the sheep's- 
 stomachs, and the heat, causes the separation of the fat from the 
 cellular tissue. The fatty matters are removed, cooled, and 
 submitted to powerful hydraulic pressure in the cold, which 
 effects their separation into a solid and a liquid portion, 
 the former being stearin, a commercially valuable article, and 
 the latter the olein and margarin, or oleomargarin, required 
 for making the artificial butter. This is the process patented 
 by Mege-Mouries, and under which a large quantity of 
 butterine is made. The disadvantages of all these processes 
 are the necessity for the comminution of the fat, and the length 
 of time required by the process, i. e. the large amount of plant 
 necessary to " render " a few tons of rough fat. Their advan- 
 tages are the almost complete freedom from noxious vapours 
 (hence they are strongly recommended by the Government 
 factory-inspectors), and the great purity of the product. 
 
 "When the saving of the animal tissue is a matter of no 
 moment, it is better to " render " the fat in the presence of 
 water and steam. This can only be completely done under 
 
EAW MATERIALS. 
 
 19 
 
 slight pressure (boiling the commimited fat upon water in 
 an open vessel only extracts part of the taUow, &o.), and is 
 most suitably effected in a vessel such as that shown in Fig. 2. 
 
 Pig. 2. 
 
 o 2 
 
20 SOAP. 
 
 The apparatus consists of a series of steam-tight cylinders of 
 1200-1500 gal. capacity, formed of boiler-plate, with a 
 length ahout 2^ times as great as the diameter, and pror 
 vided -with false bottoms. The operation proceeds thus : — 
 The cylinder is fed through the man-hole E with crude fatty 
 matters to within about 2^ ft. of the top. The man-hole is 
 secured, and steam is admitted by the foot-valve into the 
 perforated pipe 0. The safety-valve is set at the required 
 pressure, and frequent testing of the state of the contents 
 of the cylinder is made by opening the try-cock E. An ex- 
 cess of condensed steam in the cylinder will be indicated by 
 the spurting ejection of the fatty matters, when the regu- 
 lating-cock X must be opened, and the condensed steam be 
 drawn off into the tub T, till the escape of fatty matter 
 from E has ceased. After 10-15 hours' continued steaming, 
 the steam is shut off, and such as remains uncondersed in 
 the cylinder is let out by the try-cock and safety-valve. 
 The fatty matters then gradually separate out and form the 
 uppermost layer, and are drawn off through the cocks p into 
 ordinary coolers. The fat being emptied from the cylinder, 
 the cover P is raised by the rod G from the discharging- 
 hole B, and the residue falls into the tub T. Should the 
 residue retain any fat, it is returned to the cylinder with 
 the next charge. The pressure of steam commonly used is 
 50-75 lb. a sq. in., sometimes advancing to 100 lb., though 
 this last figure is excessive, and calculated to injure the 
 quality of the fat by decomposing the animal matters pre- 
 sent. The yield obtained is considerably greater than by 
 the ordinary methods, being stated at 12 per cent, extra for 
 lard, and 6 per cent, for tallow. On the other hand, it is 
 almost necessary to wash the fat with fresh water, and re- 
 melt and settle or strain it, to remove the last traces of 
 animal matter held in suspension by the unseparated water, 
 and having a tendency to putrefy. 
 
 Another modification of the steam process is to subject the 
 rough fat to the action of about J its bulk of water, con- 
 taining 2-3 per cent, of sulphuric add, boiling the whole by 
 
EAW MATERIALS. 21 
 
 Bteam at atmosplieric pressure, i. e. in an open, or loosely 
 closed, lead-lined tank. There exists, however, a prejudice 
 against tallow or lard in whose preparation any " chemicals " 
 have heen used. 
 
 In all cases, it is highly desirahle to render the fat as soon 
 as possible after its removal from the animal's body, since the 
 animal tissue rapidly decomposes, and sets up fermentation, 
 producing rancidity in what would otherwise be a neutral 
 fat, and injuring the colour, &c., of the ultimate product. 
 The different kinds of fat should also be sorted, and each 
 description melted separately. In large establishments, such 
 as the Union stockyards of Chicago, the stockyards at 
 St. Louis, and the packing-houses of Cincinnati, where 
 thousands of beasts are killed every day, there is a row of 
 these digesters, each one allotted to its own kind of fat, 
 which is placed therein a few minutes after the death of the 
 animal. In this way is secured great uniformity in the 
 various grades of tallow and lard produced. The waste 
 liquor, containing large quantities of nitrogenous matter, is 
 sold for manure. 
 
 Many soap-makers " render " rough fat in a soap-copper, 
 by the simple action of wet steam upon it, while the cover 
 of the copper is secured by bolts or weights. When all the 
 tallow has been skimmed off, a weak impure solution of 
 caustic soda and common salt, technically known as " half- 
 spent lye,'' is run in, and the whole is boiled. The object is 
 to saponify the last remaining portions of tallow, and the 
 discoloured imperfect soap is used in lower grades of the 
 pure article. The process, however, is a wasteful one, since 
 large quantities of the soda are used up in forming ammonia, 
 by its action upon the nitrogenous animal tissue, and this 
 ammonia, being volatile, escapes with the noxious vapours, 
 and thus a valuable fertilizing agent is lost. As far as 
 concerns the avoidance of noxious odours, rendering by steam 
 has undoubted advantages, and it is altogether a more rapid 
 and satisfactory process. 
 
 The foregoing descriptions of the various processes for the 
 
22 ' SOAP. 
 
 " rendering " of beef-, mutton-, and pig-fat (for the produc- 
 tion of lard), apply equally, mutatis mutant, to that of 
 kitchen-stuff, ships' grease, &c. In these cases, however, the 
 liability to rancidity, and production of noxious fumes, is 
 much greater than with fresh fat. 
 
 The nature and qualities of commercially pure tallow vary- 
 greatly. The most important constituents are stearin and 
 olein; stearin predominates, but its proportion fluctuates 
 with the species, age, and sex of the animal, the portion 
 of its body which afforded the suet, and the nature of its 
 food. Ordinary fodder produces the hardest tallow, while 
 animals fed on brewery refuse, &o., give quite a soft fat. 
 Beef-tallow usually contains less stearin than does either 
 mutton-, or venison-, and mutton-tallow is always whiter 
 than beef-tallow, but S. American beef-tallow presents the 
 curious exception of containing more stearin than S. Ameri- 
 can mutton-tallow. The hardness and melting-point have 
 an equal influence upon the value of the tallow, and exhibit 
 the same want of constancy under similar changes of condi- 
 tion. The degree of solidity is largely influenced by the 
 food, increasing as the latter is drier. Pure tallow is white 
 and almost tasteless, but much of that imported has a yellow 
 tint. It dissolves in about 40 parts of boiling alcohol, sp. gr, 
 ■ 82- Nearly half its weight is olein, the remainder being 
 chiefly stearin ; 100 parts of it yield by saponification 94 "5 
 parts of fatty acids, whose solidifying-point varies from about 
 110° to 122° r. (43°-50° 0.), according to the locality and the 
 circumstances of its production. According to Dr. Hager, 
 its specific gravity varies thus, at 58°-60° P. (15°-16° C.) :— 
 Beef, 0-925-0 -929; mutton, 0-937-0 -940; beef and mutton 
 mixed in equal proportions, - 936-0 - 938. When exposed to 
 the air, it gradually undergoes the change known as ran^ 
 cidity, becoming very white, and developing a peculiar and 
 characteristic smell. In this condition it should be carefully 
 avoided by the soap-maker, because the acids which are 
 formed produce brownish-red compounds with soda, seri- 
 ously discolouring the soap, or in technical phraseology, the 
 
EAW MATEEIALS. 23 
 
 rancid tallow " works foxy." No satisfactory process has yet 
 been discovered for removing these complex acids from 
 tallow, hence tallow which is contaminated hy them shonld 
 be relegated to the candle-maker, for even as a lubricant it 
 would be very objectionable in use, owing to the action of 
 the free acid upon the metal.* It is worthy of note that 
 the more perfectly a tallow is rendered, the less liable is it 
 to undergo this change, since the minute portions of nitro- 
 genous matter left in it, appear to act as ferments in pro- 
 moting those chemical changes, chiefly caused by oxidation, 
 ■which result in the formation of these complex acids. 
 
 In commerce, tallow occupies a very important place. 
 Eussia exports immense quantities, chiefly from the ports of 
 Cronstadt, Odessa, and Taganrog. A dozen years ago, 
 Eussia's annual production was reckoned at 160,000 tons, half 
 of which was consumed locally. The home consumption has 
 since much increased. Thus the exports were 3,249,802 
 poods (of 36 lb.") in 1866 ; they gradually fell to 411,585 poods 
 in 1875, recovered to 1,110,729 poods in 1877, and dropped 
 back to 619,301 poods in 1878. Eussian tallow is nearly all 
 beef, and comes chiefly from Siberia and the Ukraine. It is 
 transported in casks of 300-400 kilo. The commercial quota- 
 tion of " P.Y.C. tallow " (Petersburgh Yellow Candle) is a 
 fiction, and does not regulate the market-price of tallow ; 
 it is a mere speculative medium, thousands of casks being 
 bought and sold that have no existence whatever. Eussian 
 tallow has lost much of its hold on the market, and now forms 
 but a small item in the total consumption in this country, 
 notably in the case of the soap- and stearin-makers, for whose 
 purposes it is less suited than for " dips." The States of 
 S. America afford very large quantities of tallow from the 
 carcases of animals slaughtered principally for the sake of 
 this product and their skins, bones, and horns. It is gene- 
 rally known as " Eiver Plate " tallow, and is mostly shipped 
 from the Eio de la Plata. It has a strong yeUow colour, but 
 
 * This will be further alluded to in the chapter on Lubricants. 
 
24 SOAP. 
 
 is of good quality ; it first arrived in serons of hide, Imt now 
 comes in old wine-casks — ^pipes and half-pipes. The United 
 States ship considerable quantities of tallow to Europe, 
 chiefly from New York and New Orleans. It is usually^ 
 known in the trade as North American, and as Western, 
 tallow, the former being packed in large drums, and th« 
 latter usually in barrels. Western tallow is frequently 
 irregular in colour, but much harder as a rule than the 
 other variety, which is too often mixed with softer fats, and 
 the whole sold as " Prime Butchers' Association Tallowi' 
 Another great source of tallow, especially in recent years, 
 is Australia, many hundreds, and even thousands, of casks of 
 colonial tallow being disposed of at the weekly public sales 
 in London. The production of tallow in the United King-^ 
 dom has been estimated at 100,000 to 120,000 tons yearly) 
 Sniall supplies occasionally are received from China and 
 Japan, the East Indies, the tallow from whence is very 
 hard but bad in colour, from Turkey, Holland, Belgium,; 
 the Falkland and Sandwich Islands, and many other places. 
 Our total annual imports of tallow and stearin fluctuate 
 between 50,000 and 65,000 tons. ^ 
 
 Lard and. Ijard-oil. — The fat of the pig, freed from the 
 ciellular tissue in which it is contained, is known as " lard." 
 The pieces of adipose tissue are sometimes salted a little to 
 keep them sweet, and are stored in barrels. They are scored 
 and sliced till they do not exceed about 1 in. in diameter, and 
 thrown into caldrons. The common method of " render- 
 ing " the lard, among very small fat-melters, is by means of 
 boiling with water in an open cast-iron vessel exposed to the 
 direct heat of a fire. The use of a steam-jacketed pan and 
 injected steam, as described on p. 19, is universal in the 
 great American centres. Whatever plan be pursued, the 
 oil is liberated from the tissues, and forms a layer on the sur- 
 face of the mass ; it is drawn off while still warm and liquid, 
 and received in the vessels in which it is to be stored and trans- 
 ported. These vessels are bladders in the case of superior 
 qualities, and little wooden kegs for inferior sorts. The 
 
EAW MATERIALS. 25 
 
 fat immediately surroiinding the kidneys yields tlie best and 
 purest lard. This, and that which is obtained in flaky layers 
 between the flesh and the skin of the animal, is known as 
 "leaf" lard, and is kept separate from the rest, being much 
 more valuable — harder and less fusible. Second-quality lard 
 (which, in reality, is the ordinary commercial first quality of 
 wholesale quotations) is used for the production of lard-oil ; 
 the third quality, from trimmings which have become 
 slightly tainted, is employed for making low-grade oil or for 
 soap. The best pure lard should be moderately firm and 
 white ; the degree of firmness entirely depends upon tem- 
 perature and the molecular condition [unless stirred while 
 cooling, or exposed to very great cold in a refrigerating-room, 
 it is usually " seedy " and sloppy, even at as low a tempera- 
 ture as 50° F. (10° C.)] ; when melted, it is as clear and 
 transparent as water ; completely free from taste and smell ; 
 liquefiable at about 212° F. (100° C.) without ebullition, or 
 affording a particle of deposit ; and containing never more 
 than 2 per cent, of either water or salt (good American lard 
 has no salt, and not above • 5 per cent, of water). Its com- 
 position, according to Braconnot, is 38 per cent, of stearin 
 and margarin, and 62 per cent, of olein ; 100 parts of it by 
 saponification yield 9 parts of glycerin and 94 '65 parts 
 stearic and oleic acids. The solidifying-point of the fatty 
 acids of lard is about 106° F. (41° C). Lard dissolves in 
 36 parts boiling alcohol at 0*816 sp. gr. According to 
 Dr. Hager, the sp. gr. of lard is 0-931-0 -932 at 58°-60° F. 
 (15°-16° C.) when fresh, and 0-940-0 -942 when old. 
 
 The lard produced in the United Kingdom is chiefly Irish. 
 Of European countries, Eussia, Hungary, and Servia hold the 
 foremost position. Hungarian lard is supplied to the whole 
 Continent ; many of the pigs are so lean as to be useless for 
 food, and some establishments in Budapest boil down ^ million 
 yearly for the lard alone. Pig-keeping is the leading indus- 
 try of Servia, and large supplies of lard may be expected 
 from that country in the near future. At present, America 
 is the chief producer. In the United States, the average 
 
26 SOAP. 
 
 yield of lard from eacli pig was 25 lb. in 1862, and 37 J lb, 
 in 1874. The total exports of lard from the United States 
 in 1870 were but 35,809,000 lb.; in 1878, they reached the 
 enormous figure of 342,668,000 lb., value 30,014,000 dollars 
 (of 48.), but fell to 326,659,000 lb. in 1879. Our total annual 
 imports of lard vary between 33,000 and 45,000 tons. 
 
 " Lard-oil " is prepared by placing the lard in woollen bags 
 between wickerwork and the plates of hydraulic presses, 
 where it is left for some 18 hours under a pressure of about 
 10 cwt. a sq. in. in the cold. The oil or liquid portion (olein) 
 is thus expressed in a pure, colourless, and limpid state, 
 in the proportion of 62 per cent, of the weight of lard. It 
 remains liquid even in the presence of great cold. It 
 is largely used for adulterating olive-oil in rrance, and 
 sperm-oil in the E. States of America ; it is esteemed as 
 a lubricant, and is said to be also used for illuminating. In 
 Cincinnati, there are some 40 manufactories, turning out 
 about IJ million gal. of this oil annually. The production 
 of lard-oil in the United States in 1875 was 8,552,583 gal. 
 The so-called " lard-stearin " left in the presses is frequently 
 used as a substitute for tallow in the soap-pan, when the 
 price of it is suitable. 
 
 Horse -grease or Mares' -grease. — Quantities of this 
 article are shipped from S. American ports. It has about the 
 same consistency as ordinary commercial American lard, and, 
 except for its inferior colour, it has practically a like value for 
 the purposes of the soap- and candle-maker. 
 
 Bone-grease or Bone-tallow. — Bones invariably 
 contain a certain amount of fat, which must be extracted as 
 a preliminary to any other process needed to fit them for 
 their various uses, and this fat is so largely employed in the 
 manufacture of soap that it is not uncommon to find the two 
 industries of bone-boiling and soap-making united. All 
 kinds of bones should not be boiled indiscriminately toge- 
 ther, both because the bones themselves will be devoted 
 to different purposes, and because the qualities of the fat 
 produced will also be various ; hollow buUocks' shank-bones 
 
EAW MATERIALS. 
 
 27 
 
 Fig. 3. 
 
 yield the best fat. A simple method is to boil the hones 
 with water in large open vessels for 24 hours, skimming off 
 the fat as it floats. The odours evolved during this process, 
 however, are exceedingly offensive, and a very great improve- 
 ment consists in the application of steam in closed vessels, as 
 adopted hy most large firms. The form used hy Morris and 
 Griffin, at Wolverhampton, is shown in Fig. 3. It is com- 
 posed of a l^-in. iron cylinder a, 6 ft. long hy 3 ft. 6 in. 
 in greatest diameter, furnished 
 with hinged doors 6 c at top 
 and bottom, which are tightly 
 closed during operations by 
 l:|-in. screw-threaded bolts and 
 nuts d, and further provided 
 with 2-in. tap-holes at e and /. 
 The bones are introduced at the 
 top door 6, which is then se- 
 cured ; steam at about 286° E. 
 (141° C.) is introduced for 40 
 minutes ; the steam is shut off, 
 and that remaining in the cy- 
 linder a is let out into a con- 
 denser ; ^ hour later, the fat is 
 drawn off by the tap / at the 
 bottom of the cylinder ; the bottom door c is then opened 
 and the bones are allowed to fall upon the floor below. The 
 bones are rendered much more brittle than by ordinary 
 boiling, and are much drier and more easily ground, requiring 
 no previous storing. The cylinder shown will steam at 
 a charge 46^ cwt. of bones, yielding 87-88 lb. of fat per 
 ton. 
 
 One of the best and most inoffensive arrangements of the 
 bone-boilers for a large establishment is that adopted at 
 Adams' knackery in Birmingham, erected under the direction 
 of Dr, Alfred Hill, and shown in Figs. 4, 5. A set of 6 pans 
 is fixed and heated in the usual way. They are enclosed above 
 in a sort of closet, formed by a wooden partition, reaching up 
 
 Scale, ^.-Ifi' 
 
28 
 
 SOAP. 
 
 to the roof of the building and down to the front of the top 
 of the pans. Opposite each pan, is a shutter in the partition, 
 
 which can be slid up whenever it is requisite to obtain access 
 to the pan. Each pan is closely covered with a wooden lid, 
 
RAW MATEEIALS. 
 
 29 
 
 Fig. 6. 
 
 and from the upper and back part of each pan, beneath the 
 cover, starts a pipe leading to a 10-in. main running the whole 
 length above the pans and within the hopper, receiving contri- 
 butions of vapour from each pan. This pipe finally has exit 
 outside the building ; it here communicates with an oblong 
 condenser, made of sheet iron, filled with coke, measuring 
 14 ft long, 3 ft. in vertical section, and 14 in. in horizontal 
 section, inclined a little in its long diameter. At the lower end, 
 it receives the pipe from the boilers ; and from its lower 
 border, another small pipe conveys away the water produced 
 by the condensation of the vapour, the cooling agent being 
 the outer air, to which the condenser is exposed on all sides. 
 The upper end of the condenser communicates by two air- 
 pipes with the flues from the fire-places. "When the pan-lids 
 are raised, the escaping vapour rises to 
 the roof, and is conveyed from the inte- 
 rior of the closet into the chimney-shaft, 
 by escape-steam pipes provided for the 
 purpose. The reference-letters indicate : 
 a, fire-holes ; 6, boiling-pans ; c, steam- 
 pipes ; d, main steam-pipe ; e, escape- 
 steam pipes; /, air-pipes; g, chimney- 
 shafts ; h, condensed-steam pipes ; i, 
 water-trough ; k, wrought -iron con- 
 denser ; , I, doors for cleaning smoke- 
 flues ; m, smoke-flues ; n, closet with 
 sliding door. 
 
 The form of digester employed by 
 Proctor and Eyland, of Birmingham, for 
 extracting both fat and gelatin from 
 bones, is shown Fig. 6. It consists of a 
 (duplicate) egg-shaped iron vessel a, ca- 
 pable of holding 6-7 tons of bones : at the 
 upper end is a short neck 6, surrounding the charging-hole, 
 which is closed by a tight-fitting cover; here enters the 
 steam-pipe c, which descends to the bottom of the digester, 
 here also the waste-steam pipe has its exit. At the bottom 
 
 Joaif 1 -le n 
 
30 SOAP, 
 
 of the digester is a wooden, false bottom e, for supporting the 
 bones, and on one side is a man-hole / for reacMng the 
 false bottom and removing the boiled bones. Cold water 
 can be introduced by the pipe g. The liquid matters are 
 withdrawn by the pipe Ji, separating into 2 branches, with 
 appropriate taps, the one i leading to a drain, the other .h to 
 a tank. The bones are first boiled in water by the admission 
 of free steam ; when sufiSciently boiled, steam is turned off, 
 and time is allowed for the fat to separate; cold water is 
 then let in by g to raise the fat to the level of the pipe I, 
 where it escapes into a receptacle. The water is next run off 
 from the digester by the pipes h i into a drain, the top cover 
 is fastened down again, and the bones are steamed at a 
 pressure of about 50 lb. for the extraction of the gelatin ; 
 the gelatin is drawn off by the pipes b k, and the bones are 
 finally removed by the m.an-hole /. The bones are in a 
 less friable condition than when the form shown in Fig. 3 
 is used, and they require to heat somewhat before beiag 
 ground. 
 
 The product thus obtaiaed varies in colour from drab to 
 deep brown ; it possesses a characteristic odour, and is liable 
 to contain free fatty acids, as well as more or less lime dis- 
 solved in it (see Chap. III.). The solidifying-point of its fatty 
 acids is usually about the sariie as in the case of lard, although 
 the best specimens of bone-tallow approach ordinary tallow 
 in this respect. Bone-grease must not be confounded with 
 bone-oil, which results from the decomposition of gelatinous 
 tissue in bones, when they are calcined for the preparation of 
 bone-black, and the volatile products are condensed. 
 
 Kitchen and Ships' -grease. — The names of these 
 sufficiently indicate the sources whence they are derived, and 
 it is not an unusual thing for the soap-manufacturer to 
 purchase them in their rough form, as collected by the small 
 dealers. The apparatus for, and mode of, rendering and 
 purifying are the same as those described under the head 
 of tallow and bone-grease, but the operation is more offensive,, 
 and special pains should be taken to mitigate the nuisance 
 
EAW MATERIALS. 31 
 
 caused iDy tlie fumes.* The colour of the product varies as 
 does that of bone-grease, the older and sourer qualities of 
 rough grease yielding a browner and inferior product. A 
 well rendered sample should not contain any other impurity 
 than about • 5 per cent, water, and its fatty acids should 
 approach 108° F. (42° C.) in their solidifying-point. 
 
 Glue- and Skin-grease. — These greases are bye- 
 products in the manufacture of glue, size, &o., and are 
 usually very dark in colour; with a strong disagreeable odour, 
 which does not disappear in the resultant soap. They are 
 liable to contain water and sulphuric acid, as well as traces 
 of gelatin, &o. Their fatty acids solidify at about 100° F. 
 (38° C). 
 
 Curriers' -grease is not unfrequently used in inferior 
 soaps. It is a mixture of tallow and fish-oils, and possesses 
 the characteristic smell of the latter, combined with that of 
 leather. The solidifying-point of its fatty acids varies with 
 the proportion of fish-oil used. Occasionally the variety 
 known as " leather tallow " (which contains little or no fish- 
 oil) is met with, especially in imports from the United States. 
 
 Butter occasionally finds its way to the soap-maker, 
 when it has become unsaleable for food purposes. It contains 
 water and salt as impurities, and also the complex organic 
 acids similar to those mentioned as occurring in rancid tallow. 
 Although its fatty acids solidify at about the same point as 
 those of lard, its value as a saponifiable material is not great, 
 on account of the presence in it of several of the lower terms 
 of the acetic series of acids (p. 8), which are themselves 
 soluble in water, while their soda salts cannot be precipitated 
 from their aqueous solution by the use of salt (sodium 
 chloride); Butterine is also sometimes offered to the soap- 
 maker ; the basis of this is, or should be, the softer parts 
 of tallow, the so-called oleo-margarin, whose fatty acids 
 solidify at about 107° F. (42° C). 
 
 Fish Oils of various kinds can only be used in the 
 
 * Some remarks under this head will be found in Chap. VIII. 
 
32 SOAP. 
 
 manufacture of so'ft soaps ; they are usually offered for sale 
 in a fairly pure condition, and require little or no previous 
 preparation to fit them for the soap-pan. The chief 
 caution to be observed in using them is that their smell 
 is so penetrating as to hang about the vessels which are 
 used to contain them, so that there is danger of contami- 
 nating other materials with their odour, unless special 
 precautions are taken. 
 
 Further information about these fats and oils, and about 
 some of the rarer kinds of fatty materials which are occa- 
 sionally offered to the soap-maker, will be found under the 
 head of " Oils " in ' Spons' EncyclopsBdia of Manufactures 
 and Eaw Materials,' at the end of which article also the 
 bibliography of the subject is given. 
 
 SECTION B.— VEGETABLE OILS. 
 
 Palm-oil. — Although the consumption of palm-oil by 
 the soap-maker has enormously decreased of late years, in 
 consequence of the comparatively low price of tallow, it is 
 still an essential constituent of certain soaps, and it is one 
 of the most important raw materials of the candle manufac- 
 ture; a somewhat detailed description of it will therefore 
 not be out of place in this volume. 
 
 Palm-oil is the product of the outer fleshy coating of the 
 fruit of several species of palm, but particularly of MoBis 
 
 For the production of commercial oil for exportation, the 
 spadices are cut from the trees, and put in a heap in the 
 outer air, where they are allowed to remain for 7-10 days ; 
 this causes the joints of the nuts to be weakened by the 
 process of decomposition, and they are then easUy detached 
 by simply beating them. The nuts or fruits are gathered 
 together, and the husks that adhere to their base are 
 removed, either by hand or by rubbing them together, and 
 are separated by throwing them in the air, and allowing 
 a strong breeze to blow them away. A hole about 4 ft. deep 
 is dug in the earth, and lined with plantain-leaves, into 
 
EAW MATERIALS. 33 
 
 which the nuts with their hard unyieldiiig pulp are put, 
 and covered over, first with plantain-leaves, and then with 
 palm-leaves and earth. The nuts are allowed to remain for 
 various periods — from 3 weeks to 3 months — until more or 
 less decomposition has taken place, so that the pulp when 
 removed is soft, and appears as if it had been thoroughly 
 boiled. They are now put into a trough, made by digging a 
 hole 4 ft. deep, and paving it below and around with rough 
 stones. In some oases, a portion of the nuts is boiled in iron 
 or earthenware pots, and then mixed with the unboiled 
 portion before putting into the trough. They are now 
 pounded with wooden pestles by men standing around the 
 trough, until the pjilp is quite detached from the surface of 
 the hard nut ; the whole is removed from the trough and 
 piled in a heap, and the stones are taken out, leaving the 
 oily fibrous pulp, which is put into a pot with a small 
 quantity of water over a good fire, and well stirred until 
 the oil begins to melt out. The pulp is then put into a 
 rough net, open at both ends, to which are attached 2 or 3 
 short sticks, by turning which in opposite directions the oil 
 is squeezed out through the nets; it runs into a receiver 
 or tub, leaving the fibre behind. The longer the oil-nuts 
 remain underground, the thicker the oil will be when made, 
 the quality will also be inferior, and the smell bad. On the 
 other . hand, the shorter the time, within certain limits, 
 during which the nuts are underground, the better will be 
 the oil made from them. It is evident from this rough 
 mode of preparation that the oil is liable to contaia mo^e or 
 less vegetable fibre, which is apt to act as a ferment, and 
 render the oil rancid in course of time, besides holding in 
 suspension a varying quantity of water. These impurities 
 in the commercial oil are further increased by the fact that, 
 when the oil is brought down to the coast, should no vessel 
 be there prepared to receive it, it is frequently buried in 
 the sand till an opportunity arrives for exporting it. 
 
 It has been estimated that the yield of oil from this palm 
 is at the rate of 7 cwt. an acre, or more than ^ greater than 
 
34 SOAP. 
 
 the oil product from the olive in Southern Europe. On some 
 parts of the West Coast of Africa where the regular collec- 
 tion of the fruits is not practised, the trees grow so thickly, 
 and afford such regular and rapid crops, that the ground 
 becomes covered with a thick deposit of the fatty matter 
 afforded by the fallen nuts. 
 
 The oil obtained from the pericarp, the palm-oil proper, 
 has the consistence of butter, a yellow colour, an odour 
 resembling violets, and a mild flavour; it easily becomes 
 rancid, bleaches in the sunlight, saponifies readily with 
 alkali, dissolves in all proportions of ether, and in alcohol of 
 • 848 sp. gr. Its specific gravity varies considerably, as 
 also does the solidifying-point of its fatty acids, which 
 ranges from that of lard to above that of the hardest tallow. 
 Besides its industrial applications to candles and soap it is 
 largely used in the manufacture of tin-plate, in South Wales 
 and elsewhere. For this latter purpose, its non-drying 
 qualities render it valuable as a preservative of the surfaces 
 of the heated iron sheet from oxidation, until the moment of 
 dipping into the bath of melted tin, the sheets being rapidly 
 transferred to that from the hot-oil bath, which consists 
 almost entirely of palm-oil. The softest, purest, and most 
 neutral oil is preferred for this purpose, and hence the kiud 
 known as " Lagos " is much used. 
 
 Scarcely any oil which finds its way into commerce has a 
 greater range of quality than palm-oil. The various kinds 
 are well known by the names of the parts of the coast whence 
 they are shipped. The oil used to be brought home by small 
 vessels trading from London, Liverpool, and Bristol, which 
 went out with empty casks, and lay some months along the 
 coast, especially near the mouths of rivers, until they were 
 filled up with oil. The great regularity with which 
 steamers now call at many African ports, and the cheapness 
 of freight, has materially altered the mode of conducting the 
 trade. Casks are now left at the various depots, and instead 
 of, as formerly, a 300-ton ship coming home laden with one 
 or two classes of oil, steamers arrive regularly in Liverpool 
 
EAW MATEEIALS. 35 
 
 with cargoes chiefly of palm-oil, made up at various ports- of 
 call, ranging perhaps from 8° N. and 13° W. (near Sierra 
 Leone) to 10° S. and 12° E. 
 
 Along so great a range of coast, it is not a matter of sur- 
 prise that there should be such variations in the quality of 
 the oil, especially when, to differences in climate affecting 
 the trees and their fruit, are added differences in mode of 
 preparation, &o. It is found, however, that the oil from 
 any given port is tolerably uniform in quality. Thus, as 
 explained before, Lagos oil, which chiefly comes to London, 
 is the most neutral (i. e. non-rancid) and the cleanest, the 
 water and other impurities not exceeding 1-2 per cent. ; it 
 is also nearly the softest. On the other hand, " Brass " oil is 
 almost equally pure, but is the hardest of all the varieties, 
 and contains the largest percentage of palmitic acid ; hence 
 it usually commands the highest price for candle-making in 
 the Liverpool market. " Cameroons " and " Windward " oils 
 (which chiefly come to Bristol) occupy an intermediate posi- 
 tion as regards hardness; in the latter, impurities may 
 amount to 5-6 per cent. " Saltpond " and " Monrovian " 
 may be mentioned as instances of the most impure oils, 
 25 or even 30 per cent, being not an unusual amount of 
 impurity. On this account, it has been proposed to sell 
 
 palm-oil by analysis, guaranteed to contain per cent, of 
 
 clean oil, just as soda-ash is sold at, say, 55 per cent. soda. 
 The presence of these impurities tends to partially decompose 
 the oil, and render it harder, since the fatty acids are more 
 solid than the neutral fat whence they are derived. Any 
 determinations, therefore, of the melting- or solidifying- 
 points of palm-oil itself, i. e. the oil of commerce, are utterly 
 misleading. Commercial palm-oil is a mixture of palmitin 
 and olein (the glycerides), and of palmitic and oleic acids, 
 in very varying proportions, with the addition of uncertain 
 quantities of water, vegetable fibre, and sand. 
 
 Until 10-12 years ago, palm-oil from certain parts of the 
 African coast was usually mixed with the oil obtained in 
 a very crude way from the kernel of the fruit (see Palm-nut- 
 
 D 2 
 
36 SOAP. 
 
 oil) ; as the kernels were somewliat burnt in tte process of 
 extraction, they comnmnicated a peculiar smell to their oil, 
 and that again to the palm-oil, which was known in the 
 market as " coffee-oil ; " such oil being difficult to bleach, 
 and weaker in body, was considerably lower in price than 
 good, palm-oil. It is more usual now, however, for the 
 kernels to be sent to England to be treated. Our total 
 annual imports of palm-oil fluctuate between 35,000 and 
 50,000 tons. 
 
 Palm-nut-, Palm-kernel-, or Palm-nut-kernel- 
 oil. — This oil, which is known in commerce under each 
 of the synonyms given, is extracted from the nuts or kernels 
 of the fruit described under Palm-oil. Some 10-12 years 
 ago, the nuts were partly charred, and the oil that ran from 
 them, discoloured by the burnt cellulose, was exported either 
 separately or mixed with palm-oil. This brownish oil 
 could only be very slightly bleached, and was therefore not 
 of great value for soap-making. Since the improved methods 
 of oil extraction, described later on, have been worked out, 
 the nuts have been exported to England, and the nearly 
 colourless oil there extracted, while the ground nuts have 
 been used for cattle-food. The following is a description 
 of the old process, which is still in vogue in some districts. 
 
 The nuts which have been subjected to the processes 
 described for making oil are deprived of their external pulp, 
 and the kernels only remain; or old nuts are picked up 
 from under the trees, and put in the sun for days, and even 
 months, until they are perfectly dry. They are then broken 
 between two stones, and the kernels are obtained whole, in 
 perfect condition, and fit for exportation, and so form the 
 commercial palm- kernels. If they have not been perfectly 
 dried, the kernels break into pieces. The oil obtained from 
 these kernels by the following process is called "white- 
 kernel-oil." The kernels are placed in wooden mortars, and 
 pounded very fine ; then removed to a grinding-stone, and 
 ground into a homogeneous mass, which is put into cold 
 water, and stirred with the hand. The oil rises in white 
 
RAW MATEEIAIS. 37 
 
 lumps on the surface of the water, and is collected and 
 boiled. It is of a very light straw-colour, and, when 
 exposed to the sun and dew, becomes, after a time, perfectly 
 white. " Brown " or " black " oil is thus obtained. The 
 kernels are put into a pan, and fried ; the oil oozes out, and 
 is strained; the fried nuts are placed in wooden mortars, 
 pounded, and afterwards finely ground on a grinding-stone. 
 The mass is thrown into a small quantity of boiling water, 
 and stirred constantly ; the oil rises, and is continually 
 skimmed off. The pulpy mass is removed from the fire, 
 spread out in a large bowl, and allowed to cool, after which 
 it is again ground, and put by until the cool of the day, 
 when it is mixed with a little water to soften it. It is now 
 beaten with the hand for some time until the oil comes out 
 in white pellets. As soon as this is observed, a large quan- 
 tity of water is put into it, and a fatty substance floats on 
 the top ; this is skimmed off and boiled, and the pure oil is 
 obtained. 
 
 The greater portion, however, of the palm-kemel-oil 
 which is now used in commerce, is extracted from the nuts 
 by the solvent action of carbon bisulphide. This plan is 
 adopted on a very large scale by Heyl of Berlin and Sevin of 
 London, and as the method is applicable to a great variety 
 of purposes, it will be shortly described here. Olive-oil 
 residues, for example, treated in this way, yield a greenish 
 oil much used for soap-making. 
 
 In the case of palm-kernels, so completely is the meal 
 freed from all traces of carbon bisulphide and its attendant 
 nauseous-smelling compounds, that it is much used for cattle- 
 food, though less valuable for that purpose than the meal 
 from simple expression, by reason of its deficiency in oil. 
 The residues from the extraction of olive-oil in Southern 
 Europe are dealt with in the same way, and made to yield 
 an additional 2-4 per cent, of the so-eaUed " pyrene " oil. 
 
 The method of employing carbon bisulphide may be 
 illustrated by Pigs. 7 and 8, showing respectively a longitu- 
 dinal section and plan of Deitz's apparatus. It consists of 
 
38 
 
 SOAP. 
 
 extractor^ B, whicli are ustially worked in couples alternately, 
 and in connection with a still D, containing a steam-coil, and 
 
 Fig. 7. 
 
 communicating with a cooler C hy means of a pipe e'. The 
 pipe j leads from the cooler-worm to a receptacle A for 
 storing the bisulphide. The extractor B is also cotineoted 
 
RAW MATEEIALS. 39 
 
 with the cooler C hj the pipe e, and provided with suitable 
 openings for the introduction and withdrawal of the fatty 
 matters. These latter are put into B between two perforated 
 plates d d' ; bisulphide is pumped from A by the pipe h, in 
 at the bottom of B. The bisulphide passes up through the 
 mass, absorbs the fat present, and escapes finally by the pipe 
 / to the still D. The admission of bisulphide is continued 
 till a sample drawn off at h is free from fat. The bisulphide 
 is then shut off, and steam is injected into the extractor 
 through a perforated coil lying between the bottom and the 
 perforated plate. The remaining bisulphide is thus carried 
 by the pipe / into the receptacle A. The fat-saturated 
 bisulphide is heated in D, by means of a steam-coil. The 
 vapour of the bisulphide condenses in the cooler C, and runs 
 back, into A for further use. Steam is generally passed 
 through the fat, to completely free it from bisulphide ; and 
 the clean fat is finally let out by the pipe «'. 
 
 In America, preference is given to petroleum-spirit of low 
 boiling-point, as being cl^eaper and less dangerous, though 
 less rapid in its action. The materials there principally 
 dealt with are the residues from the rendering of animal fats 
 (as taUow and lard), containing 12-15 per cent, of extraotable 
 grease. The patents relating to this industry in America 
 are very numerous, but those taken out by Adamson seem 
 to be most largely adopted. The process lasts 24-36 hours, 
 and the products are used mainly as lubricants, being unfit 
 for making good soap. " Pomace " or castor-cake, and greasy 
 cotton-waste, are similarly treated. 
 
 A very great disadvantage of petroleum-spirit, however, is 
 that whereas the high sp. gr. of carbon bisulphide enables it 
 to be kept covered with water (and even collected from the 
 mouths of the condenser-worms under water), and thus 
 protected from all risk of explosion by contact of its vapour 
 with air and flame, petroleum spirit, which is, bulk for bulk, 
 about half as heavy as the bisulphide, cannot be so protected 
 from accident and loss by evaporation. Its vapour-density 
 also is much less. 
 
40 SOAP. 
 
 When it is desired to produce a palm-temel meal for 
 feeding purposes, which shall not be totally devoid of fat, 
 the palm-kernels are treated by ordinary oil-mill machinery, 
 one form of which will be briefly described under the head 
 of cotton-seed-oil. 
 
 By whichever of these processes it is obtained, palm- 
 kernel-oil, when freed from impurities, is of a pale primrose- 
 yellow colour, with a characteristic odour not unlike that of 
 coco-nut-oil, which it strongly resembles in its chemical and 
 physical characteristics. Indeed, for soap-making, it has 
 largely supplanted coco-nut-oil in the cheaper soaps in 
 which that oil has hitherto been employed on a large scale. 
 It is slightly softer than good coco-nut-oil, its fusing-point 
 being tolerably constant at 78° P. (25J° C). If, however, 
 the whole of the oil be removed from the kernels, the oil is 
 slightly harder, containing a larger proportion of the higher 
 terms of the series, lauric (or lauro-stearic) acid, cocinic 
 acid, &c. The oil itself, being tolerably pure, is a neutral 
 glyceride, and does not readily get rancid. Its fatty acids, 
 however, are partly fixed and partly volatile, like those of 
 coco-nut-oil; 100 parts of it yield only 91 '5 to 92 parts of 
 solid fatty acids. 
 
 Olive-oil. — Olive culture is successful in the Old World 
 wherever the mean annual temperature is from 58° to 66° F. 
 (14^°-19° C), that of the coldest month not falling below 
 42° F. (5J° C), nor that of the hottest below 71° F. (22° C). 
 The Olea europwa seems to be the only species which is an 
 object of systematic cultivation, and it thrives and is most 
 prolific in dry calcareous, schistous, sandy, and rocky ground, 
 so that it may be grown on land which is worthless for 
 many other crops. In the extraction of the oil there are 
 two distinct processes — crushing and pressing. In the first 
 process the fruit is by some completely crushed ; by others, 
 the pericarp only is crushed first. The pulp or paste is 
 shovelled into bags which are placed in the press (the latter 
 being kept warm), and exposed to air as little as possible. 
 " Virgin " oil is that obtained by the first pressing j the 
 
EAW MATEEIALS. 41 
 
 pulp or maro is then stirred up with boiling water, and 
 pressed again, more strongly, giving an oil only slightly 
 inferior to the first. The marc is again treated with boiling 
 water, the stones are all thoroughly crushed, and the whole 
 again pressed, yielding what is known as " pyrene " oil. 
 The husks and various oily crusts and residues are now 
 frequently exhausted of their oil by the carbon-bisulphide 
 process described above, and as the oil thus obtained is richer 
 in stearin than any other variety, it makes a harder soap. 
 
 Good olive-oil is a somewhat viscid liquid, pale- or 
 greenish-yellow, of faint, agreeable odour, and bland 
 oleaginous flavour; sp. gr. 0-916 at 63^° F. (17^° 0.); it 
 commences to lose transparency by separation of a crystal- 
 line fatty substance, chiefly stearin, at 32°-50° F. (0°- 
 10° C.) ; when congealed and pressed, affords ^ of solid fat 
 melting at 68°-82J° P. (20°-28° C), the fluid portion (olein) 
 remaining liquid at 25°-14° F. (-4° to -10° C). It is one 
 of the less alterable, non-drying oils. The best kinds of oil 
 are consumed enormously in food and medicine, constituting - 
 the " salad-oil " of the shops ; the commoner kinds are em- 
 ployed in lubricating, illuminating, woollen-dressing, and the 
 manufacture of soaps. It is most extensively adulterated 
 with refined cotton-seed, ground-nut, and other oils. We 
 import some 20,000 to 30,000 tuns of olive-oil annually. 
 
 Coco -nut- and. Copra-oil. — As indicated by its name, 
 this oil is obtained from the fruit of the coco-nut palm, Cocos 
 nudfera, which flourishes with equal vigour on the coasts of 
 the East Indies, throughout the islands of the tropical Pacifi.c, 
 and in the West Indies and tropical America. Ceylon, 
 which is peculiarly favourable to it, is estimated to contain 
 some 20 million trees. The composition of the nut is said 
 to be : — 
 
 Water 39-7 
 
 Oil 29-3 
 
 Amygdalin .. .. 14 '0 
 
 Woody fibre.. .. 9-5 
 
 Sugar 3-6 
 
 Gum 21 
 
 Emulsin I'l 
 
 Albumen .. .. 0"5 
 Mineral matter .. 0*2 
 
 100 
 
42 SOAP. 
 
 The albuminous pulp dried at ordinary temperatures 
 (called "copra" or "copperah") contains 54 "3 per cent, of 
 oil, and dried at 212° P. (100° C), 66 per cent. For pre- 
 paWng copra, only ripe nuts should be collected, and they 
 should not he broken till 4-6 weeks after gathering ; the 
 copra then dries more quickly, does not become mouldy, 
 and affords a greater yield of oil. 
 
 All the native modes of extracting the oil are, compara- 
 tively speaking, rough and wasteful, but two of them may 
 be briefly described here. The most effectual methods of 
 extraction, however, are those described under the heads of 
 palm-kemel and cotton-seed oils. 
 
 An Indian pi'ocess for extracting it, when required to be 
 colourless for perfumery manufacture, is as follows. The 
 kernel is plunged into water, a,nd boiled for a few minutes, 
 then grated, and placed in a press ; the emulsion thus 
 obtained is boiled until th^ oil rises to the surface. This 
 process is not cheap enough for ordinary commercial oils, 
 and recourse- is had to rude forms of oil-mill, worked by 
 oxen, and treating about 130 lb. of copra daily, obtaining 
 about 40 qt. of oil. Another plan is to divide the kernel 
 into pieces, and dry them on shelves over charcoal fires; 
 after 2-3 days, they are put into the press. By this method, 
 100 nuts carefully dried are estimated to yield by pressure 
 10-13 eddngalies (of 92 cub. in.) of oil, or 40 nuts to a gallon ; 
 inferior nuts will not give more than 3-9 edangalies ; those 
 from trees on salt marshes afford the least oil. Eecently a 
 factory has been erected at Borongan for the better prepara- 
 tion of the oil. The grating of the pulp is performed by 
 iron discs with toothed edges, radiating from the ends of 
 iron rods, and bluntly pointed towards the centre of the 
 fruit. These discs are made to rotate by suitable gearing, 
 while the workmen force the inner face of half coco-nuts, 
 held firmly by both hands, and pressed by means of a pad on 
 the chest, against the revolving rasps. The finely shredded 
 nut lies for 12 hours in flat pans, to undergo partial decom- 
 position, and is then gently, pressed; the resulting liquor, 
 
EAW MATERIALS. 43 
 
 consisting of ^ oil and | water is caught in tubs, and after 
 standing for 6 hours, the supernatant oil is skimmed off. 
 The latter is next heated in iron pans holding about 20-25 
 gal., until all the water has evaporated, occupying 2-3 
 hours. In order to cool the oil rapidly, and prevent its 
 deepening in colour, 2 pailsful of cold oil, freed from water, 
 are poured in, and the fire is quickly withdrawn. The 
 compressed shreds are once more exposed to the air, and then 
 subjected to powerful pressure. After these two operations 
 have been twice repeated, the rasped substance is suspended 
 in sacks between strong vertical boards, and alternately 
 squeezed and shaken up for a considerable time. The refuse 
 finally serves as pig-food. The oil which runs from the 
 sacks is quite free from water, and very clear, and is used 
 for cooling that extracted by the boiling process. 
 
 When pure, coco-nut-oil is white, and almost as fluid and 
 limpid as water, in tropical climates, but solidifies at 61°-64^° 
 r. (16°-18°C.), and consequently generally appears in Europe 
 as a solid, opaque, unctuous substance, of the consistence of 
 butter, and fusible at 75°-82° P. (24°-28° C). When fresh, 
 its odour and flavour are sweet and agreeable, but it quickly 
 becomes rancid. It dissolves readily in alcohol, and saponi- 
 fies with facility. It contains at least ten different fatty 
 acids, of which the chief is laurostearic, together with oleic, 
 palmitic, myristic, and some of less importance, all combined 
 with glycerin. In Europe, the chief applications of the oil 
 are for candle- and soap-making. It is an excellent illu- 
 minator, in both candles and lamps, as it emits no smoke; 
 and it forms a hard and very white soap, more soluble in 
 salt water than any other kind made on a commercial scale. 
 During the last 15 years, its consumption for soap-making 
 in England has been greatly reduced by the substitution of 
 palm-kernel-oil, extracted here. In the East, the oil is 
 largely used in 'booking and medicine while fresh, and for 
 burning, painting, soap-making, and anointing the body, 
 when rancid. 
 
 It has been already noticed that coco-nut- and palm- 
 
44 SOAP. 
 
 kernel-oils combine witli a larger quantity of soda tlian any 
 other known fat, and hence that the yield of soap from 
 these oils is greater than from other fats. Further, the 
 soap so produced has the power of combining (and making 
 a hard soap) with more water than can ever be communi- 
 cated to tallow soap, a property which has frequently given 
 rise to dishonest traffic. This soap is more soluble in water 
 than any other, and requires a much larger quantity of 
 common salt to separate the excess of water from it. In 
 technical language, it is said to " work close." Eeference to 
 the table on p. 8 will show the reason for this. Oooo-nut-oil 
 contains a number of low terms of the fatty-aoid series, 
 whose salts are so very soluble, that even the lime and 
 baryta salts of the lower among them are quite soluble in 
 water, just as are the lime and baryta salts of formic and 
 acetic acids, the lowest terms of all. Our annual imports of 
 coco-nut-oil, range between 6500 and 15,500 tons. 
 
 Castor-oil. — The inferior qualities of this oil are not 
 unfrequently found among soap-making materials. The 
 plant, Bicinus communis, or Palma-Ghristi as it is often called, 
 is indigenous to India, whence it has been distributed by 
 cultivation through the tropics and in many temperate 
 countries. There are two varieties of it, distinguished by 
 the size of their seeds ; the small-seeded variety yields the 
 better oil. The medicinal variety is expressed from the seeds 
 without any heat. In 1878 the total Indian export had 
 reached the very large figure of 1,411,216 gal. 
 
 The manufacture of castor-oil is actively carried on in 
 the United States, especially at St. Louis, the seeds being 
 largely produced in S. Illinois. In 1875, Kansas had 24,145 
 acres under this crop, producing 361,386 bush, of seed. 
 Other states participate in the industry. The land is pre- 
 pared as for other crops, and the seeds are planted much the 
 same as maize, except that only one seed is put into each hill, 
 and that every fourth row is missed to afford space for the 
 harvesting. Eipening commences in August ; the yield varies 
 from 15 to 25 bush, an acre, 20 being considered fair. The 
 
RAW MATERIALS. 45 
 
 oil is generally extracted in the following manner. The seeds 
 having heen thoroughly cleansed from the dust and particles 
 of the pod with which they are always contaminated, are 
 placed in an iron tank, and heated to such a degree as will 
 liquefy the oil without any risk of scorching. They are then 
 pressed, the oil escaping heing known as " 1st quality." The 
 pressed seed is heaped up and left for a day ; on the following 
 day, it is again heated and pressed, and gives a " 2nd quality " 
 oil. The yield from 1 bush, of seed is 12 lb. of 1st quality, 
 and 4 lb. of 2nd quality oil ; sometimes a 3rd expression is 
 made, giving 1-3 lb. of a very highly coloured oil. Occasion- 
 ally too, the cake from the 2nd pressing is treated with 
 carbon bisulphide, which extracts a small additional quantity 
 of thick, dark, common oil. All qualities need purifying and 
 clarifying. This is usually effected by boiling first with a 
 large quantity of water, and skimming oflf the impurities as 
 they rise, while the mucilage and starch are dissolved, and 
 the albumen is coagulated. The clear oil is removed and 
 boiled with a very little water, which clarifies it, and drives 
 off volatile acid matters. The chief point to be noticed is to 
 expose the oil as little as possible to the air, or it quickly 
 becomes rancid. The 1st quality oil is used medicinally, 
 the 2nd for burning, lubricating, leather-dressing, &c. In 
 America the cake is frequently used as fuel. 
 
 Castor-oil has a sp. gr. of 0-969 at 53^° F. (12° C), 0-957 
 at 77° P. (26° C), and 0-908 at 201 J^° F. (94° C); it has 
 usually a pale-yellow colour, viscid consistence, and slight 
 mawkish odour and flavour, which are much intensified when 
 it becomes rancid ; at 5° F. ( — 15° C), it commences to congeal, 
 but does not completely solidify above 0° F. ( — 18° C), when 
 it dries up, forming a transparent varnish-like film in three 
 layers ; its boiling-point is 509° F. (265° C), when it begins 
 to distil, and affords various products ; it mixes in all propor- 
 tions with glacial acetic acid and absolute alcohol, and is even 
 soluble in 4 parts alcohol of 0-838-0 -860 at 59° F. (15° C), 
 and forms a clear mixture with equal weights of the same at 
 77° F. (25° C.) J it is said also to render other oils mixed with 
 
46 SOAP. 
 
 it soluble in alcohol. It saponifies readily, yielding several 
 fatty acids, the chief of which is ricinoleid (O18H34O3), 
 peculiar to this oil, and another appears to be palmitic. Its 
 drastic principle and optical properties stiU await investiga- 
 tion. Some of its uses have already been alluded to. For 
 medicinal use, as a purgative, the cold-drawn oil is the only 
 kind fit for human subjects ; but the oil obtained by roasting 
 and boiling, or that extracted by alcohol, is preferred by 
 veterinary surgeons, as containing much more of the drastic 
 principle, and being therefore more powerful. The common 
 kinds are largely used by leather-dressers, principally, 
 perhaps, for morocco leather, but with equal success on all 
 descriptions ; moreover it repels rats and other vermin, and 
 does not interfere with subsequent polishing. As a lubri- 
 cant, it is in extensive use in Europe and America ; and 
 as a Itimp-oil, in India, Brazil, &c. Chiefly 3 sorts appear 
 in the London market — that expressed here from imported 
 (essentially Egyptian) seed, E. Indian expressed, and Ameri- 
 can expressed. The oil is imported in tins, barrels, hogs- 
 heads, and duppers. It is often adulterated with poppy- 
 seed-oil and croton-oil. Our imports of castor-oil in 1883 
 were 148,320 cwt., value 237,954Z., of which, no less than 
 113,965 cwt., 182,482Z., were from Bengal. 
 
 Cotton-seed-oil. — The seeds which are separated from 
 the " lint " or " wool " of the various kinds of cotton in the 
 process of " ginning " are valued for their oU. The utiliza- 
 tion of this oil has of late years assumed the importance of a 
 distinct industry in the United States, where there are now 
 upwards of 40 oil-mills, 9 being situated in Mississippi, 9 in 
 Louisiana, 8 in Tennessee, 6 in Texas, 4 in Arkansas, 2 in 
 Missouri, 2 in Alabama, and 1 in Georgia. The quantity of 
 seed there treated for its oil now amounts to over 400,000 
 tons annually, and the increasing production of the oil may 
 be gathered from the following figures, showing (a) the 
 number of gallons exported, and (6) the home consumption : — 
 year 1876-7, a 1,316,000, 6 2,000,000 ; 1877-8, a 1,457,000, 
 6 1,800,000 ; 1878-9, a 5,750,000, 6 2,425,000. The American 
 
EAW MATEEIALS. 47 
 
 process of extraction is as follows. The seed coming from 
 the ginning operation still has some fibre adhering to it, and 
 has a tendency to accumulate in masses. These are thrown 
 into a machine containing a screw-knife rcTolving in a 
 trough, which divides the materials into particles fit for the 
 screening operation. This is conducted first in a sieve with 
 meshes that allow the sand and dirt to pass, while retaining 
 the seed ; and then in one through which the seed can escape, 
 but not husks and coarse foreign matters. The cleaned seed 
 is next passed through a special gin for removing all remain- 
 ing fibre (useful for paper-making and other purposes) ; and 
 finally through a hulling-machine or decorticator, consisting 
 of fixed and revolving knives set so close as to sever the seeds. 
 The huUer made by D. Kahnweiler, 120, Center Street, New 
 York, was favourably noticed at the Centennial Exhibition. 
 Thus treated, the seeds are taken through one or more 
 separators, which pass the kernels but retain the shells. 
 The kernels are pressed into cakes between iron rolls, and 
 are then placed in steam-jacketed iron tanks, 4 ft. wide and 
 15 in. deep, where, by constant stirring, and the action of dry 
 heat obtained from injecting steam at 35 lb. a sq. in. into the 
 jacket, the oil is liberated from the cells in the course of 
 about 5 minutes. The heated mass is then filled into sacks 
 and subjected to repeated hydraulic pressure, till most of the 
 oil is extracted. By this plan, the yield from 1000 lb. of 
 seed averages 490 lb. of husks, 10 lb. of cotton, 365 lb. of cake, 
 and 135 lb. of oil. Its value in New York is about 18-20d. 
 a gal. The cake remaining after the expression of the oil 
 is invaluable as a cattle-food and as a fertilizer, and is an 
 important article of commerce. In 1880, Galveston (U.S.) 
 exported 399,841 lb. of cotton-seed, value 459Z. ; and New 
 Orleans, 255 sacks of cotton-seed, and 8137 barrels of the oil, 
 besides 3480 barrels of " soap-stock," one of the bye-products 
 of the oil refineries. 
 
 In India, cotton-seed is used more as a cattle-food direct, 
 than as an oil-yielder. By the native mills, it afibrds 25 per 
 cent, of a good oil, which, if purified, might become of con- 
 
48 
 
 SOAP. 
 
 sideraUe commercial importance. The seed cannot safely be 
 shipped without undergoing preliminary cleansing, other- 
 wise it heats and deteriorates in bulk on the long voyage. 
 Egypt exports large quantities of the seed to Marseilles and 
 English ports ; the total exports for the season 1879-80 were 
 estimated at 2,200,000 ardebs (260,000 tons), value 1,750,000Z., 
 of which, 98| per cent, was for the United Kingdom ; the 
 official figures are 1,282,770Z. worth to Great Britain, 66,200Z. 
 to France, and lOOZ. to Turkey. The Turkish port of Adana 
 
 Fig. 9. 
 
 shipped 3,389,375 lb. of cotton-seed, value 6740Z., in 1878. 
 According to Mr. Leopold Field, there were 3,000,000 tons of 
 cotton-seed produced in 1882, of which only 300,000 tons 
 were worked up, meaning 90,000,000 gal. of oil lost. 
 
 To describe the various methods adopted for the extraction 
 of oil from oleaginous nuts and seeds would be beyond 
 the scope of this volume ; a detailed account of oil-mill ma- 
 chinery may be found in such works as ' Spons' Dictionary 
 of Engineering.' One of the best systems is that introduced 
 by Messrs. Eose, Downs & Thompson, of Hull, which is the 
 
EAW MATERIALS, 
 
 49 
 
 chief seat of the seed-oil industry in England ; it will now be 
 described. 
 
 The arrangement of the mill is shown in plan in Pig. 9, 
 and in elevation in Pig. 10. The seed or other material passes 
 through the following ^course : — It runs from an upper floor 
 through the roll-frame A, by which it is crushed 3 or 4 times ; 
 it is then taken by the elevators B to the kettle C, where it 
 is heated and damped. Trom beneath the kettle, it is drawn, 
 in quantities sufficient to make a cake, by a box which con- 
 
 FiQ. 10. 
 
 veys it to the moulding-machine E. Here it undergoes 
 preliminary compression, the objects of which are (1) to 
 increase the number of cakes which may be inserted in the 
 presses at one time, enabling 18 12-lb. cakes to be made 
 where 4 8-lb. cakes were formerly made, and (2) to ensure 
 uniform size and weight, and uniform density or consistence 
 throughout. The cakes are removed from the moulding- 
 machine, and put into the press F, 3 or 4 of which are re-, 
 quired to each moulding-machine. The pressure is applied 
 either by means of hydraulic pumps, or by a high- and-low- 
 
50 SOAP. 
 
 ^pressure accumulator ; but unless extreme care is used with 
 the latter, it gives too rapid a pressure, squirting out the 
 Seed at the side of the plates and exercising a destructive _ 
 effect upon the cloth employed. The pulsation caused by the 
 pumps working directly to the press-cylinder is more akin to 
 the action of a wedge, and seems to extract the oil better 
 than the dead pressure given by the accumulator. If the 
 latter is used, a small cylinder may be applied to give the 
 preliminary pressure in the moulding-machine, in lieu of a 
 cam. After remaining under pressure about 25 minutes, the 
 cakes are withdrawn, and after being stripped of the cloth, 
 are pared by the machine H, which completes the manufacture 
 of the cakes. The parings fall under a very small pair of 
 edge-running stones J, which automatically discharge them, 
 when sufficiently ground, into an elevator conducting to the 
 kettle, where they are worked up with fresh seed. In a mill 
 with 4 presses, 2 men and a boy in the press-room can make 
 6 tons of cake in 11 hours, a rate of production requiring 
 6 men by the old process. The saving in steam-power is 
 about 30 per cent., chiefly due to the absence of the heavy 
 edge-runners, which also effects an economy of space. About 
 2 per cent, more oil is extracted, and the cakes are improved 
 in appearance by not having the structureless texture caused 
 by the trituration of the seed under edge-runners. 
 
 The general routine of the process having been described, 
 details may be added concerning the working of the several 
 machines. The roll-frame. Fig. 11, consists of 4 or 5 chilled- 
 iron rolls, each 3 ft. 6 in. long by 16 in. in diameter, placed 
 one above the other. These rolls are used for crushing all 
 the seed that passes through one set of presses, making 5^-6|^ 
 tons linseed-cake per spell of 11 hours. The seed passes into 
 the hopper in the usual manner, and is distributed to the 
 crushing-rolls by a fluted feed-roll the same length as the 
 crushing-rolls, placed at the bottom of the hopper. When the 
 seed passes the feed-roll, it falls on a guide-plate that carries 
 it between the 1st and 2nd rolls. After passing between these 
 rolls and being partly crushed, it falls on a guide-plate on 
 
EAW MATERIALS. 
 
 51 
 
 the other side, which carries it back between the 2nd and 
 3rd rolls, where it is crushed more fully. It then falls on 
 another guide-plate, which carries it between the 3rd and 
 4th rolls, where it is ground more fully ; then it falls on 
 a dth guide-plate, and is conveyed between the 4th and 
 
 Fio. 11. 
 
 5th rolls to receive the finishing touch. It is thus crushed 
 4 times. 
 
 The kettle is shown in Fig. 12, which represents one 
 capable of heating sufficient seed to keep 4 16-plate presses 
 ' occupied, or to make 6 tons of cake per 11 hours. It is steam- 
 jacketed and furnished inside with a damping apparatus. 
 The inside diameter is 5 ft., and the depth 2 ft. 6 in. The 
 seed introduced is kept in motion by the stirring-gear, and 
 when sufSciently heated and damped, is withdrawn by the 
 
 E 2 
 
52 
 
 SOAP. 
 
 box A in quantities to form one cake, and transferred at once 
 to the moulding-machine, attached or separate. 
 
 Pia. 12. 
 
 This machine is illustrated in Figs. 13, 14. Its purpose is 
 to measure the quantity of seed required to make each oake, 
 to shape it as required, and to press it so much, without ex- 
 tracting any oil, as will enahle the greatest number of cakes 
 to be put into the press. The measure of seed is placed on 
 a strip of woollen cloth, spread upon a thin iron tray, sliding 
 on the guides B ; the bottomless hinged mould C, having the 
 exact shape of the intended cake, is closed iipon it, and the 
 measure A (Fig. 12), which is also bottomless, is drawn over 
 guides in the upper surface of the mould C, thus accurately 
 distributing the seed. The mould is next thrown upon its 
 hinge (Fig. 13), and the ends of the strip of cloth are folded 
 over the seed, the thickness of which is about 3^ in. The 
 thin iron tray, with the mould of seed upon it, is then 
 pushed along the guides B, beneath the die D. This action 
 gives motion to a cam, shown above in the illustrations, but 
 
HAW MATEEIALS. 
 
 53 
 
 which may be placed heneath if necessary. This cam brings 
 down the die, and compresses the mould of seed to a thick- 
 ness of 1^ in.; its revolutions are so timed that the seed 
 
 Fig. 14. 
 
 is Tinder pressure long enough (about ^ minute) to let the 
 workman have another cake ready. 
 
 When the die of the moulding-machine rises,, the cake and 
 tray are removed and placed in the press (Fig, 15), the tray 
 
54 
 
 SOAP. 
 
 being withdrawn. The plates of the press are slightly 
 thickened towards the edges, and bear the name of the 
 manufacturer in reverse. The press is suitable for extract- 
 ing oil from linseed, rape-seed, cotton-seed, hemp-seed, niger- 
 seed, sunflower-seed, gingelly-seed, castor-seed, ground-nuts, 
 
 coco-nuts, olives, &o. It 
 ^i**- 15. ig made in various sizes. 
 
 The No. 1 double press 
 (not shown) is furnished 
 with 4 cake-boxes, suit- 
 able for making 4 ta- 
 pered cakes at one press- 
 ing, each about 2 ft. 5 in. 
 long, by lOi^ in. wide at 
 one end, and 7^ in. at 
 the other, when using 
 linseed, 48 lb. of Bom- 
 bay seed being required 
 to charge the press, and 
 giving a cake weigh- 
 ing about 8 lb. ; the 
 maximum and mini- 
 mum weights of its 
 charges are 60 lb. and 
 40 lb., of the cakes, 
 13 lb. and 6^ lb. The 
 charges vary from 3 to 
 
 6 an hour, being 4 for 
 
 cotton-seed and 5 for 
 linseed; most other seeds are worked the same as linseed, 
 but rape and gingelly are worked twice. By using 2 
 presses for the first time and 3 for the second, 3 presses 
 will crush as much seed as 5. These presses are made of a 
 capacity to take 270-320 lb. seed at a charge, giving cakes 
 of 9-15 lb., and requiring 30-45 minutes for the operation. 
 In all these presses, the hair wrappers, weighing some 26 lb., 
 used in the old process, are dispensed with. 
 
EAW MATERIALS. 
 
 55 
 
 After teiBg sufficiently pressed, the cakes are withdrawn, 
 stripped of their cloths, and pared by the machine shown in 
 Fig. 16, which consists of 2 reciprocating knives moving 
 ahove a table fitted with guides and gauges, and with a 
 screw conveyor in the centre, for discharging the parings at 
 one end. Two boys attending the machine can pare 12-13 
 tons a day. The parings are taken under a very small set 
 of edge-runner mill-stones, which automatically discharge 
 
 Fig. 16. 
 
 them, when sufficiently ground, into an elevator leading to 
 the kettle, where they are worked up with fresh seed. 
 Larger edge-runners are very commonly used for crushing 
 Egyptian cotton-seed ; a set weighing 404 cwt. crush about 
 6 tons per 11 hours. 
 
 The ordinary method of liberating the coco-nut from the 
 shell is to break the latter into 2 or more pieces by blows 
 from a hammer, and to leave these exposed to the sun's rays 
 for a few days, when the kernel contracts, and leaves the 
 shell. Some years since, Messrs. Eose, Downs, & Thompson 
 designed 2 machines for slicing and rasping the dried kernel, 
 or copra, which, in general construction, resembled gigantic 
 mincing-machines. The slicing-machine worked well, and 
 turned out a large quantity, but it was found to be of little 
 value in practice, on account of the frequency with which 
 stones and similar foreign bodies got mixed among the 
 copra, and injured the knives. The rasping-machine also 
 
56 SOAP. 
 
 suffered in a minor degree from the same cause. Moreovep, 
 there was no real gain in using the machines, as they did 
 not reduce the material to a sufficiently fine degree. The 
 first produced thin slices, and the second rendered these 
 granular only, like coarse sawdust, so that it was still neces- 
 sary to pass the material through an edge-runner mill, and 
 no perceptible difference was made in the amount of grind- 
 ing required in this latter. Consequently, both machines 
 have been abandoned, and the broken copra is thrown at 
 once under edge-runners, and then pressed and dealt -jvith 
 much in the same manner as an ordinary oleaginous seed. 
 The firm named estimate the average cost of the machinery 
 adapted to a small mill capable of treating about 40 cwt. of 
 copra daily, and making 24-25 cwt. of oil, and 15-16 cwt. 
 of cake, as follows : — Engine, boiler, edge-runners, pr ssses, 
 pumps, gauges, " hairs," cisterns, pipes, nuts, bags, bagging, 
 and all fittings complete, at about 1000/. The same motive 
 power will drive also the machinery for preparing the fibre 
 from the husk, costing about 150Z. additional. 
 
 The yield of oil varies with the season and the locality in 
 which the seed is produced. In the United States, it is 
 reckoned that for each 1 lb. of ginned cotton there are 3 Ih. 
 of seed, or a total approaching 4000 million lb., half of whici 
 only is required for sowing. One authority estimates that 
 100 lb. of seed give 2 gal. of oil, 48 lb. of oil-cake, and 6 Ibj 
 refuse fit for soap-making; another says that 1 ton of 
 American seed gives 20 gal. of oil; a third, tbat the oil pro-, 
 duct is 37 per cent, of the weight of the kernels ; a fouithj 
 that 2 gal. of oil and 96 lb. of cake are afforded by 1 cwt. of 
 seed ; a fifth, that 1 ton of cotton material yields at the rate 
 of some 35 gal. of oil. 
 
 The crude oil from new seed is clear and of a claret colour, 
 but that from old or heated seed is opaque and much darker 
 in colour. When refined it much resembles yellow olive-oil, 
 and has a pleasant, sweetish flavour; sp. gr., 0" 925-0 "9306 ; 
 congealing-point, 34° F. (1° C.) ; it is largely used in adul- 
 terating other oils, as linseed-oil, sperm-oil, and lard-oil, for 
 
RAW MATEEIALS. 57 
 
 painting, burning in lamps, and lubricating, but for this 
 purpose its tendency to become " gummy,'' i. e. to " dry," 
 or oxidize, is objectionable. It is extensively mixed witb 
 olive-oil, and often replaces it altogether ; as a preventive 
 measure, the Italian Government has levied a heavy duty on 
 its importation. Large quantities of it are consumed by 
 soap-makers, in combination with other oils and fats. For 
 lubricating purposes, some manufacturers prepare a " wintey 
 oil " from it, which does not thicken in cold weather, by pre- 
 cipitating and removing the stearin; but its gumminess 
 must limit its application. The stearin so removed is 
 usually made into soap. Although the oil itself is liquid at 
 ordinary temperatures, the solidifying-point of its. fatty acid 
 is about 98°-100° F. (37°-38° C), and it enters very largely 
 into the composition of the lower qualities of blue mottled 
 
 Liiuseed-oil. — Almost the whole of the flax now grown 
 is produced from the Linum usitatissimum, and after the crop 
 is harvested, the first operation is the removal of the seeds 
 by a mechanical process termed " rippling." 
 
 The supplies of linseed for crushing are furnished chiefly 
 by Eussia and India. It is found that, as a general rule, 
 the colder the climate in which the seed is grown, the greater 
 are the drying properties of the oil, but the worse is its 
 colour. In India, preference is given to white seed, as 
 yielding 2 per cent, more oil, affording it more freely, and 
 giving a softer and sweeter cake, than the red seed ; the 
 latter, moreover, always comes to market largely mixed with 
 rape-seed, which is very difficult of separation, and greatly 
 depreciates the market value. Oil from unripe seed is 
 watery. The seed should always be kept for 3-4 months in 
 a dry place, as the oil furnished after this lapse of time is 
 much more abundant than when the expression takes place 
 immediately after the harvest. The seed is crushed and 
 pressed in the manner described above. The best and finest 
 oil is that which is " cold-drawn ; " it is paler, less odorous, 
 and less flavoured, but the yield is only 21-22 per cent, of 
 
58 SOAP. 
 
 the seed. By the aid of a temperature not exceeding 200° F. 
 (93^° C), and powerful and long-continued pressure, as much 
 as 28 per cent, of very good oil can be obtained. The cake 
 forms a valuable cattle-food. The Italian variety is said to 
 have a much more highly oleaginous seed than the Eussian. 
 
 Linseed-oil has a faint colour, and mild odour and flavour, 
 when pure, but the commercial article is dark-yellow, with 
 sharp repulsive flavour and odour. Its sp. gr, is • 930 ; at 
 0° F. (- 18° C), a little solid fat separates out ; at - 4° F. 
 ( — 20° C), it solidifies. By exposure to the air, after heating 
 with lead oxide, it rapidly dries up to a transparent varnish. 
 The fresh oil saponifies readily, giving a yellow and very 
 soft soap with soda ; by saponification, it yields 95 per cent, 
 of fatty acids, chiefly linoleic, with a little oleic, palmitic, 
 and myristic acids. It dissolves in 1 ■ 6 parts of ether, and 
 in 32 parts of alcohol at 0"820 sp. gr. The oil is very ex- 
 tensively used in the manufacture of paint, printing-ink, 
 floorcloth, artificial indiarubber, oil-varnishes, and soft-soap. 
 For artists' use, it is purified by shaking up with whiting, 
 and warming. Linseed-oil is never met with in commerce 
 really pure, nor even is the seed itself. Previous to the 
 Crimean War, it was a recognized custom at the Black Sea 
 ports to add 1 measure of hemp or other seed to every 39 of 
 linseed. Since then, the proportion has advanced to 1 in 19, 
 in addition to which, the Indian seed is grown mostly as a 
 mixed crop with mustard and colza ; pure linseed-oil can 
 only be obtained by picking out the seeds individually. 
 
 Hempseed-oil. — The seeds of the hemp-plant, so well 
 known as a fibre-producer, are valued for their oil. It 
 is from Bussia and Lorraine that the seed for expressing 
 mostly comes. When the fibrous stems are tied in bundles, 
 the seed is rudely threshed out, and spread in thin layers 
 under cover to dry. The extraction of the oil is performed 
 in the same manner as with other seed-oils. The proportion 
 of oil contained in the seed is about 34 per cent, on an 
 average ; the yield varies from 25 to 30 per cent. The oil 
 is at first greenish- or brownish-yellow, deepening with 
 
EAW MATERIALS. 59 
 
 exposure to the air; the flavour is disagreeable, and the 
 odour is mild. It has a sp. gr. of -9252 at 59° F. (15° C.) ; 
 it thickens at 5° F. ( - 15° C), and solidifies at - 1 3° to - 18° F. 
 (-25° to -27^° C.) ; it dissolves in 30 parts of cold alcohol 
 and any proportion of boiling ; it saponifies with liiffioulty, 
 forming a soft soap, but less soft than that from linseed-oil. 
 It is locally consumed largely for lighting, but its most 
 important application is for making soft-soaps. 
 
 Colza- and Rape-oil are identical, and are derived 
 from the seed of several species or varieties of Brassica, chiefly 
 B. campestris and B. Napus (Napa oleifera), cultivated chiefly 
 on the Continent and in India, the shipments from which 
 latter place reached 3,193,488 cwt. in 1877-8. 
 
 The oil is extracted from the seed by the usual methods ; 
 its sp. gr. is 0-912 to 0-920, and it congeals at 21° F. 
 ( — 6° C). Its colour is brownish yellow, and it is chiefly 
 used for illuminating and lubricating purposes, and in lesser 
 quantities for making soft soaps. 
 
 Gingelly-, Sesame-, Til-, or Benne-oil.— Gin- 
 gelly-oil, whose name is variously spelt, is obtained from the 
 seeds of Sesamum indicum [orientale], an annual plant 2-4 ft. 
 high, indigenous to India, but long since propagated by 
 cultivation in almost all tropical and sub-tropical countries, 
 and now found nowhere in the wild state. There appears to 
 be only one true species, but Indian cultivators distinguish 
 two varieties— a white-seeded, called mffed-til ; and a black- 
 seeded,, called kala-til. 
 
 In France, where this oil is very largely prepared, it is 
 usual to subject the Levant seed, which is considered the 
 best, to 3 processes of expression. After the first simple 
 expression, affording superfine (mrfine) oil, the cakes are 
 softened with cold water, and again pressed (pression a froid 
 or froissage), and finally they are treated with steam and hot 
 water for a third pressing (pression a chaud or rahat). The 
 average product from 100 lb. of seed is 30 lb. of oil by the 
 1st pressure, 10 lb. by the 2nd, and 10 lb. by the 3rd. 
 Calcutta seed gives 47 lb. : 36 lb. by the pression a froid. 
 
60 SOAP. 
 
 and 11 lb. by the presaion a chaud. Bombay seed affords 
 also 47 lb. : 25 lb. superfine, 11 lb. by the pression a froid, 
 and 11 lb. by tbe pression a chaud. This last is contrary to 
 the experience of Dantzig seed-crushers, as mentioned pre- 
 viously. The commercial oil has a sp. gr. of • 923 at 59° F. 
 (15° C), and some extracted by ether, • 919 at 73J° F. (23° C). 
 This latter solidified at 41° F. (5° C), becoming turbid at 
 several degrees above this point ; yet the congealing-point 
 of the ordinary oil is placed at 32° P. (0° C.) by Prof. A. B. 
 Prescott, and at 23° F. ( - 5° C.) by Dr. Pohl. Visible ebulli- 
 tion commences at 212° F. (100° C). At ordinary tempera- 
 tures, it is more fluid than ground-nut-oil, and is less liable 
 to change under the influence of the air ; indeed, when well 
 prepared, it is said to keep for years without manifesting any 
 rancidity. The oil is essentially composed of olein, which is 
 sometimes present to the extent of 76 per cent., but it is not 
 invariable in commercial' samples. Among the other fatty 
 acids, are stearic, palmitic, and myristic. The oil is fre- 
 quently adulterated with ground-nut-oil. It is said that 
 10 per cent, of gingelly-oil in admixture with other oils may 
 be detected by shaking 1 grm. of the oil with 1 grm. of a mix- 
 ture of sulphuric and nitric acids previously cooled, when 
 a fine green colour is produced which no other, oil exhibits. 
 The local uses of gingelly-oil are for. cooking, medicine, 
 anointing the body and hair, absorbing the fugitive odours 
 of plants, and illumination. In Europe, the superfine 
 quality largely replaces olive-oil for domestic purposes, and 
 the other grades are employed by soap-makere. 
 
 Ground-nut-, or Arachis-oil, — The ground-nut or 
 pea-nut, AracMs hypogcea, is very widely cultivated in all 
 tropical and sub-tropical countries, for the sake of its oily 
 seeds. The American crop for 1880 amounted to 2,820,000 
 bush., nearly one-half of which was grown in Tennessee. In 
 Java, the oil is extracted by drying the seeds in the sun, and 
 then' subjecting them to pressure. In European mills, the 
 nuts are first cleaned, then decorticated and winnowed,. by 
 which the kernels are left perfectly clean. These are 
 
SAW MATERIALS. 61 
 
 cmslied like any other oil-seed, and put into bags, which 
 are introduced into cold presses; the expressed oU is re- 
 fined by passing through filter-bags. The residual cake is 
 ground very fine, and pressed under 3 tons to the inch, in 
 the presence of steam-heat ; this affords a second quantity of 
 oil, inferior in quality to the cold-pressed. The usual pro- 
 duct is 1 gal. of oil from 1 bush, of nuts by the cold 
 process, beside the extra yield by the hot-pressing. In 
 France, where the oil is most largely prepared, 3 expres- 
 sions are adopted, as with some sorts of gingeUy : the first 
 gives about 18 per cent, of superfine oil, fit for alimentary 
 purposes ; the second, after moistening with cold water, 
 affords 6 per cent, of a fine oil, suitable for lighting and for 
 woollen-dressing; the third, after treating with hot water, 
 yields 6 per cent, of rahat, or oil applicable only to soap- 
 making. In India, the total mean yield is 37 per cent, at 
 Pondioherry, and 43 in Madras. The cold-pressed oil is al- 
 most colourless, of agreeable faint odour, and bland olive-like 
 flavour. The best has a sp. gr. of about 0-918, or 0-9163 at 
 59° F. (15° C.) ; it becomes turbid at 37^° P. (3° C), con- 
 cretes at 26^°-25° F. (-3° to -4° C), and hardens at 19^° F. 
 ( — 7° C). By exposure, it changes very slowly, but thickens 
 with time, and assumes a rancid odour and flavour. As an 
 illuminating-oil, it has feeble power, and its chief industrial 
 uses are for soap-making and lubricating, particularly the 
 former. Locally, it is employed for cooking and burning, 
 and as a general substitute for olive-oil. Indeed, very large 
 quantities are readily passed off as olive-oil in European 
 markets. As a rule, the seeds are exported in a raw state 
 to such centres as London, Marseilles, Bordeaux, Nantes, 
 Dunkirk, Hamburg and Berlin, where they are crushed, and 
 the oil passes into general commerce without maintaiuing its 
 identity. Thus statistics concerning it are meagre. 
 
 Niger, Kersanee, or Kam-til Oil. — The "Niger seed" 
 of African commerce, and the ram-til or kersanee of Indian 
 cultivators, is the product of Guizotia oleifera. The plant 
 grows wild on the Gold Coast of Africa, and is cultivated in 
 
62 SOAP. 
 
 Abyssinia, and in many parts of India, especially Mysore and 
 tlie Decoan ; here the seed is sown in July-Angust, after the 
 first heavy rains, the fields being simply ploughed, and 
 neither weeded nor manured. The crop is cut 3 months 
 after the sowing, and, after being sun-dried for a few days, 
 the seed is threshed out, the produce being about 2 bush, an 
 acre. By the common country mills, only 25 per cent, of oil 
 is got from the seed, but better appliances bring the average 
 up to 35. The oil is limpid, clear, pale, and sweet-flavoured, 
 and is used as an edible oil by the poorer classes of India, 
 and commonly as a lamp-oil. Though much inferior to 
 gingelly-oil, it is frequently used as a substitute for it, and 
 to adulterate both this and castor-oil. The oil contains but 
 little stearic or palmitic acid, hence soap made from it, 
 though very white, is soft. The cake is an esteemed food 
 for milch cows. 
 
 Dika-fat. — The seeds of Irvingia Barteri, the dika of 
 West Africa, afibtd 60 per cent, of a solid fat resembling 
 cacao-butter, fusing at 86°-91J° F. (30°-33° C), containing 
 myristin and laurin, and capable of making very fine soaps. 
 Much of the dika-fat imported into this country is almost as 
 hard as stearin, with a reddish colour from suspended impuri- 
 ties, and a fatty acid melting at above 120° F. (49° C.) ; its 
 soap is very hard. 
 
 Shea-, Galam-, or Bambouk - butter. — The ce, 
 shea, or butter-tree of West Africa (Butyrospermum [Bassia] 
 Parhii) forms miles of forest on the south bank of the 
 Niger, and the same or an allied species, locally termed lulu, 
 is common on the river Djour, in the Bahr el Ghazal pro- 
 vince, where its " butter " is used by the natives in cooking. 
 The seeds, as large as pigeons' eggs, are exposed for several 
 days to dry in the sun, and reduced to flour in a mortar ; the 
 flour is placed in a vessel, sprinkled with warm water, and 
 kneaded to the consistence of dough. When the kneading 
 has proceeded so far that greasy particles are detached by 
 the addition of hot water, this last operation is repeated until 
 the fat is completely separated, and rises to the surface. 
 
EAW MATEBIALS. 63 
 
 The fat is then collected, and boiled over a strong fire, with 
 constant skimming, to remove any remaining pulp. When 
 sufficiently boiled, it is poured into a damp mould, and, when 
 set, is wrapped in leaves, and will keep thus for 2 years. 
 The yield is 30-40 per cent. The "butter'' is greyish 
 white, with sometimes a reddish tinge, and may be rendered 
 quite white by repeated filtration in a warm closet; it 
 resembles tallow in appearance, but is more unctuous, and 
 greases the fingers ; it has a faint characteristic odour, and a 
 sweetish flavour. According to one authority, the fatty acid 
 is margario, and its melting-point is 142° F. (61° C); ac- 
 cording to others, there are 2 fatty acids, stearic and oleic, 
 the melting-point of the mixture being 156° F. (69° C). Yet 
 another authority states the proportions as 7 of stearin to 3 
 of olein, and states that when acidified and distilled, it gives 
 a yellow, crystalline fatty acid melting at 133° F. (56° C), and 
 when pressed, at 151° F. (66° C), but that it cannot be used 
 for candle-making, as it is comparatively soft, despite its high 
 melting-point, and is very liable to give a red smoky flame. 
 It dissolves entirely in the cold in turpentine-spirit, incom- 
 pletely in ether, and is almost insoluble in alcohol. It sapo- 
 nifies readily with alkalies. There is also present in it, in the 
 proportion of ^-| per cent., a substance resembling gutta- 
 percha, and which has been called " gutta-shea." This is 
 insoluble in alcohol, alcohol and ether mixed, acids, and 
 alkalies ; but slightly soluble in pure ether, and in ordinary 
 animal and vegetable fats. It can be removed from the fat 
 by dissolving in a mixture of • 3 parts ether and 1 alcohol, 
 when it separates in a filmy state, more readily if the fat be 
 first saponified. It exists ready-formed in the oil, some in 
 suspension, removable by filtration, some in solution in the 
 fat. The fat itself, shea-butter, is imported iuto England to 
 the extent of upwards of 500 tons annually, from Sierra 
 Leone, for use in the manufacture of hard soaps, chiefly in 
 combination with other oils. It is largely consumed in some 
 of the Continental candle-factories. The natives employ it 
 for food, for anointing, and for lighting. 
 
64 SOAP. 
 
 Vegetable Tallow is a sort of generic name for a 
 mimljer of hard fats olDtained from various members of the 
 vegetable kingdom in tropical and sub-tropical countries ; 
 the history of many of these products is often very hard to 
 trace, and it not unfrequently happens that two such sub- 
 stances, nominally from the same district, vary considerably in 
 value for soap-making purposes. Hence th e manufacturer will 
 do "well to test the merits of each lot, before purchasing it. 
 
 (a) Chinese. — The vegetable tallow of China is produced 
 by the " tallow-tree " {StiUingia [Groton, Sapium, Excoecaria] 
 sebiferd). It is a native of China and the adjacent islands, and 
 has been introduced and naturalized in India and the warmer 
 parts of America. In China, it is chiefly cultivated in the 
 province of Chekiang, and the adjacent Chusan Archipelagoj 
 in Kiangse, and in Hoopih. In India, it thrives in the North 
 West Provinces and the Punjab, especially at Paonee, in 
 Gurhwal ; at Ayar Tali and Hawul Baugh, in Kumaon ; and 
 in the Kangra Valley. The tree flourishes equally well on 
 low alluvial plains, in the rich mould of canals, in sandy 
 soils, and on mountain slopes. Its fruits are about ^ in. in 
 diameter, and contain 3 seeds, thickly coated with a fatty 
 substance, whence the " tallow " is obtained by treatment with 
 steam and hot water. A very inferior oil is obtained from 
 the seeds or kernels also, which are crushed between mill- 
 stones, and steamed. The tallow itself is purified by melt- 
 ing and subsidence, and is then poured into moulding-tubs, 
 sprinkled inside with dried red earth, to prevent adhesion. 
 "When cold, it is turned out in masses of 80 lb., a hard, 
 brittle, pure opaque white, tasteless and odourless fat. Its 
 melting-point varies from 98J° to 111^° F. (37°-44:° C), and its 
 composition is almost pure stearin. The yield is about 20-30 
 per cent, of the weight of the seeds. Its chief and almost 
 only application in China is for making candles, which are 
 usually coated with wax ; in India, it has been tried as a 
 lubricator ; and it is found to burn well, without smoke or 
 smeU. An immense native trade in it is carried on in China. 
 
 (6) Malayan. — ^In Borneo, Java, and Sumatra, are several 
 
RAW MATERIALS. 65 
 
 species of Eopea, producing nuts, whicb, -when compressed, 
 yield fatty oils, extensively used under the names of " vege- 
 table tallow " and " vegetable wax." Three species of this 
 genus are common in Sarawak; the one most valued for 
 producing oil is a fine tree growing on the banks of the 
 Sarawak river to a height of 40 ft. ; its fruits are produced 
 in the greatest profusion about December-January, and are as 
 large as walnuts. These nuts are collected by the natives, 
 and yield a very large proportion of oil, which, on being 
 allowed to cool, takes the consistence of sperm, and in appear- 
 ance very much resembles that substance. In England, it 
 has proved to be an excellent lubricator for steam machi- 
 nery, far surpassing even olive-oil ; and it has been used in 
 Manilla in the manufacture of candles, and found to answer 
 admirably. As it becomes more common, it will doubtless 
 be applied to many other purposes. This oil has nearly the 
 consistence, and something of the appearance, of tallow, but is 
 generally yellower. It is found in the markets in rolls 1^3 in. 
 in diameter. It is used in the interior almost exclusively for 
 lighting and culinary purposes. A vegetable tallow is also 
 afforded by the seeds of Tetranthera laurifolia, widely dispersed 
 over Tropical Asia, and the Eastern Archipelago, as far south 
 as New Guinea. In Java and Cochin China, it is commonly 
 used for making candles, notwithstanding its disagreeable 
 odour. The exports of vegetable tallow from the state of 
 Sarawak in 1879 were valued at 7305 dollars (of 4«. 2d.). 
 
 Both Chinese and Malayan kinds of vegetable tallow, like 
 shea-butter, are glycerides, and contain about 95 per cent, of 
 saponifiable matter, which has much less olein in it than 
 animal tallow. 
 
 (c) African. — A so-called vegetable tallow or butter is 
 obtained in Sierra Leone from Peniadesma butyracea ; the 
 tree yields from its several parts, especially the fruit when 
 out, a yellow fatty juice. The fat of a species of Peniadesma, 
 under the name of hanya, is used for culinary purposes in the 
 neighbourhood of Zanzibar, and is said to remain sweet for a 
 long time. 
 
66 SOAP. 
 
 SECTION C.—BOSIN. 
 
 Kosin or Colopliony. — The several kinds of rosin, 
 colophony, &c., are the- solid residues left after the distillation 
 of the turpentines, which are themselves liquid oleo-resins 
 obtained by tapping the trunks and branches of the ConifercB, 
 or , pines. The so - called " pine barrens " of the United 
 States extend from Virginia to the Gulf of Mexico, but the 
 extraction of turpentine is an industry mainly developed 
 in North Carolina. The production in the United States 
 in 1876 is given as 300,000 casks of turpentine spirit and 
 1,500,000 barrels (of 280 lb.) of rosin. American rosin is 
 characterised by a peculiarly fragrant smell, in which French 
 rosin is deficient, and this smell is retained by the soap made 
 from the rosin. During the American civil war, when no 
 rosin was to be had from thence, the small stores of it in 
 England were so much valued for this fragrance in soap, that 
 soap-makers were compelled to pay more for American rosin 
 than for tallow. The chief seat of the French rosin industry 
 is in the departments of Landes and Grironde, where the 
 extraction of the crude oleo-resin and its subsequent treat- 
 ment are carried out in a more systematic manner than in 
 ^merica. 
 
 The rosin of commerce varies very much in colour ; the 
 finest grade is known as " window-glass," and all shades 
 occur from this down to a black opaque rosin. 
 
 The lighter shades only can be used for better-class soaps. 
 Such are liable to contain a little turpentine, which, to some 
 slight extent, injuriously afieots the hardness of the soap; 
 and they are apt to become unpleasantly soft in very hot 
 weather. Opaque rosins contain turpentine, and in rare 
 cases, water. Dark rosins may be improved in colour, and 
 deprived of suspended impurity, by being melted, allowed 
 to settle, and then boiled on a weak solution of common 
 salt. Dark rosin may also be distilled with steam under 
 a pressure of 10 atmos. to make it nearly white for soap- 
 
BAW MATEEIALS. 67 
 
 making. Like many other distilled products, however, it 
 has a tendency, both alone and' in combination, to oxidize 
 rapidly, and deteriorate in colour. When fine rosin is 
 unusually dear, however, this process may he employed 
 with advantage. It is somewhat remarkable that if 2 rosins, 
 French and American, of equally fine colour, be converted 
 into soap, the soap from the American rosin will be some 
 shades lighter than that from the Trench. In carelessly 
 prepared rosin, bits of stick, leaves, &c., are apt to occur, 
 all which, if they find their way into the soap-copper, 
 seriously damage the colour of the ultimate product. 
 
 Eosin is never employed alone for soap, but always in con- 
 junction with fats ; it has been described as an ameliorator, 
 and is also a cheapener ; it contributes to the popular quali- 
 ties of soap, rendering it more readily soluble, and forming a 
 copious lather in laundry and household soaps. In them the- 
 proportion varies from 15-20 per cent, of the fatty matter 
 employed, to an equal weight, or even more. Hard soaps for 
 manufacturing purposes rarely contain it. It may be sapo- 
 nified alone, and the result mixed with a fat-soap in due pro- 
 portion, or the whole may be saponified together. The result 
 is the same, and the choice of methods depends upon conve- 
 nience in working ; but the former is preferable with impure 
 rosin, in order to give it as many changes of lye as possible, and , 
 thus to wash out suspended impurities, such as leaves, bits of 
 stick, &c., alluded to above. Our annual imports of rosiu 
 average over 50,000 tons. 
 
 SECTION D.-~8UNI>BIEB. 
 
 Sapouifiable "Waste matters. — Besides the raw 
 materials used by the soap-boiler, enumerated above, are 
 various bye-products of other manufactures, among which 
 may be mentioned — the olein or oleic-acid from candle-works ; 
 the grease recovered from the wash- water of woollen factories, 
 which is very apt to contain unsaponifiable oils, and should 
 
 F 2- 
 
68 • SOAP. 
 
 be employed with, caution;* the "foots "from various oil- 
 refineries, which either contain strong mineral acids, or are 
 partly-formed soaps when an alkaline refining process has 
 been used; waste fats recovered by carbon bisulphide or 
 petroleum-spirit, also liable to contain unsaponifiable oils ; 
 " suint," or the grease derived from natural wool, accompanied 
 by potash salts ; and, especially in France, the yolks of eggs 
 (of which the whites have been used in the preparation of 
 albumen), which contain a considerable percentage of fatty 
 matter. This list might be largely increased, since the 
 soap-pan appears to be the natural destination of any rough 
 fat-containing material which can be turned to no other 
 purpose. 
 
 The value of a soap-making material is best ascertained by 
 saponifying a weighed quantity (say 5-10 grm.') with soda, 
 dissolving the soap in water, decomposing it with a mineral 
 acid, and then washing, drying, weighing, and examining the 
 resultant fatty acids, as will be described later on. 
 
 Water. — The purity of the water employed in the factory 
 is a matter of great moment to the soap-boiler. As a rule, 
 spring-water should be avoided, and river-, lake-, or even 
 rain-water should be employed whenever possible. If it 
 contains suspended impurities, these should invariably be 
 Tcmoved by subsidence or filtration. Organic impurities, if 
 colourless, may be disregarded. The great enemies of the 
 soap-maker are the soluble salts of lime, of alkaline earths, 
 and sometimes even of metals, occurring in natural waters, 
 because all these bases form insoluble soaps in the soap-copper, 
 and use up large quantities of fat to no purpose, since these 
 insoluble soaps are of no market value themselves, and if 
 disseminated in a marketable soap, injure jits appearance 
 greatly. The hardness of water may be determiaed by 
 " Clark's test " (described in most text-books of chemistry), 
 
 * As this grease can scarcely be used by the soap-maker without being 
 previously distilled, the account of its recovery and preparation is 
 deferred to Chap. XI., upon the distillation of fatty matters, under the 
 heading of Candles. 
 
BAW MATERIALS. 
 
 69 
 
 in which an alcoholic solution of pure soap is employed. 
 The amount of soap wasted by hard waters may be ascer- 
 tained from this table, in which the hardness is supposed 
 to be caused simply by lime salts. 
 
 Degree of 
 HardneES. 
 
 5° 
 10 
 15 
 20 
 
 In 1000 lb. Water. 
 
 Lime. 
 
 lb. 
 0-25 
 J50 
 0-76 
 1-01 
 
 Gypsum. 
 
 lb. 
 0-61 
 1-23 
 1-84 
 2-45 
 
 Soap decomposed 
 
 by 1000 lb. 
 
 Water. 
 
 lb. 
 
 3-66 
 
 7-31 
 
 11-12 
 
 14-75 
 
 If no other than hard water is available, one of the various 
 plans for softening it should be adopted under the guidance 
 of a chemist, such as the addition to the water of milk of lime, 
 either alone or with barium chloride, or of sodium silicate. 
 
 Salt. — As will be seen in the sequel, common salt plays a 
 very important part in soap-boiling, and what has been said 
 with regard to water applies equally to it. The purest 
 kind is rock-salt freed from insoluble matter; next in order 
 comes salt from brine-springs, such as those in Worces- 
 tershire and Cheshire; while sea-salt contains so many 
 other salts besides sodium chloride, especially magnesium 
 chloride, that it should be avoided if possible. "When that 
 is not the case, it should be dissolved in water, and the 
 magnesia removed by the addition of sodium silicate, when 
 the insoluble magnesium silicate should be allowed to sub- 
 side before the brine is used. In connection with salt, it 
 will be found convenient to remember that strong brine, or 
 a saturated solution of salt, contains ^ its weight or 25 per 
 cent, of sodium chloride, that its sp. gr. is 42° Tw. (25° B.), 
 and that if nothing else be present in solution, every degree 
 Baume of sp. gr. corresponds to 1 per cent, of salt. 
 
70 SOAP. 
 
 CHAPTER III. 
 
 EAW MATEKIALS; — Eepining, Clarifying, and 
 Bleaching. 
 
 The various processes under this head may at first be hroadly 
 divided into " mechanical " and " chemical," although each, 
 especially the latter, is capable of many subdivisions. They 
 have for their object, firstly, the removal of all extraneous 
 matters from the oil, such as animal or vegetable fibre and 
 tissue incidental to the modes of preparation (as in olive- 
 and other seed-oils, badly-rendered tallow, &o.); secondly, 
 the removal of resinous substances dissolved in the oil, of 
 which the refining of cotton-seed-oil is a notable example; 
 thirdly, the removal of fraudulent admixtures, such as lime, 
 glue, &o. ; fourthly, the correction of rancidity ; and fifthly, 
 where the preceding operations do not suflSciently improve 
 the colour of the oil, its bleaching by chemical processes. 
 These will now be considered under their various heads, 
 and it is obvious that much care and judgment are re- 
 quired in the selection of the particular method or com- 
 bination of methods suitable to the refining of any given 
 oil. The tei-m oil will, in this connection, include melted 
 fats, as weU as those which are liquid at the ordinary air- 
 temperature; almost all the operations described in this 
 chapter can only be performed upon liquid substances. 
 
 The first and most important method, to be employed 
 either alone, or as a sequel to others, is that of simple but 
 prolonged subsidence, on a large scale. Where necessary, 
 the tanks employed may be heated by steam-coils or steam- 
 jackets. These must be used with caution, however, since con- 
 vection currents are set up, which interfere materially with 
 the steady deposition of impurities. The tanks should be 
 
RAW MATERIALS. 71 
 
 provided with stop-cooks or valves at various levels, in order 
 to draw off separately the purified oil, and the "foots," 
 ■which is a generic name for that concentration of impurities 
 in a small quantity of oil, which accumulates at the bottom 
 of vessels in which oil-refining is carried on. For example, 
 olive-oil is mostly subjected to no process of purification, 
 beyond what is attained by allowing it to deposit impurities, 
 and repeated deoantation. But for the best qualities, farther 
 purification is necessary, not only to secure limpidity, hut 
 a capacity for lengthened preservation, by eliminating the 
 water, mucilage, and parenchymatous matters, some of 
 which, if not removed, are liable to act as ferments. Coco- 
 nut-oil is another example of purification by simple subsi- 
 dence and filtration. 
 
 When prolonged subsidence fails to remove suspended 
 impurities, filtration may be tried with advantage. In 
 Fj ance the oil to be purified is received into perforated 
 boxes carpeted with carded cotton (wadding) ; elsewhere, 
 cotton tissue interposed between beds of granular and 
 washed animal charcoal form the filter ; also a bed of dry 
 moss, on the " Grouvelle et Jaunez" system ; also layers of 
 sand, gypuum and coke; also alternate beds of sand and 
 vegetable charcoal, according to Denis de Montfort's plan ; 
 also carbonized schist and peat, by Cossus' method; also 
 clay heated to 200° F. (93° C), as proposed by Wright; also 
 by introducing China-play and allowing the oil to stand at 
 a moderate temperature, then filtering through cotton, as 
 adopted by A. Bizzarri. It is usual to assist the action of 
 the filter in some way, mechanically, owing to the viscidity of 
 oils. A simple mode of doing this is so to arrange the filter 
 that there is a considerable pressure upon the filters from 
 a " head " or column of the oil to be filtered. This may be 
 conveniently carried out by using closed bags of filter-cloth 
 confined in cylindrical wire cages as the filtering medium ; 
 the mouth of each bag is tied tightly over a stop-cock con- 
 nected with a main pipe which delivers the oil from a tank, 
 and this tank may be placed at any desired level above 
 
72 
 
 SOAP. 
 
 the filters. With oils that are vei:y thick, or even solid, at 
 the atmospheric temperature, it is necessary to enclose the 
 whole arrangement in a heated chamber. Another mode of 
 hastening filtration is by utilizing the atmospheric pressure 
 upon the surface of the filter-bed ; this is conveniently done 
 by placing the filtering mediunl in any suitable vessel, to 
 the bottom of which is adapted a pipe for the exit of the 
 filtered oil, which pipe is connected with an air-pump arjd 
 small engine, by which a partial vacuum is maintained in it. 
 In this case the oil is practically sucked through the filter. 
 Still another mode is that of Pietro Isnardi, of Livornial 
 Tuscany, which received an award at the Vienna Exhibition. 
 
 Fig. 17. 
 
 This apparatus, Pig. 17, consists of a boiler full of water, 
 serving as a water-bath for 2 turned-iron cylinders b, receiving 
 the oil from the reservoir c, a suction- and force-pump d, and 
 a filter e, containing perforated trays whose holes are filled 
 with wadding. This apparatus enables the oil to be filtered 
 without coming into contact with the air, and at an elevated 
 temperature which can be regularly maintained. As a useful 
 adjunct to filters of any kind, some form of filter-press will 
 be found very useful, for removing the last traces of oil from 
 the residues left on the filters. 
 
 When impurities are not removed by subsidence or filtra- 
 tion, recourse may be had to the action of acids or alkalies 
 
EAW MATEBIALS. 73 
 
 upon them. There are several methods of applying mineral 
 acids to the purification of oils. Thenard's process consists 
 in gradually adding 1-2 per cent, of strong sulphuric acid to 
 oil previously heated to 100° T. (38° C), and mixing by con- 
 stant agitation.* When the action of the acid is complete, 
 the oil, after 24 hours' rest, appears as a clear liq[uid, holding 
 flooculent matter in suspension ; a quantity of water heated 
 to 140° F. (60° C), equal to about f of the oil, is added, and 
 the mixture is well agitated until it acquires a milky 
 appearance. It is then allowed to settle for a few days, 
 when the clarified oil rises to the surface, while the flocculent 
 matter falls to the bottom with the acid liquid. The oil is 
 then drawn off, and washed in another vessel by agitation 
 with half its bulk of warm water; but it requires to be 
 filtered to make it perfectly clear. This process is largely 
 used for refining linseed-oil. A mechanical mixer may be 
 used, or the whole mass may be well agitated by the injection 
 of finely divided streams of air, through a perforated pipe. 
 Cogan operates upon about 100 gal. of oil with about 10 lb. 
 • of sulphuric acid, previously diluted with an equal bulk of 
 water. This mixture is added to the oil in 3 portions, the 
 oil being well stirred for about an hour after each addition. 
 It is then stirred for 2-3 hours to ensure perfect mixture. 
 After being allowed to stand for 12 hours, it is transferred to 
 a copper boiler with a perforated bottom, through which 
 steam enters and passes in a finely divided state through 
 the oil, raising it to the temperature of 212° F. (100° C). 
 This is continued for 6-7 hours, And the oil is transferred 
 to a cooler, shaped like an inverted cone, terminating in a 
 short pipe, and provided with a stop-cock at the side, a 
 little distance from the bottom. After standing till the 
 liquids are separated, generally about 12 hours, the acid 
 liquor is drawn off through the pipe at the bottom, and the 
 
 * The first effect of the acid is a powerful dehydrating action, which 
 removes the water that holds the impurities in solution; next it chars 
 the impurities themselves, by which they are rendered insoluble and 
 are partially destroyed. 
 
74 SOAP. 
 
 clear oil by the stop-cook in the side of the cooler ; all below 
 this tap is generally turbid, and is clarified by subsidence, or 
 mixed with the next portion of oil. 
 
 These acid processes are efficient when well conducted, but 
 too much or too little acid may spoil the product, because, as 
 most of them depend for their action upon the fact that 
 strong sulphuric acid chars organic substances by the removal 
 from them of the elements of water, it chars the fibre in the 
 oil first, but if more acid than necessary for this be present, 
 it attacks the oil iiself, and oil thus stained by charring 
 cannot be completely decolorized again. 
 
 On this account perhaps, more general preference seems to 
 be accorded to alkaline processes. Evrard's, which is chiefly 
 applied to colza- and rape-oils, is as follows. The oil, drawn 
 cold, or at very slight heat, is well crutched up with a weak 
 lye of soda or potash, and allowed to settle. Two layers 
 soon form — a neutral oil floating on an alkaline liquid, a 
 mixed emulsion intervening. The alkaline liquid is dravra. 
 off, and replaced by slightly alkaline water, and the whole is 
 left to settle. This is repeated a few times with clear water, 
 till the liquid at the bottom of the settlers is only slightly 
 milky. The oil is drawn off and filtered, and is superior to 
 oil purified by sulphuric acid, being much less corrosive to 
 metal. The turbid residual waters are treated with acid, 
 and give a greasy product fit for soap-making. A much 
 simpler alkaline method adopted in Italy for olive-oil is to 
 add 400 grm. of ammonia, diluted with 800 grm. of water, to 
 every 100 Jcilo. of oil, the whole is then thoroughly agitated, 
 and allowed to stand for 3 days ; after which the clear oil is 
 decanted and filtered. 
 
 One of the most remarkable impurities in fats, arising from 
 methods of preparation merely, is that of lime in bone-fat. 
 This fat has the power of dissolving considerable quantities 
 of lime-salts, especially phosphate and carbonate. No amount 
 of subsidence or filtration will remove them, and their pre- 
 sence in a soap-copper is most objectionable. It is greatly 
 to be desired, therefore, that English makers of this fat 
 
SAW MATBEIALS. 75 
 
 would follow the example of their American confreres, and 
 boil their hone-grease, after removal from the extractors, 
 with a weak solution of sulphuric acid, in lead-lined wooden 
 tanks. This removes all the lime in the form of sulphate, 
 which deposits on the floor of the tank after due subsidence ; 
 it also removes the gelatin and extraneous water entangled in 
 the bone-fat, which cause the crude grease to froth greatly 
 when heated. 
 
 A good example of the removal of resinous substances from 
 oils is afforded by the process adopted for refining and bleach- 
 ing cotton-seed-oil, an industry which has enormously de- 
 veloped, both in England and the United States, within the 
 last 15 years. When freshly expressed from new seed, this 
 oil is of a light-claret colour, which darkens by long keeping, 
 in which case also, the oil becomes more viscid, probably from 
 oxidation of some of its constituents. The colouring matter 
 is almost entirely rosin, which may be removed by agitation 
 at about 140° F. (60° C.) with a solution of sodium carbonate. 
 It is found in practice, however, that a much better result is 
 obtained by the use of a caustic alkali — solution of soda, or 
 potash, or in some rare oases, milk of lime. The amount of 
 alkali thus employed depends entirely upon the quality of 
 the crude oil, and is best determined by a preliminary experi- 
 ment upon a small scale. A solution of caustic soda at about 
 20° Tw. (13° B.) is a suitable strength. Agitation must be 
 thorough, and may be effected by any convenient mechanical 
 means, or by the injection of air, before alluded to. The 
 process is a rapid one ; if the saponaceous liquid does not 
 readily separate from the oil, the addition of a little brine 
 will cause it to do so. The operation is often divided into 2 
 or 3 stages, and occasionally the refined oil is further bleached 
 by one of the oxidation processes, such as by " chloride of 
 lime" or "bleach." 
 
 After all the refining, it should be washed with warm 
 water, allowed to settle, and decanted, or filtered at as low a 
 temperature as possible, especially if an oil be desired that will 
 remain fluid at a low temperature. This process will answer 
 
76 SOAP. 
 
 well for any oil containing rosin. The imperfect soap, after 
 removal, is treated with enough mineral acid to remove all 
 the soda, and the resulting mixture of rosin, fatty acids, and 
 neutral oil is distilled with superheated steam (see Chap. XI.) 
 for the manufacture of fatty acids, the rosin being left in the 
 still as pitch. The chief seat of this industry in England is 
 at Hull. In the United States, the quantity of rosin is so 
 small, that the " foots " from the cotton-seed-oil refineries are 
 made into a curd soap. 
 
 For the removal of fraudulent admixtures from commercial 
 oils, no general rule can be given ; but subsidence, filtration, 
 and boiling with weak sulphuric acid, will generally effect 
 the desired result. Special modes are best sought under 
 the head of Proximate Analysis, which forms the subject 
 of the next chapter. Some of the methods there recom- 
 mended for the laboratory, are capable of being carried out 
 on a large scale. 
 
 Methods for correcting rancidity in oil are as follow : — 
 (a) Agitation with 5 parts of good vinegar, repeating the 
 operation several times. (6) Agitation (5-6 times) of 50 parts 
 of oil with 80 parts of water at 86° F. (30° 0.) holding 12 
 parts of common salt in solution, (c) To 100 litres of oil, 
 are added 2 Mlo. of calcined magnesia; the mixture is 
 agitated i times daily for ^ hour each time for 6 days ; 
 the oil is then filtered ; it must be quickly used, or it wiU 
 become rancid again, (d) Agitation with a weak solution 
 of caustic alkali, or with a moderately strong one of an 
 alkaline carbonate, (e) Prolonged agitation with water. 
 
 Most processes for refining and bleaching oils also deodo- 
 rize them to a certain extent. As many of the odorant 
 principles are more volatile than the oils, they may occa- 
 sionally be removed by merely heating the oil in a closed 
 vessel provided with an exit-pipe. For destroying the dis- 
 agreeable smell of coco-nut-oil for soap-making, it has been 
 recommended to boU it in a wooden vessel by free steam on 
 water containing 6 lb. sulphuric and 12 lb. hydrochloric acid 
 to each ton of oil. Prolonged steamin g will sometimes remove 
 
EAW MATERIALS. 77 
 
 the unpleasant odour characteristic of oily distilled products, 
 although it is liable to damage their colour. 
 
 Many plans of decolorizing oils are in vogue : — (a) Exposure 
 to sunlight in large white glass bottles : the oil soon becomes 
 colourless, but acquires an almost rancid flavour. (6) Agita- 
 tion with 2 per cent, of a solution of potassium permanganate : 
 bleaches effectually, but also leaves a bad flavour, (c) The oil 
 is first agitated with water containing gum, and to the emul- 
 sion thus formed, is added coarsely crushed wood-charcoal; 
 the whole is then slowly warmed to a degree not reaching 
 212° r. (100° C), and when cold, the oil is dissolved out by 
 ether or petroleum-spirit, and the latter is recovered by 
 distillation : the result is good, (d) A process often recom- 
 mended is to pass nitrous acid gas through the oil.* (e) The 
 oil (500 parts) is clarified by addition of 50 parts of China- 
 clay and 50 of water. ,(/) I^^ some cases, it is found ad- 
 visable to use the coagulation of albumen in clarifying oils. 
 The oil to be treated is mixed by agitation at the ordinary 
 air-temperature with a weak solution of albumen in water. 
 The whole is then gradually heated, most conveniently by 
 steam, and when hot enough to coagulate the albumen, this 
 latter collects in clots, enclosing particles of impurity ; after 
 the lapse of sufficient time, these clots subside, and the clari- 
 fied oil is removed by decantation. The process is analogous 
 to that of refining sugar syrups by the serum of blood. 
 
 Many oils are partially or completely decolorized by filtra- 
 tion through, or agitation with, freshly-burnt animal-charcoal 
 or bone-black. The apparatus for filtering is similar to that 
 employed in sugar-refineries, and consists essentially of tall 
 wrought-iron cylinders filled with bone-black, and provided 
 with a steam-jacket to control their temperature. When the 
 charcoal ceases to decolorize, it should be treated with some 
 solvent (carbon bisulphide, or petroleum-spirit) to remove the 
 oil, before it is revivified by calcination. 
 
 Most processes for the bleaching of oils depend upon the 
 oxidization of the colouring matter by some suitable reagent, 
 * See subsequent paragraph, p. 80. 
 
78 SOAP. 
 
 cMefly evolving nascent oxygen in some form. There are, 
 however, instances known in which the colour is destroyed 
 by a reducing agent, such as sulphurous acid, in an aqueous 
 solution, as gas, or arising from the decomposition of an 
 alkaline hyposulphite (e. g. that of sodium) hy a strong mineral 
 acid. It may he laid down as a general rule that oils which 
 ■have been burnt or charred by any previous process cannot 
 be satisfactorily bleached. Experiment alone can determine 
 the particular process best suited to any given oil, having 
 regard to the purpose for which it is to be used. The utmost 
 care is required in using any oxidation process for oils in- 
 tended to be converted into soap, since if the oil itself be 
 oxidized in any perceptible degree, as well as the colouring 
 matter (i. e. if too much of the bleaching reagent be used), 
 the resulting soap will often be worse in colour than if the 
 oil had not been bleached at all, owing to the rapid forma- 
 tion of the same complex acids which gradually make their 
 appearance in rancid tallow. 
 
 Palm-oil and tallow are the two chief fats bleached by 
 the soap-maker. Both may be bleached by pumping air 
 into them in finely divided streams, while they are kept at 
 about 180°-200° F. (82°-93° C.) The colour of tallow may 
 also be removed by boiling it in lead-lined tanks upon a 
 solution of " chloride of lime," or of potassium chlorate, to 
 which a strong mineral acid has been added. No more 
 potassium chlorate than • 3 per cent, on the tallow should 
 be employed. Another mode of bleaching tallo"w, especially 
 for dip-candle making, is to agitate it with the clear solution 
 prepared by digesting manganese black oxide with dilute 
 sulphuric acid, and then allowing the mixture to settle. 
 
 Experiment has shown that the colour of palm-oil may be 
 quite destroyed by heat. To effect this, the oil may be kept 
 for some hours at about 260° F. (127° C.) or it may be put 
 into a closed, horizontal, iron cylinder, and rapidly heated 
 by a fire beneath up to about 464° F. (240° C), at which 
 temperature the colour is destroyed. This process gives rise 
 to most offensive vapours, especially acrolein, and necessi- 
 
EAW MATERIALS, 79 
 
 tates the conduct of operations in a closed vessel, with suita- 
 ble means of condensing the vapours and rendering them 
 innocuous; as they come off at a high temperature, they 
 must not he conducted into a flue until they have been 
 cooled down, and impregnated with water. The details of 
 such an apparatus, which may be applied to other opera- 
 tions, will be further described in a later chapter, dealing 
 with legislative enactments affecting the soap-trade. 
 
 Palm-oil may also be very suitably bleached by potassium 
 bichromate and hydrochloric acid. The oil is made as free 
 as possible from impurities, and, at about 120°-130° F. 
 (49°-54° C), is agitated with a strong solution of potassium 
 bichromate, containing about 1 lb. of the salt to every 
 100 lb. of oil. To this, is added enough hydrochloric acid to 
 form chromium sesquichloride with all the chromium in the 
 bichromate, the quantity of liquid acid necessary of course 
 varying with the amount of real acid contained in it. A 
 slight excess of acid is rather, an advantage than otherwise. 
 The process occupies about an hour, after which, subsidence 
 removes most of the chemicals, while subsequent agitation 
 with hot water renders the oil quite pure enough for the 
 soap-copper, although it is a curious fact that palm-oil has a 
 strong solvent action upon chromium salts, so that it is 
 impossible to remove all the green colour from the oil by 
 washing it, and hence a considerable precipitation of 
 hydrated chromium oxide takes place in the soap-copper. 
 This should be carefully removed with the spent lye, else 
 the result in the soap will be most unsightly. Quite 
 recently, sodium bichromate has been offered as a commercial 
 product, at a less price than the corresponding potassium 
 salt. 
 
 Several years ago, when palm-oil was much more used in 
 soap-making, and " bichrome " was much dearer, than at 
 present, the chromium oxide was thus recovered, and used 
 over again. Excess of milk of lime was added to the solu- 
 tion, and the resulting mixture of lime and chromium oxide 
 was dried by^ a gentle heat, and finally roasted at a com- 
 
80 SOAP. 
 
 paratively low temperature, till it assumed a lively yellow 
 colour. TMs rough calcium cliromate was then, digested in 
 the cold with a slight excess of hydrochloric acid, so that 
 the solution contained calcium chloride and impure chromic 
 acid, and was used for bleaching fresh quantities of oil. In 
 this way the same chromium did duty many times over, 
 but, for reasons given above, there' was always a certain 
 loss of chromium in the series of operations. By whatever 
 process palm-oil is ^bleached, it should be saponified as soon 
 as possible after bleaching, since it is apt to deteriorate in 
 colour (especially if it is allowed to get cold, and is then 
 melted again), becoming more or less brown ; the same 
 remark applies, to a less extent, to other bleached fats. 
 
 A very effective mode of decolorizing fatty matters is to 
 distil them in an atmosphere of superheated steam. This 
 process will be described in Chap. XI., but it may be use- 
 ful here to warn the inexperienced soap-maker, that fatty 
 matters which have been distilled are apt to deteriorate in 
 colour (instead of improving, like a neutral fat), under the 
 influence of air and light, also every time that they are 
 melted and cooled again. Moreover, the colour of a soap 
 from distilled material is decidedly worse than the colour of 
 that from a neutral fat of the same shade. 
 
 In some text-books, and by many adventurers, soap-makers 
 are advised to treat comparatively fluid oils with nitrous 
 acid, in order (1) to bleach them and (2) to solidify them. 
 This is a process which it is as well to avoid; both the 
 bleaching and the hardening effects are apparently very 
 successful; the colour of the oil, however, rapidly resumes 
 its original tint, or worse; and the soap made from the 
 solidified oil is no harder, and often worse in colour, than 
 that from the oil before such treatment. 
 
 There is, however, a very scientific process for the solidifi- 
 cation of liquid oils, which has been worked out industrially 
 by M. St. Cyr Eadisson, of Marseilles. It depends on the 
 laboratory reaction discovered by Warentrapp, that when 
 oleic acid (or olein) is heated with an excess of caustic 
 
EAW MATERIALS, 81 
 
 potash, it is resolved into palmitic acid, acetic acid, and 
 hydrogen. M. Eadisson has shown that caustic soda will 
 effect the same change. Although the process has hitherto 
 been confined to the conversion of oleic acid into palmitic 
 acid, for candle-making, it is applicable to any fluid saponifi- 
 able oil. It requires, however, that the fatty acid,s so pro- 
 duced shall be distilled in order to be made sufficiently good 
 in colour, and hence an account of it is reserved for Chap. XI., 
 in the part of this book relating to Candles. 
 
 One other mode of treatment of neutral fats, preliminary 
 to their saponification, remains to be noticed, and is of 
 very recent origin. It is that by which these neutral fats 
 are deprived of their glycerin before being saponified with 
 soda (or potash). As will be seen in the sequel, the problem 
 of recovering glycerin from the " spent lye " of the soap- 
 maker, is a very difficult one, and in the opinion of several 
 who are well qualified to judge, all glycerin in future will 
 be made from the fats direct, before they are saponified, 
 and not recovered from the spent lye. Detailed informa- 
 ' tion on this subject will be found in Chap. XIII. 
 
82 SOAP. 
 
 CHAPTER IV. 
 
 EAW MATEEIALS ;— Theie Peoximatb Analysis. 
 
 The object of this chapter is to deal with comparatively 
 simple methods of testing the purity, or otherwise, of the 
 various fatty matters employed by the soap-maker, and to 
 point out the most probable impurities in and adulterations 
 of them, so as to enable the manufacturer to form a true 
 judgment as to the actual vdlue to him of any saponifiable 
 material. The necessary tests of the alkali employed will 
 be explained in Chap. V., which is devoted to the prepara- 
 tion of caustic alkali, while the ordinary analysis of water, 
 and of the various mineral salts employed in soap-manufac- 
 ture, is of the kind which is best obtained by practical 
 instruction in any laboratory, assisted by a text-book of 
 inorganic analysis, of which there are very many published. 
 A general acquaintance with laboratory manipulation will 
 therefore be assumed. 
 
 The ordinary solid fats and fixed oils (with the exception 
 of butter and a few others) may be looked upon as mixed 
 glycerides of oleic, stearic, and palmitic acids, in various pro- 
 portions, the first preponderating in the oils, and the two 
 last (especially stearin) in the fats. For ordinary purposes, 
 there are therefore the following constituents to determine : — 
 (1) Moisture, present in greater or less quantity in every 
 commercial sample of fat ; (2) organic suspended matter, 
 such as impurities from animal and vegetable tissue; 
 (3) mineral matters, such as lime in bone-grease; (4) free 
 fatty acids, arising mainly from the rancidity of fats ; (5) total 
 fatty acids, in any ordinary oil or fat ; (6) oleic, stearic, and 
 palmitic acids, in any ordinary oil or fat ; (7) soluble and in- 
 soluble fatty acids, only necessary in butter, and the few excep- 
 
EAW MATERIALS. 83 
 
 tional fats similarly constituted (coco-nut and palm-nut oils 
 contain some soluble fatty acids) ; (8) glycerin, from which, 
 to calculate the glyceryl in the fat ; (9) possible presence of 
 paraffin-wax and mineral oils. 
 
 It is desirable to point out here the great importance of 
 obtaining for analysis a sample which shall really represent 
 the bulk fairly. In some cases, this is much more difficult 
 than is generally supposed. Ordinary casks or barrels of 
 tallow, from well-known brands, present little or no diffi- 
 culty, provided that the borer is driven well into the middle 
 of the cask. In the case of palm-oil, the circumstances 
 tinder which the casks are gradually filled, and kept in a semi- 
 liquid state, render such a simple proceeding quite valueless, 
 since different parts of the cask are very liable to contain 
 quite different proportions of water and of " dreg," the 
 generic name given to solid impurities in raw fats. Hence 
 in sampling palm-oil, it is necessary to employ a special 
 kind of borer, provided with a slide, which shall take a com- 
 plete section of the contents of the cask from one side to the 
 other, and, if need be, from one end to the other also. These 
 sections, weighing some ounces, must then be thoroughly incor- 
 porated. The same precautions should be applied in the case 
 of greases of various kinds, which are often poured into their 
 casks before they have deposited all their impurities in the 
 tank, so that the process of subsidence is continued in the 
 cask, producing layers of various composition. In the case of 
 liquid oils, the casks should be well roUed about, in order to 
 mix their contents thoroughly, just before sampling them. 
 Eosins, as a rule, are very rarely adulterated, and their mode 
 of manufacture is such, that- a piece taken out of the head of 
 a cask is usually a fair sample. 
 
 (1) Estimation of Moisture in Fats, — 25 grm. of the fat are 
 weighed into a carefully tared porcelain dish, or a small 
 beaker, which is then placed over a low gas-flame, and 
 stirred with a thermometer, taking care that the temperature 
 is maintained considerably above 212° F. (100° C), but not 
 exceeding 275° P. (135° C). This is continued until no 
 
 G 2 
 
84 SOAP. 
 
 more bubbles of vapour escape, indicating tbat all the 
 moisture has been expelled ; the thermometer is then care- 
 fully drawn out, and any fat remaining attached to it is 
 scraped off and returned. If, however, an instrument with a 
 long narrow bulb be used, and it be carefully turned round 
 while it is drawn out, usually no fat will adhere on with- 
 drawing it. The dish plus the fat is then weighed, and the 
 tare being deducted, the remainder is the dry fat in the 
 25 grm. taken, which, multiplied by 4, gives percentage of 
 pure fat, and the difference between that and 100 represents 
 the percentage of moisture. Some fats, especially bone- 
 grease, skin-grease, &c., will froth very much during the first 
 part of this operation, so that the vessel employed should be 
 a capacious one, and the temperature should not be raised too 
 rapidly ; until, however, 278° F. (135° 0.) is reached, it is 
 not safe to assume that all water is expelled. Cooo-nut and 
 palm-nut oils, thus treated, are apt to lose a small fraction of 
 1 per cent, of the oily constituents, but scarcely any other 
 oil does so, unless the sample be maintained long at the 
 highest point. Any mineral acids likely to be present are 
 volatilized at the same time, except sulphuric acid, any 
 notable quantity of which will discolour the oil at the above- 
 named temperature. 
 
 Another method is to keep a weighed sample of the fat 
 in an air-bath at 230° F. (110° C.) until it ceases to lose 
 weight; but the time required for this operation is rather 
 longer than for the method previously given, and hence the 
 result is not obtained so quickly. 
 
 As an illustration of the great range in percentage of 
 moisture, it may be stated that while good tallow should 
 not exceed 0*25 per cent., certain kinds of palm-oil and 
 inferior butter exceed 30 per cent. 
 
 (2) and (3) Estimation of Organic and Mineral matters present 
 as Impwrities in Fats. — This applies to the estimation of fibrous 
 and mineral impurities in oils and fats, of curd and salt in 
 butter, &c., and is thus conducted. The contents of the dish 
 already used for moisture are melted, and the melted fat is 
 
EAW MATEEIALS. 85 
 
 poured off as far as possible withoTit distur'biiig the sediment. 
 Some petroleum-spirit, rectified at a temperature not exceed- 
 ing 188^° F. (87° C), or some carbon bisulphide, is poured 
 into the dish, and the whole is well stirred, and transferred 
 to a previously weighed filter. By means of successive 
 portions of the solvent, the whole of the contents of the dish 
 are washed on to the filter, and all traces of fat are completely 
 washed away from the other matters, which remain on the 
 paper. The filter is then dried at 212° F. (100° C), weighed, 
 and the tare having been deducted, the remainder is organic 
 matter plus mineral matter (or, in a butter, curd plus salt). 
 
 The filter and contents may then be transferred to a pre- 
 viously weighed platinum crucible, and heated for some time 
 to dull redness, till the ash becomes greyish-white. The 
 crucible and ash are weighed, and the weight of the former 
 being deducted, the difference is mineral matter (or, in a butter, 
 salt). The mineral matter thus found is deducted from the 
 former result, and the difference is the organic matter ; each 
 being multiplied by 4 gives the respective percentages. 
 
 There are certain cases, however, in which impurities are 
 actually dissolved in the fats, and hence are not estimated by 
 this method. Bone-grease is a good example of this, holding 
 as it does, lime salts in solution. In such cases it is well to 
 boil the fat upon dilute sulphuric acid, then upon water, a,ni 
 afterwards to proceed as above, weighing the pure fat ulti- 
 mately obtained. Or a weighed quantity of the fat may be 
 ignited, either alone or after being mixed with mercury 
 oxide. In the case of palm-oil, and similar imperfectly 
 purified fats, it will generally be found that the percent- 
 age of " dry dreg " is from one-third to one-half that of 
 the water; hence the mere estimation of the water (a 
 comparatively rapid operation) affords good material for an 
 approximately correct valuation of the sample. 
 
 (4) Estimation of the Free Fatty Acids in Fats. — This is a 
 point to which attention has only recently been directed, but 
 as it is of more importance in relation to the use of fats and 
 oils as lubricants, than for conversion into soaps or candles, 
 
86 SOAP. 
 
 it will only be sbortly dealt with here.* Ahoiit 5 grm. of the 
 fat is taken (the absence of mineral acid being first deter- 
 mined) and dissolved in a suitable flask in 50 c.c. of strong 
 rectified spirit of wine (about 0-82 sp. gr.), by boiling for 
 3 minutes in a water-bath, a vertical condenser being at- 
 tached to the flask, which is shaken round once or twice 
 while in the bath. The reagent employed is alcoholic 
 potash, containing caustic potash equal to 28 grm. of pure 
 po.tassium hydrate, and this is cautiously added from a 
 burette. The indicator is an alcoholic solution of phenol- 
 phthalein, whose crimson colour is instantaneously discharged 
 until neutrality is reached, when the pink colour produced 
 by a slight excess of potash fades with sufficient slowness to 
 leave, in most cases, no doubt as to the point at which to 
 stop. From the amount of potash used, the acidity can 
 readily be calculated. In the case of tallow, since the mean 
 of the equivalent weights of stearic, palmitic, and oleic acids 
 is 274, the potash-acidity percentages multiplied by 5 will 
 probably not be very far from the truth. This factor, how- 
 ever, must vary in other fats and oils, owing to the differences 
 in the equivalent weights of their fatty acids. 
 
 (5) Estimation of the total Fatty Adds in any ordinary Fat or 
 Fixed Oil not containing Glycerides of Soluble-Acids. — This pro- 
 cess, which is also applicable to the estimation of the total 
 insoluble acids in a fat containing glycerides of soluble acids, 
 divides itself into 2 heads, as follows : — 
 
 (a) Preparation of the sample. — If the sample be a per- 
 fectly clear and dry oil, it is at once ready for use ; but if 
 it be at all turbid, or if a solid fat, a portion must be placed 
 in a tube, and kept in the water-oven below 212° F. (100° C), 
 until any moisture and heavy suspended impurities have 
 settled, to the bottom. A well-dried filter-paper is then 
 placed in a funnel over a dry beaker, also in the water-oven, 
 
 * A valuable resum^, and some original investigatibns of the subject, 
 will be found in a paper by W. H. Deering, in the ' Journal of the Society 
 of Chemical Industry,' iii. Also a good paper by L. Archbutt in the 
 Atialyet, vol. ix., may be consulted with advantage. 
 
EAW MATERIALS. 87 
 
 and the nearly clear upper portion of the melted fat is filtered, 
 until a sufficient quantity is thus obtained fit for analysis. 
 
 (;8) Process of analysis. — A perfectly clean and dry 5-oz. 
 flask is accurately tared on the balance, and 5 grm. of the 
 melted fat are carefully weighed into it. (It is not important 
 exactly to a fraction, but as nearly 5 grm. as possible should 
 be taken, and, in any case, the weight must be noted with 
 great care.) To this, are then added about 30 ex. of methy- 
 lated spirit 60 o.p., and a fragment of caustic potash weighing 
 about 2 grm., and the flask is then placed in a basin of boiling 
 water, until the whole of both fat and potash have dissolved, 
 and the addition of a little water produces no permanent tur- 
 bidity, which will he attained within 10 minutes, as a rule. 
 The contents of the flask are then poured into a basin, and 
 the flask is washed out with repeated quantities of boiling 
 distilled water, until the contents of the hasin measure about 
 250 c.c, and no trace of soap remains in the flask. The 
 basin "is then placed over a low gas-flame, and evaporated till 
 it ceases to give off spirituous vapours, a little boiling dis- 
 tilled water being added, if necessary, to prevent too great a 
 loss by evaporation. After simmering in this way for some 
 time, the contents of the basin are made up to 300 or 400 c.c. 
 with distilled water, and while gently boiling, a slight excess 
 of hydrochloric or dilute sulphuric acid is added to them. 
 The whole is well stirred and kept at a point just short of 
 ebullition (to avoid loss by spirting) until a perfectly clear 
 layer of fatty acids separates on the surface. If time be an 
 object, the basin must now be cooled by immersion in cold 
 water, and when the cake of fatty acids is solid, the watery 
 liquid is poured off, and some distilled water added, which in 
 its turn is boiled, cooled, and poured off. If the fatty acids 
 are not sufficiently solid to make a good cake, a known weight 
 (2 or 3 grm.) of stearic acid or bees' -wax may be added with 
 advantage. After washing and draining, the fatty-acid cake 
 may be carefully dried with filter-paper, taking care that the 
 latter absorbs no oil; it is then transferred to a weighed 
 beaker or capsule, dried at a temperature of about 230° F. 
 
•g8 SOAP. 
 
 (110° C), and weighed. If any fat remains adherent to the 
 basin, the latter should be rinsed and dried, the fat can then 
 be dissolved off by petroleum-spirit or some other solvent, 
 and its solution placed in another capsule, dried, and weighed. 
 Prom the total weight of fatty acids thus obtained, their per- 
 centage in the original fat can be readily calculated. 
 
 (6) Estimation of Oleic Acid apart from the Palmitic and Stedrie 
 Acids. — To do this, advantage is taken of the solubility of lead 
 oleate in ether, so enabling its separation from the stearate 
 or palmitate of the same metal. As formerly conducted, this 
 was a tedious and not over accurate process ; but by the 
 apparatus and process devised by Dr. Muter, and here 
 described, the estimation is rendered simple. 
 
 " A small quantity (not more than 1 • 5 grm.) of the purified 
 fat is saponified by alcoholic potash in a flask, washed into a 
 basin with boiling distilled water, and the alcohol is removed 
 by evaporation, all as described before in the estimation, of 
 the total fatty acids. The solution is kept boiling, and 
 treated with acetic acid, drop by drop, until a decided 
 permanent turbidity is produced; dilute solution of caustic 
 potash is then added by drops, with constant stirring, until the 
 liquid just clears again. The clear solution is then precipitated 
 by plumbic acetate in slight excess, and stirred until the. 
 precipitated soap settles thoroughly. The supernatant liquor 
 is poured off, and the soap is at once washed by boiling with 
 a large volume of distilled water, and decanting. By this 
 process, are obtained the -perfectly neutral lead salts, con- 
 taining : — Plumbic oleate (Pb 2C18H33O2), plumbic palmitate 
 (Pb 2C16H31O2), and plumbic stearate (Pb 2C18H35OS). The 
 first is readily soluble in ether ; the two last are quite inso- 
 luble. The soap is scraped from the basin with a platinum 
 spatula, and transferred to a flask of 100 c.c. capacity. The 
 basin is rinsed into the flask with absolute ether, and then 
 the flask is filled up with the same solvent, corked, shaken 
 at intervals for some hours, and finally set to subside. The 
 whole is then filtered through white blotting-paper, and the 
 precipitate is washed with ether, till the washings cease to 
 
EAW MATBEIALS. 
 
 89 
 
 Fig. 18. 
 
 blacken with ammonium hydrosulphide. The filtrate and 
 washings (which should not exceed 200 c.c.') contain the 
 plumbic oleate, while the palmitate and stearate remain on 
 the filter. Having thus got a solution of pure neutral oleate 
 of lead in ether, it is transferred to a long tube of 250 c.c, 
 graduated from the bottom upwards, fur- 
 nished with a well-ground stopper, and 
 having a stopcock placed at 50 ex. from the 
 bottom (Fig. 18). About 20 c.c. of a mix- 
 ture of 1 part hydrochloric acid and 2 parts 
 water are then added; the tube is stoppered, 
 well shaken, and set to subside, when a 
 clear solution of oleic acid remains, the 
 plumbic chloride sinking to the bottom. 
 When sufficiently settled, a fixed portion 
 of the ethereous solution is run off through 
 the stopcock into a tared platinum dish, 
 evaporated at a gentle heat, then dried at 
 212° F. (100° C), and the oleic acid is 
 weighed and calculated to the whole bulk. 
 To make sure, it is well to run off two 
 different quantities, and weigh them, so 
 che9king one by the other.'' 
 
 In the case of drying-oils, it is advisable 
 to evaporate the ether, and to dry the fatty 
 acids, in a stream of hydrogen, rather than 
 in the open air. 
 
 The residue left on the filter is trans- 
 ferred to a basin, heated with dilute acid, 
 and treated as described in the last section, the result being 
 a cake of stearic and palmitic acids. 
 
 7. Analysis of Fats containing both soluble and insoluble Fatty 
 Acids. — To this class belong coco-nut and palm-nut oils, 
 butter, and a few other fats. The process is performed 
 as follows:— 6 grm. of melted and purified butter-fat (as 
 directed under "total fatty acids") are weighed into a 
 5-oz. flask, 50 c.c. of alcoholic potash (containing 60 grm. 
 
 
90 SOAP. 
 
 ordinary caustic potasli per litre), are carefully added from a 
 burette, and the whole is boiled on a water-bath for about 
 15 minutes, or until the addition of a little water produces 
 no turbidity. This solution is washed into a long, narrow, 
 graduated measure with successive quantities of distilled 
 water, till the whole measures 300 c.c, and it is then divided 
 into 2 parts of 150 ex. each. In part A, the insoluble acids 
 are estimated ; in part B, the soluble. 
 
 Part A is treated with solution of barium chloride, until 
 no more precipitate forms ; the precipitate is collected on 
 a filter, and well washed with warm water. It is then 
 transferred to a " Muter's olein tube " (see Fig. 18) having a 
 wide mouth, by washing it in with distilled water, and 
 allowed to .settle. As much as possible of the water is 
 drawn off by inclining the tube forward and running off 
 the clear water at the stopcock; 20 c.c. of diluted hydro- 
 chloric acid (1 acid to 2 water) are added, together with 
 100 c.c. of pure ether ; the stopper is introduced, the tube is 
 well shaken, and then allowed to settle till the ethereous 
 solution separates. The amount of the ethereous solution 
 is noted, and a definite quantity (say J) is dravro off into a 
 tared platinum capsule; the ethdt having been evaporated 
 off, the residual acids are weighed. 
 
 Part B is diluted with another 100 c.c. of water, placed in 
 a flask, and brought under a burette containing sulphuric 
 acid of known strength, a slight excess of which is run in. 
 The flask is then attached to an upright condenser, boiled 
 until the insoluble acids separate in a clear oily layer, and 
 then allowed to cool. The cake is detached, and the fluid 
 is run off through a filter. Another 100 c.c. of boiling water 
 is then added to the cake, and the whole is again boiled 
 under the upright condenser; when cooled, the liquid is 
 passed through the same filter. This operation is repeated, 
 and the united filtrates are brought under a burette con- 
 taining a solution of sodium hydrate, of such strength 
 that 1 c.c. of it corresponds to 1 c.c. of the aoid, and, a 
 few drops of alcoholic solution of phenol-phthalein having 
 
EAW MATEEIALS. 91 
 
 been added, the solution is run in. When a pink colour has 
 been produced, the number of e.c. used is noted, and from 
 this, the quantity of soluble fatty acids present can be readily 
 calculated. 
 
 8. Estimation of Glycerin in Fats. — This is very rarely 
 wanted except foi- scientific purposes, and it is a very diffi- 
 cult operation to perform satisfactorily. A comparatively 
 simple process is that proposed by Dr. Muter, and described 
 in detail in the Analyst for March 1881. 
 
 9. Estimation of Unsaponifiahle Oils in Fats. — A convenient 
 quantity, say 10 or 20 grm. of the fat is thoroughly saponified 
 with an alcoholic solution of caustic soda; a few grm. of 
 sodium bicarbonate are then added, and the whole well 
 stirred; 50 grm. of sand are then incorporated with th6 
 mixture, the evaporation being continued till a dry residue 
 is obtained. This is then macerated with petroleum spirit, 
 and the whole thrown on a percolator and washed with more 
 spirit, until a few drops leave no residue on evaporation. 
 The whole quantity of spirit used is well mixed together, 
 and from an aliquot part of it, the solvent is distilled off, 
 and the residue weighed. This process gives good results 
 with comparatively pure oils, but when much mineral oil 
 is present, portions of the dry soap dissolve with it in the 
 petroleum spirit. 
 
 Another method has been worked out by Mr. A. H. Allen, 
 which is capable of general application.* . A solution is 
 prepared by dissolving 80 grm. of caustic potash, or 60 grm. 
 of caustic soda, in 1 litre of redistilled methylated spirit. 
 To about 5 grm. of the fatty substance to be tested, 25 c.c. of 
 this solution are added in a hemispherical porcelain dish, 
 about 5 in. in diameter ; the whole is stirred, and gently 
 boiled till all the alcohol is expelled, and the residual liquid 
 
 * ' The Practice of Commercial Organic Analysis,' by Alfred H. Allen, 
 1882 edition, vol. ii., pp. 120, 121 and 165-169. This book may be con- 
 sulted with great advantage by those concerned in the Industry of Oils 
 and Fats. See also Chemical News, vol. 44, p. 161, and 'Journal of the 
 Society of Chemical Industry,' vol. ii., pp. 49-58, 101-103 and 435-438. 
 
92 
 
 SOAP. 
 
 froths strongly. If incomplete saponification bq suspected, 
 lOc.c. more alcohol may he added, and the operation repeated. 
 The contents of the basin are brought to a volume of 70-80 c.c. 
 with warm water, and are then transferred to a pear-shaped 
 separator furnished with a tap below and a stopper above, 
 and there thoroughly agitated with about 50 c.c. of ether. 
 After subsidence and separation, the aaueous solution is run 
 off into a beaker, and the ethereous solution into a tared flask. 
 The ether is distilled off; the residue, which may contain 
 the higher alcohols from waxes, sperm-oil, or bottle-nose-oil, 
 rosin-oil, parafSn-wax, or mineral oU, is dried at 212° F. 
 (100° C.) and weighed. 
 
 Table. 
 
 Dissolved by the Ether. 
 
 Hydrocarbon oils. 
 Neutral resins. 
 Unsaponified fat. 
 
 TJnsaponifiable matter, as cholesterin. 
 Myrioyl alcohol (from beeswax). 
 Cetyl alcohol (from spermaceti). 
 Spermyl alcohol (from sperm-oil). 
 Colouring matters, as from palm-oil. 
 
 Aqueous Solution. 
 
 Fatty acids 
 Eesiu acids 
 Carbolic acid 
 Cresylio acids J 
 
 Glycerin. 
 
 Excess of caustic allai.li. 
 
 as potassium salts. 
 
 SPECIFIC GBAVITY OF OILS, &e. 
 
 It may be convenient here to discuss the subject of the 
 specifi-O gravity of oils, since there is often much to be learnt 
 from a careful observation of this, especially when perfectly 
 pure standards of undoubted genuineness can be obtained 
 for the purpose of comparison. The differences, however, are 
 so very slight, and the phenomena in the case of mixtures of 
 oils so remarkable, that great care is necessary both in the 
 observation and in the inferences drawn from it. Moreover, 
 there exists unfortunately great confusion in the mode of 
 stating specific gravities. Thus: — the "specific gravity 
 of butter is 0-912 at 100° F. (37-8° 0.)," may mean that 
 the weight of a given volume of butter at 100° F. divided by 
 the weight of the same volume of water at 60° F. (or even at 
 
EAW MATEKIALS. 
 
 93 
 
 Fig. 19. 
 
 32° r.) gives a quotient of 0*912; or it may mean that 
 the weight of the volume of hutter at 100° F. divided by the 
 weight of the same volume of water also at 100° F. gives a 
 quotient of 0-912. This last is the true way of stating the 
 case, and the term "actual density" was applied to it hy 
 Dr. Muter. There are several modes of making the observa^ 
 tion; perhaps the most accurate is the employment of a 
 " Sprengel's specific gravity tube," which is a y-tube whose 
 legs are drawn out to a capillary bore, and bent at right 
 angles ; it is filled with water by exhausting the air from it, 
 and supported in the neck of a 20-oz. flask (Fig. 19) in the 
 bottom of which water is kept 
 boiling briskly. The mouth of 
 the flask should be closed by a 
 watch-glass or porcelain cruci- 
 ble cover, so as to prevent cool- 
 ing. When no further expan- 
 sion of the contents of the tube 
 is observed to occur, its nose is 
 touched with a piece of filter- 
 paper, and the tube is removed, 
 wiped dry, cooled, and weighed. 
 The whole process is then re- 
 peated at the same temperature 
 with the fats, or fatty acid, 
 and the weights are compared. 
 With proper precautions, this 
 
 gives results which are perfectly accurate to the fourth 
 decimal place, but it is laborious. A somewhat simpler, but 
 not quite so accurata process, is as follows. 
 
 A special sp. gr.-bottle is procured, of a pear shape, and 
 having a thermometer fused through the stopper. The ther- 
 mometer has a long narrow bulb, running right through the 
 centre of the bottle, and its scale, which is from 60° to 120° F. 
 (15^°_49° C.), is entirely above the stopper. This bottle is 
 exactly counterpoised, and is then filled with recently boiled 
 distilled water at 95° F. (35° C.).' The stopper is inserted, 
 
94 SOAP. 
 
 and the whole is at once plunged np to the neck into a 
 12-oz. squat heaker, partially filled with distilled water at 
 103° F. (39^° C), in which is placed a thermometer". As the 
 temperature rises in the bottle, the water leaks out at the 
 stopper, and in a few minutes (if the quantity of water in the 
 beaker be properly regulated), a time arrives at which the 2 
 thermometers equalize themselves at 100° F. (37 • 8° C). The 
 jointbetween the stopper and the bottle is instantly wiped with 
 a small piece of blotting-paper to absorb loose water, and the 
 bottle is lifted out, wiped thoroughly dry, and weighed. This 
 process having been repeated 3 times, the average weight is 
 scratched on the bottle with a diamond, and it is then ready 
 for use. The fat, de;^rived of all impurities, is melted in the 
 water-oven, and cooled to 95° F. (35° C). It is then poured 
 into the bottle till full, the stopper is inserted, and the whole 
 is plunged into the beaker of water at 103° F. (39^° C). The 
 same operations are gone through as just directed for the 
 water, and the weight so obtained is divided by that marked 
 on the bottle. The contrivance of having a rising fat heated 
 by a falling water until the 2 equalize is the perfection of 
 accuracy, and moreover gives an appreciable rest in the variation 
 of temperature, sufficient to enable the excess of fat which has 
 leaked out to be removed exactly at the required point. 
 
 It is also frequently very desirable to determine the " actual 
 density " of the fatty acid, since so many fatty oils occur in 
 commerce in a state of partial rancidity, that the density of 
 the oil itself is not unfreqiiently affected thereby. If, how- 
 ever, the whole be converted into fatty acids, more constant 
 and reliable results are obtained. 
 
 It may be stated broadly that observations on the density 
 or specific gravity of fats or oils made by hydrometers, or by 
 any process other than that of actual weighing as above 
 described, unless they are made with very delicate instru- 
 ments a.nd with extreme care, are comparatively valueless 
 for any except the roughest purpose. 
 
RAW MATERIALS. 95 
 
 VISCOSITY OF OILS. 
 
 The viscosity or fluidity of an oil is a useful physical test 
 at times, and it is determined by ascertaining the rate at 
 which a known volume of it will flow through a given 
 aperture. The operation is -usually conducted in a Mohr's 
 hurette, furnished with a glass stopcock, and surrounded by 
 a glass cylinder in which water can be maintained at any 
 desired temperature. The orifice of the burette should be 
 of such a size that 100 c.c. of German refined rape-oil will 
 flow out of it in 7-9 minutes, at the ordinary atmospheric 
 temperature. Careful maintenance and observation of tern 
 peratures are of great importance in making these tests. 
 
 MELTING COB SOLIBIFTINQ) FOINT OF THE FATTY 
 ACIDS. 
 
 In Dalican's work {Moniteur Scientifique, Paris, 1868), 
 minute instructions are given for testing the value of tallow, 
 oils, &o., for candle-making and soap-boiling. It is stated that 
 this method has been adopted as a standard by the tallow- 
 melters, brokers, and candle-manufacturers of Paris, and it is 
 claimed for it that it gives absolutely concordant and reliable 
 results. The following is a summary of the process. 
 
 In an enamelled basin of at least 1 litre capacity, 50 grm. 
 of the tallow (or oil) is heated till it begins to give off vapour, 
 [about 392° P. (200° C.)]. While this is heating, a mixture 
 is made of 40 c.c. of pure caustic soda solution at 65° Tw. 
 (35^° B.), and 30 c.c. of alcohol 40° Cartier or 95°-96° Gay- 
 Lussac (sp. gr. 0-815). This mixture is added gradually to 
 the hot tallow, the whole being well stirred, until a solid mass 
 is formed ; 1 litre water is added, and the whole is boiled for 
 45 minutes. The soap solution is then decomposed by the 
 addition of 60 c.c. of sulphuric acid at 41° Tw. (24^° B.), and 
 the whole is boiled until the fatty acids are perfectly limpid, 
 and free from clots. 
 
 To perform the "titration," which consists in a very care- 
 ful determination of the melting-point, a glass tube, 10-12 c. 
 
96 
 
 SOAP. 
 
 long and 1^2 c. wide, is filled f full with the fatty acids 
 melted at as low a temperature as possible, and the tube is 
 suspended in a fiask by a perforated cork. The bulb of a 
 delicate thermometer, whose stem is divided into fifths of a 
 degree C, is placed in the centre of the mass of fatty acids, 
 the thermometer being suspended for convenience of mani- 
 pulation and observation. When the fatty acids begin to 
 crystallize, a rotary movement thrice to the right and thrice 
 to the left, is given to the thermometer. During this opera- 
 tion, the thermometer falls slightly and then rises again to a 
 point at which it remains stationary for at least 2 minutes. This 
 is the degree which is accepted as the " titre " of the tallow, 
 and is sometimes called the melting-point, but is really the 
 point of solidification, of the fatty acids. 
 
 From the titration so obtained, the percentages of stearic 
 and oleic acid in the original tallow may be deduced from 
 the following table, constructed synthetically by Dalican, 
 from so-called pure stearic acid, and oleic acid perfectly 
 freed from stearic, palmitic, and other hard fatty acids. 
 In the table, 1 per cent, is allowed for loss by water and 
 impurities, and 4 per cent, for loss by glycerin, contained in 
 the original tallow. 
 
 Degrees C. 
 
 40-0° 
 40-5° 
 41-0° 
 41-5° 
 42-0° 
 42-5° 
 43-0° 
 43 ■5° 
 44-0° 
 44-5° 
 45-0° 
 
 Percentage of 
 
 Stearic acid. Oleic acid. 
 
 35- 
 36' 
 38' 
 38' 
 39' 
 42' 
 43' 
 44' 
 47' 
 49' 
 61 
 
 15 
 10 
 00 
 95 
 90 
 75 
 70 
 65 
 50 
 40 
 30 
 
 59-85 
 58-90 
 57-00 
 56-05 
 54-10 
 52-25 
 61-30 
 50-35 
 47-50 
 45-60 
 43-70 
 
 Degrees C. 
 
 45-5° 
 46-0° 
 .46-5° 
 47-0° 
 47-5° 
 48-0° 
 48-5° 
 49-0° 
 49-5° 
 50-0° 
 
 Percentage of 
 
 Stearic acid. Oleic a£id. 
 
 52 
 53 
 55 
 57 
 58 
 61 
 66 
 71 
 72 
 75 
 
 25 
 ■20 
 10 
 •95 
 ■90 
 ■75 
 ■50 
 ■25 
 ■20 
 ■05 
 
 42-75 
 41-80 
 39-90 
 37-05 
 36-10 
 83-25 
 28-50 
 23-75 
 22-80 
 19-95 
 
 N.B.— The range of this table is between 104° and 122° P. 
 
EAW MATERIALS. 
 
 97 
 
 Fib. 20. 
 
 It is scarcely necessary to add that, if the original fat be 
 accurately weighed, the operations carefully conducted, and 
 the fatty acids [freed from water by exposure to at least 
 248° P. (120° C.)] be then weighed, it will be seen at once 
 whether the original tallow contained any undue impurity 
 or fraudulent admixture. 50 grm. pure taUow should give 
 4:7-&grm. fatty acids. 
 
 For various other commercial tests, Dalican's book may be 
 consulted with advantage. 
 
 There are various other methods of tating " melting " or 
 " fusing " points, but none so accurate as Dalican's. In some 
 cases, capillary tubes are used, which are 
 filled with the fatty acid for about ^-f in. 
 of their length, immersed in water with 
 their ends downwards, and gradually 
 heated in a water-bath : the point at 
 which the semi-fluid fatty acid rises in 
 the tube, is considered to be the melting- 
 point. Several determinations may be 
 made simultaneously by this method. 
 An apparatus suitable for a third method 
 is shown in Fig. 20. The fatty acid is in 
 the inner tube B, surrounded by water, 
 which is gradually heated over a lamp ; 
 temperatures are observed by thermo- 
 meters C, D, — being also used as a 
 stirring-rod. Another mode is to dip a 
 small loop of platinum wire into the 
 melted fatty acids, and, after withdraw- 
 ing it with an adherent bead of fat, to allow the latter to 
 cool, and then immerse it in water which is gradually 
 heated ; a sudden increase in the transparency of the bead 
 denotes the melting-point. Determinations by this method 
 are usually higher than by others. 
 
 Whatever method be chosen, it should be adhered to, 
 since the results by different methods cannot be compared. 
 Moreover, long experience has convinced the writer that 
 
 m. 
 
 
 ^ — 
 
»» SOAP. 
 
 no observations on the so-called melting-point of neutral 
 fats are of any practical value, since such a variety of 
 circumstances are likely to interfere with its accurate 
 determination, 
 
 IDENTIFICATION OF OILS IN MIXTURES. 
 
 The next subject claiming attention is the identification 
 and testing of oils, especially when mixed, a point of the 
 greatest difficulty, and one which eminently requires ex- 
 perience. It does not, like the subject just finished, rest on a 
 definite chemical basis ; and although many processes have 
 been from time to time advocated, none has really stood the 
 test of repetition by other hands. The peculiarity of oils is 
 that one analyst may have methods which may and do give 
 fair results in his own hands, but which, repeated by others 
 without his special experience, become not only inaccurate, 
 but positively misleading. It cannot be too clearly impressed 
 upon the would-be acquirer of information on this subject, 
 that, in the present state of chemical knowledge, there are 
 no decided and definite tests for each kind of oil, as there are 
 for each kind of mineral substance, and that, in arriving at a 
 conclusion as to the composition of any oil or mixture of oils, 
 the analyst can only be guided by what may not inaptly be 
 described as " circumstantial evidence," several tests indica- 
 ting a balance of probabilities in one direction. An essential 
 point in setting about the study of oils is the possession of a 
 set of really genuine standard samples; this is very difficult 
 to procure, as the oil-trade is so permeated by the principle of 
 admixture, that the refiners have too often good reason to shun 
 any attempts to render its detection more easy. 
 
 The first step is to train the nose to distinguish between 
 certain main groups. To do this, take some oil in a small 
 flat porcelain basin, warm it up to about 300° F. (142° C), 
 and observe the smell. Then, as soon as sufficiently cool, rub 
 some into the palm of the hand, and again smell. A little 
 practice will thus permit the easy detection and distinction 
 
EAW MATEBIALS. 99 
 
 between (1) marine animal oil, (2) terrestrial animal oil, 
 (3) vegetable oil, (4) mineral oil. The odours of these four 
 classes are entirely sui generis, and it is safe to pronounce on 
 the main question by this test. The marine oils have all the 
 repulsive fishy odour in various degree, the sperm requiring 
 most practice ; the other animal oils have all the peculiar 
 sourish smell of cooking animal fat, soon learned by experi- 
 ence ; the vegetable oils, on the other hand, have a more or 
 less sweetish odour, and practice will even enable most of 
 them to be named. Mineral oils of the parafSn class are 
 easily recognisable, and so is the peculiar odour of any fatty 
 oil which has been distilled. 
 
 A large number of tests are known as " colour tests," and 
 depend upon the production of certain colours when different 
 reagents act upon pure oils and mixtures thereof, and their 
 general behaviour under these conditions. They are, how- 
 ever, very liable to be interfered with by the presence of free 
 fatty acids in the oil. The usual mode as first brought out by 
 Chateau in 1861, is to allow 5 drops of the reagent to act 
 upon 10 drops of the oil in a white capsule, and to observe 
 the results at the end of short intervals. The reagents usually 
 employed are : — Sulphuric acid, phosphoric acid, nitrous or 
 nitric acid, zinc chloride, barium polysulphide, stannic (tin) 
 chloride, and mercuric nitrate, with or without sulphuric 
 acid.* With the exception of the first they are of very 
 limited utility. 
 
 A more refined colour-test consists in observing the ab- 
 sorption-bands of the fixed oUs by means of the micro- 
 spectroscope. No oils of animal origin give definite bands, 
 while in many vegetable oils the absorptive bands due to 
 chlorophyl and other impurities, are well marked, especially 
 those near the Praunhofer line B. Hence rape, olive, or 
 linseed oil may readily be detected in sperm, cod, or lard oil. 
 
 » A Ml description of these tests, from the pen of Dr. Muter, will be 
 found at pp. 1467-1476 of ' Spons' Bncyclopsedia of Mamifaetures ' ; also 
 in vol, ii. of Allen's ' Commercial Organic Analysis.' But Mr. Allen has 
 more recently pointed out the fallacious nature of certain of them. 
 
 H 2 
 
100 SOAP. 
 
 Some vegetable oils, however, e. g. castor-oil, have no definite 
 hands of this character. To this may he added a reference to 
 the amount of information which maybe derived from examin- 
 i'lgj ^J polarized and by ordinary light, under a microscope, the 
 manner of crystallization of thin layers of fatty acid mixtures 
 allowed to cool between two pieces of glass pressed together ; 
 some very remarkable results of this method were shown by 
 Price's Candle Co. at the Paris Exhibition of 1878. 
 
 " Maumene's test for oils by observing the rise of tempera- 
 ture produced on mixing 50 grm. of the oil with 10 c.c. of 
 sulphuric acid is a useful test dependent on the chemical 
 constitution of the oils examined, and, when carefully con- 
 ducted, it gives remarkably constant indications. The 
 following are essential conditions of success ; — (1) Always 
 to use an acid of exactly the same sp. gr., and to preserve it 
 most jealously from the air. (2) To bring the oil and acid to 
 exactly the same temperature before commencing an experi- 
 ment. (3) To mix the oil and acid thoroughly by means of a 
 thermometer, stirring the whole time, and not reading off the 
 temperature till the mercury begins to fall. (4) To work 
 with the same apparatus, and to prevent loss of heat by en- 
 closing the beaker in a non-conducting substance. In the 
 case of the vegetable oils, the rise of temperature increases 
 very regularly with the drying tendencies of the oil — olive- 
 oil developing about the least heat, and linseed-oil the 
 most.'' * 
 
 A reagent frequently employed in the examination of olive- 
 oil is a saturated solution of mercurous nitrate, which, when 
 agitated with the oil, solidifies it in more or less time, and 
 to a greater or less extent, according to its purity .t Various 
 modifications of this, known as the elaidin test, have been 
 from time to time proposed, but none of them is very satis- 
 
 * A. H. Allen, loc. cit., p. 56. According to this author, also, even 
 with the greatest care, resulta are obtained by Maumene's method which 
 defy explanation. 
 
 t The action of this salt is in all piobahility due to the nitrous acid 
 which it persistently holds in solution. 
 
RAW MATEEIALS. 101 
 
 factory. They all depend on the property of olein and oleic 
 acid of yielding isomeric bodies of comparatively high melting- 
 point under the action of nitrous acid. The process has even 
 been proposed for operation on a manufacturing scale, but 
 the compounds thus formed are very unstable, and exhibit 
 a decided tendency when saponified to revert to their original 
 soft condition. 
 
 As an example of the application of the melting-point test, 
 the familiar case of mixtures of olive-oil and cotton-seed-oil 
 may be taken. The fatty acids of refined cotton-seed-oil melt 
 at 97° F. (36° C), while those of pure olive-oil are fusible 
 at about 30° P. lower, varying between 60° and 70° F. 
 (15^°-21° C), according to whether the oil comes from the 
 first or last portions expressed. The inference from this 
 is obvious. 
 
 In applying this test, it is of the utmost importance to 
 ensure complete saponification of the oil, and it is very 
 desirable to precipitate the soap from its solution in 
 water by the addition of sodium chloride, and to dissolve 
 the soap so precipitated in a fresh portion of water 
 before decomposing it with mineral acid. Since there are 
 so many ways of determining melting-points, which give 
 different results, it is undesirable to quote actual figures 
 here, or to do more than point out the method, and the im- 
 portance of each operator keeping to one mode of working, 
 and one system of recording his observations. Dalican's 
 method, described above, is the one usually adopted for 
 determining melting- and solidifying-points ; and its chief 
 disadvantage is that it involves the preparation of a con- 
 siderable amount of the fatty acids. 
 
 A test for the presence of coco-nut- or palm-kernel- oils, 
 in presence of any other vegetable or animal fatty oils, 
 depends upon the quantity of salt required to separate or 
 precipitate their soaps from solution in a given quantity of 
 water. It may be thus applied : — To 10 grm. of the pure 
 fatty acids is added aqueous solution of caustic soda equal to 
 1 -25 grm. soda (100 per cent,), in a beaker of 100-150 c,c. 
 
102 
 
 SOAP. 
 
 capacity, previously tared. The whole is tlien boiled, and 
 water is added until the contents of the beaker weigh 50 grm. 
 at 212° F. (100° C). At this point, a saturated solution of 
 sodium chloride is run into the beaker from a burette, and 
 the whole is stirred and boiled over a gas-flame. It will be 
 found that while only about 8-10 c.c. of the solution are 
 required with ordinary oils, coco-nut-oil will require more 
 than 50 ex., and mixtures of the two will take proportionate 
 amounts to separate the soap. By keeping the solution just 
 boiling, constantly stirring, and adding the sodium chloride 
 gradually, the exact moment of precipitation of the soap 
 may easily be observed. 
 
 A somewhat refined method of differentiating fatty bodies 
 is due to Koetstorfer, and is founded upon the determination 
 of their "saturation-equivalent,'' or the exact quantity of 
 alkali necessary to saponify them. About 1 • 5 to 2 • 5 grm. 
 of the fat is treated with 25 c.c. of the ^ normal alcoholic 
 potash described on p. 86 ; when saponification has taken 
 place, 1 c.c. of an alcoholic solution of phenol-phthalein is 
 added, and the liquid titrated with J normal hydrochloric 
 acid. A blank experiment is then made by titrating 25 c.c. of 
 the alcoholic potash alone, and the difierence in the volumes of 
 acid used gives the volume of potash solution neutralized by 
 the fat, each 1 c.c. corresponding to ■ 02805 grm. of potassium 
 hydrate, whence the saturation-equivalent is easily calculated. 
 The following are a few examples : — 
 
 Grm. of 
 
 Potassium hydrate 
 per 1000 of Fat. 
 
 SatUTation- 
 equivalent. 
 
 Tallow 
 
 Lard 
 
 Cooo-nut and palm-nut oils 
 
 Butter-fat 
 
 Olive-oil 
 
 Eape-oil 
 
 196-8 
 195-6 
 270-275 
 233 4-221- 
 191-8 
 175-0 
 
 285-1 
 
 286-8 
 
 205 
 
 247-1 
 
 298-2 
 
 320-6 
 
BAW MATEEIALS. 303 
 
 For the detection and estimation of rosin in admixture 
 with fats and fatty oils, the determination of the specifLo 
 gravity of the fatty acids will be found a very valuable guide. 
 The greater the proportion of rosin, the higher is the sp. gr. 
 Since, however, some of these fatty-acid mixtures are solid at 
 100° F. (38° C), it is desirable to adopt a higher temperature, 
 say 212° F. (100° C), as a standard at which to perform the 
 operation. As in every other case, unknown samples pre- 
 sented for examination must be compared with samples of 
 known composition. Further methods of estimating rosin 
 in the fatty acids derived from soaps, will be found in 
 Chap. VIII., which is devoted to the valuation and analysis 
 of soap. 
 
 Another process, applicable to the same problem, as well 
 as to similar ones, consists in making an " ultimate organic 
 analyeis " of the mixture, and determining by direct combus- 
 tion the proportions of carbon and hydrogen in the sample, 
 and of oxygen by " difference." Such an operation, however, 
 can only be conducted by a skilled chemist, and cannot be 
 described here. 
 
 A comparatively new, but apparently very accurate method 
 of examining oils and fats is founded on the differences in 
 their power of absorbing bromine. Details will be found in 
 the ' Journal of the Society of Chemical Industry,' vol. ii., 
 pp. 435-438. The test may be applied in one of two ways, 
 according to whether it is desirable that water should be 
 present, or not. In the dry method, as worked out by 
 Messrs. Mills and Snodgrass, carbon bisulphide is the com- 
 mon solvent of the bromine and the substance to be treated, 
 and the process is carried out as follows : — 
 
 " The substance having been first dried by heat, or by 
 filtration through a quantity of dry paper scrap (which is 
 usually quite sufficient), is dissolved in the bisulphide so as 
 to make a solution of 10 per cent, or less strength. A 
 definite volume of this solution is then placed in a narrow- 
 mouthed stoppered bottle of 100 c.c. capacity, and diluted 
 
104 SOAP. 
 
 with more bisulphide to ahout 50 ex. A deci-normal solu- 
 tion of bromine in the bisulphide is then run in gradually 
 and in successive portions, with agitation, until the colour 
 of the free bromine remains permanent for ^ hour. During 
 this operation direct sunlight must be carefully avoided. 
 At the end of that time, to 50 ex. of bisulphide, in an exactly 
 similar bottle, standard bromine is added until the tint in 
 both bottles is the same. The number of c.c. used in the 
 blank experiment is then deducted from the number in the 
 absorption experiment, and the remainder gives the requisite 
 datum for calculating the percentage of bromine added. 
 The probable error of a single determination of a percentage 
 absorption by this process is, on the average, about 1 • 36 ; 
 that of the mean of 3 experiments, • 79." 
 
 Modifications of, and additions to, this method are frequently 
 being proposed by the original authors of the process, details 
 of which usually appear in the ' Journal of the Society of 
 Chemical Industry.' As an example, reference may be made 
 to the number for February, 1885. 
 
 Another generally applicable method for the examination 
 of fatty substances has recently been proposed by Hubl,* 
 who employs an alcoholic solution of mixed iodine and 
 mercuric chloride : 25 grm. of iodine are dissolved in J litre 
 of alcohol 95 per cent., free from fusel oil, and 30 grm. of 
 mercuric chloride in another J litre of the same. The two 
 solutions are then mixed, after filtration if necessary, and 
 used after 12 hours' standing ; it must also be standardised 
 immediately before or after use. About 0-2-0 "4 grm. 
 of oils, and • 8-1 • grm. of solid fats, is weighed ofi, and 
 dissolved in 10 c.e. of chloroform ; 20 c.e. iodine solution is 
 added, and successive additions of 5 or 10 c.e. are made, until 
 after 2 hours, the solution has a dark-brown tint. The next 
 10-15 e.e. of a 10 per cent, aqueous solution of potassium 
 iodide are added, and 150 e.c. of water. The free iodine is 
 - then titrated with solution of sodium thiosulphate containing 
 
 * Dingl. Polyt. Journal, 253, 281, 1884, Jour. Soo. Ohem. Ind. iii. 
 
EAW MATEEIALS. 105 
 
 24 grm. per litre. The amount of iodine atsorbed is calcu- 
 lated into units per cent, of the fat, and may be conveniently- 
 termed the Iodine degree. This number appears to be 
 tolerably constant for each oil, or class of oils, and is highest 
 with the vegetable drying oils, as will be seen by this short 
 list taken from Hiibl's table : — Linseed-oil, 158 ; hempseed- 
 oil, 143; cottonseed-oil, 106; olive-oil, 82-3; lard, 59-0; 
 palm-oil, 51 "5; tallow, 40*0; coconnt-oil, 8 '9. 
 
106 SOAP. 
 
 CHAPTER V. 
 
 CAUSTIC ALKALI,— AND other Mineral Salts. 
 
 The main subject of this cliapter is the preparation of the 
 caustic lye (whether of soda or potash) used in soap-making, 
 starting in the case of soda from the commercial product 
 known as " salt-cake," i. e. sodium sulphate. The various 
 sources of potash, and their conversion into caustic potash, 
 will be described. The manufacture of those curious salts 
 which may almost be termed mineral soaps, sodium and 
 potassium silicates, will also be briefly dealt with, and a 
 very short notice will be given of some of the alkaline salts 
 which, for various purposes, are incorporated with soap. 
 
 It was stated in Ohap. I. that " hard " soaps contained 
 soda as a base, and " soft " soaps contained potash. As the 
 production of hard soaps far exceeds that of soft, it will be 
 convenient to describe first the processes necessary to 
 produce caiistic soda lye. These may be classed under 
 3 heads, according to the starting-point of the process, and 
 they may be thus arranged in order of simplicity : — 
 
 A. By the simple solution of solid caustic soda in water. 
 
 B. By causticizing a solution of soda-ash with quick-lime. 
 
 C. By causticizing the crude soda liquor obtained' from the 
 
 lixiviation of " black-ash," which is produced during 
 the conversion of salt-cake into soda-ash. 
 
 From the manufacturer's point of view, the cost of these 
 processes is in the inverse order of their simplicity, owing to 
 the relative market value of the caustic sOda, soda-ash, and 
 salt-cake respectively. Hence, almost all large soap-makers 
 in the United Kingdom adopt the last process, which is 
 very slowly finding its way into America, where the second 
 
CAUSTIC ALKALI. 107 
 
 process lias been in vogue for many years, even in the very 
 largest factories. Tlie first method is chiefly confined to 
 small soap-houses, to makers of high-priced toilet-soaps 
 (where expense is a matter of less moment), and to those 
 consumers, whether manufacturers or private individuals, 
 who prefer to make their own soap. 
 
 Nearly the whole of our soda is now obtained from common 
 salt (sodium chloride), and until a very few years ago it, was 
 practically all obtained by the Leblanc process. This con- 
 sists of 3 stages ; — (1) The conversion of salt into salt-bake 
 (i. e. of sodium chloride into sodium sulphate), by heating 
 the former with sulphuric acid ; (2) the manufacture of 
 "black-ash," by which sodium sulphate is transformed 
 into a crude sodium carbonate by fusion with coal and 
 limestone ; (3) the preparation of soda-ash and caustic 
 soda in their numerous forms, from black-ash. Within the 
 last 3 or 4 years, however, the efforts of M. Solvay in 
 Belgium, and of Mr. Mond and others in England, have 
 resulted in carrying out to an industrial success the labo- 
 ratory reaction long known, that when carbon dioxide is 
 passed into a solution of common salt and ammonia, sodium 
 bicarboQate and ammonium chloride are formed : — 
 
 NH3 + CO2 + NaOl -I- HjO = NH«C1 + HNaCO,. 
 
 Or, in shorter form, ammonium bicarbonate and sodium 
 chloride in solution produce sodium bicarbonate and ammo- 
 nium chloride. The former is decomposed by heat to yield 
 neutral carbonate, the latter is, or may be, distilled with 
 lime or magnesia, by which the ammonia is recovered, and 
 used over again. Soda made in this way is known as 
 "ammonia soda," and the process has been developed to 
 such an extent as seriously to threaten the continued exist- 
 ence of the Leblanc method. This is not the place, however, 
 to discuss the relative positions of the two industries ; those 
 interested in the matter will find an excellent summary of 
 it in the Presidential Address of Mr. "Walter Weldon, F.E.S., 
 to the London Section of the Society of Chemical Industry 
 
108 SOAP. 
 
 (and published in its journal) in 1883. The local condi- 
 tions required for the ammonia-soda process are so peculiar, 
 and the practical difficulties of the process itself so great, 
 that it is not at all likely to be adopted by Soap-boilers 
 who make their own soda. The " ammonia soda," as it 
 is called in commerce, is now being extensively and in- 
 creasingly used by soap-makers, and especially by those 
 who, from local difficulties in disposing of their tank waste 
 (p. 133), cannot make their own soda. 
 
 It is quite otherwise, however, with the two last stages of 
 the Lebla,no process, which are well within the reach of all 
 but very small soap-boilers, and hence a careful description 
 will now be given of these. The first stage, viz. the pro- 
 duction of sodium sulphate, is one which cannot be con- 
 ducted well with a small plant, and it also involves, almost 
 necessarily, the simultaneous carrying on of several other 
 processes, such as the manufacture of bleaching-powder ; 
 hence no account will be given of this, and those seeking 
 information upon it are referred to treatises on alkali manu- 
 facture in general. 
 
 1.— MANUFACTURE OF BLACK ASH. 
 
 The second operation of the Leblanc process consists in 
 calcining salt-cake, i. e. sodium sulphate, with chalk or 
 limestone and small coal, producing the impure sodium 
 carbonate known as " black ash," or " ball soda." 
 
 The raw materials necessary are : — Salt-cake, limestone 
 or chalk, and mixing coal, and the plant required is a 
 reverberatory furnace. Good sodium sulphate should come 
 out of the furnace red-hot, and present while cooling a pale 
 canary colour (with no shade of green upon it), which 
 disappears when the salt-cake is quite cold. The lumps 
 when broken should show no centres of undecomposed salt. 
 The presence of reddish lumps, while proving indeed, that 
 the sulphate has been well fired, indicates also the presence 
 of a considerable amount of free sodium chloride. The salt- 
 
CAUSTIC ALKALI. 
 
 109 
 
 cake is then, teclinically, " weak." The following is atout 
 the composition of an ayerage English salt-cake : — 
 
 Sodium sulphate 
 Calcium „ 
 Magnesium „ 
 Iron and alumina 
 Sodium chloride 
 
 96-00 
 0-90 
 0-25 
 0-25 
 1-20 
 
 Free sulphuric acid , 
 Insoluble matter 
 
 0-80 
 0-25 
 
 99-65 
 
 A careful manufacturer, however, -will keep the amounts 
 of hoth sodium chloride and free acid helow those set down. 
 The hest hand-made salt-cake should test 97 per cent, of 
 sodium sulphate, and not more than • 5 per cent, of sodium 
 chloride and the same amount of free sulphuric acid. 
 
 Two varieties of calcium carhonate are employed, chalk and 
 limestone. The former is the material chiefly used in the 
 Tyne district, for the hand-hall furnaces ; the latter in 
 Lancashire. The hest chalk comes from the neighbourhood 
 of London, Northfleet, Greenhithe, &c., and costs ahout 
 2«. 6d. per ton delivered to the works as block-chalk. 
 " Smalls " cost about Is. &d. per ton. The low cost results 
 from the custom for small coasting vessels to take it in as 
 ballast upon their return journey. Usually containing some 
 12 to 15 per cent, of moisture, a portion of the chalk is dried 
 in kilns and mixed with the fresh damp material, in quantity 
 just enough to make the whole run well in the mill. It is 
 then crushed between fluted rollers, or edge stones, and is 
 ready for the furnace. If used in lumps, or wet, the sulphate 
 in the furnace is fluxed and burned before the chalk is acted 
 upon, and the "ball" spoiled. Moreover, it is necessary, 
 when lumpy chalk has to be used, to put in a considerable 
 excess, which in the lixiviating tanks gives rise to caustic 
 soda. Good limestone, Buxton, Irish, or Welsh, as used in 
 Lancashire and other districts, has about the following 
 percentage composition : — 
 
 Organic matter 
 
 trace 
 
 Calcium carbonate .. 
 
 .. 98-370 
 
 Silica 
 
 .. 0-398 
 
 Magnesium „ 
 
 .. 0-756 
 
 Alumina 
 
 .. 0-1.S5 
 
 Manganese „ 
 
 .. 0-026 
 
 Ferrous carbonate . . 
 
 .. 0-252 
 
 Calcium phosphate .. 
 
 trace 
 
110 SOAP. 
 
 The selection of a good "mixing" coal, as it' is called, is 
 an important matter, and the quality must be kept as uni- 
 form as possible. When ignited, it should leave as small a 
 quantity of ash as possible, and must be free from slaty 
 and siliceous matter. A bituminous gas coal mixes well. 
 The ash should not exceed 5 per cent., nor the sulphur 
 • 75 per cent. 
 
 These 3 materials, in the proportion of 3 cwt. of sulphate 
 to 3J-3f cwt. of chalk and about 1^ cwt. of small coal, are 
 introduced into the ball furnace by means of a hopper, or 
 thrown by hand upon the charging bed. The mixture 
 varies with the judgment of the individual manufacturer, 
 or with the state and quality of the materials; but the 
 above proportions represent the usual charge. The furnace 
 is reverberatory ; elevation, section, and plan are given in 
 Figs. 21, 22, and 23. The fire-place is at the end, and is 
 about 4 ft. by 6 ft. The 2 bars that will be noticed below 
 the grates afford leverage to the poker which is used to 
 break up the scars or " clinkers." "When these scars are 
 removed and fall into the " cave " or fire-hole, they must be 
 cooled with water to prevent damage to the iron. It is 
 usual to place a water-tap in the fire-hole for the purpose. 
 Coal is introduced through the fire-hole at the end of the 
 furnace, which is covered with a hanging door of cast iron 
 lined with " half-thicks." Between the fire and the first bed 
 of the furnace a long narrow slit will be observed. This 
 allows a current of cool air to pass continually under the 
 bridge. One side of it is formed by what is called a " bridge- 
 plate " — a long oast-iron slab of peculiar construction, flanged 
 at each end and bolted into the side plates of the furnace. 
 This keeps both bridge and furnace-bottom in their places, 
 and prevents any fluxed material from escaping from the bed 
 of the furnace. It is usual to give the bridge-plate sides 
 about 2 in.'high, and a lining of thin fire-bricks to strengthen 
 it. The bed of the furnace is divided into 2 parts : the 
 " working bed," that nearest to the fire, is 6 in. or so lower 
 than the " shelf " or charging bed ; the hopper in which the 
 
CAUSTIC ALKALI. 
 
 Ill 
 
 charge of salt-cake, coal, and chalk is contained, is built into 
 the arch over the centre of the " shelf." Each hed is pro- 
 
 
 vided with a -working door, closed by cast-iron covers lined 
 with half-thicks. Concerning the pan placed at the end of 
 
112 
 
 SOAP. 
 
 the furnace more will be said presently. A ball furnace re- 
 quires very careful and substantial building, to stand the heat 
 (about 1200° F.), the wear and tear, and the contraction and 
 
 expansion. The walls are about 
 14= in. thick, the arch 9 in., 
 the sole 9 in., formed of 9-in. 
 fire-bricks, of the best pos- 
 sible quality, set on end and 
 " grouted in " with a thin 
 mixture ^of finely ground fire- 
 clay and water. Below this 
 bed a foundation of, first, con- 
 crete, and then brickwork is 
 laid, with as thin jointings as 
 possible. Bevelled portions of 
 brickwork, as shown in Fig. 
 23, allow the workman to 
 reach every comer of the beds 
 with his paddle and rake. 
 The arch goes in a nearly 
 horizontal line over the first 
 bed and then dips down to- 
 wards the pan, so as to carry 
 the heat well into the material. 
 The connection between fur- 
 nace and pan is formed of a 
 bridge and air-course some- 
 what similar to the fire-bridge 
 and its air-course, a large flat 
 quarl, which projects some 4 
 in. over the edge of the pan, 
 preventing the flames from 
 coming into contact with the 
 iron. The whole erection of furnace and pan is firmly bound 
 up by strong iron binders running over upright bars set into 
 the ground or foundation. The outside of the furnace is 
 usually cased with plates of cast iron, as shown in Fig. 21, 
 
CAUSTIC ALKALI. 113 
 
 but in Lancashire it is customary simply to pass strips of 
 metal behind the binders. The bricts used in building a 
 ball furnace, and especially in the beds, must be '*hard 
 burnt," and as free as possible from silica — to prevent the 
 formation of sodium silicate. The fireclay must be as well 
 ground as possible so that all joints may be kept fine. The 
 charging by hopper is a great improvement over the old 
 custom of throwing the materials down in front of the 
 charging door and shovelling them in by hand. Not only is 
 a considerable saving of labour effected, but less cold air is 
 admitted into the furnace. A fresh charge is always kept 
 in the hopper to lute it, the simple withdrawing of a slide 
 causing the materials to fall down upon the shelf of the 
 furnace. 
 
 It has been said that the wear and tear of a ball furnace is 
 very great. The working bed requires renewal about every 
 3 months, the arch immediately over the fire lasts about the 
 same time, while the whole furnace, except plates and 
 foundation, requires reconstruction about once in every 3 
 years. With inferior workmanship in tbe construction, or 
 inferior materials, the life of a furnace is much shorter than 
 3 years, and the renewals from, time to time of the several 
 portions mentioned, are very frequent indeed. 
 
 The placing of a pan at the end of the hall furnace, as set 
 forth in the drawings, is simply a matter of convenience and 
 economy, to utilize the waste heat of the furnace in concen- 
 trating the black-ash liquors, and it is of more use to the 
 ordinary alkali manufacturer who is going to make soda-ash,. 
 &c., from his black-ash liquors, than to the soap-maker who 
 is going to causticize them at once. The latter may with 
 advantage use the space and waste heat thus available for 
 drying the calcium carbonate mud, which is the result of the 
 operation of caustioizing, in order that it may be used in the 
 furnace again instead of a portion of the limestone. 
 
 The balling operations are as follows : — The required 
 quantities of chalk, salt-cake, and small coal are weighed off 
 and introduced into the furnace — upon the back bed — by 
 
114 SOAP. 
 
 some such, means as has heen dehcrihed. The workmaii 
 ■with his " slice " then spreads the charge over the bed so as 
 to thoroughly expose every portion to the action of the 
 flames, and shuts down the door. After a short time the 
 charge — already called a "ball" — is raked np, half of it 
 transferred to the bed nearest the fire, and the other half 
 again " spread." This splitting of the ball is not a universal 
 method of working, but is upon the whole preferable. 
 Again the doors are closed and the split ball exposed to the 
 fluxing heat for about 10 minutes. The second half is now 
 transferred to the working bed, and the really hard labour of 
 the ball furnaceman begins, hardly ceasing until his ball is 
 drawn. As the materials begin to soften and flux — ^the 
 salt-cake first — every portion must be continually turned 
 over so as to get an even fusion, and prevent any portion 
 being burned. This is done with the paddle, and requires 
 great experience, strength, and judgment on the part of the 
 workman, as his materials are constantly varying, and, 
 technically speaking, will " stand more fire " and need more 
 fining-down at one time than another. As soon as the fused 
 mass begins to get stiffer, and the jets of flame, or " candles " 
 begin to die down, the ball furnaceman takes his, rake-— ' 
 the heavy cast-iron head about 10 in. by 7 in. — and after 
 thoroughly mixing up every portion of the ball, draws it out 
 as rapidly as possible into a wrought-iron barrow, or " bogie," 
 placed under the furnace-door, and just overlapped by the 
 door-plate. All this finishing and drawing must be timed 
 to a nicety, and calls into practice all the skill of the work- 
 man. If the ball be drawn a shade too soon, it is " green," 
 and certain to contain undecomposed sodiuni sulphate ; if left 
 for a moment too long exposed to the heat it is burned, 
 and solidifies into a close hard mass, difficult to break up and 
 lixiviate . A badly judged mixture is at once apparent at the 
 finishing of the ball. If too little coal has been used, the 
 whole mass remains soft; if too little chalk, it becomes 
 thoroughly stiff and is difficult to draw. It takes about 40 
 mitttttes to dry, work, and draw a ball. A fresh charge is 
 introduced upon the shelf a few minutes after transferring 
 
CAUSTIC ALKALI. 
 
 115 
 
 the second half of the previous hall to the working 'hed, and, 
 after drawing, this part of the furnace is left empty for 10 
 minutes or so, to get up a thorough heat again, almost a 
 white heat heing required to flux rapidly. After the ball 
 has been raked out into the bogie, it is left for a short time 
 to cool and solidify, the " candles " or " pipes " (jets of burning 
 carbonic oxide) rapidly dying out, and the mass assuming 
 a creamy brown appearance; it is then wheeled away and 
 tipped up in convenient contiguity to the lixiviating tanks. 
 
 The amount of work got out of a ball furnace varies with 
 all different circumstances and mixtures, but as a rule, a 
 workman can draw 9 balls in an 8 hours' shift, weU worked 
 and fired, and weighing about 4£ cwt. each. 
 
 The exact nature of the changes wrought in the ball 
 furnace is still but imperfectly understood. For a full 
 description of all the chemical theories which have been 
 from time to time advanced, the reader is referred to the 
 many papers that have been published upon the subject. 
 The simplest -view is, that first the sodium sulphate is 
 reduced to sulphide by the action of the coal, and that then a 
 mutual decomposition takes place between this substance and 
 the calcium carbonate, — sodium carbonate, carbon dioxide, 
 and a mixture of calcium sulphide and oxide being pro- 
 duced. The analysis of black ash is not only 'very intricate 
 on aci ount of the number of constituents, but is also exceed- 
 ingly uncertain, from the variety of the materials used and 
 the circumstances attending sampling and testing operations. 
 The following, however, is given in the article Alkali in 
 ' Spons' Encyclopaedia ' as representing the composition of a 
 good and well-worked ball : — 
 
 Sodium sulphate . . . . 1 • 00 
 
 „ chloride .. .. 1'50 
 
 „ carbonate .. .. 39 '00 
 
 „ silicate .. .. trace 
 
 „ aluminate .. .. trace 
 
 „ cyanides .. .. 0°50 
 
 Calcium carbonate . . . . 4 00 
 
 „ oxysulphide .. 85 '00 
 
 Lime 0-35 
 
 Magnesia 0-50 
 
 Iron, water, and alumina .. 6-00 
 
 Silica 1-70 
 
 Sand 2-00 
 
 Carbon 4-00 
 
 Other lime compounds .. 3 '00 
 
 98 '70 
 
 l2 
 
116 SOAP. 
 
 2.—LIXiriATI0N OF TEH BLACK ASS. 
 
 The next process is to extract the sodium compounds from 
 the black ash by treating the balls with warm water. It 
 will be noticed by referring to the analysis given that about 
 one half of a ball is soluble, and the remainder insoluble — 
 the latter consisting of various impurities, but chiefly a mix- , 
 ture of different compounds of sulphur, calcium and oxygen. 
 For the purpose of lixiviation, the balls are broken into 
 pieces, and thrown into the series of tanks, shown in. Figs. 
 24, 25, and 26. Water at about 100°-110° F. (38°-43° C), and 
 the second liquors, are then run upon them, the soluble 
 compounds aie drawn off to the settlprs, and the insoluble 
 residue is thrown out. During the process of breaking up, 
 the quality of the balls may be judged by an experienced eye 
 almost as correctly as by complete analysis, and the careful 
 attention of the manufacturer should be specially and 
 unremittingly devoted to this point of review. The interior 
 of a ball should present a clear, steel grey appearance, well 
 honeycombed. It should break readily with a sharp ring, 
 preferably splitting right down the centre. The outer crust 
 should not be loose, nor too well defined, and lumps of 
 undecomposed salt-cake should be conspicuous by their 
 absence. A pinkish shade shows a " green " ball, a dull red 
 a burned one. Irregularity of appearance, with vrhite 
 lumps and. dark patches, shows want of work, a general 
 soft " mushy " character, an ill-judged mixture, or too long 
 exposure to the air. The exact amount of harm which a ball 
 receives by lying too long before lixiviation is a matter of 
 doubt. If put into the tanks too hot, the temperature of the 
 water is raised too high, if left upon the ground more than 
 48 hours or so, a certain amount of decomposition, with 
 oxidation of the lime compounds, takes place. As a general 
 rule, 12 hours may be taken as the best time for a ball to lie 
 before being tanked.- 
 
 A description of the older apparatus for lixiviating black 
 ash is only interesting to the alkali antiquarian. The 
 
CA.USTIC ALKALI. 
 
 117 
 
 ingenious method at present adopted was originally the 
 invention of Shanks of St. Helens, and leaves little to be 
 desired. It depends upon the different specific gravities of 
 
 iffilt 
 
 4^ 
 
 
 
 svsgp p 
 
 ^ 
 
 OM? 
 
 ^ 
 
 o lap 
 
 ^ 
 
 the water and liquor. The tanks vary in size with the 
 experience and judgment of different manufacturers. Good 
 dimensions may be tdken to be 10 ft. long by 8 ft. wide and 
 
118 
 
 SOAP. 
 
 7 ft. deep. They are ustially arranged in sets of 4 — 
 4 tanks of tlie size named being sufficient for 3 hand-ball 
 furnaces, or a decomposition of 60 tons of saltrcake per wenk 
 
 — and are formed by placing 
 partitions in one long tank. 
 The sides, ends, and bottom 
 are formed of f-in. iron plates 
 well riveted together with 
 angle-irons at all the comers. 
 The bottom is sometimes flat, 
 and sometimes assumes for 
 each tank the shape shown 
 in the drawings, sloping 
 down to a drainer, or " well," 
 which runs along the centre 
 of the tank. In either case 
 a lining of 4^ bricks, on edge, 
 is given to the bottom, leav- 
 ing a cross drainer, as shown 
 in Fig. 24. Over both longi- 
 tudinal and cross drains are 
 laid loose sheets of iron, well 
 perforated. In each drainer, 
 reaching just below the false 
 bottoms, are fixed 2 " jugs," 
 one of which communicates 
 with the next tank and the 
 other with a spout running 
 along the whole range of 
 pipes, which conveys the 
 strong liquor to the settlers. 
 These jugs consist of metal 
 pipes 3 in. bore in the lower 
 part, widening to 4 in. in 
 the upper part — shaped in fact like a pnmp. By means of 
 a plug and seat arranged just below the outlet pipe, or 
 "nose," communioation with the neighbouring tank or 
 
CAUSTIC ALKALI. 119 
 
 settlers can he made or cut off at will. The outlet pipes of 
 the jugB along the front of the tanks — ^those hy which the 
 strong liquor runs to the settlers — are placed slightly helow 
 the level of the communications between the tanks. By a 
 pipe running hack from the fourth to the first tank the whole 
 operation is made continuous, each one becoming in turn the 
 " strong " tank, the intermediary, and the " we^k," or ex- 
 hausted tank. Water is supplied to the surface of the tanks 
 •by any convenient apparatus, and is heated, before it touches 
 the liquor, or halls, by waste or other steam. Some manufac- 
 turers turn the steam direct into the tank, a method which 
 causes loss through the temperature of the tank at that 
 particular spot being raised too high, so that the sulphides 
 are dissolved. Finally, in the drainer of each tank are fixed 
 a pipe and cock to carry off the waste liquors. 
 
 The plan of working is as follows : — The tanks are filled 
 with lumps of black ash — not too large — to within about 1 ft. 
 of the top, a layer of dry ashes being, placed upon the bottoms. 
 Water heated to about 100° F. (38° C.) is then run on, 
 which, percolating through the mass of black ash, rises up 
 the jugs, and that one which communicates with the settlers 
 being open, finds its way out in the shape of strong soda 
 liquor. At first this liquor will test about 50° Tw. (29° B.), 
 but the strength speedily advances to 55° Tw. (31° B.) or 
 even 60° Tw. (33° B.), and then rapidly falls down to 40° 
 Tw. (24° B.). The plug is then placed in its seat, and the 
 tank left to itself for awhile. After J hour or so the plug is 
 withdrawn, and a second " running " of liquor taken off, now 
 testing up to 48° Tw. (28° B.) or so. Each tank should bear 
 a third tapping, the liquor never being allowed to go to the 
 settlers below 38° Tw. (23° B.). This outlet pipe is then 
 closed, and the communication between the first and second 
 tanks opened. The liquor from the first tank flows over, 
 percolates through the balls with which the tank is fiUed, 
 and is drawn off to the settlers in the manner described. In 
 the meantime a steady flow of water upon the balls in 
 the first tank is kept up. This operation is repeated with 
 
120 SOAP. 
 
 all 4 tanks. By the time the last is reached, a sample of 
 the liquor drawn from the jug of the first tank will be found 
 to test not more than l°-2° Tw. (0-7°-l-4° B.) showing that 
 all the soda is, practically, dissolved out. The water is then 
 turned upon the second tank, the first hein^ shut off. The 
 spent liquors are drawn off through the pipe at the hottom 
 and run away, leaving a mass of insoluble residue — tank 
 waste — about half filling the tank. This is shovelled out, 
 the drainer cleaned, a fresh layer of ashes sprinkled over the 
 bottom, and the tank is ready to receive a supply of broken 
 ball and the liquor to be dissolved by the returned liquors 
 from the fourth tank. Sometimes the weak tank is " run 
 down," as it is called, to 0° Tw. ; but between 2° and 0° the 
 sulphides dissolve more rapidly than the sodium carbonate, 
 and spoil the liquor. Tig. 24 gives a plan of the tanks, 
 showing the bottom drains and false bottoms; Fig. 25, 
 elevation andN sectional elevation through the line A B ; 
 Fig. 26, a section through the line D. The last drawing 
 shows a set of tanks as at work. No. 1 tank is just 
 filled with black ash, and is receiving the liquor running 
 round from No. 4. No. 2 is empty, No. 3 spent. No. 4 about 
 half through its work. 
 
 The working of the tanks is an operation requiring con- 
 siderable care and judgment, much of the success of the 
 after processes depending upon the securing of good liquor. 
 The most important points are, to keep the temperature as 
 low as possible ; to take off the strong liquor speedily, that 
 it may be kept from contamination, and not to allow the 
 strength of the liquor running to the settlers to fall below 
 38° Tw. (23° B.). With regard to the first point, the water 
 should not be run upon the tanks hotter than 90° Y. (32° C.) 
 in summer, and 110° F. (42° C.) in winter. The temperature 
 of the mass in the tanks has always a tendency to rise, owing 
 to the hydration of the lime and other chemical reactions 
 going on. If the liquors show any greater heat than 150° F. 
 (65° C), it is safe to conclude that the water has been run on 
 too hot. Both strong and weak liquors, and tank waste, 
 
CAUSTIC ALKALI. 
 
 121 
 
 should be tested daily — at least once on eacli shift. The 
 waste should present no lumps of undisintegrated ball, 
 and should be of a dirty green colour. It should be tested 
 at any rate for soda, and from time to time should be subjected 
 to complete analysis. The amount of soluble soda should 
 not exceed 0"15 per cent. A fresh sample wiU give about 
 the following composition : — 
 
 
 Per cent. 
 
 Per cent 
 
 Calcium sulphide 
 
 . 37-0 
 
 Sodium carbonate .. .. 0-25 
 
 „ hydrate 
 
 . 9-0 
 
 Iron, alumina, and magnesia 7-0 
 
 „ carbonate . . 
 
 . 16-0 
 
 Carbon 6-0 
 
 „ Bulphate 
 
 . 6-0 
 
 Silica, &c 5-0 
 
 Sodium sulphide 
 
 . 0-5 
 
 
 It is of the greatest importance to keep both the sulphide 
 and the carbonate of sodium as low as possible. A good 
 manufacturer will not allow even as much of these salts 
 as set down in the above analysis, • 25 total soda being the 
 point to be aimed at. 
 
 The liquor that is drawn off to the settlers should be of a 
 yellowish brown colour and perfectly clear. It should be 
 tested 2 or 3 times daily for sodium sulphide, to make sure 
 that the tanks are not being overheated or the liquor allowed 
 to stand too long before being drawn off. The amount 
 shown should never exceed • 75 per cent., though where the 
 weak liquors are pumped back upon the tanks, and used over 
 and over again in place of water — a piece of poor economy — 
 as much sulphide as 2 per cent, will be often registered. As 
 this is simply converted into sulphate in the after processes, 
 it is sheer loss of soda. An average tank liquor, not the best, 
 will show about the following percentage composition : — 
 
 Sodium carbonate .. .. 69-0 
 
 „ hydrate 15'0 
 
 „ sulphide l-O 
 
 „ sulphite 2-0 
 
 „ sulphate 7'0 
 
 „ chloride 3-0 
 
 Sodium cyanide 
 
 .. trace 
 
 „ ferrocyanide .. 
 
 .. trace 
 
 „ silicate .. .. 
 
 .. 0-5 
 
 „ alurainate 
 
 .. 0-5 
 
 Iron and alumina 
 
 .. 0-5 
 
 Insoluble 
 
 .. 0-5 
 
122 SOAP, 
 
 The weak liquor, standing atout 1° Tw. (0-7° B.) is, as 
 has been stated, sometimes used over again in the place of 
 water, but is usually run to waste. It contains very small 
 proportions of sodium carbonate, hydrate, sulphide, hypo^ 
 sulphite, sulphate, chloride, silicate, and aluminate. 
 
 Various methods for utilizing the tank-waste will be men- 
 tioned hereafter. Usually it is removed as soon as thrown out 
 of the tanks, and either carried out to sea or deposited upon 
 waste land. Some use is made of it in building walls and 
 laying foundations, since the calcium sulphate, or gypsum, 
 which is formed from it by the action of the air, causes it to set 
 very hard. If allowed to remain in heaps, as loosely thrown 
 out of the tanks, the mass spedily becomes hot, even red 
 hot. The oxygen of the air, and the moisture present, cause 
 the formation of soluble calcium hydrosulphide, bisulphide, 
 and hyposulphite, &c., and the presence of carbon dioxide 
 causes an evolution of sulphuretted hydrogen, which is most 
 offensive and injurious. Much of this evil can be prevented by 
 spreading the waste over the ground, or building it promptly 
 into whatever shape may be required, keeping out all ashes 
 or substances that would tend to porosity, and beating it 
 down carefully with shovels so as to keep out the air as 
 much as possible. The most abiding mischief is caused by 
 the drainage from all " tank heaps." The sulphide becomes 
 soluble, and is washed out by rain, &c., forming a yellow 
 liquid, which gives off a well-known nauseous odour. The 
 yellow coating that appears upon the surface of a heap of 
 tank-waste after exposure to the air consists mostly of soluble 
 salts which' have exuded and crystallized. 
 
 3.—0AUSTIC1ZIN6 TEE TANK LIQUORS. 
 
 When this is done regularly, as in a soap-factory, it is 
 usual to modify somewhat the ball-mixture given above for 
 the furnace. The proportion of mixing coal is increased, a 
 large excess of limestone or chalk is added, and the lime mud 
 from the oausticizer is usuallj' worked up in the ball furnace. 
 
CAUSTIC ALKALI. 
 
 123 
 
 So the mixture may assume either of the following propor- 
 tions : — 
 
 
 a. 
 
 6. 
 
 Salt-cake 
 
 Limestone 
 
 Lime mud 
 
 Small coal 
 
 cwt. 
 
 2f 
 
 none 
 
 1* 
 
 cwt. 
 
 li 
 
 3 
 
 The admixture of lime mud varies, and with it the amount 
 of limestone or chalk. 
 
 The tank liquors after settling are pumped into the 
 " causticizers." These are extremely various in size 
 Fro. 27. ^^^ shape. Often old 
 
 boileis, cut in half cross- 
 wise, are used. The best 
 apparatus, in which the 
 liquors are both causticized 
 and oxidized, and at the 
 same time thoroughly 
 agitated, is shown in Figs. 
 27 and 28. But little 
 explanation is necessary. 
 
124 SOAP. 
 
 The air oxidizes the sulphides and performs the necessary 
 agitation of the contents of the vessel, and steam helps 
 Iq the agitation and heats the liquors. Steam and air are 
 admitted below a perforated false bottom, the plan of 
 which is given in Pig. 28. Sometimes a previous oxidation 
 by a special blower is resorted to before the liquors are 
 introduced into the causticizer, and mechanical agitation, by 
 an engine fixed to the side of the vessel, is adopted, the latter 
 addition effecting a saving of lime. A sludge valve serves 
 to run off the residue, or " lime mud," and the clear caustic 
 liquors are decanted by any convenieut form of siphon. 
 Special care must be taken by the soap-maker that all the 
 sulphides are oxidized in this operation, else his soap will be 
 very seriously discoloured. 
 
 Before being oaustioized, it is usual to reduce the strength 
 of the liquor to 20°-22° Tw. (13°-14° B.). Occasionally the 
 reduction is carried down to 14° Tw. (9J° B.), but a liquor of 
 20° Tw. (13° B.) causticizes as readily as one at 14° Tw. (9^° 
 B.), and, the extra amount of water simply represents an 
 extra expenditure of fuel afterwards. Steam is blown in 
 until a temperature of 212° F. (100° C.) is attained, and the 
 mass of the liquor begins to boil. A quantity of quick-lime 
 contained in a convenient cage, which keeps back all stones 
 and big lumps, is then lowered into the vessel (or, perhaps 
 more advantageously, the lime is added gradually, the lumps 
 falling on a screen to keep back stones, &c.), and the steam- 
 ing and agitation are continued until a sample of the liquor, 
 after filtration, g;ives no effervescence with dilute hydro- 
 cliloric or sulphurio acid. A simple view of the reaction in 
 the causticizer is the following : — 
 
 NajOOj -I- CaO = NajO + CaOO,. 
 
 Besides this, the sodium sulphide is converted into hypo- 
 sulphite, and the alumina and silica are curried down with 
 the calcium carbonate. About IJ hour is required for the 
 causticizing of a batch of liquors. For the soap-maker, 
 probably the most economical and satisfactory way is so to 
 
CAUSTIC ALKALI. 125 
 
 adjust the operation that the resulting caustic lye -when cold 
 shall he at 18°-20° Tw. (12°-13° B.). Under these conditions, 
 only ahout 3 per cent, of the total soda present is in the 
 state of carhonate. If the lye is weaker, a fraction less soda 
 will he lost as carbonate, hut this advantage is more than 
 counterbalanced by the need for extra suit in the soap-pan. 
 On the other hand, the amount of soda lost as carbonate, 
 which cannot be causticized by any excess of lime, increases 
 rapidly above that point. In fact, under certain conditions, 
 the reaction above quoted may actually be reversed. 
 
 The caustic lye having been thus produced, great rare 
 should be taken that it is stored for ut^e in covered tanks, 
 from which the air is excluded as much as possible, or at any 
 rate where constant change in the air above the lye is 
 prevented. If this be not done, the caustic soda will rapidly 
 be re-converted into carbonate, by the absorption of car- 
 bonic acid from the air ; normal, country air, contains 
 about 3 parts of carbonic acid in 10,000, but the amount in 
 town air may be more than double this. As neutral fats do 
 not' decompose sodium carbonate in the soap-copper,' and 
 rosin does so only very partially, every pound of soda thus 
 carbonated is so much dead loss. For some kinds of soap, 
 caustic lye at a higher density than 20° Tw. (13° B.) is 
 useful ; this may be readily made by concentrating the 
 weaker lye in any convenient vessel. If wrought iron, with 
 riveted joints, be used, the work must be exceptionally 
 good, since the joints are very apt to leak. A ready, but 
 expensive method of increasing the strength of weak lye, is 
 to dissolve solid caustic soda therein. 
 
 After the completion of the operation of causticizing, the 
 contents of the vessel are allowed to settle for ^ hour or so, 
 during which time the insoluble portions rapidly subside. 
 The clear caustic liquor is then drawn off, a fresh lot of 
 diluted tank liquor run in upon the lime mud, and the caus- 
 ticizing operation is repeated. The mud is not removed after 
 every operation, because a certain amount of vmdecomposed 
 lime is always present, and serves to causticize the next 
 
126 SOAP. 
 
 charge to some extent. After a second operation, fresh water 
 is run in upon the mud, and the whole well agitated. 
 The washings are run off to dilute the tank liquors, and the 
 mud run out upon the " filter." This filter is usually a half 
 hoUer, cut longitudinally. The hottom is paved with bricks 
 in somewhat similar fashion to that already described when 
 explaining the construction of the lixiviating vats, a channel 
 being left down the centre, and the bricks only loosely put 
 in. The actual filter is formed by layers of coke to a depth 
 of 9 in. or so, the bottom layer composed of good-sized lumps, 
 the top of small pieces, and a covering of coarse sand or 
 cinders. Crushed limestone, of varying degrees of fineness, 
 may also be used. Over the filter are laid perforated iron 
 plates or grids, upon which the mud is run out. When a 
 batch is spread over the grids, it is allowed some little time 
 to drain, and is then thoroughly washed with water. The 
 drainings and washings are utilized in diluting tank liquor, 
 and the finally hard, close mud is shovelled out of the filter 
 and wheeled away to the ball furnaces, or mixing depot. An 
 ingenious mechanical contrivance is often used to assist the 
 draining and washing of the mud. A 2-in. iron pipe is 
 bolted upon the bottom of the boiler, below the filter, and 
 communicates with a small air-tight tank placed upon a 
 higher level, and connected in its turn with a vacuum pump. 
 Upon the top of this tank is an air-cock, and let into the 
 bottom is a pipe to convey away the collected water and liquor. 
 When a batch of mud is spread over the filter, the vacuum 
 pump is set up, and draws away, first the drainings and then 
 the washings. These collect in the tank, and are run off to 
 their destination. The completely washed mud should not 
 contain above 1 • 5 per cent, of caustic soda. About 40 per 
 cent, of it is calcium carbonate, 4 per cent, calcium hydrate, 
 and 50 per cent, water. 
 
 It is highly desirable that records and tests of the whole 
 of this process should be kept in such a way that the manu- 
 facturer can tell the result of the whole operation of soda- 
 making, not only as regards quality, but logs during the 
 
CAUSTIC ALKALI. 127 
 
 iiitrioaoies of the process. A considerable amount of loss is 
 inevitable. The plant leaks in various directions, however • 
 well it may he cared for and looked after ; a certain amount 
 of soda goes away with the weak tank liquors, in the volati- 
 lization of sodium salts, in the formation of salts — e. g. 
 sulphide and sulphate — which do not reckon as available 
 soda, in incomplete work in the sodium sulphate process, &c. 
 As a rule, the average production of sodium carbonate from 
 sulphate is not above 69 per cent. — perhaps hardly so much. 
 In a carefully conducted alkali works, 70 parts of soda-ash of 
 " natural strength " — i. e. 52 to 53 per cent. — should be 
 obtained from 100 parts of sulphate. Theoretically, 75 parts 
 should be obtained. 
 
 It is not difficult to obtain such records in the case of 
 caustic lye, by testing average samples of each lot of liquor 
 causticized, and keeping a register of its quantity also. 
 
 TESTING TEE LYE, ETC. 
 
 It may be convenient here briefly to indicate the method of 
 testing solutions of caustic soda, or samples of soda-ash, for 
 the " available soda " which they contain ; and for carbonic 
 acid. Full details will be found in the various works on 
 Alkalimetry and Analysis. The principle of the process 
 consists in ascertaining what volume of an acid solution of 
 known strength is required to exactly neutralize a given 
 quantity of the lye or ash. The exact point of neutralization 
 is determined by the use of an " indicator," usually litmus, 
 or, latterly, methyl orange, or sometimes phenol-phthalein, 
 which is colourless in acid liquids and pink in alkaline.* 
 
 The standard solution of sulphuric acid contains 49 grm. of 
 real sulphuric acid per litre, and may be made in the follow- 
 ing way :— 30 c.c. of the pure acid, 168° Tw. (66° B.), is 
 diluted with water in a beaker, and the mixture is left to 
 stand; when perfectly cool, it is washed into a litre flask, 
 and diluted to the containing-mark. The solution is next to 
 
 * ' Jaumal of the. Society of Chemical Industry,' vol i., pp. 16 and 202. 
 
128 
 
 SOAP. 
 
 Fig. 29. 
 
 be tested with, a standard solution of sodium carbonate, 
 containing 53 grm. of tlie pure carbonate to the litre 
 carefully weighed and measured. 10 c.c. of this latter 
 solution is placed in a beaker with a little distilled water 
 and a few drops of the " indicator," and the acid is run in 
 carefully and slowly until the point of saturation is reached. 
 If more than 10 ex. be required, the solution is too weai ; if 
 less, it is too strong, and it must either be strengthened 
 or diluted, as the case may be, until 10 c.c. of each solution 
 exactly neutralize each other. In order to ensure perfect 
 
 accuracy, larger quantities of 
 the 2 substances, say 50 or 
 100 c.c, may be employed, 
 when the difference, if any, 
 will be more readily detected. 
 If it be preferred to use 
 caustic soda instead of car- 
 bonate, about 42 grm. is to be 
 dissolved in water (about 
 800 c.c.) ; the above test is 
 applied, and small quantities 
 of water are added until 
 equal volumes exactly corre- 
 spond. AU' these solutions 
 are kept in tightly-stoppered 
 bottles. 
 
 The. method of procedure 
 is as follows : — The necessary 
 quantity of alkali being 
 weighed or measured, as the 
 case may be, it is diluted with distilled water in a flask, and 
 enough litmus is added to produce a distinct, but not too 
 deep, blue colour. The acid from the burette (Fig. 29) is 
 then run in until the contents of the flask have been changed 
 to a bright red colour. In order to expel the carbonic acid, 
 the flask is boiled until the blue colour reappears ; the acid 
 solution must now be run in, a few drops at a time, with con- 
 
CAUSTIC ALKALI. 
 
 129 
 
 Fig. 30. 
 
 tinned boiling, until, by the addition of a single drop, a 
 distinct pink colour is produced. In order to obtain a very 
 accurate result, it is well to run in an excess of acid, boU the 
 liquid well, and then add, drop by drop, the standard alkaline 
 solution until the liquid suddenly changes from pink to 
 violet blue. The quantity of the alkaline solution required 
 to effect this change is subtracted from the volume of acid 
 originally run in, and the exact volume of standard acid 
 required to neutralize the amount of alkali previously taken 
 for analysis is thus determined at once. 
 From this, the amount of soda can be calcu- 
 lated. The result is slightly too high, as far 
 as the soap-maker is concerned, because the 
 soda present as carbonate, sulphite, hypo- 
 sulphite, silicate, &c., is all reckoned as 
 available alkali. 
 
 Mohr recommends the use of oxalic acid 
 instead of sulphuric or hydrochloric, because 
 it is more readily weighed than a liquid, 
 and because its solution may be kept for 
 a much longer period than these without 
 undergoing change in strength. The weight 
 required is 63 grm. per litre of water. 
 
 The carbonic acid is usually determined 
 directly, by the aid of the little apparatus 
 represented in Fig. 30. The weighed car- 
 bonate is dissolved in warm water in the 
 flask A, or the caustic lye is placed there, 
 and a quantity of acid, more than sufficient 
 to neutralize the alkali, is placed in the 
 short tube, in the interior. A small quantity of potassium 
 bichromate is also added, to oxidize the liberated sulphurous 
 acid, which would otherwise be reckoaed as carbonic acid. 
 The apparatus is then weighed, and the tube d closed 
 by a plug of wax ; the flask is tilted gently, so as to cause 
 the acid to flow into the flask upon the carbonate. Carbonic 
 acid is thus evolved, and the apparatus should be warmed 
 
130 • SOAP. 
 
 until the evolution of gas completely ceases. When this is 
 the case, the ping is removed, air is drawn through, and the 
 whole is again weighed. The hulb-tuhe B is filled with 
 calcium chloride to dry the evolved gas. The loss indicates 
 the quantity of carhonic acid evolved, from which the 
 amount of real carbonate contained in the sample may be 
 calculated at once. The acidity of the solution, at the 
 conclusion of the test, should be determined by adding a 
 drop of litmus solution ; if it be not acid, more acid must 
 be added, and the operation repeated. 
 
 Another, and very usual method, of testing the causticity 
 of lye involves 2 alkalimetrical tests, but no weighing 
 beyond that of the samples to be tested. In one of these, the 
 total alkali present is determined; the second is treated 
 while boiling, with so much barium chloride as will convert 
 the alkaline carbonate into the insoluble barium salt, the 
 barium carbonate is filtered off, and the alkali determined in 
 the filtrate ; the difference between the two gives, of course, 
 the amount of alkali present as carbonate. The results are 
 liable to be a trifle higher than the exact truth. 
 
 Still another method is to make a direct determination by 
 the use of phenaoetoUn as an indicator, which is yellow with 
 caustic alkalies, but brick-red with alkaline carbonates and 
 with magnesia.* Some operators, however, say that this 
 method is difficult to work, except in the case of solutions of 
 particular strength. In connection with this subject, it may 
 be well to state that, commercially, soda-ash is sold by the 
 percentage of sodium carbonate it contains, and at so much 
 " per degree." The equivalent of sodium is usually taken 
 as 24 instead of the correct figure 23, and of the carbonate 
 108 instead of 106. Hence the correction to " English degrees " 
 in the table annexed — the degrees upon which the carbonate 
 is usually reckoned. The DecroiziUes' degrees represent 
 the French standard, and show the number of parts of oil of 
 vitriol neutralized by 100 parts of the sample. The follow- 
 ing alkalimetrical table has been drawn up by Mr. John 
 Pattinson, of Newcastle-upon-Tyne. 
 
 * ' Jorimal of the Society of Chemical Industry,' vol, i., pp. 56, 57. 
 
CAUSTIC ALKALI. 
 
 131 
 
 Percentage 
 
 Sodium 
 
 JUnglish 
 
 deoroizilles' 
 
 Percentage 
 
 Sodium 
 
 English 
 
 Decroizilles' 
 
 of Soda. 
 
 Carbonate. 
 
 Degrees. 
 
 
 of Soda. 
 
 Carbonate. 
 
 Degrees. 
 
 Degrees. 
 
 30-0 
 
 51-29 
 
 30-39 
 
 47-42 
 
 54-0 
 
 92-32 
 
 54-71 
 
 85-35 
 
 30-5 
 
 52-14 
 
 30-90 
 
 48-2) 
 
 54-5 
 
 98-18 
 
 55-22 
 
 86-14 
 
 81-0 
 
 53-00 
 
 81-41 
 
 49-00 
 
 55-0 
 
 94-03 
 
 55-72 
 
 86-93 
 
 31-5 
 
 53-85 
 
 31-91 
 
 49-79 
 
 55-5 
 
 94-89 
 
 56-23 
 
 87-72 
 
 32-0 
 
 64-71 
 
 32-42 
 
 50-58 
 
 56-0 
 
 95-74 
 
 56-74 
 
 88-52 
 
 32-5 
 
 55-56 
 
 32-92 
 
 51-37 
 
 56-5 
 
 96-60 
 
 57-24 
 
 89-31 
 
 33-0 
 
 56-42 
 
 38-43 
 
 52-16 
 
 57-0 
 
 97-45 
 
 57-75 
 
 90-10 
 
 33-5 
 
 57-27 
 
 33-94 
 
 52-95 
 
 57-5 
 
 98-81 
 
 58-26 
 
 90-89 
 
 34-6 
 
 58-13 
 
 34-44 
 
 53-74 
 
 58-0 
 
 99-16 
 
 58-76 
 
 91-68 
 
 34-5 
 
 58-98 
 
 34-95 
 
 54-53 
 
 58-5 
 
 100-02 
 
 59-27 
 
 92-47 
 
 35-0 
 
 59-84 
 
 35-46 
 
 55-32 
 
 59-0 
 
 100-87 
 
 59-77 
 
 93-26 
 
 35'5 
 
 60-69 
 
 35-96 
 
 56-11 
 
 59-5 
 
 101-73 
 
 60-28 
 
 94-05 
 
 36-0 
 
 61-55 
 
 36-47 
 
 56-90 
 
 60-0 
 
 102-58 
 
 60-79 
 
 94-84 
 
 36-5 
 
 62-40 
 
 36-98 
 
 57-69 
 
 60-5 
 
 103-44 
 
 61-80 
 
 95-63 
 
 37-0 
 
 63-26 
 
 37-48 
 
 58-48 
 
 61-0 
 
 104-30 
 
 61-80 
 
 96-42 
 
 37-5 
 
 64-11 
 
 37-99 
 
 59-27 
 
 61-5 
 
 105-15 
 
 62-81 
 
 97-21 
 
 38-0 
 
 64-97 
 
 38-50 
 
 60-06 
 
 62-0 
 
 106-01 
 
 62-82 
 
 98-00 
 
 38-5 
 
 65-82 
 
 39-00 
 
 60-85 
 
 62-5 
 
 106-86 
 
 63-32 
 
 98-79 
 
 39I-0 
 
 66-68 
 
 39-51 
 
 61-64 
 
 63-0 
 
 107-72 
 
 63-83 
 
 99-58 
 
 39-5 
 
 67-53 
 
 40-02 
 
 62-43 
 
 63-5 
 
 108-57 
 
 64-83 
 
 100-37 
 
 40-0 
 
 68-39 
 
 40-52 
 
 63-22 
 
 64-0 
 
 109-43 
 
 64-84 
 
 101-16 
 
 40-5 
 
 69-24 
 
 41-03 
 
 64-01 
 
 64-5 
 
 110-28 
 
 65-35 
 
 101-95 
 
 41-0 
 
 70-10 
 
 41-54 
 
 64-81 
 
 65-0 
 
 111-14 
 
 65-85 
 
 102-74 
 
 41-5 
 
 70-95 
 
 42-04 
 
 65-60 
 
 65-5 
 
 111-99 
 
 66-36 
 
 103-53 
 
 42-0 
 
 71-81 
 
 42-55 
 
 66-39 
 
 66-0 
 
 112-85 
 
 66-87 
 
 104-32 
 
 42-5 
 
 72-66 
 
 43-06 
 
 67-18 
 
 66-5 
 
 113-70 
 
 67-37 
 
 105-11 
 
 43-0 
 
 73-52 
 
 43-57 
 
 67-97 
 
 67-0 
 
 114-56 
 
 67-88 
 
 105-90 
 
 43-5 
 
 74-37 
 
 44-07 
 
 68-76 
 
 67-5 
 
 115-41 
 
 68-89 
 
 106-69 
 
 44-0 
 
 75-23 
 
 44-58 
 
 69-55 
 
 68-0 
 
 116-27 
 
 68-89 
 
 107-48 
 
 44'5 
 
 76-08 
 
 45-08 
 
 70-34 
 
 68-5 
 
 117-12 
 
 69-40 
 
 108-27 
 
 45-0 
 
 76-95 
 
 45-59 
 
 71-13 
 
 69-0 
 
 117-98 
 
 69-91 
 
 109-06 
 
 45-5 
 
 77-80 
 
 46-10 
 
 71-92 
 
 69-5 
 
 118-88 
 
 70-41 
 
 109-85 
 
 46-0 
 
 78-66 
 
 46-60 
 
 72-71 
 
 70-0 
 
 119-69 
 
 70-92 
 
 110-64 
 
 46-5 
 
 79-51 
 
 47-11 
 
 73-50 
 
 70-5 
 
 120-53 
 
 71-43 
 
 111-43 
 
 47-0 
 
 80-37 
 
 47-62 
 
 74-29 
 
 71-0 
 
 121-39 
 
 71-93 
 
 112-23 
 
 47-5 
 
 81-22 
 
 48-12 
 
 75-08 
 
 71-5 
 
 122-24 
 
 72-44 
 
 113-02 
 
 48-0 
 
 82-07 
 
 48-63 
 
 75-87 
 
 72-0 
 
 128-10 
 
 72-95 
 
 113-81 
 
 48-5 
 
 82-93 
 
 49-14 
 
 76-66 
 
 72-5 
 
 123-95 
 
 73-45 
 
 114-60 
 
 49-0 
 
 83-78 
 
 49-64 
 
 77-45 
 
 73-0 
 
 124-81 
 
 73-96 
 
 115-39 
 
 49-5 
 
 84-64 
 
 50-15 
 
 78-24 
 
 73-5 
 
 125-66 
 
 74-47 
 
 116-18 
 
 50-0 
 
 85-48 
 
 50-66 
 
 79-03 
 
 74-0 
 
 126-52 
 
 74-97 
 
 116-97 
 
 50-5 
 
 86-34 
 
 51-16 
 
 79-82 
 
 74-5 
 
 127-37 
 
 75-48 
 
 117-76 
 
 51-0 
 
 87-19 
 
 51-67 
 
 80-61 
 
 75-0 
 
 128-23 
 
 75-99 
 
 118-55 
 
 51-5 
 
 88-05 
 
 52-18 
 
 81-40 
 
 75-5 
 
 129-08 
 
 76-49 
 
 119-34 
 
 52-0 
 
 88-90 
 
 52-68 
 
 82-19 
 
 76-0 
 
 129-94 
 
 77-00 
 
 120-13 
 
 52-5 
 
 89-76 
 
 53-19 
 
 82-98 
 
 76-5 
 
 130-79 
 
 77-51 
 
 120-92 
 
 53-0 
 
 90-61 
 
 53-70 
 
 88-77 
 
 77-0 
 
 131-65 
 
 78-01 
 
 121-71 
 
 53-5 
 
 91-47 
 
 54-20 
 
 84-56 
 
 77-5 
 
 132-50 
 
 78-52 
 
 122-50 
 
 K 2 
 
132 
 
 SOAP. 
 
 In the case of nearly pure solutions of caustic soda, a very- 
 close approximation to their strength (i. e. the percentage of 
 caustic soda) may he ohtained by the observation of their 
 density with a hydrometer, Fig. 31. These instruments are 
 usually made very cheaply of glass, the lower end being 
 weighted with shot or mercury. When floated, they displace 
 their own weight of liquid, and hence the bulk displaced 
 varies with the sp. gr. of the liquid examined at the tempe- 
 rature at which the observation is made, 
 which is indicated on the stem of the in- 
 strument. The following table (Tiinner- 
 mann), gives the amount of soda (NajO) 
 in t olutions of varying densities : — 
 
 Fig. 31. 
 
 Specific 
 
 Per cent, of 
 
 Specific 
 
 Per cent of 
 
 Gravity. 
 
 NaaO. 
 
 Gravity. 
 
 NaaO: 
 
 1-4:285 
 
 30-220 
 
 1-2280 
 
 14-500 
 
 1-4101 
 
 29-011 
 
 1-2058 
 
 13-297 
 
 1 -3923 
 
 27-802 
 
 1-1841 
 
 12-088 
 
 1-3751 
 
 26-594 
 
 1-1630 
 
 10-879 
 
 1-3186 
 
 25-385 
 
 1-1428 
 
 9-670 
 
 1-3426 
 
 24-176 
 
 1-1233 
 
 8-462 
 
 1-3273 
 
 22-967 
 
 1-1042 
 
 7-253 
 
 1-3198 
 
 22-363 
 
 1-0855 
 
 6-044 
 
 1-3125 
 
 21-758 
 
 1-0675 
 
 4-835 
 
 1-2982 
 
 20-550 
 
 1-0500 
 
 3-626 
 
 1-2843 
 
 19-341 
 
 1-0330 
 
 2-418 
 
 1-2708 
 
 18-132 
 
 1-0163 
 
 1-209 
 
 1-2578 
 
 16-923 
 
 1-0040 
 
 0-302 
 
 1-2453 
 
 15-714 
 
 
 
 Two hydrometer scales are in use among soap-makers, 
 those of Twaddell and Beaume. The zero point of each is 
 that to which the instrument sinks in distilled water at 
 60° F. (15^° C). To convert degrees Twaddell into real 
 specific gravity, multiply their number by 5, add the result 
 to 1000, and then divide by 1000. Thus, 15° Tw. = 1-075 
 sp. gr. The remarks in the last chapter upon the true 
 sp. gr. of fats at various temperatures, are applicable here 
 also. 
 
CAUSTIC ALKALI. 
 
 133 
 
 The following taMe gives the means of comparing degrees 
 Twaddell and Beanme with each other, and with actual sp. gr., 
 and also gives the approximate percentages of caustic soda 
 and caustic potash in solutions of that sp. gr. at 60° F. (15^° C), 
 provided they contain no other salts than the caustic alJcalies. It 
 must be remembered that increase pf temperature in a fluid, 
 by increasing its bulk, diminishes its specific gravity. 
 
 Degrees 
 
 Degrees 
 
 Specific 
 
 Per cent, of 
 
 Per cent, of 
 
 Beaume. 
 
 Twaddell. 
 
 Gravity. 
 
 Canstic Soda. 
 
 Caustic Potash. 
 
 3 
 
 5-2 
 
 1-026 
 
 1-81 
 
 2-83 
 
 5 
 
 7-5 
 
 1-037 
 
 2-72 
 
 3-96 
 
 7 
 
 11-8 
 
 1-059 
 
 4-23 
 
 6-21 
 
 10 
 
 14-0 
 
 1-070 
 
 5-44 
 
 7-36 
 
 12 
 
 19-8 
 
 1-094 
 
 6-65 
 
 9-62 
 
 15 
 
 23-6 
 
 1-118 
 
 7-86 
 
 11-82 
 
 17 
 
 26-2 
 
 1-131 
 
 9-07 
 
 13-01 
 
 20 
 
 32-6 
 
 1-163 
 
 10-88 
 
 15-84 
 
 25 
 
 42-4 
 
 1-212 
 
 13-90 
 
 19-80 
 
 30 
 
 53-0 
 
 1-265 
 
 17-52 
 
 23-76 
 
 85 
 
 64-2 ■ 
 
 , 1-321 
 
 22-97 
 
 27-72 
 
 40 
 
 78-0 
 
 1-390 
 
 27-50 
 
 32-40 
 
 It may be noted here that for every 31 parts of pure soda 
 required in any operation, 53 parts of pure dry sodium 
 carbonate, or 143 parts of sbda crystals, are required, and 
 that the corresponding quantities of caustic potash and 
 potassium carbonate necessary to do the same work are 
 respectively 47 and 69 parts by weight. With this basis, 
 a simple proportion sum will show in any given form ths 
 quantity of alkali required for any purpose. 
 
 UTILIZATION OF THE TANK-WASTE. 
 
 In concluding this brief account of the preparation of 
 caustic soda lye from salt-cake, reference must be made to 
 one objection to it, viz. that it involves the production of a 
 very disagreeable bye-product, the waste residue from the 
 lixiviating vats, the disposal of which is often a very difficult 
 matter, lest it should become a source of nuisance to the 
 
134 SOAP. 
 
 neightourlioocl. Hence many processes have been devised 
 to render it innocuous, and to extract from it the large 
 amount of sulphur which it contains. Only five of these 
 processes have been worked industrially with any approach 
 to success, and of these, three, viz. Hoffmann's, Mactear's, and 
 Schaffner & Helhig's (as carried out hy Mr. A. M. Chance, 
 near Birmingham) are of no use to the mere soap-maker, 
 since some of the materials and plant employed are only to 
 be found in a fully equipped alkali works. 
 
 The process of Mond, patented in 1863, is the best known, 
 and is as follows : — In addition to the tanks in ordinary use 
 for lixiviating, IJ times as many more are provided, or 6 
 extra tanks for every set of 4. In these extra tanks the 
 waste is exposed to a strong current of air, forced through a 
 false bottom with which the tanks are provided, for a period 
 of 12-18 hours, depending upon the quality and texture of 
 the material. During this oxidation process the temperature 
 rises to about 220° F. (104° C), and clouds of steam are given 
 off. The surface of the waste becomes covered with bright 
 yellow spots, their appearance being a guide to the workman 
 as to the progress of the operation. Weak liquor from a 
 previous lixiviation is then run upon the waste and allowed 
 to stand for 8 hours or so, until, starting at about 18° Tw. 
 (12° B.), the density falls to 10° Tw. (6t° B.). Water is then 
 run on, and the product collected as weak liquor to be used 
 for the next tank. This process of blowing and washing is 
 repeated 3 times, the quantity of strong liquor obtained being 
 less each time. The resulting liquors contain calcium sul- 
 phide, sulphite, and hyposulphite, together with small pro- 
 portions of similar sodium compounds. They are allowed 
 to settle thoroughly in a series of tanks, and then run into 
 a wooden vessel lined with lead, some 10 ft. in diameter, 
 and 5 ft. deep, treated with weak hydrochloric acid from 
 the condensers, and heated to 135° F. (57° 0.) with steam. 
 Viewed in the simplest possible form, the following reaotion 
 takes place : — 
 
 2CaS + CaSjOj + 6HC1 = 30a01j + 3HjO + iS. 
 
CAUSTIC ALKiLI. 135 
 
 The quantity of hydrooLlorio acid must he carefully 
 gauged — continued till just a faint smell of sulphurous acid 
 ifl apparent — and the contents of the " tuh " must he well 
 agitated continuously. The liquors are next run into tanks 
 where the freed sulphur settles out, and is washed, dried, 
 and melted. Ingenious though this extraction method is, 
 and successful in so far as it deprives the tank-waste of 
 those constituents which make it an absolute nuisance, it 
 must he confessed that it does not repay the expenditure 
 upon plant, and the trouhle of conducting a delicate opera- 
 tion. It is, however, carried on to some considerable extent 
 by manufacturers who, from the situation of their works, are 
 specially compelled to guard against nuisance. Unless care- 
 fully watched, both in the oxidizing and decomposing opera- 
 tions, an appreciable amount of sulphuretted hydrogen is 
 given off. The average amount of sulphur recovered is f of 
 the total amount in the waste. 
 
 While the details of Sohaf&ier's process differ considerably 
 from the above, the substances employed, as well as the ulti- 
 mate product, are the same ; hence, both are equally suitable 
 for the soap-maker, whose choice between them must be 
 guided by local conditions, the price of labour, &c. In 
 Schaffner's process, the waste is piled in peculiarly-con- 
 structed heaps, and undergoes slow atmospheric oxidation, 
 after which it is lixiviated. Hence much more land is 
 necessary than when tanks are used, 
 
 PBEPABATION OF CAUSTIC LYE FROM SODA-ASH. 
 
 This operation is very simple, all that is necessary being 
 to dissolve the soda^ash in water, and to boil it with the 
 requisite quantity of quiok-lime, conducting the operation 
 precisely as described for causticizing black-ash liquors. 
 Every 31 parts of pure soda employed, require 28 parts of 
 pure quick-lime, on the assumption that all the soda present 
 is in the state of carbonate. In practice of course, an allow- 
 ance must be made for " grip," i. e. unbumt limestone, and 
 other impurities. 
 
136 SOAP. 
 
 Solid caustic soda requires more time and heat for its solu- 
 tion in water tlian might he expected, and the solution 
 usually needs some hours' suhsidence, for the deposition of 
 its impurities. It may he well to repeat here the caution 
 against letting any sodium sulphide (a very common im- 
 purity) find its way into the soap-pan. The Hast,; or 
 oxidizing stream of air, should be continued through the lye 
 for some time after all traces of stdphide (readily detected 
 by a solution of any lead salt) have disappeared, since the 
 slightly-oxidized compounds which are thus produced, have 
 a decided tendency to become reduced again to the condition 
 of sulphide. 
 
 CAUSTIC POTASH. 
 
 Upon a manufacturing scale, the following are the principal 
 sources of potash : — Probably about one-half of the total pro- 
 duce is still made from the ashes of 'land and marine plants ; 
 one-fourth from potassium sulphate, produced by the decom- 
 position of the chloride by sulphuric acid, and from various 
 potassium compounds ; the remainder from beet-root molasses, 
 " suint,'' or the wool of sheep impregnated with the sweat 
 exuded from the skin, and from felspar and other silicates. Al- 
 though the last-named source is as yet comparatively untried 
 ground, it should be noted that in reality felspar and the 
 other silicates yield, in the first instance, their potash salts 
 to all the other sources. The ashes obtained by the calcina- 
 tion of plants show great diversities in quantity and composi- 
 tion, due mainly to the soil in which the plants have been 
 grown. The method of lixiviating the ash corresponds 
 almost exactly with the tank operations of the Leblanc 
 soda process, and the resulting liquor is simply evaporated to 
 dryness in open iron pans, producing commercial " pot-ash." 
 American pot-ashes are graded into 3 brands — " firsts," con- 
 taining 54^58 per cent, of potash; "seconds," 48-52 per 
 cent.; and "thirds," 35-40 per cent. If the pot-ash be 
 thoroughly calcined, so as to burn out all the carbonaceous 
 matters, the product is called " pearl-ash " and is nearly white. 
 
CAUSTIC ALKALI. 
 
 137 
 
 The composition of an average sample of good Canadian pearl- 
 ash is given in the following table : — 
 
 Potassium carbonate 
 „ sulphate . 
 „ chloride . 
 Sodium carbonate 
 Soluble silica, Ira. 
 
 74-44 
 
 13-01 
 
 3-14 
 
 2-58 
 
 1-76 
 
 Insoluble silica, &c. 
 Water .. 
 
 0-35 
 ,4-72 
 
 100-00 
 
 American pot-ashes contain, as a rule, more oaustic potash 
 than other qualities. This is owing to the use of lime in the 
 lixiviating tanks ; and, for many purposes, as, for example, 
 soap-making, where the pot-ash has ultimately to be causti- 
 cized, it is a positive advantage, saving lime in the after 
 process. 
 
 The amount of potash obtained from timber is exceedingly 
 small, as compared with the quantity of the latter consumed. 
 Pine-wood contains about 1 • 25 per cent, of ash, of which 
 about 0-12 per cent, is potash; hence, in order to produce 
 1 ton of commercial pot-ashes, containing 65 per cent, of 
 total potash, about 520 tons of tinjber would have to be 
 burned. 
 
 New and better methods of manufacture have to a large 
 extent supplanted the wood process ; but the industry is 
 still a very large one. It is carried on chiefly in America, 
 Canada, Eussia, France, Italy, Poland, Belgium, and Austria ; 
 America alone supplies about one-half of the total amount 
 manufactured. The prices range from 20«. to 24s. per cwt. 
 for pot-ashes, and from 28g. to 32s. for best pearl-ashes. 
 
 Of late years, however, a large proportion of the potash 
 salts which find their way into the English market are 
 derived from the so-called " Stassfurt salts " produced from 
 the alkaline minerals which occur in enormous quantities in 
 the valley of the river Bodej about 25 miles south-west of 
 Magdeburg, in Prussia.* The potash deposits, which for 
 some time were looked upon as an incumbrance, were first 
 
 • A very interesting account of the whole industry, by Mr. C. Napier 
 Hake, is to be found in the ' Journal of the Society of Chemical Industry,' 
 vol. ii., pp. 146-152. 
 
138 SOAP. 
 
 utilized in 1860 ; at present 19 factories in the neighbour- 
 hood produce potassium chloride from the raw mineral 
 camallite, which is a mixture of magnesium and potassium 
 chlorides with kieserite, a magnesian mineral. The new 
 Stassfurt Mining Company is erecting plant sufficient to 
 consume 600 tons of its own raw material daily. 
 
 The manufacture of potassium chloride is hased on the 
 decomposition of the carnallite contained in the raw mate- 
 rial, in a hot saturated solution, potassium chloride crystal- 
 lizing out, and magnesium chloride remaining in solution. 
 The hot solution is brought to 68° Tw. (36^° B.), diluted 
 to 64° Tw. (35° B.), run into settling-tanks, and allowed 
 to crystallize ; these crystals, once refined, are almost pure 
 potassium chloride. 
 
 The next stages of the process are almost identical with 
 those of the Leblanc soda process, the raw material (potas- 
 sium sulphate) being obtained either from potassium chlo- 
 ride and sulphuric acid by the ordinary sulphate process, or 
 by decomposing the former with magnesium sulphate or 
 kieserite. Equal weights of potassium sulphate and finely 
 divided limestone, or chalk, together with varying quantities 
 of small coal, are roasted together in a reverberatory fur- 
 nace, the product being an exceedingly impure potassium 
 carbonate. When the decomposition is complete, the molten 
 mass is raked out, broken up when cool, and lixiviated in 
 tanks. The soluble potassium and sodium salts are thereby 
 dissolved out, evaporated, and calcined in a small reverbera- 
 tory furnace. 
 
 A carbonate of better quality is produced by following 
 more closely the carbonating operation of the soda process. 
 The liquors from the tanks are evaporated, the potassium 
 chloride and sulphate which separate out during the concen- 
 tration being skimmed off, and sawdust is thrown in. The 
 dried salts are then removed to the carbonator and exposed 
 to a heat at first gentle, but finally urged to dull redness. 
 By this process, the sulphur compounds are oxidized into 
 
CAUSTIC ALKALI. 
 
 139 
 
 sulphate and the caustic potash is converted into carhonate. 
 The chief object of the sawdust is to keep the mass of salt 
 open. A carbonate carefully made in this manner should 
 have about the following composition : — 
 
 Potassium carbonate .. 89' 59 
 
 „ sulphate .. .. 3-98 
 
 „ chloride .. .. 2-49 
 
 Sodium carbonate . . . . 2-83 
 
 Soluble silica and alumina ' 19 
 
 Insoluble matter 
 Water 
 
 0-13 
 
 1-27 
 
 99-98 
 
 The manufacture of potassium carbonate from the sulphate 
 by the methods described is a rapidly increasing industry. 
 Something like 16,000 tons per annum are now produced, 
 and, all things considered, it seems likely to supersede the 
 other processes. It is much more amenable to the altered 
 conditions of the labour market ; a pure article is more 
 readily obtained ; and the soil is not impoverished by a too 
 rapid withdrawal of the potash compounds, which must be 
 the case where beet-root and other plants are the material 
 operated upon. 
 
 It is of great importance to free the potassium carbonate 
 as much as possible from soda compounds, as these consider- 
 ably destroy the fine character which the potash salts give 
 to the articles manufactured from them. In the preparation 
 of soft soaps, for example, the potash compound should not 
 contain above 3 per cent, of soda. 
 
 Other large sources of potash salts are, beet-root molasses, 
 which yield about 12,000 tons a year ; and " suint," or the 
 solid residue from the sweat of sheep, which is retained in 
 the wool, — 44 '5 per cent, of this residue is potassium 
 carbonate. 
 
 The mode of preparing caustic potash lye is precisely the 
 same as that described for caustic soda lye, mutatis mutandis ; 
 in caustioizing for example, every 47 parts of potash, or 
 69 parts of pure potassium carbonate, require 28 parts of 
 quick-lime. 
 
140 
 
 SOAP. 
 
 The following table by Tunnermann will be found 
 useful : — 
 
 Specific 
 
 KHO 
 
 KjO 
 
 Specific 
 
 KHO 
 
 K2O 
 
 Gravity. 
 
 per cent. 
 
 per cent. 
 
 Gravity. 
 
 per cent. 
 
 per cent 
 
 1-3300 
 
 33-693 
 
 28-290 
 
 1-1437 
 
 16-846 
 
 14-145 
 
 1-31S1 
 
 32-345 
 
 27-158 
 
 1-1308 
 
 15-498 
 
 13-013 
 
 1-2966 
 
 30-998 
 
 26-027 
 
 1-1182 
 
 14-151 
 
 11-882 
 
 1-2805 
 
 29-650 
 
 24-895 
 
 1-1059 
 
 12-803 
 
 10-750 
 
 1-2648 
 
 28-303 
 
 23-764 
 
 1-0938 
 
 11-456 
 
 9-619 
 
 1-2493 
 
 26-954 
 
 22-632 
 
 1-0819 
 
 10-108 
 
 8-487 
 
 1-2342 
 
 25-606 
 
 21-500 
 
 1-0703 
 
 8-760 
 
 7-355 
 
 1-2268 
 
 24-933 
 
 20-935 
 
 1-0589 
 
 7-412 
 
 6-224 ' 
 
 1-2122 
 
 23-585 
 
 19-803 
 
 1-0478 
 
 5-957 
 
 5-002 
 
 1-1979 
 
 22-237 
 
 IS -671 
 
 1-0369 
 
 4-717 , 
 
 3-961 
 
 1-1839 
 
 20-890 
 
 17-540 
 
 1-0260 
 
 3-369 
 
 2-829 
 
 1-1702 
 
 19-542 
 
 16-408 
 
 1-0153 
 
 2 021 
 
 1-697 
 
 1-1568 
 
 18-195 
 
 15-277 
 
 1-0050 
 
 0-6738 
 
 0-5658 
 
 FOTASSIUM AND SODIUM SILICATES. 
 
 Of the various salts employed for mixing -with soaps, these 
 are probably the most important, and in some aspects they 
 may be regarded as mineral soaps. 
 
 These compounds, known also as soluble glass or water- 
 glass, may be prepared either by the dry or wet methods. 
 The first is usually adopted by Gossage, Orosfield, and 
 others; it depends on the fact that, at high temperatures, 
 silica plays the part of a very strong acid, capable of displac- 
 ing acids much stronger than itself at ordinary temperatures. 
 On the clean hearth of a reverberatory furnace, 9 parts of 
 Boda-ash at 50 per cent, soda are fused with 11 parts clean 
 white sand, or (for the potash salt) 45 parts of sand, 3 of char- 
 coal, and 30 of potassium carbonate. The product, which is 
 a glassy looking substance, may be sold in the dry state, or 
 may be dissolved in boiling water; not unfrequently boiling 
 under pressure is. necessary to effect complete solution. If 
 the solution be too alkaline, it may be boiled with rosin, or 
 a fatty acid, or it may be treated with a mineral acid, either 
 liquid or gaseous. Instead of sodium carbonate, a mixture 
 
CAUSTIC ALKALI. 141 
 
 of " salt-cake " (sodium sulphate) and coal may be fused with, 
 sand, and the mixture decolorized by sodium arseniate (or 
 a mixture of white arsenic, sodium nitrate, and soda-ash), 
 but a much higher temperature is required in this case, 
 and the wear and tear of the furnace is very great. 
 
 For purposes where uniformity of composition is impor- 
 tant, it is far better to employ the wet method, as is used by 
 Eansome for artificial stone, and by Christr. Thomas & Bros., 
 Bristol. In this case, white sand or calcined flint is put into 
 a Papin's digester, with a solution of caustic soda at about 
 18° Tw. (12° B.) Steam is turned into the jacket, and main- 
 tained there at about 25-30 lb. a sq. in. ; occasional samples 
 are drawn off by a try-cook, and when all trace of causticity 
 has disappeared, steam is turned off, and the contents are 
 " blown out " into tanks where a few hours' subsidence 
 deprives the solution of all suspended impurity. If the 
 flints are not thoroughly calcined, the organic matter in 
 them reduces the sodium hyposulphite to sodium sulphide, 
 which produces the usual discolouration in soap. It is then 
 about 40° Tw. (24° B.) and may be concentrated, if desired, 
 as far as 140° Tw. (59^° B.). Any mechanical arrangement 
 that moves the flints about, facilitates their solution. Made 
 in this way, the silica and the soda bear to each other a very 
 simple, but a very constant, ratio, viz. 2 to 1, and hence 
 great uniformity of composition is obtained, which is not 
 always the case when soluble silicates are made in the fur- 
 nace. The compound is usually sold in solution at 140° Tw. 
 (59^° B.), and should scarcely vary from this composition — 
 
 Silica 33 -00 per cent, to 32 -00 
 
 Soda 16-50 „ 16-00 
 
 Other soda salts 2-50 „ 3-00 
 
 Water 48-00 „ 49-00 
 
 100-00 100-00 
 
 Solutions of sodium silicate, containing a larger proportion 
 of silica than 2 to 1, cannot be concentrated so far, but are 
 
142 
 
 SOAP. 
 
 very suitable for many soaps; those containing less silica 
 than 2 to 1 are unsuitable for all soaps, and should be 
 carefully avoided. 
 
 SODIUM ALUMINATE. 
 
 As a detergent for mixing with soap, this substance is 
 perhaps even more powerful than sodium silicate. It is 
 chiefly obtained from cryolite, a mineral found in great 
 abundance in Greenland, and may be readily prepared from 
 it by boiling it with lime ; cryolite, being a double alumi- 
 nium and sodium fluoride, gives up the whole of its fluorine 
 to the lime, leaving a mixture, or compound, of alumina and 
 soda. Like sodium silicate, it is not a definite chemical 
 compound, — as will be seen by the following ' analyses of 
 different samples : — 
 
 Soda .. 
 
 Alumina 
 
 Water 
 
 A. 
 
 43-0 
 
 48-0 
 
 9-0 
 
 lOO-O 
 
 B. 
 
 44-0 
 24-0 
 32-0 
 
 100-0 
 
 The commercial product is an amorphous white substance, 
 readily soluble in water, in which state it may be mixed with 
 soap, like sodium silicate. 
 
 MI80ELLANE0VB SALTS. 
 
 Many other soda and potash salts are at times used to mix 
 with soaps for various purposes. The most general are 
 sodium chloride, sulphate, and carbonate, which latter 
 may be readily crystallized from " salt-cake " and soda-ash 
 respectively, by dissolving them in warm water, allowing 
 the impurities to subside, and running off the clear solution 
 into crystallizing-pans. Borax is occasionally added to 
 soap, and " salts of tartar," the commercial potassium 
 
CAUSTIC ALKALI. 143 
 
 bitartrate. In fact, almost any potassium or sodium salt 
 may he thus employed, if its price, or the peculiar effect 
 which it has upon the soap, render it desirable thus to add 
 it. Only purely alkaline salts, however, can be used in 
 this way ; if a salt of any other base were mixed with soap, 
 mutual decomposition would ensue, resulting in the forma- 
 tion of a soap insoluble in water. The detection of impuri- 
 ties in these alkaline salts comes under the usual methods of 
 instruction in inorganic analysis, and their preparation is 
 hardly likely to be undertaken by the soap-manufacturer ; 
 hence nothing further need be said upon the subject. 
 
144 SOAP. 
 
 CHAPTEE VI. 
 
 MANUFACTUEE OP HOUSEHOLD SOAPS ;— The 
 •Pkocess op Saponification. 
 
 Befoke proceeding to describe the process of saponification 
 on a large scale, where operations involyiag considerable 
 mechanical, physical, and chemical knowledge are conducted 
 with the view of producing the best possible article at the 
 lowest cost, a short space will be devoted to instructions for 
 making small quantities of soap of inferior appearance, which 
 will answer well for homely purposes, for the benefit of those 
 living far from large towns, and who may yet have on their 
 farms or stations many of the ingredients necessary for their 
 production. 
 
 For those who have plenty of fat or oil at command, but 
 no alkali, the small canisters of pure powdered caustic soda 
 and caustic potash, sold by the Greenbank Alkali Co., 
 St. Helen's, will be found very convenient. With these 
 products, soaps can be made without any boiling. For a 
 hard soap, dissolve 10 lb. of this soda in 4 gal. of water, 
 and allow the lye to cool. Take 75 lb. of clean . fat or oil, 
 rendered fluid by heat if necessary, and when it feds just 
 warm to the hand, add the lye to it in an uninterrupted 
 stream, stirring well all the time ; continue the stirring for 
 15 or 20 minutes, and then set aside in a warm place for a 
 day. In this interval, the soda reacts upon the fat, a,nd 
 turns out its glycerin, which remains mixed with the soap. 
 Any impurities in the fat used, such as salt or any other ex- 
 traneous substance, wiU be apt to spoil the operation. For soft 
 soap, use 20 lb. of this caustic potash, dissolved in 3J gal. of 
 water, and mix as above with 8| gal. of cotton-seed, fish, or 
 other (non-mineral) oil. For a harder soap, one or more of the 
 
MANUFACTURE OF HOUSEHOLD SOAPS. 145 
 
 gallons of oil may lie replaced by 10 lb. (or a corresponding 
 multiple thereof) of tallow. 
 
 A very firm soap may be made on a small scale from the 
 oleic acid of candle-factories, known commercially as olein 
 or red-oil, by heating it to about 212° F. (100° C.) and adding 
 thereto ^ its weight of caustic soda lye at 66J° Tw. (36° B.). 
 The combination takes place instantaneously, and it is only 
 necessary to allow the soap to get cold, when it is fit for use. 
 For the preparation of the lye, see Chap. V. It need not 
 be perfectly caustic ; but if any sodium carbonate be present, 
 the lye must be of proportionately higher sp. gr., and the 
 vessels employed must be capacious, in. consequence of the 
 efier'^escence that occurs. 
 
 Hard soaps may also be made on a small scale without 
 boiling, by adding to a mixture of 2 parts tallow and 1 part 
 coco-nut-oil, or of 3 parts tallow and 2 parts coco-nut-oil, 
 ^ its weight of caustic soda lye at 66^° Tw. (36° B.), the 
 whole being at a temperature of 130°-140° F. (55°-60° C); 
 the mixture, after being well stirred, should be set aside for 
 a day or two. Here also the presence of common salt is a 
 serious obstacle to the combination. 
 
 Soaps that require boiling cannot be well prepared in 
 small quantities. Those who wish to make them, however, 
 would do well to study the description of the process on a 
 large scale. In making small quantities of hard soap, it will 
 be well to boil together the fat, and the soda lye previously 
 well causticized by lime, and to calculate from the table on 
 p. 132 how much lye is necessary, taking as a basis that for 
 every 10 lb. of fat, about 1 lb., or rather less, of pure soda 
 (100 per cent.) is required. Combination will not take place 
 unless the solution is quite weak, say 18° Tw. (12° B.), and 
 when it is effected, salt may be added to separate the excess 
 of water. The salt should bei sprinkled in gradually, time 
 being allowed for each portion to dissolve, and when a small 
 sample, taken out on a shovel and allowed to cool, separates 
 into liquor and soap, enough salt has been added ; the boiling 
 should then be stopped, and the whole allowed to repose ; 
 
146 SOAP. 
 
 in an hour's time, the soap may be skimmed off. Soft soap 
 is more easily made hy boiling on a small scale, since the 
 process is the same whatever quantities of materials are 
 employed. The reader is, therefore, refetred to p. 160 for 
 instructions under this head. 
 
 In considering the manufacture of soap in large quantities, 
 the subject may be conveniently and naturally divided under 
 the following heads : — 
 
 I. The apparatus and processes employed in effecting the 
 chemical combination between the fatty matter and alkali, 
 including in this a general description of the mode of boiling 
 (or otherwise preparing) soaps of different types. 
 
 II. The machinery and mechanical and physical con- 
 trivances made use of to convert the chemical compound 
 so produced into a marketable soap. 
 
 III. Ingredients and formulae for the production of special 
 kinds of soaps for particular purposes, including toilet soaps, 
 manufacturers' soaps, &c. 
 
 These two last will be considered in the next chapter, but 
 it -will be convenient to treat, in this chapter, in the order of 
 their complexity, the somewhat extensive range of subjects 
 included under I., commencing with the simplest, and 
 accordingly we find the following natural subdivisions : 
 
 I.a. Soaps produced by the direct union of fatty acids and 
 caustic alkali, or by the decomposition of carbonated alkali 
 by fatty acids. 
 
 1.6. Soaps produced by the action upon a neutral fat, 
 of the precise quantity of alkali necessaiy for saponification 
 without the separation of any waste liquor, the glycerin 
 being retained in the soap. This class includes — a. Soaps 
 made by the " cold process," p. Soaps made under pressure. 
 
 Lc. Soaps produced by the ordinary methods of boiling in 
 open vessels, working with indefinite quantities of alkaline 
 lye, the processes being controlled by the experience of the 
 operator. These are again subdivided into — a. Soft soaps, in 
 which the glycerin is retained, potash being the base ; 
 j8. The so-called "hydrated" soaps, with soda for a base, 
 in which the glycerin is retained, and of which " marine " 
 
MANTJPACTUKE OF HOUSEHOLD SOAPS. 
 
 147 
 
 Ftg. 32. 
 
 soap may be taken as the type ; y. Hard soaps, with soda 
 for a base, in which the glycerin is eliminated, comprising 
 3 kinds — cnrd, mottled, and yellow soaps. 
 
 It may be noted that a very large proportion of aU the 
 soaps manufactured is included in this last and most complex 
 subdivision, since practical 
 experience shows that, all 
 things being considered, 
 they are the most market- 
 able. 
 
 Full directions for the 
 faljjrication of these several 
 kinds will now be given, 
 the paragraphs treating of 
 each being numbered to 
 correspond with the above 
 classification. 
 
 I.a. In soaps made from 
 fatty acids, the soda is 
 generally used in the form 
 of a refined carbonated ash 
 at 52° (that prepared by 
 the Jarrow Co., Newcastle- 
 on-Tyne, is recommended), 
 every 100 lb. being dis- 
 solved in 160 lb. water in 
 a lead-lined vat, and the 
 solution allowed to settle 
 previous to use. The store- 
 tanks of this, and of the 
 fatty acids employed, are 
 connected with small gauge- 
 tanks or measuring-tubes 
 
 (rig. 32), for the purpose of obtaining uniformity in the 
 results by the use of exact quantities in every operation. 
 For the delivery of the soda solutions into the soap-pan, a 
 
 L 2 
 
 Fig. 33. 
 
148 SOAP. 
 
 special feeder (Fig. 33) is provided, closed with a movable 
 plug, by which the flow of liquid may be regulated at 
 discretion; a perforated rose-spout may be advantageously 
 placed under the exit-pipe. 
 
 The soap-pan in which the operation is conducted, shown 
 in Figs. 34, 35, 36, is jacketed, the inlet-pipe being at Z, 
 and the steam is either superheated, or used at a pressure of 
 75-80 lb. Above the pan, is a movable curb 0, with slide at 
 m, necessary to give room for the intumescence caused by 
 the liberated carbonic acid ; a wheel arrangement W enables 
 it to be readily drawn aside on a railway behind the columns 
 N, which support the gearing M. This gearing moves the 
 stirrer E at the rate of 40 rev. a minute ; the latter is made 
 of wrought iron, and is most efficient when the 2 sets of 
 blades move in opposite directions ; when this is not the 
 case, the pan itself should be provided with fix^d traverses 
 armed with vertical cross-teeth. In making soap with this 
 apparatus, 1000 lb. oil are run into the pan with the curb 
 in its place, and heated to 280°-320° F. (138°-160° C.), 
 according to its quality. At this point, 190 lb. of soda ash 
 for a neutral soap, or 210-225 lb. for a strong soap, dissolved 
 in the proper quantity of water, and at 212° F. (100° C), is 
 let into the pan at such a speed that it occupies not less than 
 6 nor more than 12 minutes. The whole is well stirred 
 meanwhile, and swells up enormously ; but 5 minutes after 
 the last portions of alkali have been added, the mass subsides, 
 and, in 15 minutes more, changes from a spongy to a clear, 
 soft, brilliant, homogeneous paste. The curb is then removed, 
 and, in about an hour, 100 lb. of boiling water is let in from 
 the rose-spout of the soda-feeder, and the whole is again well 
 stirred ; if it be desired to mix sodium silicate or anything 
 else with the soap,, it is added at this stage, after which, the 
 soap is transferred to the cooling-frames (Chap. VII.), and a 
 fresh batch is proceeded with. Soap thus made has the follow- 
 ing composition : — Oleic acid, 65 • per cent. ; soda, 6 • 7-7 ■ 50 ; 
 water, 27*50. When rosin is used, it should be added to 
 the oil while the latter is being heated ; or the rosin soap 
 
MANUFACTUEE OF HOUSEHOLD SOAPS. 
 
 149 
 
150 
 
 SOAP. 
 
 may he made in a separate pan, provided with a Morfit's 
 steam-twirl (Fig. 37), in which the tubular hlades of the 
 stirrer are perforated so as to emit steam while the whole is in 
 motion ; 1200 lb. rosin and 2200 lb. caustic lye at 16^° Tw. 
 (11° B.), are boiled together, and the thin jelly so produced 
 is transferred in suitable quantities to other pans. Its per- 
 centage composition is : — EcSsin, 54 ■ 5 ; soda, 7 • 8 ; water, 
 
 Fia 37. 
 
 37 -7. The apparatus described here is also suitable for 
 several other kinds of soap, the steam-twirl, &c., being 
 especially useful for making " hydrated " soaps (p. 161). 
 It is not improbable that such an apparatus as this may 
 be extensively used in the near future, especially if the 
 
MAKUFACTUEE OF HOUSEHOLD SOAPS. 
 
 151 
 
 Prench. process, so largely adopted in America, for de- 
 glycerining neutral fats before they are saponified (vide 
 Chap. XIII.), comes into general favour. 
 
 1.5, a. — The so-called " cold process " consists in mixing 
 given weights of fat, or a mixture of fats, previously melted 
 at as low a temperature as possible [about 109°-111° F. 
 (43°-44° C.)], with caustic soda solution of a given sp. gr., 
 and at about the same temperature, the quantities of each 
 being so adjusted that only just enough soda shall be 
 present to completely saponify the fat. After thorough 
 incorporation, the mixture is covered up, and allowed to 
 stand. In a few hours, the chemical reaction commences, 
 accompanied by considerable evolution of heat, and the soap 
 is formed. After the lapse of 2 or 3 days, it is usually hard 
 enough for use. It is obvious that soaps made in this way 
 retain all the glycerin originally combined with the fatty 
 acids, disseminated through the particles of soap. This, 
 and the comparatively low temperature at which the soap 
 is made, are the chief reasons why this process is much in 
 vogue for the cheaper kinds of toilet soap, since the perfumes 
 employed are not dissipated by heat. It is found, however, 
 that soaps thus prepared are very apt to contain an excess 
 of alkali, and hence they are unavailable where perfectly 
 neutral soaps are required. 
 Another objection is, that, "■ 
 
 as there is no oppor- 
 tunity of removing any 
 extraneous matter, the 
 materials employed must 
 be of the purest, and as 
 
 the soda lye is usually required in a concentrated (and 
 therefore expensive) form, the process is not so advantageous 
 as at first sight appears. It is chiefly applicable to soaps 
 made on a small scale ; when larger quantities are operated 
 on, a mechanical agitator, such as Hawes' boiler, represented 
 in Fig. 38, is necessary. This, for operating on 2^ tons of 
 
152 
 
 SOAP. 
 
 tallow, is a cylinder 6 ft. diam., 12 ft. long, with a central 
 shaft provided with radiating arms, set in rotation by any 
 convenient mechanism. Any saponifiable fat or oil may be 
 Tised, and for every 100 lb. of the pnre fat, 50 lb. of caustic lye 
 at 66^° Tw. (36° B.), should be taken. When this is not 
 very pure, i. e. if it contains much extraneous soda salts, 
 especially sodium chloride, saponification will not take place, 
 unless some proportion (10 per cent, on the fat, at least) of 
 coco-nut-oil be used. The following mixtures will be found 
 useful for this process : — 
 
 
 Tallow. 
 
 Lard. 
 
 Palm-oil. 
 
 Coco-nut- 
 oil. 
 
 Eosin. 
 
 (1) 
 
 100 
 
 
 
 .. 
 
 J , 
 
 (2) 
 
 100 
 
 .. 
 
 
 50 
 
 
 (3) 
 
 
 
 55 
 
 55 
 
 100 
 
 (4) 
 
 50 
 
 30 
 
 20 
 
 
 .. 
 
 (5) 
 
 •• 
 
 100 
 
 •• 
 
 •• 
 
 ■• 
 
 Nos. 1, 2, and 5 make good toilet soaps, which are improved 
 if about ^ of the soda used is replaced by an equivalent 
 quantity of potash. No. 4 with unbleached palm-oil gives 
 a fine yellow soap, liable however to bleach in the light. 
 No. 3 is given on the authority of Cristiani, who recommends 
 the use of 100 lb. lye at 42° Tw. (25° B.) to the 210 lb. 
 mixed fat and rosin. 
 
 The time required increases with the amount of materials 
 operated on at once. The chief points needing attention are, 
 to use pure materials, to avoid excess of alkali, and so to 
 manage the temperature and the stirring as to make a com- 
 plete mechanical mixture of the melted fat and lye which will 
 not separate before the chemical combination, i. e. saponifica- 
 tion, takes place. 
 
 1.6, 13. — This class comprises the soaps which are pro- 
 duced by boiling under pressure. This process has been the 
 subject of numerous patents at various times, all having 
 
MANUF40TUBE OP HOUSEHOLD SOAPS. 
 
 153 
 
 for their object the shortening of the time occupied in the 
 ordinary methods of open boiling (I.e.), and the saving of 
 the salt employed therein. In this case, also, the quantity of 
 alkali employed, whether caugtic or carbonate, is accurately 
 adjusted to the fat to be saponified, and the glycerin is 
 retained in the ultimate product ; mixtures of any saponi- 
 fiable fats and resins may be employed. The kind of appa- 
 ratus used is shown in Fig. 39 ; it consists of a steam-boiler 
 provided with a man-hole and safety-valve, with a feed-pipe 
 
 Pig. 39. 
 
 A and discharge-pipe C, and with a long thermometer B, in 
 a pocket filled with paraffin. The proper quantities of fat 
 and caustic lye are let in through A ; all taps are closed ; a 
 fire is kindled, and maintained until the thermometer rises 
 to about 310° r. (154 "4° C), equivalent to a steam pressure 
 of 63 lb. a sq. in. When it has remained at this point for an 
 hour, the tap at C may be opened, and the contents dis- 
 charged into a cooling-frame D, by the steam pressure in the 
 boiler. For a good j-ellow soap, 7^ cwt. tallow, 3 cwt. palm- 
 
154 SOAP. 
 
 oil, 3 cwt. rosin, and 140-150 gal. caustic soda lye at 34° Tw. 
 (21° B.) are recommended by tlie inventor, Dunn. Another 
 formula is 800 lb. tallow, 200 lb. palm-oil, 400 lb. rosin, 
 175 gal. caustic soda lye at 42° Tw. (25° B.) for 1 hour at 
 252° F. (122-2° C), or 17 lb. steam pressure. It is obvious 
 that this will make a drier soap, since lye at 42° Tw. contains 
 less water than at 34° Tw., and that the quantity of water 
 desired in this product can thus be regulated to a nicety. 
 In 1865, Bennett and Gibbs, of Buffalo, New York, took out 
 a patent for effecting this operation with carbonated alkali, 
 thus avoiding the expense of causticizing. The boiler is 
 similar to that shown in Fig. 39, but is placed horizontaEy, 
 and provided with an agitator similar to that for Hawes' 
 boiler. The process requires a higher temperature and 
 pressure than the previous one, ranging from 350° to 404° F. 
 (176-6°-204-4° C), or 220-280 lb. a sq. in. The outlet- 
 pipe is provided with a safety-valve, and the inventors state 
 that if this be loaded to about 250 lb. a sq. in., and the raw 
 materials be pumped in at one end, the process may be made 
 continuous, finished soap coming from the outlet, produced 
 in less than one hour from the introduction of the raw 
 materials. The formula recommended is, for every 100 lb. of 
 saponifiable fat, 30-33 lb. of soda ash of 48 per cent, dissolved 
 in 100 lb. water. In. the early stages of the process, the 
 liberated carbonic acid is allowed egress by one of the 
 safety-valves, and if any liquid escapes before a temperature 
 of 325° P. (163° 0.) is reached, it should be returned to the 
 cylinder. The following advantages over ordinary processes 
 are claimed : — (1) Eapidity of manufacture, (2) improve- 
 ment in quality, (3) increased yield of soap, (4) economy of 
 labour, (5) saving of fuel, (6) use of cheaper fatty material, 
 (7) saponification of the whole of it, (8) uniform certainty of 
 results, (9) retention of glycerin, and improvement of pro- 
 duct thereby, (10) ability to use carbonated alkali. It is 
 obvious, however, that the risk of explosion is not slight, 
 and the practical difficulty of working the agitator at that 
 temperature and pressure must be considerable. 
 
MANUFACTURE OF HOUSEHOLD SOAPS. 155 
 
 I.c, a. Soft Soaps. — The production of these is the simplest 
 case of the process most usually adopted in the fahrication 
 of soap, viz. toiling in open vessels, technically termed 
 " coppers," with the aid of steam (either wet or superheated) 
 or of fire, or of the two simultaneously. It will be con- 
 venient, therefore, to describe here the construction and 
 fittings of the various kinds of soap-ooppers (or soap-pans), 
 and the different modes in which steam and fire are applied 
 to boil their contents. 
 
 In the days when there was an excise duty upon soap, 
 " coppers " were usually of what is now considered a very 
 small size, and were constructed of cast iron ; they consisted 
 of hemispherical pans, upon which were mounted as many 
 cylindrical rings as were necessary to make the copper of a 
 suitahle depth, usually about twice its diameter ; the rings 
 were joined to each other, and to the hemispherical bottom, 
 with cement joints. There was no limit to their size, except 
 the difficulty of making large castings, and they were usually 
 encased in masonry, and fitted with fire-places and flues in. 
 the manner to be presently described for modem wrought- 
 iron " coppers." In the case of those boiled by fire (the 
 only method until steam-boiling was introduced), the hemi- 
 spherical bottoms were very apt to crack from overheating, 
 and from many other causes, which it is scarcely necessary to 
 detail, as these pans are fast becoming obsolete. 
 
 The removal of the excise duty in England, in 1853, gave 
 an enormous impetus to the soap industry. Manufacturers 
 were no longer deterred from making large batches of soap 
 by the fear that, if they were spoiled, double duty would 
 have to be paid when they were re-made and produced fit for 
 sale; and, as a natural consequence, numerous experiments 
 were tried, both with the raw materials and the apparatus 
 employed. Soap-coppers are now made of colossal size, those 
 capable of turning out 50 tons of finished soap (112,000 lb.) 
 at one operation being by no means uncommon, and some of 
 the large American manufacturers have built even still 
 larger coppers, requiring a factory of 3 stories to contain 
 
156 SOAP. 
 
 them. Although it is desirable that those boiled by fire 
 should be circular in shape, and not too large — say 20 tons 
 capacity — the coppers whose contents are boiled by steam 
 may be of any desired shape, circular, oval, or rectangular, 
 provided tbat the steam-pipes be carried into the corners (if 
 any), and be so arranged as to ensure uniformity of ebulli- 
 tion throughout the whole mass. There is no necessary pro- 
 portion between diameter (or superficial area) and depth j 
 English soap-makers are more accustomed to pans whose 
 diameters are to their depth as 1 to 1, 1 to !• 25, or 1 to 1*5 
 (e. g. a pan 15 ft. diam. and 15 ft. deep will turn out 
 25-30 tons of soap); while their American confreres, less 
 trammelled by -tradition, increase the ratio as far as 1 to 2, 
 1 to 2 • 5, or even 1 to 3. 
 
 Soap-coppers are now almost invariably built of wrought- 
 iron plates, riveted together in the place where the copper is 
 eventually to stand. Figs. 40, 41 show a simple form of 
 copper for fire-boiling, with the fire-place, flues, &c. ; A B D C 
 is the outline of the copper, C D being a circular renewable 
 plate, in the part most exposed to the action of the fire F. 
 At E, are supporting lugs of cast iron ; K L is the floor- 
 level ; H I, a steam-pipe ending in a perforated coil, steam 
 being controlled by the cock at Gr. Eigs. 42, 43 show a 
 copper where steam only is used : A B is the floor line ; 
 C D E, the copper, provided with a " hat " at E to receive 
 impurities that subside, and to enable spent lye to be 
 removed completely by the draw-off at K. Another draw- 
 off is fitted at L ; 2 steam-worms are provided, H, with cock 
 F, whose coil is perforated, admitting " open " or " wet " 
 steam among the copper contents, and I, with cock G, in 
 which high pressure or superheated steam is circulated, for 
 use when it is desired to evaporate water. This last coil is 
 usually omitted in the largest coppers, being only used in 
 making curd and mottled soaps. 
 
 An important adjunct to a soap-copper is a little piece of 
 machinery for preventing the contents from boiling over, as 
 
MANUFAOTUKE OF HOUSEHOLD SOAPS. 
 
 157 
 
 they are apt to do when saponification is taking place, and 
 also in a later stage, even after the steam is turned ofi". It 
 
 Fig. 40. 
 
 Fig. 42. 
 
 ^. ..-. 
 
 
 ./"■ 
 
 N^ 
 
 / /^'"^ ^^* 
 
 ■^ \ 
 
 (--■■// /^'""'^ 
 
 C\ N 
 
 i if~"w' — 
 
 \ w 
 
 1 ^^ 
 
 ft 1 
 
 i // 
 
 ■ --•^''^^ ~ ^ 
 
 // ■' 
 
 \ \v^ — ^ 
 
 
 \ ^-5:s=sS^ 
 
 -^ / 
 
 \ 
 
 y' 
 
 
 
 
 
 
 
 Fig. 41. ■ 
 
 Fig. 43. 
 
158 
 
 SOAP. 
 
 is called a fan, and is represented in Pigs. 44, 45 ; it consists 
 essentially of a rotating paddle, whose blades just touch, 
 the top of the boiling mass. The motion is derived from 
 
 Fig. 44. 
 
 Fig. 45. 
 
 ^n overhead shaft J, on which is keyed a bevel-wheel H, 
 gearing into a similar wheel Q ; this latter slides on a 
 feather on the shaft P, being thrown in or out of gear by a 
 fork E, to which is attached a rod 0, actuated by links B and 
 
MANUFACTURE OF HOUSEHOLD SOAPS. 159 
 
 bell-crank A, in the bottom end of whicb is an eye for 
 attaching a cord which may be drawn to right or left. The 
 lower end of the fan-shaft drives the over-shaft M, on which 
 the fans N are keyed by means of bevel-wheels K L. The 
 top and bottom of the fan-shaft are carried by bushes driven 
 in at each end of a piece of stout 2-in. steam-pipe, and the 
 pipe S is inserted in cast-iron frames Q E. Near the lower 
 end of the pipe, is a shackle P, to which a rope or chain is 
 attached for lowering or raising the fan, according to the 
 level of liquid in the copper. The whole swings on the 
 axis of the shaft J. 
 
 The fabrication of soft soaps will now be described. Soft 
 soap is a more or less impure solution of potash soap mixed 
 with glycerin in caustic lye, and forming at ordinary tem- 
 peratures a transparent smeary jelly, containing at times, 
 and especially in cold weather, white grains, which are 
 impure potassfum or sodium stearates. The most suitable 
 form of copper for making it is shown in Fig. 40. In 
 England, whale-, seal-, and linseed-oils are chiefly used, 
 and occasionally a little tallow to produce the grains, or 
 " figging," just described, an appearance which serves no 
 really useful purpose. On the European continent, hemp- 
 seed-, linseed-, camelina-, and poppy-oils are used, and also 
 rapeseed- and train-oils, especially in summer, since they 
 j produce a harder soap. In America, cotton-seed-oil and oleic 
 acid are often employed. Hempseed-oil gives a greenish 
 tint, much prized by consumers, which may be imitated by 
 the addition of a little indigo precipitated by potash from its 
 solution ia sulphuric acid. 
 
 A very desirable, but not necessary, adjunct to the soap- ■ 
 copper is a set of tanks of iron or wood, whose contents per 
 inch of depth are known, in order that the quantities of oil 
 and lye let into the copper may be regulated. In many 
 large factories, the practice is to keep a strict account of the 
 quantity of fatty matter and rosin used, but to control the 
 amount of lye according to the judgment of the soap-boiler. 
 
160 SOAP. 
 
 Sucli ^gauge- and store-tanks may be in any convenient 
 place, and pipes or open shutes are carried from them to 
 deliver their contents into the copper; suitable plugs and 
 cooks control the flow of the liquid at the pleasure of the 
 operator. 
 
 To make an unsophisticated soft soap, a suitable quantity of 
 oil is run into the copper, not exceeding J its total capacity ; 
 at the same time, potash lye at 13i°-16J° Tw. (9°-ll° B.) 
 not absolutely caustic, but retaining some potabsium car- 
 bonate, is let in, and the steam is turned on, or the fire 
 kindled, or both ; the fan may also be adjusted at the height 
 beyond which the soap is not to boil, and the whole is care- 
 fully watched. If the copper has not boiled until a volume 
 of lye has run in equal to that of the fat, the stream of lye 
 should be stopped, and started again when the ebullition 
 commences. If the oil and lye do not appear to have com- 
 bined, the fire should be checked, the stream of lye stopped, 
 and gentle steam-boiling continued until this is the case. It 
 is very difficult, especially with rape-oil, to get the alkali to 
 combine, but when once the process has begun, it goes on 
 with tolerable rapidity with subsequent additions of lye. 
 From time to time, small samples of the soap are dropped 
 upon a glass plate, and after cooling at a temperature as near 
 46 • 4° F. (8° 0.) as can be obtained, are carefully examined. 
 The soap is good if it is clear and translucent ; a fatty border 
 indicates deficiency of alkali; while if the sample be 
 granular, grey, and lustreless, too much lye has been added, 
 a fault that must be corrected by the addition of more oil, 
 previously mixed with lye at 3° Tw. (2° B.). Should the 
 sample separate on the glass into soap and clear liquor, the 
 quantity of lye is excessive. If the combination be good, 
 and alkali deficient, stronger lye (at first 23°-25° Tw. 
 [15°-16° B.] then 38°-42° Tw. [23°-25° B.]) maybe cautiously 
 added ; a sign of saturation, or rather slight excess of alkali, 
 is the appearance of a striped skin, or lye-veins, on the 
 surface of the sample. When it is judged that enough 
 alkali is present, the steam is turned off, and a certain 
 
MANUPAOTUEE OF HOUSEHOLD SOAPS. 161 
 
 amount of water is evaporated by boiHng the copper with 
 fire, during whicli operation the bubbles get larger, the soap 
 being almost laminated, and they make so much noise in 
 their escape that, in the language of the soap-boiler, " the 
 soap talks." 
 
 When the soap is finished, a small sample must not glide or 
 be slippery on the glass, nor must it draw into threads when 
 worked up between the fingers and thumb; a very small 
 ring should appear in the sample in 12-15 min., indicating 
 the necessary slight excess of potash. The soap is filled into 
 barrels while quite hot, and to promote rapid cooling of the 
 mass, cold soap is often added. 
 
 A somewhat shorter method, saving the evaporation in the 
 later stages, has been introduced of late. For every 100 lb. 
 oil, 200 lb. lye at 32J° Tw. (20° B.) is required ; when liquid 
 fats are used, this quantity is run in at the commencement 
 of the operation ; with solid fats, ^ may be taken, and when 
 thoroughly incorporated, the rest may be added, and the 
 soap boiled as previously described. 
 
 If it be desired to make a soft-soap in which some of the 
 potash is replaced by soda, the proportions of the 2 lyes must 
 be accurately adjusted to each other, and to that of the fat 
 used. The process was first worked out by Grentele, and 
 improved by Cristiani, who recommends for the saponifica- 
 tion of oil by f potash and f soda the following formula : — 
 50001b. oil, 2674 lb. potash lye at 32^° Tw. (20° B.), 740 lb. 
 potash lye at 42° Tw. (25° B.), and 2353 lb. soda lye at 
 32^° Tw. (20° B.). If enough steam be not condensed in 
 the boiling, water may be added to make the whole weigh 
 12,500 lb. 
 
 To produce a grained soft-soap (or " fig "), it is essential to 
 use pure potash lye, and to employ some hard fat, the stearic 
 or palmitic acids of which form potash salts whose crystalliza- 
 tion produces the grains, within somewhat narrow limits of 
 temperature, viz. 48-2° F. and 59° F. (9°-15° C). The 
 following fat mixtures will produce it : — (a) 55 palm-oil, 45 
 oleic acid ; (b) 55 palm-oil, 15 tallow, 30 linseed-oil ; (c) 70 
 
 M 
 
162 
 
 SOAP, 
 
 palm-oilj 30 linseed-oil. An artificial grain is sometimes 
 given by clay starch, &c.* 
 
 Two kinds of genuine soft-soap occur in commerce, whose 
 compositions are respectively: — 
 
 Water 
 Potash 
 Fatty acids 
 
 n. 
 
 per cent. 
 
 per cent. 
 
 50-5 
 
 31-5 
 
 9-5 
 
 11-5 
 
 40-0 
 
 50-0 
 
 The question of admixtures with genuine soft-soap, after its 
 fabrication has been completed, is one that demands the 
 serious attention of both manufacturer and consumer. They 
 may be divided into 2 classes : (1) those intended to increase 
 the detersive power ; and (2) those added solely to cheapen 
 the product. To the latter belong clay, starch, fecula, glue, 
 and a number of other fraudulent admixtures, whose detec- 
 tion will be dealt with tinder the head of soap-analysis. The 
 first class demands a few explanatory words, and contains 
 chiefly 2 substances, rosin, and sodium or potassium silicate ; 
 the manufacture of the latter, and their use in hard soaps, are 
 described in Chap. VII. For soft-soap intended for house- 
 hold and laundry purposes, rosin may be substituted for part 
 of the saponifiable material (to the extent of 10-15 per cent, 
 upon the total oil used) without injury, and, in some cases, 
 with actual benefit ; in the same class of soaps, the addition 
 of potassium or sodium silicate (or carbonate) certainly in- 
 creases the detersive power, especially where hard water is em- 
 ployed. Most of the soft-soaps made, however, are used by 
 woollen manufacturers, for wool- washing, fulling, scouring and 
 sizing, and there is no doubt that the best soap for these pur- 
 poses is a genuine neutral potaBh~oil-soap. Experience has shown 
 that the addition of rosin has an undesirable effect upon the 
 
 * A valuable paper on the preparation of soft soaps, will be found in 
 Dingler's Polyteohn. Journal, 1882, Bd. 244, Heft. 1, and an abstract of 
 it in Jour. Soc. Chem. Ind., i. 236, 
 
MANUFACTUEE OF HOUSEHOLD SOAPS. 163 
 
 fibre, and that tie presence of soda in any form is absolutely 
 injurious to it. Wool in its natural state is lubricated by 
 " suint," which contains nearly 50 per cent, potassium car- 
 bonate, and scarcely a trace of soda ; it is evident therefore 
 that in discarding soda, and using potash, the manufacturer 
 foUows the teachings of nature. On the other hand, as has 
 been pointed out by Mr. W. J. Menzies, a well-made neutral 
 soda soap is preferable for wool-washing, &c., to an impure 
 potash soap, containing, as it so ofteu does, excess of caustic 
 potash and carbonate. This is the real ground on which, 
 some years ago, Leroux deprecated the use of potash soaps 
 for such purposes, since, at that time, pure caustic potash, 
 such as is now manufactured in large quantities, was 
 unknown. The use of potassium silicate is injurious, since 
 it attacks the fibre of the wool, and in some cases, by its 
 decomposition, even deposits silica therein, greatly to the 
 detriment of the ultimate fabric. So much injury has been 
 done by the use of unsuitable soaps, that many woollen 
 manufacturers have been driven to make their own, thereby, 
 as they think, ensuring purity. This, however, is also a 
 hazardous proceeding, and it would be reaUy more to their 
 interest to state their exact wants, and to pay a proper 
 and fair price for a soap carefully made with all the appli- 
 ances and knowledge of a large soap-factory, than to run the 
 risk of using a product in which, from want of practice or 
 knowledge, a serious oversight had occurred. The excessive 
 desire for cheapness on the part of purchasers has done more 
 than anything else to depreciate the quality of soft-soaps (and 
 of others). Further general remarks on this subject, and 
 upon the desirability of purchasers buying soaps whose compo- 
 sition is guaranteed by analysis, will be found in Chap. VIII. 
 
 I.c, p. — The method of making " hydrated " soaps is very 
 similar to that just described. Fatty matter and (soda) lye 
 are run into the copper, and the whole is boiled together, care 
 being taken to avoid an excess of aJkali at first; when 
 saponification has taken place, lye is cautiously added until 
 
 M 2 
 
164 SOAP. 
 
 the soap tastes very faintly of caustic alkali, when the opera- 
 tion is iinished, and the soap is ready to be transferred to the 
 frames. Marine soap, for use with sea-water, is made in this 
 way, the fatty matter heing entirely coco-nut-oil, and the lye 
 heing usually at 32J° Tw. (20° B.). This soap is soluble 
 in weak brine, while other soaps are not. It is difficult to 
 make the saponification begin, but once begun, it proceeds 
 with extraordinary rapidity, the united mass of oil and 
 lye swelling up almost instantaneously to many times its 
 volume. In connection with hydrated soaps, Blake and Max- 
 well give the following table for the quantity of soda lye 
 necessary for their manufacture : — 
 
 100 lb. tallow 
 
 require 
 
 3800° 
 
 at 
 
 16i° Tw. (11° B.). 
 
 „ cooo-nnt-oU 
 
 „ 
 
 4100° 
 
 ,» 
 
 25°-32|° Tw. (16°-20° B.). 
 
 „ palm-oil 
 
 )» 
 
 3200° 
 
 9, 
 
 28 J°-36° Tw. (18°-22° B.). 
 
 „ lard 
 
 jj 
 
 3400° 
 
 « 
 
 20° Tw. (13° B.). 
 
 ,, tallow olein 
 
 )i 
 
 2800° 
 
 1, 
 
 28i°-36° Tw. (18°-22° B.). 
 
 „ olive-oil 
 
 j» 
 
 3000° 
 
 »» 
 
 25° Tw. (16° B.). 
 
 To use this table, divide the larger number of degrees by 
 the degrees Tw., and the quotient is the number of lb. of soda 
 lye at the gravity of the divisor, required to make a hydrated 
 soap with 100 lb. fat. 
 
 I.C, y. — Hard soaps, with soda for a base, made by open- 
 pan boiling, in which the glycerin is eliminated. This class 
 probably includes 90 per cent, of the total soap made in 
 English-speaking countries, and may be divided into 3 kinds, 
 curd, mottled, and yellow. The coppers for their production 
 have already been sufficiently described, but a necessary and 
 hitherto unused adjunct must now be explained, viz. the 
 pumps required for changing the lye beneath the soap. They 
 may be placed inside the copper, or outside, and, in this latter 
 case, are connected with the outlet pipes at K L, Fig. 42. 
 For small pans, a simple hand suction-pump answers ; for 
 larger ones, a single- or double-acting lift- or force-pump 
 may be placed inside the copper, and worked by hand, or by 
 an eccentric on a shaft. In large soap factories, some form of 
 centrifugal pump will be found very useful ; the usual objeo- 
 
MANUFACTURE OP HOUSEHOLD SOAPS. 
 
 165 
 
 tion to the use of these pumps, viz. the need of constant 
 luhrieation, being ohviated by the fact that, so employed, 
 they lubricate themselves. Their great advantages are the 
 absence of valves and of easily deranged working parts, and 
 the large amount of work they wiU do in a short time. In 
 England, the names of Gwynne and Appold have long been 
 connected with centrifugal pumps ; in America, the one most 
 usually employed is Hersey's patent rotary soap-pump (Hersey 
 Bros., Boston, Mass.), which is represented in Figs. 46, 47, 
 and 48. The pump should be placed as little as possible 
 
 Fig. 46. 
 
 Pis. 47. 
 
 Fia. 48. 
 
 above the outlets in the coppers, and connected therewith by 
 2^in. iron pipes, provided with valves. The pipes inside the 
 copper, communicating with the outlets, have swing joints, 
 so that they can be raised or lowered at pleasure. To avoid 
 the pipe-system becoming choked by soap congealing in it, a 
 steam-pipe should be inserted at one end, to warm the pipes 
 
166 SOAP. 
 
 and pump previous to use, and to " blow-out " all tlieir 
 contents at the end of the operation. In the figures, S is the 
 srt3tion-pipe ; H, the delivery ; P, the blades set upon a cone 
 (the rotation of which in the closed case produces the pump- 
 ing), which is kept in its place by adjustable set-screws. 
 This pump will transfer to any desired part of the factory, 
 lye, melted fat, finished soap (if not too stiff), " nigre," and 
 soft" curd. The diameter of the pump is 10 in., of its outlet 
 2J in. ; when making 120 rev. a minute, it will pump 6000 
 gal. an hour, its contents being twice emptied in each 
 revolution. 
 
 Whatever kind of hard soap is to be made, the first stages 
 of the process are the same for all; but since a curd or a 
 mottled soap requires the use of fire or " close " steam to 
 evaporate water during the final stages, it is desirable to 
 commence making those in coppers so provided, and either 
 high-pressure or superheated steam may be used in the 
 close-steam worm. Yellow soaps may be made in coppers 
 furnished only with an " open " or " free " steam worm. A 
 useful addition to any copper, giving more room to boil, and 
 hence adding to its capacity, is a " curb," or ring 2-3 ft. high 
 loosely fitted on in segments above the angle-iron of the top 
 ring of the copper itself, and capable of easy removal. If, 
 as in Fig. 42, the copper project 2|- ft. above the floor, a 
 " curb " 2^-3 ft. high may be conveniently added, and the 
 fan adjusted so that its blades revolve about 1 ft. below the 
 top of the curb. 
 
 To commence a boiling of hard soap, melted fat and caus- 
 tic soda lye (hereinafter only called lye) at about 16^° Tw. 
 (11° B.) are simultaneously run into the copper, and the steam 
 is turned on ; the same precautions to prevent an excess of 
 lye must be observed as are detailed in making soft soap ; if 
 lye stronger than 18° Tw. (12° B.) be used at this early stage, 
 saponification will not take place. When the contents of the 
 copper present the appearance of a homogeneous magma or 
 paste, lye of a higher sp. gr., say up to 42° Tw. (25° B.), may ^ 
 be cautiously added, but it is not essential to do so. The 
 
MANUFACTUBE OP HOUSEHOLD SOAPS. 167 
 
 boiling, and the addition of fat and lye, must be continued 
 until a small sample cooled between the fingers has a tolerably 
 firm consistence, and when applied to the tongue, no caustic 
 taste, or only a very faint one. Should there be a strong taste 
 (or " touch," to use the Americati term), or should the sample 
 separate into soap and liquor when squeezed, too much lye 
 has teen admitted, and more fat must be added. Should the 
 sample be soft and greasy, more lye is required, especially if 
 any uasaponified fat be yisible ; occasionally the 2 conditions 
 obtain, both caustic liquor and fat appearing in a sample, 
 which is evidence that combination has not taken place ; the 
 remedy is more boiling, with occasionally the addition of 
 water. Practice alone will enable the operator to judge of 
 the completion of this first operation, called " pasting " 
 (French, empdtage). In English phraseology, it is called 
 " killing the goods " or raw material, and the soap is then 
 said to be " close," or in a " hitch " or " glue.'' In this con- 
 dition, the soap should contain about -^ of the total soda 
 necessary for complete saponification, with a large excess of 
 water, which is separated from it in the next stage. 
 
 Separation (French, rilargage). — To effect this, a quantity 
 of common salt is sprinkled into the copper while still boiling, 
 or the strongest brine at 40° Tw. (24° B.) is run in. Since 
 the quantity necessary depends entirely on (1) the sp. gr. of 
 lye used in the last operation, (2) the amount of condensed 
 water where free steam is used for boiling, and (3) whether 
 there is much coco-nut- or palm-kemel-oil in the fat employed, 
 no directions can be given as to how much salt should be 
 added ; the addition should be made cautiously and gradually 
 (taking care to allow time for the solution of the salt), and 
 continued until a small sample removed upon a spatula or 
 trowel allows clear liquor to run from it. During this opera- 
 tion of " graining," the contents of the copper are very apt 
 to boil unsteadily, and occasionally to boil over with great 
 violence. When this point is reached, the whole process 
 should be stopped, and, the steam being turned off, the copper 
 should stand at least 2-3 hours. Its contents then divide 
 
168 SOAP. 
 
 themselves into 2 portions, the upper consisting of soap-paste 
 holding about 40 per cent, water, and the lower of a solution 
 known as " spent lye," containing common salt, any carbonate 
 and other sodium salts present as impurities in the original 
 lye, and nearly aU the glycerin of the fat employed. It 
 should contain no caustic soda, and no soap or saponifiable 
 material ; if it contains the latter, enough salt has not'been 
 used. For the presence of caustic soda, a sensitive tongue 
 will be found a sufficiently delicate tesf, while the addition of 
 a mineral acid will throw up a scum of fatty matter, if any 
 be present; it will also be found useful to observe the. sp. gr. 
 of the spent lye, as a means of controlling the amount of salt 
 used. After the copper has stood for some hours, the spent 
 lye should be pumped off, and, if there is then sufficient room, 
 more fat may be run in, and the whole operation repeated ! 
 at this stage, the rosin is usually added for a yellow soap, 
 being broken into lumps, and shovelled in, unless it is com- 
 bined with soda in a separate copper, and mixed with the fat- 
 soap in the next operation. 
 
 Clear-boiling (French, coction). — All the goods having been 
 " killed," and the spent lye removed, a small charge of lye at 
 about 18°-21i° Tw. (12°-14:° B.) is run in, and the copper 
 boiled for 2-3 hours ; at the end of this operation, the soap 
 should have a faint but decided caustic taste, and a small 
 sample on a spatula should allow clear lye to run off it ; if 
 this be not the case, more, and in some cases stronger lye, 
 must be added. This operation communicates additional 
 soda to the soap, and washes out, as it were, some of the salt 
 entangled in it. After some hours' subsidence, the "half- 
 spent " lye that sinks to the bottom is pumped off, and may 
 be used in another copper for " killing " more fresh goods ; 
 the soap from such lye, however, will be of an inferior 
 colour. 
 
 The next stage of this operation is to boil the copper with 
 open steam ; if the contents are not perfectly homogeneous, 
 and in a state resembling a stiff paste, i. e. if the copper be not 
 " close," but have a tendency to separate into lye and soap, 
 
MANUFACTURE OF HOUSEHOLD SOAPS. 169 
 
 when examined on a spatula, the sp. gr. of the entangled lye 
 is reduced by the addition of water, until the desired condi- 
 tion is reached. A small stream of lye at about 18° Tw. 
 (12° B.), is then allowed to trickle in, until the homogeneous 
 paste again separates into flakes of soap and clear lye, the 
 boiling being continued all the time ; the soap should now 
 taste strongly of caustic soda, and feel hard when cold ; this 
 operation is technically called " making " the soap, and when 
 enough lye has been run in, boiling should be continued 
 for some hours, to ensure complete saponification, since it is 
 very difficult to make neutral fats take up the last portions 
 of soda. The large coppers previously alluded to require a 
 whole working day (12 hours) for this operation. 
 
 The operations above described, may in experienced hands 
 be somewhat reduced in number and time, but much greater 
 care is then required. By the proper use of lye of various 
 degrees of concentration and of salt, it is possible to " kill " 
 40-50 tons of mixed tallow and rosin in one copper in a 
 day — to dispense with the next operation — and to " make " 
 the copper on the day following, finishing it on the third 
 day. The mode of finishing depends entirely on the kind of 
 soap required. 
 
 Curd Soaps. — The raw materials for curd soaps should 
 contain no rosin, and but little, if any, coco-nut- or palm- 
 kernel-oil, but any other oils or fats may be used. White 
 curd is usually made from tallow or lard, or a mixture thereof ; 
 brown curd, from bleached palm-oil, or kitchen-grease, or 
 bone-tallow, and manufacturers' curd-soaps, from various fats. 
 When the soap is " made," the open steam is shut off, and 
 the boiling is continued either with fire or with close steam ; 
 this concentrates the lye, and the flakes of soap gradually 
 approach the spherical form. From time to time, the boiling 
 is stopped, the sp. gr. of the lye is observed, and a sample of 
 the soap, from which the lye has been allowed to separate, 
 is put out to cool. When it is sufficiently hard, the boil- 
 ing is finally stopped, and after a few hours' subsidence, the 
 
170 SOAP, 
 
 soap is ready to be removed ; the amotint of water left in 
 it varies inversely as the sp. gr. of the lye in which it is 
 boUed. 
 
 Mottled Soaps. — The term is here used to denote the old- 
 fashioned curd-mottled soaps, not those marbled with blue, 
 grey, or red, which have appeared in the English and foreign 
 markets within the last 20 years, and which will be described 
 in Chap. VII. In the fabrication of soap, it is impossible to 
 avoid entirely the presence of earths and metallic oxides. 
 These conseq[uently decompose a small portion of the soap, 
 combining with its fatty acids, and forming soaps of lime, 
 magnesia, and iron (from the " coppers "), which though in- 
 soluble, are softened by heat, and disseminated in a state of 
 minute division through the soap-paste ; any slight impurities 
 in the fat employed, when not dissolved in the caustic soda 
 solution, are similarly diffused. If, after a soap is " made," the 
 lye in which it is suspended is concentrated to a point short 
 of that necessary to produce hard curd-soap, and it is then 
 transferred to the cooling-frames, with a certain quantity of 
 lye entangled in it, these insoluble particles will, during the 
 solidification of the soap, collect together, and produce the 
 appearance known as " mottling " ; and the effect is heigh- 
 tened by the partial crystallization of the soap. No rule can 
 be given for the point of concentration ; it varies with the 
 fat used, with the amount of lye in the copper,, with th,e 
 quantity of salts other than caustic soda in them ; and in 
 short, the proper " mottling condition " is a physical one, 
 chemical tests being of little use in deciding it. Nothing but 
 practice and careful observation can make a successful mot- 
 tled-soap boiler. The principle of the process has been clearly 
 laid down ; and the various formulae given in books, involving 
 in many instances several changes of lye, are but different 
 modes of arriving at the same result, viz. the suspension 
 of pure soap, and of soaps of the metallic oxides, in soda lye 
 of a given sp. gr. If the soap be boiled too long, it " sets " 
 in cooling before the mottling has had time to aggregate; 
 
MANUFACTUEE OF HOUSEHOLD SOAPS. 171 
 
 if it is not boiled enougli, an undue quantity of lye remains 
 in tlie soap ; but, from their mode of manufacture, mottled 
 soaps always must contain some lye in tbe cavities between 
 the curds ; hence they are the most suitable and really econo- 
 mical soaps for washing clothes, &c., in hard waters, although 
 not, of course, for toilet purposes. It not unfrequently hap- 
 pens that the soap-copper does not contain enough metallic 
 soaps, &c., to produce a definite mottle. In this case, some 
 " mottling " is added ,• for a grey, Frankfort-black, or very 
 finely levigated manganese black oxide, may be used ; the 
 peculiar greenish mottle which becomes red on exposure, 
 characteristic of Marseilles and Castile soaps, is produced by 
 adding some solution of iron protosulphate to the copper 
 when the soap is nearly finished (about 4 oz. of the salt to 
 100 lb. fat) ; the precipitated iron protoxide suspended in 
 the soap is greenish, but it becomes peroxide in contact with 
 air, to which the change to a red colour on exposure is due. 
 
 In England, mottled soaps are usually made from kitchen- 
 grease, and from bleached palm-oil. In Marseilles, from 
 mixtures of various seed-oils, of which olive-oil is the 
 principal, and cotton-seed-, poppy-, hempseed-, gingelly-, and 
 ground-nut-oils are frequent components. In these mottled 
 soaps, little or no coco-nut- or palm-kemel-oU. should be used, 
 although such oils form an almost essential constituent of 
 the new mottled soaps referred to above. 
 
 Yellow Soaps. — The finest yeUow soaps are made from the 
 best tallow and rosin, which last is an essential constituent 
 of them ; in some cases, lard, or lard-stearin is used. Inferior 
 qualities may be made from the " nigres " of better sorts, from 
 bleached palm-oil, greases of aU kinds, and in fact from any 
 saponifiable solid fat ; fluid oils must be used, if at all, in 
 small quantities and with caution. The proportion of rosin 
 may vary from \ of the total fat, to an equal weight, or even 
 more, according to the quality of soap required. In the 
 south and west of England, the very best quality is known 
 in the trade as "Primrose," and is made from the finest 
 
172 SOAP. 
 
 (unHeaolied) tallow and " window-glass " rosin ; the lowest 
 grade of brown is made from the " nigres " of the grades ahove, 
 mixed with curriers' grease, leather tallow (" sod-oils "), and 
 other dark and foul but hard fats, with black rosin. 
 
 Although rosin is insoluble in water, its compound with 
 soda is soluble, the solution frothing strongly like that of 
 the fatty soaps, which, in most respects, it closely resembles. 
 The chief point of difference is the granular character of the 
 solid compound, which prevents its being compacted into 
 masses having the sectile consistency of the fatty soaps. 
 But it is nevertheless capable of being incorporated in con- 
 siderable proportion with the fatty soaps, without sensibly 
 affecting the consistency of the product, although the colour 
 and smell of the latter are thereby modified ; in fact, the 
 characteristic colour and odour of " yellow soap " are due 
 mainly to the rosin in it.* It is scarcely necessary to poiat 
 out that no question of adulteration can be raised in this 
 connection. The soda-rosin-acid salts are valuable deter- 
 gents, whose application alone would be very limited, owing 
 to their inferiority, in certain points, to the soda-fatty-acid 
 salts. But as this is duly recognized in the price of the 
 soap, there can be no suggestion of fraud. 
 
 The finishing operation for yellow soaps is termed " fitting " 
 in England, and liquidation in France, and requires consider- 
 able judgment on the part of the operator. After being 
 thoroughly well "made," the copper stands at r§st for at 
 least 12 hours ; the half-spent lye is then pumped off, and 
 the open steam is turned on. When the copper is again 
 boiling, it should be continued so until its contents are 
 perfectly homogeneous (the time depending much on the size 
 of the copper), and the soap should then be examined with a 
 clean trowel. When in proper condition, a thin layer should 
 drop off a hot trowel held edgeways, in 2 or 3 flakes, leaving 
 
 * The odour is due mainly to American rosin, whioh differs very 
 markedly in this respect from French. Moreover, with grades of equal 
 colour, American rosin gives a soap decidedly superior in this respect to 
 that from French rosin. 
 
MANUFACTUEE OF HOUSEHOLD SOAPS. 173 
 
 the metallic surface quite clean ; but if, as is more probable 
 the layer breaks up into several small jQakes, and the soap is 
 stiff, water should be cautiously added, to reduce the sp. ot. 
 of the still-entangled lye. If, on the other hand, the film 
 will not leave the trowel at all, a small quantity of strong 
 lye, at say 23°-32J° Tw. (15°-20° B.), or of brine, may be 
 cautiously added, to cause it to do so. In the first case, the 
 " fit " is said to be " open " or " coarse " ; and in the second, 
 to be " close " or " fine." Here, again, practice and observa- 
 tion alone enable the operator to obtaia " a good fit," and 
 when it is obtained, the steam is turned off, and the whole is 
 allowed to stand. The copper is then covered up with planks, 
 or an iron cover, and kept as warm as possible ; small coppers 
 may stand a day or two, large ones as long as a week. 
 During this period, the contents arrange themselves in 3 
 layers, (1) a light crust full of air-bubbles, technically called 
 " fob," (2) the finished or " neat " soap, forming about f of 
 the whole, (3) the " nigre," which is an impure soltition of 
 soap in lye, and contains all the impurities present in the 
 copper. The amount of this last depends entirely upon the 
 character of the " fit." A fine fit gives a very large nigre, 
 containing much soap ; while a coarse fit gives a small nigre, 
 composed chiefly of impure lye. The English practice is to 
 fit rather " fine," competition among the various makers for 
 purity and colour being excessive; while the Americans 
 are usually content with a coarse fit. 
 
174 SOAP. 
 
 CHAPTER VII. 
 
 TEEATMENT OF SOAP AETEK ITS EEMOVAL PEOM 
 THE SOAP-COPPEE,— Household, Manufactueees', akd 
 Toilet Soaps. 
 
 Aftee the soap has been finished in the copper, it may either 
 be put in the "neat" state direct into the cooling-boxes or 
 " frames," or it may be transferred to mixing-tanks where 
 various solutions or substances are incorporated -with it, 
 prior to its being allowed to solidify. Curd soaps, and most 
 old-fashioned mottled soaps (unless they are so thin, and 
 their curd so flat, that they may be treated like a fitted soap), 
 should always be carefully skimmed off the subjacent lye by 
 ladles, a process which demands very careful attention in the 
 case of curd soaps, lest any portions of lye should be acciden- 
 tally entangled in the soap, producing want of homogeneity, 
 called "rowiness," seen when the soap is cut up for sale. 
 The same appearance is presented in curd soaps which are 
 framed before they have been boiled dry enough, i. e. when 
 the sp. gr. of the lye and the state of aggregation of the soap 
 particles are insufficient to cause a complete separation, after 
 standing, between the lye and the soap. Mottled soaps, 
 however, not being boiled so dry, i.e. the lye not being 
 so concentrated, always should contain a fuU proportion of 
 lye, thus meehanically mixed with the curd. 
 
 In large factories, fitted soaps are invariably transferred 
 to the frames by suitable pumping machinery. A peculiar 
 method. of emptying coppers which contain perfectly homo- 
 geneous soaps, without any nigre or lye beneath them, was 
 invented by Gossage, and is represented in Figs. 49, 50. 
 An air-tight cover is screwed on to the copper, and a blast of 
 air is turned in through A ; the pressure thus exerted forces 
 
TREATMENT AFTER REMOVAL FROM SOAP-COPPER. 175 
 
 the soap out through the delivery-pipe B in a continuous 
 stream, until the lower end of that pipe becomes uncovered, 
 when air rushes through it. This is chiefly used for hy- 
 drated soaps, and for the "blue-mottled" soaps, described 
 on pp. 190-3. 
 
 Soap-frames are of 2 kinds, according as it is desired to 
 cool the soap slowly or quickly. In England, the internal 
 measure of both is 45 in. x 15 in., a reUc of the days when a 
 duty (removed in 1853) was levied ; the width of this makes 
 
 the length of the English bar of hard soap, which is usually 
 either 2J or 3 lb. in weight, according to its thickness. 
 Where slow cooling is required, as is always the case with 
 mottled soap, wooden frames, usually made of pine, are 
 employed. Their general appearance is shown in Fig. 51; 
 each section or " lift " (2) is lined with thin sheet-iron, the 
 wood being 2i^3 in. thick, and the several sections, each 
 about 9-12 in. deep, should fit closely upon each other when 
 piled in a series (1). The bottom of the frame (3) may 
 
176 
 
 SOAP. 
 
 be made of wood or of brick; in the case of curd-mottled 
 Boaps, it is convenient to have a well in the bottom, to 
 receive the lye which drains from the soap, especially if, as 
 
 FiQ. 51. 
 
 is frequently the case, the frame is 20-30 ft. high. Most 
 curd and all yellow soaps are cooled rapidly in cast-iron 
 frames of any desired shape and size. Figs. 52, 53, show a 
 
 Fia. 52. 
 
 Fig. 53. 
 
 longitudinal section and plan of a form frequently adopted in 
 England, which is almost water-tight; the superficial mea- 
 sure is 45 in. x 15 in., and the height 50-60 in. The 4 sides 
 are held together by bolts and nuts, and when the soap is 
 
TREATMENT AFTER REMOVAL FROM SOAP-COPPER. 177 
 
 cold (i. e. after tlie lapse of 3-7 days for this size), these 
 are unscrewed, the sides are removed, and a solid block of 
 soap is left standing on the bottom of the frame. This 
 may be at once cut up into slabs and bars, or may be slid 
 away bodily to store. Occasionally such frames are mounted 
 upon wheels, for convenience of transport about the factory. 
 During the cooling of stiff soaps, it is desirable, in order 
 to avoid waste in the subsequent cutting, to follow up the 
 
 C 
 
 Fia. 54. 
 
 contraction of the Pia. 55. 
 
 soap in the frame 
 
 by slight pressure, 
 
 exerted either by a 
 
 screw -, top to the 
 
 frame, or by beating 
 
 down the soap with 
 
 a mallet. 
 
 When it is desired 
 to cut the soap, the 
 sides of the block are 
 marked with a scribe. 
 
 Fig. 54, the teeth of which are set at the thickness desired 
 for the bar of soap. A brass or steel wire is then taken 
 by 2 men, and drawn through the block, Fig. 55, which 
 is thus divided into slabs; these are at once removed 
 to a machine which will divide them into bars. The 
 cutting-machine usually employed in England is shown 
 in Figs. 56, 57, 58. The cutter itself is worked by a 
 
 N 
 
178 
 
 SOAP. 
 
 
 t 
 
 ^' 
 
 -•« 
 
TEEATMENT AFTER EEMOVAL FKOM SOAP-COPPEE. 179 
 
 lever-frame L, wliioli contains wires, or, for very hard 
 soaps, thin steel knives h ; the slab is placed longitadinally 
 and nearly upright on the base-hoard 6, and the lever-frame 
 is then drawn through it. The bars thus formed fall back 
 upon the shelf / behind, whence they may be removed and 
 set aside to get cold. Before repeating the operation, the 
 lever-frame must be raised, and hitched in its place by the 
 spring-catch c. The bars, when removed from the machine, 
 are piled across each other in " open pile," in such a way 
 that air freely circulates among them. When thoroughly 
 set, they are stored away in " close pile," or packed in 
 boxes for distribution. In America, Ealston's cutter and 
 spreader. Fig. 69, is largely used ; it has an arrangement 
 A B for spreading and stamping the bars, and is very useful 
 where soap is rather soft when freshly cut. The slab is 
 laid upon C, and the cutting-wires are shown at D. Van 
 Haagen, of Cincinnati, has devised a machine for dividing 
 a frame of soap into bars all at one operation, and various 
 slabbing-machines have been invented, none of which, how- 
 ever, has come into very general use, and they will not 
 be further described. The main objection to them is the 
 tendency of slabs and bars of soap, when fresh, to adhere 
 strongly together, unless they are immediately separated. 
 
 In connection with the cutting-up of soap, it may be 
 conveniently mentioned here that certain soaps undergo a 
 kind of case-hardening process as soon as they have been 
 barred-up. Most of the French mottled soaps are soaked, or 
 even stored, in weak lye, or weak brine, or a mixture of both ; 
 and some of the English blue-mottled soaps are also soaked 
 in brine. The usual process, however, is a drying one, which 
 may be carried out either by directing a current of warm, 
 dry air, by a fan or otherwise, against a pile of bars, or by 
 spreading the bars in a drying -chamber, Fig. 60, which 
 is heated by fire to a temperature short of that at which 
 the soap begins to melt. The fire is kindled in A, and the 
 heated products of combustion pass along E to F, while the 
 air, which enters at H, heated by them rises through the vent- 
 
 N 2 
 
180 
 
 SOAP. 
 
 holes 0, and, after taking up much moisture from the soap M, 
 passes out through K. 
 
 The bars of soap, when freshly cut and still soft, are 
 
 usually impressed with some words indicating the name or 
 quality of the soap, and the trade-mark or name of the 
 manufacturer. This is most simply done hy a hand-stamp. 
 
TBEATMENT APTEK REMOVAL FROM SOAP-COPPEE. 181 
 
 in whicli the letters or device are out in hard wood or cast 
 in brass (B) ; the arrangement and mode of using it with 
 very hard soaps are shown in Figs. 61, 62. 
 
 In England, it has long been customary to sell soap in 
 bars 15 in. long, weighing 2^3 lb. ; but during' the last 
 
 Fig. 60. 
 
 Pro. 62. 
 
 FiQ. 61. 
 
 few years a great demand has sprung up among the retailers 
 for ordinary household soaps cut and stamped into 1-lb., 
 ^Ib., and :J-lb. blocks, a form which also obtains to a very 
 large extent in America. Various parts of each country 
 differ considerably in the shapes preferred for these blocks, 
 
182 
 
 SOAP. 
 
 and the formation of each kind demands a special set of 
 cutting-wires, and of moulds and dies, for their production. 
 The 1-lb. and ^-Ib. blocks are often " semi-cut," so that they 
 can be readily divided into 2 ^-Ib. and J-lb. pieces respec- 
 tively. The simplest moulds are usually cast in brass, each 
 tablet requiring 2, producing an upper and an under sur- 
 face; but occasionally a mould-box a b with hinged sides 
 is employed, with a screw-press, such as is represented in 
 Fig. 63. With the ordinary tablets, it is necessary to 
 
 Fis. 63. 
 
 slightly dry them superficially, and to give them a very 
 thin coating of oil, that they may not stick to the die. 
 The simplest form of hand-press will stamp upwards of 
 600 |-lb. pieces an hour. For larger tablets, a foot-power 
 press is desirable, such as that made by W. H. King, 
 Philadelphia. All large manufacturers, however, employ 
 some form of steam-power press ; one made by Neill & Sons, 
 
TREATMENT APTEK REMOVAL FROM SOAP-COPPER. 183 
 
 Fig. 64. 
 
 St. Helens, Lancashire, England, is shown in Fig. 64. By 
 moving the handle A, steam is admitted into the bottom of 
 the steam-oylinder D ; the piston being forced up, the 
 cylinder lowers the die E into the die-box F. The rod 
 attached to the lever at B works in connection with a die 
 that is always in the die-box 
 and attached to the spindle 
 Cj having a slot for the lever 
 to work in such a manner 
 that when the piston is at the 
 bottom of the steam-cylinder 
 the bottom die is at the top of 
 the die-box, and when the 
 piston is at the top of the 
 cylinder the bottom die is at 
 the bottom of the die-box; 
 thus the stamped tablet, being 
 raised out of the die-box at 
 each stroke, can readily be 
 removed. The great advan- 
 tage of the lever working the steam valve is, that the, 
 attendant must take his hand from the dies before the 
 blow is given, thus preventing accidents arising through 
 the blow being given when the hands are at the dies. A 
 very ingenious press was patented by Mr. F. J. Cleaver in 
 1870, and exhibited in action by his firm at the International 
 Health Exhibition, 1884. It comprised a turn-table holding 
 4 lower moulds, a pile-driving stamp, worked by a double 
 cam, and an ingenious mechanical finger to pick up the 
 stamped tablets, and deposit them upon a moving belt. 
 Another form (Fig. 65) is made by Hersey Bros., Boston, 
 and with it a smart workman can mould 2000 cakes an 
 hour ; it is supplied with steam at 20 lb. pressure through 
 a tin pipe. 
 
 Hitherto, in treating of the fabrication of soap, genuine, 
 unsophisticated, or " neat " soaps, containing not more than 
 32 per cent, of water when freshly made, have been described. 
 
184 
 
 SOAP. 
 
 It now remains to deal with, tlie various substances whicli , 
 are mixed, by almost every manufacturer, with, soaps after 
 they have been removed from the copper, and the mode of 
 their incorporation, known in the trade by the suggestivp 
 name of " filling." These may be classed under two heads. 
 
 Fig. 65. 
 
 The first class, which will be considered somewhat in detail, 
 comprises all those soluble alkaline salts, such as silicates and 
 carbonates, added to soap to increase its detergent power; 
 between the two classes may be placed water, which is 
 always present to a greater or less extent in " filled " soaps, 
 
TREATMENT AFTER REMOVAL FROM SOAP-COPPER. 185 
 
 and simply reduces their actual value and economical use; 
 while the second class includes all insoluble substances, such as 
 clay, steatite (i. e. soap-stone, or magnesium silicate), pow- 
 dered talc, barium sulphate, starch, fecula, as well as all 
 soluble substances, like glue and gelatin, which have no de- 
 tergent power in themselves, and are simply added to increase 
 the quantity of water in soaps, or as mere adulterants or 
 make-weights. (A notable example of this is the use of clay, 
 or steatite, 5 or even 10 per cent, of which may be mixed 
 with soap without its presence being apparent to the eye.) 
 Tor obvious reasons, only the use of the first class will 
 be described in the present chapter ; but further remarks on 
 the subject, and methods for detecting and determining the 
 quantity of these adulterants, wiU be given in Chap. VIII. 
 on the Analysis of Soap. 
 
 With the exception of the silicated mottled soaps (blue, grey, 
 and red), a special description of which is given on p. 190, 
 all " filled " soaps are made by incorporating the soap-paste 
 fresh from the copper with the " fiUing," at a tempetature 
 of about 170° F. (77° C). On a small scale, this may be 
 readily done by stirring the two together in the soap-frame 
 with a " crutch," which is a perforated piece of wood or 
 iron, whose flat side is attached at right angles to a pole, by 
 which it is moved by a man vertically up and down in the 
 frame. When many tons have to be mixed, however, 
 machinery in some form must be employed, and the choice 
 of the form thereof depends upon the probable consistency 
 of the mixture. Whatever form be decided upon, it is quite 
 essential that it should not merely mix the soap in one plane, 
 but that the contents of various planes should be inter- 
 mingled; simple rotation of arms at right angles to a vertical 
 shaft is therefore insufficient. 
 
 Such an arrangement is shown in Figs. 66, 67. The 
 blades E of the mixers are set at an angle of 45° on the 
 shaft A B, at the top of which is a pair of bevel-wheels 
 with fast and loose pulleys CD; F is the discharge-hole, 
 provided with a valve for drawing off the stiff soap. At 
 
186 
 
 SOAP. 
 
 Pig. 66. 
 
 Fig. 67. 
 
TREATMENT AFTEK REMOVAL FROM SOAP-COPPER, 187 
 
 G G', are portions of the mixers and scrapers in section. It 
 is desirable, but not necessary, that there should be some 
 means of controlling the temperature Of the tanks or vessels 
 in which the " orutching " (as this mixing process is techni- 
 cally called) is carried on. Close steam-worms or steam- 
 jackets are very suitable for this purpose ; they should in all 
 cases, however, be cased with a non-conductor, to prevent 
 loss of heat by radiation. 
 
 Where very fitiff soap has to be crutched, probably the 
 best arrangement is an Archimedean screw, which is very 
 largely used in America, where most of the soap made is 
 very stiff;" this lifts up the various layers most effectually, 
 and is most conveniently set inside a jacketed cylinder, 
 whose height is about 1 J times its diameter. Tor crutching 
 soaps that are somewhat thinner, such as are usually made 
 in England,- the crutching-machinery designed by Neill & 
 Sons, St. Helens, Lancashire, is very suitable. 
 
 One of the earliest methods of cheapening, hardening, and 
 increasing the detergent powers of soaps was that proposed 
 by Dr. Normandy, who mixed " neat " soap with crystallized 
 sodium sulphate, previously melted in its own water of 
 crystallization. The salt re-crystallized in the soap as it 
 cooled, and the soap was thereby considerably hardened, so 
 that it wore better in the wash-tub when rubbed upon 
 clothes, and in this way its detergent power was mechani- 
 cally increased, although sodium sulphate as such, being a 
 neutral salt, had no detergent power of its own, and its 
 addition to soap really diminished chemically the percentage 
 of soda available for washing. These soaps usually effloresced 
 with a white powder, and gradually fell out of use, especially 
 as raw fatty matters became cheaper. 
 
 It was then discovered that the addition of sodium 
 carbonate, or " sal soda," has a remarkable effect in stiffen- 
 ing and hardening soaps to which it is added in a state of 
 strong solution ; it also increases chemically their detergent 
 power. This process is very largely employed in America ; 
 the amount of soda used depends upon the raw materials 
 
188 SOAP. 
 
 from wliich the soap is made, and upon the quality of the 
 desired product ; a very usual proportion is 1 cwt. sodium 
 carbonate crystals (melted) to every ton of soap. Not un- 
 frequently, a solution of pearl-ash (impure potassium car- 
 bonate) and common salt, mixed in varying proportions, at 
 a sp. gr. of about 52°-64° Tw. (30°-35° B.), is used for a 
 similar purpose. 
 
 SiLicATED Soaps. — The discovery of methods of manu- 
 facturing on a large scale soluble potassium and sodium 
 silicates, gave a very important impetus to the soap-trade, 
 since these substances are peculiarly suitable for the purposes 
 now being described. Their first application on a large scale 
 was the production of soaps by Christr. Thomas & Bros., of 
 Broad Plain Soap and Candle Works, Bristol, containing 
 " both sUicate and sulphate of soda," and by these means they 
 were able to produce, and patented in 1856, a soap of very 
 great detergent power, which could be sold retail at less than 
 the duty on soap, which had been removed a few years 
 previously. It is usually supposed, however, that the value 
 of silicated soaps was first publicly and of&oially recognized 
 at the International Exhibition of 1862, when a prize medal 
 was awarded to W. Gossage and Sons, Widnes Soapery, for 
 their samples. 
 
 Sodium silicate may be mixed with almost any kiud of 
 soap, but the strength of the solution employed must be 
 varied according to circumstances. Very weak solutions 
 are often added to " neat yellow soaps," and when employed 
 in this way, it is a good general rule, ceteris paribus, to 
 increase the sp. gr. of the solution with the percentage of it 
 employed. Thus, if it be desired to increase the quantity 
 of water in a " neat " soap by 4r-5 per cent., a solution at 
 7^° Tw. (5° B.), when cold, wiU be suitable; while if the 
 quantity of water is to be increased to a total of 50 per cent., 
 a stronger solution, say 15°-18° Tw. (10°-12° B.) is required. 
 This kind, technically known as "run soap," was at one 
 time largely made in America, and stiU. is in England, under 
 the name of " London pale," in the south and west, and of 
 
TREATMENT APTEB EEMOVAl FROM SOAP-COPPER. 189 
 
 " Primrose " in the north. Such soaps are of the consistency 
 of thin treacle when mixed, at say 160°-170° P. (71°-77° C), 
 and are apt to disappear rapidly in hot water, as well as to 
 lose weight when kept. They are usually subjected to the 
 storing or case-hardening process described on p. 179. 
 
 A more legitimate application of sodium silicate is to mix 
 varying quantities of the concentrated solution with " neat " 
 yellow or curd soaps. This treatment makes yellow soaps 
 much stiffer, and in many cases, hy hardening them, adds 
 to their durability. About 5 per cent, of the solution at 
 140° Tw. (59^° B.), is a suitable quantity, and has much 
 the same effect as the addition of the 5 per cent, of sodium 
 carbonate crystals before described. Much larger quantities 
 than 6 per cent, may be used, but soap so treated is apt to 
 disintegrate unpleasantly in use, as well as to feel very 
 harsh to the hands of the consumer. Curd soaps are sold 
 in England vrith which 15 or even 20 per cent, of sodium 
 silicate at 140° Tw. have been mixed. These large quan- 
 tities considerably increase the " soda available for wash- 
 ing," as given by the alkalimetric test (see Soap Analysis, 
 Chap. Yin.). 
 
 In connection with silicated soaps, the following quotation 
 from Mr. C. F. Cross's lecture on Soap at the International 
 Health Exhibition of 1884, deserves attention : — 
 
 " The solution of sodium silicate is inferior in lathering 
 properties, its detergent action is not aided, as in the case of 
 the soaps, by a softening action of the acid constituent upon 
 the surface to be cleaned, and lastly it cannot be brought 
 into a form so universally convenient as that of soap; 
 existing only as a glassy solid or a viscous liquid. There- 
 fore it can only be used in a state of solution, or when in- 
 corporated with a sufficient proportion of soap to aUow the 
 physical properties of the latter to preponderate. These 
 considerations will enable us to appreciate the right side of 
 the " silicated soap " question. The wrong side consists, not 
 in production by means of the silicate of a detergent of lower 
 quality, but in not selling it at a proportionately low price. 
 
190 SOAP. 
 
 A silioated soap is an advantage to commerce, for there is 
 much work which it can perform as well as, if not better 
 than, soaps of higher quality. But let there be fair division 
 .•of the advantage between manufacturer and consumer, and 
 the millenium will not suffer postponement." 
 
 Blue, Grey, and Bed Mottled Soaps. — These come under the 
 head of siHcated soaps, and are thus made. Two coppers are 
 required, an ordinary steam-copper for the first stage, and a 
 fire-copper, for the later stages. In the steam-copper, the 
 raw materials are saponified, and fitted rather open. The 
 fat-mixtures employed are usually vegetable oils, and almost 
 always (though not necessarily) contain a fair proportion of 
 cooo-nut- or palm-kemel-oil. When first introduced from 
 Germany, these soaps were made from well-bleached palm- 
 oil and coco-nut-oil, in such proportions as 3 palm- to 2 coco- 
 nut-, or 2 to 1, or even 3 to 1. Latterly, however, palm- 
 kernel- has supplanted coco-nut-oil, and some of the palm- 
 has been replaced by refined cotton-seed-oil. The choice of 
 materials is very much guided by their cost. The fitted soap 
 is shifted off its nigre into the fire-copper, and, to every 
 1000 lb. of it, is added about 250 lb. solution of sodium sili- 
 cate at about 82^° Tw. (20° B.) ; the exact sp. gr. depends 
 chiefly upon the proportion of palm-kernel- to other oils. 
 The whole is then boiled together with steam and fire, to 
 thoroughly incorporate the mass ; when this is complete, the 
 steam is stopped off, and the appearance of the copper is 
 examined. Practice and experience, assisted by chemical 
 analysis, can alone decide when the soap is in "mottling 
 condition " ; in that state, it should have about 45 per cent. 
 (or less) of fatty acids, and • 5-1 • per cent, of sodium 
 chloride, according to the raw materials employed. A good 
 physical test is to take a layer out rapidly upon a cold 
 trowel, qnd observe its appearance, and the time required 
 for it to " set." A shiny appearance on its surface indicates 
 a deficiency, a frosty appearance, an excess, of mineral salts ; 
 if it sets too quickly, and is shiny, more sodium chloride 
 must be added ; if it appear frosty, and is long in setting. 
 
TEEATMENT AFTEB EEMOVAL FROM SOAP-COPPEE. 191 
 
 enough mineral salts are present. So delicate is tte process, 
 that the addition of 1 Ih. salt per ton of soap at this stage 
 will entirely alter the appearance of ihe mottling when cold. 
 When it is in mottling condition, the mineral substance nsed 
 as mottling is mixed with a small quantity of water, and 
 sprinkled into the copper ; it is there thoroughly incorpo- 
 rated with the soap hy a few minutes' boiling, and the soap 
 is then transferred as rapidly as possible to wooden frames, 
 which are carefully covered up when full, and kept as warm 
 as possible, to allow time for the " mottle to strike." For 
 blue mottle, 5-10 lb. artificial ultramarine per ton of soap 
 a,re used ; for grey, 1-3 lb. finely levigated manganese oxide. 
 If the soap be cooled rapidly, it will be of a homogeneous blue 
 or grey colour ; slow undisturbed cooling is essential to these 
 soaps, and once in the frame, they should never be touched 
 until they are quite cold ; it was for them that Grossage de- 
 vised the pneumatic method of emptying coppers (p. 174), 
 but a centrifugal pump answers as well. It requires greater 
 skill to make good " blue-iaottled " soap than for any other 
 kind, and the manufacture is in the hands of a few large 
 firms. 
 
 Another mode of producing these soaps is to make a por- 
 tion of the fat employed (usually all the coco-nut-oil, with or 
 without some portion of the other oils) into hydrated soap 
 (p. 163); the remainder of the fatty matter is made either 
 into a " fitted soap " or a " flat curd " soap, and then trans- 
 ferred to the hydrate previously prepared in another copper ; 
 after both are incorporated by thorough boiling, the soap is 
 finished as before directed. This method, for which Blake 
 & Maxwell and C. N. Kottula had various patents, was intro- 
 duced into England from Germany by the last named about 
 25 years ago ; it is said to~ produce a more solid and close 
 soap from the same materials than any other method, but 
 when a blue-mottled has to be made, the greatest care must 
 be used to allow no impurities in the materials for the 
 hydrated soap, or the brilliancy of the mottling wUl be 
 seriously interfered with. 
 
192 SOAP. 
 
 It may be observed here that in these soaps, the mottling, 
 so difficult to produce, is a matter of appearance merely, and 
 that soap with a plain white ground would wash just as weU. 
 The remarks ,of Mr. Cross, upon mottled soaps, in his Health 
 Exhibition lecture quoted on p. 189, are very much to the 
 point in this case. Speaking of naturally mottled curd soaps, 
 he says : — 
 
 " Still more meretricious methods have been followed for 
 imitating this natural marbling of soaps, not so much for 
 the sake of the particular effect, but because mottled soaps 
 are necessarily of high quality, and the next thing to 
 possessing this quality is to possess the appearance 
 which is its more obvious criterion. . . . The practice of 
 artificially mottling inferior soaps — even though there be 
 not the slightest intention to defraud — ^is not to be com- 
 mended. It is difficult to see any useful purpose which 
 it subserves, and it certainly cannot be defended on art 
 grounds. We would therefore ask consumers to aid in 
 breaking down a bad custom — bad, because it wears an 
 appearance of evil intent — ^by avoiding artificially mottled 
 soaps. We would more especially instance the blue mottled 
 soaps in which the marbling is produced by means of tiltra- 
 marine blue incorporated into the soap-paste. It requires 
 very little insight to enable the buyer to detect an artifi- 
 cially marbled soap, and we hope no further showing to 
 induce him to reject it when detected." 
 
 To this emphatic condemnation may be appended the pub- 
 lished remarks of another soap-manufacturer, Mr. Leopold 
 Field, who, in speaking of the various classes of soaps and 
 of Castile soap and the common red, blue, and grey mottled 
 soaps in particular, says : — 
 
 " The two last are really only varieties of the others, and 
 well exemplify the manner in which manufacturers have to 
 fall in with the public prejudice to the public detriment. 
 
 " From time immemorial the soaps made in the south of 
 France and the north of Spain (Marseilles and Castile) have 
 enjoyed the highest reputation, and deservedly so ; inasmuch 
 
TREATMENT AFTEE EBMOVAL FROM SOAP-COPPEE. 193 
 
 aB, at least till lately, they were prepared from vegetable 
 oils and natural alkalies containing enough potash to give 
 a plasticity and smoothness which was lacking in pure 
 soda soaps. Now as these natural alkalies contained a 
 certain amount of mineral matter (oxides and sulphides of 
 iron and manganese), the soaps, during making, developed 
 coloured streaks and blotches, thus acquiring a marbled 
 appearance. In a thin watery soap, this colouring matter 
 would have sunk to the bottom, and hence the mottled 
 appearance was held to be a proof of excellence. With fine 
 logic therefore, the public came to the conclusion that be- 
 cause Castile soap, which was good, was mottled, therefore 
 all mottled soap must be good. Consequently the manufac- 
 ture of ' mottled soap ' has become an art of itself, the 
 object naturally being to get as much mineral matter in as 
 poor a soap as may be, and in this, as in most branches of 
 adulterative art, the Germans shiae supreme." [The manu- 
 facture of these " artificial mottled " soaps was introduced 
 into England by a German, C. N. Kottula]. To this we 
 need only add — Caveat emptor I 
 
 Special Household and Laundry Soaps.— A few of these, 
 including the commoner kind of scented soaps, will now be 
 consideried. Cheap toilet soaps are thus made on a large 
 scale. For " Honey soap," a good " neat " yellow soap is 
 taken, and an aqueous solution of some yellow dye, such as 
 may be obtained from the dealers in aniline colours, is mixed 
 with it ; 5 per cent, sodium carbonate crystals, or 5 per 
 cent, sodium silicate at 140° Tw. (59^° B.), is then added to 
 stiffen it ; the whole is crutohed, and scented by the addition 
 at as low a temperature as possible of as much citroneUa- 
 oil as is deemed necessary. For " Brown Almond soap," an 
 inferior grade of yellow soap is similarly treated, and 
 scented with about 10 lb. of mirbane (i. e. nitro-benzol) or 
 artificial almond-oil to the ton of soap. When cold, these 
 soaps are cut into bars or cakes, superficially dried, and 
 stamped with one of the foot-power or steam stamping- 
 machines (p. 182). A similar method may be employed for 
 
194 SOAP. 
 
 the incorporation of any cheap scent or colour, or otter 
 desired admixture. The apparatus employed necessarily 
 depends npoii the quantity operated on at one time, and for 
 the choice of this, the hints given on p. 185 are sufficient. 
 
 Disinfectant Soaps. — ^In few ways can disinfectants he so 
 agreeably applied to the skin as when incorporated with 
 soap. One of the last introduced, though probably one of the 
 most efficacious, is thymol soap — ^first made by Ferris & Co., 
 Bristol. Thymol is a non-poisonous crystal (herein differ- 
 ing from carbolic acid), about 8 times as powerful an antiseptic 
 and disinfectant as carbolic acid, and is probably the only 
 substance that combines disinfecting properties with a really 
 pleasant smell, that of thyme. The best mode of incor- 
 porating thymol and phenol (i. e. carbolic acid) with soap is 
 a trade secret; Morfit however, states, that carbolic soaps 
 are best made by his process (p. 150), using as a basis hot- 
 pressed fat-acid cake, on account of the tendency of carbolic 
 acid to soften the soap-paste. 
 
 Carbolic soaps are made in great variety and in large 
 quantities by F. C. Calvert & Co., of Manchester, whose 
 products contain specified definite quantities of carbolic acid 
 of various qualities. Their " medical " soap contains 20 per 
 cent, pure crystallized carbolic acid ; their toilet and house- 
 hold soaps, 10 per cent. ; their domestic soap, 8 per cent. ; 
 and their " No. 5 " or " scouring " soap, 4 per cent, liquid 
 carbolic and cresylic acids. The comparative antiseptic 
 power of soaps may be tested by adding equal weights, in 
 solution, to equal weights of flour-paste, and, after exposing 
 these to the air under identical conditions, noting the day 
 on which mould first appears on each. The so-called 
 " coal-tar " soap or " sapo carbonis detergens," owes its 
 disinfectiijig properties to a small quantity of carbolic acid 
 in the coal tar. 
 
 It may be assumed as a pretty safe working rule, that 
 almost any desired substance, whether soluble' in water or 
 not, can be mixed in this manner with soap, provided that 
 (1) it is not too volatile at the lowest temperature at which 
 
TREATMENT AFTER REMOVAL PROM SOAP-COPPER. 195 
 
 the soap can be maniptdated ; (2) that if insoluble in water 
 or alcohol it is in a state of very fine subdivision ; (3) that 
 it contains neither enough acid to decompose any portion of 
 the soap, nor any mineral bases which would cause double 
 decomposition with the sodium salts of fatty acids. 
 
 Sand Soap. — Under this heading, occur a number of soaps 
 in which it is sought to unite the chemical action of soap 
 with the mechanical aid afforded by sand in scouring. 
 According to 0. Eoth {Seifensieder Zeitung, Nov. 21, 1884), 
 as much as 70 per cent, of clean sand or powdered quartz is 
 sometimes mixed with soap-paste, and experiments showed 
 that such soap had no disagreeable effect on the hands when- 
 used as a detergent. In a similar way, soap is made the 
 vehicle of many substances to be applied to the skin, 
 medicinally or otherwise, or in any cleansing process. All 
 these should be incorporated with "neat" soaps, freshly 
 made or remelted, at as low a temperature as possible. Some 
 form of soap is not unfrequently the basis of polishing 
 pastes. 
 
 Cold-water Soaps. — This term, which has made its appear- 
 ance within the last few years, was at first confined to soaps 
 made from very soft fatty materials, but containing a very 
 small amount of water ; such, for instance, as those produced 
 by Morfit's process. Similar products are also very largely 
 made by artificially depriving " neat soap," fitted in the 
 ordinary way, of about ^ of the 30-32 per cent, of water 
 which it naturally contaips. This is done by exposing it to 
 prolonged fire-heat in a vessel in which it can be thoroughly 
 agitated at the same time; occasionally it is also stiffened 
 by the addition of sodium carbonate or silicate, as described 
 above. These soaps are sold at a low rate, and, from their 
 great dryness, may be kept indefinitely without losing 
 weight, a property possessed by scarcely any other household 
 soap ; being perfectly pure soap, they are truly economical, 
 provided they are not used with hot water. Latterly, 
 however, the use of the term has been appropriated by 
 makers of heavily- watered soaps, which run away in hot 
 
 2 
 
196 SOAP. 
 
 ■water. Hence, in this case also, the consumer should be 
 careful what kind of soap he huys under this name. 
 
 Mantjfactubeks' Soaps. — The various kinds of house- 
 hold soaps haying now been described, a few remarks 
 will be made upon the soda-soaps suitable for various 
 manufacturing purposes. Most of these are dissolved in 
 water for use, and hence it is immaterial into what sized bar 
 they are cut. Care, however, should be taken that they are 
 dissolved ; a case occurred in the writer's knowledge when 
 the quality of a soap was much complained of, as producing 
 greenish stains upon black cloth. The soap-maker asserted 
 .his ignorance of anything deleterious in the soap, and 
 subsequent investigations showed that the cloth-manufac- 
 turer's workman, instead of completely dissolving the soap, 
 had impregnated the cloth with a solution- containing 
 undissolved pieces, and the soda in these, not unnaturally, 
 affected locally the indigo and logwood with which the cloth 
 had been dyed. 
 
 For ordinary scouring purposes, there are few better soaps 
 than the old-fashioned curd-mottled : many others, however, 
 are used, such as curd soaps boiled very dry, made from 
 cheap and inferior greases, cotton-oil foots, &o., and fitte4 
 soaps from greases and black rosin. For scouring goods of 
 finer quality, a white curd soap from tallow, or tallow and 
 lard, with, or without, the addition of a small quantity of 
 coco-nut-oil, is used, or a curd soap from olive- or cotton-seed- 
 oils, or a mixture of both. The soaps made on Morfit's plan 
 (p. 150), are also good scouring soaps. As a rule, traces of 
 unsaponified fat (or indeed any extraneous material) are very 
 deleterious in manufacturers' soaps, which, under ordinary 
 circumstances, should contain a very slight excess (as curd 
 and mottled soaps always do) of caustic soda. When for 
 any purpose, an absolutely neutral soap is required, as e. g. 
 where delicate dyes are employed, either a " finely-fitted " 
 soap should be used, or a curd soap from which the caustic 
 lye has been pumped off, and the soap finished by boiling on 
 brine. (See also Dr. Wright's patent, p. 206). 
 
TREATMENT APTEB EEMOVAL FROM SOAP-COPPER. 197 
 
 According to Crace-Calvert, soaps for dyers' use are not 
 indiscriminately applicable to all colours. To produce the 
 maximum effect in brightening the shade, the soap should 
 have the following composition : — 
 
 Patty acids 
 Soda 
 Water . . 
 
 For Madder 
 Purples. 
 
 64-4: 
 
 5-6 
 
 34-0 
 
 For Madder 
 Pinks. 
 
 59-23 
 
 6' 77 
 
 34-00 
 
 The problems to be dealt with in the use of soap by dyers, 
 however, belong more properly to the technology of that 
 industry, and probably cannot be settled by so elementary 
 an analysis as this.* Such questions may be involved as the 
 proportion of soda to fat acids of a particular molecular 
 weight (vide Chap. VIII.) 
 
 For some purposes, a soap whose solution will remain 
 liquid at a low temperature is required ; such soaps are weU 
 made by Morfit's process, and should contain large quantities 
 of oleic acid. For " fulling," this soap is often employed, 
 mixed with curd soap made from unbleached palm-oil only. 
 
 Much has been written about the frauds practised by 
 unprincipled soap-makers upon manufacturers using soap, 
 and the latter have been advised, in self-defence, to make 
 their own soaps, Eeasons have been given (p. 163) against 
 this course ; it is much to be desired, however, that soap- 
 users would take soap-maite»-fl personally more into their 
 confidence in explaining their requirements, and would 
 themselves superintend (and not leave to their foremen) any 
 experiments made on the working of different kinds of soap. 
 A system, too, on which manufacturers' soaps should be 
 sold, guaranteed to contain a given percentage of fatty 
 
 " The question has recently received much attention in the Dyeing 
 .School attached to the Yorkshire College, Leeds, where the pupils receive 
 special instruction in this subject. 
 
198 
 
 SOAP, 
 
 matter of a definite quality, with its full equivalent of soda, 
 is greatly needed. Such arrangements, if carried out, would 
 very probably put this trade upon a far better footing than 
 it is at present. 
 
 FINE TOILET SOAPS. 
 
 Three distinct processes are in vogue for the fabrication of 
 these, according to the quality of the product desired. For 
 the commoner kinds, the basis is a good grade of fitted 
 yellow soap, taken direct from the copper, or remelted in 
 a small steam-jacketed pan, or in a Whitaker re-melter, 
 provided with continuous coils of steam-pipe. To this, are 
 added (1) suitable colouring matter, in a soluble form if 
 possible, such as some aniline dye, (2) some mineral salts, as 
 sodium or potassium carbonate, salts of tartar, &c. (silicates 
 should be avoided), to stiffen and " close " the soap, usually 
 about 5 per cent, in strong solution, (3) at as low a tempera- 
 ture as possible, the perfume. When cold, the soap is cut 
 up into slabs, bars, and cakes, dried, and stamped, as 
 previously described. A few formulae for perfumes are here 
 given, calculated in each case for 100 lb. soap : — 
 
 Brown Windsor. 
 
 oz. 
 
 Oil of cinnamon 4 
 
 „ cloves 1 
 
 „ caraway 1 
 
 „ sassafras 2 
 
 „ bergamot .. .. .. 2 
 
 Or— 
 
 Oil of bergamot . . . . . . i 
 
 „ caraway 2 
 
 „ cassia 2 
 
 „ lavender 8 
 
 „ cloves 1 
 
 „ petit-grain .. .. 1 
 
 Almond Soap. 
 
 OH of bitter almonds.. .. 12 
 
 „ lemon 4 
 
 Money Soap. 
 
 Oil of oitrouella 8 
 
 „ lemon-grass .. .. 2 
 
 Glycerin Soap. 
 
 Oil of cassia 2 
 
 „ caraway 1 
 
 „ lavender 4 
 
 „ mirbane 1 
 
 In connection with "Brown Windsor" soap, it may be 
 mentioned that the more it is melted, cooled, manipiilated, 
 and remelted, the better it becomes, and that the scraps of 
 
TREATMENT AFTEE REMOVAL FROM SOAP-COPPER. 199 
 
 various sorts of soap that accumulate in the factory are 
 usually worked into this soap. 
 
 The intermediate quality of toilet soap is often made hy 
 the cold process (pp. 144-5), from the purest materials that 
 can be prepared, and when the fatty matter (tallow, lard, &c., 
 with usually a large percentage of coco-nut-oil) and lye have 
 been well stirred together, the colouring matter, perfume, &c., 
 are added, and the whole is left quiet to effect the saponifi- 
 cation. As previously directed, the fat should not exceed 
 120° F. (49° C), and J its weight of caustic soda lye at 
 66^° Tw. (36° B.) should be stirred into it ; in about 5 hours, 
 when saponification occurs, the temperature will rise to 
 180° F. (82-2° C). This method enables more delicate 
 perfumes to be used, since they are added at so low a 
 temperature. A marbled appearance may readily be given 
 to this soap by drawing, in wavy lines, through the mixed 
 fatty matter and lye, a steel blade dipped in colour ground 
 up with oil ; to produce a good effect, the peculiar wrist-turn 
 should be used with the blade, such as is required to wield a 
 fencing-foil well. It is obvious that these soaps retain their 
 own natural glycerin, which is almost their only advantage, 
 for they are exceedingly liable to contain both unsaponified 
 fat, and, what • is far worse, free caustic alkali. This may 
 arise from the saponification process not being complete, or 
 from errors on the part of the workman in adjusting the 
 quantities. Moreover the presence of a large quantity of 
 coco-nut-oU is decidedly objectionable. 
 
 To the perfume formulsB given above, may now be 
 added : — 
 
 Sose Soap. 
 
 ^ oz. 
 
 Oil of rose geranium 4 
 
 „ bergamot 2 
 
 „ rose 1 
 
 ,, cinnamon 1 
 
 Marsh-maUow Soap. 
 
 Oil of lavender 6 
 
 „ lemon-grass 4 
 
 „ peppermint J 
 
 „ petit-grain J 
 
 The finest qualities of toUet soaps, however, require a 
 great deal of manipulation by costly machinery, which has 
 
200 
 
 SOAP. 
 
 Fig. 68. 
 
 been chiefly devised by the French, although the Americans, 
 with their well-known mechanical ingenuity, have recently 
 constructed equally good machines. The basis of these soaps, 
 or "stock" as it is technically termed, is sometimes carefully 
 made by the cold process, from the purest possible tallow, 
 lard, &c., with little if any coco-nut-oil, which, if used, 
 should be the Cochin variety. It is better, however, for 
 reasons above given, to employ a carefully " fitted " soap for 
 " stock " purposes. All the colouring matter, perfjime, and 
 other ingredients, are incorporated with the soap under hy- 
 draulic pressure, at the ordinary atmospheric temperature ; 
 
 hence the most delicate es- 
 sences can be employed, even 
 those that are extracted in 
 the cold from plants. The 
 first operation is to " strip " 
 the stock-soap, i. e. to cut it 
 up into strips or shavings; 
 this may be done with a plane 
 by hand, or by a machine 
 (Fig. 68), whose essential 
 parts are a revolving wheel 
 A, upon which are set 4 or 6 knives, and a hopper F to 
 contain the bars. After stripping, the soap is frequently 
 dried somewhat, and it is then passed through the mill 
 several times, while the colour, perfume, &c., are here 
 added to it. The mill, which is shown in Figs. 69 and 70, 
 consists essentially of 3 cylindrical contiguous rollers B, by 
 whose action the soaps, colour, perfui^, &0i, after repeatedly 
 running through, are blended into a thick homogeneous, 
 paste. When this has been effected, the soap is ready for 
 the final operation, known as " plotting " (from the French, 
 pelotage), in which the paste is subjected to enormous 
 pressure, sometimes 3000-4000 lb. a sq. in., to form it into 
 cakes, or into continuous bars from which cakes may be cut. 
 Such a machine, known as Eutschman's hydraulic soap- 
 
TREATMENT AFTER REMOVAL PROM SOAP-COPPER, 201 
 
 plotting machine, made in Pliiladelpliia, is shown in Tig. 71. 
 It may be charged 5 times in a -working day, and wiU " plot " 
 200 lb. at each operation. It is better to let each separate 
 cake be " plotted " by this machine, bnt if bars are made, 
 and the cakes subsequently stamped, a powerful stamping- 
 press must be employed, such as one of those described and 
 figured on pp. 182-4. Cakes made in this way are not liable 
 to crack in use, as those made by the other 2 processes are ; 
 before being packed, they are not unfrequently dried, and 
 almost always polished. This may be done by hand with a 
 cloth moistened with alcohol, or, according to Dupuis, by 
 
 Fia. 69. 
 
 Fia. 70. 
 
 momentary exposure to a current of steam, which, if desired, 
 may be previously passed through a cloth impregnated with 
 any fragrant odour ; it is said that no other method gives 
 such a beautiful, even, and lustrous coating. 
 
 The whole process of manufacturing toilet soaps by this 
 method was weU illustrated at the International Health 
 Exhibition of 1884, by Messrs. Cleaver, in connection with 
 their Terebene soap. Terebene is a volatile essential oil 
 obtained by acting upon oil of turpentine with sulphuric 
 acid, and then distilling the product; it has a very agree- 
 able smell, not unlike that of thyme. 
 
202 
 
 SOAP. 
 
 A few hints on colour, and formulas for perfume, are here 
 given. Whenever it is desired to produce a mottled or 
 
 S 
 
 marhled appearance in the soap, an insoluWe colour must be 
 employed ; but whenever a uniform tint is required, prefer- 
 ence should be given, whenever possible, to colours soluble 
 
TEEATMENT AFTER REMOVAL FROM SOAP-COPPEE. 203 
 
 in either water or alcohol, a condition fulfilled hy numerous 
 coal-tar colours. Care should be taken to choose those that 
 are permanent, and unaffected by strong alkali. Salts of 
 chromic acid should be avoided, since they are apt to turn 
 green by transference of some of their oxygen to the fatty 
 matter of the soap ; the chromium borate, known as " Guignet's 
 green," is very stable, and so are ultramarine and vermilion. 
 The finest yellow is produced by infusion of saffron ; red palm- 
 oil should be avoided for this purpose, as the soap bleaches 
 by prolonged exposure to light. The resources of the dyer's 
 art are constantly producing new tints, whose properties in 
 relation to soap must be ascertained by that best of all tests, 
 experiment. 
 
 The following recipes for high-class toilet soaps may be 
 found useful ; the quantities are calculated for 100 lb. soap : — 
 
 Violet Soap. 
 
 ^ oz. 
 
 Powdered orris root .. .. 71 J 
 
 Oil of lemon . . . . , . . . 5 
 
 „ rhodium 2§ 
 
 „ thyme 2| 
 
 Tincture of musk 5 
 
 Oil of orange peel 8J 
 
 „ cinnamon I 
 
 „ thyme 2 
 
 Lemon 8oa/p. 
 
 Oil of lemon 8J 
 
 „ bergamot 4 
 
 „ lemon-grass .. .. 4 J 
 
 „ cloves 2 
 
 Elder-flower Soap, 
 
 OU of bergamot 
 „ lavender 
 „ thyme , . 
 „ cloves .. 
 „ cassia . . 
 „ almonds 
 
 MiUefleur Soap. 
 
 Oil of orange (Portugal) .. lOJ 
 
 „ lavender 5 
 
 „ cloves 2 J 
 
 „ nutmegs 5 
 
 Tincture of musk 5 
 
 N.B. Impregnate the fats used in 
 this, vrith vanilla, ambergris, and 
 rose-leaf. 
 
 Finest Honey Soap. 
 
 Oil of oitronella 8 
 
 „ lemon-grass 4 
 
 „ cassia 2 
 
 Bose Soap. 
 
 Oil of rose 2J 
 
 „ rose-geranium .. .. 2| 
 
 „ cinnamon 1 
 
 „ bergamot IJ 
 
 Tincture of ambergris .. .. | 
 
 Glycerin Soap, 
 
 I. OU of lavender 4 
 
 „ bergamot .. .. 2i 
 
 „ thyme li 
 
 „ cloves 1 
 
 „ caraway | 
 
 II. Oil of rosemary . . . . 6 
 
 „ orange 3 
 
 „ cassia 1 
 
 „ thyme 1 
 
 „ mirbane 1 
 
204 SOAP. 
 
 Transparent Soaps. — The peculiar appearance of these soaps 
 is due to the use of alcohol in their fabrication, and it may be 
 applied in 2 ways. Pure soaps, i. e. the soda compounds of 
 the fatty acids, are soluble in alcohol, whereas the saline and 
 other impurities which accompany even the best manufactured 
 soaps to a small extent, are for the most part insoluble. The 
 soaps are well dried, and then dissolved in strong alcohol ; as 
 the insoluble impurities fall to the bottom, they can readily 
 be separated from the alcoholic solution by subsidence. The 
 latter is then placed in a distillation apparatus, and the alco- 
 hol is distilled oflF, condensed, and recovered for use in the 
 next operation ; the soap, still hot, is left behind as a treacly 
 mass, which cools to a semi-transparent solid. The hot soap 
 is poured into moulds and allowed to cool ; it is then set 
 aside for some months, during which it is exposed to a tempe- 
 rature of 95° P. (35° 0.). By this treatment it passes from the 
 muddy, semi-opaque condition to one of perfect transparency, 
 and is then stamped, polished, and sent into the markets. 
 This is the process by which the famous Pears' soap is 
 manufactured. 
 
 Inferior transparent soaps, however, are usually made by 
 the cold process, but to ensure success, very great exactitude 
 in the proportions of the materials used is necessary, as well 
 as much experience and skill. The fatty matters employed 
 are tallow, coco-nut-oil, lard, castor-oil, and olive-oil, in varying 
 proportions, but all of the purest quality. For 100 parts by 
 weight of fatty matter, 45 parts caustic soda lye at 76^° Tw. 
 (40° B.), and 50-55 parts of alcohol of 95° should be used. 
 One half the lye should be stirred into the melted fat, the 
 temperature of the mixture not exceeding 120° F. (49° C), 
 and, when thoroughly incorporated, the remainder of the lye, 
 mixed with the alcohol, should be added ; saponification will 
 take place rapidly, and the perfume should now be added, 
 and the whole cooled very gradually in frames ; 20 parts 
 glycerin added to the above will make a good transparent 
 glycerin-soap ; occasionally some clear syrup of white sugar 
 is added also. These soaps are seldom coloured, but any 
 
TREATMENT AFTEK REMOVAL FROM SOAP-COPPEB. 205 
 
 colour used in tliem should be quite transparent ; it will be 
 noticed that they do not become quite transparent until they 
 have been exposed to the air for some days. The following 
 is an analysis of one of these products, where a serious defect 
 of this method, the presence of free caustic alkali, is evident. 
 
 Fatty acids 49-31 
 
 Combined alkali 6'37 
 
 TJncombined alkali 1-80 
 
 Water ' 22-40 
 
 Sugar, Glycerin, &o 19-40 
 
 99-28 
 
 Solidified Glycerin. — The preparation of this by Price's 
 Candle Co. is a trade secret, but Morfit recommends the 
 following method. Heat to 310° P. (154^° C.) a mixture of 
 350 lb. hot-preesed fatty acids, 150 lb. white oleic acid, 200 lb. 
 best rosin. To this, add 135 lb. Jarrow 52° ash (p. 147) in 
 25 gal. boiling water. When the soap-paste is quite homo- 
 geineous, which should be in about an hour, add 250 lb. pure 
 glycerin, and stir well. If a sample be not transparent when 
 cold, add glycerin untU this is the case, controlling the 
 amount of glycerin by testing 2 lb. samples of the soap with 
 glycerin over a gas flame. This soap has the following com- 
 position : — Patty acids, 34 'O; rosin, 13-0; soda, 4'6; 
 water, 15'4; glycerin, 33-0. 
 
 Since it is beyond the scope of this work to devote more 
 space to the detail of this part of the subject,* it may be 
 mentioned briefly that the various shaving - soaps and 
 creams are wholly or in great part potash-soaps ; that soap- 
 essences are usually alcoholic solutions of soft-soap; that 
 opodeldoc is a solution of soap in enough alcohol to make a 
 jelly when cold ; that " floating " soaps are made by dissolving 
 soaps in a small quantity of water, and agitating the solu- 
 
 * The Cantor lectures on "The Manufacture of Toilet Soap," to be 
 delivered in May, 1885, by Dr. C. E. A. Wright, F.E.S., and to be subse- 
 quently published in the ' Journal of the Society of Arts,' will contain 
 valuable information on the manufacture and the analysis of soap. 
 
206 SOAP. 
 
 tion violently in contact with air ; and that powdered soaps 
 are made from any pure soap, cut into shavings, thoroughly 
 dried, and then ground to fine powder and sifted. It may 
 also he well to call attention to the fact that nearly aU the 
 so-called washing-powders, soap-powders, and essences of soap, 
 frequently contain no soap at aU, and are merely mixtures of 
 soda-ash, common salt, and sodium sulphate, with occasionally 
 a trace of dry powdered soap. 
 
 Addendvm, referred to on p. 196. 
 
 A very ingenious mode of making soaps of any kind abso- 
 lutely neutral has lately (Jan. 12, 1885) been patented 
 (No. 14,681) by Dr. C. E. Alder Wright. Some salt of 
 ammonia, such as ammonium sulphate or chloride, is mixed 
 up with the soap paste while hot. The caustic soda present 
 turns out the ammonia (producing sodium sulphate or 
 chloride), and much of the ammonia is volatilized at once 
 by the heat of the mass, while the remainder escapes after 
 the soap has been cut up and exposed to the air for some 
 days. 
 
( 207 ) 
 
 CHAPTER VIII.' 
 
 THEOEY OP THE ACTION OF SOAP,— ITS VALUA- 
 TION AND ANALYSIS. Disteibution and Positiok of 
 THE Trade. 
 
 ACTION OF SOAP. 
 
 The mode in which soap facilitates the removal of dirt is 
 by no means clearly understood, and prohahly depends upon 
 a variety of causes, partly physical, partly chemical. Un- 
 questionably much of its power is due to the alkali it contains, 
 which unites with and renders soluble the grease that forms 
 so large a portion of much of our dirt ; but it can hardly be 
 true, as is maintained by some, that the value of a soap de- 
 pends solely upon its percentage of alkali, since, if that were so, 
 solutions of sodium silicate, carbonate, or aluminate, contain- 
 ing the same percentage of soda as soap, ought to do as much 
 work, which is notoriously not the case. Further, since the 
 proportion of alkali in a soap varies inversely as the equiva- 
 lent weight of its fatty acids, those soaps with fatty acids of 
 the smallest equivalent weights (e. g. coco-nut-oil) ought to 
 be the most advantageous. Grager, who advocates this view, 
 gives the following table of anhydrous soaps. 
 
 Oleic acid soap . 
 Palm-oil Boap 
 Tallow soap . . 
 Coco-nut-oil soap 
 
 Equiv. Weight. 
 
 3800-95 
 3558-85 
 3300-95 
 3065-45 
 
 Quantity of Boap 
 
 necessary to do the 
 
 same work as 100 
 
 tallow soap. 
 
 115-1 
 
 108-7 
 
 100-0 
 
 92-8 
 
208 SOAP. 
 
 Gold water is never in contact with an alkaline stearate or 
 oleate (the soap of commerce therefore) without decomposing 
 it ; the neutral salt is resolved into alkali, which dissolves, 
 and an acid salt, which is precipitated as insoluble. Hence 
 soap even in the purest cold water produces turhidity, 
 although, when treated with warm water, it dissolves entirely. 
 The alkali thus liberated acts upon the acid substances present 
 in the surface which is being washed, and removes them in 
 the form of emulsions or soluble compounds. But, it may 
 be asked, does the fatty acid contribute directly to the de- 
 tergent action of soaps ? The question is thus answered 
 by Mr. C. F. Cross, ' in his lecture on Soap at the Health 
 Exhibition, previously quoted : — 
 
 " We have seen that the property of being slowly decom- 
 posed by water ensures in the use of soda soaps a gradual 
 supply of free alkali, and this supply being obviously regu- 
 lated by the combination of the alkali with the fatty acid, we 
 recognise herein an important indirect influence of the fatty 
 acid upon the cleansing action of soaps. It is also evident 
 that the fatty acids, which are continuously liberated from 
 their combination with the alkali, will be brought into 
 contact with the substance undergoing the cleansing opera- 
 tion ; indeed when they are of an acid nature — and, in most 
 cases, surfaces exposed to the air are more or less acid 
 —the fatty acid wiU be liberated upon the surface as the 
 result of the union between the alkali and the acids in 
 question. The fatty acids brought into contact with the sur- 
 faces of organic substances will tend to render them soft 
 and smooth, and thus to lessen their adhesive attraction for 
 foreign substances. Still this is rather an indirect effect, 
 and the alkali would appear to be the sole effective agent 
 in the cleansing work. But there remains to consider 
 that property which is directly the result of the presence 
 of the fatty acid in combination with the alkali, viz. the 
 lathering of soap solutions. To understand the import of this 
 property we may consider its most interesting demonstration; 
 which is afforded in the soap-bubble. It is only of late years 
 
THEOEY OF ITS ACTION. 209 
 
 that the sublime and the trivial have found a meeting-place 
 in this curious phenomenon. That which was one of the 
 delights of our childhood — which to the poet became the 
 type of the evanescent, — to the material philosopher affords 
 food for solid reflection, and has been made the subject of 
 recondite discussions.* The course of blowing a soap-bubble 
 is a greater and greater attenuation of a soapy film, and 
 the limit of this attenuation, i. e. the size of the bubble, is 
 determined by the strength of the film, which is, in its turn, 
 determined by the cohesion of the ultimate particles of soap. 
 Now this cohesion, brought to demonstration by means of 
 the bubble, upon an isolated portion of the liquid, is clearly 
 a property of the solution itself, and must exert an import- 
 ant influence in overcoming the adhesion of foreign matters 
 to surfaces." 
 
 Considerable light has been thrown upon the manner of 
 removal of dirt by soap, by the researches upon Pedesis of 
 the late Prof. W. Stanley Jevons, F.E.S., who has given 
 this name to a microscopic phenomenon long known as the 
 " Brownian movement " of small particles. When clay is 
 stirred up with water, and the whole is allowed to stand, the 
 water clears itself very slowly, and microscopic examination 
 shows that this is due to a kind of molecular movement 
 of infinitesimally small particles of the clay. To this- 
 movement. Prof. Jevons gave the name Pedetic action (vide 
 ' Quarterly Journal of Science ' for April, 1878, No. LVIII.), 
 and he found that it was largely influenced by the addition of 
 certain substances to the water containing clay in suspension. 
 Soap and sodium silicate enormously increase this Pedetie 
 action, or movement of the particles (Keport of the British 
 Association for the Advancement of Science, 1878, p. 435), 
 and from observations made by Prof. Jevons, and by the 
 present writer (who hopes to extend his researches in this 
 direction), it seems clear that the action of such substances 
 
 * "See the Presidential Address of Lord Eayleigh at the British 
 Association, 1881. Also the lecture of Prof. Backer, at the Boyal 
 Institution, London, March 20, 1885." 
 
 P 
 
210 SOAP. 
 
 in promotiug this movement of extremely minute particles, 
 is an important factor in the cleansing power of soap. 
 
 When soap is rubbed in use against the surface to be cleansed, 
 it is obvious that its consistency is an important consideration, 
 since a harder soap requires much labour to detach a sufS- 
 cient quantity, while a softer soap rubs away rapidly. It 
 has been already shown that, ceteris paribus, the softness of 
 a soap depends upon how much potash it contains ; but where 
 soda only is the base, the question of the comparative 
 solubilities of the soda salts of the fatty acids has to be 
 considered. WhUe sodium oleate is freely soluble in 10 
 parts of water, sodium stearate is scarcely affected thereby ; 
 or in other words, the salts of oleic acid are far more soluble 
 than those of stearic. Hence the hardness of a soap depends, 
 not merely upon the base used, but upon the relative quanti- 
 ties of stearic and oleic acids in its composition ; this point 
 will be again referred to in the analysis of soaps. Moreover, 
 the quantity of water contained by a soap influences very 
 materially, not merely its hardness, but its rate of solubility 
 in water, and especially in warm water. The quantity of 
 water in normal, "neat," or genuine, soaps, varies from 16 
 to 35 per cent., according to their kind. Curd soaps, and 
 the old-fashioned mottled soaps (p. 170), are, however, almost 
 the only household soaps occurring in commerce, in which 
 the normal amount of water has not been increased by the 
 addition of some weak saline solution (p. 188). In low-priced 
 coco-nut-oil soaps the addition of water is carried to am 
 enortoous extent ; the writer has repeatedly seen a good- 
 looking hard white or yellow soap, which contained 70 per 
 cent, of water. 
 
 The impurity of the water employed in washing with soap 
 has a material influence upon its consumption. Eain-water, 
 and next to it, river or lake-water, is the best, while spring- 
 water should be avoided if possible ; all such water is more 
 or less " hard," owing to the presence in it of salts of lime 
 (chiefly the carbonate and sulphate), some of which may be 
 removed by boiling, or, more completely, by the addition of 
 
THEORY OF ITS ACTION. 211 
 
 Boditim carbonate. When a soluUe potash- or soda-soap comes 
 into contact with lime salts in solution, mutual decomposition 
 occurs, resulting in the formation of insoluble lime-soaps, 
 which have no detergent action. Until all the lime has 
 been thus removed, the soda-soap refuses to cleanse, and 
 hence much of it is wasted. It is obvious also that the 
 presence of any acid in the water, or on the surfaces to be 
 cleansed, will decompose soap, uniting with its alkali, and 
 destroying its detergent power. When nothing but hard 
 water can be procured, or when much grease has to be 
 removed, no soap will be found so economical as the old- 
 fashioned curd-mottled, entangled in the interstices of which 
 are appreciable quantities of caustic soda lye. Since the 
 hardness of water is for the most part caused by the presence 
 of salts of magnesia and lime, the laboratory test of the hard- 
 ness of water will need but little explanation. The reagent 
 employed is a solution of 10 grm. of a pure fatty acid soap 
 (Castile soap is recommended) in 1 litre of weak alcohol. 
 This is checked and standardized by a solution of known 
 strength of a pure lime salt. The operation consists in 
 gradually adding the soap solution to the hard water, 
 shaking after each addition, until a permanent lather is 
 formed. From the volume of soap solution used, the degree 
 of hardness may be calculated.* The number of " degrees of 
 hardness " indicates that the water contains soap-destroying 
 salts approximately equivalent to that number of gr. of 
 calcium carbonate per gal. of the water. The water-supply 
 of London is derived almost entirely from the rivers Thames 
 and Lea, and its average hardness is 15°. This represents 
 a destruction of soap equal to about 2 lb. for every 100 gal. 
 of such water used for laundry purposes. 
 
 In many cases, some of the lime salts are kept in solution 
 in water by the carbonic acid which all natural waters con- 
 tain. When such water is heated, the carbonic acid is 
 
 * The lathering-point may be very accurately determined by a piece of 
 apparatus introduced by Gr. Loges (Ghem. Zeit., 1884, p. 69) and figured 
 in Jour. Soo. Ohem. lad., iii. (1884), p. 652. 
 
 p 2 
 
212 , SOAP. 
 
 expelled, and the lime salts are deposited in an insoluble 
 form, snoh as the " furring " in a tea-kettle or boiler ; this 
 is why boiling lessens the hardness of water. The hardness 
 is conveniently reduced on a small scale by the addition of 
 sodium carbonate, or washing soda ; on a large scale, some 
 form of Clark's process may be adopted with advantage.* 
 
 There are few things which are so ill understood in 
 practical life as the real value, or, what is the same thing, 
 the proper price, of soap. From what has been said, it 
 appears certain that the real value depends upon the amount 
 of dry (anhydrous) soap present, and upon the proportion 
 of stearic and palmitic acids to oleic, and of these 
 three to that of the cocinic, laurosteario, &c. In other 
 words, the determination of the following elements is neces- 
 sary to arrive at an estimate of the value of a soap : — 
 (1) The percentage of water; (2) the percentage of soda 
 available for detergent purposes, (a) combined with the 
 fatty acids, (6) as caustic, carbonate, silicate, or aluminate ; 
 (3) the percentage of fatty acids ; (4) the melting, or rather 
 the solidifying-point (p. 96) of those fatty acids. To these 
 may well be added a fifth, viz. some notion of the probable 
 source whence they were derived, or some tests by which 
 the more characteristic of them may be recognized ; some 
 hints in this direction will be found in Chap. IV. 
 
 It would be very greatly to the advantage of all large 
 consumers of soap, as well as to soap-manufacturers them- 
 selves, if soaps were to be sold, guaranteed to contain so 
 much per cent, of fatty matter of a given melting-point, 
 combined with the full quantity of soda necessary for its 
 complete saponification, just as many other commercial 
 products are sold at a price varying with the "test" of 
 the quantity of the valuable constituent. It cannot be too 
 widely known among consumers of all classes that those 
 soaps are the most truly economical in which the percen- 
 tage of water is lowest ; but, on the other hand, it is unfor- 
 
 * ' Journal of the Society of Chemical Industry,' Feb. 29, 1884. 
 
VALUATION AND ANALYSIS. 213 
 
 tunately too often considered by the seller to be for his 
 (immediate) interest to sell a soap which contains as large 
 a quantity of water as can be incorporated therein, consis- 
 tently with the " saleable " character of the soap. What 
 will " sell," not what wiU " wash " (in the metaphorical as 
 well as in the literal sense of that word), is unfortunately 
 the criterion too often adopted in the soap-trade as in others. 
 On this question of the ethics of the trade, we may quote 
 again from Mr. Cross's lecture at the International Health 
 Exhibition of 1884,— 
 
 " The love of gain when indulged at the expense of others, 
 is a vice which leads men to forsake art, and take to artifice. 
 In soap-making it takes this form of perverting ingenuity 
 to the production of highly 'watered' soaps,* the artifice 
 consisting in keeping up the appearances of the soap in 
 opposition to the influence of the water, Tsrhich is in the 
 direction of causing diminished hardness and loss of the 
 ' graining ' or ' strike ' peculiar to normal soaps. ... It 
 is scarcely necessary to point out that the severe test of the 
 wash-tub soon reveals the true character of these fraudulent 
 soaps, their lack of the genuine substance causing them to 
 ' waste.' In view of these facts, of which some of my 
 audience will probably have been in ignorance, there should 
 be no excuse for continuing to pay for water at the rate of a 
 penny a pound or more." 
 
 In concluding these remarks upon this very important 
 constituent of commercial soaps, and upon one of the un- 
 happy results of keen competition, it may be well to point 
 out, — Firstly, that in the case of the larger English firms, 
 the manufacturers' price for a soap depends entirely upon 
 the percentage of fatty acids, and the kind of fats employed 
 to produce them ; Secondly, that fraud consists in inducing 
 a purchaser to believe that a given soap is more nearly 
 a " neat " or genuine soap than it really is (p. 183) ; and 
 
 * " The practice of watering soaps has led to a saying amongst 
 manufacturers, ' He makes his fortune who makes water to stand 
 upright.' " 
 
214 SOAP. 
 
 Thirdly, that muoli of the evil complained of is due to the 
 want of knowledge among purchasing consumers, who fre- 
 quently insist on some (adulterated) article being sold to 
 them retail at actually a less price than the genuine article 
 would fetch in the wholesale market.* It follows, there- 
 fore, that it is very much in the power of consumers to 
 assist the manufacturers in this important question, the 
 incidence of which upon their consciences is often a heavy 
 burden. Again we repeat, Caveat emptor ! 
 
 VALUATION AND ANALYSIS OF SOAP. 
 
 Brief instructions will now be given for the most suitable 
 methods, consistent with accuracy, for the analysis of soap ; 
 for fuller information, manuals of technical and of general 
 chemical analysis should be consulted.| 
 
 Uniformity of' Sample. — Great care should be taken to 
 ensure this ; singe soap loses water rapidly on exposure, 
 the soap should be sliced up in thin pieces, well shaken, 
 and kept in a well-stoppered bottle. Other convenient 
 plans are (1) to weigh out at once, while the soap is fresh, 
 all portions required for analysis, (2) to make a standard 
 solution of the soap, say 100 grm. in 1 lit., and measure 
 off what is required, taking care to avoid loss by evapora- 
 tion. In analyzing case-hardened soaps (p. 179), care must 
 be taken to see that the section of the bar includes a 
 proper proportion of skin ; sometimes separate analyses 
 have to be made of different parts of a bar of these soaps. 
 
 Percentage of Water. — About 2 grm. of the soap is exposed 
 in a wide-mouthed flask of about 100 c.c. capacity, to a 
 temperature not exceeding 300° P. (149° C), in an air- or 
 oil-bath for 1 hour, and the loss in weight is noted. The 
 flask should be weighed as soon as it is cool, and, where 
 
 * A very good instance of this is afforded by cocoa. A mixture of 
 cocoa, sugar, starch, &c., is sold by retail grocers at a much lower figure 
 than the wholesale price of even low qualities of pure cocoa. 
 
 + Allen's ' Commercial Organic Analysis,' is one of the best books of its 
 class. 
 
VALUATION AND ANALYSIS. 215 
 
 great accuracy is required, should he cooled tinder a bell- 
 glass in presence of strong oil of vitriol, as anliydroTis 
 soap is very hygroscopic. The time required for the opera- 
 tion may be shortened by ^, if a few drops of alcohol be 
 added as soon as the soap has melted; the addition of 
 a known weight of fine dry sand prevents the soap from 
 swelling up too much. No well-made soap should turn 
 brown or be discoloured at this temperature. 
 
 Percentage of Soda (or Potash). — A burette is provided, 
 divided into fifths of a c.c, and a standard solution of 
 acid, such as is directed in works on alkalimetry; either 
 sulphuric or oxalic acid may be used. To determine the 
 total percentage of soda present, dissolve -5 grm. of the soap 
 in boiling water, and add to it the standard acid solution, 
 stirring and boiling the whole time, until a permanent 
 froth is no longer visible ; from the number of c.c. of acid 
 used, the amount of soda is readily calculated. Instead of 
 the disappearance of froth, one of the numerous " indicators " 
 may be used, as litmus, turmeric, eosin, &c. Another modifica- 
 tion of the test is to add a decided excess of standard acid, boil 
 the whole, and titrate back with a standard alkaline solution. 
 
 The amount of alkali combined with the fatty acids is 
 probably most accurately determined thus. Dissolve the 
 soap in alcohol ; pass a current of carbonic acid gas through 
 the solution, to precipitate as carbonate any caustic alkali 
 present, filter off all insoluble matters, and determine the 
 alkali in the filtrate. A simpler but less accurate method is 
 to dissolve the soap in water, precipitate it thence by salt 
 (repeating the operation a second time, to wash out all traces 
 of uncombined alkali), and determine the alkali (A) in the 
 soap only, (B) in the brine solution ; A -|- B should of course 
 be equal to the total percentage described above, while B 
 alone gives the alkali present as free caustic, carbonate, 
 silicate, borate, aluminate, &c. Errors, however, may arise 
 from two sources :— (a) the impurities in the salts employed 
 react on the soap ; (6) partial decomposition of the soap by 
 solution in water and re-precipitation. 
 
216 SOAP. 
 
 If the alkali present be entirely potash, or entirely soda, 
 the Tolumetrio methods can be relied on ; but if both are 
 present, their proportions may be ascertained (1) by con- 
 verting all the alkali present into oxalate, then evaporating 
 to dryness and igniting the residue, which yields a mixture 
 of carbonates in which the relative amouats of potash and 
 soda may be determined by the principles of indirect 
 analysis; (2) by the direct determination of the potash 
 with platinum tetrachloride. 
 
 Alkaline Salts. — The determination of soluble silica and 
 alumina (as sodium silicate and aluminate), of sulphuric 
 acid (as sodium sulphate), of chlorine (as common salt), and 
 of other mineral constituents of soap, must be made in the 
 acid solution that remains after decomposing the soap with 
 a suitable mineral acid ; for example, for sodium chloride, 
 decompose with nitric acid, and titrate with silver nitrate — 
 for silica, alumina, and sulphuric acid, decompose with 
 hydrochloric acid, evaporate to dryness, filter oif and weigh 
 the insoluble silica, and determine the alumina, and the sul- 
 phuric acid by barium chloride, in the filtrate, by the usual 
 methods. The most difScult problem is the carbonic acid, 
 which is usually only present in very small quantity. It 
 must be estimated gravimetrically (p. 129), and this may be 
 done in the insoluble residue obtained by dissolving the soap 
 in alcohol, or by operating in a somewhat larger apparatus 
 (to give room for the solution of the soap, which must be 
 aqueous) on about 10 or 15 grm. of the soap itself. 
 
 Substances Insoluble in Water. — In a properly-made un- 
 adulterated soap, these should only consist of colouring 
 matters and mottling, and should never exceed 1 per cent. 
 To estimate their amount, dissolve a known weight in water, 
 decant the clear liquid, collect the deposit on a tared filter, 
 wash, dry, and weigh. Organic impurities may be estimated 
 by igniting this residue, and weighing again, when only 
 mineral impurities remain. Starch or farina is detected by 
 iodine ; mineral impurities, by the , ordinary methods o 
 
VALUATION AND ANALYSIS. 217 
 
 mineral analysis. Steatite, a silicate of magnesia and 
 alumina, is an occasional constituent of low-class soaps. 
 
 Glycerin. — A weighed portion of the soap is dissolved in 
 water, and decomposed with slight excess of sulphuric acid ; 
 the fatty acids are removed, and the acidulated solution is 
 evaporated to dryness, dried at 230° F, (110° C), and treated 
 with absolute alcohol ; the alcoholic solution of glycerin is 
 separated by filtration into a tared flask, from which the 
 alcohol itself is distilled ofif. The result is invariably too 
 low, owing to the volatility of glycerin in presence of 
 warm aqueous vapour. A volumetric method has been de- 
 scribed by Dr. Muter * for the indirect estimation of glycerin 
 in soap, and in the lye resulting from the saponification of 
 fats. It is based on the assumption that the solvent action 
 of a solution of potash on cupric hydrate is directly 
 proportional to the amount of glycerin in the liquid. 
 
 Carbolic acid, &c. — Mr. 0. Lowe recommends the following 
 process. Take 50 grain-measures of aqueous solution of 
 caustic soda at 69° Tw. (37° B.), dilute to 1000 gr.-m. ; in 
 this, dissolve by heat 100 gr. of the soap, then add 1000 
 gr.-m. saturated solution of common salt. Filter oflF, and 
 wash with brine, the soap thus precipitated ; slightly acidify 
 the filtrate and washings with hydrochloric acid, and add 
 thereto enough bromine-water to make the Kquid perma- 
 nently yellow. Warm the liquid till the precipitate melts, 
 then let it cool ; remove, carefully dry, and weigh the 
 resulting mass, of which, 331 parts correspond to 94 parts of 
 carbolic acid. If the inferior qualities of carbolic acid have 
 been used, the precipitate, which is tribromocresol, CgHgBrjO, 
 forms a sticky mass, owing to the liquid nature of the 
 cresylic acid it contains. For the determination of the 
 various constituents of toilet and medicated soaps, such as 
 thymol soap, terebene soap, &o., the literature of the tech- 
 nology of those substances should be consulted. 
 
 * • Analyst,' vi. 41. 
 
218 SOAP. 
 
 Unsaponified fat. Hydrocarbon oils, dc. — These are best 
 determined by agitating an aqueous solution of tbe soap 
 ■with ether, which dissolves them all, and then treating the 
 mixture in a separator as described on p. 92. When the 
 ether has been distilled off, and the total constituents of this 
 class weighed, the detection and estimation of them separately 
 may be carried out as described on pp. 98-li05. 
 
 Percentage and Examination of Fatty Acids. — A known 
 weight of the soap (10 or 20 grm., if only the percentage is 
 required, 50 or 100 grm. if the nature of the fat is to be 
 ascertained) is dissolved in hot water. If any portion 
 refuses to dissolve, as will be the case if steatite, clay, or 
 starch have been mixed with the soap, the solution must 
 be filtered, either in a hot closet, or through a funnel sur- 
 rounded by hot water ; if the filter be previously weighed, 
 the insoluble portion can be weighed upon it after being 
 washed and dried at or above 212° F. (100° C.) ; to the clear 
 soap solution, an excess of sulphuric or hydrochloric acid Is 
 added, and the whole is gently boiled until the fatty acids 
 are clear and transparent, and all clots have disappeared. 
 If there is reason to believe that the fatty acids will be fluid, 
 or even soft, and greasy, at the ordinary temperature, and a 
 fat percentage only is desired, a weighed quantity of white 
 wax or stearic acid, previously deprived of water (see p. 84), 
 should be added at this stage. When the cake of fatty acids 
 is cold, the liquid beneath should be removed, and the cake 
 remelted oyer fresh hot water, to remove all traces of salts 
 and acids. When cold, it may be partially dried with damp 
 blotting-paper, if it is solid enough not to give up any oleic 
 acid to that absorbent ; it should then be all carefully trans- 
 ferred to a tared capsule, gradually heated to (but not kept 
 at) at least 260° F. (127° C), to expel the last traces of 
 mechanically mixed water, and theji weighed, the weight of 
 wax or stearic acid added being of course deducted. Every 
 100 parts of fatty acids so obtained represent 105-106 parts 
 of pure neutral fat used to make the soap. In this condition, 
 the fatty acids are hydrates, and from every 100 parts, 3" 5 
 
VALUATION AND ANALYSIS. 219 
 
 parts must be deducted in stating the analytical results for 
 water chemically combined with them, because anhydrous 
 soap [dried at 300° P. (149° C.)] does not contain these 
 elements of water. 
 
 Another method, which is especially applicable where the 
 fatty acids will not solidify at the ordinary temperature, and 
 it is also desired to examine their nature, is to decompose 
 the soap in a separator (p. 92) and agitate the liquid with 
 petroleum spirit. When the aqueous liquid has been run 
 off, and all traces of the petroleum solution have been 
 transferred to a tared flask, the spirit is distilled off, and 
 the fatty acids are dried and weighed. 
 
 Both these methods assume the complete insolubility of the 
 fatty acids in water. For practical purposes, this assump- 
 tion is sufficiently correct, except in the case of coco-nut- 
 and palm-nut oils, and butter. Various complicated methods 
 have been described for estimating these soluble fatty acids, 
 useful in the hands of skilled analysts, but unreliable in 
 inexperienced hands. The best plan for a soap-maker is to 
 operate in the same vessels which he habitually uses for 
 fatty acid estimations, and in them to make a blank ex- 
 periment with a suitable weight of pure (say) coco-nut oil, 
 saponifying it, decomposing the soap, and weighing the fatty 
 acids resulting therefrom. Probably 100 parts of oil will 
 give him about 93 parts of fatty acid. Using these data, the 
 quantity of coco-nut oil used to make a given soap (which 
 is what the soap-maker wants to know) can be readily 
 calculated from the percentage of fatty acids obtained from 
 it by analysis. The same proceeding applies, mutatis 
 mutandis, to any fat. 
 
 To ascertain the nature of the fatty acids, the melting-, or 
 Bolidifying-point of the mixture should first be taken by one 
 of the methods given on p. 97. Where the presence of 
 coco-nut- or palm-nut oil is suspected, the question may be 
 determined, and their quantity estimated with a close 
 . approach to accuracy, by the test described on p. 101. In 
 any case, and more especially after the record of many such 
 
220 SOAP. 
 
 data, the determination of their specific gravity (p. 93), 
 will afford much useful material for judgment as to the 
 nature of the fatty acids, and it is especially valuable in the 
 estimation of the amount of rosin present. 
 
 Another mode of attacking the same problem (proposed 
 by Dalican but due originally to P. Jean) is here given, 
 with the remark that Sutherland's process, by which the 
 rosin is oxidized by nitric acid, and Eampal's process, in which 
 the rosin is precipitated in a finely-divided state by throwing 
 an alcoholic solution of the fatty acids into water, are both 
 unreliable. Dissolve 10 grm. of the soap in 100 grm. water, 
 add enough concentrated soda lye to precipitate the soap; 
 some resinates remain in the liquor, which is neutralized, 
 evaporated to dryness, and the rosin is extracted with alcohol 
 which may be distilled off, and the rosin weighed (A). Then 
 dissolve the precipitated soap in water, and add excess of 
 barium chloride ; collect and dry this baryta soap, and ex- 
 tract it with ether, which dissolves out only the resinates ; 
 evaporate off the ether, and treat the resinates with boiling 
 water and sulphuric acid, which sets the rosin free ; it may 
 then, if necessary, be similarly dissolved out by alcohol, or 
 may be merely collected on a weighed filter, and its weight 
 (B) noted ; A + B is the weight of rosin in the soap. The 
 portion insoluble in ether may then be suspended in water, 
 decomposed with sulphuric acid, and the fatty acids 
 collected, dried, and weighed. Another tolerably simple 
 process has been devised by Barfoed, with which some 
 analysts have obtained very encouraging results.* 
 
 The method, however, which will probably supersede all 
 others, is that described by Mr. T. S. Gladding in the Chemical 
 News for April 14, 1882. About • 5 grm. of the mixture of 
 fatty acids and resin is dissolved in 20 c.c. of 95 per cent, 
 alcohol, and thoroughly saponified with a slight excess of 
 alcoholic potash. The solution is then mixed with enough 
 ether to make it up to 100 c.c, and to it is added 1 grm. of 
 
 * Vide Joum. Chem. Soc, xxix. 773, and Zeit. Anal. Chem., xiv. 20. 
 
VALUATION AND ANAXTSIS. 
 
 221 
 
 very finely powdered neutral silver nitrate, the wtole being 
 well shaken for 10 minutes. After the precipitate has sub- 
 sided, an aliquot part of the solution is measured off, and 
 decomposed with dilute hydrochloric acid (1:2); an aliquot 
 part of the same ethereous solution remaining after this treat- 
 ment, is evaporated in a tared dish, and weighed as rosin, a 
 small deduction (0-00235 grm. for 10 c.c.) being made for oleic 
 acid. 
 
 Shorter, but less reliable, methods than the above have 
 frequently been proposed for determining the value of soap. 
 To shorten the operation of weighing the fatty acids, many 
 methods have been tried for measuring them, by collecting 
 them in a long-necked flask, graduated, or in a graduated 
 tube attached thereto. Whenever this is done, the weight 
 can only be arrived at from the estimated sp. gr. of the fatty 
 acids, and as this is very variable, the method is at best an 
 approximate one, though useful in the factory when that 
 sp. gr. is known, Buchner decomposes 16 '66 grm., and 
 measures the fatty acids to the ^ c.e., multiplying by 0-93 to 
 get the weight in grm. He also gives the following useful 
 table, on the basis that 100 lb. fat produce 155 lb. soap and 
 about 6 ■ 25 lb. glycerin ; the 3 last columns are of general 
 
 Wn of c c of 
 
 
 
 
 " Neat " or 
 
 100 parts of 
 
 100 parts of 
 
 fatty acids 
 from 16§ 
 
 Sp. gr. of 
 fatty adds. 
 
 Mean weight 
 of the fatty 
 acids mgrm. 
 
 Fat used for 
 100 lb. soap. 
 
 grain soap 
 in 165 lb. 
 of soap 
 
 the soap 
 contain of 
 water, soda, 
 
 the soap 
 contain of 
 real grain 
 
 QTWi. soap> 
 
 
 
 
 examined. 
 
 glycerin, &c. 
 
 soap. 
 
 0-5 
 
 0-93 
 
 0-46 
 
 3-13 
 
 4-85 
 
 97 
 
 3 
 
 5 
 
 
 4-65 
 
 31-30 
 
 48-50 
 
 69 
 
 31 
 
 6 
 
 
 ■5'58 
 
 37-56 
 
 58-20 
 
 63 
 
 37 
 
 7 
 
 
 6-51 
 
 43-82 
 
 67-90 
 
 57 
 
 43 
 
 8 
 
 
 .7-44 
 
 50-08 
 
 77-60 
 
 51 
 
 49 
 
 9 
 
 
 8-37 
 
 56-34 
 
 87-30 
 
 44 
 
 56 
 
 10 
 
 „ % 
 
 9-30 
 
 62-60 
 
 97-00 
 
 38 
 
 62 
 
 11 
 
 
 10-23 
 
 68-86 
 
 106-7 
 
 32 
 
 68 
 
 12 
 
 
 11-16 
 
 75-12 
 
 116-4 
 
 26 
 
 74 
 
 13 
 
 
 12-09 
 
 81-38 
 
 126-1 
 
 20 
 
 80 
 
 14 
 
 
 13-02 
 
 84-64 
 
 135-8 
 
 13 
 
 87 
 
 15 
 
 
 13-95 
 
 93-90 
 
 145-5 
 
 7 
 
 93 
 
222 SOAP. 
 
 use, when the "fatty acids per cent." are determined by 
 weight. 
 
 A short way of ascertaining whether there is much besides 
 pure soap and water in a sample of soap, is to treat it with 
 strong warm alcohol, which dissolves nothing but the soap, 
 and excess of caustic soda, if any ; this last may be removed 
 by a stream of carbonic acid gas. The insoluble residue may 
 be collected on a tared filter, washed with alcohol, dried, and 
 weighed. 
 
 The Industrial Society of Mulhouse awarded a prize to 
 Cailletet for a method of analyzing soap without more 
 weighings than that of the soap itself. Minute instructions 
 are given in the Bulletin of the Society, No. 144, Tome 
 xxix., p. 8. Suffice it to say here that, in the first place, 
 much information may be gained for industrial purposes by 
 attentively observing the behaviour of the soap with hot and 
 cold water; 10 grm. of the soap are then decomposed by 
 excess of standard acid in presence of a measured volume 
 of turpentine-oil, the increase in volume of which, mul- 
 tiplied by the sp. gr. of the fatty acids, gives their weight. 
 The acid solution is titrated back with soda, and the soda 
 per cent, is calculated. It is, however, stated erroneously, 
 that the turpentine does not dissolve the rosin, and that 
 thus the presence of rosin may be detected, and even esti- 
 mated. 
 
 A good scheme for the complete analysis of soap, first 
 published in the Chemical News by Prof. Albert E. Leeds, 
 is reproduced on the opposite page. 
 
 It is somewhat remarkable that there are very few- 
 published analyses of soaps upon which much reliance can be 
 placed, the amount of information afforded by them being 
 very meagre, and usually confined to the pei centage of fatty 
 acids and of the " total soda," the remainder being entered as 
 " Water, &c." A valuable table is given by Mr. Allen ■ 
 (loc. cit. p. 255), and appended are some published by the 
 author in 1881, with a few additions. It must be remem- 
 bered thai; the fatty acids are weighed as hydrates (pp. 9, 11), 
 
a ^ rt 
 
 Is 
 
 ■■ CO 
 
 ^ d3 
 
 
 
 1.3 E?.3'o'3 • 
 
 laof*"' 
 
 
 ;as 
 
 ass 
 
 ?«■! 
 
 fag 
 81-9| 
 
 So ' 
 
 ■&^' 
 
 
 OJ ~ o 
 
 *^ S 
 
 ■a P, m 
 g u M 
 
 hCH' 
 
 ■. o 
 
 il 
 
 'wjixig pan a^Bonis m paniqmoo Bpos suiniia^dp 
 puB iQH miii asodmoodQ ■a^Boixia mnipog 
 
 
 •lOSy SB qSraM. ao ^oijSv qjiai ai^mx 'TOBN 
 
 •Sq^Sb^ SB a^BinoiBO 
 
 
 
 * S t. 
 
 (D ^ O 
 
 o o 
 
 rtQ'0,-3 S S 
 
 s CIS 
 Sisg 
 
 "" 3'S.Sf53.M-s 
 F,SSgB§.s° 
 
 = |3§-aS.»sg 
 cn«M Sso) ? g 3 
 
 
 ■13 ft 01 ;l fc * tH:='0 H 
 . t- ft « -s -S -H &ja S ■*= 
 
 ■|IPIll|i1 
 
 
 
 ® S b 9 o oj si rt .2 Q) ' 
 
 -qSjSAi puB oOIT VB £lQ 
 
 "iv} p9n|qraooun sf qo-Bj^xgr 
 
224 
 
 SOAP. 
 
 and hence the sum of the constituents should always exceed 
 100 per cent. Approximately, 100 parts fatty acids as 
 ■weighed represent 97 parts of the " anhydrides,'' as they 
 exist, for example, in soap dried at 300° F. (149° C). 
 
 A good Yellow Soap knoijim as 
 " Primrose " in South and West of 
 England, 
 
 Per cent. 
 
 "Water 32-8 
 
 Soda, total 6-7 
 
 Sodium chloride . . . . • 2 
 Fatty aoida 62-3 
 
 102-0 
 
 An old-fashioned Grease Mottled 
 
 Per cent. 
 
 Water 29-8 
 
 Soda with fat 7-0 
 
 „ (free caustic) .. .. 0-6 
 
 Sodium chloride 0-1 
 
 Fattyaoids 64-7 
 
 102-2 
 
 A genuine " Cold-water " Soap. 
 
 Per cent. 
 
 Water .. 22-0 
 
 Sodawithfat 7-3 
 
 „ with silica, &c 1 • 8* 
 
 Silica 1-6 
 
 Sodium chloride and sulphate 0-4 
 Fattyaoids 70-2 
 
 103-3 
 
 * Or 6'0 per cent. Bodium silicate sp. gr. 
 l-'700. 
 
 Manufaciwers' Brown Oil i 
 from Oleic aaid. 
 
 Per cent. 
 
 Water 21-00 
 
 Combined soda 7-88 
 
 Free soda 1-00 
 
 Other soda salts . . . . 1-00 
 Fatty acids 68-60 
 
 99-48 
 
 A Blue (red, or grey) Mottled Soap. 
 
 Per cent. 
 
 Water 44-3 
 
 Soda with fat 5-2 
 
 ,-. (free, or) as silicate . . 0-8 
 
 Silica 1-3* 
 
 Sodium chloride . . . . 0-8 
 
 „ sulphate .. .. 0-3 
 
 Mottling and insoluble .. 0-7 
 
 Fattyaoids 47-5 
 
 100-9 
 
 * Eqnalto 3-9 per cent, sodium silicate 
 at 1-700 sp. gr. Some of the "case 
 hardened " mottled soaps (p. 179) contain 6 
 or J per cent, of sodium chloride. 
 
 A neutral Curd Soap, for Manu- 
 factwrers. 
 
 Per cent. 
 
 Water 28-0 
 
 Soda with fat 7-0 
 
 „ free, &c 0-0 
 
 Sodium chloride .. .. 0-2 
 
 Fattyaoids 67-9 
 
 108-1 
 
THE SOAP TRADE. 
 
 225 
 
 Marine Soap, for emigrants' 
 use. (0. Hope.) 
 
 Per cent. 
 
 Patty acids 20-02 
 
 Soda existing as soap .. 3' 11 
 
 Silica 9-00 
 
 Soda as silicate 3*98 
 
 Sodium chloride .. .. 6' 13 
 
 „ sulphate .. .. 0'35 
 
 „ carbonate .. .. 2 "35 
 
 „ hydrate .. .. 0-65 
 
 Liine,ironoxide,&c 0'16 
 
 Water 53-82 
 
 Glycerin (calcul.) .. .. 2-80 
 
 100-87 
 
 Prim/rose Soap as in the North of 
 England. 
 
 Per cent. 
 
 Water 50-40 
 
 Combined soda 5-41 
 
 Soda, free and as silicate .. 1-21 
 
 Silicic acid 0-94 
 
 Sodium chloride 0.42 
 
 „ sulphate 0-13 
 
 ■Patty acids 42-66 
 
 101-17 
 
 THE SOAP TRADE. 
 
 A few remarks upon the location, prospects, legislative 
 condition, and other general considerations connected with 
 the soap-trade, may fitly close these chapters on this 
 important manufacture. 
 
 This industry is by no means localized in any one part of 
 the British Islands ; but, although the total amount of soap 
 made in England is probably greater now than it ever was, 
 the tendency of the last 25 years has been in the direction of 
 concentrating the manufacture in the hands of a few large 
 firms. Probably the oldest soap-works in the country are, or 
 at any rate until recently were, to be found in Bristol, which 
 still retains great reputation for its soap. A relic of this 
 may be found at the present day in Holland, in some parts of 
 which no soap can be sold which is not stamped with the 
 word Bristol. Of the two soap-works now left in that 
 city, the larger, belonging to the firm of Christopher 
 Thomas & Bros., was established in 1745. 
 
 The abolition of the duty on soap in 1853, then about 2d. 
 a lb., and producing a revenue of upwards of 1,000,000Z., 
 naturally gave an immense impulse to improvements in the 
 manufacture, and various valuable patents were very shortly 
 taken out, the most important of which were those of 
 
 Q 
 
226 SOAP, 
 
 W. Gossage for silicated soaps ; that of T. Thomas for cheap 
 detergent soaps made from mixtures of neat soap, with 
 sodium silicate and sulphate ; that of Blake & Maxwell for 
 hydrated soaps (p. 164) ; and those of C. N. Kottula, for 
 various improvements in the making of hlue-mottled and 
 other soaps. An association of soap-manufacturers in England 
 holds quarterly meetings, at which prices are revised, common 
 action agreed upon, and legislative enactments affecting the 
 trade discussed and watched. All soap-works, in common 
 with other factories, are subject to inspection by Factory 
 Inspectors acting under the Government, and to the visits of 
 a certifying surgeon who regulates the admission to work 
 of young persons under 18 years of age, and also performs 
 various functions of inspection and report in cases of ac- 
 cidents, &c. It is his duty to see that certain sanitary 
 precautions are duly enforced. 
 
 In a well-managed soap-works, the sources of nuisance are 
 very slight, and comparatively inoffensive; most of them 
 arise, not from the actual process of soap-making itself, 
 but from the preliminary operations of refining, purify- 
 ing, and bleaching the fatty matters employed (Chap. III.)." 
 They may all be 'obviated by conducting such operations 
 in closed vessels provided with trunks communicating with 
 the draught of a' flue; when impure and rancid fats are 
 used direct for soap-making, the copper should be provided 
 with a cover and a similar trunk. In default of a flue- 
 draught, a fan or a jet of steam may be used to create a 
 good current of air. In some cases the obnoxious fumes 
 may be conducted with advantage into the ashpit of a 
 fire-place or furnace, where they are at once consumed ; care 
 must be taken, however, that they do not contain enough 
 vapour of fatty matters to make them inflammable. In dealing 
 with these matters, water-lutes, water-joints, wash-bottles, 
 and similar contrivances, will be found very useful, but it is 
 an obvious precaution so to arrange the apparatus that there 
 may be no chance of any water being " sucked back " (by a 
 suddenly formed vacuum) into heated tallow or oils, else an 
 
THE SOAP TEADB. 227 
 
 explosion might ensue. Mamifactnrers will derive some 
 ■useful hints upon the prevention of odorous nuisances in 
 their works, from Dr. Ballard's reports to the Local Govern- 
 ment Board. 
 
 Since the removal of the duty, there are few means of 
 forming an estimate of the extent of the soap-trade in 
 England ; it is known, however, that ' many of the larger 
 houses make much more than 5000 tons a year, while a few 
 make over 10,000, and it is stated that one house is capable 
 of turning out 500 tons in a week when necessary. The 
 total annual production in the United Kingdom was esti- 
 mated at 250,000 tons by Prof. Eosooe, in his inaugural 
 address as President of the Society of Chemical Industry, in 
 June 1881. 
 
 In France, the chief seat of the industry is at Marseilles, 
 while a not inconsiderable amount of common soap, and 
 nearly all the toilet soaps, are made in Paris. In a report 
 on the exhibits at Paris in 1878, it was stated that the 
 French soap-trade had been for some time stationary at about 
 220,000 tons per annum, but was then declining, owing to 
 practices not very creditable to the manufacturers. 
 
 In Germany, and other parts of the Continent, soft soaps 
 are much more proportionately in vogue for laundry and 
 other purposes, than in England, while the chief hard soaps 
 made are for toilet purposes. 
 
 In the United States, Kirk & Co. of Chicago have probably 
 the largest trade, but they are closely approached by Babbitt 
 & Co., and Colgate & Son, of New York. The changes 
 which have lately passed over the trade in America have 
 been already alluded to (p. 188). It may be said, without 
 fear of contradiction, that while perhaps for fancy toilet 
 soaps the palm must be given to France, England and the 
 United States are pre-eminently the countries where the 
 manufacture of the different varieties of household and 
 factory soaps is most clearly understood, and carried out on 
 the largest scale, and in the best manner. 
 
 In Australasia, the largest soap-works are those belonging 
 
 Q 2 
 
228 
 
 SOAP. 
 
 to Messrs. Kitchen Bros. The chief seat of the trade is in 
 Melbourne; and the products recently shown at the Mel- 
 bourne International Exhibition compared very favourably 
 with similar articles manufactured in England. As in 
 America, nearly the whole of the alkali used is imported, 
 chiefly from England. 
 
 The quantity and value of the soap exported from Great 
 Britain in 1883 are shown in the following table : — 
 
 To Germany 
 
 „ France 
 
 „ Spain and Canaries 
 
 ., Italy 
 
 „ Western Africa (Foreign) 
 
 „ Java 
 
 „ China 
 
 „ United States : Atlantic 
 
 „ Foreign West Indies 
 
 „ Central America 
 
 „ Channel Islands 
 
 „ Gibraltar .. .. • 
 
 „ Western Africa (British) 
 
 „ British Possessions in South Africa 
 „ British India : 
 
 Bombay and Soiude 
 
 Bengal and Burmah 
 
 „ Hong Kong 
 
 „ Australasia 
 
 „ British North America 
 
 „ British West India Islands and British 
 
 Guiana 
 
 „ Other Countries 
 
 Total 
 
 Cwts. 
 
 3,844 
 7,741 
 
 26,098 
 8,772 
 8,505 
 
 29,642 
 8,747 
 7,286 
 
 10,250 
 5,117 
 4,526 
 
 11,677 
 5,379 
 
 72,465 
 
 14,346 
 
 13,757 
 
 24,891 
 
 8,352 
 
 3,725 
 
 74,508 
 42,160 
 
 391,788 
 
 6,754 
 13,937 
 25,067 
 10,772 
 
 8,519 
 27,974 
 
 8,443 
 11,953 
 10,508 
 
 5,989 
 
 5,939 
 11,736 
 
 5,461 
 74,725 
 
 21,121 
 17,331 
 27,021 
 17,848 
 5,185 
 
 77,564 
 55,957 
 
 449,804 
 
( 229 ) 
 
 CHAPTEE IX. 
 
 LUBEICATING OILS, EAILWAT AND WAGGON 
 GEEASB, Etc. 
 
 The object of lubrication is the reduction of friction between 
 moving surfaces, hence an efficient lubricator must exhibit 
 the following characteristics : — (1) Sufficient " body " to keep 
 the surfaces between which it is interposed from coming 
 into contact ; (2) the greatest fluidity consistent with (1) ; 
 (3) a minimum co-efBcient of friction; (4) a maximum 
 capacity for receiving and distributing heat; (5) freedom 
 from tendency to " gum " or oxidize ; (6) absence of acid and 
 other properties injurious to the materials in contact with it ; 
 (7) high vaporization- and decomposition-temperatures, and 
 low solidification-temperature ; (8) special adaptation to the 
 conditions of use ; (9) freedom from foreign matters. 
 
 There are certain qualities which ought to be taken into 
 consideration, when it is desired to form an opinion as to the 
 suitability of a given lubricating oil for a particular class of 
 work, hence the modern methods of testing the lubricating 
 qualities of oils are directed to a discovery of the following 
 points : — (1) Their identification and adulteration ; (2) den- 
 sity ; (3) viscosity ; (4) " gumming " ; (5) decomposition-, 
 vaporization-, and ignition-temperatures ; (6) acidity ; (7) co- 
 efficient of friction. Of these, Nos. 1, 2, 3, and 6 have been 
 described in Chap. III., but it may be well to add in this con- 
 nection that the viscosity of oils (p. 95) decreases greatly with 
 rise of temperature, and in a different degree with different 
 oils. This is well shown in the following table (Allen), the 
 figures in which are the number of seconds required by the 
 same quantity of the respective oils to pass through the same 
 aperture at different temperatures. 
 
230 
 
 LUBRICATING OILS, EAILWAY 
 
 So. of Seconds required. 
 
 (60° F.) 
 (15^° C.) 
 
 (120° F.) 
 (49° C.) 
 
 (180° F.) 
 (82° C.) 
 
 Sperm-oil 
 
 Olive-oil 
 
 Lard-oil 
 
 Kape-oil 
 
 Neata'-foot-oil 
 
 Tallow-oil . . 
 
 Engine tallow 
 
 47 
 
 92 
 
 96 
 
 108 
 
 112 
 
 143 
 
 Solid 
 
 30-5 
 
 37-75 
 
 38-0 
 
 41-25 
 
 40-25 
 
 37-0 
 
 41-0 
 
 25-75 
 
 28-25 
 
 28-5 
 
 30-0 
 
 29-25 
 
 25-0 
 
 26-5 
 
 The viscosity and gumming tendency may be simul- 
 taneously detected by noting tbe time required by a drop to 
 traverse a known distance on an inclined plane. A 9 days' 
 trial gave the following result : — Common sperm-oil, 5 ft. 8 in. 
 on the 9th day ; olive-oil, 1 ft. 9J in. on the 9th day ; rape- 
 oil, 1 ft. 7f in. on the 8th day ; best sperm-oil, 4 ft. 6j in. on 
 the 7th day ; linseed-oil, 1 ft. 6 J in. on the 7th day ; lard-oil, 
 11 1 in. on the 5 th day. The day given is in each case that 
 on which the oil ceased to travel. There are several ways of 
 applying the inclined plane test, and for further details 
 Appleton's ' Dictionary of Mechanics ' may be consulted with 
 advantage. A very simple and general test of fluidity is to 
 dip blotting-paper in the oil, and hold it up to drain : sym- 
 metrical drops indicate good fluidity ; a spreading tendency, 
 viscosity. Eetention of the oil on the paper for some hours at 
 200°F.{93J'' 0.),or for some days at ordinary temperatures, will 
 show the rate of gumming. A more exact method of exa- 
 mining the drying property of an oil is to expose a definite 
 number of drops in a shallow capsule, to a temperature of 
 about 266° F. (130° 0.) for twelve hours, side by side with a 
 sample of oil of known purity. Another useful test is 
 Gellatly's, in which a definite quantity of the oil is spread 
 over cotton waste, and kept at about 176° F. (80° C.) ; after a 
 length of time, varying with each oil, the mass bursts into 
 active combustion. 
 
 It is scarcely necessary to observe that all lubricating oils 
 
AND WAGGON GREASE, ETC. 231 
 
 should he entirely free from any acid reaction, whether that 
 arises from traces of mineral acid left from refining processes, 
 or from the formation of fatty acids (through the agency of 
 ferments, &c.) in the oils themselves. Many experiments 
 have heen published concerning the action of oils on metals, 
 tut they are all untrustworthy. There is now no reasonahle 
 douht that the action observed and described was due, in all 
 cases, to the acidity of the oils from one, and probably from the 
 second, of the two causes named. The method of determining 
 the acidity of an oil is described on p. 86. 
 
 An ingenious method of detecting the sophistication of 
 mineral oil by rosin-oil has lately been proposed by E. 
 Valenta.* It depends upon the fact that glacial acetic acid 
 at 122° F. (50° C.) has only a slight solvent action upon 
 mineral oils, while it readily dissolves rosin-oil. As the 
 solubility of a mixture of rosin and mineral oils is not pro- 
 portional to the quantity of the former, the test is not 
 capable of yielding quantitative results. If, however, it be 
 combined with the determination of the absorptive power 
 for iodine of the oil in question (p. 104) by Hiibl's 
 method, and with an observation of its rotary power (most 
 rosin-oils rotate the polarised ray very strongly), valuable 
 results may be obtained.f 
 
 Owing to the fact that hydrocarbon oils of low volatility 
 enter largely into the composition of many lubricating oils, 
 the " flashing-point " becomes a character of importance. 
 
 There are several forms of apparatus for determining this, 
 as Tagliabue's, Millspaugh's, Abel's, Saybolt's, Parrish's, 
 Salleron-Urbain's, Sintenis', Bernstein's, and Bailey's. The 
 apparatus consists essentially of a receptacle for the oil to be 
 tested, a water-bath surrounding the receptacle, a lamp for 
 heating the water-bath, a thermometer to indicate the 
 temperatures, an outlet for the vapour generated from the 
 oil, and a means of reaching the oil itself. 
 
 * Dingl. Polyt. Journal, 252, 253, 296, 418 (1884). 
 f Journ. Soc. Chem, Ind., iii. 
 
232 
 
 LUBEICATING OILS, RAILWAY 
 
 ^r, 
 
 The form of tester recognized in tiiis country under the 
 Petroleum Act, 1879, is shown in Fig. 72. The oil-cup A 
 consists of a cylindrical vessel of 2 in. diameter and 2-f^ in. 
 internal height, with an outward projecting rim h ^ va.. 
 wide, I in. from the top, and \\ in. from the bottom of the 
 cup. It is made of gun-metal or brass, tinned inside. A 
 
 bracket h, consisting of 
 I'm. 72. a short stout piece of 
 
 wire bent upwards and 
 terminating in a point, 
 is fixed to the inside of 
 the cup to serve as a 
 gauge. The distance 
 of the point from the 
 bottom of the cup is 
 \\ in. The cup is pro- 
 vided with a olose-fit-'j 
 ting overlapping cover 
 made of brass, which 
 carries the thermometer 
 I and test-lamp m. The 
 latter is suspended from 
 two supports at the side 
 by means of trunnions 
 on which it oscillates, 
 and is provided with a 
 spout, whose mouth is 
 
 ^ in. in diameter. The 
 
 socket to hold the thermometer is fixed at such an angle, and 
 its length is so adjusted, that the bulb of the thermometer 
 when inserted to its full depth shall be 1^ in. below the 
 centre of the lid. Technical handbooks on the subject 
 contain elaborate descriptions of it, and instructions for its 
 use, especially for testing lamp-oils. Most of them are 
 taken from the Schedule to the Petroleum Act itself, which 
 may be consulted with advantage, 
 
AND WAGGON GKBASE, ETC. 233 
 
 The " flasMng-point " of an oil is understood to mean the 
 temperature at which the escaping vapour will momentarily 
 1 1 ignite ; the " burning-point " is that at which the oil takes 
 fire and bums. Lubricating-oils should always flash above 
 250° P. (120° C), and take fire at a considerably higher 
 temperature. Animal and vegetable oils do not vaporize, 
 but decompose at high temperatures, beyond the range of 
 a water-bath. A comparison of petroleum, sperm-oil, and 
 lard-oil showed the following respective figures : — Flashing- 
 point : 245° F. (118° C), 425° F. (219° C), 475° F. (246° C.) ; 
 igniting-point : 290° F. (143° C), 485° F. (252° C), 525° F. 
 (274° C.) ; burning-point : 300° F. (149° C), 500° F. (260° C); 
 525° F. (274° C). The standard animal and vegetable lubri- 
 cating-oils, and all mineral oils of good " body " and high 
 sp. gr., decompose or vaporize only at temperatures exceeding 
 that of steam in ordinary engines, the former usually, and 
 latter sometimes, bearing steam at locomotive pressure. The 
 precise value of any lubricating material is best ascertained 
 by one of the many forms of apparatus devised for this 
 purpose, such as McNaught's, Napier's, Ingham and Stapper's, 
 Bailey's, Ashcroft's, Crossley's, Van Cleve's, Hodgson's, &c., 
 fully<described and figured in Thurston's ' Friction.' 
 
 The suitability of a lubricating medium depends upon the 
 character of the work being done, and is not constant. In 
 order to procure the nearest possible approach to what is 
 required for special purposes, many compounds are now pre- 
 pared, which are mainly mixtures of mineral and animal or 
 vegetable oils in proportions calculated to develop the parti- 
 cular characteristics required. The general experience 
 gained of various oils used for lubricating tends to the 
 following results : — 
 
 (1) A mineral oil flashing below 300° F. (149° C), is 
 unsafe, on account of causing fire ; 
 
 (2) A mineral oil evaporating more than 5 per cent, in 10 
 hours at 140° F. (60° C.) is inadmissible, as the evaporation 
 creates a viscous residue, or leaves the bearing dry ; 
 
234 LUBEIOATING OILS, EAILWAT 
 
 (3) The most fluid oil that will remain in its place, ful- 
 filling other conditions, is the best for all light bearings at 
 high speeds ; 
 
 (4) The best oil is that which has the greatest adhesion 
 to metallic surfaces, and the least cohesion in its own 
 particles : in this respect, fine mineral oils are 1st, sperm-oil 
 2nd, neats-foot-oil 3rd, lard-oil 4th ; 
 
 (5) Consequently the finest mineral oils are best for light 
 bearings and high velocities ; 
 
 (6) The best animal oil to give " body " to fine mineral 
 oils is sperm-oil ; 
 
 (7) Lard- and neats-foot-oils may replace sperm-oil when 
 greater tenacity is required ; 
 
 (8) The best mineral oil for cylinders is one having 
 sp. gr. 0-893 at 60° F. (15 J° C), evaporating-point 550° F. 
 (288° C), and flashing-point 680° F. (360° C.) ; 
 
 (9) The best mineral oil for heavy machinery has sp. gr. 
 0-880 at 60° F. (15^° C), evaporating-point 443° F.(229°C.), 
 and flashing-point 518° F. (269° 0.) ; 
 
 (10) The best mineral oil for light bearings and high 
 velocities has sp. gr. - 871 at 60° F. (15 J° C.) evaporating- 
 point 424° F. (218° C), and flashing-point 505° F. (262° C.) ; 
 
 (11) Mineral oils alone are not suited for the heaviest . 
 machinery, on account of want of " body,'' and higher degree 
 of inflammability ; 
 
 (12) Well-purified animal oils are applicable to very 
 heavy machinery ; 
 
 (13) Olive-oil is foremost among vegetable oils, as it can 
 be purified without the aid of mineral acids ; 
 
 (14) The other vegetable oils admissible, but far inferior, 
 stated in their order of merit, are gingelly-, ground-nut-, 
 colza-, and cotton-seed-oils ; 
 
 (15) No oil is admissible which has been purified by 
 means of mineral acids. 
 
 Railway- and "Waggon-grease.— The first of these 
 consists essentially of a mixture of a more or less perfectly 
 
AND WAGGON GEEASE, ETC. 235 
 
 formed soap, water, sodium cartonate, and neutral fat, and is 
 used on the axles of all locomotives, railway-carriages, and 
 trucks which are provided with axle-boxes ; while the second 
 is a soap of lime and rosin -oil, with or without water, and is 
 used on all railway-trucks unprovided with axle-hoxes, and 
 for ordinary road-vehicles. 
 
 The requisites for a good " locomotive-grease " for high 
 velocities are: — (1) a suitable consistency, such that it 
 will neither run away too rapidly, nor be too stiff to cool 
 the axles ; (2) lasting power, so that there may be as little 
 increase of temperature as possible in the axles, even at 
 high speeds ; (3) a minimum of residue in the axle-boxes. 
 
 In practice, it is found that a grease containing 1-1 to 1 • 2 
 per cent, soda gives the • best results. The process of 
 manufacture is very simple, Morfit's soap-pans, provided 
 with stirrers, p. 148, Pigs. 34^6, are the most suitable vessels 
 for the purpose. , The fats, usually tallow and palm-oil, 
 are heated to 180° P. (82° C), and into them are allowed 
 to flow the sodium carbonate and water heated to 200° F- 
 (93^° 0.) ; the whole is then well stirred together, and run 
 into large tubs to cool slowly. Many railway companies buy 
 a curd-soap made from red palm-oil, dissolve it in water, and 
 add thereto enough tallow and water to bring the compo- 
 sition of the whole to the desired point. It is usual to allow 
 2^ per cent, for loss by evaporation of water during the 
 manufacture. The composition has to be slightly varied 
 according to the season of the year ; the following formulae 
 for mixing have stood the test of successful experiment ; the 
 summer one ran 1200 miles. It should be carefully borne in 
 mind that a chemical analysis of locomotive-grease is no test 
 whatever of its practical value, which can only be determined 
 by actual experiment in some such apparatus as has already 
 been indicated. The instructions given for the analysis of 
 oils and soap (Chapters III. and VIII.) are also suitable for 
 the analysis of products of this class, all of which contain a 
 large amount of unsaponified oil. 
 
236 
 
 LUBEICATING OILS, ETC, 
 
 
 Tallow 
 
 Palm-oll 
 
 Sperm-oil 
 
 Soda crystals 
 
 Water 
 
 Summer. 
 
 Winter. 
 
 • 
 
 
 per cent. 
 
 18'3 
 
 12-2 
 
 1-5 
 
 5-5 
 
 62-5 
 
 per cent. 
 
 22-3 
 
 12-2 
 
 1-2 
 
 5-0 
 
 69-3 
 
 
 
 100-0 
 
 100-0 
 
 
 The " waggon-grease " is thus prepared. A good milk of 
 lime is made, and run through several overflow-tubs, where 
 all grit is deposited ; it is then drained on canvas. If the 
 grease is to he made without water, the paste must be 
 agitated with rosin spirit, which expels the water, and it is 
 then thinned with a further quantity of rosin spirit. The 
 aqueous milk of lime, or the mixture of lime and rosin spirit, 
 is then stirred together with a suitable quantity of rosin-oil 
 in a tight barrel furnished with a shaft and stirrers, without 
 the application- of heat, after which, the whole .is run out 
 into barrels to set. Many other ingredients are often stirred 
 in, such as " dead oil," petroleum residues, graphite, sea-weed 
 jelly, sodium silicate, oil refiners' foots, micaceous ores, 
 steatite, Irish moss, &o. 
 
 A careful estimate was made in 1865, compiled from 
 various reliable sources, by Watts, of the total quantity of 
 anti-friction greases made in the United Kingdom in a year, 
 of which the following is an abstract :— 
 
 Tons. 
 
 ill - 7 owt. per mile per year 6 , 358 
 1-42 owt. per 1000 tons coal 6,108 
 Other minerals, &c 711 
 
 Agricultural carts 2,130 
 
 Trade and other carts, &c. .. , 2,070 
 
 Tvtal 17,377 
 
( 237 ) 
 
 CHAPTER X. 
 
 CANDLES ; — Kaw Materials, Their Sources and Preli- 
 minary Treatment. 
 
 HISTORICAL SKETCH. 
 
 Probably the earliest known means of lighting was the 
 torch, usually cut from pitch pine, and sticky with exuded 
 rosin ; it was used largely of old in northern countries, and 
 even in Eome (Lat. Taeda). Next came the link (Gr. Xv;^os), 
 a mere mass of cordage, thoroughly saturated with rosin and 
 pitch, a source of light which even still, on foggy days, 
 connects us with the past. After that appeared the ^amSeaw, 
 which was a finer kind of link, consisting of a centre of oakum, 
 surrounded with alternate layers of rosin and crude beeswax. 
 These may be said to have formed the main illuminating 
 agents of the upper classes up to the 16th or 17th century, 
 the lower classes contenting themselves with rushlights, 
 the origin of which probably dates back to the 1st century 
 after Christ.* Etymology shows that the word candle 
 (Lat. candelo, Gr. xavS^Aa, Persian handeel, Sanscrit han), is 
 derived from roots signifying to shine or burn ; it is not 
 met with in any classical writings till towards the end of the 
 2nd century, and it is clear that candles wt-re at no time 
 considered so respectable as lamps. A chandler's apparatus 
 was found at Herculaneum, and in the British Museum is a 
 fragment of a huge candle (i.e. a wick surrounded with 
 a coating of wax or tallow) supposed to have been made 
 during the 1st century. 
 
 * For an exhaustive account of the ancient modes of lighting, and a 
 disquisition on the etymology and nomenclature of the iUmninants, the 
 Cantor Lectures of Mr. Leopold Field, F.C.S., published in the Soo. Arts 
 Journal, Jan.-Mar., 1883, may be consulted with advantage. 
 
238 CAUDLES. 
 
 Wax and tallow contimie4 to be used, to the exclusion of 
 every other solid illuminant, till very near the end of the 
 18th century, when the sperm fishery began. Spermaceti 
 is the best and most beautiful material for candles that 
 exists, but its cost is a serious objection to its use. Early 
 in the 19th century the brilliant researches of Chevreul 
 demonstrated the constitution of fats (pp. 4-11), and sub- 
 sequently the practical genius of De Milly in France, and 
 later of G. T. Wilson in England, applied this knowledge 
 to the successful elaboration of the two chief industrial pro- 
 cesses by which candles are made from stearic and palmitic 
 acids (Chap. XII.). In the latter half of this same century, 
 the observing insight and untiring energy of James Young 
 created the paraffin candle, which was- followed by the utili- 
 zation, for the same purpose, of ozokerit, or earth-wax, by 
 the Messrs. Eield. 
 
 BAW EATESIALS. 
 
 In addition to tallow, palm-oil, and the various fats and 
 oils described in Chap. II., there are several other classes of 
 hydrocarbons which are largely used by the candle-maker 
 only ; a short account will now be given of the sources and 
 chemical constitution of these, as well as of their preliminary 
 treatment and preparation for conversion into candles. 
 
 Waxes (including Spermaceti). 
 
 Waxes may be defined as bodies of a certain viscid plasti- 
 city when warmed, composed of fatty acids of the adipic 
 series, OnHj^Oj, either free, or in combination with an 
 alcohol radicle, or of a mixture of both. They are very 
 difficult to saponify, yielding no glycerin, and their soaps" 
 are only sparingly soluble in water. The following list 
 includes most of those valuable to the candle-maker, — 
 
 Animal. 
 
 
 Origin. 
 
 Bees- wax 
 
 . . A'pis. 
 
 Spermaceti 
 
 .. Pliyseter macrocephalus. 
 
 Chinese wax . . 
 
 Cocam ceriferus. 
 
RAW MATERIALS. 239 
 
 Origin, 
 CariiE^uba wax . . . . . . Copernida eerifera. 
 
 Myrtle „ •■ •• ■• Myrica eerifera. 
 
 Japan » ■ • • ■ • • Rhus suceedanea. 
 
 Palm II • • ■ ■ ■ ■ Ceroxylon andicola. 
 
 Beeswax. — The composition of beeswax has recently been 
 settled by the elaborate researches of Mr. Otto Hehner ; the 
 discrepancies in former analyses being probably due in great 
 part to the exapiination of adulterated articles. As many 
 as 40 different varieties are known, nearly all of them 
 characteristic of their native lands, and although they 
 differ greatly in physical characters, their composition 
 (when pure) varies but little. The two chief constituents are 
 cerotic acid, C2, Hj^Oj, 12 per cent., and myrioin C4JH92O2, 
 88 per cent., with traces of a substance very difficult to iso- 
 late, for which the name cerolein is proposed. When bees- 
 wax is treated with alcohol, the cerotic acid dissolves, 
 leaving the crystalline myricin. This substance is a typical 
 
 wax, being a palmitate of myricil p^'xT^'^ [ Oj. The general 
 
 C H ) 
 
 formula of a true wax is r^"-!!^" "*" ' ?0.,. 
 
 A considerable quantity of beeswax is imported annually 
 from Corsica, and smaller amounts from India, Ceylon, North 
 America, and Brazil. It is always of a brownish or yel- 
 lowish colour, and has a peculiar smell resembling, and 
 derived from, honey. 
 
 Commercial beeswax is adulterated with almost every 
 conceivable fat, cheap paraffin, &c., as well as with " make- 
 weights " of a coarser description ; by careful sampling, a 
 keen buyer manages to escape with about 75 per cent, of 
 pure wax. The first operation is to boil it on weak acid 
 water, and to separate the dross by subsidence. It is 
 bleached either by air, or by potassium bichromate and 
 hydrochloric acid, much as directed for palm-oil, p. 79. 
 Thus treated, however, it becomes much more crystalline, 
 owing to the myricin being split up into palmitic and 
 
240 CANDLES. 
 
 cerotio acids. When it is air-bleached it is melted in hot 
 water, or by steam, in a vessel either of tinned copper or of 
 wood, allowed to settle, and the waxy superstratum is run 
 off while fluid into a wooden trough having a row of per- 
 forations in its bottom, by which it is distributed upon 
 horizontal wooden cylinders, made to revolve with their 
 lower portions surrounded by cold water. The ribbons or 
 films made in this way are then exposed to the bleaching 
 action of the atmosphere and the sunlight, being frequently 
 moistened and turned over during the process. It is neces- 
 sary to guard against wind, which might scatter the shreds ; 
 for this purpose, large cloths are provided. The operation is 
 continued until the wax becomes perfectly clean and white. 
 It is usually conducted from April till September, the exi- 
 gencies of the weather preventing it at other seasons. In 
 France, it is customary to add a little cream of tartar or 
 alum to the water in which the wax is melted, by which the 
 long and tedious operation of bleaching is rendered much 
 shorter. Bleaching agents, such as chlorine, cannot be em- 
 ployed to bleach wax, since they render it unfit for making 
 into candles. Purified in the above manner, beeswax is 
 perfectly white, and has neither taste nor smell ; it has a 
 specific gravity of from 0-960 to 0'996; at a temperature 
 of 86° F. (30° C.) it becomes soft, and melts at 15i° F. 
 (68° 0.) ; at 32° F. (0° C.) it is hard and brittle. 
 
 Spermaceti (Germ. Wallraih, Fr. Blanc de laleine) is written 
 in old works sperma ceti, testifying to the belief then current 
 that it was the spawn of the whale. The history of the rise 
 of this industry is fraught with interest.* The cachalot or 
 sperm' whale {Physeter macrocephalus), so called from its enor- 
 mous head, 14 ft. high and 25 ft. long, is the main source of 
 this beautiful candle-material. It is found not only in 
 the "head-matter," but generally diffused throughout the 
 blubber ; moreover it is now acknowledged that the oil from 
 the " bottle-nose " whale (Balcena rostrata) contains a consider- 
 
 » Consult Field's Cantor Lectures, ho, eit. 
 
EAW MATERIALS. 241 
 
 able quantity of spermaceti, of a slightly higher melting- 
 point than from the cachalot, which melts at 113° F. (45° C.)- 
 
 P IT 1 
 
 Spermaceti mainly consists of cetyl palmitate, p'^-cr"/-) [O, 
 
 ■which, on distillation, yields a peculiar suhstanoe called ethal 
 (cetyl alcohol, CuHssOH), the alcohol of cetene GigSsn, one 
 of the higher terms of the olefin series, of which ethylene, or 
 olefiant gas, is the type, and the lowest term. 
 
 The first operation needed to fit spermaceti for use is tech- 
 nically termed " bagging." The crude sperm oil, as brought 
 in by the whalers, is placed in a reservoir, at the bottom of 
 which are a number of pipes leading into long bags lined 
 with linen, and temporarily closed at the bottom by tying 
 cords round the mouths. The pressure exerted by the body 
 of material in the reservoir forces a large proportion of the 
 oil through the pores of the sacking, leaving behind the solid 
 or " head-matter," as a dingy brown mass. This so-called 
 crude or " bagged " sperm is deprived of a further quantity of 
 oil by the application of pressure. It is put into hempen bags, 
 which are deposited between the plates of a hydraulic press. 
 The pressure applied is about 80-90 tons. When the oil 
 ceases to flow, the sperm is taken out, melted by heat, and 
 then drawn off into trays to granulate. The brittle crystal- 
 lized blocks are ground to a coarse powder by means of 
 revolving cylinders ; the powder is collected in a bin beneath, 
 and is filled into cloths, and subjected to a hydraulic pres- 
 sure of about 200 tons. The oil expressed under this force 
 contains a small amount of solid matters, and is therefore 
 returned for re-bagging. The blocks, as turned out of the 
 press, are melted down, and boiled for 2-3 hours with 
 caustic soda lye at 22° Tw. (14° B.), in the proportion of 
 40 parts by measure of the former to 1 J of the latter. It is 
 important to guard against an excess of alkali beyond that 
 required for combination with the oil, as it would tend to 
 saponify the spermaceti, and cause a wagte of material. The 
 mixture is kept at a low equable temperature, till the oil is 
 taken up, and Is allowed to remain at a gentle simmer, while 
 
 B 
 
242 CANDLES, 
 
 the soap that has been formed rises to the snrface and is 
 skimmed off. The heat is then raised to ahont 250°, F. 
 (121° C.),and the mass is treated with small successive doses 
 of water, the additional scum being carefully taken off as it 
 rises, till the whole is clear. It is then drawn off' to crystal- 
 lize in flat tin dishes, whereupon the cakes are again reduced 
 to powder, placed in linen bags, and subjected to hot pres- 
 sure in a very powerful hydraulic press heated by steam, 
 after which the spermaceti will still contain a quantity of 
 oil, or weak sperm, which no mere pressure will remove, and 
 which must be extracted by saponification. The final opera- 
 tion consists in boiling down the sperm with strong alkaline 
 lye at 235° F. (112° C), removing the scum as before. When 
 the latter ceases to appear, further purification is effected by 
 introducing a little water, at intervals, while the heat is 
 lowered. The supernatant spermaceti, now perfectly colour- 
 less and transparent, is cast into blocks and crystallized. 
 
 Spermaceti candles are valued for their beauty and illumi- 
 nating power. They usually contain about 3 per cent, of 
 wax or paraffin, to counteract the crystalline structure of 
 the spermaceti, and are moulded in the ordinary way 
 (see Chap. XII.). The addition of a little gamboge makes 
 the spermaceti resemble wax, the compound being known 
 as " transparent wax." 
 
 Chinese wax (Chung peh-la) is produced by a small insect 
 like S, woodlouse, the Coccus ceriferus, whose cultivation is 
 now an industry next to silk in importance. According to 
 Mr. Thiselton Dyer, F.E.S., whose position at Kew Gardens 
 affords him exceptional facilities for investigating questions 
 of economic botany, the annual value of the amount pro- 
 duced is computed at about 600,000Z. The statements as 
 to the tree on which it feeds, and whose branches it covers 
 with wax, are conflicting. Fraxinus cMnemis, however, is 
 certainly cultivated for the purpose. The wax is a cerotic 
 
 (^ TT r\'\ 
 
 ether (ceryl cerotate), p^'o-^^ [O, corresponding to the true 
 cerotic ether g2^«30|o, or ethyl cerotate. It melts at 180° F. 
 
BAW MATERIALS. 243 
 
 (82° C), and can be crystallized tmchanged from boiling 
 alcohol. It has a longitudinal crystalline fibre, like stearin 
 or stearic acid, and yet possesses some of the flaky qualities 
 of sperm. 
 
 Vegetable Waxes. — Carnauba wax or stone-wax is found 
 in thin films on the leaves, stalks, and berries of a Brazilian 
 palm, Oopernieia cerifera. Its sp. gr. is • 999, and its melting- 
 point 185° F. (84° C.) ; the composition of it is not definitely 
 settled, but according to Allen it contains a notable quantity 
 
 of free myricyl or melissic alcohol ^"tt^'JO. Lewy says 
 
 that it contains 80 per cent, of carbon. The most recent 
 investigator into its composition, H. Stiirke,* states that he 
 has succeeded in isolating from it seven distinct bodies, 
 one a hydrocarbon melting at 189° F. (59-5° C); three 
 alcohols, one of which melts at 218° F. (103 • 6° C); and 
 three acids, one of which is identical with cerotic acid. 
 
 Japan wax is obtained by boiling the berries of several 
 trees of the genus Ehus, from incisions in the stems of which 
 flows the famous Japan lacquer varnish. It ought properly 
 to rank as a fat, for it consists almost entirely of glycerin 
 palmitate, and yields glycerin upon saponification. Its 
 sp. gr. is • 999, and its melting-point 120° F. (49° C). It is 
 largely used in vegetable-wax candles, which are made as a 
 substitute for beeswax. 
 
 There are several other waxes, much used in their native 
 countries, as Palm wax, from the stem of Geroxylon andicola, 
 and Ocuba wax, from Myriatiea hicuhiba, both growing in 
 Brazil, and furnishing most of the candle power of northern 
 South America ; also Andaquies wax, Cuba wax, and others 
 of uncertain origin. 
 
 Paraffins. 
 
 To Dr. James Young belongs the honour of creating the 
 paraf&n industry. In 1848 his attention was called by 
 
 * Jour. Soc. Chem. Ind., iii. 448. 
 
 B 2 
 
244 CANDLES. 
 
 Dr. Lyon Playfair to a little stream of oil perpetually 
 running in a small garden on th.e top of a coal seam at 
 Alfreton, in Derbystire. From this oil he extracted paraffin, 
 a light burning oil, and a heavy lubricating grease. In 1850 
 he took out his celebrated patent for the distillation of coal 
 minerals at a temperature not exceeding 600° F. (315° C). 
 Just prior to Dr. Young's invention, Eees Eeeoe had obtained 
 paraffin crystals and liquid, by distilling slowly the tar 
 which resulted from the rapid distillation of peat. Since 
 1862, the bituminous shale which abounds in Linlithgow and 
 Midlothian has been the only source of paraffin oil, of which 
 22-38 gal. are obtained from a ton of shale. This crude oil 
 is then subjected to fractional distillation, and the last 
 fraction is very heavy, containing 30 per cent, of paraffin. 
 The hard scale separates from the oil by crystallization in 
 ordinary weather, and the residual oil is then artificially 
 cooled, and yields a further quantity of soft scale. 
 
 The crude solid product thus formed is known as " paraffin 
 scales,'' and is of somewhat variable composition. The impu- 
 rities amount, on an average, to 20 per cent, of the weight, and 
 consist of blue oil, greasy hydrocarbons of low fusing-point, 
 solid refuse, and water. The oil manufacturers, having an 
 eye to the quantity of solid product, often separate the scales 
 from the oil, as early in the process of oil refining as possible, 
 knowing that the subsequent distillation and the treatment 
 with acid and alkali will reduce the weight of solids by 
 decomposition. Hence the process of refining may vary 
 according to circumstances. The method adopted by Messrs. 
 Young and by Messrs. Walls and Co., of Glasgow, is first to 
 melt the scales in a large pan, by the introduction of steam 
 through a perforated wrought-iron coil. The mechanical 
 impurities and the bulk of the water subside ; the supernatant 
 liquid is decanted into another vessel, and mixed with a due 
 proportion of coal-oil or spirit, varying in gravity from • 785 
 to • 765. It is then caked, or allowed to fall on a revolving 
 drum, kept cold by an internal flow of water; less oil or 
 spirit — say ^ of the weight of the scales — is required by the 
 
EAW MATBKIALS. 245 
 
 former plan, more by the latter. The cakes or pulp, as the 
 case may he, are then placed between porous or absorbent 
 materials, iisually coco-nut matting lined with canvas. 
 These are arranged in a hydraulic press, fitted with iron 
 plates and wickerwork mats to keep the layers distinct, and 
 are subjected to pressure. This operation is repeated till 
 all the oil and greasy hydrocarbons are removed. "When 
 this is accomplished, the cakes, as removed from the press, 
 should be almost transparent. Instead of employing clean 
 coal-oil or spirit at each operation, some manufacturers, with 
 a view to economy, use the pure liquid for the last wash only. 
 When this principle is adopted, the liquid pressed from the 
 cakes at the last operation is used for those at the second 
 stage, and from that stage again for those at the first stage. 
 Thus the scales are subjected to 3 pressings, which, if done 
 with care, should be sufficient to produce highly refined 
 paraffin. It is obvious, however, that unless the scales have 
 been properly treated by the oil refiners, before coming 
 under the operations described, disappointment and failure 
 will result. It is also clear that the refining will be more 
 perfect by using pure spirit at each operation. 
 
 The oldest form of hydraulic press was the vertical cold 
 press, still used for the commoner kinds of fat. The newly 
 introduced hot presses, on the other hand, are horizontal in 
 shape, and altogether of superior construction. They are 
 made by Needham and Kitfe, of VauxhaU ; and by Galabrun 
 Treres, of Paris. Pigs. 73, 74, and 75 show respectively a 
 front elevation, partly in section, side elevation, partly in 
 section, and a plan, of a novel hot-press specially adapted to 
 the requirements of paraffin, sperm, and stearin refiners. It 
 is made by James Clarkson and Co.,Maryhill Engine Works, 
 Glasgow, from the design of W. WaUs, of that city, through 
 whose kindness the following description and illustrations 
 have been obtained. For convenience in working, and 
 economy of labour, whether as a hot or as a cold press, it is 
 unequalled. The plates A are notched at each end with a 
 check of varying width, corresponding with the diameter of 
 
246 
 
 CANDLES, 
 
 Fig. 73. 
 
 2 vertically tapered bars B, placed at each, end of the press 
 and parallel with its snpporting pillars. The object of this 
 
 contrivance is to do away 
 with the necessity for a 
 balance weight, or other 
 arrangement for bring- 
 ing back the ram, plates, 
 &c., when the press is 
 opened. By this plan, on 
 the ram being lowered 
 by its own weight, each 
 plate falls back into 
 place, being stopped by 
 the increasing size of 
 the tapered bars; thus 
 the plates are held in 
 their places, equidistant 
 from each other, and in 
 a position to render the 
 refiUing of the press a 
 matter of the greatest 
 ease and simplicity. 
 The bottom of the press 
 is cast with a trough 
 on it, which receives 
 all the drippings from 
 the plates, while the 
 cylinder head, and the 
 bottom collars on the 
 pillars, are provided 
 with projecting droop- 
 ing rings ; in this way 
 no oil can escape down 
 the sides of the tapered 
 bars or the pillars, but all must drop into the trough. The 
 press is entirely encased in sheet iron, with hinged doors in^ 
 front, for introducing and withdrawing the materials. A 
 
Pis. 74. 
 
 
 Fig. 75. 
 
 ^ 
 
248 CANDLESi 
 
 perforated eteam-pipe C is introduced at the top of the prees, 
 and is carried down the hack inside ; thence it passes on both 
 sides around the bottom of the trough, for the purpose of 
 keeping the drippings in a liquid state. An outlet pipe is 
 attached to the front or back of the trough, and serves to 
 conduct the oil to a tank. 
 
 The process of purification is simply mechanical ; its 
 efficacy, other things being equal, may be a subject of arith- 
 metical calculation, the factors being the relative quantity 
 of spirit or oil used at each wash, the amount of oil left in 
 at each pressure, and the number of washes. There is, 
 moreover, another matter which exercises an important 
 bearing upon the results, viz. the temperature at which 
 the cakes are cooled after each melting. In the act of 
 cooling, crystallization takes place, and the slower this is 
 performed the more perfect are the crystals. The result 
 is that when a perfectly crystallized cake is subjected to 
 piessure, it behaves like a sponge, yielding up the impurities 
 to combination with the spirit. A quickly cooled cake, on 
 the other hand, may be compared to a piece of pntty or 
 dough, and will not press to advantage, nor yield satis- 
 factory results. The washes containing the impurities, 
 along with paraffin in solution, are, as has been shown, 
 either sent back in the process in bulk, or the naphtha may 
 be distilled off, and the residue returned and treated ah initio. 
 In all cases, the liquid which has been used for the washing 
 at the first stage is the most heavily charged with low 
 hydrocarbons, and must be subjected to distillation. The 
 spirit is separated from this residue by steam heat, and may 
 be used again ; but the heavier portions require treatment 
 with acid and alkali, as in the case of crude oils. 
 
 The cakes, which, by repeated washing and pressing, have 
 been freed from colour, and from the greasy oonstitufents 
 which would spontaneously decompose arid injure the wax, 
 will, even after extreme pressure in hydraulic presses heated 
 by steam, still contain a proportion of naphtha. To get rid 
 of this, the cakes are put into a stiU or rectifier, an iron 
 vessel furnished with a condensing apparatus. Amongst 
 
EAW MATEEIALS. 249 
 
 the melted paraffin, high-pressure steam is introduced 
 through a perforated pipe, and produces violent agitation. 
 This is continued till the last trace of smell is remoTed, 
 12-70 hours being required to effect it, according to the 
 specific weight of the oil or spirit used. The condenser is 
 employed for the purpose of recovering the naphtha for 
 future use. 
 
 The only operation now requiring explanation is the 
 passing of the liquid wax through animal charcoal. Before 
 this process can be applied with effect, every trace of 
 suspended moisture must be removed ; this is done by 
 heating the liquid, as decanted from the rectifier, in a 
 steam-jacketed pan. After the complete removal of the 
 water, freshly burned animal charcoal, to the amount of 
 5-8 per cent., is added to the wax, stirred actively for 
 J hour, and left to settle. The clear liquid is then allowed 
 to percolate through filters, which effectually remove the 
 very fine particles of charcoal that refuse to subside. This 
 liquid, which should now be as pure as water, is put into 
 moulds to cool; when it will be ready for candle-making. 
 
 By the method above described, the very finest " wax " is 
 now made by the Glasgow firms before mentioned. The 
 only drawbacks to this interesting process are the risk of 
 fire, created by the accumulation of inflammable vapour of 
 naphtha, and the loss of volatile materials from the same cause. 
 To obviate these drawbacks, other methods of refining paraffin 
 have been devised and duly patented by their inventors ; but 
 no other process has proved effective in yielding a paraffin- 
 wax of equjal purity and beauty. The patent process adopted 
 by Price's Candle Company, at Battersea, depends upon the 
 fact that paraffins have different melting-points. Oil has a 
 greater solvent power over the low paraffins, consequently 
 when a properly crystallized cake is warmed to a degree 
 below the fusing-point of its higher constituents, the lower 
 grades melt, and carry away with them oil and other im- 
 purities, leaving the former comparatively pure and free 
 from oil. The proportion of oil in these drainings is such 
 that, when caked, they can be pressed without any addition 
 
250 CANDLES. 
 
 of napMha, and can thereafter be mixed with scales for 
 draining again. This operation is performed in "cooking 
 cuphoards," closets about equal in size to an upright hy- 
 draulic press, fitted with shelves formed of double iron 
 plates, each shelf being charged with steam. The hard, 
 partially purified paraffin cakes, which remain on the 
 shelves fii the " cooking cupboard," are melted in a lead- 
 lined vessel heated to 350° F. (177° C), and into them is 
 forced 5-10 per cent, of sulphuric acid, at 169° Tw. (66° B.). 
 Sulphurous fumes are copiously given off, and must be con- 
 veyed away by suitable means. The agitation with steam is 
 kept up for several hours, and by this treatment, all the 
 more unstable hydrocarbons are destroyed, and settle down 
 in the tank. The contents are allowed to stand for a time ; 
 the paraffin is drawn off, treated with weak soda-lye, then 
 digested for a considerable period with animal charcoal, and 
 passed through a filter, heated by a steam-jacket to maintain 
 the fluidity of the mass. 
 
 Several materials have been substituted for charcoal in 
 the above process. In one instance, the addition of about 
 12 per cent, of powdered fullers' earth, at a temperature of 
 230° P. (110° C.) is recommended. The mixture is well 
 agitated, then left to settle, and the clear paraffin is run off. 
 The fullers' earth may be cleansed from paraffin by washing 
 or agitation, and used again. By another process, invented 
 by Smith and Field, silicates of magnesia, and of other bases, 
 may be employed for the same purpose. Moreover, a very 
 ingenious process has been patented by Mr. Sterry, for 
 removing the oil from paraffin without pressing ; it consistB 
 in simply washing or rather kneading the wax with a solu- 
 tion of soap, at a temperature about 9° F. (5° C.) below the 
 melting-point of the paraffin. The paraffin thus produced is 
 pure white, but opaque, hence its use is limited. 
 
 Pure paraffin is sometimes used alone for candle-making ; 
 but it is generally mixed with proportions of hard stearic 
 acid varying from 5 to 15 per cent. The refined paraffin 
 causes the candle to bum with a flame of great power, while 
 the high melting-point of the stearin renders it less liable to 
 
RAW MATEKIALS. 251 
 
 bend under the influence of a warm atmosphere, and to give 
 off smoke during combustion. 
 
 Chemically speaking, the paraffins are true hydrocarbons, 
 and the solid paraffins are the higher terms of the series of 
 which marsh-gas, or methane, CH^, is the lowest; their 
 general formTila is O^Hj^^. The second term, ethane, OjHg, 
 is noteworthy as being the parent of ordinary alcohol, ether, 
 and acetic acid. The sixteenth term, hexdecane, CuHm, is 
 solid at 70° F. (21° C), and the melting-points of the series 
 rise according to their complexity of composition. 
 
 Ozokerit, or Earth-wax. — Although the viscid forms of 
 native bitumen are very numerous, and widely distributed 
 over the world, it is somewhat remarkable that a solid, 
 high-melting-point paraffin is only known to occur in 
 Galicia, where miners' candles have long been made from it. 
 The colour of the mineral varies from brown to greenish 
 and yellow tints ; its fracture is resinous. It contains 85 • 75 
 per cent, of carbon, and 15 • 15 per cent, of hydrogen, and 
 appears to consist of a group of hard, solid hydrocarbons, 
 whose melting-points range from 140° to 176° F. (60°-80° C). 
 Dr. Letheby says that the illuminating power of ozokerit 
 exceeds that of the best paraffins, and is therefore far beyond 
 those of spermaceti, wax, and stearin. The following table 
 shows the number of grains of the various substances enu- 
 merated, required to give the light of 1000 gr. of the best 
 spermaceti candles : — 
 
 Ozokerit 754 
 
 Paraffin 798-891 
 
 Spermaceti 1000 
 
 "Wax 1150 
 
 Various compounds 992-1189 
 Stearin 1200 
 
 The leading properties of ozokerit are : — (1) That it has a 
 very high melting-point, and does not bend or soften in a 
 warm atmosphere ; (2) that it has great illuminating power ; 
 (3) that it burns with a dry " cup," and is not so liable to 
 "gutter" as ordinary transparent candles; (4) that it is 
 entirely free from smell, is not at all greasy to the touch, 
 and has an appearance not unlike that of the finest bleached 
 beeswax. 
 
 To obtain commercial products from the mineral, two pro- 
 
252 CANDLES. 
 
 cesses are employed. One consists in dissolving it in some 
 spirit, filtering the solution through charcoal, and distilling 
 off the spirit from the filtrate. In the second, and most Tisiial, 
 the ozokerit is first heated with fuming snlphnric acid, and 
 then carefully distilled with superheated steam in an ap- 
 paratus similar to that which will he described in the next 
 chapter, for the distillation of the fatty acids of tallow and 
 palm-oil. By Field and Siemssen's patent, the crude wax. 
 is heated and distilled direct with superheated steam, without 
 previous acidification. 
 
 The process of purification by acidification with strong , 
 sulphuric apid gives ceresin, a substance much resembling 
 beeswax in consistency and fracture. By this method, the 
 whole of the mineral is converted into a homogeneous 
 yellow substance, without much loss, except that of filtra- 
 tion, and a certain amount of charred products. This sub- 
 stance (ceresin) is, however, useless in candles, as it smokes 
 persistently. By Field and Siemssen's patent, the ozokerit 
 is melted, and introduced directly into the still, whence 
 it is distilled by bottom heat and superheated steam. 
 This process yields about 50 per cent, of hard white paraffin 
 (140° M.P.), 35 per cent, of black paraffin 170° M.P. (em- 
 ployed in insulating materials for electrical purposes), and 
 15 per cent, of oil and soft grease (ozokerine, a substitute 
 for vaseline.) 
 
 When thus purified, the ozokerit resembles fine beeswax 
 in colour, but is more translucent than wax, though less so 
 than paraffin. The hardness and high melting-point [142° F. 
 (61° C.)] of the candles made from this source give rise to a 
 drawback, common to wax candles, viz. the smouldering of 
 the wick on extinction. The immediate cause of this is the 
 fact that the cup of the candle dries and solidifies as soon as 
 the flame is blown out, so that there is no liquid matter left 
 to extinguish the spark. This difficulty is now overcome 
 by a special contrivance of the wick. 
 
( 253 ) 
 
 CHAPTEE XI. 
 
 PEOOESSES FOE THE CONVEESION OF NEUTEAL 
 FATS INTO FATTY ACIDS.— The Manufactdee 
 
 OF CoMMEECIAi " StBAEIN." 
 
 In the first chapter of this book some account was given 
 of the theory of the constitution of fats, oils, &c., and of the 
 masterly researches of Chevreul into their real nature ; in 
 the present one, an acquaintance on the part of the reader 
 with what is there stated, will be tacitly assumed. From a 
 keen eye like Chevreul's it was impossible that the intrinsic 
 value of his discoveries could long remain concealed, and in 
 1825, in conjunction with Gay-Lussac, he started a factory 
 for the manufacture of stearic acid. Chemical knowledge, 
 however, is seldom united in the same person with technical 
 — or rather commercial — success, and the enterprise failed. 
 It was reserved for M. de Milly to reap the harvest which 
 the great chemist had sown, and in 1832 he manufactured 
 near the Barriire de I'Etoile some excellent stearin (i.e. 
 stearic acid) candles which were called by that name. 
 
 One of Chevreul's discoveries was that the removal of 
 glycerin from neutral fats, i. e. their conversion into fatty 
 acids, enormously increased their hardness and illuminating 
 power, so that candles made from the mixture of stearic and 
 oleic acids, resulting from the removal of glycerin from tallow, 
 were less greasy, and gave much more light, than candles 
 made from the same tallow untreated, though they had not 
 so nice a colour. The next step was the separation of the 
 harder from the softer portions of the fatty acids, and it was 
 found that when this was effected by pressure, the oleic acid, 
 in flowing away, carried with it in solution the whole of the 
 colouring matter of the mass, leaving the crude stearic acid 
 
254 PEOCESSES FOE THE CONVEESION OP 
 
 tolerably white. To make it absolutely so, little else was 
 found necessary than repeated pressings at various tempera- 
 tures, the series of operations, after the removal of the 
 glycerin, being purely mechanical. In carrying out this on 
 a manufacturing scale, the expensive alkalies soda and potash 
 were soon replaced by lime, and the preparation of stearic 
 acid by this process is now conducted as follows : — The tallow 
 to be saponified is placed in a large, slightly conical, wooden 
 tun, which is made of oak or cedar, and is tightly bound 
 with iron hoops. Steam is introduced by means of a spiral 
 copper tube, laid on the bottom, and perforated with numerous 
 small holes. An upright wooden shaft, carrying wooden 
 arms fitted with teeth, is fi.xed in the centre of the tun, and 
 revolves during the process. The tuns are arranged in rows 
 in a large room, 2 being required for the completion of each 
 batch. 
 
 In this tun, the tallow is mixed with good slaked lime, 
 made into a thin cream with water. At first, and even for 
 several years, a very large quantity of lime was used, as much 
 as 16 lb. per 100 lb. of tallow, but this was gradually 
 lessened. After tightly closing the tun, steam is introduced 
 from a pipe below, and the contents are boiled for 3 hours. 
 During the boiling the mixture is kept constantly agitated 
 by means of a wooden shaft bearing some horizontal arms, 
 worked by steam power. The action of lime upon the 
 constituents of tallow decomposes them, glycerin being set 
 at liberty, while calcium stearate and oleate are formed. 
 The formation of these salts, which, when mixed together, 
 constitute an insoluble soap, technically called " rock," greatly 
 facilitates the subsequent separation of the solid and liquid 
 constituents of the tallow. To ascertain when the operation 
 is complete, a small portion of the boiling mixture is drawn 
 out in a ladle, and cooled. When cold, the sample should 
 appear perfectly smooth and solid, and should be very brittle, 
 powdering finely in a mortar. When the operation is com- 
 plete, the steam is shut off and the agitator is stopped, the 
 whole contents standing until cool, and the fatty matters 
 
NEUTEAL PATS INTO FATTY ACIDS. 255 
 
 and lime form a solid mass at tlie bottom. They are then 
 dug out and removed to another tun, similar in all respects 
 to the last. Here they are treated with 4 parts of strong 
 sulphuric acid for every 3 parts of lime previously added, 
 and are then heated and agitated in the same manner as 
 before. During the operation, the lime salts are decomposed 
 by the acid, calcium sulphate falling to the bottom, and the 
 fatty acids rising in a thick layer to the surface. Again, the 
 ^whole is permitted to stand ; when cool, the fat is skimmed 
 off and placed in a third wooden vessel, where it is well 
 washed with water and by steam blown into it. The washed 
 fatty acids are next heated to the melting-point, and run into 
 dishes or troughs made of tin; these are placed in a room, 
 the temperature of which is kept at 68°-86° F. (20°-30° C), 
 and left for 2 or 3 days, or until the contents have assumed 
 a granular or crystalline structure, when they are removed 
 from the dishes, and placed in canvas or wooUen bags, or 
 between large square sheets of canvas, and are carefully 
 deposited between the plates of a powerful hydrauUo press. 
 Pressure is exerted gently at first, and is gradually increased 
 until the flow of the liquid oleic acid ceases. The press is then 
 unlocked, and the hard, thin cakes of crude stearic acid are 
 thrown into another wooden tun similar to the others. Here 
 they are melted down by blowing in steam, which is con- 
 tinued for some hours. After settling, the fatty matters 
 are drawn off into tin dishes, and placed aside to cool. The 
 temperature of the room in which the cooling is conducted 
 should be slightly higher than the previous one, or about 
 86° r. (30° C). The dishes should remain here until the 
 contents assume a crystalline structure, when they may be 
 emptied. The blocks are then cut up into lumps, and 
 ground to a mealy powder by means of a rasping machine, 
 worked usually by steam. This powder is gathered into bags, 
 made either of hair or of wool, or both, and is then sub- 
 mitted to a second pressure in another hydraulic press, 
 differing from the former one by having a heating apparatus 
 attached ; the plates should also be heated before the press 
 
256 PEOCESSES FOE THE CONVEESION OF 
 
 is used. The temperature and pressure vary with the 
 material operated on, hut with good tallow, a pressure of 
 6 tons per sq. in. at a temperature of 120° P. (49° 0.) is not 
 uncommon. The necessity for heat in this second pressure 
 is due to the extreme difficulty experienced in eliminating 
 the last portions of oily matter from the fat. When the full 
 pressure is being exerted, the press is left for about 15 
 minutes before being unlocked. The cakes thus obtained are 
 cleaned with a knife, the parings being added to the next 
 batch. They are again , melted by steam, a little wax being 
 sometimes added, in order to destroy the crystalline texture 
 of the stearic acid, which renders it unfit for use in candle- 
 making. 
 
 The arrangement of the apparatus is shown in Fig. 76 : 
 A, tub from which lime is emitted ; B, lead-lined vats with 
 steam-pipe, for boiling fat' and lime ; C, ditto to which rock 
 is transferred, and boiled with sulphuric acid; D, rack 
 holding pans for caking mixed acids ; E, cold press ; F, 
 hydraulic pump ; H, hot press ; I, vat for melting the 
 refined stearin for casting into blocks. 
 
 This finishes the process, and the stearic acid, commercially 
 called " stearin," is melted into blocks ready for use. The 
 oleic acid as it runs from the presses still contains much 
 stearin, which is separated from it by filtration, exposure to 
 artificial cold, &c. As the relative prices of stearin and olein 
 are usually as 50 to 30, attention to these precautions is 
 most necessary. 
 
 The disadvantage of this process is that so much sulphuric 
 acid is required to decompose the lime soap, thereby injuring 
 the colour of the resulting fatty acids. It was soon found 
 that if the saponification were conducted in closed vessels, 
 under a steam pressure of 3 or 4 atmospheres, the amount of 
 lime might be reduced to about 8 or 4 per cent, upon the 
 tallow, thus lowering the cost, and improving the colour, of 
 the product. This modification is still very largely worked, 
 especially in America. Subsequently it was discovered by 
 Mr. Tilghmann, who patented the process in 1854, that if 
 
NEUTRAL FATS INTO FATTY ACIDS. 
 
 257 
 
 sufficiently high temperature and pressure were employed, 
 the lime might be dispensed with altogether, and that thg 
 resolution of the fat into 
 fatty acids and glycerin 
 might be effected by 
 steam alone. This pro- 
 cess, known as the 
 " autoclave," has been 
 largely worked, both in 
 Europe and America ; 
 but in consequence of 
 numerous accidents, 
 
 arising from the explo- 
 sion of improperly con- 
 structed vessels, it is 
 usual to decompose tal- 
 low at a lower pressure, 
 with the aid of 2 or 3 per 
 cent, of lime, the subse- 
 quent operations of crys- 
 tallization of the fatty 
 acids, hot and cold 
 pressing, &o., remain- 
 ing the same. As at 
 present conducted by 
 the large London candle- 
 makers, about 1 ton of 
 fat, usually mixed tal- 
 low and palm-oil, is 
 heated with 2 per cent, 
 of lime, and |- the fat- 
 volume of water, in an 
 upright Papin's digester, 
 at a pressure of 8 atmo- c^^ 
 spheres (about 110 lb.) " 
 for 4 hours. The whole is then blown-out into a tank, and 
 the " sweet- water" is run off. The subsequent processes are 
 
258 PROCESSES FOE THE CONVEBSION OF 
 
 detailed above. Another very recent modification of this pro- 
 cess consists in replacing the 2 per cent, of lime in the above 
 operation by a fraction of 1 per cent, of zinc oxide ; this is 
 fully described in the chapter on Glycerin, and will probably 
 prove of more value to the soap-maker than to the candle 
 manufacturer. 
 
 The next advance -was the discovery that when neutral 
 fats are exposed to a very high temperature, 572° T. (300° C), 
 or above, in presence of superheated steam, they are de- 
 composed, and the fatty acids are volatilized ; and that when 
 these vapours are condensed, the fatty acids are almost white : 
 that, in fact, fatty acids may be distilled, almost unchanged, 
 in an atmosphere of superheated steam. It was impossible, 
 however, to conduct this process on a large scale, in conse- 
 quence of the simultaneous production of acrolein, a vapour 
 resulting from the decomposition of glycerin, and possessing 
 intensely irritating properties ; but in 1841, it was discovered 
 that if neutral fats were treated first with concentrated 
 sulphuric acid, and then boiled with water, they might be 
 distilled without any such inconvenience, and the problem 
 was thus solved by Dubrunfaut. In 1842 and 1843, Messrs. 
 Jones and Wilson, under the name of Price and Co., took out 
 two patents for the combined treatment of fatty bodies by 
 sulphuric acid and water successively, and their subsequent 
 distillation by the aid of superheated steam. From that 
 time to the present, this process has been worked, in its 
 various modifications, on a most extended scale, especially in 
 England. It gives a much larger quantity of material, of 
 good colour for candle-making, from a given weight of fat, 
 than any other known process. The candles are not so hard, 
 nor quite so white, as the Continental bougies of stearic acid ; 
 but while tallow, treated by the saponification process, yields 
 only about ^ its weight of candle material, tallow and palm- 
 oil, when distilled, give at least 75 per cent, of such material, 
 of a slightly inferior quality. 
 
 The most perfected form of apparatus now used in the 
 distillation process, as made by Merry weather and Sons, of 
 
NEUTBAL FATS INTO PATTY ACIDS. 
 
 259 
 
 London, is shown in Fig. 77. The process is conducted as 
 follows : — The fat is melted from the casks in which it is 
 stored, hy means of 
 a steam jet inserted 
 in the bunghole, and 
 runs into the under- 
 ground wooden tank 
 A, where it is left 
 for some hours to 
 settle the condensed 
 water out of it. 
 Hence it is pumped, 
 by means of the 
 gun-metal lift- and 
 force-pump C, into a 
 series of lead-lined 
 collecting tanks B, 
 fitted with steam 
 coils, by which the 
 material is boiled 
 before being passed 
 through the tap c 
 to the vessel D. 
 This latter, which 
 is known as the 
 "acidifier," is made 
 of stout copper, sup- 
 ported either on 
 wrought - iron gir- 
 ders or on brick- 
 work. It is fitted 
 with a valved pipe a, 
 for the admission of 
 superheated steam ; 
 a copper pipe with 
 water-shower pipe 
 d, for condensing 
 
 B 2 
 
260 PROCESSES FOE THE CONVEESION OF 
 
 the vapours generated hj the acidifying process ; a thermo- 
 meter b, for guidance as to temperature ; also a gun-metal 
 cover e, at the lower side, for cleaning out, and to which is 
 affixed a tap /, for drawing off the acidified materials. On 
 admission to D, the fats are heated for a certain time, by 
 the introduction of superheated steam, at a temperature of 
 ahout 350° F. (176° C), from the superheater T, constructed 
 from the special design of Mr. Ed. Field, C.B. Sulphuric 
 acid in the proportion of 3-6 lb. per cwt. of fat is next 
 supplied to the acidifier from the tank E by opening the 
 plug g. When the acidifi'cation is complete, the material is 
 left to stand for about 6 hours, and is then discharged into 
 a series of lead-lined, open washing-vats G, provided with 
 copper steam coils, and containing water and a little sul- 
 phuric acid. Here it is boiled with free steam for another 2 
 hours, and is left for about 24 hours to settle ; it is then 
 drawn off into the tank A, and pumped through the tap c' 
 into a large, open, lead-lined tank H, placed at a sufficient 
 elevation. This tank is fitted inside with a coil, which is 
 charged with steam, to keep the contents in a liquid state. 
 By means of the valve h, about 5 tons of the material is run 
 into the still I, consisting of an iron body and copper dome ; 
 it is fitted with a thermometer i, and the necessary taps of 
 copper or gun-metal. The contents of the still are heated, 
 by fire, to a temperature of about 240° F. (116° C.) ; super- 
 heated steam, at about 560° P. (294° 0.) is then admitted by the 
 pipe m from the superheater N, and the process of distillation 
 commences. The temperature must be regulated according 
 to the quality of the material operated upon. The vapours 
 pass over by the pipes n to the refrigerator K, which consists 
 of a series of vertical copper pipes, connected at top and 
 bottom by gun-metal bends. These pipes are mounted on 
 iron frames, over a set of 6 circular iron tanks 1e, into which 
 they can be emptied. The tanks are furnished with pipes 
 for the admission of steam, and with spiral copper cooling- 
 coils, through which cold water may be passed. The " essence- 
 tank'' I is fitted with an improved shower-pipe L, which 
 
NEUTRAL PATS INTO FATTY ACIDS. 261 
 
 prevents any vapour passing away uncondensed. The pipe 
 M conveys vapours to be burnt in tlie flue. The fatty acids 
 are collected in pails from the mouths or outlets of the copper 
 coils, the greater part in a fit state for candle-making, with- 
 out the necessity for putting them through hydraulic presses. 
 That part which is not fit for candle-making, as it comes 
 direct from the still, is pressed and redistilled. As the result 
 of distilling tallow, it may be mentioned that out of every 
 100 lb. subjected to this process, 78-80 lb. of crude stearic 
 acid is produced ; f of this, or about 60 lb., is ready for 
 making stearin (i.e. stearic acid) candles without farther treat- 
 ment : the remaining fourth, about 20 lb., after being pressed 
 and redistilled, yields about | of stearic acid and J of oleic 
 acid. Thus the total proportion of the latter product is only 
 5 lb. Besides the stearic and oleic acids, there is a large 
 quantity of a third product, called " pitch." If allowed to 
 get cold, this is a hard, black substance ; but provision is 
 made for passing it at once to an iron vessel, where it is 
 submitted to great heat, and yields a product similar to that 
 obtained by the distillation process, and which is often used 
 in the preparation of "composite" candles, though much 
 inferior to the pressed and purified material. The pitch, 
 after this operation, becomes a commercial article of many 
 uses, and will in all probability soon be recognized as an 
 efSoient substitute for " black-japan," for coating iron, the 
 latter article being worth from 20s. to 30«. a gal. The approxi- 
 mate cost of the plant required for distilling tallow or palm- 
 oil according to the above process, exclusive of steam boiler, 
 may be stated at 1700?. to 3150Z., according to whether 1 ton 
 or 3 tons are to be distilled at a time. 
 
 Palm-oil is now used in enormous quantities for the pro- 
 duction of palmitic acid at Price's Candle Company's works, 
 as well as by almost every candle manufacturer iu Great 
 Britain, about 25,000 tons being annually consumed. In 
 many Continental countries, a prohibitive duty prevents its 
 employment. The plant and the modus operandi scarcely 
 differ from those last described. The distilled mixture of 
 
262 PEOCESSES FOR THE CONVERSION OF 
 
 palmitic and oleic acids, is cut into shreds, by means of a 
 revolving knife, and the shreds are wrapped in canvas or 
 ■woollen cloths, spread in even layers between mats of coco- 
 nut fibre, and submitted first to the cold press, and after- 
 wards to the hot press, at a temperature of 85°-90° P. 
 (29°-32° C). The pressed cakes of fat are pared, and then 
 melted again by steam, in large, wooden, iron-bound vessels, 
 containing water and sulphuric acid. The whole is boiled 
 for a time and is then allowed to stand, after which the 
 acidulated water is drawn off. The melted fat is repeatedly 
 washed with hot water, and then run into moulds ; when 
 cold, it is quite pure, and ready for manufacture into candles. 
 From this palmitic acid, the finest composite candles are 
 m.ade, the well-known " Belmont Sperm " for example being 
 produced by hot-pressing the distilled palmitic acid.* Of 
 late years, a quantity of inferior stearin (using the word in 
 its commercial sense) has been prepared from what is tech- 
 nically known as " recovered grease." In spinning wool, 
 it is necessary to lubricate it with a certain amount of oil, 
 which afterwards has to be washed out. From these and 
 other processes in woollen mills, large quantities of wash- 
 waters are run to waste, containing soap in solution, and oil 
 in suspension. In many factories, and especially in those 
 localities where it is forbidden to pollute the rivers, these 
 wash-waters are run into tanks, where enough mineral acid 
 is added to give them, after thorough agitation, a faintly acid 
 reaction. After some hours, the contents of the tank divide 
 themselves into (1) a greasy dirty scum, (2) clear water, 
 (3) greasy mud on the bottom. The clear water is run away, 
 and the residue, after draining, is packed in canvas bags and 
 placed in hydraulic presses, which are slightly heated during 
 the operation. "Water and crude fatty acids are expressed, 
 and separate from each other by subsidence ; the fatty acids 
 
 * In the Journal of the Society of Aits for 1852 is an excellent lecture 
 upon the history of the stearin industry, by Mr. G-. F. Wilson, of Price's 
 Patent Candle Company, who should perhaps rank next to Chevreul for 
 his share in developing it. 
 
NEDTEAL FATS INTO FATTY ACIDS. 263 
 
 are then pressed and distilled as described above, the yellow 
 hard portions being used for low class candles, and the oil 
 used over again in the mill. 
 
 It will be observed that 3 processes for the decomposi- 
 tion of neutral fats have now been described — viz. (1) By 
 saponification with a strong alkali, at a temperature but 
 little above 212° F. (100° C); (2) By the use of water, 
 with or without a very small quantity of lime, at very great 
 steam pressure, and a correspondingly high temperature ; 
 (3) By treatment with strong sulphuric acid and water in 
 successive portions, and subsequent distillation at normal 
 atmospheric pressure, but at a dangerously high tempera- 
 ture—above 572° F. (300° C). It was reserved for a 
 physician at the Danish Court, the late Dr. J. C. A. Bock, to 
 demonstrate the important fact that, by properly conducting 
 the operation, water alone might be made to decompose 
 tallow into fatty acids and glycerin, and that by the use of 
 water and sulphuric acid combined, fatty acids might be 
 prepared from tallow in open lead-lined tanks furnished 
 with steam coils,— without any of the complicated and 
 dangerous apparatus required by the " autoclave " or the 
 " distillation " processes, without any lime or other alkali, 
 and with a much less expenditure of acid than was required 
 by any other process. Unlike many inventors, he was able 
 to carry out his ideas into actual practice, and in the 
 International Exhibition held in London in 1862, were 
 shown some beautifully white and hard stearic acid candles, 
 which had been prepared by this process in the manufactory 
 of 0. F. Asp, Prindsessegade, Copenhagen. Since then, the 
 process has been constantly at work ; it has also been 
 adopted in several other Continental candle factories, and 
 among other places, in New Zealand. The simple character 
 of the " plant " required renders it peculiarly valuable for 
 countries distant from great manufacturing centres. Con- 
 sidered from a theoretical point of view, it is, perhaps, the 
 most ingenious and the most strictly scientific of all the 
 methods for decomposing neutral fats. 
 
264 PEOCESSES FOE THE CONVEESION OF 
 
 Dr. Book pointed out that tallow is composed of exceed- 
 ingly minute globules of fat, surrounded by membranous 
 envelopes, composed, probably, of albumen j and tbat until 
 these enveloping walls are destroyed, no reagent can act upon 
 the fat within. In ordinary saponification, the albuminous 
 envelopes are dissolved by the caustic alkali ; in acidifica- 
 tion, they are burned and charred by the strong sulphuric 
 acid, the quantity of which may be so adjusted as not to 
 burn and discolour the tallow itself, which, after pouring out 
 from the destroyed envelopes, is in a state to be readily 
 decomposed by water at 212° P. (100° C). Dr. Bock's pro- 
 cess was described by him in an article in Dingler's 
 ' Polytechnisches Journal,' for May 1873, of which the 
 following is a synopsis. 
 
 By the lime saponification plan, the albumen contained in 
 the fat is dissolved, lime-soap is formed, and the extraction 
 of the glycerin is rendered possible. By acidification, the 
 whole process is effected at once. Conducted properly, the 
 fat, washed out with water, always remains as neutral fat, 
 and, by the use of concentrated sulphuric acid, not a trace of 
 glycerin is left. Acidification, rationally conducted, is only 
 a preliminary operation, intended to break up, corrode, or 
 carbonize, the albumeniferous matters. But the conduct of 
 the operation was long based on the erroneous belief that a 
 double acid, sulpho-stearic, was formed. With due care, 
 only the envelopes of the cells are blackened, and these are 
 soluble neither in fat nor in fatty acids. The production of 
 a real black solution is only an evidence that a certain part 
 of the fat has been burned, which should be avoided under all 
 circumstances. There is no doubt that the operation has 
 generally been carried to excess, in the matters of duration, 
 height of temperature, or strength of acid. By proper 
 acidification, the neutral fat is only unclothed, as it were, and 
 freed from the cells, or at any rate, the latter are so ruptured 
 as to allow of the easy exit of the fat. This latter is then 
 in a condition to be decomposed, an operation accomplished 
 in much shorter time by the chemical equivalent of acid — 
 
NEUTRAL FATS INTO FATTY ACIDS. 265 
 
 4-4^ per cent. — and the necessary water. After letting out 
 the glycerin waters, the fatty acids appear more or less 
 black. They may now be distilled. Their melting-point 
 varies from 120° to 134° F. (49°-57° C). 
 
 The real valne of Dr. Bock's method consists in dispensing 
 with distillation. The object of this operation is the removal 
 of the black colour, or rather of the black-coloured matters, 
 by superheated steam. These black matters are the partially 
 carbonized albumen cells, which swim about in the fatty 
 acids because the sp. gr. of the two bodies is about the same. 
 This difficulty is overcome by oxidizing the mass, by which 
 the sp. gr. of the cells is raised from 0-9 to 1 • 3. They are 
 thus precipitated, and the fatty matters can be washed off. 
 The subsequent cold and hot pressings are the same as with 
 ordinary methods. 
 
 From several years' experience at the works of Messrs. 
 Asp, the following results have been deduced. Tallow 
 yields, by complete decomposition, 95 per cent, of fatty acids, 
 which lose 2 per cent, by oxidation and washing. The 
 glycerin obtained equals 6|- per cent, from tallow at 88° Tw- 
 (23° B.), and is quite free from all organic acids. The oleic 
 acid resembles that produced by the lime saponification 
 process; but it is much richer in solid acid. The stearic 
 acid is also like that produced by the lime saponification 
 method ; but it is much harder, and its melting-point is 
 136°-140° F. (58-60° C). It amounts to 55-60 per cent, of 
 the tallow employed. 
 
 The plan is free from danger, as the steam is only used in 
 open vessels. The plant is much cheaper, as nothing special 
 is required. The labour also is much reduced, as the opera- 
 tion is completed in one vessel. It is as applicable to 
 vegetable as to animal fats. 
 
 The process indicated above has now been for many years 
 in daily operation on a manufacturing scale in Copenhagen, 
 and, in the hands of the inventor and his son, Alexander 
 Bock, has been greatly improved and simplified since its 
 first introduction. At that time, there were 6 stages in the 
 
266 PROCESSES FOR THE CTONVERSION OF 
 
 process, viz. : — (1) Acidification, to remove the membranous 
 cellular tissue from the tallow; (2) Decomposition, by 
 acidulated water, into dark fatty acids and glycerin; (3) 
 Oxidation, to increase the sp. gr. of the dark membranous 
 matters, so that they might separate themselves from the 
 fatty acids ; (4) Eepeated washings with water ; (5) Press- 
 ing, both cold and hot. 
 
 The greatest improvement is due to the discovery that the 
 dark membranous matters may be oxidized while the fat is 
 still neutral. The acidification, oxidation, and decomposi- 
 tion are all now conducted, in rapid succession, in one and 
 the same wooden tank, after which, one or two washings in 
 another tank render the fatty acids fit for the press. 
 
 Another point of great practical importance, which has 
 been developed in the working out of this process, is the 
 increased hardness of the stearic S-cid produced by it, arising 
 from the solidification of some of the oleic acid in the tallow, 
 by the prolonged action of sulphuric acid upon it. This 
 reaction has lately been pointed out as a novelty, by 
 Bornemann and Kraut ; but it was suspected some years ago, 
 and soon afterwards was definitely proved,, by the Messrs. 
 Bock. They observed that the fatty acids became harder 
 and harder, so that cold pressure had no effect upon them ; 
 by the adoption of hot-pressing, they produced white stearic 
 acid, and an exceedingly brown oil. This latter, when dis- 
 tilled, saved the cost of distillation, by its yield of solid 
 matters. It is claimed, therefore, for the Bock process, that 
 stearic acid can be made of better quality and in larger 
 quantity from a- given weight of tallow, than by any other 
 process at present known. 
 
 Conversion of Oleic into Palmitic Acid. — -Whichever of the 
 4 processes (lime-saponification, autoclave, distillation, or 
 Bock's) is employed, a large proportion of oleic acid is 
 unavoidably produced. The quantity of it, per ton of 
 neutral fat, varies in inverse proportion to the hardness of 
 the original fat, or of the material manufactured from that 
 fat. For many years, it was difficult, at any rate in England, 
 
NEUTBAL PATS INTO FATTY ACIDS. 267 
 
 where soft soaps are muoli less used than on the Continent, 
 to find a suitable outlet for this oleic acid : it could not be 
 used as a lubricant, owing to its acid reaction upon metals ; 
 when saponified by the ordinary methods, it produced a very 
 soft and very brown soap, slow of sale. It was discovered, 
 however, that when saponified with soda-lye of very high 
 specific gravity, a hard soap could be made from it, contain- 
 ing a very large percentage of fatty acids, and good for 
 ordinary cleansing purposes, but whose smell was considered 
 objectionable. It was, nevertheless, found to possess certain 
 special advantages for many manufacturing purposes, espe- 
 cially in the woollen industry, and accordingly it finds a 
 ready sale under the name of " pure-oil soap " (pp. 145, 
 147-8, 224). A few years ago, moreover, M. Eadisson, of 
 Lyons, taking advantage of a laboratory reaction of oleic 
 acid which had long been known, developed a method of 
 converting it into palmitic acid, and, by dint of great 
 perseverance, worked out the details of the process on an 
 industrial scale ; it is now a commercial success, and has 
 been patented in nearly all countries where candles are 
 manufactured. Whether it is more economical to convert 
 the oleic acid into soap or into palmitic acid, depends upon 
 the relative cost of the 2 processes, and the current market 
 values of the manufactured products. 
 
 The following information relative to this remarkable 
 process, which is extremely interesting, from both scientific 
 and technological points of view, has been kindly supplied 
 to the writer, by the patentee, M. St. Cyr Eadisson, 37, 
 Boulevard Oddo, Marseilles. 
 
 In 1841, Warentrapp announced that when oleic acid was 
 heated with a great excess of caustic potash, it was decom- 
 posed into palmitic acid, acetic acid, and hydrogen, the acids 
 combining with the potash, the reaction being explained 
 by the following equation : — 
 
 01eic.acld. Pot^. P°fS" ^o^™ Hy^gen. 
 
 CisHajOj + 2KH0 = CeHj.KOj + CjH,K:Oj + H, 
 
268 
 
 PEOCESSES FOE THE CONVEESION OP 
 
 At Marseilles, this has been practically realised, and about 
 3 tons of oleic acid can be daily converted into palmitic 
 acid, by this process ; it is used in the large candle-factory 
 of M. Fournier. The system has also been worked in 
 Copenhagen, in conjunction with the Bock process, and 
 elsewhere. 
 
 The vessel in which the fusion takes place is technically 
 called a cartouche, and is shown in section in Fig. 78. It is 
 a cylindrical vessel A B, 10 ft. 6 in. in diameter, and 4 ft. 
 
 4 in. in height, the 2 
 Ftq. 78. ends being slightly 
 
 " dished," and the 
 bottom made of cast 
 iron, while the sides 
 are of wrought iron. 
 The whole is set in 
 brickwork in such a 
 way that the bottom 
 is at least 5 ft. 9 in. 
 above the fire-bars M, 
 thus giving a large 
 fire-chamber, a very 
 important point in 
 the facility of control 
 of temperature and 
 the maintenance of a uniform heat. The cartouche contains 
 any convenient mechanical agitator C, worked with gearing 
 D, also a manhole E, safety-valve at F, steam and water 
 cocks G H, exit-pipe J for steam and hydrogen, and a large 
 outlet-pipe K, with suitable valve, for removing the fused 
 mass at the end of the operation. In working with caustic 
 potash, the original form of the process, the cartouche is 
 charged with 1650 lb. of oleic acid and 2750 lb. of caustic 
 potash lye at 80° Tw. (41° B.). Heat is gradually applied, 
 and when the disengagement of steam ceases, the manhole E 
 is closed, and the evolved gases pass through J to a coke- 
 tower condenser, and thence to a gasholder. At 554° F. 
 
NEUTRAL FATS INTO FATTX ACIDS. 269 
 
 (290° C.) deoomposition commences and much hydrogen is 
 evolved. From 572° to 590° F. (300°-310° C.) is the proper 
 temperature for the operation, and at 608° T. (320° 0.) the 
 odour of the evolved gas suddenly changes, and the stage 
 of destructive distillation is reached. To arrest this, steam 
 is suddenly distributed through the mass, hy the Gififard 
 injector I. Some 36-40 hours are required for one complete 
 operation, including fiUing and emptying ; its progress is 
 judged by taking samples, decomposing them, and deter- 
 mining (by Dalican's method, p. 96) the solidifying-point of 
 the fatty acids. When the outlet-pipe K is opened, the 
 potassium palmitate falls into an open tank, where the soap, 
 and a quantity of water sufficient to melt it, are heated 
 together by a steam-jet. After subsidence, the contents of 
 the tank divide themselves into an upper layer of neutral 
 potassium palmitate, and a lower layer of potash lye, usually 
 about 28J° Tw. (18° B.). The neutral palmitate is removed 
 to another vessel, and decomposed with sulphuric acid ; the 
 last traces of potassium sulphate are removed by washing 
 with water. 
 
 At this stage, the palmitic acid is of a clear chocolate hue, 
 and when cooled, crystallizes in large tables ; its solidifica- 
 tion-point varies between 122° and 127° F. (50°-53° C), 
 according to the nature of the oleins employed. It can be 
 distilled with great facility in the usual apparatus, and 
 leaves only 3 per cent, of pitch. After distUlation, the 
 palmitic acid is extremely white, and bums with a very 
 clear, smokeless flame. Moulded into candles, it compares 
 very favourably with the best stearic acid ; and when mixed 
 with ordinary stearic acid, it " breaks the grain " of the 
 latter (i. e. destroys its tendency to crystallize), and gives 
 it a semi-transparency, very valuable in the eyes of a candle 
 manufacturer. 
 
 Instead of decomposing the potassium palmitate by 
 sulphuric acid, it may be boiled with mUk of lime, under a 
 pressure of 3 atmospheres, when the result will be a lime- 
 soap, floating in caustic potash lye. So much water, how- 
 
270 PEOCESSES FOB THE CONVEESION OF 
 
 ever,. is necessary for this reaction, that the resulting lye is 
 only 9° Tw. (6° B.), and its concentration to 85° Tw. 
 (43° B.), is so costly, that it is more economical to regenerate 
 the potassium sulphate by Leblano's process. The potash lye 
 may be completely caustioized in the cold at a sp. gr. of 
 32J° Tw. (20° B.) with 6 hours' brisk agitation, thus econo- 
 mizing fuel. The calcium carbonate so obtained is pulve- 
 rulent, and can be easily washed by " displacement " (i. e. 
 running water through it to wash out the potash), in a layer 
 3 ft. thick. The caustic lye is rapidly concentrated to 85° Tw. 
 (43° B.), and stored in tanks, where, on cooling, it deposits 
 the small amounts of potassium sulphate and carbonate 
 which it contains, and the vertical partitions of the tanks 
 become covered with crystals of potassium acetate, arising 
 from the preceding solidification. The perfectly clear lye 
 is then employed in the transformation of fresh portions of 
 oleic acid into palmitic acid. The crystals of potassium 
 acetate are separated by a centrifugal machine, from the lye 
 which hangs about them, and are then taken to a distilling 
 apparatus, where the acetic acid is displaced by sulphuric 
 acid. The crude acetic acid, thus obtained, is purified by a 
 second distillation, and becomes of commercial value. Its 
 quantity should be 2 ■ 5 per cent, of the oil solidified. 
 
 Oleic acid which is the product of the distillation of fatty 
 bodies, contains small quantities of hydrocarbons analogous 
 to natural petroleum. These distil over during the con- 
 version of the potassium oleate into palmitate, and are 
 condensed in a tower, furnished with transverse partitions 
 extending alternately nearly across its diameter. A simple 
 rectification makes them pure enough for illuminating oils, 
 and the paraffin which remains in the heavy portions of the 
 oil can be separated by crystallization in the cold. As a 
 matter of purely scientific interest, it may be mentioned 
 that caprylic alcohol, sebacio acid, caproic acid, and other 
 rare substances, are formed in very small quantities, 
 simultaneously with the palmitic acid. 
 
 All fatty bodies, with the exception of mares' grease, and 
 
NEDTEAL PATS INTO FATTY ACIDS. 
 
 271 
 
 the fat of " suint," can thus be solidified hy the action of 
 caustic potash ; but the ultimate products vary, and the 
 palmitic acid is by no means always pure. Different percen- 
 tages of palmitic acid are obtained in the final result, 
 according to the nature of the fatty bodies employed. Thus, 
 100 lb. of oleic acid, resulting from tallows decomposed by 
 lime, should yield 91 lb. of palmitic acid fit for candle- 
 mating, while 100 lb. oleic acid resulting from distillation 
 processes only yields 87 lb. of white palmitic acid. It may 
 be noted as an interesting fact, that the oleic acid produced 
 by Bock's process is more suitable for conversion into palmitic 
 acid than that produced by either of the other methods. 
 The 2 processes (Bock's and Eadisson's) are worked con- 
 jointly with the most satisfactory results. The percentage 
 of palmitic acid from Bock's oleic acid is higher than from 
 any other. 
 
 The following figures give the cost, in francs per 100 
 Mlos., of white palmitic acid produced from distilled oleic 
 acid :— 
 
 General charges 5-80 
 
 Labour 6'35 
 
 Lobs of alkalies 2 ' 60 
 
 Fuel for all operations .. 8 "10 
 
 Calcium carbonate . . . . ■ 60 
 
 Caustic lime 0'65 
 
 Sulphuric acid 2-60 
 
 Wear and tear of plant .. 0'95 
 Distillation 3 '50 
 
 31-15 
 
 or a total of about 13Z. a ton. 
 
 The expense of the process can be materially reduced by 
 the substitution of soda for potash. Owing, however, to 
 the comparative infusibility, and want of heat-conducting 
 power, on the part of sodium oleate, it is necessary to add a 
 quantity of solid parafSn, in which the sodium oleate is 
 suspended during the operation ; in this way an equilibrium 
 of temperature is speedily distributed throughout the whole 
 mass, and there is no fear of heating the sodium oleate to its 
 decomposing-point, since that is higher than the tempera- 
 ture at which paraffin distils. When the mass is treated 
 with water, the paraffin forms the topmost layer, and can be 
 completely separated. The loss in manipulation is found 
 
272 CONVEBSION OF NEUTRAL FATS INTO FATTY ACIDS. 
 
 not to exceed 1 per cent, of the oleic acid originally taken, 
 and the cost of the conversion is about 71. 10s. per ton 
 instead of 13Z. M. Eadisson suggests as a still further 
 reduction, the use of heavy hydrocarbon oils for paraffin 
 and of the caustic " red liquors " from a Leblanc soda factory, 
 estimating that the cost might thus be reduced to as low as 
 10 frames per 100 kilos., or about il. 5s. per ton. 
 
 M. Eadisson claims the following advantages, as accruing 
 to the stearic acid manufacturer from the adoption of his 
 process : — 1. Utilization of the olein, a troublesome by- 
 product of variable value ; 2. The floating capital necessary 
 for the purchase of raw material is diminished by about 30 
 per cent., the production of stearin being increased by nearly 
 the amount of olein produced ; 3. The manufacturer can use 
 low-priced greases, whose value varies in inverse proportion 
 to their richness in olein ; 4. The stearin produced by this 
 process is little, if at all, inferior to that produced by any 
 other process. 
 
 Writing, in 1878, a short account of his enormous candle- 
 factory, and of the objects which he exhibited at the 
 Industrial and International Exhibition in Paris, Pournier 
 says of this process — " La stearinerie a done pris possession 
 d'une maniere definitive de ce nouveau precede si important 
 pour son avenir. Cette transformation est la nouveaute 
 la plus saillante qui ce soit produite dans I'industrie 
 stearique depuis I'Exposition de 1867." 
 
( 273 ) 
 
 CHAPTER XII. 
 
 THE MANUFACTUEE OF CANDLES AND NIGHT- 
 LIGHTS ; — Their Yalue as Illuminants. 
 
 A CANDLE consists essentially of 2 parts : (1) the combus- 
 tible material; and (2) a porons substance through, the 
 medium of which combustion takes place. The first portion 
 of the candle, the combustible material, has been fully dealt 
 with in the two preceding chapters, and the second portion, 
 or the wick, the type of which is found in the rushes em- 
 ployed by our forefathers, is usually made of cotton. The 
 chief essential qualities of a wick are good power of ab- 
 sorption, and a capacity for burning freely, evenly, and 
 thoroughly, while producing the least possible proportion 
 of ash. It must necessarily be quite free from inequalities 
 of whatever kind, and should be made of perfectly sound 
 fibres. The forms and kinds of wick differ widely with 
 the quality and composition of the candle ; the melting- 
 points, and other characteristics of the hydrocarbons forming 
 the candle, vary to such an extent that, in order to bum to 
 the best advantage — or indeed, in some cases to bum at 
 all — each sort of candle needs to be accommodated with a 
 special wick. One of the greatest secrets of candle-making 
 is to have the wick perfectly suited to the peculiarities of 
 the fatty matters employed ; on this score, it is impossible 
 here to do more than indicate the principles involved. 
 
 But little variety is to be remarked in the choice of 
 material for making wicks. The original, and not yet obso- 
 lete, medium was the common soft rush, Juncus conglomeratus, 
 to be found in most moist pastures, and by the sides of 
 streams and ditches. The rushes are in best condition in the 
 height 'of summer, but may be gathered on to the autumn. 
 
 T 
 
274 THE MANUFACTURE OF 
 
 As soon as out, they are placed in water, otherwise they 
 would dry and shrink, and the peel would not run. They 
 are then stripped of half the peel, the object of which is to 
 expose the pith sufficiently to enable it to conduct the molten 
 fat, while enough of the rigid epidermis remains to afford it 
 support. When duly peeled, they are laid out to bleach 
 and take the dew for some nights, and are afterwards dried 
 in the sun. These rushes are gathered in Lancashire, and 
 abundantly in the Ten Country, and in Ireland. Candle- 
 wicks are ordinarily made of fine cotton yarn; Turkish 
 cotton rovings are said to be the best, but of the cotton 
 employed for this purpose there is certainly a great deal 
 more imported from the United States than from Asia 
 Minor. The wicks of night-lights vary greatly in composir 
 tion, according to the fancy of the manufacturer. Sometimes 
 little sections of rush are used, as well as very fine cotton 
 yarn ; but the majority consist of " inkle," a fine flax yarn. 
 
 The manufacture of cotton and flax wicks is now per- 
 formed almost exclusively by machinery, the threads of 
 fibre being bound together either by twisting or by 
 braiding. For dip candles, the wicks require to be bulky 
 and of loose texture, in order that the melted tallow may 
 rise freely. They are therefore made by twisting, and 
 ooastitute the simplest form of wick after rushes. The 
 cotton yam chosen for the purpose must be " oozy " or furry, 
 and the threads must be free from twist. This is placed 
 ready balled in the cutting machine, a simple contrivance 
 already repeatedly illustrated elsewhere. By it, the yarn 
 iSi doubled in proper lengths around a rod ; a knife then de- 
 scends and severs the yarns, to which a twist is communicated, 
 by means of a rolling apparatus worked by a treadle. The 
 twist is secured by dipping the wicks at once in molten fat. 
 
 Twisted wicks have a great drawback, inasmuch as they 
 are only very partially consumed in the flame, and thus 
 necessitate the troublesome operation of snuffing. The first 
 attempt to remedy this evil was made by Price's Candle 
 Company, on the occasion of the Queen's marriage. The 
 
CANDLES AND NIGHT-LIGHTS. 275 
 
 candles were made self-Biiuffing, hj means of plaiting the 
 wick, and " gimping " strings of wire, or other fibrous 
 material, into the plaits, with the object of bending the 
 wick outwards, so that the end of it should reach the oxi- 
 dizing part of the flame, and thus be destroyed. Mr. Palmer 
 in his "Metallic Wick Candles" introduced a fine thread 
 impregnated with impalpably powdered bismuth, into the 
 body of the wick, which consisted of parallel fibres bound 
 together by one wound round them. The bismuth fuses 
 into a little ball, the weight of which draws the wick later- 
 ally out of the flame into contact with the air, having per- 
 formed which duty, the bead oxidizes and disappears, by 
 volatilization or otherwise. A simplification of this plan 
 consisted in plaiting the wick with strands of unequal 
 length, by which the same result was d,ttained. In these 
 cases, the wick was round. At the present day, plaited 
 wicks are made flat, by which means they acquire a natural 
 inclination to bend. For .all kinds of moulded candles, 
 plaited, or in technical language, " braided," wicks are used, 
 the old-fashioned twisted wick being reserved for " dips." 
 
 An improved form of wick-plaiting machine is shown in 
 Fig. 79 ; of a triple set, one apparatus only is seen. The 
 contrivance is simple, but very ingenious. The strands of 
 cotton yam are carried on 3 revolving bobbins, whose 
 gyrations are regulated by the beater beneath. The 
 plaited wick is passed away in an endless rope over the 
 wheels. In principle, this is identical with ordinary 
 braiding machines, but it differs from them in always 
 having but 3 bobbins. Given proper materials, the suc- 
 cess of a wick depends upon the manner in which it is plaited, 
 and especially upon the relative tightness of the plaiting. 
 Stearin candles require a moderately tightly braided wick ; 
 for paraffin, the braiding must be extra tight ; for sperm and 
 wax, on the other hand, it needs to be unusually loose. Few 
 candle-makers plait their own wick, at least in any quantity ; 
 they prefer, in most instances, to entrust the work to cotton 
 spinners who make it more or less a specialty. 
 
 T 2 
 
276 
 
 THE MANTJFACTUEE OF 
 
 After being twisted or plaited, tlie wicks are bleached in 
 the ordinary way, and thoroughly dried. Before being used 
 
 Fig. 79. 
 
 by the candle-maker, they are dipped in a bath of pickling 
 liquor, the effect of which is to retard combustion, and to 
 
CANDLES AND NIGHT-LIGHTS. 277 
 
 help in causing the destruction of the ash. The pickle 
 most commonly employed is a solution of about 1 lb. of 
 boracic acid in 75 pints of water; in this, the wicks are, 
 soaked for about 3 hours. When taken out, they are either 
 wrung, or put into a centrifugal machine, to remove the 
 first excess of water, and are then completely dried in a 
 tinned-iron box, provided with a steam jacket. Various 
 other pickles are recommended; the principal are — (1) A 
 solution of 5 to 8 grm. of boracic acid in 1 litre of water, to 
 which 0*3 to 0*5 per cent, of sulphuric acid has been added ; 
 (2) a solution of ammonium phosphate (used in some Austrian 
 works) ; (3) a solution of sal-ammoniac at 3°-4^° Tw. (2°- 
 3° B.) (proposed by Dr. Bolly) ; (4) a solution of 2 oz. borax, 
 
 1 oz. potassium chloride, 1 oz. potassium nitrate, and 1 oz. 
 ammonium chloride in 3 qt. water; (5) the wicks of the 
 newly-introduced " snuffless dips " are plaited, and are then 
 soaked in a solution of bismuth nitrate. 
 
 Having described the nature and preparation of the 
 materials which, in one form or another, constitute the 
 
 2 component parts of every candle, the next consideration 
 will be the manner in which their combination is effected. 
 Three plans are in vogue, each exceedingly simple ; dipping, 
 moulding, and pouring. The first is employed for common 
 tallow candles, which are accordingly called " dips." The 
 rods supporting the twisted wicks, as they come from the 
 twisting and cutting machine, are transferred to a frame 
 capable of being raised and lowered at will. This commonly 
 takes the form of a beam, but a better arrangement is seen in 
 Fig. 80. The frame, made of iron, and capable of revolving, 
 is so suspended that a perfectly horizontal position is always 
 maintained, even under undue pressure at either end; in 
 this way, are secured a uniform length of candle and a 
 plumpness at the top, which is difficult of attainment, even 
 by skilful workmen, by the ordinary beam. Under the frame 
 are placed troughs containing melted tallow, into which the 
 suspended wicks are repeatedly dipped. After each dipping, 
 the adherent fat is allowed to cool sufficiently to retain a new 
 
278 
 
 THE MANUFACTURE OF 
 
 coating on fresli immersion. The process is renewed until 
 the candles have grown to the proper thickness ; they are 
 then left to cool and harden. Dip candles are still largely- 
 manufactured, and are much" employed in mines and small 
 
 factories, and hy 
 ^^^- ^^- domestic servants, 
 
 as well as in cot- 
 tages ; but within 
 the last 3 or 4 years 
 they have there 
 heen largely re- 
 placed by the small 
 moulded "cottage 
 composites," made 
 from distilled fatty 
 acids, with a self- 
 consuming wick. 
 These are, in fact, 
 small and cheap 
 composite candles, 
 tallow "dips," and 
 
 as the old 
 
 made in the same sizes 
 at nearly the same price. 
 
 Pouring is used only with wax candles, which cannot be 
 moulded, for the candles refuse to leave the moulds, or crack 
 while doing so. The wicks are placed upon a horizontal 
 hoop, and the operator, holding this with one hand, pours 
 the previously melted wax over the wicks with the other. 
 After 3 or 4 revolutions, that hoop is laid aside, and another 
 substituted. At a certain period the candles are reversed, as 
 there is a natural tendency to thicken at the lower extremity. 
 They are then rolled on a marble slab, under a weighted 
 board, and are trimmed to the required length with a knife 
 and gauge. A well-made wax candle should show rings like 
 a tree, where the different layers have been superposed. 
 
 By far the greater number of candles now manufactured 
 are moulded, by which they acquire a much more finished 
 appearance. The most simple form of moulding machine is 
 
CANDLES AND NIGHT-LIGHTS. 279 
 
 that known as the ',' hand-frame," which is in. use only among 
 small manufacturers, and for particular kinds of candles, 
 hought by those who, for reasons best known to themselves, 
 prefer " hand-made " articles. The hand-frame contains from 
 3 or 4 to 3 dozen mould-pipes (each making one candle)^ 
 held together by woodwork, and opening into a trough at 
 the top, their points heing downwards. The wicks are cut 
 to the proper length and proyided with a loop at one end, 
 which is caught by a long crochet-hook, and thus one wick 
 is drawn into each pipe, where it is secured hy a peg at the 
 tip, and a cross wire at the " butt " end of the candle. The 
 frames are then heated to a temperature about 10° F. (5J° C.) 
 short of the solidifying-point of the candle-material, which 
 is then poured into them, in the case of fatty acids, as cold 
 as possible, provided that there are no lumps of solid fat in 
 the material as poured. The trough is filled full, to allow 
 for the contraction of the candle when cold, and the super- 
 fluous material is eventually removed with a trowel. The 
 hand-made candle is readily distinguished hy the little 
 groove which the wire wick-holder makes in its hase. 
 
 The machine now usually employed for candle-moulding 
 is an improvement by Mr. E. Cowles upon one introduced 
 into this country from America about 1848-50. 
 
 It is shown in Fig. 81 ; A, standards and water-box, with 
 80-100 candle-moulds partially enclosed ; B, movable clamps, 
 for holding the ejected candles ; 0, handle of eccentric 
 wedge, for opening and closing the clamps; D, pistons, 
 having the tips soldered at the top ends, which are fitted to 
 the lower ends of the candle moulds ; B, cotton bobbins, 
 revolving on strong iron pins ; F, crank handle, for raising 
 the pistons, by the action of which the newly-made candles 
 are ejected into the clamps ; G, handle of gun-metal gland 
 cock, for emptying water-box (this cook is so arranged that 
 it cannot leak or get out of order) ; H, overflow pipe, which 
 prevents the box from being overcharged with water; I, 
 newly made candles, held by clamps while the melted 
 material is being poured in, so that the wick is centred in 
 
280 
 
 THE MANaFACTUEE OF 
 
 each moTild ; J, a clearing pin, to enable workmen to clear 
 the bend of the overflow pipe if it should become choked ; K, 
 a pipe to admit hot or cold water to the water-box. The 
 method of using the machine is as follows : — After having 
 made the connection between the hot and cold water pipes 
 and the machine at K, and having connected the outlet-pipe 
 with a drain, the machine is ready for cottoning. The 
 
 pistons are raised by turning the crank-handle F, until the 
 tips are level with the butt ends of the tin candle-moulds, 
 where they can be held by the pawl catobing in the pinion. 
 A' fine wire, doubled, and of sufBcient length to go through 
 the tip-mould and piston, is then inserted, and extended 
 below the piston sufSciently to enable the operator to pass 
 the candle-wick end through the loop. This permits the 
 
CANDLES AND NIGHT-LIGHTS. 281 
 
 cotton to be drawn up througli the mould ; it must then be 
 secured in any convenient manner during the first filling. 
 The crank F is returned, the melted material is poured in, 
 and the operation is complete. When nearly cold, the butt 
 ends of the candles are shaved off with a tin scoop or a 
 wooden spud. The clamps B should be placed open over 
 the machine ; the crank-handle F is then turned, and the 
 candles are ejected into the open clamps. These are then 
 closed by the handle C, so that each candle is held in its 
 proper position. The crank-handle F is then returned to 
 allow all the pistons to recede into their places : the wicks 
 are thus held in a central position by the candles I and the 
 cotton-bobbins B. The cotton should be slightly strained 
 under the piston plate. The melted material is again poured 
 into the moulds to form a second batch; when these are 
 nearly set, the wicks are severed under the clamps, and the 
 first batch is removed in the clamps. The temperature of 
 the water in the machine is easily regulated, by shutting off 
 or admitting hot or cold water, as required, at the T connec- 
 tion at K. The internal immersion pipes, situated inside 
 the water-box and between the rows of moulds, are per- 
 forated. These machines occupy only about 3 ft. x 2 ft. of 
 space, and are made to mould candles from 1 lb. each to 56 
 to the lb. It is also possible to make candles of 2 different 
 diameters, or several different lengths, in the same machine. 
 A polished appearance is given to the candles by alternately 
 admitting hot and cold water into the water-box; the 
 adjustment of the temperature is an operation needing 
 special experience, the men's fingers forming usually their 
 only thermometer. 
 
 A great improvement in the candle was made in 1861, 
 when Mr. J. Lyon Field patented the conical "butt" by 
 which a candle could be adapted to any candlestick, without 
 paper or scraping. The moulds for the butts used to be cast 
 in a separate frame, which was removed when the candles 
 were finished, by a chain and pulley, and the candles were 
 then pushed out in the usual way. Several different patents 
 
282 
 
 THE MANTIFACTUEE OF 
 
 exist for accomplisHng the same object more neatly. The 
 last patent of Mr. Cowles, the inventor of the candle-machine, 
 raises the bed containing the conical butts, and divides it 
 while rising, thns obviating great loss of time and vpick : in 
 fact, enabling conical ends to be made as easily as plain ends. 
 Another form of moulding machine is shown in Fig. 82. 
 It is manufactured by Galabrun Freres, of Paris, and is in 
 general favour on the Continent; it is said to be capable 
 
 Fig. 82. 
 
 of turning out 200 candles per half hour; but it is only 
 suitable for stearic acid, or similarly hard material. 
 
 When moulded and cold, the candles are taken to little 
 tables, fitted with circular knives revolving at high speed* 
 Here the butt ends are trimmed, and the length of the 
 candles is adjusted to the weight. Some of the superior 
 kinds of candle undergo a special polishing operation, per- 
 formed by subjecting them to the friction of felt and other 
 
CANDLES AND NIGHT-LIGHTS. 
 
 283 
 
 substances. In Fig. 83 is seen a trimming, washing, and 
 polishing machine comhined, as made hy Galahrun Freres. 
 
 The various fancy patterns of candles, spiral, rope-Hie, &c., 
 all require special hand-moulds. The devices to prevent 
 
 
 guttering are endless ; one which answers well for the upper 
 half at any rate, of the candle, is to mould it partially 
 hollow, by inserting 2 or 3 solid rods in the mould, and 
 
284 THE MANUFACTUEB OF 
 
 withdrawing them when the candle is solid. Tor colouring 
 candles, vegetable or anilin dyes are almost always used; 
 mineral dyes are to he avoided, as they seriously interfere 
 with the combustion of the candle. In order to tint paraffin 
 candles with many dyes which are insoluble therein, the dye 
 must first be dissolved in stearin, and then that compound 
 will be readily taken up by the paraffin. As an illustration 
 of the demands made by fashion, it may be mentioned that 
 Price's Candle Company keep 300 varieties of candle always 
 in stock, and are open to make 1000 different kinds (including 
 size, colour, and material) in case of need. 
 
 In moulding candles of any kind, great attention must be 
 paid to the temperature of the melted material, to the warmth 
 of the mould, and to the rate at which the mould is cooled, 
 in order to produce the best possible appearance. If the 
 mould, or the candle-material, or both, are too cold, the 
 surface of the candle will have holes, owing to the air 
 bubbles not having had time to escape. If, on the other 
 hand, they are too hot, or the whole is cooled too slowly, 
 the fatty acids crystallize, and the surface of the candle 
 instead of being smooth and homogeneous, is mottled, and 
 frequently greasy to the touch. Many years ago, arsenic 
 was added to stearic acid, to prevent this crystallization ! 
 Paraffin and other transparent candles miist be filled-in very 
 hot, and after all air-bubbles have escaped, the moulds must 
 be rapidly cooled by a large flush of cold water, to pre- 
 vent the paraffin, &c., from crystallizing, and thus causing 
 opacity. 
 
 Night-lights. — The making of night-lights is an impor- 
 tant branch of candle manufacture. In 1877, Price's Candle 
 Company turned out 32 millions of them. Messrs. Ogleby 
 produce annually about 12 millions of their " Star " night- 
 light, and Clarke's patent " pyramid " night-light has an 
 enormous sale. There are 2 distinct kinds of night-light ; 
 the common form, so long known as Child's, from the in- 
 ventor, whose son now manages this department of Price's 
 Candle Company's factory, and the Company's new patent 
 
CANDLES ASJ) NIGHT-LIGHTS. 285 
 
 night-liglit. The former are made by rtmning molten 
 fatty matters into little wooden cases, wliicli are the 
 result of a series of operations. Balks of timber, free 
 from knots, are the foundation of the manufacture; the 
 best American pine is preferred, but it is now becoming 
 scarce and dear, and the so-called " tulip-wood " has often 
 to be substituted for it. The balks of timber are brought 
 UDder a huge planing machine, which shaves off beauti- 
 fully even slices, no thicker than stout paper. These are 
 used as well for the boxes in which the night-Ughts are 
 packed for transport as for the cases of the night-lights 
 themselves. It is perhaps a little out of order, but at any 
 rate it is convenient, here to complete the account of the 
 manufacture of the ■ packing boxes. The slices of wood are 
 cut into rectangular form of the required size, and corre- 
 sponding sheets of tough, but very thin, paper are pasted 
 over them, by boys, at great speed. In this condition, they 
 are pressed, to ensure adhesion, and are then taken to a 
 machine for the purpose of having incisions made in them, 
 where the edges are to be turned up to form the sides and 
 ends. The cutters of this machine are so beautifully adjusted, 
 that they completely sever the wood without so much as 
 scratching the paper backing, which remains to form the 
 hinges or angles. The same thin slices of wood are used in 
 making the night-light cases. The slices, each of a size to 
 form about a dozen cases, are coated with paper. This, like all 
 the remaining processes in the manufacture of Child's night- 
 light cases, is performed in a most dexterous manner by girls. 
 The slices are placed on a ta.ble before a girl, who with one 
 hand pastes a printed yellow label on the wood, while with 
 the other hand she coats the paper label with gum, which 
 gives it a glazed appearance, and at the same time renders 
 it waterproof, the latter being an important consideration, 
 as the light has to be burnt in a saucer of water. The double 
 slices are immediately rolled to a given diameter, and are 
 then carried on trays to a heated room to dry. After drying, 
 each roll is subdivided into the proper number of cases, by 
 
286 CANDLES AND NIGHT-LIGHTS: 
 
 means of a lathe, at the rate of 150 per minute. Next they 
 are bottomed with cardboard, by means of a fitting stick, and 
 an aperture is punctured in the centre for the introduction 
 of the wick. This is provided with a tiny square tin-foil 
 sustainer, which is secured to the case by means of a single 
 drop of wax. The cases, thus prepared, are placed on trays 
 to be filled. This operation is entrusted to boys, who 
 manifest a skill and exactitude quite astonishing, and have 
 proved themselves superior to any mechanism which has 
 yet been tried for the purpose. The creamy fat is poured 
 from a can with a narrow straight spout, sufficient being 
 tipped at one operation into each case to exactly fill it and 
 no more. When cool, the exterior of each case is scraped 
 with a blunt knife to remove accidental splashes, and the 
 lights are ready for packing in the boxes already alluded to. 
 The new patent night-lights difier from the foregoing, not 
 only in being made from very much better materials, but 
 also in the method of manufacture and mode of burning. 
 Cases are dispensed with, and the fatty material, usually 
 derived from palm-oil, is moulded to the required shape by 
 being run into a frame, which consists of a number of moulds 
 or cups securely fitted to a bed of iron or wood. Into these, 
 the melted material is poured and left to cool. When cold, 
 the excess of fat is scraped off with a blunt tool, and the 
 night-lights, ready punctured for the insertion of the wick, 
 are lifted out by a screw. The wicks are introduced by 
 boys. On each wick, cut to the proper length, is threaded a 
 tiny square of tin-foil, which is to serve as a support for it 
 during the latter stage of the combustion of the light ; the 
 wick is then thrust through the little disc of opaque white, 
 fat, and is secured by a cleat effected by a sharp blow on a 
 miniature vertical anvil. The rapidity and precision with 
 which the lads perform this operation is something to admire. 
 The lights are now ready for burning, for which purpose 
 they are placed without water in little glass cups. Night- 
 lights are made of various sizes, calculated to burn for 6, 8, 
 or 10 hours. 
 
THEIB ILLUMINATING VALUE. 
 
 287 
 
 Statistics. 
 
 The following tatle shows the exports of candles of all 
 sorts in 1883 : — 
 
 To Belgium 
 
 „ France 
 
 „ United States of Colombia 
 
 „ ChannelMands 
 
 „ British Possessions in South Africa .. 
 „ British India : 
 
 Bombay and Scinde 
 
 Bengal and Bunnah 
 
 „ Australasia 
 
 „ British North America 
 
 „ British West India Islands and British 
 
 Guiana 
 
 „ Other Countries 
 
 Total 
 
 Lb. 
 125,300 
 218,800 
 263,000 
 525,900 
 436,600 
 
 305,800 
 
 281,800 
 
 1,007,500 
 
 230,400 
 
 533,600 
 1,353,900 
 
 5,285,600 
 
 £ 
 
 3,164 
 
 6,068 
 
 7,202 
 
 12,006 
 
 12,324 
 
 8,721 
 
 8,423 
 
 28,755 
 
 6,605 
 
 14,465 
 40,228 
 
 147,961 
 
 \ILLVMINAT1N0 VALVE. 
 
 It isj somewhat remarkable that purchasers, in judging of 
 the value of a candle, are entirely guided by its mere 
 appearance, and more particularly by its colour. The 
 primary object of a candle is to give light. In estimating 
 the value of any light-giving material, 3 factors have to be 
 taken into account, viz.: — (1) the cost of the material; (2) 
 the rate of its consumption; (3) the luminous intensity 
 produced. In practice, a sperm candle burning at the rate 
 of 120 gr. an hour, is taken as the standard light with which 
 all others are compared. This is the explanation of the 
 phrases " 16-candle gas,'' electric light of so many thousand 
 "candle-power," and so on. Such a standard, however, is 
 unsatisfactory at best, since very slight inequalities in the 
 wick, or changes of its curve in the candle flame, materially 
 affect the luminous intensity, without appreciably altering 
 the amount of sperm consumed. Various other standards 
 
288 
 
 CANDLES AND NIGHT-LIGHTS: 
 
 have been proposed, but none is thorotiglily reliable. There 
 are therefore 3 variable elements, each of which must be 
 duly considered. If, for example, paraffin and stearin (or 
 composite) candles give equal light photometrically, and 1 lb. 
 of stearin candles lasts 48 hours, while 1 lb. of paraffin 
 candles lasts 54 hours (146 and 129 gr. per hour respectively), 
 it is obvious that if the stearin candles cost 8d. per lb. and 
 the paraffin candles cost 8fd. per lb., the paraffin is really 
 the cheaper of the two, and at 9d. per lb. would cost the 
 same. 
 
 Some writers throw this calculation into the form of " cost 
 per 100 of light," where the 100, or standard, is taken from 
 a standard " hot-oil " lamp, burning every hour 815 gr. of 
 oil, or 0-1164 lb. at lid. a lb. Hence in this case, the cost 
 per 100 of light is 0-1164 xll = l- 2804d. Comparing this 
 with a wax candle, burning 125 gr. an hour, giving only 
 ^ the light of the lamp, and costing 2s. 6d. or 30d. a lb., 
 we have as the cost per 100 of light,— 
 
 125 X 11 = 1375 gr., or 0-196i lb. x 30 = 5-892d. 
 
 Proceeding in this manner. Dr. Frantland has drawn up 
 the following tables of illuminating equivalents, or the 
 quantities of different illuminating materials necessary to 
 produce the same amount of light : — 
 
 Young's paraffin-oil . . 1 • 00 gal. 
 American petroleum, No. 11-26 „ 
 No. 2 1-30 „ 
 Paraffin candles .. .. 18-60 lb. 
 
 Taking into account the market prices of these various 
 materials, he concludes the comparative cost of the light, 
 equal to that of 20 sperm candles (each burning for 10 hours 
 at 120 gr. an hour), to be : — 
 
 Sperm candles .. 
 
 .. 22-90 lb 
 
 Wax „ .. 
 
 .. 26-40 „ 
 
 Composite „ 
 
 .. 29-50 „ 
 
 Tallow „ 
 
 .. 36-00 „ 
 
 s. d. 
 
 Wax 7 2^ 
 
 Spermaceti 6 8 
 
 Paraffin 3 10 
 
 Tallow 2 8 
 
 Sperm-oil 1 10 
 
 American petroleum . . 
 
 Young's paraffin-oil . . . . 
 
 Coal-gas 
 
 Canuel-gas 
 
 d. 
 
 ei 
 
 5 
 
 4J 
 
 3 
 
THEIK ILLUMINATING VALUE. 289 
 
 It may be remarked, in passing, that tlie difference in 
 favour of gas, as against candles, is very much reduced in 
 practice, since users of gas always haMtuate themselves to a 
 much more intense light than when they employ candles. 
 Probably the same thing -will obtain, mutatis mutandis, when 
 domestic electric lamps are substituted for gas. 
 
 Taking into account the cost of material, its rate of con- 
 sumption, its market price per lb., and its light-power, 
 Peclet gives the valuable table on p. 290, upon the data 
 that : — -1 pint of oil costs 5d. ; 1 lb. tallow candles, 7d. ; 1 lb. 
 wax candles, 2s. 2d. ; 1 lb. stearin candles, Is. id. ; 100 ft. 
 coal-gas, 7d. ; 100 ft. oil-gas, 2s. 3d. ; and that 1000 ft. coal- 
 gas = 44^ lb. sperm, or 51 lb. stearic acid, or 6^ gal. colza- 
 oil, or 5 • 9 gal, sperm-oil. 
 
 Although it is impossible to avoid the inference from the 
 figures given, that candles in any form are very expensive 
 illuminating agents, compared either with coal-gas or 
 parafiSn-oil (or any of its numerous modifications), neverthe- 
 less, the numerous advantages which they possess render it 
 exceedingly unlikely that they will, to a greater extent than 
 at present, be superseded by either of the two cheaper 
 methods of illumination. Neither coal-gas nor para£Qn-oil 
 can be employed except at what are, for all practical pur- 
 poses, stationary points ; they cannot be carried about, while 
 evolving light, from one place to another, and are altogether 
 destitute of that element of portability which renders the 
 candle so valuable. Further, except in so far as a fire 
 may result from actual contact between a candle flame and 
 any inflammable substance, candles are absolutely safe 
 illuminating agents, and persons burning them are not liable 
 to the alarming explosions and fires which result from the 
 careless use of gas, or of paraffin lamps.* 
 
 Before proceeding to describe the various kinds of photo- 
 
 * Valuable suggestions on this subject will be found in a lecture on 
 " Accidental explosions produced by non-explosive liquids," by Sir P. 
 Abel, O.B., F.K.S., delivered at the Koyal Institution on March 13, 1885, 
 and reported in ' Natuie,' Nos. 803, 804, 805. 
 
290 
 
 CANDLES AND NIGHT-LIGHTS: 
 
 
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THEIR ILLUMINATING YALUE. 291 
 
 meters, it may be useful to consider briefly two remarkable 
 results of careful photometric observation, -wiiicb have an 
 important practical bearing upon the most economical 
 arrangement of a number of separate lights, whether they 
 be candles, lamps, or gas-flames, i. e. the arrangement which 
 will give the greatest total amount of light from the various 
 illuminating sources. 
 
 The first is that when the flames of two lamps or candles 
 touch each other, the luminous intensity of the combined 
 flame is greater than the sum of the intensities of the 
 separate flames. This efiect was first observed by Dr. Benj. 
 Franklin, and appears to be due to the increased temperature 
 at the part where the flames overlap. 
 
 The second result may be thus expressed : — A comparison 
 of the amounts of light afibrded by the same number of 
 flames in different relative positions proves that flame is 
 perfectly transparent, and thus that the luminous effect of 
 a row of lights is the same whether their arrangement is 
 parallel with or perpendicular to the direction of the rays ; 
 similarly a flat gas-flame gives the same degree of light in 
 all directions. 
 
 The chief forms of photometer will ■ now be described. 
 The simplest, most readily constructed, and most easily used, 
 is that known as Eumford's. It consists merely of a black 
 cylindrical rod mounted vertically upon a stand or foot, and 
 of a white screen upon which . to receive the shadows of the 
 rod. The lights to be compared (all others should be put 
 out) are placed about until the respective shadows cast by 
 the rod are of equal depth. The distances of the lights 
 from the screen are then carefully measured, and each num- 
 ber thus obtained is multiplied by itself. The proportion 
 between these products represents the relative intensities of 
 the lights under examination. For example, suppose lamp 
 A at 21 in. and lamp B at 30 in. from the screen gave equally 
 deep shadows, then, since 21x21 = 441, and 30 x 30 = 900 
 lamp A is to lamp B as 441 to 900, or nearly as Isto 2, or, in 
 other words, lamp B gives twice as much light as lamp A. 
 
 u 2 
 
292 CANDLES AND NIGHT-LIGHTS : 
 
 As a similar calcTilation lias to be made in all photometric 
 tests (thoiigh. it is frequently assisted by previously con- 
 structed tables suited to each instrument), it •will not be 
 repeated. 
 
 Bunsen's photometer depends on the equal illumination of 
 two surfaces, and is much more exact than the preceding. 
 The principle of it, with very slight modifications, is 
 adopted in the delicate photometers used in gas-testing. 
 The essential part of it is a piece of thin paper stretched 
 in a frame, and the paper is rendered semi-transparent by 
 being saturated with a solution of spermaceti in turpen- 
 tine-oil, with the exception of a central spot about • 75 in. 
 in diameter, which is allowed to remain opaque. In using 
 it (in a dark room), the standard light is placed behind the 
 spot, and the variable one in front. When the two surfaces 
 are equally illuminated, the opaque spot disappears, and 
 the whole surface of the disc is perfectly homogeneous in 
 appearance. 
 
 Wheatstone's photometer consists of a small silvered 
 polished bead, mounted upon a stem to which a looped 
 motion is given by appropriate clockwork. When it is 
 placed between two sources of light, and the clockwork is set 
 in motion, two looped curves of different brightness are seen, 
 so very close together that their intensities can readily be 
 compared; the lights are then adjusted to give curves of 
 equal brightness, and their respective distances are read off. 
 The formation of a luminous curve by a moving bright bead, 
 depends, of course, upon the well-known principle of " persis- 
 tence of vision," the simplest illustration of which is the 
 circle of fire traced by a lighted stick whirled round by 
 hand. 
 
 Letheby's and Evans's photometers are similar in con- 
 struction, and both depend upon the principle of Bunsen's. 
 Letheby's consists essentially of a long bar, at each end of 
 which are supports for a light, one being the standard 
 candle upon a Keate's candle-balance. Upon the rod slides 
 a box, with holes on each side and in front ; it contains the 
 
THEIR ILLUMINATING VALUE. 293 
 
 semi-transparent paper with the opaque spot.* The box is 
 moved until the spot disappears, when a pointer attached to 
 the box indicates on a scale the intensity of the unknown 
 light in terms of the standard. Evans's is a similar instru- 
 ment, but the box is fixed, and the lights move along the bar. 
 In the concluding words of Mr. Leopold Field's Cantor 
 Lectures : — " Gas and electric lighting have taken high rank 
 as sciences, and justly so, involving as they do, such profound 
 thought and supreme skill. But the candle and the lamp 
 have also called forth the highest powers of great scientists 
 to perfect them — Chevreul and Young laboured for little 
 else — and they are now nearly perfect of their kind. So, 
 while honouring to the full the authors of the greater lights, 
 we must not forget the many workers whose labours have 
 brought the candle from the crude, smoky, wax and tallow, 
 to the beautiful form and light it now owns,— workers of 
 whom more than six generations sleep in the shadow of old 
 Lambeth Church [London] with no other monument than 
 that of a fair life and faithful toil ! " 
 
 * Such disoB may be procured in quantity from Messrs. Sugg & Co., 
 Charing Cross, London. 
 
( 294 ) 
 
 . OHAPTEE XIII. 
 
 GLYCEEIN. 
 
 Few things in the history of chemical industry are more 
 wonderful than the enormous development in the use of this 
 substance, which, a few years ago, was thrown away as a 
 waste product, hut which now finds so many useful applioa'- 
 tions in the arts and sciences. The researches of Chevreul, 
 which demonstrated the constitution of fats, showed that 
 glycerin exists in nearly all neutral fats (see pp. 4^11) in a 
 combined state, and small traces of it have lately been dis- 
 covered uncombined in palm-oil. It is formed, as Pasteur 
 has shown, in the process of fermentation, 100 parts cane- 
 sugar forming 3'5 parts of glycerin. Eecent researches 
 have also made it clear that its compound with phosphoric 
 acid is the starting-point of a number of complex constituents 
 of the brain. For practical purposes, however, glycerin is 
 always obtained from the bye-products of candle-, and quite 
 lately, of soap-factories. Cap worked out the first process 
 for preparing it on a commercial scale from the waste liquor 
 of the saponification of tallow by lime, in the first stage of 
 stearic acid making (see p. 254). Early in 1854, Tilghman 
 produced it by pumping an emulsion of 2 parts tallow and 
 1 part water through a coil of pipe heated to 612° F. (322° C), 
 after which, the emulsion separated into two layers, the 
 tipper one of fatty acids, and the lower one of glycerin and 
 water. 
 
 Several modifications of this were afterwards patented, but 
 the only one worked on a large scale was that of G. F. Wilson 
 and Gr. Payne, dated July 24, 1854, under which, considerable 
 quantities of glycerin have been made by Price's Candle Co. 
 In this process, neutral fats are put into a still provided 
 
GLYCEBIN, 295 
 
 with a fine steam-worm, and with a fractional condensing 
 apparatus of large surface, similar to that described on 
 p. 260 ; they are then heated to 550°-600° F. (288°-315° C), 
 and plenty of superheated steam is injected, — when mixed 
 vapours of fatty acids, glycerin, and water are canied over 
 to the condenser, where the divisions nearest the stiU colleot 
 only fatty acids, while those farthest from it yield mixtures 
 of fatty acids with glycerin and water in various stages of 
 concentration. Glycerin so made can he concentrated in a 
 vacuum-pan. Care must he taken that the temperature 
 does not exceed 600° F. (315° 0.), and that plenty of steam 
 is present, else some of the glycerin is decomposed, and 
 acrolein, a compound most irritating to the eyes, is formed — 
 
 Glycerin = Water + Acrolein 
 0,HA =2HjO + CaH^O 
 
 Eaw glycerin was also prepared from the water employed to 
 wash the fatty acids after acidification (p. 260) of the neutral 
 fats. The acid liquid was neutralized by barium or calcium 
 carbonate, either of which was added until effervescence 
 ceased, or by milk of lime ; it was then concentrated to 
 48° Tw. (28° B., or 1 • 240 ep. gr.), in an open, shallow, cast- 
 iron pan. Of late, however, glycerin has become sufficiently 
 valuable to cause candle manufacturers to adopt that method 
 of preparing fatty acids which gives them the greatest yield 
 of glycerin from neutral fats. In this process, as patented 
 by De Milly on Nov. 19, 1856, a copper vessel called an 
 autoclave is employed ; it is now very extensively used for 
 glycerin making, both on the Continent of Europe and in 
 England, and is thus conducted. About 1 ton of fat, usually 
 mixed tallow and palm-oil, is heated with 2 per cent, lime 
 and i the fat-volume of water in an upright Papin's digester 
 to 8 atmos. pressure for 4 hours, a little steam being allowed 
 to escape at the top, so as to promote the agitation of the 
 mass. The whole is then blown out into a tank, and the 
 " sweet-water " is run off. The lime-soap is decomposed in 
 the usual way with sulphuric acid, and the resulting fatty 
 
296 
 
 GLTCEEITf. 
 
 acids are either pressed for saponified stearin, or acidified and 
 
 distilled for "distilled stearin.' 
 
 Tlie "sweet-water" is 
 tlien concentrated in a 
 modification of tlie 
 " Wetzel " evaporating- 
 pan (originally intro- 
 duced for sugar-boil- 
 ing), constnibted by 
 Chenaillier, Paris, and 
 others. This evapo- 
 rateur universel, as it is 
 termed, which is very 
 economical and effec- 
 tive, is shown in 
 rig. 84, and consists 
 essentially of pairs of 
 saucers set edge to 
 edge upon a hollow 
 central revolving shaft, 
 through which steam 
 passes to the interior 
 of the saucers (the 
 waste steam from a 
 high - pressure engine 
 will do); the lower 
 edges of the saucers 
 dip in a jacketed trough 
 of the liquid to be 
 evaporated, and when 
 they are revolved, 
 layers of this are 
 brought up and 
 speedily concentrated 
 on their surface. It 
 may also be worked 
 in a vacuum as shown 
 in Fig. 85. 
 
GLTCEBIN. 
 
 297 
 
 Evaporation is continued to 44° Tw. (26° B., or 1 ■ 220 sp. gr.), 
 when the glycerin is of a brownish colour, and known as 
 " raw," in which state it is sold for many purposes. At Price's 
 Candle Company's works the further purification is conducted 
 as follows. The raw glycerin, sp. gr. 1 • 240-1 ■ 245, is heated in 
 a jacketed pan with that kind of animal charcoal known as 
 ivory-black, and is then distilled; this alternate treatment 
 is repeated as often as may be necessary. The distillation is 
 performed with superheated steam in a copper stiU provided 
 with copper fractional condensers (the same as shown in 
 Pig. 77, p. 259, but omitting the right half of the apparatus, 
 including the tanks G), the still being also heated exter- 
 nally ; the operation is performed at as low a temperature as 
 is consistent with distillation, usually aboui; 440° F. (227° C). 
 The number of distillations depends upon the quality of the 
 raw glycerin and the purity of the product demanded. Of 
 the 6 runs, Nos. 1, 2, and 3 usually give pure glycerin, 
 while the dilute condense-products from Nos. 4, 6, and 6 
 are generally returned to the stUl, though occasionally con- 
 centrated in an emporateur universel, or in a vacuum-pan. 
 Some stills hold as much as 3 tons, but they are usually 
 smaller, and in all 
 
 cases the process ■^"'- ^^• 
 
 is conducted very 
 slowly. A form of 
 still and condenser 
 much used on the 
 Continent of Europe- 
 is outlined in Fig, 
 86. External heat 
 and injected super- 
 heated steam are 
 used to effect dis- 
 tillation. The still A has an unusually large head B, and 
 the gooseneck C is provided with a catch-box D, in case the 
 still-contents should, as sometimes happens, boil over ; the 
 fractional condensers E are upright cylinders with longi- 
 
298 GLYOEBIN. 
 
 tudinal partitions 'F running nearly tteir whole length ; the 
 condensed products run out through G into receptacles H. 
 The -whole apparatus is of iron, and usually made to distil 
 J ton at a time ; in some cases the process is conducted 
 continuously, with a properly arranged feed. 
 
 At the( first general meeting of the Society of Chemical 
 Industry, the President called attention to the enormous 
 waste of glycerin in the manufacture of soap as then (and 
 at present) conducted ; he also pointed out that the growing 
 demand for this substance for the preparation of dynatnite 
 and the various explosive derivatives of nitro-glycerio, was 
 causing a great increase in its price. One of the earliest 
 attempts to extract glycerin from the spent lye of the soap- 
 house was a patent by H. Eeynolds, June 10, 1858, for con- 
 centrating it, and distilling off the glycerin by superheated / 
 steam between 380° and 400° F. (193J°-204i° C); the 
 large quantity of sodium salts, especially sodium chloridoj 
 were found, however, to be an almost insuperable difficulty. 
 From that time the subject has been pursued with varying 
 success by both British and Continental soap-makers, and 
 although a large number of patents on the subject have been 
 taken out during the last 4 years, very few of them are 
 actually worked in practice. The history of many of them 
 is only another instance of the well-known fact that it is 
 far easier to obtain a patent, than to make a discovery. 
 
 The " spent lye " contains water, glycerin, sodium chloride, 
 sulphate, and carbonate, a small quantity of caustic soda, 
 together with albuminous, resinous, and soapy matters, whose 
 amounts vary with the nature of the materials which have 
 been saponified. Mr. C. T. Kingzett (Jour. Soc. Chem. Ind„ 
 i. 78) gives the following as its average composition after con- 
 centration to 72° Tw. (38° B..), the gallon being composed of. 
 
 Water T'oSlb. 
 
 Glycerin 2-04 „ 
 
 Salts 2-78 „ 
 
 12-35 „ 
 
GLTCERIN. 299 
 
 and the same authority gives the following analysis of the 
 salts as deposited from the lye on concentration, — 
 
 Sodium chloride 78-12 
 
 Sodium sulphate 8'61 
 
 Insoluble organic matter 0'22 
 
 Glycerin and organic matter 3-55 
 
 Water 7'50 
 
 Alkali (calculated as sodium carbonate) ., 2-61 
 
 100-61 
 
 The objects of the various patented processes may be 
 reduced to 3, viz. — 
 
 1. To remove or destroy the albuminous, resinous, and 
 
 soapy matters from the lye. 
 
 2. To facilitate the removal of the salt, either by dimi- 
 
 nishing in some way the solubility of the sodium 
 chloride, or substituting for it another which may 
 be more readily and profitably removed. 
 
 3. To economise the cost of concentration to the point 
 
 where the product may be either used as crude gly- 
 cerin, or purified by distillation. 
 To effect the first object, a large number of " coagulating 
 agents" have been proposed, and in most cases abandoned. 
 The process by which the first successful production of crude 
 glycerin from soap lye was effected on a manufacturing scale 
 was patented on March 31, 1879, and was for some time 
 worked, by Messrs. Thomas, Fuller, and King. It con- 
 sisted in boiling the concentrated lye with a fatty acid, 
 which removed all the caustic and carbonate of soda, 
 and simultaneously " coagulated the albumen." Among 
 the other "coagulating agents" proposed at various times 
 have been, — albumen itself, blood, gelatin, salts of alumina, 
 salts of chromium, caustic lime, calcium chloride, tannic 
 acid, &c. 
 
 Under the second head may be mentioned the use of 
 hydrochloric acid gas, to render the salt more insoluble, and 
 of carbonic acid gas to precipitate the alkaline soda salts as 
 
300 
 
 GLYCERIN. 
 
 Fig. 87. 
 
 bicarbonate; also the proposal to employ sodium sulphate 
 instead of sodium chloride in " salting out " the soap. 
 
 Many ingenious methods of economic concentration of the 
 lye have been devised, such, for example, as blowing hot air 
 through the solution. It is generally considered advisable • 
 that an ordinary concentrating pan, if used, shall be fired at 
 the side, and not from beneath, to avoid cracking it from 
 
 the deposition of salts. A very 
 effective evaporator for this 
 purpose is that patented by 
 Thomas and Domeier, June 4, 
 1881. From a rose D, Fig. 87, 
 at the top, the liquid trickles 
 down over the inclined shelves 
 E, during which it meets an 
 upward current of hot air 
 introduced through the pipe F, 
 whose mouth is protected by a 
 suitable cover. The hot air 
 and watery vapour are drawn 
 off by an exhauster through the 
 pipe G. The same patent 
 covers one of the few com- 
 mercially successfal processes 
 for the preliminary purification 
 of the crude glycerin. The lye 
 is concentrated, then treated 
 with a slight excess of mineral 
 acid, and allowed to stand some hours, after which the scum 
 is removed, and the liquid exactly neutralized with alkali. 
 This crude glycerin is then washed by being mechanically 
 mixed with about ^ of its bulk of some suitable solvent, 
 which will dissolve out the impurities. For this purpose 
 the patentees use " a hydrocarbon obtained from the distil- 
 lation of coal tar, petroleum or other mineral oil, carbon 
 bisulphide, amylic alcohol, ether, or other suitable solvent in 
 which the glycerin is practically insoluble." 
 
GLYCEBIN. 301 
 
 Another propoBal* is to mix the concentrated crude glycerin 
 with more than its own volnme of methyl or ethyl alcohol, 
 and separate the salts by filtration. Lead oxide, or solnhle 
 lead salts, are added to remove the last traces of chlorine, and 
 the final filtrate is distilled, to drive off the alcohol, whiuh 
 also carries off some of the volatile fatty acids as ethers, 
 thus effecting a further purification of the glycerin. 
 
 It is usual to employ a centrifugal machine or a filter- 
 press to extract the last traces of crude glycerin from the 
 salts deposited during concentration. Other methods than 
 distillation also have been proposed for purifying crude 
 glycerin, such for example as that of H. Flemming, of Kalk, 
 who has patented in Germany (No. 12,209) a process for 
 removing glycerin from spent lye by dialysis, a membrane 
 of parchment-paper serving as the diaphragm through which 
 the crystalline salts present in the glycerin diffuse them- 
 selves. 
 
 In the opinion, however, of many who are well qualified to 
 judge, all these processes for the recovery of glycerin from 
 spent lye will in time be superseded by the removal of 
 glycerin from fats prior to their saponification. Such a pro- 
 ceeding is by far the more scientific, but the great practical 
 objection to it is the slight inferiority, in appearance only, of 
 the soap ultimately produced. This process was worked out 
 by Messrs. Michaud Freres of Paris, and has been patented 
 in most countries. In America, where it is now extensively 
 worked, a large company f has been formed to acquire the 
 patent rights. It consists essentially in resolving neutral fat 
 into fatty acids and glycerin by the action of water and a 
 minute quantity of zinc oxide (or, in another modification, 
 of magnesium carbonate), under pressure, and it is thus 
 described in the English patent (Oct. 27, 1882) :— 
 
 " Tor this purpose the fatty matter is subjected in a close 
 vessel to the action of steam at a pressure of 100-130 lb. 
 per sq. in. and at corresponding temperature, in presence of 
 
 * Eng. Pat. 2326, 1883. 
 
 t The Oontinental Glycerin Co., 55, Liberty Street, New York. 
 
302 GLTCEKIN. 
 
 ;^-4- part of its weight of water, and ^| per cent, of its 
 weight of the oxide of zinc known commercially as zinc white, 
 or a like proportion of zinc powder or zinc gray, which is a 
 residue in the treatment of zinc, being a mixture of zinc 
 with its oxide. 
 
 " The close vessel and the decanting tanks are arranged 
 in the same way as those used for saponification by the lime 
 process, and the system of operation is the same after the 
 steam pressure has been applied for 3 or 4 hours, according 
 to the character of the material operated upon and the 
 quantity of zinc or its oxide employed. The very small 
 proportion of mineral substance used is sufficient for dis- 
 pensing with the acid treatment applied for decomposing 
 lime soap, and the product obtained, consisting almost ex- 
 clusively of acid fat, can be converted by the acids usually 
 employed, into soap or candles. In soap-making, the 
 dissolving powers of the caustic alkalies remove all objec- 
 tions to the presence of the zinc, if it should be used in 
 excess. The reducing power of the zinc powder prevents 
 discoloration of the acid fats, such as results from the 
 ordinary treatment ; and the use of zinc as described dis- 
 penses with that of the agents usually employed for decom- 
 posing the fatty salts, so that there is great economy of 
 labor in the process, and great diminution of tear and 
 wear of the plant.'' 
 
 The following is an account of the details of an experi- 
 ment made in a large American factory : — 
 
 " The experiment was made as follows : — Jan. 15, 1884, 
 placed in digester 8096 lb. of tallow; Jan. 16, pumped from 
 settling-tanks the free fat acids, made same into soap, and 
 boiled to a good dry curd ; removed same from pan Jan. 17 
 and weighed carefully and found as a result that we re- 
 ceived 12,666 lb. of good marketable soap, or a percentage 
 of 63 "39 per cent, of fat acids against the usual yield of 
 65 per cent., showing a,n actual gain of moisture by using 
 our process of 1 • 61 per cent." 
 
GLYCERIN. 
 
 303 
 
 The glycerin thus produced finds a ready sale as it runs 
 from the eTaporators ,- and from it, as " crude," 96 per cent, 
 of pure glycerin can he obtained. 
 
 Although evaporation and distillation are the usual methods 
 of purifying glycerin, the action of cold upon more or less 
 dilute glycerin is sometimes employed in conjunction with 
 them, especially by Sarg, at Vienna. When an aqueous 
 solution of glycerin partially freezes, the frozen mass con- 
 tains more water than the remaining liquid, hence some 
 amount of concentration- may he thus effected. The following 
 table gives the freezing-points of such mixtures : — 
 
 Glycerin 
 Per Cent. 
 
 Sp. Gr. 
 
 Freezes. 
 
 Glycerin 
 Per Cent. 
 
 Sp. Gr. 
 
 Freezes. 
 
 10 
 20 
 30 
 
 40 
 50 
 
 1-024 
 1-051 
 1-075 
 1-105 
 1-127 
 
 - 1°C. 
 
 - 2°-5 
 
 - 6° 
 -17°-5 
 -31°-3 
 
 60 
 70 
 80 
 90 
 94 
 
 i-isg^i 
 
 1-179 
 1-220 ^ 
 1-232 1 
 l-24lj 
 
 Below 
 - 35° C. 
 
 Another authority gives : — 
 
 Glycerin solution sp. gr. 10° B. 12° B. 14° B. 15° B. 
 Melting-point .. - 9° 0. -13° 0. -18°C. -21° C. 
 
 In January 1867, some glycerin sent in tin cans from 
 Germany to England froze into pea-sized octahedral crystals ; 
 these, while melting, had a constant temperature of 45° F. 
 (7 "2° C), but would not freeze again even when cooled to 
 0° F. (— 18° C). According to Werner, commercial glycerin 
 will freeze more readily if chlorine gas be passed into it. In 
 purifjdng glycerin by cold, the whole mass is cooled to nearly 
 32° F. (0° C), and some crystals of solid glycerin are added ; 
 almost the whole mass solidifies on agitation, and a centri- 
 fugal machine is used to separate the solid from the liquid 
 parts. Treated in this way, glycerin at 48° Tw. (28° B., 
 
304 GLYCERIN. 
 
 or 1-240 sp. gr.) yields crystals wliioh, -when melted, are 
 54° Tw. (30^° B., or 1-270 sp. gr.). 
 
 Pure glycerin, is a viscid, oolourless, and transparent 
 liquid, with an intensely sweet taste, soluble in water in all 
 proportions, in alcohol, cUoroform, and carbon bisulphide, 
 but not in ether ; its sp. gr. is 1 - 267 ; it solidifies at — 32° F. 
 (— 35-5° 0.) to an amorphous mass. When distilled, it 
 is said by G. Th. Gerlach* to boil so quietly and uniformly 
 at 554° F. (290° C.) that it may be used for determining 
 that point on high-temperature thermometers. According 
 to Bolas, however, at 12-5 mm. pressure, it boils at 355° P. 
 (179^° C), and at 50 mm., at 410° P. (210° C), whUe 
 Heminger gives 354° P. (179° 0.) as its boiling-point under 
 20 mm. It burns with a clear flame like oil, if there be free 
 access of air and a high temperature for kindling it. 
 
 The chemical constitution of glycerin, and its relationship 
 to fatty bodies, were fully explained in Chap. I. It remains 
 to notice some of its chief physical properties, the chemical 
 tests for it, some of its useR, and its possible adulterants. 
 
 Next to water, glycerin is the most powerful solvent 
 known. It dissolves bromine, iodine, and carbolic acid better 
 than water does. Klever gives a long table of the solubilities 
 of different substances in 100 parts of glycerin, from which 
 the following are taken : — 93 sodium carbonate, 40 alum, 
 25 green vitriol (ferrous sulphate), 20 lead acetate, 20 sodium 
 chlorate, 0-50 quinine and other alkaloids, 1-9 iodine, 0-20 
 phosphorus, - 10 sulphur. 
 
 With baryta, strontia, and lime, it forms compounds 
 insoluble in water, not preoipitable by carbonic acid. Anhy- 
 drous glycerin dissolves caustic potash and soda, lead oxide, 
 all deliquescent salts, potassium, sodium, and copper sulphates 
 and chlorides, and the vegetable acids and alkaloids. It 
 mixes with water in all proportions ; the following tables 
 will be found very useful commercially : — 
 
 * Dingl. Polyt. Journ., 255, 208, 1885 ; abstracted in Joura. Soo. Chem. 
 Ind., iv. 226. 
 
GLTCEEIN. 
 
 305 
 
 Table of Qtjantitt bt Weight of Water lii 100 parts by Weight of 
 Dilute GLTOEKitr at 63^° F. (17i° 0.)-[F. Hoffmann.] 
 
 Sp. Gr. 
 
 Per cent. 
 
 Sp. Gr. 
 
 Per cent. 
 
 
 Per cent. 
 
 Water. 
 
 
 Water. 
 
 
 Water. 
 
 1-267 
 
 
 
 1'212 
 
 17 
 
 1-161 
 
 34 
 
 1-264 
 
 1 
 
 1-209 
 
 18 
 
 1-159 
 
 35 
 
 1-260 
 
 2 
 
 1-206 
 
 19 
 
 1-156 
 
 36 
 
 1-257 
 
 3 
 
 1-203 
 
 20 
 
 1-153 
 
 37 
 
 1-254 
 
 4 
 
 1-200 
 
 21 
 
 1-150 
 
 38 
 
 1-250 
 
 5 
 
 1-197 
 
 '22 
 
 1-147 
 
 39 
 
 1-247 
 
 6 
 
 1-194 
 
 23 
 
 1-145 
 
 40 
 
 1-244 
 
 7 
 
 1-]91 
 
 24 
 
 1-142 
 
 41 
 
 1-240 
 
 8 
 
 1-188 
 
 25 
 
 1139 
 
 42 
 
 1-237 
 
 9 
 
 1-185 
 
 26 
 
 1-136 
 
 43 
 
 1-234 
 
 10 
 
 1-182 
 
 27 
 
 1-134 
 
 44 
 
 ~ 1-231 
 
 11 
 
 1-179 
 
 28 
 
 1-131 
 
 45 
 
 1-228 
 
 12 
 
 1-176 
 
 29 
 
 1-128 
 
 46 
 
 1-224 
 
 13 
 
 1-173 
 
 30 
 
 1-126 
 
 47 
 
 1-221 
 
 14 
 
 1-170 
 
 31 
 
 1-123 
 
 48 
 
 1-218 
 
 15 
 
 1-167 
 
 32 
 
 1-120 
 
 49 
 
 1-215 
 
 16 
 
 1-164 
 
 33 
 
 1-118 
 
 50 
 
 G. Th. (jerlach's determinations, 1885 {loc. cit.) : — 
 
 
 Percentage 
 
 Speciac Gravity. 
 
 
 
 of Pure 
 Glycerin. 
 
 
 
 
 Atl5°C. 
 
 At20°C. 
 
 
 
 100 
 
 1-2653 
 
 1-262 
 
 
 
 90 
 
 1-2400 
 
 1-236 
 
 
 
 80 
 
 1-2130 
 
 1-209 
 
 
 
 70 
 
 1-1850. 
 
 1-182 
 
 
 
 60 
 
 1-1570 
 
 1-155 
 
 
 
 50 
 
 1-1290 
 
 1-128 
 
 
 
 40 
 
 1-1020 
 
 1-101 
 
 
 
 30 
 
 1-0750 
 
 1-074 
 
 
 
 20 
 
 1-0400 
 
 1-048 
 
 
 
 10 
 
 1-0245 
 
 1-0235 
 
 
 
 
 
 1-0000 
 
 1-0000 
 
 
 According to F. Strohmer (Ckemisolies Centralblatt, 
 15,397), the amount of glycerin present in its aqueous solution 
 
306 GLYCEEIN. 
 
 may he determined by its index of refraction. The formula 
 given, deduced by the method of least squnres, is 
 
 ^ _„.„„„ , (K + 56-569) D 
 nm - 75875 + j)^^oo_C) + o' 
 
 where D = sp. gr. of anhydrous glycerin, which is 1'262 
 at 63° F. (17^° C), and C = percentage of glycerin by 
 weight. (Jour. Soc. Chem. Ind., iii. 490.) 
 
 Commercial glycerin is liable to contain various impurities, 
 arising from its mode of preparation ; also certain adulterants, 
 of which cane-sugar and glucose are the chief. M. Ferdinand 
 Jean (Jour. Soc. Chem. Ind., i. 411) has described minutely 
 the adulterations and imperfections in the manufacture of 
 glycerin. Glucose may be detected by the brown colour 
 formed when the suspected glycerin is boiled with caustic 
 soda; or by the blue colour produced when 3 drops of 
 glycerin are boiled in a test tube with 100-120 drops of 
 water, 1 drop of nitric acid, and 1 grm. ammonium molybdate. 
 Cane-sugar is shown by its deposition when the glycerin is 
 agitated with chloroform, or, more certainly, by a polarizing 
 sacoharimeter, since glycerin has no rotary action on the 
 plane of polarization. Lead is detected by sulphuretted 
 hydrogen ; lime, by the addition of alcohol and sulphuric 
 acid, a white precipitate of calcium sulphate being formed ; 
 butyric and formic acids, by the characteristic smell of their 
 ethers, produced by boiling the suspected glycerin with 
 alcohol and strong sulphuric acid ; oxalic acid by the addition 
 of calcium chloride and ammonia ; sodium chloride, by the 
 addition of silver nitrate, which should give no precipitate 
 with pure glycerin after 24 hours' standing. A rough and 
 ready test for impurities generally is to agitate the glycerin 
 with an equal bulk of chloroform, when they collect in the 
 intermediate layer. Pure glycerin should not blacken when 
 mixed, in the cold, with strong sulphuric acid. 
 
 Traces of glycerin present in other substances may be 
 detected by the formation of formic ether (which smells of 
 
GLYOEKIN. 307 
 
 peaoh-Hossom), produced by boiling glycerin with manganese 
 binoxide, alcohol, and snlphnric acid. 
 
 The uses of glycerin are very numerous, and are almost 
 daily increasing in number. Its applications in pharmacy 
 are nearly endless ; it is used wherever a substance requires 
 to be kept more or less moist, e. g. modelling-clay, tobacco, 
 paper for printing, adhesive gum, &c. ; also in spinning, 
 " dressing," weaving, rope-making, and tanning. It is 
 employed in gas-meters, and in floating compasses, to lower 
 the freezing-point of the water therein used ; it is an ex- 
 cellent preservative medium for meat, and for natural his- 
 tory specimens, to which latter purpose it was first applied 
 in 1856 by Dr. Carpenter, F.E.S. Owing, however, to its 
 solvent action upon calcium carbonate, delicate specimens, 
 especially for the microscope, should be mounted in glycerin 
 which has been standing over crushed marble. Glycerin is 
 also of very great importance as the starting-point of other 
 chemical products of great value, one of the most valuable of 
 which is nitro-glycerin. Fbr this purpose, it must contain no 
 sodium chloride. The engineers of the Panama Canal esti- 
 mated their requirements of nitro-glycerin at a minimum of 
 8000 tons, equal to about half that quantity of raw glycerin. 
 Besides nitro-glycerin, two other important products are 
 obtainable from glycerin, viz. isopropyl iodide, and allyl 
 iodide, each of which serves as the starting-point of a large 
 series of chemical products, many of lhem of great utility 
 in the arts. They are formed by heating glycerin with 
 hydriodic acid, thus : — 
 
 CsHsCOH), + 5 HI = 2 12 + 3 H^O + CaH,! (isopropyl iodide). 
 OaHsCOH;, -t- 3 HI = I2 + 3 H2O -1- C3H5I (allyl iodide). 
 
 When oxalic acid is heated in contact with glycerin, the 
 former breaks up into formic acid and carbon binoxide. This 
 process is much used in the preparation of formic acid, the 
 glycerin employed not being consumed, but merely succes- 
 sively decomposed and recomposed. 
 
 The total production of glycerin yearly was estimated by 
 
 X 2 
 
308 GLTCEEIN. 
 
 Eicte, in a report on the Paris Exhibition of 1878, at 
 10,000,000 kilo., with a value of 5-6 million /r. The produc- 
 tion was thus distributed : — ^Prance, 4000 tons ; Germany 
 and Austria, 1500 ; Holland, 900 ; Eussia, 900 ; Belgium, 
 800 ; Italy, 400; England, 300; Spain, 100. 
 
309 ) 
 
 (JHAPTEE XIV. 
 
 SUMMAEY OF PATENTS. 
 
 lu compiling the following summary of patents relating to 
 the fatty industries, granted in this country between the 
 years 1870 and 1884 (both inclusive), a certain degree of 
 discretion has been exercised with the view of excluding 
 matters of no value. Thus it is presumed that a patent 
 which is not carried beyond the stage of " provisional protec- 
 tion," either has no legal ground to stand on, or possesses 
 some inherent fault which renders it useless. Again, in the 
 Patent Indexes, under the heads of soap, candles, &c., will be 
 found a number of specifications relating to the domestic or 
 other application of these substances, rather than to their 
 manufacture, such as save-alls, shaving-lamps, &c., which do 
 not come within the scope of the present work. 
 
 The arrangement of the subjoined abstracts is according to 
 a system of classification, much better calculated to facilitate 
 reference than a chronological sequence would be. Where 
 the subject matter of the patent is a " communication " to a 
 patent agent, the name of the communicator is given in 
 ^ addition. Uniformity in standards and nomenclature is 
 adopted whenever possible. 
 
 1. P0EIFYING Fatty Matters. 
 
 Morfit (C). 1872, No. 140. Eefines cotton-seed-oil (p. 75) 
 by boiling with milk of lime. 
 
 Hutchison (E.). 1873, No. 3287. Subjects the oil (animal, 
 vegetable, or mineral) to the temperature of boiling 
 water for 8-10 days, in ^ - in. layers. With fatty 
 oils the process at once develops any tendency to 
 
310 SUMMAEY OF PATENTS. 
 
 thicken, so that for lubricating compounds (p. 229) the 
 necessary amount of mineral oil can be added with 
 greater accuracy. In treating mineral oils to remove 
 the fluorescence, an alkaline solution is £rst applied. 
 
 Hopkinson (J.). 1875, No. 1667. Makes an insoluble lime 
 soap of the impure grease, and then dissolves out the fat 
 by a volatile solvent, separating afterwards by distillation. 
 
 Justice (P. M.) : com. by A. W. Winter and W. T. Coleman. 
 1880, No. 3745. The fatty matter, heated to lique- 
 faction, is treated with 1-15 per cent, of powdered 
 fullers' earth, well agitated together. The purified fat 
 floats above the impurities. 
 
 Tichenor (A. C). 1883, No. 2229. Applies an electric 
 current for puriiying and decomposing fats. , 
 
 Imray (J.) : com. by I. A. F. Bang and J. de Castro. 1883, 
 No. 3658. When fats have been treated with zinc (see 
 Section 2, Class a, p. 302) to effect separation of the gly- 
 cerin, they become contaminated with metal, and dis- 
 colour the soap made from them: To prevent this, 
 while still hot they are treated with sulphurous acid in 
 a lead-lined vessel. 
 
 2. Decomposing Fatty Bodies. 
 
 (a.) By Lime. 
 
 Newton (A. V.) : com. by G. Tardani. 1874, No. 1614. The 
 fatty matter is boiled and agitated with double the 
 quantity of water and 12 per cent, of slaked lime in a 
 flat-bottomed iron boiler, shaped like a truncated cone. 
 This gives a hard lime soap and a solution of glycerin, 
 the latter being drawn off. The lime soap is slightly 
 washed, and to it is added a solution of sodium carbonate 
 in excess of the lime used. On mixing and boiling, the 
 Ume soap is decomposed, lime carbonate falls to the 
 bottom, and flakes of soda soap float, especially if some 
 sea salt has been added. This process is claimed to 
 make good soap from impure fat. 
 
DECOMPOSING PATTY BODIES. 311 
 
 Lombardon (P.). 1874, No. 3715. Secures complete saponi- 
 fication of the fatty matters by means of a compound 
 containing 10 parts soda subcarbonate, 10 of quicklime, 
 1 of alum, and 1 of common salt ; tbe whole well boiled 
 with the fat. All the glycerin goes into the soap. 
 
 Payne (G.). 1882, No. 25. The fatty matter is treated 
 with lime and water under pressure in an autoclave ; 
 after decomposition, the aqueous solution of glycerin is 
 drawn off, and the lime soap formed is decomposed by 
 soda or potash hydrate, precipitating the insoluble lime, 
 and leaving a soda or potash soap, which may be finished 
 in a soap copper as usual. 
 
 (h.) By Steam. 
 
 Field (E.). 1878, No. 646 ; illus. Treats fats by water and 
 heat to separate the stearin, olein, and glycerin. The 
 fatty matter is mixed with water in a cylindrical, hori- 
 zontal vessel, surrounded by a heating space, and fitted 
 with agitators. The conteiits after treatment are dis- 
 charged in fine streams, to facilitate dissipation of the 
 steam. On settling, the glycerin and water go to the 
 bottom. 
 
 Burghardt (C. A.). 1880, No. 5191 ; Ulus. The raw fat is 
 placed in a jacketed retort and heated by steam at 260°- 
 360° P. (127°-182° C). When the fat begins to volati- 
 lize, cold air is blown upon the vapours, and drives them 
 into a condensing apparatus, where they are collected 
 over water ; or direct into caustic lye for soap-making. 
 
 Varicas (L.) : com. by H. Heckel. 1882, -No. 1479; illus. 
 Extracts the glycerin from fatty matters before they 
 undergo saponilication, by direct action of steam and 
 water under a pressure of 150 lb., thus producing a soap 
 stock susceptible of instant saponification by adding 
 alkali. 
 
 Thompson (W. P.) : com. by W. West. 1882, No. 5466 ; Ulus. 
 Shows a still and condenser for decomposing fatty bodies, 
 by superheated steam, into fatty acids and glycerin. 
 
312 SUMMAET OF PATENTS. 
 
 (c.) By Soda. 
 
 Henry (M.): com. by J. H. Destibeanx. 1873, No. 4211. 
 Melts together stearic acid and olein ("say 56|^ lb. of the 
 former, and 43| lb. of the latter) at 140°-167° F. (60°- 
 75° C), and adds 250 lb. caustic soda at 12° Tw. (8° B.) 
 containing anhydrous soda equal to J.1 per cent, of the 
 weight of fatty matters. 
 
 Jensen (P.) : com. by J. Weineck. 1881, No. 1289. Makes 
 soaps without boiling the fats with the lye, thus obtain- 
 ing a spent lye containing no salt. The fat is melted 
 in a jacketed pan ; then about 20 per cent, of a solution 
 of 2 parts soap in 100 of water is added with constant 
 agitation. About 50 per cent, of caustic lye at 71 J° Tw. 
 (38° B.) is required for hard neutral soap from tallow. 
 The water in the jacket is heated up to 194° P. (90° C.) 
 till saponification is complete. The spent lye contaiQS 
 only glycerin and " caustic lye ''. 
 
 Gla^er (F. C.) : com. by 0. Leibreich. 1882, No. 1725. 
 Secures direct saponification of oils contained in seeds, 
 by subjecting the seed to a temperature of 212°-356° F. 
 (100°-180° C), pulverizing, and treating with alkali in 
 excess. The half-stuif thus obtained is treated with 
 water and filtered off from the cellulose, &c. 
 
 {d.) By 2iinc. 
 
 Imray (J.) : com. by C. F. E. PouUain, E. F. Michaud, and 
 E. N. Michaud. 1882, No. 5112. The fats, mixed with 
 ■^ water, and ^J per cent, of zinc oxide, are steamed at 
 100-130 lb. per in. pressure for 3-4 hours, yielding gly- 
 cerin and a saponified fat ready for soap or candle 
 making. 
 
 Lake (W. E.): com. by E. 0. Baujard. 1883, No. 279a 
 Eelies upon the action of oxygen and hydrogen in the 
 primitive state, brought about by steaming the fatty 
 matters with water in a digester, and adding metallic 
 zinc in a fine state, the pressure maintained being 125- 
 150 lb. per in. Part of the water is decomposed. 
 
SEPAEATING SOAP FROM SPENT X-YE. 313 
 
 Eumble (C.) and Sear (F.). 1883, 'So. 4264. The fats are 
 mixed with 5-8 per cent, of a zinc or magnesium salt of 
 a fatty acid, and about ^ of water, and the whole sub- 
 mitted in an autoclave to steam at 120-130 lb. per sq. in ., 
 the temperature being maintained at 368° F. (187° C). 
 The glycerin is thus set free, and can be recovered in the 
 usual way. The soaps formed are decomposed by a 
 mineral acid, and the metallic salts recovered by an 
 alkaline solution. 
 
 (e.) By Medlianical Means. 
 
 Maris (A.). 1883, No. 2349 ; illus. Decomposition of the 
 fat is effected by mechanical means in the shape of a 
 finely divided ne'itral substance (as pipe-clay) acting by 
 abrasion on the cellular membrane, liberating the gly- 
 ceral oxide so that it may combine with the water 
 present, and freeing the fatty acids. This is effected 
 in vacuo, and the various constituents are drawn over 
 and separately condensed. 
 
 3. Sepaeating Soap from Spent Lye. 
 
 Lake (H. H.) : com. by Benno, Jaffe, and Darmstaedter. 1881, 
 No. 1562. The common salt generally used for separa- 
 ting the soap from the spent lye is replaced by sodium 
 or potassium sulphate, thus facilitating recovery of the 
 glycerin f i cm the spent lye. 
 
 Abel (C. D.) : com. by Fabrik Chemischer Produkte. 1884, 
 No. 6472. Makes hard soap freer from water and excess 
 of alkali by placing it before separation of the lye, and 
 while warm, in a centrifugal hydro- extractor. 
 
 Newton (W. E.) : com. by B. T. Babbitt. 1870, No. 1783. 
 Uses caustic alkali, instead of common salt ; the liquor 
 is boiled with fresh fat, which absorbs the alkali, leav- 
 ing a mixture of glycerin and water ; the latter is then 
 evaporated off. 
 
314 summary of patents. 
 
 4. Soap. 
 
 (a.) Composition, 
 
 i. Liquid. 
 
 Scharr(J.). 1871, No. 701. Combines water, starch, linseed, 
 sal-ammoniac, soda-ash, refined alkali, pearlash, Eussia 
 potash, rosin, olein, borax, turpentine, and ammonium. 
 
 Leitch (.!.). 1871, No. 3244. Combines ^ gal. soluble glass, 
 1 gal. water in which has been dissolved about 6 oz. 
 sugar, and 2 oz. chalk. 
 
 ii. Household. 
 Jacobson (G. J.). 1874, No. 2030. Makes a soft white 
 household soap by mixing 2 gal. distilled olein, 1 gal. 
 soda Ij'e, and 5 gal. hot water. The hot water and Ij e 
 are poured into the olein during constant stirring, con- 
 tinued till the whole mass has assumed the appearance of 
 a thick yellowish soap without curdles. In 24 hours the 
 soap is white and ready for use. 
 
 iii. Detergent. 
 
 Hunt (W.). 1870, No. 1831. Adds sodium sesquicar- 
 bonate. 
 
 Van Baerle (V.). 1872, No. 1851. Adds concentrated sodium 
 or potassium silicate, and 5-20 per cent, glycerin. 
 
 Lorberg (W.). 1872, No. 2959. Combines 100 parts fat, 50- 
 60 alkali, 25-50 sodium or potassium silicate, 25-50 
 gluten, 20-50 water. All operations of mixing are 
 conducted at a temperature not exceeding 100° F. 
 (38° C). 
 
 Gibbon (R.). 1873, No. 2766. Adds 10 per cent, imperial blue. 
 
 Lewis (8. S.). 1876, No. 1157. Incorporates soluble . glass 
 " at 1700° Tw. ! " and flour with oleic acid soap, say 1 
 part of mixture (1 flour to 10-12 soluble glass) to 3 parts, 
 soap, with 1 part rosin to 10 of soap. 
 
 Maokey (J. B.) and Sellers (J.). 1878, No. 934. Incor- 
 porate potassium chlorate. 
 
SOAP. 315 
 
 iv. Emollient. 
 
 Lorberg (W.). 1871, No. 1978. Adds 10 per cent, of a solu- 
 tion of gluten and caustic alkali made thus : to a solution 
 of caustic alkali at 32J° Tw. (20° B.) is added as much 
 bran or gluten as it will take up; after some hours' 
 digestion, the mass is filtered, and the filtrate is em- 
 ployed. 
 
 Green (W.). 1875, No. 129. Incorporates an extract of sea- 
 weed. 
 
 V. Textile. 
 
 Way (J. T.). 1875, No. 3876. Adds alumina phosphate, 
 and caustic soda to soaps for dressing woollen and silken 
 fabrics. 
 
 Soharr (J.). 1877, No. 1319. Liquid soap for scouring yarns, 
 &o. To make 100 gal. soap, mixes 66 gal. water, 
 12-21 lb. linseed, 2 lb. farina starch, 13 lb. calcined 
 potash, 162 lb. refined soda-ash, 12 lb. ro^n, 4 lb. borax, 
 3 lb. sal ammoniac, 2 gal. olein, 8 qt. spirit of turpentine 
 and 2 qt. liquid ammonia at 880° with 4r-6 qt. water. 
 
 Soharr (J.). 1879, No. 728. Soap cream for dressing textiles. 
 To make 100 gal. requires 55 lb. Marseilles soap, Gj lb. 
 sodium carbonate, 6^ lb. pearlash, 3^ lb. borax, 175 lb. 
 olive-oil, 2^ lb. Japanese isinglass, IJ lb. tragacanth, 
 J lb. salicylic acid, 37 lb. glycerin, (a) The soap, soda, 
 pearlash, and borax are boiled 2 hours in 40 gal. of 
 water ; the olive-oil is added, and boiling continued ; 
 (6) meantime the isinglass and tragacanth are steeped 
 and. boiled, the salicylic acid and glycerin being intro- 
 duced when solution is complete. When 6 is cool, a and 
 b are well mixed together. 
 Glover (J..). 1882, No. 4477. Fulling soap. Animal fibrous 
 matters are dissolved in alkali; the animal matter is 
 precipitated by acid, again dissolved by alkali, and this 
 is used for saponification. 
 
316 SUMMAET OF PATENTS. 
 
 vi. Dry. 
 
 Shaw (T.) and Blackburn (W.). 1875, No. 3955. Make 
 dry soaps in. pyramidal blocks composed of detachable 
 pieces. 
 
 vii. Disinfectant. 
 
 Cleaver (F. J.). 1875, No. 4335. Incorporates terebene, 
 
 cupralnm, or ferralnm. 
 Eobottom (A.). 1876, No. 33. Incorporates borax or other 
 
 borates. 
 
 viii. Hard-water. 
 
 Wirth (F.) : com. by C. Funk and A. Eltze. 1877, No. 1058. 
 Adds sodium phosphate, when the soap can be used in 
 hard or sea water. 
 
 ix. Cheapening. 
 
 Brandon (J.) : com. by A. Lavandier. 1874, No. 3161. In- 
 corporates 50-100 per cent, of kaolin. 
 
 Waller (T.). 1877, No. 1235. Incorporates sawdust. 
 
 Boult (A. J.) : com. by C. S. Higgins. 1881, No 2543. In- 
 corporates an unusually large percentage of rosin with 
 hard soaps. Thus for a cheap laundry soap, 10,000 lb. 
 fat is saponified in the usual way with caustic soda at 
 521° Tw. (30° B.) ; after the " grease " change, 10,000 lb. 
 rosin is added and likewise saponified, a total of 6000 lb. 
 caustic soda being needed. Saponification being com- 
 plete, and the mixture still hot and fluid, before framing, 
 2 per cent, stearic acid or 3 per cent, stearin, hot and 
 fluid, is well crutched into the body, which is then 
 framed as usual. 
 
 Armstrong (J. T.) and Bostock (W.). 1882, No. 5196. In- 
 corporate 33 per cent, of glucose. 
 
 X. Floating. 
 
 Lake (W. .E.) : com. by J. Hilgers. 1878, No. 1486. En- 
 closes a piece of cork or other light body within the 
 soap tablet. 
 
SOAP. 317 
 
 xi. Priotional. 
 
 Gross (H. B.). 1878, No. 2486. Incorporates very hard 
 angular material in a fine state of comminution, to adapt 
 the soap for cleaning and polisliing metal-work, &c. 
 
 , xii. Mineral oil. 
 
 Abel (C. D.) : com. by J. Barbieux and A. Eosier. 1879, 
 Ud. 300. About 15 per cent, of fatty matter is melted 
 in a water-bath and mixed with the mineral oil by 
 thorough stirring ; 2 parts of this and 3 of fatty matter 
 are combined ready for saponification in the usual way. 
 
 Justice (P. M.) : com. by L. Bastet. 1880, No. 3908. Makes 
 petroleum soap by treatment with alkali and boracic 
 acid. 
 
 Green (W.). 1881, No. 2682 ; 1882, No. 4226 ; 1883, No. 
 5954. Incorporates mineral oils and alkaline silicates, 
 thus: to 1 cwt. mineral oil is added 5-10 per cent, of 
 a saturated alcoholic solution of potassium subchloride 
 and caustic soda, with agitation and boiling; then 
 1 cwt. sodium silicate and 3 cwt. water, and renew 
 boiling ; then 2-3 cwt. of soap in flakes or shreds, by 
 , degrees, and with continued stirring. When m.elting 
 and admixture are complete, the mass is run into 
 frames. 
 
 Leedam (J.). 1884, No. 434. This patent is quoted as a 
 curiosity and an illustration of the progress of modem 
 days, rather than as conveying any great amount of 
 iiiformation. The patentee " desolves " 1 cwt. bar soap 
 in 75 gal. boiling water, and cools down to " 90 degrees " ; 
 then adds 9 gal. " benzoline or similar spirit extracted 
 from petrolium" together with 24 oz. "lavinder" water 
 and 6 oz. " oil of telremella." 
 
 xiii. Naphthaline. 
 
 Jeyes (W.). 1878, No. 5248 ; 1879, No. 4740. Incorporates 
 naphthaline and other coal-tar derivatives. 
 
318 SUMMARY OP PATENTS. 
 
 xiv. Mottled. 
 
 Hedley (A.). 1882, No. 3994. Prepares a " mottling " mix- 
 ture and a " ground " mixture, and incorporates them 
 while hot. 
 
 (6.) Mechanical Apparatus for Mahing. 
 
 Mills (B. J. B.) : com. hy M. and F. Hyde. 1870, No. 1766 ; 
 
 illus. Apparatus for continuous mixing by mechanical 
 
 means. 
 Anderson (J. H.). 1870, No. 2824 ; illus. Steam-jacketed 
 
 vessel with mechanical stirrer for crutching stiff-boiled 
 
 or curd soaps. 
 Edwards (E.) : com. by E. Freeland. 1874, No. 3766 ; illus. 
 
 Apparatus for heating ingredients under pressure, and 
 
 maintaining mechanical agitation. 
 ■Degener (E. L.) : com. by F. M. Weiler. 1876, No. 4560 ; 
 
 illus. Apparatus for mixing soap without admitting air. 
 Wright (W.) and Bintliff (T.). 1878, No. 3660; illus. 
 
 Apparatus for mixing hard soap with alkalies to form 
 
 soap powder, by mechanical means. 
 Pielsticker (0. M.). 1882, No. 1706; iUus. Effects con- 
 tinuous saponification by forcing the fat and alkali 
 
 through a heated coil by the aid of an injector. 
 
 (c.) Bendering Marketable. 
 
 Thomas (C). 1870, No. 496 ; illus. Uses hollow (jacketed) 
 ' frames, so that rate of cooling can be regulated by sur- 
 rounding the frame with water at desired temperature. 
 
 Cleaver (E. S.). 1870, No. 1418; illus. Apparatus for 
 moulding and stamping. 
 
 Homer (J.) and Starkey (H.). 1870, No. 3221; iUus. 
 Cut bars of soap to any required size, by means of a 
 table on which are mounted a number of frames working 
 in bearings. 
 
SBPAEATING GLYCERIN FEOM LYE. 319 
 
 Toner (J.). 1873, No. 3054; illus. Makes tablets with 
 internal cores of wood, &c., to preserve the shape pro- 
 duced by use. 
 
 O'Keeffe (J.). 1880, No. 4749 ; illus. Machine for stamp- 
 ing and moulding tablets. • 
 
 Chapelain (P.). 1881, No. 437. Makes tablets with an 
 illustration or device on paper or gelatin enclosed in 
 the centre, for decorating transparent soaps. 
 
 Eedfern (G. F.) : com. by H. Buczkowski. 1882, No. 2936 ; 
 illus. Making soap leaves. Into a mixture of 10 parts 
 glycerin and 35 parts spirit in a boiler, are introduced 
 60 parts dried shreds of glycerin soap and 50 parts 
 coco-nut-oil soap ; the whole is treated at 161^°-179^° F. 
 (72°-82° C.) with constant stirring tiU reduced to a 
 homogeneous and semi-liquid mass. To facilitate solidi- 
 fication, -^-1 per cent, oil of turpentine may be added. 
 The liquid mass is poured into a jacketed trough, where 
 the temperature is maintained. In this condition, an 
 endless roll of absorbent material, such as paper or 
 textile fabric, is passed through, excess being removed 
 by suitable rollers. 
 
 Humble (J. P.). 1884, No. 3409 ; illus. Machine for shaping 
 soap by forcing it through orifices in the moulding 
 frame. 
 
 5. Separating Glycerin from Lye. 
 
 Newton (A. V.) : com. by G. Tardani. 1874, No. 1614. The 
 liquid from the first saponification, containing 4 per 
 cent, of glycerin, is used 3 or 4 times, instead of fresh 
 water, and becomes so highly charged with glycerin as 
 to economise its recovery. 
 
 Thomas (C.) and Fuller (W. J.). 1879, No. 1282. The lye 
 is evaporated till nearly all the salts are deposited ; the 
 liquor is then boiled with excess of fatty acids to remove 
 salts in suspension, filtered, and distilled to liberate the 
 glycerin. 
 
320 SUMMARY OF PATENTS. 
 
 Lake (W. E.) : com. hy C. V. Clolus. 1881, No. 681. The 
 cold liquor is saturated with, hydroclilorio acid till 
 neutralized, and the neutral clear liquid is evaporated to 
 a density of 57° Tw. (32° B.). The glycerin present is 
 further freed from impurities by blowing in air (with 
 heat) to remove the moisture, whereby also the salts. in 
 solution are precipitated, being very slightly soluble in 
 anhydrous glycerin. The glycerin is drawn off by a 
 hydro-extractor or by dialysis. 
 
 Lake (W. E.) : com. by P. J. B. DepouUy and L. Droux. 
 1881, No. 2176. The glycerin present in spent lye 
 is combined with acids to form insoluble glycerides, 
 and the foreign matters are eliminated by washing 
 with water. The glycerin is recovered by saponifying 
 the glycerides. 
 
 Thomas (0.) and Domeier (A.). 1881, No. 2462. See p. 300. 
 
 Payne (G.). 1881, No. 2816. First saturates the unspent 
 alkali with hydrochloric acid, then separates albuminous 
 and gelatinous matters by a reagent such as tannic acid, 
 next filters and evaporates the liquid containing the 
 glycerin and sodium chloride, and finally distils the 
 glycerin. 
 
 Versmann (F.). 1'881, No. 3138. A large percentage of the 
 salts present in the lye is separated by boiling down and 
 raking them out as they become insoluble; then the 
 concentrated solution is cooled, and carbonic acid gas 
 is passed through it till all the carbonate and caustic 
 soda are converted into bicarbonate, which is much less 
 soluble .in glycerin, and can be easily removed by filtra- 
 tion. The sodium chloride still present in the glycerin 
 is eliminated by dialysis. 
 
 O'Farrell (F. J.). 1881, No. 3284; iUus. The lye is 
 evaporated down to a saturated aqueous solution, and 
 used repeatedly instead of entirely fresh salt for sepa- 
 rating the glycerin from fresh portions of soap. When 
 a maximum quantity of glycerin is thus contained in a 
 minimum of lye, the solution is evaporated to make as 
 
SEPARATING GLYCERIN FROM L¥E. 321 
 
 niTich. salt as possible crystallize out, and then the 
 glycerin is dissolved or distilled out from the re- 
 mainder. 
 Lake ("W. E.) : com. hy M. C. A. Euffin. 1881, No. 4936. 
 Causes separation hy action of superheated steam in a 
 centrifugal hydro-extractor. 
 Young (B. J.) : com. by J. P. Battershall. 1882, No. 1728. 
 Employs neutralization of the alkalies present, evapora- 
 tion, distillation, and centrifugal machines. The lye is 
 heated by steam coils in tanks and the alkali is neutra- 
 lized by adding 5 per cent, sulphuric acid (1 part water, 
 1 part acid at 168° Tw.) ; the bulk is reduced to ^ by 
 evaporation ; lime carbonate is next added to the strained 
 liquor, and concentration is continued till a syrupy con- 
 sistence is attained ; the mass is then put into a hydro- 
 extractor to separate the glycerin from the salts. Some- 
 times methylic or ethylic alcohol is added to the glycerin 
 as it leaves the centrifugal. 
 Allan (r. H. T.). 1882, No. 2449. Thoroughly spends the 
 lye, then neutralizes with mineral acid; settles, adds 
 solution of alum, or pyroligneous acid, or lime chloride ; 
 settles again, evaporates clear upper liquor to concen- 
 tration, and finally distils. 
 Clark (A. M.) : com. by E. Broohon. 1882, No. 2758. The 
 lye is treated with sodium chloride to absorb excess of 
 water, settled, and the clear liquid filtered off; this is 
 treated with slight excess of sulphuric or hydrochloric 
 acid. The part thus rendered insoluble is precipitated 
 by albumen, gelatin, or any chloride or soluble metallic 
 sulphate in the cold. The clear liquor is filtered off, 
 boiled, rendered alkaline with milk of lime which pre- 
 cipitates the metallic salts, settled, treated with just 
 sufficient soda bicarbonate to precipitate the lime, and 
 neutralized with hydrochloric acid. The liquor is boiled 
 down in a series of pans to concentrate the glycerin and 
 cause the salts to crystallize out. Finally the glycerin 
 is distilled. 
 
322 SUMMAKT OF PATENTS, 
 
 Lawson (A. J.) and Sulman (H. L.). 1882, No. 4590. The 
 lye is first evaporated down to a density of 28°-32'' Tw. 
 (18°-20° B,), and cooled. The supernatant soapy matters 
 are then skimmed off. Next the albuminous matters 
 are removed by heating and adding an astringent 
 metallic salt. The removal of the albuminous matters 
 at this stage prevents their decomposition by further 
 evaporation, and affords a purer and more concentrated 
 glycerin. The alkalinity of the liquor is first neutra- 
 lized by acid ; then the liquor is treated with a slight 
 excess of calcium carbonate, and boiled, to precipitate 
 chromic salts added as decolorizers, and neutralize any 
 remaining acid, at the same time sending down the 
 metallic salt used to precipitate the albuminous matters. 
 The resultant liquor is filtered and evaporated to yield 
 the glycerin. 
 Imray (J.) : com. by I. A. F. Bang. 1883, No. 4593. The 
 glycerin liquor from saponification is cooled to separate 
 most of the fatty acid as an emulsion, and evaporated in 
 a tin- or lead-lined vessel, with occasional addition of 
 white stearic acid, which has the effect of decomposing 
 the lime salts of the volatile organic acids. As lime 
 stearate is formed, the supply of stearic acid must be 
 renewed. The impurities go with the stearate, and the 
 glycerin is found pure beneath a crust of stearic acid 
 and stearate wheai the evaporation has been continued 
 till the density is 36°-40° Tw. (22°-24° B.) at 60° F. 
 (154° C). 
 Payne (G.). 1883, No. 5257. The lye is boHed with | its 
 weight of caustic lime, to precipitate the fatty and 
 resinous matters; neutralized with excess of hydro- 
 chloric acid, and boiled; finally excess of- acid is re- 
 moved by lime, and the product is evaporated and 
 distilled. 
 
PDEIFYING GLYCEKIN, 323 
 
 6. PtJEiFYiNG Glycerin. 
 
 Abel (0. D.) : com. by K. Kraut. 1871, No. 873. Causes 
 crystallization by keeping in closed vessels at low tem- 
 perature for a long time. 
 
 Clark (W.): com. by P. Armandy. 1881, No. 5348; illus. 
 Purifies glycerin on a commercial scale by distillation 
 in vacuo, thus avoiding carbonization and loss in escaping 
 vapours. 
 
 Payne (G.). 1882, No. 203 ; illus. . Distils glycerin in con- 
 junction with a receiver so heated that while the aqueous 
 vapour is prevented from condensing, anhydrous glycerin 
 is collected in a fluid form. 
 
 O'FarreU (P. J.). 1883, No. 1584 ; illus. Vacuum pan and 
 condenser for distUling and purifying crude glycerin. 
 
 Haddan (H. J.) : com. by C. Moldenhauer and C. Heinzerling. 
 1883, No. 2326. To completely purify glycerin from 
 salts and volatile organic acids, it is mixed with an equal 
 to a double volume of pure methyl or ethyl alcohol, and 
 rendered alkaline if necessary by adding 1-10 per cent, 
 calcined sodium carbonate ; the filtered liquor is acidified 
 to throw down the soda, and treated with soluble lead 
 salts to remove the chlorine. The alcohol and volatile 
 ethers formed are finally distilled off. 
 
 7. Eecoveeing Fat from Suds. 
 
 Smith (T. J.) : com. by C. P. Tessi6 du Motay. 1871, No. 
 1725. Calcium, magnesium, or barium bicarbonates are 
 generated in the suds from cleansing wool, &c. ; double 
 decomposition ensues; the soluble salts are filtered off; 
 the insoluble are treated with a mineral acid, which 
 isolates and permits the recovery of the resinous and 
 fatty bodies. 
 
 Thom (J.) and Stenhouse (J.). 1872, No. 2186. To soap 
 liquors obtained in clearing woven fabrics is added 
 calcium chloride ; the precipitate is filtered off and 
 
 Y 2 
 
324 SUMMABT OF PATENTS. 
 
 treated with hydrochloric acid, pressed, melted, and 
 again pressed ia a hot room, which removes most of the 
 fat in a fit state for soap-making. 
 
 Benjamin (H.). 1874, No. 682. Wool-washing suds are 
 treated with boiling alum solution (2-3 cwt. alum to 
 8000-10,000 gal. suds), stirred, stood for 24-48 hours, 
 and the liquid drained off. The greasy mud is treated 
 with hydrochloric acid to neutralize the alum ; then hot- 
 pressed ia woollen bags. The extracted grease is refined 
 by boiling with hydrochloric acid. 
 
 Mewbum (J. C.) : com. by E. Neumann. 1880, No. 243. The 
 waters from fulling mills, &c., are treated with lime- 
 water and iron or magnesium sulphate in suitable tanks. 
 The iron or magnesia soap and the calcium sulphate 
 resulting go to the bottom, leaving the water com- 
 paratively clean. The mud is repeatedly distilled to 
 afford the fatty and other matters present. 
 
 Lake (W. E.) : com. by F. Prevost. 1880, No.. 5438 ; iUus. 
 The soapy water from wool-washing is treated with a 
 mixture of 1 part sulphuric acid at 168° Tw. (66° B.) 
 and 3 parts at 116° Tw. (53° B.), and 1 part of hydro- 
 chloric acid at 36° Tw. (22° B.). A fatty magma floats, 
 and is strained off; this is boiled with addition of some 
 dry sawdust, and meanwhile constantly stirred. 
 
 8. Candles. 
 (a.) Preparing Combustible. 
 
 Lake (W. E.) : com. by A. GreU. 1872, No. 1176 ; iUus, 
 Obtains stearin and olein from fats and greases by 
 solution in " the products of distillation of naphtha." 
 
 Clark (A. M.) : com. by E. Deiss. 1872, No. 3328. Separates 
 stearin from olein by replacing the usual hot pressing 
 of the cakes by a cold pressing with the aid of carbon 
 bisulphide, or other volatilizable solvent. 
 
 Morgan-Brown (W.) : com. by E. Bastie. 1874, No. 8021. 
 Transforms oleins into crystalline substances, by con- 
 
CANDLES. 325 
 
 tact with reagents whioL. cause the reduction of any 
 
 peroxide. 
 Pielsticker (C. M.). 1876, No. 797. Eefines crude ozokerit 
 
 by agitation first with sulphuric acid, and afterwards 
 
 with barium carbonate and caustic soda. 
 Thellot (J.). 1876, No. 2893. Uses petroleum in making 
 
 candles. About 20 parts powdered camauba wax is 
 
 added to 80 parts petroleum heated to 160° P. (71° C); 
 
 the two combine, and solidify on cooling. 
 Wirth (F.): com. by A. MuUer-Jacobs. 1881, No. 1786. 
 
 Oils at 140° V. (60° C), are mixed with 30-40 per cent. 
 
 sulphuric acid at 164°-165° Tw. (65° B.). When the 
 
 mixture has a temperature of 95° F. (35° C), it is mixed 
 
 with double the yolume of cold water under constant 
 stirring. The sulpho-fat acid produced, after boiling for 
 24 hours, is separated and boiled continuously in several 
 times its volume of water, being thereby converted into 
 a solid fat-acid, resembling stearic acid, melting at 159° F. 
 (70 "6° C), and into liquid oxyoleic acid. From the 
 separated fat-acids soluble in alcohol, the solid consti- 
 tuents are allowed to crystallize out by standing 2-3 days 
 in the cold, after which the liquid constituents (say 40 
 per cent.) are -separated by centrifugals or presses, and 
 the cake is washed and distilled. 
 
 (6.) Preparing Wicks, 
 
 Pickering (J.). 1871, No. 2796. Uses flat wicks, preferably 
 of cotton roving. 
 
 Hill (W. F.). 1875, No. 8738 ; Ulus. Spinning candle-wick 
 yarn. 
 
 Field (J. L.). 1879, No. 2061. Treats wicks to prevent 
 smouldering when extinguished, by steeping them in a 
 solution of phosphoric acid, or ammonium phosphate, or 
 ammonium phosphate and borax, or ammonium phos- 
 phate and boracic acid. 
 
 Pirie (L. J.) and Findlay (H.). 1888, No. 8787; illus. 
 Machine for plaiting candle-wicks. 
 
326 SUMMARY OF PATENTS. 
 
 Mills (B. J. B.) : com. by A. Duparquet. 1884, No. 5734. 
 Treats wicts to prevent smoke and smell on extinction. 
 Bleached wicks are soaked for J hour in a bath contain- 
 ing 16 grm. ammonium phosphate and 7 grm. sulphuric 
 acid at 168° Tw. (66° B.) per litre of distilled water, the 
 acid being added when the phosphate is weU dissolved. 
 Unbleached wicks require 40 minutes' soaking, and need 
 a preliminary cleaning in a bath of 6J oz. volatile am- 
 monia, 1 oz. sulphuric acid at 168° Tw. (66° B.) in 246 oz. 
 water, the mixture being boiled by steam, and the wicks 
 kept in for IJ hour, then boiled for J hour in pure 
 water, rinsed in cold water, wrung, and dried, ready for 
 the second bath. 
 
 (c.) Uniting Wick and Cmiibustible. 
 
 Ascough (J.). 1870, Nos; 835, 3288; 1871, No. 3478; all 
 iUus. Forming and arranging the rods and blocks 
 employed to carry the wicks during dipping ; adapted 
 for snuffless and other " dips." Also winding the wick 
 material. 
 
 Watson (J., C, and G.). 1870, No. 890 ; illus. Means for 
 raising and moving very large frames, so that more 
 candles can be dipped by 1 man at a time. 
 
 Cowles(E.)andBrash(P.). 1870, No. 2078 ; iUus. Moulds 
 and frames for making candles with soft cores. 
 
 Mallory (S.). 1870, No. 3193; illus. Eods for dipping 
 candles. 
 
 Field (A.). 1861, No. 3032; 1872, No. 2652; 1874, No. 1682 ; 
 all iUus. Moulding candles with taper bases. 
 
 Spicer (G. H.). 1876, No. 1863; illus. Apparatus for 
 moidding candles with enlarged, conical, fluted ends. 
 
 Beck (W. H.) : com. by A. A. Eoyau. 1880, No. 4666 ; illus. 
 Moulding frame, capable of alternate warming and 
 cooling, hastening the output and improving the 
 » appearance of the candles. 
 
 Nutt (W. E.). 1880, No. 5507 ; illus. Machine for moulding 
 taper-ended candles. 
 
CANDLES. 327 
 
 Groth (L. A.): com. by L. C. A. and C. E. Motard. 1881, 
 
 No. 4816 ; illus. Machine for cutting off candle-ends 
 
 without damage. 
 Cowles (E.). 1882, No. 5595; illus. Moulding machines 
 
 requiring much less cold water than usual. 
 Beck (W. H.) : com. by Societe anonyme des machines a 
 
 bougies et chandelles, systeme Eoyau. 1883, No. 3187 ; 
 
 illus. Machine specially adapted for moulding candles 
 
 requiring to be dealt with at a low temperature, and to 
 
 be promptly cooled. 
 Wigfleld (W.). 1884, No. 4137; illus. Moulding candles 
 
 with taper ends. 
 
 [d.) Packing Candles. 
 Thomas (C.) 1877, No. 4117 ; illus. 
 
 (e.) Disinfectant Candles. 
 
 Webb (A. E.). 1873, No. 728. Adds iodine chloride or 
 carbolic acid, say 1 dr. per lb. 
 
 Wirth (F.): com. by W. Eeissig. 1874, No. 2884. Adds 
 sulphur or organic sulphides. 
 
 Clarke (S. and G. B.). 1875, No. 685. Add ^ part cam- 
 phor. 
 
 Lake (W. E.) : com. by P.L. Quarante. 1876, No. 461. Adds 
 disinfectants. 
 
 Wright (A.). 1884, No. 11963. Adds 5-10 per cent, of 
 eucalyptus and (or) cajeput oils, with some carbolic 
 acid. 
 
 (/.) Fancy Candles. 
 
 Sterry (A. C). 1871, No. 95. Uses inferior parafSn for semi- 
 transparent candles, and gains a pearly effect by a wick 
 coloured blue or violet. 
 
328 SUMMAEY OF PATENTS. 
 
 (g.) Ozokerit Candles. 
 
 Field (F.) and Siemssen (G-.). 1870, No. 961. Distil the 
 raw material, and the solid ,and liquid parts of the oUy 
 distillate are separated by pressure, and refined (p. 252). 
 
 White (G.) : com. by 0. Beurle and H. Ujhely. 1871, No. 
 2364. Uses " ceresine,'' prepared from crude ozokerit. 
 
 Qi.) Perfecting Combustion. 
 
 Field (J. K.). 1870, No. 2513 ; illus. Makes lateral aper- 
 tures near the base of candles to admit air for passage 
 through longitudinal apertures, so that the air issuing 
 near the flame may perfect the combustion. 
 
 Greaves (J. E.). 1870, No. 2680 ; illus. Prevents " guttering " 
 by making the candle fluted externally. 
 
 Field (A.). 1870, No. 3397 ; 1871, Nos. 122, 1763 ; all iUus. 
 Makes candles with spiral passages to receive surplus 
 melted material, and perfect combustion. Also makes 
 them with hollow centre, to be afterwards filled with 
 material of another colour or kind. 
 
 Lyttle (W. A.). 1872, No. 3741 ; 1878, No. 3312 ; iUus. 
 Attaches an incombustible base (of plaster, pottery, -(fee). 
 
 LasteUe (F. M, de). 1876, No. 2461; iUus. Increases 
 luminosity of candles by arranging a number of wicks 
 in a circle, and having a hole through the centre of the 
 candle to admit air. 
 
 Brewer (E. G.) : com. by F. M. Joly. 1881, No. 209 ; iUus. 
 Makes wick* with independent core pieces, to perfect the 
 combustion and avoid the necessity for snuffing. 
 
 (i.) Night-ligMs. 
 
 Payne (G.) and Freestone (J. W.). 1874, No. 1541 ; illus. 
 Make night-lights with paper bottom above the plaster 
 filling ; fix the wick out of the centre of the paper, to 
 ensure its perfect combustion by inclining to one side ■ 
 
NIGHT-LIGHTS. 329 
 
 make the wicks of " inkle," witli a wire running through 
 to regulate the position ; and gimp the inkle and wire 
 together. Also make the wicks of bibulous paper. 
 
 Clarke (S.). 1883, No. 5877 ; illus. Makes night-lights with 
 a plaster casing, to ensure complete combustion of the 
 fatty matter. The plaster bottom is made concave. 
 
 Groth (L. A.): com. by F. E. Berta. 1884, No. 3434; illus. 
 Makes night-light cases iu one piece, and fixes the wick 
 upright tiU aU the material is consumed. 
 
( 330 ) 
 
 CHAPTEE XV. 
 
 BIBLIOGEAPHY. 
 
 In tlie preceding pages many references have already been 
 made to tlie various books and papers dealing with the 
 industry under notice. Following is a summary of the most 
 important literature on the subject. 
 
 Allen (A. H.). 
 
 Handbook of Commercial Organic Analysis. 
 
 London, 
 Bernardin (P. J.). 
 
 Classification de 160 Huiles et Graisses Vegetales, et 95 
 Huiles et Graisses Animales. 2nd ed. Ghent : 1874. 
 Chateau (T.). 
 
 La Connaissance et I'Exploitation des Corps Gras Indus- 
 trielB. 2nd ed. Paris : 1863. 
 
 Cristiani (K. S.). 
 
 Soap and Candles, with a glance at the Industry of Fats 
 andOUs. PhUadelphia: 1881. 
 
 Cross (C. F.). 
 
 Health Exhibition Lecture on Soap. London : 1884. 
 
 Dalican et Jean. 
 
 Methodes Chimiques servant a determiner la Valeur 
 commerciale des Matieres Grasses, Glycerines, Savons, 
 Cires, &c. Paris [Moniteur Scientifique] : 1868. 
 
 Decugis (B.). 
 
 Les Tourteaux des Graines oleagineuses. Toulon. 
 
 Deite(C.). 
 
 Die Industrie der Fette. Brunswick : 1878. 
 
BIBLIOGBAPHT. 331 
 
 DuBsauce (H.). 
 
 The Manufacture of Soap. Philadelphia : 1869. 
 
 Field (L.). 
 
 Solid and Liquid Illuminating Agents. 
 
 (Cantor Lecture, Soc. of Arts, 1884.) 
 Hake (C. N.). 
 
 The Stassfurt Salt Industry. 
 
 (Jl. Soc. Ohem. Industry, ii. 146-52.) 
 Hofmann (A. W.). 
 
 Entwickelung der Cheiaischen Industrie. 
 
 Brunswick: 1877. 
 Lovine (G. E.). 
 
 Traite de la Fabrication des Savons. Paris : 1859. 
 
 Lunge (G.). 
 
 Manufacture of Sulphuric Acid and Alkali. 
 
 London: 1879. 
 Morfit (C). 
 
 Soaps. New York: 1871. 
 
 Spons' Encyclopssdia of the Industrial Arts, Manufactures 
 and Commercial Products. London : 1882. 
 
 TomUnson (C). 
 
 Verification of Olive-oil by means of its cohesion-figure. 
 (Jour. Soc. Arts, xii. No. 589. London : 1864.) 
 
 Wiesner (J.). 
 
 Die Eohstoffe des Pflanzenreiches. Leipzig : 1873. 
 
 Wilson (G. F.). 
 
 The Manufactures of Price's Patent Candle Co. 
 
 (Jour. Soc. Arts, iv. 148.) 
 Wiltner (F.). 
 
 Seifen fabrikation. Vienna. 
 
 Windakiewicz (B.). 
 
 Das Erdol und Erdwachs in GaHzien. 
 
 (Berg, und Huttenmannisohes Jahrbuch, 
 Bd. xxiii. Heft. 1. Vienna: 1875.) 
 
332 BIBLIOGEAPHY. 
 
 Wright (C.E. Alder). 
 
 The Manufacture of Toilet Soaps. 
 
 (Cantor Lecture, Soc. of Arts, 1885.) 
 
 ' Analyst.' London. 
 
 ' Dingler's Polyteohnisches Journal.' 
 
 ' Journal of the Society of Arts.' London. 
 
 ' Journal of the Society of Chemical Industry.' London. 
 
 ' Seifensieder Zeitung.' 
 
( 333 ) 
 
 INDEX. 
 
 Abboeption bands of oils, 99 
 Acetic acid series, 7 
 Acid processes for refining oils, 73 
 Acidification of neutral fata, 263-6 
 Acidity of oils, 231 
 Acrolein, 295 
 Acrylic acid series, 7 
 Action of soap, 207-14 
 Adams' bone-boiler, 27 
 Admixtures with soft soap, 162 
 Adulteration of soap, 184^8,212, 213 
 African vegetable tallow, 65 
 Alkali in soap, estimating, 215 
 
 making, 106-43 
 
 Alkalimetrical table, 131 
 Alkaline processes for refining oils, 
 
 74 
 
 salts in soap, estimating, 216 
 
 Almond soap, 198 
 
 Alumina in soap, estimating, 216 
 
 Aluminate of soda, 142 
 
 Ammonia-soda process, 107 
 
 Analyzing fats, 82-105 
 
 containing soluble and 
 
 insoluble fatty acids, 89-91 
 
 soap, 214-25 
 
 , Leeds' scheme, 222-3 
 
 , short methods, 221-4 
 
 Andaquies wax, 243 
 
 Animal fats, 15-32 
 
 Anti-friction greases, 234-6 
 
 Arachis oil, 60-1 
 
 Autoclave process for decomposing 
 
 tallow, 257 
 
 glycerin, 295 
 
 Available soda in soap, 127 
 
 B 
 
 AGGiNG spermaceti, 241 
 
 Ball soda, appearance, 116 
 
 , composition, 115 
 
 Ball soda furnace, effects of, 115 
 , working capacity, 
 
 furnaces, 110-3 
 
 making, 108 
 
 mixtures, 110, 123 
 
 Balling operations, 113 
 
 Bambouk butter, 62-3 
 
 Bar soap, 177 
 
 Basis for selling palm-oil, 35 
 
 Baasia Parkii oil, 62-3 
 
 Baume's hydrometer, 132 
 
 Beeswax, 239-40 
 
 Behaviour of soap to saline solu- 
 tions, 13 
 
 Benn^ oil, 59-60 
 
 Bibliography, 330-2 
 
 Bichrome for bleaching oils, 79 
 
 Bisulphide of carbon for extracting 
 oils, 37-9 
 
 Black-ash, lixiviation, 116-22 
 
 making, 108 
 
 kernel oil, 37 
 
 Blanc de baleine, 240-2 
 
 Bleaching oils and fats, 70-81 
 
 Blue mottled soap, 190-3, 224 
 
 Bock's process for decomposition of 
 neutral fats, 263-6 
 
 Boiling soaps under pressure, 152 
 
 Bone grease, 26-30 
 
 — , lime in, 74 
 
 Borax in soap, 142 
 
 Borith, 1 
 
 Braided wicks, 275 
 
 Brassica oils, 59 
 
 Bromine absorption teat for oils, 103 
 
 Brown almond soap, 193 
 
 kernel oil, 37 
 
 Windsor soap, 198 
 
 Brownian movement, 207 
 
 Burette for testing lye, 128 
 
 Butter, Bambouk, 62-3 
 
334 
 
 INDEX. 
 
 Butter for soap-making, 31 
 
 , Galam, 62-3 
 
 , Shea, 62-3 
 
 Butterine, 17 
 
 for soap-making, 31 
 
 Butyrospennum oil, 62-3 
 
 a 
 
 ^ALOiuM carbonate for alkali mak- 
 ing, 109 
 
 Oameroons palm oil, 85 
 
 Candle-works, olein from, 67, 145, 
 224, 267 
 
 Candles, commerce in, 287 
 
 , conical butt, 281 
 
 , dipping, 277-8, 326 
 
 , disinfectant, 327 
 
 , fancy, 327 
 
 , Mstorical sketch, 237-8 
 
 , illuminating value, 287-93 
 
 in ball-soda process, 114-5 
 
 , manufacture, 373-84 
 
 , moulding, 278-84, 326 
 
 , night-lights, 284-6, 328 
 
 , ozokerit, 328 
 
 , packing, 327 
 
 , palmitic acid, 269 
 
 , paraffin for, 250-1 
 
 , patents, 324-9 
 
 , perfecting combustion, 328 
 
 , pouring, 278 
 
 , preventing guttering, 283, 328 
 
 , raw materials, 238-52, 324 
 
 , tallow, compared with bou- 
 gies, 258 
 
 , trimming, 282 
 
 , waxes, 238-43 
 
 , wicks, 273-7, 325 
 
 Carbolic acid in soap, estimating, 
 217 
 
 soap, 194 
 
 Carbon bisulphide for extracting 
 oils, 37-9 
 
 Carbonic acid, determining, 129 
 
 — — in soap, estimating, 216 
 
 Carnauba wax, 243 
 
 Cartouche for fusing oleic acid, 268 
 
 Case-hardening soap, 179 
 
 Castile soap, 192 
 
 Castor cake, recovering oil from, 39 
 
 oil, 44-6 
 
 seed oil, extracting machinery, 
 
 48-55 
 
 Causes of different combining pro- 
 portions, 6 
 Caustic alkali, 106-43 
 
 lye from soda ash, 135 
 
 , making, 106-43 
 
 , settling, 125 
 
 , storing, 125 
 
 potash, 136-40 
 
 for solidifying fatty 
 
 bodies, 267-72 
 
 lye, 139 
 
 Causticity of lye, testing, 130 
 Cauatioizers, 123 
 Caustioizing processes, 106 
 
 tank liquors, 122-7 
 
 Ce fat, 62-3 
 
 Chalk for alkali making, 109 
 Cheapening soap, 316 
 Chinese vegetable tallow, 64 
 
 wax, 242-3 
 
 Chloride of lime for bleaching oil, 
 
 78 
 Chlorine in soap, estimating, 216 
 Choice of fatty matters for soap, 14 
 Chromium oxide, recovering from 
 
 bleached fats, 79 
 Chung peh-la, 242-3 
 Clarifying oils and fats, 70-81 
 Clark's test for hardness of water, 
 
 68 
 Cleaning cotton-seed, 47 
 Cleansing, how performed, 207-14 
 Clear-boiling hard soap, 168 
 Coal for alkali making, 110 
 
 minerals, distilling, 244 
 
 tar soap, 194 
 
 Coconut oil, 41-4 
 
 extracting machinery, 
 
 48-55 
 
 rasping machine, 55 
 
 slicing machine, 55 
 
 Cocos nucifera oil, 41-4 
 
 Coction, 168 
 
 Coffee palm-oil, 36 
 
 Cogan's process for purifying oil, 
 
 73 
 Cold drawn linseed oil, 57 
 
 water soap, 195, 224 
 
 Colophony, 66-7 
 
 , characters, 11 
 
 Colour tests for oils, 99 
 Coloured soaps, 202 
 Colza-oil, 59 
 
INDEX. 
 
 335 
 
 Combining proportions of salts, 5 
 Composition of coconut, 41 
 Concentrating lye, 300 
 
 sweet waters, 296 
 
 Conical butt candles, 281 
 Consistency of soap, 210 
 Constituents of fats, 82 
 Converting neutral fats into fatty 
 
 acids, 253-72 
 Converting oleic into palmitic acid, 
 
 266-72 
 Cook and Hall's system of render- 
 ing suet, 17 
 Cooking-cupboards for paraffin, 250 
 Cooling soa,p, 175-7 
 Copperah oil, 41-4 
 Coppers, soap, 155-7 
 
 , , curb for, 166 
 
 , - — , emptyiQg, 174 
 
 , , fan for, 158 
 
 , , hat for, 156 
 
 Copra oil, 41-4 
 
 Correcting rancidity of oils, 76 
 
 Cost of light, 287-93 
 
 of Eadisson's palmitic acid, 
 
 271-2 
 Cotton seed oil, 46-57 
 , extracting machi- 
 nery, 48-55 
 
 Waste, grease from, 39 
 
 wicks, 274 
 
 Cowles' frames, 279 
 Croton sebiferum fat, 64 
 Crushing oil seeds, 49 
 Crutchiog soap, 187 
 Crystallization of alkaline salts of 
 
 acetic acid series, 12 
 Cuba wax, 243 
 Curb for soap-coppers, 166 
 Curd soaps, 169, 224 
 Curriers' grease, 31 
 Cutting soap, 177-80 
 
 JJecolobizing oils, 77 
 Decomposing fats in open vessels, 
 
 263-6 
 
 , patents, 310-3 
 
 Definition of a salt, 3-4 
 
 soap, 3-4 
 
 Deitz's carbon bisulphide apparatus 
 
 for extracting oils, 37-9 
 Densities of soda solutions, 132 
 
 Deodorizing oils, 76 
 Detecting gingelly oil, 60 
 
 rosin oil in mineral oil, 231 
 
 Detergent soap, 314 
 
 Determining carbonic acid, 129 
 
 Dika fat, 62 
 
 Dip candles, 277-8 
 
 Dirt, how removed, 207-14 
 
 Disinfectant soaps, 194-5, 316 
 
 Disposal of tank waste, 122 
 
 Distilling coal minerals, 244 
 
 fats in superheated steam, 80 
 
 glycerin, 297 
 
 tallow, 258-61 
 
 Distinction between hard and soft 
 
 soaps, 12 
 Dole's cylinder for rendering tallow, 
 
 16 
 Dry soap, 316 
 Drying soap, 179 
 Dyers' soaps, 197 
 
 JilAETH-WAX, 251-2 
 
 Egg-yolks for soap-makiog, 68 
 
 Blseis guineensis oil, 32-6 
 
 Blaidin test for oils, 100 
 
 Elder-flower soap, 203 
 
 Emollient soap, 314 
 
 Emp8.tage, 167 
 
 Emptying soap-coppers, 174 
 
 Equivalents of salts, 5 
 
 Estimating alkali in soap, 215 
 
 alkaline salts in soap, 216 
 
 carbolic acid in soap, 217 
 
 fatty acids in soap, 218-21 
 
 free fatty acids, 85-6 
 
 glycerin in fats, 91 
 
 soap, 217 
 
 insoluble ingredients in soap, 
 
 216 
 
 mineral matters in fats, 84-5 
 
 moisture in fats, 83-4 
 
 oleic acid, 88-9 
 
 organic matters in fats, 84-5 
 
 total fatty acids, 86-8 
 
 unsaponifiable oils in fats, 91 
 
 vmsaponified fat in soap, 218 
 
 water in soap, 214 
 
 Evaporateur universel, 296 
 Bvrard's process for refining oils, 74 
 Examining fatty acids in soap, 218- 
 21 
 
336 
 
 INDEX. 
 
 Excoeoaria sfebifera fat, 64 
 
 Extracting castor-oil, 45 
 
 CMnese vegetable tallow, 64 
 
 cooontit-oil, 42-3 
 
 gingelly oil by French pro- 
 cesses, 59-60 
 
 oUs by carbon bisulphide, 37-9 
 
 modern machinery, 
 
 48-55 
 
 petroleum spirit, 39 
 
 &om seeds, 48-55 
 
 palm-nut-oil, 36-9 
 
 palm-oil, 32-3 
 
 shea butter, 62-3 
 
 F 
 
 ^ AN for soap coppers, 158 
 Farina in soap, estimating, 216 
 Fat, c4, 62-8 
 
 , croton, 64 
 
 , diia, 62 
 
 , exctBcaria, 64 
 
 , hopea, 65 
 
 , kanya, 65 
 
 , lulu, 62-3 
 
 , pentadeama, 65 
 
 , recovering from suds, 323-4 
 
 , sapium, 64 
 
 , seeding, 17 • 
 
 , stiUingia, 64 
 
 , tetranthera, 65 
 
 Fats, analysis of, 82-105 
 
 , animal, 15-32 
 
 as glycerides, 82 
 
 , bleaching, 70-81 
 
 , clarifying, 70-81 
 
 , decomposing, 263-6, 310-3 
 
 . , free fatty acids, in, 85-6 
 
 , glycerin in, 91 
 
 , mineral matters in, 84-5 
 
 , moisture in, 83-4 
 
 , oleic acid in, 88-9 
 
 , organic matters in, 84-5 
 
 , purifying, patents, 309-10 
 
 , refining, 70-81 
 
 . rendering, 16-22, 24-5, 26-30 
 
 , in soap-copper, 21 
 
 , under pressure, 18 
 
 , sampling, 83 
 
 , total fatty acids in, 86-8 
 
 , unsaponifiable oils in, 91-2 
 
 , unsaponified, glycerin from, 
 
 801-2 
 
 Fatty acids, 7 
 
 , , convertiag neutral fats 
 
 into, 253-72 
 
 (free) in fats, 85-6 
 
 , fusing-points of, 95-8 
 
 in natural fats, table of, 8 
 
 in soap, estimating, 218- 
 
 21 
 , examining, 
 
 218-21 
 
 (insoluble) in fats, 89-91 
 
 , melting-point of, 95-8 
 
 , solidifying-point of, 95-7 
 
 (soluble) in fats, 89-91 
 
 (total) in fats, 86-8 
 
 bodies, solidifying by potash, 
 
 267-72 
 
 matters for soap, choice of, 14 
 
 - — , purifying, patents, 309 
 
 Field and Siemssen's treatment of 
 
 ozokerit, 252 
 Fig in soap, 12 
 Figging soft soaps, 159, 161 
 Filling soaps, 184-8 
 Filtering lime mud, 126 
 
 oils, 71 
 
 Fine toilet-soaps, 198-206 
 Fish-oils for soap-making, 31 
 Fitting yellow soaps, 172 
 Flashing-point of oUs, 231-3 
 Flax seed oil, 57-8 
 
 wicks, 274 
 
 Floating soap, 316 
 
 Foots from oil refineries, 68 
 
 Formulse of fats, 11 
 
 Foxy tallow, 23 
 
 Frames for moulding candles, 279 
 
 soap, 175-7 
 
 Free fatty acids in fats, 85-6 
 Freezing water out of glycerin, 303 
 French processes for extracting 
 
 gingelly oil, 59-60 
 Frictional soap, 316 
 Fulling soap, 197, 315 
 Fusing-points of fatty acids, 95-8 
 
 (jTalabedn's frame, 282 
 Galam butter, 62-3 
 Gauge tanks, 159 
 Grimping wicks, 275 
 Gingelly oil, 59-60 
 
INDEX. 
 
 337 
 
 Gingelly seed oil, extracting ma- 
 chinery, 48-55 
 
 Glue grease, 31 
 
 Glycerin, 294-308 
 
 as a trivalent alcohol, 9 
 
 , autoclave process, 295-8 
 
 ; characters, 303-7 
 
 , commerce in, 308 
 
 , distilling, 297 
 
 , early production, 294 
 
 , freezing water out of, 303 
 
 from fats prior to saponifica- 
 tion, 301-2 
 
 neutral fats, 81 
 
 spent lye, 81, 298-301, 
 
 319-22 
 
 in fats, 91 
 
 in soap, estimating, 217 
 
 — — mixtures, freezing-points of, 
 303 
 
 , purifying, 297, 301, 303, 
 
 323 
 
 , separating from lye, 319- 
 
 22 
 
 soap, 198, 203, 205-6 
 
 , solidified, 205-6 
 
 , solvent powers, 304 
 
 , uses of, 307 
 
 Grain in soap, 12 
 
 Grease, bone, 26-30, 74 
 
 , curriers', 31 
 
 from castor cake, 39 
 
 cotton waste, 39 
 
 , glue, 31 
 
 , kitchen, 30 
 
 , locomotive, 235 
 
 , mares', 26 
 
 mottled soap, 224 
 
 , raUway, 234-6 
 
 , ships', 30 
 
 , skin, 31 
 
 , waggon, 234^6 
 
 Greases, anti-friction, 234-6 
 
 Grey mottled soap, 190-3 
 
 Ground nut oil, 60-1 
 
 , extracting machi- 
 nery, 48-55 
 
 Guizotia oleifera oil, 61-2 
 
 Gumming of oils, 230 
 
 Gutta-shea, 63 
 
 Guttering of candles, preventing, 
 283 
 
 m 
 
 AND-PBAMES for Candle?, 279 
 
 Hard and soft soaps contrasted, 12 
 
 soap, 164-9 
 
 , boiling, 166 
 
 , clear boiling, 167 
 
 , pasting, 167 
 
 , separation, 167 
 
 without boiling, 145 
 
 water soap, 316 
 
 Hardness of water, 210 
 
 Hat for soap -coppers, 156 
 
 Hawes' boUer, 151 
 
 Heat evolved in chemical combina- 
 tions, 6 
 
 Hempseed oil, 58-9 
 
 extracting machinery, 
 
 48-55 
 
 Hersey's soap-pump, 165 
 
 History of soap, 1-2 
 
 Home-made soap, 144 
 
 Honey soap, 193, 198, 203 
 
 Hopea fat, 65 
 
 Horse-grease, 26 
 
 Household soaps, 144-73, 193-6, 314 
 
 Hiibl's iodine test, 104 
 
 Hydrated soap, 163-4 
 
 Hydrocarbon oils in soap, estimating, 
 218 
 
 Hydrolysis, 9 
 
 Hydrometers, 132-3 
 
 iDENTii'vrNfG oils in mixtures, 98- 
 
 105 
 Dlumiuating value of candles, 287- 
 
 93 
 Inkle, 274 
 
 Insoluble fatty acids in fats, 89-91 
 ingredients in soap, estimating, 
 
 216 
 Iodine degree of oils, 104 
 Irvingia Barter! oil, 62 
 
 } APAN wax, 243 
 
 xLala 
 
 .A-THi, 59 
 
 Kanya fat, 65 
 Kernel oil, 36-40 
 
338 
 
 INDEX. 
 
 Kersanee oil, 61-2 
 Kettle for extracting seed-oils, 51 
 Killing the goods, 167 
 Kitchen grease, 30 
 Koetstorfer's test for oils, 102 
 
 Jjagos palm-oil, 34 
 Lard, 24-6 
 
 oil, 26 
 
 Laundry soaps, 193-6 
 
 Leaf lard, 25 
 
 Leather tallow, 31 
 
 Leblanc process for soda, 107 
 
 Leeds' scheme for soap analysis, 
 
 222-3 
 Lemon soap, 203 
 Levant gingelly oil, 59 
 Light, cost of, 287-93 
 Ligliting agents compared, 287-93 
 Lime chloride for bleaching oils, 78 
 
 for decomposing fats, 310 
 
 in bone fat, 74 
 
 mud filtering, 126 
 
 saponification of tallow, 254-6 
 
 soap, decomposing, 295 
 
 Limestone, composition, 109 
 
 for alkali makiiig, 109 
 
 Linseed-oil, 57-8 
 
 , extracting machinery, 
 
 48-55 
 Liuum usitatissimum oil, 57-8 
 Liquid soap, 314 
 Liquidation of yellow soap, 172 
 Literature, 330-2 
 Lixiviation of black ash, 116-22 
 Locomotive grease, 235 
 London pale soap, 188 
 Lubricants, general rules for, 233-4 
 Lubricating oils, 229-34 
 Lulu fet, 62-3 
 Lye, 6 
 
 , concentrating, 300 
 
 , making, 106-43 
 
 (spent), composition, 298 
 
 ( ), glycerin from, 298-301, 
 
 319-22 
 (■- — ), separating soap from, 
 
 313 
 
 , storing, 125 
 
 , testing, 127-33 
 
 ■ , causticity, 130 
 
 JMachine for moulding oil-seed 
 cake, 52 
 
 rasping coconut, 55 
 
 slicing coconut, 55 
 
 Machinery for extracting seed oils, 
 48-55 
 
 Malayan vegetable tallow, 64-5 
 
 Manufacturers' brown oil soap, 224 
 
 soap, 196-8 / 
 
 Mares' grease, 26 / 
 
 Marine soap, 225 / 
 
 Marseilles soap, 192 
 
 Marsh-mallow soAp, 199 
 
 Maumene's test for oil, 100 
 
 Mege-Mouries' rendering process, 18 
 
 Melting-point of fatty acids, 95-8 
 
 Mill for crushing oil-seeds, 49 
 
 Millefleur soap, 203 
 
 Mineral impurities in soap, estima- 
 ting, 216 
 
 matters in fats, 84-5, 
 
 oil, detecting rosin-oil in, 231 
 
 soap, 317 
 
 salts used in soap-making, 
 
 106-43 
 
 Mixers for filling soap, 185 
 
 Mixing coal, 110 
 
 Mixtures for cold process soaps, 152 
 
 for soaps boiled under pressure, 
 
 153 
 
 Moisture in fats, 83-4 
 
 ' Molecular weights of fatty acids, 7 
 
 Monrovian palm-oil, 35 
 
 Morfit's steam-twirl, 150 
 
 Morris and GrifSn's bone-boiler, 27 
 
 Mottled soap, 170, 190-3, 318 
 
 Moulding candles, 278-84 
 
 machine for oil-seed cakes, 52 
 
 Mud, filtering, 126 
 
 JN APA oils, 59 
 
 Naphthaline soap, 317 
 
 Nether, 2 
 
 Neutral fat, type of saponification 
 
 of, 7 
 fats, as compound ethers of a 
 
 trivalent alcohol, 9 
 , converting into fatty 
 
 acids, 253-72 
 
 soaps, 196-8, 206 
 
 soda soap for wool, 163 
 
INDEX. 
 
 339 
 
 Niger-seed oil, 61-2 
 
 extracting machi- 
 nery, 48-55 
 
 Night-lights, 284-6 
 
 Nitrous acid for bleaching and 
 solidifying oils, 80 
 
 Nuisances in soap-making, 226 
 
 
 
 EJECT of the soap-maker, 11 
 Oouba wax, 243 
 Odours of oils, 98-9 
 Oil, arachis, 60-1 
 
 , bassia Parkii, 62-3 
 
 -, benn^, 59-60 
 
 , black kernel, 37 
 
 , brassica, 59 
 
 , brown kernel, 37 
 
 , butyrospermum, 62-3 
 
 , Cameroons palm, 85 
 
 , castor, 44-6, 48-55 
 
 , coconut, 41--4, 48-55 
 
 , coffee palm, 36 
 
 , colza, 59 
 
 , eopperab, 41-4 
 
 , copra, 41-4 
 
 , cotton-seed, 46-57 
 
 , elaeis, 32-6 
 
 , fish, 31 
 
 , flax-seed, 57-8 
 
 , gingelly, 59-60 
 
 , ground-nut, 48-55, 60-1 
 
 , gulzotia, 61-2 
 
 , hempseed, 48-55, 58-9 
 
 , Irvingia, 62 
 
 , kernel, 36-40 
 
 , kersanee, 60-2 
 
 , Lagos palm, 34 
 
 , lard, 26 
 
 , Levant gingelly, 59 
 
 , linseed, 48-55, 57-8 
 
 mill machinery, 48-55 
 
 , Monrovian palm, 35 
 
 , napa, 59 
 
 , niger seed, 48-55, 61-2 
 
 , olive, 40-1, 48-55 
 
 , palm kernel, 36-=40 
 
 , nut, 36-40 
 
 , kernel, 36-40 
 
 , pyrene, 37, 41 
 
 ■, rabat, 59, 61 
 
 , ram-til, 61-2 
 
 Oil, rape-seed, 48-55, 59 
 
 , red, 145, 224, 267 
 
 , refiners' foots, 68 
 
 , ricinus, 44-6 
 
 , salad, 41 
 
 , Saltpond palm, 35 
 
 , sesame, -59-60 
 
 , sunflower-seed, 48-55 
 
 , til, 59-60 
 
 , virgin olive/ 40 
 
 , white kernel, 36 
 
 , Windward palm, 35 
 
 Oils, absorption bands, 99 
 
 , acidity, 231 
 
 , bleaching, 70-81 
 
 , bromine absorption test for, 
 
 103 
 
 , characters, 229-34 
 
 , clarifying, 70 
 
 , colour tests, 99 
 
 , detecting rosin in, 103 
 
 , elaldin test for, 100 
 
 , fish, 31 
 
 , flashing-point, 231-3 
 
 , gumming, 230 
 
 in mixtures, identifying, 98- 
 
 105 
 
 , Iodine degree of, 104 
 
 , lubricating, 229-34 
 
 , Maumene's test, 100 
 
 , odours of, 98-9 
 
 , refining, 70-81 
 
 , soap-precipitation test for, 101 
 
 , specific gravity of, 92-4 
 
 , testing by saturation equiva- 
 lent, 102 
 
 , viscosity of, 95, 230 
 
 Olea europssa oil, 40 
 
 Oleic acid, converting into palmitic, 
 266-72 
 
 in fats, 88-9 
 
 , soap from, 145, 224, 267 
 
 Olein from candle-works, 67, 145 
 
 Oleomargarin, 17 
 
 Olive-oU, 40-1 
 
 , extracting machinery, 
 
 48-55 
 
 Orange soap, 203 
 
 Organic impurities in soap, estima- 
 ting, 216 
 
 matters in fats, 84-5 
 
 Ozokerit, 251-2 
 
340 
 
 INDEX. 
 
 X alma-Chkisti oil, 44-6 
 Palm-kernel-oil, 36-40 
 
 nut-kemel-oil, 36-40 
 
 oil, 36-40 
 
 oil, 82-6 
 
 , basis for selling, 35 
 
 wax, 248 
 
 Palmitic acid, characters, 269 
 
 from oleic acid, 266-72 
 
 palm-oil, 261-3 
 
 Paraffin for candle-making, 250-1 
 
 , pressing, 244-8 
 
 , purifying, 248-50 
 
 scales, 244 
 
 Paraffins, 243-51 
 
 Paring-machine for oU-seed cakes, 
 
 55 
 Pasting hard soap, 167 
 Patents, summary of, 309-29 
 Pearlash, composition, 137 
 Pedesis, 209 
 Pentadeema fat, 65 
 Perfumes for soap, 198-9, 203 
 Petroleum-spirit for extracting oils, 
 
 39 
 Photometry, 287-98 
 Pickles for wicks, 277 
 Piling soap bars, 179 
 Pipes in ball soda making, 115 
 Plaited wicks, 275 
 Plotting soap, 200 
 Pomace, 39 
 
 Potash, caustic, 186-40 
 for solidifying fatty bodies, 
 
 267-72 
 
 in soap, estimating, 215 
 
 , sources, 136 
 
 Pot-ashes, 136 
 
 Potassium bichromate for bleaching 
 
 oUs, 79 
 
 bitartrate in soap, 143 
 
 carbonate, composition, 189 
 
 from camallite, 138 
 
 chloride from camallite, 188 
 
 palmitate, 269 
 
 , decomposing, 269-70 
 
 silicate, 140 
 
 Pouring wax candles, 278 
 Powdered caustic alkali, 144 
 Preparing caustic lye from soda 
 
 ash, 135 
 
 Press for oil-seed cakes, 53-4 
 
 Presses for soap, 182 
 
 Pressing paraffin, 244-8 
 
 Prime Butchers' Association tallow, 
 
 24 
 Primrose soap, 171, 189, 224, 225 
 Proctor and Eyland's bone-boiler, 29 
 Proximate analysis of fats, 82-105 
 Pumps for soap-works, 164-6 
 Pure oil soap, 145, 224, 267 
 Purifying fatty matters, patents, 809 
 
 glycerin, 297, 301, 303, 323 
 
 paraffin, 248-50 
 
 P.Y.O. tallow, 23 
 Pyrene oil, 37, 41 
 
 Q 
 
 UANTITT of alkali required to 
 saponify various fats, 6 
 
 ElA 
 
 ABAT oil, 59, 61 
 Eadisson's palmitic acid, 267-72 
 
 process for solidifying fats, 80, 
 
 267-72 
 
 — , advantages, 272 
 
 , cost, 271-2 
 
 EaUway-grease, 234-6 
 Ram-til oil, 61-2 
 Eancidity of oils, correcting, 76 
 Eape seed oil, 59 
 
 , extracting" machi- 
 nery, 48-55 
 Easping machine for coconut, 55 
 Eeactions in oausticizers, 124 
 Real value of soap, 212 
 Eecords in alkali making, 126 
 Recovering fat from suds, 828-4 
 
 sulphur from tank waste, 134 
 
 Eed mottled soap, 190-3 
 
 oil, soap from, 145, 224, 267 
 
 Eefining oils and fats, 70-81 
 Eelargage, 167 
 Removal of dirt, 207-14 
 Rendering fats, 16-22, 24-5, 26-30 
 
 in a soap-copper, 21 
 
 in presence of an acid, 
 
 20 
 
 under pressure, 18 
 
 Eesinous impurities in oils, remov- 
 ing, 75 
 Eicinus communis oil, 44-6 
 
INDEX. 
 
 341 
 
 Eiver Plate tallow, 23 
 EoIIb for oil-seed crushing, 50 
 Rose soap, 199, 203 
 Eosin, 66-7 
 
 , characters, 11 
 
 in oils, detecting, 103 
 
 oil in mineral oil, detecting, 
 
 231 
 Eowiness of soap, 174 
 Eun soap, 188 
 Eutsohman's plotting machine, 200 
 
 s 
 
 rjALAD oil, 41 
 
 Saline solutions, behaviour of soap 
 
 to, 13 
 Salt, definition of, 3-4 
 
 in soap boiling, 69 
 
 in soap, estimating, 216 
 
 cake, composition, 109 
 
 Saltpond palm-oil, 35 
 
 Salts, combining proportions of, 5 
 
 , miseellaneoua, mixed with 
 
 soaps, 142 
 - — of tartar in soap, 142 
 Sampling fats, 83 
 
 soap, 214 
 
 Sand soap, 195 
 Sapium sebiferum fat, 64 
 Sapo oarbonis detergens, 194 
 Saponifiable waste matters, 67-8 
 Saponification, 146 
 
 of a neutral fat, type of, 7 
 
 Saponifying tallow, 254 
 Saturation equivalent for testing 
 
 oils, 102 
 Scales of hydrometers, 132-3 
 Scouring-soap, 196-8, 315 
 Seed oils, extracting, 48-55 
 Seeding fat, 17 
 Separating glycerin from lye. 319- 
 
 22 
 
 soap from spent lye, 313 
 
 Separation of hard soap, 167 
 
 Sesame oil, 59-60 
 
 Sesamum oil, 69-60 
 
 Settling caustic lye, 125 
 
 Shea butter, 62-3 
 
 Ships' grease, 30 . 
 
 Short methods of soap analysis, 
 
 221-4 
 Silica in soap, estimatmg, 216 
 
 Silicated soap, 188-90 
 Skin grease, 31 
 
 Slicing-machine for coconut, 55 
 Snufless wicks, 277 
 Soap, action of, 207-14 
 
 , adulteration, 184-8, 212, 213 
 
 , almond, 198 
 
 , analyzing, 214-25 
 
 , , Leeds' scheme, 222-8 
 
 , short methods, 221-4 
 
 bars, 181 
 
 , piling, 179 
 
 , behaviourtosalinesolutionB,13 
 
 , blue mottled, 190-3, 224 
 
 boiling, water for, 68 
 
 , brown almond, 193 
 
 , Windsor, 198 
 
 , carbolic, 194 
 
 , case-hardening, 179 
 
 , Castile, 192 
 
 , cheapening, 316 
 
 , choice of fatty matters for, 14 
 
 , coal-tar, 194 
 
 , cold-water, 195, 224 
 
 , coloured, 202 
 
 , commerce in, 228 
 
 , consistency, 210 
 
 , cooling, 175-7 
 
 coppers, 155-7 
 
 , curb for, 166 
 
 , emptying, 174 
 
 , fan for, 158 
 
 , hat for, 156 
 
 cTUtching, 187 
 curd, 169, 224 
 cutting, 177-80 
 definition of, 3-4 
 detergent, 314 
 disinfectant, 194-5, 316 
 dry, 316 
 drying, 179 
 dyers', 197 
 elder-flower, 203 
 emollient, 314 
 estimating alkali in, 215 
 
 alkaline salts in, 216 
 
 carbolic acid in, 217 
 
 fatty acids in, 218-21 
 
 glycerin in, 217 
 
 hydrocarbon oils in, 218 
 
 ingredients insoluble in 
 
 water, 216 
 
342 
 
 INDEX. 
 
 Soap, eatimating unsaponified fat 
 
 in, 218 
 
 , value, 212 
 
 , water in, 214 
 
 , examining fatty acids in, 218- 
 
 21 
 
 , examples of composition, 224-5 
 
 , filling, 184-8 
 
 , fine toilet, 198-206 
 
 , floating, 316 
 
 frames, 175-7 
 
 , friotional, 316 
 
 from oleic acid, 145, 224, 267 
 
 red oil, 145, 224, 267 
 
 , fulling, 197, 315 
 
 , glycerin, 198, 203, 205-6 
 
 , grease-mottled, 224 
 
 , grey mottled, 190-3 
 
 , hard, 164-9 
 
 , and soft contrasted, 12 
 
 , water, 316 
 
 , history, 1-2 
 
 , home-made, 144 
 
 , honey, 193, 198, 203 
 
 , household, 144-73, 193-6, 314 
 
 , hydi'ated, 163-4 
 
 -^— industry, seat of, 227-8 
 
 , laimdry, 193-6 
 
 , lemon, 203 
 
 , liquid, 314 
 
 , London pale, 188 
 
 making, cold process, 151 
 
 , gauge tanks, 147 
 
 , heads, 146 
 
 on small scale, 144 
 
 , store-tanks, 147 
 
 , manufacturers', 196-8 
 
 - — -, brown oil, 224 
 
 , marine, 225 
 
 , Marseilles, 192 
 
 ^, marsh-mallow, 199 
 
 , mechanical apparatus for 
 
 making, 318 
 
 , millefleur, 203 
 
 , mineral oil, 317 
 
 mixers, 185 
 
 mixtures for cold process, 152 
 
 , mottled, 170, 190-B, 318 
 
 , naphthaline, 317 
 
 , neutral, 196-8, 206 
 
 , orange, 203 
 
 pan, 148 
 
 Soap, perfumes for, 198-9, 203 
 
 plotting, 200 
 
 , precipitation test for oils, 101 
 
 presses, 182 
 
 , primrose, 171, 189, 224, 225 
 
 pumps, 164-6 
 
 , pure oil, 145, 224, 267 
 
 , real value, 212 
 
 , red mottled, 190-8 
 
 , rendering, marketahle, 318 
 
 , rose, 199, 208 
 
 , rowiness, 174 
 
 , run, 188 
 
 , sample for analysis, 214 
 
 , sand, 195 
 
 , scouring, 196-8, 315 
 
 , separating from spent lye, 813 
 
 , shaving machine, 200 
 
 , silieated, 188-90 
 
 , soft, 155-63 
 
 solution for removing oil from 
 
 parafSn, 250 
 
 , stamping, 181 
 
 tablets, 182 
 
 " talking," 161 
 
 — — , textile, 162-8, 197, 315 
 
 , theoretical principles, 3-13 
 
 , theory of its action, 207-14 
 
 , thymol, 194 
 
 trade, 225-8 
 
 , transparent, 204 
 
 , treatment after removal from 
 
 the copper, 174-206 
 
 , violet, 203 
 
 , yellow, 171-3 
 
 , watering, 213 
 
 Soap-maker's object, 11 
 Soap-works, nuisances in, 226 
 Soaps boiled under pressure, 152 
 
 from fatty acids, 147 
 
 Soda in soap, estimating, 215 
 -^— soaps for manufacturers, 196-8 
 
 solutions, densities, 132 
 
 Sodium aluminate, 142 
 
 carbonate in soap, 187 
 
 silicate, 140 
 
 , composition, 141 
 
 in soap, 188, 216 
 
 sulphate in soap, 187, 216 
 
 Soft and hard soaps contrasted, 12 
 
 soaps, 155-63 
 
 , admixtures with, 162 
 
INDEX. 
 
 343 
 
 Soft soaps, chaxacteis, 161 
 
 , composition, 162 
 
 , coppers, 1 55-9 
 
 , mating, 159-61 
 
 Solidified glycerin, 205-6 
 Solidifying fatty bodies by caustic 
 
 potash, 267-72 
 
 liquid fats, 80, 267-72 
 
 point of fatty acids, 95-8 
 
 Soluble fatty acids in fats, 89-91 
 
 glass, 140 
 
 Specific gravity, 1 32 
 
 of oils, 92-4 
 
 Spent lye, composition, 298 
 
 , concentrating, 300 
 
 r, glycerin from, 81, 298- 
 
 301, 319-22 
 
 , separating soap from, 313 
 
 Spermaceti, 240-2 
 
 Stamping soap, 181 
 
 Standards for testing lye, ] 27-8 
 
 Starch in soap, estimating, 216 
 
 Stassfurt salts, 137 
 
 Steam for decomposing fats, 3] 1 
 
 -jacketed pan for rendering 
 
 tallow, 17 
 
 twirl, 150 
 
 Stearic acid by the Bock process, 
 
 263-6 
 Stearin candles, earliest, 253 
 
 , making, 253-72 
 
 Steatite in soap, estimating, 217 
 
 Stillingia fat, 64 
 
 Stone wax, 243 
 
 Store tanks foi soap-making, 147, 159 
 
 Storing caustic lye, 125 
 
 Strike in soap, 12 
 
 Stripping machine for soap, 200 
 
 Subsidence tanks for oils, 70 
 
 Suds, recovering fat from, 323-4 
 
 Suet, 15 
 
 Suifed til, 59 
 
 Suint for soap-making, 68 
 
 Sulphur, recovery from tank waste, 
 
 134 
 Sulphuric acid for purifying oils, 73 
 
 in soap, estimating, 216 
 
 Summary of patents, 309-29 
 Sunflower-seed-oil, extracting ma- 
 chinery, 48-55 
 Superheated steam, distilling fats 
 
 in, 80 
 
 Xable of alkalimetric degrees, 131 
 
 caustic potash, 140 
 
 densities of soda solu- 
 tions, 132 
 
 fatty acids in natural 
 
 fats, 8 
 
 freezing-points of gly- 
 cerin mixtures, 303 
 
 glycerin solutions, 305 
 
 iUuminants, 290 
 
 soda lye for hydrated 
 
 soap, 164 
 
 Tablets of soap, 182 
 
 Taking density by hydrometer, 132 
 
 Tallow, 15 
 
 candles compared with bou- 
 gies, 258 
 
 , decomposing by autoclave pro- 
 cess, 257 
 
 , distillation, 258-61 
 
 , foxy, 23 
 
 , leather, 31 
 
 , lime saponification, 254-6 
 
 , qualities, 22-4 
 
 , rendering, 15-22 
 
 , Eiver Plate, 23 
 
 , saponifying, 254 
 
 , separating into solid and 
 
 liquid constituents, 254 
 
 , vegetable, 64-5 
 
 Tank-liquors, causticizing, 122-7 
 
 '■ — , composition, 121 
 
 waste, 108, 133 
 
 , composition, 121 
 
 , disposal, 122 
 
 , recovering sulphur from, 
 
 134 
 
 Tanks for lixiviating black ash, 117 
 
 , gauge and store, 159 
 
 Testing causticity of lye, 130 
 
 lye, 127-33 
 
 Tetranthera fat, 65 
 
 Textile soap, 162-3, 197, 315 
 
 Thenard's process for purifying oils, 
 73 
 
 Theoretical principles of soap-mak- 
 ing, 3-13 
 
 Thymol soap, 194 
 
 Til oil, 59-60 
 
 Toilet soaps, 198-206 
 
 Total fatty acids in fats, 86-8 
 
344 
 
 INDEX. 
 
 Transparent soap, 204 
 Trimming candles, 282 
 Tiinnermann's soda table, 132 
 
 table of caustic potash, 140 
 
 Twaddell's hydrometer, 132 
 Twisted wicks, 274 
 
 U NSAPONIPIABLE olls In fats, 91-2 
 Unsaponified fat in soap, estimating, 
 217 
 
 fats, glycerin from, 301-2 
 
 Utilizing tank-waste, 133-5 
 
 V ALTIE of a soap-makiug materia], 
 
 68 
 of candles, illuminating, 287- 
 
 93 
 
 of soap, real, 212 
 
 Vegetable oils for soap-making, 
 
 32-67 
 
 tallow, 64-5 
 
 waxes, 243 
 
 Violet soap, 203 
 Virgin olive-oil, 40 
 Viscosity of oils, 95, 230 
 
 w. 
 
 ' AGGOK-grease, 234-6 
 Walbath, 240-2 
 Walls' press for paraffin, 245-8 
 Washing, water for, 210 
 Wash-waters of woollen factories, 67 
 Waste matters, saponifiable, 67-8 
 Water for soap-boilers, 68 
 
 washing, 210 
 
 , freezing out of glycerin, 303 
 
 glass, 140 
 
 Water, hardness, 210 
 
 in soap, estimating, 214 
 
 Watering soap, 213 
 Wax, andaquies, 243 
 
 candles, pouring, 278 
 
 , carnauba, 243 
 
 , Chinese, 242-3 
 
 . ohung peh-la, 242-3 
 
 ; Cuba, 243 
 
 , earth, 251-2 
 
 , Japan, 243 
 
 , ocuba, 243 
 
 , palm, 243 
 
 •, spermaceti, 240-2 
 
 , stone, 243 
 
 Waxes for candles, 238-48 
 
 , vegetable, 243 
 
 Wetzel evaporator, 296 
 Whitaker re-melter, 198 
 White kernel oil, 36 
 Wick-plaiting machine, 275 
 Wicks for candles, 273-7, 325 
 
 , pickles for, 277, 325 
 
 Windward palm-oil, 35 
 
 Wood potash, 137 
 
 Wool, soap for, 162-3 
 
 Woollen factories, wash-waters of, 67 
 
 Working black ash tanks, 119 
 
 Wright's neutral soap, 206 
 
 JLaen for wicks, 274 
 Yellow soap, 171-3 
 
 , fitting, 172 
 
 , liquidation, 172 
 
 z 
 
 iiNC for decomposing fats, 312 
 
 lOHPON : PltlKTED BY WILLIAM CLOWES AND SONS, UUHED, 
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 in a limp cover. We congratulate the author on the success of his laborious and practically 
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 sional person to -vyhom we nave shown it."— The Dublin Bui^er. 
 
 ■<■' ■ ..••■ ., i . . iX) ,™l 
 Tabulated Weights of Angle, Tee, Bulb, Round, 
 
 Squari,. and J'lat Iron -dnd Me^^ aifd Qther fnibrmaitiou" forlthe use of 
 Naval Architects and Shipbuilders. By C. H. Jordan, M.I.N.A. Fourth 
 edition, 32ino-,i cloth, 2^. 6<i.; rj^ ... ..•:\'-vi ■//•.| ,■- 
 
 Quantity Surveying. By J. Leaning. 
 
 trations, crown 8vo, cloth, gj."""™"*" 
 
 Contents : 
 
 With 42 illus- 
 
 A complete Explanation of the London 
 Practice. 
 
 General Instructions. 
 
 Order of Taking Off. 
 
 Modes of M easurement'.of the various Trades. 
 
 Use and Waste. 
 
 Ventilation and Warming, '- 
 
 Credits, with various Examples;of Treat.raent. 
 
 Abbreviations, , 
 
 Squaring the Dimensions ' ' 
 
 Abstracting, iyil:K Examples iri. illustration of 
 each Trade. 
 
 Billing. 
 
 Examples of Preambles to each Trade. 
 
 Forni for a Bill of Quantities. 
 
 Do Bill of Credits. ''■" ^ ' -^ ■^"' 
 
 Do. Bill for Alternative Estimate. 
 
 Restorations and Repairs, and Form of Bill. 
 
 Variation^ before Abceptaiice of Tendej;.^ - . 
 
 Errors in a Builder's Estimate. ' * '^■iJf 
 
 Schfiduie gf Prices. 
 
 Form of Schedule of Prices. 
 ' A<nalysis of Schediile of Prices; 
 
 Adjisstmeht of'Accounts. . 
 
 Formjof a i^jllJi^f^Yariatiqns., 
 
 Remarks dn^Specincatipn'^. 
 
 Prices' and '- Valuation f' of Work, with 
 , J :E^a;nple,s and Remarks upon each Trade. 
 
 Thje.Law 35 "it affects Quantity Surveyors, 
 with Law Reports. "^' 
 
 Taking Off after the Old Method. 
 
 Norther-n Practice.' 
 
 The G^ilei-al StatcitJent of the Methods 
 recommertded by the Manchester Society 
 of Architects for taking Quantities. 
 
 Exan^t^les of Collections. 
 
 ExamTi)IeS of " Taking Off" in each Trade. ■ 
 
 Remarks on the Past and Present Methods 
 
 A Practical Treatise on Heat, as applied to the 
 
 Useful Arts; for the Us^" of Engineers, Architects, &c. ' By Thomas 
 Box. With, l4>/af'i?J|.'^ Third edition^ dbwu 8Vb; clothf I2s.(>d. 
 
 A Descriptive ^Treatise on :;^athei^aticdl Drawing 
 
 Instruments: theii::const;ruc$ion, ,us,es, q,ualit^es,,,sdection,^ preservation, 
 and.swiggifstipnsfor improveraentgy, with hints uRon JJjawing, and Colour- 
 ing. Py W. F. STANLEY, M.R.I. Fifih edition, witt% nufnerpus. illustrations, 
 crosvn 8vo, cloth, 5j. - ^ . , , ■ ; i, 
 
PUBLISHED BY E. & F. N. SPON. 
 
 Spons Architects and Builders Pocket-Book; of Prices 
 
 and Stemor.anda. Edited by W. '^owng. Architect. Royal 32mo, roan, 
 4j/6</. ; pr elpth, , red edges, 3^.61^'. Published annually. Eleventh edition. 
 Now ready. 
 
 \ \ '^ 
 
 Long-Span Railway Bridges', comprising' Investiga- 
 tions of, the Comparative .Theoretical, and, Practical Advantages of the 
 various adopted or proposed'Type Systems of Constructio'n, with numerous 
 , Eormujae and /J^ablei giving the weight of , Iron or Steel required , in 
 ^ 'Bridges from' 300 feet' to the limiting Spans'; to which are added similar 
 Investigations and Tables Mating to Short-span Railway Bridges. 'Second 
 and revised edition. By B. Baker, Assoc. Inst. C.E. /&/«, crown 8vo, 
 cloth, Jj; - 
 
 Elementary Theory'^ and' Calctclaiion of Iton Bridges 
 
 and Roofs. By August RitteS., Ph.D., Professor at the Polytechnic 
 School at Aix-la-Chapelle. Trmslated from, the third, German edition, 
 by H. R. SaNKEY, Ca'pt. RlE. ''yViih.'jyo'illusiratioks, 8vo, cloth, 15J. 
 
 The Builder's Clerk : a: Guide to the Management 
 
 of a Builder's Business. By Thomas Bales. Fcap. 8vo, cloth, is. 6d. 
 
 The Elementary' Principles of Carpentry. By. 
 
 Thomas Tredgold. Revised .from Ithe original edition, and partly 
 , re^written, by John .,Tj^.omas, Hus^t. . C(intaiae;d. Ir 517 pages of letter- 
 ■' press, a.ni 'illustrated with 4.8 plates land ISO wood engravings. Third 
 edition, crown 8vo, cloth, i8j. ''■• \y ■' , . 
 
 Section I. On the Equality and i Distribution of Forces — Secttoa II. Resistance of 
 Titnbbr — Section III. Construction of Floors^ Section IV. Construction of Roofs — Sec- 
 tion V. Construction of 'Domes and Cupolas-— Section VI. Constcuction of Partitions — 
 Section VII. Scaffolds, Staging, and Gantries— Section VIII. Construction of Centres for 
 BridW.^Secticrn'l!!C.'. Coffer-dams, Shoring,, aad Strutting— Sejaon.j}C. Wvpiefi Bridges 
 and Viaducts — Section XI. Joints, Straps, and other Fastenings— Section XII." Timber. 
 
 ■■; H'^THOl 
 
 Our Factories, Workshops, 'and 'War&koUses : their 
 
 Sanitary and Fire-Resistiny; AuixigiiitieAis: By B. ft: Thwaite, Assoc. ^ 
 Mem. Inst. C.E. With 183 wmd engravings, ctoyin Svo, cloth, gj. 
 
 Gold : Its, Occurr,ence and'Extrsiction, embracing the 
 
 Geographical and Geological Distribution, and tte, Mineralogical Charac- 
 ters of Gold-bearing rocks ; the peculiar features and liiddes of -working 
 Shallow .placers, ;^^er§,..and Deep Leads ; Hydraulicipg ; the Reduction 
 and Separation of Auriferous Quartz ; ' the treatment of complex Auriferous 
 ores containing other metals ;' a/ Bibhography of the- subject and a GlosKary 
 of Technical and Foreign Terms. By Alfred G. LdcK, F.R.G.S. With 
 numerous illustrations and' map, IZ50 pp., super-royal 8vo, cloth, 
 il.izs. bd. "■ ' ' 
 
 E 2 
 
4 CATALOGUE OF SCIENTIFIC BOOKS 
 
 A Practical Treatise on Coal Mining. By George 
 
 G. Andr^, F.G.S., Assoc. Inst. C.E., Member of the Society of Engineers. 
 With %z lithographic plates. 2 vols., royal 410, cloth, 3/. I2j. 
 
 Iron Roofs : Examples of Design, Description. Illus- ■ 
 
 traied with 64 tVorking Drawings of Executed Roofs. By Arthur T. 
 Walmisley, Assoc. Mein. Inst. C.E. Imp. 4to, half-morocco, £,2 X2s. 6d. 
 
 A History of Electric Telegraphy, to the Year 1837. 
 
 Chiefly compiled from Original Sources, and hitherto .Unpublished, Docu- 
 ments, by J. J. Fahie, Mem. Soc. of Tel; Engineers, and of the Inter- 
 national Society of Electricians, Paris. Crown 8vo, cloth, gj. 
 
 Spans' Information for Colonial Engineers. Edited 
 
 by J. T. Hurst. , Demy 8vo, sewed. 
 
 No. I, Ceylon. By Abraham Deane, C.E. 2j. 6(/. 
 Contents : 
 
 .Introductory Remarks — Natural Productions — Architecture and Engineering — Topo- 
 graphy, Trade, and Natural History— Prihapal Stations — Weights and Measures, etc., etc 
 
 No. 2. Southern Africa, including the Cape Colony, Natal-, ' and the 
 Dutchi Republics. By. Henry Hall, F.R.G.S., F.R,C.I. With 
 Map. 3^. dd. 
 
 Contents: 
 
 General Description of South Africi— Physical Geography with reference to Engineering 
 Operations— Notes on Labour and Material in Cape Colony— Geological Notes on Rock 
 Formation in South Africa— Engineering Instruments for Use in South Africa— Principal 
 Public Works in Cape Colony: Railways, Mountain Roads and Passes, Harbour Works 
 Bridges, Gas Works, Irrigation and; Water Supply, iLighthouses, Drainage and -Sanitary 
 Engineermg, Public Buildings, Mines— Table of .Woods in South Africa— Animals used for 
 Draught Purposes^Statistical Notes— Table of Distances— Rates of Carriage, etc. 
 
 No. 3. India, By F. C. Danvers, Assoc. Inst C.E. With Map. 4j. dd. 
 
 Contents : 
 
 Physical Geography of India — Building Materials — Roads — Railways — Bridges — Irriga- 
 tion— River Works -i^ Harbour's— Lighthouse Buildings -^Native LaTibur — The'Prflicipal 
 Trees of India — Money— Weights and Measures— Glossary of Indian Terms, etc. 
 
 A Practical Treatise on Casting ana Founding, 
 
 including descriptions of the modern machinery employed in the art. > By- 
 N, E. Spretson, Engineer. Third edition, -with 82 ;/S&fef ' drawn to 
 scale, 412 pp., demy 8vo, cloth, 'i8j. 
 
 Steam Heating for Buildings; or. Hints to Steam 
 
 Fitters, being. I a description of Steam Heating Apparatus for Warming 
 and VentilalSng Private, Houses and Large BuilcJ^pgs, jvith remarks on 
 . Steam, Water, and Air in their relation to Heating, By. W. J. Baldwin. 
 With many illustrations. Fourth edition, crown 8vo, cloth, \os. 6d, 
 
PUBLISHED BY E. & F. N. SPON. 
 
 The Depreciation of Factories and their Valuation. 
 
 By EwiNG Matheson, M. Inst. C.E. 8vo, cloth, ds, 
 
 A Handbook of Electrical Testing. By H. R. Kempe, 
 
 M.S.T.E. Third edition, revised and enlarged, crown 8vo, cloth, 15^. 
 
 Gas fF(?r^.y : their Arrangement, Construction, Plant, 
 
 and Machinery. By F. CoLYER, M. Inst. C.E. With -^x folding plates, 
 8voj cloth, 24f. 
 
 The Clerk of Works: a Vade-Mecum for all engaged 
 
 in the Superintendence of Building Operations. By G. G. Hoskins, 
 F.R.I.B.A. Third edition, fcap. 8vo, cloth, \s. 6d. 
 
 American Foundry Practice: Treating of Loam, 
 
 Dry Sand, and Green Sand Moulding, and containing a Practical Treatise 
 upon the Management of Cupolas, and the Melting of Iron. By T. D, 
 ; ; West, Practiqal Iron Moulder iapd Foundry Foreman. Second edition, 
 ■with numerous illustrations, crown 8vo, cloth, \os. dd. 
 
 The Maintenance of Macadamised Roads. By T. 
 
 CoDRlNGTON, M.I.C.E, F.G.S., General Superintendent of County Roads 
 for South Wales. 8vo, cloth, bs. 
 
 Hydraulic Steam and Hand Power Lifting and 
 
 Prasing Machinery. By Frederick Colyer, M. Inst. C.E., M. Inst. M.E. 
 With Ti, plates, 8vo, cloth, i%s. 
 
 Pumps and Pumping Machinery. By F. Colyer, 
 
 M.I.C.E., M.I.M.E. With infolding plates, 8vo, cloth, 12s. dd. 
 
 The Municipal and Sanitary Engineers Handbook. 
 
 By H. Percy Boulnois, Mem. Inst. C.E., Bbrough Engineer, Ports- 
 mouth. With numerous illustrations, demy 8vo, cloth, izs. bd. 
 
 , ,iri> jj, ■-•/ ■,! , Contents: 
 
 The Appointment and Duties of the Toww Surveyor^Traffic-Macadamised Roadways- 
 Steam RollmB— Road Metal and Breakuig— Pitched Pavements— Asphalte— Wood Pavements 
 —FooWaths— Kerbs anfl Gutters— Street Naming and Numbenng-Strcet Lightmg— ?e«rer- 
 a„e— Ventilation of Sewers— Disposal of Sewage— House Drainage— Disinfection— Gas and 
 Water Comoanies, &c.. Breaking up Streets- Improvement of Private Streets— Borrowing 
 Powers— Artizans' and Labourers' Dwellings— Public Conveniences— Scavenging, including 
 Street Cleansing— Watering and the Removing of Snow- Planting Street Trees— Deposit of 
 Plans— Daneerous Buildings— Hoardings— Obstructions— Improving Street Lines— Cellar- 
 ODeninES— Public Pleasure Grounds-^Cemeleries— Mortuaries— Cattle and Ordinary Markets 
 
 Public Slaughter-houses, etc Giving numerous Forms of Notices, Specifications, and 
 
 General tiiformation upon these and other subjects of great importance to Municipal Engi- 
 neers and others engaged in Sanitary Work. 
 
CATALOGUE: OF SCIENTIFIC BOOKS 
 
 Tables of the Principal Speeds occurring in Mechanical 
 
 Engineering, expressed in metres in a second. By P. K^erayeff, Chief 
 Mechanic of, the Obouchoff Steel Works, St. Petersburg ; translated by 
 Sergius 'Kern, M.E. ; Fcap. 8vo, sewed, (>d. ■ \ jViC \'s.,\\\;'t\ 
 ... J J ,> I ij J" ,; I ...... . .' - , ■' ' ■ ■■ ■ '■ . ' 
 
 /4 Treatise on the Origin, Progress, Prevention, and 
 
 Cwe of Dry Rot in Timber; with TRemarks on the Means of Preserving 
 Wood from Destruction by Sea- Worms, Beetles, Ants, etc. By Thomas 
 Allen Britton, late Surveyor to the Metropolitan Board of Works, 
 etc., etc. With lo plates, crown 8vo, cloth, 1$. dd. 
 
 Metrical Tables. By G. L. Molesworth, M.I.C.E. 
 
 32mo, cloth, ys.dd.' 
 
 Contents., 
 
 Generals-Linear Measures — Square Measures — Cubic Measures — Measures of Capacity — 
 Weights — Combinations — ^I'hermometers. 
 
 Elements of Construction for Electro-Magnets. By 
 
 Count Th. Du Moncel, Mem. de I'lnstitut de France. Translated from 
 the French by C. J.-Whartqn. Crown -8vo, cloth, 4j. 6rf; _, . . 
 
 ' - .''. -.v.-. ' ■ ■ ■ ■ .1' ■■! , ; V,. ■■ .' '.'( 
 
 Electro- Telegraphy. By. Frederick S. Beechey, 
 
 Telegraph' Engineer. A Book for Beginners. Illustrated. Fcap. 8vo, 
 
 H andr ailing : by the Square Cut. By John Jones, 
 
 Staircase Builder. Part Second, with eight plates, 8vo, cloth, 3J-. td. 
 
 Practical Electrical Units Popularly Explained, With. 
 
 tfumerous illustrations and Remarks. By James Swinburne, late of 
 J. W. Swan and Co., Paris, Me of BrushTSwan Electric Light Company, 
 U.S.A., i8mo, ,clpth, is. 6d. 
 
 PhilippReis, Inventor of the Telephone: A Bidgraphical 
 
 Sketch. With Documentary Testimony, Translations of the "Original 
 Papers of the Inventor, &c. By Silvanus P. THOMPSON, B.A., Dr. Sc, 
 Professor of Experimental Physics in University College, Bristol. With 
 illustrations, 8vo, cloth, is. 6d. 
 
 A Treatise on the Use of Belting for the Transmis^ 
 
 sion of power. By J. H. CoopeR. Second &d\\\aa,illuitrated, 8vo, 
 cloth, 'i'ls. 
 
PUBLISHED 'BY E. ;& , F. N. SPON. 
 
 A Pocket-Book of Useful Fgrnivlc^ and. M^morand^ 
 
 for Civil an4- Mechanical jE^gineers. By puiLFQB.!? L. MoLESWORTH, 
 ,R([em. last.. C^E., Consulting , Engineer to the Government of India for 
 
 ■-,, .St?ite ,I<Lailw,ays. ,, Wil/p numerpiiis illustrations, 744 pp.,. Twenty-first 
 
 . , edition, rei^lsed and enlargedj 3?mo, rpan, 5j. 
 
 ; , . -,a ■\ SyNOPSI^,. OF CONTEMTSt 
 
 Siirvfeying, LeTel|ing, etc. — Strength and Weigit of Materials — Earthwork, Brickworlc, 
 M-isohry.ltebh^^/etc.-^StrutSj'Golamris, Beams, and Trusses — Flooring, Roofing, and Roof 
 Trusses-T-Girders,<Bridgft';, etai — Railways and Roads — Hydraulic Formulae— Canals. Sewers, 
 Water wgrksp DocEsiTjlrrigf flbnj .and Breakwaters— Gas, Ventilation, and Warming— Heat, 
 Light, raloftrV'and Strund'ij-Qraj.rity: Centre's, Forces, and Powers— MillWork, Teeth of 
 Wheels, Shafting, etc. — Workshop' Recipes — Sundry Machinery — Animal Power — Steam and 
 Uje Ste^iii' _^ngin^^ Water-power,. Water^hcels^ Turbines, 1 etc. — Wind and Windmills — 
 Steam -Navigation,' Snip Building, Tonnage, etc.— Gunnery, Projectiles, etc. — ^Weights, 
 Measure, .and i^IqnpyrT-JPrigonoin^try, Cpnic Sections, and Curves — Telegraphy— Mensura- 
 tion— Tables of Areas and Circumference, and Arcs of Circles — Logarithms, Square and 
 Cubp Ropts, Ppwers— ^Reciprocals, etc. — Useful Numbers — Differential and Integral Calcu- 
 lus — Algebraic Signs— Telegraphic Construction and Formulae. 
 
 ■'•■-■ ■■■',. ;j..v ■ ■■' ■ 
 
 Spons Tables and ' Memoranda for Engineers ; 
 
 ^el^cted and arranged "by J. T. HiiS.ST, C.E., Author of ' Arcliitectural 
 Suiry^eyors' Handbook,' ' Hiirst's' Tredgold's Carpentry,' etc. Seventh 
 (, , edition, '64mOi!roan, gilt edges, is. ; or in cloth case,., is. (id. 
 
 'JTfeis Work is'pr^nted in a pearl typfe,'and is so small, measuring only 24 in. by if in. by 
 i ill.' tliick, that'^t may be easily carried iii the waistcoat pocket. 
 
 _«./,.*.It_is certainly an extremely rare thing for a reviewer to be called upon to notiqe a volume 
 n3;ea;S|EEii;ig,.but z^ in. by rf . in., yet tlje.se dimensions faithfully represent the size of the handy 
 iuHtJ^jpopiJc before usf,^, The volumeTr-which contains 118 printed pa^s, besides a few blank 
 pag^-/p^-memorandai — is, in fact, a. true pocket-book, adapted for being carried in the waist- 
 coat pocket, and containing a. far; greater amount and variety of inforniatiqu.than most people 
 
 wouja imagine could be, compressed into io small a space The little volume has been 
 
 "Gotnpiled with CQiisTdera'ble care aa^^t- judgment, and we can cordially recommend it to our 
 readers as a useful little pocket compariibp." — E?tgi?ieering. 
 
 A Practical Treatise on Natural and Artificial 
 
 Concrete, its, Vfirietif^ find Constructive Adaptations. By Henry Reid, 
 Author of fhgf Sci(eijp,e and,Art of thp Manufacture of Portland Cement.' 
 ^ New Edition, with, ^<) xi^ppdcutsfind ^i plates, 8vo, cloth, 15J. 
 
 Hydrodynamics : Treatise relative to the Testing of 
 
 •| . . Water-Wheds: and -Machinery, with varlojus other matters pertaining to 
 Hyd'rddynami,cs.- By James EmerSCin', ' IVilh numerous illustrations, 
 360 PJ3, Third edition, crown 8vo, cloth, 4J. 6rf. 
 
 Electricity as li Motive Power. By Coufit Tfi. Du 
 
 "■"'"MoNCTL,vK[fembre.de I'ihstitutde France, and Frank Geralby, Inge- 
 nieur'des;Pon.ts.el5Chaussee,s. ' Translatedand.Eriited.w'ith Additions, by 
 C. J. Wharton, Assoc. Soc. TeL Eng. and Elec. . With 113 engravings 
 », -|.#»5.(6'fl8^^a»iy,' crown 8vo, cloth, 7s. ^f^..^. - 
 
 Hint} on Architectural Draughtsmanship. By G. W. 
 
 TuxFORD Hallatt. Fcap. 8vo, cloth, is. 6d. 
 
Hops 
 
 8 CATALOGUE- OF SCIENTIFIC BOOKS 
 
 Treatise on Valve^Gears, with special consideration 
 
 of the Link-Motions of Locomotive Engines. By Dr. Gustav Zeuner, 
 Professor of Applied Mechanics at the Confederated Polytechnikum of 
 Zurich. Translated from the Fourth German Edition, by Professor J. F. 
 Klein, Lehigh University, Bethlehem, Pa. Illustrated, 8vo, cloth, izj. dd. 
 
 The French- Polishers Manual. By a French- 
 
 Polisher; containing Timber Staining, Washing, Matching, Improving, 
 Painting, Imitations, Diirections for Staining, Sizing, Embodying, 
 Smoothing, Spirit Varnishitig, French-Polishing, Directions for Re- 
 polishing. Third edition, royal 32mo, ^ewed, dd, , 
 
 Tops, their Cultivation, Commerce, and Uses in 
 
 various Countries. By T. L. SiMMONDS. Crown 8vo, cloth, 4j. 61/. 
 
 A Practical Treatise on the Manufacture and Distri- 
 bution of Coal Gas. By William Richards. ' Demy 4to, vpith numerous 
 wood engravings and 29 plates, cloth, 28J. 
 
 Synopsis of Contents : 
 
 Introduction — History of Gas Lighting — Chemistry of Gas Manufacture, by Lewis 
 Thompson, Esq., M.R.C.S. — Coal, with Analyses, by J. Paterson, Lewis' Thompson, and 
 G. R. Hislop, EsCirs.^-Retortsi ' Iron and Clay — Retort Setting — Hydraulic ' Main-^-Con- 
 densers-^ Exhausters — Washer? and Scrubbers — Purifiers — Purification — History of Gas 
 Holder — Tanks, Brick and .Stone, Composite, Concrete, Cast-iron, Compound Annular 
 Wrought-iron — Specifications — ^ Gas Holders — Station Meter — Govertior — Distribution — 
 Mains — Gas Mathematics, or Formulas forthe Distribution of Gas; by Lewis Thompson, Esq. — 
 Services — Consumers' Meters — Regulators — Burners — Fittings — Photometer — Carburization 
 of Gas — ^Air Gas and Water Gas — Composition of Coal Gasi' by Lewis Thompson, Esq. — 
 Analyses of Gas--^Influence of Atmospheric Pressure and Temperature on Gas — Residual 
 Products— Appehdix^-Description of Retort Settings, Buildings, etc., etc. 
 
 Practical Geometry, Perspective, and Engineering 
 
 Drawing; a Course of IJescriptive Geometry adapted to the Require- 
 ments of the Engineering Draughtsman, including the determination' of 
 cast shadows and Isometric Projection, each chapter being followed by 
 numerous examples ; to which are added rules for Shading, Shade-lining, 
 etc., together with practical instructions as to the Lining, Colouring, 
 Printing, and general treatment of Engineering Drawings, with a chapter 
 on drawirig Instruments. By George S. Clarke, Capt. R.E. Second 
 edition, 2«2VA 21 /toifj. , 2 vols., cloth, loj. 6(/. ■, vr ■ 
 
 The Elements of Graphic Statics. By Professor 
 
 Karl Von Ott, translated from the German by G. S. Clarke, Capt. 
 R.E., Instructor in Mechanical Drawing, Royal Indian Engineering 
 College. Witk 93 illustrations, crown Svo, cloth, 5j. 
 
 The Principles of Graphic Statics. By George 
 
 Sydenham Clarke, Capt. Royal Engineers. With 112 illustrations. 
 4to, cloth, I2S. 6d.. 
 
 Dynamo-Electric Machinery : A Manual for Students 
 
 of Electro-technics. By Silvanus P. Thompson, B.A., D.Sc, Professor 
 of Experimental Physics in University College, Bristol, etc., etc. Second 
 edition, illustrated, SvO, cloth, 12s. 6d. 
 
PUBLISHED BY E. & F. N. SPON. 
 
 The New Formula for Mean Velocity of Discharge 
 
 ,, (^Rivers and Canals. By W. R. Kutter. Translated from articles in 
 "'Uie' 'Cultur-Ingenieur,' by Lpwis D'A. Jackson, Assoc. Inst. C.E. 
 8vo, cloth, I2s. 6d. 
 
 Pradtical Hydraulics ; a Series of Rules and Tables 
 
 ■ for the use of Engineers, etc., etc. By Thomas Box. Fifth edition, 
 numerous plates, post 8Vo, cloth, ^s. 
 
 A Practical Treatise on the Construction of Hori- 
 zontal and Vertical Waterwheels, specially designed for the use of opera- 
 tive mechanics. By William CULLEN, Millwright and Engineer. With 
 
 " , t r plates. Second edition, revised and enlarged, small 4to, cloth, lar. bd. 
 
 Tin: Describing the Chief Methods of Mining, 
 
 - Dressing and Smelting it abroad ; vf ith Notes upon Arsenic, Bismuth and 
 Wolfram. By Arthur G. Charleton, Mem. American Inst, of 
 Mining Engineers. With plates, 8vo, cloth, \2s. dd. 
 
 Perspective, Explained and Illustrated. By G. S. 
 
 Clarke, Capt. R.E. With illustrations, 8vo, cloth, y. 6d. 
 
 The Essential Elements of Practical Mechanics; 
 
 based on the Principle of Work, designed for Engineering Students. By 
 
 - Oliver Byrne, formerly Professor of Mathematics, College for Civil 
 Engineers. Third edition, with 148 wood engravings, post 8vo, cloth, 
 
 •IS, dd. 
 
 Contents : 
 
 "Chap I How Work is Measured by a Unit, both with and without reference to a Unit 
 of Time^Chap. 2. The Work of Living Agents, the Influence of Friction, and inttoduces 
 one of the most beautiful Laws of Motion— Chap. 3. Thepnnciries expounded in the first anJ 
 second chapters are applied to the Motion of Bodies— Chap. 4. The Transmission of Work by 
 simple MaiSiines^^Chap. %. Useful Propositions and Rules. 
 
 The Practical Millwright and Engineers Ready 
 
 Reckoner; or Tables for finding the diameter and power of cog-wheels, 
 diameter, weight, and power of shafts, diameter and strength of bolts, etc. 
 By Thomas Dixon. Fourth edition, i2mo,, cloth, y. 
 
 Breweries and Mailings : their Arrangement, Con- 
 struction, Machinery, and Plant. By G. Scamell, F.R.I.B.A. Second 
 edition, revised, enlarged, and partly rewritten. By F. Colyer, M.I.C.E., 
 M.I.M.E. With 20 plates, 8vo, cloth, i&f. 
 
 A Practical Treatise on the Manufacture of Starch, 
 
 Glucose, Starch-Sugar, and Dextrine, based on the German of L. Von 
 Wagner Professor in the Royal Technical School, Buda Pesth, and 
 other authorities. By Julius Frankel ; edited by Robert Hutter, 
 proprietor of the Philadelphia Starch Works. With 58 illustrations, 
 344 pp., 8vo, cloth, i&r. ^ ^ 
 
,;o CATALOGUE OF SCIENTIFIC BOOKS 
 
 A Practical Treatise on Mill-gearing, Wheels, Shafts, 
 
 Riggers,- etc.; for the use of Engineers. By Thomas Box. Third 
 edition, with 1 1 plaies. Crown 8vo, cloth,' 7j. bd. 
 
 Mining Mack;inery: a Descriptive Treatise on thfe 
 
 Machinery, Tools, and. other Appliances used in , Mining. By G. G. 
 Andre, F.G.S., Assoc, tnst. CE.., Mem. of the Society of Engineers. 
 Royal 4to, uniform with the Author's Treatise on Coal Mining, con- 
 taining 182 plates, accurately drawn to scalCj with descriptive text, in 
 
 ■ 2 vols., tloth, 3/. i2j. 
 
 Contents':"' ' 
 
 Machinery for Prospecting,-Excavating, Hauling, and Hoisting — 'Ventilation — Pumping — 
 Treatment of Mineral' Products, '^including Gold and^ Silver, Copper, Till, and Lead,' Iron 
 Coal, Sulphur, China Clay, Brick Earth, etc.. 
 
 Tables for Setting out Curves for Railways, Canals, 
 
 • Roads, etc., 'varying from a radiuS of five chains to three miles. By A. 
 Kennedy and R. W. Hackwood.- Illustrated, 32mo, cloth, 2s. 6d. 
 
 The Science dnd Art of the Manufacture of Portland 
 
 Cement, with observation's' on some of its cbnstnictive applications. With 
 66 illustrations. By Henry Reid, C.E., Author of 'A Practical 
 Treatise on Concrete,' etc., etc. 8vo, cloth, \%s, 
 
 Thi' Draughtsman s Handbook of Plan and Map 
 
 Drawing; including instructions for the preparation of Engineering, 
 Architectural, and Mechanical Drawing^. With numerous illustrations 
 in the text, and 33 plates (15 printed in colours). ■ ByQ. 'G. Andre, 
 F.G.S., Asspc.| Inst. C.E. 4tq, cloth, ^s, ' , ' ' 
 
 ' Contents: 
 
 ■ 'The Drawing Office and its Furnishings-^GepnietriGal Problems — ^Lines, Dots, and their: 
 Combinations — ^Colours', Shading, Lettering, Bordering, and North Points — Scales — Plotting 
 — Civil Engineers' and • Surveyors'- P^laps — Map DrawingrTMechanic^'.and- Architectiir^Ll 
 DSrawirig-^Copyirig and' Reducing Tngbnometrical' Formulae, etc., etc. ■ ^ '' ■ ^ 
 
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 comprising a series of origirial and carefiilly calculated tables, of the 
 utmost utility to persons interested in the iron trades. By James Foden, 
 
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 Painting and Painters Manual: a Book of Facts 
 
 for Painters and those who Use or Deal in Pairit Materials. By C. L. 
 CONDIT and J. ScHELLER. Illustrated, 8vo, cloth, \os. kd. 
 
PUBLISHED BY E.'& F. N. SPON. 
 
 A Treatise on Rbpemaking.as practised in public and 
 
 private Sdpe-ydrdsi with a Description of the Manufacture, Rules, Tables 
 of Weights, etCi, adapted to the Trade, Shippiiigj Mining, Railways, 
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 'Sanitary Engineering^: a Guide to the Construction 
 
 of Works of Seivelrage and Hotise Draiiiage, with Tables for facilitating 
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 'Screm Cutting Torbles for \ Engineers and Machinists, 
 
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 Threads, of Screws of any required pitch, with a Table for making the 
 
 Universal Gas-pipe Threads and Taps. By W. A. Martin, Engineer. 
 
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 using Public. By Maurice John Sexton. Second edition, royal 
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 . ■ r " " ' 
 
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 of Ores by means of Electiipity. By Hippolyte ' Fontaine, translati^ 
 from the French by; J. A. Berly, CE,, Assoc. S.T.E. With engravings. 
 8vo, cloth, gj. ,, , 
 
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 ■m'-ilCa. Essays on the Principles involved in Desigii and Constmclioh. -By 
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 Barlow's Tables of Squares, Cubes, Square Roots, 
 
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 Camus (M.) Treatise on the Teeth of Wheels, demon- 
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PUBLISHED BY E. & F. N. SPON. 13 
 
 A Practical Treatise on the Science of Land and 
 
 Engineering Surveying, Levelling, Estimating Quantities, etc., with a 
 general description of the .several Instruments Teqrared, for Surveying, 
 , -Levelling, Plotting, etc. By H. S. Me?.rett. Fourth edition, revis.ed 
 by G. W. UsiLL, Assoc Mem. Inst. C.E. ^\ plates, with illustrutioHs 
 and tables, royal 8vo, doth, 12s. dd. 
 
 ' .J ,, , Principal Contents : ' 
 
 ^ Part "i. Introduction and the Pririciples.of Geometry. Part 2. Laiid Surveying: com- 
 
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 Levelling with a Theodolite — Gradients — ^Wooden Curves — To Lay out 'a Railway Curve- 
 Setting out Widths. Part 4. Calculating QuaiWities generally for Estimates— Cuttings and 
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 . and Use of Instilments in Surveying and Plotting— The Improved Dumpy Level — Troughton's 
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 for, Setting out Curves, and for .various Calculations, etc., etc., etc. 
 
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 ■The Steam Engine considered as a Heat Engine: a 
 
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14 CATALOGUE OF SCIENTIFIC BOOKS. 
 
 Electricity: its Theory, Sources, and Ap lications. 
 
 By J. T. Sprague, M.S.T.E. Second edition, revised and enlarged, with 
 numerous illustrations, cico^n ?,\o, cloth, 15^. 
 
 The Practice of Hand Turning in Wood, Ivory.i Shell, 
 
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 in the Practice of Turning, in T^ood, Ivory,, etc. ; also an Appendix on 
 Ornamental Tviming, (A book for begiriiiers.) By FRANCIS Campin. 
 Third edition, with wood engravings, crown 8v6, cloth, ,6j. 
 Contents : 
 
 On Lathesr-Turning Tools — Turning Wood-^Drilling-r-Scfew ^Cuttihgr-Miscellaneous 
 Apparatus and Processes — ^Turning Particular Forms — Staining — ^Polishing — Spinning Metals 
 —Materials — Ornamental Turning, etc. , , ' 
 
 Health and Comfort in House Building,, or Ventila- 
 tion with Warm Air by Self- Acting Suction Power, with Review of the 
 mode of Calculaiting the Draught fc Hot- Air Flues, and "with some actual 
 Experiments. By J. Drysdale, M!;D., and J. W. Hayward, M.D. 
 Second edition, with Supplement, to«A5 ^/ato, demy 8vo, cloth, ']s.6d. 
 
 Treatise on Watchwork, Past and Present., By the 
 
 Rev. H. 'l. NEtTHROPP, M.A., F.S.A; ■With^zillustreitions, crown 
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 Notes in Mechanical Ekgineering. Compiled prin- 
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 Memi Inst; C.E., Mem. Soc. of Engineers. Crown avo, cloth, 2j. bd. 
 
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 .'i ■• . ■ ■ . , - \CONTENTS: 
 
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 §ppns" Dictionary of Engineering, Civil, Mechanical, 
 
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PUBLISHED BY E. & F. N; SPON. 15 
 
 Cfi^oe and Boat Building: a. complete Manual for 
 
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 Proceedings of the National Conference of Electricians, 
 
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 Dyndmo - Electricity, ' its Generation, Application, 
 
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 Domestic Electricity for Amateurs. Translated from 
 
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 Manual for Gas Ewgineering Students. By D. Lee.' 
 
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PUBLISHED BY E. & F. N. SPON. 17 
 
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 Steam. Making, or Boiler Practice. By Charles A. 
 
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 Locomotive and Marine.iBoilers — 6. Design, Construction^ apd Strength of Boilers— 7. Pro- 
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 .?Enittedh , Fabrics — 
 Hosiery, 15 pp. 13 figs. 
 
 Lace, 13 pp. 9 figs. 
 
 Leather, 28 pp. 3 1 figs. ' 
 
 Linen Manufactures, 16 
 pp. a figs. , 
 
 Manures, 2i pp, 30 figs. 
 
 Matches, 1 7 pp. 38 figSi 
 
 MbrdantSinl3 pp. 
 
 Narcotics, 47 pp. :, i 
 
 Nuts, 10 pp. 
 
 Oils and Fatty Sub- 
 
 :-■ 'stances! 125 pp. ' ■ ■' 
 
 Paint. 
 
 Paper, 26; pp. 23 figsi 
 
 Paraffin, 8 pp. 6 figSi 
 
 Pearl and Coral, 8 pp. 
 
 Perfumes,- 10 pp.- 
 
 Photography, 13: pp. 20 
 
 figs. 
 Pigments, 9 pp. 6 figs. 
 Pottery, 46 pp. 57 figs. 
 Printing and Engraving, 
 .,.?o.pp, 8 figs. 
 Rags. .„.,,, 
 
 Resinous and.-j • Guipmy 
 - Substances, 75, pp. 16 
 
 figs. 
 Rope, 16 pp. 17 figs. 
 Salt, 31 pp. 23 figs. , 
 Silk, 8 pp. , , . : 
 
 Silk Manufactures, 9 pp. 
 
 II figs. 
 Skins^ 5 pp. 
 Small Wares, 4 pp. > 
 Soap, and Glycerine, 39 
 
 pp. 45 figs. 
 Spices, 16 pp. 
 Sponge, 5 pp. 
 Starch, 9 pp. 10 figs. 
 Sugar, ISS pp. 134 
 
 figs. 
 Sulphur. , 
 Tannin, 1 8 pp. 
 Tea. 12 pp. 
 Timber, 13 pp. 
 Varnish, 15 pp. 
 Vinegar, 5 pp. '-. 
 Wax, 5 pp. ' •' 
 Wool, 2 pp. 
 Woollen Manufactures, 
 
 58 pp.39 figs.-- 
 
 London i E. & F. 
 aiew. York : 
 
 N. SPON, 15J5, Strand. 
 
 .35, Miurray Street. 
 
Crown 8vo, clotli, with Ulustratiohs^Sj. 
 
 WORKSHOP RECEIPTS, 
 
 FIRST SERIES. 
 
 By ERNEST SPON. 
 
 Bookbinding. 
 
 Bronzes and Bronzing. 
 
 Candles. 
 
 Cement. 
 
 Cleaning. 
 
 Colourwashing. 
 
 Concretes. 
 
 Dipping Acids. 
 
 Drawing Office Details. 
 
 Drying Oils. 
 
 Dynamite. • 
 
 Electro - Metallurgy — 
 (Cleaning, Dipping, 
 Scratch-brushing, Bat- 
 teries, Baths, and 
 Deposits of every 
 ' deseripfion); 
 
 Enamels. 
 
 Engraving on Wood, 
 Coppet, Gold, Silver, 
 Steel,' and Stone. 
 
 Etching and Aqua Tint. 
 
 Firework Making '^- 
 (Rockets, Stars, Rains, 
 Gerbes, Jets, Tour- 
 
 , billons. Candles, Fires, 
 LanceSjLights, Wheels, 
 Fire-balloons, and 
 minor Fireworksji 
 
 Fluxes. - 
 
 Foundry Mixtures. 
 
 Synopsis of Contents. 
 
 Freezing. . . 
 
 Fulminates. ' '' 
 
 Furniture Creams, Oils, 
 Polishes, Lacquers^ 
 and PasteSi 
 
 Gilding. ' - 
 
 Glass Cutting, Cleaning, 
 Firostingj Drilling, 
 Darkening, Bendingi 
 Staining, and Paiiit- 
 ing. ■ ■ - -' '; 
 
 Glass Making. 
 
 Glues. : ' 
 
 Gold. ' , ' , >--! 
 
 Gi-ainiag. : . in ' 
 
 Gums. " ' 
 
 Gun Cotton. ■ 
 
 Gunpowder. 
 
 Horn Working. 
 
 Indiarubber. 
 
 Japans, Japanning, and 
 kindred processes. 
 
 Lacquers. 
 
 Lathing. 
 
 Lubricants. 
 
 Marble Working. 
 
 Matches. 
 
 Mortars. ; ; ' 
 
 Nitro-GIycerine, ■ ' ' 
 
 Oils. 
 
 Paper. 
 
 Paper Hanging. 
 
 Painting in Oils, in Water 
 Colours, as well as 
 ' FiJesco,' House, Trans- 
 parency, ■ Sign, and 
 ■ Carriage Painting. 
 
 Photography. 
 
 Plastering. 
 
 Polishes. 
 
 Pottery — (Clays, Bodies, 
 
 . t Glazesj Crflonrs, Oils, 
 Stains, Fluxes, Enar 
 mels, and Lustres). 
 
 Scouringi ' 
 
 Silveribg. 
 
 Soap. ' 
 
 Solders. 
 
 Tanning. 
 
 Taxidermy. 
 
 Tempering Metals. 
 
 Treating Horn, Mother- 
 o'-Pearl, and like sub- 
 stances. 
 
 Varnishes,.' Manufacture 
 and Use of. 
 
 Veneering. - 
 
 Washing; ; ■ 
 
 Waterproofing. 
 
 Welding. 
 
 Besides Receipts relating to the lesser Technological matters and processes, 
 such as the manufacture a.nd use of Stencil Plates, Blacking, Crayons, Paste, 
 Putty, Wax, Size; Alloys, Catgut, Tunbridge Ware, , Picture Frame and 
 Architectural Moiildings, Compos, Cameos, and others too numerous to 
 ihention. .i:,[ 7, 
 
 London : E. & F. N. SPON, 135, Strand. 
 
 New York: 35, Murray Street. 
 
Crown 8vo, cloth, 485 pages, with illustrations, Jj. 
 
 WORKSHOP RECEIPTS, 
 
 SECOND SERIES. 
 
 By ROBERT HALDANE. 
 
 Synopsis of Contents. 
 
 Acidimetry and Alkali- 
 metry. 
 Albumen. 
 Alcohol. 
 Alkaloids. 
 Baking-powders. 
 Bitters. 
 
 Bleaching , i /i 
 
 Boiler Incrusta.tions. ; , , . ; 
 Cements and Lutes. 
 Cleansing. 
 Confectionery. 
 Copying. 
 
 Disinfectants. 
 Dyeing, Staining, and 
 , Colouring. 
 Essences. 
 Extracts. 
 Fireproofingj . 
 Gelatine, Glue, and Size. 
 Glycerine. 
 Gut. 
 
 Hydrogen peroxide. 
 Ink. 
 
 Ifldine. - 
 Iodoform. 
 
 Isinglass. 
 
 Ivory substitutes. 
 
 Le^tjier^ 
 
 Luminous bodies. 
 
 Magnesia. 
 
 Matches. 
 
 Paper. 
 
 Parchment. 
 
 Perchloric aci^. 
 
 Potassium oxalate. 
 
 Preserving. 
 
 Pigments, Paint, and Painting : embracing the preparation of 
 Pigments, including!, alumina lakes, blacks (animal, bone, Frankfort, ivory, 
 lamp, sight, soot), blues (antimony, Antwerp, cobalt, cceruleum, Egyptian, 
 manganate, Paris, Peligot, Prussian, smalt, ultramarine), browns (bistre, 
 hinau, sepia, sienna, umber, Vandyke), greens (baryta, Brighton, Brunswick, 
 chrome, cobalt, Douglas, emerald, manganese, mitis, mountain, Prussian, 
 sap, Scheele's, Schweinfurth, titanium, verdigris, zinc), reds (Brazilwood lake, 
 carminated lake,' carinine, Cassius purple, cobalt pink, cochineal lake, cblco- 
 thar, Indian red, madder lake, red chalk, red lead, vermilion), whites (alum, 
 baryta, Chinese, , lead sulphate, white ,J,^ad— by, American, Dutch, French, 
 German, Kremnitz, and Pattinson processes, precautions in making, and 
 composition of commercial samples — whiting, Wilkinson's white, zinc White), 
 yellows (chrome, , gamboge, Naples, orpiment, realgar, yellow lakes) ; Paint 
 (vehicles, testing oils, (driers, grinding, storing, applying, priming, drying, 
 filling, coats, brushes, surface, water-colours;' removing smell, discoloration; 
 miscellaneous paints— cement paint for carton-pierre, copper paint, gold paint, 
 iron paint, hme paints, silicated paints, steatite, paint, transparent paints, 
 tungsten paints, window paint, zinc paints) ; Painting (general instructions, 
 proportions of ingredients, measuring paint work -''carriage painting — priming 
 paint, best putty, finishing colour, cause of cracking, mixing the paints, oils, 
 driers, and colours, varnishing, importance of washing vehicles, re-varnishing, 
 how to dry paint ; woodwork painting). 
 
 London : B. & F, 
 
 KTew York : 
 
 N. SPON", 125, Strand. 
 
 35, Hurray Street. 
 
aXrST PXJJ3LISHED. 
 
 . ": ■:. I ■! JHlTTOTf a yi H O " ' 
 
 Crown 8vo, cloth, 480 pages, with 183 illustrations, Sj. 
 
 WO R K;S flQjP, R j;g EI PT S, 
 
 THIRD SERIES. 
 By c. g. warnford; lock. 
 
 tTniforiii with the First' aiid ^e«pnd Series. •", 
 
 ,,..,.■ [ 
 
 Synopsis oe-' Cowtents. 
 
 ^^dI-'jI :■■■: 
 
 Alloys. .:;..... -Mi -u."! 
 
 Indium. ■ ■ ' ■* 
 
 Rubidium. •j,.i.'-.-. 
 
 Aluminiuni. ■ "" ' ',;. 
 Antimony. _, ,,, ,,■ 
 
 Iridium.- ",' 
 i Iron and Steel. -i.,i 
 
 Ruthenium. 
 Selenium. ,-, .1 n'r. 
 
 Barium. 
 
 ] Lacque'rs and Lacqueribgi. 
 
 Silver. -V -''•' '■ 
 
 Beryllium. 
 
 Lanthanum. ' '^' 
 
 Slag. •- ■ 
 
 Bismuth. 
 
 Lead. -;*(, 
 
 Sodium. 
 
 Cadmium. 
 
 Lithium. 
 
 Strontium. 
 
 Caesium, 
 
 Lubricants. ' ' 
 
 Tantalum. 
 
 Calcium. , 
 
 Magnesium. 
 
 Terbium. 
 
 Cerium. 
 
 Manganese. 
 
 Thallium. 
 
 Chromium. 
 
 Mercury. , 
 
 Tl^cirium. i 
 
 Cobalt. - 
 
 Mica.' .•'■''' , •. ' ' ! 
 
 Tin. 
 
 Copper. 
 
 Molybd&iunl'. ' 
 
 titanium. 
 
 Didymium. 
 
 Nickel.' ','''.': 
 
 Tungsten. 
 
 Electrics. 
 
 Niobium. 
 
 Uranium. 
 
 Enameiis and Glazes. 
 
 Osmium.,, 
 
 yanadium. 
 
 Erbium. . 1 . 
 
 Ealladium.-i "'i , ; 1 
 
 Yttrium. 
 
 Gallium. 
 
 ■Platinuni.;, "■■'■'• ' ■"\"' _ 
 
 Zilld. ' 
 
 Glass. 
 
 .Potassium. , . ,,, 1, 
 
 rZkcwium-. 
 
 Gold. 
 
 Rhodium. - ' • ; 
 
 rut' - -.1- ^ :_.[ :;'. ■ 
 
 New York : 35 Murray Street. 
 
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