[CHURCHILL'S TECHNOLOGICAL HANDBOOKS.] SOAPS AND CANDLES. EDITED BY JAMES CAMEEON, F.I.C. ANALYST Ilf THE LABOBATOKY, SOMERSET HOUSE. LONDON: J. & A. CHUECHILL, 11 NEW BURLINGTON STREET 1888. -T o Zo P1IEFAGE. As in the preceding Handbooks of this series, the articles in COOLEY'S " Cyclopedia " have been added to from various scattered sources, so as to present, ill as small a compass as possible, information which, it is hoped, may be found useful to technological students and others interested in the industries described. In order to economize space, it has been assumed that the student has some previous knowledge of theoretical and practical chemistry, and details of many analytical processes, which are described in general treatises on practical chemistry, have been, for that reason, omitted. The Editor has pleasure in expressing his thanks to Mr. LEOPOLD FIELD, Lambeth, and to Messrs. COOK, East London Soap Works, for much valuable infor- mation, and to his colleague, Mr. CHAELES CAETEE, for assistance in revising the proofs. J. C. LOXDOX, May 8, 1888. CONTENTS. PAKT I. SOAPS. CHAP. PAGES I. DEFINITION, HISTORY, AND PROPERTIES OP SOAP i 16 II. MATERIALS. i. FATTY MATTERS: ANIMAL FATS FISH OILS VEGETABLE OILS RE- COVERED GREASE. ROSIN. 2. ALKALIES: CAUSTIC-SODA LYES STEAM LYES CAUSTIC- POTASH LYES ALKALINE SILICATES SODIUM ALUMINATE. PRELIMINARY TREATMENT OP FATTY MATERIALS : RENDERING BLEACH- ING BONE-BOILING . 17 44 III. HYDROMETERS AND LYE TESTING . . . 4549 IV. SAPONIPICATION ... ... 5058 V. APPARATUS AND ARRANGEMENT OF THE FACTORY 59 80 VI. CLASSIFICATION OP PROCESSES : GENERAL PRO- CESS SAPONIPICATION UNDER PRESSURE COLD PROCESS 8189 VII. HOUSEHOLD, DOMESTIC, OR LAUNDRY SOAPS : i. CURD, OR WHITE, SOAP 2. GENUINE viii CONTENTS. CHAP. PAGES MOTTLED SOAP 3. CASTILE SOAP 4. ARTI- FICIALLY MOTTLED SOAPS 5. YELLOW, OR ROSIN, SOAP 6. MARINE SOAPS 7. SILI- CATED SOAPS 8. SULPHATED SOAPS . . 90 1 1 6- VIII. TOILET, OR FANCY, SOAPS : MATERIALS APPA- RATUS MANIPULATION FORMULA FRENCH SYSTEM 117 144 IX. MEDICINAL SOAPS 145 155 X. OLEIC-ACID, RED OR BROWN OIL, SOAPS SOFT SOAPS INDUSTRIAL SOAPS .... 156 167 XI. VARIOUS SOAPS AND SOAP POWDERS. PREPARA- TION OF SOAP IN SMALL QUANTITIES XII. RECOVERY OF GLYCERIN FROM SPENT LYES XIII. TESTING SOAPS. COMPARISON OF SOAPS PAET II. CANDLES. I. DEFINITION. HismRY II. MATERIALS : ANIMAL FATS VEGETABLE OILS WAXES FATTY ACIDS. REFINING PAR- AFFIN. PREPARATION OF FATTY ACIDS : LIME SAPONIFICATION ACIDIFICATION DIS- SOCIATION BY HEAT AUTOCLAVE PROCESS BOCK'S PROCESS. SEPARATION OF STEARIC AND OLEIC ACIDS. WICKS CONTENTS. ix CHAP. PAGES III. MANUFACTURE : DIPPING MOULDING HAND- FRAMES MOULDING MACHINES. NIGHT- LIGHTS. WAX CANDLES 256270 IV. SPECIALITIES : ORNAMENTAL CANDLES COLOURED CANDLES. QUALITY OF CANDLES . 271 274 V. BYE-PRODUCTS : OLEIC ACID. GLYCERIN. OLEIN. TESTING GLYCERIN .... 275288 APPENDIX: COMPOSITION OP BLACK ASH. STRENGTH OP SOLUTIONS OP CAUSTIC POTASH. STRENGTH OP SOLUTIONS OP CAUSTIC SODA. SODA ASH : COMPARISON OF ENGLISH AND FRENCH DEGREES. EXPORTS OP SOAP AND CANDLES. IMPORTS OF TALLOW AND STEARIN. STATISTICS OP SOAP AND CANDLE FACTORIES IN THE UNITED STATES 289294 INDEX 295306 BIBLIOGEAPHY. (English.} MUSPKATT'S " Chemistry applied to the Arts and TJanufactures." RICHARDSON and WATTS' " Chemical Technology." SPON'S " Encyclopaedia of the Industrial Arts.'' URE'S " Dictionary of the Arts and Manufactures." WAGNER'S " Chemical Technology." WATTS' " Dictionary of Chemistry." ALLEN'S " Commercial Organic Analysis " (1886). CARPENTER'S "Treatise on the Manufacture of Soap, Canutes, Lubricants, and Glycerin " (1885). CRISTIANI'S "Technical Treatise on Soap and Candles " (1881). DUSSAUCE'S "General Treatise on the Manufacture of Soap" (1869). FIELD'S Cantor Lectures on " Solid and Liquid Illuminating Agents " (1883). KURTEN'S " Art of Manufacturing Soap " (1854). OTT'S " Art of Manufacturing Soap and Candles " (1867). MORFIT'S "Chemistry applied to the Manufacture of Soap and Candles" (1847). MORFIT'S " Treatise on the Manufacture of Soaps " (1871). WATT'S " Art of Soap-making" (1884). WRIGHT'S Cantor Lectures on " Toilet Soaps " (1885). "Analyst." " Chemist and Druggist." " Journal of the Chemical Society." " Journal of the Society of Arts." "Journal of the Society of Chemical Industry." " Pharmaceutical Journal." " Year Book of Pharmacy." SOAPS AND CANDLES PART I.-SOAPS. CHAPTER I. DEFINITION, HISTORY, AND PROPERTIES OP SOAP. Definition. Chemically speaking, a soap is produced when- ever a metallic base is combined with & fatty acid, such as the acids, of the general formula C n H 2a _ 2 O 2 , occurring in, or obtainable from, the natural fats or fixed oils, and hence, besides the ordinary commercial soaps, we have the lead soap, or lead plaster of pharmacy, and also manganese, copper, mercury, zinc, tin, silver, cduminium, and other metallic soaps. But, in ordinary language, by soap we understand a compound of an alkali and a fatty acid the alkali potash affording, when so combined, soft soap, and the alkali soda forming hard soap. According to another definition, soap is a chemical com- bination of any oily with any saline matter, whereby the oil acquires a solubility in menstrua with which, naturally, it refuses to unite. MORFIT says : " True soap is a definite chemical compound 2 SOAPS. of one or more fat acids with a base, and a certain ratio of water of constitution." KJNGZETT* gives this definition : " Soap, considered com- mercially, is a body which, on treatment with water, liberates alkali." A similar definition is mentioned in the Reports of the Juries, Exhibition 1851 (p. 607): "Soap is a sort of magazine of alkali, which it gives up in the exact quantity required at any moment when it is rubbed with water." Dr. C. R. A. WRIGHT f states that "a soap, in the widest sense of the term, implies a compound of a fatty acid with an alkali, or other metallic derivative capable of playing the part of an alkali, glycerides not being classed as soaps, for the reason that glycerin, although capable to a certain extent of playing the part of an alkali, is neither such a metallic derivative nor an alkali itself." History. A complete soapery was found in excavating Pompeii, which contained some soap in a good state of pre- servation. Hence we are at once thrown back to the year A.D. 79 in our search for the first employment of soap. The- elder PLINY, who perished at that time, is the first writer who mentions soap in the sense in which we now under- stand the word. He states J that it was made from tallow arid ashes, the best materials being goat's tallow and beech- ask. He was also acquainted with the hard and soft varieties of soap. He ascribes the invention of the compound to the- Gauls, but states that it was well prepared in Germany.. References to cleansing by writers before this time only show that soap was unknown to them ; for instance, HOMER gives us an account of the washing expedition of NAUSIKAA,. * "The Alkali Trade," p. 173. | Cantor Lectures on Toilet Soaps, May 4, 1885. J "Nat. Hist." xxviii. 12, 51 (HOLLAND'S translation, ii. 328). "Odyssey," vi. 90-118. HISTORY OF SOAP. 3 but without any mention of soap. The word occurs twice in the Scriptures,* but the original word in both instances is borith, and BECKMANN has shown t that this really means alkali. We have distinct evidence that soap-making nourished in the seventeenth century, but it is only in the most modern times that the manufacture attained that extraordinary development for which this industry is remarkable, and which gave occasion for the following oft-quoted remarks of LTEBIG : " The quantity of soap consumed by a nation would be no inaccurate measure whereby to estimate its wealth and civilization. Of two countries with an equal amount of population, we may declare, with positive cer- tainty, that the wealthiest and most highly civilized is that which consumes the greatest weight of soap." J Various circumstances have contributed to the advance- ment of this manufacture since the commencement of the present century, but two discoveries have specially influenced it viz., CHEVREUL'S discovery of the true nature of fats, and LEBLANC'S discovery of a method for the artificial pre- paration of soda on a large scale. CHEVREUL'S researches, although they explain the nature of saponification, have perhaps contributed less to the progress of the soap manu- facture than to that of candle-making, but the development of the manufacture of soda has proved a most powerful stimulus to that of soap, by freeing it from dependence on the uncertain and limited supply of barilla and kelp. Soap was formerly heavily taxed. An excise duty of id. per Ib. was first imposed in 1711 on all soap made in Great Britain, and in 1713 this was raised to id. per Ib. In * Jer. ii. 22 ; Mai. iii. 2. f " History of Inventions," translated by JOHNSON (BOHN). j " Familiar Letters on Chemistry," letter xi. p. 129. B 2 4 SOAPS. 1782 the duty was again increased, and a distinction was for the first time made between hard and soft soaps, the duty on the former being 2\d. and on the latter ifd. per Ib. In 1816 the duty on hard soap was raised to $d. per Ib. In 1833 the duty was i%d. per Ib. on hard soap and id. per Ib. on soft. The duty was repealed in 1853. Properties. Only soaps made from alkalies and fatty acids are soluble in water, and consequently such only are valuable for cleansing purposes, and are commercially recog- nized as soaps. All other soaps are insoluble in water, the most familiar of these insoluble soaps being the lime soap, which separates in curdy particles whenever hard water is used for ordinary washing purposes. But cold water, however pure, never entirely dissolves soap without decomposition. The neutral salts of which soap consists are resolved, in contact with water, into an alkali which dissolves and an acid salt which .is precipitated.* The same decomposition takes place when hot weak solutions of soap are cooled. This behaviour explains why, in using soap even with the purest cold water, a white turbidity (soap-suds) is always produced. On this decomposition, probably, the purifying action of soap largely depends. The liberated alkali unites with the greasy dirt, and the insoluble acid salt forms the lather which envelopes it, and thus assists its removal. According to Dr. W. LANT CARPENTER^ considerable light has been thrown upon the manner of removal of dirt by soap by the researches of the late Prof. W. STANLEY JEVONS, F.R.S., upon the " Brownian movement " of small particles. When clay is stirred up with water, and the * MUSPRATT'S " Dictionary of Chemistry," ii. 875 ; WATTS' " Dic- tionary of Chemistry," v. 315 ; Srox's " Encyclopaedia," v. 1793. f SPON'S "Encyclopaedia," v. 1793. PROPERTIES OF SOAP. 5 water is allowed to stand, it clears itself very slowly, and microscopic examination showed that this was due to a kind of molecular movement of the infinitesimally small particles of the clay. To this movement Prof. JEVONS gave the name of pedesis, or pedetic action,* and he found that soap and sodium silicate enormously increased this action.t From, these observations, and from his own experiments, CAR- PENTER is of opinion that in the action of these substances in promoting the molecular movement of extremely minute particles is to be sought part of the explanation of the cleansing power of soap. Soap is readily soluble in alcohol and in hot water. A hot concentrated solution of ordinary soap solidifies on cool- ing to a jelly-like mass. Soap is insoluble in a solution of common salt, and if the latter is added to a hot solution of the former, the soap separates as an oily layer, which solidi- fies on cooling. Prof. ROTONDI, of the Eoyal Industrial Museum of Turin, rejects the theory of BERZELIUS that the usefulness of soaps depends upon the facility with which neutral soaps decom- pose, on solution, into acid soaps and free alkali, and also that of PERSOZ, who assumes neutral soaps to be soluble in hot water without decomposition, but to be resolved in cold water into acid and basic soaps, the latter dissolving fatty substances by saponification. These hypotheses do not explain why hot soap solutions are more active than cold ones. The following conclusions were arrived at by ROTONDI from experiments upon carefully purified Mar- seilles soap: Neutral soaps are decomposed, on solution, into basic and acid soaps ; the latter are insoluble in cold, and only slightly soluble in hot water ; they are not dia- * " Quarterly Journal of Science," April 1878, No. Iviii. f Report of the British Association, 1878, p. 435. 6 SOAPS. lysable, and so are thus separable from the former, which readily dialyse. The neutral soaps, though thus decom- posed, lose neither free nor carbonated alkali. Basic soaps are completely soluble in hot and cold water, and are entirely precipitated by sodium chloride without loss of alkali ; their solutions dissolve acid soaps on heating, but become turbid on cooling. They emulsify fatty bodies readily, but no saponification of the latter takes place ; neutral soaps possess this property to a smaller extent ; acid soaps scarcely at all. Carbonic acid produces, in cold solu- tions of basic soaps, insoluble compounds, which, however, disappear on heating. Hence, waters rich in carbonic acid are not suited for industrial operations with soap. The above explains the greater efficiency of hot soap solutions, and has an important bearing upon the manufacture and industrial uses of soap, inasmuch as different results are often observed in the use of soaps made from the same materials (and containing no free alkali), which are due to their containing variable amounts of acid and basic soaps. ROTONDI considers that soaps should consist, as nearly as possible, of neutral compounds, instancing the injury arising in the boiling of silks from the presence of excess of basic soap, and that these points should be borne in mind in the operations of soap-boiling, as well as in soap analysis, when it is desired to ascertain the fitness of a sample for a given purpose.* The partial decomposition of a neutral soap when treated with cold water is called hydrolysis, and has been recently carefully investigated by WRIGHT and THOMPSON, f with very interesting results. Their experiments were made as * "Chem. Kev." xiv. 228 ; " J. Soc. Chem. Ind." 1885, p. 601. t " J. Soc. Chem. Ind." 1885, p. 629. . PROPERTIES OF SOAP. 7 follows: The soaps examined were either prepared by themselves, or obtained from manufacturers with infor- mation as to the fatty acids present ; they were carefully examined, and, in those cases where minute amounts of free alkali were present, corrections were made for these small .amounts. Weighed quantities of soap, representing known quantities of anhydrous soap, were dissolved in known quanti- ties of distilled water on the water-bath, and, after cooling to near the ordinary temperature, the liquids were treated with pure sodium chloride, so as to throw out of solution all, or nearly all, the soap as curd. The curds thus precipitated, on drying and dissolving in alcohol, were always more or less acid, phenol- phthalein being the indicator, so that one way of determining the amount of hydrolysis was to determine the amount of alcoholic potash or soda solution required to neutralize this acidity. It was found, however, in practice to be far more convenient to determine the .alkali contained in an aliquot part of the brine, correcting the amount found for the free alkali (if any) originally contained in the soap. With smaller proportions of water, the addition of moderate quantities of salt sufficed to throw all soap out of solution so perfectly that, at most, only traces of fatty acids could be obtained from the brine by acidulating and shaking with ether ; with larger pro- portions it was found convenient to evaporate the brine until nearly saturated, and filter again from any soap thrown out of solution during the evaporation, using only a fraction of the salt requisite to saturate the water for the salting out, rather than to use more salt in the first instance and titrate without evaporation, greater accuracy in hitting the terminal reaction being thus attained. With cocoa-nut oil soaps the brines were evaporated to dryness, and then treated with just sufficient water to dissolve the salt, and SOAPS. filtered. In this way, liquids free from more than traces of soap were obtained, the soap originally contained in the- brine before evaporation being thus eliminated. The following corrected mean values were obtained in a lengthy series of experiments with various soda soaps, all of which were neutral or only faintly alkaline. The numbers represent the quantities of Na 2 set free by hydrolysis, reckoned per 100 parts of Na 2 combined with fatty acids in the soap^ x molecules of water being used for one of anhydrous soap. Fatty Acids. Mean Mole- Hydrolysis bro light about by x M of Water. olecules Weight. ^=150. la; 250. #=500. , #=1000. X = 2000. Pure stearic acid 284 0.7 | 1.0 1.7 1 2.6 3-55 Nearly pure palmitic acid 2tf 1.45 1.9 2.6 3.15 3-75 Crude lauric acid (cocoa-nut oil soap) 195 3-75 i 4-5 5-4 6. 45 7-1 Pure oleic acid . 282 1.85 2.6 3-8 q.2 6.65 Crude ricinoleic acid (castor oil soap) 294 1.55 2.2 3-o 3-8 4-5 Chiefly stearic, palmi- tic and oleic acids (palm oil and tallow soap) 271 I.I 1.55 2.6 4 .I 5-3 Chiefly tallow and resin (primrose) 280 1.5 I 2.2 3.1 4.2 5-3 Cotton seed 250 2.25 | 3.0 5-o ; 7-5 9-5 The above results lead to the following general con- clusions : 1. The amount of hydrolysis brought about by the action of a given quantity of water on a neutral soap is variable with the nature of the fatty acids from which the soap is made, but in all cases increases with the amount of water employed relatively to the soap, but less rapidly. 2. Addition of excess of alkali to a neutral soap causes a diminution in the amount of hydrolysis effected under PROPERTIES OF SOAP. 9 given conditions, to such an extent as completely to stop the action with comparatively small proportions of water r when the free alkali only amounts to a fraction (say 20-25 per cent.) of the alkali combined with the fatty acids. 3. Alcohol, even when not absolutely anhydrous (90-95 per cent.), does not decompose ordinary neutral soaps intc* free alkali and acid salts. If, however, water be added to an alcoholic soap solution, more or less hydrolysis takes place, so that if a gelatinous mass of neutral soap, dissolved in strong spirit containing a little phenol-phthalein, be treated with water, a more or less strongly marked coloration is noticeable as the water diffuses into the mass. The following observations of LIEBIG on the behaviour of soap with a solution of common salt are of great practical importance to the soap-maker : " If a piece of common hard soap be placed in a solution of salt at ordinary tempera- ture, it floats upon the surface without even being moistened, and, if the liquid be heated to boiling, it separates without foam into gelatinous flocculse, which collect on the surface,, and, upon cooling, unite into a solid mass, from which the solution flows off like water from fat. If the floccuke be taken out of the hot fluid, they congeal, on cooling, into an opaque mass, which may be pressed into fine laminae between the fingers without adhering to them. If the solution is not quite saturated, the soap then takes up a certain quantity of water, and the flocculae separate through the fluid on boiling. But even when the water contains ^ J^th part of common salt, ebullition does not produce solution. If the soap is boiled in a dilute and alkaline solution of salt, and suffered to cool, it again collects on the surface of the fluid in a more or less solid state, depending on the greater or less degree of concentration of the solution that is, on the quantity of water taken up by the soap. By boiling the dilute solution of salt with soap for a considerable time, the io SOAPS. aqueous flocculse intumesce, and the mixture assumes a foam}* appearance ; but still they are not dissolved, as the solution separates from them. The flocculse, however, have become soft and pasty, even after cooling, and their pastiness is due to the quantity of water they have taken up. By continuing the boiling, this character again changes, and in proportion as the water evaporating renders the solution more concentrated, the latter again extracts water from the noccuke ; the liquid, however, continues to foam, but the bubbles are larger. At length a point is reached at which the solution becomes saturated ; the larger iridescent bubbles, formed just before, disappear, and the liquid continues to boil without froth; all the soap collects as a translucent mass on the surface ; and now the solution and soap cease to attract water from each other. If the plastic soap be now removed and cooled, while the solution is pressed out, it becomes so solid as scarcely to receive an impression from the fingers. In this state it is called grain-soap. 11 The addition of salt, or its solution, to a concentrated alkaline solution of soap in water, precipitates the soap in gelatinous flocculae, and the mixture behaves precisely as solid soap boiled with a solution of salt. Potassium car- bonate and caustic potash act exactly as salt in separating soap from the alkaline fluid. "The application of these facts to the manufacture of soap is obvious. The fat is kept boiling in an alkaline lye until all pasty matters disappear ; but the lye should have only a certain strength, so that the soap may be fairly dissolved in it. Thus, tallow may be boiled for days in a caustic potash solution of specific gravity 1.25 without being saponified. If the lye be stronger, a partial saponi- fication ensues ; but, being insoluble in the fluid, the soap floats on the surface as a solid mass. By the gradual addi- PROPERTIES OF SOAP. 11 tion of water, with continued boiling, the mass at a certain point becomes thick and clammy, and with more water an emulsion is formed. On continued heating, this becomes perfectly clear and transparent if a sufficient quantity of alkali be present. In this state it may be drawn out into long threads, which, 011 cooling, either remain transparent, or are milky and gelatinous. As long as the hot mass suffered to drop from a spatula exhibits a milkiness or opalescence, the boiling is continued, or more alkali added. When excess of alkali is present, the milki- ness arises either from imperfect saponification, or want of water , the former is known by dissolving a little in pure water, which becomes perfectly clear when the whole is saponified. If the lye contain lime, the mixture is also turbid, but the addition of an alkaline carbonate causes the turbidity arising from this cause to disappear instantly. " In order to separate the soap from water, free alkali, and glycerin, a large quantity of salt is gradually added to the boiling mass, waiting, after each addition, .till the portion added is completely dissolved. The first addition increases the consistency of the mass, while each successive portion renders it more fluid, till it loses its adhesive character, and drops from the spatula in short thick lumps. As soon as the congelation is complete that is, when gelatinous floc- culse separate from a clear watery liquid the fire is extin- guished, the soap allowed to collect on the surface, and cooled either on the liquid or ladled out, and allowed to get solid. " The same results are also produced, although in a less energetic manner, by potassium chloride, alkaline car- bonates, sodium sulphate, potassium acetate, and ammo- nium chloride. Of these, sodium sulphate and potassium chloride have but a very slight action. Concentrated caustic lyes also separate soap from its solution in the 12 SOAPS. same manner as common salt. In weak caustic tye, on the contrary, soap is perfectly soluble. On this account, soap- boilers, especially at the commencement of the operation, except in the case of cocoa-nut oil, always use weak lyes, as the stronger would prevent the necessary amount of contact amongst the ingredients, and very much retard the process of saponification. Thus, by means of caustic or saline solu- tions, not only all foreign matters, but also the glycerin, may be completely separated from soap." T. N". WHITELAW,* starting with the well-known fact that soaps, when boiled with solutions of common salt, retain amounts of water inversely as the quantity of sodium chloride in solution, has described certain experiments instituted by him with the view of denning this action. Tallow and palm- nut oil soaps were selected as affording types of the manner in which solutions of soap behave with salt, the greater number of oils used in soap-making resembling tallow, while cocoa-nut oil is more like palm-nut oil in the manner in which its soap solution behaves. Six grms. of fatty acids from tallow and palm-nut oils respectively were saponified in a flask of about 250 c.c., separated with excess of caustic soda from solution, and, after cooling till the soap curds had solidified, the caustic soda liquor was allowed to drain off. The soaps so obtained were dissolved in 100 c.c. of distilled water, and a weighed quantity of pure NaCl added, enough to obtain distinct separation of the soap in small curds. Then water was added in small quantities from a burette, and the soap solution brought to the boiling point and well agitated after each addition, a cork provided with about 14 inches of glass tubing preventing any loss of water during the momentary boiling. * " Journ. Soc. Chem. Ind." 1886, p. 90. PROPERTIES OF SOAP. 13 With a certain strength of solution, the soap grains were distinct and separate, without any tendency to settle out fluid soap. With a further addition of water, the grains became softer, and a thin layer of fluid soap could be ob- served settling beneath them. With the addition of still more water, the grains became entirely fluid, and the fluid soap occupied more and more of the total fluid volume as more water was added, until a point was reached when the fluid became clear and bright, and the soap completely dis- solved. The points of distinct separation in grains, and the points of complete solubility in boiling solutions, were found to be as follow : Separation in Distinct Grains. NaCl per Cent. Completely Soluble. KaCl per Cent. Tallow soap .... Palm-nut oil soap . . , 6. 5 18.0 3-0 13.0 On cooling these solutions, the tallow soap remained com- pletely soluble, and, when cold, formed a firm jelly, while the palm-nut oil soap separated as it cooled into a thin layer on the surface of the salt solution. It was found that the tallow soap is nearly as soluble in the cold as in the hot solution of salt, but that while palm-nut oil soap is soluble in boiling water containing 13 per cent, of NaCl, it is in- soluble in cold solution of 3 per cent. A difference was observed in the composition of the soap according as it separated in distinct grains from the saline solution, or as slightly liquefied grains floating on a thin layer of liquid soap above the solution. In the first case we have an ordinary soft curd soap, and in the second case, if we consider the subnatant saline solution removed, we have soap grains washed by a solution of soap. Both these methods viz., purifying with salt and purifying with soap SOAPS. are adopted on the large scale to obtain pure soap of a definite composition. WHITELAW obtained the following results from the analysis of the two soaps thus prepared : Soap settled from Salt. Soap. Palm Oil Curd. Tallow Fitted Soap. Water . Soda(Na,0) . Fatty anhydrides . Sodium chloride . 1 3I-38 : : $2 , 1.67 314 7-0 60.3 i-3 100.00 IOO.O Action of More Concentrated Solutions of Common Salt upon Soaps. A soap from a good quality of olive oil, after boiling for thirty minutes with an 8 per cent, solution of salt, retained 31.6 per cent, of water; with a 17 per cent, solution, it retained 25.7 per cent. ; and with a saturated salt solution, it retained 19.1 per cent. The following are analyses of various soaps after thirty minutes' treatment with a hot saturated solution of salt : Soap. Water. Per Cent. Fatty Anhydrides. Per Cent. Soda. Per Cent. Sodium Chloride. Per Cent. Olive oil Tallow . Palm-nut Cotton oil Castor oil ig.i 16.94 iS.8 17.2 48-3 67.9 64.49 66.4 62.4 31-3 7.8 7.64 9-9 6.4 37 5-2 10.93 4-9 14.0 I6. 7 Prolonged boiling does not reduce the quantity of water retained by the soap after thirty minutes' treatment. This. is shown by the following analysis of a soap after sixty minutes' treatment : PROPERTIES OF SOAP. 15 Olive Oil Soap treated Sixty Minutes. Water Fatty anhydrides .... Soda Sodium chloride .... 100.00 There is thus a limit to the action of sodium chloride in withdrawing water from soaps. Soap which contains a larger amount of water than curd soap is called ivatered when water or weak lye is added and mixed with the curd in the pan itself, or when the curd is treated subsequently with water whilst still in contact with the brine. When, however, the water is added and crutched into the curd after its removal from the pan, the soap is termed liquored or filed. The term filed is also applied to soap which has been mixed either with the soluble alkaline carbonates, sulphates, or silicates, or with such insoluble materials as barium sulphate, chalk, clay, china clay, fuller's earth, pumice stone, sand, steatite, starch, talc, &c. The following are the characters of soap given in the British Pharmacopoeia (1885) : HARD SOAP (Sapo durus : white Castile soap), made from soda and olive oil. Colour, yellowish-white. Dry, inodor- ous. Horny, and pulverizable, when kept in dry warm air. Easily moulded when heated. Soluble in rectified spirit. Soluble also in hot water, the solution being neutral or only faintly alkaline to test-paper. It does not impart a greasy stain to paper. Incinerated, it yields an ash which does not deliquesce. CURD SOAP (Sapo animalis). Made from soda, and a purified animal fat consisting principally of stearin. Colour, white, or with a very light-greyish tint. Other- wise, its characters are the same as those of sapo durus. SOFT SOAP (Sapo mollis). Made from potash and olive 1 6 SOAPS. oil. Colour, yellowish-green. Inodorous. Of a gelatinous consistence. Soluble in rectified spirit. Does not impart an oily stain to paper. Incinerated, it yields an ash which is very deliquescent. The United States Pharmacopoeia (1883) gives the following characters of soap prepared from soda and olive oil : A white or whitish solid ; hard, yet easily cut when fresh ; having a slight, peculiar odour, free from rancidity ; a disagreeable, alkaline taste, and an alkaline reaction. Readily soluble in water and in alcohol. When cut into thin slices, and dried to a constant weight at a 'temperature of 110 C. (230 F.), it should not lose more than 34 per cent, of its weight (absence of an undue amount of water). A 4 per cent, alcoholic solution should not gelatinize on cooling (absence of animal fats). 100 parts of the soap when dissolved in alcohol should not give more than 3 parts of insoluble residue (limit of sodium carbonate, &c.), and at least 2 parts of this residue should be soluble in water (limit of silica, and. other accidental impurities). CHAPTER II. MATERIALS. THE materials which are essential to the soap manufacturer may be classified under two heads : i. Fatty matters and rosin ; 2. Alkalies. i. FATTY MATTERS. The fatty substances employed have been fully described in the fourth volume of this series of Handbooks,* but the tabular statement given on pp. 18-22 will be convenient here. Recovered Grease. Obtained from the washings of woollen works. These are decomposed with sulphuric acid, steam is admitted to hasten separation, the fatty acids are filtered through hempen cloth, and the fatty mass then subjected to hydraulic pressure. It is of a brownish colour, and requires to be used with judgment, as it is liable to con- tain varying quantities of unsaponifiable oils. Also, extracted by carbon disulphide from the residue of stearin factories, from sawdust which has served for filtering oil, from refuse waggon grease, from oily rags, &c. Recovered grease is never used alone in soap-making, but mixed with palm oil or tallow, and chiefly "for rosin soaps. Rosin. Syn. COLOPHONY. This is an important ingre- dient in the production of soap. It is the residue left * "Oils and Varnishes." 18 SOAPS. a s . i'sj a o M ."= a a I III! ^^ ^^ " ^ rri ;il . a ^ . . bo *| iai! 3 SM fl < J n '5 tL *i a H 3 S f H -So W 03 .11 3 as C rrj g t* P ft MATERIALS. ft 02 .3 CJv. t QQ 0* -^ 03 - fto I tf to -2 ' _5 1* ft 02 o M O cc "- 1 | oT^" J3 .-g g g gr 3 ^ O . ,&! .si jMix. ill ^ 'ft -2 I - . H H g 1 O 02 ft ft OQ 02 O III A f & ..! . c o o ft' ^^ ^^ 00 H | o a* g a C 2 20 SOAPS. fa it t M W M O H ,2_ "1 i 02 *d I I 3 S 01 bfl Co at *J 8ll^ 111* |S|a O Q i i I S MATERIALS. 21 ON O g wit Bassi Br a. ure, or by boi from seeds or longi/oUa. sia parkii, a e inferior kinds are used oap-making e.g. : orgon" obtained by fer- ing and boiling in water ressed cake, or marc, after ction of the finer kinds, kimming off the oil. il of the infernal regions " mmed off the waste water p a Oi ski j^fl= lllg- T , ^ .3 ^ S -M SAP ONI PICA TION. 55 Acrylic, or C n H 2n _ i.CO(OH) Series. Name of Acid. Formula. Equi- valent. Melting Point C. Source. Oleic. C^ CO(OH) 282 J 4 Tallow, suet, lard, almond, and olive oils, &c. Ela'idic* . C^H^. CO(OH) 282 44-45 Ditto. Linoleic . C lb .H 2g O 2 252 Linseed oil. Kicinoleic . C H 2 282 __ Castor oil. Physetoleic C H 254 30 Sperm oil. Doeglic CWK 296 Bottle-nosed whale. Brassic, or erucic . CHA 338 33-34 Rape oil. From the equation given above (p. 52) we learn some- thing more than merely the change of arrangement which takes place in the combination. If we add up the various chemical equivalents in the equation, we shall find that, taking palm oil as simply tri-palmitin, C 3 H 5 (OC 16 H 31 0) 3 , 806 parts by weight (oz., lb., cwt., or tons) unite with 120 parts by weight of caustic soda (3NaHO) to produce 834 parts of palm soap, and that 92 lb. of glycerin are set free. Hence, it is easy to calculate how much soda, or potash, will be requisite to completely saponify any given quantity of fat. Inasmuch, however, as palm oil is not pure tri-palmitin, but contains also tri-olein (the stearin may be neglected), the actual equivalent of palm oil will be more nearly that of Tri-palmitin . C 3 H,(C 16 H 31 0,) 3 = 806 Tri-olein . C 3 H 5 (C 18 H 33 O 2 ) 3 = 884 1690 -~ 2 = 845 Then, as ("molecular] fequiva-] lb. lb. 845 4 weight of I : 93 -j lent of I : : 100 (palm oil) : 1 1 ( palm oil J ( 3 Na a O J of caustic soda (100 per cent. Na 2 0) requisite for the saponi- fication of 100 lb. of palm-oil. * Isomeric with oleic acid, from which it is obtained by the action of nitrous acid. 56 SOAPS. The proportion of tallow equivalent to 3Na a O is similarly found to be 887 Tri-stearin . C 3 H 5 (C 18 H 35 O 2 ) 3 = 890 Tri-olein . C 3 H 5 (C 18 H 33 2 ) 3 = 884 and that of cocoa-nut oil, 748, thus : Tri-laurin . C^C^O.^ = 638 Tri-myristin . C 3 H 5 (C 14 ~H 27 O 2 J 3 = 722 Tri-olein . CaH^CjgH^O.^ = 884 1774 -~ 2 = 887 2244 4- 3 = 748 Calculating thus, the following proportions are ob- tained :* ioo Ib. of Kequire of Soda (ioo % Na,0). Potash (ioo%K,0). Tallow ..... Palm oil . Cocoa-nut oil . Oleic acid (tri-olein) io.5olb. 11.00 12.43 10.52 15.92 Ib. 16.67 18.86 15.95 As the percentage of available alkali at command is never ioo, it is requisite to make a correction for the percentage available. If that were 60 per cent., then the amount of alkali to be employed for every ioo Ib. of fat would be the above quantities increased in the proportion of 60 to ioo j or if it contained 20 per cent, of available alkali, then the proportion would be five times the above ; and so on. The quantity of alkali necessary to saponify any fat may also be found experimentally by KOETTSTORFER'S saponifica- tion method,t which, after the standard solutions have * CRISTIANI, " Treatise on Soap and Candles," p. 154. f For details of the process, see ''Analyst," 1879, p. 106; or "Churchill's Technological Handbooks" "Oils and Varnishes," p. 246. SAPONIFICA TION. 57 been prepared, is simple, accurate, and rapid. The follow- ing are the figures obtained in this way by KOETTSTORFER, STODDART, ARCHBUTT, MOORE, HUBL, ALLEN, and others :* Saponification Equi- Percentage off KHO valent, or No. of Nature of Oil. for Saponification, or Ib. KHO for Grammes of Oil or Fat saponified by One 100 Ib. Fat. Equivalent inGrammes of any Alkali. A. OLEINS Lard oil . 19.10 to 19.60 \ Olive oil . 19.10 to 19.60 Olive oil . 18.93 to 19.26 Almond oil (sweet) . Arachis oil 19.47 to 19.61 19.13 to 19.66 - 285 to 296 Tea oil . 19-55 Sesame oil 1 9.00 to 19.24 Cotton-seed oil 19.10 to 19.66 j B. RAPE OIL CLASS Colza and rape oils . 17.08 to 17.90 | Rape oil . Mustard-seed oil 17.02 to 17.64 1 7.40 to 17.50 J- 313 to 330 Cabbage-seed oil 17.52 ) C. VEGETABLE DRYING OILS Linseed oil 18.74 to 19.52 Poppy-seed oil 19.28 to 19.46 Hemp-seed oil . 19.31 286 to 300 Walnut oil 19.60 Niger-seed oil . 18.90 to 19.10 D. MARINE OLEINS Cod-liver oil . 18.51 to 21.32 Menhaden oil . 19.20 Pilchard oil 1 8.60 to 18.75 Seal oil . 18.90 to 19.60 - 250 to 303 Southern whale oil . 1931 Northern whale oil . 18.85 to 22.44 Porpoise oil 21.60 to 21.88 E. BUTTER CLASS Butter fat 22.15 to 23.24 241 to 253 Cocoa-nut oil . Palm-nut oil . 24.62 to 26.84 22.00 tO 24.76 j 209 to 255 * ALLEN, " The Analyst," 1886, p. 146. f These numbers x .5535 = percentage of soda (Na 2 O 100 per cent.), or Ib. of soda required for 100 Ib. of any of the fatty bodies. SOAPS. SAPONIFIGATION EQUIVALENTS (continued}. Nature of Oil. Percentage of* KHO for Saponification, or Ib. KHO for 100 Ib. Fat. Saponification Equi- valent, or No. of Grammes of Oil or Fat saponified by One Equivalent inGrammes of any Alkali. F. STEARINS, &c. Lard . . . j 19.201019.65 Tallow . 19.32 to 19.80 Dripping . 19.65 to 19.70 Butterine . . 19.35 to 19.65 Goose fat . . | 19.26 - 277 to 294 Bone fat . . . 19.091019.71 Palm oil . . . 19.63 to 20.25 Cacao butter . . j 19.98 j G. FLUID WAXES Sperm oil 12.34 to 14.74 38010454 Bottle-nose oil 12.30 to 13.40 419 to 456 H. SOLID WAXES Spermaceti 12.73 to 13.04 43210441 Bees' -wax 9.20 to 9.70 Carnaiiba wax . 7. 90 to 8.51 Chinese wax . 6.50 I. UNCLASSED Shark-liver oil . 14.00 to 19.76 284 to 400 Wool fat (suint) 17.00 330 Lanolin . 9.83 570-9 Olive -kernel oil 18.85 298 Castor oil 17.60 to 18.15 30910319 Japanese-wood oil . 21.10 266 Japan wax 21.01 tO 22.25 25210 267 Myrtle wax 20.57 to 21.17 265 to 273 Blown-rape oil 19.80 to 20.40 275 to 284 Colophony 17.00 to 19.30 290 to 330 In the case of the glycerides, the saponification equivalent is one-third of the molecular weight, but in case of mon- atomic ethers, like those which essentially constitute sperm oil and bees'-wax, the saponifieation equivalent is identical with the molecular weight. * See note f on p. 57. CHAPTER V. APPARATUS AND ARRANGEMENT OP THE FACTORY. APPARATUS. THE apparatus of a soap factory is of a simple kind, and may be arranged under the following heads : i. The lye tanks, for the alkalies. 2. The pans, for effecting the combination between alkali and fat. 3. Various appliances for ivorking the product into com- mercial forms. i. Lye Tanks, or Vats. When the alkalies are caus- ticized at the factory, the operation is performed in cast- or wrought-iron tanks, 6 or 7 feet broad, and 4 or 5 feet in depth, either furnished with a perforated false bottom, or having a coarse piece of matting placed over the plug-hole. From these tanks the lyes, of various strengths, are con- veyed to the reservoirs. These may be, for convenience, placed at one end of the soap-pan series, and at a some- what higher level, so that the lyes may be readily run, by means of a shoot, into the boilers, as required, or as N N N, Fig. 22, p. 78, or B B B, Fig. 23, p. 80. If the alkalies are obtained by the soap-maker in the caustic state, their solution may be made in cast-iron or sheet-iron kettles. For the finer qualities of soap, especially toilet soaps, for 60 SOAPS. which it is necessary to have a perfectly clear and colour- less lye, it is advisable to have the vat or tank lined with lead.* 2. The Pans. In these the combination between the alkali and the fat is effected. They are variously termed pans, coppers, caldrons, kettles, or boilers, and they differ somewhat in construction, according to the process of soap- making adopted. Speaking generally, large coppers offer advantages over small ones in economy of labour, fuel, and lye. It will be convenient to consider the construction of the pans under the heads of the particular processes for which they are suitable. The chief methods followed may be classified thus : 1. The ordinary 2 )rocess (large-boiler process) : the open boiling of an indefinite, i.e., not exactly proportioned, mix- ture of fat and alkali. 2. Processes requiring the mixture of fat and alkali in calculated proportions : a. The cold process (little-pan 'process). b. Boiling under pressure. c. Open boiling. d. Free-acid process. i. Open Boiling. The pans are made either of cast or wrought iron in .small factories, often of cast iron, either in one piece, or in plates united together by iron cement ; in larger factories, more frequently of wrought-iron plates riveted together. They are usually made with a flange at the rim, and above this rim is fixed the curb, which is often made of wood, well hooped with iron rings. Their capacity varies according to the quantity of soap to be made at each operation : some- * DUSSAUOE. APPARATUS OF THE FACTORY. 6i< times 15 feet deep and 15 feet in diameter, and capable of turning out 25 to 30 tons at one boiling. It Las been ascertained* that for every 100 Ib. of fatty matter a capacity of 37 J gallons is required. Hence 1000 Ib. fat require a copper of 375 gallons capacity 2000 ,, 750 ,, 3000 1000-1125 ,, In some large American factories the coppers extend through several storeys of the building. The heating may be accomplished either by fire or by steam. In either case the pans are set in brickwork, and so built round, when fire is used, that the fire shall not play upon the sides, but only on the convexity of the lower part of the boiler ; but, even after every attention has been given to the construction of the arrangement on the most scientific principles, there is an enormous waste of fuel. Heating by steam may be effected either by passing the steam directly into the pan by steam-pipes terminating in a perforated coil resting on the bottom of the pan (open, or ivet method) ; or (a) by a closed coil, or (b) by means of a steam-jacket (close, or dry method). If the steam is dis- charged directly into the mass of soap, as in the open method, some disadvantage is experienced through the weakening of the lye by the condensation of the steam, and, on this account, the use of more concentrated lyes is rendered necessary. The arrangement found to work best is to send the steam through a flat, closed worm about 3 or 4 inches above the bottom of the pan. In this way a pan holding 1000 Ib. may be boiled in half an hour, while to do the same by means of a fire would take from three to four hours. Besides, a single steam boiler and one furnace will thus heat * DrssAucE, " Treatise on the Manufacture of Soap," p. 344. 62 SOAPS. several pans at once, and there is no danger of the soap burning. Steam, therefore, affords economy of fuel, labour, and time, and the boiling can be more readily, at any time, controlled. Superheated steam is still more rapid in its operation, and cheaper than ordinary steam.* The lids of the pans, made either of wood or iron, are arranged so that they may be put down, or taken off, by means of a chain and pulley. The soap is removed either by pumps or by ladling, and the lyes either by pumping or by a pipe fixed to the bottom of the copper. FIG. 6. Fig. 6 represents a boiler arranged for heating by the direct heat of a fire. Fig. 7 is a representation of the arrangement designed by CAMPBELL MORFIT for employing steam heat, and known as Morfitri steam series. In this figure three caldrons, A A A, are shown. In large factories this is a convenient number, though more are often used, but, in a small work, one will answer, though there will always be a loss of time in cleaning it when the charge has to be changed from yellow to white soap. The * DUSSAUCE, " Treatise on the Manufacture of Soap," p. 350. APPARATUS OF THE FACTORY. 63 6 4 SOAPS. feeder, G, is attached to the boiler, w, which is generally fitted against the wall, immediately above the caldrons. The cook i is for the withdrawal of the spent lyes. The pipe, L, called the blow-pipe, serves to communicate, when necessary, additional heat to the contents of the pan, and is also useful to stir up the mass occasionally, an operation more readily accomplished in this way than by a crutch in the hands of a workman. Steam is let on or off by the cock H. Waste steam passes off through x. The current of steam from the boiler may be regulated by the cock P. 2. Processes requiring Definite Proportions of Alkali and Fat. a. Cold process. The apparatus required for this opera- tion, according to HAWES, who invented it, may be an ordinary caldron (Fig. 8) with the addition of a machine to Fio. 8. produce the intimate admixture and minute division of the tallow; or a cylinder, as represented in Fig. 9, may be used. b. Boiling under pressure. For boiling under pressure, DUNN'S apparatus, represented in Fig. 10, may be employed. The boiler should be furnished with a man-hole, A, a safety-valve, B, a thermometer fixed in a mercury chamber, C, APPARATUS OF THE FACTORY. 65 and all the ordinary appendages of such an apparatus. D is the feed-pipe, and E the discharge-cock. When in use, the valve is weighted till the temperature in the boiler FIG. 10. rises to 310 F., and the boiling is complete in about an hour after that temperature is reached. c. Open boiling. The ordinary open pans already de- scribed are suitable for preparing the soaps which fall under this head. d. Free-acid process. This is also called Morfit's process. The boiler is made of wrought iron, is steam-jacketed, and is fitted with a wrought-iron stirrer for thoroughly mixing the ingredients. Fig. 1 1 is a representation of the steam- jacket pan designed by MORFIT. A is the interior of the kettle, surrounded by brickwork ; B is the outer cast-iron caldron, which should fit the inner P 66 SOAPS. kettle tightly so as to prevent any escape of steam ; D is the steam-pipe from the boiler, fitted with a cock by which steam may be let on or off; C is the discharge-pipe for con- FIG. ii. densed vapour the cock in this pipe may be left slightly open so as to form a safety-valve ; E is the discharge-pipe of the kettle. A pump may be conveniently employed for taking off or removing soap, when required, from one pan to another, or for introducing either hot or cold lye, or strengthening change lye. A very serviceable description of pump is made by Hersey Bros., of South Boston, Mass., and is represented in Fig. 12 (a, bj and c). a represents the pump complete. When the pump is rotated in the direction of the arrow, the outlet marked s is the suction ; when rotated in the opposite direction, the opposite outlet becomes the suction, and thus, by giving a few revolutions by hand in this direction, the discharge-pipes may be emptied of their con- tents, b is a view of the interior of the pump when the cover is taken off; when turned in the direction of the arrow, the blade F sweeps round, drawing the fluid in at i, APPARATUS OF THE FACTORY. 67 and forcing it out at H, the contents of the pump being twice emptied at each revolution. The fluid is prevented from passing from one side to the other by the contact of the cone with the cover, c shows the cone and blade, and forms the entire working part of the pump. No valve is FIG. 12. used, and the operation of the pump is consequently little liable to any derangement. The pump may be set up in any convenient position adja- cent to the pan, not more than 10 feet above its bottom, and connected to it by means of a 2|-inch iron pipe, tapped through the iron plate at a distance of about 2 feet above the worm, or coil. Several pans may be connected with the F 2 68 SOAPS. pump by iron pipes, with valves placed upon them on the outside of the kettle, so that any one of them may be pumped off and framed without disturbing the others. In- side the pan the pipe has a suitable swing- joint so arranged that it can be raised or lowered at pleasure. 3. Appliances for Finishing the Soap. Prames. The frames, which were formerly made only of wood, are now constructed of iron, commonly cast iron, and the wooden ones are chiefly used for mottled soaps, which FIG. 13. require slower cooling than other descriptions. When soap was subject to duty, the dimensions of the frames were fixed by law, and were required to be exactly 15 inches by 45 inches inside, and not less than 45 inches deep. These dimensions are generally still retained in England, and APPARATUS OF THE FACTORY. 69- hence an English bar of freshly made hard soap measures 45 inches in length. The wooden frame is made up of a number of separate sections, piled upon each other, and fitting closely together. Each section, having the internal measurement just men- tioned, is about 9 inches in depth, and is constructed of wood, : about 2 to 3 inches in thickness, lined with thin sheet-iron. These are frequently piled upon one another to the height of more than 20 feet. The bottom of the frame may be of wood, or brick, and furnished with a well to receive the drainings. When the soap has become solid, the frames .are removed one by one, and the block of soap remains ready for division into slabs. Fio. 14. Outside view of crutching machine. 70 SOAPS. Iron frames are now extensively used. Fig. 13 is a re- presentation of WHITAKER'S patent frame,* much used by American firms. It consists of two sides of plate-iron, flanged at their upper edges, and strengthened by ribs of corrugated plate-iron, riveted to the outer surface, and run- ning in the direction of the length of the frame. These ribs are intended to prevent the budding or twisting of the side- FIG. 15. Working part of crutching machine. plates. The trouble and expense of the ordinary stays and supports are thus avoided, as the frame is self-sustaining.. The sides are connected by ends made of 2 -inch plank, secured by clamps. The frame is very light, and easily * Made by Horsey Bros. APPARATUS OF THE FACTORY. 71 worked. The soap cools sufficiently to strip in twenty -four hours in cold, and in forty-eight hours in warm, weather. Crutching. For stirring the soap-paste in the pans or frames, an instrument called a crutch is used, consisting simply of a board, to which a long wooden handle is Fio. 1 6. & Jacket view of Clutching machine. attached. For mixing various ingredients with soaps, several forms of steam-crutching machines are employed. ]?igs. 14, 15, 1 6 are representations of a form patented by STRUNZ (May 13, 1873, and April 23, 1878), and largely employed in the United States. It crutches soap completely within three minutes, and turns out an article of great smoothness. 72 SOAPS. Cutting and Barring. The blocks of soap when re- moved from the frames are marked off on the sides by means of a scribe, or dentier. This consists of a stick of hard wood, in which are fixed iron teeth. The distance of the teeth from each other is arranged according to the desired dimensions of the bars. The workman then, by means of a brass or steel wire directed in the track of the scribe-marks, divides the mass into slabs, which are afterwards subdivided into bars. FIG. 17. The operation of barring may be rapidly accomplished by machinery. Fig. 17 is an illustration of a soap-cutting machine much used in this country.* It consists of a fixed frame of woodwork, A A, and a movable lever-frame, B B, attached to A A by the centre-pin, c. The frames are wide enough to receive a slab of soap 45 inches long by 1 5 inches wide. This is placed in an inclined position, as * RICHARDSON and WATTS, " Technology," vol. i. pt. iii. p. 664. APPARATUS OF THE FACTORY. 73 shown by the dotted lines, resting on the bar, D, of the fixed frame, and against a number of wires forming part of the movable frame. "When the lever, G, is pressed down, the wires pass through the slab of soap, dividing this into regular bars, and when the handle is again raised up to the position 74 SOAPS. shown in the figure, the bars of soap are found on the- table, F, ready to be removed. Fig. 1 8 is an illustration of RALSTON'S champion soap- slabber, made by Hersey Bros., which is considered as effective as it is simple, and is little liable to get out of order. Fig. 19 exhibits an arrangement, by the same makers, by means of which the three operations of cutting, stamping, and spreading may be carried out. The frame of soap is cut into slabs either by the slabbing machine, of which Fig. 1 8 is an illustration, or else by the old way of slabbing by hand. In either case the slabs are taken one by one and placed on the cutting-table, shown on the right-hand side of Fig. 19. They are forced against a set of wires, and are thereby divided into bars by turning the handle seen on the right-hand side of the machine. They are afterwards pushed against the wires shown on the left-hand side of the machine, in a direction at right angles to the former move- ment, and are thus divided into cakes, the size of which is regulated by the distance apart of the wires. The stamping attachment consists of a framework, which is seen in the central portion of the machine, and which, by suitable means, is brought down at regular intervals as the soap passes through, so as to stamp upon each cake some name or simple device. It is intended to be used in cases where the soap is to be put on the market without being pressed. The spreading attachment consists of a series of wooden blocks of such size that, when the soap has passed through the second set of wires, each cake rests upon one of the blocks. These blocks are attached to strips of webbing in such a manner that, when the strips are pulled tight, there is a slight interval between the blocks. To receive the soap, the blocks are pushed close together. The racks for soap are laid so that the strips of which APPARATUS OF THE FACTORY. 75 they are formed lie in intervals left between the rows of blocks, and, after the soap has been pushed on the blocks by the action of the cutting portion of the table, a slight puU on the ends of the webbing separates the cakes, so that the racks can be lifted and placed for drying, with the cakes of ARRANGEMENT OF THE FACTORY. 77 soap in the best position for that purpose. The treadle, shown on the lower portion of the spreading attachment, is intended to lift each alternate block slightly before they are pulled apart, so that the cakes of soap will separate more readily. Stamping. The name of the maker, or the description of the soap, &c., may be put on by means of a stereotype plate and a mallet, or by a stamping machine, such as Pigs. 20, 27, 28, 29. By the HERSEY steam press (Fig. 20) a boy can turn out from 1800 to 2000 cakes per hour; a gentle pressure of the foot upon the treadle fills the cylinder with steam, causing the die to descend with great rapidity and power upon the cake, and the instan- taneous return of the lever raises it out of the die-box ready for removal. The cakes may vary in weight from a few ounces up to the largest sizes. ARRANGEMENT OF THE FACTORY. The following plans for a soap factory, which have proved convenient in actual working, are outlines of those given by DUSSAUCE and CRISTIANI :* The whole building is of an oblong or square form, divided into three compartments. i. The boiling-house, containing the kettles, frames, and lye-vats, is most conveniently placed in the centre of the factory and arranged round the large chimney. For a large business, two large boiling -pans answer in most cases, while two- other pans may be reserved for making the lyes. If the kettles are to be heated by open fire, or by superheated steam, the furnace is usually in the basement, while the rim * DUSSAUCE, " Treatise on the Manufacture of Soap," pp. 382-388 ; CRIBTIANI, " Technology of Soap and Candles," pp. 197-217. 78 SOAPS. of the kettle is extended above the first floor, at a height sufficient to facilitate the stirring. The lye-tanks are best made of cast iron, and are fre- quently inserted in the ground for the sake of economiz- ing space. They must be well covered best with cast-iron Fio. 21. lids. But the most "convenient arrangement is to have the tanks in an elevated position, so that the lyes can be drawn off. 2. Store-rooms. Adjoining the boiling-house, on one side, should be a warm store-room for the alkalies, and a second room, as cool as possible, for the fatty matters. FIG. 22. ARRANGEMENT OF THE FACTORY. 79 3. On the opposite side of the boiling-house may be the barring or cutting room and the drying and packing rooms. Description of Fig. 21 (pans heated by open fire) : A A, Factory building. B B, Kettles, c c, Fireplace. D D, Grate. E, General chim- ney. P F, Ash-pit. G G, Cisterns for waste lye. H H H, Vessels for oils and fats. / /, Cellars. L L L, Lixiviating vessels, situated above caustic lye-vats. M M (on right of illustration), Soap frames ; the upper part should be lower than the edge of the kettle, so that, after boiling, the soap may, by a shoot, be readily run into them. M M (on left of illustration), Store-rooms. N, Apparatus for poiudering crude soda. Description of Fig. 22 (pans heated by steam): A, Boiler. B, Fire-grate. c, Chimney. D, Dome from which steam is discharged through the pipe, F F, and the flat coil, E E, at the bottom of the kettle. F F, Kettles. G G, Waste-pipes. H H, Spent-lye pipes. 1 1, Spent-lye cis- terns. M M, Foundation of kettles. N N, Sheet-iron caustic- lye, vats, o o, Soap-frames. P, Barring-table. Q, Drying- room. R, Soap-moulding machine. The arrangement of a small factory illustrated in Fig. 23 is one that has been found efficient in its results and econo- mical in its working. It may be thus briefly described : A A are soap-pans, consisting of a wrought-iron curb, b being the cast-iron bottom. These pans, one of which only is shown in section, are set in brickwork, bound round with wrought-iron tie-bands, c is the cock for drawing off the lyas or spent alkali. d d the close steam-heating worms, or pipes, connected to the steam and waste mains, G and H. e e are the open free steam-boiling worms. //are the tie-bands for securing the brickwork round the boiler. So SOAPS. Both the pans have covers the same as shown on the pan not in section. Fm. 23. B B B are the cast-iron lye or alkali vats, having false bottoms, and being fitted with water-supply. C C G are the cast-iron pans for receiving the lyes or alkali solution from the vats, B B B. The lyes are taken from these pans by means of a pump, through a trough, to the soap-pans, A A. E E E E are the frames in which the soap is cooled, the side and end plates of which are taken off. F F are steam- jacketed pans for making toilet soap. They are fitted with free steam-boiling worms and all neces- sary connections, and are placed on a bench as indicated. G is the main steam-pipe from the boiler. II is the main waste steam-pipe. CHAPTER VI. CLASSIFICATION OP PROCESSES. DR. W. LANT CARPENTER'S classification is as follows:* a. Soaps produced by the direct union of fatty acids and caustic alkali, or by the decomposition of carbonated alkali by fatty acids. b. Soaps produced by the action of the precise quantity of alkali necessary for saponification upon a neutral fat, without the separation of any waste liquor, the glycerin being retained in the soap. This class includes (i) soaps made by the cold process ; (2) soaps made under pressure. c. Soaps produced by the ordinary methods of boiling in open vessels, working with indefinite quantities of alkaline lyes, the processes being controlled by the experience of the operator. These are again subdivided into (i) soft soaps, in which the glycerin is retained, potash being the base; (2) the so-called hydrated soaps, in which the glycerin is retained, and of which marine soap may be taken as a type ; (3) hard soaps, with soda for the base, in which the glycerin is eliminated, comprising three kinds curd, mottled, and yellow soaps. Dr. C. R. A. WRIGHT f classifies the various processes for the production of soap as follows : * SPON'S "Encyclopaedia," v. 1770. f Cantor Lectures, " Journ. Soc. Arts," May 1885. G 82 SOAPS. Group I. Fatty, or resinous, acids in the free state directly neutralized with alkalies (carbonated or caustic). Resulting soap devoid of glycerin. Group II. Saponification of fatty glycerides by alkalies, with retention of glycerin intermixed with the soap. In this group are the processes for making (a) soft soaps and marine soaps by open boiling; (b) soaps made by boiling under pressure ; and (c) cold-process soaps. Group III. Saponification of fatty glycerides by alkalies, with separation of glycerin. Group IV. Processes consisting of combinations of the foregoing. It will be seen from a consideration of the above that the methods may be arranged under three main heads viz., open boiling, boiling under pressure, and the cold process. i. General Process. The general method of preparation is the same for all the hard soaps, but there are variations in the details, more especially in the later stages. The following is an outline of the general method : i. Saponification, Pasting, or Killing the Goods. Usually the whole of the fat to be saponified is introduced into the boiler, and at the same time, for every ton, from 150 to 200 gallons of caustic lye, of sp. gr. 1.050 to 1.085 (10 to 17 Tw.), are added, and the whole is gently heated to ebullition. Lye stronger than sp. gr. 1.085 would, at this stage, hinder Saponification. After boiling for an hour and a half or two hours, a viscid emulsion, capable of being drawn out into threads, or ribbons, is produced. 2. Separation, Cutting the Pan, or Salting. To separate the imperfect soap produced, and to allow the spent lye, containing the glycerin, to be withdrawn, a sufficient CLASSIFICATION OF PROCESSES. 83 quantity of common salt is added, and this, dissolving in the liquid, causes the soap, which is insoluble in the saline solution, to rise to the surface, combined with a definite proportion of water. Thus separated, the soap is called grain soap. The spent lyes should contain no caustic soda, and no fat should be thrown up on adding to them a mineral acid. 3. Completion of Saponification or " Finishing" This part of the operation follows the removal of the waste lye, by pumping or drawing off. It consists in boiling up the granulated soap with fresh, stronger lyes, called strengthen- ing lyes, to complete the soap, and to bring it into what is called the close state. If curd soap is to be prepared, it is allowed to stand a while, that the lyes may subside, and then the operation is continued as in 5. If the grain soap contain impurities, such as iron soap, iron sulphide, &c., and if the quantity of water be not in excess after cooling in the frames, a marbled or mottled appearance results. 4. Fitting. The unrefined grain soap is apt to contain a proportion of lye entangled in it. To separate this, the curd is melted,, with the addition of water or weak lye, and foiled, so as again to produce a homogeneous compound. The mixture is allowed to stand for a considerable time about two days when a separation takes place into three layers, and the soap, which forms the middle layer, is then treated as in 5. 5. Cooling and " Cleansing." When the soap has re- mained in the pan a sufficient time to become partially cool, it is ladled out in buckets, or pails, or by other means con- veyed to the frames to solidify. Curd soap has then a rough, granulated texture, and is extremely hard, containing only about 20 per cent, of water. G 2 84 SOAPS. A properly fated soap will have a feathery texture, and contain about 30 per cent, of water. 6. Barring and Drying. The soap having become cold, the frames are removed, and a compact mass of soap, the size of the frames, remains. This is marked round by the iron-toothed scribe or dentier, the teeth of which are near or distant from each other according to the size of the blocks desired. The mass is then cut in the places so marked into slabs, and these slabs are subdivided into bars. These bars are then removed to the drying-room, and piled upon one another cross-ways, interstices being left for the circula- tion of air to facilitate the drying. MORFIT thus describes the general method pursued in the United States: 1. "The strength of the lye employed varies as the fat to be saponified is richer in olein or in solid constituents. The operation is commenced by pouring the lye into the copper to a third of its capacity. This is then heated to ebullition, and the oil is now run in. The reaction is such that a magma is immediately formed. The proper formation of this magma is considered to be the most delicate and important part of the whole process, and, if badly managed, a much greater quantity of lye is required to form the same weight of soap than would otherwise b& necessary. After the addition of the fat, the heat is- decreased by opening the doors of the furnace, and, when the mixture of fat and lye is complete, if necessary a further quantity of weak lye is added gradually, and with constant stirring during the addition so as to insure thorough con- tact. The mass should remain homogeneous \ the oil should neither rise to the surface nor descend to the bottom. " If oil should present itself, it is then necessary to add more strong or weak lye, according to the capacity of the caldron. On the other hand, if the lye is in excess, a further quantity of oil must be added, always stirring briskly upon CLASSIFICA TION OF PROCESSES. 85 any addition of new material. The operation requires from eighteen to twenty-four hours for completion, but it may be greatly accelerated by throwing in the scrapings or waste of soap already made." " An excess of soda is recognized by the liquidity and transparency of the paste. When oil is in excess, it rises to the surface. An excessive proportion of common salt in the soda also more or less interferes with the proper for- mation of the magma, and, if the proportion is very con- siderable, the use of soap scraps is indispensable." 2. " The next step in the process is the removal of the large quantity of water which was required for the complete saponificatioru This is effected by the addition of lye con- taining common salt, and by afterwards boiling the mixture for from fifteen to twenty hours, with constant stirring. When the mass opens in different places, the separation is complete. The fire is then withdrawn, and the whole is allowed three or four hours' repose, after which the settled waste, or spent, lye is drawn off. A further quantity of lye, charged with common salt, is now added, and the mix- ture is gently boiled, care being taken to remove from the sides of the caldron any adhering soap, so that all portions may come into contact with the lye. The mass now acquires more consistence, and, after some hours' rest, the settled waste is again withdrawn." 3. "A fresh quantity of lye, of sp. gr. i.io (20 Tw.), is now added, and the mixture again boiled, by which it acquires still greater consistence. After about three hours' further boiling, it is allowed to settle, and the spent lye is again drawn off. This operation is again repeated, with strong lye, constant stirring, and gentle ebullition, so that the whole may form a homogeneous mass. At this stage the soap begins to acquire firmness. " The boiling with lye several times successively serves 86 SOAPS. not only to complete the saponification, but to wash and purify the soap. That it may be perfect, it is necessary to repeat the operation four or five times. As soon as com- plete, the heat should be withdrawn, and the mass allowed to settle and become somewhat cool. It is then ready to be conveyed to the frames." 2. Saponification under Pressure. BENNETT and GIBBS, of Buffalo, N.Y., took out a patent in 1865 for making soaps by agitation under pressure. This method consists in agitating in a closed vessel, or boiler, fitted with a revolving shaft, or stirrer, the fatty matters with caustic or carbonated alkalies in solution in water while under heat and pressure, in such a manner as to cause a thorough mixing of the fats with the alkaline solution, and the production of a rapid combination of the fatty acids with the base. The pressure is 220 to 280 Ib.. per square inch, at the temperature of 350 to 400 F. (176.6 to 204.4 0.). At first, if carbonated alkali be used, it is necessary to allow some of the liberated carbonic acid to escape, so as to avoid undue pressure. A batch of soap may, in this way, be made in less than one hour. The patentees used from 30 to 33 Ib. of sodium carbonate at 48, and 100 Ib. of water to each 100 Ib. of lard, tallow,. or oil. The produce obtained is 200 Ib. of soap for every 100 Ib. of grease. The following advantages are claimed for this method : (i) Rapidity; (2) Quality improved; (3) Quantity in- creased; (4) Labour saved; (5) Fuel saved; (6) Cost of materials saved; (7) Completeness of saponification;. (8) Uniformity of results ; (9) Incorporation of glyce- rin ; (10) Admissibility of alkaline salts, instead of caustic- lye. DUNN'S method (p. 103) is also available for preparing. CLASSIFICA TION OF PROCESSES. 87 ordinary soaps under pressure. It differs from the pre- ceding in the employment of caustic, instead of carbonated, alkali, and of a lower pressure (20 to 65 Ib. per inch). 3. The "Cold" Process. By this method the high degree of heat necessary in the ordinary process is entirely dispensed with, and complete saponification is effected at temperatures lower than the ordinary boiling heat. The following is the description of the system as given by WILLIAM HAWES, the inventor : Two tons and a half of tallow, or any given quantity, are taken and melted at as low a temperature as possible, and then mixed, by mechanical means, with the quantity of lye required to completely saponify the fat. Ordinary soap- boiler's lye is used, preference being given to that made from the strongest and purest alkali. The saponification of the tallow, or other fat, may be ascertained by its absorp- tion or combination with the lye, care having been taken, in the first instance, to use a sufficient quantity of the lye. Twenty gallons of lye, of sp. gr. 1.125 (25 Tw.), are required for every 100 Ib. of tallow, but the proportion varies according to the nature of the fat or oil* employed. An ordinary soap-pan may be used as the combining vessel, with the addition of a stirrer to facilitate the admixture of the tallow and the lye. Figs. 8 and 9 (p. 64) will convey an idea of the apparatus. For the quantity of fat mentioned above, if the cylinder is used, it should be about 6 feet in diameter and 12 feet in length. When it has been charged with fat, motion is communicated to the machinery, and the lye is then gradually added. In a short time the ingre- dients will be thoroughly mixed, but the agitation must be continued for about three hours, or until saponification appears to be complete. During the process there is a con- siderable evolution of heat. After from one to four days. 88 SOAPS. according to the quantity, it is hard enough for use. As the value of the process chiefly depends upon the lowness of the temperature at which the saponification is effected, it is desirable to transfer the contents of the cylinder, as soon as thickening occurs, to an ordinary soap-pan, where the opera- tion may be finished, either by conversion into yellow soap with the addition of rosin, or into mottled or white soap by finishing lyes in the usual way. The cold process is very suitable for the manufacture of soap on a small scale, and in such case the mechanical stirrer can be dispensed with. The advantages obtained by this process are economy of cost and time, retention of the glycerin, and, when per- fumes are introduced, the avoidance of loss which a high temperature naturally causes. The disadvantages are the liability of the product to con- tain an excess of alkali, and the necessity of having very pure materials, because in no part of the operation is there any opportunity of getting rid of objectionable impurities. If the alkali contains too much chloride, it will be necessary to add a proportion of cocoa-nut oil in order to effect the saponification. It is also not uncommon to find, owing to incomplete saponification, that the product contains both unsaponified fat and free alkali. "We shall consider the various commercial soaps produced by these methods, or by modifications of them, in the following order : Household, domestic, laundry, or plain soaps. 1. Curd, or white, soap. 2. Genuine mottled soaps. 3. Castile, Marseilles, Venetian, or olive-oil soaps white and genuine mottled. 4. Artificially mottled soaps blue, grey, and red. 5. Yellow, or rosin, soap. CLASS1FICA TION OF PROCESSES. 89 6. Cocoa-nut-oil, marine, or liydrated soaps. 7. Silicated soaps. 8. Sidphated soaps. Toilet, or fancy, soaps. Medicinal, or pharmaceutical, soaps. Oleic-acid, or red-oil, soaps. Soft soaps. Industrial soaps. CHAPTER VII. HOUSEHOLD, DOMESTIC, OB LAUNDBY SOAPS. HAKD soaps are made with non-drying oils, or solid fats and soda. Their hardness is in proportion to the amount of stearic and palmitic acids which they contain. Soda soaps made with drying oils, such as linseed, are pasty and easily liquefied by a small quantity of water, and approach to the character of soft soaps made with potash. The most im- portant kinds of hard soaps arc those made chiefly with tallow, as in England and other Northern countries, and olive-oil^soaps, as made in Southern Europe. i. Curd, or Wliite, Soap. A. ENGLISH METHOD.* The fatty materials used for the production of hard soaps in this country are tallow, lard, palm oil (well bleached), and cocoa-nut oil, or mixtures of these in almost any proportion. The pan used is the ordinary open boiler (pp. 62, 63, 66), heated either by fire or by closed steam-pipes. From 10 to 14 cwt. of tallow are required to produce i ton of soap. i. The pan having been charged with the fat, weak lye of specific gravity about 1.040 is added (the proportions are * Founded on GOSSAGE'S description KICHAEDSON and WATTS, ' Technology," vol. i. pt. iii. p. 680. HOUSEHOLD SOAPS. 91 about 200 gallons of such lye to i ton of the fat), and the whole is heated, by injection of steam, or otherwise. If the process goes on properly, the fatty matters soon com- bine with the lye, producing a uniform milky emulsion, from which no watery particles separate on cooling. If such an emulsion is not produced, water, or weaker lye, is added, and the boiling is continued till the combination is complete. At this stage, the application of the tongue shows that the taste of the alkali has passed away, or, in technical language, the lye is killed. Repeated additions of stronger lyes are made, and the boiling is continued till the presence of free alkali becomes evident to the tongue. It is then necessary to introduce more fat, followed by stronger lyes, but with care that, at this stage, the alkali shall not be in excess. 2. The imperfect soap is now separated by the addition of common salt, and, after a few hours' subsidence, the spent lyes are withdrawn from under it. This spent lye contains a portion of the glycerin of the fat, together with sodium sulphate (from the alkali used) and common salt. 3. The next stage of the process consists in the*addition of weak lye to the imperfect soap, and subsequent^boiling to bring the contents of the pan into a state of homogeneous mixture, called the close state, as distinguished from the granulated condition in which the soap separated at the end of the first operation. Stronger lyes (of about sp. gr. 1.160) are now added till the mixture has a strongly alkaline taste. Sufficient com- mon salt is then thrown in to cause the separation of the soap, and the mixture is boiled for several hours, so that the whole of the fat may be combined with the alkali.* * This point is well known to the experienced workman by the consistence of the compound. If a little of the mass taken out on a -92 SOAPS. In this process, attention has to be specially given to the separation of the alumino-ferruginous impurities of the lye, which, if not removed, tend to discolour the soap. Their removal is effected by boiling the soap several times with fresh weak lye or water, applying gentle heat, covering the caldron, and allowing time (one to two or three days, ac- cording to the quantity of the materials) for the darker- coloured soap, or nigre, to settle. The upper stratum of white soap is afterwards ladled out into the cooling frames, -curd soap being generally too thick to pump. In England by far the greater quantity of curd soap produced is made from tallow, or mutton suet, and soda only. Soap thus made is, however, inconveniently hard and difficult of solution. Hence, some manufacturers re- place one-fourth of the tallow by as much lard, or olive oil, obtaining thus a soap of superior quality, and less liable to change by exposure. Lard has this advantage over olive oil that it does not detract from the whiteness of the soap. The advantages gained by the use of lard and olive oil with tallow are thus summed up by MUSPRATT :* " The soap remains unaltered for a longer period ; it does not emit the -disagreeable odour of tallow ; and the saponification is more perfect, as the excess of olein in the lard, or oil, compen- sates for the large amount of stearin in the tallow, thus inducing a more ready and perfect union of the alkali and fatty acids." English curd soap is much used in Yorkshire by cloth trowel is squeezed between the finger and thumb, it will still have a greasy feeling if not thoroughly finished ; but if the saponification is complete, it will readily separate from the skin in hard scales. Or a portion may be decomposed by an acid, and, if the saponifica- Aion is complete, the separated grease is wholly soluble in boiling .spirits of wine, but not otherwise. * " Chemistry/' ii. 879. HOUSEHOLD SOAPS. 93 manufacturers, and at Nottingham in the bleaching of lace and stockings. B. GERMAN METHODS.* (a) The old method of preparing hard soap formerly practised in Germany is of great interest, historically and chemically, and a short description of it may therefore find place here. i. The crude tallow is saponified with potash lye pre- pared from potashes causticized by lime in the usual manner. The first lye has a strength of 20 B. Soon after the boiling has commenced, an emulsion is formed, and, on continued ebullition, the mass becomes clear, having the appearance of a thick syrup, indicating that the whole of the fat has entered into combination with the potash. Turbidity may be due either to excess or deficiency of potash, or to the presence of lime. On treatment of a few drops of the mixture with pure rain-water, a continuance of the milkiness indicates unsaponified fat or the presence of lime. If the latter is the cause, it is removed by the addition of a car- bonated alkali; when there is unsaponified fat, more lye must be added and the boiling continued. The milkiness due to excess of alkali disappears on addition of water. 2. "When the clear solution will flow from the spatula in an unbroken stream of the consistence of treacle, and will solidify to a thick jelly when placed on a cold stone, the product is ready for the salting process. This consists in throwing salt into the pan and boiling up with the solution of soap. " Double decomposition " takes place analogous to that ensuing between silver nitrate and sodium chloride (see example (e) (2), p. 51), thus: {.} + Potash soap Soda soap * RICHAUDSON and WATTS, " Technology," vol. i. pt. iii. p. 674. r UNIVERSITY 1 94 SOAPS. This reaction, in conjunction with the excess of common salt, causes the separation of the soda soap and the forma- tion of the under-lye. The soap, insoluble in the brine, coagulates into a whitish mass of small flocks. After resting for some time, the soap is scooped out into the cooling- frame. The soap is obtained quite clean, even from very impure materials, being washed by the salting process. The impurities from the salts in the ash employed, and from the action of the lye on the membranous parts of the crude tallow, are all found in the under-lye. When all the soap has been taken out, the lye is removed, and the soap afterwards replaced in the clean pan, with an addition of fresh weak lye. The mass is boiled, and a clear solution, as in the first boiling, is obtained, containing chiefly soda soap, but with an admixture of potash soap from the fresh lye. Salt is again added, and the boiling continued. The heat is then removed, the contents of the pan allowed to rest, the soap scooped out again, and the under-lye emptied out. After this, if crude tallow has been used, about three or four more boilings must be made before the soap is com- pletely saturated with alkali. Less salt is required at every fresh boiling, because there is gradually less potash soap to be decomposed. A less number of boilings will be sufficient if purer tallow is employed. 3. The mass is then boiled clear, and if the soap appears satisfactory, the fire is withdrawn, and the product is skimmed off and transferred to the mould. 100 Ib. of tallow will produce from 150 to 155 Ib. of curd soap, weighed as soon as cut. Dr. C. K. A. WRIGHT has pointed out * that, in all pro- * Cantor Lectures, " Journ. Soc. Arts," May 1885. HOUSEHOLD SOAPS. 95 bability, hard soaps were first manufactured in this way, the use of wood ashes and fatty matters for making potash soaps of a crude character being the earliest traceable kind of soap-making, and that this mutual decomposition is avail- able for the manufacture of hard soda soaps under circum- stances when caustic soda is less readily obtainable than potashes e.g., where wood ashes are available in districts a long way from commercial centres where soda ash and caustic soda can be bought. This old method, brought to great perfection by long experience, enabled the manufacturer to prepare an excel- lent soap, but the increasing price of potash and the cheapening of soda have caused it to be nearly abandoned for the modern method of saponification by soda alone. (6) Modern German Method* The boiling is conducted as follows : The pan is charged with 190 gallons of soda- lye of 13 B., and 2000 Ib. of the best melted suet. The mixture is gently boiled for two hours after it has be- come milky; then the heat is withdrawn, two hours' repose is allowed, and the lye is run off. Boiling with fresh lye follows, and when the soap, on pressure between the fingers, forms clean solid scales, a few buckets of lye are thrown in to cool it, and again drawn off after settling for a while. The soap is again boiled up with 9 or 10 gallons of fresh lye, and, when fusion is complete, a trial of the paste is made with the spatula. If it runs from the lye, water is added ; if it does not run, it must be boiled a little longer, adding a bucket of water containing a third of its weight of common salt, in order to effect the separation of the soap. When this separation appears to be complete, after settling for about an hour, the liquid, which contains the greater part of the lye remaining from the first boiling, * RICHARDSON and WATTS, " Technology," vol. i. pt. iii. p. 678. 96 SOAPS. generally of a deep bottle-green colour, is drawn off. About eight buckets of water are now added, and the boil- ing continued till the incorporation is complete. If, on exa- mination, the soap runs from the water, more water must be added, in small portions at a time, till the running ceases, and the pasty mass, when shaken, trembles like a gela- tinous compound. The operation is finished by well boil- ing the contents of the pan, and, unless the soap has a bluish tinge (in which case it should have another wash- ing), the heat is then withdrawn, the pan covered up, and the whole left at rest for a day or more. The soap is then ladled into the frames. 2. Genuine Mottled Soap English or London. The cheaper fatty matters are usually employed for this description of soap, such as bone-fat, kitchen-stuff, inferior tallow, &c. Lyes prepared from crude sodas are preferred, because the impurities which they contain materially help in the formation of the strike, or mottled appearance. The process, up to the third stage, is conducted in a manner similar to that adopted for curd soap (p. 90). After this, instead of allowing the total subsidence of the nigre, the operator inserts a rake, breaking the paste in all directions, and then, thrusting it downwards to the lye, he draws it rapidly upwards so as to cause some of the lye to rise and spread over the surface. As it descends through the viscid mass, the dark-coloured nigre leaves veins or marks which, in the cooled soap, remains as mottle. When ready for cleansing into the moulds, the soap is in a gelatinous condition, interspersed throughout with lye. To judge of the proper condition for cleansing requires the experienced care of a good soap-boiler. If iron frames are used, the ends of the bars have often no marbling, owing to the too rapid cooling of the parts in contact with the metal, and hence HOUSEHOLD SOAPS. 97 some makers prefer to use wooden frames for mottled soap. 3. Castile, Marseilles, Venetian, or Olive-oil Soap White and Mottled. The process for the manufacture of this soap does not differ greatly from that of other hard soaps. The fatty material used is olive oil, often with the addition of poppy, cotton-seed, or other seed oil, as the soap made from olive oil alone is inconveniently hard. Of course only the cheaper kinds of olive oil are employed, the most suitable being those which contain the largest proportion of stearin, and which, consequently, most readily solidify in the cold. The operation may be described in four stages : i. The preliminary boiling, or pasting (empatdge) ; 2. Cutting the pan (relargage) ; 3. Clear-boiling (coction) ; and, in the case of mottled soaps, 4. Mottling, or marbling (madrage). i. Pasting. The lye, of 8 to 11 or 12 B. (the latter when the oil is thin, the former when it contains more solid matter) is either run into the boiler, or prepared therein by mixing weak and strong lye till the desired strength is reached. It is necessary to be particular about its strength, because, if too strong, or if the quantity of lye be excessive, the solution of the soap formed is hindered, and the first action of the oil and alkali can only take place rapidly and completely when the soap remains dissolved in the lye. This lye should also be, for this stage, as free as possible from common salt (soft lye) ; hence the purer kinds of soda are taken for the first lye, and afterwards soda containing sodium chloride (salted lye). The oil is run in at once with stirring, when the lye has reached the boiling point. An emulsion is soon produced, 98 SOAPS. and any excess of oil or of lye is then noticed and treated in the manner already described (pp. 84, 85, 91, 93). As soon as the mass has become perfectly uniform, and has acquired the consistence of soap, the heat is withdrawn, and the salt- ing process begins. 2. Cutting the Pan, or Salting. This operation is per- formed as detailed previously (pp. 82, 85, 91, 93), or by the use of salted lye at 25 to 30 B. The solution of salt, or the salted lye, is thoroughly mixed with the contents of the boiler. The soap, insoluble in the salt solution, separates in flocks from the excess of water, and by continued boiling, it is at length brought to a granular or curd-like condition. At this point the heat is removed, time is allowed for the lye to deposit, and the liquor is afterwards drawn off. 3. Clear-boiling, or Clarifying. The lye now added must be so strong that the soap will not dissolve in it. Its strength is accordingly 18 to 20 B.,and about 10 percent, of common salt is added. According to DUSSAUCE, it is preferable to begin this part of the process with soft lyes that is, lyes free from salt. After boiling till the caustic properties of the lye are lost, the liquor is drawn off and replaced by a similar lye, and it may be necessary to repeat the treatment with fresh lye several times, till the soap has greater consistency, and the alkalinity of the lye remains unaffected. This shows that the soap is completed, as it will take up 110 more alkali. The mixture no longer boils smoothly, but in jerks, and the curd, when pressed against the palm of the hand, forms a firm and granular mass, which does not adhere to the skin. Up to this point the details of the process are nearly the same for both white and mottled Castile soap. If a white soap is to be produced, the impurities, such as iron compounds, &c., must be separated by further treat- ment as in . HOUSEHOLD SOAPS. 99 3a. Liquefying. The last lyes having been drawn off, the soap is again treated with weak lye, and heated gently, so that the heavier, dark-coloured soap, or nigre, may sink below the lighter mass of purer soap. After settling for a sufficient time in the covered boiler, the upper stratum is ladled off into the frames, and is sometimes, as an additional precaution, poured into these through sieves, so as to keep back casual impurities. 4. Mottling. If, instead of a white soap, the object is to produce a mottled soap, impure soda, containing sulphides, is preferred for the lye, and a quantity of ferrous sulphate (green vitriol), about 8 oz. for each cwt. of oil, is added at the end of the preliminary boiling. This is at once precipi- tated, partly as iron oxide and sulphide, and partly as an insoluble iron soap. In consequence of this addition, and also from the presence of iron and sulphur in the lye, and of ferruginous matters from the pan, the curd obtained at the end of stage 3 has a uniform slate colour. If this were allowed to remain, the effect would not be pleasing, but, instead of directing his endeavours to exclude these impuri- ties, as in the case of the white soap, the soap-maker con- ducts the operation in such a way as to preserve and arrange them, by diffusing the colour in veins, in order to give a marbled, or mottled, appearance. When the proper con- sistence of the soap has been attained, the mass is worked about with rakes, so as to bring the lower and darker- coloured parts of the curd to the top. When this has been sufficiently done, the viscid soap is transferred to the frames, where, in about a week or more, according to the quantity, it cools down to mottled soap. By varying the proportion of iron sulphate added, a tint is produced of a lighter or darker hue. By exposure to the air, the iron gets oxidized to the state of sesquioxide, and a reddish tint, called manteau Isabette, is diffused over the bluish mottled mass. H 2 ioo SOAPS. It is thus apparent that in mottled soap the veins and patches of heavy, insoluble, coloured compounds are present because, by special manipulation, they have been intention- ally prevented from subsiding, and by the conveyance of the soap to the frames in so viscid a condition that the downward trickling of the coloured impurities should pro- ceed so slowly as only to intensify the desired appearance, and not subside altogether. It is evident also that, if a soap so prepared were thinned by admixture with water, the impurities would more readily subside, and that the veining or mottling would be greatly diminished or entirely pre- vented. Hence, a genuine mottled soap cannot contain more than 33 or 34 or, at mosfc, 36 per cent, of water. Hence, also, as a mottled appearance was formerly a special characteristic of " Castile " soap, and as this was essentially a good soap, a mottled or marbled character came to be regarded as a sign of excellence. So far was this belief carried, that it used to be said there was no need to analyse a marbled soap, as it must necessarily be genuine.* This, however, is now by no means the case. 4. Artificially Mottled Soa2^s Slue, Grey, and Red. BLAKE and MAXWELL'S process may be used to produce these soaps. Two soap-pans are required. In one of these a known quantity of tallow, or bleached palm oil, or a mix- ture of 80 per cent, of cocoa-nut oil, 14 per cent, of tallow, and 6 per cent, of lard, is boiled with a quantity of soda lyes, carefully calculated by means of the second table on p. no, and the hydrated soap thus formed is transferred to the other pan, in which a soft curd soap has been prepared from fatty matters and lyes, as calculated from the first table * KAMPEL'S " Method of Assaying Soaps," quoted in WATT'S "Art of Soap-making," p. 209. HOUSEHOLD SOAPS. 101 on p. no. The mottle is produced by adding to this soap, when in a finished state, colouring matter to impart the desired colour, and in about half an hour after the soaps and colouring matter have been thoroughly incorporated, the soap may be transferred to the frames. For the best descriptions of mottled soaps, the weight of fatty matters used to produce the hydrated soap amounts to from one- fourth to one-half of the fat used to produce the soft curd. For cheaper descriptions, the hydrated soap may be in- creased till the proportion of fat in the hydrated soap amounts to from two-thirds to one and a half times the weight of fat in the curd soap. Another way is to prepare a " fitted " soap from the fatty mixture containing cocoa-nut or palm-kernel oil in one pan, and to remove it from the nigre to the second pan. Here, for every 1000 Ib. of soap, are added 250 Ib. of sodium silicate, and the whole is thoroughly incorporated by boiling, until the experienced workman judges that the proper condition for mottling has been attained. The colouring matters mixed with water are then sprinkled into the pan, and, after boiling for a few minutes, the mixture is transferred to the frames. The colouring matters are for blue, artificial ultramarine, 5 to 10 Ib. per ton; for grey, manganese oxide, i to 3 Ib. per ton ; and for red, vermilion. 5. Yellotv, or Rosin, Soap. The distinctive yellow tint of this soap is due to the pre- sence of a considerable quantity of rosin. Several methods are followed in its preparation. i. The ingredients are common fat, or inferior tallow, or bone-fat, or red oil, palm oil, and rosin. The proportion of rosin in this mixture should not exceed one-third of the fat ; if equal parts are used, the soap produced is soft and dark 102 SOAPS. coloured. It is usual, in this country, to partially make- the palm oil or tallow soap, and, when the saponifi cation is nearly complete, to introduce, with the last charge of lye, the coarsely powdered rosin. The contents of the copper are- then well mixed together and boiled for some hours, generally with open, or wet, steam, adding more lye whenever neces- sary, to preserve an excess of alkali till the completion of the saponification. This point is ascertained by cooling a portion of the soap and noting whether it then has a proper con- sistence and the proper grain, and whether it will wash without leaving a film of rosin on the hands. The lyes having been drawn off, the paste is next purified, or fitted, by boiling up with weak lye (about 8 B.) in order to facilitate the deposition of the impurities. After resting for a while, the lye is again removed, and boiled once or twice more with still weaker lye. After a long interval from a day or two to a week, according to the size of the pan there is a separation into three layers : a scum, OT/ob, uppermost, the nigre at the bottom, and the pure soap (or neat soap, as it is called) in the middle. The scum is next taken off, and the soap is cleansed i.e., the neat soap is removed into the frames. The dark-coloured nigre may be afterwards used for mottling, or for inferior sorts of yellow soap. 2. If tallow, or other grease, be employed, without any palm oil, the following procedure is sometimes adopted :* 2000 Ib. of the fat, 600 Ib. of rosin, and from 150 to 175 gallons of soda lye of specific gravity 1.075 * I ' I 5 ( I 5 to- 30 Tw.) are run into the boiler, and, when the whole is melted, it is boiled, with continued stirring to prevent the rosin adhering to the bottom and sides of the boiler. If there is a great swelling of the mass, the heat must be * MusrBATi's " Chemistry," ii. 880. HOUSEHOLD SOAPS. 103 lessened. The first boiling should be continued not more than two or three hours, on account of the ease with which the combination is effected. After six hours' repose the spent lye is withdrawn, more lye is run in, and the whole is again boiled for about three hours. Another repose of six hours is now allowed, the spent lye is again drawn off, and fresh lye afterwards added. These boilings, c., are con- tinued day after day till the proper consistence, which is ascertained in the manner already described (pp. 91, 95), has been attained. If the soap is not yet satisfactory, it is requisite to add more lye, and to re-boil \ but if the examina- tion shows it to be finished, it is boiled up briskly, the heat is withdrawn, about 6 gallons of lye are thrown in to cool the soap, and two hours afterwards the liquor is run off. From 12 to 16 gallons of water are now added, and the whole is again briskly boiled, stirring constantly till the soap is melted. A little of the boiling paste is now removed on a wooden spatula, and, if it run clear from the lye, more water is added, and the boiling is continued. If it should not run, too much water has already been added, and about a gallon of a strong solution of salt or of lye must be thrown in. . 3. Another and, as some think, better plan* is to make a rosin soap, or, more accurately, an alkaline, resinate, and a tallow soap separately, and to mix the two in the boiler, where they are kept in a state of ebullition for some time, until a uniform mixture results. Salt is then added, and, after treatment similar to that already described, the soap is ready for the frames. 4. Dunn's Method, t Into each of the ordinary coppers, a circular ring of ij-inch pipe, perforated with * RICHARDSON and WATTS, " Technology," vol. i. pt. iii. p. 686. f Quoted in ibid. 104 SOAPS. holes, is fixed just far enough above the bottom to allow the free movement of a stirrer beneath it. This circular ring of pipe is supplied with air from a cylinder blast, or other suitable forcing apparatus, being connected therewith by means of a pipe which passes to the top of the copper, where it is furnished with a stop-cock and union- joint, for the purpose of connecting, or disconnecting, the parts of the pipe within and without the pan. For a clear yellow soap, 90 gallons of lyes of sp. gr. 1.14 made from strong soda-ash are introduced into the pan. The fire is kindled, and about 2050 Ib. of grease are added, and, as soon as the lye boils, the blast is set in action. A brisk fire is kept up, so as to maintain the materials as near ebullition as pos- sible. When the lyes are exhausted, more lye is gradually added until the fatty matter is killed. 550 Ib. of fresh rosin are then added, a bucketful at a time, with more lye occasionally, until 300 gallons, of the strength above mentioned, have been used. The blast is kept in action the whole time if the fire draws well ; if not, it is advisable to stop the blast for a while before adding the rosin, to allow the mixture to approach ebullition. "When the whole of the rosin is melted and completely mixed with the soapy mass, and the strength of the lyes taken up, the blast must be stopped, and a brisk boiling given. The whole is then left to rest, that the spent lyes may separate and settle. These are drawn off, and the soap brought to strength on fresh lyes, as in the ordinary process. During the operation of the blast the soap must be kept in what is technically called an open or grained state, and for this purpose salt, or brine, is to be added when necessary. Experience proves that it is better not to make a change in the lye during the operation of the blast where lye of the strength mentioned is used, but if weaker lye is em- ployed one or more changes may be made. It is also found HOUSEHOLD SOAPS, 105 desirable that the soap should be kept in a weak state during the action of the streams of air through the materials; otherwise the soap is apt to swell up from the air hanging in the grain, and this is troublesome to get rid of, requiring long boiling. If dark-coloured materials are used, it is well to keep the blast in operation three or four hours after the rosin is melted, provided the soapy mass is kept weak and open or grained. When a charge is to be worked upon a nigre, such nigre should be grained, and the spent lye pumped, or drawn off, as usual, and the fresh charge added in the way mentioned above, using less or more lye in proportion to the quantity and strength of the nigre, and taking care not to turn on the blast until there is sufficient grease present to make the nigre weak. 5. Meinecke's Method.* This is an attempt to pro- duce rosin from turpentine in the soap-pan which shall be at once available for making soap. The rosin is added, as it occurs in white turpentine, and this, on boil- ing, gives off its volatile oil, which has to be condensed and saved as an incidental product, thereby decreasing- the expense of the soap. To condense the spirit of tur- pentine, the soap-pan must be furnished with a still-head and worm for cooling the vapours. The operation is as follows : 1000 Ib. of white turpentine are melted in the copper by steam, with 800 Ib. of tallow, or inferior fat, and when the mixture reaches 108 F. it must gradually receive, with constant stirring, 800 Ib. of caustic-soda lye containing 30 per cent, of dry soda. The union of the materials is very rapid at this temperature ; the acids of the rosin and of the fat are completely neutralized by the alkali, and converted into liquid soap. To promote the * KICHARDSON and WATTS, "Technology," vol. i. pt. iii. p. 687. io6 SOAPS. vaporization of the essential oil of turpentine, salt or brine is then added, the still-head luted to the copper and con- nected with the worm, and the contents of the copper are boiled up. The steam and oil of turpentine pass over, and are condensed. When no more oil distils over, the soap is finished in the ordinary manner. 6. Jennings' Method. To curd soap prepared with tallow or oil and caustic alkali, in the usual manner, is added about 25 per cent, of colophony, 2 to 4 per cent, of sodium carbonate, and about i per cent, of aluminium sulphate, common alum, or other double salt of alumina. The mix- ture is boiled with water till perfect combination is effected. To prevent the rosin from precipitating, a small quantity of dilute sulphuric acid ( i part acid to 9 parts water), amount- ing to about 2 per cent, of the fats and rosin, is stirred into- the mixture. The composition of primrose soap by analysis is :* South England. North England. Fatty acids . . . .62.3 42.66 Soda as soap . . . . 6.7 in other forms . . o.o Neutral salts . . . . 0.2 Silica o.o Water 32.8 5-41 1. 21 0-55 0.94 50.40 Total . . . 102.0 ... 101.17 Cost of an Ordinary Yellow Soap. The following calcula- tion indicates, approximately, the cost of production of i ton of ordinary yellow soap at the prices quoted : s. d. Tallow ii cwt. at (say) 255. - . . . . 13 15 o Kosin 3 cwt. at (say) 55. . . . . . o 15 o Alkali 2 cwt. 3 qrs. (58 at \\d. per unit), 5$. 6d. o 15 i.J, Labour, &c .300 Total 18 5 ii * CARPENTEK SPOK'S "Encyclopaedia," v. 1796. HOUSEHOLD SOAPS. 107 6. Cocoa-nut-oil, Marine, or " Hydrated " Soaps. The use of cocoa-nut and palm oils in the manufacture of soaps has increased to a great extent since artificially pre- pared soda came into general employment. This is well shown by the following statistics : Imports of Year. 1820 1830 1840 1850 1860 1870 1880 1881 1882 1883 1884 1885 1886 1887 The behaviour of cocoa-nut oil differs from that of the other fatty matters in the process of saponification. It is difficult to make the saponification begin, but, once started, it goes on with great rapidity, the mixture swelling up enormously. The resulting soap can only be separated from solution in the copper by very strong solutions of common salt. The reason of this is that cocoa-nut-oil soap is soluble in dilute brine, and is, consequently, avail- able for washing in salt water. Hence it is called marine soap. If, however, cocoa-nut-oil soap be prepared in this way, it contains very little water, and becomes so hard that it cannot be cut with a knife. The usual method is there- fore not followed in making this soap. As weak lyes will not saponify cocoa-nut oil, the operation is commenced by employing strong lye, of about 20 B. ; and, by having the Palm Oil. ^x Cocoa-nut Oil. cwts. cwts. 17*456 8,353 213,476 8,534 315*503 42,428 447*796 98,039 804,326 194,309 868,270 198,602 1,026,378 317,828 819,749 248,476 801,545 136,087 743,5*2 210,874 825,822 245,695 898,481 185,971 993.091 156,667 966,536 183,766 io8 SOAPS. lye pure and perfectly caustic, the use of salt in cutting the pan is dispensed with. Saponification is also aided by the use of potash lye with the soda. Pure cocoa-nut-oil soap hardens much too quickly to exhibit any distinct formation of curd, and is, consequently, incapable of marbling by itself. It is very white, translu- cent like alabaster, exceedingly light, and forms a good lather, but always possesses a more or less offensive odour. Cocoa-nut oil has the very important property of com- bining with more water than can ever be incorporated with tallow soap. It really produces no greater quantity of actual soap than an equal weight of tallow, but it can easily be made to absorb one-third more water or lye, and, at the same time, shows no want of consistence or softness, as would be the case with other soaps. Cocoa-nut oil is not usually employed alone, but is added to other oils for the purpose of producing quickly solidifying soaps containing a large proportion of water, which could not be obtained from tallow, &c., alone. It is even possible* to prepare soap on a large scale in a few hours without salt, und almost without fire, by the use of cocoa-nut oil and tallow, together with strong lye, by merely warming them sufficiently to melt the fat, and keeping them constantly in a state of agitation. Soap prepared in this manner has a finer appearance, and sets in the mould, so that it can be cut. It contains, however, nearly all the water of the lye, as there is very little evaporation in the pan, together with the entire amount of foreign salts, and, in the fresh state, has less resemblance to soap than to stiff dough, taking deep. im- pressions from the thumb, and having a slimy consistence when squeezed between the fingers. When dried for a length -of time, there is a copious efflorescence of salts, but it finally * RICHARDSON and WATTS, " Technology," vol. i. pt. iii. p. 683. HOUSEHOLD SOAPS. 109 acquires the consistence of ordinary soap. " Marine" soaps are often met with containing 70 per cent, of water. If equal parts of cocoa-nut oil and tallow are used, the smell of the former is scarcely perceptible in the soap. The boiling of such a mixture is continued till a sample exhibits the proper consistence under the thumb. Under the same conditions, tallow could not be saponified alone, but the sap onin cation begins with the cocoa-nut oil, and the presence of the cocoa-nut-oil soap carries on the saponification of the tallow. Blake and Maxwell's Process. In this process it was proposed to form a soap by combining saponified materials, in the state called soft curd, with a hydrated soap, or neutral soap not deprived of its water. The curd soap may be prepared in the usual way, or it may be made, as preferred by the patentees, by means of soda lyes of the strength and in the quantity mentioned below, so as to obtain a soft curd better adapted for com- bining with a neutral soap. The soap thus formed may be separated from the water, or excess of lyes, by means of salt, or concentrated lyes, in the usual way. The rosin soap is recommended to be prepared as follows : About one-third of the rosin to be used is mixed with a small quantity of fatty matter, equal to from 6 to 10 per cent, of the rosin. One-third of the lyes is also mixed with the rosin, and the mixture is slowly melted. The remainder of the rosin is then added gradually, by small portions at a time, as the added portions melt, and, when the whole is melted, the rest of the lye is introduced. Increased heat is then applied till the mixture boils, and this is continued for about three hours, or till saponification is complete, when the mass will have the consistence of thick glue or paste. The hydrated soap is prepared in another pan from any no SOAPS. of 'the fatty matters mentioned below, either singly, or in combination, and to it are transferred the soft curd, rosin, and tallow soaps. After boiling together for about two hours, the soaps will become thoroughly united, and the compound soap will have assumed an appearance similar to ordinary soap in process of finishing. The soap should be removed to the frames within two or three hours after it is finished, and the frames should be covered so as to retain the heat as long as practicable. The following table shows the oily and fatty matters which may be used for making the soft curd, and the strength and quantity of the soda lyes deemed most suitable for speedily effecting their saponification. The weight of lye required to saponify each 100 Ib. of fatty matter may be found by dividing the number of degrees by the strength of the lyes applicable to each kind of fat. Fat to be used. Quantity of Lye in Degrees BaumtS. Strength of Lye. Degrees Baume". 100 Ib. tallow require . ,, palm oil ,, ,, tallow olein ,, ,, rosin ,, 3,800 3,200 2,800 2,700 I4-I5 16-18 16-18 16-22 The fats that may be used for making the Jiydrated soap, and the quantity and strength of the lyes required for saponification, are the following : Fat to be used. Quantity of Lye in Degrees Baume. Strength of Lye. Degrees Baume". IOC ) Ib. tallow reqi cocoa-nut oil palm oil lard tallow olein olive oil rape-seed oil linseed oil lire 3,800 4,100 3,200 3>4QO 2,800 3,000 2.400 2,400 11 16-20 18-22 1 8-22 16 24-28 24-28 HOUSEHOLD SOAPS. in 7. Silicated The use of sodium silicate as an ingredient of soap was first proposed by Mr. SHERIDAN in 1835. It has been stated * that the value of silicated soaps was first publicly and officially recognized at the International Exhibition of London in 1862, when a prize medal was awarded to "W. Gossage & Sons, of Widnes ; but we find the following paragraph in the " Heport of the Juries, Exhibi- tion, 1851 " (p. 607) : "The soap called silicated soap, now manufactured extensively at Liverpool, is formed by mixing a basic silicate of soda (made by boiling powdered flint in a close vessel, under pressure, with caustic soda) with hard soap in a melted state. It appears to possess remarkable detergent properties, but is liable to feel gritty in the hand." Though they may be useful, therefore, for household pur- poses, they are unsuitable as toilet soaps. Sheridan's Process. The method of preparing the sili- cate is described on p. 27. The silicate is incorporated with the soap, previously prepared in the ordinary manner, by mechanical mixture, and, when the mass has been brought into the proper state for solidifying, the whole is placed in the moulds. Gossage's Process. GOSSAGE'S patent is dated 1854. His plan for the preparation of the silicate, which differs slightly from that of SHERIDAN, is described on p. 28. In mixing viscous solutions of soluble glass with genuine soap, it is best to commence t the mixing by adding a portion of the solution at a specific gravity of about 1.300, and to add the remaining portions required at increasing specific gravities, so that the average specific gravity of the * SPON'S " Encyclopaedia," v. 1786. f KICHARDSOX and WATTS, " Technology," vol. i. pt. iii. p. 713. 112 SOAPS. whole solution used may be equal to that which has been found by previous trials to yield a compound soap of proper hardness when using a genuine soap of the composition employed. The temperature of the silicate and of the soap-paste should be about 160 F. at the moment of mixing, and, to promote homogeneity, the mixture is stirred up by ma- chinery. This consists* of a large tub or vessel, A (Fig. 24), Laving the shape of an inverted cone of about 26 inches FIG. 24. internal diameter at its lowest part, 3 feet 6 inches at the upper part, and 6 feet deep. It is furnished with a central upright shaft, B, supported by a foot-step, C, fixed to the bottom of the tub, and, by a journal, D, adapted to a metallic bridge-piece, E, which is fixed over the vessel and secured by screw-bolts to its sides. At the upper part of * RICHARDSON and WATTS, "Technology," vol. i. pt. iii. p. 713. HOUSEHOLD SOAPS. 113 the shaft is a bevelled cog-wheel working in gear with another bevelled cog-wheel fixed on a horizontal shaft, S, which is made to revolve by a band passing round the driving-pulley, P, and also round another driving-pulley. The upright shaft is driven at the rate of sixty to eighty revolutions per minute. To the upright shaft B is fixed a closed tub or vessel, F (Fig. 24, i), of such a diameter as to admit of its being placed within the larger vessel, A, leaving a space of about 2 inches at the lower, and 6 inches at the upper part ; and to the outside of this inner vessel are attached, by means of screws or otherwise, a number of projecting blades, / /, made by preference of sheet iron, of such a length as to approach within about J inch of the inside of the vessel A. A spout, G, having a movable stopper, If, is adapted to the lower part of the vessel A for the purpose of running off its contents. The projecting blades //, instead of being attached to an inner vessel, may also be affixed to the inside of the upright shaft, and in that case it is best to attach other projecting blades, K K, to the inside of the vessel A, in such a manner as to allow the blades //to revolve between them. When this apparatus is to be used for the production of compound soap by mixing genuine soap with the silicate solution, it is necessary to ascertain previously the highest temperature at which the mixture will become too thick to run from the mixing apparatus. For this purpose, a pre- paratory mixing of the neat soap with the silicate is made by means of paddles, or crutches, in a vessel capable of con- taining about J ton of soap, the soap and viscous solution being added at such temperatures as will yield a mixture having a temperature at least 10 higher than the tempera- ture referred to. The contents of the preparatory vessel are then transferred to the mixing apparatus, and a rapid i ii4 , SOAPS. revolving motion is communicated to the projecting blades. The stopper of the spout G -is then withdrawn, so as to allow the compound soap, in the state of perfect mixture, to flow from the mixing apparatus, and further quantities of mixed soap and silicate are then supplied. The mixed compound soap is then transferred to the ordinary frames, in which it solidifies on cooling. Way's Method. The alkaline silicate is prepared by one of the methods described on pp. 27, 28, 29. To produce 100 Ib. of soap, the operator puts into the soap-pan 11.5 per cent, of bleached palm oil, 11.5 per cent. of cocoa-nut oil, and 30.6 per cent, of soda lye of 36 Tw. These ingredients are boiled till the soap becomes stiff, and then there is added 44 per cent, of the solution of silicate of 36 Tw. The boiling is now continued till the soap becomes thin and limpid, when 2 .4 per cent, of common salt is thrown in, and the boiling continued for three or four hours. After this the soap may be cleansed, either at once, or after it has been allowed to stand for a few hours. If open steam is used, it is best to nave the solution of silicate and the lye of greater strength than that mentioned, in proportion to the quantity of water which is condensed from such steam into the soap-pan. Other siliceous matters, such as powdered soap-stone, porcelain earth, pipe-clay, and fuller's earth, are also used for mixing with soap instead of soluble glass. Davis's Alk-alumino-silicic Soap* is a mixture of ordinary soap with fuller's earth, pipe-clay, and pearl-ash or soda, by which the cost of the soap is said to be much diminished, while it is claimed that its detergent properties are improved. It is prepared by adding, to every 126 Ib. of soap-paste, 56 Ib. of fuller's earth, slaked or dried, 56 Ib. of * RICHABDSON and WATTS, " Technology," vol. iii. pt. i. p. 714. HOUSEHOLD SOAPS. 115 dried pipe-clay, and 112 Ib. of calcined soda or pearl-ash, all reduced to powder, and sieved as finely as possible. These ingredients are then thoroughly incorporated by stirring or crutching. The mixing must be very perfectly and rapidly done before the pasty mass cools. To obviate any objection against the use of this soap for washing white linens, a modification of the above process is proposed, by which the use of fuller's earth is omitted, leaving the pro- portions, for every 120 Ib. of soap, 112 Ib. of dried pipe-clay and 96 Ib. of calcined alkali. A soap thus prepared is said by the patentee to be useful for general purposes at sea, and for washing white linen in salt water. For the preparation of a soap for washing white linen in fresh water, the process is still further modified by using 112 Ib. of soap-paste, 28 Ib. of dried pipe-clay, and 36 Ib. of calcined soda ; and to prepare a toilet soap, either for fresh or salt water, 28 Ib. of fuller's earth, slaked or dried, and 20 Ib. of calcined soda are mixed with 112 Ib. of perfumed curd soap. DUNN devised and patented a special boiler for combining soap with sodium and potassium silicates under pressure (see p. 65). The soap is prepared from tallow 7 parts, palm oil 3 parts, rosin 3 parts, caustic-soda lye (21 B.) 140 to 150 gallons. These having been placed in the boiler, heat is applied till the pressure is suflicient to permit the tem- perature in the boiler to rise to 310 F. This temperature is maintained for an hour, and the soap is then discharged into the vessel at the side of the apparatus. The silicate is prepared as previously described (p. 29). 8. Sulphated Soaps. These are prepared by a process patented by Dr. NOR- MANDY. The object is to impart hardness to soaps made from inferior fats, and also to soaps containing large I 2 n6 SOAPS. quantities of rosin. "Without this addition, such soaps are apt to be too soft, and, dissolving too freely in water, are very wasteful. The process thus enables a large class of fats, otherwise unsuitable, to be employed in soap-making. The soap is first prepared in the usual manner, and when ready for cleansing, the salts are crutched in. For every 80 Ib. of soap the proportions are 28 Ib. of sodium sulphate (Glauber's salt) and 4 Ib. of potassium carbonate, or 2 Ib. of potassium carbonate and 2 Ib. of sodium carbonate. When the whole has been thoroughly mixed, the soap is ready for the frames. Another process for the preparation of salinated soaps is that patented by NORMANDY and SIMPSON. The soap may be prepared in the usual way from tallow, bone-fat, lard, palm oil, &c., and after the soap has been curded by means of salt, or strong lye, the lye is allowed to settle down, and., after it has been drawn off, a certain quantity of fresh lye and cocoa-nut oil is added, and the whole well boiled till a homogeneous mass results having the appearance, except as regards colour, of fitted yellow soap. The desired proportion of sodium sulphate, sulphite, or hyposulphite is next intro- duced, the mixture boiled, and the soap afterwards trans- ferred to the frames. This method, it is claimed, will yield a mottled soap of better consistence and appearance than is obtainable from the same fatty materials in the ordinary way, and without separation of lyes in the frames. Sodium hyposulphite crutched into the soap increases its hardness, like the sulphate, and the soap so treated is less liable to effloresce. It has also the property of removing the chlorine, which bleached fabrics have a tendency to retain, and by which they are exposed to deterioration. HOFFMANN, MILLER, URE, and MUSPRATT all commend the usefulness of this process, but these soaps are not so much used as formerly. CHAPTER VIII. TOILET, OH FANCY, SOAPS. THE manufacture of these soaps is either carried on as a separate business, or as a branch of the ordinary soap- maker's work, or of the perfumery business. The stock soap is either a specially prepared article cold-process soaps being largely used or a soap prepared in the ordinary manner. It will be convenient to consider this branch of soap- .making under the following heads : i, The materials; 2, The apparatus ; 3, The manipula- tion; 4, Formulce; 5, The French i. The Materials. These are chiefly white curd soap, fitted soaps, and soaps prepared from palm and almond oils. Cocoa-nut-oil and rosin soaps are also used for some toilet soaps. They should .all be of superior quality. 2. The Apparatus. a. For the Preparation of the Soa%). The selected soaps have first to be sliced. This is accom- plished either by a cutter, or planing-kiiife, fixed on a strong wooden bench, and furnished with a drawer to re- ceive the soap shavings as they are sliced off from the bars. (Fig. 30, p. 136.) iiS SOAPS. Or a cutting machine turned by a handle may be em- ployed where larger quantities are operated upon. The bar of soap is pushed down an inclined plane against the edge of one of the blades, the handle is turned, and the shavings fall into a box placed underneath. By this machine, 2 cwt. of soap may be cut in an hour. (Fig. 31, p. 136.) b. For lie-melting the The most convenient pans for this purpose are small steam-jacketed pans, of 2 cwt. to ^ ton capacity, according FIG. 25. A, The shell. B and C, Steam-coils. D, Grating for soap to rest upon. E, Discharge-gate. F, Small pipe for admitting direct steam through perforations. G, Feed-spout. H H, Floor. J, Dry steam. /, Exhaust steam. K, Open steam. TOILET, OR FANCY, SOAPS. 119 to the extent of business ; or a WHITAKER re-inelter (Fig. 25) may be employed. The method of using this, apparatus is as follows: Fill the re-melter with soap, close the discharge-gate, E, and let the open and dry steam on for ten minutes. Then shut off the open steam, open the discharge-gate, and run off the soap into the steam crutcher till the latter is full, and run the crutcher from three to five minutes until the soap is thoroughly mixed. As fast as the soap lowers in the re- melter, add more stock, so as to keep the vessel full, as the soap will thus melt more quickly. The open steam should be let on two or three times, for ten minutes at a time, while filling the crutcher, some kinds of soap requiring more than others. This machine is also used for re-melting soap scraps, with the object of saving fillings, such as sodium silicate, talc, and other substances. c. Frames. These are smaller than those used for household soaps. d. Moulding. For moulding the tablets, various kinds of apparatus are employed. Fig. 26 will give the jr IG 2 6. reader an idea of the modus operandi. A A is a table to which the press is fastened by bolts and screws. E is the lower portion of the mould ; the upper portion is attached to the piston D, which is worked by the lever (7, connected with the cast-iron pillar B. e. /Stamping. For this purpose the press Fig. 27 may be employed. 120 SOAPS. In this machine* there are two spiral springs, A and B, by which the cake of soap is immediately expelled from the box (7, as soon as it is pressed. D is a rope suspending a FIG. 27. wooden rod, E, which serves as a support to the bottom of the die during the pressure. The box C is movable, being merely fastened by screws, and, when necessary, may be replaced by others of different sizes. The die from which the tablet is to receive a device, or name, is screwed to the top of the box (7, and may also be changed when required. Another form of stamping-press is that shown in Fig. 28, which is worked by hand. Fig. 29 represents a stamping-press worked by steam. 3. The Manipulation. The numerous varieties of fancy soaps may be classed as (a) opaque and (b) transparent. * MORFIT, p. 185. TOILET, OR FANCY, SOAPS. 121 a. Opaque Toilet Soaps. In the manufacture of these soaps, the operator may either (A) prepare the article directly by the little-pan or cold process ; or (B) he may re-melt and refine, and after- wards perfume soaps prepared in the ordinary manner. Or, to prepare the finest toilet soaps, he may adopt the French system (p. 136). FIG. 28. A. COLD PROCESS. The selected fats, such as clarified beef marrow, clarified lard, sweet-almond oil, cocoa-nut oil, castor oil, and other fats of good quality, are melted to- gether, and, if necessary, strained. Some makers now add 122 SOAPS. the alkaline lye to the melted fat ; others heat the lye, and add the melted fat to it. In either case the added materials are introduced gradually with continual stirring, and care is Fia. 29. taken that the temperature does not rise much above 150 F. (65.5 C.). The next stage is to run the soap into the cooling-frames, and allow it to repose. The low temperature at which this operation is conducted TOILET, OR FANCY, SOAPS. 123 is extremely favourable to the use of delicate perfumes. These are, of course, best introduced at as late a stage of the process as possible, so as to prevent loss, yet before it is too late to secure complete admixture with the mass. The advantages and disadvantages of the cold process have been already specified (p. 88). B. RE-MELTING. The soap for this purpose should be a good yellow fitted soap of recent manufacture, and as neutral as possible. i. After having been sliced by one of the machines pre- viously mentioned (p. 117), it is transferred to the melting- pan. It must not, however, be all put in at once, but, after the first portions have been melted and crutched, so as to produce uniformity, a little more of the cut soap is added, the pan covered till this has also become fluid, and the whole again stirred. Other portions are then introduced, and successively melted and crutched as before, so as to effect intimate mixture. When the paste begins to cool, the desired colouring matters are mixed with it, and after- wards the selected perfume, reserving the latter to the last so as to avoid any unnecessary loss by evaporation. At this stage also, if desired, a portion of glycerin may be introduced. 2. FRAMING. The soap is now ready for the frames, into which the pasty mass may be transferred by ladles. The frames are covered with cloths, so that the cooling may be gradual. 3. FINISHING. In a day or two it will be sufficiently hard to cut into bars and tablets of any desired size. The cakes are then trimmed at the edges and corners, moulded, and stamped. Savonettes, soap-balls, or wash-balls are shaped by rotating blocks of soap upon a soap-scoop, made of brass with sharp edges, or the paste may be first formed into 124 . SOAPS. .balls by hand, and, when quite dry, finished by turning them with a lathe. The surface of tablets or of savonettes may be polished, either by rubbing with a little spirit on a cloth, or by exposure to the action of wet steam for a few seconds. b. Transparent Soaps. Two methods are in use for the manufacture of trans- parent soaps (i) Solution of stock soaps in alcohol; (2) The cold process. i. PREPARATION BY SOLUTION OF SOAP IN ALCOHOL. It has been long known that a concentrated hot solution of soap retains its transparency on cooling. This fact is applied to the production of transparent soaps. As any non-soapy matters that may be present in the stock are, with the exception of free caustic alkali, insoluble in strong spirit, a transparent soap properly prepared by the alco- holic process from a good soap is necessarily of a high degree of purity, and is justly valued for toilet purposes. Makers do not all operate in exactly the same way, but the following is an outline of the process generally : 1. Yellow soap of good quality, reduced to shavings, and dried, is introduced into a still of sufficient capacity to- gether with alcohol (strength about 55 to 60 o.p.). Some- times the shavings are previously powdered, and in this country, owing to the high spirit duty, methylated spirit, instead of pure alcohol, is employed, in the proportion of about 5 gallons to i cwt. of dried soap. Most makers also add a certain proportion of glycerin. The still is heated by steam, or by a hot-water jacket, as the direct action of fire would interfere with the appearance of the product. 2. Moderate heat is continued till about one-fifth to one- third of the spirit has passed over. 3. The clear residue, free from any deposited matters, is TOILET, OR FANCY, SOAPS. 125 run into moulds to form bars, and when these are cold they are cut into cakes. 4. The cakes, after drying sufficiently, are bevelled, polished, and stamped. The cakes are not at first transparent, and require to be kept in the drying-room for some months before they are ready for sale. During this time evaporation of the remain- ing alcohol and water takes place, the colour deepens, and much of the odour of the methylated spirit goes off. If too much spirit is left in the soap at first, it is liable to be- come opaque, and, if there is too little, the soap will not harden properly. The finished soap contains only from 9 to 1 2 per cent, of water, and no spirit. Scents and colouring matters, when desired, are mixed with the dissolved soap at the commencement of the pro- cess. The colouring matters are introduced in alcoholic solution for red, tincture of alkanet ; for yellow, tincture of turmeric, annatto, or saffron ; for orange, a mixture of alkanet and turmeric ; for green, tincture of chlorophyll, or a mixture of blue and yellow ; for blue, tincture of indigo-carmine ; &c. 2. THE COLD PROCESS. Certain kinds of soaps* pre- pared by the cold process, especially castor-oil soap, have a natural tendency towards a somewhat transparent appear- ance, which is increased by the addition of spirit, glycerin, sugar, or petroleum. With the employment of a consider- able proportion of sugar (15 to 30 per cent.) a comparatively large amount of tallow is admissible without interfering with the transparency, provided that complete saponification is insured. Dr. WRIGHT gives the following formula for the production of a transparent soap by this process, which will be without great excess of free alkali or of sugar : * Dr. C. R. A. WEIGHT, Cantor Lectures, May 1885, p. 25. 126 SOAPS. Heat to 149 F. (65 C.) a mixture of tallow 20 parts, palm oil 12 parts, castor oil 8 parts, and then gradually run in 20 parts of caustic-soda lye at 38 B. When inter- mixed, crutch in 20 parts of strong alcohol, 20 parts of glycerin, and 10 of syrup containing half its weight of loaf- sugar. Colours and perfumes may be added as desired. As an" illustration of the materials sometimes used in this class of soaps, WRIGHT quotes the following formula :* Melt the following with agitation: 10 kilos, cocoa-nut oil, 10 kilos, castor oil, 8 kilos, neutral tallow, and saponify them at 122 F. (50 C.) with 14 kilos, of caustic soda at 38 B., and continue stirring until pastiness sets in. Add 8 kilos, loaf-sugar in 8J- litres of water at 185 F. (85 C.), taking care to bring it in gradually. As soon as the soap begins to solidify at the sides, the boiler is jacketed with a water-bath, kept at 176 F. (80 C.), until the soap has attained the proper consistency and the scum has separated. Add 20 to 30 per cent, of loading, agitate well, and then stir in a boiling solution of I kilo, crystallized soda in a litre of water; dye, perfume, and finish off the batch as usual. The loading is made from mineral oil and soap shavings, the petroleum being previously deodorized by means of bleach- ing-powder solution and hydrochloric acid, and subsequent treatment with chalk to remove adhering acid. 30 kilos, of the oil thus purified are heated to 122 F. (50 C.), mixed with 2 kilos, of well-dried soap shavings, and heated until a sample taken out solidifies on cooling. On this formula WRIGHT makes the following useful observations : " It is evident from the above that even without the loading the resulting mass would not contain as much as half its weight of actual soap, for the ingredients consist of 28 kilos, fatty glycerides (representing a little * "'Journ. Soc. Chem. Ind." April 1883. TOILET, OR FANCY, SOAPS. 127 more than the same weight of anhydrous soda soap about 29 kilos.) and 32^ kilos, of water, soda, and sugar, so that, when 30 per cent, of loading is added, the resulting mass would not contain much more than one-third its weight of actual soap. On the other hand, the total alkali used (partly as caustic-soda solution, partly as crystals) repre- sents about 113 per cent, of the amount chemically equiva- lent to the fatty matters, furnishing, consequently, a soap with an excess of free alkali equal to one-eighth of that combined as soap a quantity very far in excess of that compatible with good quality as regards injurious action on tender skins. The quantity of sugar prescribed represents some 13 per cent., reckoned on the mass without loading, and about 2 7 per cent, of the actual soap formed. " This formula, apart from the loading, results in the production of an article of distinctly better quality than most of the transparent soaps of this kind now sold in Great Britain, for these soaps usually contain a still larger excess of alkali (ranging from 15 to 25 per cent., and even more being often found), whilst the amount of actual soap in tablets fresh from the factory (and not dried by exposure in shop windows) rarely exceeds 45 per cent., so that these articles are about as much a compound of sugar-candy and soda crystals as they are soaps, if not more so." These soaps are often termed transparent glycerin soaps. The following formulae are said to give satisfactory re- sults : i. Melt together 500 parts of suet, the same quantity of Ceylon cocoa-nut oil, 250 parts of castor oil, 50 parts of palm oil, and 500 parts of glycerin. Saponify the mixture at about 75 C. with 650 parts of soda lye of 1.38 sp. gr. The soda solution should be added gradually, and the whole well stirred during the saponification, which will be com- pleted in about five minutes. The soap is now removed 128 SOAPS. from the source of heat, and mixed with 600 parts of strong alcohol (or methylated spirit), the whole being well stirred until it is clear. 150 parts of simple syrup are then added, together with the perfumes. It is then poured into moulds.* 2. 20 Ib. tallow, 12 Ib. palm oil, 8 Ib. castor oil, 20 Ib. 38 lye, 20 Ib. 96 per cent, alcohol, 20 Ib. glycerin, 5 Ib. sugar dissolved in 5 Ib. water. Heat the tallow and palm oil, add the lye, and saponify; then add the alcohol, and, when the combination is complete, introduce the glycerin. The soap may be perfumed with oil of bergamotte 250 grams, citron 90 grams, lavender 20 grams, neroli 30 grams, rose- mary 5 grams, and a few drops of otto of roses dissolved in i Ib. of 96 per cent, alcohol and coloured with saffron substitute, t CRISTIANI^ gives the two following formulae : 3. Transparent Soa}}. Tallow 209 Ib., caustic-soda lye 40 B. 94.6 Ib., alcohol no Ib. To the melted grease add one-half the alkali, keeping the heat as low as possible about 120 F. When, with con- stant stirring, the fresh lye is combined, add the remainder of the lye, to which has been previously added the alcohol, the heat being well regulated. Saponification takes place rapidly. Add the perfume, cool, pour into the frames, and continue the cooling very gradually. The transparency will not be apparent till the soap has been exposed to the air for some time. To perfume the quantities given above, 2.2 Ib. of mixed essences will be required. 4. Transparent Glycerin Soap. Tallow (mutton) 44 lb. 7 * "Pharm. Zeitung," 1879, p. 719; "Year Book of Pharmacy," 1880, p. 344. f " Seifensieder Zeitung," 1884, p. xxiii. $ " Treatise on Soap and Candles," pp. 422, 423. TOILET, OR FANCY, SOAPS. 129 cocoa-nut oil 44 lb., castor oil 22 lb., glycerin (pure) 22 lb., caustic lye 40 B. 57 lb., alcohol (96 per cent.) 48.4 lb., water 9.9 lb. Melt the grease at 104 F., and add the alkali gradually, keeping the heat low to prevent evaporation, and stir con- stantly. "When the lye has been absorbed, after three or four hours' stirring, add the alcohol, which should be warmed, and stir till the whole becomes cool. Then add the glycerin, and, when this has been mixed, the water and perfumes. Turn into frames, pouring slowly. Very superior, if well made. A cheap transparent soap may be made as follows :* Cocoa-nut oil 10 kilos., castor oil 10 kilos., tallow 8 kilos., caustic-soda lye 38 B. 14 kilos. Saponify at 112 F. (50 C.), and stir till pasty. Then add gradually 8 kilos, loaf-sugar in 8J litres at 185 F. (85 C.); cool and frame. 4. Formulae. Ammoniated Soap.t A soap made from 8 parts of stearic acid, 4 cocoa-nut oil, i potash, i soda, 6 water, is cut into shavings and placed in a retort, in which it is subjected to the action of gaseous ammonia, at a pressure of 15 lb. per square inch, till thoroughly permeated by it. Almond Soap. Oil of almonds by weight 21 oz., solu- tion of caustic soda (sp. gr. 1.334) by weight 10 oz. Add the lye to the oil in small portions, stirring frequently, leave the mixture for some days at a temperature of from 64 to 68 F., stirring occasionally, and, when it has acquired the consistence of a soft paste, put it into moulds till * " J. Soc. Chem. Ind." 1883, p. 181. f C. K. HUXLEY, English patent 3441, March 17, 1885. K 139 . SOAPS. sufficiently solidified. It should be exposed to the air for one or two months before it is used. Beef-marrow Soap.* To 500 Ib. of beef marrow add 250 Ib. of caustic-soda lye of 36 ? B., stir constantly and gently, and heat the mass till it becomes soluble in water. In this state dilute with 2000 parts of boiling water, and pour in 1000 parts of brine (containing 180 parts of common salt), with constant stirring. After allowing some time for repose, pour into the frames, and leave for a day or two to set thoroughly. Bitter-almond Soap. Pure white soap 10 kilos., oil of bitter almonds 120 grams. Not coloured. Or, white tallow soap 56 Ib., oil of almonds | Ib. For inferior kinds, nitre-benzol is employed instead of oil of almonds. Moating Soap. Good oil soap 14 Ib., water 3 pints. Melt together by aid of steam or water bath, and assiduously beat together until the mixture has at least doubled its volume. The capacity of the pan for 14 Ib. of soap should be about 1 8 gallons. Frame and cool. The thickness of the soap in the frames should not be more than 6 or 7 inches. In about a week or less it will be ready for cutting. Perfume, as desired. Colour with J to i drachm of vermilion per Ib. Glycerin Soap. Any mild soap, being melted, has glycerin intimately mixed with it in the proportion of -^th to -^t h of the weight of the soap. Perfume with oil of bergamotte or rose-geranium mixed with a little oil of cassia, to which sometimes a little oil of bitter almonds is added. Honey Soap. White Marseilles soap 4 oz., honey 4 oz., benzoin i oz., storax J oz. Mix well in a marble mortar. "When thoroughly mixed, melt over a water bath, pass * MORFIT, " Treatise on Soap," p. 244. TOILET, OR FANCY, SOAPS. 131 through a fine sieve, and run into moulds. Divide into cakes.* The article commercially vended under this name rarely contains any honey. It may be prepared as follows : Palm-oil soap and olive oil of each i part, curd soap 3 parts ; melt together. Perfume with oil of verbena, rose-geranium, or ginger- grass. Or, a neat yellow soap is mixed with 5 per cent, sodium carbonate, or silicate (59 J B.), the whole crutched, and per- fumed with oil of citronella. Lard Soap. This soap is prepared by the cold process, as follows : Melt 112 Ib. of lard by gentle heat, and add half the lye, prepared by dissolving 56 Ib. of caustic soda to mark 36 B. Agitate well without allowing the mixture to Tboil, and when the incorporation is complete the remainder of the lye is gradually introduced. The temperature is kept under 149 F. When the paste has sufficient consistence, and has no greasy feel when pressed between the fingers, it may be run into the frames. The desired perfume is added while the soap is in the pasty state. In about two -days it will have become sufficiently solid to be cut into tablets and pressed. This soap is very hard, and of a brilliant whiteness. Miahle's Neutral Soap. In a communication to the French Academy,t M. Miahle describes a soap which he states combines the advantages of being prepared without heat, and thus avoiding the loss of the glycerin in com- bination with the fatty matters, and of being free from that alkalinity generally present in soaps prepared in the cold. In its preparation the ordinary toilet soap, made without * DUSSAUCE, " Treatise on the Manufacture of Soap," p. 638. f " Pharm. Journ." iii. 665. K 2 132 SOAPS. heat, is cut into shavings and exposed, in a properly closed chamber, to the action of carbonic acid gas. The soap absorbs a quantity of the gas proportionate to the quantity of caustic soda which has escaped saponification, and by the transformation of the free alkali into bicarbonate it loses all its causticity. It then constitutes a perfectly neutral soap, containing all the glycerin of the fatty bodies employed in its manufacture, and a certain quantity of bicarbonate of soda. Samphire Soap is Messrs. Field's recently patented article, which is saponified by the use of iodized potash, obtained from seaweed ashes, with palm oil and olein. The resulting soap is subsequently milled, after completely ex- pelling the water, and is de-alkalized by the introduction of an ammoniacal salt. Savon au Bouquet. White tallow or lard soap 10 kilos.* Perfume with oil of bergamotte 15 grams, neroli 15 grams, sassafras 10 grams, thyme 10 grams. Colour with 100 grams brown ochre. The oil of neroli may be replaced by oil of lavender, and oil of cloves,. 10 grams, may also be added. Savon a 1'Huile de Cannelle (Cinnamon Soap). Pure palm soap 5 kilos., tallow soap 5 kilos. Perfume with oil of Chinese cinnamon 80 grams, sassa- fras 20 grams, bergamotte 30 grams. Colour with 80 grams yellow ochre and 20 grams burnt sienna. For inferior descriptions, oil of cassia is used instead of 011 of cinnamon. Savon au Fleur d' Or anger. White tallow soap 6 - kilos., pure palm soap 4 kilos. * i kilogram = 2.20 Ib. Avoir. TOILET, OR FANCY, SOAPS. 133 Perfume with oil of Portugal 140 grams, oil of amber i o grams. Or with oil of geranium 40 grams, oil of neroli 50 grams. Savon au Muse. White tallow soap 5 kilos., pure palm soap 5 kilos. Perfume with oil of bergarnotte 50 grams, roses 5 grams, cloves 5 grams, musk 10 grams. The musk is prepared thus : Pound 10 grams of musk in a mortar, with an equal weight of sugar, and 5 grams of pure potash; then add 160 grams of alcohol gradually, triturate for a quarter of an hour, pour the mixture into a flask, and leave it for two to four weeks, shaking it from time to time. Then filter, add the whole of the nitrate to the 10 kilos, of soap, and afterwards the other perfumes. Colour with 80 grams brown ochre. Savon a la Rose. White tallow or lard soap 10 kilos. Perfume with oil of roses 40 grams, cloves 15 grams, cinnamon 10 grams, bergamotte 30 grams, neroli 10 grams. Or with oil of roses 25 grams, geranium 60 grams, cloves 15 grams, Chinese cinnamon 10 grams. Colour with 60 or 80 grams of vermilion. Savon a la Vanille. White tallow soap 10 kilos. Perfume with tincture of vanilla 500 grams, oil of roses 5 grams. Colour with 100 grams of burnt sienna. Savonettes, or Wash-balls.* These are made of any of the mild toilet soaps, scented at will, and sometimes with the addition of starch. The spheroidal form is given to them, as described on p. 123. i. Curd soap 3 lb., finest yellow soap 2 Ib. (both in shavings), soft water f pint. Melt by a gentle heat, and stir in powdered starch i| lb. When the mass has con- * COOLEY'S " Encyclopaedia," ii. 1464. 134 SOAPS. siderably cooled, add essence of lemon or bergamotte i| oz. r and make into balls. 2. Camphor. Melt spermaceti 2 oz., add camphor cut small i oz., dissolve, and add the mixture to white curd soap 1 1 lb., previously melted by the aid of a little water and gentle heat, and allowed to cool considerably. These balls should be covered with tin-foil. 3. Honey. Finest yellow soap 7 lb., palm oil \ lb. Melt, and add oil of verbena, rose-geranium, or ginger-grass: i oz., or oil of rosemary J oz. 4. Mottled. (a) Red : Cut white curd or Windsor soap (not too dry) into small square pieces, and roll these in- powdered bole or rouge, either with or without the addition of some starch ; then squeeze them strongly into balls, ob- serving to mix the colour as little as possible, (b) Blue : Koll in powder blue, and proceed as before, (c) Green : Roll the pieces in a mixture of powder blue and bright yellow ochre. By varying the colour of the powder, mottled savonettes- of any colour may be produced. 5. Sand. Soap (at will) 2 lb., fine sand i lb. ; perfume if desired. For finer qualities, finely powdered pumice- stone is substituted for sand. 6. Violet. Palm-oil soap 4 lb., starch 2 lb., finely pow- dered orris root i lb. Shaving Paste. i. Naples soap 402., powdered Castile soap 2 oz., honey i oz., essence of ambergris and oils of cassia and nutmegs of each 5 or 6 drops. 2. White wax, spermaceti, and almond oil of each J oz. ;. melt, and, whilst warm, beat in two squares of Windsor soap, previously reduced to a paste with a little rose water. 3. White soft soap 4 oz., spermaceti and salad oil of each \ oz. ; melt together and stir till cold. Scent at will. When properly prepared, these pastes produce a good TOILET, OR FANCY, SOAPS. 13$ lather, with either hot or cold water, which does not dry on the face. Windsor Soap. Plain. The best kind is made from olive oil i part, tallow 8 or 9 parts, saponified with caustic-soda lye, and scented, after removal from the pan, with oil of caraway and a little oil of bergamotte, lavender, or origanum, in the proportion of about 2 Ib. of the mixed oils per cwt. of soap. A little oil of cassia, or of almonds, or of the essences of musk and ambergris may be also added. The oil of caraway may be replaced by a mixture of equal parts of the oils of rosemary and lavender. Ordinary plain Windsor soap is made from curd soap, scented, while pasty, with oil of caraway, and a little oil of bergamotte, lavender, or origanum, in the proportion of about i J Ib. of the mixed oils per cwt. Brown. The colour of this variety was originally the effect of age upon the plain white soap, but is now pro- duced by the addition to the above of a little brown colour- ing matter, such as caramel, umber, or brown ochre. Weise's formula.* 40 Ib. tallow and 15 to 20 Ib. olive oil are saponified with soda lye of 19 B., and the soap is treated with lye of 15, and finally with lye of 20, the process being conducted as for a curd soap, except that no excess of alkali is to be used. When boiled clear, the soap is left in the boiler for six or eight hours, then completely separated from the lye, placed in a flat mould, and pressed till it no longer exhibits any flux, to prevent it from mottling. To perfume the above-mentioned quantity, add oil of cumin 10 oz., oil of bergamotte 6 oz., oil of lavender 3 oz., oil of origanum i oz., and oil of thyme 3 oz. Another formula is the following: Hard curd soap) (made from good tallow 9 parts, olive oil i part) 100 oz., : * " Dingl. Polyt. J." cxxxv. 237. 136 SOAPS. scented with oil of caraway i oz., oil of lavender J oz., and oil of rosemary J oz. Rose Windsor is the plain variety coloured with ver- milion or iron oxide, and perfumed, after the soap has been transferred to the frame, with essence of roses. Violet Windsor* is composed of 50 parts of lard, 33 parts of palm oil, and 17 parts of spermaceti, perfumed with essence of Portugal and a little oil of cloves. 5. French System. The French have devised special machinery for the manufacture of the finest kind of toilet soaps. The " stock " soap, or basis, should be made from the purest materials. Usually, it is prepared by the cold process. The mode of procedure is as follows : i. CUTTING. The soap having been cut into bands by the hand cutter (Fig. 30) is passed to the rotary cutter FIG. 31. FIG. 30. BEYER'S hand cutter. BEYEII'S rotary cutter. (Fig. 31), or to a EUTSCHMAN automatic soap-chipper (Fig. 32), by which it is reduced to thin shavings. This machine is usually placed in the drying-room, in order that KICHARDSON and WATTS, "Technology," vol. i. pt. iii. p. 707. TOILET, OR FANCY, SOAPS. 137 during the process the shavings may become somewhat drier. FIG. 32. Automatic soap-chipper. 2. CRUSHING AND GRINDING. The dry shavings are now ready to be placed, with the desired perfumes and colouring matters, in the hopper of the crushing -mill, Fig. 33 or Fig. 34. This machine is mounted on a frame cast in one piece, and carries three or four granite rollers. The motion of 138 SOAPS. the rollers draws the soap shavings between the first and second rollers, which are so geared that the second re- volves more quickly than the first, and the soap is thus not only crushed, but also undergoes a rubbing action. The increased speed of the second roller has the effect also of passing the crushed material along so as to place it between FIG. 33. BEYER'S crushing-mill. the second and third rollers, where it undergoes a second crushing. The third roller, revolving at a still higher speed than the second, causes the soap to be seized and crushed again between the third and fourth rollers. The soap paste is removed from the last roller by a steel scraper, and returned to the hopper, from which it is again passed through the mill. This triple crushing by the sue- TOILET, OR FANCY, SOAPS. 139 cessive passing of the soap between the rollers is technically called in France passe (passage). Each passage of 30 kilo- grams (about 60 Ib.) occupies five minutes. Fio. 34. EUTSCHMAN'S crushing-mill. Three or four passages, or more, are generally required to effect perfect amalgamation of the mass, the exact number depending on the nature of the materials. When the workman judges that the operation is finished, he presses a button, acting on two scrapers, and these fall 140 SOAPS. in front of the fourth roller, and the separated ribbons of soap are received in a small waggon, by which they are conveyed to the plotting and squeezing machine (boudineuse- peloteuse). In some factories, however, the crushing-mill is so placed that the ribbons can be directly thrown from it to the feeding-hopper of the plotting machine. BEYER'S continuous plodding machine. 3. PLOTTING or PLODDING. The object of the plotting machine is to compress the ribbons and shape them into perfectly homogeneous and compact bars, and its use has tended greatly to the development of the manufacture of toilet soaps. A representation of this apparatus is given in. TOILET, OR FANCY, SOAPS. 141 Figs. 35 and 36. In this machine, below the hopper, there is a powerful screw propeller, conical in shape, and fitting closely the conical barrel. Owing to this form, the ribbons of soap, falling from the hopper upon the larger part of the revolving screw, are forced towards the mouth of the barrel with increasing pressure. The brass mouthpiece is fitted 142 SOAPS. with gauge-plates for altering the size and shape of the bar as it issues therefrom. These two machines are capable of turning out 10,000 cakes of soap in one day. In another form of plotting machine the soap is pressed by means of a hydraulic rani through a cylinder, and squirted through a mouthpiece of the required dimension shape. FIG. 37. RUTSCHMAN'S cake-cutting machine. 4. CUTTING INTO CAKES. From the plotting machine the bars are transferred to a cutting machine, worked either by the foot (Fig. 37) or by steam, and cut into blocks or -i E 8OOOOOOOOOOOOOOOOOOQ OO^OOOOOOO^OLoOOcOLouoOLOO 100 c?R -> d d oo < d * >-i iA c4 \o* ci c^ d MO ^ ro c\ ri d vo O M r/ ~> 1-1 ON 1-1 MN Co oo r^ O >O ON O O H^> 6=S d H H H o" d d EH d E-i d d d d d d d d d d o" o" d d d <4J O ^ co O O *-O O O ^J" O O C^ O O *-O O HH O "-I M s ^4 d dHHH d dr^HH cH d o" d d d d d d d d d d d 1 s? rj- o i- w N O O "1 O ^u-i^OOcoO^OO 00 CO ON CNOO O cs O 1-1 co <> 5 dE-i dH d d d o* d d o'H o'H d d d d d d O O O O O 1 r'Z'i Svg t^c o^8v^aS S^vS $& $>& S^^?^ ^ J 3%% CTv CT\ * O\ ON O C) 00 O^'OO CT* O ON 00 ^00 O C) ^" ^J" OCN^OO M ^ . W O O O ^ O OO Tf" ON 1 -^i ^t" O "^"OO OO "*-O OOOO iocor^ u^ ^ * W to CO!>D O 'O OO OO t*> l -O t s >'O O^ ~3" >* ^O 4 GO 1L O O - CO 0^00 CO 1 "iz; ^ Hrt 1 P J s | * ' ' " 1 ?L "^ rt ^ ^ w a ^ n ' .2 ^ ||| :'| | s s s 1 i s 8 |f,/: al M ^ cOTfi^vo t^OO ONO N mTfinvO t^OO OS O MEDICINAL SOAPS. 151 Shave the soap into ribbons, beat it into a paste with a little water, and add first the pumice-stone, and then the thymol and oil of wintergreen dissolved in a small quantity of alcohol. Castor-oil Soap (for Linimentum Saponis Compositum). According to M. S. HAMMER,* this soap seems to answer best for this liniment, and may be prepared by the follow- ing process : Saponify 2 pints of castor oil with 6 oz. of caustic potash and 2 pints of water by heating till a transparent mixture is obtained ; then add a saturated solution of 8 oz. of sodium chloride, stir until cool, allow to subside for a day, decant the liquid portion, cut in pieces, and dry for use. Chlorinated Soap (Sapo Colds Chlorinates). Castile soap in powder IT oz., chloride of lime (dry) i oz. Mix, beat them to a mass with rectified spirit q.s., holding in solution oil of verbena, or of ginger-grass, 5 oz. Lastly, form the mass into flat tablets, and wrap in thin sheet gutta-percha. Said to be well adapted for hospital use, for removing stains from the skin, and for preventing infection from contagious diseases. Camphorated Sulphur Soap.t 12 kilos, of cocoa-nut oil, 6 kilos, of soda lye (38 B.), i kilo, of potassium sul- phate dissolved in |- kilo, of water, and 160 grams of cam- phor, which is to be dissolved in the melted cocoa-nut oil. Gall Soap.t i kilo, of galls is stirred in 25 kilos, of melted cocoa-nut oil, and then saponified cold with. 227,- kilos, of soda lye (38 B.). The soap is coloured with 3^0 grams of ultramarine green, and perfumed with 75 grams lavender oil and 75 grams cummin oil. Iodine Soap.f 10 kilos, cocoa-nut oil, 5 kilos, lye * "Proc. Cal. Pharm. Soc." 1883, p. 50; "Year Book of Phar- macy," 1883, p. 313. f "Year Book of Pharmacy," 1883, p. 313. 152 SOAPS. (38 B.), and i-J- kilo, of potassium iodide, dissolved in ^ kilo, of water. Disinfecting Soap (JEYE'S Improved}. Gas tar is dis- tilled and the light oil rejected ; 16 parts of the heavier oil, 32 parts of cocoa-nut oil, and 16 parts of caustic soda at 35 B. are saponified in a jacketed pan, with or with- out the addition of rosin, and sodium sulphate and car- bonate. * Liquid Soaps (KiNGZETT's).t KINGZETT prepares liquid soaps for employment as insecticides by dissolving rosin or crude turpentine in alcohol, and saponifying with potash. To this is added an alcoholic solution of a fatty acid soap and various disinfectants. Or,J crude turpentine, or rosin may be dissolved in " Sanitas " oil, or rosin spirit, or rosin oil, and then saponified by caustic-alkali solution of sp. gr. 1.300. Camphor is added to insure a permanently liquid product, and this may be medicated by addition of thymol, &c. Or, petroleum spirit, or thymol, may be used instead of, or in conjunction with, the " Sanitas " oil mentioned in the last patent. Mercurial Soaps. i. Sapo Hydrargyri. Dissolve 4 cz. of mercury in the same weight of nitric acid without heat ; melt in a porcelain basin, over a water-bath, 18 oz. of veal suet, and add the solution, stirring the mixture till the union is complete. To 5 oz. of this ointment add 2 oz. of solution of caustic soda (sp. gr. 1.33) till a soap is formed which is completely soluble in water. 2. Sapo Mercurialis. Castile soap (in powder) 4 oz., corrosive sublimate i dr. dissolved in rectified spirit i oz. ; beat to a uniform mass in a mortar. * English patent 16,427, December 13, 1884. t >, t 3,894, March 26, 1885. J ,, ,, 2,210, February 17, 1885. ,, 3.855, March 25, 1885. MEDICINAL SOAPS. 153 3. Sapo Hydrargyri Precipitati AIM (Sir H. MAHSH). Beat 12 oz. of white Windsor soap in a mortar, add i drachm of rectified spirit, 2 drachms of white precipi- tate, and 10 drops of otto of roses; beat the whole to a uniform paste. 4. Sapo Hydrargyri Precipitati Rubri (Sir H. MARSH). White Windsor soap 2 oz., nitrate of mercury (levigated) i drachm, otto of roses 6 or 8 drops, in rectified spirit i to 2 drachms ; beat to a paste. Soap Leaves. These are made by passing continuous paper sheets over rollers through a hot solution of soap, the excess of soap attached to the surface being scraped off. The paper then is conducted over drying cylinders to the cutting machine.* Tannin Soap. 9 kilos, of cocoa-nut oil are saponified with 4^ kilos, of soda lye, then 250 grams of tannin, previously dissolved in alcohol, are put in, and the whole mixed. The soap is perfumed with 30 grams Peru balsam, 10 grams cassia oil, and 10 grams oil of cloves.f Tar Soap (Sapo Piceus). Tar i part, liquor potassre and soap (in shavings) of each 2 parts ; beat them together till they unite. Action, stimulant, in psoriasis, lepra, &c. Turpentine Soap (8apo Terelinthince ; STARKEY'S Soap). Potassium bicarbonate, oil of turpentine, and Venice tur- pentine, equal parts ; triturate together in a warm mortar, with a little water, till they combine ; put the product into paper moulds, and, in a few days, slice it, and preserve in well-stoppered bottles. Unna's Soaps. J UNNA started his experiments by pre- * KEITHOFFER and NEFFE, Vienna, German patent 23,195, June 6, 1882 ; " J. Soc. Chem. Ind." 1883, p. 543. f "Year Book of Pharmacy," 1883, p. 313. J " Edinburgh Medical Journ." October 1885 ; " Year Book of Pharmacy," 1886, p. 282 ; " Pharm. Journ." xvi. 328. 154 SOAPS. paring a normal soap of fixed composition, which could be incorporated with various medicinal substances. Though, theoretically, he considered that beef fat was the most per- fect, still, practically, he found that an advantage was gained by adding i part of olive oil to 8 parts of beef fat. The alkali consisted of 2 parts of soda to I of potash, this- combination being less apt to blister when medicinal sub- stances were added to the soap. Cocoa-nut oil, though pro- ducing a soap which lathers well, was found to make the skin dry after continued use. Even a neutral soap, when constantly used, tends, according to UNNA, to produce an unpleasant roughness, from removing too completely the natural oiliness of the skin. He, therefore, leaves the soap over-fatty, that is, besides the fat necessary for perfect saponification, an excess amounting to 3 or 4 per cent, is added. Any secondary addition of glycerin or vaseline he entirely rejects. This soap he terms over-fatty normal soap (iiber fettete grund Seife). It may be used as an ordinary washing soap in all forms of inflammatory skin diseases where ordinary soap is forbidden, as in eczema, erythema, and for skins poor in fat with a tendency to dryness ; also as a soap for healthy people whose occupation compels them to wash frequently in the course of the day. The compo- sition of such soap is : 1 6 parts best ox fat . . . 59.3 2 ,, olive oil . . . . . 7.4 6 soda lye (38 B.) . . . 22.2 3 potash lye . . . .11.1 27 100.0 In this soap about 4 per cent, of oil remains unsaponified. It is of a yellowish-white colour, of a waxy consistence, and quite permanent. It forms an exceedingly good soap for children, and, if rubbed on the hands and wiped off again in a few minutes with a dry towel, it leaves the hands smooth, MEDICINAL SOAPS. 155 and little liable to be injuriously affected by damp, cold, or long-continued contact with carbolic acid. Over-fatty Marble Soap consists of equal parts of the foregoing, and the finest powdered marble. It will be found useful in thinning down the horny layer in acne. It thus replaces pumice-stone and sand soap, and, while the pow- dered marble rubs off the scales or the thickened epider- mis, the over-fatty normal soap leaves the polished surface smooth and normally unctuous. Over-fatty Ichthyol Soap* This has its special value in the treatment of various forms of rosacea, both in the congestive and cyanotic forms, and can be advantageously employed with hot water. A stronger effect is produced by leaving the soapy lather to dry on. Wych-hazel Soap.t The juice of the plant Hama- tnelis virginica, or common wych-hazel, is mixed with soap, and with various compounds for toilet purposes which con- tain soap. Such compounds are said to be beneficial in the case of bruises and lacerations of the skin. * IchtJiyol, or fish oil, first prepared by SCHROTER, is the distil- lation product of a peculiar bituminous sulphurous mineral ob- tained from deposits of fossil fish. According to BAUMANN, sodium ichthyosulphate has the composition represented by the formula f DIMBLEBY, English patent 11,305, August 15, 1884; "J. Soc. Chem. Ind." 1885, p. 459. CHAPTER X. OLEIC-ACID, RED OB BROWN OIL, SOAPS- SOFT SOAP INDUSTRIAL SOAPS. Oleic-acid or Red Oil Soaps. OLETC-ACID, red or brown oil, is a bye-product of the candle manufacture, and, being already separated from glycerin, it readily enters into combination with alkalies, either caustic or carbonated. Morfit's Process. The red oil, or other fatty acid, is poured into an open pan, with a fire beneath, to one-third of the depth of the vessel, in which it is agitated and heated by the patentee's steam- twirl* If it is desired to make a ^grade of soap lower than toilet soap, rosin, in the proportion of 5 per cent, of the acid and upwards, is added in small lumps as soon as the oil has become hot. When, after con- tinued heating and stirring, the rosin is entirely dissolved, finely powdered carbonated alkali is added in quantity pro- portionate to the homogeneous mixture of fat and rosin, while the twirl is kept slowly revolving. When all the alkali is in, and the swelling-up caused by the escape of carbonic * This is a sort of rotatory paddle fixed inside the copper, tubu- lar, and perforated at intervals. It is connected by means of a hollow spindle with the boiler, so that steam can be admitted through it at will. Thus heating and mixing are effected simul- taneously. OLEIC-ACID SOAPS. 157 acid has subsided, the paste begins to thicken, and soon assumes the condition of soap. It is then removed to the- frames, and left to settle. For neutral soaps, the quantity of carbonated alkali should only slightly exceed the proper equivalent proportion, determined by calculation from the- combining number of the fat acid which constitutes the- " stock." For strong soaps the quantity of alkali may be increased. The advantages claimed for the preparation of soaps by MORFIT'S process are ( i ) As the relative proportions of the ingredients are adjusted at the beginning of the operation, there is no waste lye or any other residue. (2) The soap is said to come out promptly, and in greater perfection than can be readily obtained by the usual method of boiling upon caustic lye. (3) The product is always uniform in appear- ance and composition, and does not shrink or deteriorate by time and atmospheric influence. Another way of preparing this soap is the following: 1300 Ib. of soda lye of 18 B. are boiled in the copper, and to it are gradually added, with constant stirring, 1000 Ib. of red oil. The oil is rapidly taken up by the lye, and there is considerable intumescence, which has to be kept down by uninterrupted stirring. As long as the paste continues strongly caustic it must have new additions of oil till only slight alkalinity remains. If, on the other hand, after cooling for two or three hours in the copper, there is a deficiency of alkali, it must be heated with 50 or 60 Ib. more lye. The fire is then extinguished, and the paste, after an interval of about twenty-four hours, is removed to the frames, which should be very shallow, as this soap sets slowly. CARPENTER * describes MORFIT'S method for the prepara- tion of soap from fatty acids as follows : * SPON'S " Encyclopaedia," v. 1771. 158 SOAPS. The soda is used in the form of a refined carbonated ash at 52, every 100 Ib. being dissolved in 160 Ib. of 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 measur- ing tubes for the purpose of obtaining uniformity of results by the use of exact quantities in every operation. For the delivery of the soda solutions into the soap-pan a special feeder is provided, so that the flow of liquid may be regulated at discretion ; a perforated rose-spout may be advantageously placed under the exit pipe. The soap-pan is jacketed and furnished with a stirrer, and the steam is either superheated, or used at a pressure of 75-80 Ib. The pan has a movable curb above it, so as to give room for the increase of bulk caused by the liberated carbonic acid. The curb, when required, can be drawn aside on a railway. In making soap with this apparatus, 1000 Ib. of 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, for a neutral soap, 190 Ib. of soda ash, or, for a strong soap, 210-225 Ib., dissolved in the proper quantity of water, at 212 F. (100 C.), is let into the pan at such a speed that the time occupied is not less than six nor more than twelve minutes. The whole is kept well stirred, and swells up enormously ; but, in five minutes after the last portions of alkali have been added, the mass subsides, aiid, in fifteen, minutes more, changes from a spongy to a clear, soft, brilliant, homogeneous paste. The curb is then removed, and, in about an hour, 100 Ib. of boiling water are let in from the rose-spout of the soda-feeder, and the whole is again well stirred. If it is desired to add sodium silicate, or any other substance, it is introduced at this stage, after which the soap is transferred to the cooling frames, and a SOFT SOAP. 159 fresh batch is proceeded with. Soap thus made has the following composition : Water 27.50 per cent. Oleic acid .... 65.00 Soda . . . 6.70 to 7.50 When rosin is used, it should be added to the oil while the latter is being heated, or the rosin soap may be made in a separate pan provided with a MORFIT'S steam-twirl: 1200 Ib. rosin and 2200 Ib. caustic lyes at 11 B. are boiled together, and the thin jelly so produced is transferred in suitable quantities to other pans. This soap contains : Water 37.7 per cent. Rosin 54.5 Soda . . . . 7.8 According to MORFIT the refined ash of 52, prepared by the Jarrow Company, Newcastle-on-Tyne, has the following composition : Water i.oo Sand and silica traces Sodium chloride 2.84 ,, sulphate ..... 8.04 carbonate . . . 88.66 Total . . 100.54 Soft Soap. The article which is known as soft soap is not, strictly speaking, a true soap, but rather a more or less impure solution of potash soap in caustic lye, forming at ordinary temperatures a transparent smeary jelly. Soft soap is used to some extent for washing coarse linen, but it is of far greater importance, as an indispensable and powerful detergent, in linen-bleaching works. The fatty materials employed in this country for making 160 SOAPS. soft soaps are whale oil, seal oil, linseed oil, and tallow ; on the Continent, the drying oils, hemp, linseed, sesame, camelina, and poppy, and the non-drying oils, rape, train, live oil are generally employed for calico printing and dyeing, olive-oil soaps being sometimes pre- ferred for Turkey-red dyeing. A good soap for these in- dustries must be as neutral as possible, and thoroughly saponified. When soaps of the alkalies are used as mordants in con- junction with alum, or tin or lead compounds, there is a combination of alumina, tin, or lead with the fatty acids of the soap, and an insoluble metallic soap is deposited on the fibre. According to 0. SCHEURER^ a soap for brightening colours- such as alizarin, or garancin, should, first of all, produce a perfectly white ground, upon which the colour then appears-. much more brilliant, and, in the second place, it should not attack the colour itself. On comparing, from this point of view, the various soaps occurring in commerce, the Mar- seilles soap was found to be the best, although the reason for this superiority is not, at first, obvious. A soap which attacked the colours used to be regarded as too alkaline^ but on analysis it was found to contain no more alkali than the best soaps. It was especially the oleic-acid soaps which exhibited this injurious alkalinity attacking all shades of colour. This behaviour is attributed by SCHEURER to the * " J. Soc. Chem. Incl" 1882, p. 154. f "Bulletin de Mulhouse," 1882, p. 142; "J. Soc. Chem. IncV 1883, p. 286. INDUSTRIAL SOAPS. 165 fact that many so-called alkaline soaps made with oleic acid simply contain both free oleic acid and free alkali, because the saponification has not been complete. Such soaps may be perfected by continuing the boiling. It should be remembered that the combination of the acid and soda re- quires a considerable time two kinds of soap, an acid soap and a basic one, seem to be produced at the beginning of the process, and these gradually unite to form a neutral soap.* The reaction can be hastened either by increasing the temperature or the pressure; thus, at a pressure of 1.5 atmosphere SCHEURER found that a better soap is obtained in two hours than in twelve hours under ordinary pressure. A soap manufactured by DAUMAS D'ALLEON, of Marseilles, is recommended as the type of that best suited for dyeing and printing purposes. It has the following composition : Fatty acids 55 /-i x- -I ^.T ^N , (or Q.IOO parts Na.,0 Caustic soda (Na 2 0) . . . 6 | to * oo p ^ rts of f a 2 t Water 39 Total . .100 The following method is said to be successfully used at the Zawierciers Works for the preparation of a soap to be used in dyeing and printing : About 360 litres of water .and 69 kilos, of lye at 36 B. are boiled up together, and 140 kilos, of oleic acid added with constant stirring till a uniform mixture is obtained ; 3120 litres of water are then added, and the mixture is well stirred till a clear soap solu- tion results. "When the above proportions are used, the oleic acid is sometimes found to be in excess, and some more soda must then be added. To prevent this, a little more soda should be added at the beginning, f * See also p. 53. f " Dingl. Polyt. Jour." 247, 12 ; " J. Soc. Chem. Ind." 1883, p. 286. 1 66 SOAPS. Soap for Silk Throwsters.* This should be the best curd soap of the usual processes white, and free from- odour. Soap for Silk Dyers. The soap suitable for stripping and boiling off gum from silk is a brown-oil soap,* which should cleanse readily without injury to the silk, and be- easily rinsed out. It is usual to add to the soap a propor- tion of sodium sulphate. In the North of Europe f soft potash soaps, generally made from linseed oil, are used ; in the South, hard soda soaps made from olive and other oils are preferred. Of late years, soaps made from oleic acid have been increasingly used. In general, those which are made from oleic acid and linseed oil wash off best ; next, those from olive oil and suet, &c. Palm-oil soap does not rinse off so well. For scouring silk to be dyed, oleic-acid soap is most suitable, but for those destined to remain white a good olive-oil soap is preferable. According to CALVERT, the soft soaps usually made for dyers' use are not indiscriminately applicable to all colours. To produce the maximum effect in brightening the shade, the soap should be composed of For Madder Colours. Purples. Pinks. Fatty acids . . . 60.4 ... 59-23 Soda .... 5.6 ... 6.77 Water .... 34.0 ... 34.00 100.0 ... 100.00 Soap for Removing Stains. J 22 Ib. of the best white soap are reduced to thin shavings, and placed in a boiler together with water 8| Ib. and ox-gall 13^ Ib. Cover up, * MOBFIT. f SPON'S " Encyclopaedia, " ii. 519. j " Year Book of Pharmacy," 1885, p. 286. INDUSTRIAL SOAPS. 167 and allow to remain at rest all night. In the morning heat gently, and regulate so that the soap may dissolve without stirring. When the whole is homogeneous and dows smoothly, part of the water having been vaporized, add turpentine 9 oz. and benzine (best clear) 7| oz. Mix well, and, while still in the fused state, colour with ultra- marine, add ammonia, pour jiito moulds, and stand for a few days before using. The product is said to act ad- mirably. / Another formula-^ which requires more skill than the former to prevent the soap coming out unevenly, is the following: Cocoa-nut oil 27.5 lb., tallow 2.2 lb., soap- stone 4.4 lb., caustic-soda lye (sp.gr. 1.349) 15.4 lb., ox- gall 0.6 lb., turpentine 0.3 lb., benzine o.i lb., brilliant green o.i lb., ultramarine green 0.05 lb. Melt the fat,, add the soapstone and colour, cool to 68 F. (20 C.), and then add the solution of soda. When all is well united and mixed, add very gradually the gall, continuing the agita- tion, without intermission, for some time after all has been added. Should any separation take place, cover the boiler for a few seconds, and, if this does not help, fire up again, and continue stirring. Lastly, add the turpentine and benzine. Pour into moulds, and stand before using. This, preparation, when properly applied with a brush, is said to remove the most refractory stains without injury to the cloth. CHAPTER XI. VARIOUS SOAPS AND SOAP POWDERS. C. D. Abel's Process.* This process aims at the pro- duction of a hard soap which shall be practically almost completely freed from the lyes, and shall contain much less salt than ordinary curd soap, while at the same time a much harder and more neutral product is obtained, contain- ing also less water (from 20 to 25 per cent.) than that ob- tained in the ordinary way. The soap, separated by salt as usual, and before its separation from the lye by complete cooling has taken place, is introduced into a centrifugal machine driven at a high speed, and is subjected while hot to centrifugal action for from four to at most twenty minutes. By this means the separation of cocoa-nut-oil soap can be perfectly effected. Cold-water Soap. This is a recent make of soap which, as CARPENTER states,")" was at first made from very soft fatty materials, but containing a very small amount of water. It may also be made by drying "neat-soap," fitted in the ordinary way, till about one-third of its water has been driven off. Sometimes the term is applied to heavily watered soaps. Potassium and sodium carbonates are fre- quently added to increase the lathering property. * English patent 6,472, April 17, 1884; "J. Soc. Chem. Ind." 1885, p. 226. f " Soap, Candles, &c.," p. 195. VARIOUS SO APS. AND SOAP POWDERS. 169 The following is the composition of a genuine cold-water soap (CARPENTER) : Fatty acids . , , . ,70.2 Soda as soap ..... 7.3 in other forms . . .1.8 Silica ...... 1.6 Neutral salts ..... 0.4 Water . . . . . . 22.0 Total .... 103.3 Eichbaum's Soap. In order to make a soap from strongly smelling fish fats, F. EICHBAUM* takes 400 kilos. of the fat, 25 kilos, raw palm oil, 250 kilos, lye of 12 B., and warms up. A further similar amount of lye of 15 B. is added, and the thoroughly mixed mass allowed to boil till clear and free from scum, more lye being added when necessary. The mass is then poured in a thin stream through 20 lye, 50 kilos, powdered rosin are added gradually, and then 40 kilos, lye of 20, and the mass boiled. "When ready, the soap is salted in the ordinary way. The addition of the rosin is said to lessen the fishy smell considerably. Kottula's Compact Neutral Soap.f This soap is pre- pared by combining any of the usual fats or oils with con- centrated soda lyes and lime liquor. The soda lye is con- centrated to about 28 B., and purified by boiling for half an hour with alum, in the proportion of 4 to 4^ Ib. to every cwt. of lye. The vessel is then removed from the fire, alum again added, in the proportion of about 2 to 2J- Ib. to each cwt. of lye, and the liquid is stirred till the alum dissolves, after which the vessel is covered, and the whole is left to settle and become clear. The lime liquor is pre- * " J. Soc. Chem. Ind." 1886, p. 495. f KICHJLKDSON and WATTS, "Technology," vol. i. pt. iii. p. 721. 170 SOAPS. pared by combining water with lime, and then adding to each cwt. of lime liquor about i| to if Ib. of sal ammoniac. The liquid is boiled for about half an hour, and then allowed to settle and become clear ; or the sal ammoniac is added to the lime liquor while hot, and stirred for about half an hour. Ten tons of fatty matter, with or without rosin, 9 tons of lye prepared as above, and 13 tons of lime liquor will produce a superior compact neutral soap, which may be coloured, mottled, or perfumed by the usual processes. Kottula's Hand or Skin Soap. The fatty matters are mixed with highly concentrated soda lyes purified with a certain quantity of alum and sal ammoniac, whereby a neutral soap is said to be obtained cheaper and better than by any other process. The mode of procedure is thus described : " I prepare the highly concentrated lyes by boiling until they reach, say, about 30 to 33 B., add about 5 Ib. of alum to each cwt. of lye, and boil together for about half an hour. I remove the lyes and alum from the heat, and add to each cwt. i Ib. of sal ammoniac, stir for half an hour, cover, and allow the mass to settle and become perfectly clear. To obtain the lyes stronger than 33, I make a second addition of alum, but in smaller proportion. To obtain lyes of 42, I make a third addition of alum, and then add the sal ammoniac. I melt a quantity of any fatty matter used in soap-making, and, while still hot, stir, and add the lyes, prepared as before described, say, to every 100 Ib. of fatty matter, about 100 Ib. of 30 B., or 90 Ib. of 33 B., or 80 Ib. of 36 B., or 70 Ib. of 39 B., or 60 Ib. of 42 B. ; continue to agitate the mass till it becomes thick, and when thick it can be transferred to the frames. After the soap is finished, it may be coloured, mottled, or perfumed in the usual way." VARIOUS SOAPS AND SOAP POWDERS. 171 Preparation of Soap in Small Quantities.* The Greenbank Alkali Company, of St. Helens, Lancashire, prepare a refined 98 per cent, caustic soda in a fine powder, and pack it in cans holding from 10 Ib. to 4 cwt. This powdered article does not deliquesce or melt away like the ordinary solid caustic soda, and any quantity may be taken out as desired, and the remainder will not deteriorate, even if the package be left open for some 'days. No boiling pans are required, and it is perfectly easy to make a few pounds of soap at a time with this alkali. The following method, if exactly followed, will, it is claimed, always suc- ceed : 1. Take exactly 10 Ib. of double refined 98 per cent, caustic-soda powder (Greenbank), put it into any can or jar with 4^ gallons of water, stir it once or twice, when it will speedily dissolve and become quite hot. Let it stand until the lye thus made is cold. 2. Weigh out, and place in any convenient vessel for mixing, 75 Ib. of clean grease, tallow, or oil (not mineral oil). If grease or tallow be used, melt it slowly over a fire until it is liquid, and of a temperature not over 100 F. If oil be used, no heating is required. 3. Pour the lye, slowly into the melted fat, or oil, in a small stream continuously, at the same time stirring with a flat wooden stirrer about 3 inches broad. Continue gentle stirring until the lye and fat are thoroughly combined and appear of the consistence of honey. Do not stir too long^ or the mixture will separate again. The time required varies somewhat with the weather, and the kind of tallow, grease, or oil used j from fifteen to twenty minutes is gene- rally sufficient. * W. J. MENZIES, " Chemist and Druggist," 1880, p. 339. 172 SOAPS. 4. "When the mixing is completed, pour off the liquid soap into any sufficiently large square box for a mould, previously damping the sides with water so as to prevent the soap sticking. Wrap up the box well with old blankets, or, better still, leave it in a warm place until the next day, when the box will contain a block of 130 Ib. of soap, which can afterwards be cut up with a wire. If the grease or tallow be not clean, or contain salt, it must be rendered, or purified, by boiling with water, so as to throw out the impurities. The presence of salt would .spoil the operation entirely, but discoloured or rancid fat is quite admissible. If the soap turn out streaky and uneven, it has not been thoroughly mixed. If very sharp to the taste, too much soda has been taken; if soft, mild, and greasy, too little. In either case it must be thrown into a pan and brought to a boil with a little more w r ater. In the first case, boiling is all that is necessary; in the others, a little more oil or a little more soda must be added. Any smaller quantity of soap than the above may be made by taking the ingredients in smaller proportions, but it is not advisable to make more than double the quantity prescribed, as it is difficult to work more by hand. By working successive batches, however, a person could turn out 2 tons of soap in a day simply with apparatus obtain- able in any household. By adding a few drops of an essential oil just when the mixing is complete, a toilet soap is produced. Oil of mirbane (artificial almond oil) is the cheapest, but the perfume is not nearly so pleasant as real almond oil, citronella, or oil of cloves. When made with clean grease, or tallow, or light-coloured oil, the soap produced is quite white. VARIOUS SOAPS AND SOAP POWDERS. 173 Sand Soap. C. ROTH* recommends the following method to prepare a good sand soap : 100 Ib. of cocoa-nut oil are saponified with about 200 Ib. of lye at 20 B. The soap is then hardened by the addition of about 8 Ib. of salt dissolved in water to a density of 15 B., with the addition of 6 to 8 Ib. of soda ash. The mixture is now covered up and the foam allowed to subside. After standing five or six hours the foam is skimmed off, and from 100 to 150 Ib. of dry sifted sand is thoroughly crutched into the mass, and the crutching is continued till the whole is cool. The soap is very firm and hard. The soap is especially suited for the use of workmen en- gaged in rough and dirty avocations. If desired, it may be perfumed by the addition of 100 grams each of the essential oils of lavender, thyme, and coriander. Sodium Aluminate Soap. The Pennsylvania Salt Manufacturing Co. issue with their boxes of Natrona refined saponifier (see p. 32), the following directions for making soap without using scales, weights, or measures : " Cut out one end of this box, empty its contents into a pan, fill the box three times with cold water, and pour it on the saponifier, stirring until the latter is all dissolved. Into another pan introduce as much rendered grease or fat as will fill the same box five times. Now pour the dissolved saponifier into the rendered fat, and stir for a few minutes until thoroughly mixed. Let the whole stand till next day. Cut into small pieces, and pour in two more boxes of water. Heat and stir till the soap is all dissolved, and free from lumps. Remove the heat, and when cool cut into bars or cakes. " In very cold weather the water should be warmed a little. The rendered grease should be about as thick as honey, and not very hot." * " Seifensieder Zeitung," 1884, p. xxi. 174 SOAPS. Soap Powders.* Borax Soap Powder. Curd soap in powder 5 parts, soda ash 3 parts, sodium silicate 2 parts, borax (crude) i part. Each ingredient must be first thoroughly dried, and all mixed together by sieving. London Soap Powder. Yellow soap 6 parts, soda crystals 3 parts, pearl ash ij part, sodium sulphate ij part, palm oil (bleached) i part. These ingredients are mixed as well as possible without any water, spread out to dry, and then ground into coarse powder. The palm oil imparts an agreeable odour. Pearl Soap Powder. Curd soap (powdered) 4 parts, sal soda (crude sodium carbonate) 3 parts, sodium silicate 2 parts. Dried as much as possible, and intimately mixed. Soap Extract. Soap 14.3 parts, anhydrous soda 30 parts, and water 55 parts. Manufactured from crystallized soda and soda soap.f Washing Powder. A powdery mixture of 90 parts, effloresced soda with 10 parts of sodium hyposulphite and 2 parts of borax, f Wool-washing Composition. A mixture of 35 parts of dried soda, 10 parts of pow-dered soap, and 10 parts of sal ammoniac.f Universal Washing Powder. Sodium silicate, with a small percentage of soap and starch powder. f * " Chemist and Druggist," 1884, p. 73. f Ibid. 1879, p. 243. . CHAPTER XII. RECOVERY OP GLYCERIN PROM SPENT LYES. Spent Lyes contain variable quantities of water, glycerin, sodium chloride, sodium sulphate, sodium carbonate, caustic soda, and small quantities of albuminous, resinous, and soapy matters. The glycerin was formerly wasted, but of late years great attention has been devoted to its recovery, and many pro- cesses for that purpose have been patented. KINGZETT, in a valuable paper on this subject,* classes the various processes as designed to effect the following objects : i. To remove, or destroy, albuminous or soapy matters, together with any residual soap in the spent lyes. 2, To facilitate the removal of the salt, either by employ- ing means to diminish the solubility of the sodium chloride, in cases where that substance is used, or to substitute another which may be more readily and profitably removed. 3. To economize the cost of concentrating the lyes to that point at which the glycerin may be at once employed for certain purposes in its then crude condition, or still further purified by distillation. * " J. Soc. Chem. Ind." 1882, p. 78. 1 76 SOAPS. The following are some of the methods by which the separation of glycerin has been attempted : I. Allan's Method. Neutralize with any ordinary mineral acid. After settling, add alum and chloride of lime r or pyroligneous acid, and stir thoroughly, or, before addi- tion of the above, evaporate to the salting point. Distil with superheated steam in an apparatus furnished with an exit pipe for the removal of salt as it accumulates. II. Allen and Nickels' Method." Lancashire lyes," in addition to the impurities already mentioned, contain sulphides, hyposulphites, cyanides, ferrocyanides, sulpho- cyanides, &c., from the custom of saponifying with causti- cized Uack-ash liquor instead of by caustic soda. These impurities make the recovery of glycerin in a satisfactory condition from such lyes a very difficult operation. A. H. ALLEN, of Sheffield, and B. NICKELS, London, have re- cently, however, patented a process* which promises to overcome this difficulty. The process depends upon the factf that, when a solution of a copper salt (cuprous or cupric) is added to soap lyes previously rendered neutral or faintly acid, the sulphocyanides are wholly precipitated, together with any sulphides, cyanides, ferrocyanides, or silicates, and also with albuminous, resinous, fatty, colour- ing, and other organic matters. The precipitate settles with great facility, and the filtered liquid is obtained nearly colourless. The copper is recovered from the precipitate by roasting and treatment with sulphuric acid. According to ALLEN, the following equation expresses the main reaction which occurs in the removal of the sulpho- cyanides by a cupric salt : * English patent 11,069, August 31, 1886. f ALLEN, " J. Soc. Chem. Ind." 1887, p. 89. GL YCERIN FROM SPENT L YES. 1 77 6CuCl, + yNaCISTS + 4H 2 = Cupric Sodium Water choride sulphocyanide 6CuCNS + yKCl + 5HC1 + H 2 S0 4 + HCN Cuprous Potassium Hydrochloric Sulphuric Hydrocyanic sulphocyanide chloride acid acid acid. If the sulphur compounds are not removed, volatile organic sulphur compounds appear in the distilled glycerin, and unfit the product for the uses of the dynamite manu- facturer.* III. Benno, Jappe", & Co.'s Method. Instead of using sodium chloride to separate soap in the pan, Benno, Jappe, & Co. recommend the use of sodium sulphate. The lyes are then neutralized by acid sodium sulphate, and the salts removed by evaporation and filtration. The glycerin is then purified by distillation. IV. Clolus' Method. First neutralize with hydro- chloric acid; then remove sodium chloride by means of a turbine, or by dialysis; evaporate to 32 B.; pass hot air to render the glycerin anhydrous, in which the sodium chloride is insoluble, or nearly so ; or obtain anhydrous glycerin by evaporation in vacuo, and subsequent distillation. V. Fleming's Method.! FLEMING proposes to subject the spent lyes to dialysis. He shows that the four soap- works at Neuwied alone produce annually about 1500 tons of waste liquors, containing about 75 tons of glycerin. The percentage of glycerin in the lyes varies from 0.92 to 7.8. The most effectual means for removing the salts contained in the lyes previous to distillation is to subject them to osmotic motion. The lyes are concentrated in suitable pans by steam heat, and then neutralized by sulphuric acid. The quantity of acid required depends upon the amount of * ALLEN, " J. Soc. Chem. Ind." 1887, p. 88. f "Dingl. Polyt. Journ." ccxliii. 330-333 ; " Year Book of Phar- macy," 1882, p. 257. 178 SOAPS. sodium carbonate present in the lyes. As, owing to the vio- lent evolution of carbonic acid, it is difficult to obtain a perfectly neutral solution, it is preferable to add a slight excess of acid, which, after the precipitation and separation of the sodium sulphate, is removed by lime. The liquor is re-evaporated with steam, a further (small) quantity of sodium sulphate and chloride crystallizing out on cooling. It is now osmosed and concentrated, and, after this opera- tion, is sufficiently free from mineral constituents to be dis- tilled, either per se or in conjunction with crude glycerin obtained in the manufacture of stearic acid. The loss of glycerin by distillation is very small, and, as regards the purity of the resulting product, it is shown that it fulfils all the requirements necessary for the successful preparation of dynamite. The great feature of the process is that, unlike molasses, the liquor treated does not attack parch- ment paper. A large quantity of glycerin remains in the osmose water, and may be recovered by concentrating and distilling the liquid. FLEMING has also patented the use of a gutta-percha membrane, which, he states, is traversed by salt, but is im- permeable by glycerin. VI. O'FarrelTs Method. Evaporate and treat with methylated spirit, which dissolves the glycerin, and then distil. Or, the lye may be used again in the production of soap till a maximum of glycerin is obtained in a minimum of lye. VII. Payne's Method. Neutralize with hydrochloric, sulphuric, or nitric acids. Separate gelatinous and albu- minous matters by addition of tannin. Filter, concentrate, and distil off the glycerin. VIII. Reynolds' Method.* The lye is first concen- * Patent No. 1322, June 10, 1858. GL YCERIN FROM SPENT L YES. 1 79 trated by evaporation, and the saline matter, which gradually separates, is removed from time to time. When the fluid is sufficiently concentrated (ascertained by the boiling point having risen to 116 C.), it is transferred to a still, and the .glycerin distilled off by means of superheated steam intro- duced into the still. The distillate is next concentrated, and brought to the consistency of a syrup in a vacuum pan. If greater purity is required, it may be obtained by repeat- ing the process, and the little colour that remains may be removed by animal charcoal. IX. Thomas and Puller's Method. Neutralize, eva- porate and remove salts, and then add oleic, palmitic, or stearic acid. The neutral glycerides so obtained, after being washed, are treated, as in the candle industry, by the lime saponification process, or by superheated steam. X. Venables' Method. The liquor from the soap, -either before or after filtration, is neutralized by means of aluminium sulphate, alum, or any soluble salt of aluminium, or any substance containing soluble alumina. The sodium hydrate and carbonate, combining with the acid, precipitate the alumina, and the alumina, combining with some of the organic matters and carrying off the rest, purifies the lyes. Filter, and concentrate. Or, instead of only neutralizing, the salt of aluminium may be added till the lye becomes acid, and it may then be rendered alkaline by addition of caustic lime or any other alkali which may be found con- venient. The spent lyes may also be first partially neu- tralized by the addition of a small quantity of hydrochloric or sulphuric acid ; the remaining free sodium hydrate will then be neutralized by the aluminium salt, which may be added to exact neutrality or to excess ; in the latter case, the liquid should be afterwards neutralized, or rendered alkaline. Glycerin can then be obtained by distillation. XI. Versmann's Method. (i) The lyes are evaporated. i So SOAPS. until the liquor becomes so concentrated that the salts con- tained therein begin to crystallize out. (2) The liquor is then cooled, and filtered to get rid of gelatin and albumen. (3) Carbonic acid is then passed through the liquid* Sodium bicarbonate is precipitated, and this is separated in the usual way. (4) After undergoing this treatment, the liquor is made- to absorb gaseous hydrochloric acid until the remaining sodium carbonate is converted into chloride, and further until all, or almost all, the sodium chloride has been precipi- tated. (5) When the chloride has been separated, the liquor,, containing water, glycerin, and hydrochloric acid, is evapo- rated so as to get rid of the acid, which is absorbed in water for using afresh. (6) The dilute glycerin remaining can be purified by fil- tering through animal charcoal, or by concentrating and distilling.* XII. Young's Method. Evaporate the lyes by means. of superheated steam. Neutralize by sulphuric acid, add cal- cium carbonate, filter, and treat with a centrifugal machine (such as is used to separate sugar from molasses). Evaporate the separated crude glycerin, and distil. * VEBSMANX, " Chem. News," June 24, 1881. CHAPTER XIII. TESTING SOAPS. IT is impossible to know the real composition of a soap, and consequently its value, except by analysis. For many pur- poses it is sufficient to ascertain the proportion of water, fatty acids, and alkali, while for others a full analysis is -desirable. Samples. The sampling of soap for analysis requires ;great attention. The difficulties to be overcome are thus exemplified by R. S. TATLOCK :* A delivery of fifty boxes of Italian olive-oil soap has to be sampled, the goods being sold on the basis of 62 per cent, of fatty acids. The quality of the total contents of each box may be different. The proportion of valuable ingredients cannot be the same in every bar of a given box, from the fact that some of the bars have only their ends exposed to the outside, others their ends and one side, a third series their ends and two sides, while a fourth may be completely inside. Then, &gain, the bars selected for analysis, for the same reasons, are also in different conditions of dryness, and the sampling by the analyst of each bar for his working sample becomes a matter for grave consideration. The problem is, What ..proportion of the fifty boxes are to be opened, from what position in the box are the bars to be selected, and in what * " Journ. Soc. Chem. Ind." 1884, p. 307. 1 82 SOAPS. ways are the selected bars to be punched out so as to give an accurate average for analysis 1 Each i per cent, of fatty acids represents about i I2S. 6d. on every ;ioo value, but probably any hard-and-fast method would be com- pletely upset by the adoption of a different form or size of box. The following are some of the schemes that have been proposed for conducting the analysis of soap in a systematic manner : Dr. Leeds' Method.* (i) Water. Weigh out about 5 grams in very fine shavings on a dried, weighed, plaited filter. Dry at 110 C. till weight is constant. The loss is water. (2) Uncombined Fat. Transfer the filter containing the dried soap to a funnel connected with the return cooler, such as is used in the determination of the albuminoids in milk, and connect with the funnel a small tared flask con- taining 50 c.c. petroleum ether. Or, the filter may be placed in the ordinary Soxhlet apparatus. After complete extraction, distil off the ether, and the residue in the flask,, dried at 110, will be the uncombined fat. (3) Free Alkali, (4) Combined Alkali, (5) Glycerin. Allowing the filter with the soap, now free from water and uncombined fat, to remain in the apparatus, attach to it a flask containing about 75 c.c. of 95 per cent, alcohol, and extract. To the alcoholic solution add a few drops of phenol- phthalem ; if free alkali be present, neutralize with normal sulphuric acid, and calculate the amount of uncombined soda. (Free alkali, if present, may be detected qualita- tively, by applying to a freshly cut surface of soap a drop * "Chem. News," October 5, 1883, pp. 166-8; "3. Soc. Chem. Ind." 1883, p. 479. A tabular arrangement of Dr. LEEDS' scheme is. given on pp. 184, 185. TESTING SOAPS. 183 of mercurous nitrate, which will give a greyish tint, or a drop of phenol-phthalei'n, which will give a pink coloration.) After neutralization, add a large excess of water and boil off the alcohol. To the aqueous solution add a large excess of normal sulphuric acid, noting the quantity added. Boil, cool, and decant through a small filter ; wash with hot water, and decant, after cooling, through the filter until litmus-paper is no longer reddened by the washings. The filtrate contains the combined soda and the glycerin; the residue consists of the fatty acids and resin. Neutralize the filtrate with normal soda solution, and calculate the amount of combined soda as JSTa 2 0. Evaporate to dryness, and extract the glycerin with absolute alcohol. Transfer the alcoholic solution to a tared flask, distil off the alcohol, dry at 100 C., and weigh the residue as glycerin. (6) Fatty Acids and Resin. With a little petroleum ether, dissolve the small amount of the fatty acids and resin that may be on the filter through which the decantation w r as effected, add the solution to the larger bulk in the beaker, evaporate off the ether, dry at 100, and weigh the combined fatty acids. Multiply this result, after deducting the amount of resin, by 0.97; the product is the fatty anhydrides. (7) Resin. The resin is separated according to the method proposed by GLADDING.* About 0.5 gram of the mixture of fatty acids and resin, are dissolved in 20 c.c. of strong alcohol, and, with phenol-phthalem as an indicator, soda is run in to slight super-saturation. The alcoholic solution, after boiling for ten minutes to insure complete- saponification, is mixed with ether in a graduated cylinder till the volume is 100 c.c. To the alcoholic and ethereal solution i gram of very finely powdered neutral silver * " J. Soc. Chem. Ind." i. 205 ; " Chem. News," April 14, 1882. 1 84 SOAPS. Dr. Leeds' Scheme Weigh out 5 grams. Dry at Treat witl Residue is soap and minera Extract is soap (fatty anhydrides, resin, and combined alkali), glycerin and free alkali. Add 2 or 3 drops of phenol-pkthalei'n. If neces sary, titrate with normal sulphuric acid. Add a large excess of water, and boil off the alcohol. Decompose with excess of normal H 2 S0 4 . Note quantity added. Boil, filter, and wash. Filtrate. Combined soda Residue. Fatty acids and resin. Dry andglycerin. Titrate with at 110 C., and weigh. Dissolve ail normal soda solution. aliquot part in 20 c.c. strong alcohol, and, using phenol-phthalein as indi- H 2 SO 4 , in excess of soda, used cor- responds After titration with soda, evaporate to dryness on the water-bath. cator, saponify with soda in slight excess. Boil, cool, and add ether to 100 c.c. Decompose with AgNO 3 , in fine powder, shake well for ten minutes, and allow to settle. to com- bined soda .Treat with abso- lute alcohol. Precipi- Solution. Ecsinate of sil- in soap. Evaporate the tate is ver. Filter 50 c.c. from Calculate alcoholic solu- stearate, the total 100 c.c. De- as Na z O. tion to dryness in a tared basin, palmitate, andoleate compose with 20 C.C. HC1 (1:2). Allow the AgCl and weigh as of silver. to settle, and evaporate glycerin. an aliquot part of the ethereal solution in a tared dish. Dry at 110 C., and weigh. After applying the correc- tion for oleic acid, the weight corresponds to the resin. This weight, f subtracted from the com- bined weight of fatty acid and resin, gives the fatty acids. TESTING SOAPS. 185 'or Soap Analysis. oo C. Loss corresponds to water. )etroleum ether. constituents. Treat with alcohol. 1 Residue. Na 2 CO s , NaCl, Na 2 80 4 , sodium silicate, starch, and in- soluble residue. Wash with 60 c.c. water. Filtrate. Na 2 C0 3 , NaCl, Na^SO v and sodium silicate. Divide into four equal Residue. Starch and other insoluble matter. parts. Dry the filter, and weigh. Na 2 CO s . NaCl. Na 2 SO t . Sodium Starch.. Boil with dilute Titrate | with 1 normal H 2 S0 4 , and calculate as Na 2 C0 3 . Titrate with AgNO r or weigh as AgCl. Calculate as NaCl. Weigh as BaSO 4 . Calculate to silicate. Decompose with HC1, and deter- mine soda combined in silicate and silica. acid to convert into C 6 H 12 6 , and titrate by FEHLING'S solution. Sub- tract the weight of starch so found from the total residue. The difference is the insoluble mineral constituents. i . 1 86 SOAPS. nitrate is added, and the contents of the cylinder are shaken thoroughly for ten or fifteen minutes. After the precipitate has settled, 50 c.c. are measured off, and, if necessary, filtered into a second graduated cylinder. A little more silver nitrate is added to see if the precipitation is complete, and then 20 c.c. of dilute hydrochloric acid (i : 2) to decompose the silver resin ate. An aliquot part of the ethereal solution is evaporated in a tared dish and weighed as resin, deducting a small correction* (0.00235 gram for 10 c.c.) for oleic acid. The amount of resin subtracted from the combined weight of fatty acids and resin, as found before, gives the fatty acids. (8) Sodium Carbonate; (9) Sodium Chloride; (10) Sodium Sulphate; (n) Sodium Silicate. (12) Insoluble Residue. The filter in the funnel con- nected with the return cooler, after treatment with alcohol, contains the mineral constituents of the soap. The contents of the filter are washed with cold water till the washings amount to 60 c.c. The filter is then dried, and weighed. The weight gives the insoluble residue and starch. The starch is converted into glucose with dilute acid, and titrated with FEHLING'S solution. The weight of starch so found, subtracted from the total weight of insoluble residue and starch, gives the insoluble mineral constituents. The aqueous solution of 60 c.c. just mentioned is divided into four equal parts, in one of which is determined the sodium carbonate by titration, and, in the other parts, the chloride, * Dr. C. E. A.WRIGHT and C. THOMPSON (" J. Chem. Soc." 1886, p. 175) consider GLADDING' s process more satisfactory than any other for the estimation of resin, but they show that this correction-factor is by no means universally applicable. With pure stearic or oleic acid, it is much too large ; with acids from castor oil, far too small ; but with mixtures such as are likely to occur in the manufacture of soaps the results afforded appear to be not far from the truth. TESTING SOAPS. 187 the sulphate, and the silicate, respectively, by any convenient method. Pilsinger's Scheme.* (i) Water. In the case of hard soap, 5 grams, scraped from the sides and centre of a fresh section, are first very gently warmed, to avoid direct melt- ing, then over a water-bath, and finally in a drying box at 1 00 C., until the weight remains constant. For soft soap, 10 grams are taken, spread in a thin layer over a large watch-glass, and treated in the same way. (2) Vnsaponifiedt or Free, Fat. The dry residue from (i) is finely powdered, and washed on a filter three or four times with lukewarm petroleum ether. The filtrates are collected in a weighed beaker, evaporated, dried, and weighed. (3) Free Alkali. The residue from (2) is digested for a short time with alcohol (95 per cent.), slightly warmed, filtered, the residue on the filter washed with warm alcohol, and the filtrate, to which a few drops of a phenol-phthalei'n solution are added, titrated with - sulphuric acid. (4) Foreign Bodies. These are found, by the usual methods, together with the chlorides, sulphates, and car- bonates of the alkalies on the filter in (3). (5) Fatty Acids. The neutralized alcoholic solution from (3) is mixed with water in a moderate-sized porcelain basin, the fatty acids precipitated by sulphuric acid, and, after melting and settling, 5 grams of dry wax are added. When the whole is cool, the fat-acid wax is removed, washed with water and alcohol, dried without melting, and cooled. The weight 5 grams = the quantity of fatty acids. (6) Glycerin. The liquid from the cake of fatty acids is treated with a small excess of barium carbonate, heated, * " Chemiker Zeitung," April 17, 1884 ; " Chemist and Druggist,'" 1884, p. 290. 1 88 SOAPS. filtered, the filter washed with hot water, and the filtrate evaporated to dryness. The residue is repeatedly washed with alcoholic ether, the filtrate evaporated in a porcelain dish, dried at a temperature of 70 C., and weighed. (7) Total Alkali. 10 grams of another portion of soap, prepared as in (i), are dried in a platinum dish, and then heated till all the fatty acids have been destroyed. The porous carbonaceous residue is boiled with water, filtered into a -litre flask, and the filter washed with hot water till the washings cease to give an alkaline reaction. The bulk is then made up, the whole well mixed, and 25 c.c. ( = i gram soap) of the solution are titrated with sul- phuric acid. The result represents the amount of total alkali, and, after deducting the quantity of free alkali, found by (3), the remainder is the proportion of alkali combined with fatty acids, and existing as carbonate and silicate. (8) Chlorine. The neutral titrated solution from (7) may be used for the determination of chlorine by ~j silver solution. (9) Silicic Acid. 75 c.c. of the solution from (7) are treated with excess of hydrochloric acid, evaporated to dry- ness, treated with water, filtered, and the residue ignited and weighed as silica. (10) Sulphuric Acid. The filtrate from (9) is boiled, and, while boiling, barium chloride is added, the precipitated barium sulphate washed, dried, and weighed, and calculated as sodium, or potassium, sulphate. (n) Potash and Soda, if both are present, must be determined in the usual way by platinum chloride. In many methods of analysis met with in text-books, directions are given to weigh out for each operation small portions (i to 5 grams) of the sample. In a communica- tion from the laboratory, Owens College, Manchester, the TESTING SOAPS. 189 following objections are taken to this method :* 1. Soap is extremely variable in composition, and considerable varia- tions are possible in a single sample. 2. It is continually losing water by evaporation from its surface. As the soap is usually weighed in the form of thin shavings, the surface exposed is, in relation to the weight taken, very considerable. These two sources of inaccuracy may be obviated thus : A section is cut through the bar at right angles to its length, weighing 60 to 80 grams. This is dissolved in dis- tilled water by the aid of heat, and the bulk made up to i litre (at 60 F.). 50 c.c. are taken out for each of the following operations, immediately after well shaking the liquid, as some of the alkaline salts of the fatty acids separate out from the solution on cooling. i. Total Alkali. 50 c.c. of the solution are diluted to about 200 c.c., coloured faintly with eosine, and standard acid run in, taking care to stir briskly with a glass rod. The neutral point is extremely well marked by the decolor - ization of the whole. The cause of the disappearance of the colour is the union of the fatty acids with the eosine at the moment of their complete separation. 2. Unconibined Alkali. 50 c.c. are added to 300 c.c. of a saturated solution of common salt, which, of course, must be neutral to test-paper, and the volume made up to 400 c.c. The neutral alkaline salts of the fatty acids (i.e., true soap) are precipitated. Any excess of alkali present remains in solution, and is determined in an aliquot part of the nitrate. The filter must not be moistened previous to filtration. The total uncombined alkali is calculated therefrom, and deducted from the total alkali * " Chem. News," January 5, 1877; UKE'S "Dictionary," iv. 822. 190 SOAPS. already found. Thus the combined and unconibined alkali are determined. (This method is less reliable than the alcoholic treatment, pp. 182 and 187.) 3. Fatty Acids. 50 c.c. of the solution are introduced into a stoppered separating funnel, decomposed with excess of acid, and agitated with carbon disulphide until the liberated fatty acids are dissolved. The disulphide solution is then drawn off into a tared flask, and the aqueous solution is washed once or twice with small portions of disulphide, and the washings are added to the contents of the flask. The disulphide is then distilled or evaporated off. The fatty acids are purified from the last traces of carbon di- sulphide by heating the flask for a short time at 100 C. After cooling, the weight, less the tare of the flask, gives the weight of the fatty acids. Ether may be used instead of CS 2 , but there is this dis- advantage, that in the separator it will form the upper layer, whereas carbon disulphide forms the lower, and hence is more readily manipulated. 4. Water. The direct estimation is effected by evapora- ting 50 c.c. of the solution to dryness on the water-bath, -and finally in an air-bath at from 100 to 120 C. The residue is anhydrous soap, and from its weight the per- centage in the sample is calculated. When thin shavings of soap are dried in the usual manner, the author of the process considers that the last portions of water, amounting to from i to 2 per cent., are not driven off. 5. Mineral Impurities and Unsaponified Fat may be de- tected by taking the dried soap from the preceding opera- tion, dissolving in strong alcohol, and filtering through a funnel surrounded by a hot- water jacket. The former remain on the filter as an insoluble residue, the weight of which may be readily ascertained. TESTING SOAPS. 191 The alcoholic filtrate is evaporated with successive ad- ditions of distilled water. Any unsaponified fat or resin is thus separated from the soap, which remains in the aqueous solution. This solution may be used for i, 2, or 3. Estimation of Detergent Value of Soap. The following volumetric method affords a rapid means of comparing commercial soaps as to their respective deter- gent powers.* A standard soap is first chosen, by means of which the relative saponifying value of any other soap may be ascertained. The most suitable standard is the mottled Marseilles soap, generally known as Castile soap. The com- position of this soap is, in round numbers : Soda 6 Fatty acids 64 Water 30 100 i gram of this soap will be exactly neutralized by 0.1074 gram pure calcic chloride, or 10 grains by 1.074 grain. Therefore, a solution of 1.074 gram CaCl 2 in a litre of water, or 10.74 grains in 10,000 grains, will suffice to neutralize respectively 10 grams or 100 grains of the standard soap dissolved in the same volume. PONS f applies the above process in the following way : 1. 10 c.c. of the standard calcic solution are placed in a stoppered bottle holding 70-100 c.c. with about 20 c.c. distilled water. 2. 10 grams of the sample of soap are now treated with 100 c.c. alcohol (sp. gr. 0.825) by means of rubbing or shaking with gentle heat ; the real soap dissolves, and leaves all mineral or foreign matters, which may be filtered off, * BUTTON, " Volumetric Analysis," p. 53. f " Journ. de Pharm. et Chem." April 1865, p. 290. 192 SOAPS. and afterwards, if necessary, examined. The filtrate is diluted to i litre with distilled water. 3. This solution is then cautiously run from a burette into the 10 c.c. of lime solution, with frequent shaking, until a lather is obtained. 4. The 10 c.c. of lime solution divided by the number of c.c. of soap solution required will show the richness of the soap compared with the standard. Thus, if 10 c.c. only are used, the soap under examination is of the same quality as the standard; if 15 or 20 c.c. are required, the percentage will be yf x 1 00 = 66 per cent., or -Jg- x 100 = 50 per cent., and so on. A. H. ALLEN'S modification of this process is as follows : He ascertains what measure of a standard solution of the sample must be added to 50 c.c. of a very dilute solution of calcium chloride, or sulphate, solution, in order to obtain a persistent lather on shaking. The soap solution is made by dissolving 10 grams of the sample, as in the preceding method, in proof spirit (sp. gr. .920), filtering, and diluting the filtrate with proof spirit to i litre. The test is made exactly as in determining the hardness of waters, the soap solution being added to the standard hard water in small quantities at a time till a lather is obtained, on shaking,, which persists for at least five minutes when the bottle used for the operation is placed on its side. The standard hard water may be conveniently prepared by exactly neutralizing 40 c.c. of decinormal sulphuric or hydrochloric acid by cautious addition of lime water, and diluting the solution to i litre, when it will have a hardness of 14 degrees in. CLARK'S scale.* M. Cailletet's Method t of determining the Fatty * "Commercial Organic Analysis," second edition, ii. 250. f "Bulletin de la Societe industrielle de Mulhouse," No. 144, tome xxix. p. 8. TESTING SOAPS. 193 Acids. A standard acid is prepared by diluting 189.84 grams of strong sulphuric acid to i litre at 15 C. Of this acid 10 c.c. neutralize 1.2 gram of soda, and this quantity is therefore sufficient to decompose 10 grams of soap, as the amount of alkali present never exceeds 1 2 per cent. Into a tube of 50 c.c. capacity, and divided into 100 equal parts, are poured 10 c.c. of the standard acid and 20 c.c. of turpentine ; 10 grams of the sample in thin shavings are then added. The tube is then closed with the stopper, or with a good cork, well shaken for a few minutes till the soap is dissolved, and then left at rest for fifteen minutes, or till the oily solution of the liberated fatty acids has com- pletely separated from the watery liquid. In reading off the volume of the turpentine solution after the experiment, a deduction of half a division, or \ c.c., is made, to allow for the diminution of the capacity of the tube owing to the thin film of watery liquid which adheres to the inner surface of the tube. If the oily stratum occu- pies 53 divisions, or 26.5 c.c., then, deducting 20 c.c. for the volume of turpentine employed, the remainder, 6.5 c.c. (or 65 per cent.), is the volume of fatty acids in the soap.* Determination of Glycerin. Many methods have been proposed to effect this. The usual method is to dis- solve a known weight of soap in water, acidulate with sul- phuric acid, filter off the separated fatty acids, neutralize with sodium carbonate, evaporate to dryness, and treat the residue with strong alcohol, which dissolves glycerin, and leaves behind sodium salts. Dr. WRIGHT j* points out that this residue left on evaporation is rarely pure, most soaps containing small quantities of substances derived from the original fats and oils, which are soluble in the acidified * This x by their sp. gr. = percentage by weight. t Cantor Lectures on " Toilet Soaps," May 1885, p. 40. O 194 SOAPS. aqueous fluid, and thus become more or less dissolved out by the alcohol, so that soaps containing no trace of glycerin will still furnish small percentages of alcoholic extract when thus treated. Sodium chloride, being slightly soluble in ordinary alcohol, may also be contained in the extract. By re-dissolving the dried extract in absolute alcohol, and adding one and a half times its volume of ether, a certain amount of substances other than glycerin is generally pre- cipitated, but, in most cases, even this purification fails to yield pure glycerin, especially in presence of sugar. Dr. WEIGHT found the following method gave fairly accurate results : The aqueous acid solution obtained after separating the fatty acids as above described is rendered strongly alkaline with aqueous caustic soda, and then dilute .copper sulphate solution is dropped in with agitation, until the copper hydroxide thus formed begins to fail to dissolve. The filtered blue solution is compared calorimetrically with a known quantity of a standard solution of glycerin treated side by side in the same way. When sugar is present, the alcoholic extract, obtained as above, must be heated with dilute sulphuric or other acid, for some time, so as to invert the sugar. The fluid is then rendered alkaline, and copper sulphate dropped into the boiling liquid as long as suboxide of copper is reduced, after which the calorimetric estimation of the glycerin is proceeded with as before, the comparison being preferably made with a known solution of glycerin and cane sugar treated simultaneously with the sample under examination. With care and practice, fairly good results can be thus obtained, more especially when sugar is absent. The follow- ing figures illustrate the numbers which WRIGHT obtained jn analyses for glycerin, the values being percentages : TESTING SOAPS. 195 Nature of Soap. Crude Alcoholic Extract. Extract purified by Ether. Glycerin indicated by Copper Test. Opaque untinted soap, mo- . derate quality . 7.0 6.1 6.OO High-class Parisian glycerin [ soap, not transparent 8.1 7-9 S.oo Cold process soap .+ much unsaponified fat 6.6 4-9 4-75 British so-called glycerin soap, opaque 7-9 7-9 0.60 British transparent soap, without sugar . 19.0 17.6 15.00 Ditto + 10 per cent, of sugar 6.1 4.0 o.oo Dr. WRIGHT states that the entire absence of glycerin, from a toilet soap necessarily, proves that the whole mass has been prepared either by a boiling process, or by satu- rating a free fatty acid, as oleic acid, with alkali, or by both processes combined. On the other hand, the presence of a* quantity not far removed from the percentage of combined alkali, expressed as Na 2 0, suggests that the whole has been probably prepared by the cold process, for, as ordinary oils and fats are substantially tri-glycerides, i equivalent of fatty matter will yield 92 parts of glycerin, and fatty acids equivalent to 93 of ISTa 2 0. When larger quantities of .glycerin are present, extra glycerin must have been added to the materials during the manufacture of the soap. When small quantities only are present, constituting only a fraction of the percentage of combined alkali, expressed as Na 2 0, the soap is probably a blended mass, consisting partly of boiled #,nd partly of cold-process soaps. MUTER'S METHOD.* This may be used for the determina- tion of glycerin in soap and soap-lyes. The process is based * "Analyst," 1881, p. 41; "Year Book of Pharmacy," 1881, p, 121. O 2 196 SOAPS. on the power of glycerin to arrest the precipitation of cupric hydrate by alkalies. The modus operandi is as fol- lows : 1 i ) Take i gram of absolute glycerin and wash it into a long, stoppered, graduated tube, having a stop-cock at 50 c.c. from the bottom. (2) Add 50 c.c. of a strong solution of potassium hydrate (i in 2) and then a weak solution of cupric sulphate very gradually, and with constant shaking, until a fair amount of cupric hydrate is produced which remains undissolved ; make the whole up to a given bulk, close the tube, and set it aside to settle. (3) When perfectly clear, run off from the tap into a beaker a given volume of the deep-blue liquid, and add to it the slightest possible excess of nitric acid. (4) Pour in a definite excess of ammonium hydrate, bring the beaker under the burette charged with volu- metric solution of potassium cyanide, and run in till de- colorized. The number of c.c. of the cyanide used, after calcula- ting to the whole bulk originally in the tube, represents i gram of glycerin. The result has, however, to be corrected by going through a blank experiment, with the same amounts of everything, but without glycerin, and deducting the c.c. of cyanide taken from that previously found. This precaution is necessary because copper hydrate is not quite insoluble in the strong alkali, but, once made and deducted, "the difference gives the true value in glycerin of the cyanide solution, and, when that has been thus standardized, any number of estimations can be quickly made. The glycerin to be determined must first be isolated, as free from intermixture as possible, as previously de- scribed. TESTING SOAPS. 197 Determination of Carbolic Acid in Soap.* (i) 5 .grams of the soap are dissolved in warm water, with addition of from 20 to 30 c.c. of a 10 per cent, solution of caustic soda, according to the proportion of phenols believed to be present. (2) The cooled solution is then agitated with ether, and the ethereal layer separated and evaporated at a low tem- perature. The weight of the residue gives the amount of hydrocarbons, J Carbolic soft, 10 % M 10% 30.50 17.00 3-60 3-40 4.80 6.40 9.90 8.20 o. 16 Pure phenol 5) 5> Common carbolic 10 II 12 13 14 IS 16 17 Transparent carbolic ,, coal-tar No. i carbolic 5 > . . No. 2 , 1> ... Carbolic 3.20 1.50 2.50 5-40 4.40 3-50 2.60 I.IO Pure phenol Common carbolic Impure phenol Common carbolic 18 0.50 Impure 19 20 Disinfecting .... Sanitary .... none 0-75 Impure phenol Free Alkali in Toilet Soaps. In view of the objection- able effects produced by excess of alkalinity in toilet soap, and of the circumstance that the best British and foreign makes are found by analysis to contain only very small quantities of free alkali, expressed as anhydrous soda, Na,O, not exceeding 0.20 to 0.25 per cent, by weight (the com- TESTING SOAPS. 201 t>inecl alkali being usually 7 to 9 per cent., or some forty times as much), WRIGHT* classifies toilet soaps in three grades, from the point of view of the amount of free alkali present viz. : First Grade. Soaps which are, if not neutral, at any rate so devoid of free alkali that the amount of total alkaline matter present, in forms other than actual soap, does not exceed J^th part (2.5 per 100) of the alkali combined as soap. Second Grade. Soaps in which the free alkali, although exceeding the above limit, does not exceed -j 3 CO N Ti-VO ico.oo 111 || O co in t^ 8 8 ION (^ ci ci I ^&c*$ vo ^^ C? 00-001 if? g jj in o ci m CO 5 Ox 8 8 &. eg O>OO N Cf> 8 w" H 1 Kflvo" rn 8 d KN ll- |i- Sj| lii^ j| jjjj III 01 tl 5J1 r* TJ- ro 8 ^j n ONO J^ 8 d c? JK; o <> d "^~ OO'OOI r* | OVOC.C. 8 00 g 01 00 Ci vo H J 1 I O VO fO cooo t^ O 8 ? ^o fj. 00 H ^ 8 H w ^^ w n ^ ^ s 2 in in c co vo moo ON ^ co ci vo' 100.00 1 | g 5 ^ 3 "2 in m t>. in g H "o 0^00 ON 8 c? * * *,s o gg 5^=3 S. e?^ a ^5 1* l^ :a r^ liif si TESTING SOAPS. 203. on analysis ? " It is difficult always to do this with perfect accuracy. If, however, the percentages so obtained b& divided by 5, the quotient will be in cicts. per ton, and a calculation as to cost may then be made at the current prices of materials, as in the example given on p. 106. It is necessary, however, that judgment be exercised in form- ing conclusions from the results of such a calculation. PART II. CANDLES. CHAPTER I. DEFINITION AND HISTORY. Definition. A candle may be defined as a cylinder of fat surrounding a fibrous thread, or wick; "a contrivance in which, for the purposes of illumination, a wick of fibrous material is employed to effect the combustion of fatty bodies;"* "a wick surrounded by a coating of wax or tallow ;"f " a cylindrical or slightly conical rod, formed of solid fat, enclosing a bundle of parallel or twisted fibres of cotton, called the wick, through which the melted fat is drawn up to the region of combustion. "J The chief point of difference between a candle and a lamp is that in the former the fuel is a solid, which is gradually liquefied in the required quantity by the heat of the flame, whilst in the latter the fuel is, at common temperatures, a fluid. History. The early history of candles is involved in * "Jury Reports, Exhibition 1851," p. 615. f L. FIELD, Cantor Lectures, " Solid and Liquid Illuminating Agents," 1883, p. 7. J RICHARDSON and RONALD'S " Technology," vol. i. pt. ii. p. 425. 206 CANDLES. some obscurity. The Hebrew word translated candle in the Old Testament probably means lamp. Possibly the torch (Lat. tortium, a twisted thing) may have been the earliest form of the candle. PLINY * mentions that the books found in the grave of NUMA were in a box bound round with candles. These candles were, it is thought, pitched rope. PLINY also states f that the pith of " brittle rushes," which grow in marshy districts, separated from the rind, was used for making tuatc/i-candles and funeral lights to burn by dead bodies whilst lying above ground. He does not, however, say anything as to the nature of the fat employed, so that it cannot be certainly inferred whether the reference is to candles or to a kind of lamp. BECKMANNJ has recorded that the Emperor Constantine, about the beginning of the fourth century, caused the city of Constantinople to be illuminated with lamps and ivax candles on Christmas Eve. APULEIUS distinguishes wax and tallow candles by the terms cerei and sebacei. In the Saxon period we find that wax candles were not, as a rule, made by professional chandlers, because the well- known candles of King Alfred were manufactured by his chaplains, whom he commanded to supply wax in sufficient quantity, and to weigh it in such a manner, that, when there was so much of it in the scales as would equal the weight of seventy-two pence, six candles were to be made thereof, each of equal length ^ that each candle might have twelve divisions marked across it. Six of these candles, lighted in succession, burned exactly twenty-four hours. * " Natural History," xiii. 13. f Hid. xvi. 37. J " Hist, of Inven." BOHN'S ed., ii. 174. ASSER'S "Annals," translated for BOHN'S "Six Old English Chronicles," p. 84. .HISTORY. 207 FOSBROOKE* states that in the Middle Ages wax candles were made of various sizes, some exceedingly small, and others weighing as much as 50 lb. He also states that they were made in moulds, and that the wicks were formed of twisted tow. According to DUCANGE, persons who made and sold candles, or candelarii, were known in the middle of the thirteenth century. In the fifteenth century " mould " candles were intro- duced by the Sieur DE BREZ. GILBERT WHITE, writing in 1789, thus describes the method of making rush candles practised in Hampshire : The proper species of rush for this purpose seems to be the Juncus conglomeratus, or common soft rush, which is to be found in most moist pastures, by the sides of streams, and under hedges. These rushes are in best condition in the height of summer ; but may be gathered, so as to serve the purpose well, quite on to autumn. As soon as they are cut, they must be flung into water and kept there, for otherwise they will dry and shrink, and the peel will not run. At first a person would find it no easy matter to divest a rush of its peel or rind so as to leave one regular, narrow, even rib, from top to bottom, that may support the pith ; but this, like other feats, soon becomes familiar, even to children. When the rushes are thus far prepared, they must lie out on the grass to be bleached and take the dew for some nights, and afterwards be dried in the sun. Some address is required in dipping them in the scalding fat, or grease, but this knack also is to be attained by practice. 1600 rushes, weighing i lb., are coated with 6 lb. of tallow, so that 228 lights weigh i lb. and cost a little over 5^.t * " Encyclop. Antiq." p. 472. f "Natural History of Selborne,' 7 p. 220. 208 CANDLES, In the year 1799 WILLIAM BOLTS took out a patent in England for improving the form, quality, and use of the candle, the specification of which probably contains the first account of an attempt to improve the quality of candles made from tallow and other animal fats, by subjecting the material to a considerable pressure during the act of cool- ing, and which is, in effect, the preparation of the so-called stearin from fats. He likewise describes a solid candle with a short wick, which is placed in a holder, and kept pressed on the end of the candle by a spring, or else the candle is placed in a tube and pressed against the wick by a spiral spring ; as well as other contrivances, some of which have been revived and successfully carried out in our own days.* In 1830 the number of candle-makers in Great Britain was 2695, who paid ^500,048 145. id. duty; since the repeal of the duty in that year no record has been kept of their number. Yery little improvement took place in the manufacture of candles till after the discovery by CHEVREUL of the true nature of fats (see p. 51). In 1825 GAY-LUSSAC and CHEVREUL took out a patent for making stearic acid candles the badly combustible glycerin being removed, and the oleic acid being separated to be used in soap-making. But it was not till 1834 that they maybe said to have succeeded in making their candles perfect. The kernels of the candle-nut tree (Aleurites moh(.ccana r Willd.), a native of the islands of the Pacific, are used in Fiji, the Hawaiian Islands, and Tahiti, when threaded on the mid-rib of a palm leaf, reed, or stick of wood, as a sub- stitute for candles. In Tahiti and Fiji the tree is called Futui, and Doodoe is its title in Pitcairn's Island. In the * "Jury Reports, Exhibition 1851," p. 617. HISTORY. 209 history of the " Mutiny of the Bounty " it is stated that the rooms in Pitcairn's Island were lighted up with torches made of doodoe nuts strung upon the fibres of the palm leaf. The nuts are also so strung and used by the Sans Bias Indians in Central America, and a child is in attendance to knock off each nut as it burns out. Each nut burns about ten minutes.* They yield a light which was considered good a century ago, but is now thought dull, smoky, and ill- smelling. In Java the kernels are cleaned, crushed, and mixed with sufficient cotton or cocoa-nut fibre to give them the con- sistence of stiff suet. This paste is then rolled round a split reed or bamboo to form a kind of candle or torch. These burn more regularly than the contrivance just men- tioned, but they consume more rapidly than tallow candles, and give out an unpleasant odour, so that they are used only by the poorer classes. This tree must not be con- founded with the candle tree (Parmentiera cerifera) nor with the candle-berry tree (Myrica cerifera).^ * M. C. COOKE, " London Medical Kecord," 1860. f " Chemist and Druggist," 1879, p. 149. CHAPTER II. MATERIALS AND THEIR PREPARATION. Materials. THE materials chiefly used in the manufacture of candles are the following : 1. Animal Fats. Tallow; lard; stearin. 2. Vegetable Oils. Cocoa-nut oil ; palm-oil and palm- kernel oil ; piney oil, or tallow. 3. Waxes. (a) Animal. Bees'-wax; Pela, or Chinese wax; spermaceti. (b) Vegetable. Carnauba; Chinese vegetable tallow ; Japan ; myrtle ; palm. (c) Mineral. Paraffin; ozokerit. 4. Patty Acids. Coco-stearic acid ; palmitic acid ; stearic acid. i. Animal Pats. TALLOW. This has already been spoken of in treating of soap (p. 18), and various processes for its purification have been described (pp. 32, 39-43). Tallow consists chiefly of Stearin stearic glyceride, C 3 H 5 (C 18 H 35 2 ) 3 ; Palmitin palmitic glyceride, C 3 H 5 (C 16 H 31 2 ) 3 ; and Olein oleic glyceride, C 3 H 5 (C 18 H 33 2 ) 3 the first predominating, but varying in proportion accord- ing to the species, age, food, &c., of the animal from which it is obtained. The greater the proportion of stearin, the harder will be the fat and the higher its melting point. MATERIALS. 21 r The two great and inherent disadvantages of tallow as a candle material are due to the presence in it of fluid olein, and to the glycerin in combination with stearic anhydride in the stearin. The former lowers the melting point of the fat, and produces a great tendency in the candle to gutter, while the glycerin, both of the olein and of the stearin, being with difficulty consumed, diminishes the intensity of the light, and at the same time causes an unpleasant odour, by giving off, as a product of combustion, the highly pungent acrolein (C 2 H 3 .COH), which is very perceptible when a tallow candle is blown out. The setting point of tallow is found for technical purposes as for paraffin (English method), p. 229. LARD. Seep. 18. STEARIN. Seep. 231. 2. Vegetable Oils or Pats. COCOA-NUT OIL (see p. 21). This oil or fat is now more utilized for night-lights than for the manufacture of candles. Candles have been made from it, but not satisfactorily ; the untreated fat has too low a melting point, and the presence of glycerin makes it as objectionable as tallow. The caproic and caprylic acids also give rise to unpleasant odours. The chief brands are Cochin and Ceylon, of which the former is the whiter and .sweeter, and is therefore more suitable than the latfcer for night-lights. PALM OIL (see p. 22). Lagos oil is the brand command- ing the highest price. Other brands are Brass, Bonny, Old and New Calabar, Whydah, Accra, &c. PALM-KERNEL OIL (see p. 22). PINEY OIL, OR TALLOW. This is obtained by roasting, grinding, and boiling with water the seeds of Vateria, indica, or piney tree. The oil rises to the surface and is skimmed off. When cold it is a solid fat, melting at about 95 to 97 F. (35-36 C.), sp. gr. 0.926. Colour, white or pale yellow, and odour somewhat fragrant. P 2 212 CANDLES. 4. Waxes. The substances known as waxes are ob- tained partly from animal and partly from vegetable sources.. The term wax was formerly confined to bees'-wax, but candles. are now frequently called wax candles, though made from solid paraffin, or paraffin ivax. Waxes proper chiefly consist of members highest in the series of fatty acids, C n H 2n 2 , partly free and partly in combination with alcohol radicals. They differ from fats. in being less readily saponified, and in yielding no glycerin when so treated. The soap formed is also very sparingly- soluble in water. The waxes are solid at common temperatures melt below the temperature of boiling water are sparingly soluble or insoluble in water soluble in ether, chloroform, carbon di- sulphide, and in the volatile and fixed oils. Animal Waxes. BEES'-WAX. This is obtained by melting the honeycomb in water after the honey has been removed, straining the liquid mass, re-melting the defe- cated portion, and then casting into cakes, or discs. Pure bees'-wax has a pleasant odour, a pale yellowish- brown colour, and a specific gravity of 0.960 to 0.969. It is brittle at 32 F. (o C.), softens and becomes plastic at 88 to 90 F. (31.1-32.2 C.), and melts at 145 to 155 F. (62.77-68.3 C.). As met with in commerce, the wax varies in colour from very pale yellow, or almost white, to a dark mahogany shade. But, however different in colour, and from what- ever country obtained, the chemical composition, according to HEHNER, who has very thoroughly investigated it,* does not vary to any great extent. The following are HEHNER'S results from the analyses of eighteen samples of English wax : * "Analyst," 1883, p. 16. MATERIALS. 213 Average. Free add, calculatedas : cerorig j from I3 to lfi 0/o = ^ fiqponifidble matter, calculated } as myricin, [ 86 to 89.6 % = 8.09 C 16 H 31 (C 30 H 61 )CX J Myricyl palmitate Total 102.49 In all cases the sum of the cerotic acid plus myricin is higher than 100, the average being as given above. The tendency of these figures is to show that English bees'-wax -consists almost completely of cerotic acid and myricin, but that it also contains a small quantity of a substance of a lower molecular weight, probably the cerolein of LEWY. In the case of seventeen foreign samples the fluctuation, of composition was found to be more considerable than the above, but this HEHNER considers to be due to a greater degree of sophistication. Before wax is employed for the manufacture of candles it is necessary to bleach it. All waxes do not bleach with qual facility. According to BARCLAY, English, Hamburgh, Odessa, Portuguese, Mogadore, Zanzibar, East and West Indian, and North American waxes bleach readily, while those from Cuba, Dantzig, Konigsberg, Gambia, and Gaboon are only bleached with difficulty, and seldom acquire a good colour. There are two methods of bleaching wax (a) Atmospheric; {b) Chemical. (a) Atmospheric Bleaching. 1. The wax is cut up into .small pieces and placed in a vat, into which steam is ad- mitted through a perforated coil. A small quantity of very dilute sulphuric acid (in the proportion of i pint of strong acid for each ton of wax) is added, and the whole boiled and well agitated for some time. The impurities separate and subside. This operation is called " clearing down." 2. The melted, bright wax is next caused to pass into a tank, the bottom of which is perforated with holes about 214 CANDLES. the size of an ordinary quill. Through these holes it trickles in thin streams on to a revolving cylinder, or drum, half of which is immersed in a cistern of cold water. The motion of the cylinder carries up a layer of water, on which the wax falls, and becomes divided into exceedingly thin ribbons. These ribbons, by the revolution of the cylinder, are carried under the water, and are removed by a rake as they rise to the surface. 3. The ribbons are then spread evenly and thinly on long canvas sheets, and placed in the open air, so as to be ex- posed to the influence of the sun and air, for a period vary- ing from about four to ten weeks, according to the weather. Frequent turning is required so as to expose every portion to the sunlight, and frequent sprinkling with water is also necessary. Once, or perhaps twice, during the period men- tioned, the wax is re-melted, separated into threads again, and spread out as at first. It has been observed that in rainy weather the wax gets a greyish tinge, which cannot afterwards be removed. A wax that yields to the atmospheric process is termed kind, while one that is not so readily bleached is called stubborn. (b) Chemical Bleaching. Wax may be bleached by chlorine, or by bleaching powder, or by WATTS' chrome pro- cess. When chlorine is used, substitution products are formed ; and when the wax is subsequently burnt, hydrochloric acid is given off. The greenish colour which remains after the chrome process may be removed by boiling the wax several times with solution of oxalic acid. When treated by these methods, wax becomes highly crystalline, and is unsuitable for candle-making. Hence these methods need not be here described.* * For WATTS' chrome process, and other methods, see " Oils and Yarnishes," pp. 192-200. MATERIALS. 215 PE-LA, PIH-LA, OR CHINESE WAX. This is produced upon the young branches of Fraxinus chinensis, or wax tree, by an insect (Coccus pe-lci). On being scraped from the trees, the crude material is freed from impurities by spreading it on a strainer, covering a cylindrical vessel which is placed in a caldron of boiling water. The wax is received into the former vessel, and, on congealing, is ready for the market. It is perfectly white, translucent, and shining. It has a marked crystalline structure, and melts at about 82-83 G. (180 F.). It is much harder than spermaceti, and not unctuous to the touch. Its sp. gr. is 0.8090.811. It is tasteless and inodorous, and crumbles into a dry inadhesive powder between the teeth. It is soluble in essential oils and naphtha, insoluble in water, and scarcely affected by boiling alcohol, acids, or alkalies. Chemically it is cerylic cerotate (C 27 H 55 .C 2? H 53 OJ. The quantity which finds its way to this country is now very small. In China, candles are made of the substance itself, but it is more commonly mixed with softer fats, and used for coat- ing more easily fusible material, thus preventing guttering. It is often coloured red with alkanet root, and sometimes green with verdigris.* SPERMACETI. This is the solid fat which is dissolved in sperm oil in the head-cavity of the sperm whale, or cachalot (Physeter macroceplialus}, and which, after death, separates as a solid. The name appears to have been given under the erroneous belief that the substance was the spaivn of the whale tribe (sperma ceti). The head-matter, as it is called, is not the only source of spermaceti, as the blubber or body- fat, after melting and cooling, also yields a deposit of it. The following is an outline of the method of separating the crystals of spermaceti from the oil : t * RONALDS and RICHARDSON, " Technology," vol. i. pt. ii. p. 464. f "Jury Reports, Exhibition 1851," p. 626. 216 CANDLES. 1. Bagging. The oil is filtered through long cylinders of bagging, lined with linen, tied, at one end, to the nozzle of a feed-pipe communicating with a tank elevated about 6 feet, and, at the other end, tied up with string. The oil, pressed upon by the weight of its own column, readily passes through, while the bags retain the solid portion. The spermaceti, at this stage, is of a dingy-brownish colour, and is called bagged sperm. 2. first, Pressing. The bagged sperm is next placed in hempen sacks, and subjected to a pressure of about 80 tons in a hydraulic press, by which the greater portion of the adhering oil is removed. 3. Second Pressing. The pressed sperm is now melted and crystallized by slow cooling, and, after being ground to powder, is folded up in square pieces of bagging and then subjected to the action of a much larger hydraulic press, capable of exerting a force of 600 tons. The oil which runs from this press contains a small quantity of spermaceti, and is therefore returned to the bags to be filtered. 4. first Refining. The spermaceti is next melted in a large iron vessel, and boiled for some time with a solution of caustic soda or potash, which readily saponifies the sperm oil still adhering to the spermaceti, whilst it has scarcely any action on the spermaceti itself. By this means the sperm oil is removed in the form of soap. 5. Hot-pressing. The purified spermaceti is next removed from the boiler, and run into flat tin-moulds to crystallize. It is then again ground to powder, placed in linen bags, interleaved with horse-hair mats and previously heated iron plates, and pressed in a horizontal hydraulic press, heated by steam. 6. Second Refining. The hot-pressed spermaceti is now removed and boiled with a strong alkaline lye, the tempera- ture reaching 235 F. (113 C.). By this final operation it MATERIALS. 217 Incomes as colourless as water, and has only to be cast into blocks for the convenience of storing. Spermaceti, thus purified, consists mainly of cetylic palmi- tate (C 16 H 33 .C 16 H 31 O 2 ). It is white, scaly, brittle, neutral, inodorous, and nearly tasteless. Its sp. gr. is 0.943 at 15 C., and it melts at about 110 to 120 F. (43.3 48.8 C.). Vegetable "Waxes. CARNAUBA, OR STONE-WAX. This occurs as a thin film on the leaves, stalks, and berries of the Carnauba palm (Copernicia cerifera), a native of Brazil. The leaves, &c., are collected and dried, and the wax can then be peeled or boiled off, melted in earthen pots, and turned out when cold. It is of a yellowish colour, and very hard and brittle. "When bleached, it is quite white. Its sp. gr. is about 0.995-1.000 and its melting point 182 185 F. (83.3-84.9 C.). ^ Its chemical composition is uncertain. STURCKE* found it to contain myricyl alcohol (C 30 H 62 0), free and in com- bination as myricyl cerotate, to the extent of about 45 per cent. It is used sometimes to harden candles, but only in very small quantity, as 2 per cent, of the wax would cause the candle to crack. Heel-balls, for rubbing on the heels of boots, &c., contain 50 to 60 per cent, of this wax mixed with a little blacking, rosin, and soft wax. CHINESE VEGETABLE TALLOW. This is found enveloping the kernels in the nuts of Stillingia sebifera (Exccecaria, sebifera, Mull.). According to Dr. PORTER SMITH, the fat is obtained in China from the seeds in the following manner : (i) The ripe nuts are bruised and the pericarp separated by sifting. (2) They are then steamed in wooden cylinders, with * LIEBIG'S "Annalen," ccxxiii. 283-314; "Year Book of Phar- macy," 1885, p. 204. 21 8 CANDLES. numerous holes at the bottom, which fit upon kettles or boilers. The tallow is softened by this operation. (3) The mass is then gently beaten with stone mallets, to separate the tallow from the albumen of the seeds, and afterwards sifted through hot sieves. (4) To remove the still remaining brown testa of the seeds, the tallow is poured into a cylinder made up of straw rings put one on the top of the other, the whole placed in a rude press, and the tallow squeezed through in a pure state. The product is a hard, white, tasteless, odourless solid. It chiefly consists of tri-palmitin. Its melting point is about 104 F. JAPAN WAI. Although called wax, this substance is, strictly speaking, a fat, as it consists of palmitin or gly- cerin palmitate. The chief sources from which it is com- mercially obtained are Ehus succedanea and Rhus verni- cifera, which, according to Prof. J. REIN, of Marburg, were introduced into Japan probably from the Loochoo Islands. According to A. MEYER,* the most usual plan for obtain- ing the wax is the following : The previously well-dried fruits are ground either by mill-stones, or with w r ooden pestles in mortars, or by bamboo-flails. The shells and epi- dermis are separated by sifting and winnowing, and the mass is then heated in canvas bags over boiling water, in order to melt the fat, which is then pressed out. The crude tallow is now boiled with dilute lye, whereby it becomes granular and more readily bleached. The bleaching by sunlight and subsequent melting are repeated till the pro- duct is pure and white. 400 Ib. of seeds will yield 100 Ib. of wax. "When freshly broken, the fractured surface of the im- ported article is almost white, or, sometimes, slightly yellow- * " Year Book of Pharmacy," 1880, p. 220. MATERIALS. 219- ish-green. Its odour is like that of tallow, and disagree- able. Its sp. gr. is 0.916 (MEYER), 0.99 (FIELD*), 0.984- 0.993 at I 5 C. (ALLEN). It melts at 52-53 C. (125.6- 127.4 F.) (MEYER) when old, and about 42 C. (about 107.6 F.) when recently solidified. According to FIELD, its melting point is 48.89 C. (120 F.). According to other observers, its melting point varies from 120* to 130 F. As it contains glycerin, it gives off the smell of acrolein during combustion. MYRTLE WAX (MYRICA WAX, MYRTLE TALLOW, OR BERRY WAX) is a solid fat of a pale-green colour obtained by boiling off the coating of the berries of Myrica cerifcra in Louisiana, and of Myrica cordifolia at the Cape of Good Hope. Its sp. gr. is 1.005, and its melting point 47-49 CL (116.6120.2 F.) (MOORE). It contains palmitic and my- ristic acids, with a little glycerin, but its exact composi- tion appears not to have been yet ascertained. Candles made from this wax were exhibited at the Colonial and Indian Exhibition, 1886, by Messrs. Hall & Zinn, of the Cape of Good Hope. They burned with a smoky flame and with a strong odour of tallow, but without guttering, f PALM WAX. From the trunk of Ceroxylon andicola. It does not melt below the temperature of boiling water, according to some observers, but according to others the melting point varies from 161.6-186.8 F. (72-86 C.). c. Mineral Waxes. PARAFFIN is found native, or is obtained by the distillation of petroleum, bituminous shales, caniiel coal, lignite, wood-tar, or peat.J jRefining Paraffin. There are several methods practised * Cantor Lectures on "Solid and Liquid Illuminating Agents, ' r 1883, p. 18. f " Colonial and Indian Exhibition Reports, 1887," p. 276. J For details of preparation, see " Oils and Varnishes," p. 153 et 220 CANDLES. for effecting the purification of crude paraffin. In some of these naphtha is used, in others it is dispensed with. The following process is a combination of the action of naphtha and hot-pressing, by which the quantity of naphtha, which has a powerful solvent action on paraffin wax, is much reduced : 1. The crude solid is placed in a centrifugal machine, by which paraffin oil is expelled. 2. The residual mass is cast into cakes, placed in layers on cocoa-nut matting, on hollow iron plates containing water to regulate temperature, and submitted to hydraulic pres- sure. As much as possible is squeezed out in the cold, and then the temperature is raised gradually to from 35 to 40 C., by which means the paraffins of lower melting points .are squeezed out, the object being to produce a solid with a high melting point, so as to make it approximate to the character of wax or spermaceti. This operation leaves the cakes of a dark-brown colour. 3. To further purify these cakes, they are melted, heated to 155 C., and 2 per cent, of sulphuric acid added, to remove any bodies of the C 11 H 2n series, or olefines, still present. 4. The cakes are again melted with soda, cooled, and re- pressed. They are then well washed with hot water, cooled, mixed with cold colourless naphtha to assist filtration, and then filtered through animal charcoal to remove colouring matters. 5. The product is next placed in steam-jacketed wrought- iron cylinders, and superheated steam is passed through to remove naphtha. The residue is then pressed, and cast into cakes. Another way of carrying out the naphtha process is to melt the scale with a certain proportion of naphtha. The mixture is then either allowed to cool in suitable vessels, or MATERIALS, 221 It may be cooled by artificial means. The cooled mixture is subjected to hydraulic pressure, when the objectionable portion is carried away by the naphtha. This operation is repeated two or three times, or until the desired degree of purity is obtained. Diagram A. (p. 222) will make the process clear.* In some refineries t the following method, called the sweating process, is adopted: The crude paraffin scale is melted and heated to a temperature of 170-180 F., after which it is allowed to repose until every trace of water and separable impurity has settled out, the presence of which would hinder crystallization. It is run into cooling pans, which hold from i to 2 gallons ; these pans are generally furnished with overflows, and are arranged as shown at A (Fig. 39, p. 223). A stream of melted paraffin is directed into the top pans by the taps b, and is continued until the whole vertical series is full. They are then left to cool very slowly in order to promote crystallization. When cold, the solid cakes of paraffin are taken out of the pans and placed in the ovens, which are fitted with shelves, the latter having a slight inclination to the one corner, on which is laid a coarse mat of cocoa-nut fibre to prevent the paraffin from being in direct contact with the metal surface. The cakes are ex- posed to heat until the desired degree of purity and melting point is attained, the source of heat being a course of steam pipes laid on the floor of the ovens. The portion that has been fused out of the paraffin in the course of sweating is again treated in the same manner, only at a lower tempera- ture suited to its mean melting point. The drainings from this latter cannot again be very profitably sweated, as they contain the whole of the oil originally present in the scale, * K. TERVET, " Journ. Soc. Chem. Ind." 1887, p. 356. f "Journ. Soc. Chem. Ind." 1887, p. 356. 222 CANDLES. ,2ft 1 I ca '"^ tfg. , a^ o3 OO S = 3/^\ I ^ IpK s^r a MATERIALS. 223 224 CANDLES. and also the greater proportion of paraffins of low melting points. It is therefore cooled in a separate series of pans, and then hydraulic-pressed to get rid of the oil. The solid pressed paraffin obtained is either returned to the next make of crude scale, or it may be finished off separately as a low melting-point wax (mean melting point 102 F.). It is usual to allow a certain proportion of the paraffin of intermediate melting points to pass to this stage, in order to give solidity and maintain a suitable melting point for the finished product. Diagram B. (p. 225) gives in outline the several stages of this process.* An improvement in the above method, designed to econo- mize labour, is described by K. TERVET.t By reference to Fig. 39, it will be seen that the coolers are set directly above the cells in which the sweating is conducted. The cooling and sweating cells may be made of any convenient size they may be 3 feet broad by 6 feet high. The way in which the coolers are sealed at the bottom is made to depend upon the shape in which the alternate strips of soft wood and iron, or soft and hard wood, are placed, and which extend right across the lower openings. It is evident when pres- sure is applied by screws, or otherwise, to the side A, which forms the end of the system, the strips of soft wood, which go to cover the openings of the cells, will rise slightly, while the iron strips, which cover the blank spaces between, will correspondingly fall. In practice this arrangement is found more than sufficient to seal the openings of the coolers. To empty the coolers it is only necessary to relax the screws, 6, and draw forward the strips of wood when the * K. TEBVET, " Journ. Soc. Chem. Ind." 1887, p. 357. f Hid. MATERIALS. 225 i ~ I P- 1 v^x O 1 -* 1 .si i ij Sj S ^ c 5 .^5 1 f ^ 1 I 1 X-"% ' N ^^ r o CO w S 6 ? ? 1 *O 3 I f|l|2 ^ w PQ o: ? illlS I DIAGRAM WAX MJ 1 Jlp* gj s "S 5 S P a 1 f about one-third with water, containing a little sulphuric acid. The vats are furnished with copper steam coils, and the -contents are boiled with free steam for two hours, and then left to settle for about twenty-four hours. 5. Distillation. The fatty acids are then drawn off from the vats G G into the tank^, from which they are pumped through the tap c into the lead-lined charge tank, H, above the still. Inside this tank is a steam coil, which is charged with steam at the time the acids are admitted, in order to keep them liquid. From this tank the material is run into the still, /, of which the body is made of iron and the dome of copper. The distillation requires several precautions- * This is the temperature employed at Price's works, Battersea. At the works at Gentilly, near Paris, the heat is seldom higher than from 110 to 115 F. f The proportion of sulphuric acid depends upon the nature of the fatty materials employed. Kitchen-stuff, slaughter-house fat,, and the like require about 12 per cent, of their weight ; palm oil jfrom 5 to 9 per cent., according to quality. PREPARATION OF THE FATTY ACIDS. 24$ 246 CANDLES. with an open fire the fatty acids are apt to be converted into oil, tar, and a carbonaceous residue, if the heat is too high* Air should be also completely excluded from the apparatus. The contents of the still are heated by the fire underneath to about [240 F. (116* C.) and then low-pressure super- heated steam, at about 560 F. (293.3 C.), is admitted by a pipe from the superheater (shown on the left of the still in the illustration). The process of distillation then begins. The current of steam carries with it the vapour of the fatty acids, and thus facilitates the process. The mixed vapours, pass to a series of vertical refrigerating pipes, K. These are of copper, connected at top and bottom by gun-metal bends, mounted on iron frames, and set over the series of iron tanks k, containing copper cooling coils, through which cold water can be passed, and also furnished with steam pipes.. L is the essence tank, fitted with a safety condenser, or shower pipe, which prevents the possibility of any vapour passing away uncondensed. M is a pipe for conveying gas to be burnt in the flue. The fatty acids as they run from the still are, to a great extent, available for candle-making without pressing, but other portions are subjected to pressing, sometimes both cold and hot, and often to a second distillation. Out of every 100 Ib. of tallow subjected to this process it is stated by W. LANT CARPENTER* that about 78 to 80 Ib. of crude stearic acid are produced, of which 60 lb. r or three-fourths, are ready for making stearin candles with- out further pressing. The remaining one-fourth, after being pressed and re-distilled, yields} about 15 Ib. more stearic acid and 5 Ib. of oleic acid. The residue is a sort of pitch, and is transferred, before it solidifies, to a vessel of iron, where it is submitted to a muck * SPON'S " Encyclopaedia," p. 582. PREPARA TION OF THE FA TTY A CIDS. 247 higher temperature and a jet of steam more strongly heated. An additional quantity of fatty acids is thus obtained, of inferior quality, but applicable to the ; preparation of com- posite candles. The final residue is used for many purposes in the same way as ordinary pitch. The following is a brief description of Fig. 42 (p. 245) : A is the melting tank. B is one of a series of lead-lined boiling tanks. C is the force-pump. D is the " acidifier." E is the acid tank. F is the superheater. G G G G are the washing vats. H is the charge tank. / is the still. K is the refrigerator, k, one of the series of iron tanks con- taining the copper cooling coils. L, the essence tank. J/, a pipe for conveying gas to the flue. III. Dissociation by Heat. This may be effected either by the high-pressure process, or by superheated steam at ordinary pressures. The first was patented in 1854 by TILGHMANN, and its object is the separation of fats into acids and glycerin by heating with water only, under pres- sure, by which, at the same time, the substances are, to a certain extent, bleached. The method consisted, briefly, in pumping the mixture of fat and water through a coil heated to above 800 F., and at a pressure of about 2000 Ib. to the inch. This operation was attended with considerable risk. The second method was suggested to WILSON and PAYNE by the above, and was patented by them in the same year.* It is conducted as follows : The fatty matter is heated in a still to about 550-600 E. (290-315 C.). Superheated steam, at a temperature of 600 F., is injected in such a way that it rises up through the molten fat in numerous streams. Saponification is thus effected, and the liberated fatty acids and glycerin are volatilized, and carried over * No. 1624 1854. 248 . CANDLES. in an atmosphere of steam to the condensing arrange- ment. If the temperature is too high (above 600 F.), there is a great liability (diminished, however, by a very plentiful supply of steam) that the fatty acids and glycerin will be further decomposed gaseous hydrocarbons, acrolein, and tarry matters being produced. On the other hand, if the heat is insufficient, either the separation of the glycerin is imperfect, or proceeds too slowly. When the refrigerating arrangement consists of a series of chambers, each provided with a cock to draw off the dis- tiljates, and each more and more distant from the still, the compartments nearest to the still are found to condense little but fatty acids, being for the most f part free from water and glycerin, which chiefly accumulate in the more distant and cooler condensers. In all the receivers the fat acids quickly separate from any aqueous solution of glycerin present, when allowed to cool for a little time. The last of the condensing chambers is open to the air, as no pressure is necessary in this apparatus. By simply evaporating off the water, very pure glycerin is obtainable. IV. The "Autoclave" Process. The large amount of lime required in carrying out the lime saponification is attended with the disadvantage that the great quantity of sulphuric acid necessary for the decomposition of the result- ing rock injuriously darkens the fatty acids produced. By a combination of the lime saponification and TILGHMANN'S high-pressure processes, DE MILLY, in 1856, found that the proportion of lime could be reduced to 2 or 3 per cent., while a less pressure also was sufficient to effect the decom- position. This is called the autoclave* process. The fat is * From atfrds, self, and /cXets (Lat. clavis), a key = that which shuts itself. It is a Papin's digester with a steam-tight lid fixed perpen- dicularly, and is preferably furnished with a safety valve. PREPARATION '. OF THE FATTY ACIDS. 249 put into a strong boiler provided with a stirrer, and mixed with 3 per cent, of slaked lime. Superheated steam is passed in till the pressure equals 160 to 180 Ib. on the inch. After some three hours at this pressure, the separation is complete, and when the exit pipe is opened the fatty acids are forced out. A very small amount of sulphuric acid is afterwards needed to free them from lime. In twenty-four hours three operations of 2 or 3 tons each may be completed. The subsequent treatment for the crystallization of the fatty acids, cold- and hot-pressing, &c., are the same as in the other methods. The fatty materials submitted to the autoclave process should be of good quality. V. Bock's Process. In 1871 Prof. BOCK, of Copen- hagen, pointed out that the neutral fats are composed of a congeries of little globules enclosed in envelopes, probably albuminous. To the presence of these in the fat he attri- buted the difficulty of eliminating the fatty acids by means either of sulphuric acid, except in excess, or of alkali, except under great pressure, conceiving that both these agents, as ordinarily employed, are to a great extent expended in rupturing and destroying the albuminous envelopes.* CARPENTER \ gives the following synopsis of Dr. BOCK'S process, extracted from " Dingler's Poly tech. Journ." May 1873: " By the lime saponification plan, the albumen contained in the fat is dissolved, lime soap is formed, and the extrac- tion 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 a neutral fat, and, by the use of concentrated sulphuric acid, not a * COOLEY'S " Encyclopaedia," ii. 1557. f SPON'S " Encyclopaedia," p. 583. 250 CANDLES. trace of glycerin is left. Acidification, rationally conducted, is only a preliminary operation, intended to break up, cor- rode, or carbonize the albuminiferous matters. But 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 charred, 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 a much shorter time by the chemical equivalent of acid 4 to 4.5 per cent. and the necessary water. After letting out the glycerin waters, the fatty acids appear more or less black. They may now be dis- tilled. Their melting point varies from 120 to 134 F. (49 to 57 C.). " The real value of the new method consists in dispensing with this 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 specific gravity of the two bodies is about the same. The difficulty is overcome by oxidizing the mass, by which the specific gravity of the cells is raised from 0.9 to 1.3. They are thus precipitated, and the fatty matters can be washed off. The subse- quent cold- and hot-pressing are the same as with ordinary methods." PREPARATION OF THE FATTY ACIDS. 251 Dr. BOCK'S process, according to CARPENTER, consists of five stages : (i) Acidification, to remove the cellular tissue of the fat. (2) Decomposition, by acidulated water, into dark fatty acids and glycerin. (3) Oxidation, to increase the specific gravity of the dark membranous matters, so that they may separate from the fatty acids. (4) Repeated washing with tvater. (5) Pressing, both cold and hot, FIG. 43. The following advantages are claimed for this process : 1. Freedom from danger of explosion, as the steam is only used in open tanks. 2. Economy, from simplicity of plant and reduction of labour, the acidification, oxidation, and decomposition being all conducted, in rapid succession, in the same wooden tank- 252 CANDLES. 3. Superiority of product, the stearic acid being of great iiardness, and melting at from 136 to 140 F. (58 to 60 C.). 4. Increased product \ the stearic acid amounting to from. 55 to 60 per cent, of the tallow employed. 5. The oleic acid is more suitable than that obtained t>y any other process for conversion into palmitic acid by RADISSON'S method, yielding a greater . percentage of pal- mitic acid. Separation of Stearic and Oleic Acids.* In the or- dinary method of separation from the mixture of fatty acids which is obtained by saponification of tallow or palm oil by means of lime, the solid stearic acid (so-called " stearin ") is removed by passing through a filter-press at the common, temperature. Under these conditions a considerable quantity of the stearic acid remains dissolved in the liquid oleic acid. By moderate cooling a further quantity of stearic acid can. be obtained without solidification of the oleic acid. For this purpose a revolving drum, A, is employed (Fig. 43, p. 251), containing cold water, supplied by a cooling machine through the tube (7, and carried off by another tube. The drum dips into the trough /, contain- ing the liquid fatty acids, which are carried round in a thin layer upon the sur- face. During the revolu- tion the oil solidifies, and is scraped off by the scraper, h, into the reservoir, F, from which it is pumped through a Farinaux filter-press (Figs. 44 and 45). An increased yield of 4 per cent, on the raw material is obtained, and the FIG. 44. ' " Dingl. Polyt. J." 263, pp. 372- J, 49 ; " J. Chem. Ind." 1887, p. WICKS. 253 oleic acid has a higher value on account of its greater clear- ness. Wicks. The preparation of the wick is a very important branch of the candle manufacture. The wicks of ordinary tallow candles are made of the rovings of Turkey skein- cottoii, lightly twisted, the threads known in the trade as Nos. 1 6 * to 20 being employed. Twisted wicks are now only used for tallow f and for wax candles. The plaited or braided wick was introduced by CAMBAC^RES so as to do away with the necessity of snuffing. The effect of plaiting is to cause the wick to bend over during the combustion of FIG. 45. I fflfu= H III m ^ - r the candle, so that its end falls outside the flame where it is exposed to the air, and its complete combustion is thus insured. This bending over is caused either by twisting the wick with one strand shorter than the rest, which, being slightly stretched during the moulding, contracts again and bends the wick when the fat melts, or by plaiting the cotton into a flat wick, which naturally takes the required * That is, 1 6 or 20 Jianks of which weigh I Ib. f Plaited wicks are unsuitable for tallow candles because, owing- to the ready fusibility of the fat, the bending over to one side would cause guttering. 254 CANDLES. curve. In 1830, DE MILLY found that boracic and phos- phoric acids obviated snuffing by the formation of a bead at the end of the wick, which, by its weight, turned the end out of the flame. Wicks should be of uniform thickness throughout, and quite free from knots and loose threads, as the presence of any of these tends to produce excrescences and guttering. The finer the thread of which the wick is composed, cceteris paribus, the more complete will be the combustion of the fatty materials. Size of Wicks. The size of the wick requires to be ad- justed according to the diameter of the candle and the fusi- bility of the material (i.e., there must be a sufficient number of capillary threads to carry up the melted material from the cup of the candle). If the wick is too large in proportion to the diameter, no cup can be formed, and guttering ensues ; if too small, the unmelted substance forming the rim of the cup does not melt regularly with the descent of the flame, and forms little pillars round it, which are objectionable, because they not only cast a shadow, but by-and-by melt, fall into the reservoir of melted fat, and cause an overflow. Index to TliicJcness of Wicks* For Tallow candles 8 to the lb. wick (No. 16 yarn) contains 42 threads 45 50 55 60 Steario 63 87 96 108 Pickling. To prevent too rapid combustion and smoulder- ing of the wick when extinguished, wicks are dipped in various pickling solutions, such as boracic acid, i kilo, in SPON'S "Workshop Keceipts," 1885, p. 355. WICKS. 255 50 litres of water, or 5 to 8 grams boracic acid to i litre of water, with the addition of a little sulphuric acid (PAYEN) ; a solution of sal ammoniac marking 2 or 3 B. (recom- mended by Dr. BOLLEY), of ammonium phosphate (fre- quently used in Austria), or of bismuth nitrate (PALMER'S patent). A solution of 2^- oz. of boracic acid in 10 Ib. (i gallon) of water, with J oz. of strong alcohol and a few drops of sulphuric acid, is also said to form a good pickle. FIELD * treats wicks by steeping in a solution of phos- phoric acid, or ammonium phosphate, or ammonium phos- phate and borax, or ammonium phosphate and boracic acid. The plaited wicks are kept for about three hours in the pickle, and are then either wrung out, or placed in a centri- fugal machine, to get rid of the greater portion of the water. After this they are completely dried in a jacketed tinned-iron box, heated by steam. * English patent No. 2061 1879. CHAPTEE III. MANUFACTURE. ORDINARY candles are made either by dipping or mould- ing. Wax candles are made chiefly by basting or pouring. Dipping. The commoner tallow candles are made by this process. The purified melted tallow is placed in a trough 3 feet long, made of stout boards, lined with lead, sufficiently deep for the reception of the largest-sized candles, and furnished, on the side at which the workman stands, with a wiping board projecting upwards and outwards along the whole upper edge of the vessel. On this board the ends of the candles are, after each immersion, tapped, so that the super- fluous material may be detached. Another vessel is generally placed beside this trough, from which the melted fat is obtainable as required. In it the tallow is kept properly fluid by means of a steam- or hot- water jacket. The operation is thus performed: 16 or 18 twisted wicks, according to the weight of candles desired, are looped, side by side, and as nearly as possible equidistant from each other, on a wooden, or thin iron, rod (broach, or baguette). Six or eight rods, or more, carrying the wicks, are then placed upon a frame, hung above the trough, and capable MANUFA CTURE. 257 of being raised or lowered at will. There are various dip- ping machines used by chandlers for this purpose, one of which, made by Merry weather & Sons, London, is illustrated by Fig. 46. The advantage of this arrangement is that a perfectly FIG. 46. , Ob . Dipping- machine. horizontal position is always secured, even under unequal pressure at either end, and candles of uniform length are more easily produced than with the ordinary machines. The tallow should be hotter for the first than for the sub- sequent dippings, because hot tallow penetrates more readily into the interstices of the wick. "When the dry wicks have been saturated, they are with- drawn, care being taken to separate the ends of any thab may be adhering to each other, and placed on the dripping- frame, or port, below which is a tray to receive droppings. ' A fresh batch of wicks is then treated in the same way. For the second and following dippings the fat is at a lower temperature, about 100 to 110 F., with a tendency ta s 258 CANDLES. solidify at the sides of the vessel. After each immersion the candles are allowed to cool sufficiently to retain a fresh coating of tallow at the next dipping. The dippings are- continued till the candles have acquired the thickness and 1 weight desired. Greater care is required for the final dip- pings to insure symmetry of form ; if the lower ends of the candles are too thick, they are kept for a little in the molten tallow, so that the excess may be melted off and the tem- perature of the bath may be somewhat raised to produce a more even finish. The lower ends may finally be either cut away, or removed by placing the candles for a moment on a copper plate or sheet-iron tray heated by steam, and pro- vided with a spout to carry away the melted portions. A different method of dipping is practised at Messrs.. Price's works, Battersea. Instead of dipping the wicks, they dip a series of steel skewers into the melted candle material, and, after the candles have been formed and cooled, these are removed, and the wicks, specially prepared and cut to the required length, are inserted. This method entirely prevents the waste of wick by the old method, and the saving thus effected is said to cover the whole cost of the- candle-maker's labour. Moulding. This operation is performed on the small scale by hand- frames, and in large works by some of the various moulding machines. Hand-frames. Fig. 47 exhibits the form of the hand- frames. They are made in all sizes, and suitable for all materials and shapes. They are convenient for small manu- facturers, as an assortment of all sizes is less costly than one moulding machine. They are now, however, compara- tively little used. Moulding Machines. Candle machine?, or continuous MANUFACTURE. 250, wick machines, manufactured by Biertumpfel & Son, Albany Street, London, N.W., and by E. Cowles, Novelty Works, Hounslow, are shown in Figs. 48, 49, and 52. They are modifications of the machines introduced into this country from America about 1849. FIG. 47. The following is the method of using these machines : i. Raise the tip moulds to the top of the main moulds. 2. Insert a very fine wire doubled, and of sufficient length to go through the tip mould and piston, and extend below the piston about 6 inches ; insert the end of the wick in the loop made by the doubled wire, and draw up the wick through the tip mould, and secure it in any convenient manner for the first pouring ; then lower the pistons as far as they will go, pour in the material by means of the jack (Fig. 51), and when cold shave off the butts with the scoop (Fig. 50); then place the racks B in a vertical position, with the tip bars thrown out ; the crank, r, is then turned, and the candles ejected into the racks ; the racks are then closed by turning the handle of c, and the tip of each candle is held precisely over the centre of its mould ; now, the piston- S 2 2*60 CANDLES. A is the main body of the stand. B, Movable racks with tip bars. c, Handle of the eccentric wedge. D, Pistons, having the tip moulds at the upper ends. E, Spools, with pins on which they revolve, r, Crank for raising the pistons. G, Handle of cock for emptying water box. H, Overflow pipe, i, Newly made candles, j, Clearing pin. K, Pipe for admission of hot or cold water. MANUFACTURE. 261 block with pistons is let down, and the wicks are held by the candles above and the spools below ; passing through FIG. 49. Xil!^ UK the pistons, and through a small aperture in the centre of the tip mould, they are all strained exactly in the centre of the moulds, and all is ready for the melted material again, and, when this is cold, the wicks are severed below the tip 262 CANDLES. bars, and the racks with the candles are then removed to any desirable place. The machine represented by Fig. 46 is for making a FIG. 50. Scoop. large number of small-sized candles, from 24 to 100 to the Ib. It contains four trays of moulds for 224 candles, FIG. 51. Filling can. and may be arranged to produce at each operation four dis- tinct sizes say, 72, 60, 36, and 24 to thelb. MAN UFA CTURE. 263 A great Improvement in the candle was made in 1861,* when Mr. J. LYON FIELD patented the conical butt, by which a candle can be adapted to any candlestick, without paper FIG. 52. or scraping. This invention required special machinery for ^effecting its object, as the tapering butt is larger at the * FIELD, Cantor Lectures on "Solid and Liquid Illuminating .Agents," 1883, p. 48. 264 CANDLES. point of junction with the candle than the diameter of the latter, and could not, therefore, be extracted from the ordi- nary mould. Fig. 5 2 exemplifies how this difficulty is over- come. The moulds for the butts are cast in a separate frame, which is removed, when the candles are finished, by a chain and pulley, and the candles are then pushed out of the stem moulds in the ordinary manner. Machine for Cutting the Conical Ends of Candles.* The conical end may also be made by the cutting machine shown in Fig. 53. The plate A, which is capable of being turned round the FIG. 53- axle a, is furnished with grooves for holding the candles. "When the plate is in an inclined position, the candles are put in the grooves, in which they are kept by the guard B, which can be adjusted to suit the length of the* candles. On moving A into a vertical position, the candles slide downwards, the guard b keeping them from falling out, and at the same time forcing them to glide into the conical cutters, c. By pressing the board C against A, the- candles are kept in position. The cut- ters, c, consist of conical bushes, on the inner wall of which several knives are fixed; they are attached to the square rods, h, which loosely move up arid down in the collars, r. The cutters, c,, are set in motion by the screw G ; at the same time the shaft, If, turns, and by the thumb, J, lifts the bearing, /i, of the square shafts of the cutters, thus * German patent 19,656, January 10, 1882, Motard & Co., Berlin j. ' J. Soc. Chem. Ind." 1882, p. 509. MANUFACTURE. 265, causing the latter gradually to cut the ends of the candles. After one turn of the shaft, H, the bearing, jfiT, goes down again, and restores the cutters to their original position. At this point the machine stops automatically. Among the advantages of the moulding machines may be mentioned the following : i. Rapidity of the process and beauty of finish. 2. Candles can be made as well in summer as in winter. 3. They can be arranged to turn out candles of different diameters and lengths in one machine. 4. By simply raising the driving plate, the length of the candles may be shortened at will. Moulding Tallow Candles. The moulds are generally made of pewter, carefully polished inside. The wick is inserted, after saturation with melted fat, through the opening at the smaller end, where it serves as a stopper, It is fastened at the upper orifice either to the movable top, or by means of a peg put through the looped end of the wick, and resting upon the end of the mould, while the wick is pulled tight from below. The melted fat is poured in, generally by a small can, orjac/c, Fig. 50, and it is essential that the tallow should completely fill the mould, which is of course maintained in an upright position. The candle must remain entire on cooling, without any cracks, and should readily be removable from the mould. These results can only be attained when the fat at the sides cools more rapidly than that in the interior, and a rapid cooling is always necessary to prevent contraction of the candle^ Hence, cool weather is the most suitable for the operation. The proper consistence of the melted tallow to be used is- known by the appearance of a scum on the surface, which in hot weather forms between 111 and 119 F. (44 and 48 C.), in mild weather at 108 F. (42 C.), and in cold weather at about 104 F. (40 C.). If the tallow is too hot when poured in, the candles are apt to stick, and are difficult 266 CANDLES. to draw ; if too cold, the candles are not uniform in appear- ance, but become granular-looking. The candles are ready to be taken out of the moulds on the day after casting, and then only require cutting and trimming at the base. Moulding "Stearin" Candles. The blocks of the stearic acid are melted, and, to break the grain or prevent crystallization, there is added 3 to 5 per cent, of wax, or 10 to 20 per cent, of paraffin, the whole is kept well stirred till the solidifying point is nearly reached, and then poured into the moulds, previously heated to about 120 F. to 125 F. It may be noted as a rule, when fatty acids are the material to be moulded, that the moulds should be heated to a temperature about 10 F. under the solidifying point of the material used, and the fat should be cooled down as near to its setting point as possible without the production of any actually solid portions. By alternately admitting hot and cold water to the trough, a polished appearance may be communicated to the candles, but the method of doing this can only be acquired by actual experience. The fusing point of stearic candles is 131-132 F., and the produce of various makers in dif- ferent countries is remarkably uniform in this respect. Moulding "Sperm" Candles. The moulding of sperm candles can be done in almost any of the ordinary machines. The spermaceti is heated to about the boiling point of water, run into heated moulds, and, to maintain, transparency, is cooled as rapidly as possible. To destroy its highly crystalline structure, spermaceti is usually mixed with 3 per cent, of wax. Sometimes it is tinted with gamboge, and denominated transparent ivax. Sperm candles, when properly made, are remarkable for the regularity of their flame, a result of the uniformity of the constitution of the material. Hence the choice of the sperm candle, burning 120 grains per hour, as the standard MANUFACTURE. 267 for photometric purposes. On account of their high fusing point, spermaceti candles are very suitable for use in hot climates. Moulding Paraffin Candles. The same moulds may be used as for stearic and spermaceti candles. The principal difference in the operation is as regards the regulation of the heat. The moulds are heated to about 150.8 F. (66 C.), or a little above the melting point of the paraffin, and, when nlled, they are left at rest for a few moments, and then suddenly cooled by cold water. This is intended to prevent crystallization, and consequent opaqueness. The tendency of the paraffin candle to soften and bend at temperatures below its melting point is met by the addi- tion of 5 to 15 per cent, of stearic acid. FIELD and HUMFREY have patented* the following method of procedure : The paraffin, having been melted at about 140 F., is run into moulds heated to the same temperature, or rather higher. After standing for a few minutes to allow bubbles to escape, the moulds are surrounded by cold water. This sudden cooling of the paraffin prevents the formation of crystals, and candles nearly transparent, and which draw freely, are thus obtained. For paraffins of good quality, a wick of ordinary plaited cotton can be used, and, by dipping it in a weak solution of boracic acid, the ash of the wick will be fluxed, and the candles will burn with a bright and clear end. Moulding Composite Candles. J. P. WILSON patented the composite candle in 1840. The material was a mixture of coco-stearin and stearic acid. This candle is somewhat greasy, but is comparatively cheap, and gives a good light. Another method is to melt together, over a water bath, 100 parts of stearic acid and 10 to n parts of bleached * Patent No. 454, February 22, 1856. 268 CANDLES. bees'-wax, but, to insure success, the mixture must remain over the bath from twenty to thirty minutes without being stirred. At the end of that time the fire is extinguished, and the mixture allowed to cool until a slight pellicle i& formed on the surface, when it is cast direct into the moulds, previously heated to about the same temperature.* Cutting and Polishing. The candles taken from the moulds have the ends cut by a circular saw, and have the length adjusted. The machinery allows them afterwards- to fall upon an endless woollen cloth belt, supported by rollers, which carries them under other similarly covered cylinders, revolving in the opposite direction, by which means they receive a polish. Some of the higher class candles are hand-polished by rubbing with a woollen cloth moistened with aminoniated alcohol. Night-lights. These have taken the place generally of the old rushlight. Formerly they were called mortars.^ As intensity of light is not required, a very thin wick is used, with a disproportionate thickness of fatty matter, so that a very deep and full reservoir is formed, containing an excess of melted fat, which is prevented from flowing over by the case of cardboard or wood shaving, or by a small glass vessel. They were first made of wax or spermaceti, or a mixture of wax and spermaceti, but now generally from stearin, and coco-stearin, or from cocoa-nut oil and palmitic acid, in varying proportions. The wick is fastened to a little square of tin-foil the sustainer and secured in the centre of the little case by a drop of wax. The cases, placed in rows, are filled by pouring the melted material into each from a jack. * SPON'S "Workshop Keceipts," 1875, p. 358. f More (Lat.), death from their use in death-chambers. MANUFACTURE. 269 In another kind of night-light made of harder material, largely consisting of palmitic acid, the case is dispensed with, and, during the burning, the light is placed in a small glass. This description is made by running the melted fat into a special moulding frame. When cold, the night-lights are turned out ready punctured for the wick, which is after- wards inserted by hand. Wax Candles. The wicks for wax candles are made of twisted unbleached Turkey cotton. Plaited wicks are not so suitable, as the plaiting, by retarding the capillary action, necessitates the employment of a larger wick, which is apt to curl round in the name and obscure the light. Wax is not well adapted for moulding, on account of its tendency to adhere to the mould, and its great contrac- tion on cooling. The process of making wax candles is analogous to that of dipping, but, instead of dipping the wicks into the material, the melted wax is poured upon the wicks. The wicks, having been warmed in a stove, are suspended on a hoop of wood or metal, which hangs over the cauldron of melted wax. The operator causes the hoop to revolve, and, taking a ladleful of the fluid material, pours it over each wick in succession, taking the precaution to keep turning the wick quickly on its axis by the fingers at the same time, so that the wax may not accumulate more on one side of the wick than the other. After three or four revolutions of the hoop, or when the candles are coated to about one- third of their proper size, the first hoop is laid aside, and, while its load is cooling, another hoop is taken in hand. The candles on the first hoop are afterwards again basted till they are half the required size. They are next, while still warm, rolled, upon a marble slab sprinkled with water, 270 CANDLES. with a rolling board, so as to make the cylinders smooth and of a uniform thickness. After this they are suspended again on the hoop, but in a reversed position, and the basting is continued till they are of the required size. When this is attained they are once more rolled on the slab, cut to- a certain length, and have their tops trimmed with a piece of wood. The operation throughout is one requiring much skill and experience. A section of a well-made wax candle shows rings, resembling the annular layers of a tree, and corresponding to the number of bastings. Large Wax Candles for ecclesiastical use are made by placing the wick on a layer of wax, bending the wax over it, and then rolling, as in the ordinary wax candles. Other layers of wax may, if necessary, be rolled on up to the re- quired thickness. Wax Tapers. The materials wax, with stearic acid, paraffin, &c. are melted in a jacketed pan (Fig. 54) ; and FIG. 54. Silver-plated bougie or draw-wick pan, with winding drum, to heat by steam. the wick, usually of several fine yarns of cotton, twisted to suit the thickness of the taper to be made, is wound on a drum, and drawn through the pan. CHAPTER IY. SPECIALITIES. Belmont Sperm Candles. The body of this description of candle is said to be a mixture of stearic and cocinic acids, with a portion of paraffin. Belmont Wax Candles consist of stearic acid with a small proportion of wax. They are tinted with gamboge. Ozokerit Candles. These are a speciality of Field, of Lambeth. They have a remarkably high melting point and great illuminating power. They burn with a dry cup,, are not liable to gutter, are free from smell, and not greasy to the touch. They do not bend or soften in a warm atmo- sphere like ordinary paraffin candles. The hardness and liigh melting give rise to one drawback the wick is apt to smoulder on extinction. The 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 ex- tinguish the spark. This difficulty, however, is overcome by special attention to the preparation of the wick. Double- and Treble-wick Candles of large diameter are made for police and nautical use. Hydraulic-pressed Candles. E. L. BROWN, of Chicago, has patented* a process to prevent unnecessary waste in * United States patent No. 345,272, July 13, 1886. 272 CANDLES. the use of candles, by so treating them in the process of manufacture that they will melt very slowly. This is ac- complished by forming the body of the candle under extreme pressure. The candle cylinder is first moulded in the usual way, and is then compressed by means of a hydraulic press. Hygienic Candles. WATSON and FULTON* prepare these by incorporating iodine and a small quantity of sulphur with the candle material, and they consider that during the combustion the iodine and sulphur are both eli- minated in the free state, according to the equation 4 HI + S0 2 = I 4 + S + 2H 2 0. Wright's Pulmonic Candles. These are impregnated with anti-asthmatic remedies, and are made on Messrs. FIELD'S patent for securing perfect combustion and freedom from guttering by means of three or more air channels -running parallel to the wick throughout the length of the candle. SWEETSER, BELL, and BOHM have taken out a patent f for moulding and pressing candles direct from the candle material, whilst in a solid or plastic state, in continuous lengths. The material is kept under pressure, and, being forced through a tube, carries the wick along with it in situ. The coated wick has then only to be pointed, by being pro- jected against a rotary cutter, or by other means, and cut into lengths to form candles. Ornamental Candles. Decorated Candles. The materials for candles intended to be decorated should be of the best quality, and should have a high melting point. They may be varnished by gum * English patent No. 10,8761885. t No. 13,4171885. SPECIALITIES. 273 dammar, dissolved in turpentine or alcohol, or by mastic varnish, and the design painted on by hand or otherwise. Cable, Twisted, or Spiral Candles. These are moulded in the ordinary way, and then turned by means of a special lathe ; or they may be cast in rifled moulds, from which, on cooling, they are wound out. Coloured Candles. Among the colouring matters used for candles are the following : Blue : Prussian blue, indigo, ultramarine, copper sul- phate, aniline blue. Red : Carmine, Brazil wood, alkanet root, minium, ver- milion, aniline reds. Yellow : Gamboge, chrome yellow, naphthaline yellow. Green : Mixture of blue and yellow colours. Purple or Violet : Mixture of blue and red colours. Neutral Tints : Oxides of iron, yellow ochre, Frankfort black. Black : Fruit of Anacardium occidentale, aniline blacks, In order to dye paraffin candles with an aniline base, such as magenta, the dye is first dissolved in stearin, and a little of the resulting stearate is added to the paraffin. There are two ways in which candles may be coloured black :* (1) Anacardium Method. Paraffin, or whatever material is desired for the candles, is heated to from 200 to 210 C. with 25 percent, of its weight of the chopped/ ruit of Anar- cardium occidentale. Candles prepared in this way are equally black throughout, and yield no irritating vapours when burnt. (2) Aniline Method. The material to be dyed is heated a few degrees above its melting point with i to 2 per cent. of nigrosine fat colour (prepared by Destree, Wiescher, & * " Chemist and Druggist," 1884, p. 290. 274 CANDLES. Co., of Brussels). Paraffin and spermaceti require i per cent. ; stearin and wax require from i \ to 2 per cent. The candles thus prepared are said to be of a sombre hue throughout, and of a jet-black appearance. Quality of Candles. In judging of the quality of candles, the following points should be considered :* (i) Nature of the fatty materials. (2) Whiteness. (3) Transparency. (4) Hardness. (5) Dryness to the touch. (6) Fusing point. (7) Form and moulding, (8) Character of wick. (9) Nature of the flame is it uniform, long or short, well supplied, brilliant, without smoke ? (10) Does the cup burn dry, or is it filled with melted fat? (n) Is the fatty matter free from mineral ingredients ? Bending Point. Candles may be compared, as to their tendency to bend in warm atmospheres, by observing their behaviour when kept, for an hour or more, in a cupboard, or oven, heated to 100 F. Illuminating Value. The illuminating value of candles may be determined by the photometer, as described in the fourth volume of this series of Handbooks, pp. 310-315. * CRISTIANI, "Treatise on Soap and Candles," p. 488. CHAPTER Y. BYE-PRODUCTS. Oleic Acid. The oleic acid may be used for soap-making, and is specially valuable for the production of soap for the use of textile manufacturers. Oleic acid from the linie process is the best for this purpose, because it is free from hydrocarbons. If a soap is made from oleic acid containing hydrocarbons, when dis- solved in water these separate and adhere to the fabric. Oleic acid free from hydrocarbons, when saponified by heat- ing in a test-tube with twice its bulk of alcoholic soda, forms a soap which gives a dear solution when dissolved in water. It may be also converted into palmitic acid by PtADissoN's method, which is founded on the discovery of VARENTRAPP, in 1841, that when oleic acid is heated with a great excess of caustic potash it is decomposed into palmitic and acetic acids, and hydrogen, according to the equation C 18 H 34 2 + 2 KHO = C 16 H 31 K0 2 + C 2 H 3 K0 2 + H, Oleic acid Potash Potassium Potassium Hydro- palmitate acetate gen. The following is an outline of the method followed by RADISSON,* and described by CARPENTER :t * English patent 1782 1869. j- SPON'S "Encyclopaedia," pp. 584-586; "Journ. Soc. Chem- Ind." 1883, p. 98. T 2 276 CANDLES. About i \ ton of oleic acid and 2j tons of caustic potash lye (43 B.) are pumped into a cylindrical cast-iron vessel, about 12 feet in diameter and 5 feet high, provided with a sheet-iron cover. The vessel is heated from below by a fire,, sufficiently far off to avoid burning. The steam evolved passes off by a large man-hole on the top. This is closed when the soap gets dry, and the gases afterwards disengaged are conveyed through pipes, first to a condensing tower, and thence to a gas-holder. The materials are kept constantly stirred by a mechanical agitator, in order that the heat may be equally distributed, and that the froth, which rises abundantly, may be beaten down. Eventually, the soap becomes fused, and at 554 F. begins to give off hydrogen. The temperature is slowly raised to 608 F., and the gases then given off have a characteristic odour. If the heat were longer continued the materials would enter on the stage of destructive distillation. The operation at this stage is there- fore suddenly stopped by the introduction of steam and water through a G-IFFARD injector, and, at the same time, a. door in the bottom of the cylinder is opened, through which potassium palmitate falls into an open tank. Here the soap, with a sufficient quantity of water, is melted by means of a jet of steam. After subsidence the contents of the tank become separated into two layers, the upper of neutral potassium palmitate, and the lower of potash lye (usually about 1 8 B.). The palmitate is removed to another vessel,. decomposed by sulphuric acid, and the liberated palmitic acid is washed with water to free it from potassium sulphate. The palmitic acid thus obtained is of a clear chocolate colour, and crystallizes in large tables. Its melting or solidification point ranges from 122 to 127 F., according to the character of the oleic acid employed. Distilled in the usual apparatus, it leaves only 3 per cent, of pitch. After BYE-PRODUCTS. 277 -distillation, it is very white, and jburns with a clear smoke- less flame. Moulded into candles, it compares very favour- ably with the best stearic acid, and, when mixed with ordinary stearic acid, breaks the grain of the latter, and gives it a semi-transparency very valuable in the eyes of the candle-manufacturer. RADISSON has experimented with the object of replacing potash by soda, but experienced at first a difficulty in heat- ing the materials uniformly. This difficulty he successfully overcame by introducing paraffin. When paraffin is present with sodium oleate and excess of soda, the mass becomes fluid on heating, and a uniform temperature throughout is speedily established. There is no fear of decomposing the sodium palmitate, since the point at which this would occur is above the temperature at which paraffin distils. The small quantities of paraffin which are unavoidably volatilized are caught in a condenser, and the hydrogen evolved is so charged with hydrocarbons as to form a good illuminant. At the end of the reaction the whole is allowed to fall into water, as in the former process, and after a time three layers are formed the bottom layer of soda lye and sodium acetate, the middle of neutral sodium palmitate, and the uppermost of paraffin. The top and bottom layers are re- moved, and serve for succeeding operations, and the sodium palmitate is decomposed by sulphuric acid. The palmitic acid obtained has, according to the author of the process, a solidifying point varying from 140 to 154 F., according to the kind of oleic acid operated upon. A ton of palmitic acid by the first process costs about ^13, by the second only about ^7 105. The candle-maker gains, according to the inventor, the following advantages by adopting this process : (i) Utiliza- tion of the olein, a troublesome bye-product of variable value. (2) The floating capital necessary for the purchase of raw 278 CANDLES. material is diminished by about 30 per cent., the proportion of hard candle material being increased by nearly the amount of olein produced. (3) Low-priced grease, whose value varies in inverse proportion to its richness in olein, can be employed. (4) The candle material produced is little, if at all, inferior to that produced by any other method. Glycerin, C 3 H 5 (OH) 3 Syn. GLYCEEOL the base of the ordinary fats, is a colourless, odourless, syrupy liquid of intensely sweet taste, and miscible in all proportions with water. It was discovered in 1779 by SCHEELE,W!IO obtained it, in the preparation of lead-plaster, by saponifying lard with lead oxide. CHEVEEUL afterwards showed that it is a con- stant product of the saponification of the ordinary fats. It is not susceptible of the alcoholic fermentation, but an aqueous solution of glycerin, if kept in a warm place, is slowly converted by the action of brewers' yeast into pro- pionic acid (C 3 H 6 2 ). It has no action on vegetable colours. When heated in air at the ordinary pressure, it decomposes one of the products being acrolein (C 3 H- 4 0), which has a well-known peculiarly irritating odour : C 3 H 5 (OH) 3 = 2 H 2 + C 3 H 4 Glycerin Water Acrolein. In presence of aqueous vapour under pressure in air and in vacuo, it can be distilled unchanged. Its specific gravity is 1.271.28. It boils in vacuo at 179.5 ^-> anc ^ a ^ 755-55 mm - pressure at 200.08 C. According to F. NITZSCHE,* a method of obtaining glycerin in crystals was discovered by KRAUT in 1870. This method is applied in the works of Sarg & Co. at Liesing, near Vienna, to the production of glycerin, the crystals being freed from * " DingL Polyt. J." ccix. 145 ; WATTS' " Dictionary of Chem." vol. viii. pt. ii. suppt. 3, p. 871. B YE-PROD UCTS. 279 adhering mother liquor in a centrifugal machine, then dried, and melted. When quite pure and anhydrous, it crystallizes* on ex- posure to a very low temperature, especially if agitated. The crystals so obtained are mono-clinic, perfectly colour- less, and melt at 60 F. According to WERNER, f commercial glycerin may be made to crystallize by passing a few bubbles of chlorine into it. f Glycerin does not, for the most part, exist in the free state, or ready formed, in natural fats, but, when the fat is saponified, glycerin is formed by the addition of the elements of water to the radical glyceryl (see p. 52). The reaction is similar to that by which common alcohol may be produced from ethyl acetate (acetic ether) : CH 3 CO.OC 2 H 5 + KHO = CH 3 CO.OK + C 2 H 5 .HO Ethyl acetate Caustic Potassium Alcohol, potash acetate In fact, glycerin is an alcohol, bearing the same relation to the fats stearin, palmitin, olein, &c., that ordinary alcohol bears to the compound ethers. BERTHELOT'S researches on the synthesis of fats, by the direct action of acids on glycerin, have shown that glycerin is a tri-atomic alcohol, in which one, two, or three atoms of hydrogen may be replaced by acid radicals, producing fatty or oily compounds, some of which are identical in com- position and properties with the natural fats.J The following table shows the specific gravities and freezing points of aqueous solutions containing different percentages by weight of glycerin : * Eoos, " Journ. Chem. Soc." 1876, i. 651. f "Zeitschr. f. Chem." [2], iv. 413. % See also " Oils and Varnishes," p. n. 280 CANDLES. Percentage. Specific Gravity. Freezing Point (C.). 10 .024 _ j 20 .051 - 2. 5 30 075 - 6 40 .105 -I7.5 5 .127 -3I.34 60 159 70 So .179 .I2O Below 90 .232 '-35 94 .241 ' Some of the chief methods proposed for the recovery of glycerin from soap lyes have been given in Part I. p. 175. The glycerin separated in the various processes for the preparation of fatty acids to be used in the manufacture of candles is now of great commercial importance. The crude or raw glycerin is obtained by concentrating the sweet water by evaporation to about 44 Tw. (sp. gr. 1.22). Some candle-makers carry the operation no farther, but dispose of the raw article to those who make its purification a branch of their business. The purification may be effected by superheated steam in the manner already described (pp. 247 and 248). Removal of Glycerin from Fats before Saponification. A patent has been taken out in the name of IMRAY * with this object. The fatty matter is mixed with about one-third of its weight of water, and from \ to ij per cent, of its weight of zinc oxide. It is then subjected in a close vessel to the action of steam at a pressure of from 100 to 130 Ib. per square inch from three to four hours. The product thus saponified is treated as in calcareous saponification, but the very small proportion of mineral substance used enables the acid treatment for decomposition of the soap to be dispensed with, and the acid fat can be at once employed in the manu- facture of soap or candles. * English patent 5112, October 27, 1882. B YE-PROD UCTS. 28 r Testing Glycerin.* Oxide of lead, lime, and butyric acid, the result of incomplete purification, are the impurities most frequently met with in commercial glycerin. Lime and lead are indicated when, on the addition of a few drops of dilute sulphuric acid to a portion of the sample diluted with its own volume of water and with a little alcohol, a white precipitate is obtained. If the precipitate is blackened by sulphuretted hydrogen, lead is present. Butyric acid is detected by mixing strong alcohol and sulphuric acid with the sample, and heating slightly, when, if this impurity be present, the agreeable odour of butyric ether becomes manifest. Formic acid, if present, gives the odour of formic ethyl (peach-flower smell) when the glycerin is heated with alcohol of 40 and a drop of sulphuric acid. Oxalic acid would be shown by a white precipitate on the addition to equal quantities of glycerin and water of 2 drops of a solution of calcium chloride containing a little ammonia (free from carbonate). Glucose would reduce FEELING'S copper solution ; and cane sugar, after inversion by a mineral acid, would be detected by the same reagent. Or, the presence of either would be detected by the polariscope, as glycerin itself has no optical activity. The chloroform test consists in mixing equal parts of chloroform and glycerin, stirring, and then leaving the mixture to settle. Of the two layers which form, the upper one consists of pure glycerin, the lower of chloroform with the impurities. If the glycerin is pure, the chloroform re- mains clear ; if not, a greyish belt is observed at the line of separation. Perfumers test glycerin with silver nitrate ; if pure, there * F. JEAN, " Journ. de Pharm. d' Alsace-Lorraine," ix, 136; "Year Book of Pharmacy," 1883, p. 258. 282 CANDLES. is no sensible coloration produced at the end of twenty-four hours. Sulman and Berry on the Examination of Com- mercial Glycerin.* Colour. SULMAN and BERRY state that the colour of commercial glycerin does not necessarily indicate whether a sample is crude or once distilled, for,, although crude samples are usually highly coloured, pale samples are often obtained by the lime process, while once distilled samples from soap lyes are sometimes very dark. Mineral Matter. On incineration, distilled glycerin never yields more than 0.2 per cent, of mineral matter. Crude glycerin from soap lyes gives from 6 to 14 per cent, of ash. The crude product obtained in candle factories, either by the lime, magnesia, zinc, or other processes, contains a smaller proportion of mineral matter than that from soap lyes. " Crude glycerin invariably contains albuminous matters, derived from the nitrogenous envelope of the fat globules, often to the extent of several per cent. Here, as usual, it is the soap lyes which yield the most heavily contaminated samples owing to the ready solvency of the proteid matters contained in the fats by the alkalies employed. They are chiefly objectionable on account of the mechanical difficulties to which they give rise in the subsequent distil- lation, and on account of the contamination of the distillate with empyreumatic and coloured products. In glycerin from soap lyes a frequent and very objectionable impurity is rosin, which often imparts a characteristic fluorescence to the distillate. Rosin oils may be detected in the distilled samples by shaking with ether, the bulk of which rises to the surface on standing, and contains most of the oil pre- sent, which may be recognized on evaporation of the de- * " Analyst," 1886, p. 12. BYE-PRODUCTS. 283. canted ether by its physical character, its odour on warming, and its characteristic taste. Glycerin from candle factories contains no rosin. " On acidifying crude glycerin from soap lyes, a milky white precipitate is frequently obtained, the quantity of which depends upon the process of extraction adopted, and whether acidification has previously taken place. The pre- cipitate consists mainly of resinous acids and free sulphur (the latter being due to the decomposition of the sulphur compounds introduced with the caustic soda used for the saponification of the fats) ; the sulphur has been found at times to constitute 40 to 60 per cent, of the whole precipitate. The sulphur is hardly less objectionable than the rosin, as it gives rise to volatile sulphur compounds on distillation. " The albuminous matters cannot be completely removed from the crude glycerin except by distillation, and for ana- lytical purposes it is not necessary to separate them from the other organic impurities, which are separable by basic acetate of lead, and of which they form the bulk. " Crude glycerin obtained by the sulphuric acid pro- cesses of fat saponification is always charged with sul- phates, and generally sulphites; occasionally appreciable quantities of sulphide are found. Both the latter are injurious in distillation. Glycerin from candle factories frequently contains some free fatty acid, which is usually oleic. " With regard to the impurities in distilled glycerin the traces of mineral matter present may consist of sodic chloride and salts of lime, copper, and iron, the two latter being derived from the still and fittings, the presence of the copper being due to formic acid. This acid is produced either by the action of traces of mineral acids upon the glycerin in the still (oxalic acid being first formed and again immediately decomposed with liberation of carbonic 284 CANDLES. acid and the volatile fatty acid), or as one of the final pro- ducts of the action of the small quantity of alkali remaining in the crude glycerin upon the albuminous impurities. The chief organic impurities of first distillates from soap lyes are formic, butyric, and oleic acids, rosin oils, colouring and empyreumatic products, and occasionally organic sulphuric compounds. In the samples from candle factories butyric acid sometimes (according to PERUTZ) reaches the amount of 0.5 per cent. The glycerin obtained by the WILSON- PAYNE process generally contained considerable amounts of the higher fatty acids. " For the determination of the total mineral matter pre- sent in a sample, two separate ignitions are requisite, as it is impossible to burn off all the carbonaceous portion of the residue without volatilizing some of the salt which is almost invariably present. The first portion taken is warmed, the vapours ignited, &c., and the charred mass so obtained is exhausted with hot water. The solution is filtered, and the chlorides determined by titration with standard silver solu- tion. A second portion is burnt in the same way, and the residue strongly ignited, using the blowpipe, if necessary, till no more carbon remains, and the ash is fairly white ; the weight is taken, the residue dissolved, and the chlorides determined in it. The difference between the two deter- minations gives the amount of chloride volatilized, which is calculated as sodic chloride and added to the weight of the second ash. " Chlorides cannot be directly determined in glycerin by precipitation or titration with silver, owing to the solu- bility of argentic chloride in this liquid, and to the reduc- tion of the nitrate in the cold by the contained impurities. They are therefore determined in the ash, as before directed. Crude soap lye glycerin usually contains from 5 to 10 per cent, of salt. BYE-PRODUCTS. 285 "Alkalinity, due almost entirely to sodic carbonate, is most readily estimated by titration of the diluted sample with standard acid. Litmus is the best indicator, phenol- phthalein and methyl orange giving indistinct end reac- tions. Crude soap glycerins are usually alkaline, and pur- posely so, owing to the risk of concentrating them in pre- sence of acid. We have found them to contain, as a rule, from 0.5 to 2 per cent., the amount present depending to some extent upon the process adopted in their prepara- tion. In a case, cited by Dr. FLEMING,* where the soap had been separated from the lyes by excess of alkali instead of salt, the resulting glycerin contained 31 per cent, of sodic carbonate. " Calcium, Zinc, Iron, Magnesia are determined as usual in the ash. " CAP'S test for lime in the original glycerin consists in the addition to the sample of an equal volume of alcohol containing i per cent, of sulphuric acid, the alcohol largely diminishing the solubility of the calcic sulphate : we have found, however, that the ordinary ammonium oxalate test gives quite as delicate results. " Organic Impurities, consisting of albuminous and resin- ous compounds, colouring matters, and the higher fatty acids, are largely precipitable by basic lead acetate, and may be estimated with considerable accuracy by a modification of CHAMPION and PELLET'S process. The glycerin is suffi- ciently diluted with water, carefully neutralized with acetic acid, and warmed to expel carbonic acid : when cool, the basic acetate is added in slight but distinct excess in the cold, and the mixture well agitated. The precipitate is collected upon a tared, or, better, a double counterpoised filter, well washed (the first washings may be effected by * " Seifenfabrikant," i. no. 286 CANDLES. decantation in the beaker), dried at 100 C. to 105 C., and weighed. The precipitate and filter papers are ignited separately, each with a few drops of nitric acid. The weight of the lead oxide (and perhaps sulphate) obtained, when deducted from the weight of the dried precipitate, gives the organic matter contained by the latter. The nitric acid prevents the reduction of the plumbic sulphate, when present, to sulphide or metallic lead ; to control the result, and with the above view, the precipitate, instead of being ignited, may be treated with hot nitric acid, diluted, and filtered, the lead being determined in the filtrate by any convenient method. In this way any sulphate of lead present in the precipitate is left undissolved. It has been recommended to ignite the precipitate obtained by the basic acetate of lead, with sulphuric acid, to multiply the weight of the sulphate obtained by 0.736, and to deduct the weight of lead oxide obtained as before directed ; but this method is obviously inaccurate, as it takes no account of the sul- phates almost invariably present, to some extent, in crude glycerin, and thus includes the sulphuric acid in terms of 4 organic impurity.' No average figures can be given as to the varying amounts of the above impurities for crude glycerin, but in distilled samples the amount present should not exceed 0.5 to i per cent. " Fatty Acids are often present in such proportions that mere dilution with water causes their precipitation ; smaller quantities may be detected by diluting and applying the elaidin test the flocculent yellowish precipitate of elaidic acid obtained by passing peroxide of nitrogen through the solution being 1 less soluble in glycerin than the original oleic acid. " The Nitrate of Silver Test, used by perfumers, depends upon the production of a black precipitate of metallic silver on standing for some time. This reduction is principally BYE-PRODUCTS. 287 due to the presence of small quantities of acrolein and of formic acid ; a good distilled glycerin should give no pre- cipitate after twenty-four hours, though nearly all com- mercial samples we have met with in bulk do speedily effect reduction. " For the detection and estimation of Sugar, FEELING'S method is readily applicable. This substance cannot occur except as an adulteration, and hence it is only necessary to look for it in distilled samples. The same remark of course applies to glucose. Sucrose and dextrin, it need hardly be said, require the usual inversion by heating with dilute (5 per cent.) sulphuric acid before applying the FEHLING solution. The small amounts of other impurities present do not interfere with this test. That it is constantly necessary to examine samples for sugar is shown by the fact that a spurious glycerin has been found by a conti- nental chemist to be composed of a saturated solution of glucose and magnesium sulphate. " For Sugar (also glucose and dextrin, but not lactose or ardbin, which give no reaction) MASON'S test has been found fairly delicate and reliable, using 0.5 c.c. of the sus- pected glycerin, 15 c.c. distilled water, 2 drops of strong nitric acid, and 0.5 gram of amrnonic molybdate. On boiling for two or three minutes, or longer, if the quantity present be small, a blue colour is produced by the above substances; 0.25 per cent, may be readily detected. The chief points to be observed are that the liquid must not be too highly coloured, and the acid must not be in excess of the quantity mentioned. " ZSIGMONDY and BENEDIKT* have recently put forward a process for the estimation of glycerin, depending upon its oxidation by alkaline permanganate solution into oxalic * " Analyst," November 1885, p. 205. 288 CANDLES. acid ; the latter is precipitated by adding calcic acetate, and may be determined by titration with standard potassic per- manganate in an acid solution. Fatty acids have been found not to interfere with this reaction." For the manufacture of dynamite, which forms the great outlet at present for the large quantities of glycerin obtained from the soap and candle industries, distilled glycerin is alone of use ; and it must further answer the following conditions before it can be accepted as sufficiently pure for nitration : (1) Entire freedom from salt, iron, lead, lime, and fatty acids. (2) Complete absence of sugar (which can be present only as an adulteration). (3) The sample must be of good colour and practically odourless. (4) Specific gravity must at least reach 1.26. Olein. The olein obtained in the preparation of stearin (p. 231),* and known technically as oleo, is now largely employed in the manufacture of margarine. * For further details see " Oils and Varnishes," p. 18 ; and Cantor Lectures on "Milk Supply, Butter, and Cheese-making," by E. BANNISTER (April 1888). APPENDIX. Composition of Black Ash. i. 2. 3- CfI-VTT BROWN UKOEB. oTOH* and HANK. CYNASTOIT Sodium sulphate .... 1.99 i-54 0-395 chloride .... 2-54 1.42 2.528 ,, carbonate .... 23-57 44.41 36.879 silicate ..... 1.182 ,, aluminate .... 0.689 Soda caustic, hydrated . II. 12 Calcium carbonate .... sulphide .... 12.90 27.61 3.20 30.96 3-3I5 28.681 sulphite .... 2.1 7 8 Lime 7-15 8^35 9.270 Magnesia O.IO 0.254 Magnesium silicate .... 4-74 Alumina 0.79 I.I32 Water 2.IO 0.219 Ferric oxide i-75 2.658 Ferrous sulphide .... 2-45 0-371 Silica 0.89 Sand . . . . . 2.02 2.20 0.901 Charcoal i-59 5-32 7.007 Ultramarine ..... 0-959 Total ..'.... 99.78 100.93 98.180 APPENDIX. Strength of Solutions of Caustic Potash at 15 C. (59 F.) (TUNNERMANN). Density. K 2 in ioo Parts. Density. K 2 Oin ioo Parts. 3300 28.290 I.I437 14.145 S^r 27.158 1.1308 13.013 .2966 26.027 I.U82 11.882 .2805 24.895 1.1059 10.750 .2648 23.764 1.0938 9.619 2493 22.632 1.0819 8.487 .2342 21.500 1.0703 7-355 .2268 20.935 1.0589 6.224 .2122 19.803 1.0478 5.002 .1979 18.671 1.0369 3.961 .1839 17.540 1 .0260 2.829 .1702 16.408 I.OI53 1.6 9 7 .1568 15.277 1.0050 0.566 Density of Caustic-potash Solutions (SCIIIFF). Density. KHOin ioo Parts. Density. KHO in ioo Parts. .036 5 .411 40 .077 10 475 45 .124 15 539 50 175 20 .604 55 .230 25 .667 60 .288 30 .729 65 349 35 .790 70 APPENDIX. 291 Strength of Solutions oj Caustic Soda at 15 0. (59 F.) (TtJNNERMANN). Density. Na 2 O in ioo Parts. Density. Na s O in ioo Parts. 1.4285 30.220 1.2392 15.110 I-4I93 29.616 1.2280 14.506 1.4101 1.4011 29.011 28.407 1.2178 1.2058 13.901 13297 1.3923 27.802 1.1948 12.692 1.3836 27.200 1.1841 I2.o88 I-375I 26.594 LI734 11.484 1.3668 25.989 1.1630 10.879 1-3586 25.385 1.1528 10.275 I-3505 24.780 1.1428 9.670 1.3426 24.176 I.I330 9.066 1-3349 23-572 1-1233 8.462 I-3273 22.967 I."37 7.857 1-3198 22.363 1.1042 7-253 I-3I43 21.894 1.0948 6.648 1-3125 21.758 1.0855 6.044 I-3053 1.2982 21.154 20.550 1.0764 1.0675 5-440 4.835 1.2912 1-2843 19-945 19-341 1.0587 1.0500 4.231 3.626 1-2775 1.2708 18.730 18.132 1.0414 1.0330 3.022 2.418 1.2642 17.528 1.0246 1.813 1.2578 16.923 1.0163 1.209 I-25IS 16.319 1.0081 0.604 1.2453 I5-7I4 U 2 292 APPENDIX. Soda Ash : Table of Percentages of Soda and Sodium Car- bonate corresponding to "English" and DECROIZILLBS' Degrees. Percentage of Degrees. Percentage of Degrees. Soda. Sodium Carbonate English DECEOI- ZILLES*. Soda Sodium Carbonate English DECEOI- ZILLKS'. 30.0 51.29 30.39 4742 49.0 83.78 49.64 77-45 30.5 52.14 30.90 48.21 49-5 84.64 50.15 78.24 31.0 53-00 3MI 49-00 50.0 85-48 50.66 79-03 31-5 53-85 3i-9i 49-79 50.5 86.34 51.16 79-82 32.0 54-71 32.42 50.58 51.0 87.19 5L67 80.61 32-5 1 55-56 32-92 51-37 5i-5 88.05 52.18 81.40 33-o 56.42 33-43 52.16 52.0 88.90 52.68 82.19 33-5 57-27 33-94 52.95 52-5 89.76 53-19 82.98 34-0 58-13 34-44 53-74 53-o 90.61 53-70 83.77 34-5 58-98 34-95 54-53 53-5 91.47 54-20 84-56 35-o 59-84 35-46 55-32 54-o 92.32 54.71 85-35 35-5 60.69 35-96 56.11 54-5 93.18 55-22 86.14 36.0 6i-55 36.47 56.90 55-o 94-03 55.72 86.93 36.5 62.40 36.98 57-69 55-5 94.89 56.23 87.72 37-o 63.26 37-48 5848 56.0 95-74 56.74 88.52 37-5 64-11 37-99 59-27 56.5 96.60 57.24 89-31 38.0 64.97 38-50 60.06 57-o 97-45 57-75 90.10 38.5 65.82 39-oo 60.85 57-5 98-31 58.26 90.89 39.0 66-68 39-51 61.64 58.0 99.16 58-76 91.68 39-5 67-53 40.02 62.43 58-5 1 00.02 59-27 92.47 40.0 68.39 40.52 63.22 59-o 100.87 5977 93.26 40-5 69.24 41.03 64.01 59-5 101.73 60.28 94-05 41.0 70.10 41-54 64.81 60.0 102.58 60.79 94.84 41-5 70.95 42.04 65.60 60.5 103.44 61.30 95-63 42.0 71.81 42-55 66.39 61.0 104.30 61.80 96.42 42-5 72.66 43.06 67.18 61.5 105-15 62.31 97-21 43-o 73-52 43-57 67.97 62.0 106.01 62.82 98.00 43-5 74-37 44.07 68.76 62.5 106.86 63-32 98.79 44-o 75-23 44-58 69-55 63.0 107.72 63-83 99-58 44-5 76.08 45-o8 70.34 63-5 108.57 64-33 100.37 45-o 76.95 45-59 7i-i3 64.0 109.43 64.84 101.16 45-5 77.80 46.10 71.92 64-5 110.28 65-35 101.95 46.0 78.66 46.60 72.71 65.0 111.14 65-85 102.74 46.5 79-51 47.11 73-50 65-5 111.99 66.36 103-53 47.0 80.37 47.62 74-29 66.0 112.85 66.87 104.32 47-5 81.22 48.12 75.08 66.5 113.70 67-37 105.11 48.0 82.07 48-63 75-87 67.0 114.56 67.88 105.90 48.5 82.93 49.14 76.66 67-5 115.41 68.39 106.69 APPENDIX. 293 Soda Ash : Table of Percentages of /Sbrfa, <0c. (continued). Percentage of Degrees. Percentage of Degrees. Soda. Sodium Carbonate. English. DECBOI- ZILLES'. Soda. Sodium Carbonate. English. DKCROI- ZILLBS*. 68.0 116.27 68.89 107.48 73-0 124.81 73.96 H5-39 68. s II7-I2 69.40 108.27 n-s 125.66 74-47 116.18 69.0 117.98 69.91 109.06 74.0 126.52 74-97 116.97 69- S 118.83 70.41 109.85 74.5 127.37 75-48 117.76 70.0 II 9 .6 9 70.92 1 10.64 75-o 128.23 75-99 118.55 70-5 120.53 71-43 111.43 75-5 129.08 76.49 "9-34 71.0 121.39 71-93 112.23 76.0 129.94 77.00 120.13 7-1-5 122.24 72.44 II3.O2 76-S 130.79 77-51 120.92 72.0 123.10 72.95 II3.8I 77.0 I3I-65 78.01 121.71 72-5 123-95 73-45 II4.6O 77-5 132.50 78.52 122.50 Exports of Soap and Candles. Year. Soap. Candles of all Sorts. Cwts. Value. Lbs. Value. 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 335,592 383,910 391,808 353,733 409,907 391,788 476,438 402,254 426,904 451,961 405,183 432,699 440,286 397,516 458,381 449,804 547,613 472,519 446,710 451,246 5,345,900 4,790,800 5,051,800 5,071,700 4,992,744 5,285,600 7,703,400 7,810,400 8,967,100 9,321,600 170,161 135,852 143,231 137,677 135,051 147,961 213,635 200,179 201,919 180,912 1886 426,904 446,710 8,967,100 201,919 1887 451,961 451,246 9,321,600 180,912 Imports of Tallow and Stearin. From Year. Russia. Argentine Republic. United States. Australia. Other Countries. Cwts. Cwts. Cwts. Cwts. Cwts. 1878 73,646 66,754 455,991 216,722 105,820 1879 48,401 59,988 564,489 361,124 137,651 1880 25,505 103,665 516,715 492,527 178,678 1881 24,378 21,778 4I3-904 598,962 133,629 1882 33,497 128,119 291,641 434,415 | 231,167 1883 6,171 72,075 333,358 445,726 179,897 1884 14,724 97,703 332,45? 477,680 187,315 1885 7,172 107,301 241,685 410,439 243,959 1886 35,579 55,677 337,443 388,628 193,069 1887 6,532 22,209 329,367 416,658 j 120,892 294 APPENDIX. Statistics of Soap and Candle Factories in the United States (1880).* No. of establishments 629 Capital $14,541,294 Average No. of hands employed : Males above sixteen years .... 4,368 Females above fifteen years .... 388 Children and youths 533 Total amount paid in wages during the year $2,219,513 Value of materials $19,907,444 products $26,552,627 * "Report of the Manufactures of the United States (Tenth Census, 1880)." Published 1883. INDEX. ABEL'S soap, 168 Abietic anhydride, 23 Acetic series of fatty acids, 54 Acidification process, 241 Acids, fatty, tables of, 54, 55 Acrylic series of fatty acids, 55 Action of soap in removing dirt, 4 Alkalies, 23 Alkalimetry, 49 Almond oil, 20 Aluminate of soda, 31 Aluminium soap, i Animal fats, 18 Analyses of carbolic soaps, 200 castor-oil soaps, 14 caustic sodium silicate, 29 cold-water soap, genuine, 169 English, 201 cotton-oil soap, 14 fancy soaps, 202 fulling soap, 163 German soaps, 201 household soaps, 202 Jarrow refined soda ash, 159 medicinal soaps, 150 Natrona refined saponifier, 32 Analyses of neutral sodium silicate, 29 oleic-acid soap, 159 olive-oil soap, 14 over-fatty normal soap, 154 palm-oil soap, 14 primrose soap, 106 soaps for dyeing and print- ing, 165 for madder colours, 166 sodium aluminate, 31 tallow soap, 14 Apparatus for distillation of stearin, 245 and arrangement of the soap factory, 59 Appendix, 289 Arachis oil, 21 Aromatic mouth soap, 149 antiseptic tooth soap, 149 Arrangement of the soap factory, 77 Artificially mottled soaps, 100 Autoclave process, 248 B BARKING, 72 Baume's hydrometer, 48 comparison, with specific gravities, 47, 48 2 9 6 INDEX. Bauxite, 31 Beech oil, 20 Berry wax, 219 Berthelot's researches, 279 Berzelius theory of the decom- position of soap, 5 Beyer's crushing mill, 138 hand-cutter, 136 plodding machine, 140 rotary cutter, 136 Black ash lyes from, 24 composition, 289 .Blake and Maxwell's process for mottled soap, 100 Bleaching bees'-wax, 213 fats, 39 palm oil, 39 tallow, 41 by bleaching powder, 41 by chlorine, 40 by Dunn's method, 41 by nitric acid, 40 by Watt's process, 39 Bock's process, 249 advantages of, 251 Boiling under pressure, 64, 86 Bone boiling, 43 Seltsam's method, 43 grease, 18 Boomer and Boschert press, 33, 34 Borax soap powder, 174 Brown-oil soaps, 156 Bye-products, 275 CABLE candles, 273 Cacao butter, 21 Calculation of proportions of fat and alkali necessary for sapo- nification, 55, 56 Camphorated sulphur soap, 151 Candle manufacture, 256 basting, 269 cutting and polishing, 268 dipping, 256 machine, 257 filling can, or jack, 262 machine for cutting conical ends, 264 moulding, 258 composite candles, 267 paraffin ,, 267 sperm ,, 266 stearin ,, 266 tallow , , 265 machines, 258 Biertumpfel's, 260, 261 Cowles', 263 hand-frames, 258 scoop, 262 specialities, 271 Sweetser, Bell, and Bohm's process, 272 wax candles, 269 tapers, 270 Candle materials, 210 animal fats, 210 fatty acids, 210 vegetable oils, 210 waxes, 210 Candle-nut tree, 208 Candles, 205 Belmont sperm and wax, 271 bending point, 274 bye-products, 275 cable, 273 coloured, 273 composite, 267 decorated, 272 definition, 205 double and treble wick, 271 exports of, 293 INDEX. 297 Candles, fatty acids for, 235 history, 234 hydraulic pressed, 271 hygienic, 272 illuminating value of, 274 King Alfred's, 206 materials for, 210 ornamental, 272 ozokerit, 271 paraffin, 267 quality of, 274 sperm, 266 spiral, 273 stearin, 266 tallow, 256, 265 twisted, 273 wax, 269 Wright's pulmonic, 272 Capacity of boilers, 61 Carnauba wax, 217 Carpenter's classification of soaps, 8 1 Castor oil, 19 soap, 151 Caustic potash solutions, strength of, 290 soda solutions, strength of, 291 soda lyes, 23 Characters of soap, B.P., 15 Chevreul's researches, 51 Chinese wax, 215 vegetable tallow, 217 Chlorinated soap, 151 Clarifying, 98 Classification of processes, 81 Carpenter's, 81 Wright's, 8 1 Cleansing, 83, 102 Clear-boiling, 98 Close state, 83 Cocoa-nut oil, 21 Cocoa-nut oil, imports of, 107 saponification of, 107 Coco-stearin, 232 Coction, 97 Cod-liver oil, 19 Cold process, 87 advantages and disadvan- tages of, 88 apparatus, 64 Cold-water soap, 168 composition of genuine, 169 Colophony, 17 Colophonic acid, 23 Coloured candles, 273 Colouring for soaps, 101 Colza oil, 21 Cotton-seed oil, 19 Commercial soaps, various kinds, 88 Common salt, effect of excess of, 85 Comparison of soaps, 201 Comparison of English and colo- nial soaps, 202 Composition of fats, 51 Copper soap, i Cost of yellow soap, 106, 201 Crutching, 71 machine, Strunz's, 71 Cryolite, 31 Curb, 60 Curd, 83 Curd soap, B.P. characters of, 15 Cutting soap blocks, 72 Cutting the pan, 98 D D'ARCET'S method of rendering fats, 35 Davis's alk-alumino-silicic soap, 114 2 9 8 INDEX. Dechan on pharmaceutical soaps, 144 and Maben on the forma- tion of soap, 53 Definition of candle, 205 soap, i Dentier, 72 Detergent mixture, 28 Disinfecting soap (Jeyes'), 152 Dissociation by heat, 247 Drying oils, 19, 20 Doodoe nuts, 209 Dunn's method of making alka- line silicates, 29, 115 yellow soap, 103 Duty on candles, 208 repealed, 208 soap, 3 repealed, 4 Dynamite manufacture, glycerin for, 288 E EGG oil, 1 8 Eichbaum's soap, 169 Empatage, 97 Ethereal salts, decomposition of, 53 Exports of soap and candles, 293 F FANCY soaps, 117 analyses of, 202 Fat, glue, 1 8 Fats, rendering, 32 Fatty acids, 234 acidification process, 241 autoclave process, 248 Bock's process, 249 Fatty acids, dissociation by heat process, 247 lime saponification process, 235 history of, 234 preparation of, 235 Filling can, or jack, 262 Filled soap, 15 Finishing soap, 83 Fish oils, 19 soap from, 169 Fitting, 83 Fob, 102 Frames, 68 Free acid process, 65 Fulling soap, 163 GALAM butter, 21 Gall soap, 151 Glue fat, 1 8 lime in, 39 Gossage's method of preparing- alkaline silicates, 28 Grain soap, 10, 83 Grease, bone, 18 horse, 18 recovered, 17 Ground-nut oil, 21 Glycerin, 278 for dynamite manufacture, 288 recovery from spent lyes, 176 Allan's method, 176 Allen and Nickel's me- thod, 176 Benno, Jappe, & Co.'s method, 177 Clolus' method, 177 Fleming's method, 177 O'Farrell's method, 17 INDEX. 299 Glycerin, recovery from spent lyes Payne's method, 178 Reynolds' method, 178 Thomas and Fuller's method, 179 V enables' method, 179 Versmann's method, 179 Young's method, 180 removal from fats before saponification, 280 sp. gr. of aqueous solutions of, 280 testing, 281 Jean on, 281 Sulman and Berry on, 282 II HAND, or skin, soap, 169 Hard soap, I, 90 B.P. characters of, 15 Heating soap-boilers, method of, 61 Heel balls, 217 Hemp-seed oil, 19 Hersey's steam pump, 66 History of candles, 205 soap, 2 Horse grease, 18 Household soaps, 90 Hydrated soaps, 107 Blake and Maxwell's process for, 109 Hydrolysis, 6 Hydrometer, Baume's, 46 comparison of, with spe- cific gravities, 47, 48 theory of, 45 Twaddell's, 48 Hydrometers, 45 ICHTHYOL, 155 soap, 155 Illipa oil, 21 Imports of cocoa-nut oil, 107 palm oil, 107 stearin, 293 tallow, 293 Index to size of wicks, 254 Industrial soaps, 163 calico printing and dyeing, 164 Daumas d'A116on's, 165 fulling, 163 ox-gall, 163 removing stains, 166 silk dyers', 166 throwsters', 166 Iodine soap, 151 J JAPAN wax, 218 Jarrow refined ash, composition of, 159 Jevons, Prof., on pedetic action, 4 Jeyes' disinfecting soap, 152 K KILLING the goods, 82 King Alfred's candles, 206 Kingzett's definition of soap, 2 liquid soaps, 152 Kitchen stuff, 18 Koettstorfer's saponification equivalents, 56 Kottula's compact neutral soap, 169 hand, or skin, soap, 170 300 INDEX. LARD, 18 Large boiler process, 60 Lather, 4 Lead soap, i Leaves, soap, 153 Liebig on behaviour of soap with salt, 9 Lime, in glue fat, 39 saponification process, 235 Linseed oil, 20 Liquefying, 99 Liquored soap, 15 Little pan process, 60, 64 London soap powder, 174 Lye tanks, 59 testing, 26, 45 Lyes, spent, composition of, 175 Lancashire, 176 M MADRAGE, 97, 99 Manganese soap, i Manteau Isabelle, 99 Materials for candles, 210 for soap, 17 Medicinal soaps, 145 table of analyses (Dechan's), 150 Melting point of paraffin, me- thods of taking, 229 American, 229 English, 229 Mercurial soaps, 152 Mercury soap, i Merryweather's apparatus for rendering fats, 38 Milling process for toilet soaps, 136-144 advantages of, 144 Mineral waxes, 219 Morfit's definition of soap, i process for oleic-acid soap, 156 steam series, 62 Mottling, 97, 99 Myrtle wax, 219 X NATEONA refined saponifier, 32 Neat soap, 102 Neutral soap, Kottula's, 169 Miahle's, 131 Night-lights, 268 O OBJECTIONS to rendering fats by open fire, 35 Oil, almond, sweet, 20 arachis, 21 beech, 20 castor, 19 cocoa-nut, 21 cod-liver, 19 colza, 21 cotton-seed, 19 Dilo, 19 egg, 1 8 ground-nut, 21 hemp-seed, 19 Illipa, 21 linseed, 20 olive, 21 palm, 22 kernel, 22 nut, 22 poppy-seed, 20 rape, 21 seal, 19 sperm, 19 INDEX. 301 Oil, sunflower-seed, 20 tallow, 1 8 Tamanu, 19 whale, 19 Oleic acid, 274 conversion of, into palmitic acid, 274 soaps, 156 Olein, 288 Open boiling, 60 Over-fatty ichthyol soap, 155 marble soap, 155 normal soap, 154 Ox-gall soap, 163 Ozokerit, 230 refining, 230 PALM oil, or butter, 22 imports of, 107 kernel oil, 22 nut oil, 22 Paraffin, preservation of lyes by, 27 refining, 219 Tervet on, 221 Pasting, 82, 97 Pearl soap powder, 174 Pedesis, 5 Pedetic action, 5 Persoz on decomposition of soap by water, 5 Pickling wicks, 254 Pimaric acid, 23 Piney oil, or tallow, 211 Pinic acid, 23 Pliny's account of soap, 2 Poppy-seed oil, 20 Potash lyes, 26 Potassium silicate, 29 Powders, soap, 174 Powders, borax, 1 74 London, 174 pearl, 174 soap extract, 174 washing, 174 wool-washing, 174 universal washing, 1 74 Preliminary boiling of soap, 97 treatment of fats, 32 Preservation of lyes, 27 Primrose soap, analysis of, 106 Processes Abel's, C. D., 168 acidification, 241 autoclave, 248 Bennett and Gibbs', 88 Blake and Maxwell's, for hydrated soap, 109 for mottled soap, 100 Bock's, 249 boiling under pressure, 64, 86 cold, 64, 87 dissociation by heat, 247 Dunn's, 103, 115 Eichbaum's, 169 free acid, 65 Gossage's, in Jennings', 106 Kottula's, 169 lime saponification, 235 Meinecke's, 105 Morfit's, 156 Normandy's, 115 open boiling, 60 Eadisson's, 275 Sheridan's, in Tilghmann's, 247 Way's, 29, 114 Wilson and Payne's, 247 Properties of soap, 4 302 INDEX. RADISSON'S process for conver- sion of oleic into palmitic acid, 275 Ralston' s soap slabber, 74 Rape oil, 21 Recovered grease, 17 Recovery of glycerin from spent lyes, 175 Allan's method, 176 Allen and Nickel's method, 176 Benno, Jappe, & Co.'s me- thod, 177 Clolus 1 method, 177 Fleming's method, 177 O'Farrell's method, 178 Payne's method, 178 Reynolds' method, 178 Thomas and Fuller's method, 179 Venables' method, 179 Versmann's method, 179 Young's method, 180 Red-oil soaps, 156 Relargage, 97 Rendering fats, 32 D'Arcet's method, 35 Merry weather's superheating apparatus, 38 objections to open fire, 33 steam cylinder process, 36 Repeal of duty on candles, 208 on soap, 4 Rosin, 17 soap, 23, 101 Roth's sand soap, 171 Rotondi on decomposition of soap by water, 5 Rutschman's automatic chipper, 137 Rutschman's cake-cutting ma- chine, 142 continuous plodding ma- chine, 141 crushing mill, 139 soap press, 143 S SAL soda, 174 Salt, action of, on soap, 9, n, 12 Salted lye, 97 Salting process, 93 Salts, formation of, 50 Sand soap, 173 Sapo animalis, 147 calcis chlorinatce, 151 castil. alb., 147 mottled, 147 durus, 144 hydrargyri, 152 precipitati alb., 153 rubri, 153 mercurialis, 152 rnollis, 148 piceus, 153 terebinthinas, 153 Saponification, 50, 82 equivalents, 57, 58 under pressure, 86 Saponifier, Natrona refined, 32 Savon au bouquet, 132 a 1'huile de canelle, 132 au fleur d'oranger, 132 au muse, 133 4 la rose, 133 a la vanille, 1 33 Savonettes, 133 camphor, 134 honey, 134 mottled, 134 sand, 134 INDEX. 303 Savonettes, violet, 134 Scheurer on soaps for calico printing and dyeing, 164 Scribe, 72 Seal oil, 19 Separation of soap by salt, 1 1 by strong lye, 1 1 Separation of stearic and oleic acids, 252 Setting point of tallow, 211 Shanks' method of preparing lyes from black ash, 25 Shaving paste, 1 34 Shea butter, 2 1 Silicates, preparation of, 27-29 Sheridan's process, 27 Gossage's ,, 28 Dunn's 29 Way's 30 Silk dyers' and throwsters' soap, 166 Silver soap, I. Soap, Abel's, 168 action of, in removing dirt, 4 alk-alumino-silicic, 114 almond, 129 bitter, 130 aluminium, i ammoniated, 129 aromatic mouth, 149 antiseptic tooth, 149 beef marrow, 130 Berzelius theory of decom- position of, 5 boilers, 60 brown-oil, 156 caldrons, 60 calico printing and dyeing, 164 camphorated sulphur, 151 carbolic, 200 Castile, 97 Soap, castor-oil, 151 characters of, B.P., 15 chlorinated, 151 cocoa-nut-oil, 107 cold-water, 168 copper, i curd, 90 B.P. characters of , 15 English method, 90 German 93, 95 definition of, i disinfecting (Jeyes 5 ), 152 domestic, 90 duty on, repeal of, 4 Eichbaum's, 169 extract, 174 fancy, 117 filled, 15 floating, 130 fulling, 163 gall, 151 glycerin, 127, 130 grain, 10 hard, i characters, B.P., 15 history, 2 honey, 130 household, 90 hydrated, 107 hydrolysis of, 6 ichthyol, 155 industrial, 163 iodine, 151 Jevons on pedetic action, 4 kettles, 60 Kingzett's definition of, 2 Kottula's, 169 lard, 131 lather, 4 laundry, go lead, i leaves, 153 304 INDEX. Soap, Liebig on behaviour of, with salt, 9 liquid (Kingzett's), 152 liquored, 15 madder colours, 166 manganese, i marine, 107 Marseilles, 97 medicinal, 145 .mercurial, 152 mercury, i Miahle's neutral, 131 Morfit's definition of, I mottled, 96 oleic-acid, 156 olive-oil, 97 opaque toilet, 121 ox-gall, 163 pans, 60 pedetic action of, 5 Persoz on behaviour of, with water, 5 Pliny's account of, 2 preparation of, in small quantities, 171 properties of, 4 red-oil, 156 removing stains, 166 repeal of duty on, 4 Kotondi on action of, 5 samphire, 132 sand, 171, 173 separation of, by salt, 1 1 by strong lye, 1 1 silicated, in, 115 silk dyers' and throwsters', 1 66 silver, i slabber, 73, 74 sodium aluininate, 173 soft, i, 159 characters of, B.P., 15 Soap, soft Gentele's method, 162 Russian ,, 162 Scotch ,, 161 Starkey's, 153 suds, 4 sulphated, 115 tannin, 153 tar, 153 taxation of, 3 tin, i toilet, 117 transparent, 124 turpentine, 153 Unna's, 153 Venetian, 97 watered, i$ Whitelaw on action of salt on, 12 Windsor, 135 Wright and Thompson on hydrolysis of, 6 Wright's definition of, 2 wych -hazel, 155 yellow, 101 cost of, 106, 201 zinc, i Soda ash, lyes from, 23 Sodium aluminate, 31 soap, 173 ichthyosulphate, 155 silicate, 27 composition of, 29 Soft lyes, 97 soap, i, 159 Soluble glass, 27 Spent lyes, composition of, 175 Lancashire, 176 recovery of glycerin from, 175 Sperm oil, 19 Spermaceti, 19, 215 INDEX. 305 Stains, soap for removing, 166 Stamping soap, 77 Steam lyes, 26 series (Morfit's), 62 twirl ,, 156 Strength, 161 false, 161 Stearin, 231 Stone-wax, 217 Sunflower- seed oil, 20 Sylvic acid, 23 TALLOW, 18 oil, 18 Tamanu oil, 19 Taxation of soap, 3 Tannin soap, 153 Tar soap, 153 Tervet on refining paraffin, 221 Testing soaps, 181 Cailletet's method of deter- mining fatty acids, 192 determination of carbolic acid, 197 of cost of soap from analysis, 201 of glycerin, 193 Muter 's method, 195 estimation of detergent value, 191 Filsinger's scheme, 187 free alkali, 182, 184, 187, 189, 200 Leeds' method, 182, 185 Owens College scheme, 188 sampling, 181 Testing soda ash, 27 lyes, 26, 45 Theory of hydrometer, 45 Tin soap, i Toilet soaps, 117 apparatus, 117 by cold process, 125 by remelting, 123 by French system, 136 formulae for, 129 French system crushing and grinding, 137 cutting, 136 into cakes, 142 plotting, 140 stamping, 142 manipulation, 120 materials, 117 moulding, 119 opaque, 121 savonettes, 133 transparent, 124 Train oil, 19 Turpentine soap, 153 Twaddell's hydrometer, 48 U UNIVEESAL washing powder, 174 Unna's soaps, 153 VEGETABLE oils, 19-22 W WASHING powder, 174 Water, 32 Watered soap, 15 Way's process for alkaline sili- cates, 29 Whale oil, 19 X 306 INDEX. Whitaker's patent soap frame, 68 i Whitelaw on the action of salt j on soap, 12 Wicks, 253 pickling, 254 size of, 254 index to, 254 Windsor soap, 135 brown, 135 ordinary, 135 rose, 135 violet, 135 Weise's formula for, 135 Wool-washing composition, 174 Wright and Thompson on hydro- lysis, 6 Wright's classiLcatiou. of soaps, , 8l definition of soap, 2 Wych-hazel soap, 155 Y YELLOW soap, 101 cost of, 106, 20 1 ZALMON'S aromatic mouth soap, 149 Zawierciers soap for dyeing and printing, 165 Zinc soap, i PRINTED BV BALLANTYNE, HANSON AND CO. LONDON AND EDINBURGH RET Thi HOME USE CIRCULATION DEPARTMENT MAIN LIBRARY This book is due on the last date stamped below. 1-month loans may be renewed by calling 642-3405. 6-month loans may be recharged by bringing books to Circulation Desk. Renewals and recharges may be made 4 days prior to due date. ALL BOOKS ARE SUBJECT TO RECALL 7 DAYS AFTER DATE CHECKED OUT. wmi OCTH 1902 AUTO DISC. ,EP 3 1992 C1HCULATIQN LD21 A-40m-8,'75 (S77fttT General Library University of California Berkeley LD (El602slO)476B VB I I22D U.C.BERKELEY LIBRARIES TP330 THE UNIVERSITY OF CALIFORNIA LIBRARY