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Previous Next The best candle and soap tips online! here more unfavorable than was stated above, or perhaps for the reason that the greater solubility of the cold soap brought with it a larger consumption. CAILLETET'S PROCESS. It may interest the manufacturer to read the details of this process, which we give in full from the Bulletin de la Societe Industrielle de Mulhouse (No. 144, vol. xxix. p. 8). Characteristics of the Aqueous Solutions of Soaps, Normal Acid, and Alkaline Liquor.—The soaps used in industry are formed of fatty acids, of soda and potash, and water. These acids, which are solid or liquid at the ordinary temperature, are extracted from fatty substances of animal or vegetable origin. The soap of oleic acid often contains rosin. The white soap obtained by the Marseilles process is formed of:— 60 to 64 parta of fatty acids. 30 to 36 " water. 6 " soda. Some white soaps are met with in the trade which contain from 40 to 50 per cent, of water. The marbled soap cannot contaiu more than thirty-four per cent. When the soap separates from a saturated saline solution, it is formed of:— 77 7 16 Fatty acids Soda . Water . When anhydrous the same soap contains:— 91 9 Fatty acids . Soda . In certain industries, soaps are used into which there enters more than six per cent, of soda. These soaps by their excess of alkali, and according to their mode of fabrication, may be hydrated enough to contain from 50 to 60 per cent, of water. 366 TECHNICAL TREATISE ON SOAP AND CANDLES. SOAP ANALYSIS. 367 The fatty substances which enter into the composition of soaps are generally oleic, margaric, stearic, and palmitic acids. The more or less consistency of the aqueous solution of a soap is due to the presence of solid fatty acids, or to an excess of alkali. To prepare an aqueous solution of soap, take ten grammes of the soap to be tested, introduce it into a wide-mouthed bottle and add 90 grammes (3.15 ozs.) of cold distilled water, and dissolve over a water-bath. Introduce this solution into a test tube of a capacity of 100 cubic centimetres (3.38 fl. ozs.), and one hour after, examine its consistency. Hard soaps generally give a solution which by cooling forms an opalescent mass, in which crystallizations are often seen after it has been prepared for some time. Diluted with cold water, this solution divides into an acid salt which deposits, and an alkaline salt which remains in solution. The acid salt sometimes deposits in the form of a flaky substance, without consistency; it is ordinarily richer in solid acids than in liquid; sometimes, as with a solution of soap of cocoa-nut oil diluted with its volume of water, the acid salt which deposits assumes a crystalline form, and remains attached to the edges of the vessel in which the mixture has been kept. A warm solution of 10 grammes (.35 oz.) of soap of olive oil, and 90 grammes (3.15 ozs.) of distilled water, is transparent as long as the solution is warm, but as soon as it cools down it becomes more and more opalescent, andJastly, when cold, it is entirely opaque. Its consistency has some anology with that of the white of egg; it can be drawn in threads, and a few days after preparation it has lost some of its consistency. If in the soap which has been dissolved, there have entered fatty acids due to a mixture of sesame and olive oils, olive oil and earth-nut oil, etc., the solution is less opaque and has not so much consistency as that produced with olive-oil soap alone. If in the composition of this latter there enters cocoa-nut oil, the solution is partly curded. A solution of soap of cocoa-nut oil diluted with its volume of water produces, after a rest of twelve hours, an abundant and crystalline precipitate; the liquor is colorless. Generally, a solution made with 10 grammes (0.3T OZ.) of soap and 90 grammes (3.15 ozs.) of distilled water gives, by cooling, a solution much more opalescent and with more consistency, when it contains more solid acids and alkali. Soaps manufactured with solid fatty acids give a solution which is solid. Thus 3 grammes (46.29 grains) of soap of tallow, and 97 grammes (3.39 ounces) of water, produce a solid solution. Soaps in which liquid fatty acids predominate give generally a colorless solution at a temperature of 85° to 100° C. (185° to 212° F.). When the fatty acids predominate, as in the tallow soap, the solution looks flocculent. If the soap contains rosin, the solution at 185° to 212° F. is very opaque, and after being prepared a few hours it separates into three parts. The upper part, which is nearly transparent, contains very little rosin and much alkali; the middle part is entirely opaque; the lower part is formed with a white substance which has deposited and which looks like pure rosin combined with very little alkali. All soaps are heavier than water; they do not act in the same manner when in contact with warm water. If a piece of soap weighing 10 grammes (0.35 oz.) is introd uced into a wide-mouthed bottle containing 90 grammes (3.15 ounces) of cold distilled water, and if the whole is heated over a water-bath, the soaps manufactured with olive oil, palm oil, tallow, oleic acid, etc., will float on the surface and become transparent from the circumference to the centre ; soon by their contact with warm water, their transparency is complete. The contrary takes place, if the soaps have been manufactured with cocoa-nut oil or rosin ; they remain at the bottom of the vessel and dissolve very easily. The soaps of olive oil, tallow, etc., retain their transparency all the while they are in contact with warm water. If this transparent soap is taken from the warm water, it will retain its transparency for some time; but if the soap is half out of the water and is allowed to cool, the part in 368 Previous Next
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