Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1898 Excerpt: ...mixture of fats present melting at about 26 C. Test of Melting Point.--Heat some beef-fat in a dry dish, avoiding too high a temperature, and filter the melted fat obtained through dry filter paper. A one-fourth inch glass tube is closed at one end by fusion and the cooled, solid, fat introduced. The tube is then fastened to the bulb of a thermometer and suspended with it in a beaker of water, care being taken that no water enters the tube. The temperature of the water is gradually raised and the temperature at which the fat softens is noted. This will be between 40 and 50 C. The fats vary in specific gravity from 0.91 to 0.97. They are insoluble in water and, generally, in cold alcohol, but are soluble in boiling alcohol, in chloroform, and, generally, in benzine and other petroleum products. Strongly heated they yield pungent, irritating fumes of acrolein. Decomposition of fat by putrefactive organisms results in the formation of propionic, acetic and formic acids--the fat becomes rancid. Decomposed by means of superheated steam, or by an alkali or metallic oxide, the fat yields glycerol and either the free fatty acid or a metallic salt of that acid known as a soap. The "saponifica tion" of a fat with formation of a "soft' potash soap may be indicated as follows: C3H5(C13H3302)3 + 3K0H = 3KC13H3302 + C3H5(0H)3. 0lein Potassium oleate. Glycerol. The ordinary soaps are soluble in water, but when added in excess the solution becomes turbid from a partial decomposition, free alkali and an insoluble acid salt being liberated. By addition of mineral acids the soap is decomposed and the fatty acid set free. KC13H3302 +HC1 = HC18H3302 +KCl. By addition of sodium chloride a ' soft' potash soap may be transformed into a "hard" soda soap. KC...
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