Collier's New Encyclopedia

A complete general encyclopedia of 1921 — the world as it was understood just after the Great War, from Aachen to Zwingli, across twelve volumes and six thousand pages.

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Glycerin

or GLYCERINE, triatomic alcohol of the fatty series, C3H8O3, or CH2 (OH)CH(OH)CH, (OH). Glycerin was discovered in 1778 by Scheele, ele, who obtained it in the preparation of lead plaster by saponifying lard with oxides of lead. Glycerin occurs in most natural animal and vegetable fats in combination with fatty acids, from which it can be obtained by saponifying with alkalies. It is also formed during the alcoholic fermentation of sugar. Pure glycerin is obtained by heating neutral fats in still, with a condensing apparatus, and passing steam in temperature being kept below 600° F., small jets through the melted fat, the and above 550° F.; the fat acids separate the melted fat, the out in the receivers from the glycerin and water; the glycerin is then concenglycerin trated by evaporation. Glycerin is a thick, colorless, inodorous, neutral syrup, which has a very sweet taste; it mixes with water in all proportions, is soluble in alcohol and in chloroform, but insoluble in ether. Glycerin distilled with phosphorous pentachloride, P₂Cls, yields acrolein. By the action of a mixture of equal parts of concentrated nitric acid and sulphuric acid, it is converted into NITROGLYCERIN, CH₂O (NO₂) CHO (NO₂)CH2O (NO2) (q. v.). Glycerin is used for preserving fruits, also as a solvent for various salts, and in preparing copying-ink; also as a lubricator for machinery and and clockwork, and is placed over water in gas meters to prevent freezing, and is used for filling floating compasses. It is employed in the form of nitroglycerin in the preparation of dynamite, and for mixing with soap to form glycerin soap, which tends to soften the skin.

Glycerin is used on account of its physical properties as an adjunct to lotions in skin diseases to prevent the surface becoming dry. It can be used as a substitute for sugar in the diet of diabetic patients.

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