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Shepton Mallet-G. F. Burroughs, Esq. South Petherton-Johu Nicholetts, Esq. Henry Coppock, Esq., Secretary. John Rundle, Esq., M.P. Truro-Henry Sewell Stokes, Esq. Tunbridge Wells-Yeats, M.D. Uttoxeter-Robert Blurton, Esq. Virginia, U. S.-Professor Tucker. Worcester-Chas. Hastings, M.D. C. H. Hebb, Esq. Wrexham Thomas Edgworth, Esq. John Phillips, Esq., F.R.S., F.G.8, THOMAS COATES, Esq., Secretary, No. 59, Lincoln's Inn Fields, London: Printed by WILLIAM CLOWES and Soxz, Stanford Street. THE PENNY CYCLOPÆDIA OF THE SOCIETY FOR THE DIFFUSION OF USEFUL KNOWLEDGE. STE This substance is procured from STEARIC ACID. stearin [STEARIN], which is a compound of stearic acid and a peculiar sweet substance called glycerin, which is treated of under the head of SOAP. When stearin is saponified by potash, stearate of potash is procured; and when warm dilute hydrochloric acid is added to the solution, the stearate is decomposed, chloride of potassium remains in solution, and the stearic acid is precipitated. The properties of this acid are, that it has the form of brilliant white scaly crystals; it is inodorous, tasteless, insoluble in water, soluble in its own weight of æther and in hot alcohol, and the solution reddens liimus-paper; but its acid action is feeble, for it expels carbonic acid from the alkaline carbonates only at a boiling heat. It melts at about 158° Fahrenheit, and on cooling it forms a crystalline mass; it is volatile, and may be distilled unaltered in close Its composition is vessels. In the air it burns like wax. somewhat differently stated by authors, but no one statement differs much from 68 equivalents of carbon 66 equivalents of hydrogen 5 equivalents of oxygen Equivalent 408 66 40 79.4 12.8 7.8 In the state of crystals it contains two equivalents of water 18, or nearly 34 per cent. It forms compounds with the alkalis, earths, and metallic oxides, which are called stearates. Stearate of Ammonia.-Stearic acid absorbs ammoniacal gas; the resulting compound is white, inodorous, and has an alkaline taste. It is dissolved by boiling water, and the solution, on cooling, deposits pearly crystals of stearate of ammonia. Di-stearate of Potash is formed by boiling equal weights of the acid and alkali dissolved in five times their weight of water. It forms a white granular compound, which is opaque, and may be purified by solution in boiling alcohol; as the solution cools, the salt separates in white brilliant scales. This compound may also be procured by treating potash soap with alcohol. It is composed of— One equivalent of stearic acid Two equivalents of potash Equivalent 514 96 610 Stearate of Potash is obtained by dissolving one part of potash soap made with suet and caustic potash, in six of hot water, and then adding about ten times their weight of cold water to the solution; the precipitate which results contains the stearate of potash mixed with margarate of the same base; from the latter it is separated by repeated treatment with alcohol, and is then obtained in soft silvery crystalline scales. P. C.. No. 1423. Di-stearate of Soda and stearate of soda may be obtained by processes similar to those described for the stearates of potash; they are less soluble than the salts of potash, and enter into the composition of hard soaps. Stearate of Lime, Stearate of Barytes, and Stearate of Lead, are all white insoluble powders, and are not applied to any useful purpose. Stearic Acid, besides its use in the manufacture of soap, is now very largely employed in the making of candles. STEARIN (from oréap, fat) is the harder portion of animal fats; olein, or elain, being the softer one. To obtain stearin in a pure state, mutton-suet is to be melted with ten times its weight of æther in a water bath; as the solution cools, crystals of stearin are deposited, which, after washing with cold æther, are to be strongly pressed. The properties of stearin are, that it has a pearly lustre, is soft to the touch, but not greasy; it melts at about 140° to 145° Fahrenheit; and, on cooling, solidifies into a mass, like wax, which is not crystalline in its texture, and is reducible to powder. Stearin is insoluble in water, but is dissolved both by hot alcohol and æther, from which it almost entirely separates on cooling; it possesses weak acid properties, and may be combined with potash; it is the chief and most important ingredient of the harder kinds of fat, and the harder they are the more they contain. Stearin is separable into two different principles, namely stearic acid and glycerin, as has already been noticed in the preceding article; it appears to be a bi-stearate of glycerin, consisting of Two equivalents of stearic acid |