STEA'RIC ACID AND bTEARINE. The composition of stearic acid is represented by the formula HO; this acid beingone of the solid fatty acids represented by the general formula C„11,0,,110. It exists as a glyceride (stearine) iu most fats, and is especially abundant in the more solid kin•ls, sack as mutton-seet. It is readily obtained by suet, an.I decompoiing the hot solutio t of the soap by tartaric acid. Toe, oily acids which are thus liberated are compressed between hot plates, by which mans mast of the oleic :tell (q.v.) which is present is expelled. The solid residue is then to be repeatedly crystallized from alcohol, and afterward from ether till the fusing point becomes constant at 159'. If the final solution is allowed to coal slowly, the acid is deposited in beautiful, colorless, transparent rhombic plates. After fusion, it cools into a wax-like, glistening, crystalline mass, devoid of taste or smell. It is insoluble in water, on wide!' it floats, but dissolves in alcohol and ether, its solution reddening litmus powerfully. When heated above its fusing-point, it becomes decomposed into Pallnilic acid (C3211,,O,,110), p•lmilon (Cesilis02), and an oily hydro-carbon. Stearic acid forms both normal and acid salts. The only normal stearates which :li•e soluble in water are the steal-ales of the alkalies, whose solutions are frothy and form am lather, but on the addition of an excess of water, separate into an acid salt which is deposited in silky crystalline plates, and the free alkali which remains in solution. The stearates of
the alkalies are also soluble in alcohol. Chloride of sodium (common salOhas the prop erly of separating the alkaline stearates front their solution. The stearates of the alka lies are the principal constituents of the different kinds of soap. The other stearates are insoluble. Stearate of lead, which is one of the constituents of lead plaster, is readily formed by mixing solutions of stearate of soda and acetate of lead, when the stearate of lead falls as a heavy amorphous precipitate, spariagiy soluble in alcohol or ether, but dissolving freely in oil of turpentine.
The basic acid extracted from the oil of the seeds of bassia latifolia, a tree growing in the Himalayas, and the stearophanic acid obtained from the berries of monospennum =odds, are identical with stearic acid.
The use of stearic acid in the manufacture of candles is described under the head CANDLE. See also 0 Ls.