GARLIC, OIL OF. When cloves of garlic are distilled with water, about 0.2 per cent. of a brown heavy oil, with an'acrid taste, and a strong disagreeable smell, passes over. • By careful rectification from a salt water bath, about two thirds of the oil may be obtained in the form of a yellow liquid, which is lighter than water, and which, when treated with chloride of calcium (in order to dry it), and subsequently distilled from fragments of ,potassium, comes over pure and colorless as sulphide of allyl, an organic compound of very considerable interest, whose formula is The crude oil also contains oxide of allyl (06116,0), and a compound of ally! still richer in sulphur than the sulphide.
Sulphide of allvl exists not only in oil of garlic, but also in fife oils of onions, leeks, cress, alliaria, radishes, asafetida, etc. It is a light, clear, pale-yellow oil, with a pen etrating odor of garlic; it boils at 284% and dissolves readily in alcohol and ether.
Sulphide of ally1 may be obtained from essential oil of black mustard (which in its purified form •is represented by and may consequently be regarded as sulphocyanide of ally!) by distillation with sulphide of potassium. The reaction is .exhibited in the following equation: Oil of Mustard. Sulphide of Sulphide of Sulphocyanide Potassium. of Potassium.
± KS = K, We may perform the converse experiment, and obtain oil of mustard from oil of garlic by mixing alcoholic solutions of sulphide of ally! and corrosive sublimate, when a white precipitate is formed, represented by CelleS,2HgS and distill ina this compound with sulphocyanide of potassium, in which case oil of mustard will be found among the products.
The pungency of horse-radish, scurvy-grass, and other allied plants, is clue to the presence of this essential oil of mustard or sulphocyanide of allyl.
We shall postpone the further consideration of sulphocyanide of allyl to the article 3ItsrAnn, OIL, OF, but shall take this opportunity of very briefly noticing the chief members of the ally! series, which has recently been studied with very fruitful results by several of our most eminent chemists.
Free ally! or, more probably, is a very volatile combustible fluid, with a combined odor of ether and radishes. It is obtained by the action of sodium on iodide of allyl.
Allylic alcohol (C6H60,H0) is metameric with acetone and propylic aldehyde, but it differs from them in its properties. It is obtained by the action of ammonia on oxa late of allyl.
Ally' ether or oxide of ally! has been formd in at least two different ways, but the reactions accompanying its formation are too complicated for notice in this article. In exists ready formed in small quantity in oil of garlic, .and some other oils that resemble it, and may be obtained by the decomp.sition of oil of black mustard.
The chloride, bromide, and iodide of allyl have all been obtained. The iodide is a colorless fliquid, of specific gravity 1.789, with an, ethereal and somewhat alliaceous odor. It is decomposed iiy digestion with a watery solution of ammonia, and on dis tillation with potash, a base with a fishy aminoniacal odor is formed. It is probably allylia, or allyl-amine or C6116,HeN), the basic volatile alkali of the allylic series, which has also been obtained by a different process,. and corresponds to ethylia or ethyl-amine in the ethylic series.—Miller's Elements of Chemistry, 2d edit., vol. 3, pp. 574-584; Gorup-Besanez, Lehrbuch d. Chemie, vol. 2, pp. 266-272; and the recent memoirs of Berthelot end Luca, Hofmann and (labours, etc.