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distilling the bruised bulbs. When purified, this oil is colourless, and may be distilled without decomposition. When garlic has been eaten, the odour of this oil may be detected in the various secretions of the body. Regarded by some as an anthelmintic.
Mixed with vinegar it is used as an astringent in relaxed sore-throat and relaxation of the vocal cords. It is also used in asthma, general paralysis, facial paralysis, gout and sciatica, much thought of in the treatment of flatulent colic. Supposed to prevent the hair turning grey when applied externally. (Dr. Emerson.) It is resolvent in indolent tumors. Is largely used as a liniment in infantile convulsions and other nervous and spasmodic affections. It is also frequently used as a poultice in retention of urine from debility of the bladder.
Garlics were found to yield 0'09 per cent, of their weight of a yellow-coloured, optically inactive, essential oil, which has the well-known intense odour ; its sp. gr. at 14.5° is 1.0525. It deposits a small quantity of crystals when cooled in a freezing mixture, does not contain oxygen, and decomposes when heated at 150°. The oil was fractionally distilled under a pressure of 16 mm.
Fraction 1 (6 per cent.) consists of allylpropyl bisulphide, C3H5S. S. Pr., a bright-yellow oil of sp.gr. 1.0231 at 15°, boiling at 66-69° (16 mm.), and having the odour of onions ; it gives voluminous precipitates with mercuric and auric chlorides, which are sparingly soluble in alcohol, and when treated with zinc-dust at 130°, yields a compound, C6H12S. It is decomposed by oxidising agents with the production of carbonic anhydride, oxalic acid, propionic and lower fatty acids, and sulphuric acid.
Fraction 2 (60 per cent.) is diallyl bisulphide, S2 (C3H5)2 , a light-yellow oil, having the odour of garlic ; it is rendered colourless by distilling with a little potassium when it passes over at 78-80" (16 mm.). It has a sp. gr. at 14.8°=1.0237 and, on reduction with zinc-dust, yields a compound, C6H10S, which boils under the ordinary pressure at 135-139° ; it also re-acts with potassium, decomposes into carbonic anhydrid, oxalic, formic, and acetic acids, on oxidation with nitric acid, combines with halogens, and does not re-act with mercuric oxide, even at 100°.
Fraction 3 (20 per cent.), representing the portion passing over between 112° and 122° (16 mm.), has the empirical formula, C6H10S3 , its sp. gr. at 15° being 1-0845 ; it yields the compound, C6H10S, when heated with zinc-dust.
Fraction 4 (10.5 per cent.) consists of the residue boiling above 122° (16 mm.) ; it decomposes if the distillation is continued. On analysis, values were obtained approximating to those required by the formula C6H10S4 .
Oil of garlic contains neither allyl sulphide nor a sesquiterpene. — J. Ch. S. LXIV., pt. I (1893), p. 103.