189. Sinapis nigra. 189a. Oleum Sinapis Volatile. 189b. Oleum Sinapis Expressum.
BOTANICAL CHARACTERISTICS.—Similar to S. alba (see above), but has larger flowers, a longer hispid silique, and a smaller blackish seed.
HABITAT.—Asia and Southern Europe; cultivated.
DESCRIPTION OF DRUG.—A globular seed about 1 mm. (1/25 in.) in diameter, with a circular hilum and a short beak not filled with albumen; testa hard, black, or reddish-brown, finely pitted. The yellow embryo and cotyledons are folded and bent along the midrib. Inodorous when dry, but pungent and penetrating when moist; taste hot, acrid. The powder should give only a faint reaction for starch by the iodine test. Ash, not exceeding 9 per cent.
Powder.—Characteristic elements: See Part iv, Chap. I, B.
ACTION AND USES.—Externally a powerful rubefacient and counter-irritant, internally emetic, especially valuable in cases of poisoning by narcotics from its reflex stimulation of the heart and respiration. Dose: 1 to 4 dr. (4 to 15 Gm.).
189a. Oleum Sinapis Volatile. U.S.P. IX. A product yielding not less than 92 per cent. of "allyl isothiocyanate." It is produced synthetically or obtained from the seed of Brassica Nigra by maceration with water and subsequent distillation, and must conform in name to the source from which it is derived.
Great caution should be exercised in smelling this oil. It should not be tasted except when highly diluted.
DESCRIPTION AND SOURCE.—Volatile oil of mustard is not contained as such in seeds but is formed by the decomposition of "sinigrin" or "potassium myronate" in the presence of emulsin. The ground mustard seed is deprived of its fatty oil with the aid of hydraulic presses. The press cakes are mixed with tepid water, allowed to undergo fermentation, and then distilled with water vapor. The yield varies between 0.5 to 0.75 per cent. of the original seed. At a temperature exceeding 70° C. (158° F.) no fermentation takes place because the myrosin is coagulated and rendered inactive.
PROPERTIES.—Oil of mustard is a colorless or yellowish, limpid and refractive liquid with an exceedingly pungent and acrid odor. Inasmuch as it draws blisters when in contact with the skin, it should not be tasted.
COMPOSITION.—In addition to "mustard oil," C3H5SCN, or allyl isosulphocyanate, the oil from black mustard contains variable amounts of "allyl cyanide," C3H5CN, and carbon disulphide, CS2.
ACTION AND USES.—Volatile oil of mustard is rarely given internally. Locally it may be employed as a counter-irritant. Diluted with olive oil, it may be used as a substitute for mustard papers and as a stimulating liniment. Dose: 1/125 mil (⅛ drops).
189b. OLEUM SINAPIS EXPRESSUM (Unofficial).—Crushed seeds of the black and white mustard yield, by cold expression, about 22 per cent. of a bright yellow (white) or brownish-yellow (black) oil, of a bland taste. This oil is a commercial oil and not infrequently used for the adulteration of other oils. Rapeseed, or colza, oil is obtained from the seeds of different varieties of the genus Brassica, rape (Brassica napus) in particular. In Europe the term rapeseed oil is sometimes applied to the product of rape alone, colza being restricted to the oil obtained from the ruta-baga, or Swedish turnip (B. campestris), while "Rubsen" oil is furnished by the common turnip (B. rapa). There is great confusion among authors in the use both of the common names of the oils and the scientific names of the varieties of Brassica which produce them. The seeds of rape contain from 33 to 43 per cent. of oil, which, when crude, is a dark yellow-brown and used for lubricating. Refined and freed from albumen and mucilage the oil becomes bright yellow. Rape oil is extensively used for lamps, lubricating machinery, and for adulterating both almond and olive oils.