Action and Uses: Mustard is used extensively as a counterirritant. When mustard is mixed with water, the volatile oil is generated by the action of a ferment, myrosin, on a principle called sinigrin, contained in black mustard.

Sinapis Nigra.—Black Mustard, U. S. P.

The Seed Of Brassica Nigra. Dosage: As An Emetic, 8 Gm. Or 120 Grains.

Charta Sinapis.—Mustard Paper, U. S. P.

A coating of black mustard on rather thick, well-sized paper used in place of the domestic mustard poultice.

Oleum Sinapis Volatile.—Volatile Oil Of Mustard, U. S. P.

A volatile oil obtained from black mustard by maceration with water and subsequent distillation, yielding, when assayed by the process given in the U. S. Pharmacopeia, not less than 92 per cent, of allyl isothiocyanate.

Properties : Volatile oil of mustard occurs as a colorless or pale yellow, limpid liquid, having a very pungent and acrid odor. Great caution should be exercised when smelling this oil, and it should not be tasted without being highly diluted. It is miscible with alcohol in all proportions, and is generally soluble in liquids containing alcohol.

Action and Uses: See Sinapis. Dosage: 0.008 c.c. or 1/8 minim.