Black mustard seeds and white mustard seeds powdered and mixed.

Sinapis Albae Semina, B.P.; Sinapis Alba, U.S.P. White Mustard Seeds. - The dried ripe seeds of Brassica alba (Sinapis alba, U.S.P.) Britain.

Sinapis Nigrae Semina, B.P.; Sinapis Nigra, U.S.P.

Black Mustard Seeds. - The dried ripe seeds of Brassica nigra (Sinapis nigra, U.S.P.)

The seeds of black mustard are very small, round, and brownish-black outside; those of the white are larger and yellow. Both are yellow inside.

Characters of the Powder. - Greenish-yellow, of an acrid, pungent taste, scentless when dry, but exhaling when moist a pungent, penetrating, peculiar odour.

Adulteration. - Starch.

Test. - A decoction cooled is not made blue by tincture of iodine.

Dose. - As an emetic, from one teaspoonful to a tablespoonful of mustard flour, mixed with a little water.

Composition. - The pungency of the moist powder is due to oil of mustard, but this does not exist in the seeds or fresh powder. Both black and white mustard contain a crystallisable substance, called in the black sinigrin, and in the white sinalbin, and an albuminous body myrosine. When moistened, both sinigrin and sinalbin are split up by the myrosine, which acts as a ferment, and yield a volatile oil. This is not quite the same in the two mustards, that from the black being more pungent; but the oil from both possesses powerful vesicating properties. The action of myrosine as a ferment is destroyed by a heat of 60° C.; so mustard poultices should not be made with boiling water. Black mustard contains less myrosine than white - too little, indeed, to decompose the sinigrin completely, so that its pungency may be increased by admixture with white as directed by the B.P., and as found in ordinary table mustards. Both mustards also contain a fixed oil.

Preparations

B.P. (of Mustard). Cataplasma Sinapis. Charta Sinapis. Oleum Sinapis.

u.s.p. (of Black Mustard). Charta Sinapis. Oleum Sinapis Volatile.