White Mustard

Sinapis Alba. U. S. - Sinapis. Br. Black Mustard. - Sinapis Nigra. U. S. - Sinapis. Br.


Under these titles are included the two species of Sinapis, the Sinapis nigra and S. alba, or black and white mustard. Both of these plants are natives of Europe, and both cultivated in our gardens.

1. Black Mustard Seed

Sinapis Nigra. - These are roundish, about the size of a small pin's head, somewhat rugose on the surface, of a dark-brown or reddish-brown colour externally, yellow within, inodorous in the whole state, slightly odorous when bruised, of a pungent odour upon contact with water, and of a hot, very pungent, bitterish, and oleaginous, but not very durable taste. Their powder is originally yellowish-gray, owing to the intermixture of particles of the brown coating, from which it is separated by sifting, and thus becomes purely yellow. it is sometimes, however, in its original state, as kept by the druggists.

2. White Mustard Seed

Sinapis Alba. - White mustard seeds are also roundish, somewhat larger than the black, of a dull-yellowish colour externally, yellow within, inodorous, and of a taste similar to that of the black, but less pungent. They are peculiar in yielding to hot water a large proportion of thick mucilage. They have already been considered, in reference to a laxative property possessed by them (II. 499).

Common Properties. When pulverized and sifted, mustard seeds yield a yellow powder, usually called flour of mustard, or simply mustard, much used as a condiment. From the siftings, there is obtained by compression a bland fixed oil, occasionally used in the arts. The sifted powder is often mixed with wheat flower, coloured with turmeric, and rendered pungent by Cayenne pepper, before being delivered to commerce. The apothecary should endeavour to supply himself with the unadulterated powder. This is soft, of an unctuous aspect, and somewhat disposed to cake. it imparts its virtues wholly to cold water, but imperfectly to alcohol.


Besides the fixed oil above referred to, and other principles of less importance, mustard contains certain ingredients, which, though inert when applied to the surface dry, or mixed with alcohol, undergo a mutual reaction with water, which renders the powder extremely irritant. These principles are not exactly the same in the two varieties of mustard. The following is an epitome of our present knowledge on this subject, which, however, requires further investigation.

In both black and white mustard there is a peculiar principle, denominated myrosyne, which acts the part of a ferment, and in character is very analogous, though not identical with the emulsin of sweet and bitter almonds. in the black variety there is, besides this principle, another, supposed to possess acid properties, and called myronic acid, which is thought to be combined with potassa, forming myronate of potassa. in the white variety, instead of this principle, there is another of peculiar properties, called sulphosinapisin, from the circumstance that it contains sulphur, as also does myronic acid. Now, when water is added to mustard, a reaction takes place between it and the peculiar principles of the two varieties, through the instrumentality of the myrosyne, by which new products result, quite different in their properties from those pre-existing in the seeds. The myronic acid of the black mustard forms, by this reaction, a volatile oil, which may be obtained by distillation, is extremely volatile, and imparts to the powder great pungency of smell, and a strongly pungent and acrid taste. The sulphosinapisin of the white mustard, by the same reaction, forms also a very acrid and pungent substance, which, however, is not volatile; and, therefore, though little less acrid to the taste, or irritant to the surface than the volatile oil of the black variety, does not impart the same pungency of smell to the powder.

From what has been said it follows, that, to develop the activity of mustard, the presence of water is necessary. Myrosyne, through the instrumentality of which the changes are effected, is coagulated and rendered inert by heat, alcohol, and the acids. Hence, the rubefacient property of mustard is not evolved by alcohol; and the application of heat, or admixture of acids, interferes with its activity. The odour emitted, on the addition of water to the powdered black mustard, is very striking; while no such effect is produced by strong alcohol. The reader who may wish further knowledge on this subject, will find a more detailed account of the chemistry of mustard in the U. S. Dispensatory (12th ed., pp. 780-1-2). The important practical inference from all this is, that, in order to obtain the greatest effect from mustard, as a rubefacient, it is necessary to mix it with water; and that heat, alcohol, and the acids, so far from increasing its power, enfeeble, if they do not render it inert.

Effects on the Skin. The effects of mustard, taken internally, have been sufficiently considered (II. 475, 499, 647). When applied to the surface, in the form of a cataplasm, it is one of the most powerful rubefacients, and practically perhaps the most useful of the class. Though capable of producing the most violent effects, it may by dilution be reduced to any desirable degree of mildness, and may consequently be graduated to almost any condition, calling for the temporary use of these remedies. if applied undiluted, it generally produces a feeling of warmth within ten or fifteen minutes, which gradually deepens to a burning pain, and, at the end of from thirty to forty minutes, becomes so violent as to be almost insupportable. Few patients will bear a cataplasm of pure mustard longer than three-quarters of an hour. The surface, on its removal, is found intensely red and somewhat elevated; and the burning pain continues, with gradual mitigation, for a considerable time, occasionally for hours; generally leaving, when it disappears, some degree of soreness behind. Desquamation of the cuticle after a time takes place, a new cuticle being formed without any secretion of liquid. By shortening the period of application, or diluting the mustard, any amount of rubefacient effect can be obtained, from the intensity just described, down to a scarcely perceptible and very fugitive redness.