Uses—Black mustard is employed in the form of poultice as a powerful external stimulant; but it is rarely used in its pure state, as the Flour of Mustard prepared for the table, which contains in addition white mustard, answers perfectly well and is at hand in every house.[292]
The essential oil of mustard dissolved in spirit of wine is occasionally prescribed as a liniment.
Substitute—Brassica juncea Hook. f. et Th. (Sinapis juncea L.) is extensively cultivated throughout India (where B. nigra is rarely grown), Central Africa, and generally in warm countries where it replaces B. nigra and is applied to the same uses. Its seeds constitute a portion of the mustard of Europe, as we may infer from the fact that British India exported in the year 1871-72, of “Mustard seed” 1418 tons, of which 790 tons were shipped to the United Kingdom, and 516 tons to France.[293] B. juncea is largely grown in the south of Russia and in the steppes north-east of the Caspian where it appears to flourish particularly well in the saline soil. At Sarepta in the Government of Saratov, an establishment has existed since the beginning of the present century where this sort of mustard is prepared for use to the extent of 800 tons of seed annually. The seeds make a fine yellow powder employed both for culinary and medicinal purposes. By pressure they yield more than 20 per cent. of fixed oil which is used in Russia like the best olive oil. The seeds closely resemble those of B. nigra and afford when distilled the same essential oil; it is largely made at Kiew.
SEMEN SINAPIS ALBÆ.
White Mustard; F. Moutarde blanche ou Anglaise; G. Weisser Senf.
Botanical Origin—Brassica alba Hook. f. et Th. (Sinapis alba L.) This plant appears to belong to the more southern countries of Europe and Western Asia. According to Chinese authors[294] it was introduced into China from the latter region. Its cultivation in England is of recent introduction, but is rapidly extending.[295] The plant is not uncommon as a weed on cultivated land.
History—White mustard was used in former times indiscriminately with the brown. In the materia medica of the London Pharmacopœia of 1720 the two sorts are separately prescribed. The important chemical distinction between them was first made known in 1831 by Boutron-Charlard and Robiquet.[296]
Production—White mustard is grown as an agricultural crop in Essex and Cambridgeshire.
Description—Brassica alba differs from B. nigra in having the pods bristly and spreading. They are about an inch long, half the length being occupied by a flat veiny beak. Each pod contains 4 to 6 yellowish seeds about ¹/₁₂ of an inch in diameter and ⅒ of a grain in weight. The brittle, nearly transparent and colourless testa encloses an embryo of a bright pure yellow and of the same structure as that of black mustard. The surface of the testa is likewise pitted in a reticulate manner, but so finely that it appears smooth except under a high magnifying power.
When triturated with water the seeds form a yellowish emulsion of very pungent taste, but it is inodorous and does not under any circumstances yield a volatile oil. The powdered seeds made into a paste with cold water act as a highly stimulating cataplasm. The entire seeds yield to cold water an abundance of mucilage.