SEMEN SINAPIS ALBzE. 69 



into China from the latter region. Its cultivation in England is of 

 recent introduction, but is rapidly extending.^ 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 Pha)'macopoem 

 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.^ 



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 ^ of an inch in diameter and yV 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 circum- 

 stances 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. 



Microscopic Structure — The epidermal cells of white mustard 

 afford a good illustration of a mucilage-yielding layer such as is met 

 with, under many variations, in the seeds of numerous plants. The 

 cuticle consists of large vaulted cells, exhibiting very regular hexagonal 

 outlines when cut across.* The inner layer of the epidermis is made up 

 of thin- walled cells, which when moistened swell and give off the muci- 

 lage. In the dry state or seen under oil, the outlines of the single cells 

 of this layer are not distinguishable. The tissue of the cotyledons is 

 loaded with drops of fatty oil and with granular albuminoid matter ; 

 starch which is present in the seed while young, is altogether absent 

 when the latter reaches maturity. 



Chemical Composition — White mustard deprived of fatty oil 

 yields to boiling alcohol colourless crystals of Sinalbin, an indifferent 

 substance, readily soluble in cold water, but sparingly in cold alcohol. 

 From the able investigations of Will (1870) it follows, that it is to be 

 regarded as composed of three bodies, namely : 



Sulphocyanate of Acrinyl C H^ N S O 



Sulphate of Sinapine e" H^ N S O" 



Sugar C H" O* 



so that the formula C" H" N' S' O'* 



represents according to Will the composition of sinalbin. It is actually 

 resolved into these three substances when placed at ordinary tempera- 



' Morton's C'ycloped, of Agriculture, ii. * An interesting object for the polarizing 



(1855) 440. microscope. 



- Journ. de Pharm. xvii. (1831) 279. 



