06 



CRUCIFER^E. 



Constituents. The white mustard-seed is about one-twelfth of an inch 

 in diameter, almost globular, and of a yellowish color ; the black mustard- 

 seed one twenty-fifth of an inch in diameter, similar shape, blackish- 

 brown. Both yield a yellow powder, and both contain a considerable 

 percentage of fixed oil, which is bland, inodorous, and non-drying. Their 

 active irritating constituents are, however, though similar, far from identi- 

 cal, that of black mustard being 

 a volatile oil, while that of white 

 mustard cannot be obtained by 

 distillation. In neither case 

 does the acrid principle pre-ex- 

 ist in the seed, but is formed by 

 chemical reaction or fermen- 

 tation of existing principles- 

 when brought into contact with 

 each other in the presence of 

 water. The reaction differing* 

 so widely in results in the two 

 cases is thus explained : Black 

 mustard has as one of its constit- 

 uents a crystallizable substance 

 termed sinnigrin, which in the 

 presence of another constituent, 

 myrosin, an albuminous body, 

 and water, is decomposed, yield- 

 ing sugar, bisulphate of potas- 

 sium, and the volatile oil of 

 mustard. "White mustard, on 

 the other hand, though contain- 

 ing my rosin, has instead of sinnigrin a similar complex substance, termed 

 sinalbin, which is decomposed by myrosin in the presence of water, yield- 

 ing sugar, sulphate of sinapin, and sulphocyanate of acrinyl, the latter 

 being the acrid principle. 



Preparations. Of white mustard, none ; of black mustard, Charta 

 sinapis mustard paper. United States Pharmacopoeia. 



Medical Properties and Uses. These are too well known to require 

 more than mere mention. As an aid to digestion it is used in eveiy 

 household. As a prompt and efficient emetic it is almost always at hand 

 and the first to be employed in emergencies. As a rubefacient its sphere 

 of usefulness is practically unlimited. 



CAPSELLA. 



Capsella Bursa-pastoris Moench (Thlaspi Bursa-pastoris Linne). 

 Shepherd's Purse. 



FIG. 109. Brassica (sinapis) nigra. 



