70 CRUCIFER^. 



tures, in contact with water and Myrosin, the latter of which is a con- 

 stituent of white mustard as well as of brown (p. 66). The liquid 

 becomes turbid, the first of the above-named substances separates 

 (together with coagulated albumin) as an oily liquid, not soluble in 

 water, but dissolving in alcohol or ether. This Sidphocyanate of 

 Acrinyl is the rubefacient and vesicating principle of white mustard. 

 It does not pre-exist, as shown by Will, in the seed, and cannot be 

 obtained by distillation. By treating it with a salt of silver. Will 

 obtained crystals of cyanide of acrinyl, C^H'NO : by warming it (or 

 sinalbin itself, or an alcoholic extract of the seed) with caustic potash, 

 sulphocyanide of potassium is produced. The presence of the latter 

 may be indicated by adding a drop of perchloride of iron, when a blood- 

 red coloration will be produced.^ 



Sulphate of Sinapine imparts to the emulsion of white mustard, in 

 which it is formed, an acid reaction. Sinapine is itself an alkaloid, 

 which has not yet been isolated, as it is very liable to change. Thus its 

 solution on addition of a trace of alkali immediately assumes a bright 

 yellow colour indicating decomposition, and a similar colour is produced 

 in an aqueous extract of the seed. 



The above statements show, that the chemical properties of sinalbin 

 and its derivatives correspond closely with those of sinigrin (p. 66) and 

 the substances which make their appearance in an emulsion of black 

 mustard. 



The other constituents of white mustard seed are nearly the same 

 as those of black. The fat oil appears to yield in addition to the acids 

 mentioned at p. 67, Benic or Behenic Acid, C^H^O\ White mustard 

 is said to be richer than black in myrosin, so that, as explained in the 

 previous article, the pungency of the latter may be often increased by 

 an addition of white mustard. By burning white mustard dried at 

 100° C, with soda-lime, we obtained from 420 to 480 per cent, of 

 nitrogen, answering to about 28 per cent, of protein substances.^ The 

 fixed oil of the seed amounts to 22 per cent. The mucilage as yielded 

 by the epidermis is precipitable by alcohol, neutral lead acetate, or 

 ferric chloride, and is soluble in water after drying. 



Erucin and Sinapic Acid, mentioned by Simon (1838)^ as peculiar 

 constituents of white mustard, are altogether doubtful, yet may deserve 

 further investigation. The sinapic acid of Von Babo and Hirschbrunn* 

 (1852) is a product of the decomposition of sinapine. 



Uses — White Mustard seed reduced to powder and made into a 

 paste with cold water act as a powerful stimulant when applied to the 

 skin, notwithstanding that such paste is entirely wanting in essential 

 oil. But for sinapisms they are actually used only in the form of the 

 Flour of Mustard which is prepared for the table and which contains 

 also Brown Mustard seed. 



1 The red compound thus formed with ^ Experiments performed by Mr. Weppen 



sulphocyanide is readily soluble in ether, in my laboratory, 1869. — F. A. F. 

 yet in the case of white mustard we find it ^Gmelin, Chemistry, xiv. (1860) 521 and 



not to be so. 529. 



■'Ibid. 521. 



