SEMEN SINAPIS NIGR^E. 67 



nitrate. These chemists obtained sinigrin from the seeds in the pro- 

 portion of 0*5 per cent. ; Will and Korner got 5 to 06 per cent. The 

 extraction of the substance is therefore attended with great loss, as the 

 minimum yield of volatile oil, 0*42 per cent, indicates 236 of potassium 

 myronate. 



The aqueous solution of myrosin coagulates at 60° C. and then 

 becomes inactive : hence mustard seed which has been heated to 100° C 

 or has been roasted yields no volatile oil, nor does it yield any if 

 powdered and introduced at once into boiling water. The proportion of 

 myrosin in mustard has not been exactly determined. The total amount 

 of nitrogen in the seed is 29 per cent. (Hoffmann) which would corre- 

 spond to 18 per cent, of myrosin, supposing the proportion of nitrogen 

 in that substance to be the same as in albumin, and the total quantity 

 of nitrogen to belong to it. Sometimes black mustard contains so little 

 of it, that an emulsion of white mustard requires to be added in order 

 to develop all the volatile oil it is capable of yielding. 



An emulsion of mustard or a solution of pure sinigrin brought into 

 contact with myrosin, frequently deposits sulphur by decomposition of 

 the allyl sulphocyanide, hence crude oil of mustard sometimes contains 

 a considerable proportion (even half) of Allyl cyanide, C*ffN, distin- 

 guished by its lower sp. gr. (0839) and lower boiling point (118° C). 



The seeds, roots, or herbaceous part of many other plants of the order 

 Cfuciferce yield a volatile oil composed in part of mustard oil and in part 



of allyl sulphide C*H^°S = /-otts \ S, which latter is likewise obtainable 



from the bulbs of garlic. ^lany Cimciferce afford from their roots or seeds 

 chiefly or solely oil of mustard, and from their leaves oil of garlic. As 

 to other plants, the roots of Reseda lutea L. and B. luteola L. have 

 been shown by Volhard (1871) to afford oil of mustard.^ The strong 

 smell given off by the crushed seeds or roots of several Mimosea?, as for 

 instance, Alhizzia lophantha Benth, (Acacia Willd.) is perhaps due to 

 some allied compound. 



The artificial preparation of mustard oil was discovered in 1855 by 

 Zinin, and at the same time also by Berthelot and De Luca. It may be 

 obtained in decomposing bromide of allyl by means of sulphocyanate 

 of ammonium : — 



CWBt . SCN(NH') = NffBr . C^ffSCN. 



The liquid C'H'SCN, boiling at 161°, is sulphocyanate of aUyl ; if 

 it is gently warmed with a little alcoholic potash, and then acidulated, 

 the red coloration of ferric sulphocyanate is produced on addition of 

 perchloride of iron, but b}'^ submitting the sulphocyanate of allyl to 

 distillation it is at once transformed in the isosulphocyanate, i.e. in 

 mustard oil; the latter is not coloured by ferric salts, but it would 

 appear that in the cold emulsion of mustard, even at 0°, a little 

 sulphocyanate makes also its appearance. 



Mustard submitted to pressure affords about 23 per cent.^ of a mild- 

 tasting, inodorous, non-drj^ing oil, solidifying when cooled to - 17o° C, 

 and consisting of the glycerin compounds of stearic, oleic and Erucic 

 or Brassic Add. The last-named acid, C^H^O^ occurs also in the fixed 



' See also Radix Arrnoracice, p. 68. per cent, by means of boiling ether. — 



- 1 have obtained as much as 33*8 F. A. F. 



