Oct. 15, 1920 Mustard Seeds and Substitutes: I. Chinese Colza 131 



the reaction. Water alone gave results averaging about 0.6 per cent of 

 crotonyl isothiocyanate. The addition of 20 cc. of alcohol before the mac- 

 eration gave a higher percentage of volatile oil, the results reaching 

 almost 0.8 per cent. The formation of some allyl thiocyanate (34, p. 832) , 

 allyl cyanid (13), and carbon bisulphid during the fermentation process of 

 sinigrin has been observed in experiments where no alcohol was present. 

 Other products may be formed in its presence and must be expected, 

 especially in the authors' material, where no sinigrin but another gluco- 

 side is present. It has been pointed out by Kuntze (25) that side re- 

 actions can occur between allyl isothiocyanate and alcohol with the 

 formation of allyl thiourethane, and it may be presumed that a similar 

 reaction might take place between crotonyl isothiocyanate and alcohol, 

 which will lead to erroneous but probably lower results. At the present 

 time the data obtained are insufficient to ascribe the discrepancy to any 

 of these causes, nor is it yet known whether, in the presence of alcohol, 

 potassium hydrogen sulphate has also an injurious effect upon the for- 

 mation of mustard oil through rendering myrosin largely ineffective by 

 causing its coagulation (12). It is believed, however, that the maximum 

 yield was obtained, since, even in the presence of large amounts of en- 

 zym (white mustard added), higher yields were not secured. 



Shaking the maceration mixture at room temperature at intervals of 

 five minutes did not hasten the reaction sufficiently to give the total 

 amount of volatile oil in two hours. 



It has been pointed out by Forster (11) that in the preparation of rape- 

 seed cake the material is heated to about 70 C, and that when it is so 

 treated a high yield of oil is obtained. In these experiments the authors 

 were unable to verify Forster's results. In order to see whether there 

 was any difference in the yield of oil from the brown and yellow seeds, a 

 separation of the two was made, and determinations were made on the 

 separated samples with the results (calculated as crotonyl isothiocyanate) 

 shown in Table IV. 



Table IV. — Relative yield of volatile oil by brown and yellow seeds of Chinese colza. 



Treatment. 



Yield of volatile oil. 



Brown 

 seed. 



Yellow 

 seed. 



I Per cent. Per cent. 



2 hours' maceration at 37 C : o. 58 o. 55 



% hour's heating at 70 C, followed by 2 hours' maceration at ! 

 37° C I -44 ! -46 



It will be observed that in both the brown and yellow seed a lower 

 yield was obtained by the preliminary heating at 70 C. for % hour. 

 187932°— 20 4 



