Oct. is, 1920 



Mustard Seeds and Substitutes: I. Chinese Colza 129 



The volatile oil, readily volatile with the alcohol and water vapor, 

 reacts with ammonia and silver nitrate. In the case of allyl isothiocya- 

 nate (the true volatile mustard oil) mainly allyl thiourea (thiosinamin'* 



is first formed. 



^^NHC 3 H 5 



CSNC 3 H 5 + NH 3 = C=S 



^^NH 2 



Allyl isothiocyanate Thiosinamin 



This reacts slowly in the cold but is completely decomposed by heating 

 with silver nitrate, silver sulphid and cyanallylamid being formed. 



/^NHC 3 H 5 ^=NH 



C=S + Ag 2 = Ag 2 S + C 



\NH 2 ^NCA + H.O 



Thiosinamin Cyanallylamid 



Both are insoluble compounds. They are filtered off, and the silver not 

 used up in the reaction is determined volumetrically after Volhard. 

 1 atom of silver =K molecule of the volatile mustard oil. 



Other compounds may also be formed in small amounts during the 

 process (13, 25). 



NOTES ON METHOD 



Carles (7) suggests a smaller sample, 3 or 4 gm., in the case of par- 

 tially defatted samples or others yielding especially large amounts of 



volatile oil. 



The seed used for analysis should, if possible, be freshly ground, as the 

 powdered material loses its strength through hydrolysis, especially if not 

 kept thoroughly dry— at or below 7 per cent moisture, according to 

 Carles, not exceeding 2 per cent according to Boutron (5). 



Joergensen (20, p. 9) ana van Kampen (44. P- 6 3) in testing rape-seed 

 cakes recommended the addition of thymol; Brioux (6. p. 262-263) 

 recommended the addition of sodium fluorid to the rape-seed cake 

 when this is macerated and tested for the amount of volatile oil available. 

 They found that bacterial action would thus be largely inhibited in the 

 maceration and higher yields would be obtained. Brioux used 2 gm. of 

 sodium fluorid for 25 gm. of cake and 500 mils of water; van Kampen 

 used 10 mils of 1 per cent alcoholic thymol solution added to either 25 

 gm. of cake or .5 gm. of mustard seed and 300 mils of water. Joergensen 

 used a 1 per cent alcoholic solution of thymol and also in other experi- 

 ments mercuric chlorid, which, however, proved unsatisfactory. Raquet 

 (33) macerated the material in an aqueous alcoholic solution, adding 15 

 cc. of alcohol to the mixture before and 5 cc. after maceration, thus 

 obtaining seemingly higher yields. We (47) could verify his findings 

 but are still undecided whether this higher result is due to the formation 

 of other volatile reducing substances or, as Raauet claims, to the fact 



