130 Journal of Agricultural Research vol. xx, no. 2 



that in the presence of alcohol during maceration no bacterial fermen- 

 tation causing a loss of volatile oil takes place. 



A glycerin bath may be used to secure greater uniformitv in heating. 



The use of ground glass joints in the distilling apparatus has been rec- 

 ommended in literature in order to avoid possible errors caused by the 

 use of rubber stoppers. 



To insure complete absorption of the volatile oil, the tip of the con- 

 denser should always dip below the surface of the liquid in the receiving 

 flask. It is advantageous to have the condenser terminate in a tube of 

 small bore. A second receiver, containing ammonia and silver solution, 

 may be used in case the completion of the distillation is in doubt. 



According to Kuntze {25), the mixture obtained after distillation may 

 also be heated directly without standing to ioo° C. for an hour, using 

 a reflux condenser or a long glass tube as a condenser. Possible further 

 formation of an urethane compound (allyl urethane in the case of allyl 

 mustard oil) can thus be avoided. 



YIELD OF VOLATILE OIL 



Examination by the method just given of a number of samples of seeds 

 obtained from Chinese colza showed that the content of crotonyl isothio- 

 cyanate varies from about 0.4 to 0.6 per cent. Various attempts were 

 made to increase the yield of volatile oil by addition of different chemicals 

 before maceration. Table III shows the results of these experiments. 



Table III. — Effects of chemicals added before maceration upon the yield of volatile oil 



. 



Volatile oil 

 Substance added to 5 gin. of sample. (crotonyl iso- 



thiocyanate). 



Potassium hydroxid, 0.2 gm 



Potassium fluorid, 0.2 gm 



Tartaric acid, 0.2 gm 



Tartaric acid, 5 gm 



Tartaric acid, reflux 2 hours, 5 gm 



Sinapis alba, as a source of myrosin, 5 gm 

 Alcohol, 20 cc 



No chemical 



Per cent 

 o 



The results shown in Table III may be summarized as follows: Five 

 gm. of tartaric acid probably destroyed the enzym and no appreciable 

 yield of volatile oil was obtained; 0.2 gm. of tartaric acid slightly retarded 



