6 THE UNIVERSITY SCIENCE BULLETIN. 



(80 gms.) were mixed in a wide-mouthed flask or tall beaker set in 

 ice. To this was added through a dropping funnel, in the course of 

 15 minutes, aniline (54 gms.), the whole being kept in agitation 

 with an automatic stirrer. 



The milky heterogeneous mixture, which first resulted, became 

 clear and homogeneous after the addition of the aniline. The am- 

 monium salt soon began to separate, and the mixture may become 

 so thick as to stop the stirrer. After standing an hour in the ice 

 bath the white ammonium salt was filtered, the mass washed with 

 a little alcohol and dried quickly on a porous plate or between 

 filter paper. The best yield of this salt was 86 per cent of the 

 theory, although this may vary decidedly, not only in the case of 

 aniline but also with the other aryl amines. This is due to the in- 

 complete separation of the ammonium salt rather than to its non- 

 formation. 



PROPERTIES OF THE AMMOXIUM PHENYL DITHIOCARB.\MATE. 



On standing, the salt slowly decomposed with the formation of 

 hydrogen sulphide, ammonia, carbon bisulphide, aniline and thio- 

 carbanilide. The decomposition was hastened when the salt was 

 boiled with water. The results here indicated that the two main 

 reactions were as follows, the first predominating: 



I. C6H5NHCSSNH4 =3 C,;H.5NH2 + CSo +NH3. 



II. CGH5NHCSSNH4 = C6H.5NCS + H2S + NH3. 



The mustard oil and aniline reacted to give thiocarbanilide, but 

 the yield is low, only about 20 per cent of the theoretical. 



With the ammonium salts of the p-chloro and p-bromophenyl 

 dithiocarbamates, where the amines and isothiocyanates are less 

 volatile, 55 to 60 per cent yields of the substituted thiocarbanilides 

 have been obtained by this method. 



DECOMPOSITION WITH ACIDS. 



When an aqueous solution of the salt is treated with hj^drochloric 

 acid the quantitative decomposition can be expressed as follows: 

 CcH.r,NHCSSNH4 + 2HC1 = CeHsNHsHCl + CS2 + NH4CI. 



Only traces of hydrogen sulphide and phenyl isothiocyanate are 

 formed. 



PREPARATION OF THE ARYL ISOTHIOCYANATES FROM THE 

 AMMONIUM SALTS. 



It is evident, then, that in order to produce the mustard oil, 

 RNCS, from the dithiocarbamate, RNHCSSNH,, some metallic salt 

 must be used which will form a stable sulphide and an ammonium 



