232 PROCEEDINGS OF THE AMERICAN ACADEMY. 



The other portion of their product (which had not been distilled) was 

 decomposed by means of hydrochloric acid on the water bath ; the 

 chlorides obtained by evaporating the hydrochloric acid solution were 

 converted into chlorplatinates and crystallized fractionally, when they 

 obtained two end fractions in which the platinum was determined with 

 the following results : — 



(C2H5NH3)2PtCl6 requires 39.24 * per cent of platinum. 



In considering these results of Fileti and R. Schiff, it is to be observed 

 that the diethylcyanamide was not purified, and that no very sharp cri- 

 terion of purity was given (Wallach states that these substances are 

 decomposed by distillation under ordinary pressure, so that the boiling 

 point is not of much value in this respect), further that their analyses of 

 the platinum salts did not give numbers very near to those calculated. 

 It seemed to us, therefore, worth while to try similar experiments with, 

 if possible, a crystalline disubstituted cyanamide, which could therefore 

 be obtained in a state of undoubted purity, and also with one which 

 would yield amines more easily separated than ammonia and diethyl- 

 amine. We selected for this purpose the diparabrombenzylcyanamide, 

 since the parabrorabenzyl compounds show a great tendency to crystallize, 

 and the diparabrombenzylamine, if formed, could be recognized by its 

 melting point, 50° (dibenzylamine is a liquid), while the parabromben- 

 zylamine, if that were the product, gives a carbonate with a definite 

 melting point, and both these amines could be separated without difficulty 

 from ammonia. 



The diparabrombenzylcyanamide proved to be a well crystallized solid, 

 melting at 133°. On decomposition with dilute sulphuric acid it gave 

 diparabrombenzylamine, ammonia, and carbonic dioxide by the following 

 reaction : — 



(C6H4BrCH2)2NCN + 2HoO = (C6H4BrCH2)2NH + NH3 + COo . 



Our results, therefore, confirm those of Fileti and R. Schiff, and leave 

 no doubt that the dialkyl derivatives from argentic cyanamide are cyan- 

 amides and not carbodiimides. If they are formed by direct replace- 

 ment of the silver in argentic cyanamide by the alkyl radicals, the same 



* These are the numbers given by Fileti and R. Schiflf. Tliey would be some- 

 what altered by using modern atomic weights. 



