499 



Analysis led to the formula 



The dilute solution of this chloride is not precipitated by dichlo- 

 ride of platinum, nor can the double salt of the two chlorides be 

 obtained by evaporating the mixed solutions, which, just as Gott- 

 lieb observed it, is readily decomposed with separation of metallic 

 platinum. I had, however, no difficulty in preparing a platinum salt, 

 crystallizing in splendid long brown-red prisms, by adding the dichlo- 

 ride of platinum to the concentrated solution of the hydrochlorate. 



The platinum determination led to the formula 



r ( 



L H { 



(C.CH.CNO,)])'' 



~, PtCL. 



These experiments prove that, even under the most favourable cir- 

 cumstances, nitrophenylenediamine combines only with 1 equiv. of 

 acid, while the ethylene-derivatives are decidedly diacid. The dimi- 

 nution of saturating power in nitrophenylenediamine, at the first 

 glance, seems somewhat anomalous, but the anomaly disappears if 

 the constitution of the body be more accurately examined. It can- 

 not be doubted that the diminution of the saturating power is due to 

 the substitution which has taken place in the radical of the diamine. 

 I have pointed out at an earlier period *, that the basic character of 

 phenylamine is considerably modified by successive changes intro- 

 duced into the phenyl-radical by substitution. Chlorphenylamine, 

 though less basic than the normal compound, still forms well-defined 

 salts with the acids ; the salts of dichlorphenylamine, on the other 

 hand, are so feeble, that, under the influence of boiling water, they 

 are split into their constituents ; in trichlorphenylamine, lastly, all 

 basic characters have entirely disappeared. Again, on examining the 

 nitro-substitutes of phenylamine, we find that even nitrophenylamine 

 is an exceedingly weak base, whilst dinitrophenylamine is perfectly 

 indifferent. What wonder, then, that a molecular system, to which 

 in the normal condition we attribute a diacid character, should, by 

 the insertion of special radicals, be reduced to monoacidity ? The 

 normal phenylenediamine, which remains to be discovered, will doubt- 

 * Mem. of Chem. Soc. vol. ii. p. 298. 



