498 



(C 6 [H a (N0 2 )])" 



Nitrophenylenediamine 



J 8 (N0 2 )])"-l 

 H 2 >N 2 . 



H, J 



(C,[H 8 (N0 2 )])'n 



New acid N'" ?N 2 . 



H J 



(C,[H 3 (N0 2 )])" 

 Silver-salt N'" 



Ag 



If the admissibility of this interpretation be confirmed by further 

 experiments, the reaction discovered by Griess furnishes a new and 

 valuable method of recognizing the degree of substitution in the 

 derivatives of ammonia, 



The new acid differs in many respects from the substances pro- 

 duced from other nitrogenous compounds. As a class, these sub- 

 stances are remarkable for the facility with which they are changed 

 under the influence of acids, and more especially of bases. The new 

 acid exhibits remarkable stability; it may be boiled with either 

 potassa or hydrochloric acid without undergoing the slightest change. 

 Even a current of nitrous acid passed into the aqueous or alcoholic 

 solution is without the least effect. The latter experiment appeared 

 of some interest ; for if the action of nitrous acid, in a second phase 

 of the process, had assumed the form so frequently observed by Piria 

 and others, it might have led to the formation of the diatomic nitro- 

 phenylene-alcohol, according to the equation 



(C. [H, (N0 2 )])" 1 (C. [H 3 (N0 2 )]) 1 



H 2 JN 2 +2HN0 2 =2H 2 + N 1+ H 2 / l 



It deserves to be noticed that nitrophenylenediamine, although 

 derived from two molecules of ammonia, is nevertheless a decidedly 

 monacid base. Gottlieb's analyses of the chloride, nitrate, and sul- 

 phate left scarcely a doubt on this point. However, as some of the 

 natural bases, quinine for instance, are capable of combining with 

 either one or two molecules of acid, I thought it of sufficient interest 

 to confirm Gottlieb's observations by some additional experiments. 

 The crystals deposited on cooling from a solution of nitrophenylene- 

 diamine in concentrated hydrochloric acid, were washed with the 

 same liquid and dried in vacuo over lime. 



