278 



of cyanogen upon cyanamide might have yielded the compound 



(CN)H 2 N + (CN) 2 = C 3 H 2 N 4 , 



which, by acids, should have been converted into parabanic acid, 

 C 3 H 2 N 4 +3H 2 + 2HC1 = C 3 H 2 N 2 O 3 + 2H 4 N Cl. 



Cyanamide is, in fact, capable of fixing the elements of cyanogen, 

 being converted into a yellowish amorphous powder, which, when 

 heated with acids, furnishes a beautiful crystalline compound, diffi- 

 cultly soluble in water, and deposited from the boiling solution on 

 cooling in long slender needles. 



Cyanamide being very prone to molecular changes, when submitted 

 to the action of chemical agents, I have not yet been able to procure 

 a sufficient quantity of these crystals for a more minute examination. 

 In their properties they entirely differ from parabanic acid. 



XII. " Notes of Researches on the Poly- Ammonias." No. XIV. 

 Diagnosis of Diamines. By A. W. HOFMANN, LL.D., 

 F.R.S. Received May 24, 1861. 



In former parts of this inquiry I have had repeated opportunities 

 of discussing the features of distinction between the monamines and 

 diamines. I have shown that the study of the genesis and of the 

 transformations of an ammonia, and the observation of its boiling- 

 point supply most valuable data for the elucidation of this question ; 

 and that the most reliable inferences may be drawn from the deter- 

 mination of its vapour-density. 



In continuing my experiments upon this subject, I have been led 

 to the discovery of a class of salts, the formation of which decides the 

 question in an equally satisfactory manner. 



Let us imagine an ammonia of uncertain origin, the composition 

 and degree of substitution of which has been experimentally deter- 

 mined. It is obvious that as long as the boiling-point, and more 

 particularly the vapour-density, remain unascertained, it is left 

 doubtful whether the molecular value of the new compound is 



represented by 



R ] (R 2 )" 



H L N or H 2 J- N . 



Hj H 2 



