262 



formed by the union of one molecule of the latter with two molecules 

 of pyridine, 



C 2 H 4 Br a +2C 6 H 5 N=C 12 H M N 3 Br 2 . 



The constitution of pyridine itself is but imperfectly made out. All 

 we know is that this substance is a tertiary monamine ; the nature of 

 the radicals which replace the hydrogen is as yet uncertain. Pyridine, 

 in accordance with our present knowledge, may be represented by 



the expression 



(C 5 H 5 )'"N, 



and the molecular construction of the new bromide may be expressed 

 by the formula 



The composition of the bromide is confirmed by the analysis of the 

 chloride and platinum-salt. 



Dichloride. Treatment of the dibromide with chloride of silver 

 yields the corresponding dichloride as a crystalline and extremely 

 soluble substance, containing 



r (r TT Y" Ni " 



C 12 H 14 N 2 C1 2 = (C,HJ" '>,,, C1 2 . 



Platinum-salt. The solution of the above salt yields with di- 

 chloride of platinum a pale yellow and apparently amorphous pre- 

 cipitate, insoluble in water and alcohol, and but slightly soluble in 

 boiling concentrated hydrochloric acid, from which, on cooling, it 

 almost entirely separates in small brilliant yellow plates, which were 

 found to contain 



r /P TT Y" ~\r~i " 



C 12 H u N 2 Pt, Cl e = [(C, H 4 )'' $ >, *] Cl a> 2 Pt C1 2 . 



The solution of the dibromide, when mixed with freshly precipitated 

 oxide of silver in the cold, furnishes a transparent colourless and 

 powerfully alkaline liquid which contains the corresponding base, 

 viz. the hydrate of ethylene-dipyridyl-diammonium, 



C H NO - 245 a 2 



L/ 12 J1 16 J>I 2 U 2 ~ H 



The existence of this compound in the solution is readily proved by 

 saturating with hydrochloric acid, and adding dichloride of platinum, 

 when the pale yellow platinum-salt previously mentioned is preci- 

 pitated. This salt was submitted to analysis. 



