and its Derivatives. 243 



pyridine obtained by boiling the platinum salt of pyridine 

 with water. 



The reactions showing the formation of these substances 

 are : — 



(C6H7N.HCl)2PtCl4=C6H7N.PtCl, + HCl + C6H7N.HCl; 

 and 

 (Ce H, N . HC1)2 . PtOl^ = (Ce H7 N)2 PtCl^ + 2HC1. 



I was unable to obtain a compound analogous to Ander- 

 son's double salt of pyridine platinichloride and chloride of 

 platinopyridine. Supposing such a salt to exist^ it would 

 have the formula (0^ H7 N)2 HCl . PtCl^. We should then 

 have a series, the first three members of which differ from 

 each other by a progressive loss of hydrochloric acid, while 

 the last differs from the one immediately preceding by con- 

 taining a molecule of picoline less ; thus : — 



Picoline platinichloride (C^ H7 1^\ (HC1)2 PtCl^ 



{Double salt' (Cg H7N')2 HCl. PtCy? 



Platino-picoline chloride ...(Ce H7N)2 PtCl4 

 New compound (0^ H7 N) . PtCl^. 



That picoline is really evolved when the platino-picoline 

 chloride is transformed into the new salt, was proved by heat- 

 ing some of the former to a high temperature with water. 

 The dirty-yellow residue had a strong smell of picoline. 



The compound Cg H7 N . PtCl4 is soluble in hot caustic 

 alkalies ; and on cooling, brown flocks separate ; no picoline 

 is evolved even on continued boiling. (Og H7 N)2 PtCl4 also 

 dissolves in alkalies ; but on cooling, no deposit is formed, and 

 on addition of hydrochloric acid it is again precipitated as 

 before. It is very sparingly soluble in water ; it, as well as the 

 other compound, dissolves in hot picoline ; but the new com- 

 pound cannot be transformed into (C^ H7 N)2 PtCl4 by this 

 means ; no picoline adds itself on ; and when the picoline has 

 evaporated, the nevf compound is left as a gummy mass, 

 having the same composition as before. 



It was also found impossible to transform (Ce H7 N)2 PtCl4 

 or C6H7N.PtCl4 into (C^ H7 N)2 (HC1)2 PtCl4 by heating 

 with strong hydrochloric acid ; neither that acid nor nitric 

 acid has any action whatever on these compounds. 



The fact that they do not evolve picoline on treatment with 

 alkalies affords a very strong presumption that they do not 

 contain picoline as such ; but in what manner the platinum 

 is held in combination with the picoline is as yet inexplicable. 

 The compound Ce H7 N . PtCl4 has in so far an interest, that it 



R2 



