588 



long beautiful needles. The solution of this iodide is no longer pre- 

 cipitated by ammonia, but yields with oxide of silver a powerfully 

 alkaline solution, exhibiting all the characters of the completely sub- 

 stituted ammonium- and diammonium-bases discovered by Professor 

 Hofmann. The solution of this dimethyl-tetrethylated base, which 

 contains 



TT M Q _^12 AA 8 V^2 -"5/4 W AX 3>'2 ^2 1 f) 

 ^U 36 1>I 2 U 2 - HJ U2 ' 



is not further acted upon by either iodide of ethyl or methyl. 

 With acids it forms a series of salts which are remarkable for the 

 beauty with which they crystallize. The platinum-salt is almost in- 

 soluble in water, but soluble with difficulty in concentrated boiling 

 hydrochloric acid, crystallizing from this solution on cooling in 

 beautiful needles. This salt contains 



C 22 H 34 N 2 Cl 2 ,2PtCl 2 . 



The above experiments appear to establish the molecular construction 

 of benzidine in a satisfactory manner. This base is obviously a 

 primary diamine, in which the molecular group C 12 H 8 , whatever its 

 nature may be, functions as a diatomic radical. A glance at the 

 subjoined Table exhibits the construction of benzidine and of the 

 several compounds which I have described. 



Diamines. 



(C 12 H 8 )" 

 Benzidine H 2 J- N 2 , 



Diethylated ben- 

 zidine . 



(C ia H 8 )"l 



taid k, 



(H 2 ) 2 J 

 ' n " 



Tetrethylated (C 12 

 benzidine .... (C, 



Iodides of Diammoniums. 



Primary [(C 12 H 8 ) H 6 N 2 ]"I 2> 



Secondary .... [(C J2 H 8 ) H 4 (C, H 5 ) 2 NJ I 2> 



Tertiary [(C 12 H,)" H 2 (C^XNJ'I,, 



Quartary [(C 12 H.) (CH 3 ) 2 (G, H 5 ) 4 NJ I 2 . 



The experiments described in this note were performed in Pro- 

 fessor Hofmann' s laboratory. 



