66 



C 8 H 22 As N Pt 2 C1 G = [(C 2 HJ" (C * H ^]" C1 2 , 2 Pt C1 2 . 



Gold-salt. Yellow compound precipitated from the dichloride 

 obtained in the previous platinum- determination, on addition of tri- 

 chloride of gold, soluble in hydrochloric acid, deposited from this 

 solution in golden -yellow plates of the composition 



C s H 22 As N Au 2 CI 8 = [(C a HJ" (C 2 H 5 ) 3 H 3 As N]" C1 2 , 2 Au C1 3 . 



I have also made a few experiments on the action of dibromide of 

 ethylene upon trie thy Istibine. The reaction is slow, and requires 

 long-continued digestion at temperatures higher than that of boiling 

 water. The tubes invariably contained much gas ; and the product 

 of the reaction proved to be a complex mixture of several compounds, 

 many of them secondary, which in no way invited me to a more 

 minute examination of this process. I omit to quote the few pla- 

 tinum- and chlorine-determinations which were made, since they do 

 not admit of a simple interpretation. 



IV. "Contributions towards the History of the Monamines.'-' 

 No. IV. Separation of the Ethyl-Bases. By A. W. HOF- 

 MANN, LL.D., F.R.S. Received November 28, 1860. 



The preparation of the ethyl-bases by the action of ammonia upon 

 iodide of ethyl, presents a difficulty which greatly interferes with 

 the general application of this otherwise so convenient method. This 

 difficulty consists in the simultaneous formation of all the four ethyl- 

 bases. The equations 



2 H 5 I=[(C 2 H 5 ) H,N]I* 



(C 2 H 5 ) H 2 N + C 2 H 5 I=[(C 2 H 5 ) 2 H 2 NJI 

 2 H 5 I=[(C 2 H 5 ) 3 H N] I 



!(C 2 H 5 ) 2 H 



(C 2 H 3 ) 3 N + C 2 H 5 I=[(C 2 H 5 X N]I, 

 are an ideal representation of the four different phases through which 

 ammonia passes during its transformation into iodide of tetrethyl- 

 ammonium. In practice it is found impossible to carry out this 

 transformation in the several steps indicated by these equations. 

 The first substitution-product, generated as it is in the presence of 

 the agent of substitution, is immediately acted upon again, the second 



* 11 = 1; 0-16; C = 12, &c. 



