303 



precipitation, volatilization, crystallization, and perhaps other actions 

 occur, simply because one of the substances is thus removed from 

 the field of action, and the equilibrium that was first established is 

 thus destroyed. 



VII. That consequently there is a fundamental error in all 

 attempts to determine the relative strength of affinity by precipita- 

 tion, in all methods of quantitative analysis founded on the colour 

 of a solution in which colourless salts are also present, and in all 

 conclusions as to what substances exist in a solution, drawn from 

 such empirical rules as, that " the strongest acid combines with the 

 strongest base." 



March 15, 1855. 

 The LORD WROTTESLEY, President, in the Chair. 



The following communications were read : 



I. " Researches on Organo-metallic Bodies." By E. FRANK- 

 LAND, Ph.D., F.R.S., Professor of Chemistry in Owens 

 College, Manchester. Second Memoir. Zincethyl. Re- 

 ceived February 9, 1855. 



This compound, whose existence was mentioned in a previous 

 memoir*, is formed by the action of zinc upon iodide of ethyl, or a 

 mixture of iodide of ethyl and anhydrous ether, at a temperature ex- 

 ceeding 100 C. The materials are enclosed in a copper digester 

 capable of resisting great pressure. When purified by rectification 

 in an atmosphere of carbonic acid, zincethyl possesses the following 

 properties : At ordinary temperatures it is a colourless, transparent 

 and mobile liquid, refracting light strongly and possessing a peculiar 

 odour, rather pleasant than otherwise, and therefore differing greatly 

 from that of zincmethyl. Its specific gravity is 1*182 at 18 C. 

 Exposed to a cold of 22 C. it exhibits no tendency to become 



* Philosophical Transactions, 1852, p. 436. 



