679 



descent ; whilst, in a digester of thick copper, the different parts 

 of the vessel, owing to the high conductivity of the metal, are main- 

 tained at so uniform a temperature as to prevent any such circulation 

 of the liquid from taking place. 



The body just described being regarded as a mere mixture of zinc- 

 methyl and ether, incapable of being separated on account of the 

 close proximity of their boiling points, a more successful result was 

 anticipated by mixing the iodide of methyl with methylic ether in- 

 stead of vinic ether. As methylic ether boils at 21C., it was 

 thought that no such difficulty of separation could arise ; the bodies 

 employed would then, in fact, be exactly homologous with those so 

 successfully used in the preparation of pure zincethyl on the large 

 scale. It was found, however, that although a large quantity of 

 zincmethyl was produced, yet it was impossible to obtain it free from 

 methylic ether. A large portion of the product boiled at 43, a 

 small residuum only distilling between this temperature and 48 ; 

 both portions yielded, on analysis, results approaching the formula 



This result is, therefore, homologous with that obtained by the de- 

 composition of iodide of methyl mixed with vinic ether. 



In conclusion, the author states, that after an expenditure of many 

 pounds of iodide of methyl, he has been unable to obtain even the 

 smallest quantity of pure zincmethyl by the use of a copper digester, 

 although a much larger product of the ethereal solution is obtained 

 than in the corresponding preparation of zincethyl. 



March 10, 1859. 



Sir BENJAMIN C. BRODIE, Bart., President, in the Chair. 

 The following communications were read : 



I. Letter from JAMES P. MUIRHEAD, Esq., to Sir BENJAMIN 

 C. BRODIE, Bart., Pres. U.S., dated March 8, 1859, re- 

 lating to the Discovery of the Composition of Water. Com- 

 municated by Sir B. C. BRODIE. 



I have now, with your permission, to request you to lay before the 



