214 Royal Society : — 



on the walls of the glass balloon as a grey film, and the other 

 contents consisted of an inflammable gas. Mercuric ethyle appears 

 therefore to be resolved at this temperature into ethyle gas and 

 mercury. 



Another experiment was more successful, and gave the number 

 9*97 for the vapour-density. 



The equivalent weight of mercuric ethyle is 129, which, being 



129 

 divided by the former figures, gives ^ = 12-94. If the constituents 



of this radical be condensed into two volumes of vapour, the more 

 accurate number 14-86 should have been obtained. 



The theoretical density of mercuric ethyle, thus calculated, is equal 



to 1^=8-68*. 



This portion of the subject would be incomplete unless a few 

 words were added on the behaviour of zinc-ethyle towards mercurous 

 chloride. 



It has been mentioned, that all attempts to reduce iodide of mer- 

 curous methyle to the form of a radical containing one equivalent of 

 methyle and two equivalents of mercury have hitherto failed. 



Reasoning a priori, we should not expect to find a departure in 

 the present case, neither does such appear. Mercurous chloride 

 reacts with vigour on zinc-ethyle, but metallic mercury is formed 

 simultaneously with chloride of zinc and mercuric ethyle. 



The decompositions of mercurous and mercuric chlorides or 

 iodides, are thus shown : — 



C, H, Zn + Hg, C1=C, H, Hg-fZn Cl + Hg, 



and 



C,H,Zn+HgCl=C,H,Hg+ZnCl. 



Having succeeded, by these simple means, in effecting a replacement 

 in zinc-ethyle through the ordinai-y metallic chlorides, there remained 

 yet one point untouched, viz. the behaviour of various organo- 

 metallic salts, under similar treatment. 

 First in order was tried 



The Action of Zinc-ethyle on Iodide of Mercurous Ethyle. 

 Carbonic acid, or ordinary coal-gas, was slowly passed through the 

 neck of a retort ; and when the atmospheric air was displaced, about two 

 ounces of zinc-ethyle, nearly free from ether, and wholly so from iodide 

 of ethyle, was introduced. Iodide of mercurous ethyle was then added, 

 by degrees, through the tubulure, and the whole mixed by agitation. 

 The zinc-ethyle at first dissolves the iodid^, but subsequently a cake 

 of iodide of zinc is formed. Distillation was then commenced, the 



* Here it is fitting to mention an eiror that has crept into the calculation of the 

 vapour-density of mercuric methyle as it appears printed in the ' Proceedings of the 

 Royal Society.' A false figure in the denominator of one of the fractions, causes 

 the experimental density to appear as 14-86, whereas the true experimental density 

 observed was 8-29. The theoretical density of mercuric methyle, calculated for two 



, 115 _„, 

 volumes, equals iir^= /•95. 



