248 HISTORY OF CHEMISTRY. [LECTURE XII. 



nition of the bivalence of ethylene. Buff, in a preliminary com- 

 munication, several months prior to the first publication by 

 Wurtz on the subject of glycol, and in a paper laid before the 

 Royal Society one month prior to this publication, had endea- 

 voured to prove the diatomic nature of the hydrocarbons 

 C W H ; [C = 6]. 85 By treating ethylene chloride with potassium 

 thiocyanate, he had obtained a substance of the formula 

 C 4 H 4 Cy 2 S 4 , and this, on oxidation with nitric acid, yielded 

 a compound identical with Buckton and Hofmann's disul- 

 phetholic acid 80 for which Buff proposes the name ethylene 



H rsA 



sulphurous acid, representing it by the formula C 4 H 4 -[ 



H t$A- 



The formation of ethylene sulphocyanide is represented by the 

 equation : 



Cv^i ^ ( S * 



C 4 H 4 C1, + 2^ y \ S, = C 4 HA + 2 KC1. 



Cy (S, 



It appears from the whole paper that Buff had recognised 

 the diatomic nature of ethylene, and that, in this respect, he 

 can lay claim to priority over Wurtz. As regards the experi- 

 mental proof of this view, the two investigations scarcely admit 

 of comparison. The examination of the glycols by Wurtz is 

 amongst the most brilliant achievements of the period ; and by 

 its means the hypotheses as to the different valencies of the 

 radicals were provided with so broad a basis that nothing more 

 could be desired in this respect. Buff's experiments conformed 

 to the same theoretical conceptions, but they never could have 

 led to the conclusions which were drawn from the labours of 

 Wurtz. 



85 Annalen. 96, 302; Proc. Roy. Soc. 8, 188. 8G Annalen. IOO, 129. 



