1895.] 



The Action of Heat upon Etliylene. 



401 



The fact that when only 1 in. of tube is heated, there is a fairly 

 constant deficit of the kind to be expected at the temperature em- 

 ployed, and that when a greater length of heated tube is used with a 

 5 c.c. rate of flow, the deficit becomes a substantial surplus, at once 

 suggests that methane is amongst the secondary as well as the 

 primary products of decomposition. 



In the dilution experiments, the larger contraction in the volume 

 noticeable points to the diluting of the products favouring polymeri- 

 sation. 



It seems probable from the figures that when dilution reaches above 

 50 per cent., not only is decomposition of the methane retarded, but 

 formation as a secondary product commences. 



Ever since water gas has been in use it has been well known that 

 it contained traces of methane and acetylene, under conditions which 

 render it impossible for them to have been formed from hydrocarbons 

 remaining in the incandescent fuel, and the probabilities are that 

 they have been produced, the acetylene by direct combination of 

 carbon and hydrogen, and the methane by its partial decomposition. 



The formation of ethylene from nascent hydrogen and acetylene 

 takes place at such temperatures as those employed, and the amount 

 so formed and again broken up by the radiant heat is purely a func- 

 tion of mass ; so that I conceive from these experiments, the ethylene 

 at once to a great extent decomposes under the influence of 

 sufficiently high radiant heat according to the equation : 



and that the acetylene partly decomposes, the nascent hydrogen again 

 uniting with more acetylene to reproduce ethylene, whilst other por- 

 tions of the acetylene polymerise to benzene and other more complex 

 hydrocarbons, and that, if the flow of this mixture be continued 

 through a heated chamber, the action continues, the amount of ethyl- 

 ene regenerated becoming less and less, until it ceases to exist as a 

 product of the decomposition. 



VOL, Lvir. 2 G 



