1894.] The Action of Heat upon Ethylene. 101 



Analysis of Original Gas. 



Acetylene ..................... 94'28 



Oxygen ...................... 1'12 



Nitrogen ...................... 4'60 



The gas was passed through the platinum tube, 25 mm. of which was 

 heated to a temperature of 1000 C. 



Analysis of the Heated Gas. 



Acetylene .......... , ......... 25'95 



Other unsaturated hydrocarbons . 61 '97 



Saturated hydrocarbons ...'..... 3'21 



Carbon monoxide .............. 1*01 



Oxygen ....................... 0'38 



Hydrogen ..................... T50 



Nitrogen ...................... 5'98 



100-00 



Carbon and Oil formed per 100 c.c. of gas. 



Oil .................. 0-095 



Carbon ............... O'OIS 



Volume before heating. . . . 309 c.c. 

 after .... 174'2 c.c. 



showing that even under these conditions nearly three quarters of the 

 acetylene had undergone polymerisation, so that it is probable that in 

 the case of nascent acetylene, liberated from ethylene by the action 

 of heat, the condensation of the acetylene molecules to form benzene 

 .would be practically instantaneous, unless the temperature were 

 sufficiently high to cause dissociation to carbon and hydrogen at the 

 moment of liberation. 



The unsaturated hydrocarbons consisted chiefly of ethylene with 

 some benzene vapour, the ethylene probably having been formed by 

 the direct combination of acetylene and hydrogen, an interaction first 

 noticed by Berthelot, 



This also accounts for the small quantity of free hydrogen found on 

 analysis, which, having regard to the amount of carbon deposited, 

 should have been considerably higher. 



It will be noticed that with the rate of flow employed in the ex- 

 periments shown in Table I, the largest amount of acetylene found 

 in the gas after heating was 3'60, which occurs just at the tempera- 

 ture when carbon begins to deposit freely, and is therefore sufficiently 



VOL. LV. I 



