398 



Prof. V, B. Lewes. 



[Mar. 7, 



The first thing that strikes one is the enormous amount of decom- 

 position which takes place in the first inch of flow through the heated 

 tube, and the small effect which an increase in the length of the 

 heated surface has upon the further decomposition of the unsaturaied 

 hydrocarbons. 



This result might be caused by the methane and hydrogen formed 

 during the decomposition diluting the remaining ethylene, and so 

 rendering the decomposition more difficult ; it may also arise from 

 secondary actions taking place amongst the primary products, and 

 again forming ethylene, or it may be due to both these causes acting 

 together. 



In order to trace the effect of dilution, a series of experiments was 

 made in which ethylene, diluted with hydrogen, was passed through 

 6 inches of the same tube as was used in the previous experiments, 

 heated to the same temperature, and under precisely similar 

 conditions. 



The store holder of ethylene used for making the mixture contained 

 a gas which gave, on analysis, 



Ethylene 97'85 



Nitrogen 2'00 



Oxygen 0'15 



Table IV. Influence of Dilution in Checking Decomposition of 

 Ethylene. Length of tube heated, 6 inches. Rate of Flow, 10 c.c. 

 per minute. Temperature, 900 C. 



