2 Pring & Fairlie, Hydrocarbons and their Stability. 



determination to be made in any reasonable time, and the 

 decomposition of methane at this temperature proceeds 

 still more slowly, though both these reactions can be 

 accelerated by using a catalyst such as platinum or 

 palladium in contact with the carbon. 



Again, no substance can be used for the reaction 

 vessel, which can be heated to above 1200 , and remain 

 quite impervious to gases, so it is not practicable to have 

 the whole of the enclosure at a uniform temperature, as 

 was attempted by Berthelot.* 



The apparatus by means of which the synthesis of the 

 various h\'drocarbons has been observed b\- the present 

 authors consisted in heating a rod of purified carbon 

 uniformly by means of an electric current. 



The rod was mounted in water-cooled electrodes 

 supported in a tubular glass flask, which was filled with 

 pure hydrogen. The carbon itself was thus the only part 

 of the apparatus to be heated. As methane is exothermic, 

 the quantity in equilibrium with carbon and hydrogen is 

 lower the higher the temperature, so that the amount of 

 this hydrocarbon finally formed will correspond to the 

 equilibrium at the temperature of the heated carbon. By 

 this means then an accurate measure could be obtained of 

 the equilibrium value if there is no disturbance by the 

 presence of any other hydrocarbon. 



The equilibrium with the endothermic compounds, 

 acetylene and ethylene, could not be determined in this 

 form of apparatus, as the values diminish at lower 

 temperatures, and decomposition of the gas would take 

 place in passing to the cooler parts of the apparatus. 



Using platinum as a catalyst, it was found that 0-55 

 per cent, of methane was finally given at 1200". and 030 

 per cent, at 1500°. 



* Ann. Chitn. Pkys. {1905) |viii.], 6, 183. 



