Manchester Memoirs, Vol. hi. (1912), No. 6. 5 



the form of tubes, about 15 mms. external diameter. A 

 current of 500 am[)s. at 22 volts, would raise this to 1600 '^, 

 when the pressure was 150 atmospheres. 



Somewhat thinner rods were used for producing 

 higher temperatures and also when graphite was used, on 

 account of its higher conductivity. 



Hydrogen compressed in cyHnders and of about 995 

 per cent, purity was used for these experiments. When 

 working at lower pressures (below 30 atmospheres), the 

 furnace after evacuating was sometimes first filled with 

 pure methane at i atmosphere, in order to approach the 

 equilibrium from a quantity slightly in excess of this 

 value. 



Results. 



A large number of experiments were conducted at 

 various pressures between 20 and 200 atmospheres, and 

 with carbon in various forms and different degrees of 

 purity. 



It was found that the amount of methane obtained 

 was always higher with the amorphous form of carbon 

 than with graphite. As is well known, amorphous carbon 

 is unstable above 1200°, and for this reason gives with 

 methane a " false " or " metastable " equilibrium, which is 

 higher than the true value with graphite. 



On account of the great inertness of methane, de- 

 composition into the lower value only takes place very 

 slowl}'. 



It was found that with any particular modification 

 of carbon, a constant value within the limits of experi- 

 mental error was always obtained for the ratio 



at any given temperature in the range between 1200' and 



