40 Transactions. 



results, for rarely did one degree of variation occur in the 

 course of an experiment. All temperatures were measured 

 with a platinum resistance thermometer. 



The method adopted was to pass the gas through a capil- 

 lary containing the asbestos, the tube being kept at the 

 requisite temperature by the lead bath. The gas was then 

 allowed to take up a constant temperature, and carbon-dioxide 

 sought for by absorption in potassium -hydrate. 



With regard to testing the oxidation of the metal, the 

 method was altered. Oxygen was slowly passed through the 

 capillary ; the apparatus was then swept out with nitrogen, 

 and methane passed through. It was anticipated that, if an 

 oxidation had taken place, traces of carbon-dioxide would be 

 found. 



The conclusions arrived at mav be summarised as follows : — 



1. The temperature of oxidation of pure methane and 

 oxygen is about 520°-546° C, very close to that observed 

 recently by Richardt. 



2. An increase in the rate at which the gas is sent over 

 appears to cause a decided increase in the temperature of 

 combustion. Since every particle of gas was in contact with 

 the heated asbestos for over a second, this increase cannot be 

 attributed to insufficient heating. A decrease in the rate 

 caused very little alteration in the temperature of oxidation, 

 showing that increased facilities for combination in no way 

 help to overcome the natural retardation observed by Mallard 

 and Le Chatelier, and by Richardt. 



3. A variation in the proportions of the gases causes a 

 decided change in the temperature of oxidation, for a well- 

 defined minimum is obtained when the gases are present in 

 proper volumes for total commistion. 1 vol. CH 4 : 2 of 2 

 gave as temperature of combustion 520°-546° C. ; 1 vol. CH 4 : 

 1 of 0. 2 gave as temperature of combustion 565°-585° G. ; 1 vol. 

 CH 4 : 3 of 2 gave as temperature of combustion 620° C. The 

 curve connecting volumes and temperatures is appended. 



4. The addition of hydrogen, even in large quantities, does 

 not cause the methane to burn at a lower temperature. 

 Consequently the usual method of fractional combustion of 

 hydrogen in gas-analyses should give reliable results, pro- 

 vided the temperature does not rise above 500° C. It is in- 

 teresting to note that the action of the catalyser does not 

 appear to be aided by the intense heat generated by the com- 

 bustion of the hydrogen. Perhaps the most reasonable ex- 

 planation of this is that the palladium, which is catalytically 

 active not only towards a methane-and-oxygen mixture but 

 also towards a hydrogen-and-oxygen mixture, acts in the 

 presence of these three gases in such a way as to confine its 

 energy as a catalyser to that direction in which it is the 



