PRESIDEKTIAL ADDRESS. 



381 



seeing the extreme rapidity of chemical interaction at high temperature as com- 

 pared with the rate at which the liberated heat can be communicated to and 

 uniformly distributed amongst the products by ordinary physical processes. 

 Attention may be drawn to the extreme slowness of the cooling in each case 

 after the attainment of maximum pressure ; this has also been observed by 



10 15 20 



TIME IN TJlj SECONDS 



After Firing 



25 



35 



Fig. G. 

 nrevious workers in other similar cases of gaseous explosions. This was 

 particularly marked in the case of the methane-air mixture, in which there was 

 hardly any appreciable cooling during an interval of 0"22 seconds after the 

 attainment of maximum pressure (in 008 sec), a circumstance which may be 

 due in part to the combustion taking place in well-defined chemical stages, and 



2 4 6 8 10 12 14 16. 18 20 25 30 35 49 



TIME INriuSE'CONDS 



After Firing 



Fia. 7. 



in part also to the operation of the exothermic secondary interaction between 

 carbon monoxide and steam during the cooling period. On the other hand, 

 the curve for the hydrogen-air mixture, where the combustion to steam is a 

 direct and comparatively simple transaction, suggests that the attaimnent of 

 maximum press,ure is succeeded by a period of gradual cooling uninfluenced by 

 chemical combination. 



Fuel Economy and the Proper Utilisation of Coal. 



Leaving now the scientific aspects of flame and combustion I wish to say a 

 few wo7'ds, as a technologist, upon the great national importance of a more 

 adequate scientific control of fuel consumption and the utilisation of coal 

 generally, with special reference to the situation created by this terrible and 

 ruinous European conflict. And my remarks will be addressed in part to my 

 chemical friends and colleagues, who are primarily interested in scientific 

 research and its industrial applications, and in part also to the commercial and 

 manufacturing community, which is chiefly interested in the financial results 

 of such scientific activity. 



Notwithstanding the fact that we are raising annually in the United 

 Kingdom (according to the official estimate for 1913) 287 million tons of coal, 



