Manchester Memoirs, Vol. xlvi. (1901), No. 5, 



5 /O 



Rate of Cooling of the ProducLs of Combustion. 



The quantity of heat dissipated per unit of cooling 

 surface increases with the temperature interval and with 

 the pressure of the gas, but not at the same rate as the 

 latter. The heat developed, on the other hand, is simply 

 proportional to the pressure. 



By increasing the pressure from one to 70 atmos- 

 pheres, we increase the heat generated in a given 

 volume 70 times, but we do not increase the rate at which 

 heat is dissipated in anything like the same ratio. The 

 increase of efficiency, which, in the case of gas 

 engines, has always been connected with the use of high 

 initial pressures, is mainly due to this cause. It is also, 

 to some extent, due to the higher temperature obtained, 

 and to the smaller dimensions of the moving parts. 



/T 



