MOTIVE POWER OF HEAT. 77 



The first column is the result of the direct 

 experiments of MM. Delaroche and Berard on the 

 specific heat of the gas under atmospheric pressure, 

 and the second column is composed of the numbers 

 of the first diminished by 0.300. 



The numbers of the first column and those of 

 the second are here referred to the same unit, to 

 the specific heat of atmospheric air under constant 

 pressure. 



The difference between each number of the first 

 column and the corresponding number of the sec- 

 ond being constant, the relation between these 

 numbers should be variable. Thus the relation 

 between the specific heat of gases under constant 

 pressure and the specific heat at constant volume, 

 varies in different gases. 



We have seen that air when it is subjected to a 

 sudden compression of T fg- of its volume rises one 

 degree in temperature. The other gases through 

 a similar compression should also rise in tempera- 

 ture. They should rise, but not equally, in inverse 

 ratio with their specific heat at constant volume. 

 In fact, the reduction of volume being by hypothe- 

 sis always the same, the quantity of heat due to 

 this reduction should likewise be always the same, 

 and consequently should produce an elevation of 

 temperature dependent only on the specific heat 



