EXPANSION OF GASES. 47 



where v is the volume of the gas dealt with at C, v its volume at the 

 temperature to be measured. 



Since 1 v m - V 



a -foo x ~^T 



we may put 



t= JLJ^.. x iQQ (i) 



If we choose a new zero - below 0., we may term this the gas 

 zero, and if we put 



e=t+- 



a 



~t + 

 then 



or putting for - 



a 







In the second case, if /? is ^ of the increase between 0* 0. and 



100 0. of a pressure which is 1 at 0., the temperature t, measured 

 from 0. is given by 



when p is the pressure at O 8 and p that at the temperature to be 

 measured. Evidently, as with the volume scale, we have 



xlQQ (3) 



and dating from a gas zero -^ below 0., on which 0. is - = 9 we 

 have 6=- P xlQQ 



PlOO - Po 



and 60 



_ 

 ~ 



. . 



There are therefore two different scales for each gas. Fortunately, 

 however, they are nearly coincident with each other, and nearly coinci- 

 dent, as certain experiments show, with the work scale. 



Taking t as the temperature dating from 0. on the work scale, 

 t v the temperature defined by (1) for air, t p the temperature defined by 



