Thermodynamic Properties of Air. 299 



Then the above quantities are 



a(r, b)+w(S, b) 



expressed in normal volume-units. 



This same quantity of air which occupied after charging 

 the spaces 5, <r, a, and w, fills after discharge a space increased 

 by that capacity in the eudiometer (u is now the volume 

 occupied in it) in which the mercury has been replaced by 

 air, plus a small capacity (K = 42 c.mm.) laid open by un- 

 screwing the valve R (the valves were always opened by the 

 same number of turns of the spindle) . The whole quantity 

 of air supports now the common pressure B. Consequently 

 we have a new expression for the whole quantity of air, 

 namely: 



s(&, B) + c7(r, B)+K(t, B)+a(r, B)+w(3, B). 

 Equating we find the formula : 



A = M + m = u($, B)-w(S, b) + a{r, B-6) 



+ «(*', B)+[K + <r](T,B) .... (3) 



§ 9. Corrections. — We have now to calculate the small 

 amount m which is to be subtracted from A. Consider the 

 bulb No. 2, charged at temperature t= + 16° C. Suppose 

 the temperature of the corresponding space a were also 

 exactly + 16°, then obviously we could write 



w 2 =A, 



S 2 + 0~ 2 



Taking into consideration the small difference of temperature 

 between bulb ( + 16°) and stem (t 2 ) we write instead 



^A*^-^- (4) 



Simultaneously in the space cr 1? corresponding to bulb No. 1, 

 we have the following quantity of air : 



m 1 =A 2T — - 1 — , 



1 1 + yr s 2 + 02 



because in every case 



mi _ <r 1 



m 2 cr 2 * 



