



Hhe Gas-equat 



ion. 











For Air. 













III. 











Temp. -inters 



T al unknown. 



Press 



Lire 1-4 



atm. 





*. 



P. 





A. 



Pi 



(Case 



1) 00036706 



700 mm. Hg. 



case 1 

 case 2 



0-27 



030 



( .. 



2) 36944 



2525 



case 2 

 case 3 



025 



029 



( „ 



3) 36964 



2620 



case 1 

 case 3 



095 



096 



875 



In cases I. and III. the convergence of (8) is evident. 

 From equations (5) and (7) we evidently can determine 

 a and b in terms of known and measurable quantities. 

 We have : — 



Oo 



M\ 



and we get 



k*0 



1 =?(a 



0o 2 + # 2 



6- 



-»> 



6-. 



b= - 



o 0(F0„-l)-(^-P«)(0 o 2 +r) 



y. 



(9) 



(<V~0 o + 3 ).P j 



According to van der Waals those expressions ought not 

 to vary. If we regard a and b as constant we can take the 

 case of 0° C. when 6 = O , an d get 



b=/c t *e -i-2(i-v ')j' • ' • ^ 



where r ' is the volume of one gram-molecule of the gas 

 at 0° and 1 atmosphere, and a and b consequently referred 

 to one gram-molecule of gas. 

 From (10) we get 



a — b = l—>v '. 



That a—h should be expressed in a similar way can 

 a priori be regarded as probable, because the influence of a 

 tends to diminish the volume v Q ' and the influence of b to 



expa 



nd it. 



