22 PHYSICAL PROPERTIES AND COMPOSITION 



2. Introduction of Avogadros Law into the Characteristic 

 Equation. Constant Ratio between the Theoretical and 

 Critical volume 1 . 



Avogadro's law may most conveniently be introduced 

 into the characteristic equation by considering the molecu- 

 lar quantity of the substances in question. 



As in the limiting equation 



so in the characteristic equation 



PV-RT=F. 



R is the same for all bodies, and, in fact, the same as is 

 derived from the limiting equation. 



In the special characteristic equation adopted on p. 21, 

 since 



RT k _JT a TT2 a ^_TT3. 



a and 6 may be eliminated, and we get 



-^^* TT- z. 



or 



p.y t 



so that m - would have a constant value calculable from 



the laws of perfect gases. The following table gives the 

 results of the calculation : 



1 Chem. Centr.Bl. 1898, n. 1073. 



