168 



Journal of the Mitchell Society. 



[Dec. 



[IV] 



P = 



ing every conclusion we have hitherto drawn relative to the 



SP 

 value of -K7p at this point. 



Combining- equation 16 with 12 and remembering- that at 

 the critical temperature V = v we have, 



124860 T __ 10471 / 

 ?nV VVs 



Applying this equation to isopentane, we have, V = 4.266, 

 m = 72.1, T = 460.8, // = 105.4, and the pressure thus cal- 

 culated is 27600 ag-ainst 25000 observed, an agreement well 

 within the limit of experimental error, since the pressure is 

 found as a difference. 



A more g-eneral equation is obtained by combining- equa- 

 tions 7 and 8 to obtain 



[18] 



P = 



31414 ( 9.1522 



V- 



Tlog 



d — 



d ; 



}. 



an equation which, owing to the divergence shown by Cromp- 

 ton's theory is not applicable to low pressures. 



We have purposely omitted all reference to those equations 

 connecting- the latent heat with the specific heat of liquid or 

 vapor, as it is our purpose at a future time to point out a 

 relation existing between the specific heat of solid, liquid, 

 and vapor, and to discuss such equations in that connection. 



A FURTHER APPLICATION OF CROMPTON'S THEORY TO VERIFY 

 THE PROPOSED LAW OF MOLECULAR ATTRACTION. 



Following a line of argument already advanced 1 , if we con- 

 sider any gas it is reduced to the liquid state by pressure and 

 by the molecular attraction. In nature the two, pressure and 

 attraction, act jointly and continuously. But theoretically 

 we can separate their action, since mechanically all forces are 

 independent of each other. Legitimately then, we can con- 

 sider a liquid at its critical temperature as reduced to that 



1 Jour. Phys. Chem., April, 1902, p. 223. 



