/ooj] Mills — Molecular Attraction. 101 



— can also be viewed as the boiling- point and from this point 

 of view permits the deduction of equation 13. We hope 

 shortly to complete a paper applying- these ideas of molecular 

 attraction more fully to the boiling- point. 



We should also point out that by combining equation 11 

 with equation 14, we get, 



™ ^- = cV ( T l?- p 



where c is a constant. This equation can be solved so as to 

 give any one of the variables at the critical temperature in 

 terms of the others and the molecular weight. It is not feas- 

 ible now to further examine this equation, since the only cor- 



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 rect values for the -jr=- are obtained from equation 4 and this 



at once reduces the equation to the form of equation 16. 



Dr. Young has shown that the average constant of equa- 

 tion 17 is ^ . Since the theoretical critical pressure is 

 3.o27 



therefore 3.827 times the actual critical pressure it follows 

 from the gas law and equation 5 that at the critical tempera- 

 ture, 



This equation can be obtained directly from equation 18 

 but the constant is then unknown. 



SUMMARY. 



8 P 



1. It is shown that the -£-=- for a liquid (vapor) at the crit- 

 ical temperature is exactly twice what it would be for the 

 same substance as a gas occupying the critical volume. 



2. It is shown that Biot's formula for vapor pressure can- 

 not be made exactly to fit the true vapor pressure curve in the 

 immediate neighborhood of the critical temperature. When 



