160 Journal of the Mitchell Society. [Dec, 



T -p 



stant of equation, Q/ r^= = constant, were due to the 



u f d — f D 



8P 

 Biot formula from which the v-r was obtained. 



1 



For di-isobutyl, normal heptane, and normal octane, 

 Crompton's equation does not confirm the results of equation 

 4 when the constants that we have adopted are used, but 

 points instead to lower values for these constants, and we 

 would here call attention to the fact that this indication 

 meets further confirmation (Cf results equations 20, 21 and 25). 



For chlor-benzene, brom-benzene, and iodo-benzene, Cromp- 

 ton's theory points to higher constants. This evidence can- 

 not be entirely trusted since the highest measurements for 

 these substances are considerably below the critical tempera- 

 ture. 



For stannic chloride, Crompton's equations confirms in a 

 measure the constant adopted. This was a surprise, and sug- 

 gsets the possibility of an error in the Biot formula used. 



For the alcohols and acetic acid, Crompton's equation con- 

 firms the belief that in these substances the molecular attrac- 

 tion changes at high temperatures. 



To consider the question as to why Crompton's theory does 

 not give correct results at low temperatures we would call 

 attention to the fact that Mr. Crompton could as well have 

 taken the law of the vapor pressure as PV — P X V X and have 

 obtained, 



[10] L = 2P 1 V I log e ^f. 



Here V x is the volume of the liquid and P x is the theoretical 

 pressure of the liquid. In calculating this theoretical pressure it 

 will be seen that the equation cancels back to its original 



form, 2 RT log e yr-. We have here called attention to the 



transposition only that the equation might be recognized as 

 identically the same equation with which we have to deal in 

 the Joule-Thomson effect of the free expansion of gases. The 



