

1904] Mills — Molecular Attraction. 85 



where m — 0.434294. Substituting- this value of ^7=^- in 

 equation 4, we get: 



[7] L = 5.3019 K j (blogaat + clog/3/Py, 



and using values for P and J already adopted (p. 82), we have 

 finally: 



[8] L = 0.0 3 168775 P.Az^.T (b log- aa* + c log- 00* ), cals.; or 



P. Az\T 

 [9] L = ^^i A cals., if, 



[10] A = 168.775 (b log aa« + c log 009. 



In this form the calculation of the latent heat is not only 

 theoretically correct, but is much shortened in comparison 

 with the usually adopted methods. The values for A were 

 obtained from the constants for Biot's formula given in the 

 original papers, and the equations thus derived for each sub- 

 stance are given below under that substance. 



(g) All calculations in this paper were checked and every 

 effort was made to make the calculations as accurate as the 

 data from which they were derived. 



Ether. See Table 2. Data from Phil. Trans. 1887A, p. 57; 

 except density of liquid at 10°, 20° and 30° C, where the 

 values are from Oudemans. Molecular weight used 74.08. 



Di-isopropyl. See Table 3. Data from Jour. Chem. Soc. 

 1900, p. 1126, except vapor pressure at 216° and 225° C (cal- 

 culated from Biot's formula); and vapor density at 0° C which 

 is theoretical. Molecular weight used, 86.112. For calcula- 

 tion of the latent heat, 



A = antilog (1.572552 — 0.00020800/) 



+ antilog (0.1268648 — 0.00466932/), 

 where /=/° C+ 10. 



Di-isobutyl See Table 4. Data from Jour. Chem. Soc. 



