EQUATION AND THE NATURE OE COHESION. I 1 



the best which can be done until the critical density is redeter- 

 mined. The value calculated from gravitation, taking sulphur as 

 hexavaleut, so that there are 1(5 valences in the molecule, is 

 13.40 X I® 12 - This is i n entire agreement with the mean of 13.33. 

 T may say that sulphur, so far as J have been able to compute it, 

 is always hexavaleut except in S0 2 . Vax Laar's value for CS 2 - is 

 12.14 X 10 12 which is much lower than the true value. The value 

 from van der Waals' equation of 0.023 10 would be 11.40 which is 

 still lower. From the latent heat of expansion of liquids Lewis has 

 calculated 10.23 X 10 12 . I think there must be some error in this 

 calculation as usually Lewis' method makes a a little high. 



■&• 



1G. Me tl/// 1 acetate. CgZ/gOg. 



(a), a = 2.03 BT B Fjl.0& — P C Y 2 . P c = 35,21 2 mm.Hg; T = 



506.7 ; d r = . 3252; F e = 227.0 a= 15.80 X N> 12 



(b). a = 6.5 P,.F 2 • a = 16.47 X 10 12 



(c). a = fJL'M 2 4.185X1 ° 7 / : > ^ 2/3 - l J ' = 1 OS . 8 . a = 16.73 X 10' 2 



(d). a = ("HT r r r . C'= 1.784 a = 17.11 X 10" 



(e). a = 3 Mi\ iri T c C/d . (7=2.11 (Morgan and 

 Schwartz corrected according to Lohn- 

 stein) M =74. d calculated in usual 



way = 1.277 a= 15.74 X 10" 



These values show considerable variation , but the mean is 

 16.54 X Ï0' 2 which is the most probable value which can be given. 

 With M= 74 and 22 valences, a is calculated by my formula to 

 be 16.28 X 10 ' 2 which is in excellent agreement with the mean. 

 Van Laar gives 15.77 which is fairly close to my value. The usual 

 approximate value given is .03200 or 14.07 X 10 12 when calcu- 

 lated into the other units. In this case, as in one or two others 

 preceding, van Laar's correction is in the right direction but not 

 quite large enough. 



17. Ethyl formate. C s ff e 2 . 



(a). a = 2.03BT c F c /im — P c F 2 . T c = 508.2; P, = 35,535 

 mm.Hg. ■ d c = . 3232 ; V c = 228.96. . a = 16.60 X 10' 2 



(b). a = 6.0 P,.F, 2 . a = 16.14 X 10' 2 



(c). a = fi'M 2 /'à d^, // = 1 07. 1 4 a = 17.38 X N>' 2 



(rf). a = C'BT C F C . C' = 1.747 a = 16J)1 X 1<»' 2 



(<?). « = 3 MN^T c Cjd . C =2.01; J/ = 74; 



d = Sd c = 1.25.8 a = 15.27 X 10 12 



The mean of these values is 16.46 X IO 12 . The value calculated 



