EQUATION AND THE NATURE OF COHESION. 47 



28. n-llexane. C G B 14 . 



(a). a = 2.03 BTJ'Jl. 03 -- P C F C 2 . 1\. = 507.8; P c = 2.2.510 

 mm. ll(j.; d c = . 2344; V c = 366.9. . . a = 26.50 X 10' 2 



{b)\ a = 6.5 P C F C 2 a = 26.26 X 10 ,a 



(c). a=(i!M 2 l^di't f =102.8 Jf=8C... a = 27.90X10 12 



(,/). fl = r'7^7; .r„. C" = 1.752 a = 27.15 X 10 2 



(e). a = 3 MN^T c Cjd . C= 2.11 by Dütoit and 



Friedrich. c? = . 9071 a = 25.79 X 10'" 



£7=2.27 according to Morgan and Chazal corrected by Lohn- 

 St:ein. This would give for a the value 27.75 X 10' -. 



The mean of all these values is 26.91 X 10 12 . The value of a 

 computed from the molecular weight and valences with 38 valences 

 is 25.90 X 10' 2 . This is about 4% lower than the mean. The value 

 computed by van Laar is 24.92 X 10 12 which is about 9 °/ 

 below the mean, and is certainly too low. 



29. Di-isopropyl. C'^H 14 . 



(a). a = 2.03PT r F r /l.0S — P r F l 2 . 7 T ,.= 500.35; P c =23.360 

 mm. Hg. ■ d c = 0.241 1 ; F c = 350.7 . . a = 25.30 X N> 12 



(/,). a = 6.5 P C V 2 a = 25.70 X I0 ia 



(cj. a = p.' J/-'/ 3 //,- ; ; . M= 86. // = 97.53 ... a = 25.96 X 10 12 



(d). a = C RTJ\.. C = 1.725 a = 25.61 X 10 12 



(e). Surface tension not found. 



These values are very consistent. The mean is 25.64 X 10' 2 which 

 is very close to the value 25.90 X 10' 2 calculated from the molecular 

 weight and valences. The mean of the values of a for œ-hexane 

 and di-isopropyl is 26.27 which is only about 1.4 / o higher than 

 the computation from the gravitation and valences. Van Laar 

 computes the same value as for hexane, namely 24.92 which is 

 only about 3 °/ lower than the mean value for di-isopropyl. 



30. CJdor-benzène. C.BLCl. 



b O 



(a), a = 2.03 BT C F C /1.03 - P C F C 2 . T c = 032.2 ; P,. == 33.926; 



d c = . 3 6 5 4 ; V r = 3 7 . 8 . M = 1 1 2 . 4 5 a = 27.62 X 10 ' 2 



(/,). a = 6.5 P c F t a = 27.84 X I0' 2 



(c). a = //4/ 2 /3 d?'<}. fJt! = 81.42 a = 28.10 X I0' 2 



(d). a = CRT,F r . C' = 1.714 a = 27.74 X 10 12 



(e) . a = 3 sv 213 MN il3 T^j{d — D) (T c — Tf\ A t 



52.2° Walden and Swinne give for sv* 13 



the value 631.93. 1\. — T = 307.0°; 



D is neglected. d= 1.0713 a = 27.26 X 10 12 



