Vaporization of Liquids. 



303 



Several other substances tried give a similar diminution of 

 b and constancy of a. I have only come across two so far 

 which have failed to do so, propyl alcohol and carbon tetra- 

 chloride. In the first of these a shows a gradual and 

 continuous decrease, and in the second an increase, for which 

 it is difficult to see any reason. It may be as well to give 

 the data for these substances : — 



Pr 



opyl Alcohol, C 3 H 7 OH. Mol. wt. 59'86. 



t 



V. 



v'. 



U. 



b. 



a. 



80 



1-330 



9580 



161-5 



1-120 



4-12 xlO 9 



100 



1-365 



443 



1521 



1130 



4-09 



120 



1-406 



225 



141-0 



1-132 



393 



140 



1-455 



124 



130-4 



1-137 



3-81 



160 



1-515 



72-3 



1171 



1132 



3-60 



180 



1-591 



445 



104-8 



1-139 



3-52 



200 



1-689 



28-3 



91-4 



1-120 



3-30 



220 



1-823 



18-0 



75-7 



1-095 



3-12 



Carbon Tetrachloride, CC1 4 . Mol. wt. 153*45. 



t. 



v. 



v'. 



u. 



b. 



a. 



60 



0-6594 



298-2 



43-0 



0-4765 



4-29 XlO 8 



80 



•6773 



163-5 



41-2 



•4760 



4-33 



100 



•6972 



975 



39-55 



•4757 



4-42 



120 



•7193 



61-2 



37-76 



•4749 



4-48 



140 



•7435 



403 



35-76 



•4720 



451 



160 



•7703 



27-4 



3350 



•4665 



4-53 



180 



•8019 



1905 



30-90 



•4565 



4-49 



200 



•8412 



13-48 



28-20 



•4505 



4-54 



220 



•8907 



9-62 



25-31 



•4460 



4-59 



240 



•9575 



6-83 



2202 



•4460 



4-72 



260 



10628 



4-66 



17-18 



•4370 



4-71 



The examples given in the previous Tables seem sufficient 

 to substantiate for the majority of liquids the validity of the 

 assumptions on which the equation for the heat of vaporiza- 

 tion is based. It is clear that, with the two exceptions 

 mentioned, the internal heat of vaporization of these liquids 

 will be accurately expressed by the equation 



L 7 = 



RT f 1 , v f -b J^ _b_\ 



JM 1-4343 io Sio^zy + v _£ - v '-b J ' * (Jj 



in which b, although not constant, has a value satisfying 



