﻿110 



Mr. D. Tvrer on the 



Vapour 



constant volume and constant pressure respectively, and 

 ( '■_ is the specific heat of the vapour at constant volume 



^Vapour x x 



at the same temperature. 



A tahle of values of C — C,. T ., has already been 



/'Liquid l Liquid J 



given. It is only necessary to obtain values of C< p uid ~ CL 



and to compare the two. 



In the following tables are given these values of 

 C —Gv . The values of the specific heats of the 



^Liquid vapour x 



vapours at constant volume have been obtained usually by 

 extrapolation from experimental results for higher tem- 

 peratures. The values for the specific heats of the liquids 

 at constant pressure have been obtained as a rule by extra- 

 polation of values at lower temperatures. Where several 

 results by different observers were available, mean values of 

 concordant figures have been taken. Every effort has been 

 made to obtain as great an accuracy as possible in the com- 

 parison of the two sets of values. 



Substance. 



T 

 (° 0.). 



k. 



Vapour 



I 



I Authority. 



1 



! 



; Liquid 



Authority. 



'^Liquid 



-Cv 



\ apour 



^-C'Wa 



Chloroform. 



o 

 50 



0-1245 



Wiedemann 



0-2373 



Regnault. 



0-1128 



0560 



1 



GO 



0-1258 



&. Begnault. 



0-2383 



» 



01125 



0-0557 



Ether.. 



40 



3775 



Wiedemann. 



05763 





0-1988 

 0-277 



0*159 (approrO 

 0-1325 





20 



0-276 



Jaeger. 



0-5527 



" 





35 



0-288 



iNejreneuf. 



0-570 



„ 



0-282 



145 



Carbon bi- 



40 



0-112 



Regnault. 



0-242 





0-130 





sulphide. 



50 



0-114 



,, 



0-243 





0-129 









15 



0-1 10 



Capstick. 



0-236 





0126 



98 





33 



127 



Beyne. 



0-240 



» 



0113 



°'°4at25° 

 0-09 



Benzene 



40 



0-232 } 

 0-213 I 

 0-255 J 





0-433 ) 



Pickering 



0*202 



0-130 





50 

 60 



Wiedemann. 



0-437 I 

 0-446 J 



& Mills 

 & McRae. 



0194 

 0-191 



0132 

 0-140 



On account of the lack of experimental data the above 

 table is very incomplete. The figures given in columns 3 

 and 5 were not obtained directly by the authorities quoted, 

 but have been calculated from their results. A compa- 

 rison of^ the last two columns shows clearly that the true 

 value of [Gp — Cv) for liquids is considerably smaller than 

 that calculated by aid of the value of C„ for "the vapours of 

 the liquids. 



