[ 525 ] 



XLII. On the Variation of Specific Heats with Temperature 

 and Density. By John P." D Alton, M.A., Carnegie 

 Research Scholar *. 



A. According to van der Waals*s Equation. 



IN order to determine the effect on the specific heats of 

 deviations from the gas-laws, van der Waals's equation, 

 shall be used. This gives the relation | 



cv-a rt 



R 



RT-^ (»-&)' 



or 



j using reduced magnitudes, 

 f! — f! 



±dc 



R 4^o) 3 -(3oj-1) 2 - 



Fisr. i. 



-C, 



5 





I 



\ 









! 























\ 











i< 



3 







I 





\ 











<! 



> 







\ 





\ 









5 



_0 



> 







\ 





\ 









4 





\ 





1 





\ 











^ 



<fc 





\ 









\° 















\ 







\ orv 







4 









\ 





















\ 





N.CO 



















\ 





\o 





\ 

















V® 







\ 







3 



















s. 





j 



/ 



















2 







N^ 



'CT- 















! 



1/ 



0=/O 















——______ 



















e=oo 











| 















( 







| 





From this equation the accompanying set of isothermal 

 — p 3 a> i-curves were derived (fig. 1). (The portions 



of the curves corresponding to the unstable parts of the 



* Communicated by Prof. J. P. Kuenen, Ph.D. 

 t Van der Waals, Contin. i. p. 131 (1899). 



