Thermodynamic Properties of Air. 29 



use for that purpose the relation 



c 9 =c p + 18-714 ^LL , 



i. e. to obtain the values of the specific heat at constant 

 volume by means of those of c p already calculated. To 

 simplify the calculation, put pv = rj; then it follows that 



~dP _ P . 



therefore 



c p -c„=18'7U 



~dp 



3/> 



The values of <^ will be found easily by the preceding 



section ; those of ^— can be obtained by graphical differen- 

 ce 



tiation on the diagram of compressibility (Part L, pi. ii.). 



The necessary data and the results of this calculation are 



collected in the following tables : — 







<9=-- 



L40, t~- 



= 133. 







V. 



p- 



c P . 



dp 



dn 



-dp 



c v . 



c 



1 

 io 



4-668 



0-305 



00392 



-00055 



0219 



1-39 



1 

 20 



8-87 



0-385 



0083 



-00055 



0-278 



1-38 



1 

 30*" 



12-65 



0-464 



0-1363 



-0-0055 



0322 



1-44 



1 

 50 



19-29 



0624 



0-239 



-0-0059 



0-433 



1-44 



1 



60 



22-08 



703 



0306 



-0-0066 



0-457 



1-54 



1 



80 



2674 



0859 



0-435 



-0-0078 



0-501 



1-70 



1 



30-35 



1021 



0-539 



-00104 



0-535 



1-91 



loo 















