THERMAL PROPERTIES OF CARBONIC ACID AT LOW TEMPERATURES. 



81 



Five horizontal lines were divided in this way and the I lines drawn through them. 

 The values of I for the liquid, given in Table IX., were found by interpolation. The 

 values of I given for the gas were obtained l>y adding the corresponding values of L 

 to the values of I for the liquid. 



Approximate constant-pressure lines in the dry area may be drawn, if the specific 

 heat is assumed to be constant. They are logarithmic curves given by the equation 



d<f> _ a_ 

 d6~ 6' 



where a is the specific heat of the gas at constant pressure. 



40 . . . 



20 



<J 

 o 



-IO 



-20 



-30 



-40 



\ 



Comparison of 

 .tropy-tempera.tu.re diagrams. 

 Dotted lines are plotted from 



Mollier's figures. 



-1O -08 -oe -o* -ot O 



ot -O4 e -oe -1O 

 Entropy . 



Fig. 13. 



16 -1C -2O -ti -U 



These curves are drawn in the diagram as straight lines, since for the short length 

 shown the curvature is imperceptible. The values of o- are taken from the curve, 



VOL. CCXIII. A. M 



