a Fluid passing through a Porous Plug. 893 



the same diagram are shown the inversion-points corre- 

 sponding to the equation of state which Dieterici has studied 

 in connexion with isopentane, viz.: — 



A 



or, in the reduced form, 



a(2/3-l) = 76*- 1 /(^l)]. 



The inversion-points corresponding to this equation are given 

 by tbe equation 



oy*=(10-yl)e* w -V>* 



It is obvious that there is remarkably close correspondence 

 between this and the experimental curve as regards their 

 general trend. A much closer fit can be obtained by modi- 

 fying the index of T in the exponential term, from 3/2 to 

 about 1'65; but in view of a modification to be proposed in a 

 later paper no stress will be laid on this fact. 



Carbon Dioxide. 



Carbon dioxide has been studied more fully by Amagat. 

 In the case of this gas we can obtain more definite curves 

 because of the greater number of experimental points. The 

 discrepancies calculated from Amagat's are given in Table III. 

 and are plotted in fig. 4 (pp. 894 & 895). 



The inversion-points obtained graphically from the curves 

 in fig. 4 are tabulated in Table IV. 



Table IV. — Inversion-points. C0 2 . 



Pressure. 



Inversion-Points. 



Atoms. 



Eeduced. 



Cent. 



Reduced. 



200 



250 

 400 

 500 

 600 

 700 

 800 

 850 



2-74 

 342 



5-48 

 6-85 

 8-22 

 959 

 10-96 

 11-64 





 5 



30 



45 



81 



135 



168 



198 



•90 



•92 

 1 nearly 

 106 

 1-17 

 135 

 1-44 

 1-55 



