187°-5 C. (Orit. temp.) 

 v. 

 19-41 



and the Isotliermah of Vapours. 

 Table II. {continued). 



4688. Corrected /> = 2150. 

 p 3 . Fxp. p. 



453 



14-40 

 10-67 

 6-970 



3-872 



280° 0. 

 540-8 

 2630 

 125-70 

 52-34 

 24-43 

 11-40 

 5-810 

 5-172 



Pi- 

 14870 

 17970 

 20980 

 24240 

 25310 



d x + d 2 = - 

 p 2 . 

 14800 

 17840 

 20810 

 23910 

 24780 



14844 

 17920 



20900 

 24080 

 25110 



15190 

 18430 

 21480 

 24430 

 25030 



^+^=•3840. 



Corrected 6 = 2-49. 



872-2 



1766 



3579 



7881 



14310 



21810 



24860 



24880 



879-0 



1795 



3698 



8525 



16900 



31110 



49380 



53560 



879-0 



1795 



3698 



8531 



16930 



31210 



49680 



53930 



876 



1786 



3680 



8459 



16870 



31240 



49530 



53760 



Summary. 



1. Consideration o£ the internal pressure in fluids leads 

 to the relation that in a ideal 3> substances the ratio of the 

 occupied volume (co-volume) to the total volume of a liquid 

 is equal to the ratio of the unoccupied volume to the total 

 volume of its saturated vapour. The two phases, in equi- 

 librium with each other, are complementary in this respect. 

 The relation is nearly true for actual fluids. 



2. The equation 



i >=RT(rf 1 + rf 2 )(J)^ (1) 



is obtained for the saturation pressure of a vapour in terms 

 of the temperature and the densities of the two phases at 

 that temperature. This leads to an Equation of State 



*> - (2) 



P 



\ d 1 + d 2 )J \dj 



egarded 



3. It is shown that the quantity (d 1 -\-d 2 ) may be r 

 as a density factor which is a measure of the cohesive forces 

 per unit mass. 



4. On this hypothesis that for actual substances there is a 

 "density" proportional to the cohesive forces, nearly but 

 not exactly equal to {di~\-d 2 ), modified forms of equations 

 (1) and (2) are obtained. These equations express the 

 experimental facts with considerable accuracy for all 

 temperatures and pressures. 



Phil. Mag. S. 6. Vol. 41. N T o. 24:]. March 1021. 2 H 



