202 Finite Volume of Molecules and Equation of State. 



K = 3*424, for xenon * K = 3*605. We need not consider the 



Q 



van-der-Waals value . 3 , for it fails entirely. 

 o 



The most serious drawback to Dieterici's equation is, 



according to Prof. Lewis (vide Lewis's Physical Chemistry, 



vol. ii. p. 117) that it makes b or the limiting volume 



= ~- 3 while the limiting volume, obtained by the extra- 

 polation of Cailletet-Mathias mean density line to the tempe- 

 rature = 0° K is about -r- c . The value of b obtained in 



V c 4 



this paper, viz., — ^ therefore agrees better with this value- 



It is yet premature to predict what influence this investi- 

 gation will have on the speculations concerning the vari- 

 ability of the volume of molecules with temperature. A 

 more detailed investigation dwelling upon this point, and 

 the application of the formula (4) to Amagat's (pv, p) 

 curves,, will be communicated shortly. Meanwhile we point 



_ a 

 out that the factor e ^xou has been introduced into the 



expression for s p 9 only as a provisional measure, though it 

 is considered that this step, though not quite exact, is one in 

 the right direction. In the next paper an attempt will be 

 made to introduce energy into probability calculations. 



Sir T. N. Palit Laboratory of Science, 

 Calcutta. 



Note added in proof . — On consulting the literature on the' 

 subject, we noticed that in several papers in the Amsterdam 

 Proceedings {vide vol. xv. p. 240 et seq.), Dr. Keesom 

 of Leyden had also made attempts to deduce the equation 

 of state from Boltzmann's entropy principle. But, in the 

 expression (2) for W, he introduces, before differentiation, 



an approximation in which terms up to second order in - are 



retained only. In this way, he arrives at the van der Waals' 

 form v — b for the influence of finite molecular volumes. In 

 obtaining our present equation of state (4), no such approxi- 

 mation has been made. (M. N. Shaha and S. N. Basu.) 



* Paterson, Cripps, Wh-vtlaw-Gray, Proc. Roy. Soc. Lond. A. lxxxvL 

 p. 579 (1912). 



