( SOB ) 



The signilicatioii of ƒ we üiid l)y equating the vohime of the 

 molecules to zero; it appears then, that /= i? J', so that the equation 

 of state becomes 



p available volume ^n^ 



free 



—-rr ^I'ea of surface of impact 

 total ^ 



identical with (9). 



Equation (10) shows us at the same time, what is the physical 

 significance of the qnanlillcs used by van ukr Wa.\t,s Jr. in his proof 

 with the aid of the \irial. For he integrates the pressure i^ over the 

 volume V, the pressui-e P' over the volume /^ so that the equation 

 of state becomes : 



X free ^ , , X 



^ / 7~rT surface distance spheres \ 



a \ f total 'I 



'' + v^)\ " - " 1^- ; — ; \=RT .. (11) 



\ TTT ^^'^^^ surface of impact / 



which is, moreover, at once seen, when we read the cited jiaper 

 attentively. (Specially p. 492). 



Though it is not clear to me, why we must integrate here o\'er 

 half the Aolume of the distance spheres, I must acknowledge that 

 the result — to which we can also get Avithout the j)roof in question 

 by simply putting the results (6) and (9) identical — is correct. For 

 calculations formula (11) wdiich agrees closest with the original form 

 of VAN DEH Waals, may be of use. I had hoi)ed that I should be 

 able to use the formula oittained in this way h)r removing the 

 remaining discrepancios I)elween experiment and theory, at least 



T ,lp 



luirtiallv, speciallv the great dilFerence in the \'alue oï 



As 3'et these efforts ha\e not met with \\\q desired success, and it 



is obvious, that this will not l)e possil)Ie, before we know e.g. the 



numerator of (11) much more accurately than we do no\v. It is clear 



that ihis numerator in virtue of its j)liysical signification, can never 



become zero for \'oluiues largei- than the minimum volume; now we 



11 b 

 know this numerator mdy in the shape 1 , an expression 



which becomes zero for very much larger xoluines, nay ex'en for 



the ordinary liquid volumes. For these volumes therefore the appli- 



11 // 

 cation of the correction 1 will be injurious, instead of advant- 



8 r 



ageous. Not before the mathematical form of two of the three quan- 



