( 59.3 ) 



X = 0.63). The last value will probably be too large, as the curves 

 which, according to the afore-mentioned formulae, represent Txr and 

 Txpi as a function of x, and which for ,v =z almost touch each 

 other, do not do so for ,v = 1 and hence for larger .?; yield too 

 large values for 7\r — T^-pi . 



§ 10. Piu'lUj of the carbon dioMde. The values of « and /? found 

 and the increase of vapour pressure found at 25°. 55 C. with the 

 condensation: 0.07 atni. (comp. this Comm. IV, p. 567) allow us 

 to judge of the pui'ity of the carbon dioxide used. By means of 

 formula (9) of Comm. N". 79, Proc. April '02, which for the unities 

 used in this paper may be written 



if 



.4; = 1 -f 0.0036625 t 

 and 



[pal ] At 



we find, on the supposition that the admixture were oxygen, and 

 using for « and /? the values derived from the point K: 



X — 0.00027 . 

 § 11. Retrograde condensation. In the annexed plate we give 

 for the two mixtures investigated curves which represent vnq as 

 function of v according to the tables given in sections 2 and 3 

 (p. 579 IF.). The curves for the different temperatures are marked by the 

 lelters, I)}' which the corresponding isothermals have been indicated. 

 The numbers on tlie plate hold for the unity 0.00001. 



Physics. — " Isotherinah of nn.rtures (f o.ci/gen and carbon dio.Tide. 

 VI. Influence of (/ravitation on the pJienomena in the neigh- 

 bourhood of the plaitpoint for binarg mi.vt?(,re.s\ By W. H. 

 Keesom. Communication N". 88 (7''' |)art) from the Physical 

 Lal)oratory at Leiden, by Prof. Kamerlingh Onnes. 



(Communicated in tlie meeting of November 28, 1908). 



^1. In this Communication V, § 1 (P- 577) it was remarked 

 that the liquid meniscus at liie end of the condensation over a certain 

 range of temperatures appeared or disap|)ear('(l in llio tube. Kienen 

 (Comm. N°. 17, Zittingsversl. May 1895) was the first who explained 

 these phenomena by the theory of v.an dek Waals on the influence 

 of gravitation on the thermodynamic equilibrium in mixtures. (Contin. II 



