( 229 ) 



Tk.wers and Usher and Young 1 ), raustbe deferred to a later occasion. 

 However, some conclusions are obvious. 



As the temperature rises more slowly and the equilibrium in the 

 tube is better reached, we can get nearer to equality of density 

 of the vapour and liquid phases. We think we found a smaller dif- 

 ference in density in our measurements than any of the observers 

 before us 2 ;. 



We did so in the third experiment. The critical temperature was then 

 fixed between 30°.984 and 3(F.986 3 ). That at 30°.984 only a small dif- 

 ference in density existed between liquid and vapour appears as follows: 

 When the meniscus appeared we found 0.443 for the density of the 

 vapour at the height 35. So we estimate the density at 0.452 at the height 

 of the meniscus (25) according to the correction of § 5 (doubtful); 

 bulb 0.450, however, floats on t he meniscus. The density on the 

 bottom is < 0.483 (height (see § 7 beginning) 5 cm. under 30), so 

 we estimate the density of the liquid at 468 at the height of the 

 meniscus; bulb 0.466 floats. Vapour and liquid differ, therefore, 

 certainly less than y i0 , ant ' probably no more than 7>o m density. In 

 the first experiment we found o„ > 0.421, o/ < 0.483 from which 

 q p ^> 0.430 , qi < 0.468 follow with the estimated correction for 

 gravity; so under these less favourable circumstances a difference 

 of less than l / l0 is most likely realized. These results concerning the 

 closer and closer approach of the density of liquid and vapour, 

 which quite agree with the views of Andrews-van der Waals, 

 deprive the much larger differences of phases at the same tempera- 

 ture and pressure above the critical temperature, which Teichner 

 derives from his experiments, of' all importance A ). 



J ) This includes the discussion of' the mist stage of von Wesendonck, which 

 would constitute the transition stage in the neighbourhood of the critical state, 

 and which in any case can only extend over a small part of the region of density 

 and temperature where a mist can be seen. 



-) Young, Journ. Ghem. Soc. 71 (1897) p. 45a stated at O^.Oa below the critical 

 temperature a difference of 14% between the liquid and vapour densities. [Note 

 added in the translation]. 



3 ) The readings of the temperature have been reduced to those on a thermo- 

 meter which had been controlled with an air thermometer accurate up to 0",01 

 by the Phys. Tech. Reichsanstalt. Our result agrees with that of Keesom, 30°. 98 

 (Gomm. N". 88 see above), made with the same thermometer Moreover, besides 

 and after the determinations of the critical temperature of GO. : cited in Landolt- 

 Börnstein-Meyerhüffer's Phys. Ghem. Tables are to be mentioned : Verschaffelt 

 Zitt. Veisl. Juni '96 (31°. 0), von Wesendonck Verb. d. De dsch. Phys. Ges. 

 5 p. 238 (3<P.9o), Brinkman Diss. Amsterdam 1904 (31°.12). 



') It is true we might assume that the equilibrium of liquid and vapour with 

 so slight a difference of density as we observed, is only reached after so long a 

 time as was allowed in this experiment to obtain equilibrium of temperature and 

 that at first slates with greater difference of density of liquid and vapour (cf. 

 note 1 p. 1 § 1) appear at the same temperature, which gradually pass into the final 



