1157 



two series of determinalions A and B using the same vapovir-pres- 

 snre apparatus and the same crjOHtat as were used by Kameklingh 

 Onnks an(] Keksom, B falling in the immediate neighbourliood of 

 the boiling point. The results were as follows: 



The two series A and B were made with two different helium- 

 thermometers : the satisfaetorj agreemenl between the two may be 

 taken as a guarantee of the accuracy obtained. 



The lifth column shows the deviations from tlie formula given in 

 § 4 reduced to degrees; the sixth column gives the measurements 

 by Kameklingh Onnp^s and Kkesom of Comm. N". 137 J corrected in a 

 manner which will be explained presently. 



From the data of Table III it follows by interpolation in the 

 table that the boiling point is T= 20°.39 K. In Comm. NM37rf20°.33K. 

 was found. To explain this difference we may utilize the reading of 

 the thermometer J^t'j which in these measui-ements was placed in 

 the bath of liquid hydrogen together with the vapour-pressure tube. 

 In the investigation l)y Kamerlingh Onnes and Keesom, who deter- 

 mined the temperatures by means of Bf'/ one of the readings gave 



p,,,, = 78.91 cm. IIW' = 1 -928 o, 

 whereas from our measui-ements we find by interpolation 

 p,,i,-^ = 78.91 cm. Wpir = 1.9304 _^i 



80* 



