1158 



as 0.00115 i> corresponds to 0.01 of a degree, it follows that the 

 difference Kamerlingh Onnes and Keesom — Cath and Kamermngh 

 Onnf.s amounts to only .02 of a degree ^). In this we approach the 

 probable error of the measurements. 



In estimating the difference of the boiling point given in Comm. 

 N". 137*^/ wilh the value now obtained by us, we have to take into 

 account the following circumstance : in Comm. N'. 137(/the calibration 

 of Pt'j is carried out with a hydrogen-thermometer described in 

 Comm. N". 141n', whereas our measurements are based on the helium- 

 tiiermometer. Reducing this calibration to the readings on the helium- 

 thermometer which was in the same bath during the calibration of 

 the resistance in Comm. N°. 141rt, the temperatures in the hydrogen- 

 range (comp. Table I in Comm. N". 141^/) have to be raised by .02 of a 

 degree. Tlie value of 20.33 K found in 137c7 has thus to be replaced 

 by 20.35 K. All the values given by Kamerlingh Onnes and Keesom, 

 which are contained in column 6 of Table III have been corrected 

 in the same manner. 



The difference of 0.04 of a degree which thus remains near the 

 boiling point is larger than might have been expected in view of 

 the accuracy of the separate observations. Witli the exception of 



1) In Comm. N". 137d § 4, note 2, p. 42. Kamerlingh Onnes and Keesom, 

 compare their measurements on the vapour pressure of hydrogen with those of 

 Travers and Jacquerod. To this end Kamerlingh Onnes and Keesom recalcu- 

 late the results which these observers obtained with the aid of a hydrogen ther- 

 mometer [the most prominent is the boiling point of hydrogen, 20°22 from the 

 absolute zero on their hydrogen thermometer (20°. 41 from the absolute zero on 

 their heliumlhermometer)] and make use to this end of the pressure coefficient of 

 hydrogen 0,0036628 for the international hydrogen thermometer of 1000 mm. 

 pressure at 0° G , and of the correction to the KELViN-scale according to § 2 of 

 Comm. N". 137fZ for the pressure of 953 mm. at 0° C An error having been 

 found by Kamerlingh Onnes and Keesom in their recalculation we give here the 

 table as it ought to be according to them; introducing at the same lime in the 

 second column of it the correction which we applied to the observations of K. 0. 

 and K. in table 111 above. 



(Note added in the translation). 



