662 



The two measurements for solid nitrogen give the relation 



/„^;, = -^ + 4.7769; 



as holding- near the (riple-point ; this combined with the equation 

 for liquid nitrogen gives for the triple point (i.e. the point of inter- 

 section of the two vapour-pressure curves). 



7'=63°.23 K, /; = 0.1269 int. atm. =9.64 int. cm. 



whereas v. Siemens, account being taken of Holst's corrections, found 



r=:63".25K. />=:9.35cm. 



In Table IV v. Siemens' results — after correction according to Holst 

 of the reduction to the scale of Kamkrlingh Onnes c.s. — and those 

 of Hamburger and Holst to which I have applied a small cor- 

 rection ') are compared with the equation which represents my 

 obser\ations. 



Finally I have tried to connect my results to Crommelin's measure- 

 ments between the boiling point and the critical point'). The latter 

 may. be represented satisfactorily') by the equation') 



regards my measurements it seems improbable thai the iincerlainty in the deter- 

 mination of the temperature, independently of systematical errors, has been larger 

 than about Ü.01 of a degree (of. table 111), and — in view of the recent deter- 

 minations with the instrument, which will be published in the next communi- 

 cations — the systematical error of the Leiden gasthermometer (apart from the 

 effect of errors in the expansion of the glass and in the constant for the capil- 

 lary depression of the mercury) al^o may b ' put at about 0.01 of a degree. 



With regard to the ditïerences in Table IV it should be borne in mind, that 

 the observations of v. Siemens as well as those of Hamburger and Holst are 

 based on the readings of a platinum thermometer, which has not been compared 

 directly with the gasthermometer. They cannot serve therefore to estimate the 

 systematical error in the temperature-determination. [This note has been somewhat 

 modified in the translation]. 



1) Hamburger and Holst (these Proc. X\'ill i (1915) p 872) obtained tlieir 

 results by reducing the readings of their platinum-thermometer to the vapour- 

 pressures as found by Kamerlingh Onnes and Braak (comp. note 2 page 660). 

 As the authors also give the temperatures at the oxygen-pressures observed by 

 them and as at 78°.42 K. their temperature is 0.05 degrees higher than my results 

 for oxygen which are at present the only direct measurements of sufficient accuracy 

 in that region, I have applied a correction of that amount to their temperatures. 

 These are marked with an asterisk. 



2) Gomm. N". Ubd, these Proc. XVll (2) p. 959. 



3) We leave out of account the reading at 81°.21 K., which Crommelin himself 

 marked as inaccurate by placing it in square brackets. 



"*) The agreement with this formula containing two terms of the expansion of 

 Tlog p in powers of T is not inferior to what is obtained by means of three 

 terms of the expansion in i/2' as given by Crommelin. The latter formula, however, 



