645 



the inversion point for the Joule-Kklvin effect at small densities 

 (200.6° K.) was (aken from the calculations by J. P. Dai.ton '). 

 Blur the value of B for the just mentioned temperature, was calcu- 

 lated from the special reduced equation of state for hydrogen, 

 communicated in Comm. N°. 109a § 7. 



In this manner no sufficient agreement was, however, obtained, 

 neither with the quadruplet-equation, nor with the doublet-equation; 

 the value for 100° C. deviates pi'etty considerably from the calcu- 

 lated curves. 



This is to be ascribed chiefly to the value, whicli is assumed for 

 Tinii'=,)- The special equation of state used for the calculation of 

 Ti„ti-=(i) appears to give a somewhat less perfect agreement with 

 experiment in this region than elsewhere, and this fact has a con- 

 siderable influence on the result obtained for 7^,„,.(p=o) in consequence 

 of the circumstance that for the deterniinalion of 7'„i(,c=o, the value 

 of dB/(lT is of great inqwrtance. 



A value of 7'„,.(^=o) was iherpfore subsequently deduced with the 

 aid of an eqnaiion which shows a good agreement in tliis region 

 of temperatures; for this purpose an equation of the form (19) was 

 chosen, and its constants were derived from the experimental data. 

 From the residts of Kamekt.ingh Onnes and Braak we obtained: 

 r,„,.^=ü= 194.5, iJ.v„,„= 0.000465. 



Fig. 2 shows what agreement is 

 obtained with these values o'f the 

 constants '). B'or comparison the 

 curve following from van der Waals" 

 equation with constant a\y, h\y and 

 Kw is also represented. 



It appears now that, as expected, 

 for (he temperature region under 

 consideration the values of B for 

 hydrogen can be made to agree with 

 the equation derived for spherical molecules carrying a quadruplet, 

 just as well as with the equation derived for doublets. 

 From the value found for Bi„o we obtain for o^): 

 rj = 2,32.10-« cm. 



Fig. 2. 



1) J. P. Dalton. Comm. N". 109a (March 1909). 



2) The values taken from the measurements by Schalkwijk, and by Kamer- 

 LINOH Onnes, Ghommelin and Miss Smid are indicated by S and OCS respectively. 



3) l'>om £n hw = 0.000465, and BimlB^ = 0.660 (table I), follows J5x^ =0.000705. 

 ^NooC'. = 0.99942 then gives B^,, = 000705. B.\i„ = 0.000705X22412= 15.80= 

 =:J-iV . 4 -If''. Willi iV = 6.06.1 0--' accoi'ding to Milltkan one obtains for the dia. 



