1156 



Mr. J. M. Burgers for the care bestowed on the regulation of the 

 temperatures. 



The pressures^) are given in international cms mercury of 0° C. — 

 tiie re(hiction of the mercury columns which were read on the brass 

 scales being made with 0.000163 as tiie coefficient of expansion — '- 

 and in international atmospheres respectively, the international atmos- 

 phere at Leiden being taken equal to 75.9488 cms mercury at 0° C. 

 The table also contains the results in the neiglibourhood of the critical 

 point as found in Comm. N°. 151c. 



As regards the independence of the condensation-pressure from the 

 quantity of liquid condensed the following data may sufTice : 



TABLE II. 



These data refer to two determinations and the differences observed 

 in both cases do not betray any systematic deviation in the direction 

 as would have to be expected, if the hydrogen were impure. 



In the representation of the observations by a formula we were 

 able to avail o.urselves of Professor Vkrschaffelt's kind assistance, 

 who succeeded in obtaining a satisfactory agreement with the obser- 

 vations by means of the relation 



T Zo.9p= -56.605 + 3.8015 7—0 104587'^ + 0.003321T»- 0.000051027". 

 {p being expressed in international atmospheres ^). 



The deviations reduced to degrees are larger, however, (especially 

 in VII and VIII) than we had a right to expect in view of the 

 arrangements of the measurements. As it concerns deviations not only 

 from the formula, but from a smooth curve, we must assume in the 

 meantime that in VII and VIII some unexplained experimental 

 error lies at the bottom of the disagreement. 



§ 5. Determination of the boiling jwint of hydrogen. In order to 

 connect our 'determinations to those of Comm. N°. 137/^/ we have made 



1) Leiden Comm. iN^. 44. These Proceedings, i, p. 213. 



') According to this formula the critical pressure (at Tk = 38°.18 K) is found 

 to be 12.75 int. atm. in Comm. N". Iblc 12.80 atm. was found. 



