953 
TABLE Ik 
Critical point of oxygen. 
= ke ae pee ay 
Op cia tid Ty, =o Lhe? Zake Pe = 49.713 atm. | 
Critical point of nitrogen. 
irda) Set i We 
0, ——147°.13C.| Ty, = 125°.96K. | p, = 33.490 atm. | 
In the mean time we confine ourselves to communicating the 
numerical results and we will only add, that using the critical values 
obtained for oxygen the critical coefficient 
k 
Koe 
PkVkd 
where vg is the critical volume derived from the diameter, is now 
found to be 3.419 instead of the previous value 3.346 deduced by 
Marmras and KAMERLINGH Onnus using incorrect data found elsewhere 
in the literature on the subject. (Comm. N°. 117). 
The new value is no longer abnormally small when compared 
with that of normal substances of higher critical temperature and 
very nearly the same as that of argon 3.424 (Comm. N°. 1814). 
Physics. — “The rectilinear diameter of nitrogen” By E. MATHIAS, 
H. Kamertincu Onnes, and C. A. CROMMELIN. (Communication 
N°. 145c from the Physical Laboratory at Leiden.) 
- (Communicated in the meeting of December 30, 1914). 
§ 1. Introduction. This communication is a continuation of the 
investigation undertaken in the Leiden Laboratory on the diameter 
for substances of low critical temperature and simple molecular 
structure, which was begun with oxygen’) and continued with 
argon”). The object and the importance of these investigations were 
fully gone into in the paper on the diameter of oxygen and we 
need not recur to this here. For the further continuation of this 
research helium, hydrogen, and neon did not seem very suitable 
at present in view of the greater experimental difficulties, which 
1) E‚ Marutas and H. KAMERLINGH ONNES, Proc. Febr. 1911, Comm. N°. 117. 
2) E. Marnras, H. KAMERLINGH Onnes, and C. A. GROMMELIN, Proc. Oct. and 
Dec. 1911 and Jan. 1912, Comm. N°. 18la. 
