941 
TABLE I. 
Oxygen | Nitrogen 
a LET y ; 
T | Be X103 | T | Bo X10) 
| | | | ARR 
412.6 | + 0.213 | AMAGAT 1 472.5 | + 0.690 AMAGAT 
372.6 | — 0.088 : | 372.45 | + 0.324 p 
293.1 -— 0.848 | Onnes&HyNDMAN 290.6 lhe 0.298 Lepuc 1910 
288.7 | — 0.694 : || 289.1 | — 0.234 AMAGAT 
288.7 | — 0.739 | AMAGAT | 288.0 | — 0.316 | RAYLEIGH 
288.1 | — 0.645 | Lepuc 1910 | 2731 | 0.312 | Amacar 
284.3 — 0.791 | RAYLEIGH | 
273.1 — 0.812 | ONNES & HYNDMAN 
273.1 | — 0.928 AMAGAT | 
suffice to determine the quadrupole moment, besides the diameter 
of the molecules when regarded as spheres. 
For this purpose we take the values of B/B,, for different values 
of T/Tinv=o) for spherical quadrupole molecules from Comm. 
Leiden, Suppl. N°. 39a and c. 
Applying the method of the logarithmic diagrams (comp. Comm. 
Leiden, Suppl. N°. 25) we found successively : 
For oxygen: 
for the inversion temperature of the Joule-Kelvin-effect for small 
densities : 
Tinv (o=20) = 728 (450° C), 
for the potential energy of the molecules in contact (with the qua- 
drupole axes mutually perpendicular and perpendicular to the line 
connecting the centres): 
e500) x10, 
for the diameter of the molecule: 
o = 2,65 « 10-8, 
for the quadrupole moment: 
u, = 3,55 X 10-% [e.st.e. X cm’). 
For nitrogen: 
T inv (e=0) = 604, (381°C.) 
y = 4,77 X 10-44, 
B AS Oe, 
Bi 30. 102 Me steak em]: 
