sphere removed and the aluminium cylinder replaced by the brass 
one; for the rest the external conditions were taken as much as 
possible similar to those in the experiments with the sphere: the 
liquid was about at the same level, so that all the parts of the 
swinging system were surrounded by vapour of the same tempera- 
ture and density as before, and the part of the steel pin which was 
immersed before again reached down into the liquid, so that even 
the small friction due to it was taken into account. The results of 
the experiments were as follows. *) 
1=79°.90 _ d, + d, = 0,00445 
80 33 439 
80 .83 419 
so that at 
r= 79°57 Jd, + d, = 0.00460, 
whence, according to (28) 
PL), 0251; 
so that finally 
TNS ENE 
giving, by means of equation (a) of Comm. 1485 
y = 0 0016787). 
2. The viscosity of other miatures of oxygen and nitrogen. 
By allowing a quantity of liquid air freshly prepared to evaporate 
freely in an open vacuum-vessel for a whole day a liquid mixture 
of oxygen and nitrogen (and argon) was obtained containing about 
60°/, of oxygen. With this mixture a series of similar experiments 
was carried out; the results were as follows 
r= 82°34 , d = 0,94325 , d, + d, = 0,00430, 7 = 21,028 , w= 1,003 
1 — 0,01865. 
1) The conditions of these experiments were not quite the same as in the experi- 
ments with the sphere, as the room-temperature and atmospheric pressure were 
slightly different. We have not inquired into the question, in how far this involves 
a correction to be applied; later on, when pure substances will be used, this point 
will have to be specially examined. 
2) By Potseuitte’s method Cart Forscn (Phys. Zeitschr., 1, 177, 1900) found 
the very different value » = 0,0033. 
The value obtained for » is so small. that the equations for an infinitely extended 
liquid may be applied without correction (Comp. Comm. 1480 § 11). 
