1399 
Korsen with regard to the deviation from SurHeruaNnn’s formula of 
the observations on hydrogen at liquid air temperatures. 
At hydrogen temperatures SuTHERLAND’s formula is shown to be 
entirely unsuitable for expressing our results. It gives a value two 
or three times too small. We have tried to represent the series of 
measurements by another formula, and in column 4 under nj . 107 
we have given the values which we have calculated by the 
following formula. 
7 T \0.647 
clea) 
As can be seen, this empirical formula agrees remarkably well 
with the values found over the whole extensive field of temperatures. 
In a following paper we sball discuss the values for 
to VE 
mn VT, 
which follow from our experiments, and further the viscosities at 
various temperatures for different substances in connection with the 
law of the corresponding states. 
Physics. — ‘“Jnvestigation of the viscosity of gases at low tempe- 
ratures. IIT, Comparison of the results obtained with the law 
of corresponding states’. By H. KaAMERLINGH ONNEs and 
SoPHus Weper. Communication N°. 184c from the Physical 
Laboratory at Leiden by Prof. H. KAMERLINGH ONNEs. 
§ 1. Dependence of the viscosity upon temperature. We have 
already discussed this in our previous papers. It was shown that 
SUTHERLAND's formula in no way corresponded to the observations 
at low temperature, either for hydrogen or for helium *). REINGANUM’s 
formula although founded upon acceptable bypotheses about the, 
constitution and mutual action of the molecules, is even worse so 
long as we regard C in it as constant. This can be easily understood 
when we consider that SUTHERLAND's formula can be taken as a 
first approximation to RerINGANUM's, and that the terms left out must 
lead to a further divergence from the observations. Neither is it 
possible to come to an even approximate agreement at low tem- 
1) Shortly after our paper an important article by Eucken appeared in the 
Phys. Zeitschrift (April 15th 1913) in which observations concerning the visco- 
sity of helium and hydrogen taken from an as yet unpublished paper by Voce. 
were communicated, Within the limits of accuracy, which in Voecer’s observations 
are given at 5°/) at hydrogen temperature, these confirm oir measurements, of 
which the accuracy at hydrogen temperatures is to be put at about 1°/ . 
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