€ LO) 
is, therefore, no danger in uniting this one kind of deviation with 
the other ones in the common representation which we try to obtain 
for them. According to the method we followed it appears to be 
possible to unite all deviations from the law of corresponding states 
in a single representation as definite as can be desired for the present; 
but, of course, we do not mean to say that it might not be found 
more suitable in a more extended and more searching study of the 
deviations from the law of corresponding states to adopt a different 
method of summarising these deviations. 
In order to be able to ascribe the same value to 4 in every case, 
all the volumes must be expressed in the same unit. This was not 
the case with the observations which are now being dealt with, so 
that some reductions were found necessary. 
y. va , volumes in the argon 
isotherms and in the carbon dioxide isotherms are expressed in terms 
of the experimental normal volume, while those in the isopentane 
and ether isotherms are expressed in terms of the number of cubic 
centimetres per gram of the substance. Since we wished to express 
2) in terms of the theoretical normal volume for all the substances 
we calculated its values according to the following expressions : 
Eo Pr 
for argon. and carbon dioxide: A9 Ws 
T;Aa, 
het Py? 
for isopentane and ether: Av = ——— py U) 
TA:;, 
In these expressions A,, = — is the ratio of the experimental to 
UN 
the theoretical normal volume, and y is the specific mass *) in grams 
per ec. at normal temperature and pressure. 
Values of log 4», were marked off as abscissae, and as ordinates 
values of the common logarithms of the reduced temperatures. Lines 
parallel to the fog 2v axis represent the course of the equation VII. 1, 
while deviations are marked off from these lines, (positive above, 
negative below) in such a way that a 1°/, deviation corresponds to 
5 mm. on the accompanying diagram. We shall call this method of 
exhibiting the deviations in a diagram “arranging according to log t 
the deviations expressed as functions of loy av.” From this drawing 
which, since it contains the deviations for the various substances at 
the different reduced temperatures (the observation temperatures of 
the isotherms), has been somewhat abridged, the deviations for each 
1) Arch. neérl. (2) 6, 874. 1901, Comm. No. 74. 
*) In all these considerations we may neglect the difference between the specific 
mass and the density (number of grams pro m. L.). 
