908 
found that the caleulated coefficients are much too great. To this 
comes that the coefficients thus calculated must be of the same 
value for all substances, at least if a spherical shape is assigned to 
all of them. Attempts to determine them when the shape deviates 
from the spherical form have not yet been tried by anybody, but 
it may be expected that they will not differ much from those that 
have been calculated for the spherical shape. A contribution of 
importance for the decision of the question whether or no apparent- 
diminution exists will be furnished by the experimental determination 
of the equation of state of a monatomic substance. If we should 
have to conclude to diminution of 5 with decreasing value of v 
also for these substances, this diminution of 4 will certainly have 
to be called a quasi-diminution, unless one would assign & constitution 
for which real diminution is possible also to an atom. 
A second view of the cause of the diminution of 5 with v would 
of course be obtained if one should have to ascribe compressibility 
to a molecule, and if one did not explain this compressibility by a 
diminution in size of the atoms, but by their coming closer together. 
If this is to be the cause, the diminution of 5 must not be found 
for a monatomic molecule. To decide this it would be desirable to 
give so considerable and judicious an extension to the investigations 
for such substances as those of ANDREWS for carbonic acid. 
That a molecule consisting of atoms might be compressible in 
consequence of the approach of the atoms seemed a hypothesis to 
me worth investigating. And I[ carried this out in my communi- 
cations in 1901 published in these proceedings. I arrived at a 
formula there, which may be considered as the equation of state 
of a molecule consisting of two or three separate parts which are 
in thermal motion. These separate parts may be separate atoms or 
separate atom groups, which are in close relation at the temperature 
considered, and of which the component atoms are perhaps in 
vibration with almost vanishing amplitude and small period. 
This formula has the following form: 
p+ —+ a (b—2,)| (bb) = ERT. 
= 
In this formula 4 is the volume of the molecules, 5, the volume 
of the atoms or atom groups, and the latter would be the volume 
of the atoms or atom groups when the molecule was compressed 
as much as possible. The quantity £ is equal to */, for a molecule 
composed of two separate parts, and equal to 1 or < 1 according 
to the nature of the motion for a molecule consisting of three parts. 
