( 740 ) 
Whether this renders it desirable for us to give it a prominent place 
in the theory of solutions and make all the rest proceed from it, is 
a question to which IT wish to revert in a separate paper. 
First I must add this observation. The insight obtained in the 
nature of the osmotic pressure enables us to examine what quantities 
must occur in the formula for more concentrated solutions. In the 
first place it will no longer be true for concentrated solutions, that 
the term “2 vanishes, both because on the two sides of the mem- 
brane the density v differs, and because the concentration and so 
the a will differ. Further — as appears from our proof — for 
higher concentrations the volume of the molecules will assert its 
influence, and not only that of the dissolved substance, but also of 
the solvent. For as on the two sides of the membrane the density 
differs, the part of the plane of impact that falls within the distance 
spheres of these molecules, will no longer be represented by the 
above given value. As finally the molecules are of different size, 
when the terms 5, and 4, occur, the term 4,, is sure to appear. 
The formula found in this way will certainly not agree with the one 
found in the preceding communication by a thermodynamic method, 
for the latter is derived from the equation of state with constant 4, 
whereas the kinetic considerations exclude all doubt that 6 is a 
function of the volume. If ihere should be a real diminishing of 
the size of molecules when passing beyond the membrane, then this 
fact is also to be taken into account. 
Far be it from me to make an attempt to draw up such an 
equation. To achieve this, it would be required, as appears from 
what precedes, that one should be able to surmount at least all the 
obstacles which stand in the way of an accurate equation of state. 
And if this might be done — the preceding paper proves it — the 
final formula could be found in a way, which would not expose 
us again to the danger of making errors. [ shall therefore not enter 
into the question either, in what way the formula derived in a kinetic 
way can satisfy the first requirement that may be put to every formula 
for concentrated solutions: that it yields the value «© for the case 
that the substance passing the membrane has perfectly vanished from 
the solution. 
§ 9. I shall just add a single remark on the question whether 
our kinetie view implies that the so-called statie theory of the osmotic 
pressure, which ascribes the cause of the phenomenon to attractive 
forces, is entirely wrong? It seems to me that from what Lornntz 
has proved it appears that we must answer this question in the 
negative. It is true that we have seen that the attraction of solvent 
