an absolute way a question devoid of
sense to ask whether in a solution the solute is in the liquid or the
gaseous state. It is in the fluid state, and perhaps in conditions
opposed to those of a body in the state of a perfect gas. It is known,
of course, that in this case the manometrical pressure must be
regarded as very great in relation to the internal pressure which, in
the characteristic equation, is added to the other. May it not seem
possible that in the solution it is, on the contrary, the internal
pressure which is dominant, the manometric pressure becoming of no
account? The coincidence of the formulas would thus be verified, for
all the characteristic equations are symmetrical with regard to these
two pressures. From this point of view the osmotic pressure would be
considered as the result of an attraction between the solvent and the
solute; and it would represent the difference between the internal
pressures of the solution and of the pure solvent. These hypotheses
are highly interesting, and very suggestive; but from the way in which
the facts have been set forth, it will appear, no doubt, that there is
no obligation to admit them in order to believe in the legitimacy of
the application of thermodynamics to the phenomena of solution.

Sec. 4. ELECTROLYTIC DISSOCIATION

From the outset Professor Van t' Hoff was brought to acknowledge that
a great number of solutions formed very notable exceptions which were
very irregular in appearance. The analogy with gases did not seem to
be maintained, for the osmotic pressure had a very different value
from that indicated by the theory. Everything, however, came right if
one multiplied by a factor, determined according to each case, but
greater than unity, the constant of the characteristic formula.
Similar divergences were manifested in the delays observed in
congelation, and disappeared when subjected to an analogous
correction.

Thus the freezing-point of a normal solution, containing a molecule
gramme (that is, the number of grammes equal to the figure
representing the molecular mass) of alcohol or sugar in water, falls
1.85 deg. C. If the laws of solution were identically the same for a
solution of sea-salt, the same depression should be noticed in a
saline solution also containing 1 molecule per litre. In fact, the
fall reaches 3.26 deg., and the solution behaves as if it contained, not
1, but 1.75 normal molecules per litre. The consideration of the
osmoti