320 REPORT—1890. 
than that of the combination of the atoms and molecules, so that the 
lesser force must be regarded as overcoming the greater.! 
That free ions exist in solution is supposed to have been proved by a 
recent observation of Ostwald’s to the effect that these ions may be 
separated and brought into different parts of the liquid by the proximity 
of a charged body. The separation of the ions is, of course, recognised 
by the subsequent liberation of oxygen. hydrogen, acid, alkali, &c., and it 
is certain that, on allowing these to mix and combine, heat will be deve- 
loped and the salt solution re-formed; and thus, by replacing and 
removing the charged body, it would evidently be possible to produce an 
unlimited amount of heat. Now, if the charged body has lost none of its 
charge, and if no mechanical energy has been expended, this heat must 
have been produced out of nothing, and the whole groundwork of phy- 
sical science is false; whereas, if energy in some form has been expended 
ou the solution, the experiment proves nothing, for there is nothing to 
show that this energy has not been utilised in bringing about that very 
dissociation the previous existence of which was in question. 
I have already shown that the experimental data prove the absence 
of that constancy and regularity which ought to exist according to the 
physical theory, and to place the hydrate theory on unassailable grounds 
it is only necessary to show that the deviations from constancy and regu- 
larity are of a magnitude such as might reasonably be assigned to devia- 
tions due to the presence of hydrates. That variations of 260 and 36,000 
per cent. in the value of the depression—such as are observed by altering 
the dissolved substance or the solvent respectively—are amply sufficient to 
satisfy the most exalted views of the influence of chemical attraction, 
requires, I think, no demonstration, and we may therefore content our- 
selves with examining the deviations observed when the proportions of 
the solvent are altered—such deviations as are illustrated in fig, 1. 
It cannot be maintained that the energy of the chemical combination 
of, say, water with sulphuric acid, is the only reason why the tempera- 
ture of the mixture of these two must be cooled below 0° before any of 
the latter will crystallise out; some lowering of the freezing point will 
be caused by the mere interposition of the foreign molecules of sulphuric 
acid between those of the water, and on certain grounds, which I have 
explained elsewhere,? I estimate this mechanical lowering, as I term it, at 
0°56 for each dissolved molecule to 100 of the solvent (a molecule of 
solvent water being 3H,0O), a value which, it may be noted, is not far 
removed from Raoult’s experimental value of 0°-63. There is also another 
source of lowering depending mainly on the heat capacities of the sub- 
stances concerned, which I term for convenience the physical lowering ; 
but its value, in the case of weak solutions, is very small, and I need, 
therefore, say no more about it here. Both these lowering causes would 
exist whether there were hydrates present or not; but if these were 
present we should get a further depression due ‘to their existence. 
Any given hydrate would have to be decomposed into the next lower one 
before it could give up any water for crystallisation, and a certain 
amount of resistance would thus be offered to this crystallisation, to over- 
1 On the view that hydrates exist in solution, there is no difficulty, as I have 
shown elsewhere, in explaining the absorption of heat during dissolution, without 
violating the principle of the conservation of energy. 
2 Proe. Chem. Soc. 1889, p. 149. 
Fee 
