326 REPORT—1890. 
be impossible, in the time at disposal, to consider more than one of the 
conclusions arrived at by the advocates of the dissociation hypothesis, 
which did not appear to be in accordance with the chemist’s experience. 
It had hitherto been customary to regard the neutralisation of an acid by 
an alkali as a case of interchange or double decomposition, as represented, 
for example, by an equation such as 
KOH+HCI=KCl1+ HOH. 
But now that it was argued that hydrogen chloride, potassium hydroxide, 
and potassium chloride underwent almost complete dissociation when 
dissolved in water to form a dilute solution, it became necessary to 
suppose that in such cases the only new compound formed in solution 
was water, and the main action which occurred on mixing solutions of 
potassium hydroxide and hydrogen chloride was consequently represented 
by the equation 
H+C1+K+0OH=K+C1+H,0. 
Such a conclusion, although undoubtedly a necessary and logical one 
from the dissociationist’s point of view, involved the admission that 
hydregen chloride and water were compounds of a totally different order ; 
that these two hydrides were so different that while that of chlorine 
underwent practically complete dissociation that of oxygen remained 
practically unchanged. Chemists, however, were in the habit of teaching 
that chlorine and oxygen were comparable elements, and the facts of 
chemistry appeared to afford the strongest evidence that hydrogen 
chloride and oxide were in all ways comparable compounds. Moreover 
the behaviour of the two compounds at high temperatures afforded no 
grounds for any such belief in the instability of the one and the stability 
of the other. 
Referring to the series of numerical agreements between theory and 
practice relied on by the dissociationists, the speaker said that in his 
opinion these afforded no necessary proof of the correctness of the theory. 
The correlation of chemical activity and electrical resistance which had 
been established by Arrhenius, Ostwald, and others was undoubtedly of 
the highest importance, but the successful use which they had made of 
the data at their disposal appeared to him to depend on the fact that by 
observations of electrical resistance they were enabled to classify electro- 
lytes in the order of their activity, whether physical or chemical; and 
that, having done this, they were in a position to apply the correction 
required to discount the superior activity of such compounds in compari- 
son with dielectrics, i.e. compounds producing the so-called normal effect 
in depressing the freezing-point, for example. 
Professor FirzgEraLp said :—It is important to distinguish between 
what is implied and what not by experiments: e.g. osmotic pressure, 
change of freezing and boiling points are in no way independent; we can 
deduce one from the other by applying known principles. There seems 
to be a very important connection, which cannot be deduced from known 
principles, between conductivity, the variation of osmotic pressure from 
its value calculated from molecular weights, and the chemical activity of 
a substance in certain relations. The quality upon which these proper- 
ties depend is, I think, certainly the same quality in each case, and its 
existence and importance have been brought to light by the labours of 
