TRANSACTIONS OF SECTION B. 953 
aombined—that of Chemical Action. In his Presidential Address to the Associa- 
tion last year, Professor Lord Rayleigh made only a brief reference to chemistry, 
but many of us wust have felt that his few remarks were pregnant with meaning, 
-especially his reference to the importance of the principle of the dissipation of 
energy in relation to chemical change. A year’s reflection has led me to think 
“them of peculiar weightiness and full of prophecy. I would especially draw 
attention to the closing paragraph of this portion of his address: ‘From the 
further study of electrolysis we may expect to gain improved views as to the nature 
of the chemical reactions, and of the forces concerned in bringing them about. 
I am not qualified—I wish I were—to speak to you on recent progress in general 
chemistry. Perhaps my feelings towards a first love may blind me, but I cannot 
help thinking that the next great advance, of which we have already some fore- 
shadowing, will come on this side. And if I might, without presumption, venture 
a word of recommendation, it would be in favour of a more minute study of the 
‘simpler chemical phenomena.’ 
Chemical action may be defined as being any action of which the consequence 
is an alteration in molecular constitution or composition; the action may concern 
molecules which are of only one kind—cases of mere decomposition, of isomeric 
change and of polymerisation ; or it may take place between dissimilar molecules— 
cases of combination and of interchange. Hitherto it appears to have been com- 
monly assumed and almost universally taught by chemists that action takes place 
‘directly between A and B, producing AB, or between AB and CD, producing 
AC and BD, for example. This, at all events, is the impression which the ordi- 
nary average student gains. Our text-books do not, in fact, as a rule, deign to 
notice observations of such fundamental importance as those of De La Rive on the 
‘behaviour of nearly pure zine with dilute sulphuzic acid, or the later ones of 
Faraday (‘ Exp, Researches,’ Series vii., 1834, 863 e¢ seg.) on the insolubility of 
-amalgamated zinc in this acid. Belief in the equation Zn+H,SO,=H, + ZnSO, 
hence becomes a part of the chemist’s creed, and it is generally interpreted to mean 
‘that zinc will dissolve in sulphuric acid, forming zine sulphate, not, as should be 
the case, that when zinc dissolves in sulphuric acid, zinc sulphate, &c., are produced. 
In studying the chemistry of carbon compounds, we become acquainted with a 
Jarge number of instances in which a more or less minute quantity of a substance is 
capable of inducing change in the body or bodies with which it is associated with- 
‘out apparently itself being altered. The polymerisation of a number of cyanogen 
‘compounds and of aldehydes, the ‘condensation’ of ketonic compounds and the 
hydrolysis of carbohydrates are cases in point; but so little has been done to 
ascertain the nature of the influence of the contact-substance, or catalyst, as I 
‘would term it, the main object in view being the study of the product of the 
reaction, that the importance of the catalyst is not duly appreciated. Recent 
discoveries, however—more particularly Mr. H. B. Dixon’s invaluable investigation 
on conditions of chemical change in gases, and the experiments of Mr. Cowper with 
-chlorine and various metals, and of Mr. Baker on the combustion of carbon and 
‘phosphorus—must have given a rude shock, from which it can never recover, to the 
elief in the assumed simplicity of chemical change. The inference which I think 
may fairly be drawn from Mr. Baker’s observations—that pure carbon and phos- 
phorus are incombustible in pure oxygen—is indeed startling, and his experiments 
“must do much to favour that ‘more minute study of the simpler chemical phenomena’ 
~so pertinently advocated by Lord Rayleigh. 
But if it be a logical conclusion from the cases now known to us, that chemical 
action is not possible between any two substances other than elementary atoms, 
and that the presence of a third is necessary, what is the function of the third body 
-—the eatalyst, and what must be its character with reference to one or both of the 
‘two primary agents? In the discussion which took place at the Chemical Society 
-after the reading of Mr. Baker’s paper, I ventured to define chemical action as 
reversed electrolysis, stating that in any case in which chemical action was to take 
place it was essential that the system operated upon should contain a material of 
the nature of an electrolyte (‘ Chem. Soc. Proc.’ 1885, p. 40). In short, I believe 
that the conditions which obtain in any voltaic element are those which must be 
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