356 NATURE 
for the M.Sc. degree after a course of two years’ 
research work in the University. 
The new laboratory was opened on November 13 
by Sir Sydney Olivier, the Permanent Secretary of 
the Board of Agriculture and Fisheries, in the absence 
of Mr. Walter Runciman, the President of the Board, 
who was detained in London by a meeting of the 
Cabinet Council. At the opening ceremony, Dr. 
Imms gave a short sketch of the aims and scope of 
agricultural entomology, and Sir Sydney Olivier, in 
declaring the laboratory open, explained the policy 
of the Board as regards the endowment of the univer- 
sities and agricultural institutions for research work 
in agricultural science. 
At the conclusion of the ceremony a number of 
exhibits of the research work done in the department 
and of the apparatus used in entomological investiga- 
tions was shown to the visitors in the zoological 
laboratories and museum. S. J.. Hickson. 
THE PASSIVITY OF METALS. 
& GROUP of eight papers brought together with 
the view of setting forth every aspect of ‘ pas- 
sivity’’ as it presents itself to those now actively 
engaged in working out a satisfactory explanation of 
this most difficult and elusive subject, was discussed 
at the meeting of the Faraday Society on Novem- 
ber 12. 
The theoretical importance of passivity lies in the 
fact that it is in all probability so closely bound up 
with the fundamental mechanism of electrolytic action 
that a proper understanding of its cause will go far 
towards clearing away many of the difficulties which 
still surround the simple processes of anodic solution 
and kathodic deposition. It has further an important 
practical bearing on corrosion, for if this be an 
electrolytic action, a non-corrodible metal and a 
passive metal are, anyhow within certain limits, 
synonymous terms. The very idea of the connection 
suggests a line of research on non-corrodible alloys 
that may lead to most fruitful results. But if the 
subject is important, it is no less perplexing. At 
present two theories, in many respects diametrically 
opposed to one another, would appear to hold the 
field, one of which, broadly speaking, ascribes 
passivity to the presence of oxygen in some form or 
another, and the other to hydrogen. It may be added 
that the advocates of each theory point to an experi- 
mentum crucis claimed to prove the impossibility of 
its rival as a satisfactory explanation of all the pheno- 
mena which have been observed. 
While attention was concentrated on the original 
observation made in 1790 by Keir, that iron became 
‘“‘passive’’ or indissoluble after plunging into strong 
nitric acid, the simple mechanical explanation that 
the change of state was due to a close film of pro- 
tective oxide no doubt seemed all-sufficient. It was 
only when passivity was studied as an electrolytic 
phenomenon, as an example of anodic polarisation by 
which the passive metal rises higher in the electrolytic 
scale towards the ‘‘noble’’ metals than it was in its 
active state, that a broader interpretation was called 
for, and hence was put forward Le Blanc’s fruitful 
conception that the retarded anodic action was chem- 
ical and not mechanical in its origin, and that it 
must be explained as arising from the diminished 
reaction-velocity of some chemical process taking 
place at the anode. 
ally adopted in the consideration of passivity pheno- 
mena; the only question arising is, What is the 
reaction the velocity of which is diminished when 
metals become’ passive? 
To this question the following answers were given 
in the papers presented for discussion. 
2299, VOL. 92| 
-lower solution pressure than the pure metal. Sue 
This conception is now univers- 
[NovEMBER 20, 1913. 
(1) Adopting the curren: view of Nernst that e 
trode potential is a result of the formation of me 
ions when the electrode is placed into an electro 
Dr. G. Grube supposes this action to be retarded unc 
conditions known as passive by the formation of 
alloy of anode surface and oxygen, which ha 
retardation of anodic action is known to take p 
when a platinum anode is used in the electrolysis 
halogen salts, and for the self-same reason, 
analogous kathodic retardation was likewise sh 
to exist by Dr. Grube; for example, when zine a 
hydrogen are deposited simultaneously with i 
Much the same theory was developed by Dr. 
Reichinstein direct from the Nernst formula, a1 
experimental support was given to the theory by D 
H. S. Allen, who showed that the photo-electi 
behaviour of iron—its property of losing negati 
electricity under the action of light—which from con-— 
siderations of ‘fatigue’ is believed also to be due to 
se state of the gaseous film on the metal, increases 
- diminishes in intensity according as the iron is 
in the active or passive state. ‘ ae 
(2) In order to take into consideration the specific 
properties of the electrolyte anion some investigators 
are now reverting to the old Grotthus view of electro- 
lysis that the primary action at the anode is not the 
formation of metallic ions, but a discharge of negati 
ions (anions). Prof. Leblanc, however, further su 
poses that the anion is hydrated, and that passivity 
is merely the retardation of the reversible reaction, © 
ion—hydrate—ion+water. Prof. E. Schoch also 
adopts the theory of primary anion discharge, but 
impressed by Dr. Giinther Schulze’s experiments on 
the structure of aluminium anode-films, he considers” 
that under certain conditions of current density, tem 
perature, &c., there will be a diminished rate of 
reaction between anions and electrode owing to 
formation on the latter of a film of oxide or oxygen 
Neither of these theories, which seem to ma 
gratuitous and unnecessary assumptions, were re-_ 
ceived with much favour. 
(3) More attractive is the } 
stated in the paper presented ‘ Prof. 
Schmidt, and Suppo by some i 
condition is normal, and that metals like iron and 
chromium are only rendered active by the diffusion 
through them of hydrogen, which acts as a catalys 
and sets up local action. Possibly this is often the 
case, but it is doubtful whether the ‘hydrogen- — 
activation’ theory will explain all cases of passim 
In the end it may be found, as Dr. G. Senter said i 
the course of the discussion, that no one theory will 
cover every case of passivity, but the sense of 
meeting was certainly in favour of either an oxyg 
film or an oxygen surface alloy as offering in most 
cases a satisfactory working hypothesis of the passive — 
state. : 
T 
/ : 
UNIVERSITY EDUCATION IN LONDO V4 
TRE President of the Board of Education has sent | 
to the Vice-Chancellor of London University 
an important letter in which he announces that the 
Government accepts in general the recommendations 5 
of the Royal Commission on University Education in_ 
London, and is prepared to act upon them. TI a] 
letter is as follows :— mY 
Board of Education, Whitehall, S.Wa 
Nov. 12, 1913. : 
Dear Mr. HerrINGHAM,—1. I am very anxiou 
that the position of the Government in regard to the 
proposed reconstitution of the University should be — 
generally realised, and that discussion should not be ~ 
y 
