620 

formation of nickel sulphide, which forms a fusible 
scale. 
Mr. J. Arnott gave a short account of the behaviour 
of Monel metal, which is composed chiefly of nickel 
and copper, towards various reagents. This alloy is 
particularly resistant to sea water, to impure waters 
such as those of many mines, and to steam. 
An important point was brought out by Mr. J. H.S. 
Dickenson, who remarked that for many technical 
purposes stainlessness as usually understood was not 
required, freedom from pitting and gross rusting 
being more important. For example, in submarine 
work it is not essential that parts should remain 
quite bright, but it is necessary that they should 
not become jammed by accumulations of rust. A 
piece of soft stainless steel, merely sand-blasted, had 
been exposed in the garden for eighteen months, and, 
although it had rapidly assumed a yellowish tarnish 
after the first rain, it had not lost weight, while a 
mild-steel sample had rusted badly. Mr. Macnaughten 
remarked that for some purposes a good electrical 
conductivity was required as well as resistance to 
corrosion, and that in such cases pure nickel had 
advantages even over Monel metal. 
Some differences of opinion were manifested in 
regard to the chromium steels. The comparatively 
recent introduction of alloys so low in carbon as to be 
available for use without hardening, and in the cold- 
worked condition, has led to the use of the term 
“stainless iron’’ for such alloys, while other authori- 
ties prefer to regard the stainless steels as forming a 
continuous series of varying carbon content. Com- 
mercial considerations are involved, but it appears 
that for practical purposes there is a division, which 
occurs at the point where the carbon falls so low that 
the use of an expensive ferro-chrome becomes 
necessary in the manufacture. Scientifically, there 
is no break in the series. 
Turning to another class of alloys, an interesting 
announcement was made by Mr. Harold Turner, 
who exhibited articles made of a new standard silver, 
free from copper, but containing the 92°5 per cent. 
of silver required in order to obtain the hall-mark. 
Although it is not claimed that such an alloy is 
resistant to acids, experiments had shown that the 
tarnishing caused by the atmosphere of a town was 
very greatly less than that of standard silver. Fuller 
particulars of this interesting alloy will be given at 
a later date. The working qualities prove to be 
excellent. No account was given of the alloys of the 
nickel silver group, some of which have been improved 
in respect of their resistance to corrosion, particularly 
by the introduction of tin in place of zinc; but Mr. 
F. Orme described some acid tests with several alloys 
of this class, showing little difference between them and 
the older alloys. It was, however, argued that these 
alloys are not intended for exposure to acids, and that 
only a higher resistance to atmospheric action is to be 
expected from them. 
A valuable paper on the mechanism of so-called 
“dry corrosion ’’ was read by Mr. U. R. Evans, of 
Cambridge, whose experiments included the examina- 
tion of a number of metals and alloys when exposed 
to various gases, either saturated with moisture or 
in a relatively dry state, excluding the case of the 
complete absence of moisture. The action was 
regarded as electrolytic, the formation of a thin liquid 
film being an essential part of the process. The 
conductivity of such a film is an important factor. 
When the product formed is hygroscopic, so that the 
surface of the metal becomes visibly wet and the 
liquid may fall off in drops, as in the attack of zinc by 
NATURE 

hydrogen chloride, nickel by sulphur dioxide, and 
copper by ammonia, the corrosion is very rapid. | 
NO. 2792, VOL. IIT] 
[May 5, 1923 
Observation of the tarnish colours formed in the 
early stages of the corrosion seems to indicate that 
local anodic and cathodic areas are present at the 
beginning. The formation of temper colours by 
oxidation at higher temperatures, as in the case of 
iron above 220°, appears to be adifferent phenomenon. 
Dr. R. S. Hutton mentioned that this side of the 
subject was engaging the attention of the Non-Ferrous 
Metals Research Association, and that Mr. Vernon 
was conducting experiments for the Atmospheric 
Corrosion Committee in this direction. Mr. Vernon, 
in a written communication, questioned the necessity 
for the presence of water in such attack by gases, and 
offered an alternative explanation of the facts. 
The discussion undoubtedly served a useful purpose 
in bringing together data as to the classes of alloys 
now available when a greater resistance than usual 
to corroding agents is required. Great progress has 
been made in this direction, to which the stainless _ 
steels and the alloys of the nichrome class, as well as ; 
the older silicon irons, bear witness. The new silver _ 
alloy is a further indication of the attention being 
given to the production of alloys which will suffer 
less by exposure to the atmosphere of towns. Un- 
fortunately, a scientific theory of the phenomena is 
still lacking, the theory of corrosion, in spite of its 
very extensive literature, being lamentably imperfect. — 
The process of trial and error, which is at present 
almost the only method for the discovery of resistant 
alloys, needs to be replaced by a systematic conception 
of the process, which will make it possible to predict, 
with some approach to accuracy, the behaviour of a 
new combination of metals towards a given environ- 
ment. The Faraday Society has already performed 
useful services in regard to this matter, and it is to be 
hoped that when the next symposium is held it may 
be possible to review the subject in a less empirical 
manner. 
— oe a ee 































University and Educational Intelligence. 
ABERDEEN.—Sir Robert Horne, who delivered his 
address as Rector of the University on Thursday, — 
April 26, dealt with the relation of the Universities to — 
post-War problems, and with their increasing responsi- — 
bility for ‘‘ cultural’ education in an age in which 
the pressure of business leaves less and less time for — 
the cultivation of the arts. After the address, he ~ 
announced that he intended to offer a prize of 25/. — 
for an essay on ‘‘ The Function of Universities in the ~ 
Modern State.” ie 
CaMBRIDGE.—Prof. Nuttall and Sir William Pope 
have been appointed to represent the University at 
the ceremonies connected with the centenary of the © 
birth of Pasteur to be held in Paris and Strasbourg — 
during the present month. a 
In connexion with the jubilee celebration of the — 
Local Lectures to be held in Cambridge in July, it is — 
proposed to confer honorary degrees on Sir Michael 
Sadler, Prof. R. G. Moulton, and Messrs. Albert 
Mansbridge, G. P. Bailey, J. H. Fisher, and A. Cobham. 
Sir Archibald Garrod, Regius professor of medicin 
Oxford, will deliver the Linacre Lecture on May 5, 
subject being ‘‘ Glimpses of the Higher Medicine.” 
Lonpon.—A research studentship for post-gradua 
work at the London School of Economics and Politi 
Science will be awarded in July next. Its value will 
be 175/.,in addition to fees, and it will be tenable fo 
two years. Application forms 
returned not later than May 31) can be obtained 
from the director of the School, Houghton Street, 
Aldwych, W.C.2. fi 
