262 
THE ED STING OF IRON AND| STEEL. 
There is one other little point that arises out of Professor Dunstan’s reference 
to the peculiar local action that is noticeable upon some of the surfaces of metal 
that he has shown us. In connection with copper alloys, I have observed one 
curious fact, which is that if a sheet of such metal, brass or bronze, be distorted, 
if it is bent or if it is perforated by a punch or anything of that kind, the part 
which is thus distorted is the first, to be attacked. A plate of bronze, for instance, 
in its ordinary flat condition as it comes from the mill if it were immersed in 
various corrosive substances would resist the action for a long time but if it was 
simply bent across and placed into solution it would proceed to corrode to a great 
extent and I think it is possible that in the case of iron something of the same 
kind may occur. These sheets are sheets, not of chemically pure iron, I am not 
quite sure whether they are steel or wrought iron ; but at any rate they have 
been milled in the ordinary way and they necessarily have a grain of some kind, 
and I think it is that slight difference of texture which in some kind of way gives 
rise to the very curious effects that are noticeable. 
I listened with a great deal of pleasure to what Professor Dunstan has said ; I 
feel that I have learnt a great many things this afternoon and I wish him well 
in the prosecution of his inquiries. At the same time before I begin to teach his 
theory to my pupils I must feel quite sure that I am on safe ground and I want 
to know whether he actually throws over the old theory altogether or whether he 
would still allow that it is occasionally operative. 
Mr. Webster : With regard to the oxidation of iron and other metals, I have 
had considerable experience, I have especially used wrought and cast-iron plates 
in the purification of contaminated water and sewage, these plates being used as 
electrodes. The quantity of impure liquid acted upon at different times repre¬ 
sented a town of from 2,000 to 5,000 inhabitants with the usual English Manufactur¬ 
er’s waste products the experiments lasted several years and some sixty tons of iron 
plates were oxidised or used up. I am still carrying out experiments in my 
laboratory and have verified the old work which was absolutely accurate when 
properly carried out. I was unable to personally superintend any experiments 
in 1891-2-3, owing to long continued illness. The analysis of the first ex¬ 
periments, done by the opposition, were, I am sorry to say, “ faked ” and only a 
few months ago I received a confession to that effect but the analysis of Sir 
Henry Roscoe, E.R.S., Mr. Fletcher, F.I.C. etc., (who was then Chief Inspector 
for the Rivers’ Pollution Act for Scotland, and Alkali Act for England Mr. 
Midwinter, F.I.C., F.C.S. (Analyst for Windsor) Mr. Carter Bell, F.I.C. (Analyst 
for Salford) Mr. Burkhardt, (Consultant for Salford) and others absolutely 
corroborated my original statements as to the oxidation of iron electrolytically 
producing the purification which prevented putrefaction. This was at the time 
further corroborated by experiments carried out in Paris at Pasteur’s Laboratory. 
My experience with regard to the oxidation of iron is, that in the negative 
condition it does not oxidise and that even at such a low potential as 0'9 volts, 
iron electrodes decompose water, the usual potential being l - 5 volts. 
Professor John Hopkinson, F.R.S., who was my consulting Electrical Engineer 
in 1888-89 was surprised when I explained this phenomenon; and after his ex¬ 
periments came to the conclusion that oxidation of iron in impure liquids un¬ 
doubtedly did its work. In the case of decomposing vegetable and animal matter 
in solution carbonate of ammonia is formed and the iron is more easily oxidised. 
All sewage and impure water contain chlorides and in consequence the iron 
electrodes require much less E.M.F. to become oxidised; at the positive electrode 
the hypochlorite of the metal is undoubtedly formed but being an unstable salt 
it quickly becomes a chloride, or as is more probably the case the chlorine attacks 
the organic matter and sets free the metal, which as the negative electrodes give 
