566 TRANSACTIONS OF SECTION B. 



the ferro-silicon has been broken into pieces of the size in which it is usually 

 sold some time before being taken on board ship ; the marking in bold letters 

 of the certified percentage grade of each consignment on the barrel or other 

 receptacle, and the date of manufacture ; the prohibition of conveyance of ferro- 

 silicon on passenger vessels; and the adoption of certain precautions during 

 transport in cargo boats. 



7. The. Corrosion of Iron and Steel. By J. Newton Friend. 



During the last few years the consumption of iron for structural purposes has 

 largely increased. New steel bridges are being constantly erected, and reinforced 

 concrete is now meeting with an ever-increasing demand. Unfortunately, how- 

 uver, iron is very liable to decay through corrosion, and the loss entailed thereby 

 is enormous ; for not only must our new structures be built more solidly than 

 would otherwise be necessary, but many of our old structures have to be rebuilt 

 with fresh metal, which is both costly and wasteful. 



The importance of understanding the underlying causes of corrosion can 

 therefore be scarcely exaggerated. Two rival theories have been suggested. 

 The one, known as the electrolytic theory, assumes that pure oxygen (or air) 

 and pure liquid water alone are necessary to effect the rusting of pure iron. 

 According to the acid theory, however, such is not the case, the presence of at 

 least traces of an acid, either free or combined with a base, being essential to 

 corrosion. 



Hitherto no investigator has succeeded in devising an apparatus, absolutely 

 free from objection, by means of which a decision could be arrived at between 

 these two rival theories. The author, however, described a simple form of 

 apparatus by means of which the correctness of the acid theory is established. 

 [A diagram of the apparatus is given in the Proceedings of the Chemical Society, 

 June 16, 1910.] 



A small steel cylinder is closed at one end, the open end being plugged with 

 an indiarubber bung, through which two glass tubes pass in such a manner that 

 cold water can be circulated through them, and thus keep the steel cylinder cool. 

 The whole is now suspended in a flask and securely fixed in position by an 

 indiarubber bung, which closes the mouth of the flask. This latter contains 

 about 100 c.c. (i.e., 3 oz.) of strong caustic potash solution, and the pressure of 

 the air inside is reduced to about half an atmosphere. On placing the flask in a 

 water-bath at 100° C. some pure water distils from the potash solution in a 

 constant stream on the steel cylinder, and drips off, thus washing it entirely free 

 from alkali. After a few hours we thus have pure air, pure water, and steel 

 in contact, but no rusting occurs. 



If the alkali is replaced by water, however, rusting occurs with great vigour 

 in a very short time, owing to the presence of traces of carbon dioxide and other 

 acid vapours normally occurring in distilled water and the atmosphere of a 

 laboratory. 



8. The Influence of Heat Treatment on the Corrosion, Solubility, and Solu- 

 tion Pressures of Steel. By Cyril Chappell and Frank Hodson. 



The authors decided to conduct a research on the above lines, as no previous 

 work has dealt with the influence of heat treatment on the corrodibility of steel 

 in a solution like sea-water. They also wished to obtain some definite data as to 

 whether the solubility of steel in dilute sulphuric acid is a correct measure of 

 its liability to corrosion in sea-water. 



The steels used were commercial Bessemer steels of ascending carbon per- 

 centage (supplied by Professor McWilliam), and standard pieces were subjected 

 to the following typical heat treatments : hardening, normalising rolling and 

 annealing. 



Two types of test were carried out : — ■ 



{a) Simple Corrosion.— The loss in weight was determined after immersion 

 in sea- water, out of contact with any other metal, for 28, 56, and 112 davs 

 respectively. J 



{!>) Galvanic Corrosion.— This was tested in sea-water in galvanic connection 



