4:16 Scientific Intelligence. 



40 million tons. Whether these figures are exaggerated or not 

 the wastage by corrosion is so great that the concerted efforts 

 of engineers to produce some form of steel alloy with a capacity 

 for resisting corrosion seems imperatively demanded. Apart 

 from the known valuable properties of chromium steel which is 

 too expensive for use on any considerable scale the most promis- 

 ing suggestion has been the introduction of a small percentage 

 of copper into a mild steel, which has been thought by several 

 investigators to give it a superior resisting power. The report 

 of a new series of corrosion tests by Sir Robert Hatfield upon some 

 American steels containing from .02 to .27 per cent, of copper 

 has just been published. The results of the author's 

 observations may be stated as follows: (a) Under atmospheric 

 corrosion copper steel was rather less affected than ordinary 

 steel especially in the more corrosive condition of an industrial 

 atmosphere. The superiority was of the order of 10 per cent, in 

 pure air and 25 per cent, under the industrial contamination. 

 As is generally the case, material with the rolling scale removed 

 was more resistant than with the scale on. (b) In sea water 

 ordinary steel corrodes more rapidly at first but the rate of 

 corrosion for both materials slows up showing a certain degree 

 of self-protective action which was a little greater for ordinary 

 steel. The total corrosion of the copper steel however was 

 slightly less at the end of 16 weeks than that of ordinary steel. 

 (c) In tap water (Sheffield, England) there was little to choose 

 between the two materials. Though initially not so corrosive 

 as sea water, over a long period it was more corrosive due to 

 the absence of any self-protective action in the presence of tap 

 water, (d) In a 50 per cent, sulphuric acid bath both materials 

 were rapidly attacked at first but whereas the solution of 

 ordinary steel continued at a steady rate, that of the copper steel 

 showed a very much reduced rate after the scale had been 

 removed. The steel containing copper was apparently very 

 resistant to a 50 per cent, sulphuric acid solution, (e) A 20 

 per cent, sulphuric acid solution showed a more vigorous action 

 than the 50 per cent, solution but the superior resistance of the 

 steel containing copper was again confirmed. 



The deductions to be drawn from these experiments are (1) 

 that the superiority of copper steel under atmospheric corrosion 

 is due to and dependent on the amount of sulphurous impurity 

 carried by the air; (2) that no advantage will be gained by the 

 use of copper steel in ordinary fresh water; and (3) that for 

 long immersion in sea water this alloy is. probably inferior. 



The author is further of the opinion that as in the majority 

 of service conditions iron or steel is subjected to total or partial 

 immersion in natural waters it is by no means certain that a 

 copper content as a commercial constituent of mild steel might 

 not be deleterious. — Proc. Roy. Soc. 101, 472, 1822. f. e. b. 



