THE CORROSION OF IRON AND OTHER 



METALS 



Part II 



In the former article on this subject (Science Progress, April 

 191 1), it was contended that Moody's argument that iron 

 rusts only in the presence of an acid is essentially correct 

 and that the main precaution to be observed, if it be desired 

 to prevent corrosion, is to avoid the accumulation of liquid 

 films on the surface of the metal ; it was also contended that the 

 introduction of the conceptions and nomenclature of the modern 

 physical chemist has not only done little if anything to advance 

 our knowledge of the subject but has placed difficulties in 

 the way of the practical man : to parade the mythology of 

 ions — hydrogen and hydroxyl — and invoke the entire machinery 

 of an imaginary " electrolytic dissociation," in such a case, 

 when we can express ourselves in terms of simple acids and 

 alkalies, serves no useful purpose. 



As I have insisted repeatedly but with slight effect, it is 

 essential that we should arrive without delay at clear con- 

 ceptions of the nature of chemical change in general, especially 

 in the case of metals ; to this end, it is important that we should 

 seek to introduce an element of common sense into our pro- 

 ceedings and no longer allow ourselves to be tied by narrow 

 considerations. Logic demands that we should endeavour to 

 discuss the problems before us from every possible point of 

 view : as scientific workers, we shall have no claim whatever 

 to consideration if we cannot be scientific to this extent ; 

 and practical men will continue to despise theory if those 

 whose business it is to deal with theory show so clearly 

 that they are the slaves of preconceived opinion and of narrow 

 prejudice ; we must on all occasions be prepared to question 

 the grounds of our belief whatever the issue before us may 

 be and whatever the consequences. In no case should we 

 allow ourselves to be tied by an hypothesis; it is true, that 



3" 



