THE CORROSION OF IRON AND OTHER METALS 647 



referring to the great debt which chemists owe to Dr. Brereton 

 Baker for his work on highly purified materials — work which 

 he has carried on with unwearied perseverance and with a 

 degree of skill that appears to be altogether peculiar to himself. 

 Strangely enough, such work has only been done in this country 

 and but little attention has been paid to the subject elsewhere ; 

 the significance of Baker's results in relation to the problems of 

 chemical change is certainly in no way properly appreciated 

 at present. 



In the discussion that has taken place since the results of 

 Moody's experiments were made known, it has not been denied 

 that iron dissolves in presence of the carbonic acid which is 

 necessarily present in ordinary water and in the film of water 

 which condenses on the surface of the metal whenever it is 

 exposed in a moist atmosphere at a sufficiently low temperature. 

 What is asserted is that corrosion may and does take place in 

 the absence of carbonic or any other other acid. This assertion 

 may be considered from two points of view — firstly, with refer- 

 ence to the observations on which it is based : that is to say, 

 with reference to the facts ; secondly, from the point of view of 

 the hypothesis by which it is supported. 



The character of the evidence put forward will be best 

 understood if a few quotations be given from Cushman and 

 Gardner's work descriptive of experiments affording results 

 which they claim are proof that iron is dissolved without the 

 intervention of acid and that rusting may be conditioned by 

 water and oxygen alone : 



" The two clean Jena flasks A and B are three-quarters 

 filled with pure freshly distilled water. Two drops of an 

 alcoholic solution of phenolphthalein indicator (i gram in 

 100 cc. pure alcohol) are added to the water in each of the 

 flasks. The beaker C is more capacious than the flasks A 

 and B. The flasks D and E are used in each experiment as 

 blanks to check the results obtained. After connecting up as 

 shown, the water in each vessel is simultaneously boiled very 

 vigorously until about one-quarter is boiled off". The rubber 

 stopper in A is then lifted and clean, polished strips of iron 

 quickly slipped in. The stopper is again tightly inserted and 

 the boiling continued for about fifteen minutes. The lamps 

 under A and E are then extinguished, while the water in 

 B, C and D continues to boil. As soon as flasks A and E 

 have sucked back into boiling water so that they are 



