OBSERVATIONS ON THE CORROSION OF STEEL IN WATER. 67 



OBSERVATIONS on the CORROSION OF STEEL in 



WATER. 



By G. J. Burrows, b.sc, and C. E. Fawsitt, d.sc. 



[Contribution from the Chemical Department, University 

 of Sydney.] 



[With Plate IV.] 



[Read before the Royal Society of N. 8. Wales, July 5, 1911. .] 



Our attention has been specially drawn to this subject 

 recently in connection with the corrosion of Artesian Bore 

 casings. The corrosion of steel, in spite of investigations 

 by many experimenters, presents peculiarities which are 

 not properly understood and are often contradictory. It 

 is safe to say that conclusions of a general character can 

 only be drawn from series of observations made wholly 

 under the superintendence of one observer who is entirely 

 acquainted with the conditions of experiment. 



(1) Theory of Rusting.— The production of rust from iron 

 requires the presence of free oxygen and water, and takes 

 place in at least two stages. A ferrous compound is formed 

 in the first instance ; this is then oxidised to rust. We do 

 not think that the presence of carbon dioxide is necessary 

 for rusting. 1 Solutions of sodium carbonate, if they 

 dissolve any carbon dioxide, will not hold this free, but 

 combined as bicarbonate. Now neither bicarbonate nor 

 carbonate of soda prevents rusting. Indeed they sometimes 

 accelerate it. The presence of free carbon dioxide is there- 

 fore not necessary for rusting. We believe that the forma- 

 tion of a ferrous compound in the first stage of rusting 

 follows the equation 



2 Fe + 2 + 2 H 2 = 2 Fe(0H) 2 



1 Cushraan and Gardner, " The Corrosion and Preservation of Iron and 

 Steel/' 1910, p. 35. Dunstan, Journal Chemical Society, 1905, 87, 1548). 



