OBSERVATIONS ON THE CORROSION OF STEEL IN WATER. 75 



Comparing the corrosion by the bore water with that 

 obtained by distilled water, the surface in the latter case, 

 (Pig. 1) Plate 4, is almost quite uniformly corroded, whereas 

 in the former (Pig. 2) there are distinct patches of oxide, 

 and these are much darker in colour than the usual rust 

 colour. The photographs shown in Plate 4, are about half 

 the original size. 



[As the corrosion at Ooonamble does not arise from the 

 water containing any dissolved corrosive substance we 

 have analysed the steel used in these casings and find it to 

 be of good quality and not responsible for any special cor- 

 rosion. The gases which are evolved from many bores have 

 lately been examined by Mr. Symonds, Department of 

 Public Works, and, so far as these examinations go, the 

 Ooonamble bore appears to be exceptional in containing 

 both oxygen and carbon-dioxide in the evolved gases.] 



We think that future investigations into the corrosion 

 and steel should be pursued to investigate these points : (1) 

 the relation of corrosion to the surface conditions of the 

 metal, (2) the determination of any catalytic influence at 

 work — iron or ferrous compounds; (3) the velocity of the 

 diffusion of substances in the liquid to and from the surface 

 of the metal; (4) the relative corrosion rates of ferrite, 

 perlite and cementite. 



