1891.] 



The Passive State of Iron and Steel. 

 FIG. 4. 



125 



The steel rods selected for this set of experiments were of the kinds 

 given on Table IV ; they were drawn cold through a wortle, and were 

 of the general physical properties and chemical composition given on 

 Tables IV and V. 



The reduction of E.M.F. towards the close was probably owing to 

 partial diffusion between the two acids of different concentration. 



The above results show that wrought iron was less passive in the 

 weaker acid than most of the steels, the soft Bessemer steel being 

 found similar in passivity to the wrought iron. 



The average E.M.F. was as follows : With wrought iron, 0'054 

 volt ; soft cast steel, 0'028 volt ; hard cast steel, 0*036 volt ; soft 

 Bessemer steel, 0'059 volt ; tungsten steel, 0'039 volt. 



