139 



an experiment that proves about the same thing-. He found, namely, 

 that a passive electrode in diluted sulphuric acid could be cathodi- 

 call} polarized to a feeble hydrogen generation without becoming 

 active. 



The behaviour of chromium in acids can be derived from figure 1. 



^(?. ^^ 0.05 



Fig. 1. 



The 10 log of the hydrogen pressure has been plotted on the abs- 

 cissa, the" potential on the ordinate. The line AB indicates the 



