146 ^^6 Philippine Journal of Science 



method. Acetic acid gives accurate results, but the action is 

 slow. 



The separation can also be effected by the use of metallic salts, 

 notably certain salts of lead, cadmium, copper, cobalt, chromium, 

 and aluminium. The experiments with metallic salts give an 

 indication of the changes in the potential of metals which occur 

 in different liquids. 



Stripping and analysis may be accomplished with the aid 

 of the electric current, by making galvanized iron the cathode 

 in sulphuric acid, or by making it the anode in concentrated 

 caustic alkali solutions or in oxidizing solutions like sodium 

 nitrate. 



In the methods enumerated, the iron removed from the gal- 

 vanized plate is largely that contained in the zinc-iron alloy 

 present in the coating and is not due to corrosion of the iron 

 base. 



