抄録
Summarizing the previous researches the author concluded the eight experimental facts as established, two of them are the reaults of the other investigators and six are due to himself. Various theories ever proposed were criticized by these eight facts and all found to be unable to explain them. These theories included (1) Hydrolysis theory (2) Affinity and cohesion theory (3) Solute catalysis theory (4) Solubility of Mg(OH)2 theory (5) Breaking of the surface protecting film theory. Local current theory was also considered but found to be incorrect. A dual theory finally put forward by the author contains the following two fundamental chemical reactions
The existence of the surface film and its breakdown by Cl- ion are also believed. Besides, he assumed an intermediate compound with its catalitic action. By this theory he could explain the above facts satisfactorily.
