444 G. 0. Squier — Electro- Chemical 



Messrs. Nichols and Franklin* were the next to conduct 

 experiments bearing on this subject. They found that finely 

 divided iron, which has become " passive " through the action 

 of strong nitric acid, suddenly regains its activity when intro- 

 duced in a magnetic field, and also that when one of the two 

 electrodes immersed in any liquid capable of chemically act- 

 ing upon them, is placed in a magnetic field, a new difference 

 of potential is developed between them due to this magnetiza- 

 tion. They ascribe these effects to electric currents in the 

 liquid produced indirectly by the magnet, which currents go 

 in the liquid from the magnetized to the neutral electrode. 



Professor Rowland and Dr. Louis Bellf were the first to 

 note the " protective action " of points and ends of magnetic 

 electrodes, and to give the exact mathematical theory of this 

 action. Their results were directly opposite to those of Messrs. 

 Nichols and Franklin, who found, as stated above, that points 

 and ends of bars in a magnetic field acted like zincs to the 

 other portions, or were more easily dissolved by the liquid. 



The method of experiment adopted by Professor Rowland 

 was to expose portions of bars of the magnetic metals placed 

 in a magnetic field to reagents which would act upon them 

 chemically, and study the changes in the electro-chemical 

 nature of the exposed parts by fluctuations in a delicate galva- 

 nometer connected with the two bars. Iron, nickel, and 

 cobalt were experimented upon and nearly thirty reagents 

 were examined in this manner. The results are summed up 

 in the following statement : " When the magnetic metals are 

 exposed to chemical action in a magnetic field, such action is 

 decreased or arrested at any points where the rate of variation 

 of the square of the magnetic force tends towards a maxi- 

 mum." 



Other investigations in this field are those of Andrews,;}: 

 who employed iron and steel bars from eight to ten inches 

 long with their ends immersed in various solutions, and one 

 bar magnetized by means of a solenoid. The protective 

 action was not noted, but, on the contrary, the magnetized 

 bars acted as zincs to the neutral bars, thus indicating that 

 they were more easily attacked. 



Practically the same results were obtained by Dr. Theodor 

 Gross ;§ soft iron wires 8 cm long, and 3 cm in diameter coated 

 with sealing wax, except at the ends, were exposed to various 



* This Journal, xxxi, 272, xxxiv, 419, xxxv, 290. 



f Philosophical Magazine, xxvi, 105. 



^Proceedings of the Royal Society, No. 44, pp. 152-168, and No. 46, pp. 176- 

 193. 



§ Ueber eine neue Entstehungsweise galvanischer Strome durch Magnetismus, 

 — Sitzungsberichte der Wiener Akademie, 1885, vol. xcii, '85, p. 1373. 



