Effects due to Magnetization. 475 



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 liquids. When one electrode was magnetized, a cur- 

 rent was obtained going in the liquid from the magnetized 

 electrode to the non-magnetized electrode. 



It thus appears that there is at least an apparent incon- 

 sistency between the protective results of Professor Rowland 

 and Professor Remsen, and those of Nichols, Andrews, Gross, 

 and others, who find the more strongly magnetized parts of iron 

 electrodes more easily attacked than the neutral parts ; and it 

 was with the object of endeavouring to reconcile these results, 

 and of studying the exact nature of the influence exerted by 

 the magnet, that the experiments recorded in this paper were 

 undertaken. 



Apparatus and Method of Investigation. 



The method of investigation was that adopted by Professor 

 Rowland in his previous work on the subject, since its facility 

 and delicacy permitted the effects of the magnet to be 

 observed whenever there was the slightest action on the 

 electrodes by the solution examined, and the investigation 

 could thus be carried over a wide range of material. 



A large electromagnet was employed to furnish the mag- 

 netic field, and, at a distance sufficient to prevent any direct 

 influence due to the magnet, a delicate galvanometer of the 

 Rowland type was set up. Small cells were made with iron 

 electrodes of special forms, coated with sealing-wax except at 

 certain parts, and immersed in a liquid capable of acting 

 chemically on iron. The whole was contained in a 50 cubic 

 centim. glass beaker, and when joined to the connecting wires 

 of the distant galvanometer was firmly clamped between the 

 poles of the electromagnet. 



In the course of the examination of a number of substances 

 it was found necessary to use two galvanometers — one 

 specially made by the University instrument-maker and very 

 sensitive, which was employed with acids which evolve hydro- 

 gen; the other, much less sensitive, was best suited to the 

 violent " throws" with nitric acid and iron. The samples of 

 iron used throughout the experiments were obtained from 



* " Ueber eine neue Entstehungsweise galvaiiisclier Strome durch 

 Magnetismus," Sitzungsberickte der Wiener Akademie, 1885, vol. xcii. 

 (1885) p. 1373. 



2L2 



