192 Electro-chemical Effects on Magnetising Iron. [June 6. 



Table I, with cupric sulphate as electrolyte. In these experiments 

 Nos. 81, 84, 85, 86, 87, 88, 90 and 91, each pair of magnets was only 

 tested with electrolyte below. 



On Table J, in Experiments Nos. 92, 94, 95, and 96, with a solution 

 of potassium bichromate and nitric acid as electrolyte, each pair of 

 magnets was only tested with the electrolyte below. The Experi- 

 ment No. 100, with a solution containing nitric acid, potassium bi- 

 chromate, and ferric chloride as electrolyte, was made in apparatus 

 fig. 7, with the electrolyte below. In the experiments, Set VII, 

 with sulphate of iron and nitric acid, the magnets were tested first 

 in apparatus fig. 7, with the electrolyte below, and subsequently the 

 opposite ends were tested with the electrolyte above. 



The diameter of the magnets in these experiments was about 

 0-300 inch. 



In course of the investigations it was frequently noticed that an 

 instantaneous fling of the galvanometer occurred on first immersing the 

 bars in the electrolyte, the fling showing the S. polar terminal to be 

 positive at the moment of commencing the experiment ; this instan- 

 taneous fling of the galvanometer very rapidly subsided, and the sub- 

 sequent readings showed a continuously steady positive position for 

 the N. pole. (See results on the Tables.) It will also be generally 

 noticed that the E.M.F. steadily increased from the commencement of 

 an experiment, when the electrolyte was placed either above or below 

 the magnets, the polar influence appearing gradually and increasingly 

 to affect the action taking place. An examination of the results of 

 the total observations, on the steel magnets, in Table F, in which the 

 electrolyte (cupric chloride solution) was placed below the magnets, 

 gave an average E.M.F. of 0*014 volt; whereas the observations 

 made with the electrolyte above the magnets yielded an average 

 E.M.F. of 0-011 volt. The further experiments in Tables G and H 

 are also confirmatory of this difference in the extent of E.M.F. 



These general results seem, therefore, to indicate that the positivity 

 of the upper IS", polar terminal was reduced relatively to some extent 

 when the electrolyte was placed above the magnets as in fig. 7, and 

 this circumstance may possibly be owing to the action of the upper 

 N. pole having been comparatively weakened by the influence of the 

 earth's magnetism, as suggested by Professor Stokes. This difference, 

 ascertained from the results of such a considerable number of obser- 

 vations, in the extent of the E.M.F., may perhaps thus be accounted 

 for. It will be seen that the united results obtained with both the 

 arrangements of fig. 7 lead to the tentative conclusion that thera 

 was a general tendency, under the conditions of experimentation, on 

 the part of the N. magnetic terminal of the steel magnets, to assume 

 electro-chemically the positive position compared with the S. terminal, 

 when these constituted elements in certain electrolytes. The result 



