1889.] Electro-chemical Effects on Magnetising Iron. 181 



upper terminal disks only of the magnets were exposed to the solution. 

 These holes were very accurately and carefully drilled, and when the 

 bars were forced in, the arrangement was quite fluid-tight, and the 

 greatest care was exercised to ensure that the terminal planes only of 

 the magnets were exposed to the action of the solution. The steel rods 

 were connected with a galvanometer which was introduced into the 

 circuit, and the electrolyte was then poured into the upper receptacle 

 and the readings of the galvanometer noted. A new wooden 

 stand was prepared for each experiment, and a new pair of steel 

 magnets was also employed for each observation. In many experi- 

 ments the electrolyte was first introduced to the lower ends of the 

 bars, and observations first taken of the relative electro-chemical 

 positions of the N". and S. terminals at the lower end of the magnets. 

 The solution was afterwards removed, the lower bar ends cleaned, and 

 the electrolyte subsequently placed in the upper receptacle. JBy this 

 means an indication of the relative electro- chemical position of both 

 the upper and lower polar disks of the same pair of steel magnets was 

 afforded. This series of experiments are recorded in Table F, Sets 

 I to IV, and in Table H, sets V and VI. 



In other instances either the upper or lower polar terminals only of 

 each pair of magnets were immersed in the electrolyte. The typical 

 results of a considerable number of observations made in various ways 

 in the above manner are recorded in Tables F, Gr, H, I, and J. 



Explanation of Results on Tables F, G, H, I, and J. 



The results on Table F, Sets I to IV, with cupric chloride as elec- 

 trolyte, are the averages of numerous experiments on steel magnets 

 which were tested in pairs with the electrolyte below, in apparatus 

 fig. 7, the same pairs being afterwards tested at their opposite ter- 

 minals with the electrolyte above. 



The results on Table G, Experiments Nos. 62, 57, 56, 55, 46, 43, 42, 

 and 47, with cupric chloride as electrolyte, are typical experiments 

 selected from a large number of observations too numerous to record 

 in detail. In these experiments the electrolyte was placed in the 

 position described on the table, either above or below only, with each 

 pair of magnets under observation. 



The results on Table H, Sets V and VI, with cupric sulphate as 

 electrolyte, are some typical observations selected from numerous 

 experiments, in which the steel magnets were tested in pairs with the 

 electrolyte below in apparatus fig. 7. The same pairs of magnets 

 were subsequently tested at the opposite ends with the electrolyte 

 above the magnets. The Experiments ISTos. 71, 73, 75, and 79, on this 

 table, with cupric bromide as electrolyte, were made with the solution 

 below, experiments were also made with pairs of magnets placed in 

 apparatus, fig, 7, and the results observed with the electrolyte above. 



