Action of a Magnet on Chemical Action. 107 



temporary deflection, the time varying from this down to a 

 few seconds. The throw was independent of direction of 

 current through the magnet, and apparently varied in amount 

 with the strength of acid and with the amount of deflection 

 due to the original difference between the poles. This latter 

 tact simply means that the effect produced by the magnet is 

 more noticeable as the action on the iron becomes freer. 



When a pair of little plates exposed in the middle were sub- 

 stituted for the wires, or when the exposed point of the latter 

 was filed to a flat surface, the protective throw disappeared, 

 though it is to be noted that the deflection often gradually 

 reversed in direction when the current was sent through the 

 magnet ; i. e. only the latter part of the previous phenomenon 

 appeared under these circumstances. 



When the poles, instead of being placed in the field along 

 the lines of force, were held firmly perpendicular to them, the 

 protective throw disappeared completely, though as before 

 there was a slight reverse after-effect, 



Some of Prof. Remsen's experiments on the corrosion 

 of a wire in strong nitric acid were repeated with the same 

 results as he obtained, viz. the wire was eaten away to the 

 general dumbbell form, though the protected ends instead 

 of being club-shaped had the ends perceptibly hollowed. 

 When the wire thus exposed was filed to a sharp point the 

 extreme point was very perfectly protected, while there 

 was a slight tendency to hollow the sides of the cone, and the 

 remainder of the wire was as in the previous experiments. 

 In both cases the bars were steel and showed near the ends 

 curious corrugations, the metal being left here and there in 

 sharp ridges and points. In one case the cylinder was eaten 

 away on sides and ends, so that a ridge of almost knife-like 

 sharpness was left projecting from the periphery of the ends. 



These were the principal phenomena observed with nitric 

 acid. {Since this acid is the only one which attacks iron freely 

 in the cold, in Prof. Remsen's investigations this was the one to 

 which experiments were in the main confined. With the 

 present method, however, it was possible to trace the effect of 

 the magnet whenever there was the slightest action on the iron, 

 and consequently a large number of substances, some of which 

 hardly produce any action, could be used with not a little 

 facility. 



In thus extending the experiments some difficulties had to 

 be encountered. In many cases the action on the iron was so 

 irregular that it was only after numerous experiments under 

 widely varying conditions that the effect of the magnet could 

 be definitely determined. Frequently the direction of the 



