Magnetism Ofi Chemical Action. 255 



following one, mentioned by Dr. Faraday in his Experimental 

 Researches, 1st series, par. 20. 



" When a small voltaic arrangement was introduced into 

 the circuit between the galvanometer and its helix or wire so 

 as to cause a permanent deflection of 30° or 40°, and then the 

 battery of one hundred pairs of plates connected with tiie in- 

 ducing wire, there was an instantaneous action as before ; but 

 the galvanometer-needle immediately resumed and retained its 

 place unaltered, notwithstanding the continued contact of the 

 inducing wire with the trough : such was the case in which- 

 ever way the contacts were made." 



The direction of the current through the helix was altered, 

 so that sometimes the north pole was in tlie solution and some- 

 times the south pole; but no difference was observed upon 

 the galvanometer-needle. 



Bunsen's battery was the one emjiloyed, and from one to 

 six pairs were used ; but the increased power did not make 

 the slightest difference. In every experiment the iron wire 

 was changed ; for it was found that it became, when magnet- 

 ized thus, being at the same time under the influence of che- 

 mical excitement, more permanently polar than electro-mag- 

 nets do ordinarily. 



When two iron wires were employed, one of them was 

 almost invariably found to be positive to the other when they 

 were first plunged into the dilute acid; but after some short 

 time they were more equally influenced: and although the 

 deflection may at first have been 20° or 30°, yet the galvano- 

 meter-needle slowly returned to zero, or at most indicated only 

 a deflection of 2" or 3°. It certainly was expected that mag- 

 netism would render one wire positive to the other in a much 

 more decided manner ; but no such effect could be detected 

 in any one of a great number of experiments; the transient 

 tremor being the only influence observed upon the needle 

 when the helix was connected with the battery or disconnected 

 from it. 



It was thought possible, and indeed some previous experi- 

 ments with permanent magnets led me to the conclusion, tiiat 

 two magnets of ecjual power being placed in the solution, one 

 with its north polo and the other with its south pole immersed, 

 would give some indication of a current, arising from a difler- 

 ence in the chemical action upon them. With this view two 

 helices were jireparcd, and arranged in the vessel D so that 

 both of liie iron wires a b could be rendered magnetic at the 

 bame time. Not any indication could be obtained with the 

 galvanouR'ter, nor could any deflection be observed even when 

 liie electro-magnetic influence was considerably diflercnt upon 

 tlie two wires. 



