Action of a Magnet on Chemical Action. 113 



the question of direct protection of the poles, have furnished 

 additional proof of the purely mechanical action of the magnet 

 by reproducing some of the characteristic phenomena where 

 chemical action was eliminated and the only forces acting 

 were the ordinary magnetic attractions. 



An attempt was made to reverse the magnetic action, i. e. 

 to deposit iron in a magnetic field and increase its deposition 

 where there was a sharp pole immediately hehind the plate on 

 which the iron was being deposited. This attempt failed. 

 The action was very irregular and the results not decisive. 

 The question of stirring-effect was also examined. Usually 

 stirring the liquid about one pole increased the action on that 

 pole, but sometimes produced little effect or even decreased it. 

 This, however, is in entire agreement with the irregular action 

 sometimes observed in the case of the after-effect in the original 

 experiments. 



An excellent method of experiment is to imbed an iron 

 point in wax leaving the minute point exposed : imbed a flat 

 plate alsoun wax and expose a point in its centre. Place the 

 point opposite to the plate, but not too near, and place in the 

 liquid between the poles of a magnet and attach to the galva- 

 nometer as before. 



There is a wide field for experiment in the direction indicated 

 above, for it is certainly very curious that the effect varies so 

 much. If hydrogen were as magnetic as iron, of course acids 

 which liberated it would have no action. But it -is useless to 

 theorize blindly without further experiment, and we are drawn 

 off by other fields of research. 



In the ' American Journal of Science ' for 1886, p. 372, 

 Professor E. L. Nichols has investigated the action of acids on 

 iron in a magnetic field. He remarks that the solution of iron 

 in a magnetic field is the same as removing it to an infinite 

 distance, and hence the amount of heat generated by the 

 reaction should differ when this takes place within or without 

 the magnetic field. Had he calculated this amount of heat 

 due to the work of withdrawing it from the field, he would 

 probably have found his method of experiment entirely too 

 rough to show the difference, for it must be very small. He 

 has not given the data, however, for us to make the calculation. 

 The results of the experiments were very inconclusive as to 

 whether there was greater or less heat generated in the field than 

 without. 



In the same Journal, for December 1887, he describes ex- 

 periments on the action of the magnet on the passive state of 

 iron in the magnetic field. In a note to this paper, and in 

 another paper in the 'American Journal of Science ' for April 



Phil. Mar,. S. 5. Vol. 26. No. 151). August 1888. I 



