Action of 



a Magnet on 



Chemical Action. 109 



Substances. 



Effect due to 

 magnet. 



Notes. 



Nitric acid 



Strong. 

 Little or none. 



None. 

 >> 

 ■> 



Some effect. 



None. 



Slight'effect. 

 Decided effect. 



Some. 



Slight. 



Some. 



•j 



Decided. 



Some. 



Always powerful protective throw. 

 Does not act very readily on the iron. 



Sometimes quite distinct throw, 



irregular. 

 Much less marked than with chromic. 



Hardly any effect on iron. 

 More than with perchloric. 



Mainly showing as throw, on 

 breaking. 



»> t> i> 

 >> 11 «> 



J5 >> » 



Throw, on breaking. 

 Very slight solution, weak. 

 Mainly as throw on breaking. 

 Both protective throw, and some- 

 times on breaking. 

 Action very irregular. 

 >> >j 



Sulphuric acid 



Hydrochloric acid 



Formic ,, 



Oxalic ., 



Tartaric ,, 



Chromic ,, 



Perchloric ,, 



Chloric ., 



Bromic ,, 



Phosphoric ,, 



Permanganic ,, 



Chlorine water 



Bromine ,, 



Iodine ,, 



Copper sulphate 



„ nitrate 



,, acetate 



„ chloride 



Mercuric bromide 



,, chloride 



Mercurous nitrate 



Ferric chloride 



Silver nitrate 



Platinum tetrachloride . 



From these experiments it was quite evident that the 

 protective action, whatever its cause, was more general than 

 at first appeared, and steps were next taken to extend it to 

 the other magnetic metals. Small bars were made of nickel 

 and cobalt, and tried in the same manner as before. These 

 metals are acted on but very slightly by most acids, and the 

 range of substances which could be used was therefore very 

 small, but all the substances which gave the magnetic effect 

 with iron poles gave a precisely similar, though much smaller 

 effect, whenever they were capable of acting at all on the 

 nickel and cobalt. This was notably the case with nitric acid, 

 bromine water, chlorine water, and platinum tetrachloride, 

 which were the substances acting most readily on the metals 

 in question. Even with these powerful agents, however, the 

 magnetic action was very much less than with iron, and 

 experimentation on metals even more weakly magnetic was 

 evidently hopeless. 



As a preliminary step towards ascertaining the cause of 

 the magnetic action, and its nonappearance where the active 



