IfAGXETISM. 



'uminished, ox 1 ami controlled at 



pleasure, by tin; operator. 



We will examine the affltngementy and observe the effects anil 

 causes of the.*; changes. 



mi :i battery, the ends of two pieces of metal an; placed 

 iu diluted acid, and by chemin! ;i<'iin they are gradually dis- 

 solved. In this position they have no other magnetic force 

 than the* power of dissolving. Each piece has however two 

 poles, the poles in the acid being similar, and those in the 

 air beiiii; also alike. If the dry ends be brought into contact* 

 the action of the ends in the solution is seen to increase ; this is- 

 owing to the two pieces now forming one magnet with two 

 poles, in place of four. The two poles lost at the point of 

 contact, now merge their influence into the whole, and the polea 

 in the solution become dissimilar opposite poles (as explained 

 before) then reciprocate, or attract one another, and thus we 

 have the increase of the dissolving power exhibited, and an 

 increase of force developed. 



If the junction of the two metals be made by a long con- 

 necting wire, instead of close contact, the same action is 

 continued between the poles or ends in solution. No more 

 force is shown in the connecting wire, than in the middle of 

 the magnet, because the force can by i{ nature, only be 

 developed or exhibited at the ends or poles. If however we 

 tin; wire or its connection at any part, the action is 

 immediately checked at the ends, because they arc now as 

 before, two magnets and four p.l"s ; the poles in the solution 

 being of courSe similar. Baing the separated ends slightly into 

 contact, and the result is the electric spark ; for as we have 

 explained before, those ends act as opposing poles, and attract 



