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another. The electric, or galvanic, and the magnetic princi- 

 ples were inseparable, the characteristic difference being that 

 V they flowed (considering them as currents) in directions at 

 right angles to each other. In the neutral state in which 

 they generally were, very few substances in nature exhibited 

 magnetic influences. A piece of glass had the magnetic 

 principle residing in it the same as iron, but it did not exhibit 

 the magnetism, nor would the proximity of a magnet excite 

 or develope it ; it was invisible to any test whatever. If 

 they took a piece of brass in the same way, under ordinary 

 circumstances, they could not produce any magnetic change 

 in it, unless they brought it within £he circuit of the galvanic 

 apparatus, or exposed it to the action of heat or chemical 

 change; Thus in the brass, the magnetic influences that are 

 there can be developed ; at the same time, when it is separate 

 from such action, it exhibits no magnetic property whatever. 

 There was one substance, however, which did, as every one 

 knew, exhibit this property in a very striking manner and 

 degree. A piece of iron was capable, by mere proximity to 

 a magnet, and still more so by contact, to exhibit very power- 

 ful magnetic phenomena. This was the case in different 

 degrees with all ferruginous substances, whether in ore or in 

 a metallic state, as malleable or cast iron, or steel. What- 

 ever was the nature of the combination of iron, it generally 

 had some capability of exhibiting magnetic phenomena, — 

 There were other substances, not ferruginous, which had the 

 same properties, but in so slight a degree that it was not 

 necessary now to consider them. It perhaps might be well 

 at that stage to show the nature of the development of the 

 magnetic property in iron ; because that matter would bear 

 immediately on the subject that he wished to illustrate. He 

 had there a piece of iron (holding a small bar in his hand), 

 and if he brought it into proximity with the powerful magnet 

 before him, not close, but even at the distance of two or 



