three inches, it would become magnetic, and able, as they 

 observed, to sustain a large key weighing 2,300 grains. 

 They saw the effect produced by this action of the magnet, 

 but now [removing the iron away from the magnet, and 

 applying the key again,] there was no magnetism on it, and 

 it was just as indifferent to the key as before. This was not 

 by reason of actual transmission of anything from the magnet, 

 that the iron became magnetic — not by reason of anything 

 put into it that it did not contain before ; but it was the 

 development of latent or neutral principles — as might be 

 illustrated by reference to the case of a smith who took a 

 cold piece of iron, and with skill could beat it until it was red 

 hot, as was frequently done, and so that he could light his fire 

 with it. In this case, the blacksmith did not put into the iron 

 any heat that was not there previously, because his anvil and 

 his hammer were cold ; he merely developed by the peculiar 

 condensation of the substance of the iron a certain quality of 

 the iron which had previously been latent in it. So, applying 

 this illustration to the magnetic question, this analogy was 

 found — they did not put anything into the iron, they only 

 called forth the latent or neutral principle within it. This 

 was one condition that referred to the object he had in view, 

 and which bore on the method of determining the qualities 

 of iron, as they would see in a short time. He might now 

 enunciate another fundamental principle in his processes for 

 determining the quality of iron — that whereas ferruginous 

 substances generally were capable of the magnetic condition, 

 those most perfectly ferruginous, or of the purest iron, were 

 capable of the highest development of magnetic condition. 

 If he brought a piece of cast iron to the magnet, it would be 

 found that it exhibited the magnetic character in a much 

 inferior degree to that which malleable iron did. He might 

 show that a piece of steel would exhibit it, by mere contact, 

 in a slighter degree than iron. [Dr. Scoresby took a piece 



