Chap. 6.] Force of Magnetic Attr&fti on. 37 



One magnet attracts another magnet in contact^ 

 with lefs force than it attracts iron ; but the attraction 

 between them begins at a much greater diftance than 

 between the magnet and iron alone. 



As iron is diffufed in greater or lefs quantities 

 through almoft all the different bodies of which the 

 univerle is compofed, it is eafy to fuppofe that the 

 natural bodies which are fubject to the magnetic at- 

 traction are very numerous. The perfect metals, 

 gold, fiiver, and platina, as well as lead and tin, are 

 however total exceptions j though their calces are a 

 lit le attra6ted. Animal and vegetable fubftances alfo, 

 though they are known to contain fmall portions of 

 iron, feldom exhibit any difpofition to be attracted 

 before combuftion * j though it is afierted that moft 

 fubftances may be rendered magnetic in fome degree 

 by being expofed to the action of fire. 



Iron is attracted with different degrees of force, 

 according to the different modes in which it exifls, 

 It is, however, in no ftate quite infenfible to the 

 magnetic power, even in the pureft calx, or in a 

 ftate of folution. Soft iron is the moft fubject to a 

 forcible attraction ; fteel is lefs fo than iron, efpecially 

 when hardened, and the calces of iron in different 

 degrees f- 



Mufchenbrock, by a feries of experiments, endea- 

 voured to afcertain the force with which the mag- 

 net attracts at different diftances. vHe fufpended a 

 cylindrical magnet, 2 inches long and 16 drams in 

 weight, to one fcale of an accurate balance, and under 

 it he placed a cylinder of iron of the fame ihape and 

 bulk. The following is the force with which it at- 

 tracted at different diftances, eftimated by the number 

 of grains in the oppofite fcale. 



* Cav. on Mag. f Ibid. 



D 3 At 



