SECT. ii. THE AGGREGATION OF MATTER. 75 



be all compatible with and derivative from a common 

 type. The circumstances which have caused dimorphous 

 -crystals to deviate from the general law have not yet 

 been explained. 



It is very singular that when chlorate of soda is 

 dissolved in water the solution does not possess the 

 property of circular polarization, but when evaporated 

 and allowed to crystallise, some of the crystals turn 

 light to the right, and others to the left. Now if all 

 the crystals that have the same property be picked out 

 and dissolved in water a second time, the liquid will still 

 have no circular polarization, but when allowed to 

 crystallise, some of the crystals make light revolve 

 through them to the right and others to the left as 

 before. From this it is supposed that the atoms of 

 liquids, which are free to move in every direction, already 

 possess part of the characters which the change to 

 solidity renders evident and permanent. 



Although the relations between the force of magnet- 

 ism and the atoms of matter do not exhibit such brilliant 

 phenomena as light does, they are nevertheless most 

 interesting and wonderful. Mr. Faraday discovered 

 that all substances, whether solid, liquid, or aeriform, 

 are either magnetic like iron, or diamagnetic like bis- 

 muth, the latter being by far the most numerous. Thus 

 if a bar of iron be freely suspended between the poles of 

 an extremely powerful magnet or electro-magnet, it will 

 be attracted by both poles and will rest or sit axially, 

 that is, with its length between the poles or in the line 

 of magnetic force ; whereas an equal and similar bar of 

 bismuth so suspended will be repelled by both poles and 

 will rest or sit equatorially, that is with its length per- 

 pendicular to the line of magnetic force. Magnetism 

 and diamagnetism are both dual forces, but they are 

 in complete antithesis to one another, which is strikingly 

 illustrated by their action on crystalline matter. 



