UNIVERSALITY OF MAGNETISM. 253 



bodies in different ways : one set acting with relation to 

 magnetism, like iron, and arranging themselves along 

 the line of magnetic force, these are called magnetic 

 bodies ; another set, of which bismuth may be taken as 

 the representative, always placing themselves at right 

 angles to this line, these are called diamagnetic 

 bodies.* This is strikingly shown by means of powerful 

 electro-magnets; but the magnetism of the earth is 

 sufficient, under proper care, to exhibit the phenomena. 

 Every substance in nature is in one or other of these 

 conditions. The rocks, forming the crust of the earth,, 

 and the minerals which are discovered in them; the 

 surface soil, which is by nature prepared as the fitting 

 habitation of the vegetable world, and every tree, shrub, 

 and herb which finds root therein, with their carbona- 

 ceous matter, in all its states of wood, leaf, flower, and 

 fruit; the animal kingdom, from the lowest monad 



* Those bodies which are attracted by a magnet, as iron is, are 

 called magnetic bodies. Those which are, on the contrary, repelled 

 by the same power, are termed diamagnetic bodies. On these Dr. 

 Faraday remarks: "Of the substances which compose the crust 

 of the earth, by far the greater portion belong to the diamagnetic 

 class ; and though ferruginous and other magnetic matters, being 

 more energetic in their action, are more striking in their pheno- 

 mena, we should be hasty in assuming that, therefore, they over 

 rule entirely the effect of the former bodies. As regards the ocean, 

 lakes, rivers, and the atmosphere, they will exert their peculiar 

 effect almost uninfluenced by any magnetic matter in them, and 

 as respects the rocks and mountains, their diamagnetic influence 

 is perhaps greater than might be anticipated. I mentioned that 

 by adjusting water and a salt of iron together, I obtained a solution 

 inactive in air ; that is, by a due association of the forces of a body, 

 from each class, water and a salt of iron, the magnetic force of the 

 latter was entirely counteracted by the diamagnetic force of the 

 former, and the mixture was neither attracted nor repelled: To 

 produce this effect, it required that more than 48'6 grains of crys- 

 tallised protosulphate of iron should be added to ten cubic inc>>es 

 of water (for these proportions gave a solution which would set 

 equatorially), a quantity so large, that I was greatly astonished on 

 observing the power of the water to overcome it. It is not, there- 



