On the Colour and Magnetic Properties of Bodies. 45 



that the electrified state of the dry paper surface had much influence 

 in producing these movements, and that when this was guarded 

 against, the number of bodies furnishing particles to be moved on 

 silver by a magnet underneath, became much reduced. With the 

 silver cold, they were confined to the numerous compounds of the 

 three magnetic metals, iron, nickel, and cobalt ; but when the silver 

 was heated, the number of such bodies began to increase. In the 

 experiments in my first communication, where I used the magnet 

 under a sheet of dry paper, the white and dark coloured products 

 were tried under similar conditions ; so that although the magnetic 

 effect was mixed up with an electrical action, the results are not 

 thereby invalidated ; and at the time I kept checking them continu- 

 ally, by submitting each substance in its dark and light coloured 

 state to a comparative trial on the torsion balance, where the dark 

 coloured one shewed most magnetic attraction. But in writing out 

 an account of these experiments, I preferred, wherever I could, to 

 give the paper test, as it appeared to me to be a more palpable 

 proof than the other, and to admit of more easy repetition. 



To continue the evidence that shews that magnetic bodies form a 

 larger proportion of dark coloured compounds than diamagnetic ones, 

 I selected from Dr Turner's chemistry a list of the oxides of the 

 elementary bodies I had examined for their magnetism on the torsion 

 balance, which supply the following numbers : — 



Substances Attracted by the Magnet. Substances Repelled by the Magnet. 



Transparent Coloured Transparent Coloured 



or white oxides. oxides. or white oxides. oxides. 



37 



18 



In classifying these oxides I have referred to the anhydrous form, 

 excepting in a few cases where this has not been insulated, for there 

 the hydrated oxide is classified. From Gmelin's chemistry I se- 

 lected the compounds of metals arranged in three different groups—— 

 the first magnetic metals ; the second, metals of feeble magnetism in 



