214 Richard Adie, Esq., on the Connection between the 



shewn to contain magnetic particles. A similar decomposition of 

 the acetate of zinc probably gi^es some mixture of a carburet with 

 the oxide of the metal, which produces the high magnetic character 

 of some of the darker particles. Again, in the three metals, mer- 

 cury, silver, and tin, nearly allied to cadmium in colour, there is no 

 evidence of motion on paper to a magnet to be obtained from their 

 oxides or sulphurets until these have been fused, and more or less 

 ignited with citric acid. The oxide of silver, though easily partially 

 reduced by heat, will not, by such treatment, give the required par- 

 ticles — for them the black sulphuret must be ignited with citric 

 acid when the residue contains a few that move feebly to a magnet. 

 Oxides and sulphurets of tin and mercury likewise furnish, when 

 heated with citric acid, particles that move to a magnet, but only 

 very feebly, and these two metals are in every respect inferior to the 

 three diamagnetic ones for yielding magnetic products. 



Platina. — The brown bichloride of this metal has a feeble 

 attraction for the magnet on the torsion balance ; decomposing it by 

 heat alone, I did not succeed in getting a product that would move 

 on paper ; but, as in the case of silver and mercury, by adding a 

 vegetable acid, and reducing the mixture at a moderate heat, a 

 dark-grey powder was left, of which some of the particles moved to 

 a magnet.* 



Gold supplies a very pretty illustration of the connection of the 

 colour with the magnetic properties of bodies. The cyanide, a fine 

 canary-coloured powder, is quite magnetic by the torsion balance 

 test, but immoveable to a magnet on paper ; by a gentle heat, the 

 cyanogen is exchanged for oxygen, the powder assumes a dark- 

 brown colour, which moves on paper to a magnet ; by further 

 heating, the oxygen is expelled, and pure gold remains. 



Cobalt. — The ruby-red crystals of the sulphate of this metal have 

 not sufficient magnetism to move on paper when spread out in a 

 pulverised state ; by heat, they are converted into the black oxide, 

 which is more acted on by the magnet than any of the metals or 

 their compounds described, save those of iron and nickel. This 

 oxide, heated in a tube through which a current of hydrogen is 

 passed, is reduced to the pyrophoric cobalt, a pure black body very 

 nearly equal to nickel, prepared in a similar manner, in the extent 

 of the motion of its particles before a magnet. 



I may now pause to note, in the foregoing experiments, a result 

 which they have made apparent, and which I did not anticipate at 

 their commencement ; it is, that all the heavy metals in everyday 



* When the number of particles moveable to a magnet form a very small 

 proportion of the whole body, it may eventually prove that this effect is con- 

 nected with the presence of some foreign matter ; but where I suspected this, 

 I used a spirit-lamp flame to reduce the oxide, and I have not yet been able to 

 shew the motion to be due to the presence of iron. 



