Page:Memoirs of the Geological Survey of Great Britain, Volume 1.djvu/450

Rh AND OTHER CONDITIONS OF MATTER.

437

It will alfio be eTident, firom stadying these two systems of arrange- ment, that in the one case every particle disposing itself near the north pole has a tendency to attract those which are influenced by the south pole ; whereas the diamagnetic particles adjusting themselyes under the influence of north polar force, and those which are controled by the power of the other pole, have mutually a tendency to repel each other.

8. The object in view being to ascertain the influence of magnetic force in directing the order of molecular arrangement, it was neces- sary to use magnets of considerable power, and so to dispose them, and the other parts of the apparatus, that the body under experiment should be free to arrange itself in any manner obediently to the polar currents, which should have full power to act, from both poles, on the particles of matter, whilst they are held in suspension between molecular and magnetic forces. It was found most convenient to use a horse-shoe-shaped electro-magnet, so arranged that glass or metal plates could be placed upon the poles. Fig. 3 exhibits the form of my apparatus.

Fig. 3.

It consists of a bar of soft' iron, two inches in diameter and fifteen inches long, bent into a U form ; around which seven coils of copper wire are wound. For the purpose of removing the body under exa- mination as £Bur as possible from the influence of the current which circulates through the wires, when they are connected with the voltaic battery, round pieces of iron, of the same diameter as the iron of the

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