Page:Memoirs of the Geological Survey of Great Britain, Volume 1.djvu/459

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INFLUENCE OF MAGNETISM ON CKYSTALLIZATION

dency to form other magnetic curves were shown. A very remarkable quantity of crystals formed near the north pole, compared with those about the south pole ; the crystals near the north being, however, much smaller, and less perfectly defined than the others.

Fig. 9.

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30. If a very strong solution be employed, the crystals arrange them-* selves without any apparent reference to the magnetic force ; and if a solution of the same strength as the one giving crystalline curves, when the electro-magnet is connected with a strong battery, be placed on the poles when the battery current is much weaker, and consequently the magnetic force diminished, no magnetic curves will be formed by the crystals. We thus arrive at the very curious fact, that the maffTWtic force may be made to restrain the crystalline power ; or that the natural

polar forces of crystals may be too strong to be affected by magnetic in- fluence.

31. Under every circumstance yet tried, both as it regards the strength of solutions, and the power of the magnet, the crystals formed have been much more perfect than those produced in comparative experiments, which have always been made independent of the influence of the magnet.

32. The crystals of sulphate of iron, crystallizing under ordinary circumstances, unite by their faces ; but when the crystallization takes place within the influence of magnetism, they unite in a difierent manner. Sulphate of iron crystallizes in oblong rhombic prisms ; and it appears that the general tendency of these, when forming within the sphere of magnetic influence, is to arrange themselves, with regard to each other, so that the acute angle of one crystal unites with one of the faces of

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