Page:Memoirs of the Geological Survey of Great Britain, Volume 1.djvu/456

Rh AND OTHER CONDITIONS OF MATTER. 443

from the centre, at first in straight lines, but which are gradually bent into the forms represented in the figure. The exposure of the fluid containing the iron salt for some hours to the action of the air, naturally gives rise to the formation of some oxide of iron. This is gradually deposited in circles around the poles, covering the curves of silver, and, indeed, by involving the particles as they are precipitated, carrying them down widi them ; thus preventing the formation of any curves of repul- sion. It is exceedingly interesting to observe the progress of the true magnetic action, preventing any further development of the diamagnetic power, and at length so tar overcoming it as to force the metal (silver), which is powerfully repellent to magnetic influence under natural cir- cumstances, into obedience to magnetic energy. Other cases will be mentioned in which similar antagonistic powers were observable.

17. A solution of sulphate of copper being put on the plate, small glass tubes filled with a solution of caustic potash were fixed over the centre of the poles of the magnet The oxide of copper radiates in straight lines from around the tube, with scarcely any tendency to bend at all except where those lines, .springmg from the one pole, approach those thrown off from the other. A very decided reptdsion then takes place, a line is protected from the deposit of any of the oxide, and the radiations are all bent back.

18. Muriate of tin was employed in the same manner as the cupreous salt The oxide of tin, formed by the action of the alkali, had a ten- dency to arrange itself in the curves of repulsion, but this was at all times exceedingly weak, and in several experiments it was impossible to detect any regular arrangement. When we employ great battery power and very dilute solutions, the curves are more manifest On breaking connexion with the battery, they are immediately destroyed ; and if we alter the direction of the current, the curves bend in the reverse direction.

19. These curves of the oxide of tin show, in a v^y striking manner, a remarkable pulsating action during their formation, as if the oxide of tin was thrown off by a series of waves flowing from the magnetic poles. These waves are very uniform, and possibly arise fit)m the exertion of the two forces in opiporition to each other : the movement being depen- dent on the impulse given to the accumulating diamagnetic mass by the concentrated action of the checked power of the electro-magnet as it overpowers the antagonist force. I have observed the same waves, or fits of action, with permanent steel magnets.

20. Iodide of tin exhibited nearly the same phenomena as the oxide.

21. Purple of cassius^ which was formed by filling tubes with chloride of gold, and inverting them in a solution of muriate of tin, presented

2 G 2

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