Experimental researches in electricity. Vol. 3 / by Michael Faraday.

  • Michael Faraday
Date:
[1855?]
Catalogue details

Licence: Public Domain Mark

Credit: Experimental researches in electricity. Vol. 3 / by Michael Faraday. Source: Wellcome Collection.

    19/612 page 7
    2164. The power of rotating the ray of light increased with the intensity of the magnetic lines of force. This general effect is very easily ascertained by the use of electro-magnets; and within such range of power as I have employed, it appears to be directly proportionate to the intensity of the magnetic force. 2165. Other bodies, besides the heavy glass, possess the same power of becoming, under the influence of magnetic force, active on light (2173.). When these bodies possess a rotative power of their own, as is the case with oil of turpentine, sugar, tai-taric acid, tartrates, &c., the effect of the magnetic force is to add to, or subtract from, their specific force, according as the natural rotation and that induced by the magnetism is right- or left-handed (2231.). 2166. I could not perceive that this power was affected by any degree of motion which I was able to communicate to the diamagnetic, whilst jointly subject to the action of the mag- netism and the light. 2167. The interposition of copper, lead, tin, silver, and other ordinary non-magnetic bodies in the course of the magnetic curves, either between the pole and the diamagnetic, or in other positions, produced no effect either in kind or degree upon the phaenomena. 2168. Iron frequently affected the results in a very consider- able degree; but it always appeared to be, either by altering the direction of the magnetic lines, or disposing within itself of tlieir force. Thus when the two conti^ary poles were on one side of the polarized ray (2150.), and the heavy glass in its best position between them and in the ray (2152.), the bringing of a large piece of iron near to the glass on the other side of the ray, caused the power of the diamagnetic to fall. This was because certain lines of magnetic force, which at first passed through the glass parallel to the ray, now crossed the glass and the ray; the iron giving two contrary poles op])osite the poles of the magnet, and thus determining a new course for a certain portion of the magnetic power, and that across the polarized ray. 2169. Or, if the iron, instead of being applied on the opposite side of the glass, were applied on the same side with the mag- net, either near it or in contact with it, then, again, the power of the diamagnetic fell, simply because the power of the magnet was diverted from it into a new direction. These effects depend
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