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[[top of page]] 10 Oct 14th 1839

Thought of a new way of exhibiting the screening influence--placed coil no 1 in connection with the battery and between this and helix no 1 placed coil no 2 & 3 joined together first, so that the induced current from the lower coil would go in the same direction with that in the upper one, now the shock from the hilex was very severe--next turned the lower coil of the two middle ones over so that the current by induction would be sent in an opposite direction through the other from the first with this arrangement the effect was nothing ^[[scarcely?]] the shocks were only just perceptible.

I have several times thought that the zinc plate used in the experiments performed better than the lead plates, and this I have proved by exp. At first I was disposed to attribute the effect to the difference of action in the metals but I have just thought that the difference might be due to the greater surface of the zinc plate, it being of about twice the area of the lead plates. To settle this the helix [[no 1 inserted above text]] was placed over coil no 1 attached to the battery and the [[end page]]
[[start page]] 11
Oct 14 & 15th 1839

zinc plate placed between them. When the middle of the plate connected with the axes of the two coils, the shock could not be felt or very slightly, but where the plate was placed so that its edge was projected scarcely at all beyond the edge of the helix, the shock was very considerable. This exp is important it appears to me in reference to the production of secondary currents from ordinary magnetism

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[[margin - left]]Exp 1[[/margin]]
Inspected a piece of lead through which mercury had passed, found the amalgamation principally on the outer part--a cone of pure lead was left in the axis ^[[of]] about the 20 of an inchch in diameter.

Inspected a piece of copper, which was placed in a solution of nitric acid with sulphuric and mercury. The mercury after three days has penetrated the copper so as to render it soft and very brittle, its tenacity is almost entirely destroyed and the plate (the copper is of this form) appears somewhat increased in thickness. The copper remained in the acid one night and when taken out, it was only coated with mercury, but not penetrated by, and retained its original toughness, but by lying on the table since then it has assumed its present state of brittleness. In the same solution
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