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104

Jany 2nd 1844

Observed to day a fact in reference to the drop of water on a hot iron which is some importance. A quantity of water was thrown on the top plate of an air tight sheet iron stove, a considerable sized dopule of this remained for several minutes in motion on the top of the iron. When the eye was brought down so as to be on the opposite side of the drop from a window, the light could be seen between the underside of the drop, the water was not in contact with the iron, but when the metal was so much cooled as to produce the explosive production of steam, the drop  was seen at the moment of hissing to touch the metal.
Jany 18th   Repeated to day Dr. Faraday's exp given in the Philosophical magazine, vol 22 200p, on the induction through different vessels. [[image]] A large was kettle was placed on a cake of bees wax, and the out side of it was connected with an electrometer with gold leaves. A ball b was then let down into the kettle by means of a fine silk thread. The leaves instantly diverged and remained at the same angle, what ever position the ball b occupied within the kettle. It also remained the same agreeably to the account given by Dr Faraday when the ball was touched to the inside of the vessel.
 This experiment appears to me to be in strict accordance with the mathematical theory of elect. that the induction should be the same in total amount at what ever distance the surface of the circumscribing sphere is from the balls, is a consequence of the repulsion being inversely as the square of the distance, and the fact that the surface of the ball increases as the square of the same distance.
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Jany 18th 1844    105
I was enabled to make some variations in the experiment which is also in accordance with, and was suggested by this theory . When the outside of the globe, or rather bottle, was touched while the ball was inside, the leaves collapsed, because the unsaturated matter in the surface just balanced by its attraction the repulsion of the electricity in the ball. The condition [[image]] of the whole is shown by the figure in the margin. When the ball was withdrawn, the leaves then diverged with - elect! This effect was owing to the repulsion of the ball being withdrawn, and then the unsaturated matter of the globe drew into itself, the electricity of the electrometer and the leaves consequently diverged with negative electricity.
[[image]] I next next removed the knob and inner wire of a jar, charged the same plus intensely, then insulated it on a cake of wax, touched the outside, then let down into the interior a carrying ball, but no signs of electricity could be perceived, neither side was in excess.
The larger dimentions of the outer coating just made up for the thickness of the glass, so that in the arrangement of a jar without a knob, there is no excess of elect., and hence it would seem to follow that with the same amount of internal surface of coating, the same charge can be given to a jar without a knob whatever be its thickness.
The globular form of a jar enables it to retain its electricity much better, but also to receive a greater charge. Dr. Robeson has some remarks on this point, Mechanical Phil., vol 4, page 131, also some remarks on the lateral explosion may be found at page 172 of the same.