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[[start page]] 44 Thursday 11th May 1843
Procured this morning a transparent solution of acetate of lead. The acetate is often of a milky colour but it may be rendered transparent by the addition of a small quantity of the pure acetate acid. This salt of lead like the other salts of the same metal which I have tried is nearly impervious to the phosphorogenc eminations.

[[note in left margin beside this paragraph]] * [[/note in left margin]] Next tried  a plate of transparent camphor, found this nearly as impervious as mica. More impervious than glass indeed I am  not sure but that it is to be classed with mica.

The plate of camphor was next submitted to the influence of the chemical examination, over a sensible plate in connection the acetate of lead and a plate of common glass. The [[strikeout]]whole [[/strikeout]] plate under each became blackened  without any apparent difference.
[[underlined]] the time of exposure was 10 seconds [[/underlined]]
Next tried the transmissability of camphoretted water :  found this about as permiable as water.

[[in left margin beside this paragraph]] x [[vertical line]] [[/in left margin]] Next prepared a sensible plate, and placed over it a thin plate of mica, and over this again the pointed wires, or rather the blunt ends of the wires from the electrical machine. After turning the machine for about 10 minutes, the plate was impressed with the effect of the chemical examination.

Repeated this experiment with a lens - of small focus (one inch) ; the ends of the wires connected with the machine wire about 2 1/2 inches from the plate with the lens interposed, with this arrangement no effect was produced.
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[[start page]]Thursday 11th May 1843    45
Repeated the last experiment with the same arrangement as in the first case, and with the same result--the impression was very distinct-the time was about 10 minutes--This establishes [[in left margin]] [[underlined]] * [[/underlined]] [[/in left margin]] the fact that the electric spark can produce the effect.
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  In making the last experiment, a fact was observed of some interest apparently--When the thread of light of the electrical machine was viewed through a glass coloured deep [[smudged]] red [[/smudged]], it appeared as if cut into two by a black line through the middle thus: [[drawing]] as in the figure, except that the space which appears white in the drawing is black in the spark. It appears from this experiment that the middle part of the electrical spectrum is absorbed by red glass.

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  The transparent plate of camphor mentioned on the last page was next tested in reference to its thermacy. For this purpose, it was compared with salt. alum & glass.

[[image beside results below: hand with index finger extended, pointing rightward.]]
    
   alum gave 4 1/2 degrees of deflection
   camphor--4 1/2
   glass(trans) 38 degrees
   glass(ground) 28 degrees
   salt -- 90 degrees
Repeated this with the same general result. Camphor scraped, let pass a few more rays.

From this result it appears that camphor is as thermal as alum. The experiment must however be repeated with a perfect polished plate of camphor.

* The same effect would have been produced by the light of the clouds in 5 or 10 seconds.   

Transcription Notes:
interesting, well written experiment notes