Page:Journal of the Right Hon. Sir Joseph Banks.djvu/512

From Wikisource
Jump to navigation Jump to search
This page has been proofread, but needs to be validated.
454
APPENDIX

though given with as much electricity as could be got into the phial. It then (having grown by degrees weaker and weaker) ceased to work entirely. Water was applied to the cushions, but without any effect: everything then was wiped and dried as well as could be done in our situation, the cushions being carried to the fire, but no electricity perceptible to the touch was communicated to the conductor. Whether any was excited on the surface of the plate we did not then observe. An amalgam of lead was then applied, causing a small amount of electricity, but much less than at first, and this very soon ceased also. From that time no electricity perceptible (except by Canton's electrometer) could be communicated to the conductor, though the machine was worked nearly an hour.

In the course of these experiments two things were observed, differing from the phenomena usually seen. First, the phial when filled with as much electricity as possible would not retain it more than a very few seconds, three or four by guess (for no opportunity of measuring by a watch was given, the machine stopping work without any warning); at the end of this time not the smallest quantity of electricity was left, though I tried all my five phials. Two of these phials were such as were described above; the others were smaller, made much in the same manner, but instead of being coated on the inside were filled with leaf-gold. Secondly, the floor of the cabin in which the experiments were tried was covered with a red floor-cloth of painted canvas that had been issued to the ship from His Majesty's stores at Deptford. This was usually washed with salt water every morning and allowed to dry without being taken up. This proved as good a conductor of electricity as any we could make use of, so that a man standing on one side the machine and touching the coating of the phial was shocked by another who touched the conductor, without having any other communication with the first than by the floor-cloth under his feet. Dr. Solander and myself tried this in several ways, and made more experiments afterwards with Mr. Green's machine, as noticed further on.