Abstract
SIR WILLIAM THOMSON has frequently dwelt on the great importance of insulating, with the utmost care, any apparatus intended for researches relating to static electricity; he has shown that the atmosphere and other gases have but little effect in dissipating an electric charge, even when moist, and that it escapes mainly in consequence of the deposition of a layer of moisture upon the insulating supports which renders their surface conducting. In all Sir W. Thomson's electrometers there is an arrangement for drying the insulating surfaces by means of sulphuric acid, either free or absorbed by pumice. This method admits of very general application:—Any body, as for example apparatus constructed for the observation of atmospheric electricity, may be most perfectly insulated by supporting it on glass rods inserted in glass cylinders containing free sulphuric acid or pumice moistened with it. In order to do this the lower end of the rods must be either inserted into cylinders of lead or else fixed to the bottom of the jar by means of a substance not acted upon by sulphuric acid, for example, melted sulphur or paraffin; melted sulphur is liable, on account of its temperature, to crack the jars, notwithstanding the precaution of previous heating; paraffin, on the other hand, softens in the course of time, and the glass rods do not retain their vertical position. Notwithstanding these disadvantages excellent insulators may be thus extemporised as occasion may require.
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A NEW INSULATING STAND 1 . Nature 18, 44 (1878). https://doi.org/10.1038/018044a0
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DOI: https://doi.org/10.1038/018044a0