A treatise on electricity wherein its various phoenomena are accounted for, and the cause of the attraction and gravitation of solids, assigned : To which is added, a short account, how the electrical effluvia act upon the animal frame, and in what disorders the same may probably be applied with success, and in what not / By Francis Penrose.

  • Penrose, Francis, 1718-1798.
Date:
1752
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on electricity wherein its various phoenomena are accounted for, and the cause of the attraction and gravitation of solids, assigned : To which is added, a short account, how the electrical effluvia act upon the animal frame, and in what disorders the same may probably be applied with success, and in what not / By Francis Penrose. Source: Wellcome Collection.

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    t ^8 ] the air or atmofphere, fo likewife it mud depend on the make and faze of the pores of fuch bodies3 for bodies whofe pores are fmattef, mull: be adted upon with a greater power than thole whofe pores are largef or whofe pores are fo large as not only to admit light, but alfo common air into them. This Mr. Haukfbee proves by a curious experiment, for having placed two brafs hemi- fpheres, of 3 \ inches diameter, upon each other, and then extracting the grofs air out of them by the air pump, and by thefe means taking off the refinance of the common air that was within the two brafs hemifpheres, he fays, it required 140 pound weight to feparate them 3- this experiment with that of the two marble flabs before men¬ tioned, is a demonftration of the power that keeps folid bodies from falling to pieces. And even, if thefe flabs are not fo perfectly jmoothy yet the wet- ing them with water, which prevents the grofs air from entering, will produce the like effedt. That folids expand themfelves by heat or fire, is proved by heating an iron rod in the fire : in which cafe, it is always found to be bigger and longer when hot than cold 3 and it was the opi¬ nion of Boerhaave, that cold confolidates all thofe that are called firm bodies 3 that is, brings that part, which we call body in them, into a lefs co?n- fafs than before, and thus unites tire matter there¬ of «r