Experiments on air / [Henry Cavendish].

  • Henry Cavendish
Date:
1785
Catalogue details

Licence: Public Domain Mark

Credit: Experiments on air / [Henry Cavendish]. Source: Wellcome Collection.

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    tfirufting down the tube ED a wooden cylinder of fuch a fize as almoft to fill up the whole bore, and by occafionally pouring quickfilver into the fame tube, to fupply the place of that pufhed into the ball C. After the experiment was finifhed, the apparatus was weighed again, which Ihewed exaCtly how much air had been forced into the tube M during the whole experi- ment ; it being equal in bulk to a quantity of quickfilver, whofe weight was equal to the increafe of weight of the apparatus. The bore of the tube M ufed in moft of the following ex- periments, was about one-tenth of an inch ; and the length of the column of air, occupying the upper part of the tube, was in general from if to f of an inch. It is fcarcely neceflhry to inform any-, one ufed to eleCfcrical experiments, that in order to force an electrical fpark through the tube, it was neceflary, not to make a communication be- tween the tube and the conductor, but to place an infulated ball at fuch a diftance from the conductor as to receive a fpark from it, and to make a communication between that ball and the quickfilver in one of the glaffes, while the quickfilver in the other glafs communicated with the ground. ' • ‘ • . . i » I now proceed to the experiments. When the eleCtric fpark was made to pafs through common air, included between fihort columns of a folution of litmus, the folution acquired a red colour, and the air was diminilhed, conformably, to what wasobferved by Dr. Priestley. When lime-water was ufed in (lead of the folution of litmus, and the fpark was continued till the air could be no further di- minifhed, not the leaf! cloud could be perceived in the lime- water; but the air was reduced to two-thirds of its original bulk; which is a greater diminution than it could have futfered by mere phlogiftication, as that is very little more than one- fifth of the whole. Thej
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