Account of a series of experiments, shewing the effects of compression in modifying the action of heat. Read in the Royal Society of Edinburgh, June 3, 1805 / by Sir James Hall.

  • Hall, James, 1761-1832.
Date:
[1805]
Catalogue details

Licence: Public Domain Mark

Credit: Account of a series of experiments, shewing the effects of compression in modifying the action of heat. Read in the Royal Society of Edinburgh, June 3, 1805 / by Sir James Hall. Source: Wellcome Collection.

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    tions, mu ft produce, in our times, refults fimilar to thofe afcri- bed, in that Theory, to the former adtion of fire. In comparing the Huttonian operations with thofe of the volcanoes, I fliall avail myfelf of fome fadts, brought to light in the courfe of the following inveftigations, by which a pre- cife limit is aftigned to the intenfity of the heat, and to the force of compreftlon, required to fulfil the conditions of Dr Hutton’s hypothefis : For, according to him, the power of thofe agents was very great, but quite indefinite j it was there¬ fore impoffible to compare their fuppofed effedts in any precife manner with the phenomena of nature. My attention was almoft exclusively confined to the Carbo¬ nate of Lime, about which I reafoned as follows: The carbonic acid, when uncombined with any other fubftance, exifts natural¬ ly in a* gafeous form, at the common temperature of our atmo- fphere j but when in union with lime, its volatility is reprefled, in that fame temperature, by the chemical force of the earthy fubftance, which retains it in a folid form. When the tem¬ perature is raifed to a full red-heat, the acid acquires a vola tility by which that force is overcome, it efcapes from the lime, and affumes its gafeous form. It is evident, that were the attradlive force of the lime increafed, or the volatility of the acid diminifhed by any means, the compound would be enabled to bear a higher heat without decompofttion, than it can in the prefent ft ate of things. Now, prefliire muft produce an efFedt of this kind; for when a mechanical force oppofes the expan- fion of the acid, its volatility muft, to a certain degree, be di¬ minifhed. Under prefliire, then, the carbonate may be expedt- ed to remain unchanged in a heat, by which, in the open air, it would have been calcined. But experiment alone can teach us, what comprefling force is requifite to enable it to refift any given elevation of temperature 3 and what is to be the refult of fuch an operation. Some of the compounds of lime with acids are.