Elements of chemistry ... / [John Murray].

  • Murray, J. (John), -1820
Date:
1810
Catalogue details

Licence: Public Domain Mark

Credit: Elements of chemistry ... / [John Murray]. Source: Wellcome Collection.

    169/1076 (page 155)
    what diminished, from the quantity operated on being larger ; the aerial fluid being passed through the instru- ment by a spiral tube, the temperature as it enters and passes out being ascertained by thermometers. But still the results are probably considerably remote from accura- cy. Mr Leslie observed, that when a portion of air is ra- rified in a vessel, and time is allowed for its recovering the temperature of the surrounding medium, on admitting suddenly another portion of air into the partial vacuum, the ratified air is compressed ; it hence gives out a quanti- ty of caloric, and this, communicated to the air which has been admitted, raises its temperature. But the rise will be less, as this air requires more caloric to produce in it a given change of temperature ; and therefore in operating on different aerial fluids, the comparative quantities may be discovered from the respective elevations of ternpera- tlire. The method is extremely ingenious, but attended with considerable difficulties in the execution, so as to at- tain accurate results. The property by which different bodies contain their respective quantities of caloric, has been termed the Ca- pacity for Heat, or, adapting the expression to the modern nomenclature, the Capacity of a body for Caloric. This term is not designed to imply any theory with regard to the cause of this property, or the nature of it; nor does it present, as has been alleged, a vague or obscure idea. It is simply a general expression, to denote the property, in consequence of which, bodies contain at any given tem- perature, in equal quantities, peculiar quantities of caloric. That they do so is unquestionable, and it is convenient to