Meteorological observations and essays / By John Dalton.

  • John Dalton
Date:
1834
Catalogue details

Licence: Public Domain Mark

Credit: Meteorological observations and essays / By John Dalton. Source: Wellcome Collection.

    221/280 (page 195)
    ambient air, other circumstances being the same, the greater must the rarefaction be by both gauges. When by long pumping a quantity of vapour is collected in the barrel of the pump, I conceive a portion of it may, during the operation, escape again into the receiver; this will account for the 5th fact. I do not see how the 6th fact can be explained without supposing that the elasticity of dry air, when greatly expanded, decreases in a greater pro- portion than its density: it is true that the increase of cold in the receiver, and the less vapour there is in the air at first, the more will the rarefaction in- dicated by the barometer gauge exceed that of the pear gauge; for, it cannot be reasonably supposed that when the rarefaction is at its utmost degree, the proportion of vapour to air in the receiver is no greater than at first; I conceive, therefore, that the air condensed in the pear gauge is always satu- rated with vapour, unless perhaps when the vitriolic acid is in the receiver, and of course its bulk, ceteris paribus, greater than before: but this alone is not sufficient to account for the observed differ- ences of the gauges.