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.

    126/280 (page 100)
    It has been observed already that air charged with vapour, or vapourized air, is specifically lighter than when without the vapour ; or, in other words, the more vapour any given quantity of at- mospheric air has in it, the less is its specific gra- vity.—M. Dz Saussurz has found from experiment, that a cubic foot of dry air, of a certain temperature, will imbibe 12 grains of water; and that every erain of water dissolved in air becomes an elastic fluid capable of supporting ++ of an inch of mercury, while its density to that of air, is as 3 to 4.—Again, Dr. Prizstiey has found from frequent experiments (vide Experiments and Observations relating to va- rious branches of Natural Philosophy, Vol. 6, page 390) that different kinds of air, as for instance, inflammable air, and dephlogisticated air, the spe- cific gravities of which are as 1 to 12 nearly, when mixed together, do not observe the laws of hydro- statics ; for, the inflammable air, instead of rising to the top of the vessel, diffuses itself equally and permanently through the dephlogisticated air, at the same time that no chemical attraction takes place betwixt them. The Doctor further observes, that ‘‘ the phlogisticated and dephlogisticated air, which compose the atmosphere, are of very differ- ent natures, though without any known principle of attraction between them, and also of different specific gravities ; and yet they are never separated but by the chemical attraction of substances, which unite with the one and leave the other.” —Moreover, Sir Bensamin Tuomson has found that moist air