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.

    219/280 (page 193)
    4. When the leathers of the piston were soaked in water, the two gauges nearly corresponded ; but the utmost rarefaction in this circumstance was very small, being, for instance, In one pump—barometer gauge 37 pear gauge 38. In another pump .. .. B4-——-.. .. 37. 5. When the pump, &c. were dry, the barometer gauge was sometimes lower after working the pump five minutes, than after the operation was continued five minutes longer. 6. When the pump and plate were both dry, and the receiver cemented on to the pump-plate, the two gauges nearly agreed, the rarefaction by both being about 600, in damp weather; but in dry weather, and in a still greater degree when a quan- tity of vitriolic acid was in the receiver, (which was always found to gain weight by such its exposure,) the barometer gauge indicated a greater rarefaction than the pear gauge. These facts, some of which the ingenious artist who made the experiments accounted for, seem most or all of them capable of a satisfactory ex- planation upon the theory of vapour we are here maintaining.— When the pump-plate leather is soaked in any liquid, and the pressure is so far diminished that the liquid boils, or turns into va- pour, it is plain the pressure can be no further diminished ; and in such case, when the pump is wrought, it must draw each time a portion of the remaining air along with the vapour, and thus the ete