vapor pressure apparatus
Date: 1870-1890
Inventory Number: DW0182
Classification: Chemistry Apparatus
Subject:
Maker: E. Ducretet & Cie (1864 - 1931)
Cultural Region:
Place of Origin:
Dimensions:
107.8 x 27.5 x 27.5 cm (42 7/16 x 10 13/16 x 10 13/16 in.)
bulb diameter: 9 cm (3 9/16 in.)
Bibliography:
Éléments de physique expérimentale et de météorologie: planches
Description:
A wood stand supporting two vertical glass tubes connected on their lower part by some metallic fittings. The wider tube leads to a platform higher up that holds a glass globe connected to the tube through a stopcock. The narrower tube rises higher than the globe.
Signedon scale: E. DUCRETET & CIE A PARIS
FunctionThis device would be useful for determining the vapor pressure of volatile liquids. One could fill the narrower tube entirely with mercury while the wider one would contain mercury but also some amount of the liquid to be examined floating above it. After draining some of the mercury, the weight of the mercury would create an evacuated space on top of both the narrow tube and the globe of the wider one, and part of the liquid would evaporate, until reaching the vapor pressure at the present temperature. This pressure would be expressed as a difference in heights between the mercury levels in both tubes which could be easily measured.