The Probert Encyclopaedia of Science & Technology

EUDIOMETER

An eudiometer is a chemical apparatus introduced by Joseph Priestley in 1770, originally designed for ascertaining the purity of the air or the quantity of oxygen it contains, but later employed generally in the analysis of gaseous mixtures. The eudiometer consists of a graduated glass tube, either straight or bent in the shape of the letter U, hermetically sealed at one end and open at the other. Two platinum wires, intended for the conveyance of electric sparks through any mixture of gases, are inserted through the glass near the closed end of the tube, and approach but do not touch each other. The electric spark causes chemical combination to take place between the oxygen in the gas to be analysed, and hydrogen which has been introduced into the tube, and the nature and proportion of the constituents of the gaseous mixture are determined by the diminution in volume after the passing of the spark. Or certain substances, such as caustic potash, pyrogallic acid, etc, may be introduced into the closed tube in order to absorb the gases present one by one.
Research Eudiometer