From the diminution in volume (and further diminution by action of different absorbents if necessary) the quantity of hydrogen or other detonating gas is known.
Historical reference: Do not rely on this information. It is very old. About this collection
Eudiometer, a glass vessel, largely used in gas analysis. Various forms of eudiometers exist, many specially adapted for some particular analysis. The most common form consists of a straight tube of thick glass open below and closed above, upon which is accurately engraved a scale, generally in millimetres. Through the glass near the top are sealed two platinum wires across which an electric speerk can be passed. The mode of use consists in placing a known quantity of gas into the eudiometer over mercury, then adding an amount of oxygen (other gas if necessary) and exploding.