The instrument was used over a long period of time to verify the purity
of the air by determining the percentage by volume of oxygen contained
in it.
To perform this volumetric analysis, equal volumes of hydrogen and air
are placed in the eudiometer. All the oxygen contained in the air combines
with a volume of hydrogen that is double that of the oxygen and, to obtain
the volume of oxygen contained in the air sample analysed in parts per
hundred it suffices to determine, still in parts per hundred, the volume
of gas missing and divide by three.
