hygrometer using a hygroscopic substance (for example, diphosphorus pentaoxide, P2O5
) which is transformed into an electrolyte (phosphoric acid, H3PO4
) in contact with the moisture in the gas. The electrolyte (phosphoric acid) is electrolysed continuously and the electrolysis current is measured. At a constant flow of the gas to be analysed, the electrolysis current is a linear function of the water concentration.
PAC, 1990, 62, 2167. 'Glossary of atmospheric chemistry terms (Recommendations 1990)' on page 2195 (https://doi.org/10.1351/pac199062112167)