The determination of very low concentrations of hydrogen sulphide in gas-I

The determination of low concentrations of hydrogen sulphide in gas has been investigated. A modified calibration technique has been developed for the methylene blue method and its accuracy verified volumetrically and gravimetrically. Employing the methylene blue method as a primary standard, the relation between optical density and sulphur content of lead sulphide stains, obtained by passing gas through absorbent paper, has been replotted, using a specially designed photoelectric densitometer.