Brown glas reagent bottle labelled 'HYDRIC SULPHIDE', 1940.
© Science Museum / Science & Society Picture Library
Reagent bottle with an embosed, fired label and a ground glas stopper. A reagent is a substance or mixture used in chemical analysis. Many laboratory chemicals are stored in this type of bottle. Hydrogen (Hydric) Sulphide (H2S) is a poisonous gas with a characteristic 'rotten egg' smell. It disolves in water to form an acidic solution.