SRPS H.B8.318:1977

Sodium and potassium silicates for industrial use — Determination of carbonates content — Gas-volumetric method

Scope

Three cases, defined by a preliminary test, are envisaged: silicates containing neither sulphides nor chlorates; silicates containing sulphides; silicates containing chlorates. The method based on boiling of an acidified test portion containing methyl orange and with a lead paper strip in the vapour. The presence of sulphides produces blackening of the paper and the presence of chlorates decolorizes the methyl orange. Volumetric*measurement of carbon dioxide evolved from silicates containing neither sulphides nor chlorates by reaction with a hydrochloric acid solution. The principle for the oxidation of sulphides and the reduction of chlorates are specified.