Estimation of metals as sulphides : Estimation of bismuth,cadmium, lead,and indium

1. It has been shown, that under proper conditions bismuth, cadmium, lead and indium can be precipitated quantitatively as pure sulphides by alkali sulphides and the precipitate weighed directly for the estimation of the motal. 2. In the case of bismuth ammonium sulphide gives a pure precipitate of Bi₂0₃ which is washed with hot water and weighed directly. 3. In the case of cadmium sodium sulphide gives a pure orange coloured precipitate of the Bulphide which is washed with water and without any further treatment, weighed as CdS. 4. In the case of lead the solution is treated with alkali sulphide, the mixture is then acidified with. acetic acid and the pure precipitate of PbS after washing with water weighed directly without heating. 5. In the case of indium treatment with ammonium sulphide gives a pure precipitate of In₂S₃ which after washing and heating can be weighed directly for the estimation of the metal. Equally good results are obtained if the mixture is acidified with acetic acid after treatment with ammonium sulphide. 6. The given procedures provide for a convenient, quick and accurate estimation of the metals.