Stannic Chromate

When stannic chloride is added to a solution of potassium chromate a yellow precipitate is formed, while the liquid becomes orange-yellow, free chromic acid being liberated. The precipitate, when dried, becomes brownish yellow and translucent, and on heating changes into violet chromic stannate.

Stannous Chromate has been described by Berzelius as a yellow flocculent precipitate resulting on the addition of stannous chloride to an excess of potassium chromate solution. If, however, dilute potassium chromate solution is added in small portions, with constant shaking, to stannous chloride, a greenish-white precipitate is produced which is probably chromic stannate. If the tin solution contains free acid the whole remains dissolved, forming a green solution.