A Mineral White.

Manufacturer and builder 7, 1884

A mineral white, suitable for use as a pigment, may be prepared, according to Cobley, by converting first magnesium sulphate into the chloride by the addition of calcium chloride. To this 10 per cent of aluminium chloride is then added, and from the mixed chlorides a white precipitate of the hydrated oxides is thrown down by the addition of milk of lime. A cheaper white is obtained by the direct precipitation of the corresponding sulphates with milk of lime. These pigments do not discolor by the action of sulphurous gases, like lead pigment.