| Mercuric Chromate, HgCrO4, is formed by heating an equivalent mixture of mercuric oxide and chromic anhydride with a little water. It yields dark red rhombic prisms, which are decomposed by water with formation of the basic salt, 3HgO.CrO3. Many basic salts have been described, but it has been shown from an investigation of the system, HgO-CrO3-H2O, that the above is the only one which exists as a separate chemical entity. It may also be produced by precipitation of mercuric nitrate solution with a dichromate, or by boiling mercuric oxide with potassium dichromate solution. The compound, 2HgCrO4.HgS, formed by the action of a chromic acid solution of mercuric oxide on freshly precipitated mercuric sulphide, has explosive properties. |