| a crystalline, water-insoluble, poisonous compound, HgS, occurring as a coarse, black powder (black mercuric sulfide) or as a fine, bright-scarlet powder (red mercuric sulfide): used chiefly as a pigment and as a source of the free metal. |
| mercuric sulfide n. A poisonous compound, HgS, having two forms: a. Black mercuric sulfide, a black powder obtained from mercury salts or by the reaction of mercury with sulfur, used as a pigment. |