Symbol, PbO NO{5}. Atomic weight, 166.
Nitrate of lead is obtained by dissolving the metal, or the oxide of lead, in excess of nitric acid, diluted with 2 parts of water. It crystallizes on evaporation in white anhydrous tetrahedra and octahedra, which are hard, and decrepitate on being heated; they are soluble in 8 parts of water at 60°.
Nitrate of lead forms with sulphuric acid, or soluble sulphates, a white precipitate, which is the insoluble sulphate of lead. The Iodide of lead is also very sparingly soluble in water.
Nitrate of Silver. (See [Silver, Nitrate of.])
Symbol, NO{4} + Cl.
This liquid is the aqua-regia of the old alchemists. It is produced by mixing nitric and hydrochloric acids: the oxygen contained in the former combines with the hydrogen of the latter, forming water and liberating chlorine, thus:—
NO{5} + HCl = NO{4} + HO + Cl.
The presence of free chlorine confers on the mixture the power of dissolving gold and platinum, which neither of the two acids possesses separately. In preparing aqua-regia it is usual to mix one part, by measure, of nitric acid with four of hydrochloric acid, and to dilute with an equal bulk of water. The application of a gentle heat assists the solution of the metal; but if the temperature rises to the boiling point, a violent effervescence and escape of chlorine takes place.
Oxygen.