Characters. - A heavy, bright, citron-yellow powder, neutral, with no taste or smell.

Solubility. - Sparingly soluble in water, readily soluble in chloride of ammonium.

Reaction. - When strongly heated it first fuses and then is decomposed, emitting violet vapours of iodine, and leaving a citron-yellow residue.

Preparation. - By mixing solutions of nitrate of lead and potassium iodide.

Impurities. - Chromate, zinc, alkalis, and alkaline earths.

Tests. - On triturating 1 part of the salt with 2 parts of chloride of ammonium in a porcelain mortar, and adding 2 parts of water, a colourless liquid should result (absence of, and difference from, chromate). This liquid, diluted with water, affords a white precipitate with diluted sulphuric acid, and a black one with hydrosulphuric acid. If all the lead has been precipitated from a portion of the solution by the last-named reagent, the filtrate should leave no residue on evaporation and gentle ignition (absence of zinc, alkalis, or alkaline earths).

Preparations.

B.P. Emplastrum Plumbi lodidi. Iodide of Lead Plaster, 1 part in 9 (with soap and resin plaster).