254 g of potassium iodide dissolved in 125 ml of water are mixed with 100 g of ammonium sulfate dissolved in 125 ml of boiling water.
After cooling, 40 ml of alcohol are added and the mixture is kept 12 hours. The obtained precipitate of potassium sulfate is filtered and the filtrate is evaporated occasionally adding ammonia water containing some alcohol, until crystallization begins.
The crystals of potassium sulfate are additionally washed with dilute alcohol (20%), and after combining the filtrates and evaporation the ammonium iodide is obtained. Ammonium iodide crystallizes in cubes and deliquesces in the air. It should be preserved in a dark place, as light decomposes the salt, causing it to turn brown. This coloration may be removed by dissolving in distilled water, treating the solution with ammonium sulfide, filtering, and evaporating the filtrate on the steam bath, to crystallize. It is readily soluble in alcohol.
The aqueous solution becomes yellow on standing, owing to decomposition and separation of iodine.
One part of the salt dissolves in 0.60 part of water.