Preparation of Ammonium Sulfide Solution

Preparation of Ammonium Sulfide Colorless
1-  3 M. Treat 200 ml of conc. NH₄OH with H₂S until saturated, keeping the solution cold. Add 200 ml of conc. NH₄OH and dilute of 1 liter.
2-  6 N. Saturate 6N ammonium hydroxide (40 ml conc. ammonia solution +60 ml H₂O) with washed H₂S gas. The ammonium hydroxide bottle must be completely full and must be kept surrounded by ice while being saturated (about 48 hours for two liters). The reagent is best preserved in brown, completely filled, glas-stoppered bottles. 

Preparation of Ammonium Sulfide Yellow
Treat 150 ml of conc. NH₂OH with H₂S until saturated, keeping the solution cool. Add 250 ml of conc. NH₂OH and 10 g of powdered sulfur. Shake the mixture until the sulfur is dissoalved and dilute to 1 liter with water. In the solution the concentration of (NH₄)₂S₂, (NH₄)₂S and NH₄OH are 0.625, 0.4 and 1.5 normal respectively. On standing, the concentration of (NH₄)₂S₂ increases and that of (NH₄)₂S and NH₄OH decreases.