52.2 Nessler’s Reagent: 52.2.1 Solution A—Dissolve 270 g of sodium hydroxide (NaOH) pellets in water and dilute to 1 L. 52.2.2 Solution B—Dissolve 36 g of potassium iodide (KI) crystals and 13.6 g of mercuric chloride (HgCl2) powder in water and dilute to 500 mL. To prepare the Nessler’s reagent, mix three parts of Solution A with 5 parts of Solution B. It should be allowed to stand until the solution is clear before using. (Warning—Solution B and the Nessler’s reagent are highly toxic.)