Mercury Compounds
A. Place 0.05 to 0.1 ml of a solution of the substance under examination on a well-scraped copper foil; a dark grey stain, which becomes shiny on rubbing, is produced. Heat the dried copper foil in a test-tube; the spot disappears.B. To a solution of the substance under examination add carefully potassium iodide solution; a red precipitate is produced which is soluble in an excess of the reagent (mercuric compounds) or a yellow precipitate is produced which may become green on standing (mercurous compounds).
D. To a solution of the substance under examination add 6 M hydrochloric acid; a white precipitate is produced which is blackened by adding dilute ammonia solution (mercurous compounds).
Nitrates
A. Dissolve 15 mg of the substance under examination in 0.5 ml of water, add cautiously 1 ml of sulphuric acid, mix and cool. Incline the tube and carefully add, without mixing, 0.5 ml of ferrous sulfate solution; a brown color is produced at the interface of the two liquids.B. To a mixture of 0.1 m1 of nitrobenzene and 0.2 ml of sulphuric acid add a quantity of the powdered substance under examination equivalent to about 1 mg of nitrate ion or the prescribed quantity. Allow to stand for 5 minutes and cool in ice whilst adding slowly with stirring 5 ml of water and then 5 ml of sodium hydroxide solution. Add 5 ml of acetone, shake and allow to stand; the upper layer shows an intense violet color.
Phosphates (Orthophosphates)
A. To 5 ml of the prescribed solution, neutralized to pH 7.0, add 5 ml of silver nitrate solution; a light yellow precipitate form, the color of which is not changed by boiling and which is readily soluble in 10M ammonia and in dilute nitric acid.C. To 2 ml of the prescribed solution and 2 ml of dilute nitric acid and 4 ml of ammonium molybdate solution and warm the solution; a bright yellow precipitate is formed.
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