APPENDIX C TREATMENT OF SILVER RESIDUES. SILVER residues generally consist chiefly of silver chloride, and may be treated as follows. Add hydrochloric acid in slight excess to precipitate any soluble silver salt that may be present, and allow the precipitate to subside. Pour off the supernatant liquid, and wash the precipitate several times (by decantation) with water. Place the precipitate in an evaporating basin, add solution of caustic soda and one or two pieces of sugar, and boil the mixture, stirring constantly. As soon as the precipitate seitles rapidly to the bottom, leaving the liquid clear, the heating is stopped, and the precipitate washed with common water (by decantation) till no longer alkaline, and finally once or twice with distilled water. The moist precipitate is then dissolved in pure nitric acid, and evaporated to obtain crystals of silver nitrate. any choloride has escaped reduction, the solution in nitric acid will not be clear, in this case it must be diluted and filtered. When the quantity of silver residues is small, it is better to dissolve the finely divided silver in the smallest quantity of nitric acid possible, dilute with distilled water, and filter the solution. N If |