A better process is to commence by precipitating the silver entirely in the form of _chloride of silver_, by adding common salt until no further milkiness can be produced. If the liquid is well stirred, the chloride of silver sinks to the bottom, and may be washed by repeatedly filling the vessel with common water, and pouring off the upper clear portion when the clots have again settled down. The chloride of silver thus formed may afterwards be reduced to metallic silver by a process which will presently be described. b. _Separation of Silver from solutions containing alkaline Hyposulphites, Cyanides or Iodides._--In this case the silver cannot be precipitated by adding chloride of sodium, since the chloride of silver is _soluble_ in such liquids. Therefore it is necessary to use the sulphuretted hydrogen, or the hydrosulphate of ammonia, and to separate the silver in the form of _sulphuret_. Sulphuretted hydrogen gas is readily prepared, by fitting a cork and flexible tubing to the neck of a pint bottle, and having introduced _sulphuret of iron_ (sold by operative chemists for the purpose), about as much as will stand in the palm of the hand, pouring upon it 1-1/2 fluid ounces of oil of vitriol diluted with 10 ounces of water. The gas is generated gradually without the application of heat; and must be allowed to bubble up through the liquid from which the silver is to be separated. The smell of sulphuretted hydrogen being offensive, and highly poisonous if inhaled in a concentrated form, the operation must be carried on in the open air, or in a place where the fumes may escape without doing injury. When the liquid begins to acquire a strong and persistent odor of sulphuretted hydrogen, the precipitation of sulphuret is completed. The black mass must therefore be collected upon a filter, and washed by pouring water over it, until the liquid which runs through gives little or no precipitation with a drop of nitrate of silver. The silver may also be separated in the form of sulphuret from old hypo baths, by adding oil of vitriol in quantity sufficient to decompose the hyposulphite of soda; and burning off the free sulphur from the brown deposit.