R. C. Browne

As the amateur electrician is usually interested in making small and compact batteries,which may readily be carried in the pocket or used for experiments, the following description of making a chloride of silver battery may prove useful.

The chloride of silver may be purchased all prepared, but a good grade well adapted for the battery, is not difficult to make. A silver coin or piece of scrap silver (not plated ware) is placed in a clean glass tumbler and slightly diluted nitric acid is carefully poured over it in sufficient quantity to completely disolve the silver. A little pure water is added occasionally and the solution should be frequently stirred with a glass rod. When completely disolved, put strips of sheet copper into the solution and the silver will be precipitated. Continue the copper in the solution until all precipitation stops. Pour off the liquid carefully and redisolve the silver in fresh nitric acid as before.

Make a strong solution of common salt and pure water and add slowly to the silver nitrate solution until all precipitation ceases, and then allow it to settle. Pour off the liquid or filter to secure the precipitate which is chloride of silver, and after being washed with pure water, is ready for the battery. The latter part of the above operations should be done in a dim light or a dark room with a ruby lantern, as chloride of silver is sensitive to white light. The washing with water is most easily done by stirring with a glass rod and then allowing it to settle, after which the water is poured off or filtered.

Obtain some pure sheet zinc 1/16" thick or, if possible, a few inches of zinc tube 1/2" in diameter. If the sheet zinc is used, it must be rolled around a piece of 1/2" round wood to form a cylinder and the edges soldered together with a butt joint. Cut the tube into sections 11/2" long with a file and solder a round piece of zinc into one end so as to form a small cup 11/2" by 1/2", open at one end. This cup is to form the retaining cell for the battery and also serve as one pole.

Obtain a piece of sterling silver 13/4" long and 1/8" or 3/16" wide, by rolling or pounding silver wire or by cutting up a discarded spoon or other article, as it is not necessary that it be very thick. A longer piece may be used and the battery will give more current, but in such a case, the strip should be bent back to form two thicknesses 13/4" long. Make a small paper tube about the size of a lead pencil and 11/4" long, closing one end with sealing wax and after putting the silver strip in the centre, ram the remaining space with the chloride of silver. This constitutes the other pole of the battery and should be placed in the centre of the zinc cup; the space between it and the sides being filled with cotton wool or blotting paper.

Moisten the contents of the zinc cup with a strong solution of common salt and water and seal the top of the cup with sealing wax. After soldering connecting wires to the zinc cup and silver strip, the cell will be complete, giving one volt and current enough to ring a common electric bell.

The above dimensions may be changed to meet the requirements of anyone making the battery. I have made them, measuring not over 1/2" high. The chloride of silver can be melted and cast around the silver electrode but this is probably beyond the scope of the average reader. Use great care that none of the silver solution gets on the hands or clothing, as it is a caustic poison and will make indelible black stains. Remember to keep the chlroide of zinc in the dark, in fact, it will be well to keep all the chemicals in dim light.