Fig. 205.—A Single Cell.
Figs. 206 and 207.—Details of Zinc and Carbon.
The Bi-chromate Battery Fluid is made up of bi-chromate of potash, sulphuric acid, and water, in the following proportions:
4 ounces of bi-chromate of potash
4 ounces of sulphuric acid
1 quart of water
In making up this solution, first add the acid to the water,—never add the water to the acid—and then, when the solution is nearly cool, add the bi-chromate of potash. Pour the acid into the water slowly, because the combination of the two creates a great deal of heat, and if the heat forms too quickly your glass bottle is likely to split. Label the bottle in which you put this solution POISON.
As the bi-chromate solution attacks the zinc element of a cell even when the current is not being drawn upon, the zinc should be removed when the cell is not in use.
Amalgamating a Zinc Pencil. To reduce the eating away of a zinc pencil used in a bi-chromate solution, the zinc should be amalgamated by rubbing a thin coat of mercury over its surface. Dip the zinc into the solution, first, then with a rag dipped in the solution rub the mercury on to it.