Dissolve the sal ammoniac in the water thoroughly. Let stand twenty-four hours. Then add the zinc chloride, and when cool, will be ready for use.
When you have your zinc cup ready, pour a little wax in the bottom, to insulate; place a piece of blotting-paper inside cup and laying tight against the zinc, about three turns. The negative element is prepared as follows: One pound pure carbon, powdered; one pound black oxide manganese; mix thoroughly. Then add sufficient of above solution to hold it together without being plastic, as that would be too wet to tamp.
Moisten your paper in the zinc cup thoroughly. Place your stick or plate of carbon in centre of zinc cup, hold it there central while you pack in the carbon manganese element all around it; be sure that carbon manganese, or negative element, does not touch zinc cup. If it does, your cell will run down quickly. It is a good precaution to have your paper half an inch higher than cup when in the cup, and soaked with the solution. Give it a couple of quick taps on the bench; that will curl the paper in at the bottom and insure against any internal short circuit. When your cell is filled up, clean all the carbon element away from the zinc. Seal, and your battery is ready when you’ve got the connections on.
Fig. 54.
The New Standard Dry Cell.
The principal sizes of this cell (Fig. 54) are as follows:
No. 2—5-7/8 × 2-7/16.
No. 3—3-3/4 × 1-7/8.
No. 5—6 × 2-9/16.
No. 6—6 × 3.
No. 7—7 × 3.