(Battery-fluid).

A. For the Carbon and Zinc Battery. - I. (For ordinary use). - Potassium Bichromate, in powder, 6 troy ounces (180 Gm.); Sulphuric Acid, commercial, 6 fluidounces (180 Cc.); Water, cold, 48 fluidounces (1400 Cc). - II. (For use with the galvano-cautery). - Sodium Bichromate, in powder, 6 1/2 troy ounces (185 Gm.); Sulphuric Acid, commercial, 14 fluidounces (420 Cc); Water, cold, 48 fluidounces (1400 Cc).

Pour the Sulphuric Acid upon the powdered Bichromate and stir the mixture occasionally during one hour. Then slowly add the Water. Sodium Bichromate is more soluble than the Potassium Salt, and also much cheaper. When it cannot be obtained, the Potassium Salt may be substituted for it, weight for weight.

B. For the Leclanche Battery. - Ammonium Chloride, 6 troy ounces (180 Gm.); Water, enough to make 20 fluidounces (600 Cc); dissolve the Salt in the Water.