Terminals.—Take care that the solutions do not splash over terminals; keep all terminals and binding post screws clean and bright. See that all wires are tightly clamped in terminals, also that their ends are clean. A loose contact is productive of infinite trouble. Examine connections that elements are in proper relation to each other. If in multiple, to produce large current—zincs together and carbons together. If in series, for high electromotive force—zinc to carbon, throughout battery.

Zincs.—See that the zincs are clean; if crystals form, either reduce strength of solution with water, or scrape zincs clean, and watch if repeated. Examine screw which holds wire; it often corrodes, and makes poor contact in the thread.

A clever device for preserving a rod zinc from the accumulation of crystals is made by the manufacturers of the Samson cell. It consists of a thin paper tube which is slipped over the zinc. When the crystals accumulate so as to impair the cell, the tube is slipped off and a new one put on. This device increases the internal resistance of the cell but very slightly.

Porous cups and carbons.—Wash in warm water. Carbons can be well soaked in warm water and dried in sun, in a place where they will not accumulate dust. Porous cups should be well soaked in warm water, and left to drain in a place exposed to dustless air. Examine binding post holes and screws.

Solutions.—Do not make too strong. Use not more than six ounces, or more than four ounces avoirdupois, of chemically pure sal ammoniac to one cell Leclanche. Warm water can be used for making solutions, if desired. Some persons drop a teaspoonful of acetic acid in the cell; it is not recommended. If in a place where sal ammoniac cannot be procured, use temporarily common table-salt in same proportion; thoroughly well clean battery first.

Batteries should be kept in a cool dry place. Dry cells should stand upright, also in a cool place, and an examination made once in a while of the connections.


INDEX.