24. Battery Fluid for Simple Cells. For the simple cell ([App. 5]), when it is to be used for experiments with detectors or in the study of polarization, etc., a very dilute acid is best. Mix 1 fluid ounce of commercial acid with 1 pint of water. This will make 17 fluid ounces ([See App. 19]), and your mixture will be one-seventeenth acid. Make up a pint or quart bottle of this at a time, and label it with the date:
Dilute sulphuric acid.
1 part acid, 16 parts water.
Apparatus 14.
25. Note. Do not fail to paste a label on all bottles as soon as you have put anything into them. Give the date, contents, and any other information that will help you to reproduce the mixture again. Do not write on them any abbreviations or other things that you will soon forget.
26. Battery Fluid; Bichromate Solution. For running small motors, shocking coils, etc., this solution will be found good when used with the zinc and carbon elements given in [App. 3] and [4]. The bichromate destroys the hydrogen bubbles which help to polarize cells so rapidly when the plain dilute acid ([App. 14]) is used. (Study polarization.) The zinc used in this fluid must be well amalgamated ([App. 20]).
Directions. With 1 quart of cold water placed in a glass or earthen dish, slowly mix 4 fluid ounces of commercial sulphuric acid. [Read § 22] carefully. When this gets about cold, add 4 ounces of bichromate of potash. Powdered bichromate will dissolve more quickly than the lump. Keep this fluid in corked bottles, labelled, with date:
Bichromate Battery Fluid.
Apparatus 15.
27. Always take the zinc from this fluid as soon as you have finished experimenting, or even if you have no use for the cell for a few minutes. The zinc and fluid are rapidly destroyed in bichromate cells even when the circuit is open. Always wash the carbon and zinc as soon as you take them from the fluid.