A battery, to work well, should be gradually losing strength, but never gaining.

An old battery, however, may be quickened up and made to work well for some time, by adding five of six drops of sulphuric acid, repeating the quantity as often as necessary, providing always that acid be not used in manufacturing the quick.
4.

Have the plates lost their sensitiveness by being many times exposed to mercury?
Clean and burn them; but if French plates, burn light, or you spoil them.
5.

Are the buff s dry and clean?
Examine the plate critically after buffing to detect any appearance of scum or film on the surface.

If so, the longer you buff the more it shows.