Leyden Jar. A mere plate of glass, in the jar form, for the convenience of handling ; an electrical excitement is produced on one side, and this operates on the chemical elements within the substance of the glass, just as though it were a plate of air, or a plate of fluid in a galvanic combination; and the opposite side has a similarly opposite excitement, as acid and akaline, called positive and negative; and the excitement continued by a metal surface, from side to side, produces, when within a small distance, an explosive restoration of the two disturbed sides, considered either as acid and alkaline, oxygen and hydrogen, or supporter and combustible.