The breaking up of a substance by passing electricity through a solution of the substance is called electrolysis and the solution in which it takes place an electrolyte. This process is of great industrial importance. All chemical compounds - acids, salts, and bases - are made up of two parts; the positive or metallic part, and the negative or non-metallic part. When any compound is dissolved, it breaks up partially into these two parts. The positive or metallic portion is charged with positive electricity and is attracted to the negative electrode or plate.

Fig. 73.   Electric Bell.

Fig. 73. - Electric Bell.