☞ Electricity is manifested under following different forms: (a) , called also , electricity in the condition of a stationary charge, in which the disturbance is produced by friction, as of glass, amber, etc., or by induction. (b) , called also , electricity in motion, or as a current produced by chemical decomposition, as by means of a voltaic battery, or by mechanical action, as by dynamo-electric machines. (c) , in which the disturbing cause is heat (attended possibly with some chemical action). It is developed by uniting two pieces of unlike metals in a bar, and then heating the bar unequally. (d) , any condition of electrical disturbance in the atmosphere or clouds, due to some or all of the above mentioned causes. (e) , electricity developed by the action of magnets. (f) , the electricity that appears at the positive pole or anode of a battery, or that is produced by friction of glass; – called also . (g) , the electricity that appears at the negative pole or cathode, or is produced by the friction of resinous substance; – called also resinous electricity. (h) , that which is developed in organic structures, either animal or vegetable, the phrase animal electricity being much more common.