The next time I sauntered down to the mill the boys were working on what they called an electric shower bath. They had fastened upon the wall of the bath room an electric bell (Fig. 149), and placed on a shelf near by a battery of two dry cells, _P_. The switch which closed this primary circuit was on the wall by the side of the faucet and electric heating switch (Fig. 148). One of the wires, _S_, for the secondary circuit was carried up and connected to the pan _A_ (Fig. 148). The other wire was fastened to a sheet of zinc about a foot square, which lay upon the floor of the shower bath. The idea was that when one was taking a shower bath, if he chose to vary his sensations he might step upon the sheet of zinc, close the switch in the primary circuit and let the secondary current pass through his body by way of the shower. They said that it was particularly prescribed for slow people. Speaking of chores, of course the most insistent chore was to keep the storage batteries stored. This process gave rise to many questions, through which the information contained in the next chapter was brought out. XV ELECTRIC CURRENTS FROM CHEMICAL ACTION AND CHEMICAL ACTION FROM ELECTRIC CURRENTS Luigi Galvani (1737-1798) of Bologna, Italy, in 1786 unwittingly produced an electric current from chemical action. Because he was eagerly seeking other results he misinterpreted this. Several words in the dictionary are becoming either obsolete or misnomers. For example, galvanism is an old-fashioned word for an electric current. The expression _galvanic electricity_ is a relic of the abandoned idea that there are several kinds of electricity, of which Galvani discovered one. Galvanized iron is wholly a misnomer. It is a name used for iron which has been coated with zinc, and it suggests the idea that somehow the zinc is coated upon the iron by means of an electric current, whereas in fact it is done by dipping the iron into melted zinc. Alessandro Volta (1745-1827) of Como, Italy, took up the discovery of Galvani, interpreted it correctly, and perfected the method of producing electricity by chemical action. What these two men really discovered was that it is possible to produce continuous currents of electricity. Before that electricity was known only by the instantaneous discharge or spark. From the name of Volta is derived the word volt, which designates the unit of electro-motive force. The adjective _voltaic_ is synonymous with _galvanic_, as voltaic or galvanic cell, voltaic or galvanic current. For a long time it was thought that such an adjective was needed to designate electric currents generated by chemical action as a peculiar kind of electricity. We no longer think of electricity which is generated by chemical action as different from that generated by a dynamo or from any other source.