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TABLE OF CONTENTS

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CHAPTER I

Chemical Producers of Electricity-Action of Simple Primary Battery

The Dry Cell-Methods of Connecting Dry Cells-Discovery of Re-
versible Chemical Action-Secondary Batteries—Simple Lead Plate
Type-Planté, or Formed Plates-Faure, or Pasted Plates—Edison
Non-acid Battery Action.

Current Production by Chemical Action.-The earliest known method of continuous current generation is by various forms of chemical current producers, which may be either primary or secondary in character. A simple form of cell is shown in section at Fig. 1, A, and as the action of all devices of this character is based on the same principles, it will be well to consider the method of producing electricity by the chemical action of a fluid upon a metal. The simple cell shown consists of a container which is filled with an electrolyte, which may be either an alkaline or acid solution. Immersed in the liquid are two plates of metal, one being of copper, the other zinc. A wire is attached to each plate by means of suitable screw terminals.

If the ends of the plates which are not immersed in the solution are joined together a chemical action will take place between the electrolyte and the zinc plate; in fact, any form of cell consists of dissimilar elements which are capable of conducting electricity immersed in a liquid, which will act on one of them more than the other. The chemical action of electrolyte on the zinc liberates gas bubbles, which are charged with electricity and which deposit themselves on the copper plate. The copper element serves merely as a collecting member, and is termed the “negative" plate, while the zinc which is acted upon by the solution is termed the “positive” member. The flow of current is from the zinc to the copper plate through the electrolyte, and it is returned from the copper plate to the zinc element by the wiring which comprises the external circuit. The terminal on the cop

per plate is known as the “positive," that on the zinc is called the "negative.”

While in the cell shown zinc and copper are used, any other combination of metals between which there exists a difference in electrical condition when one of them is acted upon by a salt or acid may be employed. Any salt or acid solution will act as an electrolyte if it will combine chemically with one of the ele

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Fig. 1.-Types of Chemical Producers. A-Elementary Primary Cell.

B—Construction of Dry Cell. C—Simple Form of Secondary Battery. D—The Lead Plate Roll and How It is Made.

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