en much thought to the lead type of storage battery, and during the
course of three years had made a prodigious number of experiments in the
direction of improving it, probably performing more experiments in that
time than the aggregate of those of all other investigators. Even
in those early days he arrived at the conclusion that the
lead-sulphuric-acid combination was intrinsically wrong, and did not
embrace the elements of a permanent commercial device. He did not at
that time, however, engage in a serious search for another form of
storage battery, being tremendously occupied with his lighting system
and other matters.

It may here be noted, for the information of the lay reader, that the
lead-acid type of storage battery consists of two or more lead plates
immersed in dilute sulphuric acid and contained in a receptacle of
glass, hard rubber, or other special material not acted upon by acid.
The plates are prepared and "formed" in various ways, and the chemical
actions are similar to those above stated, the positive plate being
oxidized and the negative reduced during "charge," and reversed during
"discharge." This type of cell, however, has many serious disadvantages
inherent to its very nature. We will name a few of them briefly.
Constant dropping of fine particles of active material often causes
short-circuiting of the plates, and always necessitates occasional
washing out of cells; deterioration through "sulphation" if discharge
is continued too far or if recharging is not commenced quickly enough;
destruction of adjacent metalwork by the corrosive fumes given out
during charge and discharge; the tendency of lead plates to "buckle"
under certain conditions; the limitation to the use of glass, hard
rubber, or similar containers on account of the action of the acid; and
the immense weight for electrical capacity. The tremendously complex
nature of the chemical reactions which take place in the lead-acid
storage battery also renders it an easy prey to many troublesome
diseases.

In the year 1900, when Edison undertook to invent a storage battery, he
declared it should be a new type into which neither sulphuric nor
any other acid should enter. He said that the intimate and continued
companionship of an acid and a metal was unnatural, and incompatible
with the idea of durability and simplicity. He furthermore stated that
lead was an unmechanical metal for a battery, being heavy and lacking
stability and elasticity,