WeRead Powered by ReaderPub
History of electric light cover

History of electric light

Chapter 10: IMPROVEMENT OF VOLTA’S BATTERY
By Henry Schroeder
Open in WeRead

Explore more books like this:

Engineering & TechnologyHistory - Modern (1750+)

About This Book

A chronological, technical survey of electric lighting traces developments from early experiments with friction machines, Leyden jars and voltaic piles through advances in batteries, electromagnetic discoveries and the invention of the dynamo. It follows the parallel evolution of arc and incandescent illumination, outlining experimental filament and arc-control methods and the move to commercial installations and distribution schemes such as series, multiple and three‑wire systems. Later sections review later lamp technologies—Nernst, mercury‑vapor, gas‑filled and tungsten types—together with transformers, rectifiers, standardized voltages and sockets. The book is illustrated and includes a chronology, cost and usage statistics, and a selected bibliography.

IMPROVEMENT OF VOLTA’S BATTERY

It was early suggested that sheets of silver and zinc be soldered together back to back and that a trough be divided into cells by these bimetal sheets being put into grooves cut in the sides and bottom of the trough. This is the reason why one unit of a battery is called a “cell.” It was soon found that a more powerful cell could be made if copper, zinc and dilute sulphuric acid were used. The zinc is dissolved by the acid forming zinc sulphate and hydrogen gas, thus:

Zn + H2SO4 = ZnSO4 + H2

The hydrogen gas appears as bubbles on the copper and reduces the open circuit voltage (about 0.8 volt per cell) as current is taken from the battery. This is called “polarization.” Owing to minute impurities in the zinc, it is attacked by the acid even when no current is taken from the battery, the impurities forming with the zinc a short circuited local cell. This is called “local action,” and this difficulty was at first overcome by removing the zinc from the acid when the battery was not in use.