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History of electric light

Chapter 15: GROVE’S BATTERY
By Henry Schroeder
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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.

GROVE’S BATTERY

Sir William Robert Grove, an English Judge and scientist, invented a cell in 1838 consisting of a platinum electrode in strong nitric acid in a porous earthenware jar. This jar was put in dilute sulphuric acid in a glass jar in which there was an amalgamated zinc plate for the other electrode. This had an open circuit voltage of about 1.9 volts. The porous jar was used to prevent the nitric acid from attacking the zinc. The nitric acid was used for the purpose of combining with the hydrogen gas set free by the action of the sulphuric acid on the zinc, and hence was the depolarizing agent. Hydrogen combining with nitric acid forms nitrous peroxide and water. Part of the nitrous peroxide is dissolved in the water, and the rest escapes as fumes which, however, are very suffocating.

The chemical equations of this cell are as follows:

In outer glass jar: Zn + H2SO4 = ZnSO4 + H2
In inner porous jar: H2 + 2HNO3 = N2O4 + 2H2O

An interesting thing about Grove’s cell is that it was planned in accordance with a theory. Grove knew that the electrical energy of the zinc-sulphuric acid cell came from the chemical affinity of the two reagents, and if the hydrogen gas set free could be combined with oxygen (to form water—H2O), such chemical affinity should increase the strength of the cell. As the hydrogen gas appears at the other electrode, the oxidizing agent should surround that electrode. Nitric acid was known at that time as one of the most powerful oxidizing liquids, but as it attacks copper, he used platinum for the other electrode. Thus he not only overcame the difficulty of polarization by the hydrogen gas, but also increased the voltage of the cell by the added chemical action of the combination of hydrogen and oxygen.