High frequency currents : their production, physical properties, physiological effects, and therapeutical uses / by H. Evelyn Crook.

  • Crook, H. Evelyn (Herbert Evelyn)
Date:
1909
Catalogue details

Licence: Public Domain Mark

Credit: High frequency currents : their production, physical properties, physiological effects, and therapeutical uses / by H. Evelyn Crook. Source: Wellcome Collection.

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    The secondary battery, or, as it is usually called, an accumulator, consists of two plates of lead immersed in diluted sulphuric acid which has a specific gravity of about 1°15. The sulphuric acid causes a thin layer of sulphate of lead to form on the plates. If an electrical current be passed through the cell, the sulphate of lead connected to the positive pole is changed to peroxide of lead and bubbles of oxygen are formed, while the sulphate FIG. 2.—PORTABLE ACCUMULATOR (SECONDARY BATTERY). upon the plate connected with the negative pole is con- verted into spongy metallic lead and hydrogen appears in bubbles. When the cell is connected to a supply of electrical current—that is to say, is being charged—the bubbles of oxygen and hydrogen rise to the surface and give the solution a milky appearance, this being one of the means by which it is possible to know when the accumulator is fully charged. If the plates are now connected to a con- ductor, an electrical current will flow in the opposite direction to that which previously charged the cell, and
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