Dental chemistry and metallurgy / Clifford Mitchell.

  • Mitchell, Clifford, 1854-1939.
Date:
1893
Catalogue details

Licence: Public Domain Mark

Credit: Dental chemistry and metallurgy / Clifford Mitchell. Source: Wellcome Collection.

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    All chemical change produces electricity. This kind of electricity is called voltaic or gal- vanic, and is most often developed by chemi- cal action between liquids and metals. Ex- ample: when a strip of copper and a strip of zinc are placed in dilute sulphuric acid, a cur- rent of electricity will be found to flow in a wire connecting the two strips of metal above the acid. The apparatus is called a galvanic element or cell. 83. Current of Electricity.—In every gal- vanic cell, the plates and connecting wires must be conductors of electricity and the liquid used must be one which will act with greater vigor on one of the metals than on the other. The metal most actively attacked by the liquid forms the -positive or generating plate; the other, the collecting or negative plate. The current runs in the liquid from the positive plate to the negative; in the wire connecting the plates the current runs from the negative plate to the positive. 84. Closed Circuit. —When wires from the two plates are in contact. When not, the circuit is broken., 85. Electrodes.—Ends of the wires. Also called The negative pole is attached to the positive plate and vice versa. Platinum strips are often fastened to the ends of wires and constitute the electrodes, and the wires are called rheophores. 86. Galvanic Battery. — A number of galvanic ele- ments so connected that the current has the same direc-