. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. ELECTEIC WAVE TELEGRAPHY FLEMING. 181 in the United States by Fessenden, and called by him a liquid barret- ter. It was independently discovered, and described shortly after- wards in Germany by W. Schloemilch, and is generally there called the electrolytic detector. (See fig. 12.) It consists of an electrolytic cell or vessel containing some electrolyte, iisnallj^ nitric acid. In it are placed two electrodes, one a metal or carbon plate of
. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. ELECTEIC WAVE TELEGRAPHY FLEMING. 181 in the United States by Fessenden, and called by him a liquid barret- ter. It was independently discovered, and described shortly after- wards in Germany by W. Schloemilch, and is generally there called the electrolytic detector. (See fig. 12.) It consists of an electrolytic cell or vessel containing some electrolyte, iisnallj^ nitric acid. In it are placed two electrodes, one a metal or carbon plate of large surface, and the other an extremely fine platinum wire prepared by the Wol- laston process, a very short length of which is immersed in the liquid. A convenient plan is to prepare a AVollaston wire of silver, having a core of platinum which is drawn down until the latter is only one one-thousandth of a millimeter in diameter. If the electrolyte is strong nitric acid, then when the above wire is immersed to the depth of a millimeter the acid dissolves off the silver and leaves the fine platinum wire exposed as an electrode. This cell has its two elec- trodes connected respectively to a receiving antenna, and an earth plate, and also to a circuit containing a shunted voltaic cell and a tele- phone. (See fig. 12A.) The voltaic cell sends a current through the electrolyte in such a direction as to make the fine wire the positive electrode or anode. Some dispute has taken place whether the cell will work when the fine wire is the nega- tive electrode. Fessenden, who adopts a thermal theory of the cell, claims with Rothmund and Lessing that it is equally sen- sitive, whether the small elec- trode is positive or negative. According to one theory, the action of the cell as a wave de- tector depends on the power of the oscillations to remove the so-called polarization of the electrodes or adhering films of ions. Ac- cording to another theory it is due to the heating action of the
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