galvanism

[Named after Aloysius Gal. van i, who was born at Bologna in 1737, published in 1791 his celebrated work, Aloysii Galvanii de viribus Electric it at is in Motu Muscular i Com men tar i us, Physics: The branch of electric science to which and died in his native town in 1798.] an experiment by Galvani gave birth. His wife, who was making soup from frogs, happened to put them, after being skinned, in proximity to a charged electrical machine belonging to her husband. On touching them with a scalpel their legs became greatly convulsed. Galvani on his return was told what had occurred, and repeated the experiment on several occasions. He united the lumbar nerves of a dead frog with its crural muscles by a metallic circuit. He came to the erroneous conclusion that animal electricity existed in the nerves and muscles of frogs, . In this explanation Galvani ignored the metallic connecting wire. His contemporary, Volta, gave attention to this, and found that the contraction of the limbs is more energetic when the connecting arc is made of two metals instead of one. He therefore inferred that the metals took the active part in producing the contraction, and the disengagement of electricity was due to their contact, and that the animal parts constituted only a conductor, and at the same time a very sensitive electroscope. In 1793 he published these views, and in 1800 first described and constructed what has since been called after him the Voltaic pile. [PILE; see also BATTERY, B. III. 4.] Febroni, observing that the discs of zinc in the pile became oxidized in contact with the acidulated water, considered, as did Woo last on and Davy, that the oxidation was the chief cause why electricity was disengaged. Now Voltaic piles have nearly given place to Voltaic or Galvanic batteries, of which there are many varieties. [BATTERY, B. III. 4.] gal-van-ist, s. [Ital. Galvan ( i ); Eng., ., suff. -ist.] A proficient in galvanism. IMG:content-0300.jpg:[blocks in formation] duced by galvanography (q. v.). Engraving : A proce of Austrian origin, by which a plate of silvered copper is covered by an artist with different coats of a somewhat transparent pigment, so that on the dark portions the paint is thick and raised, and the surface is relatively depre ed in the light tints. A copy of this is made by the electrotype proce ; the darker being now the deeper portions, the whole forms an intaglio, like a copperplate, and is printed from by the cop per plate-printing proce .