Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . plates are at-tached to little arches of wire, which enter smallholes in the zinc, into which they may be wedgedor from which they may be removed at the depositing cell, a daguerreotype plate, D, isseen attached by its edge to a screw-cup and clampprepared for that purpose, and thence connected withthe terminal zinc cylinder of the series, Z. Opposedto the daguerreotype plate, is a plate of silver, S, con-nected with the platinujn pole, P,
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . plates are at-tached to little arches of wire, which enter smallholes in the zinc, into which they may be wedgedor from which they may be removed at the depositing cell, a daguerreotype plate, D, isseen attached by its edge to a screw-cup and clampprepared for that purpose, and thence connected withthe terminal zinc cylinder of the series, Z. Opposedto the daguerreotype plate, is a plate of silver, S, con-nected with the platinujn pole, P, of the battery, and ELEC TRO —G IL D ING AND SILVERING. 63 which is dissolved by the sohition in proportion assilver is deposited on the daguerreotype plate. Avery pure coating of silver is thus given to a platefrom which the best pictures are obtained.^^ This fig. shows the porous cell belonging tothe battery when used as a Groves. Theuse of this cell, and of nitric acid within it,constitutes the difference between these Fig. 36 represents a series of the sulphateof copper battery applied to gilding and silvering. Fig, This may be used where a very large surface is to bedeposited upon. The figure is intended to illustratechiefly the deposition of alloys by the galvanic cur-rent. If two metals are contained in a solution, thegeneral law is, that the one most easily reduced bythe electrical process will be deposited first, and in astate almost absolutely pure. If the energy of thecurrent, however, is very much increased, all themetals present will go down in variable , if there is a little silver in the gold electrotypesolution, a feeble current will throw down the silverfirst; if there is copper present, and no silver, a G4 DAVISSMANUAL. feeble current will throw down a pure yellow depositof gold, while a stronger one will throw down areddish metal resembling the gold of jewellers andof the mint. 101. The salt of silver, used for precipitation,
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
