A supplement to Ures Dictionary of Arts, Manufactures, and Mines, : containing a clear exposition of their principles and practice. . the surface of the mould with a piece of woolon a soft brush, care being taken to continue it as far as to the conducting wire, by whichthe mould is connected with the zinc. With moulds of solid metal, the deposit of coppercommences throughout the entire surface at once ; but, with moulds having only a film ofplumbago for a conductor, the action commences at the wire, and extends itself graduallyuntil it has been developed on all parts of the surface. The nature
A supplement to Ures Dictionary of Arts, Manufactures, and Mines, : containing a clear exposition of their principles and practice. . the surface of the mould with a piece of woolon a soft brush, care being taken to continue it as far as to the conducting wire, by whichthe mould is connected with the zinc. With moulds of solid metal, the deposit of coppercommences throughout the entire surface at once ; but, with moulds having only a film ofplumbago for a conductor, the action commences at the wire, and extends itself graduallyuntil it has been developed on all parts of the surface. The nature of the electro-chemical decompositions that are due to the passage of voltaiccun-ents through liquids, especially through liquids in which metal is in certain forms con-tained, can be best understood by studying the arrangement that is most commonly used inthe arts, wherein the voltaic apparatus, from which the electric current is obtained, is dis-tinct and separate from the vessel in which the electro-metallurgical operations are beingbrought about. Such an arrangement is shown in ji(j. 261, where a is a DanieUs cell, as 2G1. in fig. 259 ; and b a trough filled with an acid soliitioa of sulphate of copper; m is a metalrod, on which the moulds are hung; and c a metal rod, upon wliicli plates of copper archung facing the moulds; the copper-plates are connected by the wire z with the coiii)cr ofthe battery cell, and tlie moulds by the wire x with the zinc rod. The voltaic current isgenerated in the cell a, and its direction is from the zinc rod, through the solutions to thecopper of the coll; thence by the wire ,? to the plates of copper c; through the sulphatesolution to the moulds m ; and thence by the wire x to the zinc rod. In this arrangement,no slielf is necessary in the trough n for crystals of sulphate of copper to keej) up thestrength of the solution ; for the nature of tiie clectro-clicmical decompositions is such,that in proportion as copper is al)stracted and deposit
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Keywords: ., bookcentury1800, bookdecade1860, bookpublishernewyo, bookyear1864
