. Medical electricity; a practical treatise on the applications of electricity to medicine and surgery. t, no current proper is pro-duced. This serious objection to the use of commercialzinc in galvanic combinations has been entirely obviatedby a fortunate discovery. It has been found that if ordinarycommercial zinc is amalgamated, it is no longer acted onby the acid, except when the circuit is complete, and thesecondary currents between the impurities in the metaland the particles of zinc are entirely prevented. Theprocess of amalgamation consists in immersing the zinc indiluted sulphuric aci
. Medical electricity; a practical treatise on the applications of electricity to medicine and surgery. t, no current proper is pro-duced. This serious objection to the use of commercialzinc in galvanic combinations has been entirely obviatedby a fortunate discovery. It has been found that if ordinarycommercial zinc is amalgamated, it is no longer acted onby the acid, except when the circuit is complete, and thesecondary currents between the impurities in the metaland the particles of zinc are entirely prevented. Theprocess of amalgamation consists in immersing the zinc indiluted sulphuric acid, and then rubbing the clean surfacewith some mercury. Immediately the zinc assumes a 36 ELECTRO-PHYSICS. silvery brightness, and its surface becomes homogene- ous. To develop a galvanic current, there must be dissimilarmetals. Galvani supposed that the contact of dissimilarmetals was alone necessary, but it was soon discoveredthat one of the metals must be acted on. That dis-similar metals are essential is undoubted, for if two platesof zinc, or two plates of copper are employed, there is no Galvanic couplets and conjunctive wire. result—no current is produced. One of the plates mustbe acted on, and becomes the generating plate, whilst theother is the conducting plate. To complete the circuit, theplates are brought into contact, or are connected by a wireof varying length, the conjunctive wire (Fig. 10). If theamalgamated zinc and the copper plate are placed in theexciting fluid—diluted sulphuric acid—and are not con-nected, no effect is observed, but as soon as the circuitis completed by bringing the metals into contact, or byattaching a conjunctive wire, a very decided disturbanceis manifested ; bubbles of hydrogen gas arise from thedecomposition of the water, sulphate of zinc is producedand dissolves in the diluted acid, and a galvanic currentpasses. When the circuit is broken at any point, actionat once ceases. During the passage of the current, the conjunctiv
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectelectro, bookyear1887
