Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . l heat is not used. When asufficient thickness has been attained, the copy maygenerally be removed from the mould without dif-ficulty, care being taken to cut away any copperwhich embraces the mould at the edges. 92. Every ounce of copper deposited requires thesolution of somewhat more than an ounce of zincfrom the zinc plate of the battery. Five or six elec-trotypes may be made at once, without increasingthis expense, by arranging in succession sever
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . l heat is not used. When asufficient thickness has been attained, the copy maygenerally be removed from the mould without dif-ficulty, care being taken to cut away any copperwhich embraces the mould at the edges. 92. Every ounce of copper deposited requires thesolution of somewhat more than an ounce of zincfrom the zinc plate of the battery. Five or six elec-trotypes may be made at once, without increasingthis expense, by arranging in succession several ves-sels, each containing a mould and a copper plate con- 58 DAVIS S MANUAL. nected by a wire with the mould in the next oneThe plates of copper and the moulds should all benearly of the same size^ and the solution should con-tain less blue vitriol and more sulphuric acid thandirected in <^ 88, particularly if the series extendbeyond two or three. When the moulds are small,glass tumblers form the most convenient 33 illustrates this arrangement, in which onebattery is seen connected with three depositing cells. Fis:. The moulds will be observed to occupy the sameposition in relation to the current in each of the copper plates opposed to the moulds are dis-solved in proportion to the amount of copper de-posited, so that the solutions retain their strengthby the recomposition of sulphate of copper, exactlyequal to the decomposition at the surface of themoulds. The increase of the number of cells re-quires, therefore, no increase of electrical energy,except for the greater distance through the solutionswhich the galvanic current has to pass. In this wayseveral ounces of copper are obtained, with but a ELECTRO — ETCHING. 59 slight increase in the quantity of acid or blue vitriolrequired for working the battery, and a little morecorrosion of the zmc plate. 93. The surface of the electrotype copy is usuallyof a bright copper color; but sometimes it
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
