Knowledge; A Monthly Record of Science Volume 2

Knowledge; A Monthly Record of Science Volume 2

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1905 edition. Excerpt: ...tons. The reproduction of a statue, as may readily be imagined, is not by any means an easy or simple proceeding. Generally speaking, the original is first formed in plaster of Paris. The plaster cast is then thoroughly saturated with boiled linseed oil or with melted paraffin wax. After standing for some time to allow the oil or wax to thoroughly set and harden, the entire surface is brushed over with graphite, and is then polished, so as to form a homogeneous conducting surface. The model so prepared has conducting wires fixed against different portions of the surface, so that the electric current may be evenly distributed, and is then connected with the negative pole of the source of current and placed in a copper sulphate bath. When a coating of sufficient thickness has been obtained--about or more of an inch--the figure is removed from the bath and carefully washed. It is now necessary to remove the plaster form, and this is done by cutting the deposited copper in appropriate parts, so that the copper shell can be removed in portions. The fewer cuts that require to be made, the better, so that the portions of shell may be as large as possible. The parts or "formes" of the copper shell so obtained represent the negatives or moulds upon which the positive is to be deposited. The inner portion of the formes are exposed to the fumes of sulphuretted hydrogen or are washed with a dilute solution of potassium sulphide. By this means the copper becomes coated with a thin film of copper sulphide, which is conducting, but upon which the copper to be deposited will not adhere. The outer surfaces of the mould are varnished to render them non-conducting. The various portions of the shell are then placed in a coppering bath and the current...show more

Product details

  • Paperback | 268 pages
  • 189 x 246 x 14mm | 485g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236523784
  • 9781236523785