A History of Inventions, Discoveries, and Origins. Johann Beckmann
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Название: A History of Inventions, Discoveries, and Origins

Автор: Johann Beckmann

Издательство: Bookwire

Жанр: Документальная литература

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isbn: 4064066382865

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СКАЧАТЬ outline may however not prove uninteresting to the reader:—It had long been known to experimentalists on the chemical action of voltaic electricity, that solutions of several metallic salts were decomposed by its agency, and the metal produced in its free state. The precipitation of copper by the voltaic current was noticed by Mr. Nicholsona in a paper entitled ‘Account of the new Electrical Apparatus of Sig. Alex. Volta, and experiments performed with the same;’ but the earliest recorded process in electro-gilding is probably that contained in a letter from Brugnatelli to Van Monsb, in which he states that he had deposited a film of gold on ten silver medals by bringing them into communication by means of a steel wire with the negative pole of a voltaic pile, and keeping them one after the other immersed in ammoniuret of gold newly made and well-saturated. This announcement of a process identical with those now extensively used, attracted no attention at the time it was made, and no further experiments on the application of electricity to the deposition of metals for the purposes of the arts were published until the year 1830, when Mr. E. Davy read a paper before the Royal Society, in which he distinctly states that he had gilded, silvered, coppered and tinned various metals by the voltaic batteryc. The experiments of Brugnatelli and Davy were however completely lost sight of, and the art may be said to date its origin from the period when the late Professor Daniell described his constant battery. Since that time the art has continued to advance most rapidly, either in the perfecting of the apparatus or in the pointing out of more suitable salts of gold and silver, from which the metals might be precipitated. Among those who have contributed to its advancement we may particularly instance the names of our countrymen, Woolrich, Spencer, Jordan, Mason, Murray, Smee, Elkington, Fox Talbot, and Tuck. Nearly all the gilt articles manufactured at Birmingham are now gilded by the process patented by Mr. Elkington, in which, after the articles have been cleansed by a weak acid, they are placed in a hot solution of nitro-muriate of gold, to which a considerable excess of bicarbonate of potash has been added; in the course of a few seconds they thus receive a beautiful and permanent coating of gold.]

      COLD OR DRY GILDING.

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      Dry gilding, as it is called by some workmen, is a light method of gilding, by steeping linen rags in a solution of gold, then burning them; and with a piece of cloth dipped in salt water, rubbing the ashes over silver intended to be gilt. This method requires neither much labour nor much gold, and may be employed with advantage for carved work and ornaments. It is however not durable.

      I am of opinion that this manner of gilding is a German invention, and that foreigners, at least the English, were first made acquainted with it about the end of the last century; for Robert Southwell describes it in the Philosophical Transactions for the year 1698, and says that it was known to very few goldsmiths in Germany.

      GOLD VARNISH.

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      This ingenious process, which at present is employed all over Europe in gilding wooden frames, coaches, and various articles, and which was formerly used in the preparation of the now old-fashioned leather tapestry, was invented towards the end of the 17th century. Anderson, in his Historical and chronological deduction of the Origin of Commerce, says that it was introduced into England by one Evelyn in the year 1633; and quotes, in support of this assertion, The Present State of England, printed in 1683.

      “Take shell-lac, and having freed it from the filth and bits СКАЧАТЬ