[28] [Among the improvements of recent date there are perhaps none
of greater importance than those of electro-gilding and gilding by
immersion, which have almost entirely superseded the process of gilding
by an amalgam of mercury and gold, so fatal to the workmen exposed
to the deleterious effects of the mercurial vapours. It is not our
intention to enter at present into a history of the invention of these
processes; they will more properly be reserved for a future volume,
in which the discoveries of the present century will be treated of.
The following short 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. Nicholson[a] 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 Mons[b],
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 battery[c]. 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.]
[a] Nicholson’s Journal, July 1800, p. 179.
[b] Philosophical Magazine, 1805.
[c] Phil. Trans. 1831, p. 147.
[29] Lib. xxxiii. cap. 6.
[30] Vit. lib. vii. c. 8.
[31] In Origin. lib. xvi. c. 18.
[32] De Aurilegio, præcipue in Rheno. Argent. 1776.
[33] Historia naturale e morale delle Indie. Venetia, 1596.
[34] The same account as that given by Acosta may be seen in Garcilasso
de la Vega, Commentarios reales; Lisboa 1609, p. 225; in Rycaut’s
English translation, London 1688, fol. i. p. 347; and in De Laet, Novus
Orbis, Lugd. Bat. 1633, fol. p. 447.
[35] Vol. i. p. 414.
[36] Hakluyt’s Collection of Voyages. London, 1600, fol. vol. iii. p.
466.
[37] See La France littéraire. Paris, 1769, 2 vols. 8vo, vol. ii. p.
410.