To judge by two of the German editions, Gobet has done Barba an injustice. In that of 1676, I find Barba expressly says he does not believe the ancients were acquainted with the art of extracting silver from pounded ore by the means of quicksilver. This certainly does not indicate that he laid claim to the invention; besides, he everywhere speaks of amalgamation as an art long used in America, but complains of the negligence with which it was practised. In a passage however in the Vienna edition, and which has probably been added by Gobet, we are told that in the year 1609, Barba attempted to fix quicksilver, and with that view bethought himself of mixing it with finely pounded silver ore; that he at first imagined, with surprise, that he had obtained a mass of silver, but that he soon perceived that the mercury was not changed into silver, but had only attracted the particles of that metal. “I was,” adds Barba, “highly pleased with my new discovery of managing ore, of extracting its contents, and of refining it; and this method I continued to practise.” I imagine that Barba was still in Europe in 1609, and made that experiment before he was acquainted with the smelting-works in America. I am however of opinion, that one will see by the original that Barba did not wish to claim the invention of amalgamation as practised in the mines of America. FOOTNOTES [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perhaps none of greater importance than those of electro-gilding and gilding by immersion, which have almost entirely superseded the process of gilding by an amalgam of mercury and gold, so fatal to the workmen exposed to the deleterious effects of the mercurial vapours.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