At present considerable quantities of verdigris are manufactured at Montpelier in France, and by processes more advantageous than those known to the ancients[466]. The dried stalks of grapes are steeped in strong wine, and with it brought to a sour fermentation. When the fermentation has ceased, they are put into an earthen pot, in alternate layers with plates of copper, the surface of which in a few days is corroded by the acetic acid, and the salt is then scraped off. It is certain, that, even in the fifteenth century, the making of verdigris was an old and profitable branch of commerce in France. The city of Montpelier having been obliged to expend large sums in erecting more extensive buildings to carry it on, and having had very small profits for some years before, received by letters patent from Charles VI., in 1411, permission to demand sixteen sous for every hundred weight of verdigris made there. In later times this trade has decayed very much. Between the years 1748 and 1755, from nine to ten thousand quintals were manufactured annually, by which the proprietors had a clear profit of 50,000 crowns; but a sudden change seems to have taken place, for in 1759 the quantity manufactured was estimated at only three thousand quintals. This quantity required 630 quintals of copper, valued at 78,750 livres: the expenses of labour amounted to 1323 livres; the necessary quantity of wine, 1033 measures, to 46,485 livres, and extraordinaries to 10,330 livres; so that the three thousand quintals cost the manufacturers about 136,888 livres. In the year 1759, the pound of verdigris sold for nine sous six deniers: so that the three thousand quintals produced 142,500 livres, which gave a net profit of only 5612 livres. Other nations, who till that period had purchased at least three-fourths of the French verdigris, made a variety of experiments in order to discover a method of corroding copper which might be cheaper; and some have so far succeeded that they can supply themselves without the French paint in cases of necessity[467]. In commerce there is a kind of this substance known under the name of distilled verdigris, which is nothing else than verdigris purified, and crystallized by being again dissolved in vinegar[468]. For a considerable period this article was manufactured solely by the Dutch, and affords an additional example of the industry of that people. Formerly there was only one person at Grenoble acquainted with this art, which he kept secret and practised alone; but for some years past manufactories of the same kind have been established in various parts of Europe.