A History of Inventions and Discoveries: Verdigrise, or Spanish Green.
A History of Inventions and Discoveries.
By John Beckmann,
Public professor of economy in the University of Gottingen.
Translated from the German, by William Johnston.
Third edition, carefully corrected, enlarged by the addition of several new articles.
In four volumes.
Printed for Longman, Hurst, Rees, Orme, and Brown; Baldwin, Cradock, and Joy; R. Priestley; R. Scholey; T. Hamilton; W. Otridge; J. Walker; R. Fenner; J. Bell; J. Booker; E. Edwards; and J. Harding.
* Dioscorid. lib. v. cap. 91, 92. Theophrastus de lapidibus, edit. Heinsii, p. 399. Plin. lib. xxxiv. cap. 11, 12. Oribasius, Medie. collect. lib. xiii. Stephani Medicæ artis principes, p. 453. Vitruv. lib. vii. cap. 12.
*2 Bruckmann, Epistolæ itinerar, cent. i. p. 76.
*3 Delius, Anleitung zur Bergbaukunst. Wien, 1773, 4to. p. 425. Respecting the preparation of verdigrise, various and in part contradictory opinions have been entertained; and at present, when it is with certainty known, it appears that the process is almost the same as that employed in the time of Theophrastus, Dioscorides, and Vitruvius. * At that period, however, every natural green copper calx was comprehended under the name of ærugo. Dioscorides and Pliny say expressly, that a substance of the nature of those stones which yielded copper when fused, was scraped off in the mines of Cyprus; as is still practised in Hungary, where the outer coat of the copper ore is collected in the like manner, and afterwards purified by being washed in water. *2 Another species, according to the account of Dioscorides, was procured from the water of a grotto in the same island; and the most saleable natural verdigrise is still collected by a similar method in Hungary. The clear water which runs from old copper-works is put into large vessels, and after some time the green earth falls to the bottom as a sediment. *3
* Dioscorides: --- Plinius: Squame, delimata æris scobs.
*2 Dioscorides: ----
*3 Plinius: vinacea. Dioscorides: --- Theophrastus: --- .The last word has various meanings: sometimes it signifies squeezed grapes; sometimes wine lees, &c. of which Niclas gives examples, in his Observations on Geop. lib. vi. c. 13. p. 457; but it can never be translated by amurca, though that word is used by Furlanus, the translator of Theophrastus. The old glossary says, ----- . Oil, however, has nothing to do with verdigrise.
*4 This kind was called therefore ------, ærugo rasilis.
*5 ------ , atramentum sutorium. The artificial ærugo of the ancients, however, was out verdigrise, or copper converted into a green calx by vinous acid. To discover the method of procuring this substance could not be difficult, as that metal contracts a green rust oftener than is wished, when in the least exposed to acids. The ancients, for this purpose, used either vessels and plates of copper, or only shavings and filings; *2 and the acid they employed was either the sourest vinegar *2 or the sour remains left when they made wine: such as grapes become sour, or the stalks and skins after the juice had been pressed from them. *3 Sometimes the copper was only exposed to the vapour of vinegar in close vessels, so that it did not come into immediate contact with the acid, in the same manner as was practised with plates of lead in the time of Theophrastus, when white-lead was made, and as is still practised at present. Sometimes the metal was entirely covered with vinegar, or frequently besprinkled with it, and the green rust was from time to time scraped off;*4 and sometimes copper filings were pounded with vinegar in a copper mortar, till they were changed into the wished-for green calx. This article was frequently adulterated, sometimes with stones, particularly pumice-stone reduced to powder, and sometimes with copperas. *5 The first deception was easily discovered; and to detect the second, nothing was necessary but roast the verdigrise, which betrayed the iron by becoming red; or to add to the verdigrise some gall-nut, the astringent particles of which, united with the ferruginous vitriol of the copperas, formed an ink, which communicated a black colour to paper dipped into it.
* ----- ærugo scolacea, or vermicularis.
*2 Should this explanation be just, we ought for æruca, the name given by Vitruvius to verdigrise, to read eruga: though the conjecture of Marcellus Vergilius (Dioscorides, interprete Mar. Vergilio. Coloniæ 1529, fol. p. 656), that the reading should be anea or ærea, is no less probable; for by this epithet its difference from ærugo ferri was frequently distinguished. In early periods verdigrise was used principally for making plasters, and for other medicinal purposes; but it was employed also as a colour, and on that account it is by Vitruvius reckoned among the pigments. When applied to the former purpose, it appears that the copper calx was mixed with various salts and other ingredients. One mixture of this kind was called vermicular verdigrise,* the accounts of which in ancient authors seem to some commertators to be obscure; but in my opinion we are to understand by them, that the ingredients were pounded together till the paste they formed assumed the appearance of pieces or threads like worms; and that from this resemblance they obtained their name. For the same reason the Italians give the name of vermicelli to wire-drawn paste of flour used in cookery.*2 When the process for making this kind of verdigrise did not succeed, the workmen frequently added gum to it, by which the paste was rendered more viscous; but this mixture is censured both by Pliny and Dioscorides. It appears that the greater part of the verdigrise in ancient times was made in Cyprus, which was celebrated for its copper-works, and in the island of Rhodes.
*The latest writers on this art are mentioned in Weigel's Chemie, p. 527, and Krünitz, Ockonom. Encycloped. xx. p. 241.
*2 This is mentioned by Serane in his treatise, a translation of which may be found in the Mineralogischen Belustigungen, ii. p. 251.
*3 Journal oeconom. 1759, p. 311 At present the greater part of our verdigrise is manufactured at Montpellier in France, and by processes more advantageous than those known to the ancients. 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 vinous acid, and the calx is then scraped off.* The manufacturers of this article use only Swedish copper, for which they send to Hamburgh; and it is believed that no wine is so proper for the above purpose as that of Languedoc. However this may be, it is certain, that, even in the fifteenth century, the making of verdigrise was on old and profitable branch of commerce in France. The city of Montpellier having been obliged to expand 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 verdigrise made there.*2 In latter 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 1,323 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 verdigrise sold for nine sous six deniers; so that the three thousand quintals produced 142,500 livres, which have a neat profit of only 5612 livres.*3 Other nations, who till that period had purchased at least three-fourths of the French verdigrise, made a variety of experiments in order to discover a method of corroding copper by mineral acid, which might be cheaper; and some have so far succeeded that they can supply themselves without the French paint in cases of necessity. As one instance, I shall mention only the verdigrise manufactured by Gravenhorst and brothers at Brusnwick.
* An account of the method of making distilled verdigrise may be found in the following works; L'art du distillateur d'eaux-fortes, par Demachy. Paris, 1773, fol. p. 168. Mémoires de l'Academ. des Sciences à Paris, année 1776. p. 724.
*2 Frisch's Worterbuch, p. 291. In the works of George Agricola, printed together at Basle 1546, fol. we find in page 473, where the terms of art are explained: Ærugo, Grünspan, or Spansch-grün, quod primo ab Hispanis ad Germanos sit allata; barbari nominant viride æ:;ris.
*3 By Conrad Zeniger Nuremberg. In that scarce work, Josua Maaler, Teutsche Sprach oder Dictonarium Germano-Latinum, Zurich 1561, 4to. arugo is called Spangrüne. In commerce there is a kind of this substance known under the name of distilled verdigrise, which properly is nothing else than verdigrise purified, and somewhat crystallized by being again dissolved in vinegar. This article has been hitherto manufactured 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 there have been manufactories of the same kind at Montpellier, and another has been established at Paris by Baumé.*
The German name of verdigrise (spangrün) has by most authors been translated Spanish green; and it has thence been concluded that we received that paint first from the Spaniards. This word and the explanation of it are both old; for we find ærugo, and viride Hispanicum translated Spangrün, Spongrün, or Spansgrün, in many of the earliest dictionaries,*2 such as that printed in 1480.*3 For this meaning, however, I know no other proof than the above etymology, which carries with it very little probability; and I do not remember that I ever read in any other works than verdigrise first came from Spaniards.