Over the past few months, as I learned more and more about the use of quicksilver in eighteenth-century chemistry and medicine, I became increasingly curious about the origins of all this mercury. The chemistry of the eighteenth century was a science of materials, materials that allowed various ways of inquiry: descriptions were made, technological possibilities explored and philosophical reasoning applied. However, we should not forget that in early classical chemistry, all chemical substances were useful materials produced in mining, metallurgy and pharmacy. So where did a useful chemical material like mercury come from? In his book De Mercurio Experimenta, Boerhaave mentioned that he acquired sixteen ounces of quicksilver for his experiments at ‘the Company at Amsterdam.‘
That must have been one famous company, if Boerhaave only needed to refer to it as ‘the Company at Amsterdam’ in the transactions of the Royal Society. It was indeed. I soon found out that at the time Boerhaave was writing this, the company of the Amsterdam Deutz family had almost exclusive rights to the trade in mercury in the Low Countries, and even in Europe. The most important quicksilver mines in Europe were those in Idria in the Habsburg Empire (now in Slovenia and spelled Idrija).
In the mid-seventeenth century, the Habsburg emperor monopolised the entire mercury mining and trade business of Idria, and in 1669 appointed a limited number of ‘factors’ in Venice and Amsterdam, who had the exclusive right to trade the imperial mercury. This situation would persist more or less unchallenged until 1741.
The Amsterdam factor was Jean Deutz (1618-1673), a rich merchant originally from Cologne. After his death, first his son Jean (1655-1719) and subsequently his grandson Willem Gideon (1697-1757) took over the factorship. Because of the their monopoly, Amsterdam was the international trade centre for mercury, and the production centre of vermilion (a red dyestuff produced from sulphur and mercury) and mercurial salts in Boerhaave’s time. Although local apothecaries and assayers would also stock mercury, for the relatively large amount of pure mercury Boerhaave required – 16 ounces, which, in today’s weight, would be almost 500 grams -, the Amsterdam company was apparently the most trusted supplier.
However, in Deutz’s perspective, 16 ounces was hardly business. Mercury was used in
much larger quantities in all kinds of industries, such as felting (done by hat makers who frequently suffered mercury poisoning, hence the expression ‘mad as a hatter’), glass and mirror making and the dye industry. But the price of mercury was largely defined by the demand of the mining industry, as mercury was used to mine gold and silver. Deutz gave massive loans to the Emperor, in return for which he would receive a set amount of mercury each year, which he sold for huge profits. Around 1706, when the Amsterdam monopoly was somewhat shaken by English imports of mercury from China, the sales of eight hundred 150 pound kegs of quicksilver a year still supplied the Deutz company with an annual income of about 225,000 guilders.
 Klein, Ursula, en Wolfgang Lefèvre. Materials in Eighteenth-Century Science. A Historical Ontology. Cambridge, MA: MIT Press, 2007, 1,2. Klein, Ursula. “Objects of inquiry in classical chemistry: material substances”. Foundations of chemistry: philosophical, historical and interdisciplinary studies of chemistry 14, nr. 1 (april 2012): 7–23, 13-14.
 Boerhaave, Herman. Some experiments concerning mercury. By J.H. Boerhaave, professor of physick at Leyden. Translated from the Latin, communicated by the author to the Royal Society 1734. (London: J. Roberts, 1734), 16.
 By purchasing the complete stock of the Venice factor, Deutz created a virtual monopoly. See H.W. Lintsen (ed.), Geschiedenis van de techniek in Nederland. De wording van een moderne samenleving 1800-1890. Deel IV. Delfstoffen, machine- en scheepsbouw. Stoom. Chemie. Telegrafie en telefonie. (Walburg Pers, Zutphen 1993), 161, and C.K. Kesler, “Amsterdamsche Bankiers in de West in de 18e Eeuw”. Nieuwe West-Indische Gids 8, nr. 1 (1927: 499–516), 503-4.
 Mercury was, and is still sometimes used to extract gold or silver from ores. See http://www.miningfacts.org/Environment/Does-mining-use-mercury/
 Elias, Johan E. De Vroedschap van Amsterdam, 1578-1795. Vol. 2. 2 vols. Haarlem: Vincent Loosjes, 1905, 1046-50.