Tag Archives: chemistry

The “Gentle Heat” of Boerhaave’s Little Furnace

By Ruben Verwaal and Marieke Hendriksen

Ruben Verwaal is curator of the historical collections at Erasmus Medical Centre, Rotterdam, and at the Museum for Communication in The Hague. He obtained his PhD in June 2018 with a thesis on the role of bodily fluids in eighteenth-century chemistry. Marieke Hendriksen is a postdoctoral researcher on the Artechne Project at Utrecht University and a long-time contributor to The Recipes Project. She specializes in the material culture of science and art in the long eighteenth century. Ruben and Marieke share an obsession with an eighteenth-century object that has since disappeared: a small chemical furnace.

With the introduction of chemistry into the university curriculum in the late seventeenth century, new practical needs arose for students  such as being able to perform experiments. Would it be possible to build a chemical furnace that provides a gentle heat, yields no smoke, and is safe for students to use? Herman Boerhaave (1668–1738) believed he found the perfect solution in, what came to be called, Boerhaave’s little furnace.

Portrait of Herman Boerhaave by Cornelis Troost, c. 1730.

Boerhaave was professor of medicine, botany and chemistry at Leiden University in the early 18th century.[1] Instead of starting with the most difficult experiments with metals and minerals, he was convinced that students were better off when they learned the techniques of through simpler processes, such as distilling leaves and flowers, and fermenting bodily fluids. But most chemical laboratories were equipped with elaborate devices too complicated for freshmen students, who in the eighteenth century could be as young as fourteen. Moreover, the brick-build furnaces were designed to create high temperatures, in which small and delicate materials like rosemary leaves would burn instantly.[2] Boerhaave hence needed a device that was low-cost, user-friendly, and would provide a gentle heat.

The plan for the oven, • H. Boerhaave, Elementa Chemiae, Quae Anniversario Labore Docuit in Publicis, Privatisque Scholis, (Leiden 1732).

A small wooden oven was the answer. Boerhaave claimed he had designed this type of furnace when he himself was studying chemistry in the 1690s. He opened the chapter on instruments in his chemistry textbook with the words: “I shall begin with my simplest furnace; which I invented forty years ago, when I practiced chemistry in no large study, where there was only one little chimney, and where I required several furnaces at once.”[3]

Woman at the Virginal and stove under her feet, by Jan Miense Molenaer, 1630-1640. Rijksmuseum, Amsterdam.

This kind of device was probably inspired by ordinary foot stoves. These little stoves, also known as foot warmers, were very popular in the Dutch Republic. Coming in a wide variety of shapes (square, octagonal, cylinder), these stoves often feature in books and paintings. Filled with glowing coals or peat, women placed the little stoves under their robes or blankets to keep warm.[4] Many foot stoves were equipped with a wire bail handle for lifting and easy transportation. Such stoves were used in carriages, sleighs, at home and in church to keep one’s feet warm. This ordinary foot warmer got new applications too, namely as tea and coffee stove,   and we suspect it was the model for the ‘simplest furnace’ in the Leiden chemical laboratory.

Woman carrying a little stove, Harmen ter Borch, 1648–1677. Rijksmuseum, Amsterdam.

The gentle heat produced by Boerhaave’s small oven proved very useful in performing all kinds of chemical experiments. Take rosemary, for example, the evergreen aromatic shrub. Distilled atop a “violent fire”, it would have been turned to flame, smoke, and ashes. But when rosemary instead was distilled at “summer-heat” (approx. 85º F), the mild operation would instead reveal the most volatile, fragrant and aromatic part of the plant ordinarily exhaled in summer. The same process could be applied to Angelica, basil, and all other aromatic plants.

Students in the Leiden laboratory, in Herman Boerhaave, Institutiones et experimenta chemiae (‘Paris’, 1724). Ghent University Library.

Boerhaave, in other words, attributed the success of his device to one’s control over gentle heat. Whenever the wooden oven was filled with hot pieces of coal or Dutch turf that was no longer smoking, it established a constant and moderate heat that could be kept up to 24 hours. As such, the instrument was perfect for students to perform all kinds of heating processes and distillations. In fact, he was so excited about this apparatus, that he claimed that “I believe eggs may be hatched by it”.[5]

Was Boerhaave’s little furnace really that user-friendly and effective as he claimed it was? We checked it out by recreating Boerhaave’s stove and performing experiments with it. Check out our next blog to entry to find out whether we succeeded!

Creating an oven from two old stoves… to be continued!


[1] More on Boerhaave, see Marieke Hendriksen, “Boerhaave’s Mineral Chemistry and Its Influence on Eighteenth-Century Pharmacy in the Netherlands and England”, Ambix(2018) and Ruben Verwaal, “The Nature of Blood: Debating Haematology and Blood Chemistry in the Eighteenth-Century Dutch Republic”, Early Science and Medicine(2017).

[2] Boerhaave, Elementa Chemiae (Leiden:  Isaac Severinus, 1732), vol 2, experiment 1.

[3] Ibid., vol 1.

[4] Le Francq van Berkhey,Natuurlyke historie van Holland (Amsterdam: Yntema and Tieboel, 1769–1778), vol. 3, 706-707, 1200.

[5] Boerhaave, Elementa Chemiae, vol 1.

Teaching a Perfect Knowledge in the Arts and Sciences: Robert Dossie’s chemical, pharmaceutical, and artistic handbooks

Front page to a 1796 reprint of Dossie’s Handmaid

By Marieke Hendriksen

Robert Dossie (1717-1777) was and English apothecary, experimental chemist, and writer. Within just three years, he published three very successful handbooks: The elaboratory laid open (1758) on chemistry and pharmacy for ‘all practitioners of medicine’, Theory and practice of chirurgical pharmacy (1761) for surgeons, and The handmaid to the arts (1758), which taught ‘a perfect knowledge of the Materia Pictoriae’ such as painting, gilding, and japanning. Gibbs (1951, 1953) has written a short overview of Dossie’s life and work, with a focus on his role in the Society of the Arts, but paid no attention to the cohesion of his seemingly divergent work.

Lowengard (2006) has briefly noted that Dossie used a form typical for books about materia medica for his book on the arts, grouping the contents according to techniques employed as well as by the media to which they might be applied, yet his work has never been thoroughly analyzed. Did Dossie indeed transmit a way of structuring and presenting practical knowledge in text from one realm to another? Recipe collections and how-to books before the eighteenth century were often a mixture of medicinal and artisanal recipes and instructions, and the boundaries between medicine, chemistry, and the preparation and application of artist’s materials often so fluid as to be almost non-existent.

Moreover, some earlier printed books on painting and dying techniques did employ the format of a systematic discussion of materials and their preparations, followed by their application, for example Willem Goeree’s 1760 Verlichterie-kunde  What was novel about Dossie’s Handmaid of the Arts though was the combination of this way of presenting practical artisanal knowledge, his attempt to be encyclopaedic in his collection – listing the uses of the same base materials in the production of various artistic and decorative objects, and his very intentional use of the term ‘Materia Pictoriae’.

Rubia tinctorium (madder), one of the many plants that was both materia medica and materia pictoria

The latter appears to have been an attempt to subtly elevate the status of the visual and decorative arts by paralleling the materia pictoriae to the materia medica. Finally, the intended audience gives us more insight in how Dossie understood his own work. From the preface of the book, it appears that Dossie did not so much aim at the people creating visual and decorative objects, but at the professional preparers of artist’s materials, of whom he wrote: “a much greater share of knowledge in natural history, experimental philosophy, and chymistry, is required to the understanding the nature of the simples [sic], and principles of the composition, in a speculative light, than is consistent with the study of other subjects more immediately necessary to an artist.” (p. vii-viii)

In eighteenth-century England, high street chemists and druggists were evolving from preparers and sellers of chemical substances to compounders, stockists, and sellers of drugs and dispensers of medical advice, and it is in this light that Dossie’ work and his division between materia medica and materia pictorial must be seen. Did Dossie intentionally and successfully adapt and implement formats and language traditionally used in one field (medicine) for the organization and transmission of practical knowledge in text to others (chemistry and the arts)? To me it appears that in his mind, materia medica and materia pictoriae were both branches on the tree of chemistry, and that his corpus, which we now tend to see as divergent, was actually a cohesive body of work to him and his contemporaries.


Dupré, Sven, ed. Laboratories of Art : Alchemy and Art Technology from Antiquity to the 18th Century. Archimedes 37. Cham [u.a.]: Springer, 2014.

Gibbs, F.W. “Robert Dossie (1717–77) A Further Bibliographical Note.” Annals of Science 9, no. 2 (1953): 191–93.

Gibbs, F.W.  “Robert Dossie (1717–1777) and the Society of Arts.” Annals of Science 7, no. 2 (1951): 149–72.

Lowengard, Sarah. The Creation of Color in Eighteenth-Century Europe. Columbia University Press, 2006. http://www.gutenberg-e.org/lowengard/C_Chap05.html.

Worling, Peter M. ‘Pharmacy in the Early Modern World, 1617 to 1841 AD’, in Making Medicines: A Brief History of Pharmacy and Pharmaceuticals, ed. by Stuart Anderson (London: Pharmaceutical Press, 2005), pp. 57–76.



Metallic cures: antimonial wine and mineral kermes

By Marieke Hendriksen

In my previous post, I wrote about the ubiquity of mercurial drugs in the long eighteenth century. Mercury is a metal we are all quite familiar with, yet a variety of cures was based on metals and metallic compounds well into the nineteenth century – some of which we hardly hear of anymore today. Drugs based on antimony, a lustrous grey metalloid often found in ores together with either sulfur or mercury, and mineral kermes, a compound of antimony trioxide and trisulfide, were very popular. In universal encyclopedias from the late eighteenth and early nineteenth century for example, we find complicated recipes to create mineral kermes, which involve repeated distilling of a mixture of sulfur of antimony, fixed niter or potassium carbonate, and river- or rainwater.[i]

Antimony ore, antimony cup and Basilius Valentinus, Triump-Wagen Antimonii, Leipzig 1604. From: C. van Heertum, Alchemy on the Amstel. On Hermetic Medicine. Amsterdam: In de Pelikaan, 2012.
Antimony ore, antimony cup and Basilius Valentinus, Triump-Wagen Antimonii, Leipzig 1604. From: C. van Heertum, Alchemy on the Amstel. On Hermetic Medicine. Amsterdam: In de Pelikaan, 2012.

Although it unlikely anyone tried these recipes at home, the use of antimony and its derivatives had a long tradition. Antimony cups were used since antiquity to make antimonial wine by soaking regular wine in it for one or more days.[ii] The fact that antimony frequently occurred together with mercury or sulphur appealed to alchemists, apothecaries, and other medical men and women, as sulphur and mercury were considered the basic alchemical elements. Moreover, as antimony could cleanse the most precious metal, gold, from impurities, alchemists reasoned it could also cleanse and cure God’s most precious creature, created after his own image: man. Hence Paracelsus (1493-1541) and many of his followers advocated the use of small amounts of antimony in iatrochemical drugs, although they were well aware of the fact that it is highly poisonous.

Antimonial wine thus was a tried emetic, yet antimony cups were forbidden in England and France for much of the seventeenth century, as the use of a wine too acidic would result in a lethal concoction. This prohibition was sometimes circumnavigated by creating antimony cups from tin with a small amount of antimony.[iii] In France antimony cups became legal once more in 1658, after Louis XIV was cured from typhoid fever with antimonial wine.[iv] After this royal endorsement of antimony, men of science started to investigate it more closely than ever before. Between 1700 and 1707 the French chemist Lemery wrote an extensive series of articles on antimony and its medicinal uses for the Académie des Sciences, culminating in a book describing all the changes it underwent by chemical procedures, and how the resulting substances could be used in medicine.[v] The Leiden professor of chemistry Gaub too devoted a substantial part of his lectures on metals on antimony and mineral kermes, extensively discussing the chemical procedures that should be applied to create effective medical materials.[vi]

French Apothecary Bottle: Kermes Mineral, 1880s. Courtesy of Dr Jack Fincham.
French Apothecary Bottle with traces of Kermes Mineral, 1880s. Courtesy of Dr Jack Fincham.

The recipes in the encyclopedias show that mineral kermes was one of the most important medical materials that could be created through chemically treating antimony. As can still be seen in a late nineteenth-centruy French apothecary bottle, it is a reddish brown powder. The powder does not dissolve in water and, like mercury, had a reputation for cleansing the lymphatic vessels, and was also used as an emetic and diaphoretic. The name was probably derived from the Arabic name for a similarly coloured crimson dye made from insects, al-qirmiz. The use of mineral kermes as a drug was apparently first mentioned by Glauber (1604-1670), but how to successfully create it remained a subject of debate into the nineteenth century, even after an official recipe was published by the king of France in 1720.[vii]

[i] De Felice, Fortunato Bartolomeo, Encyclopédie ou Dictionnaire universel raisonné des connoissances, (Paris, 1773), Vol. 25, p. 345. Wilkes, John, Encyclopaedia Londinensis, or, Universal Dictionary of Arts (London: J. Adlard, 1810), Vol. iv, p. 277.

[ii] Also see one of my previous blogs on The Medicine Chest.

[iii] StClair Thomson, “Antimonyall Cupps: Pocula Emetica or Calices Vomitorii”, Proc. Roy. Soc. Med., Vol. XIX, no. 9, 1925, 123-8.

[iv] C. van Heertum, Alchemy on the Amstel. On Hermetic Medicine. Amsterdam: In de Pelikaan, 2012, 49.

[v] Lemery, Nicolás, Traité de L’antimoine (Paris: Jean Boudot, 1707).

[vi] Gaub, H.D., ‘Chemiae Praxis. Notes of Lectures by an Unnamed Student. Produced in Leyden.’, Closed stores WMS 4  MS.2479, Wellcome Library Manuscripts, p. 593-685.

[vii] Willich, A.F.M., A Domestic Encyclopedia Or A Dictionary Of Facts, And Useful Knowledge, 3 vols. (London: B. McMillan, 1802), p. 46.

‘Mercurialia are worrisome’: dangerous recipes

By Marieke Hendriksen

To anyone familiar with the practices of Thomas Dover (1662-1742), alias the Quicksilver Doctor, it may seem like mercury and mercury-based drugs were prescribed and taken rather indiscriminately by physicians, apothecaries and patients in the eighteenth century.[i] However, pharmaceutical handbooks, often written by experienced pharmacists under the auspices of university professors of medicine, give an entirely different view. These handbooks, some of which were reprinted in great numbers for decades, were aimed at professional apothecaries and other medical men. Although virtually every pharmaceutical handbook listed mercurial drugs, they all warn against using them too liberally.

Title page of the 1681 edition of the Medicina Pharmaceutica. Credit: Amsterdam University Library.
Title page of the 1681 edition of the Medicina Pharmaceutica. Credit: Amsterdam University Library.

A good example can be found in the four Dutch editions of the Medicina pharmaceutica, or Great general treasury of pharmaceutical medicine, which appeared between 1681 and 1741.[ii] In the first edition, at least nine different recipes involving mercury in some form are listed. Because of mercury’s alleged cleansing and purging properties, these cures were recommended for ailments as diverse as intestinal worms, venereal disease, and skin infections.[iii]

However, in the fifth book of that same edition, the volume on ‘Shop Compositions’ (drugs composed to sell ready made in the apothecaries’ shop), over half a page is spend on a warning about antimonial and mercurial drugs, summarized in the index as ‘Mercurialia zyn sorghelyck,’ which translates as ‘Mercurialia are worrisome.’ Following a list of drugs prepared from a variety of minerals, metals and stones, the author warns that it is not his intention to give the ‘Masters of medicine’ the idea that they should prescribe these dangerous cures often; only when there were no other options left should they revert to them.[iv] The other options, it appears, were mainly traditional herbal remedies, as the author writes:

God almighty has blessed us with some common or native herbs and remedies, that have such a power invested in them, that these can be used in general and without vicissitudes or thinking twice to cure the ill, so one should always use these first, before one turns to some dangerous and strange medicaments from chemistry; so it would be a great deception and recklessness to apply prepared Antimony or Quicksilver, if one is provided with other harmless and powerful remedies, as the former often needlessly do great damage, or could even cause death.[v]

Only if a disease did not respond to the herbal remedies could ‘dangerous chemical preparations’ be applied. As this was the first edition of the Medicina Pharmaceutica from 1681, and the first decades of the eighteenth century saw an increasing incorporation of chemistry in the academy, one might expect that the last edition from 1741 was less tentative about the prescription of chemical remedies.[vi] Previous editions had been printed in Brussels, but the 1741 edition was printed in Leiden–a city with one of the leading medical faculties of Europe at the time. The reprint even had a preface written by the Leiden professor of chemistry Hieronymus Gaub. Although the spelling of the 1741 edition was updated to modern standards, the same old warning was once again repeated.

This raises questions about the extent to which early chemical research and teaching at universities was changing professional medical men’s understanding and application of mercurial, or other chemically-based, remedies. Moreover, the apparent contrast between the cautions and warnings in professional handbooks like these and popular culture on the one hand, and the ostensible popularity of mercury remedies on the other, makes this a fascinating research topic.

[i] Also see Kenneth Dewhurst, The Quicksilver Doctor. The Life and Times of Thomas Dover Physician and Adventurer (Bristol: John Wright & Sons Ltd., 1957).

[ii] Robertus de Farvacques, Medicina pharmaceutica, of Groote algemeene schatkamer der drôgbereidende geneeskonst (Leiden: Isaak Severinus, 1741). De Farvacques, the personal physician of Charles II, was not really the author of this book. His name was used by the actual author, the Brussels friar Peter Gilles, to lend it more authority. See L.J. Vanderwiele, “Broeder Petrus Gillis S.J. (1620-1697), Auteur van Medicina Pharmaceutica of Drogbereidende Geneeskonst”, Kring voor de geschiedenis van de pharmacie in de Benelux. Bulletin. 69 (maart 1986): 8–16.

[iii] Robertus de Farvacques, Medicina pharmaceutica, of Groote algemeene schatkamer der drôgbereidende geneeskonst. (Brussels, Francois Foppens, 1681), Vol. V, 932-5, 951-5.

[iv] Ibid., 967.

[v] Ibid.: ‘Want aengesien Godt almachtigh ons met eenighe ghemeynsaeme, oft inlandtsche heylsaeme kruyden ende drôghen heeft ghejont, die met sulcken kracht zyn begaeft, dat-men ghemeynelyck met de selve sonder peryckel oft achterdencken de siecken kan ghenesen, soo behoort-men altoos eerst de selve the ghebruycken, eer men sich begheeft om eenighe ghevaerlycke ende vremde middelen uyt de schey-konst te nemen; soo dat het een groot bedrogh oft reuckeloosheydt soude wesen, achter den bereyden Antimonie oft Quick in ‘t werck te stellen, soo wanneer men versien is van andere schadeloose ende krachtighe remedien, door dien men also dickmaels sonder noot aen onsen evenaesten groote schade, jae de doodt selfs soude konnen aen-brenghen.’ (Translation mine)

[vi] On the formation of chemistry as an academic discipline in the early eighteenth century see Bruce Moran, Distilling Knowledge. Alchemy, Chemistry, and the Scientific Revolution (Cambridge, MA: Harvard University Press, 2005), chapter 4.