-Search for letters
-Search in texts






Link: • Henrik Gahn to Carl Linnaeus, 24 September 1771 n.s.
Dated 24 Sept. 1771. Sent from London (Great Britain) to Uppsala (Sweden). Written in Swedish.


Henrik GahnGahn, Henrik (1747-1816).
Swedish. Physician. Linnaeus’s student.
Founder of the Swedish Society of
Medical Sciences in 1807. Correspondent
of Linnaeus. Son of hans Jacob Gahn and
brother of Hans Jacob Gahn the Younger.
tries to awaken Linnaeus’s memory of him with a long introduction, saying that he left Sweden a year ago and that an unfortunate shipwreck and the late autumn led him to overwinter in Göttingen.

In Hamburg he got to know Hermann Samuel ReimarusReimarus, Hermann Samuel
(1694-1768). German. Professor of
Hebrew and oriental languages, Hamburg.
Author of works in natural history.
, who had refuted the Viennese Heinrich Johann Nepomuk von Crantz’sCrantz, Heinrich Johann Nepomuk von
(1722-1799). Austrian. Naturalist
and physician. Professor in obstetrics
in 1754, Vienna.
stupid botanical writings, and also Joachim Friedrich BoltenBolten, Joachim Friedrich
(1718-1792). German. Doctor of
medicine, Hamburg. Correspondent of
, who had written to Linnaeus concerning a new zoophyton, which was certainly nothing other than a variety of Vorticella ovifera in George EdwardsEdwards, George (1693-1773).
British. Ornithologist and artist.
Visited the Netherlands, France and
Scandinavia. Best known for his
History of birds (1747-1751).
Correspondent of Linnaeus.
, A natural history of uncommon birdsEdwards, George A natural
history of uncommon birds, and of some
other rare and undescribed animals
[...]. To which is added a [... ]general
idea of drawing and painting in water
colours; with instructions for etching
on copper with Aqua Fortis: likewise
some thoughts on the passage of
etc., 4 pt., 4 vols. (London,
and which Gahn had seen later when visiting Joseph BanksBanks, Joseph (1743-1820).
British. Naturalist, president of the
Royal Society. Together with Daniel
Solander he took part in Cook’s first
voyage. Correspondent of Linnaeus.
, all with elongated capitula and caught in the South Seas. In both Lübeck and Hamburg Gahn had seen specimens of Oculus mundi, and had also conducted experiments, finding that they were nothing but porous stone that absorbed air and then released air bubbles and at the same time became transparent. In Göttingen, Gahn attempted to improve himself through the German medical literature, the best opportunity being through the magnificent library that Otto von MünchhausenMünchhausen, Otto von
(1716-1774). German. Chancellor of
Göttingen University. Correspondent
of Linnaeus.
had founded. Botany had improved considerably since Andreas MurrayMurray, Andreas (1695-1771).
Swedish. Dean of the German
congregation, Stockholm. Father of
Adolph Murray, Gustaf Murray, Johan
Andreas Murray and Johann Philipp
took over and Murray worked like a slave to get his little garden in order. He already had a considerable collection of plants. Otherwise, Gahn found the Germans exactly as Linnaeus had described them: One cannot look for inventions or ingenium among them but they are extraordinarily industrious and know how to improve upon the discoveries of others with great diligence. When Gahn left Göttingen he first visited the mines in Hartz, where he found a climate similar to that in Sweden and with Swedish plants, and then he arrived in Pyrmont. All the experiments that the Germans had conducted with Pyrmont water were false and had also led to practical medical errors. Gahn found that the iron contained in the water was not dissolved by any acid or alkali but by the so-called Aër fixus Halesii [carbonic acid ]. This fluidum, that is incorrectly called air, is fully capable of dissolving iron, and Gahn believes that it forms all mineral waters. A pharmacist in London had recently performed the same experiment. When the very least warmth is applied the air is released and at the same time the iron sediments to the bottom. Consequently, when Pyrmont water is retailed it seldom has any particular content of iron and has almost the opposite effect than at the spring itself since the Sal amarum has a laxative effect but no longer gives strength when the iron has disappeared. Close to the spring is the so-called sulphur valve containing a poisonous air similar to that in Grotta del Cani in Italy. After a few deductive experiments, Gahn found that it was incorrect to believe that it was evaporated sulphur but was nothing more that this Aër fixus, which is an unsuitable fluidum for animals to respire. The warmth from the air separates it from the actual spring water when it leaves the ground and, thus, if one leans over the spring one will be killed in the same way as in the sulphur valve. Iron filings placed in the water do not leave the slightest trace of iron, but when this mixture was placed overnight in the sulphur valve it received a complete taste of mineral water and was coloured by A[cidum] Gallarum. Gahn believes that this Aër fixus, together with a bag containing bog iron, explains the manufacture of Pyrmont water, and does not originate from a neighbouring mountain where the Germans have suspected iron but have found nothing but sandstone. Gahn also visited the famous economist Otto von MünchhausenMünchhausen, Otto von
(1716-1774). German. Chancellor of
Göttingen University. Correspondent
of Linnaeus.
, who lived not far from Pyrmont. Being a disciple of Linnaeus, Gahn was fairly well received. Gahn had never seen such a large collection of trees and saw from the fields that he was as good in economy as he was as a writer. In Holland, Gahn met Johannes BurmanBurman, Johannes (1707-1779).
Dutch. Botanist, professor of medicine
in Amsterdam. Close friend of Linnaeus.
Correspondent of Linnaeus.
, Nicolaas Laurens BurmanBurman, Nicolaas Laurens
(1734-1793). Dutch. Professor of
botany. Linnaeus’s pupil in Uppsala in
1760. Correspondent of Linnaeus.
and Adriaan van RoyenRoyen, Adriaan van (1705-1779).
Dutch. Professor of botany, director of
the botanical garden of Leiden.
Correspondent of Linnaeus.
and David van RoyenRoyen, David van (1727-1799).
Dutch. Professor of botany at Leiden and
director of its botanical garden.
Correspondent of Linnaeus.
. Their gardens were now not what they were; both George Clifford’sClifford, George (1685-1760).
Dutch. Banker and merchant in Amsterdam,
Linnaeus’s benefactor. Owner of
Hartecamp and its botanical garden
outside Haarlem. Correspondent of
garden [Hartecamp] and Herman Boerhaave’sBoerhaave, Herman (1668-1738).
Dutch. Professor of medicine, botany and
chemistry at Leiden. One of the most
influential professors of medicine of
the eighteenth century. Linnaeus visited
him during his stay in Holland.
Correspondent of Linnaeus.
garden had been sold and dispersed, and the best is perhaps the one Herman Martin Wilhelm Schwenck had in The Hague. Wouter van DoeverenDoeveren, Wouter van
(1730-1783). Dutch. Professor of
medicine, Leiden.
was occupied with writing a description of Petrificates that he had found near Gröningen and promised to send Linnaeus the book when ready. However, Gahn was unable to visit the celebrated Hieronymus David GaubGaub, Hieronymus David
(1705-1780). German. Physician,
professor of chemistry and medicine at
; he had recently introduced a new medicine called Lopezii, which is excellent against all diarrhoeas caused by weakness of the fibres, in the colloquial also called Phthisicorum. This medicine is still so scarce that it is not sold in the pharmacies but nonetheless Gahn was able to acquire a small bit that will be sent to Linnaeus at the first opportunity. The root is taken from the island Malacca to Batavia but some believe it to come first to Goa, but there the plant is completely unknown. It tastes almost of nothing, but a half drachma every 3 or 4 hours almost always cures the worst diarrhoea by the second day. This has been described in a book published by Gaub, Adversariorum varii argumentiGaub, Hieronymus David
Adversariorum varii argumenti
(Leiden, 1771)

Gahn also tells Linnaeus about another medicine with almost the same effect that John PringlePringle, John (1707-1782).
British. Professor of medicine,
Edinbugh. Military physician.
in London had introduced, called Colombo after Ceylon’s capital, from where it is fetched. It is also a root of an unknown plant. As soon as Gahn finds out more, he will inform Linnaeus, but knows that it is fairly specific in treating diarrhoeas in children, but also effective in after dysenteries. Pringle had himself told Gahn that he had found the best effect of it also in nausea and other conditions. The dose is one-half drachma, like the former, two or three times a day.

When in The Hague, Gahn heard from a Pieter Bosch

that no medicine was better for treating the Dutch women’s diseases. Gahn apologises to Linnaeus for having written so much about this. Gahn had heard that Linnaeus was preparing a new edition of Materia MedicaLinnaeus, Carl Materia
Medica. Liber I. De plantis secundum:
genera, loca, nomina, qualitates, vires,
differentias, durationes, simplicia,
modos, usus, synonyma, culturas,
praeparata, potentias, composita,
digestus, &c.
I-II (Stockholm
1749). Soulsby no. 968.
and thought that these two roots would find space therein. Postage is so impossibly expensive in England that Gahn thought he would have to find a vessel bound for Stockholm to take the roots, after which Gahn’s brother [Johan Gottlieb GahnGahn, Johan Gottlieb
(1745-1818). Swedish. Chemist and
metallurgist, Falun. From 1773-1817 he
was the chemist for The Swedish Board of
Mines [Bergskollegium].
] would take them to Uppsala.

Gahn had arrived in London about one month previously, just in time to see numerous collections and discoveries made by Daniel SolanderSolander, Daniel (1733-1782).
Swedish. Naturalist, explorer. Student
in Uppsala under Linnaeus and Johan
Gottschalk Wallerius. Went to London in
1760. Curator of natural history
collections at the British Museum.
Botanist on Cook’s first voyage
1768-1771. Joseph Bank’s librarian.
Correspondent of Linnaeus.
and Joseph BanksBanks, Joseph (1743-1820).
British. Naturalist, president of the
Royal Society. Together with Daniel
Solander he took part in Cook’s first
voyage. Correspondent of Linnaeus.
. Gahn is convinced that they have, or will, give Linnaeus everything, so Gahn need not describe anything. They were planning a new journey, to be started in March. Gahn had hoped to be able to join the expedition as Solander had half promised him. So now Gahn plans to improve his medical knowledge by visiting the numerous large hospitals, either in London or in Edinburgh. During the winter Gahn had written to Jonas SidrénSidrén, Jonas
(1723-1799). Swedish. Physician.
Professor of medicine and anatomy at
Uppsala. Married to Wendla Borell.
Son-in-law of Anders Borell, and
brother-in-law of Anna Maria Acrel.
Correspondent of Linnaeus.
, but did not know if the letter had arrived. Gahn asks Linnaeus when the Medical Faculty [at the University of Uppsala] will have its next promotion. Gahn hopes that he will not be forgotten in that context and that his rapid departure would not be a disadvantage.

In closing, Gahn recalls the happy days he had at Hammarby and sends his greetings to Linnaeus’s family, his wife [Sara Elisabet LinnaeaMoraea, Sara Elisabet
(1716-1806). Swedish. Linnaeus’s wife.
Daughter of Johan Moraeus and Elisabet
Hansdotter Moraea. Mother of Carl
Linnaeus the Younger and of Elisabeth
Christina, Louisa, Sara Christina and
Sophia Linnaea.
], the young daughters [Sara Christina LinnaeaLinnaea, Sara Christina
(1751-1835). Swedish. Daughter of Carl
Linnaeus and Sara Elisabet Linnaea.
Sister of Carl Linnaeus the Younger and
of Elisabeth Christina, Louisa and
Sophia Linnaea.
, Sophia LinnaeaLinnaea, Sophia (1757-1830).
Swedish. Daughter of Carl Linnaeus and
Sara Elisabet Linnaea. Sister of Carl
Linnaeus the Younger and of Elisabeth
Christina, Louisa and Sara Christina
Linnaea. Wife of Samuel Christoffer
] and the young professor [Carl Linnaeus the YoungerLinnaeus the Younger, Carl
(1741-1783). Swedish. Botanist. Son of
Carl Linnaeus and Sara Elisabet Linnaea.
Brother of Elisabeth Christina, Louisa,
Sara Christina and Sophia Linnaea.
Attended his father’s lectures, had
private tutors (Löfling, Rolander,
Solander and Falk, all Linnaeus’s
students). Demonstrator of botany at
Uppsala. Succeeded his
] .


a. (LS, IV, 344-346). [1] [2] [3] [4] [5]


1. Bref och skrifvelser (1912), vol. I:6, p. 177-181   p.177  p.178  p.179  p.180  p.181.