Eller von Brockhausen, Johann Theodor

(b. Plötzkau, Germany, 29 November 1689; d. Berlin, Germany, 13 September 1760)

medicine, chemistry.

Eller’s father, Jobst Hermann Eller, was an eminent military man under the prince of Anhalt; his mother belonged to the Behm family, an ancient family in Livonia. He had an excellent education in law at Quedlinburg College and Jena University, but he changed to the study of medicine while at Jena. In 1711 he left Jena to search for better instruction in anatomy, going to Halle, then Leiden, and finally in 1712 to Amsterdam, where he found the most capable anatomists in Europe, Rau and Ruysch. When Rau moved to Leiden, Eller went with him and performed public dissections for him until 1716. Eller was not prepared at this point to settle down to the practice of medicine, but turned to the study of mineralogy and chemistry, first with Lemery and Homberg in Paris, and then with Hauksbee and Desaguliers in London.

Upon his return to Anhalt-Bernberg in 1721, Eller was made court physician by the prince. He married Catherine Elizabeth Burckhard in October of that year. In 1724 King Frederick William I called Eller to Berlin and made him professor of anatomy and permanent dean of the Medical College, as well as physician to the army. When Frederick the Great became king in 1740, he made Eller his personal physician and appointed him director of the Berlin Academy of Sciences. Eller’s wife died in 1751, and in 1753 he married Henrietta Catherine Rosen. In 1755 Frederick made Eller a privy councillor, a position he held until his death.

Eller held the highest medical positions in Prussia during his lifetime. He was a very competent doctor and administrator. In administration, for example, he was responsible, together with Georg Ernst Stahl, for laying the foundation for all subsequent developments in medical services in Prussia. Eller’s writings reflect his medical knowledge and consist largely of compilations of case histories, like the one he published in Berlin in 1730, based on his experiences in the Charité Hospital in Berlin. He carried out some studies on human blood, examined human calculi, and warned about the dangers of using copper kitchen utensils, but he is not noted for any significant development in medicine.

Eller’s theoretical chemistry is characterized by the central role given to heat (fire). His writings clearly place him in the Continental tradition that considered heat to be material in nature. With Eller, the Stahlian principle of phlogiston became simply another name for the primary element fire in the fixed state. In this state, fire is chemically combined with most substances and generally is released during chemical reactions. In the active state fire is the sole cause of the fluidity of water and fluids in general (air included). This principle is also integrated into his main practical chemical work, which dealt with the solubility of salts in water. Eller argued that since solubility generally increased with temperature, it must be because the fire in the water, whose activity increased with temperature, could more readily break up (dissolve) the salts.

Eller’s influence on chemical theory has never been considered of great consequence, yet it is known that Lavoisier read Eller’s papers, especially those dealing with the elements, and his early views have an interesting resemblance to Eller’s ideas about heat and fluidity.

BIBLIOGRAPHY

I. Original Works. Eller’s main in medicine is Nützliche und auserlesene medicinsiche und chirurgische Anmerkungen so wohl von innerlichen, als auch äusserlichen Krankheiten,...; nebst einer vorangegebenen kurtzen Beschreibung der Stiftung, Anwachs und jetzigen Beschaffenheit dieses Hauses, usw. (Berlin, 1730). All of Eller’s papers, which were originally published in the Berlin Academy Memories and Miscellanea Berolinensia, are found in German translation in his collected papers, Physikalisch-chymisch-medicinische Abhandlungen, aus den Gedenkschriften der köniliglichen Akademie der Wissenschaften, D. Carl Abraham Gerhard, ed. (Berlin, 1764).

II. Secondary Literature. There is no biography of Eller. Some information may be obtained from the éloge in the Berlin Academy Memoirs of 1761 and the Allgemeine deutsche Biographie, VI (Leipzig, 1877), 52–53. Only the larger histories of chemistry say anything about his scientific work.

David R. Dyck