Achard, Franz Karl

(b. Berlin, Germany, 20 April 1753; d. Kunern, Germany, 20 April 1821)

chemistry, experimental physics.

Achard, baptized François-Charles, was born of French Protestant émigré parents. His father, Guillaume Achard, a minister, died when Franz Karl was only two years old. In 1759 his mother, whose maiden name was Margarette Henriette Roupert married a Charles Vigne. Of Achard’s upbringing and early education, virtually nothing is known. At the age of twenty he began his scientific career in association with the botanist J. G. Gleditsch and with the renowned chemist A. S. Marggraf. It was Marggraf, especially, who trained young Franz Karl, gave him entrée into Berlin scientific circles, and finally obtained, in June 1776, his admission to the Berlin Academy. When Marggraf died in 1782, Achard succeeded him as director of the “Class of Physics” of the Berlin Academy.

In his youth, Achard was a prolific writer, He published articles on the thermal expansion of gases and liquids, the effects of soluble and insoluble fluids on the freezing point of water, cooling by evaporation, and various electrical phenomena, as well as numerous papers on miscellaneous chemical and physical subjects. Most of these articles were published in French in the Nouveaux mémoires of the Berlin Academy, in Rozier’s journal (Observations sur la physique...), and in the Journal littéraire (Berlin), In addition, Achard published German articles in Crell’s Chemische Annalen and in two volumes of collected essays (1780, 1784).

None of Achard’s early papers was of great importance. In general, he eschewed theoretical discussion and concentrated his efforts on the detailed investigation of facts. Typical of this procedure was his paper on cooling by evaporation, which amounted to little more than a short history of previous investigations of the topic, followed by a description of his experimental method and long lists of various liquids and their relative abilities to cool. The few general remarks that he appended to this discourse had been established years, even decades, before. Achard is known for several minor achievements in applied chemistry, most notably his description of a workable alloy of platinum and arsenic and his process for fabricating lye from common salt and litharge. In addition, he was one of the first to conduct detailed investigations of galvanism.

Achard is best known for his development of a method of extracting sugar from beets in large quantity. In 1747 Marggraf had published a paper in which he showed that crystallizable sugar could be extracted from various plants native to Europe. The most promising of these plants appeared to be the common beetroot. At his estate near Berlin, Achard began experiments in 1786, in an effort to develop a process for extracting sugar from beets in quantities large enough and at cost low enough to be commercially valuable. In 1799, after having tried various methods of cultivation and extraction, he had a loaf of beet sugar, along with a description of the process by which it had been made, presented to Frederick William III. The king appointed a special committee to investigate this new process, and when it issued a favorable report, Achard was given financial aid to build a beet-sugar refinery in Kunern, a Silesian village near Breslau. The factory was completed in 1801, and it began operations the following year.

Achard’s new process of obtaining sugar was simple but costly. It consisted of boiling specially cultivated, white Silesian beets and then pressing them to extract a sugary liquid. This, liquid, added to that obtained from a second pressing, was boiled to remove excess water and then placed in an oven at moderate temperature to allow crystallization. After a crust had formed, the liquid was cooled and the sugar was separated by filtration. The muscovado, or raw sugar, could be refined to any desired degree of purity by recrystallization. The by-products were beet pulp, which could be used for cattle fodder, and molasses, which could be made into spirits.

News of Achard’s accomplishment spread quickly throughout Europe. In France the first details were communicated by Van Mons in an article written for the Annales de chimie. The Institut formed a committee of chemists and agriculturalists to examine Achard’s process and suggest possible improvements. In June 1800 it issued an encouraging report and made several valuable recommendations, the most important of which was that the beets be pressed without cooking them. Achard afterward adopted this technique in order to reduce the considerable expenditures for fuel.

Under the artificial stimulus of the Continental System, which reduced the supply of West Indian sugar, and with the aid of liberal governmental financing, the beet-sugar industry prospered briefly. In 1813 an investigating commission of the French government reported that there were 334 beet-sugar factories in France, with a combined annual production of 7,700,000 pounds. Although no such specific figures exist for Germany, it seems evident that the beet-sugar industry was also widely established there. However, when the Napoleonic Wars came to an end and normal markets were reestablished, the industry all but disappeared. It revived about the middle of the nineteenth century, and made its greatest strides with the development of the diffusion process of extraction and with the cultivation of new strains of beets containing over twice as much sugar as those Achard had used.

After a five-week illness, Achard died only a week before his sixty-eighth birthday. He was survived by his second wife and several children. His death passed virtually unnoticed in academic circles, from which he had long since retired.

BIBLIOGRAPHY

I.Original Works. Achard’s writings include Chymisch-physische Schriften (Berlin, 1780); Sammlung physikalischer und chymischer Abhandlungen, Vol, I only (Berlin, 1784); and Vorlesungen über die Experimentalphysik, 4 vols,. (Berlin, 1790–1792). Among Achard’s many works on the beet-sugar industry, three are especially worthy of mention: Kurze Geschichte der Beweise welche ich von der Ausführbarkeit im Grossen und den vielen Vortheilen der von mir angegebenen Zuckerfabrication aus Runkelrüben geführt habe (Berlin, 1800); Anleitung zum Anbau der zur Zuckerfabrication anwendbaren Runkelrüben und zur vortheilhaften Gewinnung des Zuckers aus denselben (Breslau, 1809), repr. as Ostwalds Klassiker der exacten Wissenschaften, no. 159 (Leipzig, 1907); and Die europäische Zuckerfabrication aus Runkelrüben (Leipzig, 1809).

II. Secondary Literature. A detailed and reliable account of Achard’s life is found in Wilhelm Stieda, “Franz Karl Achard und die Früzeit der deutschen Zuckerindustrie,” in Abhandlungen der philologisch-historischen Klasse der Sächsischen Akademie der Wissenschaften, 39 , no.3 (Leipzig, 1928). See also Adolf von Harnack, Geschichte der Königlich Preussischen Akademie der Wissenschaften zu Berlin, IV (Berlin, 1900), 3–7, 389 f.; and Noël Deerr, The History of Sugar, II (London, 1950), 471–500.

J.B. Gough