Andreas Sigismund Marggraf

German chemist

• Born: May 3, 1709
• Birthplace: Berlin, Prussia (now in Germany)
• Died: August 7, 1782
• Place of death: Berlin, Prussia (now in Germany)

A pioneer German analytic chemist, Marggraf is most famous for discovering sugar in the beet, for discovering the element zinc, and for realizing commercially applicable ways of extracting each. By the mid-eighteenth century he was Germany’s most famous chemist.

Early Life

Andreas Sigismund Marggraf (ahn-DRAY-ehs SEEG-ihs-muhnd mahg-GRAHF) developed an interest in chemistry because of the influence of his father, Henning Christian Marggraf, who first moved to Berlin as a grocer before acquiring a small pharmacy in 1707 and then a large pharmacy in 1720. Henning engaged in some independent chemical research, corresponding with Prussia’s leading chemist and metallurgist, Johann F. Henckel. Andreas received schooling while training as an apprentice in his father’s apothecary.

In 1726 the seventeen-year-old Andreas transferred to Berlin’s Court Apothecary Shop, where he studied for five years under Caspar Neumann, an influential pharmacist and teacher of pharmaceutical chemistry. From 1733 through 1735 he studied chemistry in Berlin and Strasbourg and medicine at the University of Halle. Having a broad interest in science, he also studied mineralogy and metallurgy in Freiberg under the tutelage of Henckel, his father’s famous associate.

After completing his studies at the age of twenty-six, Marggraf visited a wide variety of mines to view the commercial methods used to extract ore. He then returned to Berlin, where he took over as chief administrator of his father’s apothecary, a position he held from 1735 until 1753, when the apothecary was sold to his brother.

The depth and breadth of Marggraf’s scientific training earned him election in 1738 to the Berlin Academy of Sciences. Membership in the academy provided him the opportunity to work in the academy’s chemistry laboratory, which at the time was one of the best in Germany. The appointment also carried a salary and an official residence, allowing him to devote his time to chemical research. The importance of his discoveries would earn him the position of head of the chemical laboratory in 1754 and that of director of the physics class in 1760; he held the latter position until his death in 1782. Marggraf helped make the Berlin Academy of Science’s Europe’s third leading scientific society, trailing only the royal scientific societies in Paris and London.

Marggraf’s early research was with phosphorus, an element widely used in the production of matches. He discovered how to prepare phosphoric acid in 1740, and three years later he developed a commercially cheap method for producing phosphorus by distilling urine, using the commonly available materials sand, coal, and lead chloride (horn lead). He next focused his research on developing methods for readily distinguishing compounds containing sodium from those containing potassium. His most significant research was conducted in 1746, when he discovered that zinc was a distinct element, and in 1747, when he developed a method for producing sugar by extracting it from beets.

Life’s Work

Until Marggraf published the results of his conclusive study, zinc was thought to be a blend of metals. By taking calamine ore from four different sources and heating it with carbon in closed vessels, Marggraf was able to extract pure bluish-white metallic zinc from each vessel. Marggraf was also able to extract pure zinc from sphalerite, a mineral containing heavy concentrations of lead. At the time of his discovery, zinc was used to make bronze and brass, which gave Marggraf’s methods for extraction immediate commercial value. The element was later used to make battery plates and to rust-proof iron and steel. Marggraf was unaware that similar experiments with zinc were being conducted in England and Sweden. It was Marggraf’s methodical study, however, that provided conclusive proof that zinc was an element and gained him a place in history as the discoverer of zinc.

At the same time he was working with zinc, Marggraf experimented with extracting sugar from a variety of plants by dissolving the pulp in alcohol, which left a crystalline substance after evaporation. At the time of his experiments, sugar cane was the only known source of sugar. However, sugar cane grew in tropical climates only, so the only source of Europe’s sugar supply had to be imported at considerable expense. Marggraf had long wondered about the sweet taste of the beet, a common vegetable in Europe, which was used for both its bulb and its leaves. Marggraf had particular success in using alcohol to extract sugar from the boiled root pulp of the white beet, which was common to the Mediterranean coastal region. To prove that the sugar extracted was the same chemically as cane sugar, Marggraf used a powerful microscope to compare the crystalline structures of the two. This was the first time the microscope was used as an instrument for chemical analysis, and the results provided conclusive proof that the crystalline structure was the same.

Although it had commercial applications, Marggraf’s discovery of beet sugar in 1747 remained purely academic during his lifetime, and he rapidly turned to new ventures in chemistry. His work on beet extraction was later continued by his student, Franz Karl Achard, who experimented with developing beets with higher sugar content and processes that would make sugar production commercially profitable. As a result, the first sugar factory was built in 1801 at Cunern in lower Silesia. Within a few years, interruptions of the overseas sugar trade resulting from the Napoleonic Wars caused the rapid growth of sugar beet factories.

Two years after the discovery of sugar in beets, Marggraf developed a process by which formic acid, used in dyeing textiles and treating leather, could be produced through the distillation of ants. His research also led to improved methods for the purification of silver and tin and the discovery of the chemical nature of alum, used in baking powders and dyes. He devised a method of identifying the oxides of aluminum (alumina) and calcium (lime) found in clay.

Marggraf’s last major discovery was made in 1758, when he developed a simple method of distinguishing compounds containing sodium from compounds containing potassium by analyzing the flame coloration these compounds exhibited when burned. Fire was particularly important for Marggraf, as he was a lifelong advocate of the phlogiston theory, which held fire to be an elemental substance released from a substance upon combustion. In 1777 the widespread belief in the phlogiston theory was discredited among chemists by the publication of French chemist Antoine-Laurent Lavoisier’s study of oxygen. Nevertheless, Marggraf’s fame was strong enough in France to gain his appointment as one of six foreign members of the Royal Academy of Sciences.

Significance

Marggraf helped establish chemistry as an essential discipline for studies of pharmacy, medicine, mineralogy, and physics. He helped popularize the eighteenth century Scientific Revolution and its diffusion into everyday life by embodying the connection among science, technology, and industry. His work with minerals and metals contributed to the development of theoretical and methodological natural science, but it also had immediate commercial relevance to mining. Similarly, Marggraf’s work with formic acid and sugar beets revealed the potential commercial applications of chemical discoveries. Indeed, one of his private students, Achard, established a sugar industry based upon Marggraf’s pioneering work. Other students, such as Jacob R. Spielmann, continued important work in pharmacy and chemistry, while Johann C. F. Meyer used his training in chemistry to establish Prussian alcohol distillation industries to offset the need for foreign imports. Marggraf’s most famous student, Martin Heinrich Klaproth, succeeded him as Germany’s leading chemist, receiving the first chemistry chair at the newly created University of Berlin.

Marggraf’s international esteem raised Prussia’s reputation as an Enlightenment-based state that stood with France and Great Britain as a place where science thrived. Marggraf’s fame also elevated the prestige of his patron, King Frederick the Great. Chemistry would continue to accelerate in Germany, with the country eventually gaining a position of world leadership in this field by the end of the nineteenth century.

Bibliography

Hufbauer, Karl. The Formation of the German Chemical Community, 1720-1795. Berkeley: University of California Press, 1982. Provides a good analysis of Marggraf’s work and its role in the development of Germany’s leadership in chemistry. Contains charts, tables, graphs, biographical profiles, and pictures.

Macinnis, Peter. Bittersweet: The Story of Sugar. London: Allen and Unwin, 2003. A history of sugar production that contains a treatment of Marggraf’s contribution and the subsequent development of the sugar beet industry. Includes a bibliography and footnotes.