MARGGRAF, ANDREAS SIGISMUND

(b. Berlin, Prussia, 3 March 1709; d. Berlin, 7 August 1782)

chemistry.

The few recorded accounts of Marggraf’s personal life portray a modest, even-tempered man of precarious health but of single-minded devotion to study and laboratory experimentation. The influence of his mother, Anne Kellner, ramains obscure; but it is known that his father, Henning Christian Marggraf, apothecary to the royal court at Berlin and assessor (assistant) at the Collegium Medico-Chirurgicum, introduced him to a circle of pharmacists and chemists. Marggraf’s professional apprenticeship comprised several stages: from 1725 to 1730 he was a pupil of Caspar Neumann, his father’s colleague at the court pharmacy and medical school and a disciple of Stahl; from 1730 to 1733, he assisted the apothecary Rossler in Frankfurt-am-Main and studied with the chemist Spielmann the elder at the University of Strasbourg; in 1733 at Halle he heard the lectures of Friendrich Hoffmann in medicine and of Johann Juncker in chemistry; in 1734 he traveled to Freiberg, Saxony, to study metallurgy with Henckel. After two years with his father in the Berlin court pharmacy, Marggraf visited Wolfenbüttel, Brunswick, in 1737 but refused an offer of the post of ducal apothecary. He chose to return to Berlin, where he was admitted the following year to the Königlick Presussischen Societät der Wissenschaften (reorganized in 1744–1746 as the Académie Royale des Sciences et Belles-Letters). Despite the recriminations of a senior academician, J.-H. Pott, Frederick II selected Marggraf as director of the Academy’s chemical laboratory in 1753 and as director of its Class of Experimental Philosophy in 1760. Marggraf was also a member of the Kurakademie der Nützlichen Wissenschaften of Mainz and a foreign associate of the Paris Academy of Sciences (1777). Although unable to write after suffering a stroke in 1774, Marggraf confounded attempts to replace him and prepared studies for publication until 1781.

Contemporaries recognized Marggraf as a masterful experimental chemist because of the extraordinary range of his interests and the painstaking nature of his procedures. As an adherent of the Stahl-Juncker phlogiston theory of combustion and calcination, he remained a figure of the “Chemical Ancien Regime.” But just as eighteenth-century statecraft sometimes prefigured Revolutionary politics, so Marggraf’s interest in chemistry for its own sake, his refinement of analytical tools, and his use of the balance anticipated some facets of the Chemical Revolution.

Marggraf’s innovations in analytical methods included an emphasis on “wet methods,” or solvent extraction, with careful attention to washing and recrystallization of the end product. His work with certain organic substances, for example the acid extracted from ants (1749) and the “essential oil” of cedar shavings (1753), combined traditional destructive distillation with the sophisticated use of solvents later practiced by G. F. Rouelle. Marggraf’s most significant contribution to applied chemistry was his extraction and crystallization of sugar from plants commonly grown in Europe. In 1747 he used boiling rectified alcohol to extract the juice from the dried roots of Beta alba (white mangel-wurzel), Sium sisarum (skirret), and Beta radicae rapae (red mangel-wurzl). When crystals appeared several weeks later, he confirmed their identity with those of cane sugar by microscopic observation—perhaps the first such use of the microscope in the chemical laboratory.

Marggraf also developed a less costly process involving the maceration of roots to obtain the juice and the use of limewater to aid sugar crystallization. Although he envisaged a king of household industry to assure the poor farmer a new source of sugar, half a century elapsed before any technological application of the laboratory procedures. Achard, Marggraf’s successor as director of the Class of Experimental Philosophy, began experiments on sugar refining in 1786; his first factory became operational under royal patronage in 1802 at Kunern, Silesia. Napoleon’s Continental System aroused even greater interest in France and Prussia in a substitute for overseas sugarcane.

On several other occasions Marggraf applied tests significant for modern analytical chemistry. In 1759, to distinguish “cubic niter” (sodium nitrate) from “prismatic niter” (potassium nitrate) crystals, he used, besides the microscope, the flame test—forerunner of modern emission spectroscopy—which differentiated the violet flash of ignition of saltpeter from the yellowish flash of the sodium nitrate. The blowpipe, a tube designed to intensify the flame by directing air upon it, refined this test to reveal characteristic colors and products upon the fusion of a metal. In 1745 Marggraf pioneered the use of the reagent Prussian blue, “fixed alkali ignited with dried cattle blood,” as an indicator for the iron content of limestone.

The most notable of Marggraf’s isolations of mineral substances were his production of the “acid of phosphorus” and his improved preparation of phosphorus itself. In 1740 he obtained white “flowers” (oxide of phosphorus) from the combustion of phosphorus and recorded, without explanation, the phenomenon so crucial to Lavoisier in 1772, that the calx showed an increase in weight. More remarkable to Marggraf was the hydration of the product in air to form the previously unknown oily phosphoric acid. When heated with coal this acid yielded, in Marggraf’s terms, phlogiston and phosphorus.

The preparation of phosphorus had remained a highly prized monopoly of a few German and English chemists (notably Boyle’s assistant Hanckwitz) until the French government purchased rights to Kunckel’s process in 1737 and permitted Hellot to publish his experiments the same year in the Mémories of the Paris Academy. In 1725 Marggraf had observed Neumann’s preparation of phosphorus “with extreme difficulty” from urine and sand. Applying suggestions recorded in Henckel’s Pyritologia (1725), Marggraf in 1743 evaporated stale urine to obtain a crystallizable “microcosmic salt” that, when heated to redness, yielded a clear glass (soldium metaphosphate), ammonnia, and water. A lead calx-sal ammoniac mixture then reduced the “glass” to phosphorus. This method superseded Hellot’s preparation, but in 1774 and 1777 Scheele developed a more economical method of obtaining phosphorus from bone ash.

Marggraf attempted to confirm the contention of Stahl and Hellot that phosphorus is a mixture of “acid of sea salt” (hydroloric acid and phlogiston. When his efforts to produce phosphorus from hydrochloric acid without urine failed, he caustiously concluded that the acid of phosphorus is distinct and related to the “peculiar salt” in urine necessary for the synthesis of phosphorus. In 1746 he distinguished this salt from Haupt’s “sal mirabile perlato” (dodecahydrate of sodium phosphate) by the reducible product it yielded upon heating. Marggraf also substantiated Pott’s observation that phosphorus is contained in vegetable matter, and reasoned that the higher yields of phosphorus from urine in the summer are proportional to increased consumption of vegetable foods.

In 1750 Marggraf noted that the earth contained in “Bologna stone” (barium sulfide), another phosphorescent substance, is heavier and more soluble than lime. In the same memoir he anticipated Lavoisier’s conclusions by identifying the constituents of gypsum as water,lime, and vitriolic acid.

Until the invention of the Leblanc process, many chemists unsuccessfully sought an inexpensive means of converting common salt into soda for soap manufacture. With that motive Marggraf investigated (1758) the reasoning of H.-L. Duhamel du Monceau that the “alkali” of potash differs from that of rock salt. Besides using microscopic and flame tests, Marggraf recorded the difference in solubility or tendency to deliquescence of the sulfates, chlorides, and carbonates of sodium and potassium. He designated sodium salts as “mineral fixed alkali” and potassium compounds as “vegetable fixed alkali.” In 1764 he treated plant parts with acids to establish that the vegetable alkali is an essential plant constituent and not merely a product of distillation.

On at least two occasions Marggraf followed Hoffmann’s suggestions concerning the distinctiveness of particular “earths.” He showed in 1754 that alumina is a peculiar alkaline earth soluble in acids. Moreover, he refuted the notion of Stahl, Neumann, and Pott that lime is a constituent of alum and, like Lavoisier in 1777, insisted that potash or ammonia is indispensable for alum crystallization. Despite his ignorance of Black’s experiments, Marggraf recognized that magnesia, the “bitter earth” related to Epsom salt, is a “genuine and true alkaline earth”.

Even Marggraf’s less enduring achievements were sometimes remarkable challenges to existing assumptions. His assertion in 1747 that even “pure” commercially available tin contains up to 1/8 arsenic by weight raised doubts about the use of tin in food containers or kitchen utensils until the Bayen commission of the Paris School of Pharmacy concluded in 1781 that the arsenic impurities in various tin samples averaged 1/480 by weight (one grain per ounce). In 1768 Marggraf contradicted the assumption that earths are never volatile by alleging that a distillation of fluorspar with sulfuric acid partially “volatilized” the stone. Only in 1786 did Scheele identify the volatile substance as a mixture of a new acid (prepared by the action of concentrated sulfuric acid on solid fluorite) and glass (now recognized as silicon fluorite).

Marggraf sometimes retained an alchemical outlook—specifically in his memoirs of 1751 and 1756, in which he supported the conviction that water can be transformed into earth. In a 1743 discussion of the crystallization of “microcosmic salt” he had noted his expectation that silver in nitric acid, with phlogiston and a “fine vitrifiable earth”, would be subject to “partial transformation”; but he found no trace of a “nobler metal”.

Several of Marggraf’s pupils were also distinguished analytical chemists. Valentin Rose the elder (1736–1771), a Berlin apothecary, invented a fusible alloy of bismuth, tin, and lead; his son Valentin Rose the younger (1762–1807) was assessor (assistant) at the Berlin Ober-Collegium-Medicum; and their associate Martin Klaproth discovered uranium oxide and became first professor of chemistry at the University of Berlin.

Even without the technical achievements of Achard, Marggraf’s work would remain a valuable illustration of the eighteenth-century search for precision in laboratory techniques and for purity in chemical reagents, as well as of the refusal to construct grand theory.

BIBLIOGRAPHY

I. Original Works. A full list of Marggraf’s memoirs was complied by O. Köhnke in Adolf von Harnack, Geschichte der Königlich Preussischen Akadedemie der Wissenschaften zu Berlin, III (Berlin, 1900), 179–181. The originals appear in the publications of the Berlin Royal Society of Sciences and Royal Academy of Sciences (1740–1781); Miscellanea Berolinensia ad incrementum scientiarum …, 7 vols. (Berlin, 1710–1743); Histories de l’s Académie royale des sciences et des belles-letters de Berlin, … avec les mémories … 25 vols. (Berlin, 1746–1771); and Nouveaux mémories de l’Académie royale des science et bellesletters …, 17 vols. (1772–1788). With the editorial assistance of J.-G. Lehmann, Marggraf collected his memoirs and added four MS dissertations in Chymische Schriften, 2 vols. (Berlin, 1767–1767), rev. ed. of vol. I appeared in 1768. Formey’s French trans. of vol. I was published by J. F. Demachy as Opuscules chymiques, 2 vols. (Paris, 1762). An annotated German text of three memoirs is available in Ostwalds Klassiker: Einige neue methoden, den Phosphor in fenten Zustande sowohl leicher als bisher aus dem Urin darzustellen …, G. Mielke, ed. (Leipzig, 1913), which includes “Chemische Untersuchungen eines sehr bemerkenswerten Salzes, welches die Säure des Phosphors enthält” (1746). See also Versuche einen wahren Zucker ausverschiedenen Pflanzen, die in unseren Ländern wachsen, zu ziehen, Edmund O. von Lippmann, ed. (Leipzig, 1907).

II. Secondary Literature. See Condorcet, “Éloge,” in Historie de l’Académie for 1782 (Paris, 1785), 122–131, repr. in Condorcet’s Oeuvres, A. Condorcet O’Connor, ed. (Paris, 1847), II 598–610; Formey, in Histoire de l’ Académie … de Berlin, année 1783 (Berlin, 1785), 63–72; A. de L., in Nouvelle biographie générale, XXXIII (Paris, 1860), cols. 549–553; Edmund O. von Lippmann, “Andreas Sigismund Marrgraf,” in Eduard Farber, ed., Great Chemists (New York—London, 1961), 193–200; Max Speter, “Marggraf,” in Gunther Bugge, ed., Das Buch der grossen Chemiker, I (Berlin, 1929), 231–234; and John Ferguson, Bibliotheca chemica II (Glasgow, 1906), 76–77.

The best single summary is in J.R. Partington, A History of Chemistry, II (London, 1961), 723–729. See also Frederic L. Holmes, “Analysis by Fire and Solvent Extractions: The Metamorphosis of a Tradition,”, in Isis,62 (1971), 129–148; Hermann Kopp, Geschichte der Chemie, I (Brunswick, 1843), 208–211; Max Speter, “Zur Geschichte des Marggrafschen Urin-Phosphors,” in Chemisch-technishe Rundschau,44 (13 Aug. 1929), 1049–1051; Ferenc Szabadváry, History of Analytical Chemistry, G. Svehla, trans. (Oxford, 1966), 51–52, 55–59; and Mary Elvira Weeks, Discovery of the Elements, 7th ed. (Easton,Pa., 1968), 497–498, 560–561, 861–864.

Martin S. Staum

Andreas Marggraf

Andreas Sigismund Marggraf (1709-1782) was an important figure in chemistry as it evolved from alchemy in the eighteenth century. He worked on a broad range of subjects, concentrating on problems in the areas of inorganic, organic, and analytical chemistry. He isolated several elements, made an important discovery about sugar, and was one of the first to use a microscope in the field of chemistry.

Marggraf was born on March 3, 1709 in Berlin. His mother was Anne Kellner, about whom little is known. His father was Henning Christian Marggraf, an apothecary to the Royal Court located in Berlin. The elder Marggraf was also an assistant at the medical school (Collegium Medico-Chirurgicum) and did some chemical research. Andreas Marggraf received a well-rounded training in chemistry that began with his father's various connections.

Marggraf was the last important German chemist to believe in the flawed theory of phlogiston, according to Isaac Asimov in his Asimov's Biographical Encyclopedia of Science and Technology. Phlogiston was the theory proposed and popularized by Georg Ernst Stahl that materials were composed of air, water and three earths and that one of these earths escaped from any material during combustion. Perhaps the reason for Marggraf's adherence to this theory, despite the fact that materials often increased in weight when burned, was that one of his first teachers was his father's colleague, Caspar Neumann, an adherent to Stahl's theory. Marggraf studied under Neumann from 1725 through 1730.

According to an entry in the Dictionary of Scientific Biography, by Martin S. Staum, Marggraf further learnt his craft from an apothecary in Frankfort-am-Main, next studied at the University of Strasbourg, and then studied metallurgy in Freiburg. From 1935 through 1953, Marggraf ran his father's apothecary at the court. In 1737, his background and connections helped win him an opportunity he refused, that of a ducal apothecary appointment in Wolfenbuttel, Brunswick.

Instead, Marggraf was admitted in 1738 as a member of the Koniglich Preussischen Societat der Wissenchaften (Prussian Society of Sciences) and remained an unpaid member until 1744. In 1746 the organization was reorganized and renamed Academie Royale Des Sciences et Belles-Lettres. Frederick II named Marggraf director of the chemical laboratory at the Academie in 1753 and Marggraf became director of the physical class in 1760. He remained in these positions until 1782. During this time, he also gave private instruction in chemistry.

The Chemical Work

Marggraf was a precise and careful chemist, painstaking in his work and in his recording of that work. He was known more for experimenting and describing rather than for postulating and theorizing. Before Marggraf, the alchemists had tried to discover ways to change metals into gold as well as discover the key to perpetual youth. Alchemy was the study of transmutation-the change of a substance into something more desirable.

Marggraf worked with various materials and documented what he found using the balance for weighing exact amounts, both before and after the experimental tests. He was creative in his use of solvents to extract, and then to recrystallize the substance extracted. He also used flame tests to determine differences in substances as the flame burned in different colors depending on the substance burned. This method predates the more modern emission spectroscopy. A metal blowpipe was used for his experiments. This was a tube that heightened the flame by including more air in order to see the colors more vividly. It also allowed one to see the type of debris the substance would leave as it interacted with the metal.

Phosphorus was a rare substance in Marggraf's time, and he found a simple way to prepare it. He evaporated putrefied urine and mixed its salts with "chloride of lead, sand and coal," according to E. O Von Lippmann in the essay on Marggraf he contributed to the book Great Chemists. After heating for four hours and redistilling, it was pure white and clear, and could be poured into glass tubes with the appearance of rods. Marggraf noted that when burned it increased in weight and formed a mass that was feathery. Also, when this phosphorus was dissolved in water it formed phosphoric acid, a substance that was unknown until that time. It could be returned to phosphorus by heating with coal, which was an improvement over previous methods of obtaining phosphorus.

Next, Marggraf tried to produce phosphorus from hydrochloric acid without using urine, as previous scientists had suggested that this was possible. He failed. This led him to suggest that the type of salt contained in urine was necessary in order to produce phosphorus. Staum tells us that Marggraf also substantiated another scientist's statement that phosphorus is contained in vegetable matter and Marggraf figured that "the higher yields of phosphorus from urine in the summer are proportional to increased consumption of vegetable foods."

According to Von Lippmann, the mineral and vegetable alkalies (soda and potash) were thought to be identical, "or the alkali of marine salt (sodium chloride) was held to be analogous to lime." Marggraf demonstrated that these materials were different by one of his painstaking experiments. He observed that potassium chloride when converted to nitrate turned into a needlelike salt and when burned turned the flame blue-violet. However, nitrated marine salt was cubic and turned its flame yellow when burned. The potassium sulfate was barely soluble while the sulfate of the marine salt was much more soluble. After observing all this, Marggraf reasoned that the alkalies were present in the plant before the ashing process began. As Von Lippman states, Marggraf wrote that the plant resource for these salts was that it "attracts them out of the soil, out of water and air."

The Sugar Beet

One of the most significant of Marggraf's findings, at least in terms of its impact on industry, is his discovery that sugar from beets was exactly the same as sugar from cane. Before his time, efforts had been made to extract sugar from many other fruits, vegetables and even nuts. Marggraf postulated that sugar from sweet-tasting plants must contain a sugary substance, so he investigated the white beet, the beet root and the red beet. First he sliced, dried and pulverized the three plant parts just mentioned. Next, with the use of boiling alcohol, he extracted their juice, by filtering and then letting this juice crystallize in corked tubes for several weeks as the liquid evaporated. Once the crystal stage was reached, he examined these crystals under a microscope. This was perhaps the first use of a microscope for chemical identification. The crystals seen under the microscope were identical to those of cane sugar.

Though large-scale production of sugar from beets did not take place in Marggraf's lifetime, he recognized the significance of the discovery. Previous to this time, sugar had been made from cane, which was to be found in the warmer climates such as the West Indies. It was traded to England and other places in Europe and these places experienced high prices and shortages when they were unable to get sugar due to war blockades, especially during the Napoleonic Wars that began at the end of the eighteenth century.

However, Marggraf's discovery and influence made its mark because his student, Achard, tried his experiment on a large-scale, produced a significant amount of sugar, estimated the cost to be six cents per pound, and interested the French Institute in investigating his claims. This was enough to cause King William III of Prussia to finance a sugar beet factory and thus the industry was born. Marggraf's work had reached beyond his time and today sugar is made from beets in many countries all over the world.

Marggraf himself had recognized that this was a boon for the poor farmer when he wrote, as Von Lippmann has it: "There should be no doubt by now that this sweet salt, sugar, can be made from our own plants just as well as from sugar cane." Also, in the book The Story of Alchemy and Early Chemistry, John Maxson Stillman quotes Marggraf: "the poor cultivator could well serve himself with this plant sugar or its syrup instead of the usual costly product, and if by help of inexpensive machines he pressed this juice from these plants, somewhat purified it, and reduced it to the consistency of a syrup." Thus Marggraf realized the real practical implications of his work for the domestic farmer of his time.

Other Findings

Marggraf's other scientific work was important, if not as immediately applicable as his work with beets. He discovered magnesia by decomposing a serpentine mineral; he found another distinct material, alumina; did experiments that isolated zinc by creating an industrially useful distilling process from calamine. He demonstrated that iron was present in limestone and in the ashes of many plants by the fact that these reacted with red prussiate of potash (the equivalent of potassium ferrocyanide). One of his experiments showed that selenite was chemically the same as gypsum.

He worked with cedar wood to isolate cedar oil by steaming it at lower temperatures than its actual boiling point. This process was then used to isolate other oils. He distilled ants into an oil and an acid. He froze and redistilled the acid to purify it. This type of acid forms salts when mixed with alkalies, ammonia, some metals, and reduces mercuric oxide to the metal.

Despite his prolific work in chemistry, Marggraf was never in the best of health. He had a stroke in 1774 and was ill from that time until his death in Berlin on August 7, 1782. However, he left numerous discoveries and observations to the world of chemistry.

Von Lippman tells us that Marggraf's motto was "care and cleanliness in working." He was an introvert who kept out of politics and dedicated his life to his work in chemistry. His methods of careful weighing and measuring both before and after reactions yielded much quantitative information for future scientists. His patience when waiting for crystallization, poisoning, and other reactions lent credence to the importance of time in chemical reactions. He laid much groundwork for future chemists, not to mention the practical implications of his work for industrialists.

Books

Asimov, Isaac, Asimov's Biographical Encyclopedia of Science and Technology, Doubleday and Company, Inc., 1982.

The Beet Sugar Story, The United States Beet Sugar Association, 1959.

Farber, Eduard, The Evolution of Chemistry, The Ronald Press Company, 1969.

Farber, Eduard, Great Chemists, Interscience Publishers, 1961.

Gillispie, Charles Coulston, Dictionary of Scientific Biography, Charles Scribner's Sons, 1974.

Hufbauer, Karl, The Formation of The German Chemical Community (1720-1795), University of California Press, 1982.

Hudson, John, The History of Chemistry, Chapman and Hall, 1992.

Stillman, John Maxson, The Story of Alchemy and Early Chemistry, Dover Publications, 1960. □

Andreas Marggraf

1709-1782

German biologist whose discovery of sugar in sugar beets made possible a revolution in food production. Prior to this discovery, sugar was a very rare commodity, imported from overseas. The ability to grow and produce sugar locally led to a huge increase in sugar production and consumption, leading in turn to an increase in tooth decay, obesity, and other problems related to excessive sugar and caloric intake. It also was crucial to the still-widespread popularity of industries devoted to satisfying the human sweet tooth.