Klaproth, Martin Heinrich

(b. Wernigerode, Germany, I December 1743; d. Berlin, Germany, 1 January 1817)

chemistry.

“Suffer and hope”—with these words Klaproth in 1765 captured the essence of his youth. The third son of Johann Julius Klaproth, a poor but respected tailor with pietistic leanings, he had been intended for the clergy. Shortly after his fifteenth birthday, however, an unpleasant incident apparently forced him to drop out of Wernigerode’ Latin school. Deciding to take up pharmacy, probably because of its connection with the natural sciences, Klaproth became an apprentice in a Quedlinburg apothecary shop in 1759. His master worked him hard, giving him little, if any, theoretical training and less spare time. In 1766, two years after becoming a journeyman, he moved, in the same capacity, to Hannover. There, at last, he had the opportunity to begin transcending pharmacy. Choosing chemistry, he read the texts of J. F. Cartheuser and J. R. Spielmann and conducted many minor investigations. After two years in Hannover, followed by two and a half years in Berlin and a few months in Danzig, Klaproth settled at Berlin in 1771. During his first decade there he supported himself by managing the apothecary shop of a deceased friend, the minor chemist Valentin Rose the elder. In 1780 he finally gained self-sufficiency—a fortunate marriage to A. S. Marggraf’ wealthy niece enabled him to purchase his own shop.

In the meantime Klaproth had continued his pursuit of chemistry, studying not only by himself but also, it seems, with Marggraf. He ventured into print for the first time in 1776 when a friend persuaded him to contribute a chapter on the chemical properties of copal to a book on the natural history of that resinous substance. By 1780 he felt sufflciently knowledgeable to request permission to give private lectures on chemistry under the auspices of Berlin’ Medical-Surgical College. The college’s professors, who were eager to avoid such competition for student fees, blocked his request. In 1782, after publishing several articles on chemical topics and securing the backing of influential Masonic brothers, Klaproth was in a stronger position. That year he was named to the second seat for pharmacy on Prussia’s highest medical board and soon afterward was granted permission to lecture on chemistry. Thus, at the relatively advanced age of thirty-nine, he embarked on his administrative and teaching career.

Over the years Klaproth moved up in the Prussian medical bureacracy from assessor (1782-1797) to councillor (1797-1799), to high councillor (1799-1817). Meanwhile he secured teaching posts, serving as private lecturer at the Medical-Surgical College (1782- 1810); teacher of chemistry at the Mining School (1784-1817); professor of chemistry at G. F. von Tempelhoff’ Artillery School and its successors, the Royal Artillery Academy and the General War School (1787-1812?); and full professor of chemistry in the University of Berlin’ Philosophical Faculty (1810-1817). In 1800 Klaproth was appointed to succeed F. K. Achard as the Berlin Academy’s representative for chemistry. No longer needing his apothecary shop, he sold it at a handsome profit and moved into the academy’s new laboratory-residence complex in 1803. Here Klaproth, the tailor’s son who once could only “suffer and hope,” worked until his death from a stroke on New Year’s Day 1817.

Although his wealthy wife and influential friends had helped Klaproth launch his career, it was his accomplishments as a chemist that propelled his subsequent rise. His most important work was in analytical chemistry. Indeed, he was the leading analytical chemist in Europe from the late 1780’s, when he established himself as Bergman’s intellectual successor, until the early 1800’s, when Berzelius gradually took his place. Working with minerals from all parts of the globe, Klaproth discovered or codiscovered zirconium (1789), uranium (1789), titanium (1792), strontium (1793,) chromium (1797), mellitic acid (1799), and cerium (1803) and confirmed prior discoveries of tellurium (1798) and beryllium (1798). More consequential than these specific results were Klaproth’s new techniques. For instance, he found that many particularly insoluble minerals could be dissolved if they were first ground to a fine powder and then fused with a carbonate. With his student Valentin Rose the younger he introduced the use of barium nitrate in the decomposition of silicates. He constantly drew attention to the necessity of either avoiding or making allowances for contamination from apparatus and reagents. Most significant, he broke with the tradition of ignoring “small” losses and gains in weight in analytical work. Instead, he used discrepancies over a few percentage points as a means of detecting faulty and incomplete analyses. Once satisfied with his procedure for analyzing a mineral, he reported his final results—including the remaining discrepancy. This practice became a convention with the next generation of analysts.

Besides his influence as an analyst, Klaproth played a role of some consequence in the German acceptance of Lavoisier’s theory. In the spring of 1792, after studying his friend S. F. Hermbstäadt’s manuscript translation of Lavoisier’s Traité and repeating some of its main experiments, he announced his tentative support for the antiphlogistic system. During the ensuing year he often joined with Hermbstäadt in repeating the reduction of mercuric oxide before skeptical and important witnesses. By the summer of 1793 they had discredited F. A. C. Gren and other phlogistonists who denied the accuracy of Lavoisier’ account of the experiment, thereby preparing the way for the success of the antiphlogistic revolution in Germany. In the remaining decades of his life, however, Klaproth avoided taking an active part in the theoretical development of chemistry.

Klaproth’s aversion to theory in no way dampened international enthusiasm for his work. Among the numerous honors that he received were membership in the Royal Society of London (1795) and, far more important, membership as one of six foreign associates in the Institut de France (1804).

BIBLIOGRAPHY

A complete list of Klaproth’s many publications appears in Georg Edmund Dann, Martin Heinirch Klaproth (1743-1817): Ein deutscher Apotheker und Chemiker Sein Weg und seine Leistung (Berlin, 1958). That Klaproth was Marggraf’s student is revealed by Lorenz von Crell, “Lebensgeschichte Andreas Sigismund Marggraf’s . . .,” in Chemische Annalen, no 1 (1786), 181-192.. For an appreciative assessment of Klaproth’s work by a member of the next generation of analytical chemists, see Thomas Thomson. The Histroy of Chemistry II (London, 1831), 191- 210. For Klaproth’s role in the German antiphlogistic revolution, l see Karl Hufbauer, “The Formation of the German Chemical Community, 1700-1795” (University of California, Berkeley, 1970), diss., chs. 6-7.

Karl Hufbauer