Kirchhof, Konstantin Sigizmundovich (Gottlieb Sigismund Constantin)

(b. Teterow, Mecklenburg-Schwerin [now D.D.R.], 19 February 1764; d. St. Petersburg, Russia, 14 February 1833)

chemistry.

Kirchhof’s father, Johann Christof Kirchhof, owned a pharmacy until 1783 and at the same time was a postmaster. His mother, the former Magdalena Windelbandt, was the daughter of a tin smelter.

In his youth Kirchhof helped his father run the pharmacy; after the latter’s death in 1785 he worked in various pharmacies in the duchy of Mecklenburg-Schwerin, qualifying as a journeyman apothecary. In 1792 he moved to Russia and worked in the same capacity at the St. Petersburg Chief Prescriptional Pharmacy. From 1805 he was a pharmacist and became a member of the Fizikat Medical Council, a scientific and administrative group that supervised the checking of the quality of medicaments and certain imported goods. Kirchhof began his chemical studies under Tobias Lowitz, the manager of the pharmacy, and A. A. Musin-Pushkin. A few of his works were undertaken jointly with A. N. Scherer, and all of his scientific activity was carried out in Russia. In 1805 he was elected a corresponding member, in 1809 an adjunct, and in 1812 an academician adjunct of the St. Petersburg Academy of Sciences. In 1801 Kirchhof was elected a member of the Mecklenburg Natural Science Society, in 1806 a member of the Russian Independent Economical Society, in 1812 a member of the Boston Academy of Sciences, in 1815 a member of the vienna Economical Society, and in 1816 a member of the Padua Academy of Sciences.

Kirchhof’s first major discovery was the decomposition of barite with water, which Lowitz reported in “Vermischte chemische Bemerkungen” (Chemische Annalen [1797], 179-181), explicitly mentioning the discoverer. Klaproth had discovered this reaction much earlier. In 1797 Kirchhof reported two important results: the bleaching of shellac, which had an appreciable significance for the production of sealing wax, and a wet process that made it possible to begin industrial production of cinnabar. Cinnabar was produced of such high quality that it supplanted imported cinnabar, and some was exported. In 1805 Kirchhof developed a method for refining “heavy earth” (barite) by allowing caustic potash to react with barium salts. In 1807 he entered a competition organized by the Independent Economical Society to develop a method for refining vegetable oil. In collaboration with Alexander Crichton he worked out the sulfuric acid method of refining oil and received a prize of 1,000 rubles. The two men founded an oil purifying plant in St. Petersburg on Aptekarskiy Island, the largest factory at that time, with an output of about 4,400 pounds of oil per day. In many respects (for example, in the method of adding acid and the clarification of oil by glue) Kirchhof’s method is closer to modern methods than that of Thénard (1801).

In 1809 Kirchhof resigned from the Chief Prescriptional Pharmacy but continued to carry out the assignments of the Fizikat Medical Council in his laboratory there; he also conducted investigations in his home laboratory. During this period he began prolonged research to find a method for producing gum from starch in order to supplant the imported products; he then began investigating the optimal conditions for obtaining sugar from starch.

Kirchhof studied the action of mineral and organic acids (sulfuric, hydrochloric, nitric, oxalic and so on) on starch and found that these acids inhibit the jelling of starch and promote the formation of sugar from starch. He also studied the effect of acids on the starches of potatoes, wheat, rye, and corn as well as the effect of acid concentration and temperature on the rate of hydrolysis. At the same time he was searching for new raw materials for producing sugar by the hydrolysis of starch. In 1811 Kirchhof presented to the St. Petersburg Academy of Sciences the samples of sugar and sugare syrup obtained by hydrolysis of starch in dilute acid solutions. He advanced a technological method for producing sugar that was based on his investigations published in 1812. Best results were obtained by adding 1.5 pounds of sulfuric acid in 400 parts of water to 100 pounds of starch. The duration of reaction was between twenty-four and twenty-five hours at 90-100° C. The bulk of the acid did not enter into the reaction with starch, because after completion of the reaction, Kirchhof neutralized it with a specific amount of chalk. This was the first controlled catalytic reaction.

In 1814 Kirchhof submitted to the Academy of Sciences his report “Über die Zucker bildung beim Malzen des Gestreides und beim Bebrühen seines Mehl mit kochendem Wasser,” which was published the following year in Schweigger’s Journal für Chemie und Physik. This report describes the biocatalytic (amylase) action, discovered by Kirchhof, of gluten and of malt in saccharifying starch in the presence of these agents. He showed that gluten induces saccharification of starch even at 40-60° C. in eight to ten hours. During the first hour or two the starch paste was converted into liquid, which after filtration became as transparent as water. Mashed dry barley malt saccharified the starch at 30° R. in one hour. Similarly, Kirchhof studied the starch contained in the malt, separating starch from gluten by digesting it with a 3 percent aqueous solution of caustic potash. The starch treated in this manner could not be converted into sugar. Thus he proved that malt gluten is the starting point for the formation of sugar, while starch is the source of sugar.

The catalytic enzyme hydrolysis of starch discovered by Kirchhof laid the foundation for the scientific study of brewing and distilling and resulted in the creation of the theory of the formation of alcohol.

In his last years of scientific activity Kirchhof developed a method of producing unglazed pottery by treating it with drying oils; a method to refine chervets (a substitute for cochineal) from oily substances; and a method for rendering wood, linen, paper, and other substances nonflammable. For refining chervets he suggested the regeneration of turpentine by mixing it with water and then distilling the mixture.

Kirchhof also conducted research assigned by the Academy of Sciences, including analysis of gun-powders, William Congreve’s rocket fuel, mineral samples, and mineral and organic substances.

BIBLIOGRAPHY

I. Original Works. Kirchhof’s writings include “O privedenii chistoy tyazheloy zemli v kristaly posredstvom prostogo sredstva” (“On Crystallizing Pure Barite by Simple Means”), in Tekhnologichesky zhurnal,4 no. 2 (1807), 116-119; “Über Zucker und Syrop aus Kartoffelmehle Getreide und Andere,” in Bulletin des Neusten und Wissenwürdigsten aus der Naturwissenschaft. . .,10 (1811), 88; “O prigotovlenii sakhara iz krakhmala” (“On the Preparation of Sugar From Starch”), in Tekhnologichesky zhurnal,9 , no. 1 (1812), 3-26; and “über die Zuckerbildung beim Malzen des Getreides und beim Bebrühen seines Mehl mit kochendem Wasser,” in Schweigger’s Journal für Chemie und Physik,14 (1815), 389-398.

II. Secondary Literature. On Kirchhof’s life or work, see S. N. Danilov, “Khimia sakharov v Rossii” (“Chemistry of Sugar in Russia”), in Materialy po istorii otechestvennoy khimii (“Papers on the History of Russian Chemistry”; Moscow, 1951), pp. 282-283; A. Mittasch and E. Theiss, Von Davy und Dobereiner bis Deacon, ein halbes Jahrhundert Grezflāchenkatalyse Berlin, 1932); pp. 14, 97, 243; A. A. Osinkin, “Zhizn i deyatelynost akademika K. Kirkhgofa” (“The Life and Work of Academician K. Kirchhof”), in Trudy Instituta istorii Estestvoznaniya i tekhniki. Akademiya nauk SSSR,30 (1960), 253-287; and A. N. Shamin, Biokataliz i biokatalizatory (istorichesky ocherk) (“Biocatalysis and Biocatalysts [A Historical Note]”; Moscow, 1971), 51-54, 102-117, 171-183.

A. N. Shamin
A. I. Volodarsky