MULDER, GERARDUS JOHANNES

(b. Utrecht, Netherlands, 27 December 1802; d. Bennekom, Netherlands, 18 April 1880)

Chemistry.

Mulder studied medicine at the University of Utrecht (1819–1825), from which he graduated with a dissertation on the action of alkaloids of opium, De opio ejusque principiis, actione inter se comparatis (1825). He practiced medicine in Amsterdam and then in Rotterdam, where he also lectured at the Bataafsch Genootschap der Proefondervindelijke Wijsbegeerte and taught botany to student apothecaries. At the foundation of a medical school at Rotterdam (1828), Mulder became lecturer in botany, chemistry, mathematics, and pharmacy. His attention was directed primarily to the practical training of his students. In 1840 Mulder succeeded N. C. de Fremery as professor of chemistry at the University of Utrecht. He applied for his retirement in 1868 and spent the rest of his life in Bennekom. Besides publishing on scientific subjects, Mulder took an active part in education, politics and public health. The works of Faraday and Berzelius exerted a great influence on him; his Leerboek voor Scheikundige werktuigkunde (1832–1835) was written in the spirit of Faraday’s Chemical Manipulation. Mulder edited a Dutch translation by three of his students of Berzelius’ textbook of chemistry as Leerboek der Scheikunde (6 vols., 1834–1845). His difficult character caused problems with some of his pupils and with other chemists.

From 1826 to 1865 Mulder edited five Dutch chemical journals (see bibliography), in which most of his work was published. He worked in physics and in both general and physical chemistry, the latter in combination with medicine, physiology, agriculture, and technology. Most of his work had a polemic character. His most important contributions are in the field of physiological chemistry and soil chemistry, in which he published two extensive works that attracted much attention in translation despite their many mistakes and erroneous speculations.

Studies on proteins led Mulder to his protein theory (1838): he supposed that all albuminous substances consist of a radical compound (protein) of carbon, hydrogen, nitrogen, and oxygen, in combination with varying amounts of sulfur and phosphorus. The differences among proteins resulted from multiplication of the protein units in conjunction with the two other elements. Thus, casein was formulated as

10 protein units + S,

and serum albumin as

10 protein units + SP₂.

In 1843 Mulder published the first volume of a treatise on physiological chemistry, which was translated into English as The Chemistry of Vegetable and Animal Physiology (1845–1849). At first both Liebig and Berzelius accepted Mulder’s analysis of proteins; but Liebig soon opposed the theory vigorously, and a deep conflict with Mulder ensued. In 1839–1840 Mulder investigated humic and ulmic acids and humus substances and determined the amounts of geic acid (acidum geïcum), apocrenic acid (acidum apocrenicum or Quellsatzsäure), crenic acid (acidum crenicum or Quellsäure), and humic acids in fertile soils (1844). The structure of these various brown or black substances is unknown. They are a group of aromatic acids of high molecular weight, which can be extracted from peat, turf, and decaying vegetable matter in the soil. The difference between these acids is the oxygen content. In the decay of vegetable matter ulmic acid is formed. According to Mulder, this has the formula C₂₀H₁₄O₆(in modern equivalents). In contact with air and water more oxygen is absorbed, which results in the successive formation of humic acid (C₂₀H₁₂O₆, geic acid (C₂₀H₁₂O₇), apocrenic acid C₂₄H₁₂O₁₂, and crenic acid (C₁₂H₁₂O₈).

His studies on agricultural chemistry led to the treatise De scheikunde der bouwbare aarde (1860). Mulder confirmed Berzelius’ suggestion that theine and caffeine are identical (1838) and was the first to analyze phytol correctly in his researches on chlorophyll. Among his other works are technical chemical publications on indigo (1833), wine (1855), and beer (1857), detailed research on the assaying method for analyzing silver in relation to the volumetric silver determination of Gay-Lussac (1857), and a study on drying oils (1865).

BIBLIOGRAPHY

I. Original Works. Mulder’s writings include Dissertatio de opio ejusque principiis, actione inter se comparatis (Utrecht, 1825); Leerboek voor Scheikundige Werktuigkunde, 2 vols, (Rotterdam, 1832–1835); Proeve eener algcmeene physioloaische scheikunde, 2 vols. (Rotterdam, 1843–1850). translated as The Chemistry of Vegetable and Animal Physiology (Edinburgh, 1845–1849); De vraag van Liebig aan de zedelijkheid en de wetenschap getoetst (Rotterdam, 1846), also in Scheikundige onderzoekingen, 3 (1846), 357–487, and translated as Liebig’s Question to Mulder Tested by Morality and Science (London, 1846); “De essayeermethode van het zilver scheikundig onderzocht,” which is Scheikundige verhandelingen en onderzoekingen, 1 , pt, I (1857); De scheikunde der bouwbare aarde, 4 vols, (Rotterdam, 1860); and “De scheikunde der droogende olieën en hare toepassing,” which is Scheikundige verhandelingen en onderzoekingen, 4 , pt. 1 (1865). Journals edited by Mulder are Bijdragen tot de natuurkundige wetenschappen, 7 vols. (Amsterdam, 1826–1832), with H. C. van Hall and W. Vrolik; Natuuren scheikundig archief, 6 vols, (Rotterdam, 1833–1838); Bulletin des sciences physiques et naturelles en Néerlande, 3 vols. (Leiden, 1838–1840), with F. A. W. Miquel and W. Wenckebach; Scheikundige onderzoekingen, gedaan in het laboratorium der Utrechtsche hoogeschool, 6 vols. (Utrecht, 1842–1851); and Scheikundige verhande lingen en onderzoekingen, 4 vols. (Utrecht, 1857–1865).

II.Secondary Literature. See the biography by W. Labruyère, G. J. Mulder (1802–1880) (Leiden, 1938),

with bibliography, pp. 113–130. See also E. Cohen, “Wat leeren ons de archieven omtrent Gerrit Jan Mulder?” which is Verhandeleling der K. akademie van wetenschappen. Afdeling Natuurkunde, 19 , pt. 2 (1948). An autobiographical sketch of Mulder was published posthumously as Levensschets. Door hemzelven geschreven en door drie zijner vrienden uitgegeven (Rotterdam, 1881; 2nd ed. Utrecht, 1883). Mulder’s correspondence with Berzelius was published as Jac. Berzelius Bref, H. G. Söderbaum, ed., V (Uppsala, 1916), Briefväxling mellan Berselius och G. J. Mulder (1834–1837).

H. A. M. Snelders

Mulder, Gerardus Johannes (1802–80) Dutch physiological chemist; coined the name protein for the nitrogenous constituents of all living tissue, to show they were ‘of first importance’.