Schönbein, Christian Friedrich
SCHöNBEIN, CHRISTIAN FRIEDRICH
(b. Metzingen, Swabia [now West Germany], 18 October 1799; d. Sauersberg, near Baden-Baden, Germany, 29 August 1868)
His family’ financial condition would not permit any advanced schooling, and at the age of fourteen Schoönbein became an apprentice in a chemical and pharmaceutical factory in Böblingen. He acquired a profound knowledge of theoretical and applied chemistry, and he also privately studied Latin, French, English, philosophy, and mathematics.
In April 1820 Schönbein obtained a post at the chemical factory of J. G. Dingler in Augsburg, where he assisted Dingler in making German translations of French publications for the new Dinglers polytechnisches Journal. In his spare time Schönbein studied chemistry and later, in 1820, accepted a post in the chemical factory of J. N. Adam in Hemhofen, near Erlangen. He frequently visited the University of Erlangen, where he met the philosopher Schelling; J. W. A. Pfaff, professor of physics and mathematics; and G. H. Schubert, the Naturphilosoph and professor of zoology. He remained friends with Schelling until the latter’s death in 1854. After a semester, Schönbein moved to Tübingen but in February 1823 returned to Erlangen.
Although largely a self-educated chemist, Schönbein taught (1823) chemistry, physics, and mineralogy at Friedrich Froebel’s institute in Keilhau, a small town near Rudolfstadt, in Thuringia. In 1826 he was in England, where he taught mathematics and natural philosophy at a boys’ school in Epsom (1826), and in 1827 he went to France, where he attended the lectures of Gay-Lussac, Ampère, César Despretz, and Thenard. In 1828 Schönbein moved to Basel. He received the Ph.D. honoris causa from the faculty of philosophy there and also lectured on physics and chemistry. In 1835 he was appointed professor of physics and chemistry at the University of Basel, where he remained until his death. In 1852, when the professorship was divided, Schönbein retained the chair of chemistry. From 1848 he was a member of the Basel parliament.
Schönbein was also interested in philosophy. The influence of Naturphilosophie (he was also a friend of Lorenz Oken) is evident in all of Schönbein’s work, especially in his speculative views that lack a sufficient experimental basis. Schönbein published more than 350 works, mostly qualitative, covering a wide range of research—but especially ozone, autoxidation, induced reactions, guncotton, electrochemistry, and passive iron. Schönbein’s speculative bent is evident even in his early studies (from 1835 on) on the passivity of iron. He started from the well-known fact that iron reacts with dilute nitric acid but not with concentrated nitric acid. He sought to explain this phenomenon as a type of polymerism (he himself spoke always of isomerism) and thus disagreed with Faraday’s explanation of a layer of oxide on the iron. Schönbein assumed that a conversion of the metallic iron takes place. Thus he agreed with Friedrich Fischer, professor of philosophy at Basel, who accounted for the passivity of iron by means of polarization, through which the pure attracting chemical affinity is changed into attraction and repulsion.
Schönbein thought that the iron particles possessed two “poles,” one that attracts and one that repels (1838). But under certain conditions the poles that attract oxygen are directed to the inside of the metallic iron while those that repel oxygen are directed to the outside, thus producing passive iron. To account for this passivity Schönbein assumed that iron in the passive state possesses on its surface the properties of a “noble” metal. Consequently, he questioned the status of iron as an element: if iron can be converted into a noble metal, would all other metals possess the same property? He claimed that too little is known about the nature of matter and the workable forces in it to give definitive answers to these questions. Schönbein’s reasoning was based on the analogies he drew from his 1835 lecture on isomerism, in which he stated that all known examples of isomerism (for example, tartaric and racemic acids, fulminic and cyanic acids) are dimorphic, with the exception of sulfur. He concluded that all dimorphic substances must be composite, and that sulfur is a compound.
Schönbein is known primarily for his work on ozone. While conducting experiments on the decomposition of water (autumn 1839), he noticed that the oxygen obtained in the process had a peculiar odor similar to that produced when a large electrical machine is operating—a similarity first noted by the Dutch chemist van Marum (1785). Schönbein recognized that the substance is a gas, that it is produced at the anode, and that it resembles chlorine and bromine in its chemical and electric properties. He studied extensively the properties of this gas and found (1844) that it is produced when phosphorus glows in air. He also discovered that it bleaches litmus, frees iodine from potassium iodide, and changes potassium ferrocyanide into ferricyanide.
Schönbein’s ideas concerning the nature of ozone were rather confused. At first, he thought that nitrogen is composed of ozone and hydrogen. But phosphorus cannot decompose nitrogen (“ozone-hydrogen”) unless another substance is present that can combine with the hydrogen. That substance is oxygen. Thus nitrogen is decomposed by phosphorus only in the presence of oxygen. The hydrogen in the nitrogen reacts with the oxygen of the water and ozone partly liberates and partly is bound with the phosphorus to “ozone-phosphorus.” Like phosphorus trichloride, “ozone-phosphorus” is decomposed by water, namely into phosphorous acid and nitrogen. Schönbein saw a strong analogy between ozone and the halogens chlorine and bromine. Because the electrical, chemical, and physiological reactions of ozone closely resemble those of chlorine and bromine, he concluded that ozone also forms a salt and that its chemical affinity must place it directly after chlorine.
In 1845 Marignac and Auguste Arthur de la Rive proved independently that ozone is formed by an electric spark in pure, dry oxygen. They regarded ozone as oxygen in a particular state of chemical affinity. Although Schönbein persisted in his belief that ozone is a compound, he held that its oxidation state is higher than that of hydrogen, or even more likely, that it is a particular compound of water and oxygen. He suggested that there are three forms of oxygen: ozone, antozone, and ordinary oxygen, the last being a neutralization product of the first two. Similarly, Schönbein concluded that chlorine is a compound. Only in 1851 did he declare that, in all probability, ozone is an allotropic form of oxygen.
In the field of physical chemistry Schönbein studied the phenomenon of autoxidation; the spontaneous oxidation of a substance by atmospheric oxygen, part of which combines with the substance while a second part is converted into ozone or “antozone” (hydrogen peroxide) or combines with another substance. From various reactions, he concluded that ordinary oxygen is converted into ozone and antozone. Oxidation of phosphorus yields ozone; oxidation of metals in the presence of water yields antozone. Schönbein also studied induced reactions. To investigate this phenomenon he first used compounds of sodium sulfite and sodium arsenite; only the former is oxidized when exposed to air. But both sulfite and arsenite are oxidized when mixed and exposed to air. Thus he stated (1858) that the oxidation of sulfite “induces” that of arsenite.
From 1836 on, Schönbein’s publications on voltaic current attributed the origin of this form of electricity to chemical action. His 1838 tendency theory stated that the tendency of two substances to combine with each other is sufficient to disturb their chemical equilibrium and to produce an electric current.
At the 11 March 1846 meeting of the Naturforschende Gesellschaft in Basel, Schönbein announced his discovery of guncotton. He also discovered collodion, a solution of guncotton in ether, which early found applications in medicine and photography. Schönbein produced guncotton by dipping cotton-wool in a mixture of fuming nitric and sulfuric acids and then washing and drying the product. His method of preparation remained a secret until it was discovered independently in 1846 by Böttger and Friedrich Julius Otto. Schönbein was also interested in the rise of dissolved materials from filter paper. His technique of capillary chromatography was based on the specific low rate of individual substances in nonimpregnated slips of paper. The height of ascent under standardized conditions and the time required for the ascent were recognized as characteristics of each individual substance present in the mixture under investigation. Schönbein’s pupil Friedrich Goppelsroeder greatly extended the knowledge of the technique of capillary analysis.
Schönbein’s general ideas on chemistry, and particularly on the phenomenon of catalysis, are discussed in Beiträge zur physikalischen Chemie (1844). His dynamical ideas are also emphasized. Schönbein was opposed to the atomic theory: he rejected the explanation of chemical combination as the basis for the formation of chemical substances. He thought that the qualitative changes in the formation of chemical substances indicated that every particle of a chemical element is a system of continuously working molecular forces. Schönbein sent a copy of his Beiträge to Faraday; and in a covering letter he pointed out that for years he had doubted the validity of the atomic theory and that he considered the molecule of a compound to be the “centre of physical forces.”
Although Schelling’s influence is clearly evident in the work of Schönbein, he was not strictly a Naturphilosoph. More than once he expressed himself against the views of Schelling and Oken and he passionately denounced Hegel and his school. Nevertheless, Schönbein’s work is filled with speculative remarks lacking an adequate experimental basis and with excessive recourse to analogy.
I. Original Works. Schönbein’s works include “Ueber das Verhalten des Zinns und des Eisens gegen Salpetersäure,” in Annalen der Physik und Chemie. 2nd ser., 37 (1836), 390–399; “Ueber das Verhalten des Eisens zum Sauerstoff,” ibid., 38 (1836), 492–497; Das Verhalten des Eisens zum Sauerstoff. Ein Beitrag zur Erweiterung electro-chemischer Kenntnisse (Basel, 1837); “Further Experiments on the Current Electricity Excited by Chemical Tendencies, Independent of Ordinary Chemical Action,” in London and Edinburgh Philosophical Magazine and Journal of Science, 12 (1838), 311–317; “Beobachtungen über das electromotorische Verhalten einiger Metallhyperoxyde des Platins und des Eisens,” in Annalen der Physik und Chemie, 2nd ser., 43 (1838), 89–102; “Notiz über die Passivität des Eisens,” ibid., 103–104; and “Beobachtungen über den bei der Electrolyse des Wassers und dem Ausströmen der gewöhnlichen Electricität sich entwickelnden Geruch,” ibid., 50 (1840), 616–635.
Later writings are Ueber die Häufigkeit der Berührungswirkungen auf dem Gebiete der Chemie (Basel, 1843); Beiträge zur physikalischen Chemie (Basel, 1844); Ueber die Erzeugung des Ozons auf chemischen Wege (Basel, 1844); “On the Nature of Ozone,” in London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 27 (1845), 386–389; “Einige Bemerkungen über die Anwesenheit des Ozons in der atmosphärischen Luft und die Rolle, welche es bei langsamen Oxidationen spielen dürfte,” in Annalen der Physik und Chemie, 3rd ser., 65 (1845), 161–172; Chemische Beobachtungen über die langsame und rasche Verbrennung der Körper in atmosphärischer Luft (Basel, 1845); Denkschrift über das Ozon (Basel, 1849); Ueber den Einfluss des Sonnenlichtes auf die chemische Thätigkeit des Sauerstoffs und den Ursprüng der Wolken-electricität und des Gewitters (Basel, 1850); and Ueber den Zusammenhang der katalytischen Erscheinungen mit der Allotropie (Basel, 1856).
Schönbein’ letters are collected in Letters of Faraday and Schönbein, 1836–1862, G. W. A. Kahlbaum and F. V. Darbishire, eds. (Basel—London, 1899); Letters of Jöns Jacob Berzelius and Christian Friedrich Schönbein, 1836–1847, G. W. A. Kahlbaum, ed., trans. by F. V. Darbishire and N. V. Sidgwick (London, 1900); and Justus von Liebig und Christian Friedrich Schönbein. Briefwechsel 1853–1868, G. W. A. Kahlbaum and E. Thon, eds. (Leipzig, 1900).
II. Secondary Literature. The best study of the life and work of Schönbein is G. W. A. Kahlbaum and E. Schaer, Christian Friedrich Schöbein, 1799–1868, Ein Blatt zur Geschichte des 19. Jahrhunderts, 2 vols. (Leipzig, 1899–1901). See also E. Färber, “Christian Friedrich Schönbeins Werk,” in Prometheus, 29 (1918), 413–416; E. Hagenbach, Christian Friedrich Schönbein (Basel, 1868); R. E.Oesper, “Christian Friedrich Schönbein,” in Journal of Chemical Education, 6 (1929), 432–440, 677–685; and the chap. on Schönbein in W. Prandtl, Deutsche Chemiker in der ersten Hälfte des neunzehnten Jahrhunderts (Weinheim, 1956), 193–241.
H. A. M. Snelders
"Schönbein, Christian Friedrich." Complete Dictionary of Scientific Biography. . Encyclopedia.com. (March 28, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/schonbein-christian-friedrich
"Schönbein, Christian Friedrich." Complete Dictionary of Scientific Biography. . Retrieved March 28, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/schonbein-christian-friedrich
Schönbein, Christian Friedrich
Christian Friedrich Schönbein (krĬs´tyän frē´drĬkh shön´bīn), 1799–1868, German chemist. From 1828 he taught at the Univ. of Basel (as professor from 1835). He discovered ozone (1840) and, through his work on nitrocellulose, developed guncotton and collodion.
"Schönbein, Christian Friedrich." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (March 28, 2017). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/schonbein-christian-friedrich
"Schönbein, Christian Friedrich." The Columbia Encyclopedia, 6th ed.. . Retrieved March 28, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/schonbein-christian-friedrich