Link, Heinrich Friedrich

(b. Hitdesheim, Germany, 2 February 1767;d. Berlin, Germany, 1 January 1851),

zoology, botany, chemistry, geology, physics.

Link studied medicine and natural sciences at the University of Göttingen, from which he received the M.D. in 1789 with a dissertation entitled Florae Göttingensis specimen, sistens vegetabilia saxo calcareo propria (published in Usteri’s Delectus opusculorum botanicorum, I [1790], 299-336). In 1792 he was appointed full professor of zoology, botany, and chemistry at the University of Rostock; in 1811, of chemistry and botany at the University of Breslau; and in 1815, of botany at the University of Berlin. In Berlin he was also director of the university’s botanic garden.

Link published a great many articles on topics in botany, zoology, geology, and chemistry. His primary interest was in chemistry and physics, and he conducted experiments on adhesion, solution, crystallization, and double salts and acid salts. In his dissertation Link declared himself an adherent of Lavoisier’s oxidation theory; he published a critical discussion on phlogiston, “Bemerkungen über das Phlogiston” (1790), as well as papers on the general concept of chemical affinity (1791) and Berthollet’s theory of chemical equilibrium (1807). In 1814 Link published an article on the action of sulfuric acid on vegetable material, and in 1815 one on chemical reactions of solids produced by trituration. In 1806 he wrote a textbook on antiphlogistic chemistry: Die Grundwahrheiten der neuern Chemie.

Link also published on botany and geology. In 1797-1799 he traveled with Count J. C von Hoffmannsegg through Portugal, where he studied the flora as well as the geology, agriculture, and industry. In his Versuch einer Anleitung zur geologischen Kenntniss der Mineralien (1790), Link declared himself an adherent of neither the neptunist nor the plutonic geological school; rather, he defended the general view that inorganic nature can produce the same materials by different means. In botany, Link published on morphology, classification, anatomy, and physiology of plants; and in zoology, a work on mollusks (1806) which was used by Lamarck. His last zoological publication (1830) dealt with zoophytes.

Link was always deeply interested in the philosophical foundations of the natural sciences. Throughout his life he followed critically the various philosophical currents in Germany. His philosophical thought formed no complete system, and he sought a position intermediate between the prevailing more or less speculative philosophies. In particular, Link was strongly influenced by Kant’s dynamical theories of matter; the influence of Schelling’s more speculative dynamical concepts was much less, and that of Hegel was negligible. Like the majority of the scientists of his day, Link was greatly interested in the idea of unity in all natural sciences, but he rejected emphatically the speculative Naturphilosophie of Schelling and his adherents.

In his first philosophical work, Ueber Naturphilosophie (1806), Link started from the concept that it is absolutely necessary for both physicists and chemists to study philosophy. He declared himself against a speculative natural-philosophical mode of thought but praised the dynamical theory of matter given by Kant, although he mentioned many objections against it. It remained the primary task of the natural scientist constantly to examine all natural phenomena. This critical and—to the then-ruling philosophical systems—negative attitude was undoubtedly the reason why Link’s views met with great approval among the opponents of Naturphilosophie but, on the other hand, could not convince its adherents. The same is true of Link’s other philosophical publications, of which Propyläen der Naturkunde (1836-1839) is the most important.

From his first publications, Link was averse to an atomic theory of matter. In 1798 he already accepted the infinite divisibility of matter. Like many of his contemporaries, however, in practice Link worked with little particles from which matter could be built up, since he found it possible to explain more phenomena in this way than with the dynamical construction. Link was also very interested in the problem of the nature (Wesen) of the liquid and solid states. He took the liquid state as the original form of matter and tried to derive the solid state from it. Many mineralogists, most notably J. J. Bernhardi’ and J. J. Prechtl, accepted Link’s theory as a starting point for a theory of crystallization. Link applied his ideas to the explanation of such phenomena as solution formation of crystals, chemical reactions, flexibility, and elasticity.

BIBLIOGRAPHY

Link’s most important philosophical works are Ueher Naturphilosophie (Leipzig-Rostock, 1806); Ideen zu einer philosophischen Naturkunde (Breslau, 1814); and Propyläen der Naturkunde, 2 vols. (Berlin, 1836-1839).

Among his other publications are Versuch einr Anteitung zur geohgischen Kenntniss der Mineralien (Göttingen, 1790); Beytrdge zur Physik rund Chemie,, 3 vols. (Rostock, 1795-1797); Beyträge zur Naturgeschichte, 2 vols. (Rostock-Leipzig, 1797-1801); Grundriss der Physik (Hamburg, 1798); Die Grundwahrheiten der neuern Chemie, nach Fourcroy’s Philosophie chimique herausgegeben, mit vielen Zusätzen (Leipzig-Rostock, 1806); Grundlehren der Ana-tomie und Physiologie der Pflanzen (Göttingen, 1807); Flore portugaise ou Description de toutes les plames, qui croissent naturellement en Portugal, 2 vols. (Berlin, 1809-1820), written with J. C. von Hoffmannsegg; Elementa philosophiae botanicae (Berlin, 1824); Handhuch der physi-kalisehen Erdbeschreibung, 2 vols. (Berlin, 1826-1830); and Ueber die Bildung der festen Körper (Berlin, 1841).

On Link, see C. F. P. von Martius, Denkrede auf Heinrich Friedrich Link (Munich, 1851).

H. A. M. Snelders