ROOZEBOOM, HENDRIK WILLEM BAKHUIS

(b. Alkmaar, Netherlands, 24 October 1854; d. Amsterdam, Netherlands, 8 February 1907)

physical chemistry.

After completing high school in Alkmaar (1872), Roozeboom worked in a laboratory that did research on the composition of foods and water. In 1878 lie became assistant to J. M. van Bemmelen, professor of chemistry at the University of Leiden, where he continued his studies in chemistry (1878–1882). Roozeboom received a doctorate in 1884 with a dissertation on the hydrates of sulfur dioxide, chlorine, bromine, and hydrogen chloride; in it he studied the relationship among the three states of matter (solid, liquid, gas) at different temperatures and pressures. In 1886 van der Waals brought to Roozeboom’s attention J. W. Gibbs’s phase rule (1876), which defines the conditions of equilibrium as a relationship between the number of components of a system C and the number of coexisting phases P, according to the equation

F = C + 2 − P,

where F is the degrees of freedom or variability of the system. This rule gave Roozeboom the theoretical guide to his investigations on heterogeneous equilibriums, which lie began to study in 1882. He became the founder of the scientific doctrine of heterogeneous equilibriums, important not only in theoretical chemistry but also for its practical applications in metallurgy and geology.

After receiving the doctorate, Roozeboom remained at Leiden as assistant to van Bemmelen. From 1881 to 1896 lie also taught at a girls’ high school in Leiden, and in 1890 lie was appointed university lecturer in physical chemistry. In 1896 Roozeboom succeeded van’t Hoff as professor of general chemistry at the University of Amsterdam, where lie remained for the rest of his life. In 1880 lie became a member of the Koninklijke Nederlandse Akademie van Wetenschappen. Besides his scientific work, Roozeboom was very interested in social problems; in 1895 he was one of the founders of the Christelijke Vereniging van Natuuren Geneeskundigen in Nederland.

Roozeboom’s importance in science stems from his application of the then little-known phase rule to the study of heterogeneous equilibriums. In his first important publication, “Sur les différentes formes de I’équilibre chimique hétérogène” (1887), he systematically arranged all the known dissociation equilibriums on the basis of the phase rule according to the number of components and the number and nature of the phases. In many publications Roozeboom used two-and three-dimensional figures to illustrate his theory. He always studied simple, generally applicable systems, such as calcium chloride-water and ferric chloride-water, which provide an almost complete illustration of the theory of salt hydrates (1889). With his pupil F. A. H. Schreinemakers, Roozeboom investigated the ternary system hydrogen chloride-ferric chloride-water (1894). Alone he studied astrakanite (Na₂SO₄ · MgSO₄ · 4H₂O) as an example of a double salt in a four-phase system (three solid and one gas).

In Amsterdam, Roozeboom made especially systematic studies of heterogeneous equilibriums. He gave much attention to mixed crystals, which provided insight into the homogeneous solid phase. Roozeboom represented all phase equilibriums with pressure-temperature-concentration diagrams. He and his pupils gave pseudosystems (such as tautomeric compounds) a phase-theoretical treatment—for example, the system acetaldehyde-paraldehyde and the system sulfur-chlorine.

Roozeboom’s application of the concept of a homogeneous phase to mixed crystals, gas mixtures, and liquid mixtures, from which a general theoretical treatment of equilibriums became possible, was very important. From it he derived five types of fusion curves, which were experimentally confirmed by his pupils. Both fusion lines and transition phenomena were observed. Roozeboom’s work profoundly stimulated the systematic and comprehensive investigation of alloys through practical application of the phase rule to the study of alloys of cadmium and tin and binary and ternary alloys of tin, bismuth, cadmium, and lead. Systems of two optical antipodes and liquid mixed crystals were also studied. All these investigations confirmed Roozeboom’s theory, which was also applied to technical problems, such as the system iron-steel, and to metallurgical and experimental petrographical subjects.

In volume I of Die heterogenen Gleichgewichte vom Standpunkte der Phasenlehre (1901) one-component heterogeneous equilibrium systems were systematically treated. In volume II, part 1 (1904), Roozeboom treated two-component systems that contain only one liquid phase. After his death the work was completed by his pupils Schreinemakers, E. H. Bücheer, and A. H. W. Aten (1911–1918). W. D. Bancroft described Roozeboom as having done “far more than any one else to show the importance and significance of Gibbs’s Phase Rule” (The Phase Rule, p. iii).

BIBLIOGRAPHY

I. Original Works. A complete bibliography of Roozeboom’s publications is given by J. M. A. van Bemmelen, W. P. Jorissen, and W. E. Ringer in Berichte der Deutschen chemischen Gesellschaft, 40 (1907), 1570-1574.

Among his works are “Recherches sur quelques hydrates de gaz,” in Recueil des travaux chimique des Pays-Bas et de la Belgique, 3 (1884), 29–104, his dissertation; “Sur les conditions d’équilibre de deux corps dans les trois états, solide, liquide et gazeux, d’après M. v. d. Waals,” ibid., 5 (1886), 335–350; “Sur les différentes formes de l’équilibre chimique hétérogène,” ibid., 6 (1887), 262–303; “Sur l’astrakanite et les sels doubles hydratés en général,” ibid., 333–355; “Étude expérimentale et théorique sur les conditions de 1’équilibre entre les combinaisons solides et liquides de 1’eau avec des sels, particulièrement avec le chlorure de calcium,” ibid., 8 (1889), 1–146; Die Bedeutung der Phasenlehre (Leipzig, 1900); “Eisen und Stahl vom Standpunkte der Phasenlehre,” in Zeitschrift für physickalische Chemie, 34 (1900), 437–487, English trans. in Journal of the Iron and Steel Institute (1900), no. 2, 311-316; and Die heterogenen Gleichgewichte vom Standpunkte der Phasenlehre (Brunswick): I (1901); II , pt. 1 (1904); II , pt. 2, by E. H. Büchner (1918); II , pt. 3, by A. H. W. Aten (1918); III , pt. 1, by F. A. H. Schreinemakers (1911); III , pt. 2, by Schreinemakers (1913).

II. Secondary Literature. See J. M. van Bemmelen, in Chemisch weekblad, 4 (1907), 249–285; J. M. van Bemmelen, W. P. Jorissen, and W. E. Ringer, in Berichte der Deutschen chemischen Gesellschaft, 40 (1907), 1541-1574; A. F. Holleman, in Chemisch weekblad, 4 (1907), 119–132; R. Hooykaas, in Geloof en wetenschap, 53 (1955), 68–77; W. P. Jorissen and W. E. Ringer, H. W. Bakhuis Roozeboom, Mannen en, vrouwen van beteekenis in onze dagen, no. 37, sec. 4 (Haarlem, 1907), 155–218; and W. Stortenbeker, in Recueil des travaux chimiques des Pays-Bas et de la Belgique, 27 (1908), 1–51.

H. A. M. Snelders