Hans Heinrich Landolt (5 December 1831 – 15 March 1910) was a Swiss chemist who discovered

iodine clock reaction The iodine clock reaction is a classical chemical clock demonstration experiment to display chemical kinetics in action; it was discovered by Hans Heinrich Landolt in 1886. The iodine clock reaction exists in several variations, which each invol ...

. He is also one of the founders of

Landolt–Börnstein Landolt–Börnstein is a collection of property data in materials science and the closely related fields of chemistry, physics and engineering published by Springer Nature. History On July 28, 1882, Dr. Hans Heinrich Landolt and Dr. Richard B� ...

database. He tested law of mass conservation which was given by Lavoisier.

Biography

Landolt was born in Zurich and at the age of nineteen entered the university there to study chemistry and physics. He attended the lectures of

Carl Jacob Löwig Carl Jacob Löwig (17 March 1803 – 27 March 1890) was a German chemist and discovered bromine independently of Antoine Jérôme Balard. He received his PhD at the University of Heidelberg for his work with Leopold Gmelin. During his research o ...

and published his first work on stibmethyl in ''Schriften der Naturforschenden Gesellschaft'' (Writings of the Natural Science Society). He was then appointed assistant to Lowig and followed him in 1853 to Breslau. The same year he obtained the degree of Doctor of Philosophy with a thesis "Ueber die Arsenäthyle" (On ethyl compounds of arsenic) which was a notable contribution to the law of chemical valence. After the defense, he went to Berlin to attend lectures of

Eilhard Mitscherlich Eilhard Mitscherlich (; 7 January 179428 August 1863) was a German chemist, who is perhaps best remembered today for his discovery of the phenomenon of crystallographic isomorphism in 1819. Early life and work Mitscherlich was born at Neuende ...

, Rose, Johannes Muller and Dubois. Facilities for experimental research in chemistry were practically non-existent in Berlin at the time, and therefore Landolt left for Heidelberg for a newly founded institute of

Robert Bunsen Robert Wilhelm Eberhard Bunsen (; 30 March 1811 – 16 August 1899) was a German chemist. He investigated emission spectra of heated elements, and discovered caesium (in 1860) and rubidium (in 1861) with the physicist Gustav Kirchhoff. The Bu ...

. After devoting himself for a short time to the

electrolytic An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon di ...

production of calcium and lithium, Landolt started an investigation of the gases produced in the

Bunsen burner A Bunsen burner, named after Robert Bunsen, is a kind of ambient air gas burner used as laboratory equipment; it produces a single open gas flame, and is used for heating, sterilization, and combustion. The gas can be natural gas (which is ma ...

, which had been constructed in the winter of 1854–55. In 1856 Landolt returned to Breslau, where he was soon afterwards joined by

Lothar Meyer Julius Lothar Meyer (19 August 1830 – 11 April 1895) was a German chemist. He was one of the pioneers in developing the earliest versions of the periodic table of the chemical elements. Russian chemist Dmitri Mendeleev (his chief rival) and he ...

and

Friedrich Konrad Beilstein Friedrich Konrad Beilstein (russian: Фёдор Фёдорович Бейльштейн) (17 February 183818 October 1906), was a Russian chemist and founder of the famous ''Handbuch der organischen Chemie'' (''Handbook of Organic Chemistry''). T ...

. In the same year he became a lecturer in chemistry on the strength of his monograph on "Chemische Vorgange in der Flamme der Leuchtgase" (Chemical processes in the flame of illuminating gases). In 1857, he was called to Bonn where he studied the effect of the atomic composition of liquids containing carbon, hydrogen and oxygen on the transmission of light. The results were published in 1862–1864 and were a continuation of the previous researches of

John Hall Gladstone John Hall Gladstone FRS (7 March 1827 – 6 October 1902) was a British chemist.* He served as President of the Physical Society between 1874 and 1876 and during 1877–1879 was President of the Chemical Society. Apart from chemistry, where ...

. Later in his life he elaborated the work of Hertz (1887–1888) and demonstrated that light waves are differentiated from electric waves merely by the wavelength, and in 1892 he extended his early work to measurements of the molecular refractivity of organic substances for radiowaves. At Bonn, in 1859, Landolt married Milla Schallenberg, the daughter of Swiss parents settled in Bonn. In 1869, he was appointed to the head of the newly founded technical college at Aachen, where a chemical institute was built according to his plans. His work there was concerned with the relations between physical properties and chemical constitution. In particular, he made use of polarized light and studied optical rotation by various chemicals. In 1880, he was called by the Prussian Ministry of Agriculture to the newly founded Agricultural College in Berlin, where he remained until 1891. There he constructed new laboratories and collaborated with

Richard Börnstein Richard Börnstein (9 January 1852 – 13 May 1913) was a German physicist and meteorologist. Born into a Jewish family in Königsberg, he studied natural sciences at the University of Göttingen, and later on, worked as an assistant to Georg Herm ...

in the compilation of the "Physikalisch-chemischen Tabellen" (Physical-chemical Tables). Their third edition was published in 1905 with the assistance of

Wilhelm Meyerhoffer Wilhelm Meyerhoffer (13 September 1864 – 21 April 1906) was a German chemist. Meyerhoffer studied chemistry and worked with Jacobus Henricus van 't Hoff at the University of Amsterdam and the University of Berlin Humboldt-Universit� ...

and a generous financial support by the Berlin Academy of Sciences. In 1882 Landolt became a member of the Berlin Academy. Around that time he made highly remarkable investigations into the kinetics of the

between iodic acid and sulfurous acid.See: * * From 1891 till his retirement in 1905, he served as director of the second chemical institute of the Berlin University. There he worked on three major problems: (i) relation between the melting point and molecular weight, (ii) effect of crystallinity on the optical rotation and (iii) change in weight during chemical reactions. The negative result for the last experiments was regarded as an accurate experimental confirmation of the conservation laws of mass and energy. Landolt was known for his humor, friendliness, punctuality and cigar. He was fit and worked as usual until the week before his death, when he had a sudden failure of heart and kidney. He was buried, in accordance with his desire, at Bonn where he spent most memorable years of his life.

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External links

* {{DEFAULTSORT:Landolt, Hans Heinrich 1831 births 1910 deaths Swiss chemists Corresponding members of the Saint Petersburg Academy of Sciences Articles containing video clips

Biography

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Further reading

External links