Hans Heinrich Landolt
Encyclopedia
Hans Heinrich Landolt was the Swiss chemist who discovered iodine clock reaction
. He is also one of the founders of Landolt-Börnstein
database.
and published his first work on stibmethyl in Schriften der Naturforschenden Gesellschaft. 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 Arsenathyle” which was an notable contribution to the law of chemical valence. After the defense, he went to Berlin to attend lectures of Eilhard Mitscherlich
, 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
. After devoting himself for a short time to the electrolytic
production of calcium and lithium, Landolt started an investigation of the gases produced in the Bunsen burner
, 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 and Friedrich Konrad Beilstein
. In the same year he became a lecturer in chemistry on the strength of his monograph on "Chemische Vorgange in der Flamme der Leuchtgase". 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
. 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 in the compilation of the "Physikalisch-chemischen Tabellen”. Their third edition was published in 1905 with the assistance of Wilhelm Meyerhoffer
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 iodine clock reaction
between iodic acid and sulfurous acid
. 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 well 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.
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. Two colorless solutions are mixed and at first there is no visible reaction...
. He is also one of the founders of Landolt-Börnstein
Landolt-Börnstein
Landolt–Börnstein is a systematic and extensive data collection in all areas of physical sciences and engineering published by Springer Science+Business Media. Originally, the project started with the first work published in 1883 by the physicist Hans Heinrich Landolt and the chemist Richard...
database.
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 LöwigCarl Jacob Löwig
Carl Jacob Löwig 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....
and published his first work on stibmethyl in Schriften der Naturforschenden Gesellschaft. 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 Arsenathyle” which was an notable contribution to the law of chemical valence. After the defense, he went to Berlin to attend lectures of Eilhard Mitscherlich
Eilhard Mitscherlich
Eilhard Mitscherlich was a German chemist, who is perhaps best remembered today for his law of isomorphism , which states that compounds crystallizing together probably have similar structures and compositions...
, 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 Bunsen
Robert Wilhelm Eberhard Bunsen was a German chemist. He investigated emission spectra of heated elements, and discovered caesium and rubidium with Gustav Kirchhoff. Bunsen developed several gas-analytical methods, was a pioneer in photochemistry, and did early work in the field of organoarsenic...
. After devoting himself for a short time to the electrolytic
Electrolysis
In chemistry and manufacturing, electrolysis is a method of using a direct electric current to drive an otherwise non-spontaneous chemical reaction...
production of calcium and lithium, Landolt started an investigation of the gases produced in the Bunsen burner
Bunsen burner
A Bunsen burner, named after Robert Bunsen, is a common piece of laboratory equipment that produces a single open gas flame, which is used for heating, sterilization, and combustion.- Operation:...
, 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 and Friedrich Konrad Beilstein
Friedrich Konrad Beilstein
Friedrich Konrad Beilstein , Russian name "Бейльштейн, Фёдор Фёдорович", was a chemist and founder of the famous Handbuch der organischen Chemie . The first edition of this work, published in 1881, covered 1,500 compounds in 2,200 pages...
. In the same year he became a lecturer in chemistry on the strength of his monograph on "Chemische Vorgange in der Flamme der Leuchtgase". 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
John Hall Gladstone FRS 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...
. 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
Aachen
Aachen has historically been a spa town in North Rhine-Westphalia, Germany. Aachen was a favoured residence of Charlemagne, and the place of coronation of the Kings of Germany. Geographically, Aachen is the westernmost town of Germany, located along its borders with Belgium and the Netherlands, ...
, 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
Optical rotation
Optical rotation is the turning of the plane of linearly polarized light about the direction of motion as the light travels through certain materials. It occurs in solutions of chiral molecules such as sucrose , solids with rotated crystal planes such as quartz, and spin-polarized gases of atoms...
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 in the compilation of the "Physikalisch-chemischen Tabellen”. Their third edition was published in 1905 with the assistance of Wilhelm Meyerhoffer
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 theUniversity of Berlin....
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 iodine clock reaction
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. Two colorless solutions are mixed and at first there is no visible reaction...
between iodic acid and sulfurous acid
Sulfurous acid
Sulfurous acid is the chemical compound with the formula H2SO3. There is no evidence that sulfurous acid exists in solution, but the molecule has been detected in the gas phase...
. 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 well 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.