Johann Wilhelm Hittorf

Johann Wilhelm Hittorf ( born March 27, 1824 in Bonn, † November 28, 1914 in Münster ) was a German physicist and chemist.

Life

After visiting the old school in Bonngasse he studied from 1842 Natural Sciences and Mathematics at the University of Bonn, in between a semester in Berlin. 1846 Hittorf the area conics was in Bonn " deductae Proprietales sectionum conicarum ex aequatione polarized " with Julius Plücker with the discussion of a doctorate. Hittorf was the Prussian minister of education for the orphaned since 1840 chair of physics and chemistry at the University of Münster - then in the meantime Royal Academy of Münster in Westphalia - have been proposed. After his habilitation with an experimental work on the electrical production of oxides of the noble in August 1847 his appointment by the Faculty of Arts was the autumn of 1847 nothing in the way. After the rejection of the call to the professor of physics to Bern Hittorf in 1856 full professor. In 1879 he brought the reorganization of the Academy, which is his work for the most part, the desired relief by creating a special professorship of chemistry, while Hittorf could limit his teaching to physics. The College, which served his life's work owes him much. Through him she became famous.

In the winter semester 1888/89 Friedrich Paschen Hittorfs was an assistant. One of the first led Hittorf 1850/51 practical exercises one. With the explorer Heinrich Barth Hittorf was a friend.

Services

Hittorf employed in Münster initially the elucidation of the electrical conductivity. Research on the physico-chemical behavior of certain sulphides ( He spach in this important treatise of sulphide of silver and semi- sulfur copper. ) Hittorf led to the important finding that these sulfides are derived not metallic, but electrolytically. At the same time he first introduced the term "metallic" in science, and thus clarified Faraday's way of speaking of the " actual line ". The knowledge thus gained enabled Hittorf to observe the shift of the chemical equilibrium between Cu2S and CuS, which opened a remarkable access to the exploration of these fundamental laws in chemistry 16 years ago Guldberg and Waages law of mass action. Studies on the conductivity behavior enabled Hittorf also essential to elucidate the phenomenon allotropy of the chemical elements through research on phosphorus and especially selenium. He realized that the change of the modification amorphous - crystalline exactly same way as with the already known changes in physical appearance, in particular at a defined transition temperature and with certain heat tint.

Between 1853 and 1859 Hittorf researched groundbreaking on the mobility of ions in electrolysis. He had established concentration gradient at the electrode and pointed it through different rapid movement of various ions. He could assign them so-called characteristic transport factors, which now bears his name Hittorf transference numbers by measurement. The work initially met the opposition of important scientists. They appeared in the series Ostwald classic.

Hittorf explored together with Plücker in gas discharge tubes - as an alternative or replacement necessary to the flame spectrum - the spectra of many chemical elements. It was found that allotropic modifications may produce different spectra.

Plücker and Hittorf even mention the importance of Geissler effective mercury vacuum pump and Rühmkorffs Hochspannungsinduktor in the work.

The advances in experimental technique enabled the Hittorf beyond Faraday researching electrical conduction phenomena in highly rarefied gases. He led them in gas discharge tubes of different shapes, some with potential probes, and developed the Hittorfröhre.

Hittorf observed 1868/69, the shading of the fluorescence on the glass wall by physical obstructions and thus discovered the cathode rays and their rectilinear propagation in absence of magnetic field. Thus, he created the basis for the development of X-ray tube and cathode ray tube. Hittorf himself said in 1869 "by the straight lines or the rays of the glow ". The characteristic change of the shadow cast by a magnetic field introduced Hittorf for comparison with a physical electrical conductor.

Hittorfs gas discharge works were " completely ignored " remained, William Crookes said even ten years later, to describe the observed phenomena of Hittorf first time. Eugene Goldstein coined in 1876 the term cathode rays; with this electron by JJ Thomson ( 1897) experimented Philipp Lenard around 1894 for the first time outside the Hittorfröhre.

Honors

Hittorf was a member of learned societies at home and abroad and honorary member of the London Physical Society. The Order Pour le Mérite for Sciences and Arts since 1897 and the Bavarian Maximilian Order for Science and Art counted him among their members. Hittorf is an honorary doctor of medicine and science, and he was one of the first of two technical universities honorary doctorate in engineering. appointed. 1914 awarded him the city of Münster ( Westphalia ) the honorary citizenship.

After Johann Wilhelm Hittorf the Wilhelm -Gymnasium Hittorf were in Münster ( Westphalia ) and the Hittorf school in Recklinghausen and the Johann- Hittorf -Str. in Berlin- Adlershof and the Hittorf -Str. named in Berlin- Dahlem.

Writings

• JW Hittorf and J. Plücker: On the spectra of ignited gases and Vapours with especial regard to the same elementary Gaseous substance. Phil Trans Royal Soc. ( London) 155, 1 (1865 ) (full text).