Johann Wilhelm Hittorf
Encyclopedia
Johann Wilhelm Hittorf was a German physicist
who was born in Bonn
and died in Münster
, Germany.
Hittorf was the first to compute the electricity-carrying capacity of charged atoms and molecules (ion
s), an important factor in understanding electrochemical reactions. He formulated ion transport number
s and the first method for their measurements
He observed tubes
with energy rays extending from a negative electrode
. These rays produced a fluorescence when they hit the glass walls of the tubes. In 1876 the effect was named "cathode ray
s" by Eugen Goldstein
.
Hittorf's early investigations were on the allotropes of phosphorus
and selenium
. Between 1853 and 1859 his most important work was on ion movement caused by electric current. In 1853 Hittorf pointed out that some ions traveled more rapidly than others. This observation led to the concept of transport number, the fraction of the electric current carried by each ionic species. He measured the changes in the concentration of electrolyzed solutions, computed from these the transport numbers (relative carrying capacities) of many ions, and, in 1869, published his laws governing the migration of ions.
He became professor of physics and chemistry at the University of Münster
and director of laboratories there from 1879 until 1889. He also investigated the light spectra of gases and vapours, worked on the passage of electricity through gases, and discovered new properties of cathode rays (electron rays). In 1869 he ascertained that the cathode rays glowed different colours because of different gasses and pressures. He noticed that when there was any object placed between the cathode and the illuminating side of the tube, then the shadow of that object appeared.
His work led toward development of X-ray
s and cathode ray tube
s. The measurement of current in a vacuum tube was an important step towards the creation of a vacuum tube diode
.
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
who was born in Bonn
Bonn
Bonn is the 19th largest city in Germany. Located in the Cologne/Bonn Region, about 25 kilometres south of Cologne on the river Rhine in the State of North Rhine-Westphalia, it was the capital of West Germany from 1949 to 1990 and the official seat of government of united Germany from 1990 to 1999....
and died in Münster
Münster
Münster is an independent city in North Rhine-Westphalia, Germany. It is located in the northern part of the state and is considered to be the cultural centre of the Westphalia region. It is also capital of the local government region Münsterland...
, Germany.
Hittorf was the first to compute the electricity-carrying capacity of charged atoms and molecules (ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
s), an important factor in understanding electrochemical reactions. He formulated ion transport number
Ion transport number
Ion transport number is a quantity which indicates the different contribution of ions to the electric current in electrolytes due to different electrical mobility. It has been introduced by Johann Wilhelm Hittorf in 1853....
s and the first method for their measurements
He observed tubes
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...
with energy rays extending from a negative electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...
. These rays produced a fluorescence when they hit the glass walls of the tubes. In 1876 the effect was named "cathode ray
Cathode ray
Cathode rays are streams of electrons observed in vacuum tubes. If an evacuated glass tube is equipped with two electrodes and a voltage is applied, the glass opposite of the negative electrode is observed to glow, due to electrons emitted from and travelling perpendicular to the cathode Cathode...
s" by Eugen Goldstein
Eugen Goldstein
Eugen Goldstein was a German physicist. He was an early investigator of discharge tubes, the discoverer of anode rays, and is sometimes credited with the discovery of the proton.- Life :...
.
Hittorf's early investigations were on the allotropes of phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
and selenium
Selenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...
. Between 1853 and 1859 his most important work was on ion movement caused by electric current. In 1853 Hittorf pointed out that some ions traveled more rapidly than others. This observation led to the concept of transport number, the fraction of the electric current carried by each ionic species. He measured the changes in the concentration of electrolyzed solutions, computed from these the transport numbers (relative carrying capacities) of many ions, and, in 1869, published his laws governing the migration of ions.
He became professor of physics and chemistry at the University of Münster
University of Münster
The University of Münster is a public university located in the city of Münster, North Rhine-Westphalia in Germany. The WWU is part of the Deutsche Forschungsgemeinschaft, a society of Germany's leading research universities...
and director of laboratories there from 1879 until 1889. He also investigated the light spectra of gases and vapours, worked on the passage of electricity through gases, and discovered new properties of cathode rays (electron rays). In 1869 he ascertained that the cathode rays glowed different colours because of different gasses and pressures. He noticed that when there was any object placed between the cathode and the illuminating side of the tube, then the shadow of that object appeared.
His work led toward development of X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
s and cathode ray tube
Cathode ray tube
The cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and...
s. The measurement of current in a vacuum tube was an important step towards the creation of a vacuum tube diode
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...
.