Cornelis Zwikker (19 August 1900 – 20 April 1985) was a Dutch

scientist A scientist is a person who conducts scientific research to advance knowledge in an area of the natural sciences. In classical antiquity, there was no real ancient analog of a modern scientist. Instead, philosophers engaged in the philosophica ...

.Biography by H. K. Nagtegaal.
(in Dutch) Zwikker was born in

Zaandam Zaandam () is a city in the province of North Holland, Netherlands. It is the main city of the municipality of Zaanstad, and received city rights in 1811. It is located on the river Zaan, just north of Amsterdam. The statistical district Zaa ...

as the son of Klaartje Dil and the shopkeeper Klaas Cornelisz Zwikker. He married Johanna Dorothea Theinert (*1901, Zaandam) in 1924 in Zaandam. In 1918 he had started studying chemistry and later physics at the

University of Amsterdam The University of Amsterdam (abbreviated as UvA, nl, Universiteit van Amsterdam) is a public research university located in Amsterdam, Netherlands. The UvA is one of two large, publicly funded research universities in the city, the other bein ...

, where in 1925 he obtained his PhD with the thesis "Physical properties of wolfram at high temperatures" under supervision of the Noble-laureate Pieter Zeeman. From 1923 he worked as scientific researcher at

Philips Koninklijke Philips N.V. (), commonly shortened to Philips, is a Dutch multinational conglomerate corporation that was founded in Eindhoven in 1891. Since 1997, it has been mostly headquartered in Amsterdam, though the Benelux headquarters is ...

Eindhoven Eindhoven () is a city and municipality in the Netherlands, located in the southern province of North Brabant of which it is its largest. With a population of 238,326 on 1 January 2022,Delft University of Technology Delft University of Technology ( nl, Technische Universiteit Delft), also known as TU Delft, is the oldest and largest Dutch public technical university, located in Delft, Netherlands. As of 2022 it is ranked by QS World University Rankings among ...

. He was involved in the acoustic design of sound studios and presided over multiple physics-related organizations. In 1945 he requested retirement from his professoriate in Delft and became technical director of the "light" section at

. Director of the National Aeronautical Research Institute (NLL) from 1 November 1952 to 1 November 1956. In addition he advised for many years NLL and NLR as member of the Scientific Committee, from 1968 till 1972 as chairman. Between 1956 and 1970 he again was professor of physics, now at the

Eindhoven University of Technology The Eindhoven University of Technology ( nl, Technische Universiteit Eindhoven), abbr. TU/e, is a public technical university in the Netherlands, located in the city of Eindhoven. In 2020–21, around 14,000 students were enrolled in its BSc ...

. He lived in Eindhoven until the death of his wife in March 1984 and died in Zwijndrecht in 1985. Zwikker's contributions are mostly in

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which rel ...

and chemistry. In chemistry, he introduced the

Zwikker test The Zwikker reagent is used as a simple spot-test to presumptively identify barbiturates. It is composed of a mixture of two solutions. Part A is 0.5 g of copper (II) sulfate in 100 ml of distilled water. Part B consists of 5% pyridine (v/v) in chlo ...

. In physics, he is known for his contributions to acoustics. Zwikker is the author of the classic geometry textbook, ''The Advanced Geometry of Plane Curves and Their Applications'', designed to teach the applications of

complex number In mathematics, a complex number is an element of a number system that extends the real numbers with a specific element denoted , called the imaginary unit and satisfying the equation i^= -1; every complex number can be expressed in the for ...

s to the study of

curve In mathematics, a curve (also called a curved line in older texts) is an object similar to a line, but that does not have to be straight. Intuitively, a curve may be thought of as the trace left by a moving point. This is the definition that ...

s and to the resolution of problems in geometry and engineering.

Books

Zwikker wrote many books; the best known are the following: * ''Sound Absorbing Materials'' (1949, with C. W. Kosten,

Elsevier Elsevier () is a Dutch academic publishing company specializing in scientific, technical, and medical content. Its products include journals such as '' The Lancet'', '' Cell'', the ScienceDirect collection of electronic journals, '' Trends'', ...

Publishing Co.) * ''The Advanced Geometry of Plane Curves and Their Applications'' (1963,

Dover Publications Dover Publications, also known as Dover Books, is an American book publisher founded in 1941 by Hayward and Blanche Cirker. It primarily reissues books that are out of print from their original publishers. These are often, but not always, books ...

); originally published as ''Advanced Plane Geometry'' (1950, North-Holland Publishing Co.)

Books

References

Further reading