Hans Peter Jørgen Julius Thomsen (16 February 1826 – 13 February 1909) was a Danish

chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a graduated scientist trained in the study of chemistry, or an officially enrolled student in the field. Chemists study the composition of ...

noted in

thermochemistry Thermochemistry is the study of the heat energy which is associated with chemical reactions and/or phase changes such as melting and boiling. A reaction may release or absorb energy, and a phase change may do the same. Thermochemistry focuses on ...

for the

Thomsen–Berthelot principle In thermochemistry, the Thomsen–Berthelot principle is a hypothesis in the history of chemistry which argued that all chemical changes are accompanied by the production of heat and that processes which occur will be ones in which the most heat is ...

Life and work

Thomsen was born in

Copenhagen Copenhagen ( ) is the capital and most populous city of Denmark, with a population of 1.4 million in the Urban area of Copenhagen, urban area. The city is situated on the islands of Zealand and Amager, separated from Malmö, Sweden, by the ...

, where he spent his life. From 1847 to 1856 he taught

chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules a ...

at the

Polytechnic A polytechnic is an educational institution that primarily focuses on vocational education, applied sciences, and career pathways. They are sometimes referred to as ''institutes of technology'', ''vocational institutes'', or ''universities of app ...

, where from 1883 to 1892 he was the director. From 1856 to 1866 he was on the staff of the military high school. In 1866 he was appointed

professor Professor (commonly abbreviated as Prof.) is an Academy, academic rank at university, universities and other tertiary education, post-secondary education and research institutions in most countries. Literally, ''professor'' derives from Latin ...

of chemistry at the

university A university () is an educational institution, institution of tertiary education and research which awards academic degrees in several Discipline (academia), academic disciplines. ''University'' is derived from the Latin phrase , which roughly ...

, and retained that chair until his retirement from active work in 1891. A friend and colleague of Ludwig A. Colding, who was one of the early advocates of the principle of

conservation of energy The law of conservation of energy states that the total energy of an isolated system remains constant; it is said to be Conservation law, ''conserved'' over time. In the case of a Closed system#In thermodynamics, closed system, the principle s ...

, Thomsen did much to found the field of

. In particular, between 1869 and 1882, he carried out a great number of determinations of the heat evolved or absorbed in chemical reactions, such as the formation of salts, oxidation and reduction, and the combustion of organic compounds. His collected results were published from 1882 to 1886 in four volumes under the title , and also a resume in English under the title "Thermochemistry" in 1908. In 1857 he established in Copenhagen a process for manufacturing soda from

cryolite Cryolite ( Na3 Al F6, sodium hexafluoroaluminate) is a rare mineral identified with the once-large deposit at Ivittuut on the west coast of Greenland, mined commercially until 1987. It is used in the reduction ("smelting") of aluminium, in pest ...

, obtained from the west coast of

Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...

. Although his efforts at determining the structure of

benzene Benzene is an Organic compound, organic chemical compound with the Chemical formula#Molecular formula, molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal Ring (chemistry), ring with one hyd ...

were unsuccessful, the Thomsen graph

K_

in mathematical

graph theory In mathematics and computer science, graph theory is the study of ''graph (discrete mathematics), graphs'', which are mathematical structures used to model pairwise relations between objects. A graph in this context is made up of ''Vertex (graph ...

is named after him, from an 1886 paper in which he proposed a benzene structure based on this graph. Thomsen was elected a member of the

Royal Swedish Academy of Sciences The Royal Swedish Academy of Sciences () is one of the Swedish Royal Academies, royal academies of Sweden. Founded on 2 June 1739, it is an independent, non-governmental scientific organization that takes special responsibility for promoting nat ...

in 1880, and a Foreign Honorary Member of the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (The Academy) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, and other ...

in 1884. He was awarded the

Royal Society The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...

Davy Medal The Davy Medal is awarded by the Royal Society of London "for an outstandingly important recent discovery in any branch of chemistry". Named after Humphry Davy, the medal is awarded with a monetary gift, initially of £1000 (currently £2000). Re ...

in 1883. Thomsen served on the

Copenhagen City Council The Copenhagen City Council (Danish: ) is the municipal government of Copenhagen, Denmark, and has its seat at Copenhagen City Hall. The city council is Copenhagen's highest political authority and sets the framework for the committees' tasks. ...

from 1861 to 1894, to which he lent his expertise in a number of areas during the city's development. Katherine Alice Burke translated his book on systematic research in

into English. This translation appeared in print in 1905.

Family

His brother, Carl August Thomsen (1834–1894), was lecturer on technical chemistry at the Copenhagen Polytechnic, and a second brother, Thomas Gottfried Thomsen (1841–1901), was assistant in the chemical laboratory at the university until 1884, when he abandoned science for theology, subsequently becoming minister at Norup and Randers.

References

External links

Statue and picture of Thomsen
{{DEFAULTSORT:Thomsen, Hans 1826 births 1909 deaths Danish chemists 18th-century Danish scientists 19th-century Copenhagen City Council members Scientists from Copenhagen Fellows of the American Academy of Arts and Sciences Members of the Royal Swedish Academy of Sciences Foreign members of the Royal Society Rectors of the University of Copenhagen Members of the Royal Society of Sciences in Uppsala

Life and work

Family

See also

References

Further reading

External links