Johan Gadolin | |
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 Postage stamp depicting Gadolin | |
| Born | (1760-06-05)5 June 1760 |
| Died | 15 August 1852(1852-08-15) (aged 92) Mynämäki,Grand Duchy of Finland, Russian Empire |
| Known for | Discoveringyttrium, Namesake ofgadolinium |
| Scientific career | |
| Fields | Chemistry |
Johan Gadolin (5 June 1760 – 15 August 1852)[1] was a Finnishchemist,physicist andmineralogist. Gadolin discovered a "new earth" containing the firstrare-earth compoundyttrium, which was later determined to be achemical element. He is also considered the founder of Finnishchemistry research, as the second holder of the Chair of Chemistry at theRoyal Academy of Turku (orÅbo Kungliga Akademi). Gadolin was ennobled for his achievements and awarded theOrder of Saint Vladimir and theOrder of Saint Anna.
Johan Gadolin was born inTurku (Swedish name Åbo), Finland (then apart ofSweden).[2][3] Johan was the son ofJakob Gadolin, professor of physics and theology at Turku.[4] Johan began to studymathematics at theRoyal Academy of Turku (Åbo Kungliga Akademi) when he was fifteen. Later he changed his major to chemistry, studying withPehr Adrian Gadd, the first chair of chemistry at Turku.[4]
In 1779 Gadolin moved toUppsala University. In 1781, he published his dissertationDissertatio chemica de analysi ferri ("Chemical dissertation on the analysis of iron"), under the direction ofTorbern Bergman.[5][6][7] Bergman founded an important research school, and many of his students, including Gadolin,Johan Gottlieb Gahn, andCarl Wilhelm Scheele, became close friends.[8][9]
Gadolin was fluent in Latin, Finnish, Russian, German, English and French in addition to his native Swedish.[6] He was a candidate for the chair of chemistry at Uppsala in 1784, butJohann Afzelius was selected instead. Gadolin became an extraordinary professor at Åbo in 1785[4] (an unpaid position). Beginning in 1786, he made a chemical "grand tour" of Europe, visiting universities and mines in various countries. He worked withLorenz Crell, editor of the journalChemische Annalen in Germany, and withAdair Crawford andRichard Kirwan in Ireland.[10]
Gadolin was elected a member of theRoyal Swedish Academy of Sciences in 1790.
Gadolin became the ordinary professor of chemistry at the Royal Academy ofTurku in 1797,[11] after the death of Pehr Adrian Gadd. He retained the position until his retirement in 1822.[4] He was one of the first chemists who gave laboratory exercises to students. He even allowed the students to use his private laboratory.[12]
Gadolin made contributions in a variety of areas.
Although he never visited France,[6] he became a proponent ofAntoine Lavoisier's theory of combustion.[4] Gadolin'sInledning till Chemien (1798) was the first chemistry textbook in theNordic countries that questioned the theory ofphlogiston and discussed the role of oxygen in combustion in a modern way.[12]
Gadolin studied the relationship of heat to chemical changes, in particular, the ability of different substances to absorb heat (specific heat) and the absorption of heat during state changes (latent heat).[13] This thermochemical work required extremely precise measurements.[14] Gadolin published important papers on specific heat by 1784, and on the latent heat of steam in 1791.[4] He demonstrated that the heat of ice was equal to the heat of snow,[6] and published a standard set of heat tables.[15]
The best series of experiments on the distribution of heat among different bodies was performed before the year 1784 by Professor Gadolin of Åbo, who, rejecting the notion ofCapacity, introduced the unexceptionable expression,Specific Heat. One of the most beautiful consequences derived from this theory, was the determination of the absolute zero or lowest point in the scale of Heat.[16]
Gadolin became famous for his description of the firstrare-earth element,yttrium. In 1792 Gadolin received a sample of black, heavymineral found in aquarry in a Swedish villageYtterby nearStockholm byCarl Axel Arrhenius.[17] By careful experiments, Gadolin determined that approximately 38% of the sample was a previously unknown "earth", an oxide which was later namedyttria.[17][18] Yttria, oryttrium oxide, was the first known rare-earth metal compound—at that time, it was not yet regarded as anelement in the modern sense. His work was published in 1794.[19]
The mineral that Gadolin examined was namedgadolinite in 1800.[20] Well after his death, the discoverers of the elementgadolinium and its oxidegadolinia named them after Gadolin.[21]
In an earlier paper in 1788 Gadolin showed that the same element can show several oxidation states, in his case Sn(II) and Sn(IV) 'by combining itself with larger or smaller amounts of the calcinating substance'.[22] He described thedisproportionation reaction:
Having established the composition of Prussian blue, Gadolin suggested a method for precipitating ferrous iron as ferro ferricyanide, preceding the work of Gay-Lussac by forty years.[23]
Reports of many of Gadolin's chemical investigations appeared in German in Crell'sChemische Annalen für die Freunde der Naturlehre, Arzneygelahrheit, Haushaltungskeit und Manufacturen. In 1825 he publishedSystema fossilium analysibus chemicis examinatorum secundum partium constitutivarum rationes ordinatorium, a system of mineral classification based upon chemical principles. The introduction outlines Gadolin's theories, and the text presents mineral species in a systematic ordering.[24]
One of Gadolin's latest studies was the chemical analysis of the Chinese alloypak tong in 1810 and 1827.[25] Also known asalpacca or German silver, it was a less expensive silver substitute often containing copper, zinc, nickel, and tin.[26]
Gadolin is also famous for publishing one of the earliest examples of counter-current condensers. In 1791 he improved a condenser design of hisfather's by using the "counter-current principle". By requiring water coolant to flow uphill, the effectiveness of the condenser was increased. This principle was later used byJustus Liebig, in what is today usually referred to as aLiebig condenser.[7][23]
| External image | |
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 https://www.numericana.com/arms/gadolin.htm |
Gadolin was knighted and is registered under number 245 in theFinnish House of Nobility.[27] He was also awarded theOrder of Saint Vladimir and theOrder of Saint Anna.[11] His heraldic device was:
Argent, on a bend Azure with two mullets Or between a rose Gules and crystals Proper.[27]
Johan Gadolin married first, at age 35, Hedvig Tihleman, with whom he had nine children. After his wife's death he married, at age 59, Ebba Palander.[11] Gadolin retired as professor emeritus in 1822 at age 62, a mandatory age of retirement.[11] He moved to a country estate where he lived for another 30 years. He died inMynämäki, Finland on 15 August 1852.[4][6]
TheGreat Fire of Turku of 1827 started in a bakery and damaged or destroyed much of the town of Åbo. Gadolin's laboratory and collection of minerals near the cathedral were destroyed.[6]
{{cite book}}:ISBN / Date incompatibility (help){{cite book}}: CS1 maint: multiple names: authors list (link)| International | |
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