DOLOMIEU, DEODAT-GUY-S1LVAIN TANCREDE GRATET DE, was born at Grenoble on the 24th of June 1750. Iu early youth he was admitted a member of the religious order of Malta, but in consequence of a quarrel with one of his companions which ended in a duel fatal to his adversary he received sentence of death, but after imprisonment he was pardoned, and went to France. After some hesitation whether he should devote himself to classicel literature or to natural history, he decided in favour of the latter. While at Metz with the regiment of earbineera, in which he had obtaiued a commission, Ire formed an acquaintance with the celebrated La Rochefoucault, which ceased but with his existence. Dolomieu was soon afterwards elected a corresponding member of the Academy of Sciences, and quitted the military profession.
At the age of twenty-six Dolomieu went to Sicily, and his first labour was an examination of the environs and strata of /Eton. He next visited Vesuvius, the Apennines, and the Alps, and in 1783 published an account of his visit to the Lipari Islands. Ile returned to Femme at the commencement of the revolution, and early ranged himself on the popular side. He had however no public employment until the third year of the republic, when he was included in the f]cole de Mines, then established; and he was one of the original members of the National Iustitute, founded about the same time. Ile was indefatigable in the pursuit of geological and mineralogical science, and in less than three years he published twenty-seven original memoirs, among which were those on the nature of Lencite, Peridot, Anthracite, l'yroxene, &c.
When Bonaparte undertook the conquest of Egypt, Dolomicu accom panied the expedition. He visited Alexandria, the Delta, Cairo, the Pyramids, and a part of tho mountains which bound the valley of the Nile; and he proposed also to explore the inore interesting parts of tho country, but before lie could carry his plan iuto execution his health became so deranged that he was compelled to return to Europe.
On his passage home he was with his friend Cordier, the mineralogist, and many others of his countrymen, made prisoner after being driven into the Gulf of Tarentum. His companions were soon set at liberty, but the remembrance of the disputes which had existed between him and the members of the Order of Malta led to his removal and sub sequent imprisonment at Messina, where he was confined in a dungeou lighted only by one small opening, which, with barbarous precaution, was closely shut every night. The beat, and the small quantity of fresh air admitted by the window of his prison, compelled him to spend nearly the whole of his time in fanning himself with the few tattered remnants of his clothes, in order to increase the circulation of the air. Great exertion and urgent demands were made by the
scientific men of various countries to obtain his enlargement; and when, after the battle of Marengo, peace was made with Naples, the first article of the treaty was a stipulation for the immediate release of Dolomieu. On the death of Daubenton he was appointed professor of mineralogy, and aeon after his return to France he delivered a course of lectures on the philosophy of mineralogy at the Museum of Natural History.
In a short time Dolomieu again quitted Paris, visited the Alps, and returned to Lyon by Lucerne, the glaciers of Grindelwald and Geneva, and thence to Chateauneuf, to visit his sister and his brother-itelaw De Drde : here he was attacked by a disorder from the effects of which he died, November 26, 1801.
Dolomieu had projected two journeys for aldieg, to his vast stem of geological knowledge—the first through Germauy, and the second through Norway, Denmark, and Sweden. He also proposed to publish a work which he had planned in his prison at Messina; of this there was printed a fragment on Miueral Species,' which is a monument at once of his misfortunes and his genius, being written iu his dungeon iu Sicily, on the margin of a few books, with a bone sharpened against his prison•walls for a pen, and the black of his lamp-smoke mixed with water for ink. In this work the author proposes that the integral molecule shall be regarded as the principle by which the species is to be determined, and that no other specific characters should be admitted than those which result from the compositiou or form of the integral molecule. It roust however be admitted as an objection to this proposal that the integral molecule is not always easily ascertained or characterised.
Soon after his death was published, 'Journal du Dernier Voyage du Citoyen Dolomieu daus les Alpes,' edited by Brunn-Nelgard, Paris, 8vo, 1802. M. Dolomieu's numerous We:mires ' are contained in the de l'Institut,' Journal des Mines,' Journal de Physique,' 'Recuell de l'Acadicmie des Sciences,' and the 'Voyage Pittoresque the Naples et de Sicily; he also wrote several articles for the Dictionnaire Miodralogique,' and the 'Nouvelle Encyclopddie.' Dr. Thomson, in the 'Annals of Philosophy,' vol. xii., p. 166, has drawn up an elaborate summary of the "results of Dolomieu's observations and the bases of his geological systems."