DOLOMIEU, Deodatus Guy Silvanus Tancred de Gratet de, a distinguished mineralogist and geologist, son of Francis de Gratet de Dolomieu, and Frances de Berenger, was born on the 24th of June 1750, in the province of Dauphine.

He was admitted a member of the order of Malta during his earliest infancy, as if he had been devoted from his cradle to glory and to misfortune. At eighteen he embarked in one of the galleys belonging to the order, and soon afterwards unhappily found himself under the necessity of fighting a duel, in which his adversary fell. The laws condemned him to die, but he received a pardon from the grand master; it was, however, necessary that it should be approved by the pope, who for a long time refused to confirm it, notwithstanding the solicitations of several European powers in behalf of the offender, until his consent was at last obtained by the Cardinal Torre-giani. Dolomieu, in the mean time, was closely imprisoned in the island for nine months, and this period of solitude seems to have contributed materially to increase the seriousness χ of his character, and to confirm him in a contemplative turn of mind.

At the age of twenty-two he went to Metz as an officer in the regiment of carabineers, in which he had held a commission for seven years; and he displayed great courage and personal activity on occasion of an accidental conflagration which occurred soon afterwards. His leisure hours were employed in the study of chemistry and natural history, with the assistance of Mr Thirion, an apothecary residing in this city. About the same time he also [7:8:96]became intimate with De la Rochefoucault, with whom he maintained an unshaken friendship ever after.

1. He commenced his literary career with an Italian translation of Bergmans Work on Volcanic Substances, to which he added some Notes, and some observations on the classification of those substances.

2. He also furnished some Notes to a translation of Cron-stedt’s Mineralogy.

3. In 1775 he published Researches on the Weight of Bodies at different distances from the Earth ’ s Centre ; and upon the recommendation of La Rochefoucault, was made a correspondent of the Academy of Sciences at Paris. This compliment seems to have contributed to his determination to relinquish his prospects of success in the army, and to devote himself exclusively to science. Having resigned his commission, he commenced his geological labours with a tour in Sicily, Italy, and Switzerland.

4. This expedition afforded him the materials for his Voyage aux Iles de Lipari, fait en 1781, which he published in 1783, with some other tracts. He describes a singular kind of volcano at Macaluba, in Sicily, formed by air bubbling up from the crater, and causing its contents to overflow. The Essay on the Climate of Malta is rendered inconclusive by the imperfection of the eudiometrical apparatus that was then commonly employed.

5. He spent a part of the same year in examining the effects of the earthquake in Calabria, which are described in his Mémoire sur les tremblemens de Terre de la Calabric, 8vo, Rome, 1784. Among other observations, he notices the singular fact, that all those parts of Calabria to which the earthquake extended arc of a calcareous nature, without any traces of volcanic substances.

6. He published, in the Journal de Physique, vol. xxv. p. 191, a paper on the extinct volcanoes of the Vai di Noto in Sicily.

7. His Mémoire sur les Iles Ponces, 1788, contains also a catalogue of the productions of Mount Etna, and an account of the eruption of 1787.

At the beginning of the revolution Dolomieu embarked, together with his friend La Rochefoucault, in that which appeared to be the cause of liberty. He was in Paris on the 14th of July, but he did not accept of any office under the newly-modified government. La Rochefoucault soon fell a victim to the horrors of the times. Dolomieu was present in his last moments, and received the affectionate messages which he sent to his mother and his wife, who were more distant witnesses of the dreadful scene.

8. No longer hoping for any benefit to his country from the political events of the day, he appears to have resumed his geological studies in other parts of Europe. In a Letter on the Origin of Basalt, dated Rome, 1790, Journ. Phys. vol. xxxvii. p. 193, he considers some stones of this description, for instance, the black trapps of Saxony, as the productions of water; and others, particularly the varieties found in the south of Europe, as of volcanic origin.

9. He writes, in 1791, a Letter from Malta, describing a species of limestone found in the Tyrol, hard enough to become phosphorescent upon collision, and not effervescing with acids until powdered. It was afterwards called the Dolomite. Jowm. Phys. vol. xxxix. p. 3.

10. In a paper of Directions for Naturalists, he gives some useful advice to the circumnavigators about to sail to the South Seas. Jourm Phys. vol. xxxix. p. 310.

11. A series of his essays On Compound Stones and Rocks appeared from time to time in the Journal de Physique, vol. xxxix. p. 374; vol. xl. p. 41, 203, 372. In these he insists on the necessity of supposing that the ocean must have acted with great violence in reducing the continents into their present state; neither the slow subsidence of a general deluge, nor the continued action of ordinary rivers, being sufficient to explain the phenomena; and he remarks, that a violent agitation, such as must necessarily be supposed to have taken place, would naturally cause several alternations in the state of the waters, like immense waves or tides, which must have contributed to the modifications impressed on the earth’s form. Indeed, the facts which support this opinion appear to be so obvious and so numerous, that it is difficult to understand how the opposite hypothesis should ever have become popular.

12. In the same volume there is a short paper On Petroleum found in Rock Crystal, and on some elastic fluids obtained from it, p. 318.

13. The progress of his memoirs was now interrupted by the proscription, in which many of the best and wisest of his countrymen were indiscriminately involved. “His duty and his inclination,” he says, in a Note without a date, “required the devotion of his time and his arm to the defence of his king ;” and he was obliged to submit to a temporary dereliction of his pursuits of science. P. 481.

14. But the cause was hopeless, and it was impossible for him to render it any essential service. He soon resumed his pen, and took occasion to express, with great spirit and energy, his political feelings, in his Memoir on the Physical Constitution of Egypt. Journ. Phys. vol. xlii. p. 41, 108, 194. In Egypt, he observes, there are many calcareous rocks and sands, which cannot have been brought down by the Nile; but there is also much of the soil which has the appearance of having been derived from the mud, with an admixture of sand only. The same cause, he thinks, may possibly have raised the bed of the river, so that the relative height of the inundations may have been little altered. He conceives that the Delta has increased even in modern times, though far less rapidly than it appears to have done formerly; for he is disposed to admit the credibility of the Homeric account of the distance of the Pharos from the continent, although he attempts to explain a part of the supposed change by the filling up of the lake Mareotis only; and, on the whole, he imagines that about a thousand square leagues of the surface of Egypt have been gained from the sea. He has not, however, thought it necessary to discuss the arguments which Bruce and others have brought against the established opinion, and against the facts asserted by Herodotus in its support; although some of the best informed of modern travellers have allowed the accuracy of Bruce’s statements relating to this subject.

15. In a short paper On the Figured Stones of Florence, Mr Dolomieu attributes the appearance of the arborescent and architectural figures which characterize them, to the process of slow decomposition and oxidation, gradually producing the stains in the extremely minute fissures, which favour these changes. Journ. Phys. vol. xliii. p. 285.

16. Upon the establishment of the school of Mines, in 1795, he accepted the situations of professor of geology and inspector of mines. He was also made one of the original members of the National Institute of Sciences and Arts, then organized by a law of the existing government. From this time he appears to have redoubled the energy with which he had before laboured in the pursuit of natural knowledge, and he published a great number of memoirs in the course of a very few years. One of the first of these consisted of Observations on a pretended Coal Mine, called the Desiree. Journal des Mines, year iii. N. ix. p. 45.

17. His Methodical Distribution of Volcanic Substances appeared in the new Journal de Physique, vol. (i.) xliii. p. 102, 175, 241, 406; vol. (ii.) xliv. p. 81. Of the five classes which he had before proposed in his notes on Bergman, the first comprehends substances actually pro-duced[7:8:97] by volcanoes; the second, substances thrown out by them unaltered; the third, bodies altered by the volcanic vapours; the fourth, bodies altered in the moist way; and the last, substances illustrative of the history of volcanoes only. The subsequent papers are partly continuations of the Memoirs on Compound Pocks ; and they also relate particularly to the nature of lavas, some of which are shown to be formed from argillaceo-ferruginous stones. The heat of lavas has been pretty accurately entertained, in some cases, by the fusion of silver coins exposed to it, whilst those of copper remained entire; there is, however, an account of a stream of lava over which some nuns are stated to have walked while it was yet fluid; and this circumstance Mr Dolomieu attributes to a mixture of sulphur, which remained melted at a temperature comparatively low. Some objections to this opinion have, however, been advanced by Mr Sage. Journ. Phys. vol. xlv. p. 281. An Explanation of the New Method adopted in the Description of Minerals was also published in the Magazin Encyclopédique, vol. i. p. 35.

18. Among the shorter essays of Mr Dolomieu, we find a Description of the Beryl. Journ. des Mines, year iv. Ventose, p. 11.—19. Description of the Mine of Manganese at Pornaneche. Germinal, p. 27.—20. Letter on the Heat of Lavas. Messidor, p. 53.—21. On Quartzose Concretions, p. 56. —22. On Ancient Lithology. Mag. Enc. i. p. 437.—23. Description of the Emerald, ii. p. 17, 145.—24. A letter from Berlin on the Magnetic Serpentine, ii. vol. vi. p. 7.—25. On the Leucite, or White Garnet. Journ. des Mines, year v. p. 177.—26. On the Necessity of Chemical Knowledge to a Mineralogist, and on the term Chrysolith, p. 365.

27. An Introductory Discourse on the Study of Geology appears in the Journal de Physique, vol. xlv. p. 256. It was preliminary to a course of lectures on the natural position of minerals, and it contains good and detailed directions for the use of students, with some eloquent advice on the benefits of travelling, and on the merits of temperance and simplicity of manners.

28. In the next volume, p. 203, our author announces the Discovery of the Crystallized Sulphate of Strontia in Sicily. It had before been found uncrystallized in France.

29. On Colour as a Characteristic of Stones. Joum. Phys. vol. (iii.) xlvi. p. 302. This essay contains some objections to Werner’s habit of relying too implicitly on colour, and the white tourmaline of St Gothard is adduced as an instance of the triumph of form over complexion; a just tribute of commendation is also paid to the merits of Haüy.

30. A paper On the Pyroxene, or Volcanic Schorl, is chiefly destined to support the opinion that such crystals have been formed previously to the existence of the volcano, by the observation of a specimen found adhering to a rock which had never undergone the effect of fire. Journ. Phys. vol. xlvi. p. 306.

31. A Memoir read to the Institute contains the report of Mr Dolomieu’s mineralogical tours, made in the years 1797 and 1798. Journ. Phys. vol. xlvi. p. 401. Journ. des Mines, year vi. p. 385. He visited the south of France, the Alps, and the neighbouring lakes and mountains, almost always on foot, and with his hammer in his hand, accompanied by Brochart, Cordier, Bonniers, and his brother-in-law the Marquis de Drée. From his observations in Auvergne, in particular, he concludes that the foundation or origin of the volcanoes there is certainly below the granite rocks, which therefore cannot, properly speaking, be called primitive; and he proceeds to a much bolder and less admissible conjecture, that the central parts of the globe are at present in a state approaching to fluidity, which he attempts to support by the ready transmission of the shocks of earthquakes to distant places; and he even quotes the authority of Lagrange as having been disposed to encourage the opinion. Volcanoes, in general, he divides into ancient and modern, as separated by the intervention of the changes which have reduced the continents to their present form. With respect to the heat of the lava, he observes, that it has not been sufficient to expel the carbonic acid from the limestone which has been exposed to it. He also remarks, that, where basalt in fusion has been suddenly cooled by water, the contraction has caused it to divide into columns, which are not crystalline, because their angles are irregular, and which are smaller and more uniform in proportion as the water is deeper. He contrasts the horizontal strata of France with the vertical tables of the Alps, and particularly describes the accretion of a mantle of calcareous substances, two miles in height, which has attached itself to the north-east faces of the Alps, subsequently to their first formation as mountains. From this expedition he brought home an immense collection of rocks and stones, principally valuable for their arrangement with a view to the illustration of his particular doctrines in geology, which, with the rest of his cabinet, have since formed a part of the superb museum of Μ. de Drée.

32. He published, about the same time, a paper On the Mountains of the Vosges. Jourìi. des Mines, year vi. p. 315.

33. Extract of a Report on the Mines of the department of the Lozère, p. 577.

34. The only communication of Mr Dolomieu printed in the Memoirs of the Institute, is rather on a mechanical than a mineralogical subject, containing an Account of the Art of Making Gun-Elints. Μ. Math. vol. iii. p. 348. Nicholson’s Journal, 8. vol. i. p. 88.

He was engaged, after his return from Switzerland, in some mineralogical contributions to the Encyclopédie Méthodique, when he was invited to take a part in the scientific arrangements of the expedition to Egypt. He did not, however, strictly confine himself to this department, but was successfully employed as a negociator for the surrender of Malta. In Egypt he visited the pyramids, and examined some of the mountains which form the limits of the country, but his health soon compelled him to return to Europe. In this voyage the vessel on board of which he had embarked was nearly overwhelmed by a tempest, and appears to have been only saved by the temporary expedient of throwing overboard pounded biscuit mixed with straw, which entered the leaks with the water, and afforded a partial remedy, which was repeated from time to time, until the vessel, at the last extremity, was driven into a port in the Gulf of Tarentum. The counter-revolution of Calabria had occurred but a few days before, and Dolomieu, with his companion Cordier, and many others of his countrymen, were thrown into prison, and they even owed their lives to the great exertions of an individual among the insurgents in their favour. They were afterwards removed to Sicily, but with the loss of their collections and their manuscripts; and Dolomieu being denounced, as a member of the order of Malta, for high treason, was separated from his countrymen, and closely confined in a dungeon. Solicitations were addressed to the kiqg of Naples on his behalf, by the National Institute, by the French government, by the king of Spain, and in the name of the Royal Society of London, although its illustrious president was certainly not “at the time in Sicily,” as the Nouveau Dictionnaire Historique affirms; but the captive derived essential assistance from the good offices of an English gentleman at Messina, and some Danes accommodated him in his pecuniary arrangements. Whilst still a prisoner, he was appointed successor to Daubenton, at the Museum of Natural History; and the very circumstance of his captivity seemed to give him an advantage [7:8:98]over his competitor. In the treaty made by the French with the king of Naples, after the battle of Marengo, it was expressly stipulated that Dolomieu should be set at liberty.

35. Upon his return to Paris he was made a member of the Conservative Senate, and he delivered soon afterwards a course of lectures on the philosophy of mineralogy. He had written part of an essay on this subject during his imprisonment in Sicily, with a bone for a pen, and a mixture of soot and water instead of ink, on the margins of such books as were allowed him; and his last publication was Sur la Philosophie Minéralogique, et sur l’espece Minéralogique. Paris, 1801. His classification depended on considering the species as determined by the integrant molecule, and on arranging the different external forms as varieties, whether regular as modifications, or irregular as imperfections; besides the variations of colour and appearance, and the more essential affections of the consistence of the substance, which may be called contamination; but the whole essay may be considered as rather of a logical than of a physical nature.

After the delivery of his lectures, he set out upon a new expedition to his favourite mountains, in company with Mr Neergard and Mr d’Eymar, who published an account of the journey. Paris, 1802. He meditated a tour into Germany and to the north of Europe; but his return to Paris was interrupted by indisposition, when he had arrived, by way of Lyons, at Chatcauneuf, where he met his sister and his brother-in-law, and this journey was his last.

The merits of, Dolomieu consisted as much in his personal character as in his scientific attainments. His conversation was modest, though his courage was heroic; his manners were simple though refined; and though his talents were considerable, they seem to have been surpassed by his industry. It has been remarked, that he often undertook, more than he had any reasonable prospect of completing; but, in the mean time, he was perhaps as happy in the pursuit as he would have been in the attainment of his object. He died, universally regretted, at Dree, near Maçon, on the 27th of November 1801, in the midst of his affectionate family, who had been the partakers in his pursuits, and the consolation of his misfortunes.

Lacépède, Notice Historique sur la Vie et les Ouvrages de Dolomieu; Mern. Math. Inst. vol. vii. 1800, p. 117; Chalmers’s Biographical Dictionary, vol. xi. 8vo, London, 1818. (l. l.)