Popular Science Monthly/Volume 20/February 1882/M. Sainte-Claire Deville

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HENRI-ÉTIENNE SAINTE-CLAIRE DEVILLE, one of the most distinguished of French chemists, was born at St. Thomas, in the Antilles, of French parents, March 11, 1818, and died at Boulogne-sur-Seine on the first day of July last. He went to France while still a boy, with his brother, Charles Deville, the meteorologist, and had his attention drawn early in his career in school to chemical studies, which were then enjoying high credit under the brilliant results of the investigations of Thenard, Gay-Lussac, Chevreul, Dumas, Balard, and Pelouse. It is said that he hesitated at first between science and music, but was finally attracted to chemistry by the lectures of Dumas; and, on leaving college, he constructed a laboratory at his own expense, and pursued his researches without either master or pupils for nearly nine years. He was not more than twenty years old before he marked his place in science by an original work, the scale of which he enlarged in the following years, exhibiting in it so many proofs of an inventive and clear mind that he was sent to Besançon to organize the newly-created faculty of sciences in that city, and became its dean—at the age of twenty-six years. Here, on invitation of the municipal council, he undertook the analysis of the waters of the river Doubs, and of the numerous springs around the town. Applying new and more exact methods, he ascertained the presence of nitrates and silicates in all the waters—facts which were afterward confirmed by Boussingault, and shown by him to have an important bearing on agriculture. This analytical talent out of the usual line, says M. Pasteur in his funeral eulogy, which was one of the features of Deville's genius, never abandoned him; and, "if you review the field of his persevering labor as a whole, you will find it marked at every step by evidences of a passionate seeking for the most perfect analytical methods. That rigor of analysis, which is the probity of the chemist, . . . Deville communicated to all his pupils, and it may be seen to shine in the labors of all those whom he inspired—of Debray, Troost, Fouqué, Grandeau, Hautefeuille, Gemez, Lechartier, and many others."

In 1851, when thirty-three years old, Deville succeeded Balard in the chair of Chemistry in the Higher Normal School in Paris, where he worked at tasks which have led to the enrichment of wealthy manufacturers, and with an ardor which made the laboratory of this institution a central point of chemical investigation for all Europe as well as for France, for the modest salary of three thousand francs, or six hundred dollars. In 1854 he assumed, in addition to his work here, the duties of a lectureship, which fourteen years later became a full professorship, in the Sorbonne.

M. Deville's first researches were in organic chemistry, and began to attract attention in 1840, when he published a remarkable study of turpentine-oil and various derivatives of the terpenes, the carefully tabulated results of which form the chief basis of our knowledge of the different isomeric states of this group. It was followed in 1842 by a research on toluene, which has had an important bearing in the researches on the aniline colors.

He soon afterward turned away from this branch of the science to devote himself to mineral chemistry, in which, says M. Pasteur, he for thirty years held the scepter in France and Europe.

His first great discovery in this department was announced in 1849, when he demonstrated the existence of anhydrous nitric acid, and described its preparation by the action of chlorine on silver nitrate, and its properties. The possibility of the existence of monobasic acid anhydrides had previously been disputed. In 1852 he published in the "Annales de Chimie et de Physique" an important paper upon the metallic carbonates and their combinations, and in 1853 he discovered a new method of mineral analysis. In 1855 he began the famous research on metallic aluminium, which proved, says his biographer in "Nature," to be one of the crowning features of his life-work. He was furnished the means by which he was enabled to carry his experiments to success by Napoleon III, who was looking forward to the application of the qualities of a metal of so light a specific gravity to the making of armor and helmets for the French cuirassiers. The anticipation proved to be a mere dream, and impracticable; but the ambition in which it was bred was caused for once to minister to the lasting benefit of mankind. With the means thus furnished, M. Deville was able to carry on his experiments on a large scale, and so rapidly that even in the same year in which he began he displayed at the exhibition in Paris massive bars of the metal, that had hardly been seen before in a pure state. The study of this metal and of its metallurgical production, as well as of the various compounds of aluminium, carried out during a series of years, forms, says "T. H. N." in "Nature," one of the most remarkable and complete contributions made to inorganic chemistry within a recent period. The metal is now prepared in one English and two French establishments according to Deville's perfected process, which consists essentially in heating the double salt (chloride) of aluminium and sodium with metallic sodium, fluor-spar or cryolite being added as a flux, and is used for a variety of objects where lightness, strength, and freedom from oxidation are demanded, and in many valuable alloys, of which it forms the essential part. It has not come into as extensive use as Deville hoped it might, for it is still too high in price and is hard to weld. The operations with aluminium have resulted in building up other industries, such as the production of bauxite and cryolite, and the manufacture of metallic sodium, the price of which sank in ten years from two thousand francs to fifteen francs per kilogramme. In 1863 M. Deville, in connection with Caron, applied his aluminium method to the manufacture of magnesium, and made it possible to produce that metal in commercial quantities. With Debray he carried on exhaustive researches from 1859 to 1862 on the metals of the platinum group, in which be applied the oxyhydrogen blow-pipe on a large scale to the fusion of platinum, now for the first time accomplished. This led him to operations at higher temperatures than had ever before been attained, except perhaps casually, involving the artificial production of crystalline minerals, which has since been carried out by other chemists to a larger extent, and numerous determinations of the vapor densities of bodies that are ordinarily solid, like the chlorides of aluminium, iron, and various rare metals, by means of which the molecular weights of various compounds have been satisfactorily ascertained.

M. Deville's highest title to honor, says M. Würtz, rests upon his having introduced to science the idea of dissociation as a particular method of decomposition, the understanding of which has rendered the grandest services to theoretical chemistry. Decomposition was believed, previous to his researches in this line, to be a simple phenomenon, taking place and being repeated with each body at a fixed temperature. M. Deville has shown that it is not always so, but that decomposition is accomplished in certain cases by degrees, within certain limits of temperature, in such a manner that it is arrested at a given temperature, by the establishment of an equilibrium between the decomposing body and the products of its decomposition. The principle explains a variety of occurrences among thermal phenomena that have hitherto not been accurately accounted for, and may be defined, says "Nature," "as the property of many compound bodies to undergo partial decomposition under the influence of heat in confined spaces, until the liberated gas or vapor has attained a certain tension, greater or less, according to the temperature. So long as this temperature remains constant, no further decomposition takes place, neither does any portion of the separated elements recombine. If the temperature be raised, decomposition recommences, and continues until a higher tension of the liberated gas or vapor, definite for that particular temperature, is attained. If the temperature falls, recomposition ensues, until the tension of the residual gas is reduced to that which corresponds with the lower temperature. The enunciation of this simple but far-reaching principle has thrown light upon a number of phenomena, such as the formation of minerals, the apparent volatilization of solids, etc.; and has been the fruitful source of countless novel discoveries."

Other researches with which M. Deville's name is associated are those on boron, which he prosecuted in company with Wöhler in 1857, on the preparation of silicium and its compounds with copper (1863), a new calorimeter, on the changes attendant upon the mixture of liquids (1870), and the examination of a large variety of minerals and natural products. A few years ago he was appointed on the commission to prepare the international normal standard of the measure of a metre, and acquitted himself of the task allotted to him with characteristic devotion to the interests of science.

His simplicity was the predominant quality in M. Deville's character, and distinguished him alike in his social relations and in his scientific labors. He kept away from the theoretical disputes in which many of his colleagues were too prone to indulge, finding abundant employment for his own resources "in attacking the still unsolved problems of inorganic chemistry"; and he is said to have gone so far as to declare the whole theoretical tendency of modern chemistry, the atomic theory not excepted, to be a superfluous speculation. His methods, his apparatus, and the few fundamental principles he has enunciated, were all alike simple. He was much beloved by his students, and was devoted to them. Though the labor of drilling the pupils of the Normal School year after year in the same elementary principles must have been irksome in the extreme, he was always kind and just, always ready with counsel and help. His proverbial tenderness toward candidates in the public examinations is illustrated by an anecdote:

"Let us see, monsieur," he asks; "of what is water composed?. . . Of o—?"
"Xygen," the pupil replied.
"And what else?. . . Of hy—?"
"Drogen," added the candidate.
"That is right, monsieur. Thank you."

M. Pasteur describes him as small in stature, with a high forehead, lively eyes, and an impulsive walk; a man who might have compared the beating of the blood in his veins to that of the waves in the river Rhône.

M. Deville's chief works include his contributions to the "Annales de Chimie et de Physique" concerning the properties of aluminium and his experiments with it; a comprehensive work on the same subject ("De l'Aluminium, ses Propriétés, sa Fabrication"), published in 1859; a report on the fusion of steel in the reverberating furnace without using a crucible (1862); and his large work on the metallurgy of platinum and the metals that accompany it (1863). Among his more important contributions to the Academy of Sciences are papers on the three molecular states of silicium and a memorandum on the production of high temperatures.

M. Pasteur relates that at one time, when he thought that he himself was about to die, M. Deville rallied him by telling him that he must live to pronounce his funeral address. The duty was beautifully fulfilled by M. Deville's fellow-worker in the fields of investigation. On the 5th of July last, M. Pasteur pronounced an affectionate funeral eulogy on his deceased colleague, beginning with the appropriate apostrophe: "Thy sympathetic features, thy gayety of spirits, thy frank smile, the sound of thy voice, still go with us and live among us. The ground that bears us, the air we breathe, the elements which thou didst love to question, and which were always so docile in answering thee, could tell us of thee if there were need of it. The entire world knows the services thou hast rendered to science, and, beyond the mountains and the seas, every man who is interested in the progress of human thought wears mourning for thee."