Lavoisier, Anthony Lawrence

, a distinguished chemical philosopher, was born at Paris, on the 13th of August, 1743. His father, a man of opulence, sparing no expence on his education, he displayed very early proofs of the extent and success of his studies, especially in the circle of the physical sciences. In 1764, when the French government proposed a prize question, relative to the best method of lighting the streets of a large city, Lavoisier presented a dissertation on the subject, which was highly approved, printed at the expence of the academy of sciences, and obtained for him the present of a gold medal from the king, which was delivered to him by the president of the academy, at a public sitting, in April 1766. Two years afterwards, he was admitted a member of that learned body, of which he was constantly one of the most active and useful associates. About the same time, he was occupied in experimental researches on a variety of subjects such as the analysis of the gypsum found in the | neighbourhood of Paris; the crystallization of salt; the properties of water; and in exploring the phsenomena of thunder, and of the aurora borealis: and he distinguished himself by several dissertations on these and other topics, practical and speculative, which appeared in different periodical works. In the Memoirs of the Academy for 1770 were published his observations on the nature of water, and on the experiments which had been supposed to prove the possibility of its conversion into earth. He proved, by a careful repetition of these experiments, that the earthy deposit, left after repeated distillations of water, proceeded solely from an abrasion of the vessels employed. Lavoisier performed several journeys into various parts of France, in company with M. Guettard; in the course of which he collected a store of materials for a lithological and mineralogical history of that kingdom, which he ingeniously arranged in the form of a chart. These materials were the basis of a great work on the revolutions of the globe, and on the formation of the strata of the earth: two interesting sketches of which were printed in the Memoirs of the Academy for 1772 and 1787.

Between these two periods, Lavoisier, struck with the discoveries that had been made by Dr. Black, and pursued by Dr. Priestley, respecting the properties of certain aeriform substances, gases, or factitious airs, entered into the same field of research, and published the result of his experiments in 1774, in his “Opuscules Chymiques,” which contained not only a clear and elegant view of all that had hitherto been done, in regard to gaseous or aeriform fluids, but also several original experiments, remarkable for their ingenuity and accuracy.

The existence of a gaseous body, in a fixed or solid state, in the mild alkalies and alkaline earths, which, when expelled from these substances, assumed an aerial form, and left them in a caustic state, as well as its production during the combustion of fuel, had been demonstrated by Dr. Black; and Bergman had shown that this air possessed acid properties. Dr. Priestley had also submitted it to various experiments in 1767, but the honour of ascertaining the real constituent parts of this acid gas, or fixa^le air, was reserved for Lavoisier. He now turned his experimental researches to the subject of the calcination of metals. It had already been shewn by Rey and Homberg, that metals acquire an augmentation of weight during | calcination but they differed in the causes of this augmentation. Lavoisier, who published the result of his experiments on the subject in 1774, demonstrated that a given quantity of air was requisite for the calcination of a given quantity of tin; that a part of the air is absorbed during this process, by which not only the bulk, but the weight of the air is diminished; that the weight of the tin is increased during the same process; and lastly, that the weight acquired by the tin is exactly equal to that which is lost by the air.

Thus, by a few simple, accurate, and well-chosen experiments, Lavoisier had apparently arrived at the legitimate inference, that during the process of the formation of acids, whether with carbonaceous matter, sulphur, or phosphorus, and also during that of the calcination of metals, an absorption and fixation of air take place; and thus he gained a glimpse of principles, in the view of which hit singular sagacity in devising experiments, and his accuracy in executing them, would in all probability have alone conducted him to those brilliant results to which Dr. Priestley so materially contributed. The synthetic proofs only of this union of air with the base bad been as yet ascertained; but Dr. Priestley first furnished the analytic proof, by dissevering the combination; a discovery which at once advanced the nascent theory of Lavoisier, and, in his hands, became the source of more than one important conclusion. In August 1774, Dr. Priestley discovered that by heating certain metallic calces, especially the calcined mercury (the precipitate per sc, as it was then called) a quantity of air was separated, while the mercury resumed its metallic form; and this air, which he found was much purer than that of the atmosphere, he called, from the theory of the time, dephlogisticated air. Having communicated this discovery to Lavoisier, the latter published a memoir in 1775, in which he shewed, in conformity with the experiments of Dr. Priestley, that the mercurial precipitate per se t by being heated in a retort, gives out a highly respirable air (called since oxygeri]^ and is itself reduced to the metallic state; that combustible bodies burn in this air with increased brilliancy; and that the same mercurial calx, if heated with charcoal, gives out not the pure air, but fixed air; whence he concluded that fixed air is composed of charcoal and the pure air. It has, therefore, since been called carbonic acid. | A second very important consequence of Dr. Priestley’s discovery of the pure or vital air, was the analysis of the air of the. atmosphere, which was accomplished by Lavoisier in the following manner. He included some mercury in a close vessel, together with a known quantity of atmospheric air, and kept it for some days in a boiling state; by degrees a small quantity of the red calx was formed upon the surface of the metal; and when this ceased to be produced the contents of the vessel were examined. The air was found to be diminished both in bulk and weight, and to have been rendered altogether incapable of supporting combustion or animal life; part of the mercury was found converted into the red calx, or precipitate per se; and, which was extremely satisfactory, the united weight of the mercury and the precipitate exceeded the weight of the original mercury, by precisely the same amount as the air had lost. To complete the demonstration, the precipitate was then heated, according to Dr. Priestley’s first experiment, and decomposed into fluid mercury and an air which had all the properties of vital air; and this air, when mixed with the unrespirable residue of the original air of the receiver, composed an elastic fluid possessing the same properties a atmospherical air. The vital air was afterwards made the subject of various experiments in respect to the calcination of metals, to the combustion and conversion of sulphur and phosphorus into acids, &c. in which processes it was found to be the chief agent. Hence it was named by Lavoisier oxygen (or generator of acids), and the unrespirable residue of the atmosphere was called azot (i. e. incapable of supporting life).

The new theory thus acquired farther support and conistency; oxygen appeared to be one of the most active and important agents of chemistry and of nature; combustion, acidification, and calcination (or, as it was now called, oxydatioriy the calces being also termed oxyds^ i. e. something approaching to, or resembling acids), were proved to be processes strikingly analogous to each other; all according in these points, that they produced a decomposition of the atmospheric air, and a fixation of the oxygenous portion in the substance acidified or calcined.

Time alone seemed now requisite to establish these doctrines, by exemplifying them in other departments of chemical research. In 1777 six memoirs were communicated feo the Academy of sciences by Lavoisier, in which his | former experiments were confirmed, and new advances were made to a considerable extent. Our countrymen, Black and Crawford, in their researches respecting latent heat, and the different capacities of bodies under different circumstances, had laid a solid foundation, on which the doctrines of combustion, resulting from the foregoing experiments, might be perfected, and the cause of the light and heat connected with it might be explained. The first mentioned philosopher, Dr. Black, had shewn, that a solid, when it is made to assume a liquid form, and a liquid, when it assumes the form of vapour, absorbs or combines with, and renders latent, a large portion of heat, which is again parted with, becomes free and cognizable by the sense of feeling, and by the thermometer, when the vapour is again condensed into a liquid, and the liquid becomes solid. In like manner, it was now said by Lavoisier, during the process of combustion, the oxygen, which was previously in a gaseous state, is suddenly combined with the substance burnt into a liquid or solid. Hence all the latent heat, which was essential to its gaseous state, being instantaneously liberated in large quantity, produces flame, which is nothing more than very condensed free heat. About the same time, the analogy of the operation and necessity of oxygen in the function of respiration, with the preceding hypothesis of combustion, was pointed out by Lavoisier. In the process of respiration, it was found that, although atmospheric air is inhaled, carbonic acid and azot are expired. This animal operation, said Lavoisier, is a species of slow combustion: the oxygen of the air unites with the superfluous carbon of the venous blood, and produces carbonic acid, while the latent or combined caloric (the matter of heat) is set free, and thus supplies the animal heat. Ingenious and beautiful, however, as this extension of the analogy appeared, the subject of animal temperature is still under many obscurities and difficulties. The phenomena of chemistry, however, were now explicable upon principles more simple, consistent, and satisfactory than by the aid of any former theory; and the Lavoisierian doctrines were everywhere gaining ground. But there yet remained a formidable objection o them, which was derived from a circumstance attending the solution of metals in acids; to wit, the production of a considerable quantity of inflammable air. If sulphuric acid (formerly called vitriolic acid, or oil of vitriol) consists only | of sulphur and oxygen, it was said, how does it happen, that wheti these two substances, with a little water, come in contact, they should produce a large quantity of inflammable air during their re-action? This objection was unanswerable, and appeared to be fatal to the whole theory: but it was most opportunely converted into an argument in its favour, by the great discovery of the decomposition of water, made by Mr. Cavendish; who resolved that element, as it was formerly esteemed, into oxygen and inflammable air. The latter has since, therefore, been called hydrogen, or generator of water. This experiment was repeated with full success by Lavoisier and his associates in 1783; and the discovery was farther established by a successful experiment of the same chemists, carried on upon a grand scale, in which, by combining the oxygen with hydrogen, they produced water, and thus adding synthesis to analysis, brought the fact to demonstration.

This new view of chemical phenomena, together with the immense accession of new compounds and substances, which the labours of modern experimentalists had brought to light, appeared to demand a correspondent alteration in the nomenclature. Accordingly, a committee of some of the ablest of the French chemists, of whom Lavoisier was the most conspicuous, undertook the arduous task, and produced a regular system of nomenclature, derived from the Greek language, which, although far from being faultless, and notwithstanding much opposition with which it was at first treated, has become the universal language of chemical science, and has been adopted even in pharmacy and medicine. His work, entitled “Elemens de Chymie,” which was published in 1789, was a model of scientific composition.

We have hitherto viewed M. Lavoisier principally a* a chemical philosopher, in which character he has founded his great claims to the respect and admiration of posterity. But the other arts and sciences are indebted to him for considerable services which he rendered them, both in a public and private capacity. In France, more than in any other country, men of science have been consulted in matters of public concern; and the reputation of Lavoisier caused him to be applied to, in 1776, to superintend the manufacture of gunpowder, by the minister Turgot. By the application of his chemical knowledge to this | manufacture, he was enabled to increase the explosive force of the powder by one- fourth and while he suppressed the troublesome regulations for the collection of its materials from private houses, previously adopted, he quintupled the produce. The academy of sciences received many services from his hands. In addition to the communication of forty papers, relative to many of the most important subjects of philosophical chemistry, which were printed in the twenty volumes of Memoirs, from 1772 to 1793, he most actively promoted all its useful plans and researches, being a member of its board of consultation, and, when appointed to the office of treasurer, he introduced order into its accounts, and economy into its expenditure. When the new system of measures was proposed, he contributed some new and accurate experiments on the expansion of metals. The national convention consulted him with advantage concerning the best method of manufacturing assignats, and of securing them against forgery. Agriculture early engaged his attention, and he allotted a considerable tract of land on his estate in the Vendome, for the purpose of experimental farming. The committee' of the constituent assembly of 1791, appointed to form an improved system of taxation, claimed the assistance of his extensive knowledge; and he drew up, for their information, an extract of a large work on the different productions of the country and their consumption, for which he had been long collecting materials. This was printed by order of the assembly,under the title of “Richesses Territoriales de la France,” and was esteemed the most valuable memoir on the subject. In the same year, he wa appointed one of the commissioners of the national treasury; and he introduced into that department such order and regularity, that the proportion between the income and the expenditure, in all the branches of government, could be seen at a single view every evening. This spirit of systematic and lucid arrangement was, indeed, the quality by which he was peculiarly distinguished, and its happy influence appeared in every subject which occupied his attention.

The private life of this distinguished person was equally estimable with his public and philosophical character. H was extremely liberal in his patronage of the arts, and encouraged young men of talents in the pursuit of science. His house became a vast laboratory, where philosophical experiments were incessantly carrying on, and where he | held conversaziones twice a week, to which he invited every literary character that v. >i celebrated in geometrical, physical, and chemical studies; in these instructive discussions, the opinions of the most eminent literati in Europe were canvassed; passages the most striking and novel, out of foreign writers, were recited and animadverted on; and theories were compared with experiments. Here learned men of all nations found easy admission; Priestley, Fontana, Blagden, Ingenhousz, Landriani, Jacquin, Watt, Bolton, and other illustrious physiologists and chemists of England, Germany, and Italy, found themselves mixed in the same company with Laplace, Lagrange, Borda, Cousin, Meunier, Vandermonde, Monge, Guyton, and Berthollet. In his manners M. Lavoisier was mild, affable, and obliging; a faithful friend and husband, a kind relation, and charitable to the poor upon his estates; in a word equally claiming esteem for his moral qualities, as for those of his understanding.

The time was arrived, however, when distinction even by his talents and worth was so far from securing public respect, amid the tumults of the revolution, that it became a source of danger, and, when joined with wealth, was almost certainly fatal. All those especially who had held any situation under the old administration, particularly in the financial departments, were sacrificed, during the murderous reign of Robespierre, to the popular odium. Lavoisier was seized and thrown into prison, upon some charges fabricated against himself and twenty-seven other farmers-general. During his confinement he foresaw that he should be stripped of all his property; but consoled himself with the expectation that he would be able to maintain himself by the practice of pharmacy. But a more severe fate awaited him: he was capitally condemned, and dragged to the guillotine, on the 8th of May, 1794.

The name of Lavoisier will always be ranked among the most illustrious chemists of the present age, when it is considered what an extensive and beneficial influence his labours have had over the whole science. It has been said, indeed, that if he be estimated on the score of his actual discoveries, not only Scheele and Priestley, and Cavendish, but many more, will stand before him. But he possessed in a high degree that rare talent of discernment, by which he detected analogies, which others overlooked, even in their own discoveries, and a sagacity in devising | and an accuracy in completing his experiments, for the purpose of elucidating every suggestion which he thus acquired, such as few philosophers have possessed. No one who did so much, probably ever made so few unsuccessful or random experiments. It was the singular perspicuity, simplicity, and order to which he reduced the phenomena of chemistry, that claimed for his theory the general reception which it met with, and occasioned the abandonment of those doctrines which prejudice and habit conspired to support. Subsequent discoveries, however, and more especially those numerous facts which the genius of sir Humphrey Davy has lately brought to light, through the medium of that most powerful agent of decomposition, galvanism, have rendered several modifications of the Lavoisierian theory necessary, and bid fair to produce a more general revolution in the language and doctrines of chemistry.

M. Lavoisier married, in 1771, the daughter of a farmergeneral, a lady of pleasing manners and considerable talents, who partook of her husband’s zeal for philosophical inquiry, and cultivated chemistry with much success. She engraved with her own hand the copper-plates for his last work. Mad. Lavoisier afterwards gave her hand to another eminent philosopher, count llumtbrd, who, in 1814, left her a widow a second time. ¹