Antoine Laurent Lavoisier

Antoine Laurent Lavoisier. portrait gallery, 1835

Antoine Lavoisier
(26th August, 1743 – 8th May, 1794)
"father of modern chemistry"

ANTOINE LAURENT LAVOISIER was born in Paris, August 26, 1743. He was educated under the eye of his father, a man of opulence, with discernment to appreciate his son's abilities, and liberality to cultivate them without regard to cost. Lavoisier early showed a decided inclination for the physical sciences ; and before he was twenty years old, had made himself master of the principal branches of natural
philosophy.

In 1764 the government proposed an extraordinary premium for the best and cheapest project of lighting the streets of Paris, and other large cities. To this subject, involving a knowledge of several branches of science, Lavoisier immediately devoted his attention. He produced so able a memoir, full of the most masterly, accurate, and practical views, that the gold medal was awarded to him. This production was the means of introducing him into the Academy of Sciences, of which, after a severe contest, he was admitted a member, May 13, 1768; and he proved himself through life one of its most useful and valuable associates.
At this time the whole range of chemical and physico-chemical science was in an extremely imperfect state; and the first steps to a more improved system involved the necessity of clearing away a vast mass of error which encumbered the path to truth. For instance, one of the fanciful ideas, the offspring of the alchemy of the dark ages, which still continued to haunt the regions of science, was the belief of the conversion of water into earth by gradual consolidation. This subject Lavoisier treated in the true spirit of the experimental method, and clearly showed that the pretended conversion was either a deposition of earthy particles, or a sediment arising from the action of the water on the internal surface of the retort. He also laboured on the analysis of the gypsum found in the neighbourhood of Paris, and on the crystallization of salts. He discussed the project of conveying water from L'Yvette to Paris, and the theory of congelation; and to these researches added extensive observations on the phenomena of thunder and the Aurora Borealis.

He next directed his attention more especially to mineralogy; and made excursions, in conjunction with Guettard, into all parts of France, endeavouring to form from different districts a complete collection of their characteristic mineral productions. He made advances towards a systematic classification of facts connected with the localities of fossils, which afterwards served as the basis of his work on the revolutions of the globe and the formation of successive strata, of which two admirable abstracts were inserted in the Memoirs of the Academy of Sciences, for 1772 and 1787.

Thus during the earlier part of his life, Lavoisier does not seem to have devoted himself in particular to any one branch of science. But about the year 1770 the announcement of the existence of more than one species of gaseous matter, arising out of the successive researches of Black, Scheele, Priestley, and Cavendish, had the effect of fixing his attention to the subject of pneumatic chemistry. The invaluable discoveries just alluded to had opened a new world to the inquirer into nature; and the labours of those distinguished experimentalists had conspired to commence a fresh era in science. Lavoisier was one of the first to appreciate at once the importance of the results they had arrived at, and the immense field of further research to which those results had opened the way. He perceived by a sort of instinct the glorious career which lay before him; and the influence which this new science thus, as it were, created, must have over every sort of physical research. Priestley possessed precisely those qualifications which are most available for striking out new and brilliant discoveries of facts ; a boundless fertility of invention; a power of rapidly seizing remote analogies; and an equal readiness in framing and in abandoning hypotheses, which have no value, but as guides to experiment. Lavoisier, less eminent in these respects, possessed in a more peculiar degree the mental characteristics which enable their owner to advance to grand generalizations and philosophical theories upon the sure basis of facts.

He possessed, in its fullest sense, the true spirit of inductive caution, and even geometrical rigour; and his observations, eminently precise and luminous, always pointed to more general views.
In 1774, he published his Opuscules Chimiques,' in which, after a full and truly philosophical examination of the labours of preceding experimenters in the discovery of the gases and their characteristic properties, he proceeds to describe his own beautiful and fundamentally important researches, from which resulted the True Theory of Combustion,' which may be termed the very sun and centre of the whole modern system of chemistry.

To the vague dreams of the alchemist had succeeded the remarkable theory of Hooke, who maintained that a certain ingredient of the atmospheric. air (which also enters as an ingredient into several other bodies, especially nitre) was the solvent which absorbed a portion of the combustible. This process was continued in proportion as more of the solvent was supplied. The solution took place with such rapidity, as to occasion those motions or pulsations in which Hooke believed heat and light to consist.

This near approach to the truth was thrown into discredit by the more brilliant and imposing theory of Stahl, who captivated the imaginations of chemists by his doctrine of phlogiston, the principle or element of fire, a sort of metaphysical something, which conferred the property of being combustible. Stahl taught that the process of combustion deprived bodies of their phlogiston, which, in the act of separation, exhibited its latent energies in the evolution of light and heat.

This wild chimera long maintained its ground, and received successive modifications in the hands of several distinguished chemists, the most important of which was that of Kirwan; but these all retained the fundamental error that something was abstracted from the burning body. Yet Rey, so early as 1630, and Bayer afterwards, had both shown that metals by calcination increase in weight, or have something added to them. Lavoisier turned his attention to the defects of the existing theory about 1770; and the last-named experiments probably directed him more specifically to the essential point of the inquiry. He pursued his researches with unwearied industry; and by a long series of experiments of the most laborious and precise nature, he succeeded in determining that, in all cases of combustion, that substance which is the real combustible invariably receives an addition, or enters into a new combination ; and the matter with which it combines is in all cases that same substance which had now been shown by Priestley to be one of the constituents of the atmosphere, and which was then known by the name of vital air.

It was however long before Lavoisier gained a single convert. At length M. Berthollet, at a meeting of the Academy in 1785, publicly renounced the old opinions and declared himself a convert. Fourcroy followed his example. In 1787, Morveau, during a visit to Paris, became convinced, and declared the conclusions of Lavoisier irresistible. The younger chemists speedily embraced the new views; and their establishment was thus complete. There only remained some lurking prejudices in England, where the Essay of Kirwan retained its credit. Lavoisier and his coadjutors translated this essay into French, accompanying each section by a refutation. So completely was this done, that the author himself was convinced; and, with that candour which distinguishes superior minds, gave up his views as untenable, and declared himself a convert.

These discoveries introduced Lavoisier to the notice of the most eminent persons in the State; and in 1776, Turgot engaged him to superintend the manufacture of gunpowder for the Government. He introduced many valuable improvements in the process, and many judicious reforms into the establishment.
In 1778, Lavoisier having been incessantly engaged on the subject of gases and combustion, announced another great discovery, " that the respirable portion of the atmosphere is the constituent principle of acids," which he therefore denominated oxygen.

The question as to " the acidifying principle " had long formed the subject of discussion. The prevalent theory was that of Beecher with various modifications, which made the acid principle a compound of earth and water regarded as elements. Lavoisier found in the instance of a great number of the acids, that they consisted of a combustible principle united with oxygen. He showed this both analytically and synthetically, and hence proceeded to the conclusion that oxygen is the acidifying principle in all. acids. Berthollet opposed this doctrine, and contended that, in general, acidity depended on the manner and proportion in which the constituents are combined. The fact is, that, in this instance, Lavoisier had advanced a little too rapidly to his conclusion. Had he contented himself with stating it as applying to a great number of acids, it would have been strictly true ; but lie had certainly no proof of its being universally the case. When Sir H. Davy, some years after, showed that one of the most powerful acids (the muriatic) does not contain a single particle of oxygen, and when the researches of Guy Lussac and others had exhibited other proofs of the same thing, it became evident that Lavoisier's assertion required considerable modification. And though nearly all acids have been since included under the general law of containing some supporter of combustion, yet there appear to be exceptions even to this ; the cautious language of Berthollet has been completely justified; and a perfect theory of acidity is perhaps yet wanting. Nevertheless, Lavoisier's discovery is one of first-rate magnitude and importance, and with this qualification, certainly forms the basis of all our present knowledge of the subject.

Another important research in which Lavoisier engaged, in conjunction with Laplace, was the determination of the specific heats of bodies, by means of an ingenious apparatus, which they denominated the calorimeter : these were by far the most precise experiments on the subject which had as yet been made, though some inaccuracies in the Method have since been pointed out.

Lavoisier owed much, it must be owned, to those external advantages of fortune, the absence of which, though it cannot confine the flights of real genius, yet may seriously impair the value and efficiency of its exertions; and the presence of which, though it cannot confer the powers of intellect, may yet afford most invaluable aids to the prosecution of research, and the dissemination of knowledge. In the instance before us, these advantages were enjoyed to the full extent, and turned to the best use. Lavoisier was enabled to command the most unlimited resources of instrumental aid ; he pursued his researches in a laboratory furnished with the most costly apparatus, and was able to put every suggestion to the test of experiment, by the assistance of the most skilful artists, and instruments of the most perfect construction.
But as he could thus command these essential advantages for the prosecution of his own investigations, he was equally mindful of the extension of similar advantages to others : he always evinced himself ready to assist the inquiries of those who had not the same means at their disposal ; and was no less liberal in aiding them by his stores of information and able advice. Indeed no one could be more sensible how much there is of mutual advantage in such intercourse between those engaged in the same scientific labours ; and this conviction, joined with a full perception of the immense benefits accruing from personal acquaintance among men of kindred pursuits, and the interchange of social good offices, led him to the regular practice of opening his house on two evenings in every week, for an .assembly of all the scientific men of the French capital ; which very soon became a point of general resort and reunion to the philosophers of Europe.

At these meetings general discourse and philosophic discussion were agreeably intermingled; the opinions of the most eminent philosophers were freely canvassed ; the most striking and novel passages in the publications of foreign countries were made known, recited, and animadverted upon; and the progress of experiment was assisted by candid comments and comparison with theory. In these assemblies might be found, mingling in instructive and delightful conversation, all those whose names made the last century memorable in the annals of science. Priestley, Fontana, Landriani, Watt, Bolton, and Ingenhouz, were associated with Laplace, Lagrange, Borda, Cousin, Monge, Morveau, and Berthollet. There was also an incalculable advantage in bringing into communication and intimacy men engaged in distinct branches of science : the intercourse of the mathematician with the geologist, of the astronomer with the chemist, of the computer with the experimenter, and of the artist with the theorist, could not fail to be of mutual advantage. In no instance were the beneficial effects of such intercourse more strikingly displayed than in the chemical sciences ; which, from this sort of comparison of ideas and methods, began now to assume a character of exactness from an infusion of the spirit of geometry ; and a department hitherto abandoned to the wildest speculations, and encumbered with the most vague and undefined phraseology (derived from the jargon of the alchemists), began to assume something like arrangement and method in its ideas, and precision and order in its nomenclature. This influence was strongly marked in the physical memoirs produced in France from this period downwards. The precision and severity of style, and the philosophical method of the mathematicians, was insensibly transfused into the papers of the physical and chemical philosophers.

Lavoisier individually profited greatly by the sources of improvement and information thus opened. Whenever any new result presented itself to him, which, perhaps, from contradicting all received theories, seemed paradoxical, or at variance with all principles hitherto recognised, it was fully laid before these select assemblies of philosophers ; the experiment was exhibited in their presence, and they were invited with the utmost candour to offer their criticisms and objections. In perfect reliance on the mutual spirit of candour, they were not backward in urging whatever difficulties occurred to them, and the truth thus elicited acquired a firmness and stability in its public reception proportioned to the severity of the test it had undergone. Lavoisier seldom announced any discovery until it had passed this ordeal.

At length he combined his philosophical views into a connected system, which he published in 1789, under the title of Elements of Chemistry :' a beautiful model of scientific composition, clear and logical in its arrangement, perspicuous and even elegant in its style and manner. These perfections are rarely to be found in elementary works written by original discoverers. The genius which qualifies a man for enlarging the boundaries of science by his own inventions and researches is of a very different class from that which confers the ability to elucidate, in a simple and systematic course, the order and connexion of elementary truths. But in Lavoisier these different species of talent were most happily blended. He not only added profound truths to science, but succeeded in adapting them to the apprehension of students, and was able to render them attractive by his eloquence.

In 1791 he entered upon extensive researches, having for their object the application of pneumatic chemistry to the advancement of medicine, in reference to the process of respiration. With this view he examined in great detail the changes which the air undergoes, and the products generated in that process of the animal economy. He had previously, however, as far back as 17-0, detailed a series of experiments to determine the quantity of oxygen consumed and carbonic acid generated by respiration, in a given time, in the Memoirs of the French Academy.

In the twenty volumes of the Academy of Sciences, from 1772 to 1793, are not less than forty memoirs by Lavoisier, replete with all the grand phenomena of the science :—the doctrine of combustion in all its bearings ; the nature and analysis of atmospheric air ; the generation and combinations of elastic fluids ; the properties of heat ; the composition of acids ; the decomposition and recomposition of water ; the solutions of metals ; and the phenomena of vegetation, fermentation, and animalization. These are some of the most important subjects of his papers ; and during the whole of this period he advanced steadily in the course which was pointed out to him by the unerring rules of inductive inquiry, to which his original genius supplied the commentary. So well did he secure every point of the results to which he ascended, that he never made a false step. It was only in one subject, before alluded to, that he may be said to have gone a few steps too far. Nor did he ever suffer himself to be discouraged, or his ardour to be damped by the difficulties and obstacles which perpetually impeded his progress.  He traced new paths for investigation, and founded a new school of science; and his successors had ample employment in following out the inquiries which he had indicated, and exploring those recesses to which he had opened the way.
In the relations of social and civil life Lavoisier was exemplary ; and he rendered essential service to the state in several capacities. He was treasurer to the Academy, and introduced economy and order into its finances : he was also a member of the board of consultation, and took an active share in its business. When the new system of measures was in agitation, and it was proposed to determine a degree of the meridian, he made accurate experiments on the dilatation of metals, in conjunction with Laplace (1782), to ascertain the corrections due to changes of temperature in the substances used as measuring rods in those delicate operations.

By the National Convention he was consulted on the means of improving the manufacture of assignats, and of increasing the difficulty of forgery. He turned his attention to matters of rural economy, and, by improved methods of cultivation, on scientific principles, he increased the produce of an experimental farm nearly one half. In 1791 he was invited by the Constituent Assembly to digest a plan for simplifying the collection of taxes the excellent memoir which he produced on this subject was printed under the title of The Territorial Riches of France.' He was likewise appointed a Commissioner of the National Treasury, in which he effected some beneficial reforms.

During the terrors of Robespierre's tyranny, Lavoisier remarked that he foresaw he should be stripped of all his property, and accordingly would prepare to enter the profession of an apothecary, by which he should be able to gain a livelihood. But the ignorant and brutal ruffians who were then in power had already condemned him to the scaffold, on which he was executed, May 8, 1794, for the pretended-crime of having adulterated snuff with ingredients destructive to the health of the citizens ! On being seized, he entreated at least to be allowed time to finish some experiments in which he was engaged ; but the reply of Coffinhall, the president of the gang who condemned him, was characteristic of the savage ignorance of those monsters in human form :—" The Republic does not want savans or chemists, and the course of justice cannot be suspended.".

Lavoisier in person was tall and graceful, and of lively manners and appearance. He was mild, sociable, and obliging ; and in his habits unaffectedly plain and simple. He was liberal in pecuniary assistance to those in need of it ; and his hatred of all ostentation in doing good probably concealed greatly the real amount of his beneficence. He married, in 1771, Marie-Anni-Pierrette Paulze, a lady of great talents and accomplishments, who after his death became the wife of Count Rumford.