LAVOISIER.

In the Lives of Black, Priestley, Watt, and Cavendish, it has been necessary to mention the claims of Lavoisier, first as a competitor with the great philosophers of the age for the honour of their discoveries, yet as an intruder among them by his attempts to show that he had himself, though unknown to them and ignorant of their inquiries, made the same steps nearly at the same time. The history of that great man, which we are now to consider, will enable us to perceive clearly the evidence upon which the charge rests, both the proof of his having preferred those claims, and the proof that they were groundless. But it will also enable us to perceive how vast his real merits were, and how much remained his own of the discoveries which have built up the science of modern chemistry, even after all those plumes have been stript away that belonged to others.

It is a very great error to suppose that the truths of philosophy are alone important to be learnt by its students; that provided these truths are taught, it signifies little when or by whom or by what steps they were discovered. The history of science, of the stages by which its advances have been made, of the relative merits by which each of our teachers was successively made famous, is of an importance far beyond its being subservient to the gratification even of an enlightened and learned curiosity. It is eminently calculated to further the progress which it records; it conveys peculiarly clear and discriminating ideas upon the doctrines taught, and the proofs they rest on; suggests new inquiries, and encourages the prosecuting of new researches. It is, moreover, both a debt of gratitude to our benefactors which we should be anxious to pay by testifying our gratitude, and commemorating their fame; and the discharge of this duty has a direct tendency to excite emulation, prompting to further labours that may enlarge the bounds of science. Besides, the history of scientific achievements is the history of the human mind in its noblest exertions, of the human race in its most exalted pursuits. But it is equally clear that the whole value of this, as of every other branch of history, depends upon the diligence with which the facts are examined, the care and even the skill with which their evidence is sifted, the impartiality with which judgment is pronounced, and the accuracy with which the record is finally made up. The mere panegyric of eminent men, how elegantly soever it may be composed, must remain wholly worthless, at the best, and is capable of being mischievous, if it aims at praise without due discrimination, still more if it awards to one man the eulogy which belongs to another. Nothing can be more indispensable to the execution

of the important task undertaken by the historian of science, than that he should most carefully examine the share which each of its cultivators had in the successive changes it has undergone. The greatest of these have ever felt how valuable such titles are, and have shown the most singular anxiety to compare and to adjust their relative claims. Of these illustrious men I have known two, Black and Watt, and I can safely say that when the question was raised of priority in discovery among either their predecessors or their cotemporaries, they were wont to be particular and minute, even to what seemed superfluous carefulness, in assigning to each his just share, very far more anxious in making this distribution than they ever showed themselves to secure the admission of their titles in their own case. By a singular injustice of fortune these two philosophers have been treated themselves with a more scanty measure of the like justice than perhaps any of their cotemporary discoverers.* It is proposed to examine with the same minuteness the particulars in M. Lavoisier's history, upon which some controversy has at different times arisen.

Antoine Laurent Lavoisier was born at Paris, 13th of August, 1743, the son of an opulent family, his father having been a fermiergénéral. No expense was spared upon his education; and in the college of Mazarin, where he studied, he gained many prizes for proficiency in classical acquirements. It was, however, to the sciences that he soon devoted himself, and first to the severer ones, having made considerable proficiency in the mathematics and astronomy under La Caille, in whose observatory he studied upon leaving the college. He studied botany under Jussieu, and chemistry under Rouelle. As from his earliest years he appears to have been wholly consecrated to scientific pursuits, so no one ever entered upon his course with a more fervid courage. The earliest of his inquiries of which we have any knowledge was an analysis of gypsum, presented to the Academy of Sciences in 1765, and published in the collection of " Mémoires de divers Savans," 1768. In 1764 a prize had been proposed by M. de Sartine, the celebrated chief of the police of Paris, for the best method of lighting a great town, so as to combine illumination with economy, and with facility of service. After the lapse of twelve months no dissertation had been presented which satisfied the conditions of the programme, and the prize was doubled, being raised to 2000 livres; and next year, 1766, the conditions remaining still unsatisfied by the candidates, the prize was divided among the three best, while a Memoir of great merit, by M. Lavoisier, was honourably mentioned and ordered to be printed. The King, too, on M. de Sartine's recommendation, directed a gold medal to be bestowed upon the author, who was presented with it at the public sitting of the Academy in April, 1766. In 1769 he obtained the place of a fermier-général, by a kind of hereditary title;

* When any reference is made to the Eloges of the French Academy, justice requires me to add that those of M. Arago form a most striking exception. They are strictly historical, as well as philosophical. That of Watt is a model.

and in 1771 he married Marie-Anne Paulze, whose father likewise belonged to the same financial class. In 1768 he had been admitted a member of the Academy, at the early age of twenty-five. His paper on the lapis specularis, related to the composition of the great strata forming the basin of Paris.

He appears for some years to have occupied himself principally with geological inquiries; he made mineralogical journeys in various parts of France in company with M. Guettard; and he had collected materials for an extensive work on the revolutions of the globe, when the recent progress of another science gave a new direction to his pursuits. His paper on gypsum contains a number of experiments, which show it to be a neutral salt, soluble in a great proportion of water, and composed of sulphuric acid united to a calcareous base. This and almost every other part of his paper was well known before. M. Montigny had, in the " Memoirs of the Academy," 1762, shown its solubility, and M. Margraaf, in the "Berlin Memoirs," as far back as 1750, had proved both this and its composition. M. Lavoisier refers to these long-published works in a note appended to his paper, but states that he had not seen Margraaff's till after his own was read before the Academy. He also states that M. Baume had published researches similar to his in a journal, but that he was not aware of this till he had made considerable progress with his paper. It is unfortunate that this eminent person should have begun his works with this kind of doubt hanging over his originality. Yet we may observe that his paper contains an ingenious theory, explaining the phenomenon of the formation of gypsum on the principles of ordinary crystallization; and that he has also ascertained the proportion of water required for its solution more accurately than had before been done; that he gave a systematic view of the whole subject. Qualis ab incepto processerat-It is remarkable that all the distinguishing characters of his inquiries in after times should be found to mark this his first production. We observe the same disputed originality in his experiments, the same anticipation of his discoveries by former inquirers, the same superiority of his processes in point of accurate admeasurement, the same inferiority of his experiments to his reasons, the same happy generalization of facts observed by others, the same turn for throwing doctrines and discoveries not his own into one combined system.

The discoveries of Black had, long before M. Lavoisier entered upon his scientific pursuits, directed the attention of philosophers to the important subject of gaseous bodies, to their production by the absorption of heat, and to the combinations into which they enter with other substances, so as to alter the nature of these. The great doctrines of causticity and of latent heat, with the existence of fixed air, and its evolution in respiration, fermentation, and combustion, had been established, and had formed a new era in chemical science. Fixed air was discovered in 1754; latent heat before 1763. Mr. Cavendish had prosecuted these inquiries with success; he had examined some of the properties both of fixed air and of hydrogen; had determined their specific gravities, and had shown that they

are always the same from whatever substances they may be obtained. His experiments were published in 1766. Soon after this time Dr. Priestley began his brilliant course of discovery. A new scene had been opened to philosophers; they were like infants gazing on the material world, every object of which is new to them, and whose whole existence is one continued gratification of curiosity. Aware from former discoveries that various kinds of air, each having its peculiar properties, exist in nature, he was of course ever expecting to meet with them; and, accordingly, he soon found that the air of the atmosphere yields one of these, which on a false theory he termed phlogisticated, but which others have termed azote, being incapable of supporting either animal life or flame. These experiments of his were published in 1772.

Before proceeding further with the history of chemical discovery, it is necessary I should mention a serious inconvenience thrown in the way of the accurate inquirer by the very extraordinary manner in which the "Memoirs of the French Academy" have always been published. The "Philosophical Transactions" appear most carefully in two, sometimes, though very rarely, in three parts every year, and all the papers published each year have been read before the Society during the course of that year; nay, all the papers which form each part have been read during the half-year immediately preceding the publication of that part. It is far otherwise with the French Academy's “Memoirs;" these never are published in less than three, sometimes even four years after the year to which they nominally relate. Thus the volume of 1772 consists of two parts, one of which was published in 1775, and the other in 1776. But this would occasion a small inconvenience to the inquirer into dates and facts, if it only indicated that the work was constantly in arrear, and that the papers purporting to be those of any given year, as 1772, were not published till three or four years later. That, however, is by no means the case. It continually happens that the papers classed as those of one year were in reality read a year or two later. In earlier periods the dates are often not given at which papers were read, but from internal evidence we find when they were read; for in the volume of 1772, p. 12, we have M. Lavoisier quoting a book published in January, 1773, and describing an experiment made in August of that year, (p. 598). So in the volume for 1770, we have an account of an eclipse in April, 1771, and of experiments made in autumn, 1771, (p. 621). In later volumes the dates are more accurately given, though sometimes they tend to bewilder us. Thus the volume for

1776 was not published till 1778, and it contains a paper of M. Lavoisier, printed in Sept. 1778, and read 23d Nov. 1779. So the volume for 1776 contains a paper of his, stated to have been printed in Dec. 1777. In like manner the volume for 1774 was published in 1778, and it contains a paper read 1774, but relû 1777. And the volume for 1775 has a paper read Easter, 1775, relû Aug. 1778. It is needless to remark how very difficult this kind of confusion and inaccuracy, wholly unaccountable, renders it to ascertain the precise date at which any experiment was made, or theory

formed. We are in most cases left to mere conjecture, being uncertain of any thing but the time of publication, and not always sure

of that.

In the year 1768 M. Lavoisier began to occupy himself almost exclusively with chemical inquiries. Well educated in the kindred branches of natural philosophy, and fully conversant with all that was then known of chemistry, ardent in the pursuit of scientific truth, filled with a noble ambition to distinguish himself among its students, careless of the various pursuits which men in his circumstances find all-engrossing, he was also in possession of ample wealth, and could both command the aid of some and obtain the fellowship of others in his researches, while the most costly apparatus, and the most expensive experiments, were at all times within his reach. He soon filled his house with the finest instruments, and opened it freely to all men of letters and of science. In their company, and with the inestimable advantage of their constant society, in which every point was discussed and all difficulties encountered by their lights as well as his own, he devoted the rest of his praiseworthy life to his favourite science, repeating the experiments of others, varying them with the suggestions of his own mind, and, in some instances, devising new ones which he successfully conducted. We are now to consider the fruits of these glorious labours.

In 1768 and 1769 he made a number of very laborious and very accurate experiments, with a view of ascertaining the correctness of an opinion long entertained, and among others by Bonde and Margraaff, that water may, by repeated distillations, be converted into earth; and also of determining whether or not there was any foundation for the opinion that water can, by repeated distillations, become so elastic and aeriform as to escape through the pores of vessels: an opinion entertained by Stahl, the celebrated author of the phlogistic theory. M. Lavoisier satisfactorily disproved both these positions, and showed that the earth which had misled others was a portion of the vessels: used in performing the distillation. The account of these experiments was given to the Academy in 1770, and published in 1773. It may give us some idea of the pains with which these experiments were performed, to state that one of them lasted a hundred and one days.

In the year after these inquiries were carried on, his attention appears to have been turned aside from chemical studies, by the reports which he made to the Academy upon the means of supplying Paris with water, at an economical rate. A question having arisen between the Government and M. Parcieux, a learned mechanical projector, on the comparative expense of bringing the water of the rivulet Yvette by canal and wheel engines, or by steam engine, M. Lavoisier examined the subject, and showed that the latter mode was the most expensive. His Memoir appeared in the volume for 1771. In that year, however, he resumed his chemical pursuits, and applied himself to the attentive consideration of the calcination of metals. The recent discoveries on the nature of gases by Black, Cavendish, and Priestley, appear to have chiefly