His analysis of atmospheric air and the re-combination of its elements, though not quite correct, was nevertheless ably conceived and executed. He heated some mercury in a mattress connected with a glass receiver with about fifty cubic inches of atmospheric air; he then found that a portion of the mercury was converted into small red particles, which did not increase after the heat had been continued for twelve days and he then observed that only about forty-two of the fifty cubic inches of atmospheric air remained unabsorbed, and this he found was no longer fit for respiration or combustion. On submitting tho red particles of mercury to heat, they were separated into mercury and about eight inches of gas, which eminently supported both respiration and combustion ; and having several times repeated the experiment, be mixed the residual unab sorbed portion of the air with that which was obtained by heating the red particles of mercury, and he found that air was reproduced precisely similar to that of the atmosphere, and possessing nearly the same power of supportiug respiration and combustion. Lavoisier admits that the experiment does not show the exact quantity of the two airs which constitute the atmosphere, for he states that the mercury will not separate the whole of the respirable portion, and consequently part of it remains "united to the mephitis." Lavoisier also mentions some experiments which he performed with this highly respirable air thus obtained by the intervention of mercury from the atmosphere, and he notices the brilliant effects of the coin bustiou of charcoal and phosphorus, and adds, " This species of air was discovered almost at the same time by Dr. Priestley, M. Scheele, and myself. Dr. Priestley gave it the name of dephlogisticated air; M. Scheele called it ' empyreal air ;' I at first named it ' highly respirable air,' to which has since been substituted the term of 'vital air. " It Is greatly to be regretted that so eminent a philosopher should so far have forgotten what was due both to others and himself as have made such a statement as this. It was one of the last ac of Dr. Priestley to publish, however unwillingly, that he first state to Lavoisier himself, at his own table in Paris, in the year 1774, tt fact of his having discovered this gas, in the presence of persons who he names. Nor indeed is this the only instance, to use a gent] expression, in which Lavoisier exhibited a want of candour unworth: not merely of a philosopher, but of a man. (See the 'Doctrine
Phlogiston established,' by Dr. Priestley, Northumberland, 1800.) In 1778 Lavoisier published a paper in the Memoirs of the Academi entitled 'General Considerations on the Nature of Acids, and on th principles of which they are composed.' In this paper it is attempts to be proved that all acids owe their properties to the presence c oxygen, and that when bodies were deprived of oxygen they lost thei acidity. This doctrine of the universal acidifying power of oxyge was generally adopted until Davy proved that what had been calla oxymnriatic acid had not been decomposed, and that with hydroge it formed muriatic acid; he first however distinctly proved that certai bodies, such as carbon and sulphur, were actually converted into acid by the union with oxygen ' • but by a too hasty generalisation he wa led to adopt principles which the further progress of science ha proved to be untrue.
It is to be observed that Lavoisier did not discover any one of th elementary gaseous fluids. Mr. Cavendish had clearly described th properties of hydrogen before he began his career; and oxygen, azote and chlorine were discovered, the two first in Britain and the last ii Sweden, after Lavoisier commenced his chemical researches. In on particular case he indeed denies the existence of a well-known fact namely, that gunpowder can be fired in vacuo; but then the fact i irreconcileable with his theory. The inquiries of Lavoisier, it must 1)1 added, had the principal share in introducing that reform in thl nomenclature of chemistry which ended in the expulsion of tie phlogiatic theory. "Lavoisier's character," as Brands has truly stated "has in some measure suffered by the misguided zeal of his admiring commentators, who, not satisfied with allowing him due merit for the logical precision and sagacity of induction which he brought into chemistry, have represented him as having the experimental activity of Priestley and the laborious diligence of Scheele. But Lavoisier though a great architect in the science, laboured but little in the quarry ; his materials were chiefly shaped to his hand, and his akil was displayed in their arrangement and combination."