in all bodies and the different proportions according to which these two kinds of substances unite, viz., combustible and incombustible, give rise to all the varieties of combustible bodies. Subsequently in 1720, the celebrated Stahl took up this theory, and invented the term phlogiston, as designatory of this combustible constituent of all things. This theory was so ably and extensively confirmed by experiments, and so clearly and forcibly explained by Stahl, that his name became identical therewith, and in course of time was historically distinguished by its being styled the Stahlian theory. It subsequently formed the groundwork of Dr. Black's theory of latent heat. The means was now provided in the form of an hypothesis for accounting for all the phenomena of calcination and combustion. Hooke, in his Micrographia (1671), obscurely conjectured the existence of nitrous particles existing in though not a constituent of atmospheric air. Mayow had not only held this conjecture, but had more fully developed it in 1669, and was followed by Willis in the same direction in 1671. Boyle came next into the field of inquiry; and in his celebrated work against the Peripatetics and Iatro-chemists, entitled Sceptical Chemist, published in 1661, he introduced for the first time something worthy of being called systematic investigation. And it would appear both from this and a subsequent treatise, that he approximated nearest to the conception, though he fell short of it, that a constituent of atmospheric air was necessary to combustion.

We now come to Boerhaave, whose discoveries, and the experiments of Fahrenheit regulated by him, gave to the world in 1732 the invaluable doctrine of specific degrees of heat; so usefully employed at a subsequent date, along with the phlogistic theory of combustion of Stahl and Becher, by Dr. Black, in developing his doctrine of latent heat, which we shall take into consideration in a subsequent paper. Hales of Menninge, the celebrated chemist and vegetable physiologist, was the first who saw the fire-feeding element oxygen evolved in the form of gas; this was in 1727, but he had no knowledge of its nature, origin, or value. So long did the ancient belief in the myth of phlogiston, or of the "celestial fiery matter" whose presence or absence produced all the changes which bodies undergo, check all progress in our knowledge of pneumatic chemistry, that it was not until 1766 that Black and Cavendish dispelled all doubt respecting the composite nature of atmospheric air: hitherto chemists had believed in its elemental simplicity. One of the discoveries of Black, which obtained him an European reputation, was that of fixed air or carbonic acid gas.

* "Imperfections of the Chemical Doctrine of Qualities."

Cavendish, in 1766, set up a partial claim to this discovery in a paper entitled "Experiments on Fictitious Air;" but as we have already seen, this gaseous substance had previously been discovered by Von Helmont, and designated gas sylvestre. This substance is now known to be mechanically mixed with the atmosphere. Cavendish was the first to show that there exist two species of air quite different in their properties from ordinary atmospheric air; these he distinguished by naming them inflammable air and fixed air. He was the first to collect and ascertain the nature of different kinds of air, and to determine their specific gravity: and it is remarkable, that in his paper he determines the peculiar nature of the two important gases above alluded to, hydrogen and carbonic. The actual discovery of the twofold nature of atmospheric air, as consisting of oxygen and nitrogen, was reserved for Priestly in 1772-4,* Scheele in 1774-5, Lavoisier and Trudaine in 1775, Cavendish in 1784-5, and for Dumas and Boussingault in our own time; the latter of whom have presented the world with a demonstration of its compound nature by a most refined analysis of its constituents. Cavendish appears to have the merit of first discovering the exact proportion of the constituents of air in the popular sense of oxygen being one-fifth.

This brief history of the first conjectures and discoveries in pneumatic chemistry, will eventually enable the reader to perceive that we institute no imaginary claim for Swedenborg when we affirm, that to him belongs the indisputable merit of presenting the first conjecture as well as the first exposition of the compound nature of atmospheric air; yea more, that to him belongs the merit of presenting a theoretical statement, involving the whole of the fundamental facts having reference to the number, proportion, and chemical character of its constituents. For him, therefore, we claim the important theoretical discovery, and the first published compendious announcement of the following fundamental facts:

FUNDAMENTAL FACTS.

1. That pure and dry atmospheric air is a compound of two constituents.

2. These constituents are combined in unequal proportions.

3. The proportions are various in different localities, and under different circumstances.

4. The element least in quantity is the active agent of combustion. 5. The element greatest in quantity is an extinguisher of combustion.

* "The Doctrine of Phlogiston established," 1800, p. 43.

6. The element least in quantity is a constituent of both air and water. These facts evidently form a compendium of all our present knowledge relative to the number, and to the composite and chemical character, of atmospheric air: and hence we presume, that when our confirmations shall have been presented, the historical relations to which we have referred will justify the claim we have instituted in favor of Swedenborg.

Once for all; we trust no nervous fears will possess our friends at the extraordinary statements we feel it both our pleasure and duty to make, kindly anxious as the admirers of this great genius must be, lest we should exceed the legitimate bounds of proof; for we can assure them, that whilst we shall invariably base our statements upon admitted facts and dates, and thereby avoid all chance of error and confutation, yet we shall respectfully but fearlessly state the scientific claims of this distinguished Christian philosopher; and shall not cease, with God's blessing, until the full measure of these claims on the human family shall be publicly known, if not admitted. Indeed, we are sincerely desirous of avoiding any exaggeration on the score of these claims; and hence we both have and shall prefer those only which rest upon admitted facts and dates. What, then, are the proofs of this remarkable case of theoretical foresight into the composite and chemical character of atmospheric air?

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Proof of the above Fundamental Facts.

1st.-That pure and dry atmospheric air is a compound of two elements. The chemical analysis of the atmosphere, and the relative quantities of substances forming its constituents, have been the object of a very diligent and elaborate series of investigations; it is only very recently, however, that the admirable labours of Dumas and Boussingault have by new and more accurate methods determined the chemical analysis to a degree of perfection hitherto unparalleled.* By this refined analysis, a volume of pure and dry atmospheric air is determined to consist of two permanently elastic fluids, transparent, colourless, tasteless, and inodorous. These two substances have obtained the inappropriate names of oxygen and nitrogen. Liebig, in his important work, (Organic Chemistry, &c., s. 62-72, 1840.) has presented us with sufficient evidence of the existence of ammoniacal vapors commixed therewith; and the fact has since been confirmed by Boussingault and others. This last-named physicist and Lewy have shown, from their * Researches into the composition of the atmosphere," in the Annals of Chemistry and of Physics, t. 57, 1834, pp. 171-3; and t. 71, 1839, p. 116.

experiments at Audilly, that an almost imperceptible amount (between 0.00028 and 0.00031 in volume) of carbonic acid gas, and a still minuter quantity of carburetted hydrogen gas, are also to be found in the atmosphere.* With the exception, however, of oxygen and nitrogen, all these substances are merely mechanically present in the atmosphere, and are not to be regarded as constituents thereof, or as elements in its chemical composition. So far we have the testimony of science at the present day.

Now let the reader carry his attention so far back as the year 1734, when not even a conjecture had been hazarded of the composite nature of the air we breathe, as may be seen from the historical summary given in this article. In that year, the scientific world had its attention drawn towards an eminent philosopher in the north, Emanuel Swedenborg; who, like the mysterious northern lights of his own country, now appeared on the intellectual horizon, sending forth his luminous thoughts towards every point of this vast universe, radiant with a new and unparalleled brilliancy, illuminating the world of thought with a higher and more intense light, and thereby presenting an hitherto inaccessible and unexplored region to view, in such a manner and with such accessories, as to render it for ever a subject of strict and systematic investigation. In that year Swedenborg presented a compendium of his luminous thoughts in a work which, for deep philosophical insight, and a rich treasure of profound and enlarged observations of the laws and phenomena of the universe, is as yet unsurpassed. In this work, appropriately designated the Principia, we have a beautiful exposition of the elements of creation, and the composite nature of atmospheric air, water, and other substances. With regard to air, its twofold nature is illustrated by diagrams, whilst the descriptions are elaborately stated. In the chapter, On Air, vol. ii., he says :—

"Air consists superficially of fifth finites (or fifth kind of substances), and within it are enclosed the first and second elementaries." Page 304.

"The fifth finites have entered into the surface of the aërial particle, and the first and second elementaries into the internal space." Page 305.

The first and second elementaries unite and form a new substance in the interior of a particle of air, whilst the surface is formed of the fifth kind of substances. In order to exhibit his conception to the

* Many attempts have been made to estimate the weight of the whole atmosphere, but they vary considerably in their results. Professor Schmid has estimated, that one trillion of pounds of nitrogen, three hundred thousand billions of oxygen, and one thousand billions of carbonic acid gas, form the total contents of the atmosphere.

sight, Swedenborg submits the following figure, as a representation of this particle, accompanied with the following statement :

"The aerial particle may be represented by this picture. Thus in Fig. 107, we may see an aerial particle in its highest state of expansion. (C. C.) are fifth finites; (the spherules) are first and second elementaries extending from the centre to the surface." Page 310. [Unfortunately Fig. 108 has been obtained for Fig. 107.]