A bar of iron placed within the medium of fire suffers de-electrisation; then acquires medium of space, by which the bar is expanded. When taken from the fire, it acquires electric matter similar to that of which it had suffered loss, which displaces the expanding medium, and now becomes contracted by external pressure. The olden philosophy has no contracting cause, the imputed attraction having been destroyed by the imputed heat of the fire, as the same philosophy states of the imputed attraction of magnets being destroyed by the heat of fire, which leaves the bar to contract itself.
A piece of lead on the fire becomes de-electrised and expanded. The portion of medium of space it has acquired separates the atoms of the lead by which the state of solidity is subverted; it remains as one of the constituents of the lead, and is as a menstruum to the metal, and the atoms of the metal may be said to swim in it as the globules of blood in the serum. Further de-electrisation and additional increments of medium of space are productive of complete dispersion of the atoms of the metal, and of a kind of efflorescent result, which is a subsequent formation. The air in a corked bottle before the fire loses electric matter to the medium of fire; and by the medium of space which enters the vacated interstices, the cork is exploded. In the partially exhausted air-pump receiver, that decrease in the quantity of air should increase the expansive power of the remainder, and that the atoms should fly asunder with exploding force, is most unreasonable and impossible. The physical fact is, the more the air is reduced, the greater is the quantity of influent medium of space, consequently of expanding and exploding force. In the condensing of air, as is the expression, by the piston of the syringe, the quantity is reduced from being forced out through the pores of the syringe; and pressure on the bottom of the piston springs it up when the depressing power is removed. Under the general pressure the atoms of air must be in contact; and the volume being reduced, implies reduction of quantity: hard unalterable atoms are incompressible beyond contact; and as to their being elastic, it is physically impossible; medium of space being forced out and re-entering, is what makes the air be considered elastic. Let the syringe be worked under water, and the matter displaced appears escaping as air-bubbles, and as air-beads on the outside of the syringe.
OXYGEN AIR.
All airs are compounds. Medium of space is the most voluminous constituent of every aëriform body, which accounts for an air or gas and steam being of so much greater volume than that from which it had been obtained; steam has fifteen hundred times the volume of the water it was produced from.
Oxygen air is decomposed in converting it with hydrogen to water: there is no oxygen or hydrogen air in water; their elements are the constituents of water. Oxygen is decomposed by respiration; when inspired, it is not expired, but nitrogen, which must have been one of its constituents, and from there being nothing to constitute the expiration but the previous inspiration the proposition is proved.
The constituents of oxygen are—nitrogen, a highly rare imponderable element and medium of space. The first is the most ponderable element of nitrogen air; its atoms are the largest of all others of the elements of matter, and, it may be said, they constitute the substance of the framework of all ponderable or gross formations. Davy says, "the properties of nitrogen are altogether negative;" the same applies to every other kind of air, all being constituted of inert atomic substance, consequently of inactive essence; and all being alike in every respect but in the size of their atoms. The imponderable element being highly evanescent, is never found alone, and is always connected with nitrogen; hence simple nitrogen is obtainable only from bodies, or by deoxygenating atmospheric air. Atmospheric air is nitrogen, plus the imponderable element; and when the nitrogen is saturated with the same element, the air is oxygen: hence, whichever is inspired, nitrogen is expired.
From nitrogen being evolved copiously from water in vacuo, and from ice being convertible to nitrogen, according to Priestley, so is nitrogen a constituent of water, also of the gases into which water is decomposable; but as it cannot belong to the hydrogen, owing to its superior levity, it must to the oxygen; which is confirmation of the above, that nitrogen is a constituent of oxygen air or gas.