definite proportions, by weight, and produce Five compounds, as shown in the following statement:

I. Oxygen, 3640+Nitrogen, 6360=10000 Nitrous oxide. II. Oxygen, 5333+Nitrogen, 4667=10000 Nitric oxide. III. Oxygen, 6320+Nitrogen, 3680=10000 Hyponitrous acid. IV. Oxygen, 6960+Nitrogen, 3040=10000 Nitrous acid. V. Oxygen, 7410+Nitrogen, 2590=10000 Nitric acid.

I. Is an invisible vapour, called Nitrous oxide, to denote that it is not acid.

II. Is an invisible gas, called Nitric oxide, to denote that it is not acid; and by the termination ic, that it contains more oxygen than the former. III. Is an acid liquid, called Hyponitrous acid, to denote that it is intermediate with Nitric oxide and Nitrous acid, and below the latter in its proportion of oxygen.

IV. Is an acid vapour called Nitrous acid, to denote that it contains less oxygen than Nitric acid. V. Is called Nitric acid, to denote its large amount of oxygen; the chemist has not determined if nitric acid be solid, liquid, gas, or vapour, but he is certain of its composition.

These five compounds are deadly poisons to animated beings, and yet they contain the elements of Air, which is the pabulum of life,-how can this be? The chemist replies, that to constitute Air, these elements are not combined, they are only mixed, and very nearly in the following weights :—

Oxygen, 2300+ Nitrogen, 7700 = 10000 Air.

These elements are rendered incapable of combining under all ordinary circumstances, they remain intimately and uniformly mixed to constitute the first, and the last food of life.

But when the lightning goes forth, as the terrible display of natural electricity in the thunder-storm, the chemist discovers that the elements of the air in the immediate passage of the flash, are suddenly excited to combine and produce the poison, called nitric acid; but this effect is miraculously restrained by the Hand of Providence, and not permitted to ensue throughout the entire volume of the air, or inevitable would be the destruction of every living thing; and the relatively minute portion of poison thus formed during a long protracted discharge of lightning, is soon infinitesimally diffused throughout the untainted volume of air, or absorbed by the waters, or neutralized by the earth, and thus deprived of virulence.

The animated creation is thus miraculously preserved amidst the elements of destruction; true indeed is the solemn warning, that" in the midst of life we are in death."

These extraordinary elements, Oxygen and Nitrogen, form the chief volume of the Atmosphere during all the vicissitudes of the Four Seasons; but a rigid analysis likewise proves the simultaneous existence of small quantities of two compounds, named Carbonic acid, and Water. Reference has been made to the com

position of Carbonic acid, and when obtained from the air or other sources, in a pure or insulated state, it is fatal to animal and vegetable life, and is materially heavier than either Oxygen or Nitrogen; but as mingled with these elements, and the vapour of water, to constitute Air, it has a beneficial influence, and never subsides as a distinct mephitic stratum.

The chemist discovers that Water is a compound of Oxygen and Hydrogen, an elementary gas thus named in allusion to its producing that substance; the following are the weights in which these elements combine :

Oxygen, 8890 + Hydrogen, 111010000 Water.

It does not exist in the mixture of Oxygen, Nitrogen, and Carbonic acid, as Liquid water, but as Vapour of water, produced by the all-prevailing agency of solar heat; thus it is wafted over the surface of the globe, until local changes of temperature cause its condensation, and fall, as rain or snow, and other wellknown forms, according to the season.

The result obtained by a minute analysis of Air, presents the following weights of its elementary and compound constituents.

This wondrous medium, or atmosphere, containing the elements of life and of destruction, enfolds the earth, as a mantle; and although the chemist cannot experimentally determine its limit, he can determine its total weight, and is perfectly astounded at its immensity; it is expressed by the sum of Five quatrillions, two hundred and eighty-seven trillions, three hundred and fifty billions of TONS!

The accompanying statement will show the relative proportions by weight, in which the elementary and compound constituents of Air are blended, to produce this gigantic sum total.

Both the chemist and the physiologist concur in stating, from the results of numerous experiments, that no elementary gas, no compound gas, no elementary vapour, no compound vapour, no other mixture or combination of elementary or compound gases, or of elementary or compound vapours, can support the respiratory functions of the animated creation, like Atmospheric air; and its ultimate analysis presents Four elements, namely, Oxygen, Nitrogen, Carbon, and Hydrogen.

Water is presented throughout nature in lavish abundance, it occupies more than three-fourths of the superfices of the globe; but philosophers cannot determine the total weight of this enormous bulk of water, as they can that of the atmosphere.

The chemist discovers that water, as it falls from the clouds, invariably contains air, and sometimes a compound of hydrogen and nitrogen, called ammonia, to which much of its fertilizing power may be referred: he further discovers that the water of springs, brooks, and rivers, always contains portions of earthy and saline compounds, particularly common-salt, although not sufficient to destroy its freshness, and unfit it for the beverage of man and animals.

The chemist discovers, that the water of springs in certain localities, is so impregnated with gaseous, earthy, and metallic compounds, as to be unfit for constant use as a beverage, yet occasionally taken, it exerts considerable influence in palliating or removing some forms of disease; and pursuing his investigations regarding the water of the ocean, which, when drank, soon causes delirium and death, he discovers it to derive its strong saline taste from a proportion of common-salt, far exceeding that in ordinary spring brook, or river water; and its bitter taste, from an inferior proportion of compounds of lime and magnesia.

But during all experiments and researches upon water, the chemist cannot find a solitary instance of its occurring, in nature absolutely pure, or solely