depth, and the stratum above that height is pure air. But that it is poisonous to man, is evinced by the fate of persons who incautiously expose themselves to the vapours of charcoal burning in ill-ventilated apartments, or who venture into large vessels, in which fermentation had been conducted, as in breweries and distilleries. Many persons, from ignorance of the prevalence of this gas in the vicinity of limeworks, have lain down to repose, and in a short time have slept the sleep of death. As this gas is destructive to animal life, so it extinguishes flame. This can be strikingly shown by letting down a burning taper to the bottom of a glass jar, filling a bottle with carbonic-acid gas, and pouring it as if it were water into the jar, the flame is immediately extinguished. It is this gas which gives briskness and an agreeable pungency to fermented liquors, as porter and ale, and which appears on their surface in the form of a white froth. All kinds of spring and well water contain carbonic-acid, which they absorb from the atmosphere, and to which they are partly indebted for their agreeable flavour. Boiled water has an insipid taste from the absence of carbonic-acid.

The base of carbonic-acid gas is distinguished by the name carbon, which is nearly allied to charcoal. It exists largely in animal substances, and is extensively distributed in the mineral kingdom. The only body in which carbon has been found to exist in a state of absolute purity, is the diamond-a precious stone, which has

always been esteemed as the most valuable of the gems; a superiority which it owes to its hardness, lustre, and high refractive power. It uniformly occurs crystallized, and presents a great variety of forms. Its specific gravity is 3.5, water being 1. Its hardness is extreme, so that it can be worn down only by rubbing one diamond against another, and is polished only by the finer diamond powder. The diamond, by being intensely heated with a burning-glass in oxygen gas, burns with a bright red light, and converts the oxygen into pure carbonicacid gas, as charcoal does. Carbonic-acid gas is, therefore, to be considered as a solution of diamond in oxygen gas, even when it is prepared by the combustion of mere charcoal. It may not be altogether useless to remark, that in all places, such as wine-cellars, vaults, and deep wells, where the presence of carbonic-acid gas is suspected, it is proper to use the precaution of trying whether a candle or taper will burn in such places before we venture into them. If it be a deep well that requires to be cleaned, a burning candle should be let down with a cord, and if it go out before reaching the bottom of the well, no person ought to venture down before the noxious air is removed.

Such, then, are the three constituent principles of the atmosphere in which we live and breathe. We ought not, however, to conceive that the principles which form our atmosphere, and the proportion in which they are combined, constitute the only fluid which is fitted for

supporting animal life and vigour. It is a fluid which seems to be adapted only to mortal men, and calculated to support the vital functions only to the period of eighty or one hundred years. It is not at all improbable, that it is owing to the large proportion of nitrogen which enters into the composition of the atmosphere that renders it unfit for supporting human life beyond a certain short and limited period; and that, were a much larger quantity of oxygen combined with other gases, in a certain proportion, and some slight changes effected in the . other elements of nature, the lives of men and other animals might be protracted to several hundreds or thousands of years, and their spirits preserved, at the same time, in uninterrupted cheerfulness and vigour. Nor is it altogether improbable that, in the course of those improvements which are now commencing throughout the world, the air of our atmosphere may be greatly ameliorated, and rendered more salubrious and invigorating to animated beings, when the stagnant marshes which abound in every part of the globe shall be completely drained-when those immense forests which now cover a great part of Asia, of New Holland, and of the continent of America, shall be cut down, and the soil laid open to the influence of the solar rays-when the reefs which are now rising from the ocean, by the agency of minute creatures, shall be formed into continents and islands when the barren deserts of Africa shall be transformed, by human science and

industry, into fruitful fields-when the soil throughout every region of the globe shall be universally cultivated-when those immense thickets and jungles where the lion and the tiger now roam undisturbed, shall be changed into corn-fields, gardens, and orchards, and become the seats of civilisation and of peacein short, when the whole earth shall form one wide scene of rural and architectural beautywe have every reason to believe that then the different climates of the earth will be greatly meliorated; that the fury of those storms which now carry destruction in their train will be greatly abated-and that the very atmosphere around us will be so modified, purified, and improved, as to render it capable of prolonging the life of man for perhaps two or three hundred years. Such effects correspond to what is predicted respecting the state of the world during the millennium, when the instruments of warfare shall be beaten into ploughshares and pruning-hooks; when peace shall reign triumphant over the world, and when every man shall sit under his vine and fig-tree without fear of annoyance. At which period, it is predicted, that the life of man shall be extended beyond its present boundaries. For thus saith Jehovah, "As the days of a tree* are the days of my people"-" they shall build houses, and inhabit them; and they shall plant

* Certain species of trees are said to continue in vigour during a period of five hundred years, us the oak and several other trees.

vineyards and eat the fruit of them; ... and mine elect shall long enjoy the work of their hands." "Then shall the earth yield her increase; and God, even our own God, shall bless us.

All the operations and ameliorations now alluded to are perfectly practicable, were the moral state of man improved. Could we undermine the principle of avarice and selfishness in the human heart; could we promote a spirit of harmony and general benevolence among human beings; and were the whole body of mankind to exert their powers in unison, in the cause of universal improvement-this earth, which, in many places, appears like a world in ruins, might, ere long, be transformed into one wide terrestrial paradise. But principles and dispositions directly opposite to these have, for the most part, hitherto prevailed. The present state of the moral world, and the infernal passions which have raged among mankind for ages past, have rendered it expedient, in the moral government of the Almighty, that the life of man should not extend much beyond "threescore years and ten," in order that wickedness may be kept within certain bounds. And, therefore, no extraordinary or extensive improvements in science and art, or in the general cultivation of the earth, can be expected till the moral powers of man be cultivated and improved along with the intellectual; till the religion of Jesus be universally recognised in all its bearings; till its holy principles and practical