perish. But for the creation of a supply of those gases the vegetable kingdom could not exist.

The earth does by no means furnish, as is commonly supposed, all the elements necessary for the growth of plants. The juices, the perfumes, the fruits, the vegetable tribes which nature incessantly renews with the seasons, derive much of their aliment from the air. The delicious pulp of the peach, of the orange, pears, plums, ananas, the multitude of melting fruits, with which autumn fills her horn of plenty, the fresh rose bending under the pearly dew, the proud oak, the superb cedar, the baobab, that giant of trees, which covers whole acres with its shade, are little more than consolidated gas, to which nature, elaborating them in silence, has imparted their peculiar properties on a basis of air. How incomprehensible are the works of this mysterious power!

It is not enough to purge the air of noxious gases, that plants exhale the vivifying gas of oxygen. That decomposition of water, which science considers it one of its proudest triumphs to have accomplished, has been hourly effected, from the beginning of the world, by the feeblest plant. We are surrounded with multitudes of little, silent chemists, who incessantly drink the hydrogen of water, and disengage its oxygen so friendly to animal life, and diffuse it in the air. Thus all those green surfaces, those flowering meads, those verdant groves, those velvet turfs, which delight our eye, continually lustrate the atmosphere by emitting a quantity of oxygen equal to that which the animals destroy. The respiration of vegetables sustains a perfect equilibrium with that of all living beings. We furnish them the supplies of carbonic acid gas, as they prepare for us the requisite abundance of oxygen. This invisible correspondence between the vegetable and the animal kingdom gives birth to one of the harmonies of the universe. With what different eyes must we contemplate the glorious and beautiful nature that surrounds us, after this information! What stable ground for confidence in the beneficent being, that has thus arranged every thing in nature by weight and measure!

We may imagine that this harmony between vegetables and animals is interrupted during the total cessation of vegetation in winter. Contemplate anew the wisdom of Providence. The storms of winter are among its benefits. They establish an aerial circulation between the poles, the tropics and the equator, and equalize the oxygen of the various countries of the world. Besides, immense numbers of terebinthines, and trees always green, which send their salubrious exhalations abroad, are reserved for the colder climates. The lichens and mosses subserve the same great purpose. They are sources of oxygen perpetually flowing from the north to the south. Thus tempests, which threaten the destruction of nature, are found to be among its conservative laws. At the view of these wonders can we avoid discovering why this transparent fluid, which forms the atmosphere, has been placed between us and the abysses of space, to bring us light and heat, to bear the clouds which fertilize the earth, to supply aliment to fire, without which it would become extinct, to renew and sustain vegetation, to serve as the medium and vehicle of sound, and to give life to all creatures? Behold the singular dependencies between this invisible fluid and man, between man and a planet of fire, between this planet of fire and the world! Admirable harmonies, which cause, that the heavens, the earth and air, plants and animals, winds, storms, water and fire, all concur to the well being of a thinking atom, lost upon the surface of a globe, which is itself lost in the immensity of space!

What a distance separates a spire of grass from man! Yet our life depends, by a double necessity, upon the existence of the frail tribes of vegetation. Astonishing creation, from which you can take nothing without the destruction of all! Saadi's beautiful Persian fable of the nightingale and the rose proves that he understood, as a philosopher, this harmony, which he sung as a poet. The nightingale is imprisoned in a cage of glass with a rose bush blooming with roses. Each owes life to the other. Deprived of fresh air, the bird would soon cease to swell its little throat with harmony. The rose greedily absorbs the air which has been

respired by its loved philomel, and blushes to brighter tints; respires, transforms, and returns it purified, to be inhaled anew by the bird of song. As often as the nightingale decomposes the air, the rose neutralizes the poison in its own bosom, and sends back pure air to its fellow prisoner. When the bird at length expires, in singing its dirge of gratitude, the rose bush withers and dies.

LECTURE XX.

CARBONIC ACID GAS.

CARBONIC acid gas will be the subject of this lecture. This is the product of the combustion of charcoal with oxygen. Its gravity shows one more of the innumerable instances of the foresight of nature. You recollect, that it is from this mephitic gas, that plants draw almost all their nourishment and life. Behold the reason why its weight brings it to the ground, while the other gases preserve more or less elevation, according to the wants of man. The gas, of which I speak, is often found in caverns, wells, and deep places of the earth; particularly at the grotto del cani near Naples, and at the baths of Cæsar at Mont d'Or. These mountains are full of caverns, from which it escapes. This air filled the melancholy cave of Trophonius, and, mixed with other gases, probably formed the intoxicating combination that produced the contortions and the inspirations of the Pythian priestess of Delphos. Thus a little mephitic air originated oracles, which settled the destiny of nations.

Dogs, from which the grotto del cani derives its name, cats, and all other animals, die instantly upon being plunged into this gas, as it issues from the cave. From the Rock Spring at Saratoga, a stream of this gas is constantly emitted, which produces the same effect upon animal life.

We pass from this mephitic gas, the product of charcoal, to the most brilliant substance in the universe, which decomposes light, and reflects all the colours of the bow, decks the bosom of beauty, and shines in the diadem of kings. This substance, called diamond, is pure charcoal. We owe the knowledge of this fact to Lavoisier, Tennant and Guyton Morveau.

I shall not be able to repeat to you the numerous and beautiful experiments of these great men. It is sufficient for you to know that carbon is one of the bodies which nature has most extensively diffused in the formation of the universe. It makes more than half the composition of vegetables and animals; and is found combined with minerals.

I have been astonished that geologists, who have so long and earnestly sought for the elements of the universe, have never imagined it to have been formed from an immense diamond. What a beautiful spectacle, to behold the world springing from chaos, in the form of a huge brilliant, whirling upon its axis, and emitting torrents of dazzling light! Would you prefer to suppose with Buffon, that the earth was a spark struck off from the sun; with Burnet, that it was at the beginning a bowl full of water; or with Palissy, that it was a shell? What a charming opportunity for me to bring forward my system; or if you prefer it, to prove, that there is no idea so extravagant, that it may not be rendered plausible by a theory sustained by seductive reasonings! I could write a large book to prove that a world of diamond is the most beautiful and feasible form of a world.

Recollect that carbon is the base of vegetables and animals, and is found diffused over the whole surface of the earth. If it be true, that this element is distributed with so much profusion, and that stones and trees include carbonic acid gas, as chemists prove, imagination has little more to do to make a world of diamond to my hand. I see in the present form of the world proofs of its primitive condition and ancient opulence. O happy epoch for queens and beauties, when the undue proportion of the sun's rays and the oxygen of the atmosphere had not yet converted this globe

to earth, vegetables and dark mould! Science is about to renew that age, not of gold, but of diamond. Already the

forest trees are transformed to columns of diamonds. Their branches, flowers and fruits are in our eyes so many mirrors, as luminous as the rays of the sun. The meadows put forth brilliant adamantine flowers. The flocks and herds graze and bound under a crystal canopy of transparent splendour. Bread, vestments, air, all is diamond! While the sun darts his rays upon these glittering prisms, man, dazzled with finding himself in the midst of a globe of light, becomes himself a diamond!

To operate these prodigies, it is only necessary to find the secret of reducing charcoal to the state of pure carbon. Nature would then present the dazzling spectacle, of which I have here given you a sketch. In waiting for this discovery, I hasten to propose to our fair the cheaper substitute of bracelets and collars of charcoal, one day to become pure diamond. Fashion, as you know, has the power to embellish every thing.

But this gas, which serves to form foliage, fruits and harvests, produces effects not less surprising in the interior of our globe. It is probable, that to its combinations in perpetual operation, we may attribute the formation of metals and minerals. Earthquakes, water-spouts, volcanoes, meteoric stones seem, also, to owe their origin to the different aerial elements in combination with carbonic acid. The gases circulate in the depths of the earth, as the blood in animals, Perpetually varying, and renewed by their affinities, we can no where descend deep into the earth, without encountering their effects. Hence miners are often the victims of carbonic gas, which gives them apoplexy; or hydrogen, which takes fire, and destroys them, as with a lightning stroke.

I would be glad in this place to relate to you the affecting narrative of Goffin and his fellow laborers, who were assailed at once by water and a blast of hydrogen in the coal mines of Beaujou. Europe still remembers their misfortune, and the heroic efforts of their magnanimous leader. A blast