APPENDIX.

A.

THE EARTH'S CHEMISTRY AN EXHAUSTED CHEMISTRY.

THE rocks, and clays, and sands, and soils, of which the earth's crust is composed, or with which it is covered, along with the watery contents of the ocean, are so neutral and quiescent in their nature, so little likely to take fire on the one hand, or support combustion on the other, that we are apt to suppose that, if the rest of creation were all like them, they would not be subject to any change, nor be capable of originating any action or producing any power. But when we discover that these rocks and seas are the remains, or rather the products, of a former combustion; and when, by means of chemical research, we find that their original condition was very different, we open our eyes to a new and beautiful arrangement by which there resided, in the original elements of creation, a latent power which was capable of being developed in the formation of the planets, and which is at present in action in the formation of the sun and the stars. The chemistry of our earth is, in reality, an exhausted chemistry, dealing only with residuary materials which have expended all

their force. That we have any chemical action at all is due to two circumstances: the first is, that, in a manner which we shall afterwards explain, the rays of the sun restore substances to their original condition of separate existence. It divorces them, as it were, from one another, so that they become capable of contracting other unions; for a chemical action is the marriage or divorce of substances which are all, as it were, male or female.

The second is, that all substances have different degrees of preference for others; and, although at the formation of the earth by combustion two substances were, as it were, married to one another, yet their attachment may be weak; and another substance, more masculine than the husband, or more feminine than the wife, may cause a chemical divorce and another marriage. For example, such an exceedingly masculine substance is the metal potassium, and such an exceedingly feminine substance is oxygen, that they have the very strongest attraction towards each other. Water, it is well known, is a compound of oxygen and hydrogen (produced by flame); but the mutual attraction of oxygen and hydrogen is not nearly so strong as that of oxygen and potassium-the consequence is, that when a piece of potassium is thrown. upon water, it robs the hydrogen of its oxygen, in order to form an oxide of itself (potash). The hydrogen thus set free takes fire, and unites with oxygen again to form water as before.

This division into sexes, however, must not be regarded as altogether definite, for it is rather a gradation than a division. There are extremes, no doubt the extreme masculine, and the extreme feminine-as is the case with potassium and oxygen; but there are many substances between. Among the number there are some that marry

upon either side; and it depends on circumstances whether such a substance will take the place of a husband to a more feminine wife, or the place of a wife to a more masculine husband. Such a substance is sulphur; it is feminine when united to iron-it is masculine when united to oxygen.

Our unlearned readers will now more easily understand us when we say that the chemistry of the earth is an exhausted chemistry-all its couples are married; and were it not for the analysing or divorcing power of the sun's rays, there would be no chemical changes at all—all would be still as death.

This more delicate style of chemical action is absolutely necessary for our earth, as the abode of animal and vegetable life; but it suggests a very erroneous idea of the qualities of the substances which exist in space, and which give to the sun and the stars the light and the heat and the power which are peculiar to them as the sources of light and life.

The deoxidising power of the sun's rays, to which allusion has been made, constitutes the grand instrument of planetary life—and is a law of a very general character, which governs all chemical actions. To the popular

reader it may be described as an unburning powermeaning by that, not the power of preventing combustion, but of reversing the process; the undoing of what has been done, or the restoring of that which has been burned to the state in which it was before it was burned. Chemical combination presents, as its general character, the act of burning; not that every chemical combination is what is popularly called burning, but burning is the type of chemical combination; for all chemical combinations partake of that character. The most common is the

union of oxygen with some other substance having a more positive polarity than itself this is called oxidation; and, although oxidation frequently takes place so slowly as to present no appearance of combustion, yet, however slowly it takes place, the effects of combustion are always produced, viz, heat and electric disturb

ance.

If we regard oxidation as burning; then deoxidation (that is, the separation of the two substances from one another,) may be regarded as unburning, so that the substances are capable of being burned again. The reader will now be prepared to understand what is meant by the deoxidising power of the sun's rays. Every chemical combination produces an influence which tends to chemical separation; therefore, oxidation has the power of producing deoxidation; and burning has the power of unburning.

For example-the sun's rays put out a fire, by preventing the oxidation of the fuel; and when they fall upon the leaf of a tree, they deoxidise the water, and the carbonic acid gas. When wood is burned, the hydrogen and carbon, of which chiefly it is composed, are possessed of a strongly positive polarity; and, as the oxygen of the atmosphere is possessed of a strongly negative polarity, they unite with the oxygen when they are burned, and become oxidised; the hydrogen and the oxygen form water, and the carbon and oxygen form carbonic acid gas. But when the rays of light fall on the leaf of a tree, the water which the leaf contains, and the carbonic acid gas which is in the air, are subjected to the deoxidising power of the sun, which we have mentioned; the hydrogen of the water, and the carbon of the carbonic acid gas, are forced to separate from the oxygen, with which they were previously united-and with this hydrogen and carbon the tree forms