If we attempt to trace a particle of matter, we shall find its wanderings endless. Annihilation is a term which is not applicable to material things. Matter is never destroyed; it rarely rests. Oxygen, for instance, the most important constituent of our atmosphere, is the combining element of all things, the medium of communication between the kingdoms of Nature, the agent of the interchanges that are continually taking place among all created things. Oxygen keeps life in man, by combining with his blood at every inhalation; it is absorbed by flowers, to be employed in the perfection of the fruit; many minerals are incapable of the various uses of society, until oxygen has attacked and united with them. It gives us lime and soda, the oil of vitriol, and common salt; the mineral pigments in common use are impossible without it; and the beautiful colors of our autumn leaves are due to the combination of oxygen with their juices. It enters into all plans and operations with a helping hand; animals and plants owe their lives to it; but when the shadow of death begins to fall upon them, it is as ready to aid in their destruction. Like calumny, which blackens whatsoever is suspected, oxygen pounces upon the failing and completes their ruin. The processes of fermentation and putrefaction cannot commence in any substance, until it has first taken oxygen into combination. Thus, cans of meat, hermetically sealed, with all the air first carefully expelled, undergo no change so long as the air does not get access to them. If the minutest opening remain, the oxygen of the atmosphere combines with the contents of the can, and fermentation or putrefaction follows. Rust, which takes the keen edge from the knife, is only another name for oxydation: keep the knife bright, and no oxygen dares touch it; but the slightest blemish is made a loophole for the entrance of the ever-watchful enemy, who never again leaves it until its destruction is complete.
All the elements have a great love of society; they cannot live alone; they have their likes and their dislikes; they contract alliances which endure for a time, but are dissolved in favor of stronger attractions.
We have mentioned the names of several natural elements. Let us see what they are, and what they have to do with man and the kingdoms of Nature. Beginning with man, let us see what becomes of him in course of time, what physical metamorphoses he undergoes, to what vile but excellent uses he is put.