The Breath of Life

by John Burroughs

III

Nature works with such simple means! A little more or a little less of this or that, and behold the difference! A little more or a little less heat, and the face of the world is changed.

"And the little more, and how much it is,

And the little less, and what worlds away!"

At one temperature water is solid, at another it is fluid, at another it is a visible vapor, at a still higher it is an invisible vapor that burns like a flame. All possible shades of color lurk in a colorless ray of light. A little more or a little less heat makes all the difference between a nebula and a sun, and between a sun and a planet. At one degree of heat the elements are dissociated; at a lower degree they are united. At one point in the scale of temperatures life appears; at another it disappears. With heat enough the earth would melt like a snowball in a furnace, with still more it would become a vapor and float away like a cloud. More or less heat only makes the difference between the fluidity of water and the solidity of the rocks that it beats against, or of the banks that hold it.

The physical history of the universe is written in terms of heat and motion. Astronomy is the story of cooling suns and worlds. At a low enough temperature all chemical activity ceases. In our own experience we find that frost will blister like flame. In the one case heat passes into the tissues so quickly and in such quantity that a blister ensues; in the other, heat is abstracted so quickly and in such quantity that a like effect is produced. In one sense, life is a thermal phenomenon; so are all conditions of fluids and solids thermal phenomena.

Great wonders Nature seems to achieve by varying the arrangement of the same particles. Arrange or unite the atoms of carbon in one way and you have charcoal; assemble the same atoms in another order, and you have the diamond. The difference between the pearl and the oyster-shell that holds it is one of structure or arrangement of the same particles of matter. Arrange the atoms of silica in one way and you have a quartz pebble, in another way and you have a precious stone. The chemical constituents of alcohol and ether are the same; the difference in their qualities and properties arises from the way the elements are compounded—the way they take hold of hands, so to speak, in that marriage ceremony which constitutes a chemical compound. Compounds identical in composition and in molecular formulæ may yet differ widely in physical properties; the elements are probably grouped in different ways, the atoms of carbon or of hydrogen probably carry different amounts of potential energy, so that the order in which they stand related to one another accounts for the different properties of the same chemical compounds. Different groupings of the same atoms of any of the elements result in a like difference of physical properties.

The physicists tell us that what we call the qualities of things, and their structure and composition, are but the expressions of internal atomic movements. A complex substance simply means a whirl, an intricate dance, of which chemical composition, histological structure, and gross configuration are the figures. How the atoms take hold of hands, as it were, the way they face, the poses they assume, the speed of their gyrations, the partners they exchange, determine the kinds of phenomena we are dealing with.

There is a striking analogy between the letters of our alphabet and their relation to the language of the vast volume of printed books, and the eighty or more primary elements and their relation to the vast universe of material things. The analogy may not be in all respects a strictly true one, but it is an illuminating one. Our twenty-six letters combined and repeated in different orders give us the many thousand words our language possesses, and these words combined and repeated in different orders give us the vast body of printed books in our libraries. The ultimate parts—the atoms and molecules of all literature, so to speak—are the letters of the alphabet. How often by changing a letter in a word, by reversing their order, or by substituting one letter for another, we get a word of an entirely different meaning, as in umpire and empire, petrifaction and putrefaction, malt and salt, tool and fool. And by changing the order of the words in a sentence we express all the infinite variety of ideas and meanings that the books of the world hold.

The eighty or more primordial elements are Nature's alphabet with which she writes her "infinite book of secrecy." Science shows pretty conclusively that the character of the different substances, their diverse qualities and properties, depend upon the order in which the atoms and molecules are combined. Change the order in which the molecules of the carbon and oxygen are combined in alcohol, and we get ether—the chemical formula remaining the same. Or take ordinary spirits of wine and add four more atoms of carbon to the carbon molecules, and we have the poison, carbolic acid. Pure alcohol is turned into a deadly poison by taking from it one atom of carbon and two of hydrogen. With the atoms of carbon, hydrogen, and oxygen, by combining them in different proportions and in different orders, Nature produces such diverse bodies as acetic acid, alcohol, sugar, starch, animal fats, vegetable oils, glycerine, and the like. So with the long list of hydrocarbons—gaseous, liquid, and solid—called paraffins, that are obtained from petroleum and that are all composed of hydrogen and carbon, but with a different number of atoms of each, like a different number of a's or b's or c's in a word.

What an enormous number of bodies Nature forms out of oxygen by uniting it chemically with other primary elements! Thus by uniting it with the element silica she forms half of the solid crust of the globe; by uniting it with hydrogen in the proportion of two to one she forms all the water of the globe. With one atom of nitrogen united chemically with three atoms of hydrogen she forms ammonia. With one atom of carbon united with four atoms of hydrogen she spells marsh gas; and so on. Carbon occurs in inorganic nature in two crystalline forms,—the diamond and black lead, or graphite,—their physical differences evidently being the result of their different molecular structure. Graphite is a good conductor of heat and electricity, and the diamond is not. Carbon in the organic world, where it plays such an important part, is non-crystalline. Under the influence of life its molecules are differently put together, as in sugar, starch, wood, charcoal, etc. There are also two forms of phosphorus, but not two kinds; the same atoms are probably united differently in each. The yellow waxy variety has such an affinity for oxygen that it will burn in water, and it is poisonous. Bring this variety to a high temperature away from the air, and its molecular structure seems to change, and we have the red variety, which is tasteless, odorless, and non-poisonous, and is not affected by contact with the air. Such is the mystery of chemical change.