Page:Popular Science Monthly Volume 8.djvu/485

Rh supposed elements in their relations to the various modes of energy? Perhaps in the discussion of this problem Gustavus Hinrichs would stand first. His conclusions may be easily questioned, but the ability and ingenuity displayed in reaching them cannot be denied.

To the general reader, or to the beginner in chemistry, the difficulties confronting the unitary view of matter may seem to be very great. Doubtless they are; but then every side of the subject is beset with difficulties. Obstacles must be surmounted, and the worst are not in this direction. The mind unused to speculations of this sort will probably encounter its greatest embarrassment in trying to understand how one substance alone can assume such a diversity of forms. That such a thing is within the limits of possibility, may be illustrated by reference to the facts of allotropy and isomerism. Quite a number of our present elements are known to be capable of existing in a variety of dissimilar modifications. Carbon is found as charcoal, graphite, and diamond; phosphorus exists both in its white and in its red modifications; oxygen is allotropic as ozone. Similar examples are furnished by arsenic, selenium, and, very notably, by sulphur. Among compounds, especially in organic chemistry, many cases occur in which several different bodies have precisely the same elementary composition. For instance, the essential oils of rose, bergamot, orange, lemon, lavender, turpentine, rosemary, nutmegs, myrtle, peppermint, etc., unlike as they may be in outward properties, are all composed of carbon and hydrogen in exactly the same percentages. The same atoms occur, but differently arranged. Many other sets of isomeric bodies are known in which this diversity of atomic arrangement can be distinctly traced, and the reasons for difference clearly pointed out. The limitations of space prevent their description here.

Now, since a single element may exist in several different forms, and since the same atoms can unite together so as to produce compounds very unlike each other, the chief objection to the unitary view is removed. Why may not all the so-called elements be allotropic modifications of one, or else isomeric bodies formed by the union of two or three such modifications? Such a supposition is by no means absurd, although, to be sure, it is not capable of rigid demonstration. It is only a speculation, but then within it are some fair probabilities. These may be strengthened by an appeal to spectroscopic evidence, and to the prevalent hypothesis concerning the origin of our planet.

If we examine the spectra of our supposed elements, we shall notice no more striking fact than the extent to which they differ in complexity. Some bodies give spectra of only one or two lines, while others are represented by hundreds. This atom emits light of a single wave-length, that one gives out rays of nearly half a thousand different kinds. Now, what do these facts mean? Do they indicate structural differences within molecules such that each bright line in a spectrum corresponds to a true element? Such a notion, if true,