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THE POPULAR SCIENCE MONTHLY

mists who, with the possible exception of an occasional Paracelsus, sought hap-hazard for the transmutation of the metals, has been vindicated by the disintegration theory of atoms and the discussion of the possible transmutation of one chemical element into another. This is doing altogether too much honor to the alchemists whose only object was personal enrichment; there is no credit due to them; the most extravagant theory may be realized under suitable conditions and in this mysterious universe any condition or concurrence of conditions seems to be possible.

Theories of Matter

For the belief that all matter may have a common origin, we must go back twenty-five centuries to Thales of Miletus and the hylozoistic school; it is another case of the premature leakage of subliminal wisdom. Sir Norman Lockyer can be said to have put the theory into tangible form by his work on stellar evolution which has developed the fact that the complexity of stellar matter is a function of its temperature. The higher the temperature of a star is, the fewer and the simpler are the elements present. Würtz wrote that "the diversity of matter results from primordial differences, perpetually existing in the very essence of these atoms and in the qualities which are the manifestation of them." Ascribing a common origin to all matter would tend to make the formation of new compounds from heterogeneous chemical elements appear more rational.

The problem of the ultimate structure of matter has stirred the philosophers of all ages, Democritus and Leucippus were the real discoverers of the atomic theory, and Lucretius was its poet; but the times were not propitious for its use as a working hypothesis; it was not, therefore, until revived by Gassendi and adopted by Dalton, that it became acceptable to science. As long as the chemist was obliged to work with molar masses of matter, his work was unsystematic and in a great measure fruitless; the atomic theory put things in their place and gave the chemist definite molecular masses with which to work. The proof of the atom has been its results; we have not here a question of nature, nor a question of form to discuss; the atom is a fact in chemistry, even if it has no existence in any conceivable form. Molar masses are continuous aggregates of molecules; molecules are definite aggregates of atoms. The selective qualities of atoms, the phase-rule, etc., belong at present more to chemistry than to physics, and they will, therefore, be left out of the discussion. Molar activity is known by its comparatively slow mechanical effects; atomic and molecular activity are known as heat and other forces, and as we go down the scale of size we find the activity more intense. But if it is unnecessary for the purpose of this exposition to discuss atoms and atomic aggregates, it is very important to understand the rô1e of ions.