application does not explain cosmic phenomena, though difficulties even here were suggested, but even if it account for the action of molar objects, i. e., those objects which can be weighed, measured and handled, it does not answer the questions which are put to us by the world of atoms. The study of chemistry and the queries raised by its revelations compelled the defenders of Newton's theories as a sufficient explanation of all phenomena in the heavens and on earth to enter upon a renewed investigation of the basis on which they rest, and to give patient consideration to the phenomena of the atomic world. At length, and because some other action than that of gravity was needed to explain molecular phenomena, the relation of atoms to each other, the phenomena of magnetism and electricity, what is known as the atomic theory was suggested and very generally received, not, however, as setting aside any truths discovered by Newton or involved in the astronomical theory, but as supplementing it and accounting with something like reason for the molar and molecular phenomena which it overlooked or did not recognize as existing.
This atomic theory is not an entirely modern theory. Empedocles of Sicily, who lived in the fifth century before Christ, accepting four primal elements, earth, air, fire and water, explained their modifications and their actions one upon the other, by assuming the existence of two principles, love and hate, attraction and repulsion, which are constantly in operation and which create the forms we behold and account for all the activity in the universe. The atomic theory developed, far more fully than by Empedocles, by Democritus of Abdera of the same century and defended by him with a wealth of learning possessed by no other man of his time gained wide acceptance. In its modern form the theory secured recognition in France and Germany earlier than in England. The exact methods of chemists and mathematicians, first in France then in Germany, led to the belief that matter is not a single piece of something in empty space, but is made up of a multitude of individual and indivisible particles which only partially fill this space, which is filled by that indefinable something which we call ether and which we affirm to be necessary both for sight and hearing.
As chemistry was more earnestly and wisely studied, as the laws of the combination of so-called elemental substances were better understood, men of science became less and less unwilling to admit the inadequacy of Newton's theory of gravitation as an explanation of all phenomena and the more ready to accept a theory which explained, as it seemed to them, the movements in the molecular world, and which, if matter is composed, as was asserted, of atoms, might explain conditions everywhere. Berzelius of Sweden demonstrated the truth of the theory by his wonderful experiments. Dalton's theory of atomic weights was accepted as in harmony with what seemed to be facts. Van't Hoff discovered, so it is believed, laws governing the arrangement of elements
