CHAPTER VIII.
SCIENTIFIC WORK—MOLECULAR THEORY.
Maxwell in his article “Atom,” in the ninth edition of the Encyclopædia Britannica, has given some account of Modern Molecular Science, and in particular of the molecular theory of gases. Of this science, Clausius and Maxwell are the founders, though to their names it has recently been shown that a third, that of Waterston, must be added. In the present chapter it is intended to give an outline of Maxwell’s contributions to molecular science, and to explain the advances due to him.
The doctrine that bodies are composed of small particles in rapid motion is very ancient. Democritus was its founder, Lucretius—de Rerum Naturâ—explained its principles. The atoms do not fill space; there is void between.
“Quapropter locus est intactus inane vacansque,
Quod si non esset, nullâ ratione moveri
Res possent; namque officium quod corporis extat
Officere atque obstare, id in omni tempore adesset
Omnibus. Haud igitur quicquam procedere posset
Principium quoniam cedendi nulla daret res.”
According to Boscovitch an atom is an indivisible point, having position in space, capable of motion, and possessing mass. It is also endowed with the power of exerting force, so that two atoms attract or repel each other with a force depending on their distance apart. It has no parts or dimensions: it is a mere geometrical point without extension in space; it has not the property of impenetrability, for two atoms can, it is supposed, exist at the same point.