The progress of scientific chemistry in our own times : with biographical notices / by William A. Tilden.

  • William A. Tilden
Date:
1913
Catalogue details

Licence: Public Domain Mark

Credit: The progress of scientific chemistry in our own times : with biographical notices / by William A. Tilden. Source: Wellcome Collection.

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    a force which is directly as the product of their masses, and inversely as the square of the distance between them. This is the cause of weight, in which the earth as the larger body seems to draw all things to itself, though the action is always mutual. So also a magnet attracts iron and some other metals; a stick of glass or resin, which has been rubbed, attracts light bodies, such as a feather. In the last case, as in the others, the action is reciprocal, the glass attract¬ ing the feather and the feather the glass, and the cause of the attraction is said to be the charge of electricity which has been developed upon both bodies. But after all, everv one of these cases of 7 t/ attraction is only a degree less obscure than that which we call “ chemical affinity,” which operates at distances so small as to be immeasurably beyond recognition by our senses, and even probably by any direct means of measurement which we can experi¬ mentally apply. For although we know the law of gravitation as already stated, and can make quan¬ titative expressions of the force with which bodies are drawn together in the other cases, we can only make guesses as to the essential nature of gravitation, and of the attraction due to magnetism or to electrical induction. In the case of chemical affinity, we not only do not yet know why substances unite together, but there is at present no measure of the law as to the distance through which particles of uniting substances may act upon each other. Nevertheless, speculation has of course not been wanting, and
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