Copy 1, Volume 3

A system of chemistry. In four volumes / By Thomas Thomson.

  • Thomson, Thomas, 1773-1852.
Date:
1817
Catalogue details

Licence: Public Domain Mark

Credit: A system of chemistry. In four volumes / By Thomas Thomson. Source: Wellcome Collection.

    15/636 (page 3)
    which a heavy body is urged towards the earth; that it is Chap. i. possessed, not only by the planets as wholes, but by all their, component parts also ; that it is mutual; that it ex¬ tends to indefinite distances; and that all bodies, as far as is known, are possessed of it. 3. When two bodies are brought within a certain dis¬ tance, they adhere together, and require a considerable force to separate them. This is the case, for instance, with two polished pieces of marble or glass. When a piece of metal, or indeed almost any body whatever, is plunged into water and drawn out again, its surface is moistened, that is to say, part of the water adheres to it. When a rod of gold is plunged into mercury, it comes out stained in¬ delibly of a white colour, because it retains and carries with it a portion of the mercury. Hence it is evident that there is a force which urges these bodies towards each other and keeps them together; consequently there is an attraction between them. Bodies, therefore, are not only attracted towards the earth and the planetary bodies, but towards each other. The nature of this attraction cannot be as¬ signed any more than that of gravitation ; but its existence is equally certain, as far at least as regards by far the greater number of bodies. 4. In all cases we find the particles of matter united to¬ gether in masses; differing indeed from each other in mag¬ nitude, but containing all of them a great number of par¬ ticles. These particles remain united, and cannot be separated without the application of a considerable force; they are kept together therefore by a force which urges them towards each other, since it opposes their separation. Consequently this force is an attraction. Thus we see that there is a certain unknown force which urges bodies towards each other; a force which acts not only upon large masses of matter, as the sun and the planets, but upon the smaller component parts of these bodies, and even upon the particles of which these bodies are composed. Attraction, therefore, as far as we know, extends to all matter, and exists mutually between all matter. It is not annihilated at how great a distance soever we may suppose bodies to be placed from each other, neither does it disap¬ pear, though they be placed ever so near each other. The nature of this attraction, or the cause which produces it, ' B 2