Elements of chemistry, including the recent discoveries and doctrines of the science / by Edward Turner.

  • Turner, Edward, 1798-1837.
Date:
1833
Catalogue details

Licence: Public Domain Mark

Credit: Elements of chemistry, including the recent discoveries and doctrines of the science / by Edward Turner. Source: Wellcome Collection.

    32/1026 (page 4)
    change of form or composition ; for the same material parti- cles, after having undergone any number of such changes, may still be proved to possess the characteristic properties of matter. The secondary properties of matter are opacity, transpa- rency, softness, hardness, elasticity, colour, density, solidity, fluidity, and others of a like nature. Several of these pro- perties, especially those last specified, depend on the relative intensity of two opposite forces—cohesion and repulsion. It is inferred, from the divisibility of matter, that the substance of solids and liquids is made up of an infinity of minute par- ticles adhering together so as to constitute larger masses ; and that the mutual adhesion of these particles is owing to a power of reciprocal attraction. ‘This force is called cohe- sion, cohesive attraction, or the attraction of aggregation, in order to distinguish it from terrestrial attraction. Gravity is exerted between different masses of matter, and acts at sensible and frequently at very great distances ; while cohe- sion exerts its influence only at insensible and infinitely small distances. It enables similar molecules to cohere, and tends to keep them in that condition. It is best exemplified by the force required to separate a hard body, such as iron or marble, into smaller fragments; or by the weight which twine or metallic wire will support without breaking. The tendency of cohesion is manifestly to bring the ulti- mate particles of bodies into immediate contact; and such would be the result of its influence, were it not counteracted by an opposing force, a principle of repulsion, which pre- vents their approximation. It is a general opinion among philosophers, supported by very strong facts, that this repul- sion is owing to the agency of caloric, which is somehow attached to the elementary molecules of matter, causing them to repel one another. Material substances are therefore sub- ject to the action of two contrary and antagonizing forces, one tending to separate their particles, the other to bring them into closer proximity. The form of bodies, as to soli- dity and fluidity, is determined by the relative intensity, of these powers. Cohesion predominates in solids, in conse- quence of which their particles are prevented from moving freely on one another. The particles of a fluid, on the