Volume 1

A manual of inorganic chemistry ... / by T.E. Thorpe.

  • Thomas Edward Thorpe
Date:
1877
Catalogue details

Licence: Public Domain Mark

Credit: A manual of inorganic chemistry ... / by T.E. Thorpe. Source: Wellcome Collection.

    16/424 page 12
    The globe (fig. 3) is closed with a caoutchouc cork fitted with a stop-cock ; through the cork run two copper wires connected together at the end by a thin platinum wire wrapped round the piece of gun-cotton. The globe is exhausted by means of the air-pump, and accurately coun- terpoised whilst hanging on the arm of the balance. The thin platinum wire is then strongly heated by means of the electrical arrangement represented in the figure, and the gun-cotton thus fired. It completely disappears, but the weight of the apparatus remains absolutely unaltered. By innumerable repetitions of such experiments, the truth of the fundamental principle that matter is in- destructible has been established. The sum of created matter is fixed and invariable. We cannot add any- thing to it, nor can we annihilate a particle of it. This principle constitutes the basis upon which rests the ivhole superstructure of the science of Chemistry—that science which concerns itself with the study of the mutations of matter. 3. Chemical Affinity.—In burning the candle or the gun- cotton, we have effected what is called a chemical decompo- sition. We have resolved these substances into others, possessing essentially different properties. That modification of force which brings about these changes—which causes the combination of the oxygen of the air with the carbon and hydrogen of the paraffin—is called chemical affinity. It is characteristic of this force to educe from a given body other substances differing altogether in properties from the original, or by causing the intimate juxtaposition of two substances, to produce a third body, essentially differing in properties from its components. The true nature of this action is as much hidden from the chemist as is the nature of gravitation. He can simply observe its effects, and attempt to discover the laws which regulate it. In seeking for these laws, he is led to inquire into the composition of all material things, and to study their action upon each other; to determine the conditions of their stability, and the circumstances under which they combine together; to estimate the proportions of the constituents in the resulting compounds; and to elucidate their constitution,
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