The chemistry of life and health / C.W. Kimmins.

  • Charles William Kimmins
Date:
1892
Catalogue details

Licence: Public Domain Mark

Credit: The chemistry of life and health / C.W. Kimmins. Source: Wellcome Collection.

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    weight of oxygen is 16, means that the atom of oxygen is 16 times heavier than the atom of hydrogen, whatever that may be. A ?nolecule is the s?nallest particle of an element or com- pound that is capable of existe?ice in a free state. No matter how finely divided a compound may be, the smallest particle retains the properties of the substance until the molecule is reached : if division is carried further these properties are lost, and the compound is resolved into its constituents. Assuming the molecular theory of matter, we conclude that, provided we had magnifying powers for our microscopes infinitely greater than those at present in use, we should find that a drop of water under such a microscope would consist of innumerable little particles—the molecules of water—and that these again would be built up of atoms of oxygen and hydrogen. If a cubic inch of water is raised to the boiling point it produces about 1600 inches of steam at that temperature. This steam can then be raised to a higher temperature, so that we may have 10,000 cubic inches of steam produced from this small quantity of water. Although the water in the form of steam is now distributed over an area 10,000 times as great as at the commencement of the experiment, we find that, if we examine a small quantity of the steam, it retains all the chemical properties of water, and we are still dealing with exactly the same kind of particles we had to start with. If, however, we pass some of the steam over a coil of white-hot platinum it is broken up into its constituent elements—hydrogen and oxygen; if we rapidly cool down these products below the temperature at which they unite
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