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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    and a body having entirely new properties has been pro- duced, from which the individual elements can only be obtained by difficult chemical processes, by the application of energy in some form equivalent to the energy of chemical union, as evidenced by the evolution of heat in its formation. Gunpowder is also a good example of a mixture. It consists of a chemical compound nitre, and two elements —carbon and sulphur. Here separation is easy, due to the retention of their individual properties by the constituents. Nitre is soluble in water, the other bodies are insoluble ; after separating the nitre by shaking up with water, the resulting mixture of carbon and sulphur is treated with carbon bisulphide, which dissolves the sulphur and leaves the carbon. The nitre can be obtained from the aqueous solution, and the sulphur from the carbon bisulphide solu- tion, by evaporation, and thus the mixture resolves itself into its components. 4. Atoms and Molecules.—Two views have been held as to the constitution of matter— (1) That it is indefinitely divisible. (2) That there is a limit to such divisibility, that limit being reached when we arrive at small particles termed atoms. Dalton held the latter view, and as a result of his investigations the atomic theory took a definite shape. Atoms are the indivisible constituents of molecules. They are the smallest particles of eleme?its that take part in a chemical reactio?i, and are for the greater part i?icapable of existence in the free state, being generally found in combination with other atoms either of the same kind or of dijfere?it kinds. Hydrogen being the lightest element known is taken as the standard, and the other elements are represented in terms of this one. Thus the statement that the atomic
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