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

  • Turner, Edward, 1798-1837.
Date:
1834
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.

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    the system powerfully, and without a certain degree of it the vital actions would entirely cease. Over the vegetable world its influence is obvious to every eye. By its stimulus co-operating with air and moisture, the seed bursts its envelope and yields anew plant, the buds open, the leaves expand, and the fruit arrives at maturity. With the declining temperature of the seasons the circulation of the sap ceases, and the plant remains torpid till it is again excited by the stimulus of heat. The dimensions of every kind of matter are regulated by this principle. Its increase, with few exceptions, separates the par- ticles of bodies to a greater distance from each other, producing expansion, so that the same quantity of matter is thus made to occupy a larger space; and the diminution of heat has an oppo- site effect. Were the repulsion occasioned by this agent to cease entirely, the atoms of bodies would come into actual con- tact. | The form of bodies is dependent on heat. By its increase solids are converted into liquids, and liquids are dissipated in vapour; by its decrease vapours are condensed into liquids, and these become solid. If matter ceased to be under the influence of heat, all liquids, vapours, and doubtless even gases, would become permanently solid; and all motion on the surface of the earth would be arrested. When heat is accumulated to a certain extent in bodies, they shine or become incandescent. On this important property de- pend all our methods of artificial illumination. Heat exerts a powerful influence over chemical phenomena. There is, indeed, scarcely any chemical action which is not in some degree modified by this principle ; and hence a knowledge of its laws is indispensable to the chemist. By its means bodies previously separate are made to combine, and the elements of compounds are disunited. An undue proportion of it is de- structive to all organic and many mineral compounds ; and it is essentially concerned in combustion, a process so necessary to the wants and comforts of man. Of the various effects of heat above enumerated, several will be discussed in other parts of the work. In this place it is pro- posed to treat only of its influence over the dimensions and form of bodies, a subject which will be conveniently studied under the three heads of expansion, liquefaction, and vaporization,