Volume 1

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

  • Thorpe, T. E. (Thomas Edward), 1845-1925.
Date:
1877
Catalogue details

Licence: Public Domain Mark

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

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    and greater than the two thousand-millionth of a centi- metre. We may form some conception of the degree of coarse-grainedness thus indicated, if we imagine a rain-drop or a solid globe of glass to be magnified up to the size of the earth, when, if each constituent molecule were enlarged in the same proportion, the magnified structure would be coarser grained than a heap of small shot, but probably less coarse grained than a heap of cricket-balls. * 5. Elements and Compounds.—In subjecting all matter to his experiments, the chemist arrives at an ultimate division of substances into two great classes:—(1.) Elementary sub- stances—bodies which he is unable to resolve into anything essentially different from themselves; and (2.) Compound substances—bodies which may be made to yield two or more essentially different substances. Thus, he is unable to make carbon yield any other kind of matter; nor can hydrogen, by any means at his disposal, be resolved into other sub- stances. Carbon and hydrogen are therefore termed elements. On the other handt paraffin is a compound; it is composed of carbon and hydrogen, into which substances it can be split up. So carbon dioxide is a compound; it is composed of oxygen and carbon. Water also is a compound; it is composed of oxygen and hydrogen. So also gun-cotton is a compound, since, by the action of heat, we have seen that it is decom- posed, and its state permanently changed—we have resolved it into substances essentially differing from itself. The term element is to be understood with a certain limitation. As applied to any substance, it must be taken simply to mean that, up to the present time, no one has succeeded in decom- posing that substance. Any such idea that these bodies are in their essence elementary, might lead us into error; for many substances, formerly supposed to be simple, are now known to be compounds; and no one can pi’edicate that the substances we class among the elements to-day, will be ultimately found to be absolutely simple bodies. The following is a list of the elements at present known to us. So far as we can tell, the entire universe is built up of these sixty-three elements and their combinations. * Nature, p. 551, 1870.