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Page:Popular Science Monthly Volume 19.djvu/706

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THE POPULAR SCIENCE MONTHLY.

and is not likely to afford any features of important interest. The same is the case, in a higher degree, with the most of Arabia, which the inhabitants themselves say God created in anger, and which the travels of Palgrave and Blunt show is not likely to afford enough scientific results to pay for the toil and dangers of a thorough examination. Our knowledge of Mesopotamia and Syria is being rapidly increased by the zeal of antiquarian explorers, whose investigations, although they are rather historical than geographical, and concern the past rather than the present, are not without results of contemporary interest. In Asia Minor and Armenia, researches already carried on need to be completed and systematized and made generally applicable to the whole country; and there are spots within three or four days' journey from Constantinople that still need to be thoroughly worked out.

We are back in Turkey, whence we started, but on the southern instead of the northern side of the Hellespont and Bosporus. We might complete our tour by examining these straits, and finding whether they are traversed by a single current, carrying the waters of the Black Sea into the Mediterranean, or by two currents, one superficial and running to the west, the other submarine and directed toward the east—a question that may have a bearing on the future of the countries east of the Black Sea.—Revue Scientifique.

 

WHAT IS A MOLECULE?

MODERN science declares that every substance consists of an aggregation of extremely small particles, which are called molecules. Thus, if we conceive a drop of water magnified to the size of the earth, each molecule being magnified to the same extent, it would exhibit a structure about as coarse-grained as shot; and these particles represent real masses of matter, which, however, are incapable of further subdivision without decomposition. A lump of sugar, crushed to the finest powder, retains its qualities; dissolved in water, the mass is divided into its molecules, which are still particles of sugar, though they are far too small to be seen by the highest powers of the microscope. The physical subdivision of every body is limited by the dimensions of its molecules; but the chemist can carry the process further. He "decomposes," or breaks up, these molecules into "atoms"; but the parts thus obtained have no longer the qualities of the original substance. Hence the molecule may be considered as the smallest particle of a substance in which its qualities inhere; and every molecule, though physically indivisible, can be broken up chemically into atoms, which are themselves the molecules of other and elementary bodies.