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Page:Popular Science Monthly Volume 32.djvu/150

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THE POPULAR SCIENCE MONTHLY.

the earlier years of this century, and whose surface was estimated at five hundred and thirty square miles, only three small ponds have remained. Even twenty-five years ago there were several lakes, ten and eight miles long and wide, where there are now but little ponds. The fate of Lake Abyshkan is substantially repeated in Lake Chebakly, which was represented in 1784 as an oval body forty miles long and three miles wide. Now, the largest of the three ponds which occupy its site is less than two miles wide. The same process is going on throughout the lakes of West Siberia and throughout the Aral-Caspian depression.

 

Electric Deposition of Dust.—Professor Tyndall observed, in 1870, that when a hot body was held in strongly-illuminated, dusty air, a dust-free space was formed above it, and this may take place even when the body is only slightly warmer than the air. Several hypothetical explanations of the phenomenon have been offered by Dr. Tyndall, Dr. Frankland, and Lord Rayleigh, but they have been inadequate to meet the requirements of the case. Professor Oliver Lodge has sought an explanation by the application of the kinetic theory of gases, and supposes that the dust-particles are kept out of contact with the warm body by means of a differential molecular bombardment of their surfaces. On the other hand, with the singular and not explained exception, that a similar dark plane, but descending, is formed below a moderately cool body, the dust-particles are driven toward, instead of away from, a cold body. This fact has been observed by Mr. Aitken, and applied by himself to the explanation of the deposition of soot in chimneys, and of lamp-black on cold glass. The result of the dust-bombardment of cold bodies may also be seen in the blackening of a wall over hot-water pipes, or of a ceiling over a gas-jet. Smoking of the gas-jet will, of course, provide more material to be deposited, but the dust and smoke in the air are usually ample to effect a sufficient blackening over even a perfectly clear flame. An incandescent electric lamp, hung a foot or so under a white ceiling, will similarly cause a small, black patch. In rooms warmed by radiation, objects are warmer than the air, and keep much dust off themselves. In stove-heated rooms, things are liable to be colder than the air, and thus get exceedingly dusty. Professor Lodge supposes, also, that electrical conditions may have much to do with the matter, and relates several experiments which he has made that go to confirm this view. One of them is made with a minute, vertical water-jet, which usually scatters into drops and falls in a shower-like rain; but hold a piece of rubbed sealing-wax a yard or so distant from the place where the jet breaks, and the drops at once cease to scatter, but fall in large blobs, as in a thunder-shower. These principles are susceptible of application in many processes where dust is generated in quantities that make it a nuisance for laying it. Thus, chimney-flues may be fitted with spikes or wire nettings, which will cause the smoke to be condensed, and the dust to be deposited. So, on a larger scale, the introduction of electrical action into a cloud is supposed to give rise to rain.

 

Origin of Strong Liquors.—Strong liquors are a modern invention. The ancients knew of nothing more powerful than lightly fermented wines, and have left warnings enough of the abuse of them. Alcohol was not discovered till the seventh century, although an older story exists of a monk, Marcus, who collected and condensed in wool the steam of heated white-wine, and then pressed out from the wool a balsam which he applied to the wounds of those who fell at the siege of Rheims, in the reign of Clovis I. He also mixed this balsam with honey, and produced a cordial which brought the moribund back to life. Clovis, however, did not wait for the approach of death, before claiming his share of the cordial. According to Dr. Stanford Chaille, the distillation of spirits from wine was not discovered till the twelfth century, and spirits did not come into common use as drinks until the fifteenth, sixteenth, and seventeenth centuries. Professor Arnoldus de Villanova, in the fourteenth century, made a panacea of the water-of-life, which gave sweet breath, and fortified the memory, besides being good for sore eyes, the toothache, and the gout, and having other