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Page:Popular Science Monthly Volume 57.djvu/309

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299
PHASES OF THE EARTH'S DEVELOPMENT.

hydro-carbon. Aluminum carbide yields alumina and methane (marsh gas), another hydro-carbon, the chief constituent of 'natural gas.' Other carbides yield crude petroleum. The nitrides yield ammonia, which is the hydrogen composed of nitrogen. The chlorides give hydrochloric acid, the sulphides sulphuretted hydrogen and the silicides the hydrogen silicide. The metallic hydrides yield free hydrogen.

The violence and the magnitude of some of these reactions almost baffle the imagination. Let the reader drop a piece of calcium carbide as large as a small marble into a little water in a cup; there is a rapid action, a gas (acetylene) is given off, which burns with a smoky flame if a lighted match is held over the cup. (The experiment should be tried in the open air.) So much heat is generated in the reaction that the cup becomes hot. Nearly four per cent, of the earth's outer crust is calcium; all this was at this period of the earth's history in the form of carbide. Imagine all the vast limestone mountain ranges of the present day as carbide, and try to realize the effect when water fell on any considerable area. The heat generated would be so enormous that in a moment the acetylene would ignite and burn, forming oxides of carbon and water vapor, which would in turn decompose, throwing the jets of glowing hydrogen and oxygen vast distances into the atmosphere, there to cool and reunite to water. The decomposition of other carbides, of the hydrides and silicides, as well as-the formation of hydroxides by the action of the lighter metals on water, would produce similar phenomena, as the substances formed are combustible gases, or liquids or solids easily volatilized. This is no wild fantasy, but a conservative statement. Similar reactions are taking place at the present day in those stars whose cooling process has advanced far enough; a case in point is that of the so-called 'temporary stars.'

Extremely violent reactions are taking place constantly in the atmosphere of the sun. The sun's chromosphere, or outer layer of its atmosphere, consists mainly of hydrogen, and jets of glowing hydrogen are thrown to great heights above the chromosphere; these jets or 'prominences' have been frequently observed to have a height of 100,000 miles, and prominences of more than double this height are reported by observers. The most conservative estimates assume temperatures of the sun's surface so enormous that that of the electric furnace is insignificant in comparison, and we can have no conception of the chemical changes occurring under such conditions. Whether one believes, with Lockyer, that the chemical 'elements' are disassociated by the sun's heat into simpler substances or not, it is clear that very violent chemical reactions are in progress, and if we realize that the known chemical reactions increase in intensity with increase in temperature, it does not seem strange that at the sun's temperature the reactions occurring should cause disturbances like those observed.