PHASES OF THE EARTH'S DEVELOPMENT. 299 



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 car- 

 bides, 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 pres- 

 ent 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 atmos- 

 phere 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 insig- 

 nificant 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 reac- 

 tions 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. 



