Page:Popular Science Monthly Volume 54.djvu/532

514 and interesting evidence a geologist deduced the hypothesis that the crater known as Coon Butte could have been produced by a meteor with a diameter of fifteen hundred feet, and a careful examination with a view of discovering it was made with nicely adjusted magnetic



instruments; but in no instance did they indicate the presence of a vast body of metal buried in the earth, and it was assumed that the striking of the crater by the colossal meteorite was a chance blow.

The meteorites or foreign bodies which bombard the earth may be included in three classes—meteoric irons or aërosiderites, meteoric iron stones or aërosiderolites, and meteoric stones, aërolites—all containing elements, about twenty-five in number, which have been found upon the earth. The most conspicuous and important are silicon, iron, nickel, magnesium, sulphur, carbon, and phosphorus, while the others are aluminum, antimony, arsenic, calcium, chlorine, chromium, cobalt, copper, hydrogen, lithium, manganese, oxygen, potassium, sodium, tin, and titanium. Hydrogen and the diamond have also been observed. A number of interesting chemical compounds are found in meteorites not known on the earth, and a study of their character shows that the conditions under which the meteors were formed were entirely different from those which saw the beginning of things terrestrial. In brief, where meteors were born there was an absence of air and water. On the other hand, there was at some stage in the history of meteorites an abundance of hydrogen. The meteoric irons are made up principally of iron with an alloy of nickel, and show a rich crystalline structure, the