Page:Popular Science Monthly Volume 17.djvu/362

348 of snow-water collected at the height of 8,800 feet on Mont Blanc (Fig. 4). Since I have called attention to the existence of these ferruginous bodies in the air, several men of science have confirmed my observations, particularly M. Yung, of the University of Geneva, and MM. Schoenaur and Pierre Miquel, who have pursued the study of the



air-dust at the observatory of Montsouris under the direction of M. Marie-Davy.

Whence are these ferruginous particles derived? The spherules have been melted: we can prove this by burning particles of iron and observing them under the microscope (Fig. 5); those which fly off on the striking of a flint are like them (Fig. 6). The spherules we are considering are probably derived from the showers of fire that escape



from incandescent meteorites. I have been confirmed in this view by observing with the microscope the crust of the aërolites in the collection of the Museum of Natural History, in which were perceived rounded grains having considerable resemblance to those we have just noticed. Moreover, the magnetic particles withdrawn from atmospheric sediments have given on analysis reactions indicating the presence



of nickel; of a character, consequently, to cause them to be regarded as partaking of the nature of meteorites. It may be objected that metallurgical operations and the production of oxides in iron-works give rise to similar ferruginous corpuscles. This is true; but how can we explain the presence of the spherules in geological formations that have not been worked over, where they must have been left previous to the existence of man on the earth? M. Stanislaus Meunier and I have found in the grits below the Lias, in the micaceous slates of the