Page:Popular Science Monthly Volume 48.djvu/389

Rh ; but some of the larger ones are very regular, and some of the smaller ones are more or less pyriform. Many of these are traversed by fine perlitic cracks. Together with the pellets are numbers of the vitreous scales which we have just mentioned. Some are perfectly smooth and uniformly transparent; while others contain bubbles and blisters, and have a rough surface. Sometimes innumerable little vitreous pellets are massed upon them, similar to those which form bunches like bunches of grapes on some of the finer hairs.

I do not think that the mixture of pellets with the slag threads spun accidentally near the nozzles of blowers in factories has been insisted upon. These little balls result from a special action of a gaseous medium; and it is important to remark that we can by their presence recognize the wind origin of the deposits that contain them. They have a bearing upon some observations of M. Gaston Tissandier, who has found similar globules in atmospheric sediments in very different localities. These spherules have evidently originated from the action of the air upon the fluid matter developed upon the surface of meteorites during their passage through the atmosphere. They should be formed in considerable numbers at every fall of meteors, and their small volume is favorable to their remaining suspended in the air for a long time, and to their being carried by the wind to considerable distances. This explains the quantities of them found in the ocean bottoms. All marine sediments that have been carefully examined yield globules of this kind; and, as is shown by the common researches of M. Tissandier and myself, they were equally abundant in the ancient geological seas. Thus, to cite an example that has struck us very forcibly, the green sand extracted from the artesian well of Passy, at five hundred and sixty-nine metres below the surface, and which is of the Albian (lower Cretaceous, Potomac group), is full of spherules as perfect as those which are extracted from the dust that has accumulated in the towers of the Cathedral of Paris.

The mechanism of the production of these globules is rendered very evident by their abundance in certain industrial residues, especially in the iron oxide produced by hammering, and in the product of the combustion of iron in oxygen. Evidently the melted oxide spread into laminas by mechanical projection goes through the same capillary action as gives their form to soap-bubbles. We can study all the details of the phenomenon with greater facility if we have recourse to substances much easier to melt than oxide of iron. I have had occasion to do this with the experimental products which M. Daubrée has asked me to