Page:Popular Science Monthly Volume 10.djvu/656

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one inch to six feet six inches in thickness, number 46 in the Warrior and 51 in the Cahawba field. Two beds of black-band ore characterize the Warrior measures, one of them showing 43 per cent. of metallic iron; clay iron-stone is abundant, and is found in all the Alabama coal-fields. In one instance it forms the roof of a 28-inch bed of coal in the Warrior measures. Immediately under the mountain limestone of the carboniferous formation in the Upper Silurian, a bed of fossiliferous hematite occurs. It extends in a northern direction over 120 miles into Tennessee. In Jefferson County, Alabama, its thickness is 28 feet. About two or three miles east and west of this ore-bed lie the coal-fields. For its entire extent throughout the State, and immediately under it, are the limestones of the Silurian formation, among which are many of the purest and those best adapted for fluxing iron from its ores. Geologically, in descending order, next come the immense beds of brown ore, comprising manganiferous and fibrous limonite and mamillary and crystallized hematite, from which hitherto nearly all of the iron of Alabama has been produced.


The Physical Properties of Gallium.—The physical properties of gallium, as ascertained by its discoverer, Lecoq de Boisbaudran, who has prepared a decigramme of nearly pure metal, are summed up as follows in the American Journal of Science: Its fusing-point is about 29.5 Cent., so that the heat of the hand liquefies it. When liquid, it exhibits the phenomena of surfusion to a remarkable degree. It has remained liquid for more than a month, the globule being frequently broken and reunited by a steel blade in a room the temperature of which often fell below the freezing-point, Contact with a bit of solid gallium, however, solidified it at once. Liquid gallium is very mobile, appears covered with a pellicle when exposed to the air, and adheres strongly to glass. Only a few degrees below its fusing-point the metal is hard and remarkably tenacious; but, like aluminum, it may be cut with a knife. It crystallizes with facility, crystal facets being developed by treatment with hydrochloric acid. It does not oxidize at a red heat except upon the surface, and does not volatilize. Its spark-spectrum gives the two well-known bright lines of wave-length 417 and 403.1; its flame-spectrum only the 417 line, and this difficultly. Its density approximately is 4.7, thus placing it, like its other physical properties, between aluminum and indium. Its atomic weight places it there probably also.


Death of Karl Ernst von Baer.—The eminent Russian zoölogist, Karl Ernst von Baer, died at Dorpat, November 28th, in the eighty-fifth year of his age. He was born at Piep, in Esthonia, in 1792; at the age of eighteen he entered the University of Dorpat, graduating four years later as doctor of medicine. He then went to Germany, and, at Würzburg, became a pupil of Döllinger, the eminent professor of physiology and anatomy. This was the turning-point in Yon Baer's career, and determined the course of his future studies. In 1817 he became prosector at Königsberg, and, four years later, professor of zoology. In 1830 he returned home, having been elected a member of the St. Petersburg Imperial Academy. He conducted a scientific exploration of the northern shores of Russia in 1837. Of his most celebrated work, "The Development History of Animals," the first volume appeared in 1828 and the second ten years later. He was also the author of numerous treatises on the zoölogy and botany of Russia. His latest work was an adverse criticism on the Darwinian theory.


The death of Alexander Bain, which took place at Glasgow, January 2d, was cabled to this country, and at once interpreted as applying to the eminent Professor of Logic in Aberdeen University, who bears that name, and who is much more widely known here than Alexander Bain, the electrician, to whom the dispatch referred. He was an inventor, and made various important improvements in telegraphy. He invented, or reinvented, the method of making use of "bodies of natural waters to complete the electric circuit by laying a single insulated wire between the given stations, having at each end a metallic brush immersed in the water." This principle was promulgated in a patent of 1841. In 1846 he patented the electro-