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Page:Popular Science Monthly Volume 56.djvu/297

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ence. The true scientific spirit prompts to thorough inquiry; it will have nothing to do with hasty generalizations that may glitter but do not convince; it puts a restraining hand on all immature conclusions, and demands, above all else, careful, thorough observation. It shuns all shams. Good, honest work is the only passport to the domain of science.


Constitution of the Funafuti Atoll.—In the boring of the coral atoll of Funafuti, Professor David, of the University of Sydney, reached a depth of 697 feet, and a subsequent boring was made down to about 1,000 feet. The core obtained by the David party was sent to England and placed in the hands of Professor Judd for investigation. The general statement is made respecting it that the material brought up presents much the same character throughout, and so far is regarded as supporting Darwin's theory. There are no layers of chalky ooze, such as Murray's hypothesis might have made possible, and no trace of volcanic material has been found. The later boring beyond 700 feet passed through a hard limestone containing many well-preserved corals. In a boring of the bed of the lagoon down to 144 feet, after passing through 101 feet of water, the first 80 feet below were found to consist of the calcareous alga Halimeda mixed with shells, and the remaining 64 feet of the same material mixed with gravel.


Metallic Calcium.—Metallic calcium, as prepared by Professor Moissan from solution in liquid sodium, separates in hexagonal crystals which have a specific gravity of 1.85 and melt at 760° in vacuo. On solidifying, the metal is somewhat brittle, is less malleable than potassium and sodium, and shows a crystalline fracture. When free from nitride it is silver-white in color, and has a brilliant surface. Heated to redness in a current of hydrogen, a crystalline hydride, CaH2, is formed. When pure, calcium is not acted upon at ordinary temperatures by chlorine, though at 100° C. the action is decided. But if the metal contains nitride, chlorine attacks it at the ordinary temperature. At 300° C. calcium ignites and burns brilliantly in oxygen. Gently warmed in air, it burns with brilliant scintillations. It combines with sulphur, with incandescence, at 400° C. At a red heat it unites actively with lampblack, giving a carbide, CaC2. It gives some brittle alloys with magnesium, zinc, and nickel. The alloy with tin slowly decomposes water. A crystalline amalgam is formed with mercury, which may be distilled in hydrogen at 400° C, but which forms nitride when heated in nitrogen. Heated to redness with potassium or sodium chloride, calcium sets the metal free. Water acts on calcium only very slowly, with the evolution of hydrogen. In liquefied ammonia at-40° C. calcium ammonia is formed—a reddish-brown solid.


Prosperity and Enterprise in Mexico.—The increasing prosperity of Mexico is one of the striking features of current history. In four years the imports of the country increased from $30,000,000 in 1894 to upward of $45,000,000 in 1898, the average for five years having been $40,000,000. The chief sellers to Mexicans are the United States, Great Britain, France, and Germany, and the keenness of the competition for trade is shown in the fluctuations in the relative shares of it of the several countries. Spain has a small share of trade, which is growing. Industrial enterprises are being developed throughout the country with energy, enterprise, and success. Cotton and linen factories have been established, attention is given to the erection of woolen mills, and a noticeable activity prevails in mining industries. Under all these influences the railroads are prospering too.


A Question of Economy.—A paper, "Shall we grow the Sugar that we consume?" by Freeman Stewart, called out by an article by ex-Secretary Wilson, besides matter bearing directly on the question, embodies observations on general political principles. Thus, it seems necessary to observe "that the idea that republicanism requires our public officials to act as mere weathercocks for the transient waves of popular clamor and excitement is also a deplorable delusion, which, if persistently carried into effect, will soon utterly destroy republicanism. As free institutions depend on