=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, CaH_{2}, 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, CaC_{2}. 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.