scribed its preparation by the action of chlorine on silver nitrate, and its properties. The possibility of the existence of monobasic acid anhydrides had previously been disputed. In 1852 he published in the "Annales de Chimie et de Physique" an important paper upon the metallic carbonates and their combinations, and in 1853 he discovered a new method of mineral analysis. In 1855 he began the famous research on metallic aluminium, which proved, says his biographer in "Nature," to be one of the crowning features of his life-work. He was furnished the means by which he was enabled to carry his experiments to success by Napoleon III, who was looking forward to the application of the qualities of a metal of so light a specific gravity to the making of armor and helmets for the French cuirassiers. The anticipation proved to be a mere dream, and impracticable; but the ambition in which it was bred was caused for once to minister to the lasting benefit of mankind. With the means thus furnished, M. Deville was able to carry on his experiments on a large scale, and so rapidly that even in the same year in which he began he displayed at the exhibition in Paris massive bars of the metal, that had hardly been seen before in a pure state. The study of this metal and of its metallurgical production, as well as of the various compounds of aluminium, carried out during a series of years, forms, says "T. H. N." in "Nature," one of the most remarkable and complete contributions made to inorganic chemistry within a recent period. The metal is now prepared in one English and two French establishments according to Deville's perfected process, which consists essentially in heating the double salt (chloride) of aluminium and sodium with metallic sodium, fluor-spar or cryolite being added as a flux, and is used for a variety of objects where lightness, strength, and freedom from oxidation are demanded, and in many valuable alloys, of which it forms the essential part. It has not come into as extensive use as Deville hoped it might, for it is still too high in price and is hard to weld. The operations with aluminium have resulted in building up other industries, such as the production of bauxite and cryolite, and the manufacture of metallic sodium, the price of which sank in ten years from two thousand francs to fifteen francs per kilogramme. In 1863 M. Deville, in connection with Caron, applied his aluminium method to the manufacture of magnesium, and made it possible to produce that metal in commercial quantities. With Debray he carried on exhaustive researches from 1859 to 1862 on the metals of the platinum group, in which be applied the oxyhydrogen blow-pipe on a large scale to the fusion of platinum, now for the first time accomplished. This led him to operations at higher temperatures than had ever before been attained, except perhaps casually, involving the artificial production of crystalline minerals, which has since been carried out by other chemists to a larger extent, and numerous determinations of the vapor densities of bodies that are ordinarily solid, like the chlorides of aluminium, iron, and va-
