39 8 THE POPULAR SCIENCE MONTHLY. 



and this, in turn with its earthy appearance, is oxide of aluminum. 

 This metal, therefore, constitutes nearly a sixth part of the soil 

 on which we spend our lives. The most abundant of all the 

 metals, it is at the same time the one that is nearest to us. Thus 

 alumina, and consequently aluminum, is literally under our feet 

 clay, of which it is the principal component, being found nearly 

 everywhere. Rarely, and scattered in the masses of the rocks, 

 precious gems may be found emeralds, amethysts, sapphires, 

 rubies, and topazes which are only alumina, nearly pure in 

 corundum, but alloyed with a little magnesia or lime in spinel. 



It was not till modern chemistry was born that it became pos- 

 sible to separate aluminum from its earth. Carbon, which had 

 been the chief agent for isolating the known metals from oxy- 

 gen, was not effective in separating the elements of alumina ; and 

 even the electrical process with which Sir Humphry Davy pro- 

 duced sodium and potassium failed here. A roundabout process 

 was devised. Oersted converted the intractable oxides of alu- 

 minum and magnesium, also not yet conquered, into chlorides, 

 and Woehler decomposed them with potassium, taking advantage 

 of the superior affinity of that metal for chlorine. Applying 

 potassium to chloride of aluminum in the crucible, he obtained 

 metallic aluminum and chloride of potassium. It appeared as a 

 grayish dust, with a few globules, the largest of which was not 

 bigger than a pinhead. From this small quantity only an incom- 

 plete determination of the properties of the element could be 

 made. A more exact description was reserved for Henri Sainte- 

 Claire Deville, who repeated Woehler's experiment in 1854. For 

 the rare, expensive, difficult, and somewhat dangerous potassium 

 he substituted sodium, which he found a simple method of ex- 

 tracting from sea salt ; and instead of clay, the use of which re- 

 quired a preliminary separation of the silica and the alumina, he 

 employed hydrated alumina, known as bauxite, of which consid- 

 erable beds were worked in France for the manufacture of alum. 

 Under the direct action of chlorine, a mixture of bauxite and sea 

 salt became a double chloride of sodium and aluminum. The 

 addition to this mixture, at the melting point, of the proper quan- 

 tity of sodium, caused a separation of the aluminum, which col- 

 lected in the bottom of the crucible. By remelting, the metal was 

 cleared of most of its impurities and greater cohesion was given 

 to its molecules, so that it could be cast into ingots. All this in- 

 volved great expense, and the investigation could not have been 

 effectively continued had not Napoleon III come to the chemist's 

 aid with some of the unlimited funds of which he had the con- 

 trol. The next year, June 18, 1855, Jean Baptiste Dumas presented 

 to the Academy of Sciences the first ingot of aluminum made in 

 an industrial shop. 



