126 ALUMINIUM 



iwlution is then filtered, and the flltrato evaporated to dryness. The salt is thus 

 obtained as a -whitish powder. See BAUXITE. 



AXiTTMXOTTB. See WKBSTEBITE. 



ALUMINIUM. (Sym. Al., at. wt. 137.) The name Aluminium is derived 

 from the Latin alwnen, for alum, of which salt this metal is the notable constituent. 



Aluminium, though never found in the free state, occurs extensively diffused in 

 nature in alumina and certain of its salts, especially the silicates. 



The native varieties of anhydrous alumina are, the sapphire, ruby, and corundum, 

 whilst the hydrate occurs in nature in tho minerals, diaspore ajd gibbsite. But the 

 chief quantity of aluminium is found in tho endless varieties of the mineral silicates 

 of alumina with other bases, such as the felspars, micas, many kinds of clay, the 

 zeolites, &c. 



Alumina was first decomposed by Davy, who discovered the metal soon after 

 decomposing the other earths and alkalis ; but ho never seems to have obtained it 

 without some mixture of potassium. It is evident, however, that the earth was 

 completely reduced to the metallic state by him. 



Wohlor obtained aluminium pure in 1827 ' by the reduction of the chloride 

 of aluminium in the form of a grey powder. Later (1845), 2 he succeeded by the 

 same process in obtaining it in globules, which he describes as tin whito, toler- 

 ably malleable and ductile, not materially oxidised by exposure to the air, of a 

 specific gravity of 2'5, but, when hammered, of 2'67 ; unacted upon by water at 

 the .common temperature, but slowly disengaging hydrogen from water at the 

 boiling point. 



In 1854 8 Deville's first experiments on the preparation and properties of alumi- 

 nium were published. Tho method he adopted for the liberation of the metal was 

 essentially the same as that originally employed by Wohler. But, by dint of im- 

 provements in the details of the process, he succeeded in procuring the metal in 

 larger globules, which were silver-white, having a fusing point nearly approaching 

 that of silver, which were unoxidised when exposed to the air, even in a fused state, 

 and remaining bright even in boiling water, unattacked by either dilute or concentrated 

 nitric or sulphuric acid in the cold ; but dissolved by hydrochloric acid with evolu- 

 tion of hydrogen. 



Oersted was undoubtedly the first to prepare the chloride of aluminium, 4 and it is 

 even stated that he also procured the metal by the following method : ' Pure 

 alumina, intimately mixed with powdered charcoal, was introduced into a porcelain 

 tube ; through this, when strongly heated, a stream of chlorine was directed, and the 

 chloride of aluminium formed was collected in a separate vessel. By mixing this com- 

 pound with an amalgam of potassium, containing a large proportion of the latter 

 body, and immediately heating the mixture, chloride of potassium was found, and the 

 aluminium combined with the mercury. This, on being distilled out of contact with 

 the air, gave off the mercury, whilst aluminium remained in the form of a metallic 

 button, closely resembling tin.' * . 



Deville's researches raised the hope that the metal might be obtained in sufficient 

 quantity to become of high technical importance, since ifc was probable that tho 

 chloride of aluminium might be decomposed by cheaper metals at a higher tempera- 

 ture ; and he obtained a grant from the late Emperor of the French for the purpose 

 of prosecuting his investigations on a sufficient scale. 



Bunsen also showed in 1854 6 that aluminium could be obtained in reguline masses 

 by submitting the double chloride of aluminium and sodium or potassium to electro- 

 lysis in a fused state. 



By fusing the chloride of aluminium (obtained by the process which will bo found 

 described under the head of the chloride) with an equal equivalent of common salt, 

 he obtained a double chloride, which fused below 200 C. (360 F.), and from which 

 the metal is readily reduced by the same electrolytic process previously employed by 

 Bunsen in the case of magnesium. See MAGNESIUM. 



Bunsen pointed out that the discrepancy existing in the properties of the metal in 

 the two states, as obtained respectively by Wohler and Deville, arose from its physical 

 condition ; for Bunsen found that it was only the massive metal which possessed the 

 properties ascribed to it by Deville, that in fact the pulverulent modification does 

 decompose water at 100 C., as stated by Wohler. 



Almost at the same time Deville published the results of his experiments upon the 

 production of aluminium on a larger scale.' He quite gave up the hope of succeeding 



' Poggondorff's Annalen, xl. 146. " Ann. Ch. et. Fharm. liii. 422. 



* Comptea Rendus, xxxviii. 279. 

 * Fenissai, Bui. des. Sc. Mathemat. &c. 1826, 278. 

 Record of Mining and Metallurgy, Phillips and Darlington. 

 Fogg. Aim. xcii. 618. ' Compiles Rendus, ynriY. 321. 



