Aluminum, Chloride of

Al 2 Cl 6 . Syn. Sesquichlo′′ride of Aluminum ; Alumin′ii Chlori′di , ., L. Prep. A thick paste made of dry precipitated alumina, lampblack, and oil, is strongly heated in a covered crucible until all the organic matter is carbonised. The residuum is transferred to a porcelain tube fixed acro a furnace, one end of which is connected with another tube containing dry chloride of calcium, and the other end with a small tubulated receiver. The porcelain tube is then heated to redne , whilst chlorine, dried by pa ing through the chloride-of-calcium tube, is transmitted through the apparatus. In one or two hours, or as soon as the tube is choked, the whole is allowed to cool, and the newly-formed SESQUICHLORIDE collected and preserved in mineral naphtha for use. On the large scale:—Chlorine, dried as before, is pa ed over a mixture of pure clay, lamp-black, and coal-tar, contained in an iron retort, similar to that used in the manufacture of coal-gas (previously ignited by means of a suitable furnace), and connected with a cool chamber accurately lined with tiles of earthenware. The vapours of the SESQUICHLORIDE condense in this chamber, as a yellowish crystalline ma , which is collected and preserved as before. Prop., . It is volatile at a dull red heat; exce ively greedy of moisture; and very soluble, with decomposition, hydrochloric acid and alumina being formed. Once di olved, it cannot be again recovered. Its chief use is in the preparation of aluminum. Obs. Although alumina, like magnesia, is freely soluble in hydrochloric acid, the sesquichloride of aluminum contained in this solution cannot be obtained in the anhydrous state, or even the solid form, by its evaporation; the chloride suffering decomposition, with the formation of hydrochloric acid, which is volatilised, and alumina, which is left behind.