166 INOEGANIO AGENTS 



sulphate to an aqueous mixture of magnesia (see Ferri 

 Oxidum Hydratuin cum Magnesia, p. 196). 



Heavy Metals: Including Aluminum, Cerium, Plumbum^ 



Abgentum, Zinoum, Cupkum, Bismuthum, Fekbum, 



Manganum and Hydbabgyeum. 



.Aluminum. 



(The metal is not used as medicine.) 



Alumen. Alum. A1,K, (SOJ, + 24 H,0. (U. S. & B. P.) 



Synonym. — Potassium alum, aluminum and potassium 

 sulphate, sulphate of aluminium and potassium, E.; alun, 

 sulphate d'alumine et de potasse, Fr.; alaun, kalialaun, G. 



Derivation. — From alum slate, clay, shale or schist, a 

 native mixture of aluminium silicate and iron sulphide. 

 This is roasted and pxposed to the air, when the sulphur is 

 oxidized into sulphuric acid and combines in part with 

 aluminium and iron to form sulphates. The mass is 

 lixiviated with water, and aluminum and iron sulphates 

 together with sulphuric acid are recovered in solution. The 

 solution is concentrated and to it is added potassium 

 chloride. The double sulphate of potassium and aluminum 

 (alum) is formed, which crystallizes out on cooling, while 

 potassium sulphate and ferric chloride remain as bye- 

 products. Alum is purified by recrystallization. 



Properties. — Large, colorless, octohedral crystals, some- 

 times modified by cubes, or in crystalline fragments ; without 

 odor, but having a sweetish and strongly astringent taste. 

 On exposure to the air the crystals are liable to absorb 

 ammonia and acquire a whitish coating. Soluble in 9 parts 

 of water. It is also soluble in warm glycerin ; insoluble in 

 alcohol ; reaction acid. 



Incompatihles.-^lron, lead and mercury salts, alkalies^ 

 lime, tartrates and tannic acid. 



Dose.—E.. & C, 3ii.-iv. (8.-15.); Sh. & Sw,, gr.xx.- 3 i- 

 (1.3-4); D., gr.v.-x. (.3-.6); emetic, D., 3 i. (4.). 



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