ALUMINIUM. 



BARIUM. Ba. 137. 

 Barium is chiefly used in testing. 



Chloride of Barium, BaCl 2 .2H 2 O. 

 Characters. Colourless translucent tables. 

 Dose. to 2 gr. 



Solution of Chloride of Barium, 1 in 10. 



57 



ACTION AND USES. 



Baryta greatly disturbs the blood pressure, and the 

 chloride has accordingly been recommended in aneurism. 



GROUP II. 

 THE METALS. 



ALUMINIUM. Al. 27-5. 

 Only one salt of this metal is used in medicine. 



Alumen. Alum. NH 4 A1(S0 4 ) 2 .12H 2 0. A sulphate 

 of ammonia and alumina, crystallised from solution in water. 



Characters. Colourless transparent octahedra, with an 

 acid, sweetish, astringent taste. Solubility, 1 in 12 of cold, and 

 in *th parts of boiling water. Incompatible with alkalies, liine, 

 barytas, lead, tartrates, and tannic acid, mercury, and iron. 



Impurity. Sulphate of Iron. 



Lose. 10 to 20_gr. 



From Alumen is made : 



Alumen Exsiccatum. Dried Alum. 



Source. Made by heating alum up to 400 till 

 aqueous vapours cease to be disengaged, and powdering. 



Characters. An opaque white bulky powd< 

 spongy masses. Has lost 47 per cent, by heating ; diili- 

 cult of solution in water, but unites readily with it. 



ACTION AND USES. 

 1. IMMEDIATE LOCAL ACTION AND USES. 



Externally. Alum is astringent, an effect which is fully 

 discussed under Plumbum. The dried alum absorbs water, and 



