338 acids. 



in small fragments, efflorescent on the surface, and of a pale rose 

 colour. Alum is decomposed by the alkalies and alkaline earths, 

 which precipitate the alumina ; and gallic acid produces the 

 same effect. 



Alum is used in medicine as a powerful astringent, and is not 

 unfrequently prescribed both as an external and internal remedy 

 for restraining hsemorrahgies and serous evacuations ; it is thus 

 given in obstinate diarrhoea, menorrhagia, leucorrhcea, and 

 diabetes. It has also been employed in combination with cin- 

 chona in intermittent fevers, and conjoined with opium as a pro- 

 phylactic in colica pictonum. The dose, in substance, is from 

 five grains to half a drachm. If it excite nausea or vomiting, or 

 operate as a cathartic, this inconvenience may generally be ob- 

 viated by combining it with an aromatic. A favorite and very 

 efficacious form of administering it, is that of alum whey (serum 

 aluminosum), prepared by adding two drachms of pulverised alum 

 to a pint of hot milk ; the dose of this is three or four ounces. 

 Externally, alum is used in gargles in cases of cynanche, relax- 

 ation of the uvula, and aphthous ulcerations of the mouth ; as an 



r 



injection in the latter stages of gonorrhoea, leucorrhcea, and profuse 

 menorrhagia; and as a lotion in chronic ophthalmia, hsemorrhoidal 

 affections and prolapsus ani. Burnt alum is sometimes used by 

 surgeons as a mild escharotic. 



Order IV.— SALINE MINERALS. 



Under this class are included the mineral acids, and 

 their combinations with the earths, alkalies, and metallic 

 oxides. They are distinguished by their solubility in 

 water, and sapid taste. 



Genus I.— ACID. 



Sp. 1 . Carbonic Acid. — Spiritus Lethalis, Pliny. Gas Syl- 

 vestre, Spiritus Sylvestris, Paracelsus and Van Helmont, Fixed 



