33G SALTS OF BARYTES. 



concretions, which have a striated or diverging flat fibrous struc- 

 ture. It is translucent or semi-transparent, and has generally a 

 yellowish or brownish-white colour. It has a shining or glimmer- 

 ing lustre, and the fracture is resinous. It is brittle, and easily 

 frangible. The specific gravity is about 4*30. Before the blow- 

 pipe it decrepitates slightly, and melts into a white enamel. It dis- 

 solves with effervescence, in dilute muriatic or nitric acid. Its 

 constituent parts are, barytes 78, carbonic acid 22. It occurs in 

 lead-veins in several of the mining districts of England and 

 Wales. It is a very active corrosive poison, and in Lancashire and 

 Yorkshire, where it is found, it is used for the purpose of destroy- 

 ing rats. Fifteen grains is reported to have killed one dog in eight 

 hours, and another in fifteen.* 



Salts of Barytes. 



The soluble salts of barytes are characterised by their acrid nau- 

 seous taste, and by the copious precipitate which sulphuric acid 

 throws down when it is added to their solutions. The only com- 

 pound of this salt applied to medical purposes, is the muriate or 

 hydro-chlorate. 



Muriate of Barytes. — This salt may be prepared by adding 

 dilute muriatic acid to the carbonate of barytes, and evaporating 

 the solution, or by decomposing the sulphate by heating it with 

 charcoal, and adding muriatic acid to the solution obtained by 

 washing the residue with water. The muriate in either case is 

 procured by crystalization, and a formula is given for its solution in 

 the Edinburgh Pharmacopoeia, in which one part of the salt is 

 dissolved in three of water. This solution is stimulant, and in 

 large doses poisonous; but it has been strongly recommended by 

 some practitioners as a remedy in cancer, in some obstinate 

 cutaneous eruptions, and in scrofula, under the appellation of a 

 deobstruent. The usual dose is from five drops, gradually increased 

 to twenty or more. 



When taken in an over-dose, the pure earth or oxide, the car- 



* Annates de Chimie, xxi. p. 119. 



