POTASH. 



201 



ORDER III. POTASH. 



1. Sulphate of Potash. 



2. Carbonate of Potash. 



3. Muriate of Potash. 



4. Hydrobromate of Potash. 



5. Alum. 



SULPHATE OF POTASH. 



Potasse Sulfatee. Havy. — Aphthalose. Beudant. 



This salt has been found in some mineral waters, and was formerly thought to be one of 

 the ingredients of the Salina brine. It also occurs among the products of volcanoes. 



Fig. 23. 



Fig. 24. 



Fig. 25. 



Description. Colour white. 

 Taste slightly bitter. It crys- 

 tallizes from its solution in 

 the form of the right rhombic 

 prism, which is the primary. 

 Fig. 23. M on M' 118° 8' 

 {Beudant. ) It also occurs in 

 short six-sided prisms termi- 

 nated by six-sided pyramids. 

 Fig. 24 ; and in dodecahe- 

 drons. Fig. 25. It does not 

 contain water, and suffers no change on exposure to the air ; decrepitates when heated, and 

 enters into fusion at a red heat. 100 parts of water dissolve 8.3 of the salt at 32° Fahr., 

 and 25 parts at 212° Fahr. Specific gravity 2.40. 



The solution of this salt causes a yellow precipitate when treated with chloride of plati- 

 num, by which it may be distinguished from the sulphate of soda, and indeed from all the 

 salts of that alkali. 



Composition. Sulphuric acid 45.95, potash 54.07 (JBewdan^.) Formula KO.SO3. This 

 salt, as well as the bisulphate of potash, is procured in large quantities in the manufacture of 

 sulphuric and nitric acids, where nitrate of potash is employed. 



CARBONATE OF POTASH. 



This salt has been found in the water of certain springs, but only in very small quantities. 

 It is introduced here chiefly for the purpose of directing the attention of future observers to 

 ascertaining whether it exists in our waters. 



Carbonate of potash ejtists in the ashes of plants, and, mixed with small proportions of 

 other salts, constitutes the Potash and Pearlash of commerce. Formula KO.CO. 



MiN. — Part II. 26 



