POTASSIUM. 117 



Liquor potassce is a 5 per cent, solution of the potassium 

 hydrate in water. 



Potassium carbonate, K 2 C0 3 = 138, Potassii carbonas, TJ. S. P., 

 (K 2 C0 3 ) 2 3H 2 = 330 (Carbonate of potassium), is obtained from 

 ashes in an impure state as described above, or from the 

 native chloride by the so-called Leblanc process, which will be 

 described in connection with sodium carbonate. Crude potash 

 when calcined in a furnace until white is known as pearlash. 



Potassium carbonate is very deliquescent, is soluble in an equal 

 weight of water, and has strong basic and alkaline properties. 



Potassium bicarbonate, Potassii bicarbonas, KHC0 3 = 100 (Bi- 

 carbonate of potassium}. Obtained by passing carbon dioxide 

 through a strong solution of potassium carbonate, when the less 

 soluble bicarbonate is formed and separates in crystals : 



K 2 CO 3 + H 2 O + CO 2 = 2KHC0 3 . 



Potassium nitrate, Potassii nitras, KN0 3 = 101 (Nitre, Saltpetre). 

 Potassium and sodium nitrate are found as an incrustation upon 

 and throughout the soil in certain dry and hot countries, as, 

 for instance, in Peru, Chili, and India. The formation of these 

 nitrates is to be explained by the absorption of ammonia 

 (present in the atmosphere) by the soil, where it is gradually 

 oxidized and converted into nitric acid, which then combines 

 with the strongest base present in the soil. If this base be pot- 

 ash, potassium nitrate will be formed; if soda, sodium nitrate; 

 if lime, calcium nitrate. 



Upon the same principle is based the manufacture of nitre on 

 a large scale, which is accomplished by mixing animal refuse 

 matter with earth and lime, and placing the mixture in heaps 

 under roof, to prevent lixiviation by rain. By the decomposi- 

 tion (putrefaction) of the animal matter, ammonia is formed, 

 which, by oxidation, is converted into nitric acid, which then 

 combines with the calcium of the lime, forming calcium nitrate. 

 This is dissolved by water, and to the solution potassium car- 

 bonate (or chloride) is added, when calcium carbonate (or chlo- 

 ride) and potassium nitrate are formed : 



Ca2XO 3 -f K 2 CO = 2KNO + CaCO. 



