POTASSIUM. 259 



upon a boiling solution of potassium carbonate, to which calcium 

 hydroxide has been added : 



K 2 C0 3 + 6Ca(OH) 2 + 12C1 == 2KC1O 3 + OaCO 3 + 5CaCl 2 + 6H 2 O. 



Practically all potassium chlorate is manufactured now by electrol- 

 ysis of solutions of potassium chloride under proper conditions. 



Potassium chlorate crystallizes in white plates of a pearly lustre ; 

 it is soluble in 16.7 parts of cold, and 1.7 parts of boiling water. It 

 is even a stronger oxidizing agent than potassium nitrate, for which 

 reason care must be taken in mixing it with organic matter or other 

 deoxidizing agents, or with strong acids, which will liberate chloric 

 acid. When heated by itself, it is decomposed into potassium chloride 

 and oxygen. 



Potassium sulphate, Potassii sulphas, K 2 SO 4 = 173. 04. Ob- 

 tained by the decomposition of potassium chloride, nitrate, or carbo- 

 nate, by sulphuric acid : 



2KC1 + H 2 SO 4 = 2HC1 + K 2 SO 4 ; 

 K 2 C0 3 + H 2 S0 4 = H 2 + C0 3 + K 2 S0 4 . 



Potassium sulphate exists in small quantities in plants, and in 

 nearly all animal tissues and fluids, more abundantly in urine. 



Potassium hydrogen sulphate, bisulphafe, or potassium acid sulphate, may be 

 obtained by the action of one molecule of potassium chloride upon one mole- 

 cule of sulphuric acid : 



KC1 + H 2 SO 4 = HC1 -f KHSO 4 . 



Potassium sulphite. Obtained by the decomposition of potassium carbonate 

 by sulphurous acid : 



K 3 CO 3 + H 2 SO S = H 2 O + CO 2 + K 2 SO S . 



Potassium hypophosphite, Potassii hypophosphis, KPH 2 O 2 = 

 103.39, may be obtained by decomposing a solution of calcium hypo- 

 phosphite by potassium carbonate : 



Ca(PH 2 O 2 ) 2 + K 2 CO 3 = 2KPH 2 O 2 + CaCO 3 . 



The filtered solution is evaporated at a very gentle heat, stirring 

 constantly from the time it begins to thicken until a dry, granular 

 salt is obtained, which is soluble in 0.5 part of cold and 0.3 part of 

 boiling water. 



Potassium iodide, Potassii iodidum, KI = 164.76, is made by 

 the addition of iodine to a solution of potassium hydroxide until the 

 dark-brown color no longer disappears : 



6KOH + 61 = 5KI + KI0 3 + 3H 2 O. 



