28 MATER i A MEDIC A AND THERAPEUTICS. 



From PotasscB Carbonas are made : 



a. Potassse Eicarbonas. Bicarbonate of Potash. 



KHCOg. 



Source. Made from a solution of the Carbonate in 

 distilled water, by passing a stream of carbonic acid gas 

 through it, and purifying the crystals which form. 



Characters. Colourless right rhombic prisms, not 

 deliquescent; of a saline, feebly alkaline taste; not cor- 

 rosive. 20 gr. neutralise 14 gr. of citric acid, or 15 gr. of 

 tartaric acid. 



Dose. 10 to 40 gr. 



Preparation. 



Liquor Potassae Effervescens. Potash Water. 

 Potasspe Bicarbonas, 30 gr.; Water, 1 pint. Dis- 

 solve, and pass into the "solution as much C0 2 as 

 it will contain under a pressure of 7 atmospheres. 



Dose. Ad libitum. 



j. Liquor Potassse. Solution of Potash, KHO, 

 (5'84 per cent.) in water. 



Source. Made from a solution of the Carbonate, 

 by boiling with Slaked Lime and purifying. K 2 C0 3 + 

 CaO,H 2 = 2KHO + CaC0 3 . 



Characters. A clear alkaline fluid. 



Impurities. Lime, carbonates, sulphates, and chlo- 

 rides. 



Dose. 15 to 60 min. 



From Liquor Potassce are made : 



a, Potassa Caustica. Caustic potash. KHO. 



Source. Made from Liquor Potassae by evapo- 

 ration. 



Characters. White pencils, hard but very 

 deliquescent, alkaline and corrosive. 



Impurities. The same as of the liquor. 



From Potassa Caustica is made : 



Potassss Permanganas. Permanganate 

 of potash. KMnO 4 . See Manganesium. 



Source. Prepared from a mixture of caustic 

 potash, chlorate of potash, and black oxide of 

 manganese, by semi-fusing ; then boiling, neutra- 

 lising with dilute sulphuric acid, and purifying. 

 (1) KClOo + 6KHO + 3Mn0 2 = 3K.,MnO 4 + 

 KC1 + 3H 0. (2) Boiling: 3K 2 MnO 4 + 

 2H 2 = 2KMn0 4 + 4KHO -f Mn0 2 . 



