FIXED ALKALIES AND ALKALINE EARTHS. 



Berzelius took another method of determining 

 the composition of potash. He placed a quan- 

 tity of amalgam of potassium in water ; the 

 amalgam was speedily decomposed, the potas- 

 sium being converted into potash, and dissolving 

 in the water, while the running mercury re- 

 mained behind. The potash thus formed was 

 saturated with muriatic acid, the liquid evapo- 

 rated to dryness, and the residual salt weighed. 

 The difference between the weight of the amal- 

 gam and of the running mercury remaining, 

 gave the weight of the potassium ; while the 

 weight of the muriate of potash formed, fur- 

 nished the data for determining the weight of 

 the potash. It is obvious, that the difference 

 between the weight of the potassium and the 

 potash, was the quantity of oxygen with which 

 the potassium had combined. This experiment 

 gave the constituents of potash as follows : 



Potassium 100 or 4-889 

 Oxygen SO'4-5 - 1 



According to this experiment, an atom of po- 

 tassium weighs 4-889, and an integrant particle 

 of potash 5-889. This determination is a little 

 below the truth, while that of the French che- 

 mists is a little above it. 



The mean of the two gives 5-005 for the 

 atomic weight of potassium. The true weight 



