OF POTASH. 259 



acid, equivalent to 25 grains of the pure acid, 

 were saturated with bicarbonate of potash. The 

 quantity necessary for the purpose was 52 1 74 

 grains, which 1 knew, by a previous analysis, to 

 contain exactly 24 grains of potash. Thus I 

 obtained a solution of acetate of potash in water ; 

 and I knew the exact weight of the acetic acid, 

 and of the potash constituting the salt. The so- 

 lution was placed in a small wedgewood dish 

 under the exhausted receiver of an air pump, a 

 few inches above a glass tray, containing concen- 

 trated sulphuric acid. In a few days the whole 

 water had evaporated, and left the dry salt, partly 

 in a state of crystals, and partly in that of a dry 

 white crust, which had probably lost a little of its 

 water of crystallization. Its weight was 

 grains ; and it was obviously composed of 



Acetic acid . 25 



Potash . . 24 



Water 8-26 



57*26 



If we divide each of these numbers by 4, we 

 shall obtain the atomic weights of the constitu- 

 ents as follows : 



Acetic acid 6-25 or 1 atom, 



Potash .6 - 1 atom, 



Water . 2-06-2 atoms. 



There is a slight deficiency in the water, which 



R2 



