and naphthaline, and on a new acid produced. 149 



the salts resulting being afterwards freed from sulphates, by 

 solution in alcohol. It is however proper to mention that 

 another acid, composed of the same elements, is at the same 

 time formed with the acid in question, in small, but variable 

 proportions. The impure acid used, therefore, should be 

 examined as to the presence of this body, in the way to be 

 directed when speaking of the barytic salts ; and such 

 specimens as contain very little or none of it should be 

 selected. 



Potash forms with the acid a neutral salt, soluble in water 

 and alcohol, forming colourless solutions. These yield either 

 transparent or white pearly crystals, which are soft, slightly 

 fragile, feel slippery between the fingers, do not alter by 

 exposure to air, and are bitter and saline to the taste. They 

 are not very soluble in water ; but they undergo no change 

 by repeated solutions and crystallizations, or by long conti- 

 nued ebullition. The solutions frequently yield the salt in 

 acicular tufts, and they often vegetate, as it were, by spon- 

 taneous evaporation, the salt creeping over the sides of the 

 vessel, and running to a great distance in very beautiful 

 forms. The solid salt heated in a tube gave off a little 

 water, then some naphthaline ; after that a little carbonic and 

 sulphurous acid gases arose, and a black ash remained, con- 

 taining carbon, sulphate of potash, and sulphuret of potas- 

 sium. When the salt was heated on platinum foil, in the 

 air, it burnt with a dense flame, leaving a slightly alkaline 

 sulphate of potash. 



Soda yields a salt, in most properties resembling that of 

 potash ; crystalline, white, pearly, and unaltered in the air. 



