149 
and naphthaline , and on a new acid produced. 
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. 
