150 Mr. Faraday on the mutual action of sulphuric acid 



I thought that, in it, the metallic taste which frequently 

 occurred with this acid and its compounds was very decided. 

 The action of heat was the same as before. 



Ammonia formed a neutral salt imperfectly crystalline, not 

 deliquescent, but drying in the atmosphere. Its taste was 

 saline and cooling. It was readily soluble in water and 

 alcohol. When heated on platinum foil it fused, blackened, 

 burnt with flame, and left a carbonaceous acid sulphate of 

 ammonia, which by further heat was entirely dissipated. Its 

 general habits were those ' of ammoniacal salts. When its 

 solutions, though previously rendered alkaline, were evapo- 

 rated to dryness at common temperatures, and exposed to 

 air, the salt became strongly acid to litmus paper. This 

 however is a property common to all soluble ammoniacal 

 salts, I believe, without exception. 



Baryta. It is easy by rubbing carbonate of baryta with 

 solution of the impure acid, to obtain a perfectly neutral 

 solution, in which the salt of baryta, containing the acid already 

 described, is very nearly pure. There is in all cases an 

 undissolved portion, which being washed repeatedly in small 

 quantities of hot water, yields to the first portions a salt, 

 the same as that in the solution. As the washings proceed, 

 it is found, that the salt obtained does not burn with so much 

 flame on platina foil, as that at first separated ; and the fifth 

 or sixth washing will perhaps separate only a little of a salt, 

 which when heated in the air, in small quantities, burns 

 without flame in the manner of tinder. Hence it is evident 

 that there are two compounds of baryta, which as they are 

 both soluble in water, both neutral, and both combustible, 



