84 MURIATE OF AMMONIA. ^ 



is to say, it becomes a vapor, and resumes the solid 

 form when cooled again : in the process for obtaining 

 the muriate of ammonia, therefore, it is converted into 

 vapor by the heat applied to the mixture, and is con- 

 densed in the solid form again in the upper part of 

 the vessel in which it is heated, which is kept cool on 

 purpose. The uses of sal-ammoniac in the arts are 

 numerous ; its principal consumers are the dyers and 

 workers in metals. 



159. Ammonia has a strong affinity for sulphuric 

 acid ; the sulphate may either be formed directly by 

 mixing together sulphuric acid and caustic ammonia, 

 or its carbonate, as in the process just described for 

 preparing the muriate from gas liquor ; or it may be 

 obtained by substituting for the sulphuric acid, added 

 to the gas liquor, a sulphate in which the acid is held 

 by a less powerful affinity than that which it has for 

 ammonia ; when this is done, the ammonia seizes the 

 sulphuric acid and causes it to relinquish the weaker 

 base with which it was previously combined, and which 

 thus unites with the carbonic acid, of the carbonate 

 of ammonia. 



160. When, for example, a solution of carbonate of 

 ammonia is mixed with a quantity of sulphate of lime, 

 they are both decomposed ; the ammonia combines 

 with the sulphuric acid, and the lime takes the car- 

 bonic acid. Sulphate of ammonia has a strong saline 

 taste, but no smell : it is a perfectly neutral salt, and 

 may be kept any time without undergoing change. It 

 is readily soluble in water. 



