SALTS SULPHATES. 321 



insoluble, if it requires more than 1000 parts of water for its solu- 

 tion. 



14. Incombustible, with a few exceptions. 



15. Crystallizable, either by natural or artificial processes. 



16. Saturation between acid and base is determined 



(a.) By the taste, which, when there is one equivalent of each, 

 becomes saline, or at least, ceases to be acid or alkaline. 



'.^ By the absence of any effect on test colors. 



c.) In the case of a carbonate; by the cessation of effervescence. 



d.) A scale or table of chemical equivalents, furnishes at once 

 the information desired, as to the quantity of the one agent necessary 

 to saturate the other. 



17. Salts precipitate, if they are insoluble in water,* or much less 

 soluble than their constituent principles 



(a.) In powder, as sulphate of baryta. 



(b.) In crystals, as sulphate of potassa, if formed from concentra- 

 ted acid and alkali. 



18. If soluble, they remain in solution, as most alkaline, and many 

 earthy and metallic salts do. 



19. The name of a salt expresses its composition, and the knowl- 

 edge of the composition recals the name. 



20. The nomenclature is therefore founded upon the most correct 

 logical principles. 



21. The salts are, on the whole, very important, to arts, science, 

 and domestic economy. Some of them exist in vast abundance. 



SULPHATES OF ALKALIES AND EARTHS. General Characters. 



1. Formed by sulphuric acid and a base. 



2. Generally crystallizable. 



3. Not decomposable by heat, or only partially so, (except the sul- 

 phate of ammonia.) 



4. Decomposable, (with the same exception,) by ignition with 

 charcoal, being converted into sulphurets. 



5. Have generally a bitter taste, if any. 



6. Decomposed by all the barytic salts, except sulphate of baryta ; 

 the precipitate is insoluble in acetic acid. 



7. Precipitated from their aqueous solutions, by alcohol, and in 

 general, crystallized. 



SULPHATE OF POTASSA. 



1. PREPARATION. 



(a.) By sulphuric acid and dilute solution of potassa, or of carbo- 

 nate of potassa, mingled till test paper is no longer affected, or effer- 

 vescence ceases. 



* Supposing the bases, or perhaps both acids and bases, to have been previously 

 in aqueous solution. 



41 



