420 071 the SoluUlity of alkaline and earthy Salts. 



cipitate of super tartrate of potass. Sulphate of potass, on ac- 

 count of its sparing solubility, would be precipitated on a slight 

 addition of acid, were it not capable of combining with an excess 

 of acid and being rendered by it a super and more soluble salt : 

 this then requires a much larger proportion of acid to deliqui- 

 date it than a salt of the same solubility as the neutral sulphate, 

 and which is not capable of combining with an extra dose of 

 acid. But other and more important facts presented them- 

 selves to my notice, which do not appear to have received that 

 attention by chemists which their importance in the science re- 

 quires. Students naturally coneeive that the bases of soluble 

 salts are soluble in the acids which form these combinations— 

 this very extensive error may include the whole class of salts ; 

 but as in this I allude to acids of the usual specific gravity, it is 

 alone the permanent and efflorescent salts which are precipitated 

 by them. 



Some observati<uis in your valuable Magazine, on the subject 

 of barvtes and strontian, by Mr. Hume, somewhat lessened the 

 difficulties to which the student is subject: but whether that 

 gentleman knew that these properties were not peculiar to those 

 earths, I am entirely ignorant. Berthollet hinted in a more 

 general way that such properties do exist, when he stated, that 

 by increasing the points of contact of the salt precipitated from 

 the solution of sul|)liate of potass by sulphuric acid, it may be 

 redissolved : this solution however cannot be obtained without 

 exposure of the mixture to the atmosphere (from which it ab- 

 sorbs moisture) by an increase of temperature, or perhaps by 

 some other circumstance, which, if it be the case, ought to have 

 been explained. 



B'hiiiates.~] Are not pre- 



Lime. 

 . Magnesia. 

 ^ Alumina. 



eg ; 



■g Nitrates. 

 B Magnesia. 

 Sj Lime. 

 .?* Ammonia. 

 ;!? Alumina. 



Sulphate. 

 Alumina. 



cipitated ei- 

 ther on the 

 addition of 

 their acids of 

 j the usual 

 )>specific gra- 

 vity to a sa- 

 turated solu- 

 tion, or on 

 the addition 

 I of the dry 

 J base to its 

 acid. 



Muriates. " 



Potass. 



Soda. 



Ammonia. 

 ~ Barytes. 

 u Strontian. 



C/2 



^ Nitrates. 

 "^^ Potass. 

 s Soda. 

 ^ Barytes. 

 § Strontian. 



g Sulphates. 

 fX^ Soda. 



Magnesia. 



Ammonia. 



Are precipi- 

 tated either 

 on the addi- 

 tion of their 

 acids to a sa- 

 ^'tu'-ated solu- 

 tion, or by 

 throwing the 

 dry base on 

 its acid. 



Metallic 



