76 



CHEMISTRY. 



Each one of these modifications forms its own peculiar salts, the 

 tests for which were spoken of under the head of Phosphorus. The 

 most important phosphates are those of soda, lime, ammonia, lead, 

 and silver. 



CARBONATES. 



These are distinguished by their facility of decomposition by any 

 of the acids, with effervescence. All the alkaline carbonates are de- 

 composable by heat, except those of potassa, soda, baryta, strontia, 

 and probably lithia. All, except those of potassa, soda, and ammo- 

 nia, are sparingly soluble in water; but are more or less soluble in 

 an excess of carbonic acid. Several of the carbonates occur native, 

 as those of lime, magnesia, soda, baryta, iron, copper, and lead. 



The most important carbonates are those of potassa, soda, lime, 

 ammonia, magnesia, baryta, iron, copper, and lead. 



ARSENITES AND ARSENIATES. 



These are salts of arsenious and arsenic acids respectively. The 

 ar seniles are all decomposed by a red heat ; the arsenious acid being 

 either dissipated in the form of vapour, or converted into arsenic 

 acid. 



The arseniates are not so easily decomposed, requiring usually 

 along with heat the aid of charcoal or black flux. 



CHROMATES. 



The salts of chromic acid are mostly of a yellow or red colour, the 

 latter tint predominating whenever the acid is in excess ; they are 

 valuable as pigments. The most important of the chromates are 

 those of potassa and lead. 



BORATES. 



The salts of boracic acid are very easily decomposed. The most 

 important one is the biborate of soda, or common borax. They 

 may all be recognised by their solutions in strong alcohol, burning 

 v.'ith a greenish flame. 



SECTION II. 



HYDROSALTS. 



By this term is understood such salts, of which either the acid or 

 base contains hydrogen. Formerly, this class of salts was much 

 more extensive than it is at present, in consequence of the different 

 views taken of the composition of the so called muriates, or hydrochlo- 

 rates ; but which are now generally spoken of as chlorides. Indeed, 

 all the haloid salts are now considered as compounds of the halogen 

 element (chlorhie, iodine, bromine, &c.) with a metal, rather than as 

 compounds of a hydracid with the oxide of the metal, which was the 



