of Phosphoric Acid. 323 



The supernatant fluid reddens litmus-paper. The mass is not 

 affected by ebullition, but when heated with muriatic acid, it 

 is dissolved. The precipitate is entirely dissolved by excess 

 of the soda salt; ammonia does not produce a precipitate in 

 the solution. 



A solution of sulphate of magnesia does not produce any 

 precipitate, even on ebullition. If much of the soda salt has 

 been added, no precipitate is produced in the solution by am- 

 monia ; in the opposite case, ammonia produces a precipitate 

 which is soluble in chloride of ammonium. 



Nitrate of silver produces a dense, voluminous, white pre- 

 cipitate, which is soluble in ammonia and nitric acid. It is 

 also perfectly soluble in a large excess of the salt of soda. 

 The supernatant liquid reddens litmus-paper. The precipi- 

 tate does not become oleaginous when shaken in the cold, but 

 when boiled it contracts, occupying a smaller volume, and 

 becomes perfectly resinous. Heat renders it tenacious, so 

 that it can be drawn into threads; and on cooling, it solidifies 

 to a brittle mass. 



A solution of pernitrate of mercury^ which necessarily con- 

 tains free acid, produces a white precipitate; this, when shaken, 

 even in the cold, subsides to the bottom of the vessel as a 

 dense oleaginous mass. 



Solution of bichloride of mercury produces no change. 



Solution of protonitraie of mercury produces a dense white 

 precipitate, which is soluble in an excess of the soda salt ; 

 on boiling it becomes resinous, like the salt of silver. 



Solution of sulphate of copper Y^todnces no change; but 

 chloride of copper produces a bluish-white precipitate, which 

 is soluble both in excess of the soda salt and of the chloride 

 of copper. 



Solution of acetate of lead YiToduces a dense voluminous pre- 

 cipitate, which is soluble in excess of the soda salt, and when 

 shaken forms a coherent mass, but does not become oleagi- 

 nous ; when set aside, however, it becomes somewhat resinous. 



Solution of protosulphate of manganese produces a white 

 precipitate, which when shaken becomes an oily mass. The 

 precipitate is soluble in an excess of the soda salt; sulphuret 

 of ammonium throws down sulphuret of manganese from this 

 solution. 



Solution of protosulphate of iron does not produce a preci- 

 pitate. Nor is any precipitation caused by the addition of 

 ammonia to this solution, but it renders it dark green. 



Solution of sidphate of zinc produces no change. 



Solutions of the sulphates of cobalt and nickel also produce 

 no change. However, solutions of the chlorides of cobalt and 



Y2 



