72 § 54. BASES AND ACIDS WITH REAGENTS. 



the filter; ignite the filter and its contents separately. 

 The ignition should be carried to a full red heat. The 

 residue contains 72.05" j^ of manganese. 



ZINC. Zn. 65. 



54. Compounds of zinc with phosphoric, carbonic, ox- 

 alic, and silicic acids, and sulphur and cyanogen, are in- 

 soluble or sparingly soluble in water. The silicate is 

 insoluble in acids. 



Reactions. — Solutions of zincic salts give a white pre-^ 

 cipitate, ZnO, H^O or ZnH^O^, with sodic or ammonic 

 hydrate, soluble in excess of the precipitant, and re-pre- 

 cipitated from this solution on dilution with considerable 

 water and boiling. 



Solutions of zincic salts give a white flocculent precipi- 

 tate, Zn^Fe^Cy^, with potassic ferrocyanide, that is diffi- 

 cultly soluble in acids. 



LEAD. Pb. 207. 



55* Compounds of lead with sulphuric, phosphoric, car- 

 bonic, oxalic, and tartaric acids, and sulphur and fluorine, 

 are insoluble, or sparingly soluble in water. The sulphate 

 and sulphide are insoluble in dilute acids. 



Reactions. — Solutions of salts of lead give a white pre- 

 cipitate, 2PbO, H^O or Pb^H^Og, with sodic or ammonic 

 hydrate, insoluble in excess of the precipitant. . 



If free from a very large excess of strong acid, they 

 give a white precipitate, PbSO^, with dilute sulphuric 

 acid, which appears at once, or after some time if the so- 

 lution is very dilute ; this precipitate is insoluble in dilute 

 acids, and is more insoluble in dilute sulphuric acid than 

 in pure water ; it i^ soluble in a solution of ammonic tar- 

 trate containing an excess of ammonia ; if this solution 

 is acidified with acetic acid and potassic dichromate add- 



