152 



METALS AND THEIR COMBINATIONS. 



1. Ammonium 

 sulphide. 



2. Hydrosulphu- 

 ric acid. 



3. Ammonium, 



Analytical reactions. 



Ferrous salts. 

 Black precipitate of ferrous 



sulphide. 



FeS0 4 + (NH 4 ) 8 S = 

 (NH 4 ) 2 S0 4 + FeS. 



No change. 



White precipitate of ferrous 



sodium, or potas- hydrate, soon turning green, 



Ferric salts. 



Black precipitate of ferrous 

 sulphide mixed with sulphur. 

 Fe 2 Cl 6 + 3[(NH 4 ) 2 S] - 

 6NH 4 C1 + 2FeS + S. 



Ferric salts are converted 

 into ferrous salts with precipi- 

 tation of sulphur. 



Fe 2 Cl 6 + H 2 S = 

 2FeCl 2 + 2HC1 + S. 



Reddish-brown 

 of ferric hvdrate. 



precipitate 

 Precipita- 



sium hvdrate. 



black, and brown, 

 tion not complete. 



FeCl 2 -f 2NaHO = 

 2NaCl + Fe2HO. 



Precipita- tion is complete. 



Fe 2 Cl 6 6(NH 4 HO) = 

 6NH 4 C1 + Fe 2 6HO. 



4. Ammonium, "White precipitate of fer- 

 sodium, or potas- rous carbonate, soon turning 

 sium carbonate. ; darker. 



FeCl 2 + Na 2 CO 3 = 

 2NaCl + FeCO 3 . 



Almost white precipitate, 

 soon turning darker. 



5. Alkaline phos- 

 phates or arseni- 

 ates. 



6. Potassium fer- 

 rocyanide, 



K.FeCy,.. 1 



Reddish-brown precipitate 

 of ferric hydrate, with libera- 

 tion of carbon dioxide. 



Fe 2 Cl 6 + 3Na 2 CO 3 + 3H 2 O = 

 6NaCl + Fe 2 6HO + 3C0 2 . 



A yellowish-white precipi- 

 tate is produced. 



Almost white precipitate, Dark blue precipitate of fer- 

 soon^turning blue by absorp- ric ferrocyanide, or Prussian 



tion of oxygen. 



7. Potassium fer- Blue precipitate of ferrous 

 ricyanide, j ferricyanide,orTurnbulPsblue. 



K 6 Fe 2 Cy 12 . 3FeCl 2 + K 6 Fe 2 Cy 12 = 



6KC1 + Fe 3 Fe 2 Cy 12 . 



blue. Decomposed by alka- 

 lies ; insoluble in acids. 

 2Fe 2 Cl 6 + 3(K 4 FeCy 6 ) = 

 12KC1 + Fe 4 3FeCy 6 . 



No precipitate is produced, 

 but the liquid is darkened to a 

 greenish or olive hue. 



8. Tannic acid. 



9. Potass! umsul- 

 phocyanate. 



No change, provided oxida- A dark greenish-black pre- 

 tion of the ferrous salt has not cipitateoftannate of iron (ink) 

 taken place. is produced. 



As above. 



Deep blood-red precipitate 

 of ferric sulphocyanate. 



1 Cy = Cyanogen CX. 



