MERCURY. 



181 



Analytical reactions. 



Mercurous salts. 



Mercuric salts 



1. Hydrosulphu- Black precipitate of mer- '. 

 ric acid, or am- curous sulphide. 



monium sulphide. 



Hg 2 2N0 3 

 2HN0 3 



H 2 S = 

 Hg 2 S. 



Black precipitate of mer- 

 curic sulphide. (Precipitate 

 may be white or gray, with an 

 insufficient quantity of the re- 

 agent. (See above ) 



Bed precipitate of mercuric 

 iodide. (See above.) 



3. Potassium or Dark-brown precipitate of Yellow precipitate of mer- 

 sodium hydrate. mercurous oxide, Hg 2 0. curie oxide, HgO. (Seeabove.) 



4. Ammonium Black precipitate of a mer- White precipitate of a mer- 

 hydrate. curous ammonium salt is curie ammonium salt is 



formed. (The insoluble white formed. (See explanation 

 calomel is converted into a I above.) 

 black powder.) 



5. Potassium or Yellowish precipitate of Brownish-red precipitate of 

 sodium carbonate, mercurous carbonate, which is j mercuric carbonate; unstable. 



unstable. 



6. Hydrochloric ! "White precipitate of mer- ! No change, 

 acid or soluble ; curous chloride is produced. 



chlorides. 



Hg,2NO s 

 2HNO 



2HC1 = 



7. Stannous chloride produces, in solutions of mercury, a 

 white precipitate, which turns dark gray on heating with an 

 excess of the reagent. The reaction is due to the strong re- 

 ducing or deoxidizing property of the stannous chloride, which 

 itself is converted into stannic chloride, while the mercury salt 

 is first converted into a mercurous salt and afterwards into 

 metallic mercury : 



2HgCl 2 + SnCl 2 = Hg 2 Cl 2 + SnCl 4 ; 

 Hg 2 Cl 2 + SnCl 2 = 2Hg + SnCl 4 . 



8. Dry mercury compounds, when mixed with sodium car- 

 bonate and potassium cyanide, and heated in a narrow test-tube, 

 are decomposed with liberation of metallic mercury, which con- 

 denses hi small globules in the cooler part of the tube. 



