AMMONIUM. 127 



acid carbonate is also converted into the neutral salt. The solu- 

 tion thus obtained is frequently used as a reagent. 



The aromatic spirit of ammonia (sal volatile) is a solution of 

 neutral ammonium carbonate in diluted alcohol to which some 

 essential oils have been added. 



Ammonium sulphate, (NH 4 ) 2 S0 4 , Ammonium nitrate, NH 4 N0 3 , and 

 Ammonium phosphate, (NH 4 ) 2 HP0 4 , may be obtained by the addi- 

 tion of the respective acids to ammonia water or ammonium 

 carbonate : 



H 2 S0 4 + 2NH 4 HO = (NH 4 ) 2 SO 4 + 2H 2 O. 

 HN0 3 + NH 4 HO = NH 4 NO 3 + H 2 0. 

 H 3 PO 4 + 2NH 4 HO = (NH 4 ) 2 HPO 4 + 2H 2 O. 

 H 2 S0 4 + (NH 4 ) 2 C0 3 = (NH 4 ) 2 S0 4 + H 2 + CO 2 . 



Ammonium iodide, Ammonii iodidum, NH 4 I, and Ammonium bro- 

 mide, Ammonii bromidum, NH 4 Br, may be obtained by mixing 

 strong solutions of potassium iodide (or bromide) and ammonium 

 sulphate, and adding alcohol, which precipitates the potassium 

 sulphate formed ; by evaporation of the solution the ammonium 

 iodide (or bromide) is obtained : 



2KI + (NH 4 ) 2 SO 4 = 2H 4 I + K 2 S0 4 ; 

 2KBr + (NH 4 ) 2 S0 4 = 2NH 4 Br + K 2 SO 4 . 



Another mode of preparing these compounds is the decom- 

 position of ferrous bromide (or iodide) by ammonium hydrate : 



FeBr 2 + 2NH 4 HO = 2NH 4 Br + Fe2HO. 



Ammonium hydrogen sulphide, NH 4 HS (Ammonium hydrosulphide, 

 Ammonium sulphydrate). Obtained by passing sulphuretted 

 hydrogen gas through water of ammonia until this is saturated: 



H 2 S + NH 4 HO = NH 4 HS + H 2 O. 



The solution thus obtained is, when recently prepared, a 

 colorless liquid, having the odor both of ammonia and of sul- 

 phuretted hydrogen; when exposed to the air it soon assumes a 

 yellow color. By the addition of ammonia water it is converted 

 into ammonium sulphide, (NH 4 ) 2 S : 



NH 4 HS + NH 4 HO = (NH 4 ) 2 S + H 2 O. 



