AMMONIA, CARBONATE OP 



converted into chloride or snlphate, tho details of the manufacture of the ammo- 

 niacal salts will be given under those heads. For the determination of ammonia, see 

 NITROGEN. H. M. W. 



AMMONIA, CARBONATE OF. [The scsguicarbonate of commerce, 

 2NH 1 , 3C0 1 , 2HO (4WH S , 3CO 2 , 2H*O), at. wt. 118.] This salt was probably 

 known to Raymond Lully and Basil Valentine, as the chief constituent of putrid 

 urine. The real distinction between ammonia and its carbonate was pointed out by 

 Dr. Black. 



Carbonate of ammonia is formed during the putrefaction of animal substances, 

 and by their destructive distillation. Ite presence in rain-water has been before 

 alluded to. 



The carbonate of ammonia of commerce is obtained by submitting to sublimation 

 a mixture either of sal-ammoniac or sulphate of ammonia with chalk. 



This is generally carried out in cast-iron retorts, similar in size and shape to those 

 used in the manufacture of coal gas. The retorts are charged through a door at one 

 end, and at the other they communicate with large square leaden chambers, supported 

 by a wooden frame, in which the sublimed salt is condensed. Fig. 38. 



The product of this first process is impure, being especially discoloured by the 

 presence of carbonaceous matter, and has to be submitted to resublimation. This is 

 carried out in iron pots surmounted by moveablo leaden caps. These pots are either 

 sot in brickwork, and heated by the flue of tho retort furnace, or are placed in a water- 

 bath, as shown in fig, 39. In fact, a temperature not exceeding 150 P, is found 

 sufficient. 



89 



The charge of a retort consists usually of about 65 Ibs. of sulphate of ammonia (or 

 an equivalent quantity of the chloride) to 100 Ibs. of chalk, which yield about 40 Ibs. 

 of crude carbonate of ammonia. 



Modifications of the Process. Mr. Laming has suggested to bring ammonia and 

 carbonic acid gases into mutual contact in a leaden chamber having at the lower part 

 a layer of water, and then, to crystalliso the. salt by evaporating this aqueous solution. 



