386 CARBONATES. 



BI-CARBONATE. 



1. PREPARATION, &c. 



(a.) Through a solution of the carbonate, in Nooth's or other 

 convenient machine, pass a stream of carbonic acid gas to saturation. 



(b.) Gentle evaporation gives small six sided prisms, inodorous and 

 nearly tasteless. 



(c.) A salt extremely similar, appears to be formed, when common 

 carbonate of ammonia of the shops, is simply exposed in powder, to 

 the air ; it loses sometimes nearly half its weight, in a single night ; 

 the ammonia and perhaps the water, are more wasted than the car- 

 bonic acid, and the proportion of the latter is doubled. We may 

 often observe that the volatile salts of the shops, when exposed to 

 the air, become nearly inodorous and their taste less active. 



The composition, exclusive of water, is, 



Carb. acid, 71.81, 2 proportions, - 44 



Ammonia, 28.19, 1 " - 17 



100.00 Its equivalent 61 



" By varying the proportions of the ingredients and the regulation 

 of the heat, it is possible to obtain a bi-carbonate at once, by subli- 

 mation.* 



REMARKS. The carbonate of ammonia commonly used in medi- 

 cine and chemistry, is that of the shops. In medicine, it is a valua- 

 ble remedy ; stimulating, diuretic, antacid, anti-poisonous, &LC. The 

 smelling bottles that have not been exposed much to the air, exhale an 

 odor that is highly stimulating ; but by careless keeping or frequent 

 opening, they often lose their activity. As a reagent, the carbonate 

 of ammonia is very valuable in chemistry ; it is the most convenient 

 application, for the removal of acid stains from dark clothes. It 

 should be used in solution. 



This is an elegant salt, composed entirely of condensed gases ; its 

 elements are, for the acid, carbon and oxygen ; for the ammonia, 

 hydrogen and nitrogen. f It is a striking example of the produc- 

 tion of new properties by chemical combination. 



EARTHY CARBONATES CARBONATE OF LIME. 



I. NAMES. Chalk, limestone, marble, calcareous spar, stalactite, 

 fyc. The natural carbonate of lime, is in these and other forms, most 

 extensively diffused, and contributes to many purposes of ornament 

 and utility. 



* Ann. of Philos. N. S. III. 110, and Henry, Vol. I, p. 419. 



t Thus arranged carbon G+2 proportion of oxygen, 16 = 22 carb. acid; nitrogen, 

 14+3 prop. hyd. = 17 ammonia, and there arc two propor. of carb. acid, 44+1 of am- 

 monia, 17 = Cl, as above. 



