CARBONATES, 379 



Acid, 43.9, -f- base, 47.1,-f- water, 9.0 = 100. 2 prop, carbonic 

 acid, 44 -f- 1 potassa, 48, -f 1 water, 9 = 101 for its equivalent. 



4. ACTION OF PRECEDING BODIES. 



(a.) The action of sulphur and of the acids, has been already ex- 

 plained. 



(&.) Decomposed by baryta, strontia, and lime, and an earthy car- 

 bonate is precipitated. 



(c.) Silica and alumina, by ignition, expel the acid, and unite 

 with the alkali, as before stated under the manufacture of glass. 



(d.) In the humid way, decomposes the nitrate and muriate of 

 baryta, and in the dry way, the sulphate. (See that salt.) 



5. USES OF THE CARBONATES OF POTASSA. 



Numerous in the arts. See potassa. 



In medicine, employed as an antacid and Uthontriptic, of undoubted 

 efficacy ; the bi-earbonate in good crystals should be preferred ; it, 

 is dissolved in water, or in any mild fluid. When the solution is 

 swallowed, the gas is often disengaged by acid in the stomach, or by 

 some mild vegetable acid, taken for the purpose. 



The crystals are often taken, a tea-spoonful at once, or in doses 

 of 15 to 20 grains, and they operate actively as a diuretic, especially 

 if the solution is considerably diluted. The term super-carbonate, 

 formerly applied to this salt, is incorrect. Dr. Coxe justly remarks, 

 that there can be no super-carbonate, except when the solution is 

 highly charged with carbonic acid gas, by pressure and cold. 



The bi-carbonate is one of the most elegant of the antacid reme- 

 dies ; it should be in every family, being perfectly safe and useful 

 in cases of disordered digestion. With the vegetable acids, especial- 

 ly the tartaric, or citric, it forms a fine effervescing mixture. 



CARBONATE AND BI-CARBONATE OF SODA. 

 CARBONATE. 



1. NATURAL HISTORY AND ORIGIN. 



Obtained by incineration of marine plants, fee.* 



commerce, the impure soda, or carbonate of soda, is call- 

 ed barilla, or kelp ; it contains, besides this salt, sulphate, muriate, 

 and sulphuret of soda, sulphuret of lime, usually hydriodate of pot- 

 assa, and much earthy and carbonaceous matter. 



(.) 01 

 (4.) In 



* As already mentioned under soda, it is obtained from the sal sola soda and kali, 

 in Spain, the sal sola soda, and the saliccrnia herbacea, are most esteemed ; from the 

 fuci and other marine plants, in Scotland ; from lakes and spontaneous efflorescence 

 in Egypt ; from veins in the mountains near Tripoli, and from the decomposition of 

 common salt. It effloresces on damp walls, generally on such as consist in part of 

 lime and sea sand, the carbonate of lime and the muriate of soda mutually decom- 

 posing each other. 



