MINERAL WATERS, WELL-WATERS, ETC. 223 



XII. Carbonate of soda. The water is boiled for a 

 long time, the precipitated earthy carbonates filtered 

 off, and the filtrate divided into two equal parts. In 

 one of these, previously acidified slightly with nitric 

 acid, the chlorine is determined by precipitation with 

 nitrate of silver. The other portion is mixed with a 

 slight excess of hydrochloric acid, evaporated to dry- 

 ness, and the residue heated nearly to redness ; it is 

 then dissolved in water and precipitated by nitrate of 

 silver. The difference between this amount of chloride 

 of silver and the former, corresponds to the quantity 

 of carbonate of soda which was contained in the 

 water. 



XIII. Lime. In the solution filtered from the pre- 

 cipitate obtained in IV., the lime is precipitated by 

 oxalate of ammonia, after addition of ammonia. (See 

 No. 12.) 



XIV. Magnesia. The solution filtered from the 

 lime-precipitate is concentrated by evaporation, al- 

 lowed to cool, mixed with concentrated ammonia, and 

 the magnesia precipitated by phosphate of soda. (See 

 No. 6.) 



XV. Lithia. The lithia is best obtained from the 

 mother-liquid according to the method given in XL 

 The solution filtered from the precipitate is mixed 

 with phosphate of soda, evaporated to dryness, and the 

 residue treated with a very small quantity of water, 

 when phosphate of soda and lithia is left, which 

 should, however, be tested for magnesia. 



Or the mother-liquor may be evaporated to dryness 

 with excess of carbonate of soda, the residue extracted 

 with hot water, the filtered solution mixed with phos- 

 phate of soda and evaporated to dryness. 



XVI. Strontia may be sought in the ferruginous and 

 calcareous stalactites and ochreous deposits from 

 waters containing carbonic acid. 



XVII. Phosphoric acid. The foregoing remark ap- 



