286 



On Chemical Tests. 



[Oct. 



considered as the most frequently occuring ingredients in mineral wa- 

 ters, the following are occasionally present. 



xcvn. Carbonate of soda is known to exist in water, when, after 

 having been boiled down to half its bulk, and, if necessary, filtered, it 

 reddens turmeric paper, and restores the blue of litmus reddened by 

 vinegar; it also affords an effervescent precipitate with nitrate of baryta, 

 soluble in dilute nitric acid. This carbonate is incompatible with the 

 solub ] e salts of lime. 



xcvni. Muriate of lime may also be used to detect the alkaline 

 carbonates, with which it affords a precipitate of carbonate of lime. 

 Carbonate of soda is distinguished from that of potassa, by the latter 

 affording a precipitate in neutral muriate of platinum, which the former 

 does not. Carbonate of ammonia is discoverable by its smell, when act- 

 ed on by caustic fixed alkali or lime : also by its action on test-papers. 



xcix. Silica is detected by evaporating the water to dryness, and 

 boiling the residue in dilute muriatic acid. The silica, if present, re- 

 mains as a white powder not altered by a red-heat, but instantly fusing 

 with a particle of carbonate of soda. 



c. Boracic acid and borax have been found in certain lakes in In- 

 dia, and in some parts of Italy. To detect boracic acid, evaporate to 

 one-eighth the original bulk of the water, and add carbonate of soda as 

 long as it occasions any precipitate; boil and filter. The filtered liquor 

 will contain borate of soda with some other salts of the same basis; 

 evaporate to dryness in a platinum crucible, and digest the residue in 

 three or four parts of sulphuric acid, diluted with its bulk of water. If 

 boracic acid be present, it will separate in micaceous crystals. 



ci. Alumina has been found in a few mineral waters in the state, 

 of a sulphate. It may be separated by the following process : evapo- 

 rate to dryness, digest in alcohol, and redissolve the residue in eight 

 parts of water ; filter and add oxalic acid, which throws down lime, and 

 which, being separated, leaves magnesia and alumina in solution. 

 Carbonate of ammonia throws down the alumina and leaves the 

 magnesia. 



en. Pure ammonia throws down both alumina and magnesia. These 

 earths may be separated by solution of potassa which dissolves the former 

 but not the latter. 



cm. Manganese is sometimes found in water, but only in very small 

 proportion, so as not to amount to more than a trace. Dr.' Scudamore 

 found a trace of Manganese in the waters of Tunbridge Wells, and it 

 has never been discovered in larger proportion. % 



