28 MINERAL WATERS OF THE UNITED STATES. 



IRON AND ALUMINUM. 



An aliquot portion of the silica filtrate is treated with a little ammo- 

 nium chloric! (to keep magnesia in solution) and then heated to boiling 

 temperature. Ammonia is added a drop at a time until, it can be very 

 faintly smelled coming off from the solution. The solution is then 

 boiled until the smell of ammonia has practically disappeared, filtered, 

 washed with hot water, dried, burned, and weighed as ferric oxid 

 (Fe 2 O 3 ) and alumina (A1 2 O 3 ). The filtrate is kept for the determination 

 of calcium and magnesium. 



IRON. 



An aliquot portion of the silica filtrate is treated with 2 or 3 cc of 

 concentrated sulphuric acid and evaporated to a sirupy consistency. 

 It is then reduced with hydrogen by the addition of zinc, filtered, and 

 iron determined in the filtrate by means of standard potassium per- 

 manganate. 



MANGANESE. 



An aliquot portion of the silica filtrate is treated just as described 

 above for iron and aluminum, so as to eliminate these two elements. 

 The ammoniacal filtrate resulting is treated with more ammonia and a 

 few drops of bromin. The mixture is well stirred and boiled. The 

 vessel is then removed from the source of heat, cooled slightly, and a 

 little more ammonia and bromin added. This process repeated once 

 or twice precipitates all the manganese as the oxid. The solution is 

 made slightly acid with acetic acid, filtered, and washed with hot 

 water. The filter and contents are burned and weighed as manganese 

 tetroxid (Mn 3 O 4 ). 



CALCIUM AND MAGNESIUM. 



The filtrate from iron and aluminum is treated with ammonium 

 oxalate in the usual manner and allowed to stand over night. The 

 liquid is filtered off, the precipitate dissolved in hydrochloric acid and 

 reprecipitated with ammonia and a little extra ammonium oxalate. 

 This is again allowed to stand over night and is filtered and washed on 

 the same paper previously used. The precipitate is dried, transferred 

 to a crucible, burned and blasted' in the ordinary way, and finally 

 weighed as calcium oxid. The combined filtrates are evaporated to 

 dry ness in platinum and the major part of the ammonium salts driven 

 off by the aid of heat. The residue is dissolved in dilute hydro- 

 chloric acid and filtered. The filtrate is made slightly ammoniacal, 

 enough sodium phosphate solution is added a drop at* a time to pre- 

 cipitate all magnesium, and 10 cc of concentrated ammonia are finally 

 added, drop by drop. The beaker is covered and allowed to stand 

 over night, the contents filtered, washed with dilute ammonia water, 

 dried, and blasted and weighed as magnesium pyrophosphate. 



