22 MINEKAL WATERS OF THE UNITED STATES. 



CHLORIN. 



One hundred grams of the water under examination are treated 

 with a few drops of phenolphthalein. If a red color is shown, the 

 carbonates thus indicated are titrated to bicarbonates by the addition 

 of twentieth normal HKSO 4 added at the rate of a drop every few 

 seconds until the red color disappears. a A few drops of potassium 

 chroma te are now added and the chlorids titrated with a standard 

 solution of silver nitrate. If iodids and bromids are found, a correc- 

 tion of this figure is made based on the amount of these constituents 

 present. 



To determine bromin, iodin, arsenic, and boric acid, large quanti- 

 ties of water are evaporated to dryness, after the addition of small 

 amounts of sodium carbonate. The residue thus obtained is boiled 

 with distilled water, transferred to a filter, and thoroughly washed 

 with hot water. The alkaline filtrate is made to a definite volume and 

 aliquot portions taken to determine the above constituents. 



IODIN AND BROMIN. 



The qualitative tests for the presence of iodin and bromin are very 

 much the same as those used in Fresenius. An aliquot portion from 

 the alkaline filtrate is evaporated to dryness on the steam bath. Two 

 or three cubic centimeters of water are added to dissolve and soften 

 up the residue and enough absolute alcohol is added to make the per- 

 centage of alcohol about 90. This is boiled and filtered and the treat- 

 ment with 90 per cent alcohol repeated once or twice. Two or three 

 drops of sodium hydrate solution are added to the filtrate and it is 

 evaporated to dryness. The same process of extracting with 90 per 

 cent alcohol is repeated on the new residue and the extract filtered off 

 from the undissolved portion. A drop of sodium hydrate is now 

 added to the filtrate and it is evaporated to dryness. The residue is 

 treated with a little distilled water, dilute sulphuric acid added to acid 

 reaction, the liquid transferred to a test-tube, and a little carbon bisul- 

 phid added. Three or four drops of potassium nitrite solution are 

 'then added and the test-tube shaken. The presence of iodin is shown 

 by a pink color in the carbon bisulphid. Chlorin water is added until 

 the pink color due to the iodin has disappeared, and then a little more 

 chlorin water. The presence of bromin is shown by an orange color 

 in the carbon bisulphid. 



In most cases the above qualitative examination was all that was 

 necessary, since the iodin and bromin were usually not present, or 

 only as traces. In case the qualitative examination showed a very 



Cameron, Amer. Chem. J., 1900, 23:481. 



