20 MINERAL WATERS OF THE UNITED STATES. 



NITRIC ACID. 



For the determination of nitric and nitrous acid, free and albuminoid 

 ammonia, and oxygen-consuming capacity, the methods as given in 

 Mason's Examination of Water were followed in all their principal 

 details. They are as follows: 



In determining nitric acid 100 grams of the spring water are treated 

 with 2 drops of a saturated solution of sodium carbonate and evapo- 

 rated to dryness on the water bath. The residue is treated with 2 cc 

 of phenol-sulphonic acid (made by mixing 148 cc of pure sulphuric 

 acid, 12 cc of water, and 24 grams of phenol), a little water added, 

 and then an excess of ammonia. The solution is transferred to a 100 cc 

 Nessler jar, the volume made up to 100 cc with distilled water, and 

 the depth of the yellow color compared with that produced by treat- 

 ing different amounts of standard potassium nitrate (containing 0.01 mg 

 of nitrogen as nitrate in each cubic centimeter) in the same manner. 

 Where more than 6 parts per million of chlorin are present in a sample 

 of spring water, an amount of chlorin (in the form of sodium chlorid) 

 corresponding to the amount of chlorids present in the sample under 

 examination is added to the standards before evaporation. 



NITROUS ACID. 



For this determination 100 grams of the water are placed in a 100 cc 

 Nessler jar and treated with one or two drops of concentrated hydro- 

 chloric acid. One cubic centimeter of sulphanilic acid (containing 

 1 gram in each 100 cc of water) is then added, followed by 1 cc of a 

 solution of naphthylamin hydrochlorid (obtained by boiling 0.5 gram 

 of the salt with 100 cc of water for ten minutes at constant volume), 

 and the whole well mixed. The Nessler jar is then set aside for half 

 an hour, along with several other Nessler jars containing known amounts 

 of a standard nitrite solution (containing 0.0001 mg of nitrogen as 

 nitrite in each cubic centimeter), made up to 100 cc with nitrite-free 

 water, and treated with hydrochloric acid, sulphanilic acid, and naph- 

 thylamin hydrochlorid in the manner just described. By comparing 

 the depth of pink color in the known and unknown solutions the 

 amount of nitrite can be determined. 



FREE AMMONIA. 



A large flask of about 1.5 liters' capacity is connected to an upright 

 bulbed condenser by means of a rather large glass tube and soft, new, 

 rubber-stoppered connections. In this is placed 5 cc of a saturated 

 solution of sodium carbonate and 200 cc of ammonia-free water. The 

 water is distilled off in 50 cc Nessler jars until no more ammonia is 

 shown, when the jars are nesslerized. Five hundred grams of the 

 water under examination are now added and the distillation in 50 cc 

 Nessler jars continued till ammonia ceases to be given off. About four 



