282 WATER HYGIENE 
be high the distillate may be caught in a flask (200 ¢.c.) and an aliquot 
portion Nesslerized. Usually four Nessler tubes are sufficient. The 
last one should contain no nitrogen. When Nessler tubes are used the 
following example will serve to illustrate the computation. 
First tube =3.0 ¢.c. of standard NH4Cl solution. 
Second tube =2.6 c.c. of standard NH.4Cl solution. 
Third tube =1.0 c.c. of standard NH4Cl solution. 
Fourth tube =0.0 c.c. of standard NH4Cl solution. 
P maaaannn | 
Total 6.6 c.c. of standard NH,Cl solution. 
6.6>< 0.00001 = 0.000066 gm. N. 
If 500 c.c. of the water were taken this amount must be multiplied by 
2 to get the amount of N in a liter of the water. 
0.000066 X 2= 0.000182 gm. N. in a liter=.132 part per million. 
If an aliquot portion from a flask is Nesslerized the calculation is 
about the same. 
Free Ammonia. Five hundred c.c. of the sample should be intro- 
duced into a 800 ¢.c. Kjeldahl flask fitted to a condenser so that the dis- 
tillate may be received in four Nessler tubes. Heat so that not more 
than 10 ¢.c. nor less than 6 c.c. comes over in a minute. If the nitrogen 
is known to be high, catch the distillate in a flask. Nesslerize, as 
described above. 
Albuminoid Nitrogen. This is determined cn the same sample after 
the free ammonia has been distilled off. Alkaline potassium perman- 
ganate, prepared as follows is required for this determination. Pour 
1200 c.c. of distilled water into a large evaporating dish and boil for ten 
minutes. Remove the flame and add 16 gms. of potassium perman- 
ganate. Dissolve and add 800 c.c. of a 50 per cent solution of potassium 
hydroxide. Add a little distilled water and boil down to 2000 c.c. 
After the distillate for free ammonia nitrogen has been received, 
remove the flame and add 50 c.c. or more of alkaline potassium per- 
manganate to the flask and collect 200 c.c. of distillate in four Nessler 
tubes. Nesslerize as described above. 
The free ammonia determined above probably represents nitrogen 
which is present as some inorganic salts. These may be split by boiling. 
It may represent a stage in denitrification resulting from deaminization 
of amino acids. As such, free ammonia has little significance but it 
does represent chenging organic matter. The albuminoid ammonia is 
of more sanitary significance. It indicates recent organic pollution. 
