ALKALINITY 285 
the ammonium oxalate solution and the potassium permanganate till a 
pink coloration appears. This destroys the oxygen consuming capacity 
of the water used. Now add another 10 ¢c.c. of ammonium oxalate 
solution and titrate with potassium permanganate. Adjust the potas- 
sium permanganate solution so that 1 c.c. is equivalent to 1 ¢,c. of the 
ammonium oxalate solution or 0.1 mg. of available oxygen. 
ALKALINITY 
Determination. Add 4 drops of phenolphthalein to 50 c.c. of water 
and titrate with N/50 sulphuric acid solution until the coloration dis- 
appears. The number of cubic centimeters of N/50 sulphuric acid 
times 20 will indicate the phenolphthalein alkalinity in parts per million. 
This same sample may be used for the methyl orange alkalinity by 
adding 2 drops of methyl orange and continuing the titration to a faint 
pink appearance. The methyl orange alkalinity is equal to the total 
number of cubic ecntimeters of N/50 sulphuric used multiplied by 20. 
The alkalinity of water is due to the content of inorganic salts such 
as, carbonates, bicarbonates, hydroxides, silicates, etc. The relations 
between the phenolphthalem and methyl orange alkalinities are ex- 
pressed in the following table: 
TABLE XXV 
RELATIONS BETWEEN ALKALINITY TO PHENOLPHTHALEIN AND 
METHYL ORANGE IN PRESENCE OF CARBONATE, BICAR- 
BONATE AND HYDROXIDE 
(Standard Methods, 1917) 
VALUE oF Raprau EXPRESSED IN TERMS OF CatcrIUM CARBONATE, 
Result of Titration. 
Bicarbonate. Carbonate. Hydroxide. 
P=0 T 0 0 
T =3$T T~—2P 2P 0 
P=3T 0 2P 0 
P=iT 0 2 (T—P) 2P~T 
P=T 0 0 T 
T =total alkalinity in presence of methyl orange. 
P =alkalimty in presence of phenolphthalem. 
