LIQUID CHLORINE 331 
7. Sodium thiosulphate. AN/40 solution. Dissolve 6.2 gms. of chemically 
pure recrystallized sodium thiosulphate in water and dilute the solution to 1 liter 
with distilled water. Each cubic centimeter is equivalent to 0.2 mg. of oxygen 
or to 0.13895 ¢.c. of oxygen at 0° C. and 760 mm. pressure. Inasmuch as this 
solution is not permanent it should be standardized occasionally against N/40 
solution of potassium bichromate. The keeping qualities of the thiosulphate 
solution are improved by adding to each liter 5 ¢.c. of chloroform and 1.5 gms. 
of ammonium. 
TaBLE XXIX 
PREPARATION OF PERMANENT STANDARDS FOR HIGH CHLORINE 
CONTENT 
Value in Chlorine, | CPgep Sulphate | Stronger Potassivm 
Parts per million C.C. C.C. 
0.10 1.8 10 
.20 19 20 
380 1.9 3 0 
40 20 3 8 
60 20 4 § 
.60 2.0 5 1 
.70 20 5 8 
.80 2.0 6 3 
.90 2 0 6 7 
1.0 20 7 2 
2.0 2.0 12 0 
3.0 20 21.0 
4.0 2.0 30.0 
5.0 20 39.0 
6.0 2.0 46.0 
7.0 2.0 56.0 
8.0 2.0 63.0 
9.0 2.0 70.0 
10.0 2 0 75.0 
Liquid Chlorine. To some extent, this chemical has replaced cal- 
cium hypochlorite in water treatment. It has certain distinct advan- 
tages over “ bleach ” as has been outlined by Dutton (1917) and Jen- 
nings (1915) as follows: 
1. A more accurate means of control. 
2. An elimination of dirt and the odor of chlorine. 
3. An appreciable decrease in labor. 
4. A means of storing the chemical so as to eliminate any decrease in 
strength. 
