88 
I'OWA ACADEMY OE SCIENCES. 
In the Kubel and Association methods, however, a reac- 
tion would be expected and the permanganate acted upon 
to a certain extent. As the results from the investigation 
of these two methods were the same the following table 
will give the amount of permanganate decomposed for 
both methods in terms of oxygen consumed. 
Parts per million of chlorine as Oxygen consumed in parts 
sodium chloride in sample. per million. 
5 .03 
10 08 
15 10 
20 . 
25 . 
50 . 
100 . 
200 . 
300 . 
400 . 
500 . 
600 . 
700 . 
800 
900 . 
1000 . 
1100 . 
1200 . 
1400 . 
1600 . 
1800 . 
.13 
.15 
.18 
.23 
.28 
.33 
.38 
.48 
.63 
.72 
.80 
.83 
.98 
1.08 
1.24 
1.44 
1.56 
1.68 
From these results it is seen that in waters that contain 
large quantities of chlorides, it is well to give consideration 
to the action due to the presence of chlorides on the per- 
manganate solution where the Kubel or the Association 
method is used, for the determination of oxygen consumed. 
