Dropper bottles for solutions used in this kit
shall be filled prior to testing from larger
containers (11, 12, and 13, fig. 1-6 or 11,
Fig 1-6.1) as indicated:
Arsenite (Used in
- (12) Sodium Arsenite S.
Buy 1 Only)
Wide Range pH 1
- (11) Wide Range 1 D.
- (13) Orthotolidine S.
in Buy 1 Only)
(2) Determination for pH.
(a) Insert the pH color disc into the comparator.
(b) Select two clean comparator cells.
(c) Fill one cell to the 15 ml graduation mark with water
This cell, when filled to the mark with the water under
test, compensates for color and turbidity.
The omission of this step
may cause serious errors.
(d) Insert this cell in the right-hand space of the comparator.
(e) Add 0.5 ml of the wide range pH indicator solution (white
cap) to the other cell by means of the dropper.
(f) Fill this cell to the mark with the water under test.
(g) Insert this cell containing the water and indicator solu-
tion in the left-side of the comparator.
Position the prism eyepiece
on the two bosses.
Determinations made without the prism installed are
subject to error.
(h) Hold comparator with the eyepiece about 10 inches from the
eye facing a good light source, preferably daylight, but avoid direct
Rotate the disc until the color on the disc matches the
color of the left-hand cell.
The reading can be made directly from
the round window in front of the comparator.
The value is expressed
as the pH number.
(i) If the color in the left-hand cell appears between two
color standards, the value may be estimated.
(j) When the test has been completed, empty the samples and
wash the cells with clean water.