(d) The chloride content of the test water in mg chloride/l is
found by multiplying the number of drops added by 7.58.
Color Test Kit - Apparent Color (fig. 2-15).
(1) Color in natural waters results from metallic salts, organic
and other dissolved or suspended materials present.
(a) Industrial wastes contribute specific colors to wastewater
which are dependent, as are most color forming materials, on the pH of
Color removal is necessary for some industrial processes
and is practiced for water intended for general domestic purposes.
(b) Color may be expressed as apparent or true color. The
apparent color includes that from dissolved materials plus that from
By filtering or centrifuging out the suspended
the true color can be determined.
(2) Color Test - Low Range, 0-100 APHA platinum cobalt units.
(a) Fill one of the color viewing tubes to within 1/16 inch of
the top with the water sample.
Insert the stopper in a manner so as
to expel any air bubbles.
(b) Place the lengthwise viewing adapter in the comparator.
(c) Insert the tube with the water sample into the back side
of the comparator in the opening nearest the middle.
(d) Fill the other sample tube with clear water and stopper in
a manner so as to expel air bubbles.
Insert this tube in the compara-
tor in the other opening in the back of the comparator.
(e) Hold the comparator up to a light such as a window, the
sky, or a lamp and view through the openings of the comparator.
Rotate the disc until a color match is obtained.
The reading obtained
through the scale window is the apparent color in APHA platinum
(3) Color Test - High range, 0-500 APHA platinum cobalt units.
(a) If the lengthwise viewing adapter is in place, remove it.
(b) Fill one of the tubes to the 5-ml mark with the water
(c) Insert the tube in the right top opening of the comparator.
(d) Fill the other tube to the mark with clear water and
insert this tube in the left opening of the comparator.