TM 10-4320-303-13
Figure 2-51. Preparation of Sample Cells.
e. Rinse and fill two clean 15 ml sample cells (Figure 2-51, 1) to 15 ml mark (2) with water from manual
disbursing station.
f. Hold the comparator with the prism eyepiece (Figure 2-50,1) facing you and insert one of the water
filled sample cells (Figure 2-51, 1) into the right- hand sample space (3). Insert the second water
filled sample cell (4) into the left-hand sample space (5).
g. Fill the droppers in the arsenite and orthotolidine bottles and let the dropper caps sit loosely in the
bottles. Do not screw the caps back on the bottles.
NOTE
Readings must be made within one minute of adding chemical to indicator cell.
h. Squirt with force one dropper full (not less than 0.75 ml) of arsenite (red cap) solution into the right-
hand sample cell (3). Then squirt with force one dropper full (not less than 0.75 ml) of orthotolodine
(yellow cap) solution into the right-hand sample cell (3).
i. Refill the arsenite and orthotolodine droppers and let the droppers sit loosely in the bottles.
j. Squirt with force the dropper full of orthotolodine (yellow cap) solution into the left hand sample cell
(5). Immediately squirt with force the dropper full of arsenite (red cap) solution into the same cell (5).
This is the indicator.
Figure 2-52. Viewing Water Samples
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