Appendix B
Page 2
Formulation
8 gm of iodine crystals in a 3 oz glass bottle filled with water; 30-50 micron fabric
prefilter provided; "trap" in bottle to catch crystals when pouring off water; capacity:
2000 quarts; weight: 5 oz;
Instructions
The bottle cap is used to measure iodine solution. One capful is approximately 6.5 cc.
Directions and color dot thermometer are printed on the bottle. Recommended dose (2
capfuls if iodine solution is 20C) yields 4 ppm iodine when added to one quart of clean
water. Contact time depends on temperature of the water to be consumed; warm water to
20C (68F) before adding iodine to shorten contact time.
Comments
Saturated aqueous solution of crystalline iodine is an excellent and stable source of
iodine. Recommendations are adequate for clear, warm water; but, since it is not feasible
to warm all water, extend contact time to 1-2 hours for very cold water. Temperature of
the bottle affects the concentration of iodine in the saturated solution (200 ppm at 10° C,
300 ppm at 20° C, 400 ppm at 30° C),{Chang, 1953 #46;Gottardi, 1991 #83} which is the
reason for the color-dot thermometer on the bottle. In the field, it may be easier to warm
the bottle in an inner pocket than to estimate temperature and adjust the dose. The
supernatant should be carefully decanted or filtered to avoid ingestion of the
crystals{Zemlyn, 1981 #222}; this is aided by the weight of the crystals, which causes
them to sink. Many people prefer crystalline iodine because of its large disinfectant
capacity, small size, and light weight. The glass bottle can break.
