C 2730 (OTTO) Cuprous iodide, 99% Cas 7681-65-4 - used in cloud seeding, altering the amount or type of precipitation of a cloud, or their structure by dispersing substances into the atmosphere which increase water's ability to form droplets or crystals. C 2730 (OTTO) Cuprous iodide, 99% Cas 7681-65-4 - used in the synthesis of fine chemicals, and as a heat and light stabilzer for nylon fabrics.