An inorganic chemical compound, AgI, that has a crystalline structure (symmetry; lattice spacing) similar to ice and a very low solubility in water, and can be easily generated as an aerosol. It was discovered by Bernard Vonnegut in 1947 after a search of the crystallographic tables as an effective nucleating agent for supercooled water. In cloud seeding applications it is usually combined with small amounts of other materials (e. G. , bromine, chlorine, copper) to enhance nucleating properties through change of lattice dimension to approach more closely that of ice.