The average cost of bromine is $5 per 100 grams. Bromine is obtained from natural brine deposits. It is the only non-metallic element that is a liquid at ordinary temperatures. Bromine is less reactive than chlorine or fluorine but more reactive than iodine. It forms compounds with many elements and, like chlorine, acts as a bleaching agent. Bromine compounds are used as pesticides, dyestuff, water purification compounds, and as a flame-retardant in plastics. Potassium bromine is used as a source of bromide ions for the manufacture of silver bromide for photographic film.