Barium green color. Barium sulfate is used as an insoluble additive to oil well drilling fluid, as well as in a purer form, as X-ray radiocontrast agents for imaging the human gastrointestinal tract. The soluble barium ion and soluble compounds are poisonous, and have been used as rodenticides. Barium is a soft, silvery-white metal, with a slight golden shade when ultrapure. The silvery-white color of barium metal rapidly vanishes upon oxidation in air yielding a dark gray oxide layer. Barium has a medium specific weight and good electrical conductivity. Ultrapure barium is very difficult to prepare, and therefore many properties of
Potassium chlorate are much more expensive. Chlorate propellants must be used only in equipment designed for them; failure to follow this precaution is a common source of accidents. Potassium chlorate, often in combination with silver fulminate, is used in trick noise-makers known as "crackers", "snappers", "pop-its", or "bang-snaps", a popular type of novelty firework. Another application of potassium chlorate is as the oxidizer in a smoke composition such as that used in smoke grenades. Since 2005, a cartridge with potassium chlorate mixed with lactose and rosin is used for generating the white smoke signalling the election of new pope by a papal