Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. It consists of one carbon atom covalently bonded to one oxygen atom. It is made when carbon compounds burn and there is not enough oxygen. It is a good fuel and burns in air with a blue flame, making carbon dioxide. It is very toxic, but it is useful for modern technology as well.
The most important use for carbon monoxide in industry is making iron from iron ore. The carbon monoxide takes the oxygen from the iron ore when heated in a large oven called a blast furnace. Liquid metal iron is left behind. The carbon monoxide turns into carbon dioxide.
Carbon monoxide can accidentally form when there is too little air to burn all the fuel into carbon dioxide. Such a situation may happen if the oven shutters are closed too early or if a mobile cooker is used in a small tent with no ventilation (Ventilation is fresh air coming in and smoke going out). Many people have died from carbon monoxide poisoning. Carbon monoxide poisoning can cause feelings of paranoia and hallucinations, and has been determined to be a major cause of "haunted" houses. Small amounts of it are found in coal gas, a fuel produced by heating coal without any air.