This compound is formed when a substance containing carbon is burned
in an insufficient supply of air, as for example when the draught is
partly shut off in a stove.
[Sidenote: Properties of carbon monoxid]
Carbon monoxid is a colorless gas. It burns with a blue flame, forming
carbon dioxid. The blue flame seen playing over the embers of a coal
fire is carbon monoxid burning. This gas is extremely poisonous. Carbon
dioxid, CO₂, is not poisonous. The poisonous properties of illuminating
gas are due to the carbon monoxid which it contains.