Physiological Action of Carbon Monoxide

Carbon monoxide gas is very poisonous to man and animals. As early as 1716 the poisonous nature of the fumes arising from burning charcoal was recognised by F. Hoffmann. Many deaths have been caused by breathing the gas arising from imperfectly burnt charcoal, or air mixed with coal-gas.

The poisonous action of carbon monoxide is generally supposed to be due to the formation with the haemoglobin or red colouring-matter of the blood of a compound, carboxyhsemoglobin, which is much more stable than the compound oxyhaemoglobin which oxygen forms. Thus the activity of the blood as an oxygen-carrier is seriously or fatally inhibited. The absorption coefficient of blood for carbon monoxide is 0.022. Blood becomes more purple by the absorption of carbon monoxide, and when diluted forty times shows an absorption spectrum containing two bands between the D and E lines, which much resembles that of oxygenated blood. The spectrum of the latter is, however, modified by the reducing action of ammonium sulphide or ammoniacal ferrotartrate, whilst that of blood containing carbon monoxide remains unchanged for several days after the addition of a reducing agent. The spectroscopic estimation of carbon monoxide in blood has been elaborated by Hartridge. According to Giocoso, the theory that carbon monoxide poisons by replacing oxyhemoglobin by carboxy-haemoglobin can no longer be maintained. Carbon monoxide appears to have no effect upon the germination of seeds or the action of ferments, though it retards the. catalytic action of finely divided platinum.