In acute carbonic oxide poisoning oxygen inhalation indefatigably continued and supported by artificial respiration is often successful. The serious danger from this form of poisoning renders it very necessary that in all premises where there is risk provision should be made for the administration of oxygen. The sequelæ can of course only be treated symptomatically.
OXYCHLORIDE OF CARBON (PHOSGENE)
Oxychloride of carbon (COCl₂), also called phosgene, is, at the ordinary temperature, a colourless gas with a disagreeable smell. This decomposes in moist air into carbonic oxide, hydrochloric acid, or chlorine, and produces a strongly irritant local effect upon the mucous membranes. Industrial poisoning by phosgene is characterised by great difficulty in breathing and inflammation of the respiratory tract (bronchitis and bloodstained expectoration).
Several cases have been treated successfully by oxygen inhalation.
NICKEL CARBONYL
The effects of nickel carbonyl are described on pp. [186-8].
CARBONIC ACID
Carbonic acid (CO₂), a colourless gas, is heavier than air (specific weight, 1·526), and therefore, wherever it collects, sinks to the ground. Carbonic acid is only very slightly poisonous; about 10 per cent. carbonic acid in the air causes asphyxia. The extinguishing of a candle flame will serve as an indication that the amount of carbonic acid in the atmosphere has reached this point. Cases of industrial carbonic acid asphyxia are sudden; they do not occur frequently.
The gradual action of the gas when mixed with air produces first a tingling sensation on the surface of the body, reddening of the face, irritation of the mucous membrane and the respiratory organs, after which succeed difficulty in breathing, palpitation, fainting, and unconsciousness.