Carbon Monoxide is the product of the imperfect combustion of carboniferous materials in internal-combustion writes James C. Edger-ton of the Bureau of Air Commerce. It is a colourless gas and in average concentrations is also odorless. In larger concentrations, where it is extremely dangerous, it has a slight garliclike odor.
Present in the exhaust gases of aviation engines in a ratio of from 2 to 7-per cent, of the total output, its greatest incidence occurs with large throttle openings) and rich mixtures, Engine breathers may also be a source of contamination, particularly where there are worn rings and distorted cylinder walls. There have been carbon-monoxide readings of as high as 2 per cent. from this source.
The inhaled air may be contaminated, by carbon monoxide in several ways. In single-engine aircraft, which are particularly prone to this type of poisoning, there may be seepage through the fire wall or through the fuselage openings. The engine exhaust may contaminate the slip stream and be} directly fed into the cockpit. Turbulence may produce the same effect in the case of multi-engined aeroplanes where the ventilation input is poorly located. Another prevalent source of trouble is a poorly designed heating system which depends upon circulation of exhaust gases about heating members. Hot-water heaters eliminate this source of difficulty,
Text read from the printed page and cleaned; old type leaves the occasional error.