§ Mr. Russellasked the Parliamentary Secretary to the Ministry of Works, as representing the Lord President of the Council, if he will list the chief components of the exhaust gases from diesel engines; and why some engines emit brown smoke while the exhaust of others is colourless.
Mr. BeviesWith a diesel engine properly maintained and operated, the exhaust fumes contain a small amount of solid carbonaceous matter and the follow-86W ing gaseous constituents, listed in descending order of concentration: nitrogen, carbon dioxide, oxygen, carbon monoxide, oxides of nitrogen, hydrogen, hydrocarbons, oxides of sulphur and aldehydes. If the engine is not properly maintained and operated, the concentrations of carbon monoxide. oxides of nitrogen, hydrogen and hydrocarbons are higher; in addition there may be sufficient solid carbonaceous matter to produce blue-grey or brown smoke and, in extreme cases, a dense black smoke. The emission of visible smoke from a diesel engine is due to the engine being in poor condition, or to over-loading or to maladjustment of the fuel control by the driver.