The Earth would then be burned clean of life in five billion years.
Hundreds of acres can be burned clean in minutes.
The torches burned clean, for no whisper of air stirred.
These can be odourless, burn clean with little smoke and are available in a range of flash points.
The flame burned clean, with no visible smoke or soot.
They'd been burned clean out of me.
You said yourself that these engines burn cleaner.
By contrast, we burn so clean that visitors coming into my house want to know how come it's so snug without the stove burning.
They found that gallon for gallon, the pork fat produces slightly less energy than oil, but it burns cleaner.
Besides reducing the reliance on imported oil, which is refined into gasoline, the alternative fuels generally burn cleaner.
