Many years ago (50+) as an industrial chemist I used to check for complete combustion by analyzing the flue gas with an “Orsat” which was a very simple device which bubbled a fixed quantity of flue gas (100ml) through various solutions namely sodium hydroxide, oxy-pyrogallol and ammoniacal cuprous chloride to measure the levels of carbon dioxide, oxygen and carbon monoxide respectively. Is this simple but efficient technique still used or are solid state sensors now the norm?
Thank you
Barry