Hey I just gotta pitch in with my Rube Goldberg CO2 detector...

Aren't we all forgetting that old junior school experiment where we blow into the limewater and it turns milky? Well, u get the idea: a pump that forces the sample gas through a glass of limewater, and some turbidity measurement device (LED-photodiode would be simplest). 'Nuff said.

The biggest limitation is that once the limewater turns milky, it can turn unmilky (or unturn milky) with passage of more CO2, possibly giving erroneous results, so its a once-use only. But then so was the canarycide technique. And its helluva lot simpler to automate refreshing a glass of limewater than replacing a dead canary nailed to its perch.

kundi