exchemist
Veteran Member
Listening to an interview with Susie Dent, the lexicographer well known to watchers of British TV game shows (yes, really), I was much taken with her description of the word "petrichor".
This is the name given by scientists, in the 1960s, to that special smell one gets after rain. People have spent quite a lot of effort to find out what is responsible.....and now we know: geosmin:
Chemically it is a sesquiterpenoid (and a bicyclic alcohol, as the drawing shows). Incidentally, it is often produced along with another compound, 2 methylisoborneol, which is not a million miles from my avatar - but that isn't important right now.
Geosmin is produced by certain soil bacteria and some of it gets released from the soil, as an aerosol, by raindrops. Interestingly, the human nose is extremely sensitive to this compound, being able to detect concentrations in the air down to as low at 0.4 parts per billion. There is speculation that this may have had a survival advantage for early man in semi-arid conditions, enabling detection of distant rain or moisture in the ground. "No' a lo' of people know that", as Michael Caine might say.
So now you know: next time you enjoy the smell after a shower of rain, think "geosmin".
This is the name given by scientists, in the 1960s, to that special smell one gets after rain. People have spent quite a lot of effort to find out what is responsible.....and now we know: geosmin:
Chemically it is a sesquiterpenoid (and a bicyclic alcohol, as the drawing shows). Incidentally, it is often produced along with another compound, 2 methylisoborneol, which is not a million miles from my avatar - but that isn't important right now.
Geosmin is produced by certain soil bacteria and some of it gets released from the soil, as an aerosol, by raindrops. Interestingly, the human nose is extremely sensitive to this compound, being able to detect concentrations in the air down to as low at 0.4 parts per billion. There is speculation that this may have had a survival advantage for early man in semi-arid conditions, enabling detection of distant rain or moisture in the ground. "No' a lo' of people know that", as Michael Caine might say.
So now you know: next time you enjoy the smell after a shower of rain, think "geosmin".