Thanks Nick,
praise indeed.
Final update on the experiment.
I got the camera out to photograph what is left only to find that both samples have gone! evaporated totally, leaving just pale blue powder in the bottom of the jars - in a little over 24 hours!!
It has been fairly sunny and warm for Lancashire- but by no means hot.
Volatility and control of evaporation is obviously a major issue for correct storage. We all know about the water issue but this was a new one to me. As a result of this I am going to paint my storage tank reflective silver rather than the dark brown it is to help keep the temperature down on sunny days. It could do with a repaint anyway.
I have learned quite a bit about avgas from this thread, mainly not to take it for granted that it will be OK, and it MUST be treated properly.
PPrune at its best is a great educational safety resource.
At its worst it drives me nuts!
I agree, its never dull and usually fun.
Phil.