http://www-holmes.ch.cam.ac.uk/content/co2/co2projects.html (http://www-holmes.ch.cam.ac.uk/content/co2/co2projects.html)
Post 473343 (missing)
(lugh: "Crystallization/Recrystallization", Stimulants) for more information on crystallization/recrystallization ;) As far as a campfire procedure, you'd better stick with the coffee/tea pot; purifying alkaloids for human consumption under such conditions is likely to bee futile ;D