My dissertation is actually about the origins of the drug trade, but I think you'd be interested in the journalist George Pendle's Parsons biography, Strange Angel, which I think does a great job of teasing out what alchemy meant for 1940s practitioners: http://www.amazon.com/Strange-Angel-Otherworldly-Scientist-W...

I also touch on the topic a bit (albeit from the perspective of the history of medicine) in the Aeon article that I link to further down in the comments, although that's also aimed at more of a popular audience. Another person who you might find interesting is Pamela H. Smith of Columbia University, who's actually recreating an early modern alchemical lab there as we speak.