Historically alchemy ( Spagyrics to be precise in reference on the game) was known by christian monks , mostly living in monasterys , where in parallel of the monastic life , they were taking care of the gardens , full of medical herbs and plants . They where skilled in this rude chemisrty art by preparing infusions , creams , essential oils , alcholic distilates with erbes and so on.
Alchemy ( as mentioned by some users ) was the " art " of change the state of metals , using also strange and esotreic methods to fabricate the fine gold. This was ,( and is ) a handed down knoledge , hidden by the most.
So it would be a good idea to change the Alchemy reference with Spagyrics. And it would be a very good idea to implement at least one , well done , monastery . ( ideal also for some secondary quests. )
Here an interesting link http://www.fordham.edu/halsall/medny/herbgdn1.asp .