In all these paintings it's really messy !
If we look at the left hand of the oldest man, we can see a flask, or a retort. The fact that he wears an Arabian suit, maybe this indicate that he was living there during a moment and were initiated to Alchemy by some Arabic Master. It is not a Lab here, but an oratory. An oratory is a place where you can rest, study, make some astrology and sky observations, also writing the lab journal.