This question is directly inspired from this one on French Language Stack Exchange.
I have tried to provide an answer, but, as non specialist, I feel it can be considered as opinion-based.
So, my question here is double:
- What to think about this particular case ("chemist" or "alchemist")?
- And more globally what is the good way to forge an opinion in such a case?
Following the comment of Hamlet, I try here to explain my reasoning about this translation (but my English is poor and saying all this is not self evident... sorry about that).
I think Baudelaire could have chosen the word "alchemist" if he though it was the good/appropriated one. But he did not.
Surely there is the alexandrine aspect, and due to that we can not have:
Sur l'oreiller du mal c'est Satan Trismégiste
Qui berce longuement notre esprit enchanté,
Et le riche métal de notre volonté
Est tout vaporisé par ce savant alchimiste (13 syllables).
And we can't either have
Est vaporisé par ce savant alchimiste (because we lose here the two hemistichs)
But (even if less pleasant), it can be:
Est tout vaporisé par ce grand alchimiste (12 = 6 + 6 syllables... even if Trismégiste is already "three times great"...)
Or any other formulation that surely Baudelaire was able to elaborate.
On another plane, there is the meaning aspect:
The first one is near context "riche métal" ("rich metal") which recalls gold, added to "enchanté" ("bewitched") et "vaporisé" ("vaporized")... which all could tend to alchemy.
The second is the overall poem context: Baudelaire is talking about our human condition, something totally real which is not related to false beliefs (alchemy). And presuming Satan is part of this reality (or simply an allegory), he is surely skilled enough to make usage of a real science.
So, to summarize, my opinion is "chemist" is more appropriate. But I'm in hope to find here a more accurate and expert explanation.