This will be a stumper. Many art-nouveau style typefaces were released in Continental Europe at the beginning of the 1900s. The one most similar to this that I can find in Seemann’s Handbuch (a good reference for metal type of that era) is Roland from the Ludwig Wagner foundry, but there are many others that are quite similar that could have been released earlier.
Roland from Seemann’s Handbuch, courtesy Hans Reichardt, Klingspor-Museum
As for digital fonts, there isn’t anything too close. Freeform 710, based on Eckmann but with more Roman-style caps, may be your best bet.