Once upon a time there was an artist called S. Salz...

Who was the artist S. Salz? Was it a man or a woman? Sarah or Salomon? What was he or she doing in Berlin in 1921? How old was he or she at the time? Was he or she an established artist or just an artist struggling to break through? Who's portraits were these? Were they drawn with the subjects modeling in front of the artist? Or were they the elaboration of a quick sketch from a fleeting moment? An observation of a character, of an expression, of the face of an acquaintance or of a complete stranger to the artist?

Any information concerning the mystery of S. Salz would be greatly appreciated...