This site introduces unknown Emanuel Bach (C. P. E. Bach).
ChatGPT4o writes as follows (please note that it may not be accurate):
Emanuel Bachʼs character piece "Stahl" (Stahl, Wq. 117/25) is a work featured in the 1765 collection of character pieces, known for its calmness and lyricism. The piece is in the key of C major, with a gentle and stable melody that imparts an intimate and warm atmosphere throughout the composition. The title "Stahl" is believed to be derived from a friend, supporter, or a specific individual known to Bach, reflecting respect or emotions towards that person. The piece exhibits characteristics of the Empfindsamer Stil (sensitive style), with subtle expressions and harmonic ingenuity that are captivating. Performers are required to express the elegance and emotional delicacy of this piece.