These Konzertstücke are virtuoso concertante works, but the Sonata in E-flat major, written by Mendelssohn in 1824, when he was only 15, is genuine chamber music: the clarinet and the piano are both used equally as a melody and an accompaniment instrument, but the demands on the clarinettist are far more modest than in opp.

For some time, the copy owned by the Deutsche Staatsbibliothek Berlin – Preußischer Kulturbesitz was the only known source of the work, on the title page of which the copyist noted in ink: "Sonate für B Clarinette u. Pianoforte / von Mendelssohn Bartholdi."

The following remarks were added by another hand, also in ink: "NB: Dieser Titel befindet sich nicht darauf [Refers to the version used by the copyist – probably the autograph], sondem bloß die Zu-Eignung an mich!

Baron Karl von Kaskel, who was also friends with Giacomo Meyerbeer and Richard Wagner, was a banker and a patron of the arts in Dresden.

Although the autograph[4] is now available again in the Pierpont Morgan Library, New York (from the Mary Flagler Cary Music Collection), it does not help to solve the problem concerning the Berlin copy.