Catalogued in RISM as “Pieces–B♭ major (Excerpts); Manuscript copy; US-WS SCM [39.3] Salem ms” by Anonymus. RISM 240461
Probable
Only the first section matches: its cello opening is the bass line (incipit 1.1.2) of the Kyrie of the Litany K. 125, found also in the partial-autograph parts. The other three sections are not identified.
Attributed copies compared (1 of 4 encoded incipits match):
1.1.1 Allo. molto · vlc · 12 of 12 pitches agree
,,{8B,B'D,B}{AGAF}/{BBBB}{DDDD}/{EEEE}{FFFF}/8,,{B,B'D,B}{AGAF}/{BBBB}{DDDD}/{EEEE}{FFFF}/also RISM 455013156 1.1.2
also RISM 659000817 1.1.3
1.2.1 Andante · vlc · no matching incipit among the attributed copies
{8,EE}E8-4-/{8EE}E8-4-/{8EE}{EFGA}/No encoded incipit matches this one.
1.3.1 Adagio · vlc · no matching incipit among the attributed copies
,,{6BBBBBBBB}{BBBBBBBB}/{BBBBBBBB}4B8-,B/{bGGGF}{nEEEE}/No encoded incipit matches this one.
1.4.1 Alla breve · vlc · no matching incipit among the attributed copies
,2B4BB/2B,,B/4-,BBB/4.B8,,B2B/No encoded incipit matches this one.
Catalogue data and incipits come from RISM (Répertoire International des Sources Musicales), CC BY 4.0. Incipits are rendered with Verovio. Source and data: https://github.com/aaymeloglu/rism-attributions.