The manuscript notes the clarinet part as "Clarinetto in B" and uses the
written pitch. The viola part uses the C-
clef in the alto position. The labelling of the piano part shows a correction by Mozart where he started to write "Ce" (for "cembalo", the Italian word for the
harpsichord) and then replaced it with "Piano forte". However, this part is labelled "Cembalo" for the second and third movements. The
key signature of
E major in Mozart's late chamber music indicates close friendship. The trio consists of three
movements: {{Ordered list|type=upper-roman The first movement is not the more traditional Allegro as an opening movement, but a more contemplative Andante. Following on from this, the second movement is of course not the traditional slow movement, but a moderate Menuetto, and the last movement, while lively, is not the standard Allegro. In short, the contrasts in tempo in this trio are not as stark as in most piano trios.
I. Andante The Andante is written in the
time signature of
time and consists of 129
bars; a typical performance would last just over six minutes. It
repeats neither its exposition nor the remainder of the movement, which is unusual for Mozart's mature chamber music. A particularly recognizable feature of this movement's principal theme is the
gruppetto (turn) which appears 67 times.
II. Menuetto The second movement is written in
time and consists of 158 bars, almost all of which are repeated; a typical performance would last about six minutes. The key signature of this movement is
B major, the
dominant key to E from the first movement. The opening menuetto of this movement consists of the exposition of a four-bar theme (bars 1–12, repeated), and its
development (bars 13–41, also repeated). The piano's pounding bass line and sharp dynamic contrasts set the mood of this theme apart from any conventional light and frilly notions of a Minuet. During the development, the dialogue between the instruments becomes intensified, and Mozart shows his grasp of
counterpoint without ever sounding academic or "learned". The following trio opens with a
chromatic four-note phrase, to which the viola responds with a run of lively
triplets, accompanied by chromatic chords from the piano (bars 42–62, repeated). In the development of that theme, the four-note phrase and the lively triplets are then taken up by the piano, and clarinet and viola present some chromatically rising lines, before all three instruments start a
concerto-like conversation where the 4-note phrase is only heard twice in the piano left hand (bars 63–94, repeated). The final part of the trio starts with a variation of the trio's four-note phrase, which is briefly developed (bars 95–102) before returning to the brighter theme of the Menuetto whose treatment ends the movement without repeats.
III. Rondeaux: Allegretto The last movement is written in the time signature of
cut common time (or
alla breve, similar to ) and consists of 222 bars; a typical performance would last eight and a half minutes. The key signature, as is conventional, is the same as the opening movement, E-flat major. The musical format of this movement is a seven-part rondo, a rarity in Mozart's work; this seven-part structure also explains the title
Rondeaux, the French plural form of
Rondeau. The structure is AB–AC–AD–A. Theme A is an eight-bar
cantabile melody in two parts, drawn from the first movement and presented first by the clarinet, then taken up as a
variation by the piano (bars 1–16). The melody of theme B – in B major – is played once by the clarinet (bars 17–24) before the piano plays an intermezzo of several bars. From bar 36 onwards, all three instruments play short phrases of that theme in turn, followed by a piano solo until bar 50. Theme C – in
C minor – is presented by the viola and repeated (bars 67–76); all three instruments develop that theme in bars 77–90 (repeated). This development visits the
subdominant minor scale (
vi) of
F minor before ending in the
relative key of C minor. Theme D – in A major – is introduced in bar 116 by all three instruments almost in
unison, and elaborately developed in bars 132–153 (repeated). In contrast to the previous development, this goes through the subdominant
major scale (VI) of
A-flat major. With the playful
coda of bars 191 to 222, Mozart concludes the composition, "that does not merely satisfy the listener, but leaves him enchanted!" ==References==