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b. 26

composition: Op. 10 No 4, Etude in C♯ minor

..

There are no naturals before the B-b octave in AI. It is a patent inaccuracy.

category imprint: Differences between sources

issues: Accidentals in different octaves

b. 27

composition: Op. 10 No 4, Etude in C♯ minor

..

In AI Chopin initially wrote the 6th semiquaver as c2, then he moved the note head one second up. The result of the correction is not entirely clear, as the accidental before the note became an illegible inkblot. 

category imprint: Corrections & alterations

issues: Enharmonic corrections

b. 29

composition: Op. 10 No 4, Etude in C♯ minor

..

The fact that Chopin heard the E minor key in this bar (and subsequent) is revealed by the lack of  lowering g1 to gin AI and at the same time by the presence of a  of g2 in the 2nd half of the bar.

category imprint: Interpretations within context; Differences between sources

issues: Omission of current key accidentals

b. 33

composition: Op. 10 No 4, Etude in C♯ minor

..

We add cautionary sharps before the 1st chord in the R.H. and the 1st semiquaver in the L.H. The signs before the chord were already added in GE4 (→GE5).

category imprint: Differences between sources; Editorial revisions

issues: GE revisions

b. 35-36

composition: Op. 10 No 4, Etude in C♯ minor

..

In both these bars, on the 12th, 13th and 16th semiquavers, AI has a c (in different octaves) and not a d. The correction from d2 to c2 on the 13th semiquaver in bar 35 indicates Chopin's hesitation, as eventually – in FE (→GE,EE) – all these notes were written as d

category imprint: Differences between sources; Corrections & alterations

issues: Chopin's hesitations , Enharmonic corrections