Op. 10 No 12, Etude in C minor

First French edition, based on A. The comparison with the autograph, as well as visible traces of corrections, reveal a number of more or less probable changes performed in print. Some of them were included in GE, some not, which indicates the existence of at least two stages of proofreading of FE1 (probably even three – see the Etude in C major, No. 1). Chopin's participation in all stages of proofreading and their broad range is revealed by the preserved correspondence between Schlesinger and Kistner, and their palpable proof is constituted by FEcor (in the Etude in A minor, No. 2). Examples of changes performed at particular stages of proofreading:

• 1. Changes included in GE1 – all corrections of the original versions mentioned in the characteristics of A, in addition, adding  hairpins in bars 2, 4, 12, slurs in the R.H. in bars 22-24,  in bars 43 and 45, ties sustaining the es¹-es² octave in bar 57, change of triplet slurs to phrase marks in bars 52, 56 and 60. In this stage of proofreading Chopin added also a detailed fingering and completed a significant part of necessary accidentals, also unobvious ones, e.g., in bar 75;
• 2. Changes not included in GE1 – adding a tie sustaining a² in bars 14-15, con forza in bar 15, dim. in bar 18 and sotto voce in bar 20. 

Apart from the above illustrated changes and additions, being undoubtedly a result of Chopin's intervention, in FE1 a number of differences with regard to A appears, whose qualification as authentic corrections is unclear or even dubious. Above all, it concerns the overlooked performance indications, e.g.:

• indications concerning dynamics – signs in bars 2, 5, 62 and 79,  in bar 45,  and  in bars 61-62,  in bars 80-81,  in bar 83;
• other indications – energico in bar 2, sempre legato in bar 5, appassionato in bar 10, wedges in bars 17 and 62.

According to us, a vast majority of these situations is a result of the engraver's haste. It may be even assumed that it was a more or less conscious strategy, as omitting a sign did not increase the workload (even if Chopin wrote a sign during a proofreading, adding it was not related to any additional effort), while engraving an erroneous sign required its burdensome deletion. However, in certain fragments in which, next to the aforementioned deficiencies, other signs or changes introduced in a proofreading of FE appear, one can assume the entire text to be proofread and accepted by Chopin. Therefore, we analyse each of these types of places individually in order to, on the one hand, respect the possible latest intention of Chopin and, on the other hand, not to deny the performer valuable authentic indications, which could have been omitted by accident.

In spite of a multi-level proofreading, FE1 is not free from evident errors, e.g., in the rhythmic values of the lower voice in bar 75.

Despite the fact that it was A that was base text for FE1, in the edition there are visible traces of proofreading of the versions which are not present in this autograph, e.g., deleted e¹ on the 4th beat of bar 2, deleted A₁-c at the beginning of bar 41 or the flat of d in bar 68. It is hard to determine how it occurred, yet the deleted notes may always be considered as accidental errors.