Sorry I meant rainbow étude yes 10-8
Wow that's what you get for posting w a horizontal iPhone where I couldn't see what I was typing for some reason
The nickname (given by someone other than the composer himself) for Opus 10 no. 8 is "Sunshine" - not "Rainbow." You were correct the first time!!
For the record - the other nicknames are....
Op. 10, 12 Études:
No. 1: Étude in C major, Waterfall (composed 1830)
No. 2: Étude in A minor, Chromatic (1830)
No. 3: Étude in E major, Tristesse, or L'adieu (1832)
No. 4: Étude in C-sharp minor, Torrent (1832)
No. 5: Étude in G-flat major, Black Keys (1830)
No. 6: Étude in E-flat minor, Lament (1830)
No. 7: Étude in C major, Toccata (1832)
No. 8: Étude in F major, Sunshine (1829)
No. 9: Étude in F minor (1829)
No. 10: Étude in A-flat major (1829)
No. 11: Étude in E-flat major, Arpeggio (1829)
No. 12: Étude in C minor, Revolutionary (1831)
Op. 25, 12 Études:
No. 1: Étude in A-flat major, Aeolian Harp, or Shepherd Boy (composed 1836)
No. 2: Étude in F minor, The Bees (1836)
No. 3: Étude in F major, The Horseman (1836)
No. 4: Étude in A minor (1832–1834)
No. 5: Étude in E minor, Wrong Note (1832–1834)
No. 6: Étude in G-sharp minor, Thirds (1832–1834)
No. 7: Étude in C-sharp minor, Cello (1836)
No. 8: Étude in D-flat major, Sixths (1832–1834)
No. 9: Étude in G-flat major, Butterfly (1832–1834)
No. 10: Étude in B minor, Octave (1832–1834)
No. 11: Étude in A minor, Winter Wind (1834)
No. 12: Étude in C minor, Ocean (1836)
The composition dates are "approximate."
Now back to the Torrent.......