It’s an etude in Ebony… and Ebony.
In 1939, Ernest Vincent Wright did something unusual. He took a piece of string, tied the letter “E” down on his typewriter, and wrote an entire novel. It was called “Gadsby: Champion of Youth” – and was a 50-thousand word “lipogram.” There’s not a single “E” in the book.
In one of Chopin’s crowd-pleasing and flashy études, he showed similar restraint.
Most people, when they learn how to play the piano, start with the key of C Major. It’s the easiest, because to play the major scale, you only play on the white keys.
You build up slowly, adding keys with sharps or flats, and then MORE sharps or flats; G-flat Major has 6 flats… Yet a lot of beginning piano players also know a little ditty played by rolling the knuckles over the group of three black keys, which is in the key of G-flat:
Chopin’s etude Opus 10, no. 5 uses that same pentatonic scale, completely avoiding white keys in the frenetic right-hand part, using ONLY the black keys.
In this light-hearted video on YouTube, pianist Lang Lang demonstrates how this makes it possible - sort of - to play the piece by rolling an orange over the keys with his right hand. - Jeffrey Freymann-Weyr