Here are some helpful exercises for the C Minor etude:
The following exercises apply to measures 22 through 24:
First try these octave slurs slowly and smoothly and with a full tone:
Try playing through them again using the same type of air, but a softer dynamic
Now Experiment with the following exercises:
Play through them slowly and gradually increase the speed.
The First time through play them Forte, them Mezzo Forte, then try Piano using
the same speed air through each run through
Now play through measures 22- 24 slowly, smoothly, and with a full tone.
(Make sure there are no gaps in your sound)
Play through again, following the dynamics written on the music.
Any Other Suggestions are Welcome!