Two Etudes for Four Fingers

On a whim awhile back, I worked on a set three pieces with the goal that each hand would use a fixed interval to see what I could come up with.  I finished two, the first using only thirds and the second using only octaves.  I started another etude using sixths, but tabled it after my initial efforts seemed uninspiring. 

The first etude in thirds is a simple barcarolle which I think would be easy to play.  The other etude in octaves, intended to be the third of the set, is a scherzo that probably is unplayable and would break the hands of any performer than tried it.  At the time I wrote it, I was studying the piano works of the French composer Charles-Valentin Alkan whose works are notoriously difficult so I think there may have been some influence from that.

I think they are good

I think they're OK. I like the second one more. Surely is not playable ¿?

For example at such velocity and in octaves the tremolos over the same not must be hard.

What a great idea for a writing exercise!  I actually really enjoyed the octaves, which makes me wonder if it would be worth just changing instruments to make it playable?  You could ask one of our resident organists if they had recommendations for stop choices to arrange it for organ, or designate it as a four-hand two-fingers piece?  :D 

Thanks for listening.  An organ versions or the octave etude is a good idea, thanks for the suggestion.