Which preposition to use with impromptu

In Occurrences 6%

Impromptu In C-sharp minor.

on Occurrences 5%

Piacermi Vuoi' Lines Written under a Print representing Persons Skaiting Translation of a Speech of Aquileio in the 'Adriano' of Metastasio, beginning, 'Tu Che in Corte Invecchiasti' Impromptu on Hearing Miss Thrale Consulting with a Friend about a Gown and Hat she was inclined to Wear Translation of Virgil, Pastoral I Translation of Horace, Book i. Ode xxii.

for Occurrences 1%

As for the literary soirée, the most profound silence has been maintained concerning it, neither of the wits there assembled having seen fit to celebrate it in rhyme, and Florio having actually torn up an impromptu for the occasion, that he had been all the previous day writing.

from Occurrences 1%

"But these crude suggestions, which fall almost impromptu from my lips, suggest that which I desire to offer before this audience to-night.

of Occurrences 1%

A clever impromptu of this class has been recorded as given by a judge's lady in reply to one made by the witty Henry Erskine at a dinner party at Lord Armadale's.

to Occurrences 1%

" He cast his eyes up at the ceiling, and then, releasing Gracie's hand, brought his impromptu to a close with a few soft chords.

Which preposition to use with  impromptu