to be experimented with

Or if you're Winston Churchill, "with which to be experimented."

W.J. Henderson on Tetrazzini's debut at the Manhattan Opera Company, singing Traviata:

She sang staccato with consummate ease, though not with the approved method of breathing. Her method is merely to check the flow between tones instead of lightly attacking each note separately. But the effect which she produces, that of detached notes rather than strict staccato, is charming.

As quoted by Nicholas Limansky in Opera Quarterly, 2004.

Will investigate this more in a practice room tomorrow.