In Act 4, Scene 6, Voltore accuses Bonario and Celia of defamation for their remarks against Volpone in court. In a heated exchange with Bonario, Voltare uses verbal irony to disarm Bonario's bid to have Volpone tested for the diseases he claims to have:
Voltore: Would you ha’ him tortured?
Bonario: I Would have him proved.
Voltore: Best try him, then, with goads, or burning irons;
Put him to the strappado. I have heard
The rack hath cured the gout. Faith, give it him
And help him of a malady; be courteous.
I’ll undertake, before these honoured fathers,
He shall have yet as many left disease
As she has known adulterers, or thou strumpets.
If his statement is taken literally, Voltore would appear to suggest that the best route to test Volpone would be to subject him to torture—but the flippancy of his statement that "the rack" (a medieval torture device meant to dislocate a prisoner's joints by stretching them) "hath cured the gout" reveals his irony; Volpone will still be "sick" no matter what you throw at him. This sarcastic treatment of torture is an attempt to deflect Bonario's request, which would reveal Volpone to be a fraud, and Voltore succeeds in convincing the avocatori that Bonario and Celia are guilty of slandering Volpone.
The success and failure of the various characters in Volpone is almost entirely dependent on their ability to wield language in defense of themselves and their allies. This is made explicit in the court scenes of the play, in which the ultimate arbiters of justice—the avocatori—depend on verbal testimony (and therefore the use of language) to cast their judgement. In this scene, it is Voltore's passionate facility with irony and sarcasm that allows him to paint Bonario as a fanatic making baseless accusations against Volpone.
