Sentence:  [...] "It nothing skills: I cannot help my case: / 'Tis the Last Judgment's fire must cure this place, / <WSD>Calcine</WSD> its clods and set my prisoners free." 
Meaning of the word marked with <WSD> tags:  to heat something without melting in order to drive off water etc., and to decompose carbonates into oxides or to oxidize or reduce it; especially to heat limestone to form quicklime, i.e. to calcinate.