Who ate fire in paint hotels or drank turpentine in Paradise Alley, death, or purgatoried their torsos night after night
“Fire” and “turpentine” may be drug-related slang terms, or this could be comic/hallucinatory exaggeration of the type that runs throughout the poem. The point here is that they are putting toxic, bordering on lethal, substances into their bodies. Paradise Alley was a slum in NYC. Evidently, the landscape was plentiful with run-down motels, and brothels, and dope slingers.
Dante’s purgatory is a mountain between heaven and hell where you are saved, and destined eventually for heaven, but must be purified or undergo temporary punishment. “Purgatory” here is a play on words—rather than simply “purge” their stomachs they are undergoing a more harrowing, more spiritual process.
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