I'll play:

The man turned blue due to his ingesting the chemicals--a systemic event. Coating yourself with a collodion emulsion and exposing it would be topical--the emulsion would be on top of the skin. One good scrubbing and the emulsion would be lost down the drain.

This kind of reminds me of the people who tape negatives on their skin and then go lay out in the sun for an afternoon. They get an image (sun tan) on their skin. No need to fix. But, as the skin grows and repairs itself, the image fades. Although, I remember one girl who put a Playboy Bunny sticker on her breast and spent the day at the beach. That night, she had a nice little white bunny for all to see. It got my attention. But then, I am always interested in new photographic techniques.