well ... sort-of.
I followed the directions for the "energiatype" process, substituting potassium bromide for sodium chloride. The developer was a 4% solution of FeSO4.
The results are interesting. The upper right corner has a visible image. You can see the visible trim on the house (vertical white line), and the top of my business partner's head. The rest of the image turned pure black in the developer (white in the inverted scan).
This was done on Clearprint 1000H vellum. Exposure was 75 seconds in direct, late-afternoon sun. The image came up *immediately* when the developer was brushed on.