haunting images show the decaying ruins of holmesburg prison where scientists experimented on its prisoners .
inmates were paid to test a variety of dangerous substances such as radioactive , hallucinogenic and toxic materials .
renowned dermatologist who experimented on prisoners has claimed no harm was done to any of the ` volunteers '
the prisoners who led a 38-day hunger strike in 1938 were locked in ` the bake ovens ' where four ` roasted to death '