The excruciatingly painful medical experiments went on until his body was disfigured by a network of scars. John Brown, an enslaved man on a Baldwin County, Ga., plantation in the 1820s and '30s, was lent to a physician, Dr. Thomas Hamilton, who was obsessed with proving that physiological differences between black and white people existed. Hamilton used Brown to try to determine how deep black skin went, believing it was thicker than white skin. Brown, who eventually escaped to England, recorded his experiences in an autobiography, published in 1855 as "Slave Life in Georgia: A Narrative of the Life, Sufferings, and Escape of John Brown, a Fugitive Slave, Now in England." In Brown's words, Hamilton applied "blisters to my hands, legs and feet, which bear the scars to this day. He continued until he drew up the dark skin from between the upper and the under one. He used to blister me at intervals of about two weeks." This went on for nine months, Brown wrote, until "the Doctor's experiments had so reduced me that I was useless in the field."
