From the Richmond Dispatch, 1/24/1863, p. 2, c. 3
Disinfectants. – About two weeks since the commanding officers at the Libby Prison and Castle Thunder resorted to the expedient of burning tar and scrap leather in those prisons to keep away the small pox, which has been very successful thus far in keeping the disease at a distance, very few, if any, cases having occurred in either prison since the remedies have been used.