Iodine is a chemical element, and a halogen. Iodine and its compounds are primarily used in nutrition, and industrially in the production of acetic acid and certain polymers. Iodine is also used in the production of tincture of iodine, a disinfectant.
At Wool's Orphanage, in 1938, after Billy Stubbs and Eric Whalley developed chicken pox, Mrs. Cole, the matron, told one of her helpers to take the iodine to Martha, so that she could disinfect their scabs.
- Harry Potter and the Half-Blood Prince (Mentioned only)