This work is a report on studies of the chemistry of astatine on a tracer scale, using the various methods of tracer chemistry. A general discussion of preparation of materials and analytical methods is included. The properties of astatine and its solutions as they appear in work on a tracer scale are discussed. Migration experiments show that astatine when ionized in aqueous solution is negatively charged. Electro chemical, solvent extraction, and carrying studies are presented. In general, (a) elemental astatine is extractable by organic solvents; (b) the - 1 state may be prepared by powerful reducing agents; and (c) at least two positive oxidation states exist.