Ten Septimius Severus denarii, minted in A.D. 196, were recleaned and reanalyzed three times by x-ray fluorescence in order to determine the precision obtainable on inhomogeneous coins. For highest precision, a given coin must always be positioned with the same orientation during x-ray fluorescence analysis. Good to excellent precision was obtained for determinations of seven elements in all the coins indicating that inhomogeneities in these coins do not adversely affect the analytical results. Treatment of the denarii for 10 s in 1:1 nitric acid caused marked depletion of copper and iron and enrichment of silver, gold, and lead. Tin and antimony concentrations were unaffected by the acid treatment. -- AATA