The physical processes of PIXE are described, underlying its advantages as an analytical tool and the practical limitation met in the compositional patterning of ancient bronzes, irons, and glasses. Controlled variation of the energy of the proton beam and the use of selective filters in the x-ray detection system allows certain background effects from the x-ray output of the dominant elements to be significantly reduced. Plans for a new beam line for the Bartol PIXE facility are also described. This system will provide for a beam diameter as small as 20 micrometers with a laser-based optical system that will allow for the precise location of the proton beam on the artifact's surface. This sytem will enable one to study inhomogeneous materials, such as metal residues trapped in smelted slag, solder joints in classical jewelry, and islands of metal in heavily corroded artifacts. See also AATA 23-1923 for related study. -- AATA