[en] The determination of 14 trace elements, namely As, Ag, Bi, Cd, Cu, Ga, Ge, Hg, In, Pb, Sb, Sn, Tl and Zn, in silicate rocks using d.c. arc optical emission spectrography (O.E.S.) and X-ray fluorescence spectroscopy (X.R.F.) was investigated. X.R.F. was shown to be capable of determining Cu, Ga, Pb and Zn in normal silicate rocks and Sn, As and Ge in samples enriched in these latter three elements. Improvement of the sensitivity of the trace elements selected employing d.c. arc excitation in artificial atmospheres was examined in detail. Excitation in argon, argon-oxygen and nitrogen resulted in many advantages. Several successful methods of overcoming these reduced volatilization rates were found. Increased amperage coupled with a special electrode design was one while the use of a small carrier electrode was another. The investigation demonstrated that all the elements chosen could not be determined using a single spectrographic method. The application of d.c. arc excitation in an atmosphere of argon to the determination of the volatile trace elements in non-silicate or other matrices, which do not form carbides, would appear to be a promising possibility