The reaction between Hg(I) and ethyleneglycol bis (β-aminoethylether)- N, N, N3, N3 tetraacetate (EGTA) in a weakly acidic médium (pH ≈ 5) is studied by U. V. spectrophotometric techniques. The maxiraum of absorption which appears at 247 nm is supposed due to the formation of a Hg(I) - EGTA complex. This compotmd is unstable and it decomposes slowly with formation of Hg(II) chelate and metallic mercury. When the absorbance is measured at fixed time (5 minutes), it is fovmd that Beer's law is obeyed from 1 up to 30 p p m of Hg(I) at 247 nm
