Degradation by silver permits determination of the distribution of activity inside the labelled molecule for thiosulfate and for the polythionates. When single salts are present, the reactions can be carried out either in solution or on the pherogram. In comparison, for mixtures of sulfur anions, it is necessary to perform previously a high voltage inonophoretic separation. The cutout zone of a definite anion is put on a new pherogram and the degradation by silver is carried out. The results correspond within the accuracy of measurement to the theoretical values.