| abstract |
This means of security against the chemical falsification of parts drawn up on paper or on coated synthetic supports comprises at least one cobalt salt of oxidation degree 2, giving an orange reaction in the presence of a sodium bisulphite solution. Advantageously, the cobalt salt is chosen from the group comprising cobalt sulfate, cobalt chloride, cobalt acetate, cobalt nitrate, cobalt thiocyanate, cobalt acetylacetonate. |