| 摘要 |
PROBLEM TO BE SOLVED: To make detectable a counterfeit paper money by applying a liquid containing iodine to a paper money and observing the change in color of a part with the liquid applied thereto a prescribed time later. SOLUTION: A liquid is applied to a paper money to detect a counterfeit paper money and the change in color of a part with the liquid applied thereto is observed visually a prescribed time later so that a genuine paper money is identified from a counterfeit paper money. When being the genuine one, the color before applying the liquid and the color after the lapse of a prescribed time is the same, however, when being the counterfeit one, the color before applying the liquid and the color after the lapse of the prescribed time is different. The part with the liquid applied thereto is changed into dark blown or bluish purple so as to identify one from the other. The liquid composed of iodine and appropriate solvent, and single or a plurality of solvents selected from the group composed of water, ketone group, ester group, ether group, alcohol group, and alkali metal iodide solution are suited thereto. Among the ketone group usable to the liquid are acetone, methyl ethyl ketone, diethyl ketone, propyl ketone, etc.
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