3 was repeated but the color developer substance used was 3 5 di tertiary butyl salicylate equivalent results were obtained a fingerprinting pad was impregnated with an inkless solution prepared by dissolving 1 6 parts of i br 0 2 parts of i gd 0 2 parts of i 6b and 0 25 parts of blmb in 50 parts of monoisobutyl biphenyl fingerprints were made on a paper substrate containing 2 hydroxy 4 methyl 5 isobutyl thiobenzoic acid as the color developing material black highly distinct intense fingerprints were obtained example 1 was repeated but 10 gms of a 16 solution of zinc octoate in mineral spirits were mixed with the inkless fingerprinting solution prior to impregnating the pad fingerprints of even higher intensity than those in example 1 were obtained example 6 was repeated but the inkless fingerprinting solution was prepared by dissolving 2 2 parts of i br 1 1 parts of i 6b 2 3 parts of i gd and 0 6 parts of cvl in 94 parts of monoisopropyl biphenyl equivalent results were obtained example 6 was repeated but the color developing substance was 5 octyl salicylic acid equivalent results were obtained example 9 was repeated but the color developing substance was the zincated salt of 5 octyl salicylic acid fingerprints of even higher intensity than those in example 9 were obtained a pad was impregnated with an inkless solution which was prepared by dissolving 3 2 parts.