"Exactly!" He answered me rather absently, being concerned in setting out the apparatus he would need for a hasty series of tests.
"Will the antivenin show in the blood after four, perhaps five days?"
"I should say so, Walter. If it does not, by any chance, I will be able to identify the blood, but that is much more involved and tedious—a great deal more actual work."
"I've got it straight, then. Now—" I paced up and down several times. "The finger-nail files should show a trace of the itching salve? Is that correct, Craig?"
For a moment he didn't answer, as his mind was upon his paraphernalia. Then he straightened. "Hardly, Walter! The salve is soluble in water. What I shall find, if anything, is some of the fibers of the towel. You see, a person's finger nails are great little collectors of bits of foreign matter, and anyone handling that rag is sure to show some infinitesimal trace for a long while afterward. If the person stealing the towel filed or cleaned his nails there will be evidence of the fibers on his pocket knife or finger-nail file. I impregnated the towel with that chemical so that I would be able to identify the fibers positively."
"The use of the itching salve was unnecessary?"
A quizzical smile crept across Kennedy's face. "Did you think I expected some one to go walking around the studio scratching his hands? Did you imagine I thought the guilty party would betray his or her identity in such childish fashion, after all the cleverness displayed in the crimes themselves?"
"But you were insistent that I rub in the—"
"To force them to wash their hands after touching the towel, Walter."
"Oh!" I felt rather chagrined. "Wouldn't some pigment, some color, have served the purpose better?"