On this Thorndyke opened his research case and brought forth the two bottles that Polton had procured from the Borough; of which one was labelled “Tinct. Guiaci Dil.” and the other “Æther Ozon.” As they emerged from the case Phillip read the labels with evident surprise, remarking:
“I shouldn’t have thought that the guiacum test would be of any use after all these months, especially as the sail seems to have been scrubbed.”
“It will act, I think, if the pigment or its derivatives are there,” said Thorndyke; and, as he spoke, he poured a quantity of the tincture on the middle of the stained area. The pool of liquid rapidly spread considerably beyond the limits of the stain, growing paler as it extended. Then Thorndyke cautiously dropped small quantities of the ozonic ether at various points around the stained area and watched closely as the two liquids mingled in the fabric of the sail. Gradually the ether spread towards the stain, and, first at one point and then at another, approached and finally crossed the wavy grey line; and at each point the same change occurred: first the faint grey line turned into a strong blue line and then the colour extended to the enclosed space until the entire area of the stain stood out a conspicuous blue patch. Phillip and Thorndyke looked at one another significantly and the latter said: “You understand the meaning of this reaction, Rodney; this is a blood stain; and a very carefully washed blood stain.”
“So I supposed,” Rodney replied; and for a while no one spoke.
There was something very dramatic and solemn, they all felt, in the sudden appearance of this staring blue patch on the sail with the sinister message that it brought. But what followed was more dramatic still. As they stood silently regarding the blue stain, the mingled liquids continued to spread; and suddenly, at the extreme edge of the wet area, they became aware of a new spot of blue. At first a mere speck, it grew slowly, as the liquid spread over the canvas, into a small oval, and then a second spot appeared by its side. At this point Thorndyke poured out a fresh charge of the tincture, and when it had soaked into the cloth, cautiously applied a sprinkling of ether. Instantly the blue spots began to elongate; fresh spots and patches appeared, and as they ran together there sprang out of the blank surface the clear impression of a hand—a left hand, complete in all its details excepting the third finger, which was represented by a round spot at some two thirds of its length.
The dreadful significance of this apparition and the uncanny and mysterious manner of its emergence from the white surface produced a most profound impression on all the observers, but especially on Rodney, who stared at it with an expression of the utmost horror, but spoke not a word. His brother was hardly less appalled, and when he at length spoke it was in a hushed voice that was little above a whisper.
“It is horrible!” he murmured. “It seems almost supernatural, that accusing hand springing into existence out of the blank surface after all this time. I wonder,” he added after a pause, “why the third finger made no mark, seeing that the others are so distinct.”
“I think,” said Thorndyke, “that the impression is there. That small round spot looks like the mark of a finger-tip, and its position rather suggests a finger with a stiff joint.”
As he made this statement, both brothers simultaneously uttered a smothered exclamation.
“It is Varney’s hand!” gasped Phillip. “You recognize it, Jack, don’t you? That is just where the tip of his stiff finger would come. Have you ever noticed Varney’s left hand, Thorndyke?”