By placing the gem inside a glass bell, and exhausting as much air as possible from around it, the way was cleared for introducing other forms of gases. Whereupon I discovered this:
The stone will absorb any given quantity of hydrogen gas.
In this respect it behaves analogously to that curious place on the door-frame. Only, it absorbs gas, no liquid; and not any gas, either—none but hydrogen.
Now, obviously this gem cannot truly absorb so much material, in the sense of retaining it as well. The simple test of weighing it afterwards proves this; for its weight remains the same in any circumstances.
Moreover, unlike the liquids which I poured into the wood and saw afterwards in the basement, the gas does not escape back into the air. I kept it under the Dell long enough to be sure of that. No; that hydrogen is, manifestly, translated into the Blind Spot.
Learning nothing further about the gem at that time, I proceeded to investigate the trim of the door. I began by trying to find out the precise thickness of that liquid-absorbing layer.
To do this I scraped off the “skin” of the air-darkened wood. This layer was .02 of an inch thick. And—that was the total amount of the active material!
I put these scrapings through a long list of experiments. They told me nothing valuable. I learned only one detail worth mentioning; if a fragment of the scrapings be brought near to the Holcomb gem—say, to within two inches—the scrapings will burst into flame. It is merely a bright, pinkish flare, like that made by smokeless rifle-powder. No ashes remain. After that we took care not to bring the ring near the remaining material on the board.
All this occurred on the first day after Ariadne was stricken. Jerome phoned to say that he had engaged the services of a dozen private detectives, and expected to get wind of the Rhamda any hour. Both Dr. Hansen and Dr. Higgins called twice, without being able to detect any change for the better or otherwise in their patient.
That evening Charlotte and I concluded that we could not hold out any longer. We must give in to the Rhamda. I phoned for a messenger, and sent an advertisement to the newspaper which Avec had indicated.