That respirator of yours is the only thing that seems to have a bearing on the 'fact' side of the affair.

That you did not lose your head as the others did--the effect in such case being in proportion to the amount of time each remained in the room--points to the probability that the stupefying medium was not hypnotic, whatever else it may have been.

But again, there is a fact which is contradictory.

Miss Trelawny, who was in the room more than any of you--for she was in and out all the time and did her share of permanent watching also--did not seem to be affected at all.

This would show that the influence, whatever it is, does not affect generally--unless, of course, it was that she was in some way inured to it.