“Which it is not,” volunteered Doctor Hague, with the geniality of a snowball. “You have probably observed that the many slits in the wall permit of free ventilation; and asphyxia with free ventilation is an impossibility.”
“Quite so,” agreed Cleek placidly. “But if by any chance those slits could have been closed from the outside—I observe that at some period and for some purpose Mr. Drake has made use of a charcoal furnace”—indicating it by a wave of the hand—“and apparently with no other vent to carry off the fumes than that supplied by the slits. Now if they were closed and the charcoal left burning, the result would be an atmosphere charged with carbon monoxide gas, and a little more than one per cent. of that in the air of a room deprived of ventilation would, in a short time, prove fatal to any person breathing that air.”
The doctor twitched round an inquiring eye, and looked him over from head to foot.
“Yes,” he said, remembering that, after all, there were Board Schools, and even the humblest might sometimes learn, parrot-like, to repeat the “things that are in books.” “But we happen to know that the slits were not closed and that neither carbon oxide nor carbon monoxide was the cause of death.”
“You have taken samples of the blood, of course, to establish that fact beyond question, as one could so readily do?” ventured Cleek suavely. “The test for carbon monoxide is so simple and so very certain that error is impossible. It combines so tensely, if one may put it that way, with the blood, that the colouring of the red corpuscles is utterly overcome and destroyed.”
“My good sir, those are elementary facts of which I do not stand in need of a reminder.”
“Quite so, quite so. But in my profession, Doctor, one stands in constant need of ‘reminders.’ A speck, a spot, a pin-prick—each and all are significant, and——But is this not a slight abrasion on the temple here?” bending over and, with his glass, examining a minute reddish speck upon the dead man’s face. “Hum-m-m! I see, I see! Have you investigated this thing, Doctor? It is interesting.”
“I fail to see the point of interest, then,” replied Doctor Hague, bending over and examining the spot. “The skin is scarcely more than abraded—evidently by the finger nail scratching off the head of some infinitesimal pustule.”
“Possibly,” agreed Cleek, “but on the other hand, it may be something of a totally different character—for one thing, the possible point at which contact was established between the man’s blood and something of a poisonous character. An injection of cyanide of potassium, for instance, would cause death, and account in a measure for this suggestion of asphyxia conveyed by the expression of the features.”
“True, my good sir; but have the goodness to ask yourself who could get into the place to administer such hypodermic? And, if self-administered, what can have become of the syringe? If thrown from one of the bowman’s slits, it could only have fallen upon the roof of the wing, and I assure you that was searched most thoroughly long before your arrival. I don’t think you will go so far as to suggest that it was shot in, attached to some steel missile capable of making a wound; for no such missile is, as you see, embedded in the flesh nor was one lying anywhere about the floor. The cyanide of potassium theory is ingenious, but I’m afraid it won’t hold water.”