“I walked slowly down the stairs tracing the connection between the ideas of ‘stove’ and ‘sleep.’  The nauseous air that had filtered through from that room spoke eloquently of sealed windows and stopped crevices.  It was a frosty night and the murderers were chilly.  A back-draught in the stovepipe would fill the room with poisonous gases and probably suffocate these wretches slowly and quietly.  But how was it to be brought about?  For a moment I thought of climbing to the roof and stopping the chimney from above.  But the plan was a bad one.  The police might see me and make some regrettable mistake with a revolver.  Besides it would probably fail.  The stoppage of the draught would extinguish the fire and the pungent coke-fumes would warn the villains of their danger.  Still closely pursuing the train of thought, I stepped into my bedroom and lit the gas; I turned to glance round the room; and, behold! the problem was solved.

“In the fireplace stood a little brass stove of Russian make; a tiny affair, too small to burn anything but charcoal; but, as charcoal was easily obtainable in East London, I had bought it and fixed it myself.  It was perfectly safe in a well-ventilated room, though otherwise very dangerous; for the fumes of charcoal, consisting of nearly pure carbon dioxide, being practically inodorous, give no warning.

“My course was now quite clear.  The stove was fitted with asbestos-covered handles; a box of charcoal stood by the hearth, and in the corner was an extra length of stovepipe for which I had had no use.  But I had a use for it now.

“I lit the charcoal in the stove, and, while it was burning up, carried the stovepipe and the box of fuel upstairs.  Then I returned for the stove, inside which the charcoal was now beginning to glow brightly.  I fixed on the extra length of pipe and, with my hand, felt the stream of hot air—­or rather hot carbon dioxide gas—­pouring out of its mouth.  I tried the pipe against the opening and found that it would rest comfortably on the lower edge; and then, very slowly and cautiously, I drew back the sliding panel about six inches.  The ruffians were still wrangling on the same subject, for I heard one exclaim: 

“’Don’t be a fool, Piragoff.  You’ll only attract attention if you go nosing about downstairs.’

“‘I don’t care,’ was the answer; ’I feel uneasy.  I must go down and see that all is quiet before I go to sleep.’  Here the sound of the opening and shutting of the door put an end to the discussion, save for a torrent of curses and maledictions from the two remaining men.  But in a few moments the door opened noisily and Piragoff shouted: 

“‘Come out!  Come out!  The house is empty!  We are betrayed.’

“A howl of dismay was the answer.  The two wretches burst into a grotesque mixture of weeping and cursing, and I heard them literally dancing about the room in the ecstasy of their terror.

“‘Come out!’ repeated Piragoff.  ’We will kill them all!  We will shoot those pigs, every one of them!  Some of us shall get away.  Come!’