“At this thought I started; and at that moment the man on the mattress gave a strange, snorting cry.  The ruffian, Boris, looked round, rose, went over to the mattress and stirred the other with his foot.  ’Louis!  Louis!’ he cried angrily, ’what the devil are you making that noise for?’

“The other man scrambled up with a cry of terror, pistol in hand.  ’Ah! it is you, Boris!  I was dreaming.  I thought they had come.’  He sat down again on the mattress and yawned.  ’Bah!  I am sleepy.  I must lie down again.  Watch a little longer, Boris.’

“‘Why should I watch?’ demanded Boris.  ’They will make enough noise opening that door.  I shall lie down a little, too.’

“He flung himself down beside his comrade, but in a minute or two started up, taking deep breaths.  ‘My God!’ he exclaimed.  ’I can’t breathe lying down.  I feel as if I should choke.  And you, too, Louis; you are snorting like a pig.  Get up, man.’

“He shook the prostrate man roughly, but eliciting only a few drowsy curses, resumed his restless pacing of the room.  But not for long.  Yawn after yawn told me that the gas was already in his blood; and the loud snoring of the other man indicated plainly the state of the air in the lower part of the room.  Presently Boris halted in his walk and sat down by the stove, muttering as before.  Soon he began to nod; then he nearly fell forward on the stove.  Finally he rose heavily, staggered across to the mattress and once more flung himself down.

“I breathed more freely, notwithstanding that the gas, having partially diffused upwards to the level of the opening, now began to filter through to my side.  I waited a minute or two listening to the breathing of the two murderers as it grew moment by moment more stertorous and irregular, and then, having filled up the stove, went down to the first floor and sat awhile by the open window to breathe the relatively fresh air.

“All was now quiet in the street.  No doubt the guard had been strengthened, but I did not look out.  It was as well not to be seen at that hour in the morning.  As I sat by the window, I thought about the two men in that deadly room.  It was a thousand pities that they should be lost to science.  Yet there was no help for it.  Even if I had decided to acquire them I could not have done so, for, by the very worst of luck, I had used up my last barrel and had neglected to lay in a fresh stock.  Besides, of course, the police knew they were there.

“I rested for half an hour or so and then went upstairs to see how matters were progressing.  No light now came through the opening in the wall, for the paraffin lamp had either burned out or been extinguished by the accumulating gas.  I listened attentively.  The harsh, metallic ticking of a cheap American clock was plainly, even intrusively, audible; otherwise no sound came from that chamber of death.