Winter, cold driving wind, snow and wild ducks! The Mongol explained it to me thus: "This swamp always remains warm and never freezes.

The wild ducks live here the year round and the kuropatka too, finding fresh food in the soft warm earth." As I was speaking with the Mongol I noticed over the swamp a tongue of reddish-yellow flame.

It flashed and disappeared at once but later, on the farther edge, two further tongues ran upward.

I realized that here was the real will-o'-the-wisp surrounded by so many thousands of legends and explained so simply by chemistry as merely a flash of methane or swamp gas generated by the putrefying of vegetable matter in the warm damp earth.
"Here dwell the demons of Adair, who are in perpetual war with those of Muren," explained the Mongol.
"Indeed," I thought, "if in prosaic Europe in our days the inhabitants of our villages believe these flames to be some wild sorcery, then surely in the land of mystery they must be at least the evidences of war between the demons of two neighboring rivers!" After passing this swamp we made out far ahead of us a large monastery.
Though this was some half mile off the road, the Gorokoffs said they would ride over to it to make some purchases in the Chinese shops there.
They quickly rode away, promising to overtake us shortly, but we did not see them again for a while.

They slipped away without leaving any trail but we met them later in very unexpected circumstances of fatal portent for them.