e pebbles ought to melt
in the rivers."

"So they do; but they do not melt so easily as some things--sugar, for
instance. Don't you recollect that in the Rio Blanco the water is
almost like milk, and that it leaves a whitish coating on the branches,
and even on the leaves with which it comes in contact."

"That's true enough," replied the Indian, who had often wondered at the
petrifactions with which the banks of the White River abound.

"But the water that falls down here is quite clear," urged Lucien,
holding his torch close to a natural basin.

"But, nevertheless, it contains salts of lime in solution, the same, in
fact, as all water, particularly that from wells. And it is for this
reason that housekeepers will not use it; for it will not dissolve soap,
and hardens the vegetables that are cooked in it."

"Now do _you_ understand this?" asked l'Encuerado, addressing Lucien; "I
don't."

"Yes, I do, a little."

"Well, you are very fortunate! The other day stones were said to come
from the sun or moon, and fly about all covered with fire; now, they are
formed by water. Perhaps M. Sumichrast will tell us to-morrow that they
come from the wind."

The Indian then walked away, quite indignant; we followed him, smiling
at his anger, becoming more and more enchanted by the spectacle which
met our eyes. Unfortunately, our torches gave a very insufficient light,
and the thick smoke rapidly blackened the arches above us. A great
polished stone now impeded our passage, and compelled us to crawl. I
took the lead, and, passing through a kind of narrow corridor, made my
way into a small chamber. I raised a sudden exclamation; for five or six
skulls, symmetrically arranged, seemed to glare at me through their
empty orbits.

"Oh father!" cried Lucien, "are we in a cemetery?"

[Illustration: "Five or six skulls . . . seemed to glare at me through
their empty orbits."]

"Yes, my boy; I think this must be a Chichimec burial-place. This
nation, which preceded the Toltecs and Aztecs in Mexico, were in the
habit of depositing their dead in caverns."

Sumichrast examined a skull which he had picked up; its white and
perfect teeth showed that it must have belonged to a man who died young.
A few paces farther on five or six more skulls lay on the surface of the
ground; they were inclosed in by fine stalactites, and appeared as if
they were grinning at us through the bars of a dungeon.

For more than a thousand years, perhaps,