if he demanded it. Our elevation to-day is about 7,500 feet above sea
level.


Saturday, September 3.--This morning General Washburn and I left camp
immediately after breakfast and returned four miles on our track of
September 1st to Crater Hill and the mud springs, for the purpose of
making farther examinations. We found the sulphur boiling spring to be
full to overflowing, the water running down the inclined surface of the
crust in two different directions. It was also boiling with greater
force than it was when we first saw it, the water being occasionally
thrown up to the height of ten feet. About 80 or 100 yards from this
spring we found what we had not before discovered, a boiling spring of
tartaric acid in solution, with deposits around the edge of the spring,
of which we gathered a considerable quantity. In the basin where we had
found so many mud springs we to-day found a hot boiling spring
containing a substance of deep yellow color, the precise nature of which
we could not readily ascertain. We accordingly brought away some of it
in a bottle (as is our usual custom in such cases of uncertainty), and
we will have an analysis of it made on our return home. In the same
basin we also found some specimens of black lava.

A half mile south of these springs we found an alum spring yielding but
little water and surrounded with beautiful alum crystals. From its
border we obtained a great many curiously shaped deposits of alum
slightly impregnated with iron. The border of this spring below the
surface had been undermined in many places by the violent boiling of the
water, to the distance of several feet from the margin, so that it was
unsafe to stand near the edge of the spring. This, however, I did not
at first perceive; and, as I was unconcernedly passing by the spring, my