estored, because it has
become saturated and compounded with these qualities on account of the
rarity of its nature.

CHAPTER III

VARIOUS PROPERTIES OF DIFFERENT WATERS

1. There are, however, some hot springs that supply water of the best
taste, which is so delightful to drink that one does not think with
regret of the Fountain of the Muses or the Marcian aqueduct. These hot
springs are produced naturally, in the following manner. When fire is
kindled down beneath in alum or asphalt or sulphur, it makes the earth
immediately over it very hot, and emits a glowing heat to the parts
still farther above it, so that if there are any springs of sweet water
found in the upper strata, they begin to boil in their fissures when
they are met by this heat, and so they run out with their taste
unimpaired.

2. And there are some cold springs that have a bad smell and taste.
They rise deep down in the lower strata, cross places which are on fire,
and then are cooled by running a long distance through the earth, coming
out above ground with their taste, smell, and colour spoiled; as, for
instance, the river Albula on the road to Tivoli and the cold springs of
Ardea, which have the same smell and are called sulphur springs, and
others in similar places. Although they are cold, yet at first sight
they seem to be hot for the reason that when they happen upon a burning
spot deep down below, the liquid and the fire meet, and with a great
noise at the collision they take in strong currents of air, and thus,
swollen by a quantity of compressed wind, they come out at the springs
in a constant state of ebullition. When such springs are not open but
confined by rocks, the force of the air in them drives them up through
the narrow fissures to the summits of hills.

3. Consequently those who think that they have excavated sources of
springs at the height of such hills find themselves mistaken when they
open up their excavations. Suppose a bronze vase filled not to the very
lips, but containing two thirds of the quantity of water which forms its
capacity, and with a cover placed upon it. When it is subjected to a
very hot fire, the water must become thoroughly heated, and from the
rarity of its nature it greatly expands by taking in the heat, so that
it not only fills the vase but raises its cover by means of the currents
of air in it, and swells and runs over. But if you take the cover off,
the expanding forces are released into th