e open air, and the water
settles down again to its proper level. So it is with the sources of
springs. As long as they are confined in narrow channels, the currents
of air in the water rush up in bubbles to the top, but as soon as they
are given a wider outlet, they lose their air on account of the rarity
peculiar to water, and so settle down and resume their proper level.

4. Every hot spring has healing properties because it has been boiled
with foreign substances, and thus acquires a new useful quality. For
example, sulphur springs cure pains in the sinews, by warming up and
burning out the corrupt humours of the body by their heat. Aluminous
springs, used in the treatment of the limbs when enfeebled by paralysis
or the stroke of any such malady, introduce warmth through the open
pores, counter-acting the chill by the opposite effect of their heat,
and thus equably restoring the limbs to their former condition.
Asphaltic springs, taken as purges, cure internal maladies.

5. There is also a kind of cold water containing natron, found for
instance at Penne in the Vestine country, at Cutiliae, and at other
similar places. It is taken as a purge and in passing through the bowels
reduces scrofulous tumours. Copious springs are found where there are
mines of gold, silver, iron, copper, lead, and the like, but they are
very harmful. For they contain, like hot springs, sulphur, alum,
asphalt,... and when it passes into the body in the form of drink, and
spreading through the veins reaches the sinews and joints, it expands
and hardens them. Hence the sinews, swelling with this expansion, are
contracted in length and so give men the cramp or the gout, for the
reason that their veins are saturated with very hard, dense, and cold
substances.

6. There is also a sort of water which, since it contains... that are
not perfectly clear, and it floats like a flower on the surface, in
colour like purple glass. This may be seen particularly in Athens, where
there are aqueducts from places and springs of that sort leading to the
city and the port of Piraeus, from which nobody drinks, for the reason
mentioned, but they use them for bathing and so forth, and drink from
wells, thus avoiding their unwholesomeness. At Troezen it cannot be
avoided, because no other kind of water at all is found, except what the
Cibdeli furnish, and so in that city all or most of the people have
diseases of the feet. At the city of Tarsus in Cilicia is a riv