On Architecture

19. On the same principle, copper, which is naturally more solid, will disperse and turn into verdigris if similarly treated. So, also, a pearl. Even rocks of lava, which neither iron nor fire alone can dissolve, split into pieces and dissolve when heated with fire and then sprinkled with vinegar. Hence, since we see these things taking place before our very eyes, we can infer that on the same principle even patients with the stone may, in the nature of things, be cured in like manner by means of acid waters, on account of the sharpness of the potion.

20. Then there are springs in which wine seems to be mingled, like the one in Paphlagonia, the water of which intoxicates those who drink of the spring alone without wine. The Aequians in Italy and the tribe of the Medulli in the Alps have a kind of water which causes swellings in the throats of those who drink it.