Note:  Do not rely on this information. It is very old.


Agnano, a lake occupying the hollow of an extinct volcanic crater near Naples. Its circumference is about two miles, and on its shore is the famous Grotto del Cane, a small artificial recess, in which the carbonic acid gas emitted from the soil below rises to the height of eighteen inches, and thus kills a dog, whilst a man escapes with impunity.