Vesuvius during those lava-flows that succeed an eruption, and continue for weeks or months even. What happens to-day, if studied with a little good sense and reflection, can enlighten us on what must have happened eighteen centuries ago. For instance, we have seen how slow lava-currents, remote from the vent of escape and cooled by contact with the ground and air, flowing around country-houses, level and consume them, with a sudden flaming up of roofs and floors. How could the stuccoes and the marble statues of Herculaneum remain unharmed, in their original color, free from crack or splinter, if they had been enveloped in lava? We have seen metals by mere contact melt and vanish in that viscous paste, which glows like fused iron or glass gushing from a furnace. How, then, do we find in Herculaneum articles of silver, bronze statues, leaden vases, with their shapes, their relief, their ornaments and polish uninjured? The bronzes of Herculaneum are even better preserved than those of Pompeii, being distinguished by their freshness of surface, their lustre, and dark and even tone, while the Pompeian bronzes have been attacked by sulphurous fumes, and eaten on the surface, and have taken on an agreeable ultra-marine blue tint, like that of sulphate of copper.
Other facts of the same kind are quite as puzzling. The guides amuse strangers with an experiment; breaking off a bit of lava with an iron-pointed stick, they let it cool on the ground, and stamp a penny on it, to get an impression of the coin. If the trial is made too quickly, the copper melts, and the coin, instead of leaving its image, disappears and mingles with the rest of the lava. How, then, do we find at Herculaneum so many ancient silver or copper coins, not merely undestroyed, but not even changed, by those waves of lava which attain a concentrated heat beyond all measurement? We know, too, that the ancients used colors with a mineral base in decorating their buildings; they will stand dampness from the earth, but the touch of fire changes their nature; the partial fires that have left traces in Pompeii have in some places altered the blue to gray, and the red to yellow, and Neapolitan artists in our time well understand the very simple method of producing what is called burnt-yellow, by exposing minium to the action of fire. How, then, do the houses uncovered at Herculaneum present such exquisite colors? How is it that the ultra-marine blue and the vermilion-red, covering whole walls, keep a freshness and smoothness that contact with a burning substance must necessarily have destroyed? Then, too, on Vesuvius I have seen trees just touched by the lava-flow take fire like matches, throw out a blazing jet, and fall at once, as if struck with lightning. Why have the beams and floors and sills of Herculaneum, instead of crumbling into ashes, slowly decayed in their places in the bosom of the earth, leaving no holes nor fractures? Why are they found blackened like oak-timbers that have been sunk in the mud for ages, like the piers of bridges and the piles of old docks at Carthage, and the wood brought down by the Jordan
