Now water can be made to absorb more than a thousand times its bulk of ammonia; more than five hundred times its bulk of hydrochloric acid. Alcohol may absorb three hundred times its volume of sulphurous acid. Charcoal may absorb one hundred times its volume of ammonia, eighty-five times its volume of hydrochloric acid, sixty-five times its volume of sulphuretted hydrogen, fifty-five times its volume of sulphurous and thirty-five times its volume of carbonic acid. Iron, steel and melted sulphur absorb many gases. We have already seen that immense volumes of gases are thrown off in volcanic action. Now if a column of lava rises comparatively slowly in its “chimney,” the imprisoned gases rapidly escape, producing violent boiling, but not a positive explosion. But if it rises very rapidly, the sudden removal of the pressure causes so sudden an expansion of the compressed gases in its upper portion as to amount to a tremendous explosion, which reduces the lava to microscopic dust. This very principle was made practical use of in a mechanical contrivance invented to make paper pulp out of common cane, such as the farmer’s boy delights in for a fishing pole. The hard, woody fibre was placed in a powerful iron cylinder full of water. A strong lid being adjusted, the whole was heated far above the boiling point of water. Naturally, every cell would be forced full of moisture by the immense pressure. After some hours heating, the lid was suddenly removed, and by the sudden expansion of the water into steam the cane was blown to atoms. [Illustration: CRATER OF ORIZABA.] A beautiful product of the volcano of Kilauea is the substance known as “Pele’s Hair.” Small particles of glass shot violently into the air leave behind them long, glittering filaments, like gossamers. Birds often build their nests of these beautiful threads. Man, taking a hint from nature, has learned to manufacture the glass hair for himself by passing jets of steam through the molten slag of iron furnaces. It much resembles cotton wool, and is used for packing boilers and piston-heads, and similar purposes.