Part 3 (1/2)

The wildest imagination of Scheherezade never dreamed in _Arabian Nights_ of genii that had a t.i.the of the power of these real forces.

Her genii shut up in bottles had to wait centuries for some fisherman to let them out.

NATURAL AFFECTION OF METALS

”Sacra fames auri.” The hunger for gold, which in men is called accursed, in metals is justly called sacred.

In all the water of the sea there is gold--about 400 tons in a cubic mile--in very much of the soil, some in all Philadelphia clay, in the Pactolian sands of every river where Midas has bathed, and in many rocks of the earth. But it is so fine and so mixed with other substances that in many cases it cannot be seen. Look at the ore from a mine that is giving its owners millions of dollars. Not a speck of gold can be seen. How can it be secured? Set a trap for it. Put down something that has an affinity--voracious appet.i.te, unslakable thirst, metallic affection--for gold, and they will come together.

We have heard of potable gold--”_potabile aurum_.” There are metals to which all gold is drinkable. Mercury is one of them. Cut transverse channels, or nail little cleats across a wooden chute for carrying water. Put mercury in the grooves or before the cleats, and shovel auriferous gravel and sand into the rus.h.i.+ng water. The mercury will bibulously drink into itself all the fine invisible gold, while the unaffectionate sand goes on, bereaved of its wealth.

Put gold-bearing quartz under an upright log shod with iron. Lift and drop the log a few hundred times on the rock, until it is crushed so fine that it flows over the edge of the trough with constantly going water, and an amalgam of mercury spread over the inclined way down which the endusted water flows will drink up all the gold by force of natural affection therefor.

Neither can the gold be seen in the mercury. But it is there. Squeeze the mercury through chamois skin. An amalgam, mostly gold, refuses to go through. Or apply heat. The mercury flies away as vapor and the gold remains.

If thou seekest for wisdom as for silver, and searchest for her as for hid treasure, thou shalt find.

NATURAL AFFECTION BETWEEN METAL AND LIQUID

A little boy had a silver mug that he prized very highly, as it was the gift of his grandfather. The boy was not born with a silver spoon in his mouth, but, what was much better, he had a mug often filled with what he needed.

One day he dipped it into a gla.s.s jar of what seemed to him water, and letting go of it saw it go to the bottom. He went to find his father to fish it out for him. When he came back his heavy solid mug looked as if it were made of the skeleton leaves of the forest when the green chlorophyll has decayed away in the winter and left only the gauzy veins and veinlets through which the leaves were made. Soon even this fretwork was gone, and there was no sign of it to be seen. The liquid had eaten or drank the solid metal up, particle by particle. The liquid was nitric acid.

The poor little boy had often seen salt, and especially sugar, absorbed in water, but never his precious solid silver mug, and the bright tears rolled down his cheeks freely.

But his father thought of two things: First, that the blue tint told him that the jeweler had sold for silver to the grandfather a mug that was part copper; and secondly, that he would put some common salt into the nitric acid--which it liked so much better than silver that it dropped the silver, just as a boy might drop bread when he sought to fill his hands with cake.

So the father recovered the invisible silver and made it into a precious mug again.

NATURAL AFFECTION OP METAL AND GAS

A man was waked up one night in a strange house by a noise he could not understand. He wanted a light, and wanted it very much, but he had no matches that would take fire by the heat of friction. He knew of many other ways of starting a fire. If water gets to the cargo of lime in a vessel it sets the s.h.i.+p on fire. It is of no use to try to put it out by water, for it only makes more heat. He knew that dried alum and sugar suitably mixed would burst into flame if exposed to the air; that nitric acid and oil of turpentine would take fire if mixed; that flint struck by steel would start fire enough to explode a powder magazine; and that Elijah called down from heaven a kind of fire that burned twelve ”barrels” of water as easily as ordinary water puts out ordinary fire. But he had none of these ways of lighting his candle at hand--not even the last.

So he took a bit of pota.s.sium metal, bright as silver, out of a bottle of naphtha, put it in the candle wick, touched it with a bit of dripping ice, and so lighted his candle.

The pota.s.sium was so avaricious of oxygen that it decomposed the water to get it. Indeed, it was a case of mutual affection. The oxygen preferred the company of pota.s.sium to that of the hydrogen in the water, and went to it even at the risk of being burned.

I was so interested in seeing a bit of silver-like metal and water take fire as they touched that I forgot all about the occasion of the noise.

HINT HELP

Benjamin C. B. Tilghman, of Philadelphia, once went into the lighthouse at Cape May, and, observing that the window gla.s.s was translucent rather than transparent, asked the keeper why he put ground gla.s.s in the windows. ”We do not,” said the keeper. ”We put in the clear gla.s.s, and the wind blows the sand against it and roughens the outer surface like ground gla.s.s.” The answer was to him like the falling apple to Newton. He put on his thinking cap and went out. It was better than the cap of Fortunatus to him. He thought, ”If nature does this, why cannot I make a fiercer blast, let sand trickle into it, and so hurl a million little hammers at the gla.s.s, and grind it more swiftly than we do on stones with a stream of wet sand added?”

He tried jets of steam and of air with sand, and found that he could roughen a pane of gla.s.s almost instantly. By coating a part of the gla.s.s with hot beeswax, applied with a brush, through a stencil, or covering it with paper cut into any desired figures, he could engrave the most delicate and intricate patterns as readily as if plain. Gla.s.s is often made all white, except a very thin coating of brilliant colored gla.s.s on one side. This he could cut through, leaving letters of brilliant color and the general surface white, or _vice versa_.