liquid interior froze it expanded, and the outer crust resisted that expansion. An enormous pressure was created-just what was needed to crystallize the carbon from the iron and to form diamonds. Thus Moissan explained the presence of diamonds in the meteorite of Cañon Diablo.

The next step was the creation of an artificial, miniature meteorite, something in which intense heat and terrific pressure could be generated. Moissan built himself an electric furnace. It was very simple. A block of limestone and two electrodes connected with a dynamo-that was all of which it was composed. The limestone block was hollowed out to receive a crucible. In the crucible

Moissan packed a mixture of pure iron and carbon made by burning sugar. When the powerful current was turned on-so powerful that every working minute cost Moissan one dollar-the crucible and its contents were raised to a temperature of over seven thousand degrees Fahrenheit. The sun is not much hotter. The iron became like hot, liquid wax and dissolved the sugar carbon. After a few minutes the limestone of the furnace itself began to melt and the iron to float off in clouds of vapor-so fierce was the heat. His eyes shielded by colored glasses, Moissan seized a pair of tongs and lifted the blinding white crucible-his miniature meteorite and dropped it into ice-cold water.

Exactly what happened thousands of years ago when the Cañon Diablo meteorite collided with the earth was repeated on a small scale, except that there was no explosion. A skin of chilled iron was formed that resisted the effort of the still liquid interior to expand. In that tremendous pressure diamonds were formed-not Kohinoors, but microscopic crystals, the biggest of which was only one thirty-second of an inch in diameter, and therefore too small for any practical purpose. Each microscopic diamond cost him about five times as much as a natural diamond of equal size; but a great geological secret had been revealed, something that was well worth the price paid in intellectual effort and in money.

Moissan repeated the experiment

many times in after years. Never was he able to obtain a diamond that a jeweler would dignify by calling it even a chip. Nor have others been more successful.

If we judge Moissan's results merely by the size of his diamonds, his achievement must seem as ridiculous as that of a circus clown who succeeds, after frantic efforts, in evoking a barely audible squeak from a gigantic megaphone. Yet scientific men consider Moissan's discoveries epoch-making. A Gradgrind may ask, "What is the use of spending years of time and thousands in money to produce a diamond that can be seen only with a magnifying-glass?" The answer is that, thanks to Moissan, the diamond is no longer a perennial puzzle, one of the "riddles of the painful earth," as a great poet once expressed it. We know exactly how nature's diamonds were produced, and what forces are essential to make them artificially in a factory. Moissan worked with high temperatures, but with comparatively small pressures. If we are to make a

salable diamond, we must have far more powerful mechanism at our disposal than Moissan was able to command. Some day that mechanism will be provided, and the diamond factory of Niagara Falls will compete with the Premier Mine of South Africa.

That Moissan was right has been proved by others who sought to obtain great pressures and great heat in ways different from that which he employed. A few years ago Sir Andrew Noble, one of the greatest living authorities on explosives, detonated some cordite in closed cylinders of steel.

A press

ure of over fifty tons to the square inch and a temperature of over ninety-seven hundred degrees Fahrenheit were attained. Work

ing with specially prepared explosives containing an excess of carbon, Sir Andrew collected the residue left in the cylinders and gave it to Sir William Crookes for analysis. Sir William found that true minute diamonds had been formed.

It must not be forgotten that nature made her diamonds with a great heat, applied, not for a few minutes, but for centuries, and perhaps for thousands of years; with a quantity of carbon measured, not by ounces, but perhaps by tons; and with pressures far exceeding those obtained by Sir Andrew Noble, and exercised, not for the fleeting fraction of a second during an explosion, but for protracted intervals of time. Perhaps the chemist will never succeed in making a Cullinan-a stone that weighed a pound and three-quarters in the rough-but some day he will elaborate Noble's simple apparatus and produce stones that the jeweler will not disdain to set in a necklace.

If Moissan himself never made a fortune out of his discovery, a French swindler named Lemoine did. No less a person than Sir Julius Wernher, a prominent officer of the South African diamond syndicate, fell a ready prey to Lemoine-proof, perhaps. that the owners of diamond mines do not view with equanimity the discovery of a commercial process for manufacturing Kohinoors. After having examined stones that Lemoine claimed had been produced by his secret process, Sir Julius Wernher advanced large sums for the building of a factory. No diamonds were forthcoming. Lemoine was arrested and brought to trial. Experts identified the gems that he had displayed to Sir Julius as diamonds bought from known sources. Sir Julius had pinned his faith on the statements contained in a certain sealed envelope that had been locked by Lemoine in a safe. On the day appointed for the opening of the envelope in court, the day which was to decide whether or not a historic swindle had been perpetrated, Lemoine wisely disappeared. In the court records the "secret" process, rather too literally translated from the French by some court clerk, is thus revealed:

I, the undersigned, Henri Lemoine, declare that to make artificial diamonds it is sufficient to employ the following process: (1) Take a furnace; (2) take some powdered sugar carbon; (3) place the carbon in a crucible; (4) place the crucible in the furnace and raise the temperature to from 1,700 degrees C. to 1,800 degrees C. in order to obtain crystallization; (5) when this

large stones, and however ridiculous was his secret process, Lemoine had at least wit enough to steal the general idea.

More successful than Moissan have been those chemists who have tried to make rubies and sapphires. Long ago the remarkable discovery was made that rubies and sapphires are but modifications of the common clay out of which earthen pots are fashioned-a clay called alumina. Change the formless alumina into crystals and you have what the chemist

mysterious ruddy gleam to a minute quantity of chromium oxide. But what impurities gave the sapphire its deep rich blue or its occasional yellow and green hues has only recently been discovered.

If we are to make rubies in the factory, evidently we have only to melt the common clay alumina, so as to produce corundum, and then color it with a pinch of chromium oxide. As long ago as 1848 Ebelmen, the director of the famous porcelain works of Sèvres,

made the experiment. His rubies were small and imperfect-worthless, in a word. Hundreds of attempts to make them of salable size and quantity proved futile. Frémy, a French chemist, succeeded better, after thirteen years of painstaking labor. But not until Professor A. Verneuil, of the Conservatoire des Arts et Métiers, completed Frémy's work were we able to buy factory-made rubies-stones identical in color, optical properties, brilliancy, and chemical composition with the finest Burmese stones. Because the word "artificial" suggests an imposition, chemists and even jewelers prefer to call Verneuil's gems "synthetic rubies." Although man made, they are genuine. Factories in which Verneuil's principles are commercially applied on a large scale have sprung up in France and Germany, with the result that the output of synthetic rubies amounts to about seven million carats annually, equivalent to about a ton and a half. Fine natural rubies are worth two hundred and fifty dollars a carat; exceptionally fine two-carat stones, as much as two thousand five hundred dollars. Since the manufacturing cost of crude synthetic rubies is only about two and a half cents a carat, and of the cut and polished crystal about forty cents, it is easy to picture the alarm of a Parisian association of jewelers that petitioned the French. Chamber of Deputies to pass a law which would restrict the application of the word "ruby" to gems cut only from natural raw

Stones.

Verneuil's process is astonishingly simple. Just as Moissan's white-hot crucible, filled with molten iron in which carbon is dissolved, has its natural analogue in a meteorite or shooting star, so Verneuil produces his rubies by a method akin to that by which nature fashions an icicle. By the wind or some other chilling influence a flowing drop of water is transformed into an ice crystal. The succeeding drop spreads over that crystal in a thin film and freezes to it. And so layer on layer of crystalline ice is formed in the shape of an icicle. To the eye that icicle seems like a stalactite; but for all that, its internal structure is that of a single, regular, optically perfect crystal.

While Verneuil imitates nature's method of forming icicles, he modifies it in one important respect. An icicle grows downward, drop-wise, from a large base, and tapers to a point. A Verneuil synthetic ruby icle grows upward, drop-wise, not from a

broad base but from a point. It was found that if a ruby were built up on a large base, like an icicle, it would always be so cracked as to be unsuitable for gem-cutting; but that if the base were exceedingly small a perfect stone was obtained. A synthetic ruby, immediately after it is completed, therefore, resembles a small pear standing on its stem. The pear may weigh as much as eighty carats. No synthetic cut ruby of that size has yet been sold; for fully seventy-five per cent of the pear, whether it be big or little, is lost in the cutting.

The apparatus in which Verneuil makes his inverted pear-shaped ruby icicles is comprised essentially of a downwardly hanging blowpipe to which two gases are fed-oxygen and illuminating gas. Ignited, the two burn with an intensely hot flame. Into this flame a fine powder, a mixture of chemically pure alumina (clay) and chemically pure chromium oxide, is dropped, a few grains at a time, to collect on the vertex of a clay cone or "foot." At regular intervals a little cloud of powder falls into the flame, melts, and freezes to the ruby that has crystallized on the foot. By careful adjustment of the conical clay foot a ruby pear is built up, drop by drop, to almost any desirable size. Although the pressure of the gases must be nicely regulated as the ruby is constructed, and although the adjustment of the clay cone or foot on which the molten powder falls requires much skill, a single workman can attend eight or nine furnaces. At the rate of ten carats an hour each of his flames produces rubies as beautiful and as hard as those which, nature fashioned after the lapse of centuries.

Long experience in the manufacture of synthetic rubies has revealed much that was not clearly understood about the natural stone. Why, for instance, is the inferior Siamese ruby orange-red in color, and the highly prized Burmese ruby of a deep bloody hue? Verneuil finds that if there is the slightest trace of iron in the chromium oxide with which he mixes his alumina he obtains the Siamese ruby, and only when the chromium oxide is absolutely pure is his ruby pear a Burmese stone. Who can doubt that a particle of iron has spoiled the natural Siamese ruby for the connoisseur ? If the amount of chromium oxide is very slight, a light-pink stone is obtained, which has been erroneously likened to the pink topaz-erroneously because the topaz, whatever its color, has not yet been synthetically produced. If