He rather suspected, in fact, that Pylotte had shadowed the swindler, whom Nick felt sure was Kilgore, with a view to learning just how the diamonds had been manufactured, and possibly with a design to turn the discovery to his own advantage.

This was, indeed, the most natural deduction for Nick to arrive at, after considering all the circ.u.mstances.

"So you are confident that these stones are works of art, rather than of nature, are you?" inquired Nick, who had been carefully examining the gems.

"I am absolutely sure of it, Mr. Carter," declared Pylotte.

"Have you any idea how such counterfeits can be made?"

"Oh, yes."

"By what process and means, Mr. Pylotte?"

Pylotte hastened to explain.

"A natural diamond, Mr. Carter, is pure carbon, crystallized under enormous heat and pressure in the bowels of the earth."

"I am aware of that."

"Charcoal and graphite are also pure carbon, but not in a crystallized condition," continued Pylotte. "If that condition could be imparted to the substances mentioned, we should have the artificial diamond."

"How may that be done?" inquired Nick.

"By subjecting the substance to the same condition under which the natural diamond was crystallized."

"Heat and pressure?"

"Precisely," bowed Pylotte. "Attempts to thus manufacture diamonds have frequently been made. A Mr. Acheson, of Pittsburg, while so engaged, and in obtaining graphite from coal by the heat of an electric furnace, discovered that combination of silicon and carbon now known as carborundum, which has commercial value as an abrasive."

"I know about that," bowed Nick.

"Now, then," continued Pylotte, with an unconscious display of enthusiasm; "while diamonds certainly have been made by artificial means, the great difficulty has been that of producing them at a low cost. Moissan, in my country, produced diamonds by heating charcoal and iron to a high degree, and letting the mixture cool under enormous pressure. He succeeded in obtaining very small crystals, or diamonds, but the cost of production made his method impracticable from a commercial standpoint."

"Ah! I see."

"In 1872 a chemist named Rose converted graphite into diamonds by a similar process, but with the same result."

"The cost of production being too great?" observed Nick.

"Precisely."

"Do you think that difficulty has now been overcome?"

"I am compelled to think so, Mr. Carter," cried Pylotte, pointing to the two diamonds on the table.

"You purchased them at a price compelling that belief?"

"Exactly."

"Then you think the man of whom you got them has discovered a way to make such perfect artificial diamonds at a low price?"

"I certainly do, Mr. Carter."

"Have you any idea of the machinery and ingredients he might require?"

asked Nick, with a view to getting points by which to locate the diamond plant.

Pylotte could easily inform him, and he promptly did so, following the instructions given him by Dave Kilgore.

"He would require an electric furnace and a hydraulic press," said he.

"Also the tools for cutting the crude crystals. The ingredients used would depend upon the process he has discovered, probably coal or charcoal, and possibly some quant.i.ties of iron salts and sulphur."

"In brief, then, Mr. Pylotte," said Nick, pointing to the diamonds on the table, "if those stones were made as cheaply as you think, the diamond market offers the manufacturers of them a field for a most gigantic swindle, does it not?"

"Indeed it does!" exclaimed Pylotte, throwing up both hands. "Enormous!

Enormous! Millions could be made by so unparalleled a fraud!"

"It opens the way, in fact, to the most colossal swindle on record?"

"Undoubtedly."

Nick glanced significantly at Chick, then abruptly rose to his feet.

That he had struck the big game which from the first he had suspected, he now had not a doubt.

"I require no more of you at present, Mr. Pylotte," said he, with courteous firmness. "I shall do all in my power to remedy your loss by this swindle, and to secure the perpetrators of it."

"Thank you, Detective Carter," bowed Pylotte, with a crafty display of appreciation and humility.

"Meantime," added Nick, "you will please take no action in the case, but leave it entirely to me."

"I will do so, sir."

"If you will leave me your city address, or call here again in a few days, I shall have something to report to you."

"I will call the day after to-morrow, Detective Carter," said Pylotte, promptly, too cunning to give Nick a fict.i.tious address.

"Very well," said Nick. "Call in the evening. And now, Mr. Pylotte, we will bid you good-morning, and get to work at once upon the case."

Pylotte bowed very agreeably, taking his artificial diamonds from the table and replacing them in his pocket; and Nick then conducted him to the door, again a.s.suring him that no efforts in his behalf should be spared.

Pylotte once more expressed his thanks, bowing and smiling as he descended the steps, and Nick closed the door and returned to the library.

"Well, Chick, the bag is open and the cat out," he cried, as he entered.

"Right you are, Nick."

"And a monstrous cat it is!"

"Never a larger one," declared Chick, with a laugh. "By Jove! Nick, if Kilgore has really found a way to produce such perfect counterfeit diamonds, his gang could work the greatest swindle ever known, unless headed off."