I had heard something of Moissan, but I knew his artificial diamonds were very small. I shook my head.
"You seem to know something of this kind of thing. I will tell you a little about myself. Perhaps then you may think better of the purchase." He turned round with his back to the river, and put his hands in his pockets. He sighed. "I know you will not believe me."
"Diamonds," he began—and as he spoke his voice lost its faint flavour of the tramp and assumed something of the easy tone of an educated man—"are to be made by throwing carbon out of combination in a suitable flux and under a suitable pressure; the carbon crystallises out, not as black-lead or charcoal-powder, but as small diamonds. So much has been known to chemists for years, but no one yet had hit upon exactly the right flux in which to melt up the carbon, or exactly the right pressure for the best results. Consequently the diamonds made by
