In Derby's account of himself, Nina could easily read the confidence that had led her father to send him to Italy. But their talk had gone little further than the barest outline of his mission when the prince and princess returned. At the sight of Nina sitting alone with a man, the princess came forward quickly with the question, "My child, what does this mean?" as plainly asked in her eyes as it could have been by spoken words. But at Nina's "John Derby, Aunt Eleanor!" the princess put out her hand with all the grace in the world, and as she returned the straight, frank look of his blue eyes, her whole expression became youthful, as if reflecting some pleasant memory of her girlhood.
"I knew your uncle very, very well!" She smiled entrancingly. It was a smile that irresistibly attracted to her all who ever saw it. "You are like him." Then she added softly, dreamingly, as though half speaking to herself, "You remind me of so many things—at home!"
The next minute she had turned to present Derby to her husband, and the conversation became general. But, finally, in a pause, Nina said, "Jack, tell Uncle Sandro what father sent you over to do. Or is it a secret?"
Derby looked toward Sansevero as though measuring the man. "It is no great secret—but I would rather it was not spoken of yet."
"My ears are deaf, and my tongue is dumb." Sansevero put his hand over his ear, his mouth, and finally his heart.
"I have come over to buy, or to lease—at all events, to work—sulphur mines."
As though an electric current had been turned on, Sansevero sat up straight, and his levity vanished. "To work sulphur mines! Will you tell me more? I have a particular reason for wanting to know."
Derby answered willingly. "I can give you a general idea. I was forced into inventing a new method of mining on account of the quicksands, which are found all through our mines at home. Taking a suggestion from the oil wells, I bored just such a well down into the sulphur beds. Ordinarily the sulphur is brought up in powder or rock form, and refined in vats on the surface, so that not only do the miners have to go down into the sulphurous heat, but the caldrons in which the sulphur is refined give out gases that are unendurable to human throats and lungs. In our mines, the sulphur is now refined sixty or a hundred feet below the surface of the ground, and pours out in an already purified state, at the top of the well."
Sansevero looked incredulous. "But sulphur is almost impossible to liquefy. Unlike metals, it congeals again when it has been heated beyond the proper temperature. Also it corrodes any metal it touches, so that a pipe would be eaten away immediately."
"To get over those difficulties is exactly what I am trying to do by my new process," Derby answered. "The sulphur is melted by hot water sent down the pipes, followed by sand, and then sawdust—the sand to carry the heat to the cooler edges, and the wet sawdust to check the heat at the center."