The countess was grateful for the abbé's remark, for it gave her a happy inspiration.
"Do you mean to tell me," she said, addressing Ivan, "that a diamond is combustible?"
"Undoubtedly, for the diamond is, in fact, nothing but coal in the form of a crystal. With the necessary degrees of heat you can extract from the patrician diamond ninety florins carat weight, the same amount of invisible gas or oxide of coal as from the plebeian lump of coal."
"That is proved by the focus of the magnifier," remarked the abbé.
"I don't believe it," said the countess, throwing back her head.
"I am sorry," returned Ivan, "that I cannot give you a proof that the diamond is combustible. We do not use such costly things for mere experiment, but have splints for the purpose, which are cheap in comparison. I have, however, none of these by me."
"I should like to be convinced, for I do not believe it," repeated the countess. "Will you make the experiment with this?" As she spoke she unfastened a brooch from her dress, and handed it to her host. The centre stone was a fine two-carat brilliant. Theudelinde expected that Ivan would return it to her, saying, "Oh, it would be a pity to use this beautiful stone;" and then she would reply, "Then pray keep it as a slight remembrance;" and in this manner this perverse individual would have been paid and forgotten. But, to her amazement, the countess found she had deceived herself.
With the indifference of a philosopher and the courtesy of a gentleman Ivan took the brooch from its owner.
"I conclude you do not wish to have the ornament melted," he said, quietly. "I will take the diamond out of its setting, and if it should not burn you can have it reset."
Without another word he extracted the stone with a little pincers, and placed it at the bottom of a flat clay saucepan; then he opened the window, which lay in the full blaze of the sun. He placed the saucepan upon a stand in the middle of the room and just in front of the countess; then he took the magnifying-glass and went outside, for in the room the sun's rays had not power to concentrate themselves upon the mirror.