Chapter XXI - Flashing Gems

Eagerly the adventurers looked through the opening at the end of the passage into the larger cave. The men opened the small oven in which the balls of white chemicals and carbon mixed, had been baked, and a pile of things, that looked like irregularly- shaped marbles, were placed in the steel box.

This box, which was about the size of a trunk, was of massive metal. It was placed in a recess in the solid rock, and all about were layers of asbestos and other substances that were nonconductors of heat.

"That box becomes red hot," exclaimed Mr. Jenks, in a whisper. "When things are in readiness, that lever is pulled and the diamonds are made. I pulled it once, but I did not then know the process involved. I supposed that the lightning had nothing to do with making the diamonds."

"It has--a most important part," said Mr. Parker. The hidden adventurers could talk in perfect safety now, for the men in the large cave were too excited to pay much attention to them. The muttering of the thunder grew louder, and at times a particularly loud crash told that a bolt had struck somewhere in the vicinity of the cave.

"But, bless my watch-charm!" exclaimed Mr. Damon, "I didn't know lightning made diamonds."

"It does not--always," went on the scientist. "But great heat and pressure are necessary to create the gems. In nature this was probably obtained by prehistoric volcanic fires, and by the terrific pressure of immense rocks. It is possible to make diamonds in the laboratory of the chemist, but they are so minute as to be practically valueless.

"However, these men seem to have hit upon a new plan. They utilize the terrific heat of lightning, and the pressure which is instantaneously obtained when the bolt strikes. I am anxious to see how it is done. Look, I think they are getting ready to make the gems."

Indeed there seemed to be an air of expectancy among the diamond makers. The mixing machine had now been stopped, and, as it was more quiet in the cave, our friends, in their hiding- place, had to speak in mere whispers. All the men were now gathered about the great steel box.

This receptacle had been closed by a solid metal door, which was screwed and clamped tight. Then one of the men examined a number of heavily insulated electric wires that extended from the box off into the darkness where Tom and his companions could not discern them.

"That's Folwell--the man I befriended, and who got me into this game," whispered Mr. Jenks. "He was also one of the first to turn against me. I think he's one of the leaders."

Folwell came back, after having gone into a dark part of the cave. He went over to an electrical switch on one of the stone walls.

"It's almost time," Tom heard him say to his confederates. "The storm is coming up