"Dry ice," Rick said.

CHAPTER IX

The Splitting Atoms

The storm had given way to a fine drizzle of rain by morning. Rick stared out the window at the drenched land and considered the angles he had been turning over in his mind.

The dry-ice theory wasn't conclusive, he knew, but it was a strong indication. It didn't explain the Blue Ghost himself, but it could explain the mist.

Dry ice is simply solid carbon dioxide, which is a gas at normal temperatures. It becomes a solid at low temperatures, and because it is harmless, inexpensive, and clean, it is widely used to keep things cold, as in the case of ice-cream route men who have no means of refrigeration.

When the temperature is raised, dry ice pa.s.ses directly from the solid to the gaseous state. When dropped into water it seems to boil, as the comparative warmth of the water turns it to gas, and it creates a fine white mist.

Rick was reasonably sure the Blue Ghost appeared in a carbon-dioxide cloud, and he was beginning to have an inkling of how this was accomplished--in principle, if not in specific terms. There were, after all, he reasoned, only a few ways of creating a visible image. He was going through the list of possibilities, eliminating them one by one.

If the Frostola man was connected with the ghostly appearances, it was only necessary to keep track of that tall individual. This was Rick's plan, necessarily postponed because of the storm.

"Wish we had a radio," he said. "I'd like to get a weather report."

Scotty grinned sympathetically. He knew that Rick was impatient when there was detecting to be done.

"We really should have a battery radio," Dr. Miller said. "Power here is not very dependable in stormy weather. I think I'll get one, although that won't help now."

"What we need is a radio that doesn't depend on power," Jan Miller said.

"Then it would always be ready."

Rick stared at the girl, not really seeing her. A radio without power.

He remembered a long talk with Dr. John Gordon of the Spindrift staff about the principles of radio. Dr. Gordon had sketched a circuit that needed no power, and then had told Rick of how American ingenuity had produced what soldiers called a "foxhole radio."

"I saw an old transformer in the woodshed," he said suddenly. "May I have it, Dr. Miller?" At the scientist's nod, he addressed Jan. "I'll bet you can find me a cardboard tube. Then, if I can have an old razor blade and permission to take the receiver off the telephone for a while, I can make a radio!"

The scientist, the girls, and Scotty looked at him with disbelief. "He's gone off his rocker at last," Scotty muttered. "How can anyone make a radio out of junk?"

"I'll need a pencil stub, a few screws, and a piece of board," Rick added. "A safety pin would help, too."

"Rick Brant, you're being silly," Barby said firmly. "This is no time for practical jokes!"

Dr. Miller held up his hand. "Peace, Barbara. Rick isn't joking. I believe I see what he has in mind. Rick, I've never heard of this, but I a.s.sume the oxide on the razor blade is to act as a rectifier?"

"That's right, sir. John Gordon told me about it."

The scientist rose. "Then it will work. Come on, gang. Let's build a radio out of junk."

With many hands to help, the work went quickly. Under Dr. Miller's direction, Scotty took the transformer out of its case and the girls went to work unwinding the quant.i.ties of wire from its coils.

Rick found a razor blade and anch.o.r.ed it to a rectangular piece of plywood he found in the woodshed. It was a double-edged blade, and one small screw from Dr. Miller's junk box served to hold it. He wrapped a short piece of insulated wire, one of the transformer's connecting leads, under the screw before he tightened it. He sharpened the lead pencil with his jackknife, uncoiled the safety pin, and pushed the sharp end into the exposed lead at the upper end of the pencil, which was a stub only two inches long.

The safety pin also was screwed to the board, the screw going through the s.p.a.ce in the pin's head. It was placed in such a position that the sharp end of the lead pencil rested on the razor blade. Another short piece of insulated wire was wrapped around the screw before it was tightened. Rick bared the copper end of the wire in order to make a good contact.

Jan found a cardboard roll that had once held paper towels. Rick cut off about six inches of it and proceeded to wind it with wire from the transformer. He wound evenly and tightly, until the roll was full of wire. Then he stabbed a small hole in each end of the roll and pulled the wires through to hold the coil in position. The roll--now a coil--was tacked to the board with thumbtacks.

Dr. Miller, meanwhile, had taken the receiver from the telephone. Scotty strung yards of wire around the room and handed the loose end to Rick.

That was the antenna. Then Scotty sc.r.a.ped a bright place on a water pipe with his knife and twisted a length of wire tightly around it. That was the ground.

Rick and Dr. Miller made connections. Rick gestured to the haywire apparatus with some pride. "Behold. Where there was junk is now a radio."

Jan Miller said, "I don't believe it!"

Rick had to laugh. "I'm not sure I do, either. But let's try." He sat down at the table and held the receiver to his ear. With the other hand he began the laborious job of locating a sensitive spot on the razor blade.

Dr. Gordon had told him that only an occasional spot on a blade will work. Some blades have no such spots. Others have many.

Rick was beginning to think that he had one of the no-spot kind, or that the whole idea was wrong, when he heard what he thought was a voice. He hastily concentrated on the spot, and in a few seconds music flooded into the earphone. He had caught a disk jockey in the process of introducing a record. For a long moment he listened, then held out the earphone with a broad grin. "Anyone care to listen?"

Everyone did. They took turns, with each application of the phone to an ear accompanied by expressions of astonishment.

Barby looked at her brother with new respect. "It's just fantastic! How on earth does it work?"

Dr. Miller chuckled. "I'm sure you don't want a full course in electronics, Barby. Actually, it's simple enough. The signal from the radio station is an alternating current that sets up a corresponding current in the antenna wire. This current goes through the coil and is rectified--that is, it's turned into pulsating direct current--by the razor blade. The receiver then converts it into audible sound."

Barby sighed. "I'll just have to take your word for it. But it's a miracle!"

"It may seem like one, but it's really the same kind of circuit you find in a crystal set," Rick explained. "The razor blade acts like the crystal. That's all."

The young people took turns listening to the station, located in a town nearby. Within the hour there was a weather report promising clearing skies before the end of the day. Later, in a roundup of local announcements, they heard that the annual Sons of the Old Dominion feast, postponed because of the storm, would be held the next night.

"That means we start keeping an eye on the ice-cream man tomorrow afternoon," Rick said.

Scotty nodded. "First, we'd better make a survey of the terrain. He has to approach by the road, but there are a million places he could go once he got into the mine area."

Rick looked out the window. "The rain has stopped. Maybe we can reconnoiter this afternoon."

Fortunately, the Miller farm was well equipped with boots and overshoes.

The boys borrowed footgear suitable for any mud left by the rain and started out after lunch.

The picnic area was washed clean of footprints and it was clear no one had visited the area since the rain. They made their way to the top of the hill above the mine and surveyed the cornfield that had been planted on the hilltop field. The corn was not high. The plants came only to their knees. Either it was a second planting or a poor crop. Rick guessed that the second reason was probably the correct one, because the field hadn't been cultivated recently.

"This isn't Miller land," he mused. "Wonder who is farming it?"

"It must be Hilleboe's property," Scotty returned. "Maybe he rents it to some local farmer."

They walked to the downstream edge of the cornfield to where the woods resumed. Rick had a feeling that they were wasting time. The ghost couldn't be produced from such a distance by any means he had ever heard of. The apparition had to be created right in the vicinity of the mine.

He spoke his thoughts aloud, and added, "Let's go back."