They were, and of the same brand as those the boys had located on the stream bank. Scotty picked one up and tested it between his fingers. "Mighty curious. Water cures Portland cement. Turns it hard. These bags aren't hard, even though some powder is still in them."
Rick examined the bags, his brows creased with bewilderment. "They must have held something besides cement. But what? Fertilizer for the cornfield, maybe? And why two caches?"
"If it were fertilizer, the bags near the mine could have been for the field across the creek where the plane is," Scotty suggested. "These could have been for this field. But I don't think it was fertilizer. Isn't fertilizer soluble in water?"
Rick wasn't sure. "We can take the bag along," he said. "Maybe the microscope will tell us something, or maybe Dr. Miller will know."
He had a feeling that the bags meant something. They had been hidden, and only the erosion of rain had uncovered them, first at the creek embankment and now here. The Frostola man had almost certainly taken the others. Why? Unless they had something to do with the mystery? The bags were worthless, of themselves.
They finished the survey of the area. It was clear that whoever produced the ghost would have to enter by the road from town, because there was no other road on the side of the hill in which the mine was located. To be sure, the area could be reached by walking a considerable distance, but Rick couldn't see a man with equipment doing much walking through cornfields or woods filled with underbrush. He was certain the ghost had to be produced by equipment of some kind, probably electric powered—which meant batteries.
The problem was, where did the ghost producer operate? If dry ice was used to produce the mist, how did it get into the pool? He had no answers to these vital questions, nor did Scotty.
The dark-haired boy looked at him quizzically as they trudged back to the farmhouse. "Did it ever occur to you that it's impossible for anyone to produce the ghost? There is no place within sight of the pool where anyone could hide, except in a tree, and a man with equipment wouldn't go undetected by a gang at the picnic grounds."
"It did occur to me," Rick admitted. "But doesn't that put us back where we started? Either the ghost is a genuine spook, or it's man-made. We're not making many miles an hour in proving it's man-made, I admit. But if it isn't, where does that leave us?"
Rick remembered the chase through the woods, ending with a bath in the quarry. If they had been chasing a real ghost, and the ghost had led them into danger deliberately, that meant ... He wasn't sure what it meant except that it gave him goose pimples to think about it.