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.

The electricity and telephone service had been restored by the time the
boys got back. Dr. Miller told them that he had phoned the tenant farmer
and arranged for the man to do a little inquiring in the town.

Rick displayed the bag. "Got a specimen," he told the group. He
explained their interest in the bag and asked Dr. Miller if he could
identify the contents.

The scientist examined the grayish powder from the bag. "It could be any
one of a hundred things," he said. "Let's see what we can find out about
it."

The farmhouse wasn't equipped for any kind of chemical analysis, but the
scientist did what was possible. He tried to dissolve the powder in
water, and failed. He tried vinegar, as the only acid available, and
failed. He tried ammonia, and failed.

Finally he said, "Well, it isn't cement, and it isn't fertilizer. It's
an inorganic substance. I suggest the microscope, Rick. It will at least
give us a clue to its structure, if not its identity."