Slowly the figure advanced, It waved the long white arms, as if in warning. At times it would be only dimly visible in the blackness, then, suddenly it would stand out in bold relief as a great flash of fire split the clouds.

The thunder, meanwhile, had been growing louder and sharper, indicating the nearer approach of the storm. Each lightning flash was followed in a second or two, by a terrific clap. Still there was no wind nor rain, and the campfire burned steadily.

All at once there was a crash as if the very mountain had split asunder, and the adventurers saw a great ball of purple-bluish fire shoot down, as if from some cloud, and strike against the side of the crag, not a hundred feet from where stood the ghostly figure in white.

“That was a bad one,” cried Mr. Damon, shouting so as to be heard above the echoes of the thunderclap.

Almost as he spoke there came another explosion, even louder than the one preceding. A great ball of fire, pear shaped, leaped for the same spot in the mountain.

“There's a mass of iron ore there!” yelled Mr. Parker. “The lightning is attracted to it!”

His voice was swallowed up in the terrific crash that followed, and, as there came another flash of the celestial fire, the figure in white could be seen hurrying back up the mountain trail. Evidently the electrical storm, with lightning bolts discharging so close, was too much for the “ghost.”

In another instant it looked as if the whole place about where the diamond seekers stood, was a mass of fire. Great forked tongues of lightning leaped from the clouds, and seemed to lick the ground. There was a rattle and bang of thunder, like the firing of a battery of guns. Tom and the others felt themselves tingling all over, as if they had hold of an electrical battery, and there was a strong smell of sulphur in the air.

“We are in the midst of the storm!” cried Mr. Parker. “We are standing on a mass of iron ore! Any minute may be our last!”

But fate had not intended the adventurers for death by lightning. Almost as suddenly as it had begun, the discharge of the tongues of fire ceased in the immediate vicinity of our friends. They stood still—awed—not knowing what to do.