It was still partially dark, a murky twilight replacing the former deeper blackness. But an indefinable change had taken place, somehow, in the atmosphere. Nat drew in his breath with difficulty. It seemed to scorch his lungs.
He glanced over the side of the craft and then drew back with an alarmed cry. The water all about them was bubbling and eddying furiously. A shower of spray from one of the miniature waterspouts struck Nat in the face. It was this that caused his exclamation and made him step back hastily, just as if, in fact, he had been struck a blow in the face.
The water was boiling hot!
Where it had spattered on the lad’s skin it had instantly raised blisters.
“Well, we certainly have landed in a surprising sort of fix this time,” muttered Nat to himself.
He bent over Joe. The lad had not yet regained his senses. But he was breathing heavily, and this stilled a dreaded fear, which, for a moment had almost caused Nat’s heart to stop beating.
“This air is suffocating,” gasped Nat presently. “It smells like it does when they are fumigating a room.”
He ran his tongue around his dry mouth in an effort to moisten it, for it felt parched and cracked. The reek of sulphur in the air, too, caused his throat to contract and his nose and eyes to tingle unmercifully.
But this stench also told Nat something. It furnished him with a partial explanation of the extraordinary occurrences that, as it seemed, were not yet over.
“This whole disturbance is volcanic,” reasoned the boy. “That is the cause of this awful sulphur smell. But that doesn’t account altogether for the sudden disappearance of those islands. I wonder——” But here he broke off his meditations.