Von
Holtz snarled insults at him. Von Holtz was beginning to work at the
manufacture of metallic ammonium.

* * * * *

It was an electrolytic process, of course. Ordinarily,
when--say--ammonium chloride is broken down by an electric current,
ammonium is deposited at the cathode and instantly becomes a gas which
dissolves in the water or bubbles up to the surface. With a mercury
cathode, it is dissolved and becomes a metallic amalgam, which also
breaks down into gas with much bubbling of the mercury. But Denham had
worked out a way of delaying the breaking-down, which left him with a
curiously white, spongy mass of metal which could be carefully melted
down and cast, but not under any circumstances violently struck or
strained.

Von Holtz was working at that. On the second day he delivered,
snarling, a small ingot of the white metal. He was imprisoned in the
lean-to-shed in which the electrolysis went on. But Tommy had more
than a suspicion that he was in communication with Jacaro.

"Of course," he said drily to Smithers, who had expressed his doubts.
"Jacaro had somebody sneak up and talk to him through the walls, or
maybe through a bored hole. While there's a hope of finding out what
he wants to know through Von Holtz, Jacaro won't try anything. Not
anything rough, anyhow. We mustn't be bumped off while what we are
doing is in our heads alone. We're safe enough--for a while."

Smithers grumbled.

"We need that ammonium," said Tommy, "and I don't know how to make it.
I bluffed that I could, and in time I might, but it would need time
and meanwhile Denham needs us. Dalzell is going to send a plane over
today, with word of when we can expect our own globe. We'll try to
have the big catapult ready when it comes. And the plane will drop
some extra supplies. I've ordered a sub-machine gun. Handy when we get
over there in the tree-fern forests. Right now, though, we need to be
watching...."

Because they were taking turns looking through the dimensoscope. For
signs of Denham and Evelyn. And Tommy was finding himself thinking
wholly unscientific thoughts about Evelyn, since a pretty girl in
difficulties is of all possible things the one most likely to make a
man romantic.

* * * * *

In the four days of their hardest working, he saw her three times. The
globe was wrecked and ruined. Its glass was broken out and its
interior ripped apart. It had been pil