u what a high explosive really
is, and then if we have time we will talk of something else. The
difficulty about high explosives is not in making them, but in using
them after they are made; you create a gigantic power which you do not
know how to handle.

"The rather modern discovery of how to make liquid air has simplified
matters a good deal. When you can make liquid hydrogen in quantities you
will have a still better agent for many purposes. Now, let us take a
little of this liquid air. You see it pours like water. As I happen to
know, our absent host has nearly two gallons of it, or had this
afternoon; some of it has evaporated, but, as you see, there is still
more than a gallon left, and we will not steal much, as all we want for
our experiment to illustrate to you the greatest explosive which can be
manufactured is about as much liquid air as you can hold in a thimble."

"Do you propose to try your explosive here, Mr."--I hesitated. "By the
way, what is your name?"

"Oh, call me any old name; it does not matter!"

"Mr. Spook, shall we say?"

"Ahem! a little personal, perhaps, but it will do as well as another.
Now, as I was saying, I will show you how to make the most powerful
explosive that was ever invented."

It is possible that I did not show as much interest and enthusiasm as he
expected, and to tell the truth I was a little nervous. Spooks do not
have the same interest in being careful in their experiments--an
accident or two is of little consequence to them, but might be decidedly
disagreeable to me. I may have shown something of what I was thinking in
my manner, for Spook looked at me keenly.

"What is the matter? You do not appear interested."

"On the contrary," I answered, "I am deeply so, but do we not run
considerable risk in trying such experiments in a laboratory without
the consent of its owner?"

"Not at all, not at all. I will use a very small amount of the
explosive, and there will be no damage done."

"Have you attempted to make it before, Mr. Spook?" I ventured.

"Oh, yes, last week; that was a mistake--you see now I know all about
it, I didn't then; the explosion was something awful--it blew the
building pretty much all to pieces. If I had been alive I don't believe
you could have found a piece of me as large as your finger--they called
it spontaneous combustion; however, we won't have anything of that kind
to-night."

"Please don't," I answered.

"No, I promise you. Now we