and so we have no vision-evidence of their being."

"But we see black objects in daylight," I objected.

"Very true," he went on warmly. "And that is because they are not
perfectly black. Were they perfectly black, absolutely black, as it
were, we could not see them--ay, not in the blaze of a thousand suns
could we see them! And so I say, with the right pigments, properly
compounded, an absolutely black paint could be produced which would
render invisible whatever it was applied to."

"It would be a remarkable discovery," I said non-committally, for the
whole thing seemed too fantastic for aught but speculative purposes.

"Remarkable!" Lloyd slapped me on the shoulder. "I should say so. Why,
old chap, to coat myself with such a paint would be to put the world at
my feet. The secrets of kings and courts would be mine, the machinations
of diplomats and politicians, the play of stock-gamblers, the plans
of trusts and corporations. I could keep my hand on the inner pulse of
things and become the greatest power in the world. And I--" He broke
off shortly, then added, "Well, I have begun my experiments, and I don't
mind telling you that I'm right in line for it."

A laugh from the doorway startled us. Paul Tichlorne was standing there,
a smile of mockery on his lips.

"You forget, my dear Lloyd," he said.

"Forget what?"

"You forget," Paul went on--"ah, you forget the shadow."

I saw Lloyd's face drop, but he answered sneeringly, "I can carry a
sunshade, you know." Then he turned suddenly and fiercely upon him.
"Look here, Paul, you'll keep out of this if you know what's good for
you."

A rupture seemed imminent, but Paul laughed good-naturedly. "I wouldn't
lay fingers on your dirty pigments. Succeed beyond your most sanguine
expectations, yet you will always fetch up against the shadow. You can't
get away from it. Now I shall go on the very opposite tack. In the very
nature of my proposition the shadow will be eliminated--"

"Transparency!" ejaculated Lloyd, instantly. "But it can't be achieved."

"Oh, no; of course not." And Paul shrugged his shoulders and strolled
off down the briar-rose path.

This was the beginning of it. Both men attacked the problem with all
the tremendous energy for which they were noted, and with a rancor and
bitterness that made me tremble for the success of either. Each trusted
me to the utmost, and in the long weeks of experimentation that followed
I was made a party to both sides