the answer that Joe Cardona wanted.
'Urlich!' gasped the gang leader. 'Professor — Folcroft Urlich! Place — on Long Island. Go — there.
He — he is — the one — '
'He tipped us off?' questioned Cardona.
'He — he must have,' blurted Ricordo. 'He — he told me to scram. Get him— out on Long Island — place
called Philbrook — '
Cardona was nodding. He saw Larry Ricordo close his eyes. The gang leader gasped no longer. But his
dying brain responded suddenly to a wild thought. A tremor shook Ricordo's frame as he remembered
the death trap which Urlich had prepared for all comers.
'Cardona' — Larry's lips snarled as his eyes opened for the final effort. 'Look out — when — you
get — when — you get — '
The effort was too great. Ricordo's twisted lips spat out a dying sigh. The gang leader's body nearly
rolled from Cardona's grasp. The detective could feel it go limp. He knew that the final spasm had
arrived. Larry Ricordo was dead!
Cardona let others hold the body. He arose to see Mayhew close beside him. Quickly, Cardona ordered
the other detective to take charge of Ricordo's removal. A dozen sleuths were here. Cardona growled
orders.
Two minutes later, the ace detective was striding from the terminal with a squad of men at his heels. They
piled into a waiting car, and Cardona gave the driver quick, tense orders. The car shot from the curb.
Shrieking along Lexington Avenue, it turned eastward toward a mammoth bridge that led to Long Island.
Detective Joe Cardona had worked speedily to-night. Less than an hour after Thomas Jocelyn's death,
he had received the tip-off concerning Larry Ricordo. Half an hour later, the gang lord had spoken
before he died from Cardona's shots. Half an hour from now, Cardona and his men would be at their
new objective.
Joe Cardona was on the trail of silent death. He did not know that one had gone before him — that The
Shadow was already at the spot where such death lurked.
The ace detective was pleased because he had forced those words from Larry Ricordo's dying lips. He
did not know that the gang lord had tried to give a warning also, but had failed!
Cardona and his men were heading for a fiendish trap. Soon they were to know the power of silent death
that Folcroft Urlich wielded!
CHAPTER XXI. TUBES OF DOOM
IN Professor Urlich's laboratory, a fiendish plan was nearing its completion. Cliff Marsland and Clyde
Burke, still bound beside the wall, were watching preparations that they knew would mean their doom.
All the lights in use within the room had been concentrated on this side of the laboratory, which was near
the front of the building. Sanoja and Rasch, the scientist's willing servants, had fitted gleaming
incandescents with reflectors so that a vivid glare pervaded this limited field.
Professor Urlich was seated in a folding armchair, with the air of a director in charge of a rehearsal. His
orders, barked in foreign tongues that the attendants understood, had brought forth prompt obedience.
Yet the forthcoming experiment had required considerable time for preparation.
Cliff Marsland had ceased to feign grogginess. Clyde Burke, beside him, was also fully conscious.
Despite the cold terror which Professor Urlich's presence caused, both of The Shadow's agents were
strangely fascinated by the details of the work which now seemed completed.
Directly in front of the two men stood a huge tripod, mounted on a circular base. This was a skeleton
structure that ran on wheels, and its three legs gave it the grotesque appearance of a lonely gallows. At
the top of the tripod were extended arms that supported a rim of metal.
This upper circle supported a huge carboy. The glass vessel, incased in wickerwork, gleamed with
greenish hue. Its stopper, which had been inserted in place, was a glass plug from which extended two
flexible pieces of shining hose.
As Sanoja pressed a little lever beside the rim that supported the carboy, the large container rocked
slightly, showing that it was on a pivot that would enable it to be inverted. Sanoja readjusted the lever
and the big vessel ceased to sway.
On either side of the central tripod stood a low skeleton base with upright rods that terminated in rings.
There were two of these, both large and massive.
Each pedestal held a container of thick glass, shaped like a mammoth test tube. Neither of the prisoners
had ever before seen such tremendous cylinders of glass. The tubes were more than eight feet in height,
and more than two feet in diameter.
As final preparation, Urlich's men had brought forward two caps of metal large enough to fit over the
large tubes. They had attached a hose to each cap. Professor Urlich cackled joyously as a signal that
everything was ready.
CLIFF MARSLAND studied the face of the fiend. A demoniacal glee illuminated Urlich's features. The
scientist had watched the work of his servants with increasing interest.
In spite of that fact, Cliff had noticed that the professor never failed to note the three unlighted
incandescents that projected above the spiral stairway at the center of the laboratory. Those bulbs were
scarcely visible in the darkness beyond the concentrated illumination; but had one suddenly commenced
to gleam, the professor would have spied it on the instant.
'We are ready, now,' remarked Professor Urlich, his eyes focused upon the silent prisoners. 'Inasmuch
as you are to be the subjects of my experiment, I shall explain its operation to you.'
He beckoned to Rasch, who appeared with a small tube that contained a tiny white mouse. The servant,
a grin on his dull face, held the tube in the light. The prisoners noted that it was capped with a metal cover
that had a round hole in the center.
Professor Urlich babbled in a foreign language. Sanoja passed a glass bottle to Rasch. The man held the
tube in one hand, the bottle in the other, and poured a greenish fluid from bottle into tube.
A sizzling, smoky mixture manifested itself. The green was tinged with white and fumes slowly came from
the hole in the cover. Slowly, the liquid cleared.
Simultaneous gasps of amazement came from Cliff and Clyde. The white mouse had vanished. The tube
contained nothing but a watery fluid!
'It has always been my wish,' proceeded the professor, 'to attempt this experiment on a larger scale. The
greenish fluid which you observed — the same liquid which is in the large carboy — is virtually a universal
solvent. It has no effect upon glass; but that is about the only substance which it does not dissolve with
rapacious power.
'The pieces of hose which project from the carboy are my own invention — a flexible material which
possess certain properties found in glass. It has been used to withstand the power of the solvent.
'Perhaps it is unkind' — Urlich's eyes were gleaming with irony— 'to discuss the details of this experiment
with my subjects. Perhaps you would prefer to be as the white mouse was: ignorant of what is to come.
However, I have already given you a very complete inkling, so I may as well proceed.
'Your lives mean nothing to me. Your deaths, however, would be advisable. In order to leave no
