had half crossed the room in a leap, turned to his
friends, warning them back.

"Too late. We can't go out yet. Wait for the fumes to dissipate."

They stood, the four men, rigid. Presently Average Jones, opening a rear
window, leaped to the ground, followed by the others, and came around
the corner of the porch. The dead man lay with peaceful face. Professor
Gehren uncovered.

"God forgive him," he said. "Who shall say that he was not right?"

"Not I," said the young assistant secretary in awed tones. "I'm glad he
escaped. But what am I to do? Here we are with a dead body on our hands,
and a state secret to be kept from the prying police."

Average Jones stood thinking for a moment, then he entered the room and
called up the coroner's office on the telephone.

"Listen, you men," he said to his companions. Then, to the official who
answered: "There's a suicide at 428 Oliver Avenue, the Bronx. Four of
us witnessed it. We had come to keep an appointment with the man in
connection with a discovery he claimed in metallurgy, and found him
dying. Yes; we will wait here. Good-by."

Returning to the porch again, he cleared away the fragments of glass,
aided by Bertram. To one of these clung a shred of paper. For all his
languid self-control the club dilettante shivered a little as he thrust
at it with a stick.

"Look, Average, it's the 'Mercy' sign again. What a hideous travesty!"

Average Jones shook his bead.

"It isn't 'Mercy,' Bert. It's the label that he attached, for
precaution, to everything that had to do with his deadly stuff.
The formula for cyanide of cacodyl is 'Me-2CY.' It was the scrawly
handwriting that misled; that's all."

"So I was right when I suggested that his 'Mercy' had gone back on him,"
said Mr. Thomas Colvin McIntyre, with a semi-hysterical giggle.

Average Jones looked from the peaceful face of the dead to the label,
fluttering in the light breeze.

"No," he said gravely. "You were wrong. It was his friend to the last."

CHAPTER VI. BLUE FIRES

"Cabs for comfort; cars for company," was an apothegm which Average
Jones had evolved from experience. A professed student of life, he
maintained, must keep in touch with life at every feasible angle. No
experience should come amiss to a detective; he should be a pundit of
all knowledge. A detective he now frankly considered himself; and the
real drudgery of his unique profession of Ad-Visor was supportable only
because of the compens