“Here, don’t shoot this box through as fast as you’ve done the others,” counseled Dick, as he picked up a small box, some eighteen inches long and about a foot square at the end.  “The label says, ‘Extra fragile.  Value two hundred and fifty dollars.’”

Dave reached out to receive it, as Dick laid it carefully on the counter.

“Packages of that value have to be handled with caution,” muttered Dave.  “When a fellow puts on a valuation like that, it means that he intends to make claim for any damage whatever.”

“Hold on,” muttered Dick, eyeing the counter.  “There’s something leaking from the box now.”

Dave took his hands away, then bent over to have a look with Dick.

A very tiny puddle of some very thick, syrupy stuff was slowly forming on the counter.

“I wonder if the contents have been damaged?” muttered Dave, uneasily.  Then added, in a whisper: 

“The night manager will blame us, and hold me responsible, if there is any damage.”

Both boys carefully inspected the tiny puddle for a few moments.

“Say, don’t touch the box again,” counseled Prescott, uneasily.  “Do you know what that stuff looks to me like, Dave?”

“What?”

“Do you remember the thick stuff that Dr. Thornton showed us in IV.  Chemistry the other day?”

“Great Scott!” breathed Dave Darrin, anxiously.  “You don’t mean nitroglycerine?”

“But I do!” Dick nodded, energetically.

“Wow!  Don’t stir from here.  I’ll call the night manager.”

Night Manager Drowan came over at once, eyeing the box and the tiny pool of thick stuff.

“I never saw nitroglycerine but once,” remarked Mr. Drowan, nervously.  “I should say this stuff looks just like it.  We won’t take any chances, anyway.  Dave, you go to the telephone, and notify the police.  Your friends can stand guard over the box so that no one gets a chance to go near it.”

But, while Dave was at the ’phone, Mr. Drowan hung over the box as though fascinated.

“It takes fire to set this stuff off, doesn’t it?” he asked.

“No,” Dick replied.  “If it’s nitroglycerine in that box, a light, sharp blow might be enough to do the trick.  At least, that was about what Dr. Thornton said.”

Dave came back with word that the police would send some one at once.

“They asked me whom the stuff was addressed to,” Dave continued, “and I had to admit that I didn’t know.”

“It’s addressed to Simon Tripps, to be called for.  Identification by letter herewith,” read Dick Prescott, from the label.

“Yes; I have the letter,” nodded Mr. Drowan.  “It contains the signature of the party who’s to call for the box.  That’s all the identification that’s asked.”

At this moment Officer Hemingway, in plain clothes, came in, followed by a policeman in uniform.

Hemingway took a look at the stuff slowly oozing out of a corner of the box.