"You will have to have better evidence than that," sneered Professor
Grimm.

"I think I will have," announced Jack quietly. "Of course those marks
might have been made by any sharp, rusty object. Now the bell metal
rusts scarcely at all, but the iron clapper of a bell does. The rust
from that runs down inside a bell, and gets on the edges. I took some
iron rust from the clapper of the stolen bell and placed it in a test
tube. I assumed, for the purpose of experimenting, that I did not
know that it was iron rust, but only suspected it. I applied the
proper chemical tests, and I got the results that showed me there was
iron present in the test tube. Here, I will show you."

Jack mixed a few chemicals and soon the brown mixture in the tube
turned red.

"That is from the bell clapper," the young chemist went on. "Here is
a solution made from scraping the lines on the duster. I will apply
the test and see what happens."

While the others looked on anxiously Jack dropped some of the mixture
into the second tube. In an instant it turned red.

"There!" exclaimed Jack, holding up the two tubes, side by side. "The
same color coming in both mixtures from the same strength of
chemicals that I used, shows that the iron rust on the duster and
that on the bell clapper are the same."

"What does that prove, except that you might have worn the duster?"
asked Dr. Mead.