of
surprise on his face.

"What is it!" asked the detective suddenly.

"This drawer feels very hot," said John,--he looked round as though to
measure the distance between the safe and the fire.

T. X. laid his hand upon the front of the drawer. It was indeed warm.

"Open it," said T. X., and Lexman turned the key and pulled the drawer
open.

As he did so, the whole contents burst up in a quick blaze of flame. It
died down immediately and left only a little coil of smoke that flowed
from the safe into the room.

"Don't touch anything inside," said T. X. quickly.

He lifted the drawer carefully and placed it under the light. In the
bottom was no more than a few crumpled white ashes and a blister of
paint where the flame had caught the side.

"I see," said T. X. slowly.

He saw something more than that handful of ashes, he saw the deadly
peril in which his friend was standing. Here was one half of the
evidence in Lexman's favour gone, irredeemably.

"The letter was written on a paper which was specially prepared by a
chemical process which disintegrated the moment the paper was exposed
to the air. Probably if you delayed putting the letter in the drawer
another five minutes, you would have seen it burn before your eyes. As
it was, it was smouldering before you had turned the key of the box. The
envelope!"

"Kara burnt it," said Lexman in a low voice, "I remember seeing him take
it up from the table and throw it in the fire."

T. X. nodded.

"There remains the other half of the evidence," he said grimly, and when
an hour later, the village constable returned to report that in spite
of his most careful search he had failed to discover the dead man's
revolver, his anticipations were realized.

The next morning John Lexman was lodged in Lewes gaol on a charge of
wilful murder.

A telegram brought Mansus from London to Beston Tracey, and T. X.
received him in the library.

"I sent for you, Mansus, because I suffer from the illusion that you
have more brains than most of the people in my department, and that's
not saying much."

"I am very grateful to you, sir, for putting me right with
Commissioner," began Mansus, but T. X. stopped him.

"It is the duty of every head of departments," he said oracularly, "to
shield the incompetence of his subordinates. It is only by the adoption
of some such method that the decencies of the public life can be
observed. Now get down to this." He gave a sketch of the cas