that the resulting mixture has the appearance of pure water.
The proportion of blood cannot be more than one in a million.
I have no doubt, however, that we shall be able to obtain the
characteristic reaction." As he spoke, he threw into the vessel
a few white crystals, and then added some drops of a transparent
fluid. In an instant the contents assumed a dull mahogany colour,
and a brownish dust was precipitated to the bottom of the glass jar.

"Ha! ha!" he cried, clapping his hands, and looking as delighted
as a child with a new toy. "What do you think of that?"

"It seems to be a very delicate test," I remarked.

"Beautiful! beautiful! The old Guiacum test was very clumsy
and uncertain. So is the microscopic examination for blood
corpuscles. The latter is valueless if the stains are a few
hours old. Now, this appears to act as well whether the
blood is old or new. Had this test been invented, there are
hundreds of men now walking the earth who would long ago have
paid the penalty of their crimes."

"Indeed!" I murmured.

"Criminal cases are continually hinging upon that one point.
A man is suspected of a crime months perhaps after it has
been committed. His linen or clothes are examined, and
brownish stains discovered upon them. Are they blood stains,
or mud stains, or rust stains, or fruit stains, or what are
they? That is a question which has puzzled many an expert,
and why? Because there was no reliable test. Now we have