PAGE 9
"Spontaneous Combustion"
by
“Tracks of blood such as are left by dragging a bleeding body differ very greatly from tracks of arterial blood which are left when the victim has strength to move himself. Continuing my speculations, supposing it to be a blood-spot, what did it indicate? Clearly that Mr. Langley was struck by somebody on the head with a heavy instrument, perhaps in another part of the room, that he was choked, that as the drops of blood oozed from the wound on his head, he was dragged across the floor, in the direction of the fireplace–“
“But, Professor Kennedy,” interrupted Doctor Putnam, “have you proved that the spot was a blood-spot? Might it not have been a paint-spot or something of that sort?”
Kennedy had apparently been waiting for just such a question.
“Ordinarily, water has no effect on paint,” he answered. “I found that the spot could be washed off with water. That is not all. I have a test for blood that is so delicately sensitive that the blood of an Egyptian mummy thousands of years old will respond to it. It was discovered by a German scientist, Doctor Uhlenhuth, and was no longer ago than last winter applied in England in connection with the Clapham murder. The suspected murderer declared that stains on his clothes were only spatters of paint, but the test proved them to be spatters of blood. Walter, bring in the cage with the rabbits.”
I opened the door and took the cage from the groom, who had brought it up from the stable and stood waiting with it some distance away.
“This test is very simple, Doctor Putnam,” continued Craig, as I placed the cage on the table and Kennedy unwrapped the sterilised test-tubes. “A rabbit is inoculated with human blood, and after a time the serum that is taken from the rabbit supplies the material for the test.
“I will insert this needle in one of these rabbits which has been so inoculated and will draw off some of the serum, which I place in this test-tube to the right. The other rabbit has not been inoculated. I draw off some of its serum and place that tube here on the left–we will call that our ‘control tube.’ It will check the results of our tests.
“Wrapped up in this paper I have the scrapings of the spot which I found on the floor–just a few grains of dark, dried powder. To show how sensitive the test is, I will take only one of the smallest of these minute scrapings. I dissolve it in this third tube with distilled water. I will even divide it in half, and place the other half in this fourth tube.
“Next I add some of the serum of the uninoculated rabbit to the half in this tube. You observe, nothing happens. I add a little of the serum of the inoculated rabbit to the other half in this other tube. Observe how delicate the test is–“
Kennedy was leaning forward, almost oblivious of the rest of us in the room, talking almost as if to himself. We, too, had riveted our eyes on the tubes.
As he added the serum from the inoculated rabbit, a cloudy milky ring formed almost immediately in the hitherto colourless, very dilute blood-solution.
“That,” concluded Craig, triumphantly holding the tube aloft, “that conclusively proves that the little round spot on the hardwood floor was not paint, was not anything in this wide world but blood.”
No one in the room said a word, but I knew there must have been someone there who thought volumes in the few minutes that elapsed.
“Having found one blood-spot, I began to look about for more, but was able to find only two or three traces where spots seemed to have been. The fact is that the blood spots had been apparently carefully wiped up. That is an easy matter. Hot water and salt, or hot water alone, or even cold water, will make quite short work of fresh blood-spots–at least to all outward appearances. But nothing but a most thorough cleaning can conceal them from the Uhlenhuth test, even when they are apparently wiped out. It is a case of Lady Macbeth over again, crying in the face of modern science, ‘Out, out, damned spot.’