There were several jars of various liquids on the table and a number of chemicals. Among other things was a sort of gourd, encrusted with a black substance, and in a corner was a box from which sounds issued as if it contained something alive.
I did not trouble Kennedy with questions, for I was only too glad when he consented to take a brisk walk and join me in a thick porterhouse.
It was a large party that gathered in Kennedy’s laboratory that night, one of the largest he had ever had. Mr. and Mrs. Wainwright and Miss Marian came, the ladies heavily veiled. Doctor Nott and Mr. Whitney were among the first to arrive. Later came Mr. Vanderdyke and last of all Mrs. Ralston with Inspector O’Connor. Altogether it was an unwilling party.
“I shall begin,” said Kennedy, “by going over, briefly, the facts in this case.”
Tersely he summarised it, to my surprise laying great stress on the proof that the couple had been asphyxiated.
“But it was no ordinary asphyxiation,” he continued. “We have to deal in this case with a poison which is apparently among the most subtle known. A particle of matter so minute as to be hardly distinguishable by the naked eye, on the point of a needle or a lancet, a prick of the skin scarcely felt under any circumstances and which would pass quite unheeded if the attention were otherwise engaged, and not all the power in the world—unless one was fully prepared—could save the life of the person in whose skin the puncture had been made.”
Craig paused a moment, but no one showed any evidence of being more than ordinarily impressed.
“This poison, I find, acts on the so-called endplates of the muscles and nerves. It produces complete paralysis, but not loss of consciousness, sensation, circulation, or respiration until the end approaches. It seems to be one of the most powerful sedatives I have ever heard of. When introduced in even a minute quantity it produces death finally by asphyxiation—by paralysing the muscles of respiration. This asphyxia is what so puzzled the coroner.
“I will now inject a little of the blood serum of the victims into a white mouse.”
He took a mouse from the box I had seen, and with a needle injected the serum. The mouse did not even wince, so lightly did he touch it, but as we watched, its life seemed gently to ebb away, without pain and without struggle. Its breath simply seemed to stop.
Next he took the gourd I had seen on the table and with a knife scraped off just the minutest particle of the black licorice-like stuff that encrusted it. He dissolved the particle in some alcohol and with a sterilised needle repeated his experiment on a second mouse. The effect was precisely similar to that produced by the blood on the first.
It did not seem to me that anyone showed any emotion except possibly the slight exclamation that escaped Miss Marian Wainwright. I fell to wondering whether it was prompted by a soft heart or a guilty conscience.
We were all intent on what Craig was doing, especially Doctor Nott, who now broke in with a question.
“Professor Kennedy, may I ask a question? Admitting that the first mouse died in an apparently similar manner to the second, what proof have you that the poison is the same in both cases? And if it is the same can you show that it affects human beings in the same way, and that enough of it has been discovered in the blood of the victims to have caused their death? In other words, I want the last doubt set aside. How do you know absolutely that this poison which you discovered in my office last night in that black precipitate when you added the ether—how do you know that it asphyxiated the victims?”
If ever Craig startled me it was by his quiet reply. “I’ve isolated it in their blood, extracted it, sterilised it, and I’ve tried it on myself.”
In breathless amazement, with eyes riveted on Craig, we listened.
“Altogether I was able to recover from the blood samples of both of the victims of this crime six centigrams of the poison,” he pursued. “Starting with two centigrams of it as a moderate dose, I injected it into my right arm subcutaneously. Then I slowly worked my way up to three and then four centigrams. They did not produce any very appreciable results other than to cause some dizziness, slight vertigo, a considerable degree of lassitude, and an extremely painful headache of rather unusual duration. But five centigrams considerably improved on this. It caused a degree of vertigo and lassitude that was most distressing, and six centigrams, the whole amount which I had recovered from the samples of blood, gave me the fright of my life right here in this laboratory this afternoon.
“Perhaps I was not wise in giving myself so large an injection on a day when I was overheated and below par otherwise because of the strain I have been under in handling this case. However that may be, the added centigram produced so much more on top of the five centigrams previously taken that for a time I had reason to fear that that additional centigram was just the amount needed to bring my experiments to a permanent close.
“Within three minutes of the time of injection the dizziness and vertigo had become so great as to make walking seem impossible. In another minute the lassitude rapidly crept over me, and the serious disturbance of my breathing made it apparent to me that walking, waving my arms, anything, was imperative. My lungs felt glued up, and the muscles of my chest refused to work. Everything swam before my eyes, and I was soon reduced to walking up and down the laboratory with halting steps, only preventing falling on the floor by holding fast to the edge of this table. It seemed to me that I spent hours gasping for breath. It reminded me of what I once experienced in the Cave of the Winds of Niagara, where water is more abundant in the atmosphere than air. My watch afterward indicated only about twenty minutes of extreme distress, but that twenty minutes is one never to be forgotten, and I advise you all, if you ever are so foolish as to try the experiment, to remain below the five-centigram limit.
“How much was administered to the victims, Doctor Nott, I cannot say, but it must have been a good deal more than I took. Six centigrams, which I recovered from these small samples, are only nine-tenths of a grain. Yet you see what effect it had. I trust that answers your question.”
Doctor Nott was too overwhelmed to reply.
“And what is this deadly poison?” continued Craig, anticipating our thoughts. “I have been fortunate enough to obtain a sample of it from the Museum of Natural History. It comes in a little gourd, or often a calabash. This is in a gourd. It is blackish brittle stuff encrusting the sides of the gourd just as if it was poured in in the liquid state and left to dry. Indeed, that is just what has been done by those who manufacture this stuff after a lengthy and somewhat secret process.”
He placed the gourd on the edge of the table where we could all see it. I was almost afraid even to look at it.
“The famous traveller, Sir Robert Schomburgh first brought it into Europe, and Darwin has described it. It is now an article of commerce and is to be found in the United States Pharmacopoeia as a medicine, though of course it is used in only very minute quantities, as a heart stimulant.”
Craig opened a book to a place he had marked:
“At least one person in this room will appreciate the local colour of a little incident I am going to read—to illustrate what death from this poison is like. Two natives of the part of the world whence it comes were one day hunting. They were armed with blowpipes and quivers full of poisoned darts made of thin charred pieces of bamboo tipped with this stuff. One of them aimed a dart. It missed the object overhead, glanced off the tree, and fell down on the hunter himself. This is how the other native reported the result:
“‘Quacca takes the dart out of his shoulder. Never a word. Puts it in his quiver and throws it in the stream. Gives me his blowpipe for his little son. Says to me good-bye for his wife