"Let me take these samples and make some further tests. I am sure of it, but it is new to me. Wait till to-morrow night, when my chain of evidence is completed. Then you are all cordially invited to attend at my laboratory at the university. I'll ask you, Mr. Whitney, to come armed with a warrant for John or Jane Doe. Please see that the Wainwrights, particularly Marian, are present. You can tell Inspector O'Connor that Mr. Vanderd.y.k.e and Mrs. Ralston are required as material witnesses--anything so long as you are sure that these five persons are present. Good night, gentlemen."

We rode back to the city in silence, but as we neared the station, Kennedy remarked: "You see, Walter, these people are like the newspapers. They are floundering around in a sea of unrelated facts.

There is more than they think back of this crime. I've been revolving in my mind how it will be possible to get some inkling about this concession of Vanderd.y.k.e's, the mining claim of Mrs. Ralston, and the exact itinerary of the Wainwright trip in the Far East. Do you think you can get that information for me? I think it will take me all day to-morrow to isolate this poison and get things in convincing shape on that score. Meanwhile if you can see Vanderd.y.k.e and Mrs. Ralston you can help me a great deal. I am sure you will find them very interesting people."

"I have been told that she is quite a female high financier," I replied, tacitly accepting Craig's commission. "Her story is that her claim is situated near the mine of a group of powerful American capitalists, who are opposed to having any compet.i.tion, and on the strength of that story she has been raking in the money right and left. I don't know Vanderd.y.k.e, never heard of him before, but no doubt he has some equally interesting game."

"Don't let them think you connect them with the case, however,"

cautioned Craig.

Early the next morning I started out on my quest for facts, though not so early but that Kennedy had preceded me to his work in his laboratory.

It was not very difficult to get Mrs. Ralston to talk about her troubles with the government. In fact, I did not even have to broach the subject of the death of Templeton. She volunteered the information that in his handling of her case he had been very unjust to her, in spite of the fact that she had known him well a long time ago. She even hinted that she believed he represented the combination of capitalists who were using the government to aid their own monopoly and prevent the development of her mine. Whether it was an obsession of her mind, or merely part of her clever scheme, I could not make out. I noted, however, that when she spoke of Templeton it was in a studied, impersonal way, and that she was at pains to lay the blame for the governmental interference rather on the rival mine-owners.

It quite surprised me when I found from the directory that Vanderd.y.k.e's office was on the floor below in the same building. Like Mrs. Ralston's, it was open, but not doing business, pending the investigation by the Post-Office Department.

Vanderd.y.k.e was a type of which I had seen many before. Well dressed to the extreme, he displayed all those evidences of prosperity which are the stock in trade of the man with securities to sell. He grasped my hand when I told him I was going to present the other side of the post-office cases and held it between both of his as if he had known me all his life. Only the fact that he had never seen me before prevented his calling me by my first name. I took mental note of his stock of jewellery, the pin in his tie that might almost have been the Hope diamond, the heavy watch chain across his chest, and a very brilliant seal ring of lapis lazuli on the hand that grasped mine. He saw me looking at it and smiled.

"My dear fellow, we have deposits of that stuff that would make a fortune if we could get the machinery to get at it. Why, sir, there is lapis lazuli enough on our claim to make enough ultramarine paint to supply all the artists to the end of the world. Actually we could afford to crush it up and sell it as paint. And that is merely incidental to the other things on the concession. The asphalt's the thing. That's where the big money is. When we get started, sir, the old asphalt trust will simply melt away, melt away."

He blew a cloud of tobacco smoke and let it dissolve significantly in the air.

When it came to talking about the suits, however, Vanderd.y.k.e was not so communicative as Mrs. Ralston, but he was also not so bitter against either the post-office or Templeton.

"Poor Templeton," he said. "I used to know him years ago when we were boys. Went to school with him and all that sort of thing, you know, but until I ran across him, or rather he ran across me, in this investigation I hadn't heard much about him. Pretty clever fellow he was, too. The state will miss him, but my lawyer tells me that we should have won the suit anyhow, even if that unfortunate tragedy hadn't occurred. Most unaccountable, wasn't it? I've read about it in the papers for old time's sake, and can make nothing out of it."

I said nothing, but wondered how he could pa.s.s so lightheartedly over the death of the woman who had once been his wife. However, I said nothing. The result was he launched forth again on the riches of his Venezuelan concession and loaded me down with "literature," which I crammed into my pocket for future reference.

My next step was to drop into the office of a Spanish-America paper whose editor was especially well informed on South American affairs.

"Do I know Mrs. Ralston?" he repeated, thoughtfully lighting one of those black cigarettes that look so vicious and are so mild. "I should say so. I'll tell you a little story about her. Three or four years ago she turned up in Caracas. I don't know who Mr. Ralston was--perhaps there never was any Mr. Ralston. Anyhow, she got in with the official circle of the Castro government and was very successful as an adventuress. She has considerable business ability and represented a certain group of Americans. But, if you recall, when Castro was eliminated pretty nearly everyone who had stood high with him went, too.

It seems that a number of the old concessionaires played the game on both sides. This particular group had a man named Vanderd.y.k.e on the anti-Castro side. So, when Mrs. Ralston went, she just quietly sailed by way of Panama to the other side of the continent, to Peru--they paid her well--and Vanderd.y.k.e took the t.i.tle role.

"Oh, yes, she and Vanderd.y.k.e were very good friends, very, indeed. I think they must have known each other here in the States. Still they played their parts well at the time. Since things have settled down in Venezuela, the concessionaires have found no further use for Vanderd.y.k.e either, and here they are, Vanderd.y.k.e and Mrs. Ralston, both in New York now, with two of the most outrageous schemes of financing ever seen on Broad Street. They have offices in the same building, they are together a great deal, and now I hear that the state attorney-general is after both of them."

With this information and a very meagre report of the Wainwright trip to the Far East, which had taken in some out-of-the-way places apparently, I hastened back to Kennedy. He was surrounded by bottles, tubes, jars, retorts, Bunsen burners, everything in the science and art of chemistry, I thought.

I didn't like the way he looked. His hand was unsteady, and his eyes looked badly, but he seemed quite put out when I suggested that he was working too hard over the case. I was worried about him, but rather than say anything to offend him I left him for the rest of the afternoon, only dropping in before dinner to make sure that he would not forget to eat something. He was then completing his preparations for the evening.

They were of the simplest kind, apparently. In fact, all I could see was an apparatus which consisted of a rubber funnel, inverted and attached to a rubber tube which led in turn into a jar about a quarter full of water. Through the stopper of the jar another tube led to a tank of oxygen.

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. Vanderd.y.k.e 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 p.r.i.c.k of the skin scarcely felt under any circ.u.mstances and which would pa.s.s 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 quant.i.ty 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 sc.r.a.ped 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 la.s.situde, and an extremely painful headache of rather unusual duration. But five centigrams considerably improved on this. It caused a degree of vertigo and la.s.situde 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 la.s.situde 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, antic.i.p.ating 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 quant.i.ties, 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 ill.u.s.trate 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 and the village. Then he lies down. His tongue talks no longer. No sight in his eyes. He folds his arms. He rolls over slowly. His mouth moves without sound. I feel his heart. It goes fast and then slow. It stops. Quacca has shot his last woorali dart.'"

We looked at each other, and the horror of the thing sank deep into our minds. Woorali. What was it? There were many travellers in the room who had been in the Orient, home of poisons, and in South America. Which one had run across the poison?