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DEEP in the coal mines of Pennsylvania and even in submarines lying hidden beneath the waves of the sea, white mice are used to detect the presence of poisonous gases which, even in minute quantities, are fatal to mankind.

In The Azure Ring, a narrative of death and mystery, Craig Kennedy uses two of these tiny animals to protect a life and to convict a vicious and cruel murderer.

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In the Museum of Natural History is a crude specimen of one of the most deadly poisons in the vegetable world. What is it? And was it employed to kill a young attorney, or did he die by accident?

The Azure Ring

By Arthur B. Reeve

FILES of newspapers and innumerable clippings from the press bureaus littered Kennedy's desk in rank profusion. Kennedy himself was so deeply absorbed that I had merely said good evening as I came in and had started to open my mail. With an impatient sweep of his hand, however, he brushed the whole mass of newspapers into the waste-basket.

"It seems to me, Walter," he exclaimed in disgust, "that this mystery is considered insoluble for the very reason which should make it easy to solve—the extraordinary character of its features."

Inasmuch as he had opened the subject, I laid down the letter I was reading. "I'll wager I can tell you just why you made that remark, Craig," I ventured. "You're reading up on that Wainwright-Templeton affair."

"You are on the road to becoming a detective yourself, Walter," he answered with a touch of sarcasm. "Your ability to add two units to two other units and obtain four units is almost worthy of Inspector O'Connor. You are right and within a quarter of an hour the district attorney of Westchester County will be here. He telephoned me this afternoon and sent an assistant with this mass of dope. I suppose he'll want it back," he added, fishing the newspapers out of the basket again. "But, with all due respect to your profession, I'll say that no one would ever get on speaking terms with the solution of this case if he had to depend solely on the newspaper writers."

"No?" I queried, rather nettled at his tone.

"No," he repeated emphatically. "Here one of the most popular girls in the fashionable suburb of Williston, and one of the leading younger members of the bar in New York, engaged to be married, are found dead in the library of the girl's home the day before the ceremony. And now, a week later, no one knows whether it was an accident due to the fumes from the antique charcoal-brazier, or whether it was a double suicide, or suicide and murder, or a double murder, or—or—why, the experts haven't even been able to agree on whether they have discovered poison or not," he continued, growing as excited as the city editor did over my first attempt as a cub reporter.

"They haven't agreed on anything except that on the eve of what was, presumably, to have been the happiest day of their lives two of the best known members of the younger set are found dead, while absolutely no one, as far as is known, can be proved to have been near them within the time necessary to murder them. No wonder the coroner says it is simply a case of asphyxiation. No wonder the district attorney is at his wits' end. You fellows have hounded them with your hypotheses until they can't see the facts straight. You suggest one solution and before—"

The door-bell sounded insistently, and without waiting for an answer a tall, spare, loose-jointed individual stalked in and laid a green bag on the table.

The Affidavit

"GOOD evening, Professor Kennedy," he began brusquely. "I am District Attorney Whitney, of Westchester. I see you have been reading up on the case. Quite right."

"Quite wrong," answered Craig. "Let me introduce my friend, Mr. Jameson, of the Star. Sit down. Jameson knows what I think of the way the newspapers have handled this case. I was about to tell him as you came in that I intended to disregard everything that had been printed, to start out with you as if it were a fresh subject and get the facts at first hand. Let's get right down to business. First tell us just how it was that Miss Wainwright and Mr. Templeton were discovered and by whom."

The district attorney loosened the cords of the green bag and drew out a bundle of documents. "I'll read you the affidavit of the maid who found them," he said, fingering the documents nervously. "You see, John Templeton had left his office in New York early that afternoon, telling his father that he was going to visit Miss Wainwright. He caught the three-twenty train, reached Williston all right, walked to the Wainwright house, and, in spite of the bustle of preparation for the wedding, the next day, he spent the rest of the afternoon with Miss Wainwright. That's where the mystery begins. They had no visitors. At least, the maid who answers the bell says they had none. She was busy with the rest of the family, and I believe the front door was not locked—we don't lock our doors in Williston, except at night."

He had found the paper and paused to impress these facts on our minds.

"Mrs. Wainwright and Miss Marian Wainwright, the sister, were busy about the house. Mrs. Wainwright wished to consult Laura about something. She summoned the maid and asked if Mr. Templeton and Miss Wainwright were in the house. The maid replied that she would see, and this is her affidavit. Ahem! I'll skip the legal part:

"'I knocked at the library door twice, but obtaining no answer, I supposed they had gone out for a walk or perhaps a ride across country as they often did. I opened the door partly and looked in. There was a silence in the room, a strange, queer silence. I opened the door further and, looking toward the davenport in the corner, I saw Miss Laura and Mr. Templeton in such an awkward position. They looked as if they had fallen asleep. His head was thrown back against the cushions of the davenport, and on his face was a most awful look. It was discoloured. Her head had fallen forward on his shoulder, sideways, and on her face, too, was the same terrible stare and the same discolouration. Their right hands were tightly clasped.

A Double Tragedy

"I CALLED to them. They did not answer. Then the horrible truth flashed on me. They were dead. I felt giddy for a minute, but quickly recovered myself, and with a cry for help I rushed to Mrs. Wainwright's room, shrieking that they were dead. Mrs. Wainwright fainted. Miss Marian called the doctor on the telephone and helped us restore her mother. She seemed perfectly cool in the tragedy, and I do not know what we servants should have done if she had not been there to direct us. The house was frantic, and Mr. Wainwright was not at home.

"I did not detect any odour when I opened the library door. No glasses or bottles or vials or other receptacles which could have held poison were discovered or removed by me, or to the best of my knowledge and belief by anyone else."

"What happened next?" asked Craig eagerly.

"The family physician arrived and sent for the coroner immediately, and later for myself. You see, he thought at once of murder."

"But the coroner, I understand, thinks differently," prompted Kennedy.

"Yes, the coroner has declared the case to be accidental. He says that the weight of evidence points positively to asphyxiation. Still, how can it be asphyxiation? They could have escaped from the room at any time; the door was not locked. I tell you, in spite of the fact that the tests for poison in their mouths, stomachs, and blood have so far revealed nothing, I still believe that John Templeton and Laura Wainwright were murdered."

Kennedy looked at his watch thoughtfully. "You have told me just enough to make me want to see the coroner himself," he mused. "If we take the next train out to Williston with you, will you engage to get us a half-hour talk with him on the case, Mr. Whitney?"

"Surely. But we'll have to start right away. I've finished my other business in New York. Inspector O'Connor—ah, I see you know him—has promised to secure the attendance of anyone whom I can show to be a material witness in the case. Come on, gentlemen: I'll answer your other questions on the train."

As we settled ourselves in the smoker, Whitney remarked in a low voice, "You know, someone has said that there is only one thing more difficult to investigate and solve than a crime whose commission is surrounded by complicated circumstances and that is a crime whose perpetration is wholly devoid of circumstances."

"Are you so sure that this crime is wholly devoid of circumstances?" asked Craig.

"Professor," he replied, "I'm not sure of anything in this case. If I were I should not require your assistance. I would like the credit of solving it myself, but it is beyond me. Just think of it: so far we haven't a clue, at least none that shows the slightest promise, although we have worked night and day for a week. It's all darkness. The facts are so simple that they give us nothing to work on. It is like a blank sheet of paper."

Was it Accident?

KENNEDY said nothing, and the district attorney proceeded: "I don't blame Mr. Nott, the coroner, for thinking it an accident. But to my mind, some master criminal must have arranged this very baffling simplicity of circumstances. You recall that the front door was unlocked. This person must have entered the house unobserved, not a difficult thing to do, for the Wainwright house is somewhat isolated. Perhaps this person brought along some poison in the form of a beverage, and induced the two victims to drink. And then, this person must have removed the evidences as swiftly as they were brought in and by the same door. That, I think, is the only solution."

"That is not the only solution. It is one solution," interrupted Kennedy quietly.

"Do you think someone in the house did it?" I asked quickly.

"I think," replied Craig, carefully measuring his words, "that if poison was given them it must have been by someone they both knew pretty well."

No one said a word, until at last I broke the silence. "I know from the gossip of the Star office that many Williston people say that Marian was very jealous of her sister Laura for capturing the catch of the season. Williston people don't hesitate to hint at it."

Whitney produced another document from that fertile green bag. It was another affidavit. He handed it to us. It was a statement signed by Mrs. Wainwright, and read:

"Before God, my daughter Marian is innocent. If you wish to find out all, find out more about the past history of Mr. Templeton before he became engaged to Laura. She would never in the world have committed suicide. She was too bright and cheerful for that, even if Mr. Templeton had been about to break off the engagement. My daughters Laura and Marian were always treated by Mr. Wainwright and myself exactly alike. Of course they had their quarrels, just as all sisters do, but there was never, to my certain knowledge, a serious disagreement, and I was always close enough to my girls to know. No, Laura was murdered by someone outside."

Kennedy did not seem to attach much importance to this statement. "Let us see," he began reflectively. "First, we have a young woman especially attractive and charming in both person and temperament. She is just about to be married and, if the reports are to be believed, there was no cloud on her happiness. Secondly, we have a young man whom everyone agrees to have been of an ardent, energetic, optimistic temperament. He had everything to live for, presumably. So far, so good. Everyone who has investigated this case, I understand, has tried to eliminate the double-suicide and the suicide-and-murder theories. That is all right, providing the facts are as stated. We shall see, later, when we interview the coroner. Now, Mr. Whitney, suppose you tell us briefly what you have learned about the past history of the two unfortunate lovers."

Craig Rakes Up History

"WELL, the Wainwrights are an old Westchester family, not very wealthy, but of the real aristocracy of the county. There were only two children, Laura and Marian. The Templetons were much the same sort of family. The children all attended a private school at White Plains, and there also they met Schuyler Vanderdyke. These four constituted a sort of little aristocracy in the school. I mention this, because Vanderdyke later became Laura's first husband. This marriage with Templeton was a second venture."

"How long ago was she divorced?" asked Craig attentively.

"About three years ago. I'm coming to that in a moment. The sisters went to college together, Templeton to law school, and Vanderdyke studied civil engineering. Their intimacy was pretty well broken up, all except Laura's and Vanderdyke's. Soon after he graduated he was taken into the construction department of the Central Railroad by his uncle, who was a vice-president, and Laura and he were married. As far as I can learn he had been a fellow of convivial habits at college, and about two years after their marriage his wife suddenly became aware of what had long been well known in Williston, that Vanderdyke was paying marked attention to a woman named Miss Laporte in New York.

"No sooner had Laura Vanderdyke learned of this intimacy of her husband," continued Whitney, "than she quietly hired private detectives to shadow him, and on their evidence she obtained a divorce. The papers were sealed, and she resumed her maiden name.

"As far as I can find out, Vanderdyke then disappeared from her life. He resigned his position with the railroad and joined a party of engineers exploring the upper Amazon. Later he went to Venezuela. Miss Laporte also went to South America about the same time, and was for a time in Venezuela, and later in Peru.

"Vanderdyke seems to have dropped all his early associations completely, though at present I find he is back in New York raising capital for a company to exploit a new asphalt concession in the interior of Venezuela. Miss Laporte has also reappeared in New York as Mrs. Ralston, with a mining claim in the mountains of Peru."

"And Templeton?" asked Craig. "Had he had any previous matrimonial ventures?"

"No, none. Of course he had had love affairs, mostly with the country-club set. He had known Miss Laporte pretty well, too, while he was in law school in New York. But when he settled down to work he seems to have forgotten all about the girls for a couple of years or so. He was very anxious to get ahead, and let nothing stand in his way. He was admitted to the bar and taken in by his father as junior member of the firm of Templeton, Mills & Templeton. Not long ago he was appointed a special master to take testimony in the get-rich-quick-company prosecutions, and I happen to know that he was making good in the investigation."

Templeton

KENNEDY nodded. "What sort of fellow personally was Templeton?" he asked.

"Very popular," replied the district attorney, "both at the country club and in his profession in New York. He was a fellow of naturally commanding temperament—the Templetons were always that way. I doubt if many young men even with his chances could have gained such a reputation at thirty-five as his. Socially he was very popular, too, a great catch for all the sly mamas of the country club who had marriageable daughters. He liked automobiles and outdoor sports, and he was strong in politics, too. That was how he got ahead so fast.

"Well, to cut the story short, Templeton met the Wainwright girls again last summer at a resort on Long Island. They had just returned from a long trip abroad, spending most of the time in the Far East with their father, whose firm has business interests in China. The girls were very attractive. They rode and played tennis and golf better than most of the men, and this fall Templeton became a frequent visitor at the Wainwright home in Williston.

The Charcoal Brazier

"PEOPLE who know them best tell me that his first attentions were paid to Marian, a very dashing and ambitious young woman. Nearly every day Templeton's car stopped at the house and the girls and some friend of Templeton's in the country club went for a ride. They tell me that at this time Marian always sat with Templeton on the front seat. But after a few weeks the gossips—nothing of that sort ever escapes Williston—said that the occupant of the front seat was Laura. She often drove the car herself and was very clever at it. At any rate, not long after that the engagement was announced."

As he walked up from the pretty little Williston station Kennedy asked: "One more question, Mr. Whitney. How did Marian take the engagement?"

The district attorney hesitated. "I will be perfectly frank, Mr. Kennedy," he answered. "The country-club people tell me that the girls were very cool toward each other. That was why I got that statement from Mrs. Wainwright. I wish to be perfectly fair to everyone concerned in this case."

We found the coroner quite willing to talk, in spite of the fact that the hour was late. "My friend, Mr. Whitney, here, still holds the poison theory," began the coroner, "in spite of the fact that everything points absolutely toward asphyxiation. If I had been able to discover the slightest trace of illuminating-gas in the room I should have pronounced it asphyxia at once. All the symptoms accorded with it. But the asphyxia was not caused by escaping illuminating-gas.

"There was an antique charcoal-brazier in the room, and I have ascertained that it was lighted. Now, anything like a brazier will, unless there is proper ventilation, give rise to carbonic oxide or carbon monoxide gas, which is always present in the products of combustion, often to the extent of from five to ten per cent. A very slight quantity of this gas, insufficient even to cause an odour in a room, will give a severe headache, and a case is recorded where a whole family in Glasgow was poisoned without knowing it by the escape of this gas. A little over one per cent of it in the atmosphere is fatal, if breathed for any length of time. You know, it is a product of combustion, and is very deadly—it is the much-dreaded white damp or afterdamp of a mine explosion.

"I'm going to tell you a secret which I have not given out to the press yet. I tried an experiment in a closed room today, lighting the brazier. Some distance from it I placed a cat confined in a cage so it could not escape. In an hour and a half the cat was asphyxiated."

The coroner concluded with an air of triumph that quite squelched the district attorney.

Kennedy was all attention. "Have you preserved samples of the blood of Mr. Templeton and Miss Wainwright?" he asked.

"Certainly. I have them in my office."

The coroner, who was also a local physician, led us back into his private office.

"And the cat?" added Craig.

Doctor Nott produced it in a covered basket.

Quickly Kennedy drew off a little of the blood of the cat and held it up to the light along with the human samples. The difference was apparent.

"You see," he explained, "carbon monoxide combines firmly with the blood, destroying the red colouring matter of the red corpuscles. No, Doctor, I'm afraid it wasn't carbonic oxide that killed the lovers, although it certainly killed the cat."

Doctor Nott was crestfallen, but still unconvinced. "If my whole medical reputation were at stake," he repeated, "I should still be compelled to swear to asphyxia. I've seen it too often, to make a mistake. Carbonic oxide or not, Templeton and Miss Wainwright were asphyxiated."

It was now Whitney's chance to air his theory.

"I have always inclined toward the cyanide-of-potassium theory, either that it was administered in a drink or perhaps injected by a needle," he said. "One of the chemists has reported that there was a possibility of slight traces of cyanide in the mouths."

"If it had been cyanide," replied Craig, looking reflectively at the two jars before him on the table, "these blood specimens would be blue in colour and clotted. But they are not. Then, too, there is a substance in the saliva which is used in the process of digestion. It gives a reaction which might very easily be mistaken for a slight trace of cyanide. I think that explains what the chemist discovered; no more, no less. The cyanide theory does not fit."

Is it Nux Vomica?

"ONE chemist hinted at nux vomica," volunteered the coroner. "He said it wasn't nux vomica, but that the blood test showed something very much like it. Oh, we've looked for morphine chloroform, ether, all the ordinary poisons, besides some of the little known alkaloids. Believe me, Professor Kennedy, it was asphyxia." I could tell by the look that crossed Kennedy's face that at last a ray of light had pierced the darkness. "Have you any spirits of turpentine in the office?" he asked.

The coroner shook his head and took a step toward the telephone as if to call the drug-store in town.

"Or ether?" interrupted Craig. "Ether will do."

"Oh, yes, plenty of ether."

Craig poured a little of one of the blood samples from the jar into a tube and added a few drops of ether. A cloudy dark precipitate formed. He smiled quietly and said, half to himself, "I thought so."

"What is it?" asked the coroner eagerly. "Nux vomica?"

Craig shook his head as he stared at the black precipitate. "You were perfectly right about the asphyxiation, Doctor," he remarked slowly, "but wrong as to the cause. It wasn't carbon monoxide or illuminating-gas. And you, Mr. Whitney, were right about the poison, too. Only it is a poison neither of you ever heard of."

"What is it?" we asked simultaneously.

"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. Vanderdyke 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 Vanderdyke'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 Vanderdyke 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 competition, and on the strength of that story she has been raking in the money right and left. I don't know Vanderdyke, never heard of him before, but no doubt he has some equally interesting game."

An Investigation

"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 Vanderdyke'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.

Vanderdyke 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, Vanderdyke 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."

Mrs. Ralston

I SAID nothing, but wondered how he could pass 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 Vanderdyke 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 Vanderdyke took the title rôle.

"Oh, yes, she and Vanderdyke 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 Vanderdyke either, and here they are, Vanderdyke 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.

Craig Recapitulates

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.

Poison

"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."

What Is It?

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 color 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 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?

"Woorali, or curare," said Craig slowly, "is the well-known poison with which the South American Indians of the upper Orinoco tip their arrows. Its principal ingredient is derived from the Strychnos toxifera tree, which yields also the drug nux vomica."

A great light dawned on me. I turned quickly to where Vanderdyke was sitting next to Mrs. Ralston, and a little behind her. His stony stare and laboured breathing told me that he had read the purport of Kennedy's actions.

"For God's sake, Craig," I gasped. "An emetic, quick—Vanderdyke."

A trace of a smile flitted over Vanderdyke's features, as much as to say that he was beyond our interference.

"Vanderdyke," said Craig, with what seemed to me a brutal calmness, "then it was you who were the visitor who last saw Laura Wainwright and John Templeton alive. Whether you shot a dart at them I do not know. But you are the murderer."

Vanderdyke raised his hand as if to assent. It fell back limp, and I noted the ring of the bluest lapis lazuli.

The Murderer

MRS. RALSTON threw herself toward him. "Will you not do something? Is there no antidote? Don't let him die!" she cried.

"You are the murderer," repeated Kennedy, as if demanding a final answer.

Again the hand moved in confession, and he feebly moved the finger on which shone the ring.

Our attention was centred on Vanderdyke. Mrs. Ralston, unobserved, went to the table and picked up the gourd. Before O'Connor could stop her she had rubbed her tongue on the black substance inside. It was only a little bit, for O'Connor quickly dashed it from her lips and threw the gourd through the window, smashing the glass.

"Kennedy," he shouted frantically, "Mrs. Ralston has swallowed some of it."

Kennedy seemed so intent on Vanderdyke that I had to repeat the remark.

Without looking up, he said: "Oh, one can swallow it—it's strange, but it is comparatively inert if swallowed even in a pretty good-sized quantity. I doubt if Mrs. Ralston ever heard of it before except by hearsay. If she had, she'd have scratched herself with it instead of swallowing it."

If Craig had been indifferent to the emergency of Vanderdyke before, he was all action now that the confession had been made. In an instant Vanderdyke was stretched on the floor and Craig had taken out the apparatus I had seen during the afternoon.

"I am prepared for this," he exclaimed quickly. "Here is the apparatus for artificial respiration. Nott, hold that rubber funnel over his nose, and start the oxygen from the tank. Pull his tongue forward so it won't fall down his throat and choke him. I'll work his arms. Walter, make a tourniquet of your handkerchief and put it tightly on the muscles of his left arm. That may keep some of the poison in his arm from spreading into the rest of his body. This is the only antidote known—artificial respiration."

Kennedy was working feverishly, going through the motions of first aid to a drowned man. Mrs. Ralston was on her knees beside Vanderdyke, kissing his hands and forehead whenever Kennedy stopped for a minute, and crying softly.

"Schuyler, poor boy, I wonder how you could have done it. I was with him that day. We rode up in his car, and as we passed through Williston he said he would stop a minute and wish Templeton luck. I didn't think it strange, for he said he had nothing any longer against Laura Wainwright, and Templeton only did his duty as a lawyer against us. I forgave John for prosecuting us, but Schuyler didn't, after all. Oh, my poor boy, why did you do it? We could have gone somewhere else and started all over again—it wouldn't have been the first time."

Lapis Lazuli

At last came the flutter of an eyelid and a voluntary breath or two. Vanderdyke seemed to realise where he was. With a last supreme effort he raised his hand and drew it slowly across his face. Then he fell back, exhausted by the effort.

But he had at last put himself beyond the reach of the law. There was no tourniquet that would confine the poison now in the scratch across his face. Back of those lack-lustre eyes he heard and knew, but could not move or speak. His voice was gone, his limbs, his face, his chest, and, last, his eyes. I wondered if it were possible to conceive a more dreadful torture than that endured by a mind which so witnessed the dying of one organ after another of its own body, shut up, as it were, in the fulness of life, within a corpse.

I looked in bewilderment at the scratch on his face. "How did he do it?" I asked.

Carefully Craig drew off the azure ring and examined it. In that part which surrounded the blue lapis lazuli, he indicated a hollow point, concealed. It worked with a spring and communicated with a little receptacle behind, in such a way that the murderer could give the fatal scratch while shaking hands with his victim.

I shuddered, for my hand had once been clasped by the one wearing that poison ring, which had sent Templeton, and his fiancee and now Vanderdyke himself, to their deaths.