"You have been on a bust," he said with a smile as if the remark of a few minutes before were still fresh. "Only it was a laughing gas jag--nitrous oxide."
"Nitrous oxide?" I repeated. "How--what do you mean?"
"I mean simply that a test of your blood shows that you were poisoned by nitrous oxide gas. You remember the sample of blood which I squeezed from your thumb? I took it because I knew that a gas--and it has proved to be nitrous oxide--is absorbed through the lungs into the circulation and its presence can be told for a considerable period after administration."
He paused a moment, then went on: "To be specific in this case I found by microscopic examination that the number of corpuscles in your blood was vastly above the normal, something like between seven and eight million to a drop that should have had somewhat more than only half that number. You were poisoned by gas that--"
"Yes," I interrupted, "but how, with all the doors locked?"
"I was coming to that," he said quietly, picking up the lock and looking at it thoughtfully.
He had already placed it in a porcelain basin, and in this basin he had poured some liquids. Then he pa.s.sed the liquids through a fine screen and at last took up a tube containing some of the resulting liquid.
"I have already satisfied myself," he explained, "but for your benefit, seeing that you"re the chief sufferer, I"ll run over a part of the test. You saw the reaction which showed the gas a moment ago. I have proved chemically as well as microscopically that it is present in your blood. Now if I take this test-tube of liquid derived from my treatment of the lock and then test it as you saw me do with the other, isn"t that enough for you? See--it gives the same reaction."
It did, indeed, but my mind did not react with it.
"Nitrous oxide," he continued, "in contact with iron, leaves distinct traces of corrosion, discernible by chemical and microscopic tests quite as well as the marks it leaves in the human blood. Manifestly, if no one could have come in by the windows or doors, the gas must have been administered in some way without any one coming into the room. I found no traces of an intruder."
It was a tough one. Never much good at answering his conundrums when I was well, I could not even make a guess now.
"The key-hole, of course!" he explained. "I cut away the entire lock, and have submitted it to these tests which you see."
"I don"t see it all yet," I said.
"Some one came to our door in the night, after gaining entrance to the hall--not a difficult thing to do, we know. That person found our door locked, knew it would be locked, knew that I always locked it. Knowing that such was the case, this person came prepared, bringing perhaps, a tank of compressed nitrous oxide, certainly the materials for making the gas expeditiously."
I began to understand how it had been done.
"Through the keyhole," he resumed, "a stream of the gas was injected.
It soon rendered you unconscious, and that would have been all, if the person had been satisfied. A little bit would have been harmless enough. But the person was not satisfied. The intention was not to overcome, but to kill. The stream of gas was kept up until the room was full of it.
"Only my return saved you, for the gas was escaping very slowly. Even then, you had been under it so long that we had to resort to the wonderful little pulmotor after trying both the Sylvester and Schaefer methods and all other manual means to induce respiration. At any rate we managed to undo the work of this fiend."
I looked at him in surprise, I, who didn"t think I had an enemy in the world.
"But who could it have been?" I asked.
"We are pretty close to that criminal," was the only reply he would give, "providing we do not spread the net in sight of the quarry."
"Why should he have wanted to get me?" I repeated.
"Don"t flatter yourself," replied Craig. "He wanted me, too. There wasn"t any light in the laboratory last night. There was a light in our apartment. What more natural than to think that we were both there? You were caught in the trap intended for both of us."
I looked at him, startled. Surely this was a most desperate criminal.
To cover up one murder--perhaps two--he did not hesitate to attempt a third, a double murder. The attack had been really aimed at Kennedy. It had struck me alone. But it had miscarried and Craig had saved my life.
As I reflected bitterly, I had but one satisfaction. Wretched as I felt, I knew that it had spared Craig from slowing up on the case at just the time when he was needed.
The news of the attempt spread quickly, for it was a police case and got into the papers.
It was not half an hour after I reached the laboratory that the door was pushed open by Inez Mendoza, followed by a boy spilling with fruit and flowers like a cornucopia.
"I drove to the apartment," she cried, greatly excited and sympathetic, "but they told me you had gone out. Oh, I was glad to hear it. Then I knew it wasn"t so serious. For, somehow, I feel guilty about it. It never would have happened if you hadn"t met me."
"I"m sure it"s worth more than it cost," I replied gallantly.
She turned toward Kennedy. "I"m positively frightened," she exclaimed.
"First they direct their attacks against my father--then against me--now against you. What will it be next? Oh--it is that curse--it is that curse!"
"Never fear," encouraged Kennedy, "we"ll get you out--we"ll get all of us out, now, I should say. It"s just because they are so desperate that we have these things. As long as there is nothing to fear a criminal will lie low. When he gets scared he does things. And it"s when he does things that he begins to betray himself."
She shuddered. "I feel as though I was surrounded by enemies," she murmured. "It is as if an unseen evil power was watching over me all the time--and mocking me--striking down those I love and trust. Where will it end?"
Kennedy tried his best to soothe her, but it was evident that the attack on us could not have had more effect, if it had been levelled direct at her.
"Please, Senorita," he pleaded, "stand firm. We are going to win. Don"t give in. The Mendozas are not the kind to stop defeated."
She looked at him, her eyes filled with tears.
"It was my father"s way," she choked back her emotion. "How could you, a stranger, know?"
"I didn"t know," returned Kennedy. "I gathered it from his face. It is also his daughter"s way."
"Yes," she said, straightening up and the fire flashing from her eyes, "we are a proud, old, unbending race. Good-bye. I must not interrupt your work any longer. We are also a race that never forgets a friend."
A moment later she was gone.
"A wonderful woman," repeated Kennedy absently.
Then he turned again to his table of chemicals.
The telephone had begun to tinkle almost continuously by this time, as one after another of our friends called us up to know how we were getting on and be a.s.sured of our safety. In fact I didn"t know that it was possible to resuscitate so many of them with a pulmotor.
"By George, I"m glad it wasn"t any more serious," came Norton"s voice from the doorway a moment later. "I didn"t see a paper this morning.
The curator of the Museum just told me. How did it happen?"
Kennedy tried to pa.s.s it off lightly, and I did the same, for as I was up longer I really did feel better.
Norton shook his head gravely, however.
"No," he said, "there were four of us got warnings. They are a desperate, revengeful people."
I looked at him quickly. Did he mean the de Moches?