poles of a large battery, as he proceeded: "Every day the medical detective plays a more and more important part in the detection of crime, and I might say that, except in the case of crime complicated by a lunacy plea, his work has earned the respect of the courts and of detectives, while in the case of insanity the discredit is the fault rather of the law itself. The ways in which the doctor can be of use in untangling the facts in many forms of crime have become so numerous that the profession of medical detective may almost be called a specialty."
Kennedy repeated what he had already told me about electrolysis, then placed between the poles of the battery a large piece of raw beef.
He covered the negative electrode with blotting paper and soaked it in a beaker near at hand.
"This solution," he explained, "is composed of potassium iodide. In this other beaker I have a mixture of ordinary starch."
He soaked the positive electrode in the starch and then jammed the two against the soft red meat. Then he applied the current.
A few moments later he withdrew the positive electrode. Both it and the meat under it were blue!
"What has happened?" he asked. "The iodine ions have actually passed through the beef to the positive pole and the paper on the electrode. Here we have starch iodide."
It was a startling idea, this of the introduction of a substance by electrolysis.
"I may say," he resumed, "that the medical view of electricity is changing, due in large measure to the genius of the Frenchman, Dr. Leduc. The body, we know, is composed largely of water, with salts of soda and potash. It is an excellent electrolyte. Yet most doctors regard the introduction of substances by the electric current as insignificant or nonexistent. But on the contrary the introduction of drugs by electrolysis is regular and far from being insignificant may very easily bring about death.
"That action," he went on, looking from one of us to another, "may be therapeutic, as in the cure for lead poisoning by removing the lead, or it may be toxic--as in the case of actually introducing such a poison as strychnine into the body by the same forces that will remove the lead."
He paused a moment, to enforce the point which had already been suggested. I glanced about hastily. If anyone in his little audience was guilty, no one betrayed it, for all were following him, fascinated. Yet in the wildly throbbing brain of some one of them the guilty knowledge must be seared indelibly. Would the mere accusation be enough to dissociate the truth from, that brain or would Kennedy have to resort to other means?
"Some one," he went on, in a low, tense voice, leaning forward, "some one who knew this effect placed strychnine salts on one of the electrodes of the bath which Owen Minturn was to use."
He did not pause. Evidently he was planning to let the force of his exposure be cumulative, until from its sheer momentum it carried everything before it.
"Walter," he ordered quickly. "Lend me a hand."
Together we moved the laboratory table as he directed.
There, in the floor, concealed by the shadow, he had placed the same apparatus which I had seen him bury in the path between the Pearcy and Minturn estates at Stratfield.
We scarcely breathed.
"This," he explained rapidly, "is what is known as a kinograph-- the invention of Professor HeleShaw of London. It enables me to identify a person by his or her walk. Each of you as you entered this room has passed over this apparatus and has left a different mark on the paper which registers."
For a moment he stopped, as if gathering strength for the final assault.
"Until late this afternoon I had this kinograph secreted at a certain place in Stratfield. Some one had tampered with the leaden water pipes and the electric light cable. Fearful that the lead poisoning brought on by electrolysis might not produce its result in the intended victim, that person took advantage of the new discoveries in electrolysis to complete that work by introducing the deadly strychnine during the very process of cure of the lead poisoning."
He slapped down a copy of a newspaper. "In the news this morning I told just enough of what I had discovered and colored it in such a way that I was sure I would arouse apprehension. I did it because I wanted to make the criminal revisit the real scene of the crime. There was a double motive now--to remove the evidence and to check the spread of the poisoning."
He reached over, tore off the paper with a quick, decisive motion, and laid it beside another strip, a little discolored by moisture, as though the damp earth had touched it.
"That person, alarmed lest something in the cleverly laid plot, might be discovered, went to a certain spot to remove the traces of the diabolical work which were hidden there. My kinograph shows the footsteps, shows as plainly as if I had been present, the exact person who tried to obliterate the evidence,"
An ashen pallor seemed to spread over the face of Miss Pearcy, as Kennedy shot out the words.
"That person," he emphasized, "had planned to put out of the way one who had brought disgrace on the Pearcy family. It was an act of private justice."
Mrs. Pearcy could stand the strain no longer. She had broken down and was weeping incoherently. I strained my ears to catch what she was murmuring. It was Minturn's name, not Gunther's, that was on her lips.
"But," cried Kennedy, raising an accusatory finger from the kinograph tracing and pointing it like the finger of Fate itself, "but the self-appointed avenger forgot that the leaden water pipe was common to the two houses. Old Mr. Pearcy, the wronged, died first. Isabel has guessed the family skeleton--has tried hard to shield you, but, Warner Pearcy, you are the murderer!"
Chapter XXXI
The Eugenic Bride
Scandal, such as that which Kennedy unearthed in this Pearcy case, was never much to his liking, yet he seemed destined, about this period of his career, to have a good deal of it.
We had scarcely finished with the indictment that followed the arrest of young Pearcy, when we were confronted by a situation which was as unique as it was intensely modern.
"There's absolutely no insanity in Eugenia's family," I heard a young man remark to Kennedy, as my key turned in the lock of the laboratory door.
For a moment I hesitated about breaking in on a confidential conference, then reflected that, as they had probably already heard me at the lock, I had better go in and excuse myself.
As I swung the door open, I saw a young man pacing up and down the laboratory nervously, too preoccupied even to notice the slight noise I had made.
He paused in his nervous walk and faced Kennedy, his back to me.
"Kennedy," he said huskily, "I wouldn't care if there was insanity in her family--for, my God!--the tragedy of it all now--I love her!"
He turned, following Kennedy's eyes in my direction, and I saw on his face the most haggard, haunting look of anxiety that I had ever seen on a young person.
Instantly I recognized from the pictures I had seen in the newspapers young Quincy Atherton, the last of this famous line of the family, who had attracted a great deal of attention several months previously by what the newspapers had called his search through society for a "eugenics bride," to infuse new blood into the Atherton stock.
"You need have no fear that Mr. Jameson will be like the other newspaper men," reassured Craig, as he introduced us, mindful of the prejudice which the unpleasant notoriety of Atherton's marriage had already engendered in his mind.
I recalled that when I had first heard of Atherton's "eugenic marriage," I had instinctively felt a prejudice against the very idea of such cold, calculating, materialistic, scientific mating, as if one of the last fixed points were disappearing in the chaos of the social and sex upheaval.
Now, I saw that one great fact