"No, no; I want you to come—I should like you both to come—and put a stop at once to this dreadful business. Consider! It's a matter of life and death. You won't refuse! I beg you not to refuse me your help in these terrible circumstances."
"Well," said Thorndyke, as his assistant reappeared, "let us first see what the test has to tell us."
Polton advanced to the table, on which he deposited a small flask, the contents of which were in a state of brisk effervescence, a bottle labelled "calcium hypochlorite," and a white porcelain tile. The flask was fitted with a safety-funnel and a glass tube drawn out to a fine jet, to which Polton cautiously applied a lighted match. Instantly there sprang from the jet a tiny, pale violet flame. Thorndyke now took the tile, and held it in the flame for a few seconds, when the appearance of the surface remained unchanged save for a small circle of condensed moisture. His next proceeding was to thin the arrowroot with distilled water until it was quite fluid, and then pour a small quantity into the funnel. It ran slowly down the tube into the flask, with the bubbling contents of which it became speedily mixed. Almost immediately a change began to appear in the character of the flame, which from a pale violet turned gradually to a sickly blue, while above it hung a faint cloud of white smoke. Once more Thorndyke held the tile above the jet, but this time, no sooner had the pallid flame touched the cold surface of the porcelain, than there appeared on the latter a glistening black stain.
"That is pretty conclusive," observed Thorndyke, lifting the stopper out of the reagent bottle, "but we will apply the final test." He dropped a few drops of the hypochlorite solution on to the tile, and immediately the black stain faded away and vanished. "We can now answer your question, Mr. Barton," said he, replacing the stopper as he turned to our client. "The specimen that you brought us certainly contains arsenic, and in very considerable quantities."
"Then," exclaimed Mr. Barton, starting from his chair, "you will come and help me to rescue my brother from this dreadful peril. Don't refuse me, Dr. Thorndyke, for mercy's sake, don't refuse."
Thorndyke reflected for a moment.
"Before we decide," said he, "we must see what engagements we have."
With a quick, significant glance at me, he walked into the office, whither I followed in some bewilderment, for I knew that we had no engagements for the evening.
"Now, Jervis," said Thorndyke, as he closed the office door, "what are we to do?"
"We must go, I suppose," I replied. "It seems a pretty urgent case."
"It does," he agreed. "Of course, the man may be telling the truth, after all."
"You don't think he is, then?"
"No. It is a plausible tale, but there is too much arsenic in that arrowroot. Still, I think I ought to go. It is an ordinary professional risk. But there is no reason why you should put your head into the noose."
"Thank you," said I, somewhat huffily. "I don't see what risk there is, but if any exists I claim the right to share it."
"Very well," he answered with a smile, "we will both go. I think we can take care of ourselves."
He re-entered the sitting-room, and announced his decision to Mr. Barton, whose relief and gratitude were quite pathetic.
"But," said Thorndyke, "you have not yet told us where your brother lives."
"Rexford," was the reply—"Rexford, in Essex. It is an out-of-the-way place, but if we catch the seven-fifteen train from Liverpool Street, we shall be there in an hour and a half."
"And as to the return? You know the trains, I suppose?"
"Oh yes," replied our client; "I will see that you don't miss your train back."
"Then I will be with you in a minute," said Thorndyke; and, taking the still-bubbling flask, he retired to the laboratory, whence he returned in a few minutes carrying his hat and overcoat.
The cab which had brought our client was still waiting, and we were soon rattling through the streets towards the station, where we arrived in time to furnish ourselves with dinner-baskets and select our compartment at leisure.
During the early part of the journey our companion was in excellent spirits. He despatched the cold fowl from the basket and quaffed the rather indifferent claret with as much relish as if he had not had a single relation in the world, and after dinner he became genial to the verge of hilarity. But, as time went on, there crept into his manner a certain anxious restlessness. He became silent and preoccupied, and several times furtively consulted his watch.
"The train is confoundedly late!" he exclaimed irritably. "Seven minutes behind time already!"
"A few minutes more or less are not of much consequence," said Thorndyke.
"No, of course not; but still—Ah, thank Heaven, here we are!"
He thrust his head out of the off-side window, and gazed eagerly down the line; then, leaping to his feet, he bustled out on to the platform while the train was still moving.
Even as we alighted a warning bell rang furiously on the up-platform, and as Mr. Barton hurried us through the empty booking-office to the outside of the station, the rumble of the approaching train could be heard above the noise made by our own train moving off.
"My carriage doesn't seem to have arrived yet," exclaimed Mr. Barton, looking anxiously up the station approach. "If you will wait here a moment, I will go and make inquiries."
He darted back into the booking-office and through it on to the platform, just as the up-train roared into the station. Thorndyke followed him with quick but stealthy steps, and, peering out of the booking-office door, watched his proceedings; then he turned and beckoned to me.
"There he goes," said he, pointing to an iron footbridge that spanned the line; and, as I looked, I saw, clearly defined against the dim night sky, a flying figure racing towards the "up" side.
It was hardly two-thirds across when the guard's whistle sang out its shrill warning.
"Quick, Jervis," exclaimed Thorndyke; "she's off!"
He leaped down on to the line, whither I followed instantly, and, crossing the rails, we clambered up together on to the foot-board opposite an empty first-class compartment. Thorndyke's magazine knife, containing, among other implements, a railway-key, was already in his hand. The door was speedily unlocked, and, as we entered, Thorndyke ran through and looked out on to the platform.
"Just in time!" he exclaimed. "He is in one of the forward compartments."
He relocked the door, and, seating himself, proceeded to fill his pipe.
"And now," said I, as the train moved out of the station, "perhaps you will explain this little comedy."
"With pleasure," he replied, "if it needs any explanation. But you can hardly have forgotten Mr. James's flattering remarks in his report of the Greek Street incident, clearly giving the impression that the mysterious document was in my possession. When I read that, I knew I must look out for some attempt to recover it, though I hardly expected such promptness. Still, when Mr. Barton called without credentials or appointment, I viewed him with some suspicion. That suspicion deepened when he wanted us both to come. It deepened further when I found an impossible quantity of arsenic in his sample, and it gave place to certainty when, having allowed him to select the trains by which we were to travel, I went up to the laboratory and examined the time-table; for I then found that the last train for London left Rexford ten minutes after we were due to arrive. Obviously this was a plan to get us both safely out of the way while he and some of his friends ransacked our chambers for the missing document."
"I see; and that accounts for his extraordinary anxiety at the lateness of the train. But why did you come, if you knew it was a 'plant'?"
"My dear fellow," said Thorndyke, "I never miss an interesting experience if I can help it. There are possibilities in this, too, don't you see?"