attached underneath to hold a small spirit lamp. By the heat of the flame, formalin gas, one of the deadliest germ-killers known, was given off.

Macgregor opened the can, lighted the pale spirit flame, and set the apparatus on a rude shelf that happened to be just inside the hut. They forced the door shut again, and sealed it by throwing water against it, for the water promptly froze. It was not necessary to close the chimney, for the germicidal gas is heavier than air, and fills a room exactly as water fills a tank.

As it would take the disinfectant ten or twelve hours to do its work, they hastened to construct a camp, for it was growing dark. It was a rather melancholy evening. The nearness of the cabin, with its sinister associations, affected them disagreeably; and, moreover, they were all tired with the day's tramp, and chagrined and mortified at having come, as Peter said, "on a fool's errand." After all their glittering hopes, there was nothing now for them except a week's snowshoe tramp back to Waverley, with barely enough provisions to see them through.

Still they were curious about the cabin, and before breakfast the next morning they burst open the ice-sealed door. A suffocating odor issued forth, so powerful that they staggered back.

"Good gracious!" gasped Fred, after a spasm of coughing. "It must certainly be safe after that!"

They found it impossible to go in until the gas had cleared away, and so, leaving the door wide open, they returned to breakfast. Afterward they idled about, trying to kill time; it was afternoon before they could venture inside the cabin for more than a moment.

It was disagreeable even then, for the whole interior was filled with the heavy, suffocating odor. They coughed, and their eyes watered, but they managed to endure it.

As they had seen, the contents of the place were all topsy-turvy. The furniture consisted solely of a rough table of split planks, and a couple of rough seats. A heap of rusty, brown sapin in a corner, covered with a torn blanket, represented a bed—possibly the one in which the trapper had died.

In one corner stood a double-barreled shotgun, still loaded. Three pairs of snowshoes were thrust under the rafters; several worn moccasins lay on the floor, along with nearly a dozen steel traps, a bundle of furs, some of which were valuable, a camp kettle, an axe, strips of hide, dry bones, a blanket, fishing-tackle—an unspeakable litter of things, some worthless, some to men in a wilderness precious as gold.

The last occupants had plainly left in such a desperate hurry that they had abandoned most of their possessions. Why had they done it? The boys could not guess.

The heavy formalin fumes rose and choked them as they poked over the rubbish. But they found nothing to show the fate of the prospector and the surviving half-breed, or even to tell them whether this was really the cabin they were seeking.

"Throw this rubbish into the fireplace," said Macgregor. "Burning is the best thing for it, and the fire will ventilate the place. There's no danger of germs on the metal things."

"These furs are worth something," said Fred, who had been looking them over. "There are a dozen or so of mink and marten—enough to pay the expenses of the trip."

They laid the furs aside, and cramming the rest of the litter into the snowy fireplace, with the dead balsam boughs, set it afire. In the red blaze the hut assumed an unexpectedly homelike aspect.

"Not such a bad place for the winter, after all," Maurice remarked, casting his eye about. "I shouldn't mind spending a month trapping here myself. What if we did, fellows, eh? Here are plenty of traps, and we might clear three or four hundred dollars, with a little luck."

"Here's something new," interrupted Peter, who had been grubbing about in a corner.

He came forward with a woodsman's "turkey" in his hands—a heavy canvas knapsack, much stained and battered, and rather heavy.

"Something in this," he continued, trying the rusty buckles. "Why, what's the matter, Fred?"

For Fred had uttered a sudden cry, and they saw his face turn deathly white. He snatched the sack, tore it open, and shook it out.

A number of pieces of rock fell to the floor, a couple of geologist's hammers, a pair of socks, and a couple of small, oilcloth-covered notebooks.

On these Fred pounced, and opened them. They were full of penciled notes.

"They're his!" the boy exclaimed wildly. "They're Horace's notebooks! I knew his turkey. Horace was here. Don't you see? He was the sick man!"

For a minute his companions, hardly comprehending, looked on in amazement. Then Macgregor took one of the books from his hand. On the inside of the cover was plainly written, "Horace Osborne, Toronto."

"It's true!" he muttered. "It must really have been Horace." Then, collecting his wits, he added, "But he must be all right, since he's gone away."

"No!" Fred cried. "He'd never have gone away leaving his notes and specimens. It was his whole summer's work. He'd have thrown away anything else. He must be dead."

"He was vaccinated. He's sure not to have died of smallpox," Peter urged.

Fred had collapsed on the mud floor, holding the "turkey," and fairly crying.

"He had the diamonds on him. That half-breed may have murdered him, and then fled in a hurry. Things look like it," said Maurice aside to Peter.

"Yes, but then Horace's body would be here," the Scotchman returned. "I don't understand it."

"They can't have both died, either, or they'd both be here. So they must both have gone. But no trapper would have left these valuable pelts, any more than Horace would have left his notes."

"There's something mysterious here," said Fred, getting up resolutely, and wiping the tears from his eyes. "Horace has been here. Something's happened to him, and we've got to find out what it is."

"And we'll find out—if it takes all winter!" Macgregor assured him.

They searched the hut afresh, but found no clues. They now regretted having burned the heap of rubbish, which perhaps had contained something to throw light on the problem.

During the rest of that afternoon they searched and searched again throughout the cabin, and prowled about its neighborhood. They dug into the snowdrifts, poked into the brushwood, scouted into the forest in the faint hope of finding something that would cast light on Horace's fate. All they found was the trapper's birch canoe, laid up ashore, and buried in snow.

At dusk they got supper, and ate it in a rather gloomy silence.

"We've nothing to go on," said Macgregor. "I can't believe that Horace is dead, though, and we must stay on the spot till we know something more definite."

"Of course we must," Maurice agreed.

"I shouldn't have asked it of you, boys," said Fred. "I'd made up my mind to stay, though, till I found out something certain—and it would have been mighty lonely."

"Nonsense! Do you think we'd have left you?" Maurice exclaimed. "Aren't we all Horace's friends? The only thing I'm thinking of is the grub. We have barely enough for a week more."

"What of that?" said Peter. "We have rifles, haven't we? The woods ought to be full of deer—plenty of partridges and small game, anyway. We must make a regular business of hunting till we get enough meat for a week, and we must economize, of course, on our bread and canned stuff. Then there are sure to be whitefish or trout in the nearest lake, and we can fish through the ice. Lucky the Indians left their hooks and lines. And we can trap, too."

"Boys," cried Fred, "you're both bricks. You're solid gold—" A choke in his voice stopped him.

"A pair of gold bricks!" laughed Maurice, with a suspicious huskiness in his own tones.

But the thing was settled.

It turned colder that night, and the next day dawned with blustering snow flurries. Their open camp was far from comfortable, and with some reluctance they moved into the