Dead Broke Dan had been gone a week from Golden Flat on his errand for stores, and in this time the extent of the "pay gravel" in the different mines had been fairly accurately estimated. Developments all along the line proved the existence of a rich but limited layer of the gold-carrying wash from end to end of the workings. At the Golden Promise mine the auriferous deposit, as had been anticipated, had occurred in a considerably deeper drift than in any of the others, the reason of course, being in accordance with Bob's theory that the sudden uprise of the old channel would cause an accumulation of the wash directly on the incline, and so it had happened; the thickness of the stratum was here nearly four feet, or almost twice that in all the other claims. Beyond this, however, no direct trace of the ancient waterway could be discovered; a broad lagoon-like mass of the tantalizing clay which had so mystified Emu Bill intervened, sparkling and gleaming in its deceptive beauty until raised to the surface when it unfailingly relapsed into its muddy, sordid state, to the disgust of all beholders. This odd formation was found to underlie the genuine gold-carrying cement in all the shafts, and its presence provided a topic for much vituperative language.
Until the various chemicals arrived Bob was unable to make any analysis of the much-abused deposit, but he was never tired of examining samples of it, powdering them up and applying the fire test in the hope that whatever refractory gas or element was present, and binding the gold in an invisible state, might be driven off. He never cared to say much concerning the results of these experiments, but that he received undoubted satisfaction from his labours was very evident. He was engaged roasting some of the fine grains of the clay in a crucible when Mackay entered the tent on this morning in search of a pick-handle he had mislaid.
"Well, Bob," said he, "an' are ye gettin' any nearer a solution to that mystery of Nature?"
Bob silently pointed to the crucible on the small Primus stove from which dense yellow fumes were issuing.
"Smell that," he said.
Mackay sniffed right heartily, and nearly choked in consequence.
"An' what sort o' a perfume do ye call that?" he demanded, when he had regained his composure.
"Chlorine," smilingly returned the chemist. "The clay is soaked in it, and any text-book will tell you that chlorine has a great affinity for gold."
Mackay became interested at once. "Let me hear your line o' argument, Bob," he grunted. "This is a matter o' vera considerable importance, an' I'll be the last to discourage ye in your efforts."