"Crushing is unnecessary with the process," said he. "The ore will dissolve in the vat; indeed, it would reduce itself to slime in ordinary water if puddled occasionally, or it would disintegrate very rapidly on exposure to the sun, though that plan would be rather risky, owing to the excessive oxidization which might take place. But in every case the slimes would remain unaffected by battery treatment, and for this one reason which was the basis of all my experiments—the clayey material is a chemical compound, and not a mechanical mixture like ordinary alluvial wash, consequently it will only answer to chemical treatment."
"But," interjected Jack, "there is most likely free gold in the stuff as well as the—the other kind."
"Probably enough, but, as you see, even that cannot be saved by ordinary methods; the soapy nature of the composition, I imagine, is the cause. Oily globules will form around the gold particles and insulate them, so that the mercury on the plates never really gets a chance to exert its power."
Apparently Bob's studies had been complete and exhaustive; his knowledge of his subject impressed Mackay deeply.
"I can follow your reasoning there, Bob," said he, "for the overflow even of the small vat in the tent was more like engine-grease than anything else, an' I can testify that the residue I washed in the pan was a pure and free sand."
The Shadow here broke in on their conversation; he had been away at the other end of the Flat on a tour of investigation, for it was known that several shafts were nearing the dreaded bottom.
"The whole circus is goin' to break up," he announced sorrowfully. "There's nothin' but Emu Bill's miradgy stuff down there, an' the miners are thinkin' o' giving it best."
The Shadow was not aware that Bob's experiment had proved successful; Emu Bill alone of the original group had been informed, and he certainly had not spoken of it.
"I'll go down and advise them to hang on for a bit," said Mackay, after some deliberation. "An' Bob, you can tell the Shadow anything you like, provided he promises to keep his mouth shut."
"Say boss, does I deserve that?" complained the injured youth, reproachfully.