Jack laughed. “Three or four hundred is nearer the mark, I expect,” said he. “Just lift it.”
The tin plate was standing in the gold-pan, and when I went to take it up I thought for the moment they must be stuck together; it was so much heavier than I had anticipated.
“Why,” said I, “it must weigh two pounds.”
“Just about,” replied Jack; “tin plate, black sand, and all; and so I make a guess that the gold is worth four hundred dollars or so, reckoning gold at eighteen dollars the Troy ounce, as they do here.”
It seemed impossible; such a little heap.
“But, Jack,” said I, as the discomforting thought suddenly occurred to me, “suppose it should not be gold at all. How do you know it isn’t copper?”
“Oh, there’s no mistaking gold when you’ve once seen it,” replied Jack. “This stuff is gold, all right; I have no doubt about it at all. But still, if you like, I’ll test it and make certain, just to set your mind at rest, and to satisfy you that we haven’t put in ten hours’ hard labour to-day on a wild-goose chase.”
Stepping over to the baggage, Jack hunted out an old cigar-box in which were a tiny porcelain cup and a little glass-stoppered bottle, the latter containing nitric acid. Pouring a little of the acid into the cup, Jack dropped a scrap of the gold into it, and raking some hot ashes from the fire he set the cup upon them. Soon the acid began to simmer, and for five minutes it continued to do so, without, however, producing the slightest effect upon the metal; nor did the liquid itself change colour.
“It is gold, all right,” said Jack, removing the cup. “Now, I’ll just show you what would have happened if it had been copper.”
With his knife he cut a shaving from a copper rivet, dropped the fragment into the cup, and replaced the cup upon the ashes. In an instant the acid attacked the copper, and pretty soon it had eaten it all up, turning itself a beautiful green colour in the process.