"But how does the gold get into it, uncle?"
"There is what is called an affinity between quicksilver and gold. The moment gold touches quicksilver it is absorbed by it, just as a drop of water is taken up by a lump of salt. It thickens the quicksilver, and as it is squeezed through the leather the quicksilver is as it were strained out, and what remains behind becomes thicker and thicker, until, as you see, it is almost solid. It is no good to use more pressure, for if you do a certain amount of the gold would be squeezed through the leather. You see, as the stuff in the cradle is shaken, the gold being heavier than the sand finds its way down to the bottom, and every particle that comes in contact with the quicksilver is swallowed up by it."
"And how do you get the quicksilver out of those lumps?"
"We put them in one of those clay crucibles you saw, with a pinch of borax, cover them up, and put them in a heap of glowing embers. That evaporates the quicksilver, and leaves the gold behind in the shape of a button." This was done that evening, and when the buttons were placed in the scales they just turned the two-pound weight.
"Well, boys, that is good enough for anything," Harry said. "That, with the dust, makes a pound a day, which is as good as the very best stuff in the early days of California."
They worked steadily for the next seven weeks. Contrary to their expectations the gravel was but little richer lower down than they had found it at the end of the first wash-up, but continued about equally good, and the result averaged about a pound weight of gold a day. This was put into little bags of deer-skin, each containing five pounds' weight, and these bags were distributed among the saddle-bags, so that in case of sudden disturbance there would be no risk of their being left behind. The Indians took it by turns to hunt; at other times they remained on guard in camp, Tom only staying when one of them was away. One day when the mining party stopped work, and sat down to eat some bread and cold meat,--which they had from the first brought up, so as to save them the loss of time entailed by going to the camp and back,--the report of a gun came upon their ears. All started to their feet and seized their rifles, and then stood listening intently. A minute later two more shots were heard at close intervals.