OF THE MINERAL WORK.

For when they are ground very finely, the better part always goes first into a red powder, leaving behind the ignoble, coarser, and harder part, which contains little or nothing. Even if they are ground somewhat coarsely and passed through a very fine sieve, the finer part passes the sieve like a red powder, leaving the useless part in the sieve like a white powder, which is to be thrown away. Even if some redness still appears in these, they must be ground again in a mortar, and again the better part will go into a red powder, leaving the ignoble, coarser white part in the sieve, which is therefore to be thrown away. It must be observed, however, that not all and every flint is separable by the benefit of grinding; for some, when ground, retain one and the same color everywhere without any separation of the better parts. These must be ground very finely in their whole substance and extracted. Those that are separable, however, are extracted more easily, because all the gold contained in one pound can generally be collected from three or four ounces ground very finely and separated in the aforementioned manner, so that there is no need to extract the whole stone, nor to consume such a quantity of spirit of salt. Sand and clay, however, do not need such preparation, but are extracted by the pouring on of spirit of salt without prior preparation.

℞. Afterward, take 2, 3, 4, or 6 pounds of the flints prepared and separated in the aforementioned manner, upon which, in a whole (undivided) glass cucurbit vessel for distillation, pour spirit of salt to a height of 3 or 4 transverse fingers, and place it in hot sand or in a water bath, so that the spirit of salt therein may be well heated, and the gold