Sometimes the miner will be troubled with impure gold after retorting. If the metal is very dark this shade may come from the presence of large amounts of iron. A heavy proportion of mineral salts, such as chloride of calcium (CaCl), sodium (NaCl), and magnesium (NgCl{2}), in the battery water sometimes accounts for this. In such cases amalgamate, retort, pulverize and roast. Then smelt with borax, the iron passing into the slag. If necessary smelt a second time, when the gold should be pure enough to dispose of. In extreme cases, the gold may weigh but one-fifth of the amalgam treated. In districts where sufficient water for sluicing is not procurable, dry washing is resorted to. Nothing but rich, coarse gold can be worked by this method, and the dry washer rarely delves far below the surface for his gold. In the Mexican deserts the dirt is laid on raw hide, all the large pebbles picked out and the sand rubbed as fine as possible between the hands. The sand is placed in a batea and winnowed by tossing in the air, the lighter material being blown to leaward and the heavy gold falling into the batea. A form of winnowing machine has been patented, which may be driven by horse or hand-power, which is said to give satisfaction. It works by forcing a strong blast of air from a fan through a canvas screen. The inventor claims that it will do the work of three men, and work dirt for 2-1/2 cents a cubic yard. When there is a tendency in the material to cake, dry washing is impossible. CHAPTER VI. CAMP LIFE. The Indian truthfully observes: "White man make heap big fire; keep far off. Indian make little fire; get close. All same." The small fire does best in the circular tepee tent, made of canvas or leather, in use on the plains. The tepee is quite an institution, but it is generally as full of smoke as a kitchen chimney, and for that reason cannot truthfully be recommended. In theory, the smoke should all pass out of the opening in the top. By using no second skin and carefully excluding all air from around the lower rim of the tepee, it will become an admirable place to cure hams, fish, etc., by the original smoke-dried process. The Scripture declares that he that tarrieth over the wine cup has red eyes next morning, and so has he that sleeps in a smoky tepee. Properly made, however, the tepee is the thing where wood is scarce.