On the fourteenth, we passed a small lake, highly impregnated with glauber salts, the efflorescence of which, covers the margin of the lake to the depth of several inches, and appears at a distance like snow. We made a cache on the nineteenth, of some goods, intended for future trading with Crow Indians, who rove at some seasons, on the tract of country we are now passing. Cache, derived from the French verb cacher, to conceal, is applied in this region to an excavation for the reception of goods or furs, commonly made in the following manner. A proper place being selected, which is usually near the border of some stream, where the bank is high enough to be in no danger of inundation, a round hole two feet in diameter is carried down to a depth of three feet, when it is gradually enlarged, and deepened until it becomes sufficiently capacious to contain whatever is destined to be stored in it. The bottom is then covered with sticks to prevent the bales from touching the ground, as otherwise they would soon contract moisture, become mouldy, and rot. The same precautions are observed to preserve them intact from the walls of the cave. When all is snugly deposited and stowed in, valueless skins are spread over the top, for the same excellent purpose, and the mouth is then closed up with earth and stones, beat down as hard as possible, to hinder it from settling or sinking in. The surplus earth taken out, is carefully gathered up and thrown into the stream, and the cache finally completed, by replacing stones and tufts of grass, so as to present the same uniform appearance, as the surrounding surface. If the cache is made in a hard clay bluff, and the goods perfectly dry when put in, they will keep years without damage. At this period we were in view of the Wind Mountains, which were seen stretching away to the northward, their bleak summits mantled over with a heavy covering of snow.