On the 15th November, we quitted the magnificent plains of the Koukou-Noor, and entered upon the territory of the Mongols of Tsaidam. Immediately after crossing the river of that name, we found the aspect of the country totally changed. Nature becomes all of a sudden savage and sad; the soil, arid and stony, produces with difficulty a few dry, saltpetrous bushes. The morose and melancholy tinge of these dismal regions seems to have had its full influence upon the character of its inhabitants, who are all evidently a prey to the spleen. They say very little, and their language is so rude and guttural that other Mongols can scarcely understand them. Mineral salt and borax abound on this arid and almost wholly pastureless soil. You dig holes two or three feet deep, and the salt collects therein, and crystallizes and purifies of itself, without your having to take any trouble in the matter. The borax is collected from small reservoirs, which become completely full of it. The Thibetians carry quantities of it into their own country, where they sell it to the goldsmiths, who apply it to facilitate the fusion of metals. We stayed two days in the land of Tsaidam, feasting upon tsamba and some goats which the shepherds gave in exchange for some bricks of tea. The long-tailed oxen and the camels regaled themselves with the nitre and salt which they had every where about for the picking up. The grand object with the whole caravan was to get up its strength as much as possible, with a view to the passage of the Bourhan-Bota, a mountain noted for the pestilential vapours in which, as we were informed, it is constantly enveloped.