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  required. The inconveniences which have prevented this method from being generally used, are; the difficulty of completely cleaning the phial from the liquid which it previously contained; the difficulty of filling the phial exactly with the same volume of each liquid; and the variation of the volume of the phial from changes of temperature.

The pressure of the atmosphere supports columns of different fluids, whose height is inversely as the densities of the fluids. An aræometer has been constructed on this principle. It is a curved tube, one leg of which has its extremity immersed in water, and the other in the spirit whose density is to be tried. On rarifying the air in the tube, by means of a pump fixed at the upper part of the tube, the water ascends in one leg, and the spirit in the other; the height of the column of each liquid being measured by a scale of equal parts applied to each branch of the tube. This instrument has never come into use, probably on account of the difficulty of ascertaining, with precision, the points at which the surfaces of the columns are terminated. See Encyclopædia, Art. , Part I. ch. 2. sect. 2. for some farther notice of Aræometers.

 ARAUCANIA, a territory on the western coast of South America, extending 186 miles in length, between the rivers Biobio and Valdivia, and penetrating 420 miles inland to the foot of the Andes. The lower parts of these mountains are included within its limits, and the whole superficies which is bounded by 36° 44′ of south latitude on the north, and 39° 50′ on the south, occupies about 78,120 square miles. Originally, Araucania was of smaller dimensions, not reaching above 300 miles from the sea-shore; but it received a great accession by the union of another territory belonging to the tribe Puclches, in the course of the seventeenth century.

This is a pleasant and fertile country, partly consisting of wide and extensive plains, partly mountainous, with spacious valleys interposed. It contains two considerable lakes, Laquen, called Villarica by the Spaniards, 72 miles in circuit, with a conical islet in the centre; and Nahuelguapi, 80 miles in circuit, which also has an islet towards one side covered with trees. The latter is the source of a river of the same name, which, after a long course, falls into the ocean, near the Straits of Magellan; and the Talton, which discharges itself farther north into the sea, rises from the latter. A great volcanic mountain, fourteen miles in circumference at the base, and visible at the distance of 150, stands near the lake Villarica. Its eruptions are not violent, though it is always in an active state. The summit is covered with snow, but lower down, perpetual verdure is intermixed with woods, and besides mineral springs, several streams flow from it. Sulphur and Salt are plentiful on the eastern confines; and quantities of Amber-grease are thrown up on the coast. Mines of Gold, formerly yielding immense revenues, are said to exist in the southern parts, but ever since the natives expelled their Spanish invaders, they have prohibited resorting to them under pain of death. Possibly all remembrance of their site is lost, and the Araucanians are sufficiently prudent to avoid awakening the cupidity of neighbouring nations by discovering it. This precious metal is not rare beyond their confines. We are acquainted with the vegetable productions of this territory, only in common with those of the surrounding country; they are numerous, useful, and afford a copious supply for the sustenance of mankind. The beauty and utility of a tree called the Pehnen, probably a kind of breadfruit, or of some analogous species, is particularly celebrated, as uniting the properties of the Pine, Chesnut and Frankincense. It is of spontaneous growth, requiring no culture, and rises 80 feet in height, by about 8 in circumference; the whole tree at full size being of a pyramidal figure. The flowers are conical, and its fruit, which is as large as the human head, is divided into cells, containing kernels resembling chesnuts. These are ate in the same way, or sometimes reduced to flour, and preserved by boiling. A yellowish odoriferous gum exudes through the bark. The sea abounds in fishes, and various phocæ frequent the shores. Of these the sea Elephant is the largest, often being 22 feet in length, and 15 around the breast; it produces more oil than the rest; and is so fat, that undulations under the skin are perceptible during its motion. Furious combats ensue among the males for possession of the females, which latter always retire until their issue; and that for the most part is in the death of one or other of them. Their skins are generally covered with scars; yet notwithstanding the great size of the animal, and its warfare among its own species, a smart blow near the nose is invariably fatal. A species of Hippopotamus is said to inhabit some of the lakes and rivers of Araucania, different from that of Africa, but its existence is not sufficicntly authenticated. However, it is only of late years that Naturalists have become acquainted with the real Hippopotamus, whose figure and habits were long considered to be fabulous. One of the most useful animals in this country is the Chilihueque, a species of diminutive camel, greatly resembling the sheep, about 4 feet high, of various colours, grey, brown or black, and bearing very soft wool, which is employed solely in manufacturing the finest cloths. Formerly, it was used as a beast of burden; now it ts highly prized by the inhabitants, by whom it is never killed except at festivals, or on occasion of solemn sacrifices.

The natives of the country now described, are called Araucans or Araucanians from the province of Arauco, which forms a small portion of it. They denominate themselves Auca, which signifies free, or unsubdued, though some European authors have affirmed, that both Auca and Araucanian originated with the Spaniards, as a name of reproach, signifying rebel or savage banditti; and others, such as Falkner, says, that they denominate themselves generally moluches or warriors. Whatever may be the truth, they are a