APTURINAC, a river of Peru, which, after a course of 500 m., assumes the name, first, of Tambo, and then of Ucayali, which finally joins the Tanmaragua to form the Amazon. The A. proper rises to the n.w. of the great tableland of lake Titicaca, receiving from it, however, no portion of its waters. Among the tributaries of the Amazon, it is one of the most southerly; while among them, it approaches perhaps the nearest to the Pacific. The A., from its source in 10° s., drains the eastern face of the Andes through about 5°, till it changes its name, as above, in 10° 45' s., meanwhile receiving several considerable afiluents, more especially the Villcamayo, front the opposite quarter. The A. and its feeders partake of the nature rather of mountain torrents than of navigable rivers; and even for traveling Nyland, their rocky and rugged banks are always difficult, and often impracticable. The valleys vary in climate and productiveness according to their elevation. The upper ones yield wheat and barley,
and most of the fruits of Europe; while the lower, or at least the lowest ones, abound in sugar and cotton, plantains, and pine-apples. The basin of the A., as a whole, is said to he the finest part of Peru, and to contain the largest proportion of native population —the best specimens apparently of the aboriginal civilization.
AQUA (water), a compound of oxygen and hydrogen, symbol The prefix A. was much used by alchemists; A. fortis, strong water, is nitric acid; A. regia, royal water, a compound usually containing one part of nitric acid with two of hydrochloric, which dissolves gold; A. water of life, strong drink, or alcohol. In modern pharmacy we have A. di8tilla, pluvialis, lantana, and marina, or distilled, river, rain, spring, and sea water.