Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 1, 1802).djvu/65

Rh AMMONIAC is a concrete, gummy-resinous juice, usually brought from the East Indies in large masses composed of lumps or tears of a milky colour, but on exposure to the air, it quickly acquires a yellowish appearance. Hitherto we have no certain account of the plant which affords this juice, but it has, and with some probability, been asserted, that it is a species of the ferula, from another species of which is also produced the ;—it is said to grow in Nubia, Abyssinia, and the interior parts of Egypt.

This gum has a nauseous sweetish taste, succeeded by a sensation of bitter; and a smell somewhat resembling, but more grateful than, galbanum. When chewed, it softens in the mouth, and becomes of a white colour. It may be partially dissolved, in water, or in vinegar, with which it assumes the appearance of milk, but the resinous part, amounting to about one half, subsides when suffered to rest. A similar composition, but much inferior in virtue, is frequently sold under the name of strained gum ammoniac. Those tears which are large, dry, and free from little stones, or other impurities, should be selected and prepared for internal use; the coarser kind may be purified by solution and straining, but unless this be carefully managed, it will lose a considerable portion of its line and more volatile parts.

In medicine, it is prescribed for removing obstructions of the abdominal viscera; in hysterical complaints occasioned by the deficiency of periodical evacuations, and in long and obstinate colics, proceeding from viscid matter lodged in the intestines. A solution of it, in vinegar of squills, has proved of considerable service in the humid chronic asthma of the aged and decrepit. The most convenient form for its exhibition, is that of pills; a scruple may be given every night, or oftener. Externally it is used for softening and ripening indolent tumours; and with a mixture of squill vinegar, forms a plaister which has sometimes been successfully recommended for white swellings. A solution of it, in penny-royal water, is usually kept in the shops, under the name of ammoniac milk.  AMPHIBIOUS ANIMALS are so called, on account of their living partly on land, and partly in water.

We cannot, consistently with our plan, enter into a disquisition respecting their nature and functions; and shall therefore content ourselves with observing, that in their structure, they are principally distinguished from land-animals, by having red cold blood, and instead of lungs, either gills or branchiæ, as is generally observed in snakes, eels, and fish, which chiefly inhabit the water. Sometimes, however, they have the oval hole open between the right and left auricles of the heart; and, in many, the arterial canal is also free. This is a distinguishing character of the phocæ, or such animals as enjoy their chief functions on land, for instance, otters, beavers, frogs, crocodiles, some kind of rats, birds, &c. While these remain under water, where they may safely continue for several hours, their respiration is interrupted; and the blood, not finding a free passage through the pulmonary artery, rushes through the hole from the right to the left auricle, and partly through the arterial canal; having but a short course to the aorta, the largest of all the blood vessels, and thence circu-