quartan agues. This native vegetable operates more speedily than the foreign bark; and, in large doses, induces a lethargic sleep: the portion to be given, ought never to exceed one dram, and should be administered in wine, two or three times in the course of 24 hours.—The same cautions, that are necessary in the use of the Peruvian bark, are likewise to be observed in taking the seeds and flowers of the nettle. Lastly, M. Zannetini recommends a slight infusion of the latter, in wine, as an excellent preservative for those who reside in marshy and unwholesome situations.
O.
OIL.—In April, 1792, a patent was granted to Mr. Cha. Gower, for his method of depurating and improving animal oil. He directs equal quantities of oil, and of water previously acidulated with a due proportion of vitriolic acid, to be poured into a barrel or other vessel, which must be placed near a fire, and briskly agitated, in order to unite the two fluids. The liquor is then passed into pans, with a view to complete the solution of the gelatinous parts; and that the water may sink to the bottom; when the clear oil is decanted. Should, however, the oil intended to be purified have a turbid, or ropy appearance, the patentee directs equal parts of such liquid, and pure water, to be mixed with a little yeast, and shaken in the manner above-mentioned. When the fermentation ceases, the whole must be poured into similar pans, where all feculent particles will subside, and the pure oil float on the surface, whence it may be drawn off for use.
OPODELDOC, a well-known liniment, which is prepared by digesting 3 parts of soap in 16 parts of the spirit of rosemary, till the former be dissolved; when one part of camphor should be incorporated with the whole.—This unguent is of great service in bruises, rheumatic affections, and similar painful complaints; but, being very volatile, it ought to be kept in bottles closely stopped, to prevent the access of air.
ORNITHOLOGY, is that science which treats of birds; describing their form, animal economy, and various uses.
Having already specified the natural habits, as well as the useful purposes, together with the opposite qualities, of the feathered tribe, under many individual names of birds, and especially those which are natives of Britain, in the preceding alphabet of this work, we shall, at present, only subjoin a few general observations, and conclude with an enumeration of the most remarkable objects of this class; the characters of which have been stated in vol. i. p. 58.
Although birds are, by their peculiar form, distinguished from all other creatures, yet their internal structure, in many respects coincides with that of mammillary animals. Thus, both have a heart with two ventricles and two auricles; red, warm blood; and solid
