Page:Encyclopædia Britannica, Ninth Edition, v. 18.djvu/101

O X O X A 91 separate specifically examples from those localities only shews that they possess more or less well-defined local races. Commonly placed near Asia, but whether really akin to it cannot be stated, is the genus Scops, of which nearly forty species, coming from different parts of the world, have been described ; but this number should probably be reduced by one half. The type of the genus, S. giu, the Petit Due of the French, is a well-known bird in the south of Europe, about as big as a Thrush, with very delicately pencilled plumage, occasionally visiting Britain, emigrating in autumn across the Mediterranean, and ranging very far to the eastward. Further southward, both in Asia and Africa, it is represented by other species of very similar size, and in the eastern part of North America by S. asio, of which there is a tolerably distinct western form, S. kennicotti, besides several local races. /& . asio is one of the Owls that especially exhibits the dimorphism of coloration above mentioned, and it was long before the true state of the case was understood. At first the two forms were thought to be distinct, and then for some time the belief obtained that the ruddy birds were the young of the greyer form which was called S. n&via ; but now the " Red Owl " and the "Mottled Owl " of the older American ornithologists are known to be one species. 1 One of the most remarkable of American Owls is Speotyto cunicularia, the bird that in the northern part of the continent inhabits the burrows of the prairie dog, and in the southern those of the biscacha, where the latter occurs making holes for itself, says Darwin, where that is not the case, rattlesnakes being often also joint tenants of the same abodes. The odd association of these animals, interesting as it is, cannot here be more than noticed, for a few words must be said, ere we leave the Owls of this section, on the species which has associations of a very different kind the bird of Pallas Athene, the emblem of the city to which science and art were so welcome. There can be no doubt, from the many representations on coins and sculptures, as to their subject being the C arine noctua of modern ornithologists, but those who know the grotesque actions and ludicrous expression of this veritable buffoon of birds can never cease to wonder at its having been seriously selected as the symbol of learning, and can hardly divest themselves of a suspicion that the choice must have been made in the spirit of sarcasm. This Little Owl (for that is its only name though it is not even the smallest that appears in England), the Chevcche of the French, is spread throughout the greater part of Europe, but it is not a native of Britain. It has a congener in C. brama, a bird well known to all residents in India. Finally, we have Owls of the second section, those allied to the Screech-Owl, Aluco flammcus, the Effraie* of the French. This, FIG. 2. Aluco fo.immeus. with its discordant scream, its snoring, and its hissing, is far too well known to need desciiption, for it is one of the most widely- spread of birds, and is the Owl that has the greatest geographical range, inhabitirg almost every country in the world, Sweden and Norway, America north of lat. 45, and New Zealand being the principal exceptions. It varies, however, not inconsiderably, both in size and intensity of colour, and several ornithologists have tried 1 See the remarks of Mr Ridgway in the work before quoted (B. N. America, iii. pp. 9, 10), where also response is made to the observations of Mr Allen in the Harvard Bulletin (ii. pp. 338, 339). 2 Through the dialectic forms Fresaie and Presaie, the origin of the word is easily traced to the Latin prassayaa. bird of bad omen ; but it has also been confounded with Orfraie, a name of the OSPREY (vide supra, p. 56). to found on these variations more than half a dozen distinct species. Some, if not most of them, seem, however, hardly worthy to bo considered geographical races, for their differences do not always depend on locality. Mr Sbarpe, with much labour and in great detail, has given his reasons (Cat. B. Brit. Museum, ii. pp. 291-309; and Ornith. Miscellany, i. pp. 269-298; ii. pp. 1-21) for acknowledging four "subspecies" of A. flammeus, as well as five other species. Of these last, A. tcncbricosus is peculiar to Australia, while A. novse-hollandias inhabits also New Guinea, and has a "subspecies," A. castatKqjs, found only in Tasmania; a third, A. candidus, has a wide range from Fiji and northern Australia through the Philippines and Formosa to China, Burmah, and India ; a fourth, A. ca2)ensis, is peculiar to South Africa ; while A. thomensis is said to be confined to the African island of St Thomas. To these may perhaps have to be added a species from New Britain, described by Count Salvadori as Strix aurantia, but it may possibly prove on further investigation not to be an Alucine Owl at all. (A. N. ) OX. See CATTLE. OXALIC ACID, an organic acid of the formula (COOH) 2 , which, in a general scientific sense, excites our interest chiefly by its almost universal diffusion throughout the vegetable kingdom. Traces of oxalates are contained in the juices of, probably, all plants at certain stages of their growth ; but so are lime-salts, which, in solutions, can coexist with the former only in the presence of free acid. Hence the frequent occurrence in plant-cells of those crystals of oxalates of lime with which all micro- scopists are familiar. In certain algas, if they grow on cal careous soils, this salt, according to Bracannot, may form as much as one-half of the total dry solids. Of phanero gamic tissues, the roots of the officinal kinds of rhubarb may be named as being peculiarly rich in oxalate of lime- crystals. It is perhaps as well to add that the juicy stems of the garden rhubarb, although not free of oxalic, owe their sourness chiefly to malic acid. The strongly sour juices of certain species of Rumexondi. Acetosella, on the other hand, are exceptionally rich in acid oxalates. The juice of Oxalis Acetosella, when concentrated by evapora tion, deposits on cooling a large crop of crystals of bin- oxalate of potash. This salt, as an educt from the plant juice named, has been known for some three centuries as " sal acetosellae " or " salt of sorrel." Oxalic acid and all soluble oxalates are dangerous poisons, which almost implies that they cannot occur, under normal conditions, in the juices of the higher animals. Yet human urine always contains traces of oxalate of lime, which, when the urine is or becomes alkaline, forms on standing a micro- crystalline deposit. In certain diseased conditions of the system the oxalate is formed more largely, and may be deposited within the bladder in crystals or even develop into calculi. The discovery of oxalic acid must be credited to Scheele, who obtained it in 1776 by the oxidation of sugar with nitric acid, and called it saccharic acid. In 1784 he proved its identity with the acid of sal acetosellae. Our knowledge of the elementary composition of oxalic acid is the result of the independent labours of Berzelius, Dobe- reiner, and Dulong (1814-21). Its artificial synthesis can be effected in various ways. Thus, for instance, (1) cyanogen, when dissolved in aqueous hydrochloric acid, gradually assimilates 4H 9 per N.,C and becomes oxalate of ammonia, C 2 4 (NH 4 ) 2 (Liebig). Or (2) moist carbonic acid is reduced by potassium to formic acid, CO., + H.,O - = CH.,O<>, which, of course, assumes the form of potash salt (Kolbe). This latter, when heated beyond its fusing point, breaks up into oxalate and hydrogen, 2CHKO 2 = H 2 + C,O 4 K 2 (Erlenmeyer). At 350 dry CO 2 and sodium unite into oxalate C 2 O 4 Na.> (Drechsel). Sugar, starch, and many other organic bodies of the " fatty " series, when boiled with nitric acid, yield oxalic acid as a penultimate product of oxidation In this manner oxalic acid used to be produced, industrially, from