Page:EB1911 - Volume 10.djvu/605

Rh substances in commonest use are:—lime or limestone, to slag off silica and silicates, fluor-spar for lead, calcium and barium sulphates and calcium phosphate, and silica for removing basic substances such as limestone. Other substances are also used, but more commonly in assaying than in metallurgy. Sodium and potassium carbonates are valuable for fluxing off silica; mixed with potassium nitrate sodium carbonate forms a valuable oxidizing fusion mixture; “black flux” is a reducing flux composed of finely divided carbon and potassium carbonate, and formed by deflagrating a mixture of argol with to  its weight of nitre. Borax is very frequently employed; it melts to a clear liquid and dissolves silica and many metallic oxides. Potassium bisulphate is useful in the preliminary treatment of refractory aluminous ores. Litharge and red lead are used in silver and gold assays, acting as solvents for silica and any metallic oxides present.

FLY (formed on the root of the supposed original Teut. fleugan, to fly), a designation applied to the winged or perfect state of many insects belonging to various orders, as in butterfly (see ), (q.v.),  (q.v.),  (q.v.), &c.; also specially employed by entomologists to mean any species of the two-winged flies, or (q.v.). In ordinary parlance fly is often used in the sense of the common house-fly (Musca domestica); and by English colonists and sportsmen in South Africa in that of a species of tsetse-fly (Glossina), or a tract of country (“belt”) in which these insects abound (see ).

Apart from the house-fly proper (Musca domestica), which in England is the usual one, several species of flies are commonly found in houses; e.g. the Stomoxys calcitrans, or stable-fly; Pollenia rudis, or cluster-fly; Muscina stabulans, another stable-fly; Calliphora erythrocephala, blue-bottle fly, blow-fly or meat-fly, with smaller sorts of blue-bottle, Phormia terraenovae and Lucilia caesar; Homalomyia canicularis and brevis, the small house-fly; Scenopinus fenestralis, the black window-fly, &c. But Musca domestica is far the most numerous, and in many places, especially in hot weather and in hot climates, is a regular pest. Mr L. O. Howard (Circular 71 of the Bureau of Entomology U.S. Dept. of Agriculture, Washington, 1906) says that in 1900 he made a collection of the flies in dining-rooms in different parts of the United States, and out of a total of 23,087 flies, 22,808 were the common house-fly. Its geographical distribution is of the widest, and its rapidity of breeding, in manure and door-yard filth, so great that, as a carrier of germs of disease, especially cholera and typhoid, the house-fly is now recognized as a potent source of danger; and various sanitary regulations have been made, or precautions suggested, for getting rid of it. These are discussed by Mr Howard in the paper referred to, but in brief they all amount to measures of general hygiene, and the isolation, prompt removal, or proper sterilization of the animal or human excrement in which these flies breed.

FLYCATCHER, a name introduced in ornithology by Ray, being a translation of the Muscicapa of older authors, and applied by Pennant to an extremely common English bird, the M. grisola of Linnaeus. It has since been used in a general and very vague way for a great many small birds from all parts of the world, which have the habit of catching flies on the wing. Ornithologists who have trusted too much to this characteristic and to certain merely superficial correlations of structure, especially those exhibited by a broad and rather flat bill and a gape beset by strong hairs or bristles, have associated under the title of Muscicapidae an exceedingly heterogeneous assemblage of forms much reduced in number by later systematists. Great advance has been made in establishing as independent families the Todidae and Eurylaemidae, as well as in excluding from it various members of the Ampelidae, Cotingidae, Tyrannidae, Vireonidae, Mniotiltidae, and perhaps others, which had been placed within its limits. These steps have left the Muscicapidae a purely Old-World family of the order Passeres, and the chief difficulty now seems to lie in separating it from the Campephagidae and the Laniidae. Only a very few of the forms of flycatchers (which, after all the deductions above mentioned, may be reckoned to include some 60 genera or subgenera, and perhaps 250 species) can here be even named.

The best-known bird of this family is that which also happens to be the type of the Linnaean genus Muscicapa—the spotted or grey flycatcher (M. grisola). It is a common summer visitant to nearly the whole of Europe, and is found throughout Great Britain, though less abundant in Scotland than in England, as well as in many parts of Ireland, where, however, it seems to be but locally and sparingly distributed. It is one of the latest migrants to arrive, and seldom reaches the British Islands till the latter part of May, when it may be seen, a small dust-coloured bird, sitting on the posts or railings of gardens and fields, ever and anon springing into the air, seizing with an audible snap of its bill some passing insect as it flies, and returning to the spot it has quitted, or taking up some similar station to keep watch as before. It has no song, but merely a plaintive or peevish call-note, uttered from time to time with a jerking gesture of the wings and tail. It makes a neat nest, built among the small twigs which sprout from the bole of a large tree, fixed in the branches of some plant trained against a wall, or placed in any hole of the wall itself that may be left by the falling of a brick or stone. The eggs are from four to six in number, of a pale greenish-blue, closely blotched or freckled with rust-colour. Silent and inconspicuous as is this bird, its constant pursuit of flies in the closest vicinity of houses makes it a familiar object to almost everybody. A second British species is the pied flycatcher (M. atricapilla), a much rarer bird, and in England not often seen except in the hilly country extending from the Peak of Derbyshire to Cumberland, and more numerous in the Lake District than elsewhere. It is not common in Scotland, and has only once been observed in Ireland. More of a woodland bird than the former, the brightly-contrasted black and white plumage of the cock, together with his agreeable song, readily attracts attention where it occurs. It is a summer visitant to all western Europe, but farther eastward its place is taken by a nearly allied species (M. collaris) in which the white of the throat and breast extends like a collar round the neck. A fourth European species (M. parva), distinguished by its very small size and red breast, has also strayed some three or four times to the extreme south-west of England. This last belongs to a group of more eastern range, which has received generic recognition under the name of Erythrosterna, and it has several relations in Asia and particularly in India, while the allies of the pied flycatchers (Ficedula of Brisson) are chiefly of African origin, and those of the grey or spotted flycatcher (Muscicapa proper ) are common to the two continents.

One of the most remarkable groups of Muscicapidae is that known as the paradise flycatchers, forming the genus Tchitrea of Lesson. In nearly all the species the males are distinguished by the growth of exceedingly long feathers in their tail, and by their putting on, for some part of the year at least, a plumage generally white, but almost always quite different from that worn by the females, which is of a more or less deep chestnut or bay colour, though in both sexes the crown is of a glossy steel-blue. They are found pretty well throughout Africa and tropical Asia to Japan, and seem to affect the deep shade of forests rather than the open country. The best-known species is perhaps the Indian T. paradisi; but the Chinese T. incii, and the Japanese T. princeps, from being very commonly represented by the artists of those nations on screens, fans and the like, are hardly less so; and the cock of the last named, with his bill of a pale greenish-blue and