678 BLACK FLUX BLACK FOREST The body is covered with small, hard scales. They vary in size from 2 to 14 or 16 Ibs. They are caught early in the spring, and through Black flsh (Tautoga Americana). the summer, from off the rocky ledges of the coast, or from boats anchored over the reefs. The fishing for them is a favorite sport in the warm summer weather, and the fish, though of dry flavor, are much esteemed when baked. BLACK FLUX, a mixture of carbonate of pot- ash and carbon, obtained by deflagrating two or three parts by weight of cream of tartar (or crude argol) and one part of nitre in a red- hot earthen crucible. If equal weights of these substances be taken, the nitric acid of the salt- petre will oxidize the carbon, and the result will be a pure carbonate of potash, or white flux. When black flux is fused with the ox- ides of copper, iron, or lead, or with the acid compounds of those metals, the carbon acts as a reducing agent, while the carbonate of pot- ash takes up the impurities, such as sulphur and silica. The reduced metal collects in a button in the fluid slag, and on cooling can be easily separated from its matrix. Black flux must be kept in closely stoppered bottles, as it rapidly deteriorates by absorption of water from the air. BLACK FLY, a small dipterous insect, some- times called gnat, midge, and sand fly, belong- ing to the genus simulium. The length of the common species (8. rnolestum) is about one tenth of an inch; the color is black, with transparent wings; the legs short, with a broad whitish band around them. They be- gin to appear in northern New England in May, and continue about six weeks ; after them, however, comes another species (a. noci- vum), more numerous and smaller. These in- sects are a perfect pest in the subarctic regions, and so abundant in their season in the woods from Labrador to Maine, that travellers and anglers, unless of the most determined charac- ter, rarely venture far from the seashore. In bright still days they are innumerable, swarm- ing in houses, flying in one's face, crawling un- der tightly fitting garments, and there remain- ing, biting even in the night. Human beings ad even dogs pass their lives at this season in a state of continual torment, much worse than amid the mosquitoes of the south. In cloud) weather, unlike the mosquito, they disappear. The bite is severe and stinging, each showing a point of blood, and followed by an irritation and swelling which last several days. No veils nor gloves protect against their attack, as their small size enables them to penetrate wherever they choose. The best remedy seems to be a viscid ointment, into which tar enters, and which arrests and destroys them. The smaller midges which succeed them, called no-see-'em by the Indians from their minuteness, would hardly be seen were not their wings whitish mottled with black ; they come forth in myriads toward evening, creep- ing under clothes, their bites feeling for the moment as if caused by sparks of fire; they do not draw blood, and there is rarely any swelling produced ; they are most troublesome in July and August, and nothing seems avail- able against their swarms, unless a thick smoke, quite as disagreeable, be considered a remedy. The larva and pupa are both aquatic, and the former is in some ponds as injurious to the raiser of young trout and other fish as the adult insect is to the angler for the adult fish. The larva, according to Mr. 8. Green, spins webs under water as perfect as those of the spider, with equal mechanical ingenuity and rapidity, and in the same way, by fastening the threads at different points and going back and forth till the web is finished ; the web is strong enough to destroy the fish while pro- vided with the umbilical sac, by getting wound round the fins, head, and gills. The buffalo gnat of the western prairies, a much larger species, has been known to bite horses to death ; and an allied fly (rhagio), according to Westwood, is a great pest to man and beast on the confines of Hungary and Servia, and, it is said, will destroy cattle. BLACKFORD, an E. county of Indiana, drained by the Salamonie river ; area, 180 sq. m. ; pop. in 1870, 6,272. It is traversed by the Fort Wayne, Muncie, and Cincinnati, and a branch of the Pittsburgh, Cincinnati, and St. Louis rail- road. The surface is diversified by plains and rolling lands, and the soil is fertile. The chief productions in 1870 were 82,763 bushels of wheat, 75,346 of Indian corn, 14,567 of oats, 111,106 Ibs. of butter, and 24,068 of wool. There were 2,646 horses, 1,720 milch cows, 1,685 other cattle, 7,820 sheep, and 5,863 swine. Capital, Hartford. BLACK FOREST (Ger. Schirarzwald ; anc. Silva Mareiana, the S. W. branch of the Her- cynian forest), a range of woody mountains in the S. W. part of Germany, traversing Ba- den and Wiirtemberg, and forming the eastern boundary of a portion of the basin of the Rhine, the corresponding western being form- ed by the Vosges. It extends about 90 m. in length, almost parallel with the course of the Rhine, from which it is distant in many places less than 20 m., and has a breadth in its south- ern part of about 30 m., and in its northern part
