BLACKING. 143 BLACK LETTER. models are coated to give the casting a smooth surface and to prevetft the molten metal from penetrating the same. BLACK-JACK. The name given by miners to zinc blende, which is of black color. It was also the name applied in former times to a kind of drinking-fiagon. For Black-jack as the name of a tree, see Oak. BLACK JACK. A nickname given, chiefly by his political opponents, to Gen. John A. Logan. BLACK KNIGHT, The. ( 1 ) The name of a character in the early romances, son of Oriana and Amadis of Gaul. (2) Richard Coeur de Lion was known in Scott's novel Ivanhoe as The Black Knight or The Black Sluggard, on account of the suit of black armor and the black shield he bore during his wanderings in England. BLACK KNIGHT, Complaint of The. A poem written by Lydgate, but erroneously in- cluded in some of the early editions of Chaucer. BLACK LAW. In American history, a name applied to any one of a series of laws, passed in various border and Northern States before the Civil War, sharply discriminating against free negroes who wished to emigrate to such States and become citizens thereof. Thus, in some States, certificates of freedom were to be filed, negroes ' were to be rigidh- excluded from the militia and from the public schools, and no negro was to testify in cases in which any white man was directly interested. More or less strin- gent laws were passed in Virginia, Maryland, Delaware, Mississippi, Indiana, Illinois. Iowa, Oregon, and New Mexico. Consult Wilson, Rise and Fall of the Slave Power in America (Boston, 1872-75). BLACK LEAD. See Graphite. BLACKLEG (so named because the tumors alTect the legs oftener than other parts of the body), Black Quabteb, or Svmptomatic An- thkax. An infectious disease due to the action of Bacterium chanvoli. It is confined almost en- tirely to cattle, but cases have occurred also in sheep, goats, camels, pigs, and horses. Man is immune to it. The disease is characterized clinically by the development of tumors in the muscles of various parts of the bod}', producing, when stroked, a crackling sound, which serves to distinguish this disease from anthrax. After death the tumors become infiltrated with blood and serum containing gas-bubbles; and this again distinguishes blackleg from anthrax, as the tumors of the latter are not found to contain any gas. Further, in blackleg the spleen is not af- fected and the blood coagulates quickly, while in anthrax the spleen is much enlarged and the blood clots more slowly. Blackleg has long been known as a disease of cattle, but has, until within recent years, been generally confused with anthrax. The blackleg bacterium docs not de- velop in the presence of free oxygen. In llie blood it is slightly motile. The symptoms of black- leg are loss of appetite, debility, and great eleva- tion of temperature. The disease runs its course very rapidly, and is fatal in nearly all cases. Cat- tle between the ages of six and eighteen months are most susceptible, young calves and old ani- mals being more resistant. Fat cattle seem to be especially liable to infection. The symptoms appear suddenly within from one to three days after infection. The tumors may develop at once or may be preceded by tlu' symptoms of fever and trembling. A lameness of the legs is usually observed, and is due to the muscular tumors which almost always accompany the dis- ease. The animal manifests considerable pain, and falls to the ground soon after the develop- ment of the first symptoms. The part which is most affected becomes swollen and assumes a black or blue color, which is due to the infiltra- tion and coagulation of blood within it. The dried spores of the blackleg bacterium may be carried in hay or other drj- feed, and it is quite possible that animals may be infected by eating such material. Recent investigations, however, indicate that infection most frequently takes place through wounds of the skin, mouth, or tongue, such as would be produced by various spines and the awns of grasses. Blackleg is found in nearly all countries of the globe. In the mountains of France it is known as mal de montaijnc, in Denmark as rashsi/ge, and in Gernuuiy as Rauschhrand. In the I'nited States it is most prevalent in Texas, Kansas, Nebraska, South Dakota, and Colorado. Medical treatment of blackleg has been uni- formly unsuccessful and is not to be recom- mended. On the other hand, preventive vaccina- tion has given very satisfactory results. Out of 000.000 cattle vaccinated in Europe, only one- half of one per cent, subsequently died df black- leg. Equally striking results have been obtained by the Bureau of Animal Industry of the United States Department of Agriculture. This bureau has perfected a method of producing immunity against blackleg by one vaccination, requiring less time than the old method, in which two inoculations were made, with an attenuated and strong vaccine, respectively. Stockmen may now buy the vaccine and inoculate their own cattle. For further study of blackleg, consult: A. .T.Mur- ray and others, "Special Report on Diseases of Cattle," Report of United States Department of Agriculture ( 'ashington, 1892) ; Bureau of Ani- mal Industry, 15th Annual Report, p. 27; ^locard and Leclainche. Les maladies microbi- cnncs dfs aniinnux (Paris. 1811S). BLACK LETTER (Hark Cpttrr). A name commonly given in England and America to the printing-types which on the Continent me most generally known as Gothic. The first printed books imitated every peculiaritj' of the con- temporary manuscripts; and as printing was first practiced in Germany and the Netherlands, the first types were copies of the letters in use in those countries in the middle of the Fifteenth Century. Two sorts of letters have been em- |)loyed in the writings of Western Christendom. The Gothic style dates from about the middle of the Twelfth Century; the type which imitated it, first used c. 144.3, s])read with the art of printing into most European countries, until the classical taste reverted to the more graceful letter known as Roman, which is a revival of what is known in pala'ography as the Caroline minuscule, of the kind used in the Eleventh and Twelfth cen- turies. -Aldus attempted in 1501 to supersede the Roman letters by what have been called -Vldine or Venetian, but are best known as Italic characters. The.sc can scarcely be said to have come into much more than temporary or ex- ceptional use; but the Roman letters in no long time spread from Venice all over the west of Europe. Although thus supplanted in general
