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LEFT DYEING 445 DYERSBUIIG vegetable substance — as cotton, linen, oi* jute, is easily washed off, except in the case of the "direct" colors. Vegetable substances are consequently usually treated with mordants (see Calico). Mordants are substances which form in- soluble precipitates with the dyes in the body of the fiber. The mordants most largely used are tannic acid, the salts of antimony, aluminum, and chromium. Dyeing of Cotton. — The following is a brief outline of the processes in use for a few important colors: Black is produced by mordanting the goods with salt of iron and then dyeing in a decoction of logwood or by dyeing in a bath containing logwood, bichromate of potash, and mineral acid. Aniline salts with a suitable oxidizing mixture yield a very fast and valuable black. Bichromates and chlorates are among the substances used as oxidizing agents. Brown is obtained by working in a catechu or cutch bath and then in a bi- chromate bath. Bismarck-brown on a tannin mordant, and direct browns, are also used. Purples and lilacs are obtained from alizarin on an iron mordant, with basic colors, as methyl or Hofmann's violet, on a tannin mordant, and direct dyes. Red. The fastest red dye is alizarin or Turkey red. The process is rather com- plicated, involving working in a specially prepared oil, aluminum mordant, steam- ing, dyeing with alizarin, and dunging. Reds are produced on goods impregnated with an alkaline solution of B naphthol by passing through a bath of diazotized para, with aniline or naphthylamine. Blue. The best blue in respect to fast- ness is indigo. The coloring constituent of indigo is indigotine. Dyeing^ of WooL — All the coloring mat- ters obtained from natural products men- tioned in connection with cottoa are ap- plicable to wool, and in addition rochineal is considerably used. Cochineal vith a tin mordant gives a very brilliant starlet. The basic colors dye wool without the aid of a mordant. Direct colors are appli- cable to wool. Aniline black is not applicable. Dyeing of Silk. — Black is the most im- portant color dyed on silk. In dyeing the object is usually to add weight to, or "s*^ijff," the fabric. Up to the time of the outbreak of the World War, the manufacture of dyes was practically in the hands of Germany or of German controlled organizations. The embai'go on the importation of German goods, therefore, created a very serious situation in the United States and Amer- ican chemists at once set themselves zealously at work to invent and prepare dyes which should take the place of these formerly obtained in Germany. At first the results were unsatisfactory, but by 1919 the dyestuff industry had reached such a successful basis that it was able to manufacture practically all essential dyes. In that year not less than 1,733 chemists were engaged in research and the industry required the services of over 20,000 employees. The total output of nearly 200 firms was over 50,000,000 pounds, with a value of nearly $70,000,- 000. In March, 1918, the American Dyestuff Manufacturing Association was organized. At an exhibition held in New York City in the same year, samples of dyeing from about 50 American dyestuffs were shown. These samples were .sub- jected to most severe tests, and by com- parison with German dyes, established the superiority of the American product. The production of coal tar dyes in the United States in 1918 was about 4ri,000,- 000 pounds. The imports in 1915 amounted to practically the same figure. There were exported in 1918 American dyes to the value of nearly $12,000,000; in 1920 it amounted to $25,792,565. DYER, ALEXANDER BRYDIE, an American soldier, born in Fayetteville,^ N. C, in 1852. He graduated from the United States Military Academy in 1873 and in the same year was commissioned 2d lieutant of the 4th Artillery. He rose through the various grades, becoming colonel of the artillery corps in 1907. In 1913 he retired from active service. He participated in campaigns against the Indians and in the Philippines. He also served on the Mexican border in 1913. He was the author of "Handbook for Light Artillery" (1896). DYER, MARY, a Quakeress who suf- fered persecution under the laws in the early days of Massachusetts, when mem- bers of that sect were excluded from the State under penalty of death. She was imprisoned, tried, and condemned to be executed; was reprieved on the scaffold, and forcibly taken out of the State. Her religious enthusiasm, however, was so great that she returned and was hanged on Boston Common, June 1, 1660. DYERSBURG, a city of Tennessee, the county-seat of Dyer co. It is on the Illinois Central, the Birmingham and Northwestern, and the Chicago, Mem- phis and Gulf railroads, and on the Forked Deer river. It is the center of an important agricultural region and has an important trade in cotton, wheat, and corn. Its industries include a cotton- seed-oil mill, saw, planing, and flour mills, wagon factories, pressed brick fac- torv, grain elevator, tobacco factory, etc. Pod. (1910) 4,149; (1920) 6,444. 29— Vol. Ill— Cyc