Page:The American Cyclopædia (1879) Volume V.djvu/659

 DAMASCUS BLADES DAMASKEENING 655 This being a very fusible flux, only about part is employed. Being well covered, te crucible is placed in the fire, and the blast is put on. In 3^- hours the surface is covered with a thin layer of scoriae, on which floats the excess of graphite ; one fourth of it has disap- peared. The metal has acquired a weak dis- play of longitudinal lines, a clear ground, and, if the graphite is good, a certain degree of re- flection. By continuing the fusion four hours the loss of graphite is one third, and the lines are undulating. In 4^ hours half the graphite is taken up, and the lines attain a medium de- gree of coarseness. The crucible generally be- gins to fail at this point, but if it should retain its shape five hours three fourths of the graph- ite will have disappeared, the lines will be reticulated and of medium coarseness, and the scoriae amount to nearly half a pound in weight. By continuing, when - possible, the fusion for another half hour, the graphite will nearly all disappear, the scoriae will amount to two thirds or three fourths of a pound, and the lines upon the steel will become more or less decided, reticulated, and sometimes zigzag. The follow- ing are given as requisites for the best steel : charcoal of the cleanest sort, as pine ; a fur- nace constructed of the most refractory mate- rials ; the best quality of crucibles ; iron also the best, very malleable and ductile ; pure na- tive graphite, or that obtained by breaking up the best crucibles ; flux of dolomite or calcined quartz ; a high temperature ; fusion as long continued as possible. The blast of the furnace is kept on till the fuel is entirely consumed ; and the crucible is not removed until it is cold, or at least black. The cover is then taken off, the graphite removed, the scoriae are broken, and the lump of steel is extracted. When cold, this presents a surface of uniform appearance ; or there may be a depression in the centre if the steel is very hard and shows no reflection ; or if steel of this quality exhibits no outward depression, a cavity may be looked for in the interior of the lump, which is the effect of too rapid cooling, and indicates a very inferior quality. The lump, which weighs about 11 Ibs., is drawn out under the hammer with three to nine heats ; it is then separated into three pieces, each of which is forged anew. Particu- lar care is required in reheating to attain the proper temperature. At a white heat the steel, if hard, will crumble ; if tender, it loses the watered lines. The best steel may be drawn out cold without cracking, and may even be- come red-hot by hammering. In working the bars into other shapes, they ought not to be heated beyond a clear red, and the last heat should not exceed a cherry red. It is well, as the lower part of the lump is always better marked than the upper, to keep the two ori- ginal sides distinguished from each other, that the cutting edge may be formed out of the low- er. The process of bringing out the watered appearance on the surface of Damascus blades is accomplished by the use of a diluted acid, 247 VOL. v. 42 which acts more upon the ground than upon the lines. All acids are not equally suitable for this purpose. Nitric acid acts not only upon the iron, but also upon the carbon, and moreover injures the lustre. Sulphuric acid, having no effect upon the carbon nor the re- flection of the surface, is much to be preferred, especially when it is used in the state of a sul- phate ; and a sulphate of iron which contains a certain quantity of sulphate of alumina is found to produce the best effects. The blade, thoroughly cleaned, is washed with the solu- tion by pouring it over the surface, and when the lines are developed it is repeatedly washed with soap and water, and wiped dry with a cloth, care being taken not to wet any portion after it has been once dried. Some vegetable acids, as lemon juice or vinegar, answer very well in place of the solution of sulphate of iron. The last operation is to rub the surface over with pure olive oil and again wipe it dry. The total expense of the production of blades by these processes is estimated at Zlatust to be about $1 10 a pound. They prove to be of similar properties to those of the famous orien- tal blades, the accounts of which have not been so much exaggerated as is generally supposed. Gen. Anosoff died in 1851, and Atkinson in his work on Siberia says that his successor at the works failed to produce the remarkable blades for which the establishment had become celebrated. The observations of Gen. Anosoff upon the introduction of other metals to alloy the steel are minute, but they are unfavorable to any mixtures with the iron and carbon. DAMASK, a fabric originally manufactured at Damascus, whence its name. It was made of silk, and was distinguished by its ornamen- tal woven figures of fruits, flowers, animals, and landscapes. It is still distinguished by these ornaments, and by the mode in which they are introduced in the process of weaving, though the material of modern damask is often linen, sometimes indeed woollen, or even cot- ton, or a mixture of linen and cotton. The cotton fabric, from its want of durability and beauty, has little to recommend it for this man- ufacture, particularly as it is only by great care and frequent bleaching that it can be made to retain its whiteness. Its peculiar texture is that called tweeling or twilling, in which the warp and the woof cross each other, not al- ternately, but at intervals of several threads. These intervals being at every eight threads in damask, the stuff is called an eight-leaf twill. The linen damasks manufactured at Dunferm- line in Scotland, and at Lisburn and Ardoyne in Ireland, are used chiefly for table cloths and napkins. Diaper is a variety of damask, differ- ing from it by the warp and the woof crossing each other at intervals of five threads. DAMASKEENING, the art of ornamenting iron or steel by inlaying with gold, silver, or some other metal. It is chiefly used for adorning sword blades, guards, and locks of pistols. The most beautiful method of damaskeening con-