WOOL is a variety of hair (q.v.). The term hair is applied, in ordinary language, to a smooth, straight-surfaced filament like human or horse hair, without serrations of any kind on its surface. Wool, on the other hand, is always more or less waved; besides which, externally each woolly filament is seen tinder the microscope to be covered with scales overlying each other, and projecting wherever a bend occurs in the fiber. Upon minute points of difference the value of wool chiefly depends, especially with regard to the great variety of its applications. If each fiber were straight and smooth, as in the case of hair, it would not retain the twisted state given to it by spinning, but would rapidly untwist when relieved from the force used in spinning; but the wavy condition causes the fibers to become entangled with each other, and the little projecting points of the scales hook into each other, and hold the fibers in close contact, Moreover, the deeper these scales fit into one another, the closer becomes the structure of the thread, and consequently of the cloth made of it. This gives to wool the quality of felting (q.v.). By combing, or drawing the wool through combs with angular metal teeth, some of the scales rre removed, and the points of many more are broken off, so that wool which has been combed has less of the felting property, and is consequently better adapted for light fabrics; and yarn made of such wool is called worsted, and the cloths made of it worsted goods. But such is the variety of wools obtained by careful breeding and selec tion, that these differences can be got without combing, sonic wools being found to have naturally fewer serratures, and a less wavy structure, than others. These are conse quently kept separate, and are called combing-wools ; whilst those which are much waved, and have ninny serratures, are called carding-wools, from their being simply prepared for spinning by carding-machines. The serratures or points of the scales are exceedingly small, and require the aid of a good microscope to see them. They vary from 1200 up to 3.000 to an inch.
Wool is the most important of all animal substances used in manufactures, and ranks next to cotton as a raw material for textile fabrics. Its use as a substance for clothing is almost universal in the temperate regions of the globe.
Previous to 1791 British woolen cloths were made almost wholly of native-grown wools. At that time the whole supply of the country could not have much exceeded 100,000,000 lbs. The merino wool of Spain then began to displace them in the best kind of goods, and the imports from that country reached their maximum in 1805, being in that year 7,000,000 lbs. Before 1820 the German wool had begun to supersede the Spanish, and was imported largely till 1841. After that, the cheaper wool of the British colonies to a great extent took the place of the German, and the latter is now chiefly used for only the finest cloths.
Wool varies in character according to the peculiar breed of sheep which yields it, and also with the nature of the soil, food, shelter, and climate. Ina wool of first-rate quality, the fibers are fine, soft, elastic, sound, of good color, and free from deleterious or troublesome impurities: the commercial value of any sample depends, therefore, upon the extent to which it possesses these properties. If it be a combing-wool, it will also depend upon its length of staple.
For technical purposes, shorn fleeces are divided into two classes, one called hogs or tegs. the other wethers or ewes. The former are the first fleeces shorn from the sheep, the latter are those of the second and succeeding years; but the meaning of these terms varies a little in different districts. The fleece of yearlings are, as a rule, longer in the staple, and otherwise of superior quality to the wool of older animals. In the s. of England, it is Customary to clip lambs, and the wool so obtained is called shorn lamb's wool. Wool taken from the skins of slaughtered sheep is called skin-wool or pelt-wool, and is of a more variable quality than fleece-wool, on account of its being obtained in all stages of growth.