The term wool is used indefinitely, but is most generally applied to the fine hair of the sheep, and is distinguished from hair solely by being curly and serrated, while the latter is straight and stiff. Animal fibres differ from vegetable fibres in being more flexible, strong, and elastic.

A microscopic examination of wool shows that it is covered by scales closely resembling the scales of a fish; this peculiarity has much to do with its value as a textile fibre, as it is this which gives it the matting or felting quality so necessary in spinning and weaving.

XXVI-A-Chapter-On-Materials-104

ILL. 108. - The Wool Fibre.

The skin of the sheep itself was probably the first covering used by man, and, succeeding that, it is most likely that a fabric was made by pounding the fleece in a damp and heated condition, thereby producing a species of felt or cloth similar, to some extent, to the felts used for hats, carpets, and shoes in modern times. Who first discovered the woolen thread itself is not known, but it may be taken for granted that the readiness with which wool can be made into thread would, at an early period, suggest it as a suitable material for sewing and weaving. In the Middle Ages, Flanders was the great headquarters of manufactures in wool. At various dates Flemish wool workers settled in England and taught the English, as they had also taught the French, the art they had carried to great perfection.

The value of wool depends not only on the fineness, but also on the softness, of it. The finest wool is found, as a rule, in the region of the shoulders and neck of the sheep.

The qualities which distinguish high-class wool are: 1. Weight. 2. Color and Lustre. 3. Length. 4. Fineness. 5. Elasticity. 6. Softness. 7. Soundness and evenness of fibre.

Sheep are sheared once a year. They should be washed before shearing, because of the dust and dirt adhering to the yolk or grease in the wool. After shearing, all stained or seedy places should be removed, which leaves the fleece comparatively free from fault.

It is next sorted; this process separates it into lots according to fineness and length of fibre.

It is then washed or scoured by being immersed in a bath of Chemicals, suited to remove the grease and dirt not taken out in the first process.

It is then dried, after which it again goes through a process of mixing called blending; this consists in mixing the various qualities of wool, so as to bring about the best results in spinning and weaving.

The several qualities of wool are determined principally by the touch. An indication of soundness is uniformity of growth in the several filaments of which the staple is composed. The larger fibres will, of course, sustain the most weight, but the strength of a sample of wool is not judged by the thickness of individual hairs, but by the strength of the lock.

The process of spinning is much the same as in cotton, but after the fabric is woven it is given a hot, soapy bath and subjected to a heavy pressure, which causes the fibre to felt together and to shrink in both length and width. This shrinkage must be allowed for in the weaving.

If the wool has not been dyed in either the fleece or the yarn, it is now ready for dyeing, after which it is put through various finishing touches, which give it the desired gloss and finish that makes it marketable.

Varieties of Wool.

The principal varieties of wool are:

1. Merino, from the Merino or migrating sheep, originally of Spanish origin. It is noted for the weight and fineness of the fleece, and is used universally for fine woolens.

2.  Alpaca, a species of wool taken from native alpacas or llamas, found in the high tablelands and mountain ranges of the Andes in Chili and Peru.

3.   Mohair. The wool of the Angora goat is long, abundant, fine, and silky, covering the whole body of the goat.

4.   Cashmere. The most costly wool in the world is found on the Cashmere goat of the Himalayan Mountains of Central Asia. In the Cashmere goat it is the under coat of wool next to the body that is rich, soft, and silky, almost like down. A fleece weighs but half a pound, but it is very valuable.

Supply and demand. - To-day the population of the world demands two billion seven hundred million pounds of wool per year; of this quantity, Australia supplies one-fourth; Europe, including Russia, one-third; the United States, one-eighth; and following in rank come South America, India, Central Asia, Turkey, China, Canada, and Mexico.

The fact that wool is more impervious to cold than linen or cotton, and that it is a poor conductor of heat, makes it an ideal fabric for underclothing.