Wool, even the finest, has a high tensile strength and the fibre is strong throughout its length. Sometimes tender wool results from per inch. Some of the coarse inferior wools do not exceed 500 serrations per inch. There is also much difference in the size of the in dividual fibre The finest Merino wools will vary from 1/2000 to 1/4000 of an inch, while a maximum diameter of 1/250 of an inch is ob tained in the coarsest wools.
The crimp or curliness is an important property of wool fibres, since it plays a large part in the spinning of yarn and the felting of cloth. The curly fibres will spin tivi.-r and make a better thread than the straighter ones. In the lack of proper foods, severe climatic con ditions or sickness. This is wool having a weak spot at some point in its length. Dead fibres arc sometimes found on poorly-bred sheep and are known as *kemps" and referred to as kempy wool. Dead or weak fibres are highly unde sirable as they will not stand the strain which fibres must undergo in spinning, but will break instead of stretching.
The elasticity of wool is one of its most im portant qualities, giving to wool its soft feel and to the finished cloth its characteristic pliabil ity and softness. Many of the finer wools will stretch 35 per cent of their length without breaking. There are many shades of wool found throughout the world, including black, white, brown, fawn, yellow and gray shades. White is by far the prevailing color. The colored wools are made use of in the spinning, knitting and weaving of rough yarns, knitted shawls and tweeds.
From a chemical standpoint wool is a highly complex substance. There are three components which go to make up the raw wool. All wool in its natural state contains a fatty or greasy matter called yolk. This is secreted from the skin and covers the fibres. It serves to lubri cate the fibres, prevents their matting together and protects them during growth, and pro tects the tierce to a great degree against injury by outside agencies. It is a natural impurity of the wool. There is also the wool fat which permeates both the yolk and the fibre, and the wool fibre, which is really a more complex chemical compound than either the yolk or the wool fat.
According to Hummel, the composition of the average wool is as follows: Moisture, 4-24 per cent ; yolk, 12-47 per cent; dirt, 3-24 per cent; wool fibre. 15-72 per cent.
According to Bowman, the composition of the wool fibre is as follows: Carbon, 50.8; hydrogen, 7.2; nitrogen, 18.5; oxygen, 21.2; sulphur, 23.0.
It is said to have a probable empirical formula of C.Fli.i,NiSOis. However, this con veys but a small idea of its complexity. The wool fibre belongs to a class of chemical com pounds known as proteins. The complexity of this group of compounds is clearly seen when we consider the fact that on hydrolysis they arc usually broken up into 17 distinct units known chemically as amino acids.
Wool as distinguished from cotton burns slowly with an odor characteristic of burning animal matter such as horns and feathers, leav ing at the end of the fibres a small crusty globule. Cotton on the other hand burns without odor to a white ash. Wool is readily dissolved by hot caustic soda solution, while cotton is practically unaffected. This, although a simple test, is an important one for use in determining the presence of cotton, one of the most common adulterants found in woolen goods.
Manufacture of Wool into Cloth.— When wool is received at the mill, it is generally in a graded condition, having either been graded at the shed where shorn or at some one of the numerous wool warehouses. The first step in the preparation of the wool at the mill is to remove the string and open up the fleece and tear out all hard paint which will not scour out when the fleece is cleaned. The fleece is then spread on a table, the centre of which is covered with a wire netting. This allows the sand and dirt to pass readily to the floor. The sorters tear the fleece apart, separat ing it into piles according to its different quali ties. As a rule the best wool is obtained from the shoulder and sides. That from the fore part is irregular and sometimes filled with burrs, while the loin wool is shorter and coarser. The wool from the britch and hind quarters is the coarsest, while the wool from the under side of the throat is liable to be short, worn and dirty. The wool on the shoulder is tittest and superior in soundness of fibre, softness of curl and evenness of length.