By far the largest part of the yarn is woven into plain cloth, but a considerable quan tity is used as warps in woolen and worsted goods or for knitting into underwear, and a large part water, washing it with pure water, then treating it with dilute sulfuric acid and again washing it with water. The treatment causes both a chemical and a physical change in the constitution of the fiber. The fiber before treatment is flattened and somewhat twisted, but by mercerization it becomes rounded into cylindrical shape, the walls of the tube become thicker and the cavity is correspond ingly reduced, the surface becomes smoother, the length of the fiber is reduced, it assumes a spiral shape and acquires greater strength. The industry has become very important. According to the Twelfth Census, over 7,973,000 yards of cloth and 1,600,000 pounds of yarn were mercerized in 1900, causing an additional value of $697,490. Egyptian and sea-island cottons are best adapted to mercer ization, as they have long, silky fibers which are more uniformly acted on.
Great Britain is the chief seat of cotton manu facture. The United States ranks second. For a long time the industry in this country was mainly confined to the New England states, but in recent years it has rapidly risen into prominence in the southern states. Since the year 1890, this section has probably enjoyed a greater activity in the development of the industry than any other section in the world. The achievements in those states have been so marvelous as to cause serious alarm in New England and Great Britain. However, the southern mills are engaged mainly in producing yarn and cheap grades of goods ; therefore their products are not nearly so valuable as those of New England and Great Britain. The following tables will give an idea of the status of the industry, as shown by Shepperson's "Cotton Facts" and the United States census report: of the product of sea-island cotton is converted into sewing thread.
Within recent years the process known as mer cerization has become an important adjunct to cotton manufacturing. It consists of subjecting the cotton to the acticn of caustic soda dissolved in By-products.
Until comparatively recent years, cotton was grown entirely for its fiber, but now the by products represent a large percentage of the total value of the crop. The roots supply a chemical substance similar in its action to ergot ; the bark is used to some extent for making bagging, coarse carpets and the like : but by far the most valuable by-products come from the seeds. For a long time growers either threw them into a stream or dis pesed of them in some other convenient way, as thy were not regarded as having any value. Later they were used for manure ; finally the value of their oil was discovered, and a great industry has been developed in extracting and refining it.
About 7 per cent of the seeds produced are used for planting, a large quantity are still used for manure, but the bulk of them are run through the oil mills. The quantity thus consumed from the crop of 1904 was 4,032,375 tons, or 63.2 per cent of the total supply. The average price per ton paid to growers for them this season (1904) was $14.15. At this rate the value of the entire crop of seed was over $90,000,000.
When the seeds reach the oil mills they are reginned for the purpose of removing the fuzz which covers them. This fuzz is called linters. It amounts to about thirty pounds per ton of seed and is used in upholstering, making cheap felts, and the like. The seeds are ther run through a machine which separates the bulls from the kernels. The hulls are used very largely for cattle food ; how ever, they have some other minor uses. The ker nels, "meats," are steamed or cooked and then placed in presses, where they are subjected to an enormous pressure for the purpose of extracting the oil. The residue is called oil cake. It is ground into meal and used as a concentrated cattle food and as a fertilizer. A ton of seed yields thirty eight to forty-five gallons of crude oil, which is refined in mills especially constructed for this purpose. This oil has a great variety of uses— the more refined part being used for human food under various names, while the less refined part is used for soap stocks and in various other manu facturing processes.
Cotton breeding, Breeding is one of the important factors in the production of a good cotton crop, which is almost wholly neglected. The great majority of cotton planters ordinarily nse any cotton seed without regard to variety and without practicing any selection. On the seed depends the crop, and it is just as important to use good seed as it is to cultivate and manure the crop. The results of careful experiments have shown that by sys tematically selecting and improving the seed, the yield can be greatly increased with but little extra cost (Fig. 364). In any general field crop where the margin of profit is so slight as in cotton, it behooves the grower to use every possible method to increase the profit, and no cotton-grower can afford to neglect the proper selection of the seed which he expects to plant. Every cotton-grower, in attempting to improve his crop, should test comparatively a number of the standard varieties in order to determine what variety or varieties do the best under the local conditions presented on his plantation. This test of varieties is important, and should precede any work of breeding, as it is important to start the breeding with the best available foundation stock.