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the material is mashed, rather than torn as in the burr stones. There were in the United States in 1900 about two and one-half as many pairs of rolls as runs of stone.

The separation of the different portions of the grain is accomplished partly by gravity and partly by bolting cloth of different sized meshes. The endosperm breaks up into spherical or cubical particles, while the other portions are more or less flattened, forming comparatively larger dimensions and having a less specific gravity.

177. The Purifier.—Formerly, and by what is now known as the old process of milling, wheat was merely ground as finely as possible and then bolted. By the introduction of the middlings purifier two steps have been added to the process, viz., puri

The middlings purifier, which has greatly influenced cleaned wheat, whether

granulated coarsely, resulting in three products: flour of a low grade, middlings and bran. The middlings are now put through the purifier in order to extract dirt, bran and fuzz. They are then ground by a more or less gradual process, depending upon the construction of the mill, and finally bolted. It is from these middlings thus purified that the highest grade (so-called patent) of flour is made.

The introduction of the purifier in 1870 revolutionized the process of milling, and made the use of the hard spring wheats of the Northwest of the highest value, while formerly they were of the least value for the production of high grade flour.

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the wheat industry.

rolls or burrs are used, is first ground, or rather

178. The By-products of Wheat consist of the outer coats, the aleurone layer, the embryo, and such portions of the endosperm as cannot, by the common process of milling, be removed from the aleurone layer. There are a number of grades of these by-products, depending principally upon the relative proportion of outer coats to endosperm. The common grades are bran, shorts and middlings, while a low grade of flour known as "red dog" or "dark feeding flour" is sometimes sold for feeding purposes. Bran and shorts are essentially the same, except that in the process of milling the outer coats in the latter are more thoroughly pulverized; while the middlings contain a larger portion of the endosperm, and are therefore more starchy and dense than bran or even shorts. In the bran the outer coats are in large flakes, with portions of the aleurone layer and endosperm attached, thus making a light, bulky product. While the embryo itself constitutes a much smaller proportion, in the process of milling about eight per cent of the grain is removed as embryo. (64) Care is taken to remove these embryos, because their introduction into the flour injures its keeping qualities, and its nitrogenous compounds are not suitable for breadmaking purposes.1 On account of their high nitrogen, phosphorus and fat content, they are a valuable addition to the by-products. They are sometimes found in the bran and sometimes in the middlings. As in the process of milling they are separated from the rest of the products, it is optional with the miller where they are put. The yellowish flattened embryos are readily recognized in the mill products.

179. Composition of By-products. — The analyses that have been compiled show very great variations in every constituent in different samples of bran, shorts and middlings.2 Taking them as a class, the ash has been found to vary from 1.4 to 7.8 per cent; the protein from 10.1 to 20.0 per cent; the crude

1 The Chemistry of Plant and Animal Life, p. 307. » U. S. Dept. of Agr., Office of Expt. Sta. Bui. 11.

fiber from 1.3 to 15.5 per cent; nitrogen-free extract from 45.5 to 70.9 per cent; and fat from 1.5 to 7.0 per cent. The following table shows the average composition:

[table]

High protein content may be accompanied with high content of crude fiber and low content of starch due to exhaustive milling, and equal protein content may result in two samples of bran unequally milled because of differences in the protein content of the wheat used.

The total phosphorus in wheat bran has been found by the New York (Geneva) Station to be 1.22 per cent, as compared with 0.7 per cent in malt sprouts and 0.4 in oats. It is also more soluble, eighty-seven per cent being soluble in water, as compared with eighty-one per cent in malt sprouts and fifty per cent in oats. Practically all of the soluble phosphorus of wheat bran is of an organic nature.1

180. Food Value of By-products.—Within the memory of many persons now living, the bran spout of grist mills emptied its contents into the river. The by-products of wheat are now among the most highly prized stock foods for all classes of domestic animals. While its value is undoubted, the digestibility of bran is not much greater than that of hay of good quality. The esteem in which it is held sometimes causes it to be an expensive food compared with others that are available.

1 N. Y. (Geneva) Bui. 250 (1904), p. 169.

Middlings usually sell for about five per cent more and shorts for about five per cent less than bran. So far as the ruminants are concerned, these values are not the result of experimental evidence. For ruminants and horses, the mixing of bran and middlings is probably advisable. Shorts are to be avoided on account of the practice of millers in adding the sweepings and other inferior products.1 The Maine Station has shown that for swine, middlings are much more desirable than bran, undoubtedly due to the less percentage of crude fiber in the former.2

II. PRODUCTION AND MARKETING.

181. Wheat Crop of the World.— The production of wheat in the world has varied during the years 1898 to 1902 inclusive from 2,610 to 3,124 million bushels per annum, the average yearly production being 2,869 million bushels.

The following table gives the average annual production by half decades by continents in million bushels:

[table]

This table shows that, compared with the preceding five years, Australasia has made the largest percentage increase. North America has made the largest actual increase in the production of wheat. The production of wheat in Africa has remained stationary, while in Asia it has fallen off seven per

1 W. A. Henry: Feeds and Feeding, p. 130. » Me. Rpt . 1889, p. 82.

cent. The increased production in North America has been greater than all the rest of the world combined.

Notwithstanding the great development of wheat production in other sections of the world, Europe still produces more than half the wheat of the world, and notwithstanding the fact that much of Europe has been cultivated for ages, the production of wheat continues to increase in a substantial manner. Russia, France and Austria-Hungary are the largest wheat producing countries of Europe. Second in importance to these are Germany, Spain and Italy. The United States and India are the only other large wheat producing countries. Canada and the Argentine Republic are important on account of having a relatively large surplus for export and on account of the possible future development. The Canadian Northwest is distinguished for its large yield per acre combined with high quality of the grain.

182. Wheat Crop of the United States.—The United States raises the most wheat of any nation on the globe. The largest yield ever produced in a single year was 748 million bushels in 1901. The following table presents the essential statistics for the last three decades, based upon the estimates of the United States Department of Agriculture:

[table]

These figures show a steady decrease in the value of the crop per acre through a decrease in price per bushel. The yield per acre has increased somewhat, due in part, no doubt, to the opening of new sections to the production of wheat which give high yields per acre. The census for 1900 shows that practically all

* Farm price December ist.

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