Nearly all of the sisal of commerce is cleaned by machinery. The different kinds of machines are all similar in principle. The fresh green leaves are fed sidewise at the rate of 10,000 to 30,000 per hour, and the green pulp crushed, beaten and scraped away by two or three rapidly revolving drums, against which first one end of the leaf and then the other is pressed by means of adjustable curved aprons. In some machines, streams of water play on the fiber as it passes from the scraping wheels. It is taken directly from the machine to the drying-yard, and, when dry, is baled for mar ket, usually without sorting, as it is rather uni form in quality.
The yield of fiber ranges from 3 to 4 per cent of the weight of the green leaves. The average yield of clean, dry fiber is usually between 500 and 1,000 pounds per acre.
Sisal is used most extensively for binder twine. It is also used for lariats and general cordage of one inch diameter and under for use on land. It kinks in pulley-blocks and rots in salt water, hence is not suitable for hoisting-ropes or marine cord age. It is heavier than abaci, and its working strength is about one-third less than that of current abaci rope of the same size and type.
The increasing importance of sisal in our fiber industries is indicated by the following table, showing the annual imports and increasing values during the past ten years : The fiber known commercially as New Zealand hemp and New Zealand flax is obtained from the leaves of the Phormium hemp plant, Phormium tenax, Forst., belonging to the Liliacece or Lily family. Neither the plant nor the fiber has any resemblance to hemp or flax.
The plant is similar in habit to the common blue flag or iris, but much larger. Its many coarse, grass-like leaves, one-half to one and one fourth inches wide and three to twelve feet long, grow in dense clumps from perennial roots. A flower-stalk bearing lily-like flowers grows at length from the center of the leaf-cluster. The old roots in the middle become weaker and die, and the outer plants in turn become new centers of growth. Many different varieties are recognized, varying in length and width of leaves, and in habit as well as habitat.
The plant is native in New Zealand, and is dis tributed in many parts of Australasia. It has been introduced as an ornamental in California and the southern states, and also in Europe, even as far north as Ireland and Scotland. It is cultivated for fiber-production on a commercial scale in New Zea land, and to a small extent in southern Europe. It
is the only important hard-fiber plant of the tem perate zones. In New Zealand it grows between latitudes 35° and 45°, where it is subject to frost and snow, but it will not endure the more severe winters of our northern states. It grows best in a rich, porous, sandy or loamy soil, moist but with good drainage. Some of the varieties will grow in swamps.
It is propagated by transplanting roots. The leaves are cut about once each year, and the fiber is cleaned in part by machinery. The machines thus far brought out leave the fiber but partly cleaned, requiring considerable hand-work to pre pare it for market. Under favorable conditions, the plants yield 800 to 1,200 pounds of fiber per acre.
The fiber is five to ten feet long, reddish yellow or nearly white. In color and appearance it resembles aback but it is much softer, more flexible, usually more finely subdivided and less strong. It is some what elastic, a valuable quality in tow-lines, and it is less injured by salt water than other com mercial hard fibers aside from aback It is used for fodder yarn, lath yarn, and either mixed with sisal or abaca or alone for binder twine. In New Zealand, and also in Europe, it is made up into a great variety of woven goods.
It has been quoted in the New York market at one-half to one cent per pound less than sisal until recently. The demand for it is gradually increasing.
Mauritius hemp (Fig. 402).
Mauritius hemp is a hard fiber obtained from the leaves of the Mauritius fiber plant, Furcraw fcetida, Haw. (F. gigantea), belonging to the Amu ryllidacece or Amaryllis family.
Aloes vert, as the plant is called in Mauritius, is a perennial, with a rosette of sixty to eighty erect or spreading, straight, rigid leaves, six to ten inches wide, and four to eight feet long, similar in appearance to agave leaves, but usually thinner above the base in proportion to their size, and somewhat plicate toward the apex. The terminal spine is rather weak and the marginal spines weak and irregular, or usually absent. The flower-stalk, attaining a height of fifteen to fifty feet, bears a rather loose panicle of drooping, light yellowish green flowers, followed by bulbils. Suckers are produced from the roots, and if the young flower stalk is broken, suckers are produced in abundance from adventitious buds.