. Bulletin of the Department of Agriculture. Agriculture; Agriculture. GROUND-WOOD PULP 49 MICROSCOPIC COMPARISON OF GROUND-WOOD FIBERS. Plates IV to XII are photomicrographs of the ground-wood fibers obtained from the various species tested. It is not possible, of course, to gauge accurately from such photographs the pulp-making qualities of the fibers. Length of fiber does not necessarily mean strength, for a stronger pulp can be obtained from fibers which, though quite short, will felt well. Steamed white birch pulp, for example, will test as high in strength as longcr-fibered material
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. GROUND-WOOD PULP 49 MICROSCOPIC COMPARISON OF GROUND-WOOD FIBERS. Plates IV to XII are photomicrographs of the ground-wood fibers obtained from the various species tested. It is not possible, of course, to gauge accurately from such photographs the pulp-making qualities of the fibers. Length of fiber does not necessarily mean strength, for a stronger pulp can be obtained from fibers which, though quite short, will felt well. Steamed white birch pulp, for example, will test as high in strength as longcr-fibered material from the pines, larches, and hemlocks. However, the photographs make it possible to compare the characteristics of the fibers of one kind of wood with those of another kind, especially since the lodgepole pine,. Fig. 37.—Loblolly pine (Pinus txda). western hemlock, western larch, red fir, balsam, white birch, jack pine, hemlock, and tamarack were ground under the same conditions of pressure, speed, surface of stone, etc. For some of these species photographs of both cooked and uncooked fibers are shown. The cooked-wood specimens were not treated in the same manner, nor were they ground under like conditions. In the case of birch (PI. IV) it will be seen that the uncooked pulp is very short and contains much wood flour, while the cooked fibers are fairly long and very fine. When run into paper without the addition of sulphite the steamed pulp showed a strength under test of point per pound and points per thousandth inch of thickness. 14852°—Boll. 343—16 1. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States. Dept. of Agriculture. [Washington, D. C. ?] : The Dept. : Supt. of Docs. , G. P. O.
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