X-RAY DIFFRACTION PATTERNS FROM PLANT FIBERS.
The rather long discussion just given seemed necessary in order to establish certain points before attempting to develop the lattice structure and before working out the identity of the structural unit of the ramie fiber. 1. Certain planes, 6.10, 5.40, 3.98, etc., as given in Table I, run lengthwise of the fiber; that is, they are parallel to the long axis. 2. These planes are in agreement with the assumption that one set, either the 6.10 or the 5.40 is tangential to the fiber and forms concentric cylinders, with the long axis of the fiber as the long axis of the cylinders; the other set, either the 5.40 or the 6.10. cuts the former at right angles and therefore its planes are radial with respect to the fiber, theoretically all of them meeting at the long axis, as indicated in the cross-section of a fiber in Fig. 3. 3. Other planes, 5.15, 3.40, 2.58, etc., as given in Table III, are transverse planes which form right angles with the long axis and therefore with the planes of Table I. 4. All of the planes are composed of reflecting units, probably groups of atoms, located at the intersections of the planes. This being the case, other reflecting planes must occur at other angles to the long axis. This prediction is verified by the lines given in Table IV. 5. The structural units in the wall of the fiber thus form a space lattice, the elementary cell of which is an orthorhombic structure. 6. Comparatively little can be said as yet concerning the structural unit. The unit is very probably composed of a group of atoms which are more or less closely packed together. If the groups were visible they would appear, in a cross-section of a fiber, as closely packed groups of atoms, 6.10 A.u. from center to center of groups in one direction, and 5.40 A.u. at right angles to that. In a longitudinal section, however, they would appear less compact and might even lose the appearance of groups in forming long strings of atoms which would extend lengthwise of the fiber. By establishing the positions of the planes in the wall of the fiber, as in Tables I, III, and IV, it would seem that all dimensions of the elementary cell, and the size and character of the structural unit, could be determined. Work along these lines is now in progress.
Sponsler
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OL
University of California, Southern Branch, Los Angeles.