From z-ray dulu it has been calculated that the dimensions of the unit cell of cellulose are 8.3 X 10.3 X 7.9 A. (2) and the prabuble dimensions of the micelle are appraxinzately 50 X 50 X 500 A. (3). The zpacing of the striae seen wcth the Spierer lens is approximately 96UO A., or many times any dim&ions of tlie micelle as calculated from the a?-ray data. Furthermore, it is nn longer possible to accept the measurements fram Spierer micrographs as those of any unit churacterislic of the material under observation, for it is inconceitable that the unit would have a dimeriaion common to so many and sa diwrse subslances. Apparently, the striae observed with the Spierer lens are diffraction bunds. Time has not aermilled a satisfactory investigation of their cause or causes. There is as yet no sallsfuclory ezplanation of the differences in cellulose fibers rent origins, $, in fact, such differences Further in~~e.s(iaat~ori 111 fhir direction ttempkd.
Dark-Field Study of Fibers A. T. CLIFFOHO A
F. K. CAMERON
~ D
University of North Carolina, Chapel
Hill, N. C.
ECHNOLOGISTS often assume that cellulose from certain sources is not suitable as a raw mterisl for industrial purposes on account of its ult micellar structure. Sanders and Cameron (4) the cellulose of cotton stalks and CUSDS is the sa cotton lint, spruce, pine, and poplar. Several t regenerated cellulose and cellulose derivatives were p From the different kinds of cellulose, and their x-ray diffraction patterns were studied. In every case cellulose which had differs from the ordinary inimersion ohjective in that the been given chemical treatment showed the same diffraction vertex of the front lens is ground off and silvered. The light which penetrates the objective over this area is reflected pattern, irrespective of the source. To check the work of Sanders and Cameron, x-ray spectro- at this mirror to the obj as incident illumination. In grams were made with longer exposum for a
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OF RILIUHT-FIELD AND S3'1ElGX< PHoTOMICROQRAPIiS Since tlie unit cell is the same no matter what the source, a possible explanation of vasiations of properties of different types of cellulose might be its micellar structure. Ikcently, a new type of dark-field microscope, the Spierer ultramicroscope (6),has been developed by which, it has been claimed, the micellar structure of cellulose can be detected. The Spierer ultramicroscope is an ordinary microscope equipped with a Spierer lens (objective) and a special condenser. The essential part is the immersion objective which
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