INDUSTRIAL AND ENGINEERING CIiEhfISTRY
December, 1930
(2) For this type of oil the number of carbon atoms in naphthene rings may he determined from the molecular weiEht and densitv. (3) viscosity index may he used as an indication of the chemical structure of the oil and for that reason should serve as a basis for the correlation of the various physical properties of lubricating oils. Y
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Literature Cited ~aem. ~&rei.Ei - ~ . ,~~6 , 8 1 ,8(1929) ( 2 ) Findlay, "Practical Physical Chemistry," Longmans. 1925 (8) Fisher, "Laboratory Msnual of Organic Chemirlry." Wiley, 1924. (4) Kyropoulos, 2. phyiik. Chem., 144, 22 (1929). (j) Mabcry. IND. 1233 (19~3). ( 6 ) ~ a r c u n r o n11fiii. , .M~rrri=ipruiunaromr,40,308 (19221. (7) Znl'kind, Pcirolevrn Shale . I(Ruisio), Ill, 154 (1922): J . Insf. Pibo[rum Tach., 9. l57A (19221.
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N e w l y Discovered Microscopic Structural Units of Wood Fibers' Geo. J. Ritter and R. M. Seborg U. S.Fonasr PXODUCTS LABORATOXY, MAUISON,Wrs
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ESULTS published by Ritter (1) regarding the dissection of wood fibrils by chemical means showed that the smallest structural 1mit.s of the vood fiber which had been isolated at that time were fusiform bodies. They are short, spindle-shaped units which, whcn arranged parallel to one anot,her with an overlapping of the pointed ends, form the fibrils. The fibrils are long, slender, filament-like structures, arranged to form the fibers. Careful microscopical examination of the fusiform bodies after various treatments suggested that they are composed of still smaller structural units. A t the bime of the meeting of the American Association for the Advancement of Science, Des Moines, Iowa, December, 1929, sufficient progress had been made in the study to warrant tlie following prediction (3) :
Optical Properties l'reviously described structural cellulose units ( 2 ) sliowcd between crossed Xicol prisms an inmasing degree of sharpness in the angles of minimurn and maximum luminosity with decreasing size of unit. I n other words, the parallelism of the crystalline structure which exhibits the effect in polarized light was greater in the smaller units. Such a condition would be expected from the fact that t,here is less opportunity for variation in the parallelism of crystalline arrangement in the smaller than in tlie larger units which are composites oi the small ones. It was found, however, that between crossed Nicol prisms the isolated spherical units were uniformly luminous in all positions, indicating
I t is quite probable that still smaller microscopic building units in the fusiform bodies will be discovered in the near future, and that the source of thc optical properties described in t h e preceding paragraphs will then be found in the newly discovered units.
Recently, separation of the fusiform bodies into smaller units was accomplished a t the Forest Products Laboratory, but suitable photomicrographs of the results were obtained only after much experimcntation aiddifficulty. Materials The materials used in this study consisted of two batches of mixtures of fibrils and fusiform bodies vhich were prepared from delignified white spruce fibers. One batch was prepared by the sulfuric acid method; the other, by chlorination in the sunlight. Procedure a n d Results Fleure I-Spherical
Small samples of the mixtures containing fibrils and fusiform bodies were treated on glass slides wit11 phosphoric acid (78 per cent) a t approximately 75" C. When slight pressure was applied to the cover glass over the specimen, the fusiformbodies separated into smaller units. The newly discovered units (Figure 1) are spherical in form when detached from the mother unit. They are approximately 0.45 micron, or 4500 A. in diameter, which is nine times the length of the cellulose micelle rcrcaled by the x-ray diffraction pattern. Since those units h a ~ cnot been observed in the fusiform bodies, their original fonn is unknown, but from observed optical properties it would seem that tlie shape is other than spherical. 1 Received September 20, 1930. Presented belore the Division oi Cellulose Chemistry a t the 80th Meefine of the American Cheoilcal Society, Cincinnati, Ohio, September 8 t o 12, 1930
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a random arrangement of tlie crystalline structurc. Such a disarrangement in tlic internal stmcture of the new units would result during the deformation of an angular body to a spherical one. This conclusion is confirmcd by the fact that it would be impossible to build up a solid structure with spherical units. The resu1t.s lierein described suggest a future study in which the spherical units may be isolated under minimum swelling condit,ioiis, so as t,o reduce the possibility of deforming them. If the s8mc units can be obtained by such n method, which the writers believe is possible, their optical properties sliould be siioilar to those of tlic fusiform bodies. Literature Cited (I! ~ i t t e i IN". , RNO. C H E W . . a i , 289 ( 1 ~ 2 9 ) ?a! R i t t r i . 3 . P'o"?stry, 28. 533 :l9:3'>!
