Changes in the pore structure of cotton cellulose resulting from the steps of the wet-fixation process were assessed by measurement of moisture regain, water of imbibition, and dye sorption. These measurements reveal the relative proportions of pore surfaces in the nonswollen state, the pore volumes in the swollen state, and the pore surfaces in the swollen state, respectively. The uniformity of deposition of the methylolated melamine resin was established by both light and scanning electron microscopy; the resin is deposited on fiber surfaces as well as in the internal pores of the fibers. The increases in pore surfaces and volumes in the fixation step, as well as the decreases effected by curing, were determined in relation to the structure of unmodified cotton and cotton treated by a pad-dry-cure process employing both "resinforming" highly methylated hexamethylolmelamine and "crosslinking" dimethyloldihydroxyethyleneurea reagents.

Application of partition chromatography on silicic acid columns of large capacity has made it possible to isolate and identify all of the hitherto undetected non-

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Decrystallized cotton cellulose was found to be have gel permeation properties comparable to those of the highly crosslinked dextran and polyacrylamide gels used in chromatography. Partial separations of pairs of sugars, ranging in molecular weight from 120 to 738, were studied by determining the optical rotations of fractions eluted from chromatographic columns, employing a sensitive automatic polarimeter. The elution volumes of individual sugars of known molecular weights provide a quantitative measure of changes produced in the cellulose polymer structure by crosslinking. A significant difference was found between unmodified cellulose and the same material crosslinked by formaldehyde treatment; although crosslinking reduced permeability to larger molecules, the crosslinked material was found to be more permeable than the untreated cellulose to compounds having molecular weights below approximately 1000.