Cotton linters dewaxed with benzene and alcohol possess a slightly expanded structure attributed to the swelling effect of the alcohol. Storage causes a partial collapse of the linters especially so when moisture is present. Wetting with water followed by rigorous drying produces a marked reduction in accessibility, but with each additional wetting-drying cycle accessibility of the dried linters increases slightly as measured by reaction with thallous ethylate in ether, a nitration mixture, and in hydrogen-deuterium exchange. Differences in nitration found for limited reaction times are obliterated when these reaction times are extended. Increasing accessibility due to repeated wetting and drying is accon~panied by lower water sorption and smaller heats of wetting. This anomaly is due to the fact that cellulose sanlples obtained by alternately wetting and drying dewaxed linters, when stored with a desiccant, compete for the limited amount of water present and adsorb moisture in proportion to their accessibility. Upon further exposure to water the sample of least accessibility, having adsorbed less water, can now adsorb to a greater extent than do the linters of somewhat greater accessibility.The evidence indicates that the difference in accessibility occasioned by repeated wetting and drying is of a physical rather than chemical nature. INTRODUCTIONThe accessibility of cellulose to reagents is a matter of colisiderable practical and theoretical importance and in recent years has been given a great deal of attention (6,12,16,19,21,28). I t has been shown quite conclusively that this accessibility is influenced by the previous history of the cellulose sufficiently that uniform reactivity is obtained only by the observation of great care in the choice and processing of the raw material (14, 25).The association of cellulose with water throughout most of its history has provoked enquiries regarding the influence that water has upon the properties of cellulose. I t is generally believed that water itself exercises only a swelling effect, producing nothing more than an increase in the amount of accessible cellulose a t the expense of that portion less highly organized. However, recent work indicates that a slight change in dimensions of the unit cell occurs when dry mercerized ramie, spun viscose, or regenerated acetate fibers are wetted (15). Furthermore, lengthy exposure of wet cellulose t o oxygen (air) or ozone is reported to produce some degradation of the macromolecule (3,4). The removal of water from cellulose by direct drying methods is accompanied by a decrease 1 n/Ia?~uscript

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