Adsorption of water vapor by untanned hide and various leathers at 100 degrees F

AdsOJ'ption of water vapor by untanned hide and variou tannages oJ leather was determined at relative humidities rangin g from 0 to 96 percent at 100 F. The Brunauer, Emmett, and T eller equations for adsorption of gases in multimolecular layers we re applied to the data. Adsorp1ion for all of the samples below a re lative humidity of 75 percent is a function of the available surface. Above 75-percent relative humidity, other factors exert an influence, the most importan t of which is probabl.v size of the capillaries. Untanned hide and chrome-tanned leath er adsorb the most water vapor except at relative humidities above 75 p ercen t, at which sol e leather adsorbs more. The behavior of the sole leather in this r egion is ascribed to the prese nce of deliquescent materials used in the fini shing process. The other vegetable-tanned leather s adsorb less mois ture than either hide or chrome leather. Calculated heats of adsorption indicate t hat the affinity of groups for wate r is no t appreciably altered by tanning and t hat the adsorption is physical in nature. M ethod by which the data may be applicd to practical processes, s uch a s fa t-liquoring and tanning, are pointed out.