mergy changes. It may be iiientionecl, however, that with systenis such as silica-alcohols, or cellulose-nitrogen, where the possibility of chcniical rcaction is much smaller, cwictly the s,iiiie type of have Ixwi obtained. Summary 1. Isoteric heats of adsorption of three aliphatic miities by silica gel were tleterinitiecl by means of adsorption isotherms obtained at 25' and a t 40". 2 The change in the heat content s j , the free ciiergy IF and the entropy A S per inole of adsorbI te were determined. 3. The isosteric heats 'iiid - 1Sobtaincd for the itiitial stages of atlsorptioii were so high as to indic,tte that adsorption 111 this range is not strictly physical. 4. Froin eiicrqy , t i i d cnlropy coiisitlc.r,itions it ,tppears that
