... are unconsolidated and non-rigid, but they may be converted into more n g ~ d , ADSORPTION BY POWDERS AND POROUS SOLIDS Table 13 Definitions: porous solids Term Definition Porous solid open PO=... completion and that the monolayer capacity could be derived by application of the Langmuir equation 4 ADSORPTION BY POWDERS AND POROUS SOLIDS Another important stage in the history of gas adsorption. .. associated with adsorption, powders and porous solids are defined in Tables 1.1, 1.2 and 1.3 These definitions are consistent with those proposed by the International Union of Pure and Applied Chemistry