CALORIMETRIC DETERMINATION OF SURFACE-AREAS - POSSIBILITIES OF A MODIFIED HARKINS AND JURA PROCEDURE

The immersion calorimetric method of Harkins and Jura for determining specific surface areas of powders was reexamined in the light of results obtained with 11 powders of different chemical nature and having specific surface areas ranging from 0.6 to 129 m2 g-1. Microcalorimetric determinations were performed, using water (and, to a smaller extent, butanol, pentanol, and n-decane) as the adsorbate and as the immersion liquid. Less than two water layers appears to be enough to screen" completely the solid surface. This leads to a modified procedure which avoids the previous shortcomings arising from interparticulate condensation and also from the thickness of the preadsorbed layer. The experimental reproducibility is of ±0.1 m2 g-1 ± 1% (of the measured value). © 1979."