$8-9$ Two samples of silica$-$alumina cracking catalysts have particle densities of $1\mathrm{.}126$ and $0\mathrm{.}962\frac{g}{c}{m}^3,$ respectively, as determined by mercury displacement. The true density of the solid material in each case

$$ H$.$ L$.$ Ritter and L$.$ C$.$ Drake, Ind. Eng. Chem., Anal. Ed$.,17,787(1945).$

$358$ CHEMICAL ENGINEERING KINETICS

is $2\mathrm{.}37\frac{g}{c}{m}^3.$ The surface area of the first sample is $467\frac{m^2}{g}$ and that of the second is $372\frac{m^2}{g}.$ Which sample has the larger mean pore radius?