A technique to obtain intense infrared spectra over a wide frequency range for molecules adsorbed on metal particles dispersed in a hydrocarbon medium is described. New applications of this technique to determining extents of adsorption in competitive chemisorption situations and the interactions of coadsorbed species are given. Band shifts are interpreted in terms of electronic factors for ND3 and NH3 coadsorbed with PF3 on Fe, Ni, and Cu; for H2O with BCl3 on Ni; for trimethyl phosphite with CO on V, Fe, Ni, and Cu; and for alkylamines with CO on Fe and Ni.