[en] High-sensitivity observations at the carbon 140α and 141α recombination-line frequencies in the direction of the rho Oph dust cloud show the presence of recombination lines of carbon and sulfur, but not of other heavy elements. These results require that the elements Si, Fe, and Mg are depleted by factors greater than 15, 10, and 2 respectively, most likely into interstellar grains, whereas sulfur is undepleted: and that only approximately one-sixth of the carbon is present in the gas phase in the cloud. From the observed size of the C ii region, thetaapprox. =3'.2, together with the observed carbon depletion, we infer that the density in the carbon-line-emitting region is n (H) approx. =2.5 x 10⁴ cm^-3, and that the size of the S ii region is significantly larger than that of the C ii region. The agreement between the widths of the recombination lines (which arise in a small region of the cloud) and those of the more widely distributed molecular species suggests that the lines in this cloud are broadened by microturbulence on a scale very-much-less-than0.1 pc