compounds in the distillable solvent can be replaced and increased in concentration with basic nitrogen compounds recovered from the substantially nondistillable soluble coal products the presence of these basic nitrogen compounds particularly partially saturated compounds such as 1 2 3 4 tetrahydroquinoline and indoline have been found to improve the quality of the solvent and significantly improve the yield of distillates and oils produced by the liquefaction process the residue comprising substantially nondistillable soluble coal products and insoluble coal products is withdrawn through a conduit 26 and admixed with a deashing solvent introduced through a conduit 28 to form a prepared mixture which is introduced into a first separation zone 30 sufficient deashing solvent is admixed with the residue to provide a ratio by weight of coal liquefaction products to deashing solvent in the prepared mixture in the range of from about 1 1 to about 1 10 it is to be understood that larger quantities of the deashing solvent may be employed however such larger quantities generally are unnecessary the term 34 deashing solvent 34 as used herein refers to those solvents consisting essentially of at least one substance having a critical temperature below 800 u00b0 f selected from the group consisting of aromatic hydrocarbons having a single benzene nucleus and normal boiling points below about 310 u00b0 f such as benzene toluene o m and p xylene ethyl benzene isopropyl benzene and monocyclic aromatic hydrocarbons in general having normal boiling points below about 310 u00b0 f cycloparaffin hydrocarbons having normal boiling points below about 310 u00b0 f such as cyclobutane cyclopentane cyclohexane cycloheptane and nonaromatic monocyclic hydrocarbons in general having normal boiling points below about 310 u00b0 f open chain mono olefin hydrocarbons having normal boiling points.