"Crude shale oils from conventional retorting processes are contaminated with water and sediment emulsified with the oil. Before these oils can be refined it is necessary to resolve the emulsions and remove the water and sediment; chemical and electrical emulsion-breaking processes commonly used for treating crude petroleum stocks have not proved successful. Experimental operations of the Oliver precoat filter indicated that this process will break crude shale-oil emulsions and reduce the solids content of the oil to less than 0.1 percent. However, the cost of treating wet crude shale oils by this process is 6 cents per barrel, which is rather high. On the other hand, the cost of removing sediment from dry shale oils by precoat filtration is only 1 cent per barrel. Thus it may be that precoat filtration will prove most useful in removing sediment from dry shale oil."