Abstract As a part of a general investigation of the separation of bitumen fromhydrocarbon mixtures a study was made of a restricted quaternary systemcomposed of methane, decane, tetralin, and bitumen. The work was limited to apressure of 8000 psi, a temperature of 220'F, and to a fixed relativeproportion of decane, tetralin, and bitumen. The measurements permitted thedetermination of the distribution of these components in each of the fluidphases. It was not possible to distinguish a second liquid phase in the courseof these measurements. Gas-liquid equilibrium "constants" of each ofthe components were found to vary markedly with the composition of the systemwhile temperature and pressure remained fixed. Introduction The separation of bitumen from naturally occurring hydrocarbon mixtures hasbeen of importance for a number of years in the production of petroleum, especially in the California area. The deposition of this material from crudeoils was noted in earlier studies of the solubility of natural gas in crudeoil. Studies of the separation of bitumen from crude oils from the Greeley andSanta Fe Springs fields were carried out. The behavior of these systemsappeared complex and studies of two restricted ternary systems involvingmixtures of n-pentane, tetralin, and bitumen, and of decane, tetralin, andbitumen, confirmed this belief. Reviews of the literature pertaining to theseparation of bitumen from naturally occurring and refined hydrocarbons areavailable. The important effect of methane in the separation of bitumen from naturallyoccurring hydrocarbon mixtures was apparent from the earlier studies, and forthat reason it appeared desirable to investigate a restricted quarternarysystem involving mixtures of methane, decane, tetralin, and bitumen; dataconcerning the behavior of mixtures of decane, tetralin, and bitumen havingalready been obtained. This study was restricted to a pressure of 8000 psi, atemperatue of 220'F, and fixed relative proportions of bitumen, decane, andtetralin. This composite constituent, hereinafter designated as the lessvolatile constituent, was made up of 0.0455 weight fraction bitumen, 0.0909weight fraction decane, and 0.8636 weight fraction tetralin. The experimental method involved bringing together mixtures of methane and theless volatile constituent in varying proportions in a constant volume containerat the pressure and temperature indicated above. The composition of each of thephases was determined and from this the extent of the separation of bitumen wasestablished. T.P. 2718