HYDROCARBON COMPOSITION OF MOTOR OILS

content of branched paraffinic hydrocarbons, namely 36-aa%, falling to 28% for oil from Mukhanovsk petroleum. With increasing viscosity of the oils, the content of these hydrocarbons fails markedly; in the saturated part of the oil, with a viscosity of 9-9.5 cS at 100~ their content is 17% in the sulfur oil and 11% in the low-sulfur oil. Baku petroleums are of the low-paraffin type, their oils do not undergo dewaxing, so that the saturated part has a fairly high content of normal paraffinic hydrocarbons (5.2%). In oil with such a viscosity from Tuimazy petroleum, normal paraffinic hydrocarbons are still present (up to 1%) after selective dewaxing. It will be seen from the distribution of the naphthenic hydrocarbons with respect to the number of rings inthe molecule (see Table 3) that the saturated part of the oils with a viscosity of 6 cS at 100~ has a predominance of mono- and bicyclic compounds (24-33% and 22-27~ respectively). The content of these hydrocarbons is greatest (27-38%o) in oil subjected to phenol-treatment. The content of naphthenic hydrocarbons containing three or more condensed rings in the molecule is higher in adsorption-treatment oils from Tuimazy and Mukhanovsk cmdes (4850~ instead of 40%). The difference is particularly great (29-32% instead of 23%) in the case of polycyclic naphthenic hydrocarbons with four to six condensed rings in the molecule. The maximum content of naphthenic hydrocarbons in the saturated part of Avtol (lubricating oil)from Tuimazy petroleum (specimen 5) is found in compounds with 2, 3, and 4 condensed rings in the molecule (20.5-29~ of each type of hydrocarbon), whereas the content of mono-, penta-, and hexacyclic hydrocarbons is 9-12.5%o. The distribution of naphthenic hydrocarbons of the saturated part of viscous Avtol from a mixture of Baku petroleums differs markedly from their distribution in sulfur oil of similar viscosity by the higher content of mono- and polycyclic hydrocarbons with 1, 5, and 6 rings in the molecule (17.5-22% as against 12.5-9%). In the more viscous oils the content of polycyclic naphthenie hydrocarbons is much greater than in Avtols of medium viscosity (38-4o% as against