The surface tension of petroleum from oarious sections of the United States has been determined. I t is found that the value increases with the specific grauity. The small quantity of fatty acids and amorphous and crystalline wax commonly found in petroleum products does not appear to influence the surface tension. The presence of high boiling fractions and products of high oiscosity tends to raise the surface tension of the lighter petroleum products, such as gasoline and naphtha. The surface

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... ension decreases as the temperature increases, the surface tension of the oils tested decreasing approximately 0.05 dynes per cm. for each OF. increase in temperature. Surface tension in conjunction with other tests may aid in de- termining the lubricating and other values of a n oil.