Chemical analyses of large quantities of recent marine sediments from the richest areas located during a survey of the distribution of organic matter in various types of modern deposits indicate that liquid petroleum probably does not occur in sediments at the time of their deposition, and that if it is present, it is in very small amounts, certainly less than 3 parts per 100,000. Therefore, petroleum present in newly deposited sediments is not an important factor in the genesis of oil. Presence of small quantities of solid paraffines suggests that some constituents of petroleum occur in fresh sediments. Fatty and oily substances constitute less than 1 per cent of the organic content of the marine sediments. Presumably much, if not most, of the petroleum comes from the re aining 99 per cent of the organic matter. Fatty acids ranging from cerotic (C₂₆H₅₂O₂) to melissic (C₃₀H₆₀O₂), comprise practically all the fatty acids observed and they constitute from 0.002 to 0.006 per cent of the sediment. Organic sulphur compounds form about 0.03 per cent of the deposits. Free sulphur is a common minor component of all the sediments, and ranges from 0.02 to 0.1 per cent in quantity.