Several residual organic compounds were liberated from Jurassic rock samples by treatment with hydrochloric acid and were partly characterized by absorption spectra, specific reactions, and paper chromatography.

Several ninhydrin-reacting compounds were separated chromatographically from the acid hydrolyzates and are believed to represent several amino acids, together with one or more amines. The amino compounds exhibit greatest amounts and variety in samples from alluvial and deltaic mudstones, carbonaceous sandstone, and from offshore basinal black shale. The results provide a new tool for determination of ancient sedimentary environments and measurement of their organic productivity.

Trace amounts of furfurals, probably derived from pentoses, and hydroxymethylfurfural, from hexoses, were identified in absorption spectra of distillates of hydrochloric acid hydrolyzates of the rock samples, and were further determined by a colorimetric phenol-sulphuric acid method. The furfurals are present in many different rock types, but are scarce in algal oolitic limestone and evaporites, as compared with other kinds of rock deposits.

Other organic compounds to be studied further are present in the acid extracts, commonly in amounts greater than the aldehydes or amino compounds mentioned. These have absorption spectra resembling heteroaromatic compounds and are believed to include pyridines and similar coal-tar-derived substances.