This paper contains results of research performed in the year 1928-29 on the generation of oil from possible source rocks of petroleum by high shearing pressures. An account of the earlier work has appeared in this Bulletin. High shearing pressures applied on oil shales from many localities, and on cannel coal, at room temperatures, failed to generate oil. Nearly all the specimens treated yield more soluble organic matter on extraction with chloroform than do rocks not sheared. Except in oil shale from Indiana, this increase in soluble matter is due largely to the physical effects of pressure in comminuting the rock, rather than to chemical changes produced in the organic compounds. The Indiana shale after pressure shows a large increase in soluble organic matter which is not wholly accounted for by physical changes. Most of the sands encased with the shales during shearing were found afterward to contain slight amounts of soluble organic matter which must have migrated from the shale. This, though explained also by purely physical changes in state of some of the organic matter, supports the theory of devolatilization of organic rocks by shearing pressures. Quantitatively, however, except in the oil shale from Indiana, it has still to be shown that shearing pressures exerted at room temperatures are important in converting the organic matter of such possible source rocks of petroleum into oil.