Oil shale

The article "Oil Shale Research is Moving Forward" makes it sound too easy to recover oil from shale, as if you bore a hole and distill out the trapped "oil" (C&EN, April 24, page 29). Embedded in the shale is not oil but layers of kerogen, a vegetable gum, which, when destructively distilled, yields oil that can be refined. The struggle in the early 1980s was mining, crushing, heating, and disposing of spent shale. Early industrial hygiene observations in the 19th century and the late 20th century were that some of the derived oils are carcinogenic unless hydrogenated. Oil shale may have to surmount more barriers than were described in the story.

Harvey Alter
Frederick, Md.