rock oil

But by fracking the rock, oil flowed from the shale.

From The Wall Street Journal ● Apr. 8, 2014

The oil mentioned in the next line, is that called the rock oil, petroleum, a black fetid mineral oil, good for bruises and sprains.

From The Lusiad or The Discovery of India, an Epic Poem by Luís de Camões

His words are:— “Petroleum, rock oil, or what the Welsh call it, Ymenin tylwyth têg, or Fairies’ butter, has been found in the lime stone strata in our mineral country. 

From Welsh Folk-Lore a Collection of the Folk-Tales and Legends of North Wales by Elias Owen

There are likewise springs of rock oil or bitumen.

From A General History and Collection of Voyages and Travels — Volume 02 Arranged in Systematic Order: Forming a Complete History of the Origin and Progress of Navigation, Discovery, and Commerce, by Sea and Land, from the Earliest Ages to the Present Time by Robert Kerr

So far, Bissell's enterprise seemed to promise success, yet the great problem still remained: how could he obtain this rock oil in amounts large enough to make his enterprise a practical one?

From The Age of Big Business; a chronicle of the captains of industry by Burton Jesse Hendrick