EXPLOSIBILITY OF COAL OILS. 331 



tarry oil had previously been discovered in ancient times, flowing 

 naturally out of crevices of rocks on the surface of the earth like 

 springs of water. This peculiar tarry oil received the name of ' ' pe- 

 troleum," from the original Greek words signifying "rock oil," as 

 being descriptive of the source from whence this extraordinary liquid 

 was first obtained. 



The natural petroleum so nearly resembles the artificial tarry oil 

 obtained by the distillation of bituminous coal, as above described, 

 that the same name will be applied to designate both of these products, 

 as being alike the results of the distillation of the same material. 

 The question is often asked, Whence is this petroleum produced ? 



The region of our country where the oil-springs are found gushing 

 forth on the surface of the earth is near the frontier line dividing the 

 anthracite coal-fields of the seaboard of the United States and the bitu- 

 minous coal-fields of the great valley of the Mississippi. In this 

 intermediate region are vast beds of bituminous coal, originally com- 

 posed of the woody fibres of peat and other vegetable bodies, organ- 

 ized by the action of sunshine on the surface of the earth, and 

 then covered over securely from accidental combustion. The coal is, 

 however, exposed to a heat in the depths of the earth, which is in- 

 creased regularly 1^ from 50 to 70 feet of descent, the temperature 

 at 200 feet depth having been found to be 85° in an English coal 

 mine. The decomposition of the coal at great depths is constantly 

 going on, and the coal gas is often heard in the galleries of coal mines 

 rushing in hissing streams through crevices, and forming the explosive 

 '•fire-damp," w^hich renders the safety-lamp of Sir Humphrey Davy 

 a blessing for the preservation of the miners. 



One of the deserted coal mines near Newcastle, having a 4-inch 

 pipe connected with its chambers, has continued to distil sufficient 

 coal gas to form a jet of flame from its open aperture on the surface 

 of the ground "nearly sufficient to light a small town," as a recent 

 writer has stated. From the end of a similar pipe, inserted in a drill- 

 hole in the rocky strata on the banks of the Kanawha river, in West- 

 ern Virginia, perforated to the depth of about 1,000 feet to obtain 

 salt water, sufficient coal gas to light a city has continued for several 

 years to rush forth, commingled with the salt water. The gas is 

 used as fuel to boil the salt water for the production of salt. In a 

 furnace beneath a salt pan, 100 feet long and five feet in width, the 

 writer beheld the flame of burning coal gas, sweeping throughout in 

 one continuous sheet, Avaving and flashing in wreaths of resplendent 

 brilliancy, whilst at the same time a steam-engine was operated 

 briskly by the same natural flow from the earth into an adjacent fur- 

 nace beneath a steam-boiler. Sufficient coal gas was here discharged 

 to evaporate the brine for making about 400 bushels of salt per day. 

 Happening to arrive at a spot where another similar drill-hole had 

 just been completed, an equal volume of coal gas and salt water ap- 

 peared jetting upwards from the drill-hole in the rock thirty or forty 

 feet into the air, with loud belching sounds resembling the asthmatic 

 pantings of a powerful locomotive engine. The coal gas, here natu- 

 rally elaborated, was perfectly pure and free from the disagreeable 



