356 



PETROLEUM. 



the distillation of bituminous coal ; by the ignition 

 of wood, as happens in preparing charcoal in iron 

 cylinders for the manufacture of gunpowder; and 

 also in the making of pyroUgneous acid. Petro- 

 leum, then, and carburetted hydrogen gas, may be 

 considered as the products of the beds of bitumi- 

 nous coal which lie deep in the earth, and are gen- 

 erally found to accompany the salt water in greater 

 or less quantities. Where gas is discharged freely, 

 it greatly assists the ascent of the water in the 

 wells, and saves the expense of forcing it up by the 

 aid of a pump worked either by horse or steam 

 power. If constant and abundant. Dr. Hildreth 

 states that it might be conducted by pipes under 

 the kettles, and used as a fuel in boiling away the 

 brine, thus relieving one of the heaviest items of 

 expenditure in working a furnace. In some wells 

 in Ohio the discharge of gas is periodical, and at in- 

 tervals of eight or ten days, bringing up with it 

 large quantities of petroleum, to the amount of sev- 

 eral barrels. In some the discharges of gas are 

 tremendous, throwing the water all out of the wells 

 to a height of thirty or forty feet. The eruptions 

 are attended by a flow of petroleum, which in some 

 instances has amounted to from thirty to sixty gal- 

 lons at each flow, and returning at intervals of two 

 to four days. The salt wells now average only 

 about a barrel a week. At a locality near the 

 gravel coal-beds on the Hockhocking, the earth and 

 rocks have been blown out to a considerable dis- 

 tance, leaving a cavity of several feet in diameter 

 and depth. Probably the true reason why saline 

 fountains are commonly attended by inflammable 

 gas is, that the coal formation and salt deposites are, 

 geologically, close neighbours, the salt being usual- 

 ly above in Europe and other countries, but below 

 in the Valley of the Ohio and its confluent springs. 

 This fact also lends great force to the opinion that 

 the coal formation does not exist in this state. 



