296 ANNUAL OF SCIENTIFIC DISCOVERY. 



barrels daily in December of the same year. The spring of 1863 was 

 signalized by a much larger increase. The price of crude oil was re- 

 duced from 25 cents to less than one cent per gallon in the same time. 

 But excessive cheapness forced consumption, both in this country and 

 abroad, with unparalleled rapidity, so that, in the latter months of 1862, 

 there occurred a large but spasmodic rise in the value of the oil. The 

 unrernunerative prices which had hitherto prevailed checked production, 

 causing all small wells and interests to be abandoned. The year 186;) 

 saw rising, although heavily fluctuating, prices. This state of the 

 market continued, merging into a more even upward graduation of 

 values, through the year 1864, when crude oil sold at one time as high 

 as 13.50 per barrel at the wells. 



The large flowing wells have generally stopped after 25 or 30 

 months' flow. Some few have continued with diminished volume over 

 three years. The pumping wells have averaged about the same du- 

 ration. In 1863, and until the latter part of 1864, comparatively few 

 new wells were sunk. During this period many wells gave out and 

 many were abandoned. Quite recently, however, it has been ascer- 

 tained, that by using the air-pump, wells which had ceased to pro- 

 duce oil could be made to resume their yield. This fact is now es- 

 tablished. A great many wells that were considered exhausted have 

 been resuscitated, and are now yielding very considerable quantities 

 of oil. The spontaneous flow of oil is undoubtedly due to a pressure 

 of gas evolved from the petroleum greater than the pressure of the 

 atmosphere. When this greater pressure is reduced by exhaustion 

 to an equilibrium with the atmospheric pressure, the flow ceases un- 

 til artificial pressure is applied or until a fresh accumulation of the gas 

 causes a resumption of the flow. 



" It may be safely said, then, that it is, up to this time, not the ex- 

 haustion of the oil, but the exhaustion of the gas which elevates the oil, 

 that has produced an embarrassment to oil mining which threatened 

 at one time to hazard its success, but which is now obviated by the 

 application of new and efficient inventions. The many instances in 

 which wells have been resuscitated after apparent failure have led ob- 

 serving oil-producers to believe that good oil lands will yield the ar- 

 ticle to an indefinite future period." 



THE ROCKS IN WHICH PETROLEUM IS FOUND. 



Mr. R. P. Stevens, of New York, a geological expert, contributes 

 to the Scientific American the following description of the rocks in 

 which petroleum occurs in the North American Continent. The 

 lowest geological horizon, or stratum, in which petroleum is found of 

 commercial importance, is in Canada, at Enniskillen, near Lake St. 

 Clair. The oil is in the corniferous limestone. (New York nomen- 

 clature Devonian System), which is largely composed of fragments of 

 corals, with sea shells cemented together. The cavities of these corals 

 and sea shells are often filled with liquid bitumen, which distils from 

 them, as can be seen in the walls of the Second Presbyterian Church, 

 in Chicago. This limestone in the United States is in its maximum 

 about 350 or 400 feet thick. Immediately overlying the limestone is 

 the Marcellus sliale, which is so highly charged with bitumen as to lead 

 to great expenditures of time and money in vainly looking for coal iu 



