640 EBPOKT — 1891. 



existence of adjoining beds of limestone, gypsum, &c. ; II. Volcanic action in close 

 proximity ; III. The presence of salt water in the wells ; IV. The great extent 

 of the production of oil, indicating subterranean receptacles of vast dimensions. 



I. The close and invariable proximity of limestone to the wells, has been noticed 

 by all writers, but they have been most impressed by its being ' fossiliferous,' or 

 shell limestone, and have drawn the erroneous inference that the animal matter 

 once contained in those shells originated petroleum, but no fish oil ever contained 

 paraffin. On the other hand, the fossil shells are carbonate of lime, and, as such, 

 capable of producing petroleum under circumstances such as many limestone beds 

 have been subjected to. All limestone rocks were formed under water, and are 

 mainly composed of calcareous shells, corals, encrinites, and foraminifera, the 

 latter similar to the foraminifera of * Atlantic ooze ' and of English chalk beds. 

 Everywhere, under the microscope, its organic origin is conspicuous. Limestone 

 is the most widely diffused of all rocks and contains 12 per cent, of carbon. 

 Petroleum consists largely of carbon, and there is a far larger accumulation of 

 carbon in the limestone rocks of the United Kingdom than in all the Coal-measures 

 the world contains. A range of limestone rock 100 miles in length by 10 miles in 

 width and 1,000 yards in depth would contain 743,000 million tons of carbon, or 

 sufficient to provide carbon for 875,000 million tons of petroleum. Deposits of 

 bituminous shale have also limestone close at hand ; e.g., coral-rag underlies the 

 Kimmeridge clay, which is more or less saturated throughout with petroleum, 

 and it also underlies the famous Black-shale in Kentucky, which is extraordinarily 

 rich in oil. 



II. The evidence of volcanic action in close proximity to petroleum strata is 

 next dealt with, and extracts in proof thereof are given from several writers. In 

 illustration of volcanic action on carbonate of lime, a sulphur mine in Spain, within 

 a short distance of an extinct volcano (with which the author is well acquainted), 

 is mentioned. That petroleum is not far off is indicated by a perpetual gas flame 

 in a neighbouring chapel and other symptoms ; and, these circumstances having 

 attracted his attention, he observed that Dr. Christoph Bischof records in his 

 writings that he had produced sulphur in his own laboratory b)^ passing hot 

 volcanic gases through chalk, which fact further led the author to remark that, 

 in addition to sulphur, ethylene, and all its homologues (OnH„n)) which are the 

 oils predominating at Baku, would be produced by treating — 



2, 3, 4, 5 equiv. of limestone (carbonate of lime) with 



2, 3, 4, 5 equiv. of sulphurous acid (SO-), and 



4 6 8 10 equiv. of sulphuretted hydrogen (H'-S) ; 



and that marsh gas and its homologues, which are the oils predominating in Penn- 

 sylvania, would be produced by treating — 



1, 2, 3, 4, 5 equiv. of carbonate of lime, with 



1, 2, 3, 4, 5 equiv. of sulphurous acid, and 



3, 5, 7, 9, 11 equiv. of sulphuretted hydrogen. 



Thus, we find that 



Carbonate of lime 2Ca2CO^ 1 f 2(Ca=S0'.H=0) (gypsum) 



Sulx^hurous acid 2S0= - yield \ 4S (sulphur) 



and sulphuretted hydrogen 4H^S J I. C-H", which is ethylene, 



and 



Carbonate of lime Ca=COn fCa=SO^H=0 (gypsum) 



Sulphurous acid SO- yield \ 3S (sulphur) 



and sulphuretted hydrogen SH'^S J [ CH\ which is marsh gag. 



These and all their homologues would be produced in nature by the action of 

 volcanic gases on limestone. 



But much the most abundant of the volcanic gases appears (at any rate at the 

 surface) as steam, and petroleum appears to have been more usually produced 

 without sulphurous acid and with part of the sulphuretted hydrogen H-S replaced 

 by H^O (steam), or H^O" (peroxide of hydrogen), which is the product that results 



