80 STEVENSON— FORMATION OF COAL BEDS. [April 21. 



hydrocarbons are impregnations from the forming coal or are due, 

 as in the coal itself, to transformation in place of vegetable debris, 

 imprisoned when the shales were deposited. These determinations 

 would tell us if one should prefer the doctrine of transport to that 

 of formation /;/ situ, and whether the transformation of vegetable 

 matter into coal has been accomplished by a kind of distillation or 

 has been caused by a special kind of fermentation. 



In the course of his studies. Spring discovered an unexpected 

 condition — that the shales, containing organic matter, were the 

 seat of slow oxidation, depriving them of hydrogen. The shales 

 not only protected the coal from erosion but also from oxvgen, as 

 gas or in solution, the action of the oxygen being exhausted in the 

 shales. As the encasing rocks are not the same everywhere, the 

 character of the coal should differ in the same bed and in different 

 beds. Usually, meager coals are on the peripheral parts of a basin 

 while fat coals prevail in the middle portions. May this be be- 

 cause the latter have been better protected against the action of 

 ox\'gen ? 



The .shale samples studied were from the Saint-Gilles mine near 

 Liege, eight of them, with one from the coal bed. Five were taken 

 from the toit and three from the mur, each representing a vertical 

 space of a half meter. They are marked "a," " b," " c," "d" and 

 "e" for the toit and i, 2 and 3 for the mur. The material was 

 dried and analyzed with these results ; 



Coa'. "a" '• b " "c" "d" "e" 123 



Car1)on 86.61 7.54 t,.t,^ 2.21 1.20 0.70 0.99 0.93 0.80 



Hydrogen 4.65 0.79 0.62 0.54 0.56 0.59 0.84 0.53 0.58 



Ash 1.84 98.33 92.05 93.86 92.00 94.08 95.16 93.50 93.20 



Oxygen, sulphur | ^ ^ 



by difference / ^'^'^ ^-'^ ^'"^^ "^'^^ ^-^ 4-63 3.01 5.04 5-42 



The carbon varies greatly but regularly, decreasing as one re- 

 cedes from the coal. No conclusions can be drawn from conditions 

 in the mur as the quantity is very small, but the variation in the 

 toit is a logarithmic curve, the cause producing the variation is in 

 inverse relation to distance from the coal. This seems to show 

 that Fremy's conclusions are right and that the shales were impreg- 

 nated with carbonaceous materials at expense of the coal, the com- 



80 



