68 Proceedings of the Royal Society of Edinburgh. [Sess. 
of oil per ton. It has obviously been originally a more porous rock than 
the “ paper-shale.” 
The yield of ammonium sulphate is no less remarkable than the yield 
of oil, the experiments shown at the Pumpherston works giving an average 
of nearly 77 lbs. per ton. Another series of experiments on shale from the 
Albert Mine give an average of 59’4 lbs. per ton. 
These shales are therefore true oil-shales, though not closely resembling 
the Scottish shales, and they occur in environment typical, as we have seen, 
of oil-fields. 
Very similar shales in the same series are exposed in several other 
localities in the district, though in less complicated structure. The beds in 
these cases are more clearly defined as separate seams, though often of great 
thickness. Borings for petroleum in the neighbourhood also have proved 
thick beds of oil-shale or bituminous shale, and have furnished much 
evidence to connect these occurrences with the phenomena of oil-fields. 
For instance, west of the Petit Codiac River, a few miles north of the 
Albert Mine, there is a gas-field where borings through this series supply 
natural gas in large quantities to the towns of Moncton and Hillsborough. 
Many borings have been made for oil, and small quantities — “shows” 
rather than productions — have been recorded near the Memramcook and 
Petit Codiac rivers : dark bituminous shales occur in all cases above the 
oil-sands. 
In the Albert Mine itself only traces of petroleum impregnation were 
encountered in the joints of clay-ironstone nodules, and in sandy beds at 
the deeper levels. 
From this field evidence we see that rich oil-shales may occur under 
conditions which have been shown to be typical of oil-fields, and we have 
additional instances of the connection between petroleum and oil-shale. 
The point to be noted specially is that in the case of the Albert Mine, 
where the anticlinal structure has no doubt caused at one time a great con- 
centration of petroleum and a great intrusion of bitumen, all the country 
rock, and not only a few selected bands, contains kerogen to a greater or 
less extent. 
III. Filtration, Absorption, and Adsorption. 
These facts are at least suggestive of an origin for kerogen, but there 
are still many problems unexplained. How, for instance, has kerogen been 
formed from petroleum ? Why is one bed of shale an oil-shale while 
another is barren or carbonaceous ? What determines the presence of 
crude petroleum in one district or formation, and kerogen in another ? 
