84 
Proceedings of the Royal Society of Edinburgh. [Sess. 
The following section of the seam shows very clearly its relations to 
other deposits : — 
Shale ..... 
Torbanite .... 
Fine ironstone . 
Bituminous shale 
Inferior coal 
Foul coal ( i.e . coal and shale) 
4 inches. 
1 foot 4 „ 
4 to 2 „ 
2 
2 to 4 
This is sufficient to prove the association with both the carbonaceous and 
the kerogen phases, and to suggest that we are dealing with a locality where 
the phenomenon of the transition stage between the carbonaceous and the 
petroliferous phases may be studied. 
The specific gravity of the deposit varies from 1T7 to T316, and the 
ash has the very low specific gravity of 1'22 to T28. The percentage of 
mineral matter is from 2T3 to 24, and analyses of the spent material give 
results as follows : — 
Stenhouse. 
Hofman. 
Anderson. 
S 4 0 2 .... 
58-51 
56-7 
56-09 
A1 2 0 3 .... 
33-65 
36-2 
4004 
Fe 2 0 3 .... 
7-0 
3-2 
3-24 
CaO .... 
1-3 
•34 
MgO .... 
0-4 
•46 
Alkalis .... 
1-21 
2-2 
The points to be noted are the very high percentage of alumina, and 
the low percentage of iron, lime, and magnesia. Alkalis have probably 
been lost to a great extent in the retorting. The analyses indicate a very 
pure clay, possibly rich in alkalis, as the inorganic content of the deposit. 
The vegetable fossils prove that the deposit was rich originally in organic 
matter, which no doubt has been largely converted into petroleum, inspis- 
sated, and adsorbed in situ ; but the-f act that traces of the vegetable remains 
still exist makes it certain that the conversion into petroleum has not been 
quite complete, and the richness of the deposit must be due to the absorption 
and adsorption of extraneous inspissated petroleum. 
The position above the porous sandstone correlated with the Millstone 
Grit — a rock admirably adapted to act as a reservoir for petroleum — and 
beneath impervious shales is precisely that in which vestiges of the 
petroliferous phase would be expected. 
Other abnormal deposits or minerals are the torbanite of New South 
Wales and the stellarite of Nova Scotia. The percentage of mineral 
matter in these cases — 3*2 in the former and 6 - 55 in the latter — classes 
