71 
1915-16.] The Origin of Oil-Shale. 
inorganic matter is present in such minute quantity, but must have been 
formed during the process of inspissation. 
In dealing with an asphalt consolidated at the surface, and an oil- 
rock taken at outcrop, the question of adsorption comes in, since any 
argillaceous material present will have adsorbed part of the inspissated 
heavy residues. 
Thus three specimens of oil-sands from the Guayaguayare field in 
Trinidad (analyses by Professor Carmody) give the following interesting 
results : — 
Per cent. 
Per cent. 
Per cent. 
Water ...... 
1*320 
3*28 
4*56 
Bitumen 
14*0 
9*6 
17-3 
Non-bituminous organic matter 
3-44 
5*68 
10-02 
Silica 
76*47 
73*74 
58-37 
Fe 2 0 3 and A1 Q 03 .... 
3*8 
6-8 
7-89 
CaO 
*12 
*06 
*15 
MgO 
*42 
•38 
1-04 
K20 and Na20 .... 
*25 
*35 
*45 
Sulphuric anhydride 
*09 
*09 
•08 
Phosphoric anhydride . 
*08 
traces 
•12 
100*00 
100-00 
100-00 
Thus the oil-rock poorest in silica and richest in basis not only retains 
the greatest percentage of inspissated bitumen, but by far the largest 
percentage of “ organic matter not bitumen.” 
Another very greatly weathered oil-sand from San Fernando, Trinidad, 
shows on analysis : — 
Water 0*76 
Bitumen ... ... 4‘94 
Non-bituminous organic matter . 2 - 50 
Mineral matter 91 -80 
100-00 
A much more purely arenaceous and porous oil-rock from the Guapo 
field, Trinidad, gives on alalysis : 
Water 
2-60 
Bitumen 
. 17-50 
Non-bituminous organic matter 
•46 
Mineral matter .... 
. 79-44 
100-00 
In this specimen, owing to its more purely siliceous composition, there can 
have been but little adsorption. 
The asphalt of the Trinidad pitch lake contains, as seen above, 25 per 
cent, of mineral matter. Microscopic examination shows this to consist of 
