Constitution of the Ichthyolites of Stromness. 285 
Bituminous matter, : 46.956 
Siliceous matter (sand), nae a ee ae sul | 
13.108 
phuret of iron, 
Phosphate of denies with tines ‘of duste of er oe 21.717 
Carbonate of lime, i } : 3 F 13.130 
Carbonate of magnesia, : : J ; 4.891 
Loss, : é . ; ; : é .198 
100. 
It is obvious, from the above analysis, that the greater 
portion of the original constituents of the organism had re- 
mained in connection with it; while it is equally evident that 
numerous transpositions have subsequently taken place among 
the ingredients of the mass, by which the limits of the sepa- 
rate parts have been obliterated. The same forces, however, 
which have annihilated all distinction between the surfaces of 
the scales, the viscera, and the bones, and even modified their 
constitutent parts, do not appear to have exerted any in- 
fluence on the surrounding matrix ; for the line of demarca- 
tion between the surface of the organism and the rock, is 
usually well marked in the cross fracture, although the 
adhesion is generally strong. There is, no doubt, a consi- 
derable amount of bituminous matter, forming an obvious 
ingredient in these schists; yet it would be rash to infer 
that it derived its origin directly either from the maceration 
of the ichthyolites, or their vaporized contents. The state of 
the beds at the period of their formation, and, perhaps, for 
a long time afterwards, appears to have been favourable for 
the mutual action of the different parts of the organism 
disposed for change, but not, by any means, for the abstrac- 
tion or dispersion of the greater part of the more changeable 
ingredients. Instead, therefore, of the resultant consisting 
entirely of the earthy ingredients of the organism, as pro- 
bably would have been the case had maceration prevailed to 
any great extent, or of these conjoined with the carbon, if 
igneous influence had been exerted, we have presented in the 
mass, not merely the original earthy salts, but the animal 
matter in a bituminous form, and the whole constituting a 
- singularly homogeneous coal. But the subject is too obscure 
to warrant farther speculation. 
ABERDEEN, March 3. 1845. 
