APPENDIX.                                                543

In analyzing a portion of the bituminous schists from the property of the
Earl of Caithness (near Barrogill Castle), Dr. Hofmann reported to me as fol¬
lows :—" When submitted to the action of heat, this substance evolves a consi¬
derable amount of gas, and likewise of oily matter containing a certain propor¬
tion of ammonia. The residue which remains behind is a greyish mass, consist¬
ing essentially of silicate of alumina (clay) mixed with a certain quantity of
sesquioxide of iron and of sulphate of lime. A very minute proportion of phos¬
phoric acid was likewise found to be present. The loss which the mineral
imdergoes on heating was found in two consecutive experiments to be 30-21 and
30*02 ; so that the mineral may be said to contain in round numbers—

Fixed matter (mineral)................    70

Volatile matter (organic)  ..............    30

100

" In determining the amount of gas furnished by the distillation of the mineral,
a portion of it was heated in an iron tube, in order to imitate, as nearly as
possible, the circumstances of an operation on a large scale. In two consecutive
experiments which were performed in this manner, the following results were
obtained:—

Cub. centim.

I. 100 grammes furnished................ 7690

II-    „         ,>             V         ................ 7430

Mean 7560

" Assuming 100 grammes of the mineral to yield, on an average, 7500 cubic
centimetres of gas, a ton of the material would furnish 2690 cubic feet. The
ordinary varieties of coal used in gas-making yield from 8000 to 10,000 cubic
feet of gas per ton. The gas obtained from the mineral is very luminous; it
is nearly entirely free from sulphur, and it is on this account very readily puri¬
fied. The residue left in the retort after the expulsion of the gas retains but a
small amount of carbon, viz. 8-5 per cent.; this residue, therefore, has but little
value as coke.

" The mineral in question is in no way related to ozokerite, as has been sug¬
gested. From that substance it may be at once distinguished by its infusibility
(ozokerite fuses at 80° C.= 176° Fahr.), and by its entire insolubility in alcohol
and ether, in which solvents ozokerite dissolves, although with difficulty."

I.—Fossil Reptiles in the Carboniferous Shales of Ireland.

For a full account of the remarkable evidences of Reptilian Ufe having flourished
in the Carboniferous period, referred to at p. 303, see the memoir ' On a Collec¬
tion of Fossil Vertebrata, from the Jarrow Colliery, County of Kilkenny, Ire¬
land,' by Thomas H. Huxley, F.R.S. &c., and E. Perceval Wright, A.M. &c..
Transactions Roy. Irish Acad. vol. xxiv. 1867.

K.—Spitzbergen (pp. 323 & 368).

Since Chapter XIV. was printed, I have perused with much interest an excel¬
lent sketch of the geology of Spitzbergen by Mr. A. E. Nordenskiold, resulting
from the examination of the late Swedish Scientific Expedition*.    He sub-

* Sketch of the G-eology of Spitzbergen by A. E. NordenskiiJld: Stockholm, 1866. (Transactions of
the Koyal Swedish Academy of Sciences.)