448 Notices of British and Foreign Memoirs. 
(Report of Brit. Assoc. 1864.) Possibly, however, some meteoric 
irons have been produced in this manner by the occurrence of such 
a separation. ‘The hydro-carbons with which some few meteorites 
are impregnated, may have condensed from a state of vapour at a 
relatively late period. 
I therefore conclude provisionally that meteorites are records of 
the existence in planetary space of physical conditions more or less 
similar to those now confined to the immediate neighbourhood of 
the sun, at a period indefinitely more remote than that of the occur- 
rence of any of the facts revealed to us by the study of Geology 
—at a period which might, in fact, be called pre-terrestrial. 
BROOMFIELD, SHEFFIELD: July 1865. 
VI. On THE MIcROSCOPICAL STRUCTURE OF Mount SoRREL SYENITE, 
ARTIFICIALLY FUSED, AND COOLED sLOWLY. By H. C. Sorsy, 
F.R.S., F.G.S., &c., of Sheffield. (Proceedings of the Geo- 
logical and Polytechnic Society of the West Riding of Yorkshire, 
1863-64, pp. 301-304.) 
Me. SORBY thus describes the Syenite of Mount Sorrel :— 
i ‘The rock operated on is a mixture of reddish felspar, clear — 
green hornblende, and quartz, along with some opaque minerals, 
evidently in a greatly altered state, perhaps originally pyrites or 
magnetic oxide of iron. The felspar is in very distinct crystals, 
but has often caught up much hornblende; and the quartz fills up 
the spaces between the other minerals, or is curiously crystallized 
along with the felspar, so as to form a microscopic “ graphic granite,” 
or “hebraic felspar;” and it is especially important to bear in mind, 
that the quartz contains very many fluid-cavities, nearly filled with 
water, as described in my paper in the Quart. Journ. of the Geolo- 
gical Society (vol. xiv. p. 453); and, in accordance with the prin- 
ciples therein explained, they indicate that the rock was consolidated 
under a very great pressure.’ These fluid-cavities, he adds, ‘ show 
the spontaneous movements of the bubbles which they contain 
better than those I have seen in any other rock.’ 
Of this Mount Sorrel Syenite, Mr. J. G. Marshall, F.G.S., melted 
large quantities, allowing it to cool very slowly; and of this material 
Mr. Sorby examined microscopically thin slices, comparing its 
structure with that of various kinds of igneous rocks in their natural 
state, and after having been fused and slowly cooled. After 
detailing the characters observed in the artificial rock, Mr. Sorby 
remarks that, as the hornblende melted more easily than the quartz 
and felspar, and as a portion of the mineral rose upwards, the whole 
was not thoroughly incorporated. Nevertheless this circumstance 
is not, he says, enough to account for the difference between the 
original and the fused rock, as seen also in the experiments of M. De- 
lesse; but ‘an explanation must be sought for in the very different 
circumstances under which they were formed.’ 
The fused and cooled mass is quite unlike syenite or granite, but 
has a resemblance to some of the stony masses obtained by fusing 
