192 PROCEEDINGS OF SOCIETIES. 
a deposit from water, and the other a rock that had been in 
such a state of pure igneous fusion as the slags of our 
furnaces or the erupted lavas. When the constituent 
minerals of solid granite, far from contact with the stratified 
rocks, are examined, it is seen that they also contain fluid- 
cavities. This is especially the case with the quartz of coarse- 
grained, highly quartzose granites, in which there are so 
many, that the proportion of a thousand millions in a cubic 
inch is not at all unusual; and the inclosed water constitutes 
from one to two per cent. of the volume of the quartz. 
However, besides these fluid cavities, the felspar and quartz 
contain excellent stone cavities, precisely analogous to those 
in the crystals of slag, or erupted lavas; and thus the 
characteristic structure of granite is seen to be the same as 
that of those minerals formed under aqueo-igneous con- 
ditions in the blocks which are ejected from modern 
voleanos; and the very common occurrence of minute 
crystals inside the fluid-cavities still further strengthens this 
analogy. 
The conclusion to which these facts appear to lead, is that 
granite is not a simple igneous rock, like a furnace-slag, or 
erupted lava, but is rather an aqueo-igneous rock, produced 
by the combined influence of liquid water and igneous fusion, 
under similar physical conditions to those existing far below 
the surface at the base of modern volcanos. 
These deductions of the author, therefore, strongly confirm 
the views of Scrope, Scheerer, and Elie de Beaumont; and 
he agrees with them in considering it probable that the 
presence of the water during the consolidation of the granite 
was an instrumental, if not the actual cause of the difference 
between granite and erupted trachytic rocks. 
MicroscopicaL Socigty, January 13th, 1857. 
Grorce SHapsott, Esq., President, in the chair. 
W.S. Gibbons, Esq., Melbourne, South Australia; Henry 
Blanchard, Esq., 5, Upper Bedford Place ; and T. Maltwood, 
Esq., 130, Fenchurch Street, were balloted for, and duly 
elected members of the Society. 
The following papers were read— 
“ On a New Object-finder,” by T. Maltwood, Esq. (‘ Trans.,’ 
. 59.) 
. A discussion followed, in which Mr. W. Histor said— 
I beg to remark that I have for some time been making 
experiments, having for their object the production of mi- 
nutely divided scales by photography, such scales to be used 
