22 
Mr. .W. Pengelly on the Red Sandstones, 
SPECIMENS. 
Silica , 
Lime 
Alumina and 
Phosphate of 
Alumina 
Sesquioxide of Iron 
Magnesia 
Soda 
Potassa 
Lithia 
Water 
Carbonic acid 
and Organic 
matter 
Chlorine (pro- 
bably com- 
bined with the 
Sodium 
Loss 
90-707 
•44 
•075 
5-09 
•002 
•03 
trace 
•7 
2-27 
•04 
•656 
11. 
93-037 
2-26 
trace 
roi 
•014 
•075 
trace 
l'072 
1^53 
•091 
•911 
III. 
)3^115 
2-76 
•002 
•097 
•007 
•019 
trace 
1-56 
2^44 
trace 
IV. 
92^7 
3^031 
•06 
•07 
trace 
•017 
trace 
•96 
2-51 
trace 
•652 
V. 
92^707 
2-7 
•012 
•78 
trace 
trace 
trace 
l'76 
1^97 
VI. 
91-96 
1- 35 
trace 
2- 94 
trace 
trace 
trace 
2-i' 
r64 
trace i trace 
-071 -01 
VII. 
92-119 
3-03 
trace 
2^16 
•021 
trace 
trace 
trace 
•17 
2-29 
trace 
•21 
MEAN 
92-35 
2-22 
-06 
•26 
The same author, treating of the Chemical causes concerned in 
the formation of Beekite, describes the following experiment : — " A 
fragment of recent coral was fitted into the neck of a funnel and a 
one per cent, solution of silica (prepared from silicate of potash by 
Graham's dialytic method) containing a little carbonic acid gas, was 
allowed to drop slowly on the coral and filter through : after a time 
the liquid ceased to pass. The filtrate contained no silica but 7nuch 
carbonate of lime. The fragment of coral had lost nearly all its 
lime, but had retained its structure in great measure ; it was, 
however, covered with a thick film of gelatinous silica, and was very 
soft. In such a reaction as this, it is not unlikely that a small 
portion of lime would be retained as silicate. Where the process 
of silicification has gone on to its completion, we have a tolerably 
exact reproduction in silica of the original organism, the result being 
in the case of corals, sponges, &c., a light hard porous mass, 
occasionally hollow, of chalcedony. But where the process has 
been arrested by the stoppage of the flow of the siliceous solution, 
the central portions of the Beekite have retained nearly their 
original composition as well us structure ; and in some rare instances 
it would seem that a subsequent deposition of carbonate of lime in 
the spaces not occupied by silica, had taken place." 
The Sandstofies frequently contain numerous scales of both black 
and white mica, the former being most prevalent in Torbay, the latter 
beyond the Exo. Plates " of " Iron sand " are abundant, especially 
