Geological Society.—Royal Institution of Great Britain. 223 
of coarse shelly limestone, analogous to the upper fresh-water 
formation of Paris, and quarries of it occur near Wisbaden 
and Hockheim: Paludine and Modioli abound in it. At 
’ Hockheim the beds are much dislocated; and at Wisbaden 
fossil bones are found, the teeth accompanying which refer 
them to animals allied to the Lophiodon tapzroides, and to the 
Sumatran Tapir. These calcareous deposits are only two hun- 
dred feet above the level of the Mayne, and they are per- 
forated in many places by basalt, upon which they rest. The 
basalt finally disappears south-east of Darmstadt, and is suc- 
ceeded by primitive rocks. ‘There are strong salt-springs at 
Soden, and various mineral waters near Frankfort and Had- 
nigstein. 
The Falkenstein mountain, though composed of talc-slate, 
protrudes through the high table land in the form of basalt. 
To the north of this the older rocks disappear, and the district 
is occupied by grauwacké. ‘The grauwacké is divided into 
quartz grauwacké and grauwacké slate; the latter is very di- 
stinct from micaceous slate, and contains casts of Spiriferz, of 
the Pleurobranchi of Cuvier, &c.; the former offers encrinites, 
‘and unknown coralloids. ‘The valley of the Lahn, between 
Coblentz and Diety, affords the best sections of grauwacké, 
and higher up that river the transition limestone appears at 
Baldowinstein. The schalstein (or problematic stone of Von 
Buch), is seen in all its varieties in the valley of the Aar, and 
with it are associated, porphyry, carbonate of lime in veins, 
iron, and copper. At Diety and Baldowinstein, porphyry 
seems to rise through the limestone. Crystalline dolomite, 
resting upon transition limestone, is the most recent formation 
observable in the mountainous ranges of Nassau. No diluvial 
detritus is seen in any part of the duchy, but quartz pebbles 
in sand occur in the elevated plain between Selters and 
Nassau : these are supposed to have been torn from the grau- 
wacké by local causes, and to have been deposited prior to 
the elevation of that formation. The author, reflecting upon 
the marine fossils on the summits of some of these mountains, 
infers, that the horizontal strata were formed at the bottom of 
a sea, and were subsequently elevated; and he is inclined to 
attribute the origin of the grauwacké to the attrition of the 
primitive rocks during the period of their elevation. 
ROYAL INSTITUTION OF GREAT BRITAIN. 
The following is an account of the proceedings at the Royal 
Institution, on the Friday evening meetings of the members. 
Feb. 3.—The history of caoutchouc was given in the lec- 
ture-room by Mr. Faraday, and various specimens relating 
to its chemical nature and its application in producing water- 
proof 
