76 Essay on the Transition Rocks of the Cataraqut. 
This curious substance appears to me, very decidedly, to be an in- 
filtration, as the cup-shaped ends are invariably present, either as a 
whole or in part, and are uniformly thicker by many lines than the 
vertical portions, whilst the bottom of the cup is'‘again thicker than 
its own sides, which also gradually thicken as they curve down. 
In the denuded masses of the limestone it is much more easily ex- 
tracted than in those which have not been long exposed to the action 
of the atmosphere, and the upper surface of the limestone has then 
The skeleton, after being left twelve hours, suffered no alteration. It was then put 
into a strong solution of prussiate of potassa, but no variation took place; the solution 
remaining colorless. 
now removed into a glass mortar, with a small portion of water, and on 
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slightly pressing it, it gave way and was with very little trouble pounded into a 
brown muddy mass, resembling clay. Upon this mud, the solution of prussiate of 
potassa was poured, when the usual indication of tritoxide of iron was observed. 
When the precipitation had fully taken place, the solution was decanted and nitric 
acid poured over the precipitate, but no change nor any developement of lime took 
place until the prussiate of potassa was again admitted and the vessel slightly shaken, 
when the whole solution turned of a lively greenish ea ae a few hours a ¢o- 
A little of the last nitric acid had been decanted off peavisiiliy to the last experi- 
ment, but after it had remained for some hours at rest and muriate of soda was drop- 
to it, nothing occurred; the muriate subsiding in its proper form and remain- 
ing Fe, d, 
riatic acid, both dilute and , the adhering limestone dissolved very slow- 
ly tek wit ate less efferveseetice than i in the nitric, but a copious deposit occu- 
ied the bottom of the vessel, which after twenty four hours was converted into 2 
hind jelly like substance, resembling borax when deprived of its water of erystal- 
lization. The mineral itself remained unchanged, although it required several fresh 
8 
a portion of this substance accidentally, on a glass stirring rod, and holding it to the 
blue flame of a candle at the bottom, it bubbled violently, and communicating @ 
vivid rose red light, (probably from the presence of the acid,) to the flame, it s0oP 
dried into a hard white coating on the glass, which required some trouble to remove- 
For want of time and materials I could not continue the application of chemical 
ses. 
specific gravity is 2.5, or the same as the in Scaling or invested limestone. 
It has scarcely any action with the electrometer, although every precaution Wa 
used ; its elect ricity, therefore, is feeble. 
Ma; , by the usual modes, shewed no action, or at least very feeble if any: 
Phosphorescence—none apparent, in any way. 
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