518 
The Right Honourable George Knox 
i 6 . Augite, from Arendal, Norway ; 17. Serpentine, from 
Zoplitz, Upper Saxony; 18. Clay Slate, from Bangor, North 
Wales ; 19. White Felspar, from Killiney, near Dublin ; 20. 
Flesh-red Felspar, from Aberdeen, Scotland ; 21. Menilite, 
from Menil Montant, near Paris ; 22. Adhesive Slate, from 
Menil Montant; 23. Mica Slate, from Freyburg, Saxony; 
24*. Mica, from the Ural Mountains, Siberia ; 25. Obsidian, 
from the Lipari Islands ; 26 . Fetid Quartz, from Nantes in 
France; 27. Common Quartz; 28. Rock Crystal, from the 
Cape of Good Hope. 
How far the investigation has been successful, or otherwise, 
the following details will determine. 
1. Arran Pitch-stone . 
This specimen was of a very dark oil-green colour, passing 
into raven black ; the fracture conchoidal in all directions, 
with numerous dots of pearl-grey felspar. 
It lost by ignition in a platina crucible 4,7059 per cent. ; 
at a higher heat it fused, and lost on the whole 5 grains ; 
when distilled in an iron retort 4,5 per cent, of water and 
bitumen came over : as nearly as I could estimate 2 per cent, 
was bitumen. It appeared to be similar to what I had ob- 
tained from the Newry Pitch-stone. 
The retort contained a substance resembling pumice, but 
not sufficiently indurated. It broke into joints like those in 
basaltic columns, one end of each joint being convex and the 
other concave. The colour changed to milk-white. 
2. Pearl-stone. 
100 grains lost by ignition 3,25, and changed from ash- 
grey to reddish white, having probably gained oxygen. 
