C 517 3 
XXX. On Bitumen in Stones. By the Right Honourable 
George Knox, F. R. S. 
Read June 12, 1823. 
In a Paper which I had the honour of presenting to the 
Royal Society on the 9th of May, 1822, I stated my intention 
of proceeding with an inquiry into the existence of bitumen 
in certain stones, not generally supposed to contain such a 
substance. The result of the investigation, I now beg leave 
to submit. 
In the Paper referred to, I described the manner in which 
the pulverised stone was distilled, in order to obtain the 
volatile ingredients. I had at that time detected a bitu- 
minous substance in two varieties of Pitch-stone, the Newry, 
and the Meissen. I have since subjected to the same process 
the following minerals, viz., 1 . Arran Pitch-stone ; 2. Pearl- 
stone, from Tokay, in Hungary ; 3. Pumice, from Iceland ; 
4. Amygdaloid, from Disco Island ; 5. Basaltic, or Secondary 
Green-stone, from Newry ; 6 . Transition Green-stone, from 
Carlingford Mountain in the County of Louth ; 7. Bole, 
from Disco Island; 8. Basalt, from the Giants' Causeway; 
9. Basalt, from Disco Island ; 10. Transition, by some con- 
sidered Primitive Green-stone, from Clack Hill, near Castle 
Wellan, in the County of Down, Ireland ; 11. Wacke, from 
Disco Island; 12. Iron Clay, from Disco Island; 13. Iron 
Clay, from Howth ; 14. Hornblende, from Schneeburg, Upper 
Saxony ; 15. Tourmaline, from Karorulik, in Greenland ; 
