Bitumen, &c. in Stones. 147 
epearently made e of little else than vegetable and shelly 
hese shells, 1 some time since forwarded a few 
eecintna, in a box with other minerals, to Prof. Silliman.* 
If, my dear sir, these remarks are sufficiently definite to be 
useful to you, I shall rejoice in having had it in my power 
to oblige a friend = =e of our dear departed 
brother, and in whatever way we can serve you in any future 
inquiries that may eee eemnsties we beg yon will make. 
ase of us without apolo 
Yours, truly. Jsaac Biro. 
Art. XX.—Bitumen, and other volatile ingredients, in 
Stones. 
In the analysis of stones, a considerable per centage is often 
set down as loss. The progress of chemistry has constantly 
tended to diminish the amount of loss, by showing that cer- 
tain principles, usually either soluble or volatile, had been 
overlooked. It was long, before fluoric acid and the fixed al-— 
kalies were discovered in minerals, and lithia has recently 
been added to the catalogue of their constituent principles.— 
The existence of bitumen in stones has been a good while 
known, but it seems to have been reserved for a late writert 
to prove, that this eae exists in many stones, in most of 
which its presence had n en even suspecte r. Knox 
ascertained the loss of cits ee: igniting the powdered sub- 
stances in a platina crucible, and discovered the nature of gd 
volatile parts, by distillation in an iron retort. 
* For a notice of them, see Vol. X. p. 21, of this Journal,.— 
+The Rizht Hon. George Knox, in the Philosophical ea edd for 1823. 
The paper on this sohject was forwarded by Dr. Wm, Meade to the Editor. 
