366 SF Peckham on the probable origin 
and solidifies on cooling. If the cavity were not sealed, and 
the temperature gradually decreased toward the surface, frac- 
tional condensation in the crevices of the rocks must be the 
result, the heavier portions succeeding the lighter as the descent _ 
was made, This latter supposition makes no provision for the 
ruptured crust and filling of the fissure, nor for the absence of 
petroleum in the immediate vicinity, of every degree of density. 
The first hypothesis—that the veins were ever filled with 
liquid petroleam—appears to me to be impossible ; the second — 
—that they were filled with the material in its present form, a — 
residue from the distillation of petroleum—may be possible — 
but not probable. 
he hypothesis first announced by Prof. Wurtz, is at every 
to pass through the mass to be distilled, and bear away all the 
volatile products at the lowest possible temperature, Also 
* Loe. cit. (note,) 
+ Geology of New York, Pt. III, by L. Vanuxem, p. 34. 
ea irik 
