Geology and Natural History. 369 
But in the outset one source of error must be guarded against. 
The specimens of co: rom which the foregoing ana eng were 
chters made a recent comm ce to a German 
eR in which he states his opinion ‘that the westberin of 
coal depends upon its ability to absorb oxygen, ip binge the 
hydro-carbons i into water and carbonic acid. eat, say of 
375° I’. only 5 or 6 per cent. of the carbon accepts exyaens the rest 
seems to show little or no disposition to affine with it. The F ro- 
But w coal, col at ordinary temperature, the aca is 
80 > a as to be imperceptible, even after exposure for a tire 
r € says moisture has no accelerating effect, unless pyrites 
Herr Grundmann, of Tarnowitz, on the other hand, - recently 
published elaborate. pg ipesccig i tee the effects exposure 
on bituminous coals to be mo ous. Coal which oe exposed 
for nine months lost jifty per ‘eon cof its value as fuel. His con- 
in connection with Herr Varrenthap , of Brunswick, who prov ed 
by laboratory phreianye'> that oxidation took place at common 
“33 phceraars Le ee months sufficed to rob coal, kept uniformly 
ey Q ° F.) of all vag hag ttn a heat less than that 
: Fs i proved that the ae was the same in the 
middle of the heap as at the surface, and reached its maximu 
absorbs it most rapidly ; that moisture is an bas geo condition ; 
that coals making, when freshly mined, a firm — coke o 
good quality, make, after even only eleven days expos either no 
coherent eoke at all, or coherent coke of quite eda quality. 
or gas purposes, also, the coal is greatly inju 
It is evident that these facts have an important bearing on the 
ve. 
2. On the Os wells of Terre Haute, Indiana; by 7... Sreax 
Hunr. Abstract of a a paper presented to the American Association 
for the Ne eater of Science, Indianapolis, Aug., 187].—In pre- 
Vlous publications I have en eavored to show that the 
that 
ous petroleum. I have, however, expr ressed the opini : 
the “pa, sandstones in Pennsylvania are also truly oleiferour. 
