S. Ff. Peckham—The Origin of Bitumens. 111 
the measures of Ohio and West Virginia, among which these 
coals occur, have lost nothing of their volatile content, is with- 
out force here. Professor Shaler objects that—‘‘ The condition 
of the beds that lie below the black shale in the Cincinnati 
group or in the Niagara section shows that there has been no 
great invasion of heat since the beds were deposited. Clays, 
which change greatly under a heat of 1000° Fahr., are appar- 
ently exactly as they were left by the sea, and beds retain 
their marine salts just as when they were deposited. An 
great access of temperature.in this deposit of the Ohio shale 
ave been attended by an almost equal rise of tempera- 
ture in the coal-beds which lie within a few bundred feet 
above; but these coal-beds are free from any evidences of dis- 
tillation or consequences of heat. We have already seen 
reasons for supposing an erosion of some 3000 or 4000 feet of 
strata from this section; if we could reimpose this section we. 
should probably bring up the temperature of these rocks by 
the rise of the isogeothermals or lines of equal temperature 
about 60°. ... Weare not able to suppose that the accumu- 
lation of strata would have elevated the temperature above 
the boiling point of water. The hypothesis which may 
found to account for the formation of this coal-oil must take 
into consideration the impossibility of its generation at another 
point and its removal to this set of beds, and the impossibility 
of supposing that it has been in any way the result of high 
temperatures.” 
e range of temperature between ‘the boiling-point of 
water” and “1000° Fahr.,” which is here allowed, is ample for 
all Pat Sus of explanation. 
endeljeff objects that—“ the sandstones impregnated with 
petroleum, have never exhibited the carbonized remains of 
organisms. In general, petroleum and carbon are never found 
simultaneously.” 
These three objections—first, that the supply of organic 
matter is inadequate; second, that there are no evidences of 
heat action upon the rocks holding the oil; third, that there 
are no residues of fixed carbon observed in the rocks holdin 
the oil—are the objections which have appeared to satisfy — 
those who do not accept the hypothesis that regards petroleum 
as a distillate. I think the first has been already answered; 
the second and third I shall now examine. 
not the effects of heat, as represented by volcanic 
action, that have produced petroleum, although in one notable 
instance Silvestri found paraffine and other constituents of 
petroleum in the lava of Etna. A comparison of the analyses — 
of the gaseous emanations of volcanoes with those of gas and 
petroleum springs shows that the former consist mainly of car- 
