SIMPLE HYDROCARBONS. BS: 
the rock material was in the state of a fine mud; that 
through this mud much vegetable or animal matter was 
distributed, almost in the condition of an emulsion; that 
the stratum of this mud becoming afterward overlaid by 
other strata, the decomposition of vegetable or animal mat- 
ter went forward without the presence of atmospheric air, 
or with only very little of it. Under such circumstances 
either vegetable material or animal oils might be converted, 
as chemists have shown, into mineral oil. Dry wood con- 
sists approximately (excluding the ash and nitrogen) of 6 
atoms of carbon to 9 of hydrogen, and 4 of oxygen. If now 
all the oxygen of the wood combines with a part of the car- 
bon to form carbonic acid, and this 2 CO,, thus made, is re- 
moved, there will be left C,H,; twice this, C,H, is the 
formula of » compound of the Marsh-gas or Naphtha series. 
Again animal oils, by decomposition under similar cir- 
cumstances, produce like results. Removing from oleic 
acid its oxygen, O., and | of carbon—together ‘equivalent to 
1 of carbonic acid—there is left C,, H.,, which is an oil of 
the Ethylene series ; and margaric acid would leave, in the 
same way, Cy, Tas, or a combination of oils of the Marsh-gas 
or Naphtha series. Warren and Storer have obtained from 
the destructive distillation of a fish-oil, after its saponifica- 
tion by lime, several compounds of the Marsh gus series, be- 
sides others of the Ethylene and Benzole series. ‘The de- 
compositions in nature may not have been as simple as those 
in the above illustrations, yet the facts warrant the infer- 
ence that the oils may have been derived either from vege- 
table or animal matters. Fossil fishes are often found abun- 
dantly in black oil-yielding shales, and Dr. Newberry has 
suggested that fish-o1l may be the most abundant source of 
the oil and the oil-yielding hydrocarbons. 
The oil which is collected in great cavities among the 
earthi’s strata, as in Western Pennsylvania, is believed by 
most writers on the subject to have come from underlying 
rocks, such as the black oil-yielding shales. ‘The heat pro- 
duced in the rocks by the friction attending movements and 
uplifts, is supposed to have been sufficient to have made the 
oil from the hydrocarbon of the carbonaceous shale or other 
rock, and co have caused it to ascend among the strata to 
‘the cavities where it was condensed, and now is found by 
boring. 
The oils, exposed to the air and wind, undergo change in 
