ORIGIN OF PETROLEUM. 89 
which he thus obtained from the sources-‘named are to be found illumi- 
nating oil, lubricating oil, benzine, and paraffine. Engler’s results were 
published in 1888. 
The animal world has thus been definitely proved to be, at least in its 
higher divisions, a possible source of petroleum and its various deriva- 
tives. And now comes Dr S. P. Sadtler, of Philadelphia, who has ex- 
tended a similar line of investigation to the vegetable world as well. In 
an important paper read before the American Philosophical Society 
February 5 of the present year he made known the results of the work 
which he had recently carried on and which he still continues in the 
distillation of linseed oil under pressure. He obtained by this process 
hydrocarbon oils analogous to natural mineral oil or petroleum, and, 
among other products, he produced a good specimen of scale paraffine. 
It is altogether probable that oils derived from other vegetable seeds 
would show the same characteristics. The vegetable kingdom is thus 
shown to be on the same plane with the animal kingdom as a possible 
source of the bituminous series. 
Daubree, perhaps the most ingenious and successful experimental 
geologist of the century, advanced the same claim at a still earlier day. 
He declared that by the action of superheated steam upon wood he had 
obtained both liquid and gaseous products closely allied to petroleum. 
In his view the concurrent action of water, heat, and pressure on vege- 
table matter furnished an adequate account of the natural production. 
Engler’s discovery is worthily supplemented and balanced by Sadtler’s. 
From the latter we see how hasty and unwarranted the conclusion 
adopted by some, that the origin of petroleum always and everywhere 
is to be ascribed to the products of the decay of fishes. 
Closely related to this latter claim are the facts pertaining to the Tren- 
ton limestone oil field of Ohio and Indiana. This is unmistakably one 
of the most important reservoirs of petroleum that was ever discovered ; 
but it originated long antecedent to the appearance of fishes in the geo- 
logical scale. In placing it before the introduction of fishes I do not 
forget the recent discovery by Mr Charles D. Walcott, director of the Geo- 
logical Survey of the United States, of fish remains in the lower Trenton 
of Colorado. Geologists have not yet had time to assimilate this remark- 
able discovery and to give it its due place in the history of the life of 
the world; but certainly these Ordovician fishes of Colorado might as 
well not have been, so far as the buried life of the world at large is con- 
cerned. Nota hint of the existence of one of them has been found in 
the well worked formations of Ordovician time in any other part of the 
globe. Vast periods of time elapsed after this date, periods measured 
by the deposition of many thousands of feet of the various types of sed- 
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