1888. ] NEW YORK ACADEMY OF SCIENCES. all 
[I. Keir Molliet.] ‘‘Sketch of the Life of James Keir.” 
London, n.d. [1868]. 
[W. Withering.]  ‘‘ The Miscellaneous Tracts of Wm. With- 
ering with a Memoir of his Life, Character, and Writings.” Lon- 
don, 1822; 2 vols. 
[Priestley.] A volume of sixty-eight letters from Dr. Priestley 
to Mr. Wilkinson, preserved in the Warrington Library. 
Dr. J. 8S. Newserry read the paper of the evening, entitled 
THE NEW OIL-FIELD OF COLORADO, AND ITS BEARING ON THE 
QUESTION OF THE GENESIS OF PETROLEUM. 
(Illustrated with specimens and drawings.) 
(Abstract. ) 
The speaker had visited during the past summer the oil-bear- 
ing region of Colorado, and studied it in both its practical and 
its scientific aspects. Itis evidently an important and promising 
oil-field, and has interesting geological relations as well. 
Petroleum was found as much as twenty years ago in the 
neighborhood of Cafion City, but no paying wells were worked 
until within three or four years past. When the speaker was in 
‘Colorado in August, the number of wells was about twenty-five ; 
it has now increased to forty, all at or near Florence in the Ar- 
kansas Valley, not far from Cafion City. These wells do not 
spout, but yield a steady supply of from twenty to a hundred 
barrels daily, the average being about fifty or sixty, and the total 
about a thousand barrels per day. The land in the entire vicin- 
ity, over 50,000 acres, is owned by a single company, and gives 
indications favorable to a large yield ; but actual borings have 
thus far been made in but a limited part of the area, only a few 
hundred acres ; and surface indications, however promising, are 
not always proof of permanent and available supply. ‘This was 
found to be the case in California, where the surface prospect 
was frequently excellent, but the stratigraphical conditions be- 
neath were unfavorable, and the yield consequently small. Still, 
the Colorado oil-field bids fair to be an important one, and is 
favorably situated for delivery upon the market. 
From a scientific point of view, it is of much interest to find 
petroleum here obtained from a new geological horizon, the 
middle Cretaceous. The oils of Italy and of California are Ter- 
tiary ; those of Pennsylvania are Devonian ; those of Findlay, 
Ohio, and Collingwood, Canada, are Lower Silurian, etc. Here 
the rocks that yield the petroleum are the Colorado Shales, which 
