OIL, GAS, AND ASPHALT. 
A number of papers describing the results of recent field work by 
the Survey in various oil, gas, and asphalt fields are here presented. 
In addition to this new material, a chapter on the origin and distribu- 
tion of asphalt and bituminous rocks in the United States is here 
reprinted, in greatly condensed form, from a detailed publication on 
that subject issued by the Survey in 1902. This has been done, as 
the portion reprinted serves as an excellent summary of the subject, 
and as an introduction to the other papers on asphalt here included. 
ORIGIN AND DISTRIBUTION OF ASPHALT AND BITUMINOUS 
ROCK DEPOSITS IN THE UNITED STATES. 
By Gr. H. Eldridge. 
CLASSIFICATION OF HYDROCARBONS. 
The classification of W. P. Blake, slightly modified, follows. 
Classification of natural hydrocarbons. 
, Gaseous /Marsh gas. 
\" Natural gas." 
Fluid /Naphtha. 
I Petroleum. 
Maltha. 
Viscous ( malthite) 
Bituminous 
a 
o 
z 
W 
Solid 
Asphaltite. 
I Coal 
Mineral tar. 
Brea. 
Chapapote. 
Elastic jElaterite (mineral caoutchouc) 
I Wurtzilite." 
Albertite. 
Impsonite. 
Grahamite. 
Nigrite. 
Uintaite (gilsonite). 
Lignite. 
Bituminous coal. 
Semibituminous coal. 
Anthracite coal. 
{Succinite (amber). 
Copalite. 
Ambrite, etc. 
Cereous _ / Ozocerite . 
IHatchettite, etc. 
Crystalline . /Fichtelite. 
lHartite, etc. 
Resinous 
296 
" Wurtzilite might, perhaps, better be classed with the asphaltites. 
