250 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1926 
evitable house heating by gas has hardly started. Having learned 
to cook by gas, we shall presently extend its use to the gas-fired 
refrigerator. 
Some 4,400 American cities and towns are now served by gas, 
but many others are still without it. They will before long be 
served by supergas plants designed for long-distance transmission. 
Already manufactured gas is being delivered 60 miles from its point 
of production. We have heard much of superpower plants at the 
coal mines, but their sponsors commonly ignore the fact that the 
enormous quantities of condenser water required for such plants are 
very rarely available at any mine. Supergas plants, on the con- 
trary, require very little water, but may, nevertheless, distribute 
potential heat energy over wide areas. 
As long ago as 1881 Sir William Siemens said: 
I am bold enough to go so far as to say that raw coal should not be used 
as fuel for any purpose whatsoever and that the first step toward the judicious 
and economic production of heat is the gas retort or the gas producer in 
which coal is converted either entirely into gas or into gas and coke. 
Very recently, as the result of much research in France and Ger- 
many, an entirely new field has been opened to the gas companies 
through the production, from water gas, of methyl alcohol and gas- 
oline. It has been a serious and not wholly undeserved blow to 
the distillers of wood in this country, who have not yet learned that 
the price of progress is research. It promises, none the less, ulti- 
mately to afford the gas companies a means of equalizing the present 
spread between their summer. and winter load and the broader 
gap confronting them as their activities are extended to include 
house heating. 
PETROLEUM PRODUCTS 
While the origin of the coals and lignites must be regarded 
as established beyond question, there is another series of carbon 
products, secondary only to them in importance, the beginnings of 
which are still the subject of some controversy. Concerning this 
series Le Conte says: 
Collected in fissures beneath the earth, or issuing from its surface we find 
a series of products, some solid like asphalt, some tarry as bitumen, some liquid 
as petroleum, some volatile as rock naphtha, and some gaseous. There is little 
doubt that all are of organic origin. 
The genesis of the petroleum series is, nevertheless, still attributed 
by some to the formation and reactions of carbides within the 
earth’s crust, but the weight of evidence certainly favors the assump- 
tion that the hydrocarbons of the petroleum series are the product 
of the decomposition of plant or animal remains and most probably 
the latter. 
