236 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1919. 
In spite of the vast and even overshadowing importance of pe- 
troleum and its products as war supplies, space permits only an inci- 
dental reference thereto. The United States leads the world in 
petroleum production and provides about two-thirds of the world's 
supply. Fuel oil has revolutionized naval design and tactics, and 
during the fiscal year of 1919 the Navy used 10,500,000 barrels. 
Practically every piece of operating machinery in the world de- 
pends for its proper functioning upon the lubrication of its moving 
parts by petroleum products. Automotive transportation and the 
flight of airplanes depend for the present at least on gasoline. We 
have reached the peak of our petroleum production, and consump- 
tion has overtaken the supply. Fortunately, we have another source 
of gasoline in natural gas, from which we secured in 1913, 24,000,000 
gallons and in the first half of 1918, 175,000,000 gallons. Here, 
again, we have, however, no promise of a continuing supply. 
The effective use of the airship and the observation balloon as 
instruments of war is greatly curtailed by reason of the dangers due 
to the extreme inflammability of the hydrogen upon which their lift- 
ing power depends and the explosive character of mixtures of hydro- 
gen and air. When a balloon was hit by an incendiary bullet the 
interval between the initial burst of flame and the final explosion 
was rarely more than 15 to 20 seconds. The average life of a kite 
balloon on an active sector of the Western front was 15 days, while 
some lasted only a few minutes. It became obvious, therefore, early 
in the war that if it were possible to substitute for hydrogen a non- 
inflammable gas of substantially the same lifting power the military 
value of both balloons and airships would be greatly augmented. 
Such a gas — helium — was known to exist in the atmosphere in the 
proportion of 1 volume in 250,000 volumes of air. Its existence in 
proportions reaching 2^ per cent by volume had been demonstrated 
in the natural gas from certain wells in Kansas, Texas, and else- 
where, but prior to 1916 the total world production had not reached 
100 cubic feet at a cost of $1,700 or more per cubic foot. On armistice 
day we had on the docks 147,000 cubic feet and were building plants 
for the extraction of 50,000 cubic feet a day. Thus through the dec- 
laration of war has a natural resource, so rare as to constitute a chem- 
ical curiosity, suddenly been established as a military necessity of 
the first order. Helium can not be ignited or exploded ; its diffusion 
rate through balloon fabrics is about two-thirds that of hydrogen ; it 
has over 92 per cent of the lifting power of hydrogen; it permits 
with comparative ease the passage of electric discharges, and had 
it been available in quantity would have placed the entire aero- 
nautical program on a vastly more effective basis. 
