540 MINERALS YEARBOOK

with the vapor-pressure requirements of motor fuel. On January 1, 1932, the
Natural Gasoline Association of America adopted a differential scale of grading
natural gasoline based on vapor-presstire specifications, whereby refiners
or marketers can select a blending material that will meet their particular
requirements. This grading scale, closely defining the composition of the
products, enables buyers to determine in advance the quality of motor fuel
produced by blending. The basic grade is now classified as grade 26-70' and
is comparable with the former AA grade of natural gasoline. This product
is virtually propane-free and has a butane content of 35 percent.
 The effects of the foregoing factors on the economic structure of the natural-gasoline
industry are reflected in the following review of quantities distributed.
 Blended at refinerie8.—Since 1929 the refinery demand has been decreasing
steadily, each year showing a marked decline from that preceding. In 1932
a drop of 26.2 percent from the 1931 total reduced the amount blended at
refineries to 1,053,402,000 gallons (70.1 percent of the total production
of natural gasoline for the year).
 The refinery utifization of natural gasoline by districts in 1931 and 1932
is given in the accompanying table. Except for the Ok1ahoma~~ Kansas-Missouri
and the Inland Texas districts sharp reductions in the volume blended by
refineries occurred in all districts in 1932.
 The extremely large decrease of 57.5 percent in the amount of natural gasoline
used at refineries in the east coast district reduced the volume blended
with naphthas, to 26,922,000 gallons, less than 1 percent of the total motor-fuel
output from this district during the year (2,866,962,000 gallons). Although
the expansion of cracking facilities and vapor-recovery units is an important
factor in the decline in utilization of natural gasoline by refineries in
this district, the remoteness of these refineries from sources of supply
is partly responsible for the small amount of natural gasoline blended with
motor fuel. Despite the prevailing low prices of natural gasoline transportation
charges increase its cost at these refineries to such a degree that the existing
small operating margin between the manufacturing cost of motor fuel and its
selling price at the refinery precludes the purchase of natural gasoline
for blending in this district.
 Compared with 1931 relatively small declines in the refinery usage of natural
gasoline were recorded in the Oklahoma-Kansas-Missouri and inland Texas districts—9.4
and 8.1 percent, respectively. These small reductions are accounted for by
the fact that many large refiners in these districts are also large manufacturers
of natural gasoline. In 1932 the percentage of natural-gasoline content in
refinery output of gasoline in the Oklahoma-Kansas-Missouri district was
9.4 and in the inland Texas district 11.6 percent.
 During 1932 the second largest reduction in the amount of natural gasoline
blended at refineries was recorded in the Texas Gulf coast district, which
showed a decrease of 49.3 percent, indicating further contraction of the
major market for Mid-Continent manufacturers. Of the total output of refinery
gasoline from this district 4.7 percent was natural gasoline.
 1 Grad~26—7O represents vapor pressure of 26 pounds per square inch
abs. at 1000 F. (Reid) and 70 percent evaporated at 140° F.