DEPARTMENT OF THE INTERIOR

UNITED STATES GEOLOGICAL SURVEY

GEORGE OTIS SMITH, DIKECTOK

BUIXETIN' 365

THE

FRACTIOMTM OF CRUDE PETROLEUM 

BY CAPILLARY DIFFUSION

BY

J. ELLIOTT GILPIN AND MARSHALL P. CRAM

UNDER THE SUPERVISION OF

DAVID T. DAY

WASHINGTON

GOVERNMENT PRINTING OFFICE

1908

CONTENTS.

rage.

Introduction.............................................................. 5

Detailed description of experiments........................................ 6

Fractionation in tubes.................................................. 6

Water fractionation..................................................... 28

Oil lost in the fuller's earth............................................. 30

Fractionating power of substances other than fuller's earth............... 32

Summary............................................................... 33

ILLUSTRATIONS.

i'age. 

FIG. 1. Curves showing proportion of hydrocarbons soluble in sulphuric acid,

oils 1 and 2............................'.......................... 24

. 2. Curves showing proportion of hydrocarbons soluble in sulphuric acid,

oils 3 and 4...................................................... 25

3. Curves showing proportion of hydrocarbons soluble in sulphuric acid,

oils 5 and 6...................................................... 26

3

THE FRACTIONATION OF CRUDE PETROLEUM BY 

CAPILLARY DIFFUSION.

By J. ELLIOTT GILPIN and MARSHALL P. CRAM.

INTRODUCTION.

When, in process of refinement, black vaseline is filtered through 

warm, dry fuller's earth, the first product is an oil that is perfectly 

liquid at ordinary temperatures, but the succeeding portions are 

progressively more viscous until fairly hard vaseline is obtained. 

The observation that a fractional separation of oils in vaseline had 

been effected suggested to David T. Day that a like result might be 

obtained with crude petroleum. He applied this method to a sample 

of green crude petroleum from the "third sand" of Venango County, 

Pa., and found that light products, chiefly gasoline, first appeared 

when such crude oil was allowed to filter down through a long glass 

tube filled with granulated or powdered fuller's earth.a

This result was followed by experiments with a more elaborate 

system of specially constructed funnels similar to those used by the 

refiners of vaseline in testing the comparative value of various fuller's 

earths. . The results from these experiments were briefly summarized 

in a paper on the ability of petroleum to migrate in the earth. 6 

Engler later verified these results and showed that the separation 

was mechanical and that no oxidation was effected in the process. 

Day next used a large closed funnel of galvanized iron holding about 

100 pounds of fuller's earth. When crude petroleum was dropped 

slowly and regularly into this funnel, rather light oils were obtained 

at first, followed by the usual succession of heavier oils. As it was 

evident from this work that much of the oil passed through crevices 

without any change, Day tried the effect of reversing the route of 

the oil and of allowing it to diffuse upward through a tube packed 

tightly with fuller's earth. In such a tube the lighter constituents 

rose much more rapidly than the more viscous oils, so that by separatoProc. Am. Philos. Soc., vol. 36, No. 154,1897. & Trans. Petroleum Congress (Paris), 1900.

5
6 FRACTIONATION OF CRUDE PETROLEUM.

ing the fuller's earth from different sections of the tube and displacing 

the oil by water, very different oils were obtained from the upper 

and lower parts of the tube.

By using several tubes and uniting oils of the same specific gravity 

oil of different grades can be collected in sufficient quantity to be 

fractionated again, and the process can be continued until oils result 

which are not altered by further passage through tubes fillecl with 

fuller's earth. At the suggestion and with the cooperation of Doctor 

Day we have taken up this problem with the results here stated.

DETAILED DESCRIPTION OF EXPERIMENTS.

FKACTIONATION IN TUBES.

The tubes used first were of glass, 3 feet long and 1| inches in 

diameter. They were closed at the lower end with corks along 

whose sides six or seven grooves had been cut, the inner end of the 

cork being covered with a bit of cotton cloth to prevent the earth 

from sifting out through the grooves. Such tubes filled with fuller's 

earth were placed with their lower ends, in an open dish of petroleum 

and the oil was allowed to rise.

At room temperatures (18° to 22° C.) and atmospheric pressure, 

the rate of rise of crude petroleum in a tube filled with fuller's earth 

was very slow. In seven clays the oil ascended but 73 centimeters 

in one tube and 59 centimeters in another, and in a third tube ten 

days were required for it to rise 59 centimeters. To study the 

effect of heat, a glass tube about 3 feet long and 1J inches in diameter 

was filled with earth and placed in a bottle holding about 2 liters of 

oil; and the whole was heated by an electric stove with which temperatures considerably above those of the room could be maintained 

day and night. The temperature of the tube was kept between 40° 

and 70° for three days, in which time the oil rose 54.7 centimeters in 

the tube; in another tube packed in all ways like the first, but held 

at room temperature (about 20°), the oil rose 46 centimeters in the 

same length of time. With two tubes in which the earth was packed 

much less compactly the time required for the oil to rise 54 centimeters was four days for the tube at room temperature and two days 

for the one at 50° -to 80°. The rate of rise was evidently but little 

affected by heat, at least within this range of temperature, and higher 

temperatures could not be used without loss of the more volatile 

constituents of the oil.

The next attempt at increasing the rate of rise of the oil consisted 

in applying diminished pressure to the top of the tube, which reduced 

the time required for the oil to reach the top of a tube 5 feet long 

from several weeks to seventeen hours. If diminished pressure is
FRACTIONATION IN TUBES. 7

continued after the oil has reached the top and if the oil is not 

exhausted in the reservoir at the bottom, oil will be drawn over from 

the top of the tube. The specific gravity of the oil thus collected 

steadily rises as it comes over. The samples so obtained, however, 

stand under very low pressures for some time, which may cause a 

loss of their more volatile constituents. This suggested applying 

increased pressure to the oil in the reservoir rather than diminished 

pressure to the top of the tube, and an iron bomb, like those used for 

the transportation of mercury, was fitted with an iron pipe 7 feet 

long to contain earth and a side arm at the bottom of the bomb to 

which a water.column might be attached.

The bomb, which held about 2 liters, could be partly filled with 

petroleum and the pipe containing the earth screwed into the top. 

The side arm which opened into the bottom of the bomb could then 

be connected with the water pressure so that the lower part of the 

bomb was filled with water which drove the petroleum upward. 

The oil obtained at the top, however, was fractionated no further 

nor in any larger amounts than when the oil was not allowed to 

emerge from the top of the tube. The difficulty of setting up such a 

pressure apparatus with tight connections, as well as the range of 

pressure required a column of water 7 feet high being too great when 

the oil was just started up the tube and a column 30 feet high being 

insufficient when it was near the top made its use impracticable.

To use diminished pressure, the earth in the tubes must not be 

packed so hard that the air just above the oil can not be drawn 

through the earth above, nor must the earth be packed so loosely that 

the oil will rise as in a vacuum. The right degree of hardness is 

obtained by filling about 1 foot of the tube at a time and packing that 

much earth as hard as possible with a wooden rod tipped with a 

rubber stopper. If the tube when pounded on the floor rings in the 

hand, it indicates that the earth may be packed too closely. Tubes 

may be packed much more easily by filling several at once, with a 

separate ramrod for each. By allowing a few minutes to elapse 

between successive liftings of the ramrod, much labor is avoided. A 

bit of cotton waste below a rubber stopper at the top of the tube will 

prevent any earth from being drawn up when the air is exhausted.

The fuller's earth was first heated in shallow iron pans until it 

ceased to form geysers when stirred. The" earth must be thoroughly 

cold before it is packed into tubes, or the contraction will be sufficient 

to allow the oil to run up the tube immediately when the air is 

exhausted. , Much trouble was experienced with the tubes first used on account 

of their breaking not when in service, but soon afterward. This was 

thought to be due to the age of the tubing, but the same thing hap-
8 FKACTIONATIOET OF CKUDE PETROLEUM.

pened with new tubes 5 feet long and 1£ inches in diameter. With 

the idea that the iron scraper used to remove the earth from the tubes 

might be the cause, a scraper entirely of wood was tried, but this did 

not decrease the breakage, it being nothing unusual on going to the 

laboratory in the morning to find that half of the tubes which had 

been emptied the day before were cracked.

It had been considered necessary to use tubes of glass in order that 

the height to which the'oil had risen could be seen and that in removing the oil from the middle of the tube it might be scraped out to a 

sharp dividing line, as the level to which the oil has risen is the point 

from which should be made all measurements of sections into which 

the tube is to be divided. Tin tubes were used later to avoid the 

trouble experienced with glass tubes. These tin tubes were emptied 

by shaking the earth from the bottom into four 30-centimeter cylinders of the same diameter as the tube, these cylinders being made of 

two curved pieces of tin held together by a cap at one end and a ring 

at the other. The cylinders containing the contents of the tube 

could be opened lengthwise and the earth divided into any desired 

lengths. Two glass tubes 5 feet long and 1£ inches in diameter were 

set up in the same dish of petroleum with ten or twenty tin tubes 5$ 

feet long and of the same diameter as the glass tubes, and when the 

oil stood at the top of the glass tubes the tin ones were also opened. 

Glass tubes, of course, can be emptied as well as tin tubes by shaking 

the contents from the bottom, and there was no more breakage after 

this method was adopted.

The level to which the oil will rise can be regulated by the amount 

of oil in which the tube is placed, and in the later work the adoption of this method did away with the use of glass tubes entirely. In 

a tube 1J inches in diameter and 5J feet long 950 cubic centimeters 

of oil will rise within 20 to 3'5 centimeters of the top.

When the oily earth has been removed from the tube, the oil may be 

separated by adding water. In the first experiments enough water 

was added to form a very thin mud, which was thoroughly stirred 

by a small propeller driven by a water motor. The mixed earth, oil, 

and water were then poured into a large separating funnel and allowed 

to stand several minutes until the oil had collected at the top. The 

earth and water could then be drawn off and the pure oil left.

It was found later, however, that if less water is added to the earth 

as removed from the tubes, after standing a few minutes all the water 

will pass into the earth and this will be accompanied by the liberation of oil. Oil so liberated can then be poured off directly from 

the earth without the labor of churning. When water first begins to 

liberate oil, the earth is granular; but when more water has been added 

and the last of the oil recovered, the earth has the consistency of a
FBACTIONATION IN TUBES. 9

thin paste that will flow when the dish is inclined, which it will not 

do when the oil begins to come off.

All the oil from one section of a tube is of the same color irrespective of whether it is the first or the last oil to come off when water is 

added. It was assumed at first that all the oil which came from one 

section'of earth had the same specific gravity, but this was found later 

not to be the case. The first oil to be collected, if taken in sufficiently 

small volume, say about 20 cubic centimeters, is slightly heavier than 

the next portion. If as much as 100 cubic centimeters is included in 

the first sample, however, this will not be true. Beginning with the 

second sample the successive portions of oil steadily increase in specific gravity, the gradual addition of water affording another means 

of fractionation in addition to the separating power of the earth. 

Both of these methods of separation have been combined in this 

investigation. The earth must be thoroughly mixed after each addition of water to prevent a layer of water-wet earth from isolating 

earth that contains oil from the water added.

The petroleum used was a dark-green oil from Venango County, Pa., 

of specific gravity 0.810. When 950 cubic centimeters of this oil was 

drawn upward in a tin tube 5£ feet" long, the following separation 

was obtained:

TABLE 1. Fractionation of crude petroleum in single tubes.

Distance from top of tube to oil when

]

2i

31

Specific 

gravity.

0.796

.808

f .8125

t . 8137 

.815

.818

.8205

.5

Cubic 

centimeters.

42

45

75

24 

130

170

125

Oil

2

17

28

Specific 

gravity.

0. 8012

.804

.807

.809 

. 8125

.8185

.823

.5

Cubic 

centimeters.

30

37

47

22 

148

190

100

574

3

17

28

Specific 

gravity.

' 0. 8022

.803

.8075

.810 

.812

.8175

.821

.5

Cubic 

centimeters.

1 S

 K

GO

25 

140

1 AK

105

534

The oil in grade C was collected in two portions, the second being 

obtained by the addition of more water after the first lot of oil was 

poured off. Although 950 cubic centimeters of crude petroleum were 

used in each experiment, it will be noticed that the oil recovered 

measures much less than that. When several tubes were worked up 

together, in one test 9,070 cubic centimeters of crude petroleum 

yielded 5,951 cubic centimeters of oil and in another 8,915 cubic 

centimeters gave 5,415 cubic centimeters. 

57714 Bull. 365 08 2
TABLE 2. First fractionation of crude petrole

Distance from level of oil to top of tube, 

 in centimeters ;<*

;A.

S>. .......... ..^...... ...................

 C1........'.,..-........ ..................

D....... ..............................

E. .........................................

4.

Glass, 0, 15; tin, 40, 

15, 24, 22, 28, 19, 24, 

32. 

54.

Specific 

gravity.

/ 0.8015 

t .8005

f .807 

\ .810

f .809 

1 .809 

1 .S10 

I . 8115

.815 

. 8145 

.8175

.816 

.815 

.821

Cubic centimeters.

50 

350

260 

190

100 

400 

225 

260

425 

625 

460

440 

400 

830

5.

Glass, 0, 6.5; tin, 26, 

28, 18, 15, 28, 12, 24.

24.

Specific 

gravity.

0.804 

.8055

.8085 

.811

.8097 

.8122

.813 

.8135 

.816

.8162 

.8162 

.819

Cubic centimeters.

100 

190

220 

120

430 

300

530 

600 

200

480 

725 

390

6.

2 glass, 8 

Glass, 0, 

28, 22, ,

54.

Specific 

gravity.

0.805 

. .805

.807 

.8097

.810 

.8135

.8133 

.816 

.8175 

.825

.816 

.8195 

.821

.827

tin ........

12; tin, 30, 

30, 13, 12.b

Cubic centimeters.

65 

. 200

140 

125

390 

380

610 

325 

435 

125

850 

260 

330 

325

2 g

G

84

Sp

gr

. 

a The glass tubes are 5 feet long, the tin tubes 5J feet. Both are 1J inches in diameter.

6 Record of distance lost for two of the tin tubes.

c These fractions stood uncovered on top of the earth overnight, and consequently were 
TABLE 2. First fractionation of crude petroleum 

! ia

Distance from level of oil to top of tube, 

in centimeters."*

A........................................

B. ...............:.......................

C.............. ..........................

E. ...................... ......... .........

2 glass, 9 

Glass, 0, J 

32, 36, 2 

25, 18. 

84.

Specific 

gravity.

1

0. 7995 

.8037 

.806

f .8085 

1 .810 

| . 8112

1

.810 

.812 

.8135

1

.8148 

.8175 

.817 . 

.817

f . 8197 

I . 8215 

.8223 

( .821

3.5; tin, 40, 

6, 27, 20, 27,

Cubic centimeters.

200 

160 

23

125 

275 

23

350 

525 

150

440 

' 700 

370 

200

315 

720 

570 

215

ll.«

Glass, 0, 4; tin, 0, 0, 

0, 0, 20, 17, 7, 5.

39.

Specific 

gravity.

0.799 

.802

.807 

.8115

.810 

.811 

.8145

.8133 

.8133 

.816 

- .8142

.8172 

.818 

.819 

.8175

Cubic centimeters.

80 

180

200 

140

300 

490 

175

450 

530 

290 

250

400 

520 

405 

370

12.6

2 glass, 0 tin.. ......

Glass, 7, 13; tin, 32, 

19, 32, 35, 48, 29.

60.

Specific 

gravity.

0.798 

.801

.8022 

.806 

.8072

.807 

.809 

.8115

.811 

.8097 

.811 

.815

.815 

.8148 

.815 

.817

Cubic centimeters.

150 

140

 160 

105 

20

400 

200 

60

400 

420 

290 

60

260 

510 

400 

100

G

2

S

g

o During the night, oil was drawn entirely through and out at the top of five tubes and so was lost.

b Three other tubes were set up with thes'e, but when opened the oil in .them was 81, 81, and 90 centime

between the tubes was probably caused by using in some of them earth which was not entirely cold, 

c Beginning with lot 13 the pump was run continuously day and night, 

d The glass tubes are 5 feet long, the tin tubes 5i feet. Both are 1| inches in diameter.
TABLE 2. First fractionation of crude petroleum C

Tubes ...................................

Distance from level of oil to top of tube, 

in centimeters. 6

A .......... .............. ......... ...

B.......... ....."..,. ....... ....... .

C.. ......................................

D... .....................................

E....... ......................:..........

16.

2 glass, 9 

Glass, 0, 

19, 16, 1 

4,2.

16.5.

Specific 

gravity.

I 0.800 

4 .8025 

[ .8028

j .8042 

1 .8065 

[ .810

1

.8085 

.8085 

.8115

f . 8117 

1 . 8135 

1 . 8137 

(. . 8184

£ 

be

tin........

0.5; tin, 24, 

5, 17, 23, 17,

Cubic centimeters.

125 

200 

80

245 

100 

110

230 

600 

210

435 

650 

370 

350

See 

low.

17.

1 glass, 9 

Glass, 14 

13, 6, 8,

17.

Specific 

gravity.

0.804 

.8055 

.8085

.812 

.812 

.8127

.814 

.8125 

.815

.814 

.814 

.8145

.817 

.8172

; tin, 8, 27, 

0, 0, 0, 0.

Cubic centimeters.

240 

120 

23

220 

155 

45

500 

450 

40

540 

670 

350

740 

750

18.o

Glass, 8, 5; tin, 17, 

2, 15, 19, 12, 33, 21, 

0,0.

21.

Specific gravity.

0.8005 

.8005 

. 8015

.803 

.803 

.8042 

.8055

.8078 

.8078 

.808 

.8085 

.8095 

.8105

0. 8117 420 

. 8117 680 

. 813 660 

. 8155 90

.8158 

.8158 

.8165 

.8175 

.8187

Gl

4

3

5.

C

" Two reservoirs of crude oil were used in each of lots 18 and 19, but the earth from all 22 tubes was worked 

then, for convenience in working, divided into two portions.

*> The glass tubes are 5 feet long, the tin tubes 5$ feet. Both are 1£ inches in diameter.
FKACTIONATION IN TUBES. 13

To collect a sufficient quantity of oil, several tubes were placed in 

the same container of petroleum, two of the tubes being of glass and 

the rest of tin. When the oil had reached the top of the glass tubes 

all the tubes were opened, and the earth from the same level in all the 

tubes was mixed in tin pails. The oil was then liberated in several 

successive fractions by the addition of successive amounts of water. 

If the earth had been thoroughly mixed after each addition of water, 

the various oils from the same lot of earth would have increased 

regularly in specific gravity, instead of showing the variations which 

they did. For example, the first oil to be displaced by water in 

grades D and E of lot 4 (Table 2), with so large a volume, would not 

have been heavier than the succeeding oils if the water and earth had 

been thoroughly mixed before the oil was poured off. If we were to 

repeat the work, instead of using one common reservoir for all the 

tubes, we should use a separate reservoir for each tube, and open the 

tube when the oil in the reservoir was exhausted. This would do 

away entirely with the use of glass tubes, besides insuring that the 

level of the oil in each tube when opened would be practically the 

same. If a common reservoir is to be used, the tubes should all be 

packed with practically the same degree of hardness if the oil is to 

ascend in all with equal rapidity, as the ascent in all tubes is checked 

at the same time that is, when the oil in the reservoir is exhausted.

Diminished pressure was obtained by the use of a Chapman water 

pump, which reduced the pressure to 5 to 12 centimeters Hg., when 

connected with a system of tubes. In the earlier work the pump was 

not run through the night, which accounts for the much longer time 

required for these lots of tubes.

The earth from a tube was divided into six sections, the level to 

which the oil had ascended in the tube being taken as the point to be 

measured from. A, the top section, included the 8 centimeters next 

the top; B, the next 8 centimeters; C, the next 18; D, the next 30; 

E, the next 35; and F what earth was left. F varied, of course, 

depending on the height to which the oil had risen. In fractionating 

the crude petroleum in bulk, F was usually discarded, as it was so 

viscous that it was deemed impossible to pass it through earth again. 

Records from several lots of tubes are given in Table 2. The specific 

gravity was measured with a Westphal balance, the temperature of 

the oil being in every case exactly 20° C. Although the fourth decimal 

place is not to be taken as strictly accurate, yet it is considered worth 

while to record it as giving a nearer approach to the truth than would 

result from the use of only three decimal places.

To study further the f ractionation on addition of water, the oil of 

grade E from lot 16 was collected in fourteen fractions. The weight 

of the earth impregnated with oil before any water had been added 

was 13.5 pounds, and the weight of the earth containing all the water 

added, but minus the oil, was 17.5 pounds. The earth was placed in
14 FRACTIONATIOET OF CRUDE PETROLEUM.

a galvanized-iron garbage pail and the water stirred in with an iron 

paddle. When the first portion of oil was liberated, the mass was 

of the consistency of bran, but as more water was added it turned to 

a fluid paste. When water was added and the pail inclined, oil would 

continue to drain out for half an hour or longer before the addition 

of more water became necessary. The oil which was liberated by 

one lot of water, therefore, could be collected in several portions, and, 

this was done to see whether the oil which comes off immediately 

after the addition of water is the same as that which drains out 

later. The letters I, II, etc., indicate that the fractions included 

were- liberated by one addition of water.

TABLE 3. Fractionation of oil of grade E, lot 16, Table 2.

T... ...........................

n.. ..........................

in..........................

Specific 

gravity.

0.821

f .818 

\ .818

I .8193

f .818 1 .818

1 . olo

I .820

Cubic centimeters.

25

70 

70

395

oou

60

IV...........................

V.. ..........................

VI...........................

Specific 

gravity.

f 0.8208

1 . 8222 

f .824

I . oZo 

f .827

\ . OOU

Cubic centimeters.

575

55 

170

16 

95

45

The first fraction is regularly of higher specific gravity than those 

immediately following if only enough water is added to liberate a 

first fraction of small volume, say about 20 cubic centimeters. As 

the fraction first obtained becomes larger in volume, it approaches 

nearer to the second fraction in specific gravity, and will even fall 

below that fraction if the volume is made too large.

The range of specific gravity covered by this first fractionation of 

the crude petroleum of specific gravity 0.810 was from 0.800 to 0.830. 

Fractions of the same specific gravity and of the same grade were 

united and the products chilled and filtered to remove all the dissolved paraffin possible. This was done out of doors toward the last 

of December, when the thermometer stood at about 4° to 8° C. 

Lower temperatures would not only throw paraffin out of solution, 

but cause the whole oil to thicken. The oils were filtered through 

large plaited filters of drying paper, twenty-four hours or more being 

required for many of the filters to empty completely. The lighter 

oils in sections A and B deposited no paraffin. Some of the heavier 

grades deposited as much as 10 per cent of their weight, accompanied 

in many cases by a slight change in specific gravity.

When these oils were filtered through earth again they behaved as 

shown in Table 4. As before, 950 cubic centimeters of each oil was 

used and the tube was divided into five sections, A being the top 8 

centimeters, B the next 8, C the next 18, D the next 30, and EF the 

rest.
FKACTIONATION IN TUBES'. 15

TABLE 4. Second fractionation.

(NOTE. Nine hundred and fifty cubic centimeters were needed for each tube, and for many tubes this' 

amount was available of the same grade (A, B, C, etc.) and of the same specific gravity. For some 

tubes, however, it was necessary to unite oils of the same grade which differed slightly in specific gravity. 

No such samples differed by more than 0.0015 and all are marked with an asterisk (*) in the table.]

A........... .........

B. ...................

C.. ..................

D....................

EF..................

A....................

B ....................

c.. ..................

D ....................

EF. ..................

A ....................

B ....................

c.. .........:........

D... .................

:EF. .................

A .................... :B ....................

c. ...................

.D......... ...........

"EF

A ....................

IB ....................

C. ...................

I) ....................

JEF.. ......... .......

20 (A, 0.8015).

Specific 

gravity.

0. 8012 

.800 

f .8012 

\ .8027 

. 8022

.8047

Cubic 

centimeters.

36 

44 

68 

35 

170 

330

683

24 (B, 0.8065).

0. 8077 

.807 

f .808

.8092 

.8115

38 

50 

80

160 

300

628

28 (0,0.8095).

0.805 

.8065 

f .8085 

1 .811 

j .811

.813

52 

52 

70 

28 

160

350

712

32 (0,0.8115).

0.806 

.807 

1 .810 

I .812 

) .812 

i .813 

.813 

.8135 

.813 

.813

45 

35 

60 

33 

70 

97 

103 

105 

50 

47 

a63

708

36 (0,0.815).

0. 805 

.8105 

.814 

.815 

.817

43 

40 

98 

155 

. 280

616

21 (A, 0.800).

Specific 

gravity.

0. 8038 

.8035 

.8035 

.8052 

.805 

.807

Cubic 

centimeters.

45 

48 

78 

28 

160 

320

679

25 (B, 0.809).

0. 8013 

.805 

.807 

.810 

. 8095 

.8115

45 

50 

75 

30 

180 

350

730

29(0,0.810).

0. 8035 

.808 

.810 

.8115 

.8115 

.8135 

.813

40 

40 

75 

30 

140 

40 

350

715

33(0,0.813).

0. 8072 

.811 

.812 

.813 

.8145 

.815 

.8155 

.8155 

.818

20 

35 

70 

25 

90 

80 

200 

125 

35

680

*37 (0,0.8155).

0. 8053 

.812 

.816 

. 8175 

.819

50 

45 

103 

160 

310

668

*22 (B, 0.805).

Specific 

gravity.

0. 7997 

.802 

. 8055

.8063 

.808

Cubic 

centimeters.

50 

50 

108

175 

260

643

*26 (B, 0.81 05).

0. 8075 

.8085 

.8105

.8125 

. 8133

38 

50 

100

160 

275

523

30 (0,0.811).

. 0.8005 

.809 

.812

.813 

. 8145

50 

38 

115

175 

' 310

688

*34 (.0,0.8135).

0.803 

.810 

.813

.815 

.817

42 

53 

100

150 

300

645

*38 (0,0.8155).

0.808 

.8095 

.8135 

.817 

.819

40 

50 

100 

165 

290

645

23 (B, 0/8055).

Specific 

gravity.

0.8005 

.8033 

.805

'.8063 

.8085

Cubic 

centimeters.

45 

48 

115

180 

260

648

*27 (B, 0.812).

0. 8105 

.8J05 

. 8085 

.810 

.8115 

. 8145

42 

42 

73 

22 

140 

250

569

*31 (0,0.811).

0.803 

.808 

.813

. 8135 

.8155

50 

55 

105

180 

300

690

* 35 (0,0.8135).

0. 8025 

.8077 

. 8135

.8145 

.817

35 

35 

100

160 

325

655

*39 (0,0.8165).

0.808 

.8145 

.816 

.8175 

.820

50 

50 

82 

125 

310

017

Unused.
16 FEACTIOFATION OF CETJDE PETROLEUM. 

TABLE 4. Second fractionation Continued.

A....................

B. ...................

C....................

D... .................

EF. .................

A....................

B. ...................

C.... ................

D.. ..................

EF... ...............

B. ...................

C.. ..................

D.... ................

EF. .................

A....................

B. ...................

C.. ..................

D.. ..................

EF. ..............:..

A....................

B....................

C. ...................

D.... ................

EF... ...............

*40 (D, 0.8135).

'Specific 

gravity.

0.8095 

.8085 

f .811

.8155 

.817

Cubic 

centimeters.

45 

45 

95

165 

320

670

44 (D, 0.814).

0.8008 

.8077 

f .814

f . 8175 

| .819

45 

50 

103

160 

310

668

48 (D, 0.815).

0.810 

.805 

1 .812

.817 

.819

37 

47 

105

160 

300

649

52 (D, 0.816).

0. 806 

.8115 

/ .814 

\ . 8175 

.8185 

.821

38 

42 

70 

25 

125 

300

700

*56(D, 0.8165).

0.806 

.810 

.8145 

.8185 

.821

45 

45 

95 

160 

295

640

41 (D, 0.814).

Specific 

gravity.

0. 8045 

.8115 

.8135 

.8165 

.818 

.821

Cubic 

centimeters.

30 

45 

75 

28 

140 

300

618

45 (D, 0.814).

0.800 

.8065 

.8125

.816 

.817

50 

55 

100

ICO 

300

665

49 (D, 0.8155).

0. 8045 

.811 

.815

.8185 

.820

40 

48 

98

160 

310

656

* 53 (D, 0.816).

0.803 

.8105 

.815

.8185 

.820

43 

30 

100

175 

290

638

*57 (D, 0.817).

0. 8075 

.8115 

.815 

.818 

.821

40 

40 

100 

130 

330

640

42 (D, 0.814).

Specific 

gravity.

0.806 

.811 

.813

.8175 

.8195

Cubic 

centimeters.

32 

45 

92

140 

310

. 619

46 (D, 0.8145).

0.808 

.8115 

.8135 

.8155 

.817 

.818 

.8195 

. 8202 

.821

45 

40 

65 

30 

105 

58 

180 

120 

53

696

50 (D, 0.8155).

0. 8105 

.8148 

.810

.815 

.819

45 

47 

100

140 

400

732

54 (D, 0.8165).

0.806 

.811 

.815

.8188 

.8208

47

48 

98

150 

300

643

*58 (D, 0.818).

0.808 

.8135 

.817 

.820 

.822

45 

45 

105 

150 

300

645

43 (D, 0.814).

Specific 

gravity.

0.806 

.8097 

.814

.8157 

.8175

Cubic 

centimeters.

25 

30 

50

145 

400

650

47 (D, 0.815).

0.800 

.807 

.814

.816 

.819

42 

47 

110

150 

330

679

51 (D, 0.8155).

0.8058 

.810 

.8132 

.8145 

.8172 

.8188 

.8188 

.820 

.819 

.8208 

.8208 

.8208 

 .8208

40 

40 

60 

50 

75 

55 

38 

38 

100 

30 

45 

30 

95 

a 40

736

55 (D, 0.8165).

0. 8095 

.8135 

.8145

.8188 

.821

42 

40

77

150 

295

004

59 (D, 0.8187).

0.811 

.812 

.814 

.819 

.823

40 

45 

92 

150 

305

632

Unused.
FKACTIONATION" IN TUBES. 

TABLE 4. Second fractionation Continued.

17

A. ...................

B ....................

c.... ................

D..... ...............

EF... ...............

A....................

B. ...................

C....................

D.... ................

EF. .................

A....................

B. ...................

C.. ..................

D....... .............

EF.... ..............

A ....................

B. ...................

C.... ................

D...................

EF. .................

A....................

B. ...................

C. ...................

D. ...................

EF..................

*CO (D, 0.8205).

Specific 

gravity.

0. 8045 

.813 

f . 8175

| .822

/ .823 

i

Cubic 

centimeters.

45 

45 

90

170

270 

«70

092

*C4 (E, 0.817).

\ 0.805

.810 

f . 8145

f -.820

f . 8255 

I

42

42 

75

135 

235

529

*68 (E, 0.8185).

0. 8205 

.8043 

f '.810 

I .812 

.817 

.8225

15 

35 

CO 

30 

160 

300

590

*72 (E, 0.8195).

. 0.8145 

.8105 

f .8135

.8195 

f .824 

I

30 

42 

103

160 

285

620

* 70 (E, 0.820).

0. 8045 

.812 

.817 

 .822 

.826

48 

40 

91 

155 

260

594

61 (E, 0.814).

Specific 

gravity.

0. 8075 

.810 

.8125

.818 

.8245

Cubic 

centimeters.

33 

35 

80

125 

300

573

. * 65 (E, 0.818). «

0. 8065 

.809 

.810 

.8155 

.817 

.8205 

.8205 

.8255 

.8255

90 

20 

110 

180 

50 

385 

75 

650 

260

1,826

69 (E, 0.819.).

0.804 

- .808 

.8145

.8195 

.824

24 

40 

85

140 

330

589

* 73 (E, 0.8195).

0. 8055 

.811 

.8155

.820 

.824

34 

45 

80

120 

290

569

* 77 (E, 0.8205).

0.806 

.8125 

.8175 

.823 

.8245

32 

45 

90 

100 

330

597

*62 (E, 0.8163).

Specific 

gravity.

0. 8155 

.808 

.8095 

.812 

.8175 

.8182 

.823 

.8255

Cubic 

cent, meters.

42 

50 

70 

25 

105 

32 

250 

41

 615

*66 (E, 0.818).

0.805

.811 

.8135

.819 

.8235

38

38 

104

175 

240

695

70 (E, 0.819).

0. 8115 

.814 

.815

.8165 

.824

21 

31 

90

120 

330

592

74 (E, 0.8195).

0.810 

.8135 

.809 

.814 

.8185 

.824 

.827

40' 

42 

65 

34 

160 

200 

30

031

78 (E, 0.8215).

0. 8045 

. 8135 

.8185 

.823 

.8275

28 

36 

78 

150 

300

592

*63 (E, 0.817).

Specific 

gravity.

0.804 

. 8075 

.8145

.8205 

.8245

Cubic 

centimeters.

45 

50 

102

150 

300

047

67 (E,' 0.818).

0.805

.811 

.8145

.8185 

.824

40

45 

85

125 

325

620

* 71 "(E, 0.819).

0.8095 

.8085 

.814

.820 

.824

23 

34 

SO

160 

280

577

75 (E, 0.8197).

0. 8025 

. 8105 

.816

.822 

.8255

40 

38 

90

150 

300

618

*79 (E, 0.822).

0. 8105 

.8145 

.819 

.8225 

.827

32 

42 

77 

155 

280

586

' Three tubes.

57714 Bull. 365 08 3
18 FBACTIONATION OF CKTJDE PETEOLEUM.

TABLE 4. Secondfractionation Continued.

A....................

B. ...................

c... ...............:.

D..... ...............

,EF..................

A....................

B. ...................

c.. ..................

D. ...................

EF.. ................

A. ...................

B. ...................

C.. ..................

D......!.. ...........

EF..................

A....................

B. ...................

C.. ..................

D. ....... ............

EF. .................

80 (E, 0.822).

Specific 

gravity.

0.817 

.810 

f .8153 

t . 8163 

.8225 

I .8265

Cubic 

centimeters.

30 

40 

46 

42 

160 

295

613

*84 (A-B, 0.80*65).

0. 8035 

.8055 

f .809

.8085 

.811

40 

40 

80

155 

300

615

*88 (C-D-F, 0.813).

0.8035 

.808

.8115 

.813 

.8155

.8195

40 

40

73 

30 

160

290

633

* 92 (D-E, 0.8163). e

0.805 

.8075 

.807 

.8115 

.815 

.816 

.820 

.820 

.8225 

.8225

84 

20 

100 

20 

205 

45 

350 

102 

500 

480

1,906

81 (E, 0.822).

Specific 

gravity.

0. 8083 

.814 

.8185

.824 

.8265

Cubic 

centimeters.

26 

40 

92

140 

270

568

* 85 (A-B, 0.808).

0. 8085 

.807 

.8065

.8085 

.8115

30 

30 

92

115 

330

597

* 89 (C-D-E, 0.813). e

0. 8035 

.807 

.8077

.8125 

.813 

.815 

' . 8175

.8175 

.818

130 

20 

160

' 330 

CO 

550 

90

830 

425

2,595

93 (F, 0.822).

0. 8107 

.810

.814 

.816 

.8215

.8285 

.831

35 

43

70 

25 

156

250 

60

639

82 (E, 0.824).

Specific 

gravity.

0. 8125 

.8127 

.818 

.819 

.8245 

.828 

.830

Cubic 

centimeters.

48 

48 

53 

50 

175 

200 

90 

"50

714

*86(B-C-D, 0.8125).

0.805 

.808 

.813

.815 

.820

32

42 

85

175 

280

614

*90(B-C-D,0.8145).c

0. 8065 

.808 

.809 

.8115 

.813 

.815 

.815 

.8175

.8175 

.818

130 

27 

. 137 

20 

305 

40 

560 

75

775 

410

2,479

94 (F, 0.822).

0.804 

.808

, .8165 

' .817 

.8218

.831

28 

'37

63 

30 

146

255

559

* 83 (A-B, 0.804).

Specific 

gravity.

0.803 

.8035 

.8035

.804 

.806

Cubic 

centimeters.

32 

25 

63

140 

275

535

*87(B-C-D,O.S125).b

0.805 

.8085 

.812 

.813 

.815 

.8175

SO 

73 

118 

75 

285 

520

1,151

* 91 (D-E, 0.815). <J

0.801 

.8025 

.8075 

.8085 

-.812 

.812 

.817 

.817 

.817 

.8215 

etc.

165 

176 

206 

156 

330 

512 

340 

800 

150

| 2, 733

5,568

a Left.

& Two tubes.

c Four tubes. 

dNine tubes.

Three tubes.

To chill and filter these products of two .fractionations would have 

entailed too much loss. As it was, much uniting of samples which 

differed but slightly from one another was necessary to obtain sufficient oil for further fractionation. A list of the unions which were 

made is given in Table 5.
FRACTIONATION IN TUBES. 19 

TABLE 5. Products of two fractionations united for the third fractionation.

Lot.

95.... 

96.... 

97....

98....

99.... 

100... 

101...

103... 

104...

100...

112... 

115...

116... 

120... 

123... 

126...

Specific 

gravity.

0.805 

.807 

.8085

.8085

.8105 

.8115 

. 8125

.8135 

.814

.8145

.8175 

.819

.819 

.820 

.822 

.824

Fractions united.

Grade.

f ' B

c

1 A

I c

1 A

1 A 1 A

f B 

{ A

f A 

\ A

f A 

1 C 1 c

EF 

C

f B 

( B

D 

D

f C

\ c

D 

 EF 

D 

EF 

D

Specific 

gravity.

0. 8033 

.8035 

.8045 

.805

.8058 

. 8065 

.807

.808 

.809

.8072 

.8077

.8105 

.811 

.8105

.8113 

.8123

.8125 

.8135

.8135 

.814

.8165 

.8175

-. 8175 

.8185 

.8195 

.8215 

.823

Cubic 

centimeters.

48 

63 

150 

115

40 

240 

53

767 

20

20

38

70 

115 

270

300 

520

180 

106

370 

500

258 

200

305 

845 

475 

700 

250

Grade.

A 

A 

A

A 

B 

C

C 

C

A 

B

A 

A 

B

EF 

D

B 

C

EF 

C 

D 

D 

EF 

D 

I) 

EF

Specific 

gravity.

0.8035 

.804 

.805

.806 

.8065

.807

.808 

.809

.8075 

.8075

.8115 

.811 

.8115

. 8115

.8125

.813 

.8135

.8135 

.8145 

.817 

.818 

.819 

.820 

.8218 

.8235

Cubic centimeters.

240 

65 

360

235 

100 

75

80 

210

290 

480

21 

40 

308

920

1,220

160

45 

925

715

1,085

910

1,410

425 

990

1,295

683

1,528

COO

1,075

460 

800

Grade.

B 

D 

B

EF 

D 

C

A

A

D

B 

C

EF 

C

D

EF 

D

Specflc 

gravity.

0. 8035 

.804 

.805

.806 

.8003 

.8065

.8083 

.8085

.8075

.811 

.8115

.8125 

.8132

.8172

.822 

.824

Cubic centimeters.

25 

140 

95

1,251

275 

180 

92

1,290

26 

118

1,221

270

1,098

580 

73

1,477

820

1,500

60

1,316

75

958

300

1, 460

KO

1,250

No uniting was necessary for lots 102, 105, 107-111, 113, 114, 

117-119, 121, 122, 124, 125, and 127. In the third fractionation, 950 

cubic centimeters of each of these lots was filtered through earth 

again, with the results shown in Table 6.
20 FRACTIONATIOlsr OF CRUDE PETROLEUM. 

TABLE 6. Third fractionation.

A....................

B. ...................

C. ...................

D. ...................

EF..................

A....................

B. ...................

C....................

D. ...................

EF..................

A....................

B. ...................

C.. ..................

D....................

EF..................

A....................

B. ...................

C.. ..................

D....................

EF. .................

A....................

B. ...................

c.....................

D....... .............

EF..................

A....................

B. ...................

C.... ................

D... .................

EF. .................

95 (A-D, 0.805).

Specific 

gravity.

0. 8065 

.805 

f .804 

\ .805 

.8055 

.808

Cubic centimeters.

33 

33 

62 

40 

150 

315

633

99 (A-C, 0.8105).

0. 8105 

.810 

f .8075 

\ .8085 

.811 

.814

33 

36 

71 

17 

115 

300

572

103 (B-C, 0.8135).

0. 8065 

.810 

f .8135 

\ .8165 

.815 

.817

28 

33 

60 

18 

150 

325

614

107 (D, 0.815).

0. 8035 

. 8115 

f .815 

\ . 8177 

.8175 

.8195

45 

47 

85 

30 

156

300

 663

111 (EF, 0.817).

0. 8043 

.8105 

f . 8152 

\ . 816 

.8182 

.8205

30 

32 

65 

43 

160 

290

620

115 (D, 0.819).

0. 8055 

.807 

f .816 

\ .817 

.820 

. 8225

16 

Lost. 

43 

30 

130 

300

96 (A-EF, 0.807).

Specific 

gravity.

0.8045 

.806 

.8065 

.8083 

.808 

.8095

Cubic centimeters.

37 

38 

65 

25 

142 

250

557

100 (EF, 0.8115).

0.8065 

.809 

.810 

.812 

.812 

.815

30 

36 

60 

20 

! 136 

315

597

104 (D-EF, 0.814).

0.8042 

.8115 

.8125 

.8147 

.815 

.819

35 

36 

60 

28 

175 

230

564

108 (EF, 0.8155).

0.809 

.811 

.815 

.815 

.8165

.8185

52 

47 

55 

40 

170 

255

619

112 (C-D, 0.8175).

0. 8145 

.811 

.8165 

.818 

.819 

.822

35 

32 

60 

30 

150 

245

552

116 (EF, 0.819).

0. 8032 

.8115 

.816 

.820 

.8205 

.8235

30 

36 

52 

21 

160 

240

539

97 (A-C, 0.8085).

Specific 

gravity.

0.806 

.8008 

.807 

.8095 

.8093 

.812

Cubic centimeters.

40 

40 

58 

18 

154 

295

605

101 (C-EF, 0.8125).

0.808 

.8085 

.811 

.8145 

.8145 

.817

33 

34 

54 

22 

162 

295

600

105 (C, 0.814) .

0.804 

.810 

.8142 

.816 

.8163 

.8185

40 

40 

58 

25 

270 

280

713

109 (D, 0.8163).

0.810 

.8105 

.8132 

.8145 

.8185 

.8215

33 

45 

55 

33 

140 

275

531

113 (EF, 0.8175).

0.8065 

.812 

.8155 

.8175 

.8185 

.8225

35 

48 

75 

18 

150 

283

609

117 (D, 0.819).

0. 8045 

.813 

.8175 

.8175 

:8215 

.8235

33 

38 

60 

34 

150 

325

640

98 (A-D, 0.8085).

Specific 

gravity.

' 0. 8047 

.8052 

.808 

.8093 

.8095 

.811

«

Cubic centimeters.

38 

38 

70 

30 

132 

335

043

102 (C, 0.813).

0.806 

.8105 

.8105 

.813 

.813 

.8157

26 

33 

50 

. 17 

136 

365

627

106 (C-D, 0.8145).

0.803 

.810 

. 8145 

.816 .816' 

.8185

33 

40 

54 

22 

150 

260

559

110 (JJ, 0.817).

0.8065 

. 8125 

.817 

.818 

.8195 

.821

35 

40 

68 

30 

145 

290

608

114 (EF, 0.8187).

0.817 

.8065 

.8122 

.813 

.8175 

.822

30 

25 

30 

15 

150 

340

590

118 (EF, 0.819).

0.805 

.813 

.8165

.821 

.8243

30 

30 

60 

10 

154 

295

579
FRACTIONATION IN TUBES. 

TABLE 6. Third fractionation Continued.

A....................

B. ...................

C... .................

D....................

EF... ...............

119 (EF, 0.8195).

Specific 

gravity.

0.805 

.814 

f .81C5 

1 . 8175 

.8205 

.823

Cubic centimeters.

23 

35 

58 

32 

' 152 

300

000

120 (D, 0.820) .

Specific 

gravity.

0.805 

.811 

.817 

.8175 

.822 

.825

Cubic centimeters.

33 

35 

53 

35 

1G5 

310

C33

121 (EF, 0.821).

Specific 

gravity.

0.8075 

.814 

.8182 

.819 

.822 

.8245

Cubic centimeters.

33 

41 

03 

18 

150 

273

578

122 (EF, 0.8215) .

Specific 

gravity.

0.803 

.811 

.8105 

.818 

.8225 

.828

Cubic centimeters.

41 

43 

CO 

23 

182 

270

C29

-

A.........

B. ........

C. ........

D.. .......

EF.......

123 (D-EF, 0.822).

Specific 

gravity.

0.808 

.813 

f . 8178 

1 . 8192 

' . 8233 

.8265

Cubic centimeters.

34 

35 

52 

42 

155 

260

578

124 (EF, 0.8225).

Specific 

gravity.

0.807 

.8095 

. 8175 

.8185 

.8232 

.8275

Cubic centimeters.

31 

27 

65 

17 

150 

300

590

125 (EF, 0.8235).

Specific 

gravity.

0.804 

.813 

.8185 

. 8195 

. 8252 

.829

Cubic centimeters.

35 

40 

70 

21 

144 

280

590

126 (D-EF, 0.824).

Specific 

gravity.

0.805 

,814 

.820 

.821 

.8253 

.828

Cubic centimeters.

35 

35 

60 

20 

170 

300

620

127 (EF, 0.8255).

Specific 

gravity.

0. 8055 

.8155 

.821 

.823 

. 8275 

.830

Cubic centimeters.

45 

40 

75 

25 

170 

280

035

Sufficient oil of five grades for the fourth fractionation was obtained 

by uniting fractions from the third, as shown in Table 7.

TABLE 7. Products of three fractionations united for the fourth fractionation.

Lot.

128....................

129....................

130....................

131....................

132....................

Specific 

gravity.

0.815

.8163 

.819

.8205 

.823

Fractions united.

Lot.

99 

101 

103 

104 

106 

108 

109

f 101 

{ 102 

I 103

I 104 

\ 105 

| 106

f 107 

1 110 

111 

[ 119

f 113 

\ 115 

I 119

Grade.

EF 

C 

D 

D 

C 

C 

C

EF 

EF 

EF

EF 

EF 

EF

EF 

D 

EF 

EF

EF 

EF 

EF

Specific 

gravity.

0.814 

.8145 

.815 

.815 

.8145 

.815 

.8145

.817 

.8157 

.817

.819 

.8185 

.8185

.8195 

.8195 

.8205 

.8205

.8225 

.8225 

.823

Cubic, centimeters.

300 

22 

150 

175 

54 

55 

33

295 

365 

325

230 

280 

260

300 

145 

290 

152

283 

300 

300

Lot.

100 

101 

104 

105 

107 

108 

111

105 

106 

108

108 

113 

109

115 

116 

118

120 

121 

122

Grade.

EF 

D 

C 

C 

C 

C 

C

D 

D 

D

EF 

D 

D

D 

D 

D

D 

D 

D

Specific 

gravity.

0.815 

.8145 

.8147 

.8142 

.815 

.815 

.8152

.8163 

.816 

.8165

.8185 

.8185 

.8185

.820 

.8205 

.821

.822 

.822 

.8225

Cubic centimeters.

315 

162 

28 

58 

85 

40 

65

1,542

270 

150 

170

1,575

255 

150 

140

1, 315

130 

160 

154

1,467

165 

150 

182

1,380
22 FRACTIONATIOISr OF CRUDE PETROLEUM.

The results of the fourth fractionation are stated in. Table 8. 

TABLE 8. Fourth fractionation.

A.........

B. ........

C. ........

D.........

EF.......

228 

(C-EF, 0.815).

Specific 

gravity.

0.8135 

.815 

f . 8118 

1 .813 

.8147 

.8175

Cubic 

centimeters.

19 

27 

50 

15 

140 

360

611

129 

(D-EF, 0.8168).

Specific 

gravity.

0.812 

.8122 

.8165 

.818 

.818 

.8195

Cubic 

centimeters.

30 

42 

55 

25 

160 

305

617

130 

(D-EF, 0.819).

Specific 

gravity.

0. 8115 

.8127 

.8173 

.8185 

.820 

.8215

Cubic centimeters.

24 

35 

60 

22 

160 

310

611

131 

(D-EF, 0.8205).

Specific 

gravity.

0. 8095 

.813 

.819 

.8195 

.8215 

.824

Cubic 

centimeters.

18 

26 

45 

17 

130 

340

576

132 

(D-EF, 0.823).

Specific 

gravity.

0. 8092 

Lost. 

.8195 

.8213 

.8235 

.826

Cubic centimeters.

35 

35 

60 

25 

150 

280

585

To better compare the oils of different specific gravities that were 

obtained by the process just described each of six 300 cubic centimeter samples (five of partly refined oil and one of crude petroleum) 

was separated by distillation into ten fractions. Each sample was 

distilled in the same 500 cubic centimeter distilling bulb, which was 

heated by an electric stove that entirely surrounded it. The oil was 

first heated to 200° under atmospheric pressure and then to 360° 

under a pressure of 50 millimeters. The diminished pressure was 

obtained with a large Chapman water pump and kept constant by 

the use of a valve which automatically admitted air to the evacuated 

system whenever the pressure fell below 50 millimeters. This valve 

was constructed from a piece of iron pipe 1 inch in diameter and 5 

feet long. The lower end was closed with a cap and the pipe filled 

with mercury to a depth of 76 centimeters. The upper end of the 

pipe was closed with a two-hole rubber stopper. In one hole was a 

long glass tube with the lower end beveled, which reached to the

bottom of the mercury and could be raised or lowered as the barometer varied from day to day. In the other hole was a tube which 

passed just through the stopper and was connected on the outside 

with the apparatus to be exhausted. To prevent mercury from 

being drawn up and over into the apparatus by the air admitted, the 

end of the tube inside the stopper was drawn out and bent at a right 

angle and over this was slipped a cap made of larger tubing closed at 

the bottom, but having a fine opening in the side for air. This cap was 

about 6 centimeters long and extended about 3 centimeters below 

the end of the tube inside. If any mercury passed through this first 

fine opening into the cap, it would fall to the bottom without being 

drawn over into the apparatus or clogging the fine opening in the 

tube leading thereto. With this valve there was no difficulty in 

keeping a pressure of 50 millimeters constant within 1 millimeter.
FBACTIONATION IK TUBES.

Each distillate of sufficient volume, which was not too viscous or 

partly solid, was tested as to specific gravity, viscosity, and percentage 

absorbed when treated with concentrated sulphuric acid (specific 

gravity 1.84).

TABLE 9. Fractionation of six samples by distillation.

Tubes passed thi 

Normal pressure

Below 150°..

150°-200°. . . . 

50 nun. pressure 

Below 140°..

140°-200° 

200°-230°....

230°-2(iO°....

200°-300°....

300°-340°. . . . 

340°-3GO°.... 

Residue.....

Total volu

Viscosity. ...........................

Acid treatmentlgpeclflc gravity. ....

Arid trpfttniPnr/Per cent absorbed. . AGIO. ireai.inen^gpecific gravity

Specific gravity. ....................

Viscosity. ...........................

Acid treatment|Speciflc grftvity

Arid treatmpnt/Pcr cent absorbed.. Acia "eatment|gpeciflc gravity

Viscosity. ...........................

Arid trpfltmpnr/Per cent absorbed.. Acid treatment|Speciflc gravity

Specific gravity. ....................

Ar>iri trr>ntTnor1 fJ Per cent absorbed. . Acid treatment|Speciflc gravity ....

Specific gravity. ....................

1.

0.801 

0.0404 

1

36 

0.720

0.0052 

4.4

0.722

47 

0.749 

0.0075 

3.4 

0.749

10

69 

0.790 

0. 0212 

3.4 

0.790 

25 

0.813 

0.0556

0.813 

23 

0.8255 

0. 1106 

3 4 

0. 8255 

20 

0.8395 

0.2520

25 

0.847 

21 

Fluid. 

22 

Fluid.

298

2.

0.808 

0.0555 

3

1

61 

0.7465 

0.0073 

4.4 

0. 7469

9

75 

0.790 

0.0185 

4.4 

0.7885 

30 

0. 8135 

0.0594 

4.3 

0.8125 

27 

0.826 

0.1150 

8.5 

0.8255 

22 

0.838

o30 

0.849 

a 26 

Fluid. 

17 

Fluid.

298

3.

0.815 

0.0589 

3

13 

0.737

0.0059

0. 7365

52 

0.756 

0.0075 

8.2 

0.750

3

80 

0.797 

0.0211 

8.9 

0.7915 

23 

0.818 

0.0573 

11.0 

0.816 

23 

0.830 

0.1116 

7.0 

0.828 

23 

Fluid.

27 

Solid. 

22 

Fluid. 

30 

Fluid.

296

4.

0 8195

4 

5

. 60 

0.757 

0.0073 

11.3 

0.749

6

80 

0.800 

0. 0216 

- 9.0 

0.795 

25 

0.8225 

0.0661 

 8.4 

0.8217 

20 

0.833 

0. 1168 

8.8 

0.832 

24 

Fluid.

30 

Solid.

45 

Fluid.

295

5.

0.824 

0.0657 

4

2

60 

0.759 

0.0072 

12.0 

0.750

10

73 

0.8015 

0.0196 

14.8 

0. 7915 

30 

0.822 

0.0505 

10.5 

0.818 

24 

0.838 

0. 1259 

7.6 

0.833 

20 

Fluid.

26 

Solid. 

19 

Fluid. 

35 

Fluid.

299

0.

0.810 

0.0441 

Crude 

oil.

45 

0.714 

0.0047 

8.6 

0.712 

43 

0.759 

0.0076 

9.3 

0.752

19 

0.7805 

0.0112 

11.9 

0.7735 

48 

0.804 

0. 0254 

11.0 

0.799 

21 

0.823 

0. 0593 

8.7 

0.8175 

22 

0.8355 

0. 1284 

12.6 

0.830 

17 

Fluid.

25 

Solid. 

20 

Fluid. 

32 

Fluid.

292

Viscosity was measured by taking the time of flow of a measured 

volume of oil through a capillary, the viscometer used being the one 

described by Ostwald and Luther as modified by Jones and Veazey. a 

The capacity of the small bulb was 4.5 cubic centimeters and the diameter of the capillary such as to require from five to eight minutes for 

that amount of oil to flow through it, and 1 minute 2.6 seconds for the 

same amount of water. The viscosity as well as the specific gravity 

was always measured at a temperature of 20° C. Viscosities have

TS been calculated from the formula rj = rj 0 TTTQ in which rj 0 is the coeft Zeitschr. physikal. Chemie, vol. 61, p. 651.
24 FRACTIONATION OF CRUDE PETROLEUM.

70

60

50

40

30

20

70

60

50

40

30

20

10

(1)

ficient of viscosity for water, S0 is the specific gravity of water, and 

To the time of flow of water through any given capillary at a given 

temperature; rj is the viscosity coefficient of the solution investigated, S is its specific gravity as compared with water as unity at

any given temperature, and 

T is the time of flow of the 

given solution at that temperature. The value for 

pure water at 20° was taken 

from the work of Thorpe 

and Rodger. a

Thirty cubic centimeters 

of each of these distillates 

where that much oil was 

available, or all the oil 

there was where the volume was less than 30 cubic 

centimeters was mixed with 

an equal volume of concentrated sulphuric acid (specific gravity 1.84) and 

shaken for half an hour or 

longer in a shaking machine. The oil and acid 

were then poured into a 

separating funnel and the 

acid drawn off. The oil 

was then washed twice with 

water, once with aqueous 

NaOH, again with water,

and then with this last 

wash water poured into a 

burette and allowed to settle. After standing overnight the volume was read. 

The oils boiling below 200° 

(at 50 millimeters pressure) 

separated clear, but the 

heavy distillates were milky 

from water. The volume 

of these milky oils was read, their specific gravity was taken, and 

then the milkiness was removed by shaking and heating to about 

60° with CaCl2 . The specific gravity of the clear oil was then taken 

and the proper correction made to the milky volume. In no case,

aPhil. Trans., vol. 185A, 1894, p. 397.

(2)

f

,0° 150° 200! J40° 200° 230° 260° 

Normal pressure 50 mm. pressure 

TEM'PERATURE

FIG. 1. Curves showing proportion of hydrocarbons soluble in sulphuric acid, oils 1 and 2.
FRACTIONATION IN TUBES. 25

60

50

40

30

20

(3)

however, was this correction large, and only for the three or four 

heaviest oils did it exceed one-half of 1 per cent, the largest correction of all being 2.6 per cent for the distillate between 230° and 260° 

of the oil of specific gravity 0.824. An attempt to treat with acid 

the oils selected to be distilled resulted in so much 70 

loss from the formation of 

emulsions that the loss in 

volume and change in specific gravity could not be 

determined with any degree 

of accuracy.-

The results of the distillation of these samples are

summarized in Table 9.

"Fluid" means that the 

oil at 20° was partly solid, 

but would flow when the 

bottle was inclined; "solid" 

means that the oil would 

not change its shape when 

the bottle was turned upside 

down.

It was hoped that sulphuric acid of the strength used 

would dissolve only unsaturated hydrocarbons and 

leave untouched the paraffins and benzene. By longcontinued shaking at ordinary temper atures, ho wever, 

with acid of this strength 

benzene is dissolved, provided that the acid is in large 

excess. On being shaken for 

four hours 100 cubic centimeters of benzene was completely dissolved in 434 cuf. ,. , j. . i FIG. 2. Curves showing proportion of hydrocarbons sol- bic centimeters ot acid. uble in sulphuric acidj olls 3 ftnd 4 .

Three of the distillates

which had been shaken with acid showed no action when treated with 

a mixture of equal parts of concentrated sulphuric acid and fuming 

nitric acid, whereas this nitrating mixture did act on distillates which 

had not been previously shaken with sulphuric acid. The action of 

the sulphuric acid, therefore, appears to have been complete.

70

60

50

40

30

20

10

(4)

150° 200° 140° 200° 230° 260°

Normal pressure 50 mm. pressure 

TEMPERATURE
26 FRACTIONATION OF CRUDE PETROLEUM.

70

60

50

40

30

20

70

60

50

40

30

20

10

(5)

The results of the acid treatment showed that over 90 per cent of the 

oil used consisted of paraffin hydrocarbons, and that in the filtration 

through earth the paraffin hydrocarbons tended to collect at the top 

of the tube and the unsaturated hydrocarbons at the bottom.

The increasing amount 

dissolved by sulphuric acid 

in the heavier oils may be 

seen in the curves shown 

in figs.l to 3. The abscissas represent temperatures 

and the ordinates volumes. 

The same distance on the 

x axis is taken to represent 

a distillate, whatever be 

the number of degrees over 

which it may have been collected. The upper curve 

represents the percentage 

of the total volume that 

distilled between given 

temperatures; the lower 

curve the percentage of 

the total volume recovered 

that was not absorbed by 

sulphuric acid (that is, the 

paraffin hydrocarbons). 

For the upper curve the 

ordinates are obtained by 

dividing the number of 

cubic centimeters in the 

distillate-by the total volume of oil recovered. For 

the lower curve the ordinates are obtained by 

dividing the number of 

cubic centimeters in the 

distillate not absorbed by

FIG. 3.-Curves showing proportion of hydrocarbons solu- sulphuric acid by the total 

Die in sulphuric acid, oils 5 and 6. L *

volume of oil recovered.

The area between the two curves represents the proportion of hydrocarbons soluble in sulphuric acid. It Will be seen that this is greatest 

for the oils of highest specific gravity.

Tables 4 and 6 show that in several tubes the specific gravity of the 

oil of grade A was greater than that of the grade B oil and in some

A

(6)

150 200° ,140° 200° 230° 260°

Normal pressure 50 mm. pressure 

TEMPERATURE
FRACTIONATION IN TUBES. 27

tubes than that of the grade C oil. This irregularity was marked in 

tubes 48, 62, 68, 72, 74, and 80 of Table 4 and 112 and 114 of Table 6. 

A slight irregularity appears in tubes 20, 21, 24, 27, 40, 71, and 85 of 

Table 4 and tube 99 of Table 6. Of the oils in these tubes that were 

not colorless the color was strongest where the specific gravity was 

greatest, so that although the oil of grade A had passed through 

the most earth it was yet more strongly colored than that of grade B 

or C.

No reason for this variation has been established. It should be 

remembered, however, that the different oils rise in the earth with 

differing velocities, not because they differ from one another in specific gravity, but because they differ in surface tension. A rough 

attempt was made to determine relative surface tensions by measuring the height to which different oils rise in the same capillary tube, 

but although a kathetometer was used and the level of the oil in the 

capillary brought to the same spot each time the work sufficed only 

to show that the difference in the surface tension of the oils was so 

slight as to require very careful measurement to obtain results of any 

value.

That the viscosity shows the same irregularity in these oils as color 

and specific gravity appears from the following measurements:

TABLE 10. Specific gravity and viscosity of fractions from tubes 62 and 68.

A..............................................................

B..............................................................

C..............................................................

D................................................... ...........

E F............ ...............................................

6

Specific 

gravity.

0.8155

.808

i .8095

1 .812 

\ .8175

[ . O1O4

.823

2.

Viscosity.

0.0539

.0469

.0509

.0555 

.0525

.0535

6!

Specific 

gravity.

0.8205

.8043

.810

.812 

.817

. 8225

3.

Viscosity.

0.0626

.0469

.0520

.0554 

.0524

Tube 50 (Table 4) showed an irregularity in grade B, which is also 

found in the viscosity:

TABLE 11. Specific gravity and viscosity of fractions from tube 50.

A............................................ . ....................................

B...................................................................................

C...................................................................................

T>...................................................................................

EF....... ..........................................................................

Specific 

gravity.

0.8105

.8148

.810

.815

.819

Viscosity.

0.0532

. 0559

.0526

.0526

.0552

The oils obtained by one fractionation. of the crude petroleum (see 

Table 1) had the following viscosities;
28 FRACTIONATION OF CRUDE PETROLEUM.

TABLE 12. Specific gravity and viscosity of fractions from tubes 1 to 3.

A.........................................

B.. ......................................

C.. .......................................

D.......... ...............................

E. ........................................

F. ........................................

1

Specific 

gravity.

0.796

.808

f . 8125

\ .8137 

.815

.818

.8205

Viscosity.

0.0376

.0529

.0501

.0529 

.0504

.0521

2

Specific 

gravity.

0.8012

.804

.807

.809 

.8125

.8185

.823

Viscosity.

0.0408

.0485

.0443

.0476 

.0460

'. 0537

Specific 

gravity.

0. 8022

.803

.8075

.810 

.812 '

.8175

.821

).

Viscosity.

0. 0401

.0470

.0453

.0471 

.0472

.0529

That the viscosity does not increase with the specific gravity, particularly in the higher fractions, is apparent in two of the three series 

just given. The. same is also shown in four tubes whose records are 

given in Table 4.

TABLE 13. Specific gravity and viscosity of fractions from tubes 21, 22, 47, and 53.

A....................

B. ...................

C. .......... ........

D... .................

EF.. ................

21

Specific 

gravity.

0.8038

.8035

1 . 8035

{ .8052 

.805

.807

Viscosity.

0. 0465

.0456

.0456

.0485 

0479

r>4Sn

y.

Specific 

gravity.

0. 7997

.802

.8055

.8063

.808

Viscosity.

0.0421

.0485

.0502

.0496

.0510

4'

Specific 

gravity.

0.800

.807

.814

.816

819

Viscosity.

0. 0453

.0538

.0542

.'0528

.0556

K

Specific 

gravity.

0.803

.8105

.815

.8185

.820

.

Viscosity.

0. 0515

.0563

.0684

.0570

.0559

This drop in viscosity which occurs at the bottom of the tube 

appears to be a regular occurrence in the dozen or so oils which 

have been tested. Further investigation of this point is intended.

WATER FRACTIONATION.

To test the effectiveness of water fractionation alone, 1,000 cubic 

centimeters of crude petroleum, previously chilled and filtered, of 

specific gravity 0.807, was mixed with 1,000 grams of earth and 

allowed to stand for twenty-four hours. Water was then added in 

small amounts and the oil collected. The results are stated below.

TABLE 14. Fractionation of crude petroleum with ivater.

A................................................... .....................

B........ ................................................................

C.... ......................................................................

D..... ...................................................................

E........................................................................

F........................................................................

Specific 

gravity.

0.8148

.8139

.816

.820

.8225

.8245

Cubic centimeters.

44

278

211

84

28

28

673

Total 

water 

present 

(cubic centimeters).

500

650

800

950

1,400

2,750
WATER FRACTIONATION. 29

The fractions of large enough volume were then mixed with earth 

again and the oil replaced with water. One gram of earth was used 

for each cubic centimeter of oil, the earth having been heated and 

allowed to cool. Table 15 shows the results.

TABLE 15. Second fractionation of petroleum with water.

Specific 

gravity.. 

Cubic centimeters. 

Time (hrs.)

1..........

2....... ..

3..........

4..........

5..........

0... .......

7..........

8..........

9..........

Specific 

gravity.

0.8185

.818

.818

.818

.817

.819

.820

.820

.8215

B.

0.8139

278 

1.5

Cubic centimeters.

10

10

21

20

42

10

44

16

20

193

Water 

(cubic centimeters).

70

110

164

216

277

428

686

Specific 

gravity.

0.820

.820

.8195

.820

.820

C.

0.816

211 

6

Cubic . centimeters.

10

20

72

30

10

142

Water 

(cubic centimeters) .

80

125

250

410

588

Specific 

gravity.

0.822

.823

D.

0.820

84 

2.5

Cubic centimeters.

32

90

52

.

Water 

(cubic centimeters) .

76

207

It is apparent that while petroleum is fractionated by simply mixing 

the oil with fuller's earth and then displacing the oil from the earth 

with water, the fractionation is much more complete when tubes are 

used, as previously described.

It will be noticed that although fractions C and D of Table 14 are 

separated hardly, at all by further treatment with earth and water 

(Table 15), yet the specific gravity of all the oil recovered is higher 

than that of the oil used; for example, fraction C (specific gravity 

0.816) yields nothing lighter than 0.8195, and D (specific gravity 

0.820) nothing lighter than 0.822.

To determine whether the specific gravity of the oil recovered will 

continue to rise after the oil is fractionated no further by repeated 

treatment, 330 cubic centimeters of specific gravity 0.819,obtained by 

uniting several products of one fractionation of the-crude petroleum, 

were mixed with 330 grams of earth, and water was added, as shown in 

Table 16.

TABLE 16. Second fractionation of petroleum (combined sample) with Ulster.

A ........................................................................

B ........................................................................

C.. ....................................................................... D... ............................:......................................... E ................................................... °....................

F.........................................................................

Specific 

gravity.

' 0.8215

.821

.821

.8225

Cubic centimeters.

6

50

12

60

82

26

236

Total 

water 

present 

(cubic centimeters) .

64

214

270

413

613
30 FKACTIONATION OF CRUDE PETROLEUM.

When 75 cubic centimeters of fraction E (specific gravity 0.821) 

was next mixed with 75 grams of earth and 150 cubic centimeters of 

water was added, 51 cubic centimeters of oil whose specific gravity 

was unchanged, but whose color was reduced, was obtained. Fifty 

cubic centimeters of this oil when treated with earth and water, 

returned 34 cubic centimeters of oil with the color considerably 

lighter, but with the specific gravity still 0.821.

Although only two-thirds of the oil used is recovered when oil is 

mixed with earth and then displaced with water, yet this loss does not 

seem to affect the specific gravity of the oil obtained except in the 

first one or two treatments after the oil ceases to be fractionated. 

After these first treatments the oil recovered has the same specific 

gravity as the oil used.

OIL LOST IN THE FULLER'S EARTH.

The sum of the fractions of oil displaced from the earth is as a rule 

only about two-thirds of .the volume of the oil used. A pressure of 

approximately 200 tons per square inch on the earth from which 

water has displaced all oil that it will results in the liberation of considerable water but very little oil. When earth which has been 

pressed is heated to 165° for three hours, considerable water distills 

over, but much less oil than would be expected; for example, from 75 

grams of earth which should contain 25 cubic centimeters of oil only 

4 cubic centimeters of oil was obtained. The earth was removed 

once from the flask and pulverized, and when the heat was discontinued the earth was thoroughly dry. On extraction with ether in a 

Soxlet extractor the earth gave a solution having the color of the 

original petroleum. The extraction was continued until the extract 

was colorless. On evaporation of the ether there remained about 8 

cubic centimeters of a heavy oil with the color of the natural petroleum. 

Pressure, heat, and extraction with ether together gave about half the 

amount of oil which the earth must have contained.

Earth that had been used once was allowed to dry for several weeks 

at room temperature until it had lost all appearance of containing 

moisture. It was then pulverized, sifted, and 720 grams used in a 

tube with 740 cubic centimeters of the crude petroleum of specific 

gravity 0.810, with the following results:

TABLE 17. Fractionation of crude petroleum with earth that had been used once.

Specific 

gravity.

0.8284

.8225

f .8143

i .8155 

/ .8175

t .819

Cubic 

centimeters.

0

10

45

60

80 

83

114

392
OIL LOST IN FULLER'S EARTH. 31

The first oil up the tube is evidently absorbed by heavy material in 

the earth; the first oil recovered dissolves material from the earth, 

which increases its specific gravity beyond that of the next fraction.

To see how much of the weight of the earth used the second time 

was due to material which it had retained from its first use, 300 grams 

of earth was mixed with 300 cubic centimeters of crude petroleum and 

the oil displaced by water. The oil recovered measured 205 cubic 

centimeters, and the weight of the earth after drying for several weeks 

at room, temperatures was 347.5 grams. Fully 15 per cent, therefore, 

of the weight of the earth used the second time was solid matter 

which it had retained from its first use.

In all tests the earth was heated before it was used because it was 

believed that heating decreased the amount of oil lost in the earth. 

The earth was heated usually in iron pans on a gas stove until it 

ceased to form geysers when stirred. A tube 5 feet long and 1 \ inches 

in diameter, packed with 948 grams of earth that had not been heated, 

gave results as follows with 930 cubic centimeters of crude petroleum 

of specific gravity 0.810, after standing for twenty hours at diminished pressure:

TABLE 18. Fractionation of crude petroleum with earth that had not been heated.

Rest ................................................................................

Specific 

gravity.

.8045

.8103

Cubic centimeters.

30

38si

440

.r)93

In a test of water fractionation alone with unheated earth but 242 

cubic centimeters of oil was recovered from 500 cubic centimeters of 

crude -petroleum. .

The results obtained toward the close of our work indicate that the 

loss of oil when unheated earth is used is much less than we had supposed it to be. The gain from heating the earth may not pay for the 

trouble of heating it, and this point should be investigated before 

any very extensive experiments are again undertaken.

Earth after heating must become thoroughly cold before it is used 

to pack tubes. The earth holds its heat for several hours, and if it is 

used the same day on which it is heated, there is apt to be sufficient 

contraction in the tube to allow the oil to run up the side as it would 

in a vacuum.

The length of the tubes used was 5£ feet. A tube 9 feet long was 

connected to the same vacuum pump with several 5|-foot tubes and 

held for two days with a constant diminished pressure of about 10 

centimeters Hg. The oil was drawn to the top of the shorter tubes; 

these were removed and a second lot substituted, and these also were
32 FRACTIONATION OF CRUDE PETROLEUM.

fully impregnated with oil before the long tube was opened. When 

it was opened the oil had ascended but 45 centimeters, showing that 

the diminished pressure had not penetrated the 9 feet of earth and 

reached the bottom of the tube.

A shorter tube in which the earth was packed very much harder, 

so that it rang like an iron rod when pounded on the floor, was connected with a vacuum pump at one end and a manometer at the other, 

and showed diminished pressure on the manometer when the. column 

of earth was 2 feet long but not when it was 2 feet 4 inches.

FRACTIONATING POWER OF SUBSTANCES OTHER THAN FULLER'S EARTH.

A clay from Topsham, Me., showed in tubes a power of fractionating 

as well as of decolorizing the higher fractions. Tubes 5 feet long and 

1£ niches in diameter were used, with petroleum of specific gravity 

0.806. Compared with fuller's earth, the action was as follows:

TABLE. 19. Fractionation of crude petroleum with clay from Topsham, Me., and ivith

fuller's earth.'

.................................. do....

..................................do....

..................................do....

..................................do....

..................................do....

n Fuller's 

uay- earth.

0. 799 0. 793

. 804 . 800

. 810 . 806 .

. 810 . 807

. 812 . 8092

. 812 . 8112

69 76

Neither powdered brick made from the same clay nor powdered 

feldspar showed any power of fractionation.

Another similar clay (from Mere Point, Brunswick, Me.) showed a

power of water fractionation, but its behavior in a tube was not 

tested. Four hundred grams of this clay, previously sifted^ and 

heated, was mixed with 170 cubic centimeters of crude petroleum of 

specific gravity 0.806 and allowed to stand for fourteen hours. Water 

was then added and the'following fractions were obtained:

TABLE 20. Fractionation of crude petroleum with day from Brunswick, Me.

A........................................................................

B.............................................................. ..........

C........... :........ ....................................................

D.......................... ..............................................

Specific 

gravity.

0.8165

.817

.8188

Cubic centimeters.

24

CO

20

6

110

Total

water

present 

(cubic

centimeters) .

104

133

234

374

The color was scarcely changed at all.
FRACTION"ATION OF CRUDE PETROLEUM. 33 

SUMMARY.

1. When petroleum is allowed to rise in a tube packed with fuller's 

earth, there is a decided fractionation of the oil, the fraction at the 

top of the tube being of lower specific gravity than that at the bottom.

2. When water is added to fuller's earth which contains petroleum, 

the oil which is displaced first differs in specific gravity from that 

which is displaced afterward, when more water is added.

3. When petroleum is allowed to rise in a tube packed with fuller's 

earth, the paraffin hydrocarbons tend to collect in the lightest fraction 

at the top of the tube and the unsaturatecl hydrocarbons at the 

bottom.

4. When oil is mixed with .fuller's earth and then displaced with 

water, about one-third of the oil remains in the earth.

O