V o l . 31.
J anuary
N o. 2 ^ .
1945.
CLASSIFICATION OF CRUDE OILS.
B y K . G.
'
M a r g o so h es
(Member).
I n t r o d u c t io n .
a tte m p ts to classify crude oils are recorded in the literatu re,16
b u t only th e m ore recent developm ents will be described in this review.
The accuracy and completeness of th e classifications depend on our
knowledge of th e individual com pounds or groups of compounds in th e
petroleum and on th e accuracy of m ethods to detect and determ ine them .
Some references have been selected to show th e progress m ade during
recent years.
As to th e determ ination of groups of compounds, besides referring the
reader to th e m ethods of various Standardization Committees, a few
references m ay be quoted.1
F o r th e purpose of identification of th e compounds them selves th e crude
oils have first to be separated into fractions. A system 10 for th is fractiona­
tion, which m akes use of distillation, extraction, crystallization, and
adsorption, has been chiefly developed b y A .P .I. R esearch P roject 6.
Of th e m any physico-chemical properties of th e compounds, especially
in th e petroleum fractions, electrom agnetic spectra 12' 13, 14' 15 are very
helpful in throw ing light on th e question.
In connection w ith nam es of compounds 8 present in petroleum and its
products, a tten tio n is directed to a review by T rusty,9 and also to
some 2 3- 4' 5- 6' 7 of th e m any research papers of th e above-m entioned
A .P .I. Research P roject 6.
Several
H
is t o r ic a l
R
e v ie w
.
The earlier classifications consider geological d istribution,16“’ *> chemical
composition 1
or physical properties (e.g., optical activ ity ,16*
solubility W i).
R
ecent
Cl a s s i f i c a t i o n s .
(A) U.S. Bureau of Mines Classifications.— Methods to Evaluate the
“
Baser
The B ureau of Mines of th e U nited S tates has published reports on
crude oils classifications, which distinguish various “ bases.”
In 1927, N . A. C. S m ith 17 differentiated four “ base ’’-groups (see
Table I . 18) and in a Bulletin published later 19 the usefulness of this system
is also tested.
W ith th e progress of th e science of petroleum it was found th a t th e
num ber of groups was no t sufficient: three of th e four classes were retained
and four interm ediate groups were added 20 (see Table II.). The last two
classes are possible according to this classification, b u t no examples of
either of them have been found among th e m any hundred samples analysed
b y th e B ureau of Mines (at least until 1939).21 I t m ay be m entioned th a t
according to Lane and G arton,22 about 85 per cent, of 800 analysed crude
2
M ARG O SCH ES:
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M A R G O SC H E S :
C L A S S IF IC A T IO N O F C R U D E O IL S .
3
oils from th e producing fields throughout th e world fell definitely in one
of th e three classes : paraffin, interm ediate, or naphthene base.
Nelson 23 gives a list of m ethods for judging th e base of an oil. A part
from considering th e properties indicated in the reports by N. A. C. S m ith,17
an d Lane and G arton,20 there are several m ethods which m ake use of th e
fact th a t properties are a function of th e character of crude oils for the
purpose of evaluating th e “ base ” of stocks.
One can com pare th e properties of an unknow n oil w ith th e properties
of know n stocks. This m ethod, however, has to be applied to a large
num ber of sam ples.24
The “ cast ” of lubricating oils gives to a certain ex ten t inform ation on
th e base.25
The gasoline content plo tted against specific gravity of crude oils shows
zones for th e three m ain bases of oils.26
Some of th e m any 27 m ethods which correlate two or more physical
properties in order to obtain an “ average ” chemical constitution or the
“ predom inating ” constituents in petroleum fractions are th e viscosity
index, th e characterization factor, th e characterization gravity, and, quite
recently, th e correlation index.
The viscosity index and the viscosity gravity constant have been exten­
sively described in th e literatu re,28 and only reference to this literature
need be m ade here.
The characterization factor has been developed by members of the staff
of th e U niversal Oil P roducts Com pany,29’ 30> 31 and is defined as th e ratio
of th e cube root of th e average boiling point (in degrees Rankine) to the
specific grav ity a t 60°/60° F . F o r highly paraffinic crudes this factor is
12-5-13-0, while for arom atic or naphthenic crude-oil fractions its value is
10 or below, an d th e increase betw een 10 and 12 indicates the increase in
paraffinicity. The factor has also been related to m any other physico­
chemical properties.30 I t is additive on a weight basis.32
The S tan d ard Oil Com pany of California has developed a te st to classify
heavy oils as to th eir paraffinicity, th e characterization gravity,33 which
is defined as “ the arithm etic average of the instantaneous gravities of the
distillate boiling a t 350°, 450°, an d 550° F. vapour-line tem perature a t
25 mm. pressure in a true-boiling-point distillation.”
H . M. Sm ith 34 states th a t his correlation index
“ cannot be com pared to a ‘ base ’ system of classification as it is not
a means of grouping crude oils according to th eir properties. I t
provides a cross-sectional view of th e distillable portion of a crude oil,
employing for this purpose num bers or indexes th a t represent the
average boiling-point and specific-gravity characteristics of the
distilled fractions.”
This m ethod of correlation of physical properties is therefore not m eant
to evaluate th e “ base ” for th e “ base ” system , and the system of correla­
tion indexes can w ith advantage be included in analyses 39 as a classification
on its own or in addition to th e “ base ” system.
Sm ith 34 claims, th a t
“ th e defects of th e ‘ base ’ system are elim in ated; Differences are
shown equally w ith similarities, there are no border-line cases or
4
M A R G O SC H E S :
C L A S S IF IC A T IO N
O F C R U D E O IL S .
doubtful classifications, an d nam es are n o t used, hence th e danger of
form ing misconceptions due to the nam e is elim inated.”
I t will perhaps be interesting to give a sho rt description of th e develop­
m ent an d use of th is term .34
Sm ith considers first th e relationships betw een boilin g points an d specific
gravities existing in 1940 : th e boiling point—g ra v ity constant of Jack so n
for crude-oil fractions an d th e characterization factor 29 for pure h y d ro ­
carbons. H e reaches th e conclusion th a t an ideal relationship between
boiling po in t and specific g rav ity should show system atic differences
betw een th e m em bers of th e homologous series of hydrocarbons an d also
betw een th e homologous series. This ideal case is n o t entirely reached, b u t
th e reciprocals of th e boiling points, in degrees K elvin, for th e norm al
paraffins p lo tted against th e ir specific gravities (at 60° F .) “ G ” show a
linear relation. This line is used as a reference base for th e interp retatio n
of th e other hydrocarbons and, because no hydrocarbon of a n y other
series w ith th e same boiling point has a fighter specific g ravity, th is lim iting
boundary has been assigned an index num ber C.I. of 0 . A fine parallel to
it and passing thro u g h th e co-ordinates of th e hydrocarbon benzene has
been given an index num ber C.I. = 100. These tw o fines enclose an area
which contains m ost of th e hydrocarbons, except polynuclear com ponents.
The equation for th e straig h t fines is :
b is th e in tercept on th e ^
axis.
= b — 9-7396 X 10“3 G, where
6 for th e fine th ro u g h th e norm al paraffins
is 9-392 X 10'3, b for th e fine thro u g h benzene is 11-448 X 1W3.
correlation index equation is :
48 640
C.I. = -
+
XA
The
473-7 G - 456-8.
This equation m ay be applied to pure hydrocarbons, an d also to fractions
of crude oils, in which la tte r case C.I. is only an average value for the
hydrocarbon m ixtures. According to S m ith, fractions w ith C.I. 0-15 are
alm ost certainly predom inatingly paraflfinic; a C.I. above 50 indicates
“ th a t arom atic rings probably predom inate,” an d a C.I. 15-50 indicates
“ naphthenes or different m ixtures of paraffins, n ap hthenes an d arom atics.”
Side-chains have an influence on th e value.36 W hen applied to crude oil
fractions, th e “ average boiling po in t ” “ K ” is used. There are several
definitions for this term .31 All can be obtained from th e volum etric
average boiling p o in t b y applying a correction factor based on th e slope of
th e distillation curve. F o r sm all values o f th e slope th e correction is
sm aller th a n th e errors of th e d istillation m ethod, a n d th e volum etric
average boiling po int can be used w ith an accuracy of w ithin one index
num ber.34 The volum etric average boiling po in t is determ ined by m easur­
ing w ith a planim eter th e average height of th e curve from th e te m p eratu re
axis, or b y averaging th e tem peratures for th e initial point, end point, and
tem peratures of each 10 per cent, of th e distillation. Sm ith 37 gives two
tables b y m eans of which one can read th e correlation index for an y given
specific g rav ity of th e H em pel fractions. The correlation index is n o t
additive.40 I t seems useful in obtaining refining characteristics of crude
M A R G O SC H E S :
C L A S S IF IC A T IO N
O F C R U D E O IL S .
5
oils (see also under “ Decim al System ” ), which subject Sm ith 38 discusses
in a R eport on Illinois crude oils, in which he proves th a t oils which had
been shown to have a sim ilar correlation index had been used by refiners to
m anufacture a sim ilar series of products.
In another R ep o rt on Illinois crude oils, Rees, Henline, and Bell 39 give
th e correlation indexes and characterization factors for each fraction of
th eir num erous H em pel M ethod Distillations.
(B) Decimal System.
A decim al system has been proposed by Voinov,41 and is being further
developed. Voinov classifies th e crude oils into classes, sub-classes, and
groups, according to th eir properties, and so far has assigned 3-figure
num bers. The figures in th e num bers so far consider th e content of
resinous substances, sulphur, and paraffins.
Two m otives underlie th e work to develop m ethods for analysing, char­
acterizing, and classifying crude oils ; th e one is th e purely scientific
purpose of furthering th e progress of our knowledge, th e other is th e wish
to obtain characteristics of crude oils which are of use to the refiner in
selecting suitable crudes for m anufacturing desired products.42' 43, 44
W hatever classification of crude oils has been adopted, based on either
separate or combined application of schemes w ith regard to geographical
distribution, geological location, physical properties, chemical properties,
chemical composition, products, etc., num bers can be assigned to each item
of th e adopted classification b y applying th e decim al classification of
L. C. U r e n 45—which is a modification of Dewey’s system — and/or the
Bruxelles System 46' 47.
(C) Classification with Regard to Products.
A short explanation of w hat is m eant by classification “ w ith regard
to products ” : Beiswenger 43 differentiates tw elve types of crudes (“ A ” to
“ L ” ), and shows the differences in yiçld and quality of various fractions.
Theoretically one can now adays produce any type of refined product from
any crude oil ; however, th e selection of th e refiner will be influenced 43 by
1.
2.
3.
4.
Processing cost.
Yield of products of desired characteristics.
Processing equipm ent available to him.
Price of products.
A lthough such a system will probably be very fluctuating, being a
function of extrem ely variable factors, it seem s47 w orthy of further
development.
C o n c l u s io n .
H aving quoted a few selected references on th e present state of our
knowledge of th e composition and properties of crude oils, some older
classifications 16 have been nam ed and various more recent systems briefly
reviewed.
The more recent systems are the classifications by N . A. C. Sm ith 17 and
Lane and G arton,20 who distinguish groups of “ bases ” ; th e system by H. M.
S m ith,34 who introduces the correlation index; the scheme by Voinov,41
6
M A R G O SC H E S :
C L A S S IF IC A T IO N O F C R U D E O IL S .
who applies a decim al sy s te m ; an d th e arrangem ent by Beiswenger,43 who
classifies crude oils according to th eir products.
F u rth er, th e essential features of several m ethods have been m entioned,
which enable one to evaluate th e “ base ” (Table I., T able I I .,24, 25 26' 28, 29,
. )
30 3 3
L iteratu re which refers to geographical d istrib u tio n an d geological
location, or which relates to th e problem of origin of crude oils (e.g., classifies
th e petroleum as carbonaceous m in e ra l48) has n o t been d ealt w ith.
A lready to -d ay m any organic com pounds can be directly sep arated from
crude oils by fractionation m ethods 10 or synthesized from th em b y applying
various processes 43’ 44. I t will be interesting to see w hether, an d if so how,
(1) th e progress of our knowledge of th e com pounds p resent in th e crude
oils of th e world, (2) th e progress in synthesizing new products from
petroleum as th e u ltim ate raw m aterial, will influence th e developm ent
of classifications. I f th e classifications te n d to become m ore extended
an d /o r subdivided, it is possible th a t, as outlined above,47 an y adopted
classification of crude oils will get assigned num bers to its item s, in order
to aid th e refiner in choosing quickly th e ap p ro p riate crude oil for his
production.
B ib lio g ra p h y .
A . A . E . D u n sta n el a l., “ T h e S cien ce o f P e tr o le u m ,” V o l. I I , L o n d o n , 1938.
B . W . A . G ruse a n d D . R . S te v e n s, “ T h e C h em ical T e c h n o lo g y o f P e tr o le u m ,” 2nd
ed ., N e w Y o rk , 1942.
C. W . L . N elso n , “ P etro leu m R efin ery E n g in e e r in g ,” 2n d ed ., N e w Y o rk , 1941.
la A . N . S a ch a n en a n d M. D . T ilic h e y e v , “ C h em istry a n d T e c h n o lo g y o f C rack in g,”
p p . 184^90, N e w Y o rk , 1932. S ta n d a rd m e th o d for th e q u a n tita tiv e d eterm in a ­
tio n o f th e ch em ica l co m p o sitio n o f crack ed g a so lin e.
s See a lso refs. 2 a n d 5.
c J . C. V lu g ter, H . I . W a term a n , an d H . A . v a n W e s te n , “ I m p r o v e d M eth o d s o f
E x a m in in g M in eral O ils, e s p e c ia lly th e H ig h -b o ilin g C o m p o n e n ts,” J . In st.
P etro l. T ech ., 1932, 18, 7 3 5 -7 5 0 ; 1935, 2 1 , 6 6 1 -6 7 6 . “ T h e A p p lic a tio n o f
■ G rap h ical a n d S ta tis tic a l M eth od s o f H y d ro ca rb o n A n a ly sis t o D ie s e l F u e ls ,”
ib id ., 1939, 2 5 , 6 7 8 -6 8 3 .
d S. S. K u rtz a n d C. E . H e a d in g to n , “ A n a ly sis o f L ig h t P e tr o le u m F r a c tio n s ,”
I n d u s tr. E n gn g Chem . A n a l., 1937, 9, 2 1 -2 5 .
e R . M. D e a n e s ly a n d L. T . C arleton , “ T y p e A n a ly sis o f H y d ro ca rb o n O ils,” In d u str.
E n gn g Chem . A n a l., 1942, 14, 2 2 0 -2 2 6 .
1 S ee also in B ., p p . 5 3 -9 2 , “ H y d ro ca rb o n G rou p s.” I n B ., p p . 9 3 -1 1 8 , “ N on H y d ro ca rb o n C o n stitu e n ts.”
" H . A b rah am , “ A sp h a lts an d A llie d S u b sta n c e s,” N e w Y o rk , 1938.
h O. G. S trieter, “ M eth od for D e te r m in in g th e C o m p o n en ts o f A s p h a lts a n d Crude
O ils,” J . R es. N a t. B u r. S ta n d ., 1941, 26, 4 1 5 -4 1 8 .
’ A . J. H o ib erg a n d W . E . Garris, J r., “ A n a ly tic a l F ra ctio n a tio n o f A s p h a lts ,”
In d u s tr. E n gn g Chem . A n a l., 1944, 16, 294-302.''
2 F . D . R o ssin i, “ A D eca d e o f R esea rch on th e C h em ical C o n stitu tio n o f P e tr o le u m ,”
(1) P ro c. A . P . I . , 1937, 18, I I I , 3 6 - 5 9 ; (2) O il G as J ., 1937, 36, (26), 1 9 3 -2 2 2 ;
(3) R ef. N a t. Gaso. M fr ., 1937, 16, 5 4 5 -5 6 2 .
3 F . D . R o ssin i, B . J . M air, A . F . F o r z ia ti, A . R . G lasgow , J r., a n d C. B . W illin g h a m ,
“ M eth od s for A n a ly sin g th e G asolin e F r a c tio n o f P etro leu m , w ith P relim in a ry
R e s u lts on E a s t T e x a s an d O k lah om a C ru d es,” (1) P ro c. A . P . I . , 1942, 23, I I I ,
7 -1 4 ; (2) O il G a s J ., 1942, 41, (27), 1 0 6 -1 1 4 ; (3) P etro l. R efin er, 1942, 21, 3 7 7 -3 8 2 .
4 A . F . F o r z ia ti, C. B . W illin g h a m , B . J . M air, an d F . D . R o s sin i, “ H y d ro ca rb o n s
in th e G a solin e F r a c tio n o f S ev en R e p r e s e n ta tiv e C rudes, in c lu d in g a ll th e
D is tilla te to 102° C. an d th e A ro m a tic s t o 160° C.” , (1) P ro c. A .P .I ., 1943, 24,
I I I , 34—4 8 ; (2) J . R es. N a t. B u r . S ta n d ., 1944, 32, 11—3 7 ; (3) P etro l. R efin er,
1943, 2 2 , 1 0 9 -1 1 9 .
5 F . D . R o ssin i, “ H y d ro ca rb o n s in th e L u b rica n t F r a c tio n o f P e tr o le u m ,” (1) P roc
A . P . I . , 1938, 19, I I I , 9 9 - 1 1 3 ; (2) O il G as J ., 1938, 37, (27), 1 4 1 -1 5 3 ; (3) R e f
N a t. Gaso. M fr ., 1938, 17, 5 5 7 -5 6 7 .
xvAAxvvjfu'oc'jxxiio .
xvjA T IO N
O F C R U D E O IL S .
7
6 F . D . R o ssin i a n d B . J . M air, “ H yd rocarb on s in th e K erosen e F ra ctio n o f P e tr o ­
le u m ,” (1) P ro c. A . P . I ., 1941, 22, I I I , 7 - 1 2 ; (2) O il O a s J ., 1941, 40, (26), 1 2 9 1 3 2 ; (3) R e f. N a t. Oaso. M fr ., 1941, 20, 4 9 4 -4 9 8 .
7 B . J . M air a n d S. T . S ch ick ta n z, “ C om p osition o f P etro leu m W a x ,” In d u str.
E n g n g C hem ., 1936, 28, 1 056-1057.
8 See also in B ., p p . 3 5 -5 2 , “ H yd rocarb on s in Crude O ils.” In B ., p p . 9 3 -1 1 8 ,
“ N o n -H y d ro ca rb o n C o n stitu e n ts.”
9 A . W . T r u sty , “ H y d ro carb on S tructu re o f P etro leu m is C om p lex,” P etrol. Refiner,
1942, 21, 2 5 7 -2 6 0 .
10 S ee ref. 2, O il Gas J ., 1937, 36, (26), 194 -1 9 7 .
11 S ee ref. 2, O il Gas J ., 1937, 36, (26), 1 97-202.
12 J . R . N ielsen , “ A p p lica tio n o f S p ectroscop y in th e P etroleu m In d u s tr y ,” O il Gas
J . , 1942, 40, (37), 3 4 -3 9 .
O. L . R o b erts, “ Q u a n tita tiv e A n a ly sis b y M ass S p ectro m e try ,” P etrol. E n gr.,
M ay, 1943, 14, 1 0 9 -1 11.
C. H . S ch lesm a n a n d F . P . H och gesan g, “ R a d ia tio n : th e N ew P etro leu m A n a ly tic a l
T o o l,” O il G as J ., 1944, 42, (2), 4 1 -4 4 , 69, 72, 7 5 -7 6 .
13 J . L e co m te in A , p p . 1 1 9 6 -1 2 0 2 , “ T h e A p p lica tio n o f th e In fra-red A b sorp tion
S p ectra to th e S tu d y o f P etro leu m O ils an d S p irits.”
R . B . B a rn es, U . L id d el, a n d V . Z. W illia m s, “ In fra-red S p ectro sco p y In d u str ia l
A p p lic a tio n s,” In d u str. E n gn g Chem. A n a l., 1943, 15, 6 5 9 -7 0 9 ; in b ook form
b ib lio g r a p h y in clu d ed .
14 J . H . H ib b en in A , p p . 1206 -1 2 1 2 , “ T h e A p p lica tio n o f th e R a m a n E ffect to
P etro leu m C h em istry .”
A . A n d a n t in A , p p . 1 2 1 3 -1 2 1 5 , “ A n a ly sis o f P etro leu m S p irits u sin g th e R a m a n
S p ectro g ra p h .”
G. G lockler, “ T h e R a m a n E ffe c t,” R ev. M odern P h y sic s, 1943, 15, 1 1 1 -1 7 3 , esp e ci­
a lly p p . 1 5 6 -1 5 9 .
15 F . F ra n cis a n d S. H . P ip er, in A , p p . 1 2 0 3 -1 2 0 5 , “ T h e A p p lica tio n o f th e X -R a y
M eth o d to th e S tu d y o f th e P araffin H y d ro ca rb o n s.”
16“ C. F . M abery, “ On th e C om p osition o f A m erican P e tr o le u m ,” P roc. A m er. P h il.
Soc., 1897, 36, 1 2 6 -1 4 0 .
4 C. F . M abery, “ A R esu m e o f th e C om p osition a n d O ccurrence o f P etro leu m ,”
P roc. A m er. P h il. Soc., 1903, 42, 3 6 -5 4 .
c S. F . P eck h a m , “ F ir st In te r n a tio n a l P etro leu m C ongress, P aris, 1900,” P etrol.
In d u s tr. T echn. R ev., L on d on , 1900, 3, Su p pl. 3 9 -4 1 .
d K . W . C harichkoff, Z h u m . R u sskoe F iz ik i K h im ich eskoe ohshchestyo, S t. P e te r s­
burg, 1896, 29, 1 5 1 -1 7 1 ; Chem. Z tg ., 1896, 20, 1033; 1897, 21, 7 ; Chem .
Z en trbl., 1897, I I , 2 1 3 -2 1 4 .
" J . A . A k u n ja n z, T r u d y bak. otd. im p . ru ssk. techn. obshch., 1897, 12, 4 3 8 ; Chem.
Z tg . R e p ., 1897, 21 , 311.
K . W . Charichkoff, V estn ik shirov. veshch., 1904, 5, 150; Chem . Z tg. R e p ., 1904,
28 392
9 N a p h th a , 1903, 11, 2 4 -2 5 .
u M. A . R a k u sin , “ P o la rim etrie der E r d o e le ,” p . 38, B erlin , 1910.
* A . R ich e a n d G. H a lp h en , J . de P h a rm , et de C h im ., 1894, 30, (5), 2 8 9 -3 0 0 ; D in g l.
p o ly t. J . , 1895, 29 6 , 9 4 -9 6 .
1 S .-A isin m a n n , D in g l. p o ly t. J ., 1895, 297, 4 4 -4 7 .
* H . v . H o efer, “ D a s E rd oel u .s. V erw en d u n g,” 3rd ed ., p . 107, B rau n sch w eig,
1912.
1 C. E n gler an d H . v . H oefer, “ D a s E r d o e l,” V ol. 1, p p . 226, 2 2 9 -2 3 0 , L eip zig,
1913.
m R . F . B a co n a n d W . A . H am or, “ T h e A m erican P etro leu m In d u str y ,” V ol. 2,
p. 447, N ew Y ork , 1916.
17 N . A . C. S m ith , “ T h e In terp reta tio n o f Crude-O il A n a ly se s,” U .S . B ur. M ines,
R e p . I n v . 2806, 1927, 20 p p .
18 S ee ref. 17, p. 33.
19 N . A . C. S m ith an d E . C. L an e, “ T a b u la ted A n a ly ses o f R e p resen ta tiv e Crude
P etro leu m s o f th e U n ite d S ta te s ,” U .S . B u r. M ines, B u i. 291, 1928, 69 pp.
20 E . C. L a n e a n d E . L . G arton, “ B a se o f a Crude O il,” U .S . B u r. M ines, R ep . In v .
3279, 1935, 12 pp.
21 A . J . K raem er a n d G. W a d e, “ T a b u la ted A n a ly ses o f T e x a s Crude O ils,” U .S .
B u r. M ines, T ech . P aper 607, 1939, p . 2.
22 See ref. 20, p . 10.
23 See in C, C hapter V I I, “ T h e E v a lu a tio n o f O il S to c k s,” pp. 68 et seq.
S ee also for com p arison : “ D eterm in a tio n o f C om pounds-G roups,” esp e cia lly
refs. le a n d le.
8
M A R G O SC H E S :
C L A S S IE I C A tiu jn
u i- < jn u u n
u rn o .
24 See in C, p p . 7 1 -7 6 .
25‘ S ee in C, p . 77.
20 See in C, p p . 71, 72.
27 S ee ref. 2, O il Gas J ., 1937, 36, (26), 202.
S ee also for co m p a riso n refs. lc a n d ls.
,,
28 P . D o c k se y in A , p p . 1 0 9 1 -1 0 9 8 , “ V isc o sity In d e x a n d V isc o sity G r a v ity C on stan t.
S ee in B , p p . 2 2 6 -2 2 8 .
S ee in C, p p . 6 9 -7 1 .
„
J . C. Cragg a n d E . A . E v a n s , “ V isc o sity M easu rem en t a n d V is c o s ity In d e x ,
J . I n s t. P etro l., 1943, 29, 9 9 -1 0 9 .
_ . .
29 K . M. W a tso n a n d E . F . N elso n , “ Im p ro v ed M eth od s for A p p r o x im a tin g C ritical
an d T h erm al P ro p erties o f P etro leu m F r a c tio n s,” I n d u s tr. E n g n g C hem ., 1933,
25, 8 8 0 -8 8 7 .
30 K . M. W a tso n , E . F . N elso n an d G. B . M urphy, “ C h a ra cteriza tio n o f P etro leu m
F r a c tio n s,” In d u s tr. E n gn g Chem,., 1935, 27, 1 4 6 0 -1 4 6 4 .
31 R . L. S m ith a n d K . M. W a tso n , “ B o ilin g P o in ts a n d C ritical P r o p erties o f H y d r o ­
carb o n M ix tu res,” In d u s tr. E n g n g Chem ., 1937, 2 9 , 1 4 0 8 -1 4 1 4 .
32 R . M. D e a n e s ly a n d L . T . C arleton, “ A d d itiv e P h y s ic a l P ro p erties in H y d ro ca rb o n
M ix tu res,” J . P h y s . Chem ., 1942, 46, 8 5 9 -8 7 0 , se e p p . 8 6 3 -8 6 5 .
33 R . C. M ith off, G. R . MacPh&rson, a n d F . S ip os, “ C h aracteristics o f C alifornia
Crude O ils,” P ro c. A .P .I ., 1941, 22, I I I , 2 5 -3 7 , see p . 30.
34 H . M. S m ith , “ C orrelation I n d e x to A id in In te r p r e tin g Crude O il A n a ly se s ,” U .S .
B u r. M ines, T ech . P a p er 610, 1940, 34 p p .
35 E . A . J a ck so n , “ B o ilin g P o in t— G r a v ity C o n sta n t is I n d e x o f L u b e O il C h aracter­
is tic s ,” O il Gas J ., 1935, 33, (44), 16, 20.
36 See a lso ref. 10.
37 S ee ref. 34, p p . 4, 2 9 -3 1 .
38 H . M. S m ith , “ A n a ly se s o f S om e I llin o is Crude O ils,” U .S . B u r. M in es, R e p . In v .
3532, 1940, 27 p p ., see e s p e c ia lly p . 5.
39® o . W . R ees, P . W . H e n lin e , a n d A . H . B e ll, “ C h em ical C h aracteristics o f Illin o is
Crude O ils, w ith a D isc u ssio n o f th e ir G eo lo g ica l O ccu rren ce,” D iv . o f th e S ta te
G eol. S u rv ey , U rb an a, 111., R e p . I n v . 88, 1943, 128 p p .
b See also v a lu es o f C .I. in th e A n a ly se s in : B . G u th rie, “ A n a ly se s o f Crude Oils
from so m e W est T e x a s F ie ld s ,” U .S . B u r. M in es, R e p . I n v . 3744, 1944, 45 pp.
40 S ee ref. 39«, p . 21.
41 B . P . V o in o v , “ In d e x in g o f P etro leu m s an d th e ir C la ssifica tio n ,”
V estnik
S ta n d a rd iza ts ii, 1937, N o . 4, 4 3 - 4 4 ; K h im . R eferat. Z h u m ., 1938, 1, 127; A m er.
Chem . A b str., 1939, 33, 7085.
42 H . D . W ild e, “ W h y Crudes D iffer in V a lu e ,” B u i. A m e r. A s s . P etro l. Geol., 1941,
25, 1 1 6 7 -1 1 7 4 .
43 G. A . B eisw en g er, “ F a cto rs A ffec tin g th e R efin er’s C hoice o f C ru d es,” A m er. In st.
M in. M et. E n g rs., T ech . P u b l. 1155, 1940, .11 p p .
44 A .
E . D u n sta n , “ C h em istry an d th e P etro leu m I n d u s tr y ,” J . I n s t.
P e tro l., 1943,
29, 1 6 3 -1 8 9 .
15 L. C. U ren , “ D ecim a l In d e x o f P e tro leu m T e c h n o lo g y ,” C lev ela n d , 1928.
40 “ C lassification D ecim a le U n iv e r s e lle ,” I n s tit u t I n te r n a tio n a l de B ib lio g ra p h ie,
B r u x e lles, 1 9 2 7 -1 9 3 3 .
47 R em a rk o f th e w riter o f t h is rev iew .
48 H . B rig g s, P ro c. R o y . Soc., E din bu rgh , 1 9 3 0 -1 9 3 1 , 5 1 ,5 4 - 6 3 ; 1 9 3 3 -1 9 3 4 , 54,
1 1 5 -1 2 0 .
THE MICROBIOLOGICAL ASPECTS OF GASOLINE
INHIBITORS.
By
F
r a ser
H.
A l l e n .*
G a s o l i n e s are stabilized against gum and colour form ation, and the
precipitation of T EL, by th e addition of suitable substances known as
inhibitors or anti-oxidants. The use of anti-oxidants to inhibit the
autoxidation of organic compounds was reported by Moureu and Dufraisse
in a series of over th irty publications starting in 1922.1 The stabilization
of m otor fuels by th e addition of inhibitors was first introduced in E ngland
in 1926, where tricresol was employed in m otor benzoles.2 Three years
la ter th e first use of inhibitors by the petroleum industry was reported
in papers by Egloff, Faragher, and Morrell.3 Since th a t tim e gasoline
inhibitors have become regularly employed in stabilizing essentially all
gasoline m otor fuels.
The chemical m echanism by which th e usual inhibitor concentrations
of about 0-002 per cent.- by weight can successfully stabilize gasolines
during storage periods of up to eighteen m onths has never been adequately
explained. I t is known th a t th e form ation of gum is represented by a
chain of chemical reactions, and th a t inhibiting or preventing any reaction
in the chain will consequently re ta rd or prevent th e production of gum
as the final product. H ydrocarbon peroxides are known to represent
the first step in th e form ation of gum in gasolines. Gasoline inhibitors
apparently exert th eir effect by preventing this initial peroxidation.
This contention is supported by th e fact th a t peroxide concentrations are
usually negligible in inhibited gasolines stored in th e dark.
Gasoline inhibitors are sometimes referred to as “ anti-oxidants.”
A nti-oxidants are generally assum ed to protect th e substance to which
they are added by th e preferential oxidation of th e anti-oxidant mole­
cules. The period of protection, or “ induction period,” continues until
the anti-oxidant is completely oxidized. This concept requires th a t one
molecule of anti-oxidant be destroyed for each reaction chain which is
broken or prevented from starting. The num ber of oxidation chains
which are initiated in th e absence of an anti-oxidant even during short
periods of storage far exceeds th e num ber of molecules of inhibitor which
are present. This phenom enon is usually explained by following th e
original concept of Moureu and Dufraisse.1 These workers postulated
th a t th e oxidized anti-oxidant molecule breaks down to yield inactive
oxygen plus th e original anti-oxidant molecule which is ready to de­
activate another activated oxygen molecule. Milas 4 points out th a t a
mechanism of this kind is therm odynam ically unsound, since no provision
is m ade for the energy whiqh m ust be liberated by th e breakdow n of the
oxidized anti-oxidant molecule.
R ecent studies in these laboratories 5 have shown conclusively th a t
* D ep a rtm e n t o f P etroleu m E n gin eerin g, T h e U n iv e r sity o f T exas.
10
ALLEN :
T H E M IC R O B IO L O G IC A L A S P E C T S OJb' G A SU LlJN Ji H'ijCLujJix'-'a.vo.
various micro-organisms in th e w ater phase w hich is norm ally present
below gasoline m otor fuels in storage m ay have a pronounced deteriorating
effect on th e m otor fuel. This effect has also been produced by certain
gasoline-soluble bacterial extracts. The bacterial a ctiv ity was found to
result in m any cases in th e greatly increased form ation of peroxides and
gum in m otor gasolines and th e precipitation of lead te tra e th y l from
aviation gasolines. I n a few cases th e results of bacterial action were
found to be actually beneficial to gasoline stab ility . This stu d y has also
shown th a t all th e com pounds w hich are em ployed com m ercially as gasoline
inhibitors contain a phenolic, or polyphenolic group, an d th ereb y possess
antibacterial properties. A num ber of organic dyes also are know n to be
reasonably good gasoline inhibitors. The bacteriostatic properties of such
compounds is well know n.6' 6,1 An incom plete list of some of th e b etter
inhibitors and reference to th e bactericidal powers of th e inhibitors, or
very closely related compounds, is shown below.
T
able
I.
L itera tu re References w hich D escribe the B a c te ricid a l P ro p e rtie s o f S evera l Com m on
O asolin e In h ib ito rs.
C om pound.
a -N a p h th o l .
p -A m in o p h en o ls
H y d ro q u inon e
0 -, m -, p -C resols
P y ro g a llo l
C atech ol
6 -N a p h th o l .
G u aiacol
In d u c tio n
P erio d .3
D escrib ed a s In h ib ito r
b y -
D escrib ed a s B ac tericid e
by—
2 250
2340
85
210
2185
2400
330
105
F isch er a n d G u sta fso n 7
R o g ers a n d V oorh ees 9
L ew is an d M ead 11
H o ffert a n d S o m e rv ille 2
L e w is a n d M ead 11
H y m a n a n d A y res 14
P u r e O il C o.15
E gloff, et a l l
R a iz is s a n d C lem en ce 8
O stro m islen sk y 10
M aed a 12
K a n o a 13
M aed a 12
M aed a 12
R a iz is s a n d C lem en ce 8
R e a d 16
This relationship betw een th e com m on gasoline inhibitors a n d their
disinfectant properties, together w ith th e fact th a t b acteria are found to
exert a particularly detrim ental effect upon gasolines during storage over
w ater, suggests th a t an im p o rtan t function of these inhibitors is their
ability to minimize bacterial action. Since th e bacteria live in th e w ater
phase an d use th e gasoline as th eir carbon source, it is .logical to assume
th a t th e bacteria ten d to congregate on th e w ater side of th e gasolinew ater interface. The im p o rtan t characteristics of a satisfactory gasoline
inhibitor are th a t th e substance is soluble in gasoline an d as nearly insoluble
in w ater as possible. To be effective as disinfectants against Tm~p.roorganisms below th e gasoline-w ater interface, it is necessary th a t the
bactericidal group in th e chemical stru ctu re of th e disinfectant be located
in th e w ater phase. I t is evident th a t th e com m on gasoline inhibitors
which are used commercially depend on th e ir phenolic groups for th eir
bactericidal properties. I t is also know n th a t phenol an d o th er arom atics
which possess a highly polar radical have a strong tendency to orient
them selves a t th e interface betw een a non-polar organic solvent an d w ater,
so th a t th e polar radical is located in th e w ater phase an d th e benzene
ring is in th e organic solvent. I n th is w ay a gasoline inhibitor which
contains a phenolic group would orient itself a t th e interface in such a
ALLEN :
T H E M IC R O B IO L O G IC A L A S P E C T S O F G A S O L IN E IN H IB IT O R S .
11
way th a t th e toxic hydroxyl group is located below the interface in the
proxim ity of the bacteria.
The efficiency of gasoline inhibitors as bactericides will depend on
th eir concentration a t th e gasoline-w ater interface. No direct m easure­
m ent of this concentration was possible. G ibbs’ rule states th a t if the
interfacial tension of a solvent is reduced by increasing th e concentration
of th e solute, th e n th e solute will be concentrated a t th a t interface. Thus
a decrease in interfacial tension a t th e gasoline-w ater interface when an
inhibitor is added would indicate th a t th e inhibitor is concentrated on the
gasoline side of th e interface. The following surface and interfacial
tension d a ta were obtained on an unleaded aviation gasoline base stock
w ith several commercial gasoline inhibitors and lecithin, which is added
to gasolines to increase inhibitor efficiency. The concentration of the
inhibitors was approxim ately 0-0012 per cent, by weight and of the lecithin,
0-005 per cent, by weight. These interfacial tension m easurem ents were
made w ith a ring type tensim eter.
T
able
II .
S u rface a n d In terfa c ia l T en sion R e la tio n sh ip s o f a n In h ib ited A v ia tio n Gasoline
B ase Stock.
S y stem .
In terfa cia l T en sion .
G asoline—air .
. . .
G a solin e + le c itliin -a ir .
.
.
.
.
.
.
G asolin e + A -n -b u ty l-p -a m in o p h e n o l-a ir .
.
.
.
G asolin e + 2 : 6 -d i-ieri.-b u tyl-4 -m eth y l p h en o l-a ir
G a so lin e-w a ter
.
.
.
.
.
.
.
.
G asolin e + le c ith in -w a te r
.
.
.
.
.
.
G asolin e -j- A -^ -b u ty l-p -a m in o p h en o l-w a te r
G asolin e -j- 2 : 6 -d i-ieri.-b u tyl-4= m eth yl p h e n o l-w a te r .
G asoline -j- J V -isob u tyl-p -am in op h en ol-w ater
G asoline -j- jV -n -b u tyl-p -am in op h en ol + le c ith in -w a te r
28-0 d y n e s/c m .2
27-9
27-9
27-9
36-0
ni l
,,
20-8
33-8
18-0
1-5
There is no question th a t the inhibitors and lecithin are strongly adsorbed
a t the gasoline-w ater interface. Thus, according to Gibbs’ rule, these
m aterials will be concentrated a t th e interface. The orientation concept
th en provides th a t th e phenolic hydroxyl group will be located in the
w ater phase a t th e interface where th e bacteria are also thought to con­
centrate to gain easy access to the gasoline hydrocarbons.
Fig. 1 shows th e orientation of several inhibitor molecules a t the gasolinew ater interface. I t would be expected th a t compounds such as catechol
w ith two phenolic hydroxyl groups which can both be located in the
w ater phase a t the same tim e would be more effective th a n th e mono­
hydroxy phenols. I t is ap parent th a t th e p-am inophenol type of inhibitor
which is used so widely in th e industry consists essentially of a phenolic
group, which is oriented w ith th e toxic hydroxyl group in th e w ater phase
and great enough mass of hydrocarbon radicals to m ake the molecule
more soluble in gasoline th a n in w ater. Thus p-cresol is a b etter inhibitor
th a n phenol, because phenol is too soluble in w ater and does not tend to
concentrate a t th e gasoline-w ater interface so readily. The cresols
generally are also known to be more toxic th a n phenol, as their high
12
ALLEN :
T H E M IC R O B IO L O G IC A L A S P E C T S O F G A S O L IN E IN H IB IT O R S .
phenol coefficients indicate. U sually these hydrocarbon groups are tied
to th e phenol b y m eans of an am ino-nitrogen atom . The alkylated
phenols, especially those which m ay occur n atu ra lly in th e crude, are
also know n to m ake excellent inhibitors. I t is easily observed from th e
illustration th a t hydrocarbon groups which are su b stitu ted in th e para
position to th e phenolic hydroxyl group are th e m ost effective in m ain ­
taining th e desired orientation of th e hydroxyl group in th e w ater phase.
rO
X
O
'*
ro
0
1
X
NH
o-Naphthol
p-Cresol
N -n-B utyl-p-om inophenol
Ca techol
m -C re s o l
Lecith in
F
ig
.
i
.
T H E O R IE N T A T IO N O P I N H I B I T O R M O L E C U L E S A T T H E G A S O L IN E - W A T E R I N T E R P A C E .
S ubstitution in th e ortho and meta positions should n o t be so effective in
th is respect, since th ey would exert a m om ent on th e benzene ring which
would te n d to pull th e phenolic hydroxyl group from th e w ater phase.
Two hydroxyl groups on th e same benzene ring are advantageous if th e y
are ortho to one another so th a t th e y can b o th be located in th e w ater
phase a t th e same tim e. More th a n one hydroxyl group located in th e
meta or para positions is a disadvantage, since th e benzene ring m ust he
in the interface, thereby reducing th e effectiveness of the hydroxyl groups.
The p-am inophenol compounds w hich are used so extensively as gasoline
inhibitors in th e indu stry are secondary amines, and should serve as
effective reducing agents capable of decomposing hydrocarbon peroxides.
Thus, in addition to the toxic phenolic group, these compounds also con­
ALLEN :
T H E M IC R O B IO L O G IC A L A S P E C T S O F G A S O L IN E IN H IB IT O R S .
13
tain a reactive group which m ay destroy such hydrocarbon peroxides as
are formed. Fig. 1 shows th a t this amino group is oriented in the gasoline
phase som ewhat above the gasoline-w ater interface. In this location it
is available to reduce any peroxides which m ay diffuse from the interface
tow ards th e m ain body of th e gasoline. I t appears th a t a gasoline inhibitor
like A -n - butyl -p -a m inophenol serves in th e dual role of (1) inhibiting
bacterial peroxidation by th e toxic phenolic group and (2) reducing
peroxidized hydrocarbons by th e oxidation of th e amino group.
According to th is concept of inhibitor action, a particularly effective
inhibitor for th e storage of gasoline over w ater m ight be a substituted
catechol such as 1 : 2-dihydroxy-4 : 5-di-IV-alkyl aminobenzene, which
would be insoluble in w ater and be capable of orientation w ith two toxic
phenolic hydroxyl groups below th e gasoline-w ater interface.
L e c it h in
as
an
I n h ib it o r I n t e n s if ie r .
The use of soybean lecithin has been described in th e literature to
increase inhibitor efficiency.17’ 18> 19 The mechanisms by which this is
accomplished are vaguely asserted to be “ both physical and chemical.” 17
I t has also been suggested th a t lecithin acts as a peptizing agent or as a
protective colloid in preventing th e form ation of haze in leaded gasolines.19
Lecithin is found to be insoluble in w ater and soluble in gasoline in w hat
appears to be a tru e solution. Since th e choline and oleic, palm itic and
glyceryl phosphoric acid which are th e ap p aren t reactive components of
lecithin did n o t give th e same stabilizing effect as lecithin itself,17 it is
concluded th a t it is th e physical size of th e non-polar molecule which
accounts for this property. The fact th a t lecithin is so strongly adsorbed
a t th e gasoline-w ater interface suggests th a t its actual function in increas­
ing inhibitor efficiency when gasoline is stored over w ater m ay be an ability
to facilitate th e orientation of th e phenolic inhibitors a t th e interface.
Previous work in these laboratories has shown th a t th e rate of gum form a­
tion in gasolines stored over w ater is greatly increased by th e presence
of air or oxygen in th e w ater phase.20 I t was also concluded from the
same w ork th a t m ost of th e deterioration takes place a t th e gasolinew ater interface.
Two possible explanations of th e mechanism by which lecithin is capable
of inhibiting th e deterioration of gasolines in storage are suggested from
th e foregoing discussion. These m ay be classified as physical (la and 16)
and bacteriological (2) as follows, (la) L ecithin is known to be adsorbed
on th e gasoline side of th e interface, where it m ay serve as an inert layer
which retards th e diffusion of oxygen and/or oxidation products from
th e interface to th e m ain body of th e gasoline. (16) I t is also possible
th a t th e large molecules of lecithin m ay aid in orienting or stabilizing th e
orientation of th e phenolic groups of th e inhibitors a t th e interface.
(2) Most of th e micro-organisms which are present in gasoline storage
tan k w aters are soil bacteria. Lecithin is easily hydrolysed by soil bacteria
to produce glycerol, fa tty acids, phosphoric acid, and choline.21 I t is
suggested th a t lecithin m ay have a beneficial effect on gasolines which
would otherwise be subject to bacterial action by being preferentially
attacked, thereby sparing the hydrocarbons from oxidation. I t is reported
14
ALLEN :
T H E M IC R O B IO L O G IC A L A S P E C T S O F G A S O L IN E IN H IB IT O R S .
th a t lecithin is also effective as an inhibitor when gasolines are stored dry.
I t is general refinery practice to divert finished m otor fuels to ta n k farm
storage over w ater before th e y are m easured into drum s for shipm ent.
D uring this storage over w ater gasoline is subject to bacterial action.
The gasoline m ay also become contam inated b y ex tractin g detrim ental
oxidative enzymes into th e gasoline phase. These enzymes would th en
be carried into th e d ry storage w ith th e gasoline. Since all bacterial
action m ay be considered as being enzym atic an d m any of th e enzymes
produced by bacteria are gasoline-soluble, it is possible th a t dissolved
lecithin could exert a sim ilar beneficial effect on dissolved oxidative
enzymes in contam inated gasolines stored dry.
M etal D
e a c t iv a t o r s .
The use of disalicylal ethylene for th e d eactivation of copper, iron,
cobalt, and vanadium has been described by Downing, Clarkson, and
Peterson.22 Traces of these m etals, p articu larly copper, in gasolines have
a very severe effect on its storage stability. A ny of th e m etals which
these authors have nam ed m ay constitute th e m etallic ato m in th e por­
phyrin enzymes. The porphyrin enzym es are v ery active biological
oxidation and reduction catalysts w hich are form ed by bacterial as well
as other form s of life. The porphyrins are v ery widely d istrib u ted in
n a tu re,23 and th eir solution or dispersion in gasoline as a resu lt of bacterial
action seems quite likely. I t appears possible th a t these m etals m ay
actually be present in th e gasoline in th e form of th eir po rp h y rin com ­
pounds. Disalicylal ethylene m ight th e n d eactiv ate these several m etals
by some reaction w ith th e p o rphyrin molecule w hich w ould reduce its
activ ity as an oxidation-reduction enzyme. This hypothesis presents an
interesting topic for futu re research.
Sum mary.
A new theo ry is presented to account for th e delay in th e deterioration
of gasoline m otor an d aviation fuels w hich is produced b y th e addition of
inhibitors. The bactericidal properties of th e commercial inhibitors are
noted. D a ta are presented to show th a t these inhibitors are strongly
adsorbed a t th e gasoline-w ater interface where th e y are able to exert
th eir greatest bactericidal activity. The m icrobiological aspects of
inhibitor intensifiers an d m etal deactivators are also discussed. This
biological concept of gasoline inhibitors is in ten d ed to supplem ent the
extensive chemical research which has been conducted on th e deterioration
of gasoline m otor fuels in storage.
A
cknow ledgem ent.
The auth o r wishes to express his ap p reciation to Dr. Lewis F . H atc h
and Dr. H . J . Sawin of this U niversity for th e ir help in th e p rep aration
of this paper.
L itera tu re C ited.
1 M oureu, C., a n d D u fra isse, C., C om pt. ren d., 1922, 174, 258.
2 H o ffert, W . H ., a n d S m ith v ille, P . G ., B r. P . 1926, 2 1 2 , 928.
ALLEN :
T H E M IC R O B IO L O G IC A L A S P E C T S O F G A S O L IN E IN H IB IT O R S .
15
3 E g lo ff, G ., F aragh er, W . P ., a n d M orrell, J . C., I n d u str. E ngng C hem ., 1932, 24,
1375; 1933, 25 , 315, 8 04; 1936, 28, 122.
4 M ilas, N . A ., Chem . R e v., 1932, 10, 295.
5 A llen , F . H ., P h .D . T h esis, U n iv e r s ity o f T e x a s,
1944, “ T h e E ffect o f V arious
M icro-organ ism s o n th e P recip ita tio n o f L ead T e tra eth y l from A v ia tio n F u els
a n d th e F o rm a tio n o f G um in M otor G asolin es.”
6 A rd agh , E . G. R ., a n d P a tte r so n , N . J ., B .A .S c.
T h esis,
U n iv e r s ity o f T oron to,
1933, “ T h e In h ib itio n o f G um F o rm a tio n in Cracked G asolin e E x p o se d to S u n ­
lig h t b y th e U s e o f V ariou s O rganic D y e s .”
60 L ow ry, C. D ., E gloff, G ., M orrell, J . C., an d D ryer, C. G ., In d u str. E ngng C hem .,
1935, 27, 413.
7 F isch er, H . G. M ., a n d G u sta fso n , C. E ., U .S .P . 1,904,433 (18th A p ril, 1933);
Chem . A b s ., 1933, 27, 3598.
8 R a iziss, G. W ., an d C lem ance, L. W ., U .S .P . 2 ,0 7 3 ,9 9 7 ; Chem. A b s., 1937, 31,
3214.
9 R o g ers, T . H ., a n d V o orh ees, V ., In d u s tr, E ngng Chem ., 1933, 25, 520.
10 O stro m islen sk y , I ., U .S .P . 2 ,0 4 0 ,1 8 3 ; Chem. A b s., 1936, 30, 4629.
11 L ew is, W . K ., a n d M ead, B ., Can. P . 302,271 (22nd J u ly , 1930); Chem . A b s .,
1930, 24, 4384.
13 M aeda, M ., F o lia P h a rm . J a p a n , 1936, 21, 3 02; Chem . A b s., 1936, 30, 3518.
13 K o a n a , R „ A rch . H y g ., 1923, 92, 139; Chem. A b s., 1924, 18, 543.
14 H y m a n , J ., and A y res, G. W ., B .P . 364,533 (1930); Chem. A b s., 1933, 27, 2027.
15 P ure Oil C om p any, F ren ch P . 701,340 (1930); Chem. A b s ., 1931, 25, 4116.
16 R ea d , R . R ., U .S .P . 2 ,1 7 8 ,6 0 8 ; Chem. A b s., 1940, 34, 1445.
17 E ick b erg , J ., In d u str. E n gn g Chem. (N ew s E d .), 1941, 19, 575.
18 J a co b s, J . J ., a n d O thm er, D . F ., In d u str. E ngng Chem., 1943, 35, 883.
19 R ees, H . V ., Q u im b y, W . S ., a n d O osterh ou t, J . C. D ., P roc. A .P .I ., S ect. I l l ,
1940, 21, 6.
20 A llen , F . H ., M .S. T h esis, T h e U n iv e r s ity o f T e x a s, 1941, “ T h e E ffect o f W ater
a n d B len d in g on th e D eterio ra tio n o f G asolin e M otor F u e ls in S to r a g e.”
21 S alle, A . J ., “ F u n d a m e n ta l P rin cip les o f B a c te r io lo g y ,” 1943, M cG raw -H ill, N ew
Y ork , 5 2 0 .
22 D o w n in g , F . B ., C larkson, R . G ., an d P ed erson , C. J ., N a t. P etrol. N ew s, 5 th A p ril,
1939, 31, (14), R 129; O il C as J ., 2n d J u ly , 1939, 39, (11), 97.
23 G reen, D . E ., “ M ech an ism s o f B io lo g ica l O x id a tio n s,” 1940, Cam bridge.
16
THE ANALYSIS OF LIQUEFIABLE HYDROCARBONS
BY DISTILLATION.
B y t h e L i q u e f i e d G a s e s P a n e l o f S u b - C o m m i t t e e N o . 3 .— L i q u e f i e d
P e t r o l e u m G a s e s , G a s o l in e , K e r o s i n e , a n d L ig h t D is t il l a t e s .
A P a n e l of Sub-Com m ittee N o . 3 of th e S tan d ardization C om m ittee h a s
been concerned for some tim e w ith m ethods for th e exam ination of P etro l­
eum Gases. This P anel, w hich is composed as follows :
W . H . T h o m a s (Chairman) (A nglo-Iranian Oil Co., L td.).
J . W . A r m s t r o n g (Im perial Chemical In d u stries, L td.).
N. A s t o n ( E sso E uropean L aboratories).
J . H . D. H o o p e r (A nglo-Iranian Oil Co., L td.).
N. E. J o n e s (Trimpell, L td.).
has devoted m uch atte n tio n to form ulating a procedure w hich would be
generally acceptable for th e analysis b y distillation of liquefiable h ydro­
carbon gases. The ap p aratu s used for th is purpose is diverse in form and
com plexity, and various ty p es are used, according to th e n a tu re of the
product being exam ined, th e precision of th e results desired, an d the
resources of th e lab o rato ry concerned.
I t was concluded, therefore, th a t it was neith er practicable nor desirable
a t th e present tim e to a tte m p t to standardize an y particu lar form of
apparatu s or to lay down, in*the detail norm ally associated w ith S tandard
M ethods, th e procedure for carrying o u t th e determ ination of these light
hydrocarbons.
I t m ay in th e fu tu re be possible to do this, b u t in th e m eantim e the
Panel felt th a t it was desirable to form ulate a general procedure which
should be applicable to an y reliable m ethod for distillation analysis an d to
agree on th e best available d a ta for th e boiling points an d densities of the
hydrocarbons for use in calculation. This view was agreed by Sub-Com­
m ittee No. 3 and by th e S tandardization C om m ittee.
The following m ethod is published for inform ation, an d it is suggested
th a t analysts who are interested in th is aspect of th e w ork should send any
com m ents or criticism s to th e Secretary of th e In s titu te for consideration
by th e Sub-Com m ittee and Panel concerned.
I t should be noted th a t m any points of distillation technique described
in this paper have been taken from a pap er b y Savelli, Seyfried, a n d F ilbert
entitled “ M ethods of L ig h t H ydrocarbon Analysis ” (Industr. Engng
Chem. Anal., 1941, 13, 868), and acknow ledgm ent m u st therefore be m ade
to these authors.
•
E. B. E vans.
Chairman, S tand ard izatio n Sub-Com m ittee No. 3.
T H E A N A L Y S IS O F L IQ U E F IA B L E H Y D R O C A R B O N S B Y D IS T IL L A T IO N .
17
P r in c ip l e
This m ethod involves th e distillation of gaseous and liquid hydrocarbon
m ixtures into fractions which consist essentially of hydrocarbons containing
th e same num ber of carbon atom s. The olefine content of each fraction is
determ ined by m eans of an O rsat ty p e of constant-pressure gas analysis
ap p aratu s, and th e d a ta th u s obtained, supplem ented by the distillation
curve, afford an accurate analysis.
A ppa r atu s.
Several different models of low -tem perature fractional distillation
app aratu s are available, some being fitted w ith autom atic devices for
controlling column pressure, reflux cooling, distillation rate, etc., and others
being entirely m anual in operation. The apparatus consists essentially
of a distilling bulb of from 15 ml. to 100 ml. capacity, and a vacuum
jack et enclosing a column containing a wire packing. The column head is
fitted w ith m eans for cooling, to provide reflux to th e column, and th e
outlet therefrom is m anifolded to m anom eters, a distillation ra te control
valve or cock, distillate receivers, vacuum pum p, and sample burettes or
Topler pum p for sam ple rem oval. The distillate receivers m ay be either
vacuum bottles, generally of 1- and 3-gallon capacity, or large graduated
burettes in which th e distillate is collected by displacem ent of a suitable
confining liquid, such as m ercury, brine, or satu rated zinc sulphate solution.
A therm ocouple is provided for recording th e column head tem perature.
P
rocedure.
The individual instructions issued w ith each apparatus should be followed
as closely as possible. The following gives a general outline of th e procedure
and indicates th e factors which are necessary for good fractionation.
The ap p aratu s is evacuated and tested for leaks. I f it is gas-tight, th e
column head and distilling bulb are cooled strongly by means of liquid
nitrogen. I f th is is n o t available, liquid air m ay be used instead, b u t in
view of th e dangers attending th e em ploym ent of this m aterial in close
proxim ity to liquid petroleum products, th e following precautions should be
rigidly observed :
(1) The distilling bulb m ust never be allowed to come into direct
contact w ith liquid a ir; it should be enclosed in a protecting m etal
or pyrex glass sleeve.
(2) W hen purging th e sam ple en try line, care should be taken th a t
th e vented gas is n o t condensed by th e liquid air used for cooling th e
distilling bulb.
(3) Some non-inflam m able m aterial such as glass wool should be
used for lagging a t th e m outh of th e Dewar vessel enclosing th e distil­
ling bulb. On no account m ust cotton wool be employed for this
purpose.
ffe
IJui
toimercial liquid nitrogen m ay also contain an appreciable percentage&f o % gen, it is recom m ended th a t the above precautions should also be
observed w ith this m aterial,
c
18
T H E A N A L Y S IS O F L IQ U E F IA B L E H Y D R O C A R B O N S B Y D IS T IL L A T IO N .
Samples m ay be introduced into th e bulb in th e liquid form (after th e
rem oval of H 2S), b u t are norm ally charged to th e a p p aratu s in th e gaseous
state, and are condensed in th e distilling bulb after passing th ro u g h caustic
alkali solution and calcium chloride for th e rem oval of acidic co n stitu en ts
and m oisture. I f uncondensable gases are present, th e column pressure
will rise ; it should be m aintained substantially a t atm ospheric pressure by
allowing th e gas to pass into one of th e receivers while th e rem ainder of th e
sample is being liquefied. W hen a t least 10 ml. of th e liquefied sam ple
have been a d m itted into th e distillation bulb, th e sam ple inlet is closed, and
th e receiver m anifold isolated from th e column. The refrigerant is now
rem oved from th e D ew ar vessel enclosing th e distilling bulb and th e em pty
vessel replaced round th e bulb.
The distillation is now com m enced by sw itching on th e cu rren t to the
electrical w indings a tta c h e d to th e bulb. The colum n pressure rises as th e
charge becomes w arm , and is brought to atm ospheric pressure b y releasing
uncondensable gases to th e receiver. W hen th e colum n has been brought
to equilibrium under total reflux by w arm ing th e distilling bulb a n d chilling
th e column head, u n til th e whole length is w et w ith reflux, th e receiver
pressure is recorded for th e uncondensable gases. The gas is now distilled
a t ab o u t 20 ml. per m inute an d allowed to pass over into th e distillate
receiver. D uring th e distillation, te m p eratu re an d pressure shall be
recorded a t frequent intervals, to provide d a ta for th e distillation curve.
In order to achieve consistently accurate results from th e column, the
following standardized procedure, w ith m odifications as n o ted according to
th e natu re of th e sample, m u st be rigidly followed :
(1) W hen charging th e
im portance :
sam ple,
th e
following points
are
of
(a) The sam ple e n try line should be as sh o rt as is conveniently
possible.
(b) The contents of th e distilling bulb m ust n o t be allowed to
blow back down th e sam ple e n try line.
(c) W hen samples of liquefied gas are w ithdraw n from pressurety p e containers, th e sam ple should be taken from th e b o tto m of the
container— i.e., from below th e surface of th e liquid.
(d) Liquefied gases containing any appreciable q u a n tity of
C5 or C6 com ponents should be charged directly to th e ap p aratu s
through as short a line as possible, as passage th ro u g h th e norm al
scrubbing tra in m ay result in th e p a rtia l condensation of these
components.
(2) A fter charging th e sample, th e tem p eratu re in th e bulb and
head of the column are so balanced th a t th e colum n is operated under
to ta l reflux a t slightly reduced pressure (about 100 mm . less th a n
atm ospheric) for a period of tim e depending on th e n atu re of th e sam ple.
This is particularly useful for b u ta n e separations. A period o f 30
m inutes is usually sufficient. The pressure in th e colum n is th e n
slowly increased to atm ospheric, an d th e distillation is begun w ith th e
tem p eratu re in th e head of th e colum n a t th e boiling po in t of th e
T ,t® A N A L Y S IS O F L IQ U E F IA B L E H Y D R O C A R B O N S B Y D IS T IL L A T IO N .
19
_Shtest com ponent in th e sample. I f th e sample contains large
th e ntities of m ethane, th e distillation m ay be sta rte d w ithout bringing
under to ta l reflux,
large fl Ur3nS the distillation, every effort should be m ade to avoid
m ended tlUati°ns in th e column pressure, and it is therefore recomnressm-A .
aPparatus be fitted w ith some system of autom atic
arm aratn«
' Reflux ratio should be m aintained a t 15 : 1, and
nmTOinn i° r m®asuring this ratio m ust be provided unless special
a p p a ra tu s
&S
^ been m ade by th e m anufacturer of the
(4)
D uring th e distillation, the tem p eratu re in th e condenser section
o îe co um n, as recorded by th e m illivoltm eter or potentiom eter, is
tak en as an indication of the p u rity of th e overhead product, and on
plateaux is m aintained as near as possible to th e tru e boiling point of
th e com ponent being w ithdraw n. I f on a plateau th e tem perature
should rise above th e boiling po in t of th e com ponent being w ith ­
drawn, th e take-off should be discontinued im m ediately an d th e
column operated under to ta l reflux u n til th e tem p erature returns to
its form er value. The distillation should th e n be resum ed a t a slower
rate. I f th e tem p eratu re should again rise, th is procedure should be
repeated u n til a take-off ra te , w hich will m aintain th e plateau tem pera­
tu re a t a constant value, has been established or u n til a break is
certain.
The boiling points (at 760 mm. Hg) of th e lower hydrocarbons
m ay be ta k e n as :—
M ethane
E thylene
E th an e
Propylene
P ropane
isoB utane
isoB utene
B utene — 1
B utene —2 (m ean value)
B utadiene 1-3 .
n-B u tan e .
isoPentane
w-Pentane .
161-4
103-9
88-9
47-7
42-2
11-8
6-8
6-3
+
1-0
+
+
4-5
0-5
27-95
35-95
(5)
I n general, th e following take-off rates, a t atm ospheric pressure,
will be found to be satisfactory.
B reaks
P lateau x
b u t it will be appreciated th a t
reduced rates will be required.
to be long, th e m axim um figure
exceeded, b u t im m ediately th e
— 2 - 5 ml. gas/m inute.
- 1 0 - 2 0 ml. gas/m inute.
a t pressures lower th a n atm ospheric,
W here, however, plateaux are known
of 20 m l./m inute m ay be considerably
column-head tem perature shows any
T H E A N A L Y S IS O F L I Q U E F IA B L E H Y D R O C A R B O N S B Y D IS T IL L A T IO N .
tendency to rise, th e colum n m u st be sh u t in a n d th e ra te reduced,
as described above.
(6) W hen a break between com ponents is im m inent (as indicated
either by a decrease of pressure in th e column or b y a “ thinning out
of th e reflux on th e column packing, or both), th e colum n should be
operated under to ta l reflux for several m inutes while th e boiling ra te
in th e bulb is reduced. B y reducing th e boiling rate , th e liquid reflux
on th e column packing is fu rth e r “ th in n ed o u t,’' th u s m aterially
reducing th e column hold-up (while m aintaining a high reflux ratio)
and increasing th e sharpness of th e break. A fter these conditions
have been established, th e take-off is again begun a t a v ery slow rate,
an d continued u n til th e break is com pleted. (Note.—I f it is desired
to isolate th e various fractions, th e distillate receiver should be
changed when th e cu t p o in t tem p eratu re is attain ed .) F o r colum ns
fitted w ith autom atic take-off controls, th e above procedure m ay,
of course, be considerably modified, and, in p articular, when distilling
sam ples containing large quan tities of m ethane, ethane, or propane.
F o r such sam ples, th e d istillation conditions m ay be so controlled on
p lateau x (by controlling th e h e a t inp u t) t h a t th e boiling ra te is auto­
m atically reduced when approaching a break. U nder these conditions,
th e necessity for operating th e column u n d er to ta l reflux will be
obviated.
(7) The fractions m ay be collected in different b u rettes, a n d their
volumes m easured a t atm ospheric pressure b y suitable m anipulation
of m ercury, brine, or zinc sulphate solution reservoirs, or th e y m ay
be collected in large evacuated bottles m aintained a t co nstant tem pera­
ture. The distillation is stopped tem p o rarily a t each cu t po in t while
th e receiver is changed or re-evacuated. F re q u e n t readings of tem pera tu re an d pressure should be ta k e n th ro u g h o u t th e breaks, so th a t
an accurate distillation curve can be p lo tted .
(8) The pressure in th e receiving system should be kep t, by re ­
peated evacuation, if necessary, so low th a t th e p a rtia l pressure bf any
co n stituent is far below th a t pressure a t w hich it will condense a t th e
tem p eratu re of th e receiver. The m axim um pressures recom m ended
are :—Cl5 C2, and C3 .
C4 .
.
.
C5 .
-.
.
.
.
—A tm ospheric pressure.
—300 mm. H g. (absolute).
—100 mm . H g. (absolute)..
After each reduction in pressure, th e colum n is op erated under to ta l
reflux for a t least 15 m inutes, to bring it to equilibrium .
(9) A t th e conclusion of th e distillation th e bulb is filled w ith
m ercury to reduce dead-space errors, a n d a n y residual reflux on the
packing and gas in th e colum n is draw n over into a fresh evacuated
receiver.
(10) W hen a sam ple is distilled under th e above conditions, the
appearance of th e finished distillation curve is ta k e n as th e best
indication of th e fractionation, an d hence analytical accuracy, obtained
during th e analysis. I n appearance, th is curve should have th e follow­
ing characteristics :
T H E A N A L Y S IS O F L IQ U E F IA B L E H Y D R O C A R B O N S B Y D IS T IL L A T IO N .
21
(a) The p lateaux should be horizontal, w ith few fluctuations
(such as are caused by excessive pressure variations, flooding in the
column and other undesirable operating conditions), and should
show no rise in tem perature, even when approaching a break.
(b) B reaks betw een com ponents should be sharp, exhibiting
little “ sloughing off ” a t th e plateaux, except in the case of
separations betw een isomers or betw een paraffins and olefins
containing th e sam e num ber of carbon atom s.
Samples of th e various fractions obtained will norm ally require to be
analysed for individual components such as hydrogen, olefins, etc.,
in th e appropriate auxiliary apparatus.
Ca l c u l a t io n
of
R
esu lts.
Provided th a t th e distillation is carried ou t under th e conditions laid
down in parag rap h (8) above, th e gases are assum ed to obey th e perfect
gas laws, and th e increases in pressure in th e receiver for each fraction are
assum ed to be proportional to th e volumes of those constituents in th e to ta l
gas. The am ount of sam ple tak en is given b y th e to ta l pressure rise in the
evacuated receivers (differences in size betw een th e various receivers being
duly corrected for), and th e volume percentage of each gas can th u s be
obtained.
I f it is desired to express th e results as weight percentages, it is necessary
to convert th e pressure rise equivalent to each constituent to the appro­
p ria te w eight by th e form ula :—
W eight in gm. of constituent A =
where
hence
hence
P / X Ca x F x 273 X M W a
760 x K x 22,410
P f = rise in pressure in mm. representing fraction containing A.
Ca = volume percentage of A in fraction.
P f X Ca = rise in pressure in mm. due to A.
V = to ta l volume in ml. of receiving bottle and lines to
still-head ta p .
P f X Ca x V
— —y.------- = volume in ml. of A a t 760 mm. pressure.
K = absolute tem perature (Kelvin scale) of receiving bottle.
hence
^
X
X F X 273 = volume in ml. of A
760 x K
pressure and °C.
a t 760 mm.
M W a = m olecular w eight of A.
22,410 = gm. m olecular volume in ml.
To obtain th e results as liquid volume percentages a t 60° F., th e following
proposed specific gravities a t 60° F. m ay be used :—
T H E A N A L Y S IS O F L I Q U E F IA B L E H Y D R O C A R B O N S B Y D IS T IL L A T IO N .
M ethane
E thylene
E th a n e
P ropylene
P ropane
¿.soButene
B utene —1
B utene —2
¿-Butane
»-B utane
Pentenes
¿-Pentane
» -P en tan e
¿-Hexane
»-H exane
.
.
.
.
.
0-3
0-390
0-374
0-5215
0-5073
0-603
0-600
0-615 (mean)
0-563
0-584
0-658 (mean)
0-625
0-631
0-658
0-664
23
REVISED CLASSIFICATION OF ABSTRACTS
(Prepared by Mr. C. L. G ilbert on behalf of th e A bstracts Sub-Committee)
T h e A bstracts Sub-Com m ittee has decided to make some changes in
th e headings under which th e abstracts are classified, and these are being
brought into operation in th e current num ber of th e Journal. Difficulties
arose in th e previous system for tw o reasons : (1) separate headings were
provided for products and th e tre a tm e n t of products, and it was th u s not
clear w hether, for example, th e refining of m otor fuels should be placed
under Refining or under M otor F u e ls; (2) th e field to be covered by some
of th e product headings was not clear, e.g. th e distinction between Synthetic
and Special Products.
An a tte m p t has therefore been m ade to define more precisely th e field to
be covered by each heading. A dditional headings have been provided
where necessary, and, while some of th e present headings have been dropped,
m ost of them have been retained for convenience.
As will be seen from th e list a t th e foot, th e subject m atter has been
divided into six m ain categories, these roughly following th e stages in the
treatm en t of petroleum and allied products. E ach of these is then divided
further as required. A few notes on these headings m ay assist in showing
where d a ta required m ay be located in th e abstracts.
Oilfield Exploration and Exploitation.
This m ain heading covers th e original headings, Geology and Develop­
m ent, Geophysics, Drilling, P roduction and Aerial Survey. In th e new
system D evelopm ent has been separated from Geology, as it logically
follows P roduction, whereas Geology comes first. Aerial Survey is now
included in Geology.
Transport and Storage.
No change.
Refinery Operations.
In this m ain section are placed d a ta on the refining of any product,
petroleum or otherwise, i.e. if it is a question of refining, it is placed here
rath er th a n under th e product nam e. A num ber of changes and additions
to th e sub-headings have been made. Thus the original Refining and
Refinery Operations is now restricted to general descriptions of refineries,
and of auxiliary refinery equipm ent. New headings have been m ade for
Chemical an d Physical Refining; D istillation; Solvent E xtraction and
D ew axing; A dsorption and A bso rp tio n ; Iso m erization; and Special
Processes, while Polym erization and A lkylation have been separated. The
heading M etering is now expanded to include Control, while Fire Prevention
is dropped as this is logically included in Safety Precautions.
Products.
This section covers only th e properties and uses of products (including
p aten ts relating thereto), th eir m anufacture being placed in th e previous
24
R E V IS E D
C L A S S IF IC A T IO N O F A B S T R A C T S .
section. The headings Chem istry and Physics and Analysis an d Testing
apply to all products, w hether petroleum or otherwise.
U nder Crude Oil will be placed d a ta only on its properties. U nder Gas
will be placed d a ta on all gases other th a n those used as m otor fuels.
The heading M otor Fuels has been superseded by th e heading Engine
Fuels, an d this now includes Diesel Fuels. In fo rm atio n previously placed
under th e heading of D etonation and Engines will go either under the
Engine Fuels heading or under a separate heading— Engines.
The n e x t heading th e n becomes Gas Oil and Fuel Oil. I t will be noted
th a t oils for high-speed diesel engines are n o t included here, b u t under
E ngine Fuels.
The old heading L ub rican ts an d L ubrication has been shortened to
L ubricants, th e subject of L ubrication being im plied as a p ro perty of a
L ubrican t.
The heading A sphalt and B itum en has been expanded to include Tar
under th e new arrangem ents, w hereby allied p roducts of all sources are
included u n d er th e new p ro d u ct headings. This heading will also include
inform ation on emulsions, products containing bitum en or norm ally asso­
ciated w ith them , such as soils, aggregates, etc.
T he heading Special P ro d u cts has been divided into Special Hydrocarbon
P rod u cts an d D erived Chemical P roducts, th e form er including H ydro­
carbon m aterials such as kerosines, w hite spirits, wax extracts, spray oils,
etc., an d also including ingredients norm ally used w ith these products {e.g.
P y re th ru m used in fly sprays). The heading D erived Chemical Products
includes non-H ydrocarbon P ro d u cts obtained from Petroleum and allied
products.
A fu rth e r category of Miscellaneous P ro d u cts is provided for m anu­
factu red products w hich cannot be classified under th e above headings,
such as P ain ts, S ynthetic R ubbers, Plastics, S ynthetic Fibres.
Engines and Automotive Equipment.
This heading covers th e ap p ro p riate p a rt of th e original heading Detona­
tio n an d Engines, b u t it is hoped to expand it to include any new Auto­
m otive E q u ip m en t of in terest, e.g. cars, aeroplanes, etc. R oad tests on
new equipm ent will also be included here.
Miscellaneous.
This m ain heading is for inform ation on Petroleum from th e point of view
of history, economics, statistics, legislation, specifications, m arketing, etc.
Cl a s s if ic a t io n
M ain Heading.
E
x p l o r a t io n
E
and
x p l o it a t io n
T r a n spo r t
and
S torage
of
A
bstr ac ts
Sub Heading.
Geology.
Geophysics an d Geochemical Prospecting.
Drilling.
Production.
Oilfield D evelopm ent.
R E V IS E D
R
e f in e r y
O p e r a t io n s
P roducts
E
n g in e s
and
C L A S S IF IC A T IO N O F A B ST R A C T S.
25
Refineries and A uxiliary Refinery P lant.
D istillation.
A bsorption and A dsorption.
Solvent Refining and De waxing.
Cracking.
H ydrogenation.
Polym erization.
A lkylation.
Isom erization.
Chemical an d Physical Refining.
Special Processes.
M etering an d Control.
Safety Precautions.
' C hem istry and Physics.
Analysis and Testing.
Crude Oil.
Gas.
Engine Fuels.
Gas Oil and Fuel Oil.
L ubricants.
B itum en, A sphalt, and Tar.
Special H ydrocarbon Products.
D erived Chemical Products.
Coal, Shale, and P eat.
. Miscellaneous Products.
A u t o m o t iv e E
q u ip m e n t
M is c e l l a n e o u s .
C O RRIG EN D U M .
“ Sintered Glassw are.”
1944, 30(252), 387.
B y I. C. P.
S m it h ,
J. Inst. Petrol., December
The la st sentence of th e p arag rap h en titled “ An Em ulsifying Machine ”
should read as follows : “ A pplication has been m ade for a p a te n t to
cover this p articu lar use of sintered glassw are.”
26
OBITUARY.
S IR JO H N JACOB F O X , C.B., O .B.E., D.Sc., F .R .S .
W e regret to announce th e d eath of one of our senior honorary members,
Sir Jo h n Jaco b Fox, C.B., O .B .E., D.Sc., F .R .S ., th e G overnm ent Chemist.
H e was born in 1874 an d entered th e G overnm ent L ab o rato ry in Clements
In n in 1904. H e succeeded a form er honorary m em ber, Sir R o b e rt R o b ert­
son, as G overnm ent Chemist in 1936. D uring th e w ar he served in m any
capacities in D epartm en ts of S tate and co n trib u ted w idely from his long
and unique experience in chem ical science an d technology.
The w riter of th is note w ould ra th e r rem em ber F ox as a very genial and
kindly soul who, indeed, regarded m ost of his contem poraries and juniors
as his own friends. The w riter’s m em ory goes back fo rty years to the
tim e w hen he an d F ox w orked side b y side in th e research laboratory of
an o th er genial and friendly soul, E m eritius Professor H ew itt, of Queen
M ary College, w hen tw o other m em bers of Council— Col. A uld and Dr.
Thole—were fellow stu d en ts w ith him.
Only a few m onths ago m any of F o x ’s co-workers assem bled to pay
honour to him on th e conferm ent on him of K nighthood an d th e Fellowship
of th e R oyal Society, an d it is sad to th in k th a t so soon afterw ards he
passed over.
A. E. D.