Industrial and Engineering Chemistry : analytical edition, Vol. 13, No. 5

INDUSTRIAL ^{a n d} ENGINEERING CHEMISTRY

A N A L Y T IC A L E D IT IO N

H A R R IS O N E. H O W E , E D IT O R • IS S U E D M A Y 16. 1941 m V O L . 13, N O . 5 • C O N S E C U T IV E N O . 10

A N A L Y T IC A L M E T H O D S S Y M P O S IU M

D e t e r m i n a t i o n o f H e a t o f C o m b u s t i o n o f G a s o ­ lin e s ... W . H. Jones a n d C . E. Starr, Jr. 2 8 7 T e m p e r a t u r e C o e f f ic ie n t o f D e n s ity a n d R e f r a c ­

tiv e I n d e x f o r H y d r o c a r b o n s i n L iq u i d S t a t e . . M. R. Lipkin a n d S. S. Kurtz, Jr. 291 C o n s is te n c y T e s t f o r L u b r i c a t i n g G r e a s e s . . . .

H arry Levin a n d C h a rle s J. S ch lag el 29S A n a ly tic a l P r o c e d u r e f o r M i x t u r e s o f O r g a n ic

S u l f u r C o m p o u n d s ...

Richm ond T. Bell a n d M. S. A gruss 2 9 7 V is c o s ity M e a s u r e m e n t ...

M. R. C a n n o n a n d M. R. F enske 2 9 9 Q u a l it y T e s ts f o r P e t r o l e u m S o lv e n t N a p h t h a s .

E. H. M cA rdle a n d E. L. B ald esch w ieler 301 E v a l u a t i o n a n d P e r f o r m a n c e o f T u r b i n e O ils . .

G . H. von Fuchs, N. B. W ilson, a n d K. R. E dlund 3 0 6 R in g M e t h o d f o r D e t e r m i n a t i o n o f I n t e r f a c i a l

T e n s io n . H. H. Zuidem a a n d G e o rg e W . W aters 312 D e t e r m i n a t i o n o f W ax i n A s p h a l t ic P r o d u c t s . .

E. C. K now les a n d H arry Levin 314 I n d i a n a S t i r r i n g O x i d a ti o n T e s t f o r L u b r i c a t i n g

O ils . G . G . Lamb, C . M. Loane, a n d J. W . G a y n o r 317 I n s t r u m e n t a l M e t h o d s o f C h e m i c a l A n a ly s is . . . 3 0 5 V is c o s ity D e t e r m i n a t i o n o f C e llu lo s e . . . E. B erl 322 D e t e r m i n a t i o n o f M e r c a p t a n S u l f u r C o n t e n t o f

G a s o lin e s a n d N a p h t h a s ...

H ans S ch in d ler, G e o rg e W . A yers, a n d L. M. H en d erso n 3 2 6 D e t e r m i n a t i o n o f W a t e r i n B e n z e n e ...

J. H. Sim ons a n d E. M. K ipp 3 2 8 M e a s u r i n g S m o k e s a n d R a t i n g E ffic ie n c ie s o f I n ­

d u s t r i a l A ir F i l t e r s ...

A. C . Robertson, J. G . M ulder, a n d F. G . V anS aun 331 A. C . S . A n a l y ti c a l R e a g e n t s ... 3 3 4 P a r t ic l e S iz e D e t e r m i n a t i o n b y S e d i m e n t a t i o n . .

K arl K am m erm eyer a n d J. L. B inder 3 3 5

R e c o v e ry o f M e r c u r ic I o d id e a n d I o d i n e f r o m N e s s le r iz e d S o l u t i o n s ...

G . W e b e r Schim pff a n d Russell E. P o ttin g er 3 3 7 D e t e r m i n a t i o n o f I o d a t e I o n i n P r e s e n c e o f C u p r ic

I o n ... P. L. Kapur and M . R. Verma 338 P o l a r o g r a p h i c S t u d y o f A l i p h a t i c N i t r o C o m p o u n d s

Thos. De V ries a n d R. W . Ivett 3 3 9 T r a c e r I s o to p e s i n A n a l y ti c a l C h e m i s t r y ...

John F. Flagg a n d Edw in O . W iig 341 S . I. L. V i s c o m e t e r ...

E. L. Ruh, R. W . W alker, a n d E. W . D ean 3 4 6 Q u a n t i t a t i v e D e t e r m i n a t i o n a n d S e p a r a t i o n o f

C o p p e r w i t h B e n z o tr ia z o le . . . J. A lfred C u rtis 3 4 9 V a c u u m T u b e T im e - D e la y R e la y . . Earl J. Serfass 3 5 2 C a l i b r a t i o n o f E x is tin g G u m - S t a b i l i t y T e s t B o m b s

i n T e r m s o f N e w A . S . T . M . B o m b ...

D. L. Yabroff a n d E. L. W alters 3 5 3 In e x p e n s iv e L a b o r a to r y C i r c u l a t i n g P u m p . . . .

H. M ilton W o o d b u rn 3 5 6 C o n v e n ie n t D is t i ll i n g C o l u m n H e a d ...

P au l A rth u r a n d C h a rle s L. Nickolls 3 5 6 C O R R E S P O N D E N C E

B r o m i n a t i o n o f P h e n o l s b y M e a n s o f B r o m id e - B r o m a t e S o l u t i o n ...

A lfred W. F ran cis a n d A. J. Hill 3 5 7 M IC R O C H E M IS T R Y

P r o c e d u r e f o r S e m i m i c r o d e t e r m i n a t i o n o f S u l f u r i n O r g a n ic C o m p o u n d s ...

R obert M. Lincoln, A. S. C arn ey , a n d E. C . W a g n e r 3 5 8 D e t e r m i n a t i o n o f C l e a n l in e s s o f F e a t h e r a n d

D o w n B e d d in g M a t e r i a l s . . . . H aro ld J. Kane, C h a rle s Pom erantz, a n d M orris H ech tm an 3 6 2 M i c r o d e t e r m i n a t i o n o f M o l e c u l a r W e i g h t s o f

D a r k - C o lo r e d O r g a n ic M a t e r i a l s . V. A. A luise 3 6 5 D e t e r m i n a t i o n o f Z in c b y P r e c i p i t a t i o n a s Z in c

A n t h r a n i l a t e ... C . W . A n d erso n 3 6 7

T h e A m erican C hem ical Society assum es no resp o n sib ility for th e sta te m e n ts a n d opinions ad v an ced b y c o n trib u to rs to its p ublications.

25,200 copies of th is issue p rin ted . C o p y rig h t 1941 b y A m erican C hem ical Society.

P u b l i c a t i o n O f f ic e x E d i t o r i a l O f f ic e : R o o m 7 0 6 , M i l l s B u i l d i n g , W a s h i n g t o n , D . C .

T e l e p h o n e : N a t i o n a l 0 8 4 8 . C a b le : J i e c h e m ( W a s h i n g t o n )

Published b y th e A m erican C hem ical Society, P u b licatio n Office, 20th <fc N o rth am p to n Sts., E a sto n , P e n n a . E n tered a3 second-class m a tte r a t th e P o st Office a t E a sto n , P e n n a ., un d er th e A c t of M arch 3, 1879, as 24 tim es a year. In d u stria l E d itio n m o n th ly on th e 1 st; A naly tical E d itio n m o nthly on th e 15th. A cceptance for m ailing a t special ra te of p ostage p rovided for m Section 1103, A ct of O ctober 3. 1917, au th o rized J u ly 13, 1918.

A nnual subscription r a te , In d u stria l E d itio n a n d A nalytical E d itio n

»old only as a u n it, m em bers $3.00, o th ers $4.00. Foreign postage to countries n o t in th e P a n A m erican U nion, $2.25; C an ad ian postage, $0.75.

E a s t o n , P e n n a .

A d v e r t i s i n g D e p a r t m e n t : 3 3 2 W e s t 4 2 n d S t r e e t , N e w Y o r k , N . Y . T e l e p h o n e : B r y a n t 9 - 4 4 3 0

Single copies: In d u stria l E d itio n , $0.75; A naly tical E d itio n , $0.50. Special ra te s to m em bers.

N o claim s can be allowed for copies of jo u rn a ls lo st in th e m ails unless such claim s are received w ith in 60 d ay s of th e d a te of issue, a n d n o claims will be allowed for issues lo st as a re s u lt of insufficient notice of change of address. (T en d a y s’ ad v an ce notice required.) “ M issing from files*' c an n o t be accepted as th e reaso n for honoring a claim . A ddress claim s to C harles L. P arsons, B usiness M anager, 1155 16th S t., N . W ., W ashington, D . C ., U. S. A.

New Condensate

Impurity Alarm

New Glass Electrode pH Indicator For $160

T his instrument is a specialized Indicator for two purposes only— the speedy, routine measurement of pH with glass electrodes, and the location of end-points in routine titrations with the same electrodes.

It is easier to use, faster, simpler, and lower priced, than any other of our glass- electrode pH instruments. N ot being a potentiometer, it is also less accurate, but its limit of error is still only 0.1 pH — guaranteed. And it is built to the same standards of quality which characterize the L&N Universal pH Indicator.

Characteristics include:

1. Full accuracy in atmospheres of 95% re la ­ tive hum idity up to 85 F.

2. Easy to read because the double range of 0-8 and 6-1+ pH provides a convenient overlap of 2 pH . . . a desirable feature for titrations.

3. Only 3 dial settings, including tem pera­

ture compensator w hich ends com puta­

tions, saves time, prevents errors.

4. Instrum ent is shielded from ord in ary elec­

trical disturbances.

5. F acto ry -sealed -an d -filled -eleclro d es a re highly stable.

6. Sample cup is a standard 50 ml. beaker;

only 15 ml. is necessary for measurement.

7. Leadw ires are long enough so that elec­

trodes can be used outside the case, for titration as well as pH.

8. T h e calibrated scale is longer than in any comparable pH indicator, and the pointer mechanism is outstanding for reliability and accuracy.

9. Spent batteries can’t corrode rest of instru­

ment. M aintenance is negligible.

Each Indicator is sent complete w ith supply of chemicals and operating directions. T h e catalog num ber is 7 6 6 2 -A l; price $160.00.

W e now have available a new con­

densate impurity alarm which affords a low-cost method of helping to keep con­

densate free from contamination. It is specifically designed for use where con­

tinuous recording is not needed.

It is simple, compact, and has no moving parts except a relay. Its only measuring accessory is a conductivity cell which goes into the condensate line.

It is calibrated in ohms, and can be set to compensate for temperature of conden­

sate. T he control point is set by turning a slidewire. As long as purity is satis­

factory, a green light shows. If purity drops below the control setting, a red light shows. T he instrument can also be used to operate an external alarm or valve.

T h e condensate impurity alarm can also be used as an indicating instrument.

T o measure actual condensate resistance with it, the operator merely turns the control dial until the lights change, and reads the answer on the dial.

W rite for further information.

Jrl Ad K .\T -0li00B (9)

L E E D S &. N O R T H R U P C O M P A N Y , 4920 S T E N T O N A V E ., P H 1 L A ., PA.

M E A S U R IN G IN S T R U M E N T S • T E L E M E TE R S A U T O M A T IC C O N TR O LS • H E A T -T R E A T IN G FURNACES

May 15, 1941 A N A L Y T I C A L E D I T I O N 5

C orning

y means h Research in Glass

/ \ / — r - w \

th e d e m a n d s u p o n y o u r la b o ra to rie s a re g re a te s t you

\ l I I X E A J a p p re c ia te B a la n ce d G lass m o st. F o r th is is th e id e a l lab o ra - to r y g iass—th e a ll-a ro u n d g lass. Y o u tu rn to it confidently, su re o f its s tre n g th , c e rta in o f its stab ility , a n d p o s itiv e o f its th e rm a l r e ­ sistance. A ll o f th ese p ro p e r tie s a re balanced o n e a g a in s t th e o th e r. N o t o n e has b een e n h a n c e d at th e e x p e n se o f a n o th e r. A ll a re p re s e n t in th e d e sire d p r o p o r tio n fo r virtually any la b o ra to ry w o rk . A ll are com bined fo r m axim um value— m axim um la b o ra to ry usefulness.

In th e se days w h e n tim e is such a fac to r, w h e n tests, r e p o rts , a n d fin d in g s are m o re u rg e n t th a n ever, sta n d a rd iz e o n B alanced G lassw are. A lw ays specify P yrex b ra n d L a b o ra to ry W a re , th e on ly g la ssw a re m ad e o f P yrex b ra n d C h em ical G lass, th e B alan ced G lass. A vailable fro m y o u r re g u la r la b o ra to ry w a re dealer.

“ P Y R E X ." is a registered tra d e -m a rk a n d in d ica tes m a n u fa ctu re by

C O R N I N G G L A S S W O R K S • C O R N I N G , N . Y.

6 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 13, No. 5

C H IC A G O 1 7 0 0 Irvins

Blvd.

Lakeview Station

S C I E N T I F I C I N S T R U M E N T S

T O

C H IC A G O

L A B O R A T O R Y A P P A R A T U S

• Toronto • San Francisco

B O S T O N 79 Amherst St.

Cambridge A Station

CENCO VARIABLE-SPEED STIRRERS

U n e q u a lle d in

B e a u ty

Design

P e rfo rm a n c e

C o m p a r is o n o f p o w e r a n d to r iju e c ur v es o f N o . 18805 S t ir r e r , u s i n g a s p l i t- p l i a s e m o t o r ( s o lid lin e s ) u -ith a n o t h e r s tir r e r ( d o t t e d lin e s ) , u s i n g a s lu id e d - p o le m o t o r o f c o m p a r a b le d i m e n ­ s io n s . N o te t h e h i g h t o r q u e a n d la rg e p o w e r o u t p u t o f N o . 18805 S tir r e r a t a ll s p e e d s . T h e p o w e r is c o n s t a n t a b o v e v a lu e s o f s p e e d w h e r e

t h e r e is n o s lip p in g .

P o w e r-T ra n s m is s io n

18805 M O T O R S T IR R E R S , E lectric, Cenco V ariable S p eed , F rictio n C one D rive, for all la b o ra to ry stirrin g , d riving an d ro ta tin g o p eratio n s req u irin g precise co n tro l of speed th ro u g h th e range from ap p ro x im ately 80 rp m to 1300 rp m w ith o u t reducing stirrin g effectiveness b y th e speed control m echanism , as is th e case w ith stirrin g devices hav in g rh eo sta t-o p e rate d speed control. A d eq u ate pow er is av ailab le fo r stirrin g ex trem ely viscous liquids. Speed of stirrin g does n o t change in use. W hen s tirre r is set for a c e rtain speed, it will rem ain th e sam e for th e e n tire stirrin g p eriod, even th o u g h th e consistency of th e m a terial being stirre d changes g re a tly . As th e s tirre r m a y be clam ped to a v ertical su p p o rt rod w ith th e s h a ft an d chuck p o in tin g e ith e r u p o r dow n or a t rig h t angles to th e s u p p o rt rod, i t m a y be used as a variab le-sp eed ro ta to r.

C om plete w ith su p p o rt ro d clam p, chuck, con n ectin g cord w ith a tta c h m e n t plug, b u t w ithout stirrin g rods.

N o ... ... A B C D

F o r v o lts ... ... 115 230 115 230 F o r c u r r e n t... ... A.C. 60 cy A .C . 60 cy D .C . D .C . E a c h ... ... $29.50 30.00 33.50 35.00 D e tail of C one F rictio n -D riv e

M echanism of No. 18S05 S tirrer 18805 show n in use.

M e c h a n is m

C o m p le te ly

Enclosed

May 15, 1941 A N A L Y T I C A L E D I T I O N 7

G-E XRD Unit Provides Qualitative and Quantitative Organic Analysis

The analysis o f a dust suspected o f causing silicosis, photomicrograph (A), presented a problem typical o f many encountered in modern chemical laboratories. That it could best be solved by x-ray diffraction with the G-E X R D U n it—a highly successful method o f investigating submicroscopic materials

—is evidenced by th is in te re stin g case history. <( T h is crystalline w ater-soluble organic silicate extracted from lung tissue, photomicrograph (B ), shows the types o f crystal structure. Polarized light analysis o f this material revealed it to be a complex organic compound.

An x-ray diffraction pattern (A -l), registered by the dust sample, proved the presence of, and established the fact that it contained, sufficient silica compounds to be o f toxic significance. <{ From the x-ray diffraction pattern (B-l), registered by a specimen o f the crystalline water-soluble extract o f lung tissue, it was possible to identify the nature o f the complex organic structure and establish the presence o f silicates in the compound.

W hile the problem o f silicosis is not one that you may encounter, its solution by the G-E X R D U nit is o f importance to you. The ability o f the X R D Unit to solve this problem is offered as concrete evidence that, with it, you can analyze all types o f submicroscopic crystal m aterial— both qualitatively and quantitatively— with unusual speed and a high degree o f accuracy.

The G-E X R D U nit with its complete assembly o f diffraction cameras— each a precision instrum ent designed to meet the exacting standards required in analytical p ro ce d u re s— offers a so lu tio n for many o f the numerous problems encountered in the control and investigation o f materials used in m anufacturing processes. For com plete details and data about the G-E X R D U nit and its application to your problem s, write, today, to D epartm ent R3.

GENERAL ELECTRIC X -R A Y CORPORATION

i ł S / 2 0 1 2 J A C K S O N B L V D . C H I C A G O , I L L . , U. S. A.

8 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 13, No. 5

The A v o ir d u p o i s P ound which served a s the exchequer st a n d ­ a rd o f m a s s d u r in g the d a y s o f Q ue en Elizabeth.

Standard of Mass. . .

Since the very beginnings of recorded history, standards of mass have been established for the control of accuracy and uniformity in weighing.

Today, pre-determined standards of purity, control the accuracy and uniformity of M al­

linckrodt A. R. Chemicals. Stringent refining,

testing and re-testing by skilled chemists insure dependable analytical chemicals for accurate analysis.

• • •

S end for la te s t M a llin c k ro d t catalo g u e o f A n a ly tic a l R e a g e n ts a n d o th e r chem icals for la b o ra to ry use.

I t co n ta in s d e ta ile d d escrip tio n s o f chem icals for ev ery ty p e o f a n a ly tic a l w ork . . . g rav im etric, gaso- m e tric, calo rim etric o r titrim e tric . 1

M A L L I N C K R O D T C H E M I C A L W O R K S

ST. LOUIS • PHILADELPHIA • M O N TR EA L

C H IC A G O • NEW YORK • TO R O N TO

May IS, 1941 A N A L Y T I C A L E D I T I O N 9

STRAIN FREE

sumŸHoùw*

U H Î T E D E T A Ï E

m m

V I N E L A D N J

■ c " , c a s o " ’ ’ "

» ro v ed by;

T li o r o i ig l i A fiiie aliiig

testing w ith p o la riz e d lig h ts H id d e n ' -'strains s h o w - u p as c o l o r e d s t r e a k s , -

'

w hen a su itab le co lo r filter is used*

' 'C ontrolled Amiealiwg removes.'-tlie'v s t r a i n f r o m KlraMe-, Lahoratoiwir^-v'

■ - iW i ^ : / • G l , , 8 8 „ „ e .

i p i M i

^ ^ B l i U E

TYPICAL h it ! ITEMS

B U R E T T E S

c"pv 1,y _{m l. m | f} *«•* ° uan"’yin c a s*

10 0.05 $1.75 12

25 .1 $1.75 18

50 .1 $1.75 24

100 .2 $2.53 6

F O R Q U A N T IT Y P R IC E S C O N S U L T Y O U R

D EA L ER

17030-S T

S & H 5 ' THE p i o n e e r- o f c o l

T .T 'W * » . M I

8

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10 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 13, No. 5

S E R F A S S

E L E C T R O N RAY T I T R A T I O N A S S E M B L Y

for th e d e te rm in a tio n of en d p o in ts in gen eral o x id atio n -red u ctio n re actio n s

E L E C T R O N RAY T IT R A T IO N A SSEM B LY , S e rfa ss. C onsisting of an electrical control u n it w ith an electron ra y tu b e (m agic eye) m o u n ted in ex tern al holder an d A .H .T . Co. T itra tio n S ta n d w ith accessory e q u ip ­ m en t including p la tin u m an d tu n g ste n electrodes.

T h e o u tfit o p erates d irectly from eith e r a.c. o r d.c. su p p ly sy stem s on a sim ple elec­

tronic c irc u it designed b y D r. E arl ,1. Serfass, of L ehigh U n iv ersity . See In d u stria l and Engineering Chemistry, A n a l. E d ., Vol. IS, N o. 9 (September 15th, 1940), p. 536. T h e am plified p o ten tial differences orig in atin g betw een th e electrode-solution in terface are tra n s m itte d to th e electron ra y tu b e w hich ind icates en d p o in ts in sta n ta n e o u s ly b y a change in th e size of th e w edge-shaped shadow w hich a p p ea rs on th e

circu lar fluorescent ta rg e t w ith th e tu b e. T h e e n d p o in t occurs w hen th e larg est p erm an en t change in shadow angle tak e s place per d ro p of tit r a n t added.

T h e co n tro l u n it consists of a co m p act v acu u m tu b e v o ltm e te r w ith v o ltag e reg u lato r an d connections for pow er sup p ly , electron ra y tu b e, electrodes a n d stirrin g m o to r. O n th e panel are dials for v ariatio n of se n sitiv ity a n d control of th e ra y posi­

tion a n d sw itches for connection w ith pow er su p p ly an d s tirrin g m o to r a n d for control of th e polarizing c u rre n t. T h e electron ra y tu b e is m o u n ted in a se p a ra te housing w ith a d ju s ta b le clam p fo r a tta c h ­ m en t to th e v e rtica l rod of a su p p o rt s ta n d for con­

v e n ie n t o b serv atio n of e n d p o in ts as in d icated b y th e opening an d closing of th e “ ey e.”

T h e o u tfit utilizes th e self-polarizing p latin u m - tu n g sten electrode sy stem an d is su itab le for use w ith platin u m -n ick el, calom el-platinum o r polarized p latin u m -p latin u m electrode system s, b u t is n o t a d a p te d for titra tio n s req u irin g th e glass electrode.

P a r tic u la r ly s u ita b le fo r :

T h e direct determ in atio n of chrom ium a n d vanadium in steel.

T he determ in atio n of chrom ium in chrom e tanned 4937.

le a th er and in chrom e tan n in g liquors.

G en eral potentiom etric titratio n s involving potassium d ichrom ate, iodine, p e rm an g an ate, eerie su lp h ate, ferro u s su lp h ate, sodium thiosul- p h ate a n d ferrocyanide.

Lim ited applications to acid -b a se and precipitation titratio n s, b u t not ad ap ted for pH determ in atio n s.

A d v a n ta g e s :

Sim plicity of operation.

T urbidity a n d color do n o t affect accuracy.

T he u sual d elicate indicating m e te r is rep laced by the electron ray tu b e which in d icates continuously w ithout th e ann o y an ce of key tapping.

Line operation elim in ates the in h e re n t disad v an tag es of b a tte ry operation.

A voltage reg u lato r stab ilizes the in stru m e n t a g ain st a.c. line fluctuations.

Sensitivity is continuously v ariab le, w ith full 100° shadow angle in th e “ m agic ey e,” from 50 m illivolts upw ard.

T he control u n it supplies polarizing c u rre n t w hen req u ired for polarizing m o n o -m etallic electro d es.

T h e electrical u n it is placed to one Bide of th e titratio n sta n d a n d is th e re fo re n o t su b je c t to corrosion from th e sam ple.

4937. E lectro n R ay T itra tio n A ssem bly, S e rfass, as above described, com plete assem bly as show n in illu stra tio n , consisting of co n tro l u n it w ith electro n r a y tu b e in se p a ra te housing w ith a d ju s ta b le clam p for a tta c h m e n t to s u p p o rt rod, titra tio n s ta n d com plete w ith base a n d sw inging shelf of C oors porcelain, p a ire d b u re ttes , clam ps, p la tin u m an d tu n g ste n electrodes w ith holder, a n d s tirrin g a p p a ra tu s w ith m o to r fo r 110 volts, 60 cycles, single p h ase a.c.

W ith d e ta ile d d irections fo r use including ste p b y ste p pro ced u res for ty p ic a l titra tio n s a n d p re p a ra tio n of sta n d a rd s o lu tio n s ... 8 3 .9 5 4937-F. C ontrol U nit, S e rfass, only, as included in above o u tfit, w ith electro n ra y tu b e in s e p a ra te cylin d rical housing w ith a d ju s ta b le clam p fo r a tta c h m e n t to su p p o rt rod. F o r 110 volts, 25 to 60 cycles, a .c ' ... 40 .00 N O T E — C ontrol U n it can be su pplied for use on 220 volts a.c. and for 110 or 220 v o lts a .c ./d .c . Prices on request.

M ore detailed information sent upon req uest

A R T H U R H. T H O M A S C O M P A N Y

R E T A IL — W H O L E S A L E — E X P O R T

LABORATORY APPARATUS AND REAGENTS

W E S T W A S H IN G T O N S Q U A R E , P H IL A D E L P H IA , U . S . A.

C able Address, “ B alance,” P hiladelphia

INDUSTRIAL ^{a n d} ENGINEERING CHEMISTRY

A N A L Y T I C A L E D I T I O N

P U B L I S H E D B Y T H E A M E R I C A N C H E M I C A L S O C I E T Y • H A R R I S O N E . H O W E , E D I T O R

S y m p o s iu m on A n a ly tic a l M ethod s Used In th e P e tro le u m In d u s tr y , pages 287 to 321.

D eterm ination o f the H eat o f C om bustion o f G asolines

W . H . J O N E S AND C . E . S T A R R , J R .

E s s o L a b o r a to r i e s , S t a n d a r d O il C o . o f L o u is ia n a , B a t o n R o u g e , L a.

D

lines is becoming increasingly important and is in­

cluded in certain aviation gasoline specifications. The application of this test to gasolines must be accompanied by a more closely controlled procedure than th a t ordinarily employed by petroleum testing laboratories for heavier fuels, in order to obviate losses of the more volatile com­

ponents of the gasolines, such as butanes and pentanes, which have the highest heating values.

Considerable work has been published on the art of calor­

imetry since Andrews (1) first used the bomb calorimeter in 1848. A comprehensive bibliography on this subject is fur­

nished by Kharasch {14). The apparatus, technique, and procedure of modern calorimetry have been described a t con­

siderable length by Dickinson (

4

The work on the heat of combustion of hydrocarbons has been done mainly on pure compounds in order to study the relation between energy, structure, number of carbon atoms, and the influence of organic groups. For this purpose the apparatus and technique have been developed to such a high degree of precision and accuracy that, according to Rossini (22), measurements of quantities of energy can be made with uncertainties as low as 0.01 to 0.02 per cent. To attain this degree of accuracy considerable time, apparatus, and a pre­

cise technique are necessary. However, in the practical application of this test to gasolines, such precision is not war­

ranted.

A procedure has been developed whereby six to eight determinations per day can be made on low-boiling (aviation) gasolines, with an accuracy of ± 0.2 per cent.

A p p a r a tu s a n d M a te r ia ls

A calorimeter of the adiabatic type was employed. This consisted of a double-valve oxygen bomb, a calorimeter bucket with stirrer, and a water-jacketed case equipped with a stirrer and connections to hot- and cold-water lines for maintaining adiabatic conditions.

A Beckmann thermometer calibrated by the National Bureau of Standards was used to measure the temperature rise. The jacket temperature was controlled with respect to the calorimeter bucket temperature by means of two 3-junction thermocouples and a galvanometer as shown in Figure 1. Slight differences in temperature between the bucket and the jacket are clearly

287

shown by the galvanometer and thus a sensitive balance can be maintained.

The oxygen used should be at least 99.8 per cent pure and free from any combustible material. Commercial oxygen made by the liquid air process frequently contains as much as 0.3 per cent of hydrogen, possibly from contamination, and should be passed over copper oxide at 600° to 700° C. before being used for calorimetric work. Keffler (11, 12) has shown that even elec­

trolytic oxygen may contain considerable impurities. A number of cylinders of commercial oxygen made by the liquid air process were analyzed and found to contain from 0.01 to 0.3 per cent of hydrogen. Oxygen containing no carbonaceous material and an amount of hydrogen not exceeding 0.01 per cent was con­

sidered to be satisfactory without pretreatment.

Ordinary pharmaceutical capsules (No. 00) were employed.

The ignition wire was pure iron and of No. 34 B. & S. gage. Com­

bustion cups used were made both of platinum and ¡Ilium.

Benzoic acid used in calibrations was obtained from the National Bureau of Standards.

288 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 13, No. 5

g

uCO

o

8 <

Fi g u r e 3.

< >

P ro ced u r e a n d D isc u ssio n The procedure is standard in most respects, and is generally described in the literature.

Calibrations were made using benzoic acid, the heating value of which was based on standards of e. m. f. and resistance main­

tained by the National Bureau of Standards.

The heat units employed in the calculations were the same as those used by Rossini (£2) which are:

1 calorie — 4.1833 in te rn a tio n a l joules =» 4.1850 absolute joules

1 absolute joule — 9.480 X 1 0 “ « m ean B. t. u.

1 calorie per gram — 1.7994 B. t. u. p er pound S a m p l i n g . A considerable saving in time is accomplished by basing calculations on a direct weighing of the sample rather than on a weight of sample burned as calculated from an analysis of the products of combustion.

Jessup (9) has indicated th at calculations on either basis are in close agreement when the sample is obviously com­

pletely burned.

Thin-walled glass bulbs, flattened on two sides to withstand pressure changes, have been used by Richards and Barry (19), Jessup (8, 9), and others. The ad­

vantages of the glass bulbs are th a t no corrections are necessary for the heat of combustion of the sample container, and that no ab­

sorption of moisture from th e a tm o s p h e r e is e n ­ countered. For complete combustion of liquid hydro­

carbon samples enclosed in a container, such as a glass bulb or gelatin capsule, it is necessary th at the container be completely filled with the liquid. This is done to pre­

vent explosions within the oxygen bomb, upon ignition, with consequent scattering of the sample beyond the combustion zone, resulting in incomplete combustion. However, for gasoline samples containing considerable amounts of very volatile hydrocarbons, the use of glass bulbs is not recom­

mended by the authors since, to fill these bulbs completely, it is necessary to heat and cool alternately.

Accurate weights of representative samples of gasolines have been obtained by using gelatin capsules and employing a special technique for filling and sealing. When the capsules are first removed from their sealed container, a heat of com­

bustion determination is immediately made on a composite of several capsules selected in a representative manner in order to establish a correction factor for the capsules. At the same time each of the remaining capsules is weighed, the weight being recorded on a slip of paper inserted witliin the capsule. This procedure eliminates any error in the cal­

culated heat value of the capsule due to change in weight from subsequent moisture absorption.

T h e capsule is sealed b y lig h tly w e ttin g th e p e rim ete r of th e sm aller h a lf w ith w a te r a n a in se rtin g it in to th e o th e r h alf. T h is form s a com pletely sealed capsule w hich is rew eighed before filling w ith th e sam ple. T h e gasoline sam ple, cooled in a n ice b a th , is d ra w n in to a h y poderm ic syringe a n d is th e n in jected in to th e sealed c a p s u le ." T h e a ir is allow ed to escape from th e capsule th ro u g h a sm all pinhole n e a r th e hole m ad e b y th e

m JL

Fi g u r e 2 . Ig n i t i o n Sy s t e m

1 2 3 4 5

F I N A L R EADING D E G R E E S

Ex a m p l e Co r r e c t i o n Ch a r t f o r Be c k m a n n Th e r m o m e t e r

h ypoderm ic needle. W hen th e capsule is com pletely filled th e tw o holes are p referab ly sealed w ith a sm all d ro p of collodion or, w hen sealing sam ples of h ig h v o latility , b y a p p ly in g a sm all gelatin p a tc h w hich has been prev io u sly w eighed w ith th e cap­

sule an d is w e tte d w ith w a te r for sealing. T h e w eig h t of th is w a te r (2 to 3 m g.) is e stim a te d from a n u m b er of co m p arativ e weighings. If collodion is used, a n d is p ro p erly applied, its w eight is negligible.

Where atmospheric conditions of high temperature and humidity are encountered, it is recommended th a t all sample handling be carried out in a room held a t a constant low temperature and low humidity, so th at when cold hydro­

carbon samples are injected into the capsules no moisture condensation onto the capsules is encountered.

S a m p l e I g n i t i o n . The capsule, completely filled with the sample, is suspended by means of the iron ignition wire near the bottom of an illium, stainless steel, or preferably a platinum cup, which is approximately 3.75 cm. (1.5 inches) deep, as shown in Figure 2. Although good combustion can be obtained in a shallow cup, the deep cup gives complete combustion more consistently for samples sealed in gelatin capsules. Various methods have been described by Richards and collaborators (19, 21) to ensure complete combustion of a hydrocarbon sample. However, it has been shown by some investigators (8) th a t complete combustion can be ob­

tained without using any foreign materials as combustion aids. In the work on gasolines it has been found th at un­

burned hydrocarbons and carbon monoxide exist in neg­

ligible quantities whenever the sample burns with no visual carbon formation.

Jessup (8) has recommended using 30 atmospheres of oxy­

gen pressure for complete combustion of hydrocarbons, while Richards and Jesse (21) claimed th at with 35 atmospheres an explosion took place and with 20 atmospheres no car­

bonization occurred. In the experimental work on gasolines various oxygen pressures ranging from 15 to 40 atmospheres were used. I t was found th at the use of a pressure of 30 atmospheres resulted in the most consistent complete com­

bustions.

M e a s u r e m e n t s . T o attain the desired accuracy for gasoline work it is necessary to establish the following tolerances on the measurements involved:

W eights of sam ple and capsule =*=0.1 mg.

W eight of calorim eter w ater =*=0.1 gram T h erm o m eter (bucket) reading =*=0.001° C.

Further, it is recommended th at a sensitive galvanometer be used on the thermocouple circuit shown in Figure 1, so th at

May 15, 1941 A N A L Y T I C A L E D I T I O N 2 8 9 the analyst can control the jacket temperature to within

0.1° C. of the bucket temperature during the temperature rise following ignition of the sample. When obtaining the water equivalent of the calorimeter, by burning standardized benzoic acid, the amount of sample should be such th a t the temperature rise obtained will closely approximate the tem­

perature rise th a t results subsequently when analyzing the gasoline samples.

Banse and Parks (2) report satisfactory results with the use of a Beckmann thermometer, while other investigators (8) employ platinum resistance thermometers for more accurate measurements. In the case of a calibrated Beckmann thermometer much time can be saved by the use of a chart giving the total correction to be added to the nominal tem­

perature difference observed. This total correction, as illus­

trated in Figure 3, includes the scale, emergent stem, and setting factor corrections as calculated on the basis of a Bureau of Standards certificate received with the thermome­

ter. In the construction of the chart the total corrections to be applied to the apparent difference between the starting and final temperatures are calculated for final readings of 2°, 3°, 4°, and 5° a t each of several room temperatures covering the range encountered. The points are joined with straight lines, since an appreciable part of the total correction will be due to errors in the scale graduations which are difficult to estimate a t points not calibrated.

C a l c u l a t i o n s . Corrections to the total observed heat of combustion values are made for the fuse wire consumed and for acids formed by the oxidation of nitrogen and sulfur.

The latter corrections are relatively small for gasoline work, amounting to only 3 to 5 B. t. u. per pound for samples meet­

ing customary specifications for sulfur. The methods to be applied in precision calorimetry for correcting the data to standard states are described in publications of the National Bureau of Standards, particularly by Washburn (29).

The net, or lower, heat of combustion values are the ones usually written into gasoline specifications. These are ob­

tained by correcting the gross values, as determined, for the heat of vaporization of water formed. This is most satis­

factorily accomplished by actually determining the weight

Ta b l e I . Re p r o d u c i b i l i t y o f Re s u l t s

No. Values M axim um D ev iatio n

from A verage A verage Value

% % B. t. u ./lb . gros*

25 100 0 .2 6 20,664

24 96 0 .2 5 20,666

23 92 0 .2 2 20,669

22 88 0 .1 9 20.670

21 84 0 .1 7 20,673

16 64 0 .1 0 20,671

T a b l e II. C h a r a c t e r i s t i c s o p C o n t r o l S a m p l e

« -H e p ta n e L ite ra tu re Value*

Boiling po in t, 0 C. 98 .4 9 8 .4

Freezing po in t, ° C. —9 0 .6 8 —9 0 .6

R efractiv e index, n 2^ 1.38769 1.38777

Specific g ra v ity , d£° 0 .6 8 3 6 0.6 8 3 7

per cent of hydrogen in the gasoline by means of a combustion analysis.

R e s u l t s . Reproducibility of results is exemplified by 25 determinations made on a sample of n-heptane, as shown in Table I.

The n-heptane used had the characteristics shown in Table II.

The values obtained by this method may be compared with those of the National Bureau of Standards, which reported values of 20,731 B. t. u. per pound for a different sample of n-heptane from the same source and 20,714 B. t. u. per pound for pure n-heptane (24). These data indicate th at the errors of the method used result in low values. The authors rec­

ommend, therefore, th a t the procedure be followed closely with the suggestions offered in order to keep the results within 0.2 to 0.3 per cent of the true values.

E stim a tio n , o f H e a ts o f C o m b u stio n

For laboratories th at are not equipped to make this test, or for rapid estimations of heats of combustion, a correlation has been derived to yield reasonable values from other data which may be more readily obtainable. In Figure 4 a linear

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OLEINS 1 _• -AfVUVK

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PER CENT HYDROGEN BY WEIGHT

Fi g u r e 4 . Co r r e l a t i o n o f He a t s o f Co m b u s t i o n w i t h Pe r Ce n t Hy d r o g e n

290 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 13, No 5 function is shown to relate the heats of combustion with

hydrogen content. This correlation has been derived from the literature values for the heats of combustion of pure hydrocarbons boiling in the gasoline range, as given in Table III. The paraffin and aromatic hydrocarbons line up very well, b u t the naphthenes and olefins may diverge consider­

ably. However, for gasolines of usual composition this curve may be applied. In Table IV there is tabulated a comparison of actual heats of combustion on gasolines with values estimated from the correlation in Figure 4.

The hydrogen content of gasolines is not generally deter­

mined by routine petroleum testing laboratories. Thus, in order to determine net heating values it is necessary to em­

ploy some means for obtaining reasonable approximations of the hydrogen content. Sweeney and Voorhies (27) present a correlation of hydrogen content with the average boiling point and gravity. The characterization factor, as given by Watson, Nelson, and Murphy (SO), may also be employed to derive an approximate hydrogen content from readily ob­

tainable inspections.

T a b l e I I I . H e a t s o p C o m b u s t i o n o f P u r e H y d r o c a r b o n s B o i l i n g i n t h e Ga s o l i n e Ra n g e

(Selected values from lite ra tu re )

T a b l e IV. C o m p a r i s o n o f E s t i m a t e d a n d D e t e r m i n e d G asoline

Sam ple

He a t s o f Co m b u s t i o n o f Ga s o l i n e s W eight % of H e a t of C om bustion

H ydrogen D eterm in ed E stim a te d D ivergence

1 15.3 20,430 20,350 - 80

o 15.2 20.460 20,340 - 1 2 0

3 15.1 20,400 20,300 - 1 0 0

4 14.9 20,304 20,240

20,020 - 64

5 14.3 19,988 + 32

6 14.1 20,003 19,980 - 23

7 14.0 19,885 19,950 + 65

8 14.0 19,866 19,950 + 84

9 13.9 19,930 19,900 - 30

10 13.8 19,867 19.S80 + 13

11 13 .6 19,840 19,830 - 10

12 13.4 19,814 19,750 - 64

i3 13.3 19,655 19,720 + 65

14 13.2 19,640 19,690 -f 50

15 12.9 19,581 19,600 + 19

16 12.5 19,499 19,450 - 49

17 12 .5 19,420 19,450 + 30

18 12 .0 19,355 19,310 - 45

19 10 .5 18,732 18,810 + 78

Av\ - 8

M olecu­

lar Boiling H ydro­ H e a t of Combustion® Refer­

H ydrocarbon W eight P o in t gen Gross N et ence

° C. Weight % ° K .. c a l./mole B . L u./lb. B. t. u./lb.

Paraffins

n -P en tan e 72.1 5 3 6 .0 16.77 845.27 21,100 19,515

Isopcntane 72.1 5 2 8 .0 16.77 843.36 21,051 19,466 15

N eopentane 72.1 5 9 .5 16.77 840.61 20,983 19,398 15

n-H exane 86.18 6 8 .8 16.37 1002.4 20,948 19,400 24

2-M eth y lp en tan e 86.18 60 .2 16.37 998.54 20,867 19,319 16

2,3 -D im eth y lb u tan e 86.18 58 .1 16.37 993 .9 20,770 19,222 14

n-H eptane 100.20 9 8 .4 16.10 1149.7 20,664 19,142 T his

2-M ethylhexane

2 ,3 -D im ethylpentane 100.20 9 0 .0 16.10 1148.9 20,650 19,128 p a p er

100.20 89 .7 16.10 1148.0 20,633 19,111 145

2,2,3 -T rim eth y lb u tan e 100.20 8 0 .9 16.10 1147.9 20,631 19,109 14

n-O ctane 114.22 125.6 15.88 1316.4 20,754 19,252 24

2-M eth y lh ep tan e 114.22 117.2 15.88 1306.1 20,591 19,089 u

2.4-D im ethylhexane 114.22 109.9 15.88 1298.4 20,470 18,968 16

2 ,2 ,4 -T rim eth y lp en tan e 114.22 9 9 .2 15.88 1303.40 20,549 19,047 17

n-N onane 128.25 150.7 15.72 1473.4 20.6SS 19,201 24

2-M ethyloctane 128.25 142.8 15.72 1454.1 20,417 18,930 16

2,3-D im ethylheptane

2,2,5-T rim ethylnexane 128 25 140.6 15.72 1458.8 20,483* 18,996 14

128.25 124.1 15.72 145S.8 20,483* 18,996 14

2,2,4,4 - T e tram e th y l-

p entane 128.25 122.3 15.72 1458.8 20,483* 18,996 14

N aphthenes

C yclopentane 70.13 4 9 .5 14.38 7S3.6 20,121 18,761 14

M ethylcyclopentane 84.1 6 7 1 .8 14.38 93 7 .5 20,062 18,702 7

1,2 - D im ethylcyclo-

pen tan e 9 8 .1 8 9 1 .9 14.38 1096.0 20,102 18,742 S

1 - M ethyl - 2 - eth y l-

c y d o p en tan e 112.21 121.0 14.38 1250.4 20,067* 19,707 14

Propylcyclopentane

Cyclohexane 112.21 131.4 14.38 1250.4 20,067* 19,707 14

8 4 .1 6 8 0 .8 14.38 9 3 9 .0 20,095 18,735 25

M ethylcyclohexane 9 8 . IS 100.3 1 4 .3S 1091.4 20,018 18,658 18

1,1 - D im ethylcyclo-

hexane 112.21 119.9 14.38 1242.5 19,939 18,579 13

1,3 - D im ethylcyclo-

hexane 112.21 122.7 14.38 1238.0 19.867 18,507 IS

Ethylcyclohexane 112.21 131.6 14.38 1250.4 20,067* 18,707 14

1,1,3 - T rim cthylcyclo-

hexane 126.23 138.7 14.38 1394.7 19,896 18,536 14

A rom atics

Benzene 78.11 SO. 1 7 .7 5 78 2 .0 18,030 17,298 6

Toluene 92.13 110.8 8 .7 6 93 4 .2 18.261 17,433 14

o-Xylene 106.16 144.0 9.5C 1090.9 18.506 17,608 38

m -X ylene 106.16 139.3 9 .5 0 1090.9 IS,506 17,608 28

p-X ylene 106.16 138.4 9 .5 0 10S7.1 18,441 17,543 28

E thylbenzene 106.16 136.2 9 .5 0 1089.0 18,473 17,575 18

1,3,5-T rim ethylbenzene 120.19 164.6 10.06 1242.8 18,622 17,670 28

1,2,4-T rim cthylbenzene 120.19 109.2 10.06 1239.8 IS ,577 17,625 7

Propylbenzene 120.19 159 5 10.06 1245.7 18,666 17,714 SS

Olefins

Pentene-1 70.13 3 0 .2 14.38 806.78» 20,581e 19,221 26

2-M ethylbutene~2 70.13 3 8.4 14.38 795.7 20,431 19,071 18

H exene-l S4.16 6 3 .6 14.38 963.9* 20,477e 19,117 26

2-M eth y lpen te nc-2 S4.16 6 7 .3 14.38 9 5 0 .8 20,346* 18,986 14

H eptene-1 98.1 8 9 4 .9 1 4 .3S 1120.9* 20,410e 19,050

18,945 26

5 -M ethylhexene-l 9 8 .1 8 S4.7 14.38 1107.1 20,305* 14

Octene-1 112.21 122.5 14.38 1277.9® 20,378e 19,018 26

2,4,4 - T rim eth y lp en -

tene-1 112.21 101.2 14.38 1263.4 20,275* 18,915 14

Nonene-1 126.23 145.3 14.38 1434.9» 20,345e 18,985 26

3 -M eth y lo cten e-l 126.23 136.3 1 4 .3S 1419.7 20,252» 18,892 14

* H eatin g values of liquid h y drocarbons unless designated by

* C alcu lated v alues; considered to be a ccu rate w ithin 1%.

e Values show n are calculated for liquid hydrocarbons.

A c k n o w le d g m e n ts

The authors desire to express their sincere thanks to A. Voorhies, Jr., and J. A. Hinckley for their helpful sugges­

tions.

L ite r a tu r e C ited (1) Andrews, Pogg. A n n ., 75, 27 (1848).

(2) Banse and Parks, J . A m . Chem. Soc., 55, 3223 (1933).

(3) B rooks, “ C hem istry of the Non- Benzenoid H ydrocarbons” , New York, Chemical C atalog Co., 1922.

(4) Dickinson, J . Research Natl. Bur.

Standards, 11, 189 (1914).

(5) E dgar, J . A m . Chem. Soc., 51, 1483, 1544 (1929).

(6) Huffm an, Ibid., 52, 1547 (1930).

(7) Ibid., 53, 3878 (1931).

(8) Jessup, J . Research Natl. Bur. Stand­

ards, 18, 115 (1937).

(9) Ibid., 20, 589 (1938).

(10) Jessup and Green, Ibid., 13, 469 (1934).

(11) Kefflcr, J . A m . Chem. Soc., 56, 1259 (1934).

(12) KcfUer, J . Chem. Phys., 32, 91 (1935).

(13) K harasch, J . Phys. Chem., 29, 625 (1925).

(14) K harasch, J . Research N atl. B ur. Stand­

ards, 2, 359 (1929).

(15) K now lton and Rossini, J . Research Natl. B ur. Standards, 22, 415 (1939).

(16) Nelson, Oü Gas J ., 35, No. 28,46 (1936).

(17) Parks, J . A m . Chem. Soc., 52, 1035 (1930).

(18) Ibid., 52, 4382 (1930).

(19) R ichards and B arry, Ibid., 37, 993 (1915).

(20) Richards and Guckcr, Ibid., 47, 1876 (1925); 51,712 (1929).

(21) Richards and Jesse, Ibid., 32, 268 (1910).

(22) Rossini, Chem. Rev., 18, 233 (1936).

(23) Rossini, J . Research Natl. Bur. Stand­

ards, 6, 1 (1931).

(24) Ibid., 13, 25 (1934).

(25) Rossini, Oü Gas J ., 33, No. 52, 64 (1935).

(26) Rossini and Know lton, J . Research Nalt. Bur. Standards, 19, 342 (1937).

(27) Sweeney and Voorhies, I n d . E n g . Ch em., 26, 195 (1934).

(28) Swietoslowski, J . A m . Chem. Soc., 49, 2478 (1927).

(29) W ashburn, J . Research Nail. Bur. Stand­

ards, 10, 525 (1933).

(30) W atson, Nelson, and M urphy, I n d . Enq. Ch em., 27, 1460 (1935).

(31) W hite, "T h e M odern C alorim eter", A. C. S. M onograph No. 42, New York, Chemical C atalog Co., 1928