Industrial and Engineering Chemistry : analytical edition, Vol. 15, No. 8

INDUSTRIAL ^{a n d} ENGINEERING CHEMISTRY

A N A LYTICA L ED ITIO N

W A L T E R J. M U R P H Y , E D IT O R O IS S U E D A U G U S T 17, 1943 » V O L . 15, NO. 8 9 C O N S E C U T IV E NO. 16

Editorial Assistant: G . Gl a d y s Go r d o n Manuscript Assistant: St e l l a An d e r s o n M ake-up Assistant: Ch a r l o t t e C . Sa t r e

Advisory Board

B. L. Cl a r k e G. E. F. Lu n d e l l R. H. Mü l l e r

T. R Cu n n in g h a m M . G. Me l l o n H. H . Wil l a r d

E D I T O R I A L ... '. . 477

D eterm in atio n of W ax in A s p h a l t ...

Raymond L. Betts and H. D. Wirsig 478

V isco sity o£ So lu tio n s in B ra n c h e d -C h a in P araffin s E. H. McArdle and A. E. Robertson 484

AT-M ethylaniline P o in t of V isco u s P etro leu m Oils . B. W. Geddes, L. Z. Wilcox, and E. H. McArdle 487

D eterm in atio n of Free G o ssypo l in Cottonseed M e al Carl M. Lyman, Bryant R. Holland, and Fred Hale 489

G e rm icid a l Q u a te rn ary A m m o n iu m S a lts in D ilute S o l u t i o n ...M. E. Auerbach 492

D eterm in a tio n of V ita m in Bj (T h ia m in e ) in E x tra c ts and C o n c e n t r a t e s ...

R. A. Brown, Eva Hartzler, Gail Peacock, and A. D. Emmett 494

S u g a r D eterm in atio n in S ta rc h H yd ro lyzates b y Y e a s t F e rm e n ta tio n an d C h e m ica l M e an s . . . . Alfred S. Schultz, Robert A. Fisher, Lawrence Atkin, and

Charles N. Frey 496

G as-A b so rp tio n A p p a r a t u s ...

Luther Bolstad and Ralph E. Dunbar 498

D eterm in atio n o f T e tra eth y lle ad in G asoline . . . Louis Schwartz 499

D eterm in a tio n of T in C o a tin g W e i g h t s ...

G . H. Bendix, W. C. Stammer, and A. H. C arle 501

D eterm in a tio n of M e ta llic C opp er an d C u p ro u s Oxide in C o m m e rcia l C u p ro u s Oxide P ig m e n ts .

Irvin Baker and R. Stevens G ibbs 505

D eterm in atio n of B u tad ien e in Presence o f O ther U n sa tu ra te d and S a tu ra te d G aseous H ydro carbo n s

J. F. Cuneo and R. L. Switzer 508

D eterm in atio n of Iron in W ater

Francis J. Hallinan 510

C o n ce n tra tio n of H afn iu m . P rep aratio n o f H a f­

n iu m -F re e Z i r c o n i a ...Edwin M. Larsen, W. Conard Fernelius, and Laurence L. Quill 512

D eterm in atio n of So d iu m in Presence of M o ly b ­ d en u m ...C. H. Hale 516

A n a ly sis of C o m m ercial Oil E m u lsio n s and W ax D ispersions . Frank M. Biffen and Foster Dee Snell 517

Polaro grap hic A n a lysis of C opp er an d Z in c in Brass P late . . . . Willard P. Tyler and Walter E. Brown 520

W ater T h e r m o r e g u l a t o r ...Wm. E. Boyd 523

C alib ratio n of P h otoelectric C o lo rim eter fo r D e­

te rm in a tio n of C h lo r o p h y ll...

C. L. Comar, Erwin J. Benne, and E. K. Buteyn 524

M I C R O C H E M IS T R Y :

Q u a n tita tive C h e m ica l M icro d eterm in atio n of Tw elve E le m e n ts in P la n t T issu e . R. Q. Parks,

S. L. Hood, Charles Hurwitz, and G. H. Ellis 527

Id en tificatio n of O rganic B ases b y M ean s of O p tical Properties of D ilitu rates (N itrob arb i- tu rate s) . . Elmer M. Plein and Bartlett T. Dewey 534

N E W E Q U I P M E N T ...537

B O O K R E V I E W S ...540 T he American Chemical Society assumes no responsibility for the statem ents and opinions advanced by contributors to its publications.

29,300 copies of this issue printed. C opyright 1943 by American Chemical Society.

Published b y th e American Chemical Society a t E aston, Penna. E di­

torial Office: 1155 16th Street, N. W ., W ashington 6, D. C.; telephone, Republic 5301; cable, Jiechem (W ashington). Business Office: American Chemical Society, 1155 16th S treet, N. W „ W ashington 6, D. C. A dvertis­

ing Office: 332 W est 42nd S treet, New Y ork 18, N. Y .: telephone, B ryant 9-4430.

E ntered as second-class m a tte r a t th e P o st Office a t E aston, Penna., under th e A ct of M arch 3, 1879, as 24 tim es a year— Industrial E dition m onthly on th e 1st, A nalytical E dition m onthly on th e 15th. Acceptance for mailing a t special ra te of postage provided for in Section 1103, A ct of October 3, 1917, authorized Ju ly 13, 1918.

R em ittances and orders for subscriptions and for single copies, notices of changes of address and new professional connections, and claims for missing num bers should be sent to th e American Chemical Society, 1155 16th S treet, N. W ., W ashington 6, D . C. Changes of address for the Industrial Edition m ust be received on or before th e 18th of th e preceding m onth and for the

Analytical E dition n o t later th an the 30th of th e preceding m onth. Claims for missing num bers will not be allowed (1) if received more th an 60 days from d ate of issue (owing to th e hazards of w artim e delivery, no claims can be honored from subscribers outside of N orth America), (2) if loss was due to failure of notice of change of address to be received before th e dates specified in the preceding sentence, or (3) if th e reason for claim is “ missing from files".

A nnual subscription— Industrial E dition and A nalytical E dition sold only as a unit, members S3.00, nonm em bers $4.00. Postage to countries not in th e Pan-Am erican Union S2.25; C anadian postage $0.75. Single copies—

current issues, Industrial E dition $0.75, A nalytical E dition $0.50; back num bers, Industrial E dition $0.80, A nalytical E dition prices on request;

special rates to members.

T he American Chemical Society also publishes Chemical and Engineering News, Chemical Abstracts, and Journal of the American Chemical Society.

R ates on request.

4 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

C ^orn JING

---moans---

Research in Glass

. _ J _a n y

of the marvels of science th a t are today p art of our daily lives were literally “born in a three neck flask.”

From this simple distilling flask and other items of Pyrex Labora­

tory Glassware have sprung such modern miracles as the Synthetic Fibres th a t replace silk . . . High Octane Gas for aviation . . . Sulfa Compounds with their new and faster healing power . . . Plastics . . . Synthetic Rubber . .. Solvents . . . Explosives . . . Anti-Freeze Com­

pounds . . . and a host of other scientific accomplishments.

Corning Research shares America’s pride in these laboratory vic­

tories, because of its part in constantly improving the tools of science.

Balanced Pyrex brand Laboratory Glassware—fabricated from Chemical Glass No. 774, for all-round, everyday laboratory use—is typical of the results of Corning Research in Glass. Whether three neck flasks or other types of laboratory glassware, Corning Research pledges itself to their continued betterment. And Corning, in cooperation with laboratory supply dealers, is at the service of every laboratory technician.

T he “ Pyrex” three neck distilling flask has full length, improved sta n d a rd ta p e r ( T ) precision- gro u n d jo in ts w ith cylindrical outer walls and other refinements m ade possible by Corning R e­

search in G lass.. .W rite for f r e e

Book,“The E volution of Standard T ap e r G round Jo in ts.” L abora­

tory and Pharm aceutical Division.

P Y R E X — L A B O R A T O R Y w a r e

11 PYREX'1 and n V Y C O R ,r are registered trade-marks and indicate manufacture 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 E W Y O R K

A N A L Y T I C A L E D I T I O N 5

T h e A R L-D IETER T M u lt is o u r c e U n i t is a n o t h e r o u t s t a n d i n g a d v a n c e m e n t i n t h e f ie ld of s p e c tr o - g r a p h i c e q u i p m e n t .

T h is n e w u n i t c o m b in e s t h e s e n s i t i v e n e s s of t h e a r c w ith t h e a c c u r a c y o f t h e s p a r k . T h u s , it m a t e r i a l l y i m p r o v e s t h e a c c u r a c y a n d w id e n s th e r a n g e o f t h e s p e c t r o m e t r i c a n a ly s i s o f a ll m a t e ­ r ia ls . I m p r o v e m e n t i n a c c u r a c y is o b t a i n e d b e ­ c a u s e t h e e l e c t r i c a l c o n s t a n t s o f i n d u c t a n c e , c a ­ p a c i t a n c e , a n d r e s i s t a n c e m a y b e c l o s e l y s e l e c t e d

a n d c o n t r o l l e d o v e r e x t r e m e l y w id e r a n g e s . T h is m e a n s t h a t t h e e x c i t a t i o n c o n d i t i o n s a r e p r e c i s e l y r e p r o d u c i b l e a n d s e l e c t a b l e s o a s to p r o d u c e e i t h e r v e r y a r c - li k e o r s p a r k - lik e s p e c t r a d e p e n d i n g o n t h e r e q u i r e m e n t s o f t h e m a t e r i a l u n d e r te s t.

A c o n s t a n t c h e c k o n t h e f in e r e p r o d u c i b i l i t y o f th e d i s c h a r g e is a f f o r d e d b y t h e o s c i l l o g r a p h i n c o r ­ p o r a t e d i n t h e u n it.

W r i t e fo r c o m p le t e d e t a i l s o n t h e M u lt is o u r c e U n it.

I E D 4 3 3 6 S A N

R E S E A R C H L A B O R A T O R I E S ' F E R N A N D O RD., G L E N D A L E , C A L IF .

H A 'R R Y W." D I E T É R T C O 5 3 3 0 R O SE L A W N AVE., DETROIT, M IC H

A.R.L

C O N T R

MULTISOURCE EXCITATION UNIT

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

N e w i n a p p e a r a n c e a n d c o n s tr u c tio n , L i n d b e r g L a b o r a t o r y F u r n a c e s m a k e a v a i l a b l e to t h e l a b o r a t o r i e s o f t h e n a ­ t i o n b e n e f i t s o f p e r f o r m a n c e f o u n d o n l y i n t o d a y 's m o d e r n i n d u s t r i a l f u r ­ n a c e s .

NEW!

B y e m p l o y i n g a m o d e r n p r i n ­ c i p le o f s m o o th , " s t e p l e s s " c o n tro l, th e L i n d b e r g I n p u t C o n t r o l g i v e s a n y d e ­ s i r e d d e g r e e o f h e a t w i t h i n t h e t e m p e r ­ a t u r e r a n g e o f t h e u n it, w h i c h r u n s to 2 0 0 0 °F . m a x im u m .

NEW!

C o n v e n i e n t m a n u a l l y o p e r ­ a t e d d o o r m e c h a n i s m , a s u s e d in p r e s ­ e n t d a y p r o d u c t i o n f u r n a c e s , i s p r o ­ v i d e d in t h e v e r t i c a l lift d o o r o f t h e b o x t y p e u n it s h o w n o n t h e o p p o s i t e p a g e . T h e h o t s i d e o f t h e d o o r f a c e s a w a y fro m t h e o p e r a t o r t h e r e b y a d d i n g to h i s c o m f o r t in h a n d l i n g w o r k i n a n d o u t o f t h e f u r n a c e .

NEW!

R u g g e d h e a t i n g e l e m e n t s of t h e lo w v o l t a g e t y p e p e r m i t h ig h e r o p e r a t i n g t e m p e r a t u r e s w ith l o n g e r life a n d f e w e r r e p l a c e m e n t s . T h e s e e le ­ m e n t s a r e p a t t e r n e d a f t e r t h e t y p e th a t d a i l y s t a n d t h e a b u s e o f h e a v y s c h e d ­ u l e s in p r o d u c t i o n h e a t t r e a t i n g s h o p s .

NEW!

F u r n a c e d e s i g n m a t c h e s a p p e a r a n c e , o t h e r m o d e r n l a b o r a t o r y ^ e q u i p m e n t . T h e n e a t , s t r e a m l i n e d s h a p e c o n t r i b u t e s to t h e h i g h s ta n d ­ a r d o f l a b o r a t o r y c l e a n l i n e s s .

T h e b o x f u r n a c e c o m e s i n tw o con­

v e n i e n t s iz e s :

T ype B-2 Type B-6 C h a m b e r width 4>/2" 7 W C h a m b e r d e p th 10" 14"

C h a m b e r height 3" 5"

F O R FURTHER IN F O R M A T IO N SEE Y O U R L A B O R A T O R Y EQ U IP M EN T DEALER

OTHER PRECISIO N UNITS WHICH COMPLETE THE LINE OF LA B O RA TO R Y FU RNA CES A RE THE C O M B U S T IO N TUBE TYPE, CRUCIBLE TYPE A N D HOT PLATES.

A N A L Y T I C A L E D I T I O N 7

Well-known throughout th e w orld a s the lead ers in developing and manufacturing industrial furnaces.

LIN D B E R G E N G IN E E R IN G C O M P A N Y

2 4 5 0 W e s t H u b b a r d S t r e e t * C h ic a g o , 12, Illin o is

8 I N D U S T R I A L Ä N D E N G I N E E R I N G C H E M I S T R Y

The Cenco-Pressovac Pump is ideal for backing up liquid or m er­

cury diffusion pum ps in low pressure systems. It has larg e free air displacem ent . . . 34 liters p e r minute. Tested to attain a vacuum of 0.1 mm or less . . . test data show all pum ps p roduced so far attain m uch lower pressures. W hen com pressed air is re ­ quired this pum p will satisfy the n eed . . . 6 lbs. p e r square inch.

May b e used to circulate or collect gases . . . or to conduct fumes from distillations to vents. D esigned for trouble-free

operation and long service to physicist or chemist.

Low priced for g en eral use. W.P.B. approval is not required. Specify No. 90510A for 115 volts 60 cycle c u r r e n t ...

CENTRAL SCIENTIFIC COMPANY

S C I E N T I F I C I N S T R UME NT S ( T N i f ) L A B O R A T O R Y A P P A R A T U S

RtiMroit

N E W Y O R K T O R O N T O CHICAGO B O S T O N S A N F R A N C ISC O

A N A L Y T I C A L E D I T I O N 9

W a r tim e a c h ie v e m e n ts in science are d e v e lo p in g an e ra o f p ro g re s s w h ic h c h a lle n g e s th e im a g in a tio n .

A ll t h a t S p en ce r is d o in g n o w — p ro ­ d u c in g m ic ro sc o p e s, p e risc o p e s , te le ­ scopes, a ir c r a f t a n d a n t i- a ir c r a f t g u n - s ig h ts , p ris m b in o c u la r s , a z im u th in ­ s tr u m e n ts f o r d ir e c tin g a r ti lle r y fire, t a n k s ig h ts , te le s c o p ic a lid a d e s fo r n a v i­

g a t i o n , p r o je c to r s f o r in s t r u c tio n —w ill r e a p p e a c e tim e re w a rd s in a d v a n c e d k n o w le d g e , b e t te r m a n u fa c tu r in g te c h ­ n iq u e s , finer in s tru m e n ts .

A t th e w a r ’s e n d , S p en ce r w ill be r e a d y to se rv e sc ien tific o p tic a l n ee d s o n a f a r b ro a d e r scale th a n e v e r b efo re .

S p e n c e r

L E N S C O M P A N Y i* B U F F A L O , N E W Y O R K S C I E N T I F I C I N S T R U M E N T D IV IS IO N O F A M E R I C A N O P T I C A L C O M P A N Y

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

TO ASSIST YOU

A r e c o n d i t i o n i n g s e r v i c e f o r P a r r C a lo r im e te r s is i n r e g u l a r o p e r a tio n .

ACCURATE WORKMANSHIP

is a v a i l a b l e to o w n e r s fo r t h e c o m p le t e r e c o n d i ­ tio n i n g o f t h e i r p r e s e n t P a r r e q u i p m e n t .

FOR YOUR BENEFIT

th is r e c o n d i t i o n i n g s e r v i c e h a s b e e n a m p lif ie d to o ffse t t h e i n c r e a s e d d e m a n d f o r N E W P a r r e q u i p ­ m e n t.

PARR BOMB CALORIMETERS and CHEMICAL TESTING APPARATUS

KIMBLE LABORATORY GLASSWARE an alysis and con trol. U sin g standard w ill serve you wherever your p resen t ite m s w here possible m ay be im por- vital produ ction depends on research, ta n t in m in im iz in g delays.

Standardize on

K I M B L E L A B O R A T O R Y G L A S S W A R E

Mold sand and core sand, as well as mate­

rials that go into the cupolas for production of high quality iron castings, must be rigidly examined and controlled by the metal­

lurgist. In the vital w ar metal industries, Kimble Laboratory Glassw are serves in m any types of research and control work.

“ O FFICIAI O.W. I. PHOTO

12 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

H OS K I NS PRODUCTS

where you w ant it— in the w o rk in g zone. . . . The h eating unit is m ade of 7 Ga. Chromel A wire, coiled as show n. There is no refractory mount­

ing. The combustion tube is thus heated by direct contact with the coil. Operates only on A.C. . . . For full description, write to your dealer or us. . . . Hoskins M a n u ­ facturin g C o m p a n y , Detroit 8, M ic h ig a n . This FH-303-A carbon-combustion furnace

has 3 inches of insulation. Compared to the previous model, it uses 1 8 % less power, heats up in one-third less time, and has a case temperature 120° F. cooler (at 2000°

F.), than before. In other words, the heat is

E L E C T R I C H E A T T R E A T I N G F U R N A C E S • • H E A T I N G E L E M E N T A l l O Y S • • T H E R M O C O U P L E A N D L EAD WI R E • • P Y R O M E T E R S • • W E L D I N G WI R E • • H E A T R E S I S T A N T C A S T I N G S • • E N A M E L I N G FI XTURES • • S P A R K P L U G ELECTRODE WI R E • • S P E C I A L A L L O Y S O F N I C K E L • • P R O T E C T I O N TUBE S

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

Exchequer standard W inchester bushel

of Henry VII.,

STANDARD ALL OVER U.S.

W h e re v e r A. R. chem icals are used, M allinckrodt A nalytical R e ­ agents are kn o w n for unquestionable dependability— m ade to p re ­ determ ined stan d ard s of p u rity w hich assure m ore accurate resu lts in gravim etric, gasom etric, colorimetric, or titrim etric analysis.

C atalog of M allinckrodt A nalytical R eagents and other laboratory chem icals yours on request.

A LW A YS SPECIFY REAGENTS IN MANUFACTURER'S ORIGINAL PACKAGES

MALLINCKRODT CHEMICAL WORKS

76 yeaAA. of ¿eSuUce to- chemical uAesiA.

.VICTORY

ST. LOUIS CHICAGO

PHILADELPHIA NEW YORK

MONTREAL LOS ANGELES

U N IT E D S T A T E S W AR

ÎJONDS STAMPS

14 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

S H E P H E R D

G A S A N A L Y S I S A P P A R A T U S

NEW MODEL, W IT H S P H ER IC A L IN TERCH A N G EA BLE GROUND GLASS JO IN TS W ITH NEW TY PE PIN CH CLAM P

3241. r i g . 1 Pinch Clam p for use on spherical Ball - an d - Socket Glass Joints

3241. F ig . 2

Showing m ethod by which spherical glass joints can be quickly and con­

v eniently attach ed or detached by m eans of 3241 Pinch Clam p

G A S A N A L Y S IS A P P A R A T U S , S h e p h e r d V o lu m e tr ic , N e w M o d e l.

Generally similar to No. 5879, as described on page 425 of our cata­

logue but incorporating several important new developments.

Two sizes, w ith interchangeable parts, are offered, i.e., 4-pipette size as in the original apparatus, and 6-pipette size for the more complex types of analyses. The larger size is particularly desirable for fuel gas analysis as it perm its duplicate pipettes for potassium hydroxide and alkaline pyrogallol solutions; one pair for the absorption analysis preceding the combustion and the other pair for the absorption of carbon dioxide and excess oxygen after the combustion. This arrangem ent greatly reduces significant errors arising from the physical solution of various components in these solutions.

T he outstanding improvem ent in the new model is the use of spherical ball-and-socket ground glass joints in place of rubber tubing connections throughout the gas train.

5881-A

The new joints are non-freezing, flexible and interchange­

able. Their use eliminates the necessity for frequent change of rubber tubing because of deterioration and also prevents leakage due to admission of significant am ounts of w ater and loss of gases such as carbon dioxide a t rubber connections.

A new “ A. H . T. Co. Specification” spring-action Pinch Clamp holds the joints securely and can be attached or detached quickly and w ithout danger of breakage.

T he new model also includes an enclosed vertical rheostat which avoids dangers associated w ith th e presence of m ercury vapor caused by accidental spillage on open rheostat wires; a more efficient illuminating device consisting of a 24-inch, 20-watt fluorescent daylight bulb; and a neon pilot lamp which operates directly on 115 volts a. c., eliminating the use of dry cells.

In addition, the burette w ater jacket is sand blasted on the back to facilitate reading of the meniscus, which is sharply defined by a new and simple device which fits over the jacket and, in use, is placed directly below the eye level.

5880-A. G as Analysis Apparatus, Shepherd, N ew V olum etric M odel, 4-plpette, as above described, m ounted on m etal su p p o rt com plete w ith one plain bubbling p ip ette for gases which are easily absorbed, such as carbon dioxide; tw o d istrib u to r tip pipettes with platinum disc per­

forated w ith num erous sm all holes for difficult absorptions; one com bustion p ip ette; b u rette, 100 ml capacity in 0.2 ml, w ith com pen­

sating tube and m anom eter in w ater jack et; and m anifold; all fitted w ith interchangeable No. 12/2 ball-and-socket ground glass joints.

T he outfit also includes sam pling tube, 220 ml capacity; three leveling bulbs, 250 ml capacity; a. c. am m eter; enclosed v ertical rheo­

s ta t; heavy wall n itrom eter tubing for connecting leveling bulb and sam ple tu b e; and im proved illum inating system for reading the b u rette. F o r use on 115 volts, a. c... $350.00 5881-A, D itto, 6-pipette, identical w ith 5880-A b u t w ith tw o extra d istributor tip absorption pipettes and longer m anifold on 6-place m etal support.

F or use on 115 volts, a. ... $410.00 N O T E — E ith er of above outfits can be supplied on special order w ith B u rette of precision bore tub in g a t $22.00 additional.

3241. Pinch Clamp, A. H , T. Co. Specification, No. 12, for use on Spherical Glass Joints size 12/2 as supplied w ith above.

black, corrosion resistan t finish. E a c h ...

10% discount in lots of 12; 15% discount in lots of 72; 20% discount in lots of 144.

Of brass, w ith sm ooth ... $.55

ARTHUR H. THOMAS COMPANY

RE TA IL — W HOLESALE — E X PO 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 .

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 • W A L T E R J. M U R P H Y , E D I T O R

A “ P. S .” from the Editors

A T T H E s u m m e r m e e tin g o f t h e A d v is o r y B o a r d o f t h e An a l y t ic a l Ed i t i o n o f In d u s t r i a l a n d

En g i n e e r i n g Ch e m i s t r y, a t t e n d e d b y t h e e n t ir e m e m ­ b e r s h ip o f t h e b o a r d , a n u m b e r o f s u g g e s tio n s w e re o ffe re d a n d d is c u s s e d , d e s ig n e d t o im p r o v e t h e s e rv ic e r e n d e r e d t h e r e a d e r s o f t h i s p u b lic a tio n .

I n t h e f u t u r e , a u t h o r s m u s t s u p p ly a b s t r a c t s o f t h e i r p a p e r s i f s u c h m a n u s c r ip ts a r e lik e ly t o fill m o re t h a n o n e p r i n t e d p a g e . F u r t h e r , (1) e a c h a r ti c le s h o u ld in ­ c lu d e a s t a t e m e n t o f t h e r a n g e o f a p p l ic a b ili ty o f t h e s u g g e s te d m e t h o d ; (2) in te r f e r e n c e s a n d in te r f e r in g s u b s ta n c e s s h o u ld b e lis t e d ; a n d (3) w h e r e p o s s ib le t h e p r e c is io n a n d a c c u r a c y o f t h e m e th o d s h o u ld b e g iv e n .

W e q u o t e f r o m “ A N o t e t o A u t h o r s ” , o r ig in a lly p u b ­ lis h e d i n J a n u a r y , 1937, w h e n t h e An a l y t i c a l Ed i t i o n

w a s e s ta b l is h e d o n a m o n t h l y r a t h e r t h a n a b im o n t h ly b a s is :

T he author should distinguish carefully between precision and accuracy. Briefly b u t somewhat roughly stated, accuracy is a m easure of degree of correctness; precision is a measure of re­

producibility. The precision of a result does not necessarily have anything to do w ith its accuracy; it serves merely as a m easure of th e duplicability of th e procedure in th e hands of a given operator. No claim for accuracy should be m ade un ­ less th e author believes th a t he has satisfactorily established th e correct result.

B e g in n in g w i t h t h i s is s u e n e w m o n t h l y f e a tu r e s a r e t o b e a d d e d — th e y m ig h t m o r e p r o p e r ly b e d e s ig n a te d a s d e p a r t m e n t s . O n e w ill b e t i t l e d “ N o te s o n A n a ly tic a l P r o c e d u r e s ” , a n o t h e r , “ B o o k R e v ie w s ” , a n d a t h ir d w ill r e p o r t n e w s c ie n tific a p p a r a t u s a n d la b o r a to r y e q u i p m e n t . I n a d d i tio n , f r o m tim e to tim e n e w s ite m s p e r t i n e n t t o t h e a n a ly ti c a l fie ld w ill b e p u b lis h e d , a s , fo r e x a m p le , o n e in t h i s is s u e d e a lin g w i t h p r io r itie s o n la b o r a t o r y m a te r ia ls .

A t t h i s p o i n t i t m i g h t b e w ell t o s t a t e t h e f u n d a ­ m e n t a l p u r p o s e o f t h e An a l y t i c a l Ed i t i o n:

1. To publish fundam ental chem istry of analysis and analytical methods.

2. To publish applied analytical methods.

I t w a s th e c o n s e n s u s o f o p in io n o f t h e e n t ir e A d v is o ry B o a r d t h a t lo n g p a p e r s in h ig h ly sp e c ia liz e d field s s h o u ld n o t b e p u b lis h e d ; b u t in t h e i r p la c e a b s t r a c t s o r r e la tiv e ly s h o r t d ig e s ts . H o w e v e r, e x c e p tio n s w ill b e m a d e w h e r e s u c h s p e c ia liz e d a r tic le s a p p ly t o field s in w h ic h a re a s o n a b le n u m b e r o f t h e r e a d e r s o f th is p u b lic a t io n a r e a c tiv e ly e n g a g e d a n d w o u ld , th e re fo r e , fin d s u c h a r tic le s o f g r e a t p r a c t i c a l v a lu e in th e ir w o rk . H e r e e d i to r ia l d is c r e tio n w ill, o f c o u rs e , b e c a re f u lly e x e rc ise d .

I n c o n c lu s io n , t h e e d i to r s w is h t o p o i n t o u t t o a u t h o r s t h e lim ita tio n s n o w im p o s e d o n a ll p u b lic a tio n s in t h e m a t t e r o f p a p e r s u p p lie s . T h e s e a r e p a r t i c u l a r l y s e rio u s in t h e c a se o f s c ie n tific p u b lic a tio n s , lik e th o s e o f t h e Am e r i c a n Ch e m i c a l So c i e t y, w h ic h a r e p la y in g a d i s t i n c t a n d u s e fu l p a r t in t h e w a r e f fo rt b y s u p p ly ­ in g v a l u a b le te c h n ic a l in f o r m a tio n .

I t h a s b e e n s a id t h a t “ B r e v i ty is t h e so u l o f w i t . ” I n d e e d , i t is m u c h m o re t h a n t h a t . C o n c is e n e s s c o n ­ s i s t e n t w ith c l a r ity is a s k e d fo r b y t h e b u s y m e n a n d w o m e n w h o r ig h tf u lly a r e a c c u s to m e d t o lo o k u p o n th e An a l y t ic a l Ed i t i o n a s t h e i r “ te x t b o o k ” o n a n a ly tic a l c h e m is try .

N o t o n ly a r e o u r r e a d e r s b u s ie r t h a n e v e r b e f o re , b u t so a r e th o s e w h o g iv e so w illin g ly o f t h e i r tim e a n d e n e rg ie s in t h e ro le o f re v ie w e rs . T h i s is p a r t i c u l a r l y t r u e a s r e g a r d s t h e m e m b e r s o f t h e A d v is o r y B o a r d w h o a r e c o n s ta n t ly b e in g c a lle d u p o n f o r o p in io n s . A u th o r s s h o u ld a n d m o s t o f th e m d o p r e p a r e m a n u ­ s c r ip ts w ith g r e a t c a r e . T h e r e a r e o n ly v e r y fe w w h o d o n o t.

T h i s is Y O U R p u b lic a t io n . T h e e d i to r s w e lc o m e , in d e e d u r g e y o u t o s u b m i t c o n s tr u c tiv e s u g g e s tio n s a n d c ritic is m s a s t h e y o c c u r t o y o u .

477

D eterm ination o f W ax in A sphalt

R A Y M O N D L . B E T T S AND H . D . W I R S I G1

Esso Lab o rato ries, Process D ivision, S ta n d a rd Oil D evelopm ent C o m p a n y , E liz a b e th , N . J .

W

A X m a y m a teria lly affect th e properties of an asp h alt, and th e m a g n itu d e of th e effect will depend upon th e specific n a tu re of th e wax an d th e a m o u n t present.

A sm all q u a n tity of wax w hich has a stro n g tendency to separate in large cry stals will be decidedly m ore noticeable visually th a n a considerably larger q u a n tity of a m icro­

crystalline or am orphous wax, o r one having a g rea ter solu- bilit3r in th e asp h alt. C onsequently, a reliable procedure capable of ev alu atin g b o th th e ch a racter a n d q u a n tity of wax p rese n t in an asp h a lt is desirable. R ecen t publications (2, 6) of new m ethods on th e d eterm ination of wax in asp h alt suggested th a t th e experience a t th e Esso L aboratories on th e sam e su b ject m ig h t b e of interest.

T h e H olde (4) m ethod or th e H u b b a rd (5) m odification is frequently em ployed, b u t it h a s long been considered u n ­ sa tisfac to ry because of th e belief th a t waxes are destroyed by cracking, w hich results in erroneous conclusions regarding th e q u a n tity an d n a tu re of th e w ax present. T h is belief has been corroborated (7, IS , 15), a n d a tte m p ts to reduce th e error b y lim iting th e tim e of distillation have n o t been p a r­

ticu larly successful. Because of th e lim itations of th e H olde procedure, o th e r m eth o d s ( 1, 9, 10, 12) have been developed b u t none has proved en tirely satisfactory. M aass (S), on investigating various m ethods of tre a tin g th e a s p h a lt to ob tain th e oily co n stitu e n ts p re p a ra to ry to dew axing in 1 to 1 ether-alcohol or b utanone, found th a t acid tre a tin g alone (12), tre a tin g w ith ad so rb en ts w ith or w ith o u t subseq u en t acid treatin g , or acid trea tin g a t elevated te m p eratu re s (10), gave sim ilar resu lts b u t acid tre a tin g followed by d istillation (9) gave low wax yields.

Because of th e conflicting opinions regarding th e m erits of th e various procedures, work w as u n d erta k en to stu d y an d com pare th e various m ethods. T h e problem consisted of tw o p a rts : th e selection of a su itab le solvent in w hich residual ails are soluble an d waxes are relatively insoluble, and th e effect of th e several tre a tin g m eth o d s on waxes an d on th e recovery of th e se waxes w hen added to asp h alt in know n am ounts.

S e l e c t i o n o f S o l v e n t

Ma t e r i a l s. Paraffin wax, 124° F. (51° C.) melting point.

Petrolatum , 160° F. (71° C.) melting point. This petrolatum had a Tag-Robinson color of 15-18 when liquefied and was ob­

tained from 132° F. (55° C.) melting point petrolatum by clay treating in 4 volumes of n ap h th a and allowing to settle a t 70° F.

(21° C.).

Ether, Squibb, U. S. P.

Absolute alcohol A. S. T. M. n aphtha

Trichloroethylene, commercial M ethyl-n-butyl ketone, commercial sec-Butyl acetate, boiling point 111-113° C.

Colombian distillate cylinder oil, 188 viscosity S. S. U. a t 210° F. (99° C.)

Pennsylvania bright stock, 143 viscosity S. S. U. a t 210° F.

(99° C.)- This stock was obtained by centrifuging Pennsylvania cylinder oil in 3 volumes of nap h th a a t —4° F. ( —20° C.).

Ex p e r i m e n t a l. Critical solution tem peratures of waxes were obtained by weighing th e wax in a bottle equipped with a stopper holding a therm om eter. The correct volume of solvent was added and the m ixture warmed until complete solution was obtained. The solution was then cooled slowly with frequent shaking and the tem perature a t which the first sign of tu rbidity appeared was taken as th e point of limiting solubility of th e wax in

- 1 0 0 10 SO 30 4 0 50 60 70 60 90 100 110 135 130 140

C lou d P e i n t - ° F .

Fi g u r e 1. Re l a t io n- b e t w e e n Te m p e r a t u r e a n d So l u b il it y o p 124° F . (51° C.) Me l t i n g Po i n t Wa xi n Va r io u s So l v e n t s 1 Present address, U. S. Army.

Ta b l e I . Cl o u d Po i n t so f So l u t io n s o f Wa x e s i n Va r io u s So l v e n t s ix M elting

P oint Solvent Used 2 .5 1.25 0.625 Concentration of Solution (G ram s per 100 Ml. of Solvent)

0 .4 0 .2 5 0 .2 0 0 .1 0 0.0625 0 .0 4 0 .0 3 2 0 .0 2 0 0.016 0.010 O O 0 01

° F. ° F. o F: F. 0 F. 0 F. ° F. ° F. ° F. “ F. 0 F. O O

0 F. 0 F.

124 sec-Butyi acetate S3 15 66 55 33 30 20 8 - 8

M ethyl-n-butyl ketone 82 74 66 55 35 30 20 9 - 8

3 to 1 ether-alcohol 79 71 64 51 25 16 5 - 6

A. S. T . M . n a p h th a 46 26 19 - 3 - 1 1

Trichloroethylene 40 *3i ‘¿3 15 '& - 2 - 1 4

tro la tu m )a160 sec-Butyl acetate 131 121 110 98 SO 68 64 59 54 44

M ethyl-n-butyl ketone 130 120 111 97 82 '75 68 65 58 55 46

A. S. T . M . n a p h th a 91 •

. «

^{62 40 38 27 24 15 10}

Trichloroethylene 79 70 '¿ i 54 46 '36 20 12 3

° Solutions of 160° F. M . P. p etro latu m in 3 to 1 ether-alcohol could be obtained only a t very low concentrations.

478

A N A L Y T I C A L E D I T I O N 479 the solvent. Cloud points of the cylinder stocks and of wax-oil

mixtures in each solvent were obtained in a similar m anner, the weight of oil or wax plus oil being 2.5 grams per 100 ml. of solvent in all cases.

Re s u l t s. T h e cloud p o in ts of solutions of waxes in v arious solvents, containing th e waxes in vary in g con­

ce ntrations, are show n in T ab le I a n d illu strate d graphically in F ig u res 1 an d 2. T hese curves in d icate th a t th e re is a sem ilogarithm ic relationship betw een te m p e ra tu re a n d wax solubility a t te m p e ra tu re s above 50° F . (10° C.) as re­

p o rted in th e lite ra tu re , b u t a t lower te m p eratu re s th e re is a d istin c t deviatio n from lin earity . T h ere are no appreciable differences in th e solubility of 124° F . (51° C.) m elting p o in t wax in 3 to 1 ether-alcohol, m e th y l-« -b u ty l ketone, a n d sec- b u ty l a c etate , b u t 160° F . (71° C.) m eltin g p o in t petroleum is m uch less soluble in th e first so lv e n t th a n in th e others.

All th re e solvents show m uch less solvent pow er for wax th a n trichloroethylene or A. S. T . M . n a p h th a . A lthough solubility d a ta using 1 to 1 ether-alcohol w ere n o t obtained w ith these p a rtic u la r wax sam ples, o th e r experim ents showed th a t waxes are even less soluble in th is m ix tu re th a n in a n y of the o th e r solvents.

C ylinder oils (T able I I ) are n o t p a rtic u la rly soluble in trichloroethylene a n d relativ ely insoluble in 1 to 1 e th e r al-

Ta b l e II. Mi s c i b i l i t y Te m p e r a t u r e s o p De w a x e d Oi l s i n Va r io u s So l v e n t s i n 2.5 Pe r Ce n t Co n c e n t r a t io n

143 S. S. U. Vis­ Colom bian 188 S. S. U*

cosity 210° F . Penn.

B rig h t Stock Viscosity 210° F.

Solvent D istillate

° F . ° C. o

Fm

_{° C.}

M e thyl-n-butyl ketone - 3 0 - 3 4 . 4 - 4 0 - 4 0 . 0 3 to 1 ether-alcohol — 40 - 4 0 . 0 - 3 5 - 3 7 . 2

sec-Butyl acetate - 2 5 - 3 1 . 7 - 3 0 - 3 4 . 4

A. S. T . M. n a p h th a

1 to 1 ether-alcohol — 25 - 3 1 . 7 - 4 0 - 4 0 . 0 25% insoluble a t

room tem perature + 30 - 1.1

Trichloroethylene 20 - 0 .7 + 20 - 6 .7

C loud P o i n t - * F .

F i g u r e 2. R e l a t i o n b e t w e e n T e m p e r a t u r e a n d S o l u b i l i t y o f 160° F . (71 ° C .) M e l t i n g PorN T

P e t r o l a t u m i n V a r i o u s S o l v e n t s

Ta b l e I I I . De wa x in g Di f f e r e n t i a l 160° F . M . P.

M ethyl-n-butyl ketone 3 to 1 ether-alcohol scc-Butyl acetate A. S. T . M .n a p h th a T richloroethylene

124° F. M. P . W ax P e tro la tu m

Versus Versus

Versus Penn. Versus Penn.

Colombian b right Colombian b right

distillate stock d istillate stock

° F. ° F. ° F. o

K

122 112 170 160

114 119

113 108 i é i i56

86 71 131 110

20 20 59 59

cohol, showing th a t th e la tte r solvent is n o t su itab le for th e separation of wax from oil. T h e o th e r solvents stu d ied show com paratively high solvent pow er for oils, a n d differ from one an o th er only slightly.

T he “ dewaxing differentials” w hich rep rese n t th e dif­

ferences in degrees F ah ren h e it betw een th e cloud p o in ts of solutions of th e wax an d of th e oil, each p rese n t in a con­

c e n tratio n of 2.5 gram s p er 100 m l. of solvent, are recorded in T ab le I I I . M e th y l-n -b u ty l ketone, .sec-butyl ac etate , an d 3 to 1 ether-alcohol exhibit relatively high dew axing differ­

en tials of approxim ately th e sam e m ag n itu d e and ap p e ar to be th e m o st effective solvents for dewaxing oil-wax m ixtures.

Of th ese three, th e ether-alcohol is th e least desirable m ixture because of its high volatility , w hich m akes it difficult to o b ta in solutions of high m elting waxes in reasonable con­

cen tratio n . T h e presence of cylinder oils does n o t a p ­ preciably affect wax solubility, since th e cloud p o in ts of solutions of oil-wax m ixtures (Table IV ) are su b sta n tia lly th e sam e as those o b tain ed w hen th e wax alone was p rese n t in th e sam e solv en t in th e sam e concentration (values shown in b rack ets).

T hese resu lts indicated th a t either m eth y l-n -b u ty l ketone or sec-butyl a c e ta te w ould be sa tisfac to ry for separation of wax from oil.

In order to confirm this conclusion, varying quantities of 124° F. (51° C.) melting point wax were mixed with sufficient 188 S. S. U. viscosity a t 210° F. (99° C.) Colombian distillate to give 1.0-gram samples of wax plus oil. The mixtures were then

Ta b l eIV. Cl o u d Po in t so f So l u t io n so f Oi l- Wa x Mi x t u r e s i n Va r io u s So l v e n t s

(In all cases solutions contained 2.5 gram s of oil plus wax per 100 ml. of solvent)

W ax in M ixture

%

0 5 10 25 50 100

5 10 25 10050

05 10 25 50 100

124'

’ F.

M. P. Wax

° F. ° F.

■Cloud P o in ts“ -

160° M . P . P etro latu m F.

Solvent, M ethyl-n-B utyl K etone -4 0

43 53 64 73

54 (45) (55) (66) 74)

82 93 110 120

42 52 65 71

Solvent, sec-Butyl A cetate - 3 0

(45) (55)(66) (74) S3

80 92 108120

F.

- 4 0

130

-30 F.

87) (96) (III) ( 120)

(86) (110(96)) ( 121)

Solvent, 3 to 1 Ether-A lcohol - 3 5

42 (41)

52 (51)

64 (63)

71 (71)

79

-3 5

» Figures in parentheses are cloud points of sam e wax in sam e concentra­

tion in solvent, b u t free from oil.

480 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

T Vb l e V. Wa x Re c o v e r y

(From m ixtures of 124° F. M. P. wax and 188 S. S. U. viscosity a t 210° F.

Colombian d istillate in m ethyl-n-butyl ketone) W ax in 1.0

G ram of — Recovered W a x - ---— >

M ixture Yield M elting point

Gram % ° F.

1.00 98 125

0 .50 101 123

0 .25 108 127

0 .10 98 127

0.05 101 125

Ta b l e V I . Ef f e c t o f Ad s o r b e n t o n Wa x Yi e l d b y t h e Sc h w a r z Me t h o d

C rude Oil

Sample W ax

-N uchar---*

E xtraction tim e

Bone C har (Fat-Free) E x tractio n

W ax tim e Filtrol

Wax

% Hours % Hours %

1 0 .19 18 2 .12 24 7.55

2 0 .22 18 2 .85 5 11.45

3 0 .98 4 5.41 5 11.03

4 0 .17 18 3.21 24 9.27

dewaxed in 10 ml. of m ethyl-n-butyl ketone a t —4° F. ( —20° C.) by a procedure essentially the same as th a t described by H ub­

bard (5).

T h e resu lts o b ta in ed a re given in T ab le V a n d in d ic ate th a t waxes can be recovered su b sta n tia lly unchanged w ith a precision of ± 5 p er cent.

S ch w a rz M e th o d

Follow ing th e selection of solvents suitable for th e separa­

tion of w ax from oil, a n exam ination was m ade of th e Schw arz (10) m eth o d to determ ine th e effect of th e n a tu re of th e a d ­ so rb en t on wax yield an d th e effect of stro n g sulfuric acid on refined waxes a t elevated tem p eratu res.

Samples (10 grams) of various waxy crudes were digested a t 350° F. (177° C.) w ith 96 per cent sulfuric acid until free from the odor of sulfur dioxide. The resulting coke was mixed with 35 grams of fat-free bone char, as recommended, or of Nuchar, and extracted in a Soxlilet with 400 ml. of 86° Bé. nap h th a until a few drops of extract showed practically no evidence of oil after evaporation on a w atch glass. In other cases, th e coke was

E

laced on a Gooch filter 4 cm. in diam eter containing 10 grams of ltrol which had been dried for 16 hours a t 225° F. (107° C.) and washed w ith 250 ml. of 86° Bé. n aphtha. In all cases the re­

sulting oils, free of naphtha, were dewaxed in 20 volumes of 3 to 1 ether-alcohol by the H ubbard procedure.

I t is ev id en t (T able V I) th a t th e n a tu re of th e adso rb en t has a v e ry m ark ed effect on w ax yield an d t h a t excessively long periods of ex tractio n w ould be necessary to se p a ra te th e wax com pletely from th e adsorbent.

T h e higher yields obtain ed w hen th e coke was w ashed on a S uper-F iltrol bed suggests th a t th is procedure is preferable.

L a te r experience, however, d em o n strate d th a t m uch larger q u a n titie s of n a p h th a are req u ired for w ashing th a n are specified here.

T h e effect of stro n g acid on w ax w as stu d ied b y digesting 1.0-gram sam ples of 124° F . (51° C.) m eltin g p o in t paraffin wax a n d 165° F . (74° C.) m elting p o in t p e tro la tu m in 90 per cent sulfuric acid a t 400° F . (204° C .). [This wax was obtained b y crystallizing 160° F . (71° C.) m elting p o in t p e tro la tu m from 4 volum es of sec-butyl a c e ta te a t 30° F.

( - 1 ° C .),] I t was found (T able V II) th a t th e waxes were read ily a tta c k e d u nder conditions com parable to those em ployed in th e Schw arz procedure, p articu la rly in th e case of th e lower m elting wax. In view of these resu lts it ap p ears t h a t th e Schw arz m ethod is unreliable for d eterm ining wax co n ten ts of oils.

A d so r b e n t M e th o d

C laim s are m ade in th e lite ra tu re (1, 8, 1Ą) th a t wax in asp h alts can be o b tain ed by dew axing th e oily c o n stitu e n ts rem aining a fte r tre a tm e n t of th e a s p h a lt w ith adsorbents.

T h e ad so rb e n t m eth o d h as been used in these laboratories to determ ine th e resin co n ten ts of asp h alts a n d it h as been found th a t th e q u a n tity of a d so rb e n t required to give oils of a given color varies considerably w ith th e n a tu re of th e asp h alt. Since th e q u a n tity an d ch a racter of th e ad so rb e n t were also found to hav e a m ark ed effect on wax yield b y th e Schw arz m ethod, te s ts were m ade to determ ine w hether stra ig h t waxes could be recovered a fte r tre a tm e n t w ith a c tiv a te d clay in th e absence of asp h alt.

In order to determine the minimum q u an tity of adsorbent to use, samples of Venezuelan heavy flux were dissolved in 40 vol­

umes of 86° Bć. naphtha, and after separation of asphaltenes were treated with varying am ounts of Super-Filtrol. About 8 to 10 grams of clay per gram of asphalt were required to yield a solution of 20 Tag-Robinson color. Accordingly, 1-gram samples of 124° F. (51° C.) melting point wax and 160° F. (71° C.) m elt­

ing point petrolatum (equivalent to 5 per cent by weight of a 20- gram asphalt sample) were treated in th e absence of asphalt in 800 ml. of 86° B6. naphtha w ith 160 gram s of Super-Filtrol. The clay-wax m ixtures were then extracted in Soxhlet extractors for varying periods of tim e and th e q u an tity and melting points of the waxes recovered were determined. A sample of Venezuelan heavy flux was also trea ted in a similar manner.

Ta b l e V II. Ef f e c t o f St r o n g Su l f u r i c Ac id o n Wa x W axes T reated w ith 1 Cc. of 90% I IjSO« per

G ram of Wax

124° F . M . P . W ax 165° F. M . P. P e tro la tu m

W ax recovery, % 4 1 .2 8 4.9

M. P. of recovered wax,

° F. 132 163

I n th e case of th e recovery of th e waxes from th e Super- F iltro l rem aining from th e tre a tm e n t of th e ir n a p h th a solu­

tions, th e paraffin wax could be effectively recovered b y ex tractin g for 9 hours, alth o u g h a sm all a m o u n t of th e higher m elting waxes rem ained in th e clay. On th e o th e r han d , only a b o u t 55 to 60 per cent of th e high m elting p e tro la tu m could be recovered in a sim ilar tim e a n d it w as b y no m eans com­

pletely se p arate d a fte r 43 h ours’ extraction, th e higher m elting p ortions being th e m o st difficult to rem ove. In th e ex tractio n of th e S uper-F iltrol a fte r decolorization of th e n a p h th a solution of th e asp h alt, it was found th a t th e oily co n stitu e n ts w ere su b stan tia lly , b u t n o t sharply, rem oved afte r ex tra ctin g th e clay for 6 hours (T able V II I ). T he p ro d ­ u cts obtained on longer periods of ex tra ctio n were of resinous n atu re , becom ing increasingly h a rd a n d d a rk in color. I t is a p p a re n t from these results th a t th e ex tractio n tim e of 6 to 16 hours, com m only em ployed in th e ad so rb e n t m eth o d of a s p h a lt analysis, w ould indicate lower m elting a n d sm aller am o u n ts of w ax th a n are ac tu a lly present. Sufficient ex­

tra c tio n to rem ove all wax is im practicable a n d in ad d itio n it is difficult to establish a well-defined end p o in t.

R ic h a r d so n or A c id -T r e a tin g M e th o d

A m eth o d w hich h as been extensively used for th e d e te r­

m in a tio n of w ax in asp h alts (12) involves th e use of sulfuric acid to rem ove resins before dew axing. I n view of th e fac t th a t h o t sulfuric acid readily a tta c k s a n d alters th e p roperties of waxes, it app eared possible th a t cold acid m a y also have some effect. I t was found, however, th a t 1-gram sam ples of 124° F . (51° C.) m elting p o in t paraffin wax a n d 160° F.

(71° C.) m elting p o in t p etro latu m dissolved in 500 m l. of 86° Bé. n a p h th a are unaffected w hen rep eated ly tre a te d w ith