Industrial and Engineering Chemistry : analytical edition, Vol. 9, No. 11

IN D U S T R IA L

Analytical Edition andENGINEERMG

Vol. 9, No. 11 C H E M I S T R Y November 15,1937

Vol. 29, C onsecutive N o. 43

P u b lish ed b y th e A m erican C hem ical Society H arriso n E . Howe, E d ito r

Publication Office: Easton, P a. . Editorial Office: Room 706, Mills Building, Washington, D. C. . Telephone: National 0848 Cable: Jiechem (Washington) . Advertising Departm ent: 332 West 42nd Street, New York, N. Y. . Telephone: B ryant 9-4430

C O N T E N T S

19,000 Copies of This Issue Printed

Electrometric Titration of Acids in Oxidized Petroleum Oils . A. R. Rescorla, F. L. Carnahan, and M . R. Fenske 505 Qualitative Determination of Glycerol and Ethylene

Glycol in Dilute Aqueous S o lu tio n ...

. A . G. Hovey and T. S. Hodgins 509

Determination of Butenes in Refinery G a s e s ...

... Wallace A. McMillan 511 Electromelric T itration of Dicliromate Glycerol Samples

Chemical Division, The Procter <f Gamble Company 514

Extraction of Gossypol with Different E t h e r s ...

.1 .0 . Halverson and F. II. Smith 516

Revised M ethod for the Estimation of Gossypol in Cotton­

seed M e a l ...F. II. Smith 517 Determination of Chromium in C h ro m ite ...

... G. Frederick Smith and C. A. Getz 518 Modified Distillation Method for M o is tu re ...

... II. N . Calderwood and R. J. Piechowski 520 Rapid Saponification of Esters by Potassium Hydroxide

in Diethylene G ly c o l...

... C. Ernst Redemann and Howard J . Lucas 521 Estimation of Riboflavin . S. M. Weisberg and I. Levin 523 Analysis of Crude Phosphorus and Sludges Containing

Phosphorus . Earl H. Brown, Henry II. Morgan, and Eugene R. Rushton 524

Photometric Determination of Added Phosphorus in Oils ...Paul Goodloe 527

Determination of Chlorides and B ro m id e s...

...L. A. Reber and Wallace M . McNabb 529 Determination of Gold and Silver by Recovery of Minute

Amounts from S o lu tio n ...

. . . William E. Caldwell and Kenneth N. M ethod 530 A Noncorrodible Circulating D e v ic e ...

...Kenneth A. Freeman and P. J . Thompson 532 A Piezometer R i n g ...

...Chester P. Iiaker and Albert J. Komich 533 Determination of Silicon in Aluminum (Correspondence) 533 M ICROCHEMISTRY :

Direct Microdetermination of Oxygen in Organic Sub­

stances by Hydrogenation . . . . W. R. Kirner 535 The Determination of Acetyl, Especially in O-Acetyl

C o m p o u n d s... E. P. Clark 539 The Kauri Butanol Test for Solvent Power. II . . .

. . . . E. L. Baldeschwieler, M. D. Morgan, and W. J. Troeller 540

Determination of Small Proportions of Sulfur by a Modification of the A. S. T. M. Lamp Method . . .

... Viclor Zahn 543 A Modification of the A. S. T. M. Lamp Sulfur Method

for Refined K ero se n e s...

...Edward Field and Fred II. Dempster 547

T h e A m erica n C h e m ica l S o c ie ty a ssu m es n o r e sp o n sib ility for th e sta te m e n ts an d o p in io n s a d v a n c e d b y co n trib u to rs to it s p u b lic a tio n s.

P u b lish e d b y th e A m erican C h em ical S o c ie ty , P u b lica tio n Office, 20th &

N o r th a m p to n S ts., E a s to n , P a . E n tere d as seco n d -cla ss m a tter a t th e 1 ost Office a t E a s to n , P a ., u nd er th e A c t of M arch 3, 1879, as 4 8 tim es a year.

In d u stria l E d itio n m o n th ly on th e 1 st; A n a ly tica l E d itio n m o n th ly on th e 15th ; N ew s E d itio n on th e 10th and 2 0 th . A c cep ta n ce for m a ilin g a t special ra te of p o sta g e p ro v id ed for in S e c tio n 1103, A c t of O ctober 3 , 1917, au thor­

iz e d J u ly 13, 1 918. „ __ . .

A nn u al su b scrip tio n ra tes: (a) In d u s t r i a l Ed i t i o nSo.00; ( i> )An a l y t i­ c a l Ed i t i o n $ 2 .00; (c) Ne w s Ed i t i o n S I .50; (a) an d (6) to g eth er, so .u u .

(a ), (6 ), an d (c) c o m p le te, $ 7 .5 0 . F o reig n p o sta g e to co u n tries n o t in th e P a n A m erican U n io n , (a) $ 1 .2 0 ; (6) $ 0 .3 0 ; (c) $ 0 .6 0 ; to C a n a d a o n e-th ird th e se rates. S in g le c o p ies: (a) $ 0 .7 5 ; (6) $ 0 .5 0 ; (c) $ 0 .1 0 . S p e cia l ra tes to m em bers.

C la im s for c o p ies lo s t in m a ils t o b e h o nored m u st b e re ce iv e d w ith in 60 d a y s of d a te of issu e an d b a sed on reason s o th er th a n “ m issin g from files."

T en d a y s ’ a d v a n c e n o tice of ch a n g e of ad dress is requ ired . A d d re ss C harles L. P arson s, B u sin ess M a n a g er, M ills B u ild in g , W a sh in g to n , D . C ., U . S . A:

4 INDUSTRIAL AND E N G IN E E R IN G CHEM ISTRY VOL. 9, NO. 11

The

BEC K M A N pH M E T E R

has attained Leadership in the Glass Electrode Field

2 .

4.

BECAUSE:

1. I t h a s m a n y im p o r ta n t featu res n o t available on o th er pH m eters, su c h as:

(a) Sturdy electrodes (b) S en sitiv ity o f 0.01 pH

(c) A ccurate tem p era tu re co m p en sa tio n (d) C om p lete electr o sta tic sh ield in g

(e) C o n tin u o u s in d ic a tio n o f p o te n tio m e te r u n b a la n ce

(f) W ide se le c tio n o f electrod es, developed for u n u su a l a p p lica tio n s

It w as developed by a w ell rou n d ed te c h n ic a l organ ization w ith excep tion al fa c ilitie s for sci­

en tific research.

3. I t is m ad e according to th e b e st k n ow n m e th o d s o f precision m a n u fa ctu rin g .

I t is sold by th e lea d in g laboratory a p p aratu s dealers, w h o m a in ta in tec h n ic a l staffs for co n - su lta tio n and servicing.

I t is o u r i n t e n t i o n t o m a in t a in t h e p o s it io n o f le a d e r s h ip th r o u g h a c o m p r e h e n s iv e p r o g r a m o f r e s e a r c h a n d d e v e lo p m e n t. A s a p r o d u c t o f th is y e a r ’s p r o g r a m , w e s h a ll s o o n m a k e a v a ila b le a n IN D U S T R IA L M O D E L o f t h e B E C K M A N pH M E T E R w h ic h h a s b e e n d e v e lo p e d for c o n v e n ie n t

u s e in t h e fa c to r y a n d c o n tr o l la b o r a to r y . T h e p r e s e n t s ta n d a r d B E C K M A N pH M E T E R w ill h e n c e f o r t h b e c a lle d t h e L A B O R A T O R Y M O D E L a n d th r o u g h c o n t in u a l im p r o v e m e n t w ill b e m a in t a in e d a s t h e o u t s t a n d in g p H m e te r fo r r e ­ se a r c h a n d g e n e r a l la b o r a to r y w o r k .

S e e the B E C K M A N p H M E T E R S a n d accessories in Booth 5 1 5 at the Chem ical E xp o sitio n , D e c e m b e r 6th to 11th, N e w Y o rk City. Bring samples for testing if you wish without any obligation im plied.

N A T I O N A L T E C H N I C A L L A B O R A T O R I E S

3325 E. COLORADO STR E ET PA SA D EN A , CALIFORNIA

NOVEM BER 15, 1937 ANALYTICAL E D ITIO N 5

KIMBLE GLASS COMPANY • • • • v i n e l a n d , n . j.

N E W Y O R K * * C H I C A G O • • P H I L A D E L P H I A • • D E T R O I T • • B O S T O N T h e r e c o r d o f A m erican h e a lth a n d lo n g e v ity is an en viable

o n e — a n d th e p o w e r b e h in d th is p h y sical w elfare o f th e n a tio n is th e m o d e rn A m erican h o s p ita l a n d 165,000 p ra c tic in g p h y s i­

cians. O v e r 7,0 0 0 h o sp ita ls in th e U n ite d S tates, w ith a m assed p u rc h a s in g p o w e r o f $ 8 6 4 ,0 0 0 ,0 0 0 a y e a r— w ith b u ildings, e q u ip m e n t a n d in v e s tm e n ts ra te d a t o v e r $ 3 ,0 0 0,000,000 — a n n u a lly tr e a t m o re th a n 7,000,000 p a tie n ts a n d d eliv e r o v e r 7 7 0 ,0 0 0 b a b i e s !

In to th is v a s t sy ste m o f clinical research , scien tific d e v e lo p ­ m e n t, u n e rrin g d iag n o ses a n d tre a tm e n t, K im ble L a b o ra to ry G la ssw a re h as m a d e fo r itse lf a p e rm a n e n t niche. W h e th e r in th e m e d ic a l w o rld o r in th e la b o ra to rie s o f in d u s try , BLUE L IN E EX A X G la ssw a re b rin g s in d isp u ta b le a c c u ra c y th a t m eans a s s u ra n c e — b rillia n t BLUE L IN E c a lib ratio n s t h a t m ean sp e e d o f d e te rm in a tio n s — a n d stra in -fre e , an n ealed s tre n g th th a t m ean s s a fe ty th r o u g h critical, 2 4 -h o u r-a -d a y service.

E q u ip y o u r la b o ra to ry a n d rese a rc h d e p a rtm e n t w ith K im ble BLUE L IN E EXAX w are . . . fo r A SSU R A N C E !

Pi <ÜÄx> Ö K ^

KT.TTT?

L I N E

Stocked by leading Laboratory Supply Houses throughout United States and Canada

V I S I T T H E K I M B L E B O O T H S

# 3 4 2 - 3 4 3 AT T H E C H E M I C A L I N D U S T R I E S E X P O S I T I O N G r a n d C e n t r a l P a l a c e , N e w Yor k C i t y , D e c e m b e r 6 t o 11, 1 9 3 7

T h e V i s i b l e G u a r a n t e e o í I n v i s i b l e Q u a l i t y

6 INDUSTRIAL AND E N G IN E ER IN G CHEM ISTRY VOL. 9, NO. 11

“ Cenco H yvac” is a n a m e fa m ilia r to sc ie n tists o f m a n y languages in every corner o f th e globe. I t is th e u n iver­

sal laboratory vacu u m p u m p by rea­

son o f an u n ch angin g an d th o ro u g h ly acceptable perform an ce.

T H E C E N C O H Y V A C PUMP

R O T A R Y OIL-SEALED HIGH-VACUUM PUMP

Laboratory m en prefer th e Hyvac for its sm a ll size and ready p o rta b ility , its co m p le te freed om from a d ju stm e n ts or repairs, its fa st a ctio n and its cer­

ta in a b ility to produce pressures of th ree te n th s of a m icron or less. In p rod u ction d u ty for th e in d u s ­ tries th e H yvac h a s proved its a b ility to deliver c o n tin u o u s service alon g w ith o th er p ro d u ctio n m a ­ ch in ery w ith n o in ter ru p tio n of sch ed u le. T h is to th e laboratory worker is th e assu ran ce of in v estin g in a p u m p th a t w ill yield th e sa m e fa ith fu l per­

form an ce for m a n y years to com e.

91105A For 110 v o lts A.C. $75.00

S CI ENT I F I C LABORATORy

INSTRUMENTS A P P A R A T U S

New York • Boston • C H I C A G O • Toronto • Los Angeles

Vacuum

0.3

m icron

o r

b etter

NOVEMBER 15, 1937 ANALYTICAL ED ITION 9

A p p ro x . trn/cih o f ja c k e t, m m .

Q u a n tity r c r Pkg.

N et P rice Each

N E T 1 t'kn.

I> 11 I C E 25 r k t ».

I> E R 1’ A C K A G E 50 Pkfis. 100 Pkg*.

200 12 $1.60 SI 7.28 $16.42 $15.55 $14.69

250 12 1.65 17.82 16.93 16.04 15.15

300 12 1.70 18.36 17.44 16.52 15.61

400 12 1.85 19.98 18.98 17.98 16.98 ’

500 9 2.00 16.20 15.39 14.58 13.77

600 9 2.20 17.82 16.93 16.04 15.15

750 9 2.55 20.66 19.62 18.59 17.56

" P Y R E X ” is a registered trade-mark and indicates manufacture by

C O R N IN G GLASS WORKS • C O R N IN G , N . Y.

“ Corning M eans Research in Glass”

G R E A T E l l E F F I C I E N C Y L O W E R P R I C E S

T h e hig h cooling efficiency of W est type condensers is generally recognized b y chem ists.

W e now offer a com plete line o f new a n d im proved “ Py r e x” B ran d W est ty p e condensers w hich em body these d istin ctiv e featu res:

1. E n larg em en ts in o u te r ja c k e t a t p o in ts o f ta b u la tio n — for strength.

2 . H e a v y o u te r ja c k e t an d light walled, p ro p erly cen tered in n er tu b e — for durability a n d efficiency.

:t. M in im u m am o u n t o f space betw een o u te r ja c k e t and in n er lube

— for compactness a n d speedy performance.

4

.

T u b u la tu re s on sam e side o f ja c k e t— for convenience.

F a b ric a te d in o u r A p p a ra tu s D ep a rtm e n t, these new condensers c a rry th e “ Py r e x” tra d e -m a rk — y o u r g u a ra n te e o f ex p e rt w ork­

m a n sh ip a n d co rrect annealing.

“ Py r e x” b ra n d im proved W est ty p e condensers (C atalo g N o. 1290) a re av ailab le th ro u g h y o u r reg u lar lab o rato ry su p p ly dealer, a t new low prices, in d ic a te d below. Please n o te th a t these condensers in original p ackage q u a n titie s m a y be com bined w ith selections from o u r reg u lar la b o ra to ry glassw are catalog in m aking u p q u a n tity orders of 25, 50 or 100 original packages.

Always look for the circular trade-mark

“ P Y R E X ” when buying laboratory glassware.

PYREX

See our Exhibit—

16th Exposition of Chemical Indus­

tries, Grand Cen­

tral Palace, New York C ity— Dec.

6th to 11th.

I M P R O V E D D E S I G N

10 INDUSTRIAL AND EN G IN E ER IN G CHEM ISTRY VOL. 9, NO. 11

LABORATORY SMELTING DIVISION Chicago Vitreous Enam el Product Co.

Lusterlite P o r c e la in En­

am els a r e th e result of scientific research of c e ­ ramic m aterials, m ethods and products. In th e ir n e w , m od em equipped, analytical laboratories a H e v i D u ty Combustion Furnace is u sed to assure accuracy a n d d epend­

ability in carbon deter­

m inations.

A Type 77 Hevi Duty "Multiple Unit" Combustion Tube Furnace in the Laboratory of the Chicago Vitreous

Enam el Product Co.

See Your Laboratory Supply Dealer or Write for Bulletin No. HD 123G.

H E V I D U T Y E L E C T R I C C O M P A N Y

T R A D E M A R K

LABORATORY FURNACES MULTIPLE UNIT ELECTRIC EXCLUSIVELY

REG. U. S. PAT. OFF.

M I L W A U K E E , W I S C O N S I N

LUSTERLITE

ENAMELS

NOVEM BER 15, 1937 ANALYTICAL ED ITIO N 11

Gas Analysis A p p a r a t u s

BOTH WILL BE SENT— IF REQUESTED

“ B u ild -U p

“ B u ild -U p *

“ B u ild -U p

10015

“ B u ild -U p ” De Luxe Model “ H ”

10305

‘B u ild -U p ” M as ter Model “ R C ”

CATALOG 7 9 —s

e e w h a t i t m e a n s t o h a v e a “ B u i l d - U p ” g a s a n a ly s is a p p a r a t u s a d a p t a b le t o b o t h p r e s e n t a n d f u t u r e r e q u ir e m e n t s .

10400

“ B u ild -U p ” Flue Gas Model

BURRELL M A NU A L—obtain this

n e w h a n d - b o o k j u s t p u b lis h e d t o r e v ie w , in c o n c is e f o r m , t h e m o d e r n a n a l y t i c a l p r o c e d u r e .

B u r r e l l T e c h n ic a l S ^{u p p l y} C ^o ., P i t t s b u r g h , P ^a .

12 INDUSTRIAL AND E N G IN E ER IN G CHEM ISTRY VOL. 9, NO. 11

K U H L M A N N S E M I - M I C R O B A L A N C E

T h e b a la n c e u s e d e x c lu siv e ly b y F . P r e g l fo r m a n y y e a r s a n d n o w p r e f e r r e d b y m a n y w o rk e rs fo r s e m i-m ic ro a n a ly s is b e c a u s e o f its sim p le a n d d e p e n d a b le c o n s tr u c tio n

B A L A N C E , S E M I - M I C R O , K u h lm a n n N o. 4-a. A quick-w eighing, short-beam , precision m acro balance of essentially th e sam e co n stru ctio n as th e K u h lm an n M icro-C hem ical B alance b u t w ith sen sitiv ity ten tim es less an d ca p a c ity te n tim e s g reater. T h is is th e balance used exclusively b y F. Pregl for m a n y years an d is referred to b y him in, “Q uantitative Organic M icroanalysis,” 2nd E nglish ed. (P h ila ­ delphia, 1930), pp. 6 and 10. I t is now preferred b y m a n y w orkers for sem i-m icro analysis because of its sim ple and dependable construction. See G. G orbach, “D ie M ikrow aage,” M ikrochem ie, B a n d X X , 2. u n d 3. H eft (1936), s. 299.

S en sitiv ity — 0.01 m g, c o n sta n t over en tir e range. A ch a n g e in w eigh t of 1 m g (eq u al to s h iftin g th e rider on e d iv isio n ) ch a n g es th e sw in g of th e p oin ter 10 d iv isio n s, w hich is e q u iv a le n t t o sh iftin g th e zero p o in t 5 d iv isio n s.

C apacity— 2 0 0 gram s.

C a se— Of m a h o g a n y , w ith p o lish ed b la c k g la ss b ase, w ith o u t draw er.

F r o n t a n d b a ck are co u n terp o ised an d s id e d oors are h in g ed for ea sv acc ess to p ans. O u tsid e d im en sio n s, 1 4 1/ j in ch es w id e X 14*/s in ch es h igh X 101/* in ch es d eep . W ith s p ir it le v el and le v e lin g screw s.

Beam and Hangers— H e a v ily g o ld p la te d . B ea m is 135 m m long an d is g rad u ated from le ft to rig h t in 100 n o tch ed d iv is io n s . T h e zero p o in t is a t th e le f t an d m o v in g of th e 50 m g rider for th e co m ­ p lete le n g th of th e b ea m is eq u a l to a d d in g a w eigh t of 1 d ecigram . F or 10 n o tch es, it a m o u n ts th erefore to 1 ce n tig ra m , and for one

u otch to 1 m illig r a m . T h e p o in ter sc a le h as 12 d iv isio n m arks on each sid e of th e cen tra l d iv is io n an d V ioth m g an d p o rtio n s th ereof are read b y a m a g n ify in g m irror. A v er y sh o r t tim e is requ ired to o b ta in eq u ilib r iu m , i.e . 6 seco n d s w ith an u n lo a d ed b a la n ce, 9 secon d s w ith 100 gram lo a d , an d 12 seco n d s w ith 2 0 0 gram lo a d .

Knife Edges and Planes—Of a g a te th ro u g h o u t.

Release and Arrest—T h e b eam a rr estin g m ech a n ism m o v es in a v er­

tic a l p la n e, a rrestin g th e b eam a t tw o p o in ts, a n d th e stirr u p s a t four

E

o in ts— a ll of w hich are o f a g a te— sim u lta n e o u sly sep a ra tin g th e earin g surfaces of th e p la n es from th e k n ife edges.

P a n s — 7 0 m m d ia m ete r.

A rch es— 2 10 m m h ig h , 100 m m w id th b e tw een b o w s. E a ch stirr u p is p ro v id ed w ith a hook for ca rry in g su sp en d ed v e s s e ls .

Rider Carrier— Of th e co u n terb a la n ce d ty p e fu rn ish ed w ith M icro- C h em ica l B a la n ce.

1887-M.

1887-0.

1887-P.

Balance, Semi-Micro, Kuhlmann No. 4-a, as above described, complete with No. 1887-P set of heavily platinized weights 200 grams, with fractionals of rock crystal and two 50 mg riders.

With detailed directions for weighing... ...

Ditto, but without No. 1887-P set of weights...

Set of Weights, only, 10 nig to 200 grams, for use with above Balance. With gram pieces heavily platinized and with fractionals of rock crystal. W ith two 50 mg riders and ivorv tipped forceps, in velvet lined box with lid. Per se t...

WordCode 225.00 Aolif 175.00 Aolik

50.00 Aolin

ARTHUR H. T H O M A S COMPANY

R ETA I L - W H O LESALE— EX P O R T

LABORATORY APPARATUS AND REAGENTS

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

C a b le A d d re ss, “ B a la n c e ,” P h ila d e lp h ia

IN D U S T R IA L

andENGINEERING

C H E M I S T R Y

H a r riso n E . H o w e, E d ito r

ANALYTICAL EDITION

E lectrom etric T itration o f A cids in O xidized P etroleu m Oils

A . R . RESCORLA, F. L. CARNAHAN, a n d M . R. FEN SK E

P e tr o le u m R efin in g L aboratory, T h e P en n sy lv a n ia S ta te C ollege, S ta te C ollege, Pa.

I

T IS L IK E L Y th a t n o t all the acids of oxidized petroleum oils are dissolved in the alcohol- w ater m ixture used in th e pro­

cedure (2) in A. S. T. M . Desig­

nation D188-27T, b u t th a t in­

stead they are distributed be­

tween the solvent and th e oil (3).

T his circum stance makes titra ­ tion difficult. Furtherm ore, the deep shade of th e m ixture be-

T h e very w ea k a c id s p r e s e n t in o x id ized p e tr o le u m o ils are titr a te d o n ly w it h d iffi­

c u lty b y m o s t m e th o d s . A s im p le p a ir o f d is s im ila r e le c tr o d e s a n d a d ir e c t-r e a d in g a m p lifie r w ith th e o il d isso lv e d in a n o n - a q u c o u s liq u id w it h s u it a b le s o lv e n t p ow er and c o n d u c tiv it y a llo w th e e s t im a t io n o f a cid s in slu d g e d p e tr o le u m o ils w ith r e a s o n ­ a b le a cc u r a c y .

ing titra te d masks th e delicate

color change of th e indicator. C om m ittee D-2 of the Ameri­

can Society for T esting M aterials has been active in develop­

ing a potentiom etric m ethod (1) for th e determ ination of oil acidity under such circum stances th a t o rdinary procedures are not feasible. A therm ionic titrim eter or a potentiom eter is used to indicate th e e .m .f. of an electrode system composed of a calomel half-cell and a platinum indicator electrode; th e oil is dissolved in buty l or am yl alcohol or in certain solvent mix­

tures such as equal p arts of b u ty l alcohol and benzene, lithium

chloride being present to give solution conductance; s o d iu m b u ty la te is used as th e base.

O ther investigators (3, 5 ,7 ,8 ,9 ) have studied th e possibility of electrom etric titra tio n of oxi­

d iz e d o ils in n o n a q u e o u s mediums, usually isoamyl or n- b u t y l a l c o h o l sa tu ra te d with lithium chloride. Various types of electrodes have been pro-

Fi g u r e 1. As s e m b l y f o r Eł e c t r o m e t r i c Ti t r a t i o n

A . M illia m m e ter B . B a tte r y sw itc h C. A d ju sta b le rh eo sta t D . B u ret, 10 cc.

E . S tirrer, m o to r n o t sh o w n F. P la tin u m electro d e G. T u n g ste n e lectro d e / / . E le c tr o d e sw itch

I . A lu m in u m b o x c o n ta in in g tu b es 5 7 , 2 A 3, e tc . J . A sb e sto s b o x c o n ta in in g tran sform ers, e tc .

posed; R alston, Fellows, and W y a tt (o) as a result of K ahlenberg’s work (4) used th e carbon- platinum pair. Shenk and Fenwick (6) designed a direct-read­

ing am plifier which can be substituted for th e potentiom eter frequently used in connection w ith bim etallic electrode sys­

tem s; this instrum ent is satisfactory for aqueous or nonaque­

ous solutions.

In th e present investigation, a tten tio n has been given to the selection of a suitable electrode pair, an indicating device and a base, b u t it was especially necessary to develop a nonaque­

ous m ixture of proper solvent and conducting power for use w ith oxidized oils.

A p p a r a tu s

T he a p p a ratu s used in determ ining acid contents of oxidized oils is shown in Figure 1. I t consists essentially of a p air of electrodes together w ith a device for am plifying and indicating th e very small current furnished by th e electrodes to a high- resistance circuit, a b u ret (graduated in units of 0.05 cc.), and a suitable reaction vessel w ith provision for stirring. T h e presence of air did not cause any difficulty. T he oil under exam ination was dissolved in a m ixture consisting of equal parts by volume of isoamyl alcohol, benzene, and carbon te tr a ­ chloride and sa tu ra te d w ith lithium chloride; th e base was prepared b y dissolving sodium in isoamyl alcohol.

El e c t r o d e s. Since the hydrogen electrode and o ther sta n d ard electrodes are easily poisoned and ra th e r difficult to use in routine work, th e tungsten-platinum pair was selected for this investigation. Of several electrode com binations tested (see Figure 3) th e tungsten-platinum gave th e largest change in potential a t the equivalence poin t and appeared to be sufficiently rugged. H olt and K ahlenberg (4) previously found this com bination suitable for w ater solutions.

T h e d ata in T able I present a com parison of titra tio n results 505

INDUSTRIAL AND EN G IN E ER IN G CHEM ISTRY VOL. 9, NO. 11

3 MEGOHMo

imcuMomooauMtQ -I/O k ö iJ S H

A C -

P

im m m m m im i

H— HO v o l t s -H

A.C.

P

Fi g u r e 2 . Wi r i n g Dia g r a m o f In d i c a t o r f o r El e c t r o m e t r i c Ti t r a t i o n A . V o lta g e d iv id in g re sista n ce , 2 5 0 ,0 0 0 0

B . D ir e c t cu rren t m illia r a m eter (0 to 5 0 m a.) C. R a d io “ C " b a tte r y (U H 15 B ) a n d resista n ce D . 3 -m eg o h m re sista n ce

E . R . C . A. rad io tro n tu b e 57 F . 2 5 0 ,0 0 0 ft p la te re sista n ce Q. R . C . A . rad io tr o n tu b e 874

I I. 4 -m ic ro fa ra d S p rague o il con d en ser, 1000 v o lts I . R . C . A . rectifier tu b e 81

J . R . C . A . r a d io tr o n tu b e 2A 3 K . 3 0 0 0 ft resista n ce

L . 2 .5 - v o lt ta p -o ff tran sform er M , N . 6 0 0 -v o lt ta p -o ff transform ers O. 7 .5 - v o lt ta p -o ff tran sform er P . P o w er s u p p ly to tran sform er P t. P la tin u m electro d e

W . T u n g sten electro d e 5 . S h o r tin g sw itch for electrod es

obtained w ith th e tungsten-platinum pair to those resulting from th e use of platinum -calom el and platinum -silver-silver chloride electrodes; th e neutralization num ber for a particular oil sam ple is 0.71, 0.73, and 0.77, respectively, for th e three electrode com binations.

T i t r i m e t e h . T he titrim ete r consists of a rectifier and an amplifier w ith electrical circuits as shown in Figure 2 .

The No. 81 tubes are full wave rectifiers, each with a 4-micro­

farad filter to supply voltages for the grid and plate circuits of tubes 57 and 2A3. The voltage imposed on the screen of tube 57 is controlled by a gas-filled voltage-regulator tube designated as 874. I t will be noted th a t the system is arranged to nullify the effect of variations in the source of supply.

The potential over the grid circuit of tube 57 is the algebraic sum of the bias voltage and the voltage across the electrodes.

I t may be seen from Figure 2 th a t a voltage change in the grid

circuit of the 57 tube affects the plate current of this tube. The plate current variation in the 57 tube in turn effects a change ill the bias of the grid circuit of the 2A3 tube through a 250,000-ohm re­

sistor. The bias on the 2A3 tube is the algebraic sum of the voltage drop of the plate resistor and the drop across the section of the voltage dividing resistor marked B IA S. When the current de­

creases in the plate of tube 57, the negative bias on tube 2A3 becomes less with a concomitant in­

crease in current. Since this current is indicated directly on the milliammeter, B, changes in the potential between the electrodes may be readily followed as the titration proceeds. At the outset of a titration, the plate current of the 2A3 tube is regulated to about 10 milliamperes by adjusting the variable resistance, C; with this initial current, the radio tubes function in the most sensitive part of their operating curve during the addition of base.

E x p e r im e n ta l

S o l v e n t . Electrom etric titra tio n m ethods were first used for acids in turbine oils. Such oils are usually of low viscosity and contain no appreciable am ount of sludge or n aphtha-in­

soluble m a teria l; it was found th a t isoamyl al­

cohol saturated w ith lithium chloride is a satis­

factory solvent m edium. However, th is solvent is n o t suitable for more viscous oils or for sludged products. Considerable difficulty was experienced in finding a solvent m ixture which would dissolve sludged oils com pletely and readily and a t th e same tim e possess sufficient electrical conductivity. Such good oil solvents as benzene, chloroform, or carbon tetrachloride are poor conductors and app aren tly n o t sus­

ceptible to im provem ent. W hen a sa tu ra te d solution of lithium chloride in ethyl alcohol was mixed w ith various noncon­

ducting oil solvents, th e m ixture had good conductance b u t low solvent power. T he presence of a conducting sa lt in m any

T a b l e I. C o m p a r i s o n a m o n g P l a t i n u m - T u n t g s t e > j , P l a t i - n u m - C a l o m e l , a n d P l a t i n u m - S i l v e r - S i l v e r C h l o r i d e E l e c ­

t r o d e s i n T i t r a t i n g a S a m p l e o f U s e d O i l

B ase P t-W P t-C a lo m e l P t-A g -A g C l

Cc. M a . A M a ./c c . M a . A M a ./c c . M a . A M a ./c c .

0 8 . 0 10 5 . 0

0 .1 8 . 8 *8 1 0 .8 *8 6 .0 10

0 . 2 9 .2 4 11.0 2 6 .5 5

0 . 3 9 . 8 6 1 1 .5 5 6 . 8 3

0 . 4 1 0 .2 4 1 1 .5 0 7 . 0 2

0 . 5 1 0 .5 3 1 1 . S 3 7 .2 2

0 . 6 11.0 5 1 2 .8 10 7 . 5 3

0 . 7 1 1 .5 5 1 3 .0 2 8 . 0 5

0 . 8 1 3 .0 15 1 3 .2 2 8 . 8 3

0 . 9 1 4 .2 12 1 3 .8 6 9 . 8 10

1 .0 1 5 .8 16 1 5 .0 12 1 1 .2 14

1 .1 1 7 .0 12 1 6 .5 15 1 3 .8 26

1 .2 1 9 .5 25 1 8 .0 15 1 5 .2 16

1 .3 2 1 .2 17 1 9 .8 18 1 6 .5 13

1 .4 2 4 .0 28 2 1 .8 20 1 8 .5 20

1 .5 2 7 .0 30 2 4 .3 25 2 1 .0 25

1 .6 2 9 .2 22 2 6 .8 25 2 3 .5 25

1 .7 3 0 .2 10 2 8 .5 17 2 7 .0 35

1 .8 3 1 .2 10 2 9 .5 10 2 8 .5 15

1 .9 3 2 .0 S 3 0 .5 * 10 3 0 .5 20

2 . 0 3 2 .2 2 3 1 .0 5 3 2 .5 20

2 .1 N eu tra liz a ­

tio n n um b er 0 .7 1 0 .7 3

3 3 .2 0 .7 7

7 CC. OF BASE ADDED

F i g u r e 3. I n f l e c t i o n s O b t a i n e d w i t h V a r i o u s E l e c ­ t r o d e P a i r s i n t h e T i t r a t i o n o f A c i d s i n a U s e d O i l

NOVEMBER 15. 1937 ANALYTICAL E D ITIO N 507 cases appears to decrease oil solubility. T able I I gives infor­

m ation on some of th e solvents tried. A t length it was dis­

covered th a t a m ixture composed of equal p a rts by volume of isoamyl alcohol, benzene, and carbon tetrachloride and sa tu ­ ra te d w ith lithium chloride evidences th e necessary qualifica­

tions. I t was found possible to dissolve com pletely an oil con­

taining 0.4 per cent of sludge in two volumes of this solvent; in titra tio n s six or m ore volumes of solvent to on e of oil were used.

T h e solvent m ay be conveniently prepared as follows: T he m iddle 80 per cent of commercial isoamyl alcohol as obtained b y sim ple distillation was refluxed half an hour w ith an excess of lithium chloride. Volumes of benzene and carbon te tra ­ chloride equal to th a t of th e isoamyl alcohol were then added;

th e m ixture was refluxed for an additional half hour, still in th e presence of undissolved lithium chloride. T he solvent was filtered from any excess salt and stored in d ark glass bottles.

Ba s e. A base prepared b y dissolving sodium in freshly dis­

tilled isoamyl alcohol was found to be more satisfactory than one prepared from potassium hydroxide and isoamyl alcohol.

T he solution was m ade up every week and k ep t in d ark glass bottles w ith stoppers; no special arrangem ents were m ade to exclude air. S tandardization was effected by th e use of c. p. benzoic acid, using th e electrom etric titra tio n procedure de­

scribed later. Except for oils containing more th a n about 0.2 per cent of sludge (naphtha-insoluble m aterial), th e base used was approxim ately 0.05 N ; for such oils 0.2 Ar base gave a sharper inflection in th e titra tio n . Some of th e results m ay be explained on th e basis th a t 1 cc. of reagent added contains four tim es as m uch base, b u t in other cases th e end point with th e weaker base can hardly be detected. T he situation is shown graphically in F igure 4.

P r o c e d u r e . The amplifier is set in operation by imposing 110 volts upon the transformers and switching on the “ C ” bat-

Ta b l e I I . So l v e n t s Ex a m i n e d t o r Co n d u c t i v i t y a n d Oi l So l u b i l i t y

C o n d u ctin g Oil

S o lv en ts S a lt S o lu b ility C o n d u c tiv ity

Iso a m y l alco h o l L i C l F a ir G ood

n - B u t y l a lc o h o l (10 p arts b y v o lu m e ), ca rb o n te tr a c h lo ­

rid e (1 part) L iC l P oor G ood

E t h y l a c e ta te (6 p a r ts), b e n ­ z e n e (3 p a rts), carbon te tr a ­

ch lorid e (1 p art) L iC l P oor G ood

I so a m y l a lc o h o l, b en zen e, car­

b o n tetra c h lo rid e (eq u al

p arts) L iC l G ood G ood

a ec-B u ty l alc o h o l L iC l or H g C h P oor Poor

D io x a n L iC l or H g C li P oor P oor

T etra lin L iC l or H g C h P oor Poor

T er p in eo l L iC l or H g C h P oor P oor

P e n ta c e ta te L iC l or H g C li P oor Poor

C h lorob en zen e L iC l or H g C lj Poor P oor

T etra ch lo ro eth a n e L iC l or H g C lj Poor Poor

H e x a lin L iC l or H g C li P oor P oor

B u t y l p ro p io n a te L iC l or H g C h Poor P oor

B u t y l a c e ta te L iC l or H g C h P oor P oor

a -P ic o lin e L iC l or H gC lj P oor P oor

o -D ich lo r o b e n z en e L iC l or H g C h P oor F air

f«rf-A m yl alcohol L iC l or HgCl* P oor F air

n -A m y l b u ty r a te L iC l or H g C h P oor F air

E th y le n e d ich lorid e L iC l or H g C h P oor F air

B e n z y l ch lorid e L iC l or H g C h P oor Fair

M e th y le th y l k eto n e L iC l or H g C h P oor G ood

M e th y lh e x y l k eto n e L iC l or H g C h P oor P oor

A c e to n y la c e to n e

n -B u ty l a lc o h o l, b en zen e, car­

L iC l or H g C h P oor G ood

b o n tetra c h lo rid e (eq u al

p arts) L iC l F air G ood

Ta b l e I I I . Ti t r a t i o n o f Pu r e Ac i d s i n So l v e n t

B en zo ic a cid , gram 0 .0 2 2 5 0 .0 2 1 2

S tearic a cid , gram N o r m a lity of b ase

0 .0 3 8 6 0 .0 3 5 3 0 .1 0 6 0 .1 0 6 B a se requ ired , ca lcd . for:

B en zo ic acid 1 .7 5 1 .6 5

S te a ric acid 1 .3 0 1 .2 0

B la n k 0 .5 0 0 .5 0

T o ta l 3 .5 5 3 .3 5

B a s e u sed in titr a tio n 3 .6 0 3 . 3 0

D ifferen ce, per ce n t 0 .1 4 0 .1 5

M a x im u m v a lu e of Am a. per cc . of b ase 110 100

CC. OF BASE ADDED

Fi g u r e 4 . In f l e c t i o n s Ob t a i n e d w i t h Di f f e r e n t Co n c e n t r a t i o n so f So d i u m Is o a m y l a t ei nt h e Ti t r a t i o n

o f Us e d Oi l s

tery (C, Figure 2). Ten minutes are allowed for the tubes to reach equilibrium. In the meantime, the platinum-tungsten electrodes are removed from the 5 N hydrochloric acid solution in which they are immersed when not in use, heated red-hot, and allowed to cool before being placed in operating position as shown in Figure 1. An oil sample of approximately 4 grams (weighed to 0.01 gram) is put in a cylindrical glass container about 12.5 cm.

(5 inches) tall and 3.75 cm. (1.5 inches) in diameter. To the oil are added 30 cc. of a liquid mixture containing equal volumes of iso­

amyl alcohol, benzene, and carbon tetrachloride and saturated with lithium chloride.

With the test jar in position as shown in Figure 1, its contents are whirled rapidly by an electric stirrer. The shorting switch (*S, Figure 2) is opened and the resistance, C, is adjusted to allow a current of 10 milliamperes through the system; since the elec­

trodes do not reach equilibrium a t once, variation of the resistance is continued until a steady state is attained.

Addition of base to the oil solution is made in 0.1-cc. portions with stirring for 1 minute after each increment before the reading of the milliammeter is taken. The titration is conducted in this manner until a sharp increase in current is noted on adding one of the 0.1-cc. portions of base; further additions produce little change in current. From the data so obtained the increase in milliamperes per cubic centimeter of base added ( Ama. per cc.) is calculated; the end point of the operation is indicated by a comparatively large value for this term. Correction for any solvent acidity is made on the basis of blank runs. End points may be shown very clearly by plotting Ama. per cc. against the amount of base added as has been done in Figure 3; this proce­

dure, however, is not usually necessary, as inspection of the calcu­

lated values is sufficient. The time required for each titration is approximately half an hour. The data have been expressed as A. S. T. M. neutralization numbers, milligrams of potassium hydroxide per gram of oil.

E x p e r im e n ta l R e s u lts

Pu r e Ac id s. W eighed am ounts of benzoic and stearic acids were dissolved in th e solvent m ixture; electrom etric ti­

tra tio n was conducted in th e usual way. T he detailed d a ta are given in T able I I I ; th e course of th e titra tio n m ay be followed in Figure 5. T he indication of th e end point is very clear; the

5 0 8 INDUSTRIAL AND EN G IN EER IN G CHEM ISTRY VOL. 9, NO. II observed results differ only ab o u t 0.15 per cent from the cal­

culated values.

Oil s Co n t a in in g Pu r e Ac id s. Oils containing definite am ounts of stearic, oleic, and picric acids, singly or in com bina­

tion, were titra te d using the electrom etric m ethod and also the A . S. T . M . procedure. T he results agreed reasonably well with each other and w ith th e calculated values; these d a ta are shown in T able IV. T he average difference of th e electro­

m etric indication from the calculated value was ab o u t 7 per cent; th a t for th e A . S. T . M . reading about 11 per cent. Neu­

tralization num bers on duplicate samples m ay be checked w ithin 0.2 per cent by th e electrom etric m ethod.

M ost electrom etric titra tio n s of polybasic acids or m ixtures of acid furnish more than one end point, b u t the present m ethod gives only one; this m ay be regarded as a desirable characteristic in th e titra tio n of oxidized oils having present a v ariety of acidic constituents.

Ta b l e I V . Ti t r a t i o no f Oi l s Co n t a i n i n g De f i n i t e Am o u n t s o f Or g a n i c Ac id s

A cid P resen t

E q u iv a ­ len t K O H

T o ta l K O H

K O H F o u n d E le c tro - A. S. T . M . m etric

D e v ia tio n E lectro - A . S. T . M . m etric

M g .fg , M g ./g . M g ./g . M g ./g . % %

S te a ric 0 .3 1 7 0 .3 1 7 0 .3 8 2 0 .2 7 4 20 14

S tea ric 0 .8 1 8 0 .8 1 8 0 .8 8 5 0 .7 2 4 8 11

S tea ric 1 .5 5 1 .5 5 1 .6 2 1 .4 5 5 6

S te a ric 0 .4 0 0

O leic 0 .4 3 4 0^834 0 ! 909 0 Í8 4 6 *9 i

S tea ric 0 .8 0 4

O leic 0 .8 3 2 l!(>4 1^39 l' .h i 15 8

B lank 0 .1 0 6 0 .0 6 0

Picric 0 .6 5 O leic 1 .9 1

S tea ric 6 .2 4 8 .8 0 9."54 9 Ü 9 8 •i

Ox id iz e d Oi l s. D uplicate determ inations were run on over a hundred oil samples obtained from engines operated by the D ep artm en t of M echanical Engineering. T he results were reproducible within 10 per cent; this variation m ay be a ttrib ­ uted to the difficulties of sam pling sludged oils, to th e less marked end points, and probably to other factors. Figure 5 dem onstrates th e relative values of Ama. per cc. of base added for some oxidized oils and for oils to which benzoic and stearic acid had been added. T he smaller rate of change of current a t the equivalence point is probably due to th e low ionization constante of petroleum acids as com pared even to the rela­

tively weak pure acids m entioned.

¡'¿0

too

^{o , x} BENZOIC AND STEARIC ACIDS IN SOLVENT, f TWO SAM PLES

o 80

a , o TWO S A M P L E S OF A U SED OIL

*,B TWO S A M P L E S OF A D IF F E R E N T

U SED OH- .

)

1 P

<] 40

" A

2 0

-

X 0

--- --- Ci f t . L . \ ---

\ l

0 / 2 3 4 5

CC. OF BASE ADDED

Fi g u r e 5 . Co m p a r i s o n o f In f l e c t i o n s Ob­ t a i n e dw i t h Pe t r o l e u m Ac i d st o Th o s e Sh o w n b t Mi x t u r e s o f Be n z o i c a n d St e a r i c Ac id s

T he neutralization num bers of m any of the oxidized oils were found also by th e A. S. T . M . m ethod (£) ; these are gener­

ally lower th a n those determ ined electrom etrically for the same oils, especially w hen deterioration was extensive. Illus­

tra tiv e d a ta are found in Figure 6. I t is considered th a t the electrom etric procedure for used oils is th e m ore reliable, inas­

much as th e acids in th e sludge are ta k en into account.

Sludge is soluble in th e liquid m ixture used for electrom etric titra tio n b u t n o t in th e m ixture of alcohol and w ater em ployed in th e A. S. T . M. procedure.

IS

£<o-

X

X X

x x_{* * X *}

—-cx"y5?

x X X

X X

0.0 0./ 0.2 0.3 0.4 0.5 0.6 0.7 NEUTRALIZATION N U M B E R

,

ELE C TR O M E TR IC T IT R A T IO N

Fi g u r e 6 . Co m p a r a t i v e Ne u t r a l i z a t i o n Nu m b e r so f Us e d Oi l s

T he acid content of a lubricating oil under service condi­

tions frequently becomes larger along w ith increases in Con- radson carbon residue value, viscosity, and sludge form ation, regular curves being obtained when th e quantities mentioned are plotted against acidity. In such cases it m ay be conven­

ient to follow th e deterioration of the oil b y determ ining its neutralization num ber from tim e to tim e during th e progress of an engine test.

S u m m a r y

An electrom etric m ethod using tungsten-platinum electrodes has been developed for th e estim ation of acids in oxidized petroleum oils. T he used oil is dissolved in a m ixture com­

posed of equal p a rts by volume of isoamyl alcohol, benzene, and carbon tetrachloride and sa tu ra te d w ith lithium chloride.

T he base is prepared by dissolving sodium in isoamyl alcohol.

R esults for pure organic acids dissolved in solvent are re­

producible w ithin 0.2 per cent; th e average difference of th e observed from th e calculated values is 7 per cent. Check de­

term inations on used oils have a m axim um deviation of 10 per cent.

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

T he technical assistance of E. M . F ry, R. H . M cCormick, and G. E . Woods in constructing th e ap p a ratu s and obtaining d a ta is appreciated. T his work was a p a rt of th e research pro­

gram of th e Pennsylvania G rade C rude Oil Association and is published w ith its permission and th a t of th e School of Chem­

istry and Physics of T he Pennsylvania S tate College.

L ite r a tu r e C ited

(1) Am. Soc. T esting M aterials, R ep t. Comm. D-2, "S tan d ard s on Petroleum Products a n d L ubricants,” p. 25, Sept., 1936.

(2) Ibid., p. 224.

(3) E vans, R . N ., an d D avenport, J . E., I n d . Eng. Chem., Anal. Ed., 8,287(1930).

(4) H olt, M . L., and Kahlenberg, L., Trans. Am. Electrochem. Soc., 57, 361 (1930).

(5) R alston, R . R ., Fellows, C. H., and W y att, K . S., I n d . E n d . Chem., Anal. E d., 4, 109 (1932).

(6) Shenk, W . E „ and Fenwick, F „ Ibid., 7, 195 (1935).

(7) Seitz, H., and M cKinney, D. S., I n d . Eng. Chem., 20, 542 (1928).

(S) Seitz, H., and Silverm an, L., Ibid., Anal. E d., 2, 1 (1930).

(9) W ooten, L. A., and Ruehlc, A. E., Ibid., 6, 449 (1934).

R e c e i v e d August 1 2 , 1 9 3 7 .

Q ualitative D eterm ination o f G lycerol and E thylene G lycol in D ilu te A queous Solution

A. G. IIOVEY ^{A N D} T . S. HODGINS, Beck, R o ller & C o m p an y , In c ., D e tro it, M ich.

B

ECAUSE alkyd resins contain polyhydric alcohols, de­

tecting the n ature of th e polyhydric alcohol is essential.

T he custom ary procedure in analyzing alkyd resins is to d eter­

mine th e weight of plithalic anhydride or other polybasic acids and th e w eight of fa tty acids or other modifiers leaving the glycerol to be determ ined by difference (5, 6). As long as glycerol was th e only polyhydric alcohol used, this deter­

m ination by difference was allowable though n o t satisfactory.

Today, however, ethylene glycol is available and relatively cheap and therefore we m ust expect its presence in m any alkyd resins. T here seem to be no references in the literatu re to an easy and sensitive q u alitative determ ination of ethylene glycol in dilute aqueous solution. Q ualitative tests for glycerol in dilute solutions have been described by M ulliken (8), G ardner (8), and others, b u t in these te sts there is still much to be desired, p articularly when it is necessary to distinguish glycerol from ethylene glycol.

Heretofore in attem p tin g to determ ine w hether glycerol or ethylene glycol is present, m any tedious procedures have had to be overcome. T he m ain detectable differences between glycerol and ethylene glycol have been in th eir physical properties. Differences between these two polyhydric alcohols in aqueous solutions have been determ ined by comparison of such physical properties as specific gravity (1), refractive index (4), boiling poin t (2), freezing point, etc. In actual practice, however, there is usually so m uch w ater present th a t concentrating th e solution of a polyhydric alcohol in­

volves as m uch difficulty and tediousness as th e regular m anu­

facturing process for concentrating glycerol (9 ). T his ex­

cess of w ater in th e analytical sam ple is due to th e fact th a t th e resin sam ple has first to be acidified after th e saponifica­

tion so as to precipitate out fa tty acids, phthalic acid, or other polybasic acids. After this separation a steam distillation (7) is necessary to separate th e polyhydric alcohol from th e salts, which are formed by acidification of th e saponified sample.

T he literatu re has been searched for a q u alitative colori­

m etric m ethod for determ ining glycerol and ethylene glycol in dilute solution; such a m ethod would save th e trouble of concentrating th e distillate. A te st has been described by M ulliken (5) which is essentially as follows: One drop of glycerol is dissolved in 2 cc. of cold w ater, and 5 drops of 1 per cent aqueous solution of pyrogallol and 2 cc. of concen­

trated sulfuric acid are added. U pon shaking and heating quickly to boiling, th e boiling being held 20 to 25 seconds be­

fore cooling, a coloration appears in a 15-cm. (6-inch) test tu b e upon dilution to 20 cc. w ith strong alcohol. T he color­

ation is a p urplish red, which fades in a very few m inutes on standing. T he authors have found th a t this purple coloration is also observed when using ethylene glycol in place of glycerol. In b oth tests, th e purple coloration turns to a light brown upon standing. In th e case of ethylene glycol th e color seems to fade som ew hat faster th a n th a t of glycerol, b u t un­

fortu n ately this is not a distinguishing test.

E x p e r im e n ta l

Using M ulliken’s work as a sta rtin g point, th e authors have carried th e work further, using homologs of phenol under both acid and alkaline conditions. A sum m ary of th e results is shown by T able I.

T a b l e I. Co l o r Re a c t i o n s o f Ph e n o l i c Bo d i e s w i t h Gl y c e r o l a n d Et h y l e n e Gl y c o l

R ea ctio n G lycerol E th y le n e G ly co l

P h en o l WVV« W W *

P h e n o l 4" N a O II (25% aq ueous

so lu tio n ) ww W W

P h en o l •+• N H4O H (sp. gr. 0.90) w w W W

P h en ol -f- HjSO< (con cd .) w w W W

C resol ww W W

C resol + N aO H ww W W

C resol + N I IíOH ww W W

C resol + H2SO4 ww W W

C atech ol ww W W

C a tech o l 4- N a O H G reen L ig h t brow n

C a tech o l + NH <O H P a le green

B lo o d orange P a le green

C a tech o l + HsSO* W W

R esorcin W W W W

R esorcin -f- N aO H Pu rp le L ig h t green

R esorcin 4* N H «O H Purple P u rp le

R eso rcin + H1SO4 D ark green L ig h t y ello w -g reen

W W

H yd ro q u in o n e W W

H y d ro q u in o n e + N a O H P a le y ello w B row n H y d ro q u in o n e 4* N H4OH B ro w n -y ello w B ro w n -y ello w

H y d ro q u in o n e 4* HjSO* W W W W

P yrogallol W W W W

P yro g a llo l + N a O II R ed O range

Pyrogallol + N H tQ K P a le y ello w P a le y ello w

P yro g a llo l + HjSO* P u rp le to brow n P u rp le to lig h t brow n

a W a ter-w h ite.

T able I, while it shows the possibilities of color differences between glycerol and ethylene glycol, is subject to variations if certain specific proportions and conditions are not observed.

Catechol appears to give th e m ost reliable and satisfactory color differences, especially when in an acid medium.

C h e m ic a ls

T he catechol (E astm an K odak Com pany No. 604) had a m elting p oint of 103° to 104° C. T he o ther phenols were also from th e E astm an K odak Com pany.

T he glycols were frotn th e C arbide and C arbon Chemicals Com pany and possessed th e following properties:

E th y len e g ly c o l D ieth y le n e g ly c o l T rieth y len e g ly co l Pro p y len e g ly co l

S p ecific G r a v ity 1 .1 1 7 6 @ 1 5 /1 5 ° C.

1 .1 1 8 5 § 2 0 /2 0 ° C.

1 . 1 2 2 - 1 .1 2 7 @ 2 0 /2 0 ° 1 .0 3 8 1 @ 2 0 /2 0 ° C. C.

R e fra ctiv e In d ex 1 .4 3 1 1 @ 2 0 ° C . 1 .4 4 7 5 @ 2 0 ° C .

T he trim ethylene glycol was obtained from th e P ro cter &

Gam ble Com pany and had th e following properties:

Specific g r a v ity A sh , % T iter M oistu re, % P u rity , % C olor

1 .0 6 0 3 0 .0 0 2 2 . 0 1.6 9 6 .0 14 Y ello w

2 Ited

T he glycerol c. p. had a specific grav ity of 1.265 a t 15° C.

T he sulfuric acid c. p . , specific g ravity 1.84 (A. C. S.

specifications), was from B aker & Adamson. Ammonium hydroxide was B aker’s c. p. grade (sp. gr. 0.90). Sodium hydroxide was M erck's c. p . (A. C. S. specifications).

P r o c e d u r e

T h e best conditions for th e color determ ination of glycerol appear to be as follows:

Place the following ingredients in a 15-cm. (&-inch) test tube in the order given: (1) 3 ml. of the solution to be tested, (2) 3 ml. of 10 per cent aqueous solution of catechol (freshly prepared, since such solutions color with age even if kept in a dark bottle), and (3) 6 ml. of concentrated sulfuric acid.

Heat the tube (gently) for about 30 seconds.

509