Industrial and Engineering Chemistry : analytical edition, Vol. 14, No. 8

INDUSTRIAL ^{a n d} ENGINEERING CHEMISTRY

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

H A R R IS O N E. H O W E , E D IT O R » I S S U E D A U G U S T 17, 1942 » V O L . 14, N O . 8 « C O N S E C U T IV E N O . 16

Photoelectric C o lo r ...

I. M. Diller, R. J. De Gray, and J. W. Wilson, Jr. 607 D eterm ining D eterioration of Cellulose Caused by

F u n g i ...Glenn A. Greathouse, Dorothea E. Klemme, and H. D. Barker 614 Rapid V olum etric M ethod for D eterm ination of

Sulfate Ion . Merle Randall and Henry O. Stevenson 620 Particle Size S t u d i e s ... H. E. Schweyer 622 D eterm ination of Beta-C arotene and Neo-Beta-

Carotene w ith V isual Spectrophotom eter . . . . F. P. Zscheile and B. W. Beadle 633 Pipet-Type Capillary V iscom eter for Substances

Which Are Solid or H ighly Viscous at Room T em ­ perature ...J. F. Weiler 634

E stim ation of COOH Groups in Commercial Starches Modified by Oxidation . . . L. H. Elizer 635 Colorimetric M ethod for Phosphates . . L. S. Stoloff 636 Analysis of In diu m Alloys . . . Charles W. Hopkins 638 Viscosity D eterm ination of Polym er Solutions . .

D. W. Young and E. H. McArdle 639 M easuring C oncentration of Dissolved Oxygen in

Dairy Products . . G. H. Hartman and O. F. Garrett 641 D eterm ination of Calcium in Presence of M ag­

nesiu m by Standard Soap S o l u t i o n ...

J. W. Polsky and E. C. Feddern 644

Colorimetric D eterm ination of Phenothiazine w ith Palladous C h lo r id e ...

Lyle G. Overholser and John H. Yoe 646

Identification of Alcohols by M eans of Optical Properties of Esters of Carbanilic A c i d ...

Bartlett T. Dewey and Norman F. Witt 648 Design of S till Heads for B atch Fractionation in

Laboratory C o lu m n s ... A. R. Richards 649 Oil M anom eter-M anostat to Control C olum n

T h r o u g h p u t ... S. A. Hall and Samuel Palkin 652 Simplified Calibration of Dropping Mercury Elec­

trodes ... James J. Lingane 655 Laboratory Pressure F lo w m e te r ...

L. J. Brady and B. B. Corson 656 MICROCHEMISTRY:

E stim ation of M agnesium w ith 8-Hydroxy- g u i n o l i n e ...

Louis Gerber, Ralph I. Claassen, and C. S. Boruff 658 Evaporation of Standard Solution from Tips of

M ic r o b u r e ts ...

A. A. Benedetti-Pichler and Sidney Siggia 662 N icotinic Acid C ontent of Cereals and Cereal

P r o d u c ts...John S. Andrews, Harold M. Boyd, and Willis A. Gortner 663 Growth S tim u la n ts in M icrobiological Assay for

Riboflavin and P antothenic A c i d ...

J. C. Bauernfeind, A. L. Sotier, and C. S. Boruff 666 Extraction and Assay of N icotinic Acid from

Anim al and Plant T i s s u e s ...

Vernon H. Cheldelin and Robert R. Williams 671 Technique and A pplications of Industrial Micro -

radiography . . . . G. L. Clark and S. T. Gross 67S Identification of Sugars by M icroscopic Appear­

ance of Crystalline Osazones . . . . W. Z. Hassid and R. M. McCready 683

T h e \m e r ic a n C h e m ica l S o c ie ty a ssu m es no r e sp o n sib ility for th e sta te m e n ts a n d o p in io n s a d v a n c e d b y c o n trib u to r s t o its p u b lic a tio n s.

0 5 non ■ . » I . . „ C o p y rig h t 1942 b y A m eric a n C h e m ica l S o c ie ty .

2 5 ,9 0 0 co p ies o f th is issu e p rin ted . *

P u b l i c a t i o n O f f i c e : E a s t o n , P e n n a .

E d i t o r i a l O f f i c e : 1 1 5 5 1 6 t h S t r e e t , N . W . , W a s h i n g t o n , D . C . T e l e p h o n e : R e p u b l i c 5 3 0 1 . C a b l e : J i e c h e m ( W a s h i n g t o n ;

„ P u b lish ed b y th e A m erica n C h e m ic a l S o c ie ty , P u b lica tio n Office, 2 0 th &

N o rth a m p to n S t s ., E a s to n , P e n n a . E n tere d ? s f e c o n d - c a ss m a tte r a t tn e

Post Office a t E a s to n , P e n n a ., u n d er th e A c t o f M a rch 3 , 1879, a s - . year In d u str ia l E d it io n m o n th ly o n th e 1st: A n a ly tica l E d itio n m o n th ly on th e 1 5 th . A c c e p ta n c e for m a ilin g a t s p e c ia l /a t e o f p o sta g e p rovid ed for in S ectio n 1103, A c t o f O c to b e r 3 , 1917. a u th o r ize d J u ly 13, 1918.

A nn u al s u b sc rip tio n r a te , I n d u stria l E d i t i o n an d A n a ly tic a l E d itio on ly as a u n it, m em b ers S 3 .0 0 , o th e rs $ 4 .0 0 . F o r eig n p o s ta K e to co u n tries n o t in th e P a n A m eric a n U n io n , $ 2 .2 5 ; C a n a d ia n p o sta g e , $ 0 .7 5 . S in g le

S p e c i a l L i c e n s e T E C - N Y - 8 4 1 A d v e r t i s i n g D e p a r t m e n t : 3 3 2 W e s t 4 2 n d S t r e e t , N e w Y o r k , N . Y . T e l e p h o n e : B r y a n t 9 - 4 4 3 0

cop ies: In d u stria l E d itio n , $ 0 .7 5 ; A n a ly tic a l E d itio n , $ 0 .5 0 . S p e c ia l r a te s to m em b ers.

N o c la im s can b e a llo w ed for co p ie s o f jo u rn a ls lo s t in th e m a ils u n less su c h cla im s a re receiv e d w ith in GO d a y s o f t h e d a t e o f is s u e , an d no cla im s w ill b e a llo w ed for issu e s lo s t as a r e su lt o f in su fficie n t n o tic e of ch a n g e of a d dress. (T e n d a y s' a d v a n c e n o tic e req u ired .) “ M issin g from files”

c a n n o t b e a c c ep te d a s th e rea so n for h o n o rin g a cla im . A d d re ss cla im s to C harles L . P a r so n s, B u sin e ss M a n a g er , 1155 1 6 th S tr e e t, N . W ., W a sh in g to n . D . C ., U . S. A .

LEEDS & N O R T H R U P

LEE D S &. N O RT H R U P COMPANY; 4920 STENTON

R avotube, installed in fu rn ace, is d etecting tem p eratu re w hich M icro m ax P yrom eter, in insert, records and controls.

THERMOCOUPLES SCARCE?

Maybe Rayotubes Can Serve A s W ell — Or Better

A t the time this is w ritten , the con­

servation of metals has led to certain official restrictions in the use of the thermocouples, couple-protecting tubes, and leadwires which are accessories to pyrometers, in m easuring the tem pera­

tures of furnaces, etc.

Before new thermocouples are needed, therefore, some companies may wish to see w hether they can use Rayotubes w here they have been using couples. W e suggest this possibility because a Rayo- tube lasts for years where a therm o­

couple may last for weeks or months, w ith consequent saving of much critical material.

Probably Rayrotube’s usefulness as an alternate to couples is best shown by those applications for which they are not alternate, but are preferred, and have for years been used by thousands. Such applications include:

(1 ) T em peratures too high for cou- Jrl Ad N-33-600(9)

pies; or so high couples don’t la st; or so high couples require excessive protec­

tion and are sluggish.

(2 ) T em peratures w here furnace gases are too corrosive for couples.

(3 ) T em peratures of furnaces in which vibration breaks couples.

(4 ) T em peratures of objects in mo­

tion.

(5 ) T em p eratu re of surface of an ob­

ject, rather than of a furnace gas, when greater sensitivity of control is desired.

Rayotubes can be used for tem pera­

tures as low as 650 F in certain cases.

T hey are completely at home from 900 F, up through and above the couple range, for indicating, recording and autom atic control.

If you give us a specific problem, we w ill gladly tell you w hether or not Rayotube can handle it, and recommend Rayotubes, thermocouples, or an O p ti­

cal Pyrom eter, as the case may be.

“ O h ! Say C an Y ou S ee!” is the title of this p h o to g rap h w hich won, for Photographer R. W . K n a u ft, Sales M a n a g e r of Chas.

T a y lo r Sons Co., first p rize in In d u strial Di­

vision of C eram ic C am era C lub exhibit. It show s D. I. Sm ith usin g an L&N Optical P yrom eter in the T a y lo r refractories plant.

Optical Pyrometer Can Help Users of Other Pyrometers

W h e th e r your plant uses thermo­

couples or Rayotubes to detect the tem­

peratures which are regulated by its control pyrometers, it’s almost certain th a t an L& N O ptical Pyrom eter can help in furnace operation. U ser simply looks through it at the hot work, turns a knob until a “ b ar” in the eyepiece seems to m elt into the w ork, and reads the tem perature in degrees. Readings can show difference between tempera­

tures in different parts of furnace, be­

tween couples and w ork, etc.

C atalog N -33D gives further details;

or, for special service, outline your prob­

lem and priority situation.

P a ir of R ayotubes on a Stew art contro atm osphere b ro a ch -h e atin g furnace, P ointe M ach . T ool Co., H udson, Mass.

.lled- La-

AVE., PHILA» PA‘

M E A S U R IN G IN S T R U M E N T S T E L E M E T E R S A U T O M A T IC C O N T R O L S H E A T-T R E A T IN G F U R "*00

August 15, 1942 A N A L Y T I C A L E D I T I O N 5

NEW G-E MODEL CA-6 BERYLLIUM WINDOW X-RAY TUBE SPEEDS UP DIFFRACTION STUDIES

THOROUGHLY TESTED — G -E perfected the Model CA-6 beryllium w in do w x-ray diffraction tube early in 1941, and the first commercially avail­

able model was installed in the laboratory o f a leading automotive manufacturer in August, 1941.

The performance records o f this and other CA-6 tubes back up these facts:

SPEEDS UP STUDIES—The Model CA-6 has a trans­

mission factor, in the range o f wavelengths for which these tubes are generally used, which is from six to ten times that o f Lindemann glass window tubes. Typical normal exposures can be made with the CA-6 beryllium window tube in approximately one-seventh to one-tenth the time required by Lindemann window tubes.

INCREASED TUBE L IFE -T he increased radiation out­

put o f the CA-6 tube in itself effectively serves to lengthen tube life since it permits a greater number of exposures w ithin a given time. In addition, its beryllium window is not susceptible to corrosion and x-ray deterioration.

FACTS ABOUT THE CA-6 TU BE-The G -E Model CA-6 tube is constructed with two beryllium windows in line with the long axis o f the focal spot. The w in­

dows are protected by a bakelite shield having high conductivity so that the shield may be operated at ground potential. The overall length o f the tube is approximately 28 inches, and the diameter o f the x-ray shield, the thickest portion o f the tube, is 3K inches. Target materials immediately available for war production use include copper, cobalt, iron, and chromium. Molybdenum, nickel, tungsten and other materials are available on special order.

For complete information about the new G -E Model CA-6 tube, write or wire, today, to D ept. R48.

GENERAL % ^ELECTRIC

X-RAY C O R PO R A TIO N

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

CHROMIUM IRON UUBAU NlblltL

LINDEMANN GLASS W INDOW X-RAY DIFFRACTION TUBE G-E MODEL CA-6 BERYLLIUM W INDOW DIFFRACTION TUBE

6 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 14, No. 8

H O S K IN S PRODUCTS

T h e c o i le d u n it is e a s i l y w ra p p e d a r o u n d Ih e o n e - p ie c e g r o o v e d muffle.

T h e t u r n s o f th e c o i l a r e con centrated at th e fro n t e n d to c o m p e n s a t e for h e a t l o s s a t th e d o o r . . . . T h e furnace s h o w n i s e q u i p p e d w it h s p e c ia l units a n d a 3 - w a y s w i t c h , w h ic h w ith a r h e o s t a t g i v e v e r y c l o s e tem perature c o n t r o l b e t w e e n 3 5 0 ° a n d 1 8 0 0 F.

M a y this H o sk in s Furnace help " m a k e it hot” fo r Hitler!

But it w o n ’t m ake y o u r lab. hot for you. Its thick in su ­ lation perm its the case to becom e o n ly w a rm , so if yo u chance to brush it w ith y o u r han d, y o u w o n ’t cuss. Hence, this H o sk in s Furnace contributes to com fortable w o rk in g conditions, an d is e co n o m ica l on pow er. . . . O u r 110-V.

furnace w o n ’t run on 2 2 0 -V . also . The h eating unit sh o w n here is 13 G a . (.07 2 " dia.) C h ro m el A . To run the sa m e furnace on 2 2 0 -V . a lso , the w ire w o u ld h a v e to be 17 G a . (.0 4 5 " dia.) T his s h o w s w h y the Ch rom el units of H o sk in s Furnaces are so durable. . . . For a fu ll descrip­

tion of all H o sk in s Furnaces, a s k y o u r dealer or us for C a ta lo g-5 8 . . . . H o sk in s M a n u fa c tu rin g C o m p a n y , Detroit, M ic h ig a n .

( A b o v e ) In u n it s , a n d i n s u l a t io n , H o s k i n s F u r n a c e s are very w e l l b u ilt , to b e c h e a p e s t in th e l o n g r u n . Y o u c a n buy a c h e a p e r f u r n a c e b u t n o t a b e tte r o n e .

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 E A D W I R E • • P Y R O M E T E R S • • W E L D I N G W I 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 F I X T U R E S • • S P A R K P L U G E L E C T R O D E W I 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 T U B E S

A N A L Y T I C A L E D I T I O N August 15, 1942

FACTS..

• g a th e r e d th ro u g h sy ste m a tic r e s e a r c h . . . a r e a b s o lu te ly n e c e s s a r y in m a k in g m o re d e a d ly bom bs, f a s te r p la n e s , a n d o th e r tools of w a r. Into this h e c tic r a c e for fa c ts, th e E lm es H y d ra u lic L a b o ra to ry P re ss fits like h a n d in g lo v e. It is h ig h ly a c c u r a t e . . . it is fa s t . . . it h a s "w o n its s trip e s " in lite ra lly h u n d re d s of p ro d u c tio n la b o r a to r ie s .

Q e a tu n & i O F T H E E L M E S “ L A B ” P R E S S 1 M a in ta in s c o n s ta n t p r e s s u r e w ith o u t a p p r e c ia b le loss

for a lo n g p e rio d of tim e — a c h ie v e d th ro u g h a n ew v a lv e a n d a s p e c ia lly d e s ig n e d p a c k in g .

2 S olves a v a r ie ty of sc ie n tific a n d c o m m e rc ia l l a b o r a ­ to ry p ro b le m s.

3 O ffe rs im p ro v e m e n ts n o t o rd in a rily a v a ila b le . 4 E n tire ly s e lf-c o n ta in e d ; p re c is io n built.

M A N Y APPLICATIO NS

Som e of the specific uses of this Elm es Lab orato ry Press are:

Blocking Breakin g

Tests Briquetting Cake fo rm ­

ing Forcing Form ing G lu in g C o m p re s­

sion Tests

La m in a tin g D e h yd ratin g D r a w in g E m b o ssin g Extrusion Plastic

M o ld in g P re ssin g S p rin g Test­

ing V u lc a n iz in g

A ls o M a n u fa c tu r e d in C a n a d a

WILLIAMS & WILSON, LTD., MONTREAL & TORONTO;

D is tr ib u to rs

'liJ'U te frv i b u lle ii+ t d e ta ili.

C H A R L E S F. E L M E S E N G I N E E R I N G W O R K S

246 N. M o r g a n St. • C h icago, Illino is H A Y m a r k e t 0 6 9 6

N O R T O N C O M P A N Y — W O R C E S T E R , M A S S

Vol. 14, No. 8

S c i e n t i s t s i n A m e r ic a n p r o c e s s i n d u s t r i e s a n d r e s e a r c h l a b o r a ­ t o r i e s a r e w o r k in g ’r o u n d t h e c lo c k t o t u r n o u t a r t i c l e s o£ w a r . T h e y a r e d is c o v e r in g n e w m e t h o d s , n e w m a t e r i a l s t h a t w ill m e a n b e t t e r p r o d u c t s fo r a ll o f u s w h e n o n c e a g a i n w e a r e a n a t i o n a t p e a c e .

F o r t h e s e s c i e n t i s t s N o r t o n C o m p a n y o ffe r s la b o r a t o r y w a r e m a d e o f A l u n d u m ( f u s e d a l u m i n a ) , a c h e m i c a l l y s t a b l e s u b ­ s t a n c e t h a t s t a n d s u p a t h i g h t e m p e r a t u r e s . A v a ila b le a r e c r u c i b l e s ; d i s c s ; d i s h e s ; t h i m b l e s ; t u b e s , c o r e s a n d m u f f le s fo r la b o r a t o r y f u r n a c e s , a n d p e l l e t s o r a g g r e g a t e s t o b e u s e d a s a c a t a l y t i c a g e n t o r c a r r ie r .

August 15, 1942 A N A L Y T I C A L E D I T I O N 9

T h e exchequer sta n d a rd avo ird u p o is pou nd (flat) of Queen Elizabeth

S T A N D A R D In Lot A fter Lot

Look at the maximum limits o f impurities on the label o f any package o f Mallinckrodt Analytical Reagent. And study a label o f the same chemical o f several months ago or several months later. They will read precisely the same, because Mallinckrodt Chemicals are made to pre-determined standards for precise analysis.

Have a catalogue o f Mallinckrodt Analytical Reagents and other labo­

ratory chemicals right at hand. Send for your copy now.

A L W A Y S S P E C IF Y R E A G E N T S IN M A N U F A C T U R E R ’S O R IG IN A L P A C K A G E S

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

ST. LOUIS • PHILADELPHIA • MONTREAL

CHICAGO • NEW YORK • LOS ANGELES

10 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 14, No. 8

K L E T T - S U M M E R S O N , G L A S S C E L L M O D E L

P H O T O E L E C T R IC C O L O R IM E T E R

P a rtic u la rly s u ita b le fo r u s e in in d u s tria l la b o ra to rie s

F o r g e n e r a l c o l o r i m e t r i c d e t e r m i n a - t i o n s o v e r a wide range o f colored or t u r ­ bid s o lu tio n s

R e c o m m e n d e d f o r use in th e c o l o r i m e t r i c d e t e r m i n a t i o n o f m o l y b ­ d e n u m in steel

3790-A

C O L O R IM E T E R , P H O T O E L E C T R IC (P h o to e le c tric P h o to m e te r ) , K le tt-S u m m e rs o n . A m o d i­

ficatio n of, a n d offered in a d d itio n to , th e T e s t T u b e M odel d esc rib e d b y W . H . S u m m erso n , of C ornell U n iv e rs ity M ed ical C ollege, in T he J o u rn a l o f Biological C hem istry, V ol. 30, N o . 1 {Sept., 1939), p. 149 (sold b y u s u n d e r o u r N o . 37SS-A a t $148.00). I n th e G lass C ell m o d el, m e a su re m e n ts are made in fused glass cells with solution depths of 2.5, 10, 20 or 40 mm, perm itting photoelectric measurements over a wide range of colored or turbid solutions. An adapter, for insertion in the cell chamber, provides for the use of standard 12.5 mm test tubes.

A self-contained, portable instrum ent of simple and rugged construction, with built-in galvanometer. Measure­

ments can be made with ease and rapidity, all necessary adjustm ents being controlled by a single knob, with only a few seconds required for each measurement. The zero point does not shift and results are unfailingly reproducible.

The compensated electrical circuit is based on the double photoelectric cell null-point principle, giving colorimetric measurements in terms of the graduations on a precision potentiometer. The light source consists of a 100-watt lamp which can be operated from any convenient electric outlet, a.c. or d.c., no constant current device being required since ordinary fluctuation in the line voltage or light intensity does not affect the readings.

The instrum ent is provided with a logarithmic scale, graduated from 0 to 1000 so th a t, when a linear calibration is ob­

tained, concentration of the unknown solution is determined directly by multiplying the scale reading by a factor. The working length of the scale is 12 inches and the inherent precision of measurements is ‘Ard of 1% of the full scale length.

The filter frame holds any standard light filter 2 inches square. This instrum ent is suitable for practically any pro­

cedure which has been devised for the visual colorimeter.

3790-A. Colorimeter, Photoelectric, Klett-Summ erson Glass Cell Model, as above described, complete with two color filters, i.e., 5400A (Green) and 4200A (Blue), frame for holding the filters, built-in galvanometer, heat filter, 100-watt lamp, fused glass cell for 20 mm and 40 mm solution depth, wooden box for six unmounted filters and instruction manual containing a bibliography of 63 references covering colorimetric determinations of inorganic elements and organic compounds, but w ithout test tube adapter. For 110 volts, a.c. or d.c...

... 183.00 3790-B. Ditto, b u t for 220 volts, a.c. or d.c... 183.00

Accessory and Replacement P arts

3 7 9 0 -C . 3 7 9 0 -D . 3 7 9 0 -F .

3 7 9 0 -J .

3 7 8 8 -C .

3 7 8 8 -D .

G la ss C ell, w ith p la n e , p a ra lle l s id e s fu se d to g eth e r.

F o r 10 m m s o lu tio n d e p t h ... 4 .6 0 R e d u c tio n P la t e , fo r in s e r tio n in 10 m m c e ll t o o b ta in a s o lu tio n d e p th o f 2 .5 m m ... 4 .4 0 G la s s C e ll, s im ila r t o 3 7 9 0 -C b u t for 2 0 m m s o lu tio n

d e p th or, w h en u se d e n d w ise , fo r 4 0 m m s o lu tio n d e p t h ... 5 .8 0 A d a p ter, for in ser tio n in th e c e ll ch a m b e r of a b o v e co lo r im ete r to a d a p t it for u se w ith s ta n d a r d 12.5 m m t e s t t u b e s ... 8 .0 0 S ta n d a r d iz ed T e s t T u b e , 10 m l c a p a c ity , 12.5 m m in ­

sid e d ia m ete r, u n g r a d u a ted .

E a c h ... 4 0 P e r d o z e n ... 4 .2 0 D itto , b u t g ra d u a te d a t 5 m l a n d 10 m l.

E a c h ...60 P e r d o z e n ... 6 .8 0

3 7 8 8 -D 5 .

3 7 8 8 -G 3 .

M ic ro T u b e , for 2 m l o f flu id , w ith fla t b o tto m and 12.5 m m s ta n d a r d s o lu tio n d e p th ; fo r in sertio n in t h e sp r in g h o ld er o f 3 7 9 0 -J A d a p te r in p la c e of the 10 m l t u b e ... 1*20

C olor F ilte r s , n a rro w b a n d , 2 in ch es sq u a re , u n m o u n ted for in s e r tio n in 3 7 8 8 -1 F r a m e

T r a n s m is s io n 4 0 0 0 A 4 2 0 0 A 4 4 0 0 A 4 7 0 0 A 5 0 0 0 A E a c h ... 6 .0 0 4 .0 0 6 .0 0 6 .0 0 9^00 T r a n s m is s io n . . . . 5 2 0 0 A 5 4 0 0 A 5 5 0 0 A 5 6 0 0 A 5900A E a c h ... " 6 .0 0 6 .0 0 9 .0 0 9 .0 0 6.00 T r a n s m is sio n . . . . 6 0 0 0 A 6 2 0 0 A 6 4 0 0 A 6 6 0 0 A 6900A E a c h ... 6j0 0 6^00 6 l0 0 6^00 7^00

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

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

LA B O R A TO R Y A PPARATUS AND REAG ENTS

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

C able A ddress, “ B ala n c e ,” P h ila d e lp h ia

INDUSTRIAL ^{a n d} ENGINEERING CHEMISTRY

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

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

Photoelectric Color

^{'' A}

iPOLITECHNIKIi

D escrip tion and M ensuration o f the C olor o f P etroleu m P roducts

I. M. DILLER1, R. J. DE GRAY', a n d J. W. WILSON, J r .

Socony-V açuum Oil Company, Inc., General Laboratories, T echnical Service D ivision, Brooklyn, N. Y.

P hotoelectric color is a new system for the m eas­

urem ent o f th e color o f lubricating oils. T he color is m easured directly in technologically significant term s. Only two readings are required: brilliance and characterization o f th e hue*

T h e system u ses a photoelectric colorim eter, de­

signed for accuracy and easy standardization for the m easu rem en t o f oil colors. T he colorim eter has a con tin u o u s scale from 1 to 100 for the defini­

tion o f th e in te n sity o f such colors.

D eviation o f h ue o f petroleum color from norm al is given directly in m agn itu d e and direction.

The color definition is independent o f th e visual response o f th e operator and o f th e particular in ­ stru m en t.

I. C. I. data can he calculated from photoelectric color, if desired. However, this is rarely desirable in petroleum technology. Photoelectric color can he correlated w ith th e U nion system .

T h e system is easily learned and its standardiza­

tion is based on colored solu tions w hich are re­

producible, easily prepared, and sensitive.

T

H E petroleum industry has employed a number of systems for the measurement and specifications of the color of petroleum products, each of which depends upon a visual matching of the color of the sample with th a t of a standard. Those systems commonly in use involve arbi­

trary standardization and cannot be correlated with each other by fundamental means. Furthermore, they afford no practical means for matching both brilliance and hue and, in lighter colors, purity as well—essential factors for a visual match.

Two methods in particular use are specified by the American Society for Testing Materials. The Union colorimeter (/) is used for determining the color of lubricating oils, while light- colored products are measured with the Saybolt chromometer (#), which bears no relation to the Union colorimeter except th at both depend upon a series of yellow disks and in addition the Saybolt color involves variation in depth of sample. I hese methods have several disadvantages. The instruments thern- selves are not entirely uniform. The glass standards are difficult of duplication and are subject to temperature changes, and their optical systems are not completely standardized. I he disks correspond only to certain selected points in the range of possible oil colors. Anomalous results have been noted on so-

1 P r ese n t a d d ress, 2 1 8 L in d en B lv d ., B ro o k ly n , N . Y.

called abnormal samples, when the brilliance or hue of the oil differs from th a t of the disk. These methods lack any relation to accepted systems of color definition (3, 8, 9, 10, 12, 18, 15, 17, 20), a brief description of which is given by Gardner (7).

Another method uses the Tag-Robinson colorimeter {22).

This is a combination of the Union and Saybolt methods and involves similar difficulties.

The Lovibond system (11) has a theoretical advantage in th a t it attem pts to overcome differences in hue by virtue of series in several hues of standard glasses, more closely spaced. In a limited sense the Lovibond system supplies the equivalent of a spectral curve. However, it suffers from the remaining dif­

ficulties of the other systems and, indeed, its added complexity results in an aggravation of the instrum ental disadvantages to the point where the actual results obtained are far removed from the theoretical possibilities.

A more novel method which has been used occasionally in the petroleum industry' is known as “true color” (16). Here, an oil or solution of an oil is chosen as standard either arbitrarily or in accordance with its match to a given Lovibond glass. Oils or their solutions are compared with the standard by variation of the thickness of the unknown. Other investigators have pointed out th a t the standard oil m ust be similar in color to th a t being measured, th a t the diluent introduces anomalies, and th a t Beer’s law holds for some samples but not for others. Consequently, a general correlation of true color with Union or Lovibond color is almost impossible, and widely varying values have been putn lished (14, 18, 23, 24). An attem pt to correct some of the faults of true color was made in the “optical density” method (6), which uses a neutral filter as standard and a green light source. The improvement is not substantial and the technique is further complicated.

All these systems are subjective and dependent on the observer and to a greater or lesser extent on the spectral selectivity of his eye a t the time of observation. The instru­

ments are difficult to standardize, different instruments giving different readings to the same observer. Differences in spectral distribution between standard and sample particu­

larly aggravate the difficulties of the subjective observer.

Where a thickness is varied as in the Saybolt, Tag-Robinson, true color, and optical density methods, dependence is placed on the applicability of Lam bert's law. Occasionally petro­

leum products follow Lam bert’s law; often, probably be­

cause of fluorescence, they do not.

The use of a photoelectric colorimeter has the potentiality of eliminating the effects of the subjective color response of individual observers or their equivalents. A step in this direction was proposed by Story and Kalichevsky (21).

Their proposal is limited to a single reading, which cannot express fully the color of an oil. Multiple-reading photo­

electric colorimeters have been proposed which by the use 607

of either three or four filters yield values th a t m ay be related to the various International Commission on Illumination quantities (19).

These systems yield the basic color information b u t in terms which lack immediate significance in petroleum technol­

ogy. For oil colors they are unnecessarily complex and fail to take advantage of the fortunate fact th a t the colors of petroleum oils vary only over a limited range.

The spectrophotometric curves of petroleum products are substantially smooth, have the same general shape, and invariably show higher transmission as the wave length increases. For any given brilliance, oils of various origins and methods of refining m ay be represented by a family of curves intersecting in the general region of 545 m n- Some of these curves will show a higher red transmission than others, and a correspondingly lower blue transmission—th a t is, all oils of a given brilliance have the same transmission a t the point of intersection, b u t some of the curves passing through this point are steeper than others. Thus for any oil, com­

plete characterization can be obtained by measurements of brilliance and of one other transmission a t a wave length remote from th a t of the intersection. This may be a t either the red or blue end of the spectrum, b u t for reasons de­

scribed below, it is made a t a certain point in the red region.

This paper presents a new system for the mensuration and description of the color of petroleum oils by means of a specially developed photoelectric colorimeter, so th a t it is objective, avoids any unnecessary complexity, and is de­

scriptive of the oil color in terms of direct physical significance.

The method is simple to handle and permits rapid deter­

mination. Provision is made for checking the instrum ent’s standardization by means of suitable aqueous solutions which m ay be easily prepared by any chemist. The results are convertible to the standard I. C. I. terminology (10). The system has been correlated with the Union method. A correlation with the Saybolt method is expected to be fur­

nished shortly. W ithin the limits of experimental error, the system also lends itself readily to being “additive” .

The general method here proposed should have broad application in color mensuration, particularly for classes of materials which have smooth, substantially unidirectional spectrophotometric curves of the same general shape. How­

ever, the present study concerned itself only with petroleum products. This system has also been applied to fatty prod­

ucts, with a view to Lovibond correlation (5).

D e s c r ip tio n o f M e th o d

The method, in its bare essentials, consists in focusing a stable beam of light into the sample which is held in a stand­

ard container. The light is modified by an optical filter and falls on a photoelectric cell. Readings are taken directly from the apparatus scale. One reading is required and a second is optional. The former is taken with the aid of a filter designated as “N orth Sky” or, in the case of very light oils, with a filter designated as “Violet” . The second reading is taken with a filter designated as “Red” . These readings can be converted directly, if desired, into I. C. I. values or Union color numbers.

The present system measures (1) the brilliance and (2) the steepness of the spectral curve. The first factor expresses the appearance of oil of a given thickness to a standard I. C. I.

observer looking a t C illuminant; and the second factor is best expressed in terms of the deviation of the steepness of the spectral curve from th a t of the average or normal a t the given intensity. In this manner a deviation in one direction w'ould show th a t the oil is greenish and in the other direction th a t it is reddish, with the magnitude of the figure giving the extent of deviation.

608 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 14, No. 8

Y - T R IS T IM U L U S VALUE

Fi g u r e 1. Co n v e r s i o n Ch a r t o f No r t h Sk y Re a d­ i n g s t o Br i l l i a n c e '

I t is expected th a t as a result of a future accumulation of data involving this second reading, it will become possible to use it as a refining guide as well as for the evaluation of finished oils.

The first of these factors is taken w ith the N orth Sky filter in position. This filter was so chosen th a t the instrum ent (not the filter) would respond as an average observer looking through the oil a t the north sky, but was later modified, as th e N. P. A. 8 oil gave too low a reading for practical use. By changing the filter to make the instrum ent correspond to a standard observer and C illuminant, the entire range of the Union system was best accommodated on the scale w ithout reducing the length of light path through the sample. This intensity or brilliance factor is read on a scale 1 to 100 and the reading is reported in "photo­

electric units” . The N orth Sky filter is a broad-band filter, but should not be confused with daylight glass.

(The N orth Sky reading would otherwise have differed from the combination of C illum inant and standard observer, in that the former provided for some near ultraviolet. This is ordi­

narily regarded as invisible and is therefore discounted. Such disregard is erroneous when it is considered th a t th e eye is not

“totally” blind to near ultraviolet light. Some fraction, indeed, a very small fraction, does affect th e visual response. On the other hand, th e absorption of near ultraviolet by a yellow sub­

stance such as oil is great as compared w ith the absorption of the more visible region, so th a t while th e visual response in this region is small, such effect is disproportionately felt.)

The second factor is determined with a narrow-band filter on either- end of the spectrum. For convenience, the red end is preferred. At the extreme red end, slight anomalies, otherwise unim portant, m ay arise, and for this reason the filter was so chosen th a t the instrum ent would respond to an average wave length of 610 m^.

While “color response” appears to be based primarily on bril­

liance, the eye is also influenced by the hue or dominant wave length of the oil. For this reason, difficulty is encountered in measuring many oils by the Union colorimeter whose comparison disks are fixed in hue which may differ markedly from th at of the sample. In order to express this property, two other param eters such as th e X and Z tristim ulus values appear to be necessary.

A third filter is provided, designated as V, which c a u s e s the instrum ent to respond to an average wave length of 390 mp. * ‘¡1S filter is suitable for “magnifying” the N orth Sky reading on the very light oils of th e Saybolt range, so th a t the thickness of the sample does not need to be increased. The spectral range of this filter was particularly chosen so th a t it could be converted to the equivalent of N orth Sky reading by th e simple equation given below.

The correlation of violet with Saybolt and the handling of petroleum colors in the lighter ranges will be taken up B detail in a future paper, b u t for the present the authors wish to point out th a t in the very light range, though not in the darker ranges, readings with one filter are equivalent excep

August 15, 1942 A N A L Y T I C A L E D I T I O N 609 for magnitude to readings on oil with any other filter, narrow

or broad.

By this method, a continuous color scale has been pro­

vided covering the entire range from the equivalent of Union No. 8 to Saybolt + 3 0 + .

E x p e r i m e n t a l

Th e Co l o r i m e t e r. The photoelectric colorimeter de­

veloped in the course of this work is based on Diller’s (4).

One of the features of the optical system of the instrument is th at it enables the use of test-tube sample containers without substantial error resulting from variations in the refractive index of the samples. The filters are arranged so th a t the effects of oil fluorescence are minimized. The light path is fixed. The lamp is of the prefocused type with a bar-shaped filament, and it is operated from a compensating transformer wliich supplies a constant voltage. In this manner, changes in spectral distribu­

tion of the filament emission are avoided. Such changes cannot be overcome by an attem pted balancing of photocells. A single cell of the barrier-layer type is used. The sample container is gripped in a wedge by a scratchproof roller, to maintain further the immobility of the optical system. The calibration has been found to be constant over a period of six years. I t is not subject to atmospheric variations or fatigue. The instrument is heavily constructed and its galvanometer is both rapid and damped.

The filters are mounted in a roulette with additional provision for miscellaneous filters, so th a t the instrument can also be used for chemical analysis. The optical path through the sample is approximately 18 mm. The instrument containing the photo­

metric color filters is adjusted and standardized as a complete unit, so th a t readings are the same on any of the instruments within the tolerance described below.

Approximately 1000 samples of oil have been used, rep­

resenting a wide variety of crude source, and of method of refinement. M any of these samples were carefully chosen to illustrate extremes of viscosity index and of treating, but the m ajority were merely chosen a t random from the samples passing through the laboratory for routine testing. The preliminary work consisted of measuring fifty oils, using ten narrow-band glass filters, with dominant wave length ranging from 390 to 660 m,u.

Re f e r e n c e St a n d a r d. For such measurements, the color­

imeter m ust be set to some standard reading. This necessi­

tates the use of a standard reference liquid, preferably as light or lighter in color than any of the samples. Since the range of measurement was to include th a t covered by the Saybolt chromometer, a generally available water-white liquid of reproducible color was sought.

For closest similarity to the samples to be measured, a hydro­

carbon solvent was indicated. Xylene, toluene, and mineral spirits of various distillation ranges were studied. The colors were found to vary appreciably with redistillation, distillation over caustic, acid treatm ent, clay treatm ent, etc., and after such treatm ents, the colors changed on storage. Consequently, a hydrocarbon standard would require carefully specified prepara­

tion, a t short time intervals. Distilled water, however, is easily prepared, and is stable and reproducible and was, therefore, chosen as the standard. The colorimeter was set to a scale read­

ing of 100.0 per cent transmission with water in the cell, with any filter in the light path.

No r t h Sk y Fi l t e r. Twenty-two oils, of widely varying origins and methods of refinement, were submitted to the Electrical Testing Laboratories for measurement on a Hardy spectrophotometer. The North Sky filter also was measured.

The spectrophotometric data were handled by the methods described by H ardy (5), using the 30 selected ordinates.

The N orth Sky filter was found to have the following char­

acteristics :

T rich ro m a tic C oefficien ts x - 0 .2 7 6 6 y = 0 .3 3 0 5 z - 0 .3 9 2 9

The filter described by these data is for use with a 15-c. p., tungsten bar filament bulb, operating a t 3100° K. behind a heat filter. The photocell is of the barrier-layer type and the optical path is shown by Diller (4). I t cannot be over­

emphasized th a t the instrum ent m ust be standardized as a complete unit rather than through standardization of the filter. The procedure for checking the standardization is described below.

The tristimulus values calculated from the spectrophoto­

metric curves of the 22 oils are given in Table I, which also indicates the nature of each oil sample, and gives the photo­

electric color or N orth Sky reading. Columns R and V are readings obtained with other filters, described below.

Photoelectric Color Oil

T a b l e I.

S p e ctr o p h o to m ete r E a c h V alu e X 100

N o . N a tu r e X Y Z

1 N a p h th c n ic 1 .7 0 . 7 4 0 . 0

2 H e a v y c la y 2 . 3 1 .0 0 . 0

3 C om p o u n d ed 2 . 4 1 .0 0 . 0

4 P e n n s y lv a n ia 8 . 3 3 . 8 0 . 0

5 A cid , m id -c o n tin en t 7 . 4 3 . 9 0 . 0

6 P e n n sy lv a n ia 1 1 .6 5 . 8 0 . 0

7 N o . 14 + b la ck oil 8 . 4 6 .2 0 . 2

8 N a p h th e n ic 1 1 .1 6 . 7 0 . 0

9 S o lv e n t-P e n n s y l- 1 9 .3 1 0 .9 0 . 6 10

v a n ia

A cid -n a p h th en ic 3 4 .7 3 0 . 4 0 . 6

11 S o lv e n t, c la y 4 2 .9 3 6 .2 0 . 4

12 C om p o u n d ed 4 4 .8 4 0 .7 1 .2

13 A cid , m id -co n tin en t 5 2 .8 4 7 .9 1 .9 14 A cid , m id -co n tin e n t 5 0 .7 5 0 .0 3 . 8 15 S o lv e n t, m id -c o n ti­ 5 0 .6 . 5 4 .9 8 . 7 16

n en t

N a p h th e n ic 6 5 .4 7 2 .6 1 0 .6

17 N a p h th e n ic 6 6 .3 7 5 . 0 1 8 .8

18 S o lv e n t, m id -c o n ti­ 7 1 .4 7 7 .5 4 0 .4 19

n en t

N a p h th e n ic — h e a v y a cid

N a p h th e n ic — h ea v y cla y

K erosen e

7 8 .1 8 3 .8 7 1 . 0

20 7 5 . 0 8 3 .9 4 6 .3

21 8 8 . 2 9 0 .3 1 0 5 .5

22 W h ite oil 8 8 .4 9 0 . 4 1 0 6 .2

R

10.0 1 3 .0 1 2 . 0 3 3 . 0 2 7 . 0 4 2 . 0 20.0 3 4 .0 5 6 .5 7 0 .0 8 1 .0 8 4 .0 8 9 .5 8 4 . 0 8 8 . 5 9 7 .0 9 9 .0 9 7 . 0 100.0 100.0 101.0 101 .0

AT. s.

1. 1 1 .9

1 .3

5 . 5 5 . 0 8 . 0 1 0.0

8 . 5 1 4 .0 3 5 . 0 4 0 . 0 4 5 . 0 5 2 . 0 5 4 . 0 6 2 . 0 7 6 . 0 8 0 . 0 8 1 .0 9 5 . 0 9 0 . 0 102 .0 10 2 .0

0 0 0 0.8 0 . 3 0 . 8 0 . 6 0 . 3

1 . 1

0 . 8 0 . 9 1.0 2 . 0

2.0

3 . 9 3 . 0 6 . 5 20.0 4 4 . 0 2 3 . 0 1 0 0 .0 100.0

T ristim u lu s V a lu es A' - 0 . 3 7 6 8

Y » 0 .4 5 0 2 Z = 0 .5 3 5 1

D o m in a n t w a v e le n g th 49 6 R e la t iv e b rig h tn ess

E x c ita tio n p u r ity 1 1 .5 %

The Y tristimulus value is identical with relative bright­

ness, or visual efficiency, commonly referred to as brilliance.

The spectrophotometric response of the instrum ent with the North Sky filter in position is similar in shape to the Y stimulus. The N orth Sky readings were plotted against the Y values as shown in Figure 1. Photoelectric color is seen to be directly related to Y:

Brilliance = 0.9 X photoelectric color

Distilled water is used as the standard for photoelectric color, whereas brilliance is based on a pure, theoretical white.

The brilliance of distilled water is approximately 90 per cent, accounting for the factor 0.9 in the above equation.

Re d Fi l t e r. Petroleum oils have the peculiar property of varying in the relation between brilliance, hue, and satura­

tion in a substantially fixed manner and only one other param­

eter—to determine the steepness of the transmission curve—

is required. The parameter could be similar to either X or Z.

The Z values, as shown in Table I, remain very small until the brilliance exceeds 50 per cent (Union No. 2 L/ 2) while the X values are of conveniently measurable magnitude over the entire range with the same liquid stratum used for the N orth Sky measurement. Consequently, red or orange glasses were preferred.

Dyes of various colors were also added to the oils to give products whose colors differed intentionally from those of normal petroleum products. One of the filters of this series was found to be most satisfactory in distinguishing between all of these samples. Oils which were measured had vis­

cosity indices approximating 0 and 100.

The spectral absorption of water is reasonably uniform

610 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 14, No. 8

X - T R IS T IM U L U S VALUE

Fi g u r e 2 . Co n v e r s i o n Ch a r to p Re d Re a d i n g st oX

insufficient spread and m ust be “magnified” . This may be done by a substantial increase in sample depth. However, this would involve other factors such as slight turbidity and fluorescence, which would lead to error. Another means of magnification of the spread lies in the use of a violet filter which in this range of light colors results in readings parallel to N orth Sky readings but of greater spread. The latter means is preferable. The filter was prepared so th a t for kerosenes in the Saybolt range the instrum ent gave exactly 10 times the sensitivity as with the N orth Sky filter. This filter is designated as the violet filter.

The violet filter used has the following characteristics:

T ristim u lu s V a lu es A’ » 0 .0 6 2 2

Y = 0 .0 0 4 8 Z - 0 .3 2 2 G

T rich r o m a tic C o efficien ts x » 0 . 1 5 9 7 y - 0 . 1 0 2 3

2 = 0 . 8 2 8 0 D o m in a n t w a v e le n g th 4 4 6 ta p R e la t iv e b rig h tn ess 0 .4 8 % E x c ita tio n p u r ity 1 00%

The spectrophotometric curve of the violet filter corre­

sponds roughly to the Z stimulus, as is shown in Figure 4,

throughout the visible region except a t the extreme red end (greater than 700 myu) where the absorption increases. Thus, in this region of the spectrum, the use of water as the standard results in readings which are higher than the corresponding readings a t 610 mjt» by too great a difference. The oils them­

selves also sometimes exhibit slight absorption peculiarities in this region, so th a t anomalous results m ay be obtained. A consideration of these and the other factors led to a choice of 610 mju as the average response equivalent of the instrum ent with the R filter. The characteristics of the particular filter used in order to have an instrum ent response equivalent to 610 mp. is:

T ri9 tim u lu s V a lu es X « 0 .1 0 3 9

Y - 0 .0 4 4 7 Z “ 0 .0 0 0 0

T ric h r o m a tic C o efficien ts x « 0 . 6 9 9 2 y - 0 . 3 0 0 8 2 = 0.0000

D o m in a n t w a v e le n g th 6 2 4 m p R e la tiv e b rig h tn ess 4 .4 % E x c it a t io n p u r ity 100%

Readings taken with the instrum ent when using this filter are shown in Table I under R where the correspondence to X stimulus m ay be observed. The red filter readings of Table I were plotted against the respective X values. The resultant curve (Figure 2) shows the relationship of R readings to X values.

R e l a t i o n b e t w e e n N o r t h S k y a n d R R e a d i n g s . Ap­

proximately 300 oils have been measured with both the N orth Sky and red filters, in order to establish the relation between the two readings. Since oils containing blooming or deblooming agents must be excluded from this work, only oils of known origin and treatm ent were used. This limited the choice of samples. Figure 3 shows this variation, the two lines denoting the widest variation found. I t is possible th a t oils from unusual sources or methods of treatm ent will be encountered which lie outside this lens; but, it is not to be expected th a t such samples will change the essential narrow­

ness of the lens. An average line is drawn through the lens, so th a t the R readings can be reported as plus or minus de­

viations from normal.

In general, oils of low viscosity index lie near the lower line. However, the method of refinement also affects the position, acid treatm ent tending to move the color toward the upper line, and clay treatm ent toward the lower.

V i o l e t F i l t e r . The Saybolt range ( — 16 to + 3 0 + ) corresponds to N orth Sky readings of 96 to 100. This is an

Fi g u r e 3 . No r m a l De v i a t i o n o f R

Fi g u r e 4 . Co n v e r s i o n Ch a r to f Vi o l e t Re a d i n g sto £