Industrial and Engineering Chemistry : analytical edition, Vol. 12, No. 3

INDUSTRIAL ^{a n d} ENGINEERING CHEMISTRY

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

I -«¡'tv'

HARRISON E. HOWE, EDITOR « ISSUED M A R C H 15, 1940 » VOL. 12, NO. 3 m CONSECUTIVE NO. 6

R a p i d D e t e r m i n a t i o n o f O x y g e n i n S t e e l . L. Singer 127

I b o n Abc a s S t a n d a r d S o u r c e f o r S p e c t r o c h e m i c a l A n a l y s i s ...Morris Slavin 131

Em p i r i c a l Me r c u r i m e t r i c Me t h o d f o r Zi n c...

Albert C. Titus and Jack S. Olsen 133

D e t e r m i n a t i o n o f P y r e t h r i n I ...

Clarence S. Sherman and R obert Herzog 136

D e t e r m i n a t i o n o f S i l i c a a n d R²0³ i n P o r t l a n d C e m e n t . . . . Lyle R. Dawson and Ralph V. Andes 1 3 8 T o x i m e t r i c M e t h o d f o r O i l - S o l u b l e W o o d P r e s e r v a ­

t i v e s ...Ernest E. H ubert 1 3 9 W e i g h i n g B o t t l e ...W . A. Taebel 141

De t e r m i n a t i o n o f St a r c h i n Pl a n t s...

W. Z. Hassid, R. M. McCready, and R. S. Rosenfels 142

De t e r m i n a t i o n o f Tu n g s t e n ...

M. L. H olt and Allen G. Gray 144

IonO FL U O H ID E M ETH O D FOR D ETER M IN A TIO N OF C O P PE R

William R. Crowell and Alan T. Spiher 147

De t e r m i n a t i o n o f Ch l o r o p h y l l a n d Ca r o t e n e i n Pl a n t Ti s s u e...

H. G. Petering, W. Wolman, and R. P. H ibbard 148

Fl u i d i t y o f Co t t o n i n Di m e t h y l Di b e n z y l Am m o n i u m Hy d r o x i d e...

W. Walker Russell and Norman T. Woodberry 151

NTe w Ap p l i c a t i o n s o f Si l v e r Re d u c t o r...

N athan Birnbaum and Sylvan M. Edmonds 155

St i l l f o r Pr o d u c i n g Me t a l- Fr e e Di s t i l l e d Wa t e r .

J. S. McHargue and E. B. Offutt 157

T e n - L i t e r V o l u m e t r i c F l a s k . . . Francis J. Reithel 159

R e d u c t i o n o f S p e c i f i c G r a v i t y a t 25°/25° C. t o D e n s i t y a t A n y T e m p e r a t u r e f r o m 0 ° t o 4 0 ° C. . .

R. R. Dreisbaeh 160

A n a l y s i s o f F r e e S o d i u m C y a n i d e i n B r a s s P l a t i n g S o l u t i o n s . Wallace M. M cNabb and Samuel Heiman 161

Se p a r a t i o n o f Ca d m iu m f r o m Zi n c...

F. E. Townsend and George N. Cade, Jr. 163

Ra p i d De t e r m i n a t i o n o f Ph o s p h o r u s i n Li n s e e d Oi l b y Ox y g e n Bo m b...

George T. Piercy, Edwin K. Plant, and M. C. Rogers 165

Nu l l- Ty p e Ph o t o e l e c t r i c Sp e c t r o p h o t o m e t e r . . .

Charles J. Barton and John H . Yoe 166

As s a y f o r Pl a t i n u m Me t a l s i n Or e Co n c e n t r a t e s .

John Seath and F. E. Beamish 169

D r o p p i n g E l e c t r o d e w i t h C o n s t a n t H e a d o f M e r ­ c u r y ...E. F . Mueller 171

F l o w D i v i d e r f o r G a s e s . . . . Johannes H . Bruun 172

A l l - G l a s s B a l l V a l v e S t i r r e r . . . Silvester Liotta 173

Al l- Gl a s s St i l l w i t h Au t o m a t i c Fl o a t Fe e d . . . .

George F. Liebig, Jr. 174

M a g n e t i c S h a k i n g D e v i c e ... S . Kiyomizu 174

Mi c r o c h e m i s t r y :

De t e r m i n a t i o n o f Sa t u r a t e d Hy d r o c a r b o n s . . .

E. Berl and W. Koerber 175

D e h y d r o g e n a t i o n a n d N i t r a t i o n o f H y d r o c a r b o n s o f C y c l o p e n t a n e S e r i e s . E . Berl and Regis Raab 177

C e r i m e t r i c D e t e r m i n a t i o n o f S m a l l A m o u n t s o f A r s e n i c ...I. M. Kolthoff and Elias Amdur 177

Im p r o v e m e n t si n De t e r m i n a t i o no f Io d i n ei n Bl o o d

Albert L. Chaney 179

Si m p l e Ph o t o e l e c t r i c Mi c r o d e n s i t o m e t e r . . . .

M. Spiegel-Adolf and R. H. Peckham 182

Se a l a b l e Ab s o r p t i o n Mi c r o t u b e ...

Arthur N. P rater 184

Mo d e r n La b o r a t o r i e s:

C h e m i c a l R e s e a r c h L a b o r a t o r y o f E t h y l G a s o l i n e C o r p o r a t i o n ...Harold A . B eatty 185

T h e A m erioan C hem ical Society assum es no resp o n sib ility fo r th e statem e n t« a n d opinions a d v an c e d b y co n trib u to r» t o its pu b licatio n s.

22,900 copies of th is issue p rin te d . C o p y rig h t 1940 b y A m erican C hem ioal Sooiety.

P u b l i c a t i o n O ffice : E d i to r ia l O ffice : R o o m 706, M ills B u ild in g , W a s h in g to n , D . C .

T e le p h o n e : N a t i o n a l 0848. C a b le : J i e c h e m ( W a s h in g to n )

P u b lish e d b y th e A m erioan C hem ical Sooiety, P u b lic a tio n Office, 2 0 th &

N o rth a m p to n S ts., E a s to n , P e n n a . E n te re d aa second-class m a tte r a t th e P o st Office a t E a s to n , P e n n a ., u n d e r th e A ct of M a rc h 3, 1879, as 24 tim e s a y e ar. In d u s tria l E d itio n m o n th ly on th e 1 st; A n a ly tic a l E d itio n m o n th ly on th e 15th. A cceptance fo r m ailin g a t sp ecial ra te of p o stag e p ro v id ed for in S ectio n 1103, A ct of O cto b er 3, 1917, a u th o riz e d J u ly 13, 1918.

A n n u al s u b sc rip tio n ra te , In d u s t r i a l Ed i t i o n a n d An a l y t i c a l Ed i t i o n

sold on ly as a u n it, $4.00. F o reig n p o stag e to c o u n tries n o t in th e P an

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

A d v e rtis in g D e p a r t m e n t : 332 W e s t 4 2 n d S t r e e t , N evr Y o rk , N . Y.

T e le p h o n e : B r y a n t 9-4430

A m erican U n io n , $2.25; C a n a d ia n p o stag e, $0.75. Single copies: In d u s tria l E d itio n , $0.75; A n a ly tic al E d itio n , $0.50. Special ra te s to m em bers.

N o c la im s can be allow ed for copies of jo u rn a ls lost in th e m ails unless such c la im s a re receiv ed w ith in 60 d ay s of th e d a te of issue, a n d no claim s will b e allow ed fo r issues lo st as a re s u lt of in sufficient n o tice of ch an g e of ad d ress. (T en d a y s ’ a d v an c e n o tice req u ire d .) “ M issin g fro m files”

c a n n o t b e accep ted as th e reason fo r h o n o rin g a claim . C h arle s L. P arso n s, Business M an a g e r, M ills B u ild in g , W ash in g to n , D . C ., U . S. A.

4 IN D U STR IA L AND E N G IN E E R IN G CH EM ISTR Y VOL. 12, NO. 3

E L E C T R I C H E A T T R E A T I N G F U R N A C E S • • H E A T I N G E L E M E N T A L L O Y S • « T H E R M O C O U P L E A N D L EAD 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 IX T UR E S • • S P A R K P L U G ELECT ROD 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 TU BES

BUY A FURN

T h e re ’ s a r e a s o n f o r H O S K IN S p artic u la r construction.

This FD-204 furnace w o j designed, Mr. Chemist, with your interests in mind.

Easy to get at to fix. Loosen Chromel heating unit terminals, remove 4 corner screws and front heat lifts off.

One piece muffle around which coiled Chromel units are easily wrapped In groove.

Two heavy Chromel coils In parallel, designed fo r one voltage only, pro­

vide most durable element.

Make one renewal and be done with it. "A chain is no stronger than its weakest link."

A delicately balanced sliding door, stays put in any position and thus conserves heat.

Insulation 4 1/2* thick all around. You can’t fry eggs on the top of this furnace. Economical on power.

• H o sk in s L a b o r a t o r y F u r n a c e s a r e d e s i g n e d a ro u n d no on e fe a tu re but w it h a ll f a c t o r s in p ro p e r b a l a n c e to m a k e them of m o st v a l u e to y o u . T h e s e b e n e fits a r e : d u r a b le C h ro m e l e lem en ts . . . h ard to w e a r out but e a s y to r e n e w ; a r e l a t iv e l y cool f u r n a c e c a s e f o r com fo rt a n d e c o n o m y ; a f u r n a c e th at d e l i v e r s the g o o d s month in a n d month out to y o u r c o m p le te s a tis f a c t io n . B u y from y o u r d e a l e r ’ s stock . . . H oskins M a n u fa c t u r in g C o m p a n y , Detroit, M ich.

W e have a handy little gadget, called a Heating Unit Calculator, that tells how to moke coiled Chromel units o f 275 to 1,000 watts. Glad to give you one.

This shows fhe F D -2 0 4 assem bled. H e a tin g ch am be r, 73/8" x 51/4* x 14".

H O S K I N S P R O D U C T S

ANALYTICAL E D IT IO N S

A tru e D o u b le M o n o c h ro m a to r S p e c tr o p h o to m e te r fo r u se w ith y o u r C o lem a n p H E le c tr o m e te r

Features of

Spectrophotometry

Presented in the new Colem an D M S Handbook

R ationalize Color C hem istry! Specify Color in Usable Terms!

Q uantitative Color Chem istry is fundam entally a very rapid and precise analytical procedure, but these advantages are not realized unless the deter­

m ination is m ade w ith m onochrom atic lig h t and un­

less, also, In ten sity is precisely m easured. T h ese conditions are n o t m et by “colorim eters.”

T h e n ew Colem an D ouble M onochrom ator Spec­

trophotom eter develops pure spectral lig h t in band w idths as narrow as 5 mmu, w ith an accuracy of 1 m m u, and utilizes a Coleman pH E lectrom eter to concurrently m easure ligh t intensity to 0.1%.

T h is com bination of spectral precision and excel­

len t In ten sity accuracy results in precise, reproduc­

tible data and offers Chemical Spectrophotom etry as an ex a ct science. M oreover, the data are in fun­

dam ental units— independent of lig h t sources, fil­

ters and th e color sen sitivity of the o b se r v er —<

rational.

Precise and practicable color specifications are e s­

sential to accurate process control; dyes, plastics, p h a r m a c e u t i c a ls , beverages, oils and various chem ical com pounds all present a basic color prob­

lem. T o be of real value color specifications can only be expressed in the absolute units of W a v e ­ len gth and per cent T ransm ittance.

T h e Coleman D ouble M onochrom ator Spectro­

photom eter in conjunction w ith the Colem an pH E lectrom eter constitute an inexpensive com bina­

tion for precise color expression in these absolute terms.

T h e sim plicity and precision o f th e Spectral T rans­

m ittance curve as an ex a ct color expression and the practicability of the Colem an D M Spectrophotom ­ eter as an industrial to o l is now a proved fact, w ell w orthy of your investigation.

T h is c o m b in a tio n o f a C o lem a n p H E le c tr o m e te r a n d D M S p e c tr o p h o to m e te r offers S p e c tr o p h o to m e tr y fo r th e fir st tim e as a s im p le m e a n s fo r s p e c ify in g co lo r a n d for e x a c t A n a ly tic a l C h e m is tr y . T h is a c h ie v e m e n t is a tta in e d w i t h o u t sacrifice o f s ig ­ n ific a n t a ccu ra cy, w ith s im p le , r u g g e d in s tr u m e n ts a n d a t a re a so n a b le p r ic e . T h e D M S H a n d b o o k illu s tr a te s ty p ic a l co lo r sp e c ific a tio n cu rves a n d in d ic a te s th e s u p e rio r a n a ly tic a l p r e c is io n p o s s ib le w h e n B eer’s a n d L a m b e r t’s L a w s are s tr i c t l y m e t . W r ite for y o u r c o p y o f th e D M S H a n d b o o k .

COLEMAN ELECTRIC CO., INC.

3 1 2 M adison St. M ayw ood, 111.

6 IN D U STR IA L AND E N G IN E E R IN G CH EM ISTR Y VOL. 12, NO. 3

CONSTANT TEMPERATURE

Automatically Controlled and Always Dependable

TTTTHEN y o u b u y a “ P re o isio n -F re a s” c o n s ta n t te m p e r a tu r e

* ■ c a b in e t y o u c a n be s u r e of a c c u ra te te m p e r a t u r e c o n tro l a n d a b s o lu te p e rfo rm a n c e d e p e n d a b ility b e c a u se every “ P re cisio n - F re a s ” c a b in e t c a rrie s a 5 -y ea r g u a ra n te e , a p p ly in g to b o th h e a t ­ in g e le m e n ts a n d t h e r m o s ta t . T h o u s a n d s of la b o ra to rie s all over th e w o rld a re now u s in g “ P re c is io n -F re a s ” c a b in e ts . If yo u hav e a c o n s ta n t te m p e r a t u r e p ro b le m , b y a ll m e a n s in v e s ti­

g a te w h a t “ P re c is io n ” h a s to offer you.

M any standard models to choose from

S en d for yo u r copies o f N E W B U L L E T I N S

J u s t o ff th e p re ss are tw o n e w b u lle ­ tin s , c o n ta in in g a w e a lth o f va lu a b le in fo r m a tio n o n th e s u b je c t o f c o n ­ s t a n t te m p e r a tu r e la b o ra to ry e q u ip ­ m e n t. W rite f o r y o u r co p y o f o n e or b o th , i f y o u are e v en r e m o te ly c o n ­ ce rn e d w ith th e s u b je c t o f c o n s ta n t te m p e r a tu r e .

B U L L E T IN 305

E ig h t p a g es o f a u th e n tic d a ta o n th e fa c to r s w h ic h in flu e n c e c o n s ta n t t e m ­ p e r a tu r e c o n tro l, w i th in te r e s tin g d ia ­ g ra m s o f g ra v ity a n d m e c h a n ic a l c o n ­ v e c tio n h e a t tra n sfe r.

M o c h a n ic a l c o n v e c ­ t i o n o v e n s, s t e r i l i z ­ e rs , c o n d i tio n in g c a b i n o ts , i n se v e ra l s iz e s a n d ty p e s .

M o c h a n ic a l c o n v e c ­ t i o n w e t a n d d ry i n c u b a t o r s , h u m i d ­ it y c a b i n o ts , a g in g o v e n s.

B U L L E T IN 310

D eta ile d c o m p re h e n siv e in fo r m a ­ tio n o n th e fe a tu r e s o f c o n s tr u c tio n a n d re la tiv e a d v a n ta g e s o f s ta n d a r d g ra v ity a n d m e c h a n ic a l c o n v e c tio n o ve n s. I n fo r m a tio n , to o , o n n ew ve rtica l ovens a n d H a za rd -S a fe m o d e ls.

G r a v ity c o n v e c tio n v a c u u m o v e n s, 2 s iz e s a n d 2 t e m ­ p e r a t u r e ra n g e s .

G r a v ity c o n v e c tio n o v e n s, i n c u b a t o r s , s te r iliz e r s , h u m i d ­ it y c a b i n e ts . S e v ­ e r a l s iz e s a n d ty p e s .

NEW V E R T I C A L M O D E L S

HAZARD-SAFE EQUIPMENT

L a te s t d e v e lo p m e n t in m e ­ c h a n ic a l co n v e c tio n c o n s ta n t te m p e r a t u r e c a b in e ts a re th e n ew “ P re c is io n -F re a s ” v e rti­

cal m o d e ls w h ic h r e s t d ire c tly o n th e floor. T h ese m o d e ls conserve b e n c h space, offer a d d e d co n v e n ie n ce in lo a d in g a n d u n lo a d in g , p lu s every o th e r i n h e r e n t f e a tu re of

“ P re c is io n -F re a s ” m e c h a n i­

c a l co n v e c tio n h e a t tr a n s f e r.

F o r h a n d l i n g in f l a m m a b l e o r ex p lo siv e m a t e r i a l s , o r o p e r a t i n g i n a h a z a r d o u s a t m o s p h e r e , w e c a n s u p p l y e q u i p m e n t i n ­ c o r p o r a t i n g p r o te c tiv e f e a t u r e s , a s fo llo w s : A ll w ir in g i n e x p lo s io n -s e a le d c o n d u i t ; a ll e le c tr ic a l c o n t r o l s In e x p lo s iv e -p ro o f h o u s ­ in g s —U n d e r w r i t e r s ’ a p p r o v e d ; h e a t e r s a re a ll-w e ld e d —n o b o l t s o r s c re w s t o lo o s e n , c o rro d e , o r a r c ; a ll t e r m i n a l s a n d h e a t e r m o u n t i n g s i n s u l a t e d a g a i n s t g r o u n d s a n d s h o r t s ; la rg o p o r t s i n s u r e c o m p le te ex­

h a u s t o f v a p o r s ; s a f e ty s w i t c h d is c o n n e c ts h e a t e r s w h e n d o o r is o p e n e d . W r ite f o r B u l l e t i n 310.

L . ___________________________________________________________________________________________________ A

¡PÍRÍKOÍMDMM PRECISION SCIENTIFIC COMPANY Designers and Builders of Modern Laboratory Equipment

1730-34 NORTH SPRINGFIELD AVE.. CHICAGO. ILLINOIS. U. S. A.

. . . .

u

M ARCH IS, 1940 ANALYTICAL E D IT IO N

EXTENDS TO THE OF EACH PIECE OF GLASSW ARE

K im b le superiority in fin e Labora- carton in w h ich it is packed.

Here, a gain , n o th in g is le ft to chan ce. Sturdy O U TE R sh ip p in g cases—com p act in d ividu al INNER cartons, p la in ly labeled for id e n ­ t i f i c a t i o n - i n g e n i o u s p r o te c tiv e sh ield s w ith in th e INNER cartons

— all co m b in e to offer th e m axi­

m u m in p ro tectio n an d con ven i­

en ce to th e con sum er.

Even after th e large o u ter sh ip ­ p in g carton is broken o p en , th e han d y U N IT CONTAINERS afford co n v en ien t sh e lf storage for each p iece o f glassw are—ready for im ­ m ed ia te u se , y e t protectively car­

to n ed for safety, clea n lin ess and econ om y o f sp a c e !

Standardize on K im b le Labora­

tory Glassware.

S to c k ed b y leading L a b o ra to ry S u p p ly H ouses th ro u g h o u t th e U n ited

S ta te s a n d Canada

© 1?40, KIMBLE GLASS CO.

The V ifiblt (iuarantee of Invisible Quality

KIMBLE GLASS C O M P A N Y

V I N E L A N D , N . J .

D E T R O I T * * 8 O S T O N

8 IN D U STR IA L AND E N G IN E E R IN G CH EM ISTR Y VOL. 12, NO. 3

!» L ^ a a m L u m

C E N C O S Y M M E T R I C A L J A W C L A M P S

W I T H C O A X I A L AD J US T I NG NUT

The Cenco Symmetrical Jaw Clamps, designed and produced in the Cenco shops, are an example of the application of mod­

ern facilities to the manufacture of an old device in a new form for greater convenience and utility. In addition to the im­

proved design, complete finishing with cadmium-plating pro­

vides a longer life of pleasing appearance. Cadmium plating is the most resistant of any of the common finishes under con­

ditions of use in the chemical laboratory.

12097

12102 SYM M E TR IC A L J A W BU RE TTE CLAM P, Rod Type, for objects up to 50 mm diameter with 10 mm rod, 15 cm long. Finished in cadmium plate. Length, over all, 23 cm... Each $0.28 SYM M E TR IC A L J A W BU R E TTE CLAMP, Screw Clamp Type, same as No. 12097 Clamp, but with swivel support rod clamp instead of straight rod.

Length, over all, Id1/» cm... Each .30 SYM M E T R IC A L J A W CONDENSER CLAM P, Single V-Jaw, Rod Type, for holding larger objccts than No. 12097 Clamp. Has one V-shape jaw with compressor member. With 10 mm rod, 15 cm long.

Finished in cadmium plate. Length, over all, 25 cm.

... Each .40 12102

12136

12136

12137 SYM M E TR IC A L JA W CONDENSER CLAM P, Double V-Jaws, Rod Type, same as No. 12136 Clamp, but with two V-shaped jaws. With 10 mm rod, 15 cm long. Finished in cadmium plate. Length, over all, 25 cm... Each .45 SYM M E TR IC A L J A W CONDENSER CLAMP, Single V-Jaw, Screw Clamp Type, same as No. 12136 Clamp, but with swivel support rod clamp instead of straight rod. Length, over all, 19 cm ..Each .45

12138

12137

SYM M E TR IC A L J A W CONDENSER CLAM P, Double V-Jaws, Screw Clamp Type, same as No.

12138 Clamp, but with two V-shaped jaws. Length over all, 19 cm... Each .50

L A B O R A T O R Y A P P A R A T U S S C I E N T I F I C

IN S T R U M E N T S

12139

Boston • C H IC A G O ♦ Toronto Los Angeles CHICAGO

1700 Irving Pk. Blvd.

BOSTON 79 A m h erst St.

ANALYTICAL E D IT IO N 9

“Super-Purity ’ ’

A c h ie v e d by M allin ckrod t Research

. . . ALUMINUM CHLORIDE ANHYDROUS A . R.

Pure White Cleanly Soluble

No longer need you work with an Aluminum Chloride Anhydrous which is off-color and gives turbid solutions. Mallinckrodt Research has produced this Analytical Reagent as a pure white powder which is outstanding for its

“super-purity” as evidenced by the clarity of its solutions. Iron has been lowered to the maximum limit of 0.002%, H eavy Metals (as Pb) 0.001%, and Sulfate 0.002%.

Use this improved reagent in your laboratory and note its definite superiority. Send for the Mallinckrodt Catalog of Analytical Reagents where the Maximum Limits of Impurities for nearly 500 other chemicals are published.

ST. LOUIS CHICAGO

c ^{W O R K S}

NEW Y O R K

PHILADELPHIA

10 IN D U ST R IA L AND E N G IN E E R IN G CH EM ISTR Y VOL. 12, NO. 3

gStS

A STORY OF

RESEARCH IN GLASS

THE HISTORY A N D DEVELOPMENT OF ? G R O U N D J O I N T S

IN AMERICA

C o R N I N G G^{l a s s} W O R K S h a s p r e p a r e d a n in f o r m a ­ tiv e b o o k l e t o n th e h is to r y , f a b r ic a tio n a n d u se o f S ta n d a r d T a p e r W a r e .

T o th e l a b o r a t o r y h e a d , te a c h e r , c h e m is t— to a n y o n e u s in g , o r c o n t e m p l a ti n g u s in g , S ta n d a r d T a p e r ( T ) G r o u n d J o i n t s —•

th is in s t r u c tiv e b u lle tin w ill s o o n b e a v a ila b le w i t h o u t c h a r g e . T h e firs t e d i tio n is n e c e s s a r ily lim ite d . Y o u a r e u r g e d , if in te r e s te d , to s e n d f o r y o u r fre e c o p y to d a y . P le a s e u s e c o u ­ p o n b e lo w .

C o rn in g G l a s s W orks, C o rn in g , N. Y .

P le a s e s e n d a F R E E c o p y o f y o u r n e w b o o k l e t , " T h e E v o lu tio n o f S ta n d a r d T a p e r G r o u n d J o i n t s ” to :

Name_____________________________________________________________________________

Position_

S C H O O L , C O M P A N Y , H O S P I T A L , E T C .

Address_

T H I S C O U P O N B R I N G S Y O U Y O U R F R E E C O P Y

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

“P Y R E X ” is a registered trade-m ark a n d indicates m an u fa ctu re by

C ORN ING GLASS WORKS . C O R N I N G , N. Y.

o n e o f w h ic h w a s e x a c tly lik e " A . ” T h e s e c o n d clay o f

" B ” e v id e n tly w a s n o t a c tiv a te d by th e s a m e tr e a tm e n t as th e first a n d c o n t r i b u te d little , if a t a ll, to th e c la r if y ­ i n g a c tio n . T h u s , " B ” h a d to b e r e je c te d , o r b o th c o n ­ s titu e n ts a c tiv a te d s im u lta n e o u s ly if it w a s to b e o f an y v alu e in th e p r o c e s s .

T h i s is b u t o n e o f h u n d r e d s o f c a s e s in w h ic h th e G -E X R D U n it h a s h e lp e d s o lv e m a n u f a c tu r in g p r o b ­ le m s . I t o f te n s h o w s h o w le s s c o s tly m a te r ia ls c a n b e u s e d to r e d u c e p r o d u c t i o n c o s ts a n d s till p r o d u c e a b e t te r p r o d u c t. I f y o u ’r e h a v in g " t w i n ” p r o b le m s in y o u r p la n t, y o u r o w n p r o c e s s e s m a y b e n e fit f r o m a s t e p ­ w is e a n a ly s is by x -ra y d if fr a c tio n . I n v e s ti g a te th e G -E X R D U n it, to d a y . F o r c o m p le te d a ta o n th is m o d e r n m e th o d o f a n a ly s is , a d d r e s s y o u r r e q u e s t to D e p a r t ­ m e n t I 9 3 .

GENERAL @ ^ELECTRIC

X -R A Y C O R PO R A T IO 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 .

"T V /T A N , d o w e e v e r ca u se c o n f u s io n a r o u n d o u r h o u se ! M e , I a lw a y s g e t in d u tc h , a n d h im , h e ’s a lw a y s s o g o o d th a t e v e ry b o d y w o n d e r s w h a t ’s th e m a tte r w ith m e . T h e t h in g th a t b o th e r s ’e m is: ‘H o w c a n th e y b e tw in s in ev ery w ay e x c e p t th e i r b e h a v io r ? ’

" W e ’r e n o p r o b l e m to th e h e a d m an! H e says w e ’r e ju s t lik e s o m e clay h e h a d tr o u b le w ith a t th e p la n t.

H e c a lls us 'A ' a n d 'B ’ lik e th e clay s a m p le s . M e , y o u m ig h t k n o w , I ’m rB ’.”

T h e clay s a m p le s s e e m e d to b e " t w i n s .” T w i n s in a p p e a r a n c e ; tw in s in c h e m ic a l a n a ly sis; tw in s in p h y s ­ ic a l p r o p e r t i e s . T h e y lo o k e d a lik e — b u t th e y d i d n ’t a c t a lik e ! W h e n u s e d in e x a c tly th e s a m e m a n n e r as c l a r if y in g c la y s in th e p u r ific a tio n o f o il, " A ” b e h a v e d its e lf, w a s e x tre m e ly ac tiv e , w h ile " B ” w a s a lm o s t in e rt.

H e r e w a s th e p r o b le m : F in d th e d iffe re n c e s b e tw e e n th e s a m p le s to d e t e r m in e v a ria n t a c tio n c a u se s.

A n d th e G -E X R D U n it c o u ld d o it b e c a u s e it is n o t lim ite d by th e s a m e f a c to r s w h ic h r e s t r i c t c o n v e n tio n a l m e th o d s . X -ra y d if fr a c tio n p a t te r n s p r o v e d th a t " A ” c o n s is te d o f o n e c ry s ta l fo rm , w h ile " B ” c o n ta in e d tw o ,

12 IN D U ST R IA L AND E N G IN E E R IN G CH EM ISTR Y VOL. 12, NO. 3

A.H.T. CO. SP ECI FICATION

B U R E T T E C L A M P A N D S U P P O R T

CONSIS TING OF C L A M P OF N IC K EL SI LV ER AND SU PPORT WITH COORS PORCELAIN BASE AND ALUM INUM ROD

2515 Burette Support

(B urettes are not included.)

B U R E T T E S U P P O R T , A .H .T . C o . S p e c ific a tio n .

Consisting of nickel silver clamp and support with base of solid Coors porcelain, 14 X 6 inches—see detailed descriptions below.

Coors porcelain was chosen for the base because of its superiority in color, in resistance to heat and mechanical shock, and in stability toward the reagents in common laboratory use.

The clamp is provided with rubber covered jaws so shaped as to hold the burettes firmly without obscuring the graduations at any point.

CLAMP. For two burettes, stamped from nickel silver sheet, with reinforcing ribs to provide stability. Jaws will take burettes—or other tubing—from 10 mm to 18 mm diameter, i.e. burettes from ^{1 0} ml to ^{1 0 0} ml capacity.

Clamping arrangement provides firm attachm ent to vertical support rods from 10 mm to 13 mm diameter, with convenient adjustability for height.

Although nickel silver does not corrode, it tends to discolor after exposure to laboratory fumes. We therefore offer, in addition to the tool finish, a nickel plated and lacquered finish for reasons of perm anent appearance rather th a n for utility.

SUPPORT. W ith rectangular base of solid Coors porcelain, 14 inches long by

6 inches deep, with aluminum rod with “ Alumilite” finish, 24 inches high by 34-inch diameter. Base is provided w ith four rubber feet.

2515. B u re tte Support, A .H .T . Co. Specification, as a b o v e d escribed, w ith N o . 3225 C la m p of tool finish nickel silv er. W ith o u t b u re tte s sh o w n in illu s tr a tio n ... 4.50 C ode W o rd ... B iqic 2515-A. D itto , b u t w ith nickel p la te d C la m p N o . 3 2 25-A ... 4.75 C ode W o rd ... B iq k y

3225

Showing m ethod of quick attachm ent and release of Burette

3225.

3225-A.

9340-A.

B u re tte Clam p, A .H .T . Co. S p ecification, as a b o v e described, of nickel silv er, w ith to o l finish, i.e. w ith o u t n ickel p la tin g o r la c ­ q u e r ... 1.00 C ode W o rd ... Cuvok D itto , b u t nickel p la te d a n d la c q u e re d . . . 1.25 C ode W o rd ... Cuvre S u p p o rt, A .H .T . Co. S p ecification, w ith C oors

p orcelain b ase 14 X 6 inches, a n d a lu m in u m rod 24 inches high b y H -in c h d ia m e te r 3.50 C ode W o rd ... Olors 10?

154209

discount in lot, o f 10 £ m e caialogu<

100 ) num^cr on^V

TITRATION ASSEMBLY, A.H.T. Co. Speci­

fication. Recommended for a wide range of titrations where ease of manipulation, comfort of the operator and a high degree of precision are desired. Complete as shown in illustration with Clamp, 9340-A support, two Burettes 50 ml in V io th s , one Meniscus Reader and two Pyrex beakers, 250 ml.

2532. T itra tio n A ssem b ly , A .H .T . Co. S p ecification, as ab o v e d escribed, w ith N o. 3225 C la m p of to o l finish nickel s ilv e r... 18.90 C ode W o rd ... B ixsa 2532-A. D itto , b u t w ith N o . 3225-A C la m p , nickel p la te d a n d la c q u e re d ... 19.15 C ode W o rd ... B ixvu

Titration Assembly

( Complete w ith Burettes, M en iscu s Ileader, etc., as shown i n illustration.)

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

R E T A IL —W H O LESA LE— EX P O R T

LABORATORY APPARATUS AND REAGENTS

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

Cable Address, “Balance,” Philadelphia

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

Rapid Determ ination o f Oxygen in Steel

L. S IN G ER , T h e N aval Ite sc a rc li L a b o ra to ry , A n a c o stia , D. C.

A

C O N S ID E R A B L E am ount of work has been done on th e influence of oxygen upon th e properties of steel, b u t i t h as been hindered b y the lack of a simple, rapid m ethod for th e q u a n tita tiv e estim ation of oxygen. Several m ethods (8) have been used for th e determ ination of oxygen in steel and some give good results in th e hands of careful, experi­

enced analysts. However, all th e m ethods th a t have been used are too slow for practical use and m ost of them require considerable care in m anipulation.

I t is th e purpose of th is paper to show th e results obtained in th e d eterm ination of oxygen in steel by a nitrogen fusion m ethod. T his is so called because of its sim ilarity to the vacuum fusion m ethod, in th a t th e reduction of th e oxides is obtained b y graphite. In th e Vacuum fusion m ethod, re­

duction takes place in a vacuum a t a tem perature of abo u t 1600° to 1650° C .; whereas in th e nitrogen fusion m ethod, described below, reduction takes place in an atm osphere of nitrogen a t a tem perature of 1200° to 1250° C. In b oth m ethods th e oxygen in th e m etal (present as oxide in solu­

tion or oxide inclusions) is converted to carbon monoxide.

This gas m ay be analyzed either volum etrically or gravim et- rically. I n th e gravim etric m ethod th e gas is passed over h o t copper oxide for conversion of carbon monoxide to car­

bon dioxide, w hich is then absorbed in a weighed Ascarite tube. A com plete description of th e vacuum fusion m ethod has been given b y V acher and Jo rd an (4). T o obviate th e use of th e high tem pera­

t u r e e m p lo y e d in th e v a c u u m f u s i o n m ethod, various experim enters have used tin or antim ony or

G A S

Fi g u r e 1 . Sc h e m a t i c Di a­ g r a m o f Ox y g e n De t e r m i­

n a t i o n As s e m b l y D . A sc a rite to w e r

E . P a lla d in iz e d p u m ice to w er (40 0 -5 0 0 ° C.) O, P . C o p p e r o x i d e t o w e r s

(300° C.) / / . S u lfu ric acid b u b b le r K , Q. A n h y d ro n e tow ers M . Q u a rtz re a ctio n tu b e M '. G lass tu b e M n, G ra p h ite b u c k e t O. F il te r a n d a b so rp tio n tu b e R . S c h w a rtz a d so rp tio n tu b e 8 . A n h y d ro n e g u a rd tu b e T . F lo w m e te r

j

m ixtures of tin and antim ony to effect fusion of th e steel a t a lower tem perature. I n th e work described here, tin was used as th e fluxing agent. A m ixture of tin and antim ony in equal p arts b y w eight was also tried b u t found objectionable, as the antim ony vaporizes too readily a t th e te m p eratu re em­

ployed.

Purification of Nitrogen

T he steel sam ple was m elted in an atm osphere of pure nitrogen. T his gas was prepared by first analyzing a cylinder of nitrogen for its oxygen content and then blowing in h y ­ drogen in q u a n tity slightly greater th a n equivalent to th e oxygen found present. An analysis of a cylinder of gas pre­

pared as above showed 0.67 per cen t by volum e of oxygen and 1.51 per cent by volum e of hydrogen. B o th gases were subsequently rem oved b y passing first over palladinized pum ice (a t 400° to 500° C.) to rem ove oxygen and th e n over copper oxide (a t 300° C.) to rem ove th e excess hydrogen.

T he w ater formed was th e n ta k en o u t by suitable absorbents.

A read y supply of pure nitrogen was th u s always available during th e course of an analysis.

Description of Apparatus

The train used is shown in Figure 1. Gas from the nitrogen cylinder by-passes the mercury safety bottle, A . B is a 2-way

r

j

L

^{k =5=}

J

K

¥

,

!

«V.

g

0

■M"

M 127

128 IN D U STR IA L AND E N G IN E E R IN G CH EM ISTR Y VOL. 12, NO. 3 stopcock used for regulating the gas flow. C is a sulfuric acid

bubbler which helps the operator in the adjustm ent of gas flow rate. D is an Ascarite tower which absorbs any carbon dioxide th a t may be present. E is a tower of palladinized pumice (10- to

1 2-mesh) which is kept a t 400° to 500° C., where all the oxygen in the gas is converted to water by reacting w ith the hydrogen present. G is a tower of copper oxide, kept a t 300° C., which removes the excess hydrogen. F is a 3-way stopcock placed in the train to make it possible to convert the reduced copper of G back to oxide by passing oxygen or air over the heated copper.

A t the present writing this has not been necessary, although about 4.25 cu. meters (150 cu. feet) of gas have been passed through the system. H is a sulfuric acid bubbler whose function is to take out most of the w ater th a t has been formed in E and G, while K , a large Anhydrone tower, effects the final drying of the ni­

trogen before it enters the quartz reaction tube, M . L is a 2-way stopcock th a t is used to control the gas flow.

F 6 H O L E

!L _ ' / 6

2 / "

' 3 2

n>|VO 7 " _

8

Fi g u r e 2 . Gr a p h i t e Bu c k e t

flowmeter. All the connections from A to Q are glass. The rubber stopper in M presents no practical difficulty.

C o n d i l i o n i n g o f G r a p h i t e B u c k e t s

The bucket (Figure 2) is made of Acheson graphite (Grade AGR) rod. The handle (not shown) is tantalum wire 0.762 mm. (0.030 inch) in diameter and a new wire handle is used when­

ever a determ ination on a steel sample is made. The same bucket can be used for several determinations.

The graphite bucket m ust be conditioned before a deter­

mination for oxygen is made with it. I t is first burned out a t about 1000° C. in an ordinary muffle furnace for 15 minutes. I t is then suspended in the quartz reaction tube and the tube evacu­

ated. The graphite bucket is then brought to 1250° C. and kept a t this tem perature for one hour. A vacuum is maintained during the entire heating period. Heating is done by a water- cooled coil operating from a 3-kilowatt induction unit.

After this treatm ent the bucket is allowed to cool, 15.0 grams of Baker’s c. p . stick tin are added, and the bucket is returned to the quartz reaction chamber. The heating is again repeated as above, except th a t it is done in an atmosphere of nitrogen, and the tim e allowed is again 15 minutes. After the bucket and its contents have come to room temperature, they are stored in a desiccator. The bucket is now ready to receive the steel sample for analysis.

O p e r a t i o n o f T r a i n

W ith the Schwartz adsorption tube in place (It Figure 1) and gas flowing through the system, stopcock L is closed. This causes the gas to escape through the mercury safety, A . A conditioned graphite bucket containing the tin is now loaded w ith the steel sample, which is a solid cylinder, 1.59 cm. (0.625 inch) in diame­

ter, 0.95 cm. (0.375 inch) long, and weighing about 15 grams.

The bucket and its contents are then lowered into the reaction tube and stopcock N is turned for connection to the vacuum pump. The tube is evacuated for one minute, after which N is turned through an angle of 90°, thus leaving the quartz reaction tube, M , under vacuum.

The induction heater is now immediately put in operation and nitrogen is carefully adm itted through stopcock L until the reac­

tion tube contains gas a t slightly greater pressure than atmos­

pheric. This la tte r operation requires about 3 minutes. N is now turned so th a t gas flows through the entire train. The rate of gas flow is regulated by means of the needle valve on the ni­

trogen cylinder (not shown in figure), to about ^{2 0 0} cc. per minute.

The graphite bucket and its contents attain a tem perature of about 1200° to 1250° C. in a little less than ² minutes after the induction heater is turned on and are kept a t this tem perature during the entire run. Fifteen minutes from the time the in­

duction heater is started, the Schwartz adsorption tube, R, is re­

moved and weighed. Thus for the usual case, an oxygen de­

term ination is possible in less than ^{2 0} minutes.

M", the graphite reaction bucket, is more clearly shown in Figure 2. The bucket is suspended in M by means of a molyb­

denum or tantalum wire 0.762 mm. (0.030 inch) in diameter. This wire is in tu rn supported by another wire attached to a glass tube, M ', and supported thereon by means of two small glass hooks. M ' has a clear glass window a t its top to make optical pyrom eter readings possible. As shown in Figure 1, M ' passes through a rubber stopper which fits into the quartz reaction tube. The reaction tube is clear quartz and has a wall thickness of 1.587 mm. (0.0625 inch). The tube is 55 cm. ^{( 2 2} inches) long and the outside diameter is 3.75 cm. (1.5 inches). Connection between the quartz tube and glass train is made by means of graded quartz-to-glass seals.

AT is a 3-way stopcock by means of which it is possible to con­

nect to a vacuum pump or to pass the gas on through the balance of the chain. I t is, of course, necessary th a t the system be free of any oxygen contamination and since M is opened to the air during the admission of a sample, the air adm itted must, of course, be removed before an analysis is made. This m ay be done by sweeping out M for about 10 minutes with pure nitro­

gen, but it is more expedient to use a vacuum pump for the re­

moval of air. By using an oil pump this was satisfactorily effected in one m inute’s time. The pump used was a Cenco megavac pump driven by a Va horsepower motor. After the gas leaves M it passes through the tower, O, which contains a liberal plug of glass wool to trap off carbon dust. P is a tower of copper oxide kept a t 300° C., wherein th e carbon monoxide formed in M ' is oxidized to carbon dioxide. Q is another Anhydrone tower.

R is a weighed Schwartz adsorption tube loaded with Ascarite and Anhydrone, S is a guard tube containing Anhydrone, and 7’ is a

D e t e r m i n a t i o n o f B l a n k

In the d eterm ination of th e blank th e procedure followed is like th a t described above, except th a t a steel sam ple is n o t used. A fter a num ber of g raphite buckets containing tin samples had been prepared, they were stored in a desiccator for several days. A se t of blanks was then determ ined on six different graphite containers and th e following w eight in­

creases in th e Schw artz tu b e were noted: 0.7, 0.7, 0.6, 0.9, 0.6, and 0.7 mg. T h e average value of 0.7 mg. gives a blank am ounting to 0.0017 per cent for a 15-gram sam ple. T his figure is rounded and a blan k correction of ^{0 . 0 0 2} per cent applied. C ontinued tre a tm e n t of th e graphite b u ck e t and its contents for an additional 15 m inutes (w ithout its rem oval from th e train ) yields an average b lank of 0.5 mg.

T he blank correction of 0.002 per cent is correct only so far as th e oxygen m ay be obtained from th e steel sam ple in a 15-m inute period. I f a longer tim e is necessary, th e blank correction is greater th a n 0.002 per cent. T h u s it has been determ ined th a t for every 5-m inute reduction period, th e added blank for th e weighed absorption bulb would be ^{0 . 2} mg. T his am ounts to 0.0005 per cent for a 15.0-gram sam ple of steel.

P ractically com plete reduction of oxides is usually ob­

tained in a 15-m inute period. In th e case of steels very high

ANALYTICAL E D IT IO N 129

As s e m b l y f o k De t e r m i n a t i o n o f Ox y g e n

in alum ina content, however, the tim e necessary for reduc­

tion m ay be several hours. The cum ulative blank in such a case would be so high th a t the applied correction would be of a questionable nature.

Tim e Necessary for a Run

I t was th o u g h t advisable to determ ine ju s t how m uch tim e was necessary for an analysis. Accordingly, a num ber of determ inations were m ade on a set of sta n d ard steels w ith this purpose in view. T hese standard steels were kindly furnished b y D r. Thom pson of the N ational B ureau of S tan d ard s and were the same as those used in th e accum ula­

tion of d a ta em braced in a report by Thom pson, Vacher, and B rig h t (8). T ables I to VI give the results of a num ber of runs. In th e first column is listed the to ta l length of tim e

T a b l e I. S t e e l S a m p l e 1, L o w - C a r b o n , R i m m i n g il E lap se d

T im e P ick u p B lank T o ta l N e t C O i

from Sam ple O xygen

M in . M g. M g. M g. %

15

Sam ple W eight, 14.80 G ram s

1 1 .0 0 .7 10 .3 0 .0 2 5

20 11 .1 0 .9 10 .2 0 .0 2 5

15

S am p le W eig h t, 14.62 G ram s

1 0 .2 0 .7 9 .5 0 .0 2 4

20 10 .6 0 .9 9 .7 0 .0 2 4

25 10.0 1.1 9 .8 0 .0 2 4

30 1 0 .9 1 .3 9 .0 0 .0 2 4

T a b l e II. S t e e l S a m p l e 2 , H i g i i - M a n g a n e s e , S i l i c o n - K i l l e d

T o ta l E lap se d T o tal T o ta l N e t COz

T im e P ick u p B lank from Sam ple Oxygen

M in . M g. M g. M g. %

Sam ple W eight, 14.90 G ram s

15 9 .3 0 .7 8 .0 0 .0 2 1

20 9 .6 0 .9 8 .7 0 .0 2 1

25 9 .7 1.1 8 .6 0 .0 2 1

S am p le W eig h t, 14.97 G ram s

15 9 .8 0 .7 9 .1 0 .0 2 2

20 9 .9 0 .9 9 .0 0 .0 2 2

Ta b l e I I I . St e e l Sa m p l e 7 , Op e n He a r t h Ir o n, Ri m m in g

T o ta l E lap sed T o tal T o ta l N e t CO i

T im e Pick u p B lank fro m S am p le O xygen

M in . M g. Mg. Mg. %

S am p le W eig h t, 22.10 G ram s

15 7 3 .8 0 .7 73 .1 0 .1 2 0

20 7 4 .3 0 .9 7 3 .4 0 .1 2 1

S am p le W eight, 14.81 G rains

15 4 9 .5 0 .7 4 8 .8 0 .1 2 0

20 1 .2 0 .9 4 9 .8 0. 122

Sam ple W eight, 14.70 G ram s

15 4 9 .7 0 .7 4 9 .0 0 .1 2 1

20 5 0 .3 0 .9 4 9 .4 0. 122

T a b l e IV. A l l o y S t e e l , 18 Cn, 8 N i

T o ta l E lap se d T o ta l T o ta l N e t C Oj

Tim e P ic k u p B la n k from Sam ple O xygen

M in . M g. M g. Mg. %

Sam ple W eight, 12.63 G rains

15 5 .0 0 .7 4 .3 0 .0 1 2

20 5 .5 0 .9 4 .6 0 .0 1 3

25 5 . 8 1.1 4 .7 0 .0 1 3

th e weighed Schw artz adsorber was in th e tra in d uring the run.

T he second colum n gives the w eight increase in the adsorber, and th e th ird lists th e blank correction to be applied. Col­

um n 4 lists th e pickup in th e adsorber due to steel sam ple oxide, and colum n 5 gives th e calculated to ta l cum ulative percentage of oxygen present in th e steel sample.

Discussion of Results

T ables I to V, inclusive, show th a t th e extraction of oxygen from th e steel sam ple is v irtu a lly com plete 15 m inutes after th e ru n has sta rte d . T his is tru e for low- an d high-oxygen rim m ing steels (Tables I, I I I , and IV ), a high-m anganese silicon-killed steel (Table I I ) , and a chrome-nickel steel (Tables IV and V). H owever, in th e case of the alum inum - killed steel (T able VI) a m uch longer tim e is required to ex-

130 IN D U STR IA L AND E N G IN E E R IN G CH EM ISTR Y VOL. 12, NO. 3

T a b l e V. A l l o y S t e e l 7, 18 Cr, 9 N i

T o ta l E la p se d T o ta l T o ta l N e t COs

T im e P ic k u p B la n k fro m S am p le O xygen

M in . M g. M g. M g. %

S am p le W eig h t, 11.35 G ram s

15 4 . 0 0 .7 3 .3 0 .0 1 1

20 4 .3 0 . 9 3 . 4 0 .0 1 1

Ta b l e V I . St e e l 8 , Al u m i n u m- Ki l l e d T o ta l E lap se d

T im e P ic k u p

T o ta l

B la n k T o ta l N e t CO i

fro m S am ple O xygen

M in . M g. M g. M g. %

15

S am p le W eig h t, 14.55

5 .1 0 .7

G ram s

4 .4 0 .0 1 1

20 7 .0 0 .9 6 .1 0 .0 1 5

25 8 .7 1.1 7 .6 0 .0 1 9

30 9 .7 1 .3 8 .4 0 .0 2 1

35 1 0 .4 1 .5 8 .9 0 .0 2 2

40 1 1 .2 1 .7 9 .5 0 .0 2 4

45 1 1 .6 1 .9 9 .7 0 .0 2 4

50 1 1 .6 2 .1 9 .5 0 .0 2 4

15

S am p le W eight, 14.85

5 . 5 0 .7

G ram s

4 .8 0 .0 1 2

20 8 .2 0 .9 7 .3 0 .0 1 8

25 9 .6 1 .1 8 .5 0.0 2 1

30 1 0 .4 1 .3 9 .1 0 .0 2 2

35 11.1 1 .5 8 .6 0 .0 2 3

40 1 1 .5 1 .7 9 .8 0 .0 2 4

45 1 1 .6 1 .9 9 .7 0 .0 2 4

Ta b l e V I I . Co m p a r i s o n o p Ni t r o g e n a n d Va c u u m Fu s i o n Me t h o d s

O xygen D e te rm in e d

Steel N itro g e n fu sio n B e s t v a lu e , v a cu u m

N o. m e th o d fu sio n m e th o d

% %

1 0 .0 2 5 0 .0 1 8

0 .0 2 5 0 .0 2 7

2 0 .0 2 1 0 .0 1 7

0 .0 2 2 0 .0 2 0

4 0 .0 0 4 0 .0 0 2

0 .0 0 5

5 0 .0 0 9 0 .0 0 9

0 .1 2 1 0 .1 0 6

0 .1 2 3 0 .1 1 9 0.122 0 .1 2 2 0 .1 2 4

8 0 .0 2 3 0 .0 1 7

0 .0 2 4 C r-N i alloy

(1 8 -8 )° 0 .0 1 3 0 .0 1 2

0.011

° N o t in c lu d e d in c o o p erativ e re p o rt.

tr a c t th e oxygen presen t in th e sam ple. T hese results show t h a t reduction of th e alum ina, as i t exists in th e steel, takes place ra th e r rapidly a t as low a te m p eratu re as 1 2 0 0° to 1250° C. T h a t reduction of th e alum ina occurs a t 1200°

to 1250° C. is som ew hat surprising, since it is com m only ac­

cepted t h a t reduction of alum ina by carbon does n o t tak e place a t tem p eratu res lower th a n 1600° C. (2). T h e in­

creased ra te of reduction of alum ina as it exists in th e steel m a y be due to a very sm all particle size of th e alum ina in ­ clusions or to th e cataly tic influence of th e tin.

A n in teresting p o in t in connection w ith th is cataly tic in­

fluence w as obtained while w orking w ith th e hydrogen re­

du ctio n m ethod for analysis of oxygen in steel. A m ullite tu b e suffered no reduction in an atm osphere of hydrogen a t a tem p eratu re of ^{1 2 0 0}° C. In tro d u c tio n of a nickel b o a t into th e tu b e caused th e continuous reduction of th e refractory oxides for m any hours. R em oval of th e nickel b o a t re­

sulted in an im m ediate sto p of th e reduction and th e afore­

m entioned cycle of sta b ility of th e oxides in hydrogen a t ^{1 2 0 0}° o u t of contact w ith m e tal and th e production of w ate r w hen m e tal was present w as repeated. I t is therefore n o t sur­

prising th a t alum ina in co n tac t w ith m e tal is reduced by g raphite a t 1200° to 1250° C.

T ab le V II (second column) contains th e results of a num ­ ber of oxygen determ inations m ade by th e nitrogen fusion m ethod. T h e th ird colum n is ta k e n from a rep o rt (4) on these sam e steels and gives th e values o btained b y th e vacuum fusion m ethod, listed as “ b est” values in th e cooperative rep o rt. R esults obtained b y th e n itrogen fusion m ethod are in general higher th a n those of th e vacuum fusion m ethod.

T his difference is in some m easure accounted for as due to sam pling of th e original sta n d a rd steel specim ens. T h e sam ples used in th e vacuum fusion m ethod w ere 2.41 cm.

(0.95 inch) in d iam eter an d were ta k e n from a solid rod w hich w as originally 25 cm. (1 inch) in diam eter. I n th e nitrogen fusion m ethod, specim ens only 1.59 cm. (0.625 inch) in di­

am eter were ta k e n from th e center of th e afore-m entioned steel rods an d would analyze slightly higher, or lower, ac­

cording to the segregation. D eterm inations of steel 1, m ade b y th e vacuum fusion m ethod (S), show a com plete cross section to contain 0.019 per cent oxygen an d th e core (0.914 cm ., 0.36 inch, in diam eter) 0.033 per cen t oxygen. Like­

wise for steel 7, th e value for th e com plete cross section ob­

tained b y th e vacuum fusion m ethod w as ^{0 . 1 1 2} p er cent

oxygen an d th e core (1.27 cm ., 0.50 inch) w as 0.128 per cen t oxygen.

I t has been observed (1) th a t th e chief sources of error in th e vacuum fusion m ethod are sp a tte rin g of th e sam ple, ab­

so rption of th e gases b y films of volatile m etals (such as m anganese or alum inum ), an d incom plete reduction of re­

fra cto ry oxides. I n th e use of th e nitrogen fusion m ethod no sp a tte rin g of th e sam ple was ever observed. I t w ould be expected th a t errors due to absorption by films of volatile m etals w ould be g reatly m inim ized, if n o t entirely elimi­

n ated , in th e nitrogen fusion m ethod, since th e v ap o r pressures of th e m etals are m uch lower a t th e lower te m p e ra tu re em­

ployed in th e nitrogen fusion m ethod. Again, th e use of an atm osphere of n itrogen in place of a v acuum would also m a­

terially reduce th e a m o u n t of vaporized m etal. I t is to be expected th a t th e vacuum fusion m ethod m ig h t reduce some refra cto iy oxides (such as alum ina or zirconium oxide) m uch m ore rap id ly th a n these oxides w ould be reduced in th e nitrogen fusion m ethod. T h is w ould be no serious ob­

jection to th e use of th e nitrogen fusion m ethod, since th e am o u n t of these oxides in com mercial steels is usually low.

Conclusions

A tra in for th e d eterm in a tio n of oxygen in m etals has been developed w hich allows a d eterm ination (except for alu­

m inum -killed steels) to be m ade in less th a n 2 0 m inutes.

T h e su b stitu tio n of nitrogen for high vacuum obviates th e necessity of operators skilled in high-vacuum technique.

T h e tw o system s are alike in one essential p o in t— th e ab­

sence of oxygen contam ination.

R esults obtained b y th e nitrogen tra in are reproducible, an d w hen segregation is ta k en into account, com pare favor­

ably w ith those of th e vacuum fusion m ethod.

Alum ina, as presen t in alum inum -killed steels, is reduced b y graphite in th e presence of tin a t 1250° C. T h e ra te of reduction is, however, considerably less th a n w ith th e oxides produced using ferrom anganese or ferrosilicon as deoxidizers.

Literature Cited

(1) Am. Soc. for Metala, Handbook, 1939, p. 713.

(2) Reeve, Lewis, Am. Inst. Mining Met. Engrs., Contrib. 56 (1933).

(3) Thompson, J. G., Vacher, H. C„ and Bright, H. A., Am. Inst.

Mining Met. Engrs., Tech. Pub. 758 (1936).

(4) Vacher, H, C., and Jordan, L., Bur. Standards J . Research, 7, 375-99 (1931).