Industrial and Engineering Chemistry : analytical edition, Vol. 8, No. 2

INDUSTRIAL

AND ENGINEERING

Analytical Edition T T T T ' l \ / f T Q ' T ' 1 I > * \ 7 *

Vol. 8, No. 2 K J JLL XL 1V1 ^{l U} 1 JTl X March 15, 1936

Vol. 28, C onsecutive N o. 10

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

Publication Office: Easlon, Pa. . Editorial Office: Room 706, Mills Building, Washington, D . C. . Telephone: National 0848 Cable: Jiechem (Washington) . Advertising Department: 332 W est 42nd Street, New York, N . Y. . Telephone: Bryant 9-4430

C O N T E N T S

17,100 Copies of This Issue Printed.

* Semi-Micromethod of Analysis for N it r o g e n ...

... Anthony R. Ronzio 122 Surface-Tension Measurements of Viscous Liquids . . . .

... A . II. Pfund and E. W. Greenfield 81 A New Buret for Potentiometrie Titrations . L. S. Keyser 82 Laboratory Service Testing o f Automotive Lubricating

G r e a s e s ...E . N . Klemgard 83 Determination of Starch in Plant T is s u e s ...

. . . George \V. Pucher and Hubert Bradford Vickery 92 Determination of Zinc in S o i l s ...

... Hugh M . Boggs and A. 0 . Alben 97 Recovering Chloroform from Used Dithizonc Solutions . .

... Donald A . Biddle 99 Measuring the Susceptibility of Asphalts to Temperature

Changes . A . Holmes, J . 0 . Collins, and W. C. Child 100 Control of High Lights in Reading Microbalance Swings .

...Paul II. M .-P. Brinlon 101- Determination of Gaseous Olefins or Hydrogen by Catalytic

H y d r o g e n a t io n ...

Wallace A . M cM illan, Howard A . Cole, and A . V. Ritchie 105 Fluidity and Hygroscopic Properties of Shellac . . .

... R. V. Toumend and W. R. Clayton 108 Determination of Selenium in 18-8 Stainless Steels . . . .

... George G. M arvin with Walter C. Schumb 109 An Efficient Laboratory Extraction A p p a r a tu s...

... Frederick C. Opperi 110 A Rapid and Efficient M i x e r ... D. II. Nelson 111 The Determination of Rhenium. I I ...

...Loren C. Hurd and Bernard J . Babler 112 Separation of Stannic Oxide from Various Oxides by Igni­

tion with Ammonium I o d i d e ...

...Earle R. Caley and M . Gilbert Burford 114 The Ignition of Silicic A c i d ...

...Knut A . Krieger and Iliram S. Lukens 118 Determining Copper in the Presence of Interfering Elements

...II. W. Foote and John E. Vance 119 A New Buret for Alkali Titrations . . . . L. S. Keyser 121 &

Studying the Hardness of Butter F at . . W illis D. Gallup 123 Determination o f Iron by Titanium Titration and by a,a '-

Bipyridine Colorimetry . . . . W illiam D. McFarlanc 124 Direct Titration of S u lf a t e s ...

...R. T. Sheen and II. L. Kahler 127 Determination of S u lf a t e ...John E . Ricci 130 Gravimetric Determination o f Selenium in Alloy Steel . .

...Louis Silverman 132 Detection o f Rhenium in the Sodium Carbonate Bead . .

... Herman Yagoda 133 Rotenone Determination by Colorimetric Methods . . .

... H. D. Rogers and J . A . Calamari 135 Determination o f Iron in Sea Water . . . . Norris W.

Rakeslraw, Henry E. Mahncke, and Eliot F. Beach 136 Determination of Reducing Sugars and Sucrose in Plant

M a t e r i a ls ... W . Z . Hass id 138 The Assay of the Platinum M e t a l s ...

... F. E . Beamish and J . J . Russell 141 A Thermionic Titrimeter without B a t t e r ie s ...

...Hobart II. Willard and 0 . B. Hager, J r. 144 A Continuous-Reading Electron-Tube Conductance Meter

... R. L . Garman 146 When Is a D esicca to rP ...

...Harold Simmons Booth and Lucille M cIntyre 148 A Versatile Low-Temperature Thermostat . . G. B. Ileisig 149 Improved Apparatus for Isolation of F lu o r in e ...

... W i K . Gilkey, II. L. Rohs, and II. V. Hansen 150 Improved Micromanometer . . . . H arry W. Smilh, Jr. 151 D evice for Determining Rate of Siphoning in M etal E x­

traction S y s t e m s R. S. Asbury 152

P u b lish e d b y th e A m erican C hem ical Society, P u b lica tio n Office, 20th &

N o rth a m p to n Sts., E a sto n , P a . E n te re d as second-class m a tte r a t th e P o st- Office a t E a s to n , P a ., u n d e r th e A ct of M arch 3, 1879, as 42 tim es a year.

In d u s tria l E d itio n m o n th ly on th e 1st; News E d itio n on th e 10th a n d 20 th , A n aly tical E d itio n b im o n th ly on th e 15th. A cceptance for m ailin g a t special ra te of p o stag e pro v id ed for in Section 1103. A c t of O cto b er 3, 1917, a u th o r­

ized J u ly 13, 1918.

A n n u al s u b s c r i p t i o n r a t e s : ( a ) In d u s t r i a l Ed i t i o n $5.00; (6 ) An a l y t i­ c a l Ed i t i o n $2.00; (c) Ne w s Ed i t i o n $1.50; ( a ) a n d (6 ) t o g e t h e r . $6.00;

(a), (b), a n d (c) com plete, $7.50. F oreign p o stag e to c o u n trie s n o t in th e P a n A m erican U n io n , (a) $1.20; (6) $0.30; (c) $0.60: to C a n a d a o n e -th ird th e se ra te s. Single copies: (a) $0.75; (6) $0.75; (c) $0.10. Special ra te s to m em bers.

C laim s for copies lo st in m ails to be ho n o red m u s t be received w ith in 60 d a y s of d a te of issu e a n d based on reasons o th e r th a n “ m issin ? from files.”

T en d a y s ' ad v an ce n o tice of change of ad d ress is re q u ire d . A d d ress C harles L. P arso n s, B usiness M an a g e r, M ills B u ild in g , W ash in g to n , D . C .,

4 IN D U ST R IA L A N D E N G IN E E R IN G CHEM ISTRY VOL. 8, NO. 2

CHROMEL-ALUMEL

L E A D S

^{a n d}

C O U P L E S

Y

E S , h e C A N g e t b y w i t h o u t s h a v ­ in g , t o d a y m a y b e . . . . a n d y o u , t o o , m a y g e t b y w i t h o u t u s i n g C h r o - m e l - A l u m e l L e a d s w i t h y o u r C h r o - m e l - A l u m e l C o u p le s . B u t i f y o u a re u s i n g s o - c a lle d " c o m p e n s a t in g le a d s ” w i t h t h o s e c o u p le s , h e r e ’s w h a t it m e a n s —

I n s u c h a h o o k - u p , t h e le a d s a n d ' c o u p le s o f c o u r s e d o n ’t h a v e t h e s a m e c o m p o s i t i o n . H e n c e w h e r e t h e y j o i n i n t h e c o u p le h a n d l e , a t h e r m o - e l e c t r i c j u n c t i o n e x is t s . I f t h i s j u n c t i o n d o e s n ’t g e t v e r y w a r m , n o s ig n if ic a n t err o r is i n t r o d u c e d . B u t if i t g e t s v e r y h o t , a s i t o f t e n d o e s , t h e n t h e erro r m a y in d e e d b e

s e r io u s . T h e p o i n t is , t h a t “ c o m ­ p e n s a t i n g l e a d s ” u s e d w i t h C h r o m e l c o u p le s a r e a lw a y s a t l e a s t a p o t e n ­ t i a l s o u r c e o f e r r o n e o u s t e m p e r a t u r e r e a d in g s . S o w h y t a k e t h i s c h a n c e o f t r o u b le ?

T h e w a y o u t is s i m p l e : j u s t u s e C h r o m e l- A lu m e l L e a d s w i t h C h r o - m e l - A l u m e l C o u p le s . W h e r e t h e y j o i n , s i n c e t h e y ’r e o f t h e s a m e c o m ­ p o s i t i o n , t h e r e is n o t h e r m o - e l e c t r i c e f f e c t , a n d t h u s y o u e l i m i n a t e t h a t s o u r c e o f e r ro r. . . I t ’s r is k y b u s i ­ n e s s , t h i s t h i n g o f t r y in g t o “ g e t b y ” . . . F o r t h e c o m p l e t e s t o r y , s e n d f o r F o ld e r - G Y . . . . H o s k in s M a n u f a c ­ t u r i n g C o ., D e t r o it , M ic h .

gel fy . .

M ARCH 15, 1936 ANALYTICAL E D IT IO N 5

Retention Efficiency

Speedy Filtration

Practical Strength.

-purpose Iter Paper

. . not 3 G ra d e s

T he idea surely must appeal—it may seem radical. Tim es change. Proc­

esses improve—even in filter paper treatment. Baker & Adamson is out in front.

T h in k of the convenience. One paper—no hesitance in choosing at the bench, no multiple stock to watch in the storeroom. One grade

—retentive enough for fine pre­

cipitates, sufficiently strong for all practical require­

ments and speedy beyond anything of equal fineness. W ill amaze you on Iron or A lum inum precipitates.

Try it out at our expense. W e’ll quit talking and send you an ade­

quate test supply, if you’ll give it a critical trial . . . You’ll be surprised and w e’ll get an order.

IF Y O U HAVE N O T RECEIVED Y O U R C O P Y O F T H E B A K E R & A D A M S O N CATALOG . . . . PLACE A C H E C K M A R K H E R E

BAKER & A D A M SO N D IV IS IO N

G EN ER A L C H E M IC A L C O M P A N Y , 4 0 R e c to r St., N e w Y o rk Send me your FR E E SAM PLE ENVELOPE of B & A Filter Paper Circles, w hich I w ill test for a personal observation o f its speed and efficiency.

N a m e ...

Address

IN D U ST R IA L A N D E N G IN E E R IN G C H EM ISTRY VOL. 8, NO. 2

W r it e u s if w e c a n b e o f S e r v i c e .

M ERCK & CO. Inc. • M a n u fa ctu rin g C h em ists • RAHWAY, N. J.

N E W Y O R K • P H I L A D E L P H I A • S T . L O U I S

Some of ihe I mp o r t a n t

M E R C K R E A G E N T S O L V E N T S

*

A C E T O N E R EA G EN T

A L C O H O L A M Y L IS O R EA G EN T

A L C O H O L M ETH Y L A BSO LU TE REA G EN T

B EN ZE N E R EA G EN T

BEN ZIN R EA G EN T

C A R B O N D ISU LPH ID E R EA G EN T

C A R B O N TE T R A C H L O R ID E R EA G EN T

C H L O R O F O R M R EA G EN T

ETHER A N H Y D R O U S R EA G EN T

ETHER R EA G EN T

ETHY L A C E T A T E R EA G EN T

G LY CERIN R EA G EN T

PY R ID IN E R EA G EN T

T O LU EN E R EA G EN T

X YLEN E REA G EN T

M a n y lim e s w h e n S o lv e n ls a r e u s e d , e x a c t i n g research or analytical w ork is in v o lv e d . The e x p e ­ r ie n c e d ch em ist k n o w s that h e c a n d e p e n d u p o n

M J Ü M 23 S

LABORATORY CHEMICALS

M ARCH 15, 1936 ANALYTICAL E D IT IO N 7

SARGENT RPS

Rubber Plated Steel

LABORATORY SUPPORTS

P a t e n t s P e n tlin g

B ulletin on Request

C P D R F = O X - 9 H I ■ lOI L I l l

E.H. S R R G E f l T 5c CO. C H I C R G O

L A B O R A T O R Y SUPPLIES

155-165 E. Superior St. Chicago, III.

W e l d e d s t e e l s t r u c t u r e s are c o m p l e t e l y p l a t e d w i t h a t h i c k la y e r o f p u r e la te x r u b b e r .

P ric e s a n d D is c o u n ts

9783— K jeldahl Support, fo r 500 a n d 800 m l f l a s k s . ... $2.75 ea.

D iscount: 6 -1 0 % : 1 2 -2 0 % .

9793— F u n n el Support, 12 p la c e...$2.75 ea.

D iscount: 6 -1 0 % : 12-20%).

9813— Test Tube Support, 12 place, fo r tubes */<" to 1 " ... $1.40 ea.

D iscount: 1 2 -1 0 % : 3 6 -1 5 % : 7 2 -2 0 % : 144-25% .

9809— Test Tube Support, 12 place, fo r tubes y 2" to 3/ 4" ...$1.25 ea.

D iscount: 1 2 -1 0 % : 3 6 -1 5 % : 7 2 -2 0 % : 144-25% .

9811— Test Tube Support, 24 place, fo r tubes l/ 2" to * / / ...§1.50 ea.

D iscount: 1 2 -1 0 % : 3 6 -1 5 % : 7 2 -2 0 % : 144-25% .

9815— Test Tube Support, 24 place, fo r tubes */«' to 1 " ... $1.75 ea.

D iscount: 1 2 -1 0 % : 3 6 -1 5 % : 72-20% ,: 144-25% .

A th ick , p ro te c tiv e co atin g of p u re latex ru b b e r a n d w elded steel stru c ­ tu re s c o n stitu te th e m o st p ra c tic a l a n d d u ra b le co m b in atio n o f m aterials fo r service in la b o ra to ry e n v iro n m en t. T h e latex ru b b e r is electrolyti- cally d ep o sited ov er th e e n tire s tru c tu re , leaving no m etal surface ex­

posed to corrosion.

S a rg e n t RPS su p p o rts a re unaffected b y corrosive ag ents w hich ru in o u sly a tta c k m e ta l p lated , enam eled o r w ood su p p o rts.

T h e th ic k la y e r o f la te x ru b b e r is soft, resilien t a n d extrem ely to ugh, effectively re sistin g ab ra siv e actio n . T h e su p p o rts, w elded a t all unions, a re rig id a n d c a n n o t becom e loose o r u n jo in ted.

RPS su p p o rts abso rb o r re ta in n o co n tam in atin g m aterial an d m ay be easily a n d th o ro u g h ly cleaned, o r sterilized b y boiling in w ater. B ecause glassw are c o n ta c ts no o th e r m a te ria l th a n soft, resilien t latex ru b b e r, n o r­

m al b reak ag e ra te s a re m a te ria lly reduced.

S a rg e n t RPS F u n n el su p p o rt N o. 9793 h as been designed to elim inate th e fo rm er u n n ecessary a n d aw k w ard a d ju sta b le shelf. T h e h e ig h t of th e fixed shelf is such t h a t th e 150 m m stem of a n a n a ly tic a l funnel ex­

te n d s to a su ita b le d e p th in to b eak ers of 250 m l to 600 m l cap acity . T h e su p p o rt accom m odates, in a double row , 12 funnels of 50 to 75 m m d ia m e te r a n d 12 b e a k ers of 250 m l to 600 m l cap acity .

S a rg e n t RPS K jeld ah l su p p o rt N o. 9783 accom m odates six flasks of 500 a n d 800 m l c a p a c ity w hich a re held securely b y sp rin g clips a n d w hich m a y be easily rem o v ed b y a slig h t p re ssu re in th e d irectio n o f th e long axis o f th e s u p p o rt w ith o u t need of h o ld in g th e s u p p o rt itself.

All S a rg e n t RPS te s t tu b e su p p o rts h av e shelves a t th ree levels in c o n tra s t w ith o lder designs w hich p ro v id e only tw o shelves from w hich tu b e s a re easily dislodged. T h is a d d ed p re c a u tio n m akes i t im possible for a tu b e to fall th ro u g h a S a rg e n t RPS te s t tu b e su p p o rt. D ry in g p in s a re a n in te g ra l p a r t of th e s u p p o rt stru c tu re .

IN D U ST R IA L A N D E N G IN E E R IN G CHEM ISTRY VOL. 8, NO. 2

ADVANTAGES

*Doreco Enclosed Element . . . Impervious to fumes.

‘ Dual Input . . . High for quick heating;

low for holding at temperature.

‘ Plug Type Door. . . Seals perfectly. . . . stops losses.

‘ Cool Terminals . . . Heavy industrial type of large cross section.

‘Heats Quickly . . . Uniformly . . . Eco­

nomically.

STANDARD SIZES AND PRICES

P R IC E T Y P E C H A M B E R S IZ E F U R N A C E R H E O ST A T

W. H. L. O N L Y O N L Y

MPI 4" x 3" x 8"

M PI-A 4" x 3" x 10"

MP2 6" x 4" x 12"

MP3 8" x 6" x 14"

MP4 10" x 6" x 18"

(Type MP Furnaces are also available with rheostats enclosed.)

$60.00 $14.00 70.00 15.00 90.00 18.00 115.00 38.00 175.00 53.00

TYPE M P MUFFLE FURNACE

COOLEY MUFFLE FURNACES HANDLE THE HARD JOBS!

One has been run n in g for th irte e n m o n th s con tin u o u s service a t 1850 degrees F ; h e a tin g sm all stainless steel p a rts in an atm o sp h ere th a t viciously a tta c k s exposed elem ents. T h re e o th ers are fusing bifocal lenses, an o p eratio n th a t req u ires precision a n d accu racy .

C H E M IS T S A N D M E T A L L U R G IS T S H A V E A C C E P T E D C O O L E Y E L E C T R I C F U R N A C E S because these furnaces are h an d lin g th e ir jo b s u n d e r ex trem e conditions. T h e re is no prem ium to be paid for this q u a lity o f e q u ip m en t an d added v alue o f perform ance.

F or fu rth e r details concerning M uffle, C om bustion T u b e, C rucible F u rn aces, and H o t P lates, w rite for ou r catalogue N o. 34 o r consult your dealer.

COOLEY ELECTRIC FURNACE CO. INDIANAPOLIS INDIANA

Micro-Analysis ( ^ v )

n o w o f i n t e r e s t to all c h e m i s t s •

The technique of carrying out chemical analytical determinations of the elements by using only minute amounts of substances has to-day reached a state of im­

portance equal to that of large scale qualitative and quantitative chemical analyses. The value of all analytical w ork rests fundamentally on the accuracy of the apparatus used.

A .P .W . P LA T IN U M W A R E have always qualified as the most reliable means for obtaining absolute accurate results. W e have published a special leaflet called

D

P L A T IN U M M IC R O -A P P A R A T U S Showing all various types of micro wares.

A S K FO R Y O U R C O P Y T O D A Y

For the first time any chemist has the opportunity for making all the chemical determinations with Platinum Wares, which formerly only a most lavishly equipped analytical laboratory could afford.

A complete micro or semi-micro analytical equipment in platinum involves only a relatively small cost.

W E I N V I T E Y O U R I N Q U I R I E S

The AMERICAN PLATINUM WORKS

N.J.R.R. A V E . A T O L IV E R ST.

N E W A R K , N. J.

Refiners and Manufacturers of Platinum, G o ld and Silver

MARCH 15, 1936 ANALYTICAL E D IT IO N 9

<e:xax>

S iiiS

l ik e

N O R M A X

G R A D U A T E D L A B O R A T O R Y G L A S S W A R E

| K IM B L E L A 8 O R A T O R

» B R A h iO

uld blown

°l*ssvvare

KIMBLE GLASS

lihese New KIMBLE

Catalogs should be in every Laboratory

E v ery b u y e r o f scientific g lassw are— e v e ry ch ief c h e m ist, re se a rc h m an, clinical te c h n ic ia n , a n d c h em ical d e p a rtm e n t h e a d in sc h o o ls a n d co lleg es—

w ill w a n t o n e o r m o re o f th e se n ew K im ble b o o k s:

BLU E LIN E E X A X C A T A L O G — c o m p le te listings, illu stra tio n s a n d p ric e s o n Blue Line R e te m p e re d a n d R e te s te d G r a d u a te d G lassw are.

N O R M A X C A T A L O G — c o m p le te line fo r P recision, C o n tr o l a n d R esearch.

K - B R A N D C A T A L O G — on lam p an d m o u ld b lo w n la b o ra to ry glassw are.

y o u r coii/xm to d a y. D'our copies will i)o fo r w a r d prom ptly.

KI MBLE G L A S S C O M P A N Y

D E P T . 1 6 V I N E L A N D , N . J . NAME

P le a se send the Catalogs checked: FIRM...

□ BLUE LINE EXAX □ K-BRAND T1TLE---

□ NORM AX ADDRESS.

10 IN D U ST R IA L A N D E N G IN E E R IN G C HEM ISTRY VOL. 8, NO. 2

S U L F U R I C A C I D

MA NUFACTURE

by A ndrew M . Fairlie

American Chemical Society M onograph No. 69

f O R

th e first tim e in E n g lish , a n a tte m p t h a s b een m a d e to p ro d u c e w ith in th e com p ass o f a single v olum e a b o o k o n S u lfu ric A cid M a n u fa c tu re w h ich w ould be a t once a u th o rita tiv e , re aso n ab le in p rice, a n d h a n d y to use.

D escrib in g b o th th e n itra tio n (c h a m b e r) processes a n d th e c o n ta c t processes as p ra c tic e d in th e U n ite d S ta te s a n d a b ro a d , it deals w ith m a n y d e v e lo p m e n ts o f p rim e im p o rta n c e to th e su lfu ric acid in d u s try w h ich h a v e b een ev o lv ed a n d p laced on a p ra c tic a l w ork in g b asis d u rin g th e la s t te n y e a r s —flash ro a stin g processes, liquid-cooled c h am b ers o f th e new M ills -P a c k a rd a n d G a illa rd -P a rris h ty p e s, new to w e r processes, a new c o n ta c t p rocess, new su lfu r b u rn e rs , su lfu r s p ra y nozzles for m o lte n su lfu r, su lfu r-fired s te a m boilers, new v a n a d iu m a n d p la tin u m c a ta ly s ts , th e expan sio n o f th e use o f v a n a d iu m -m a ss, se lf-co n tain ed h e a t- exchange co n v e rte rs, e tc.

T h e re is no p rev io u s bo o k in a n y la n g u ag e t h a t describes all o f th e se re c e n t d e ­ v e lo p m en ts w ith a n a r r a y o f u p -to -d a te d e ta ils, p e rta in in g to e q u ip m e n t a n d m e th o d s o f o p e ra tio n u sed in m o d e m m a n u fa c tu rin g p ra c tic e .

CONTENTS

P reface.

In tro d u c tio n . H isto rical

C h e m istry a n d T h e o ry R e la tin g to S ulfuric Acid M a n u ­ fa ctu re.

C o n stru c tio n M a terials.

P ro d u c tio n M a terials.

B u rn e rs, R o a ste rs a n d F u rn a c es.

B u rn er- o r F u rn a c e-g a s.

N itra tio n P ro cesses— M e th o d s o f N itra tio n . G lo v er T ow er.

L ead C h a m b e rs a n d C h a m b e r S u b s titu te s . R eco v ery o f N itro g en Oxides.

A uxiliary E q u ip m e n t o f a N itra tio n -p ro c e ss P la n t.

C o m p lete P la n t D esig n — O p e ratio n o f a N itra tio n -p ro c e ss P la n t.

P u rifica tio n a n d C o n c e n tra tio n o f Su lfu ric A cid.

C o n ta c t o r C a ta ly tic Processes. G en eral D iscussion.

T h e C o m p o sitio n o f B u rn e r- o r F u rn a c e-g a s. C leansing, C ooling a n d D ry in g th e G as.

B low ers; P re h e a te rs ; H e at-e x ch a n g ers; C o n v e rte rs.

C a ta ly s ts .

C o m p ariso n o f P la tin u m a n d V a n ad iu m C a ta ly s ts . SO j-gas C oolers; SOj A b so rb ers; O leum M a n u fa c tu re ;

M iscellaneous C o n tac t-p ro c e ss E q u ip m e n t.

C o m p lete C o n ta c t P la n t. O p e ratio n . M e th o d s o f C o n ­ tro l o f Process.

S pecial T y p e s o f C o n ta c t P la n t; In d iv id u a l In s ta lla tio n s . M ixing a n d S h ip p in g S ulfuric A cid; H a z a rd s a n d S a fe ty M easu res; C o sts a n d C o st-a cc o u n tin g ; T o B u y o r T o B u ild ? C hoice o f P ro cess; T re n d s in th e I n d u s try . A P P E N D I X E S .

Emphasis

is laid on the value of the follow­

ing tables included in the Appendixes.

I. Hydrometers.

II. Sulfuric Acid Tables of the Manufacturing Chemists Association of the U nited States.

III. Sulfuric Acid Temperature Correction Tables.

IV. Sulfuric Acid Conversion Factors.

V. Sulfur Dioxide Percentage Tables.

VI. N itrosity of Nitrous Vitriol or Sulfuric Acid.

VII. Boiling Points of Sulfuric Acid Solutions.

VIII. Properties of Saturated Steam.

IX . Tables Giving the Composition and W eight of Sulfuric Acid Solutions, from 1.02 to

100 per cent HsSO«.

X . Fuming Sulfuric Acid Tables.

X I. Table for Finding Conversion Percentage.

X II. Brick Shapes, Illustrated, with Sizes.

X III. Lead Pipe and Sheet Lead, Sizes and Weights.

X IV. General Conversion Factors (9 pages of them) for Converting Quantities of a Given U nit into Equivalent Quantities of a Different Unit.

XV. Nomographs.

672 Pages • Illustrated • $9.75

REINHOLD PUBLISHING CORP. 330 j t r ^ u ? A.

MARCH 15, 1936 ANALYTICAL E D IT IO N 11

( J nL Y skilled h an d s m ake the lab o rato ry glassw are th a t carries the tra d e -m a rk “ Pyrex’ ’.

T h ey are the h an d s of ex p ert w orkm en whose chief concern is th e fab ricatio n of technical glassware.

M ore th a n this, th eir w ork is guided by chem ists, physicists a n d engineers w ho are leaders of progress in this field; they are sup­

plied w ith the most m o d ern a n d com plete tools o f th e ir tra d e ; an d th ey w ork w ith the m a te ria l th a t gives fullest scope for their

skill— “ P y rex ” B ran d h eat-resistan t glass.

In m ak in g the m ore elab o rate ap p a ra tu s, they deal w ith lam p-blow n blanks of uniform w all thickness. T h e skill a n d thoroughness of m aster craftsm en have m ade pro d u cts of the C orning L am p Shop fam ous for superior strength, uniform ity a n d reliability.

Y our investm ent in la b o ra to ry glassw are is best p ro tected by m ak in g sure each piece, from a test tube to th e m ost com plicated piece of a p p a ra tu s, carries the m a rk “ Pyrex” . 11 P Y R E X ” is a registered trade-mark and indicates manufacture by

C O R N IN G GLA SS W O R K S • C O R N IN G , N . Y.

THE MARK OF

12 IN D U ST R IA L A N D E N G IN E E R IN G C H EM ISTRY VOL. 8, NO. 2

The Burette magnifier is not suitable for reading ther­

mometers and the thermometer magnifier is not suitable for meniscus reading because of the great difference in magnifying -power, depth of focus, etc.

A. H .T . CO. S P E C IF IC A T IO N

B U R E T T E A N D T H E R M O M E T E R R E A D E R S

ARTHUR H. THOMAS COMPANY

R E T A IL — W H O LE SA LE— E X P O R T

LABORATORY APPARATUS REAGENTS

W EST W ASHINGTO N SQUARE PH ILA D ELPH IA , U.S.A.

C able A ddress, “ B ala n c e ,” P h ilad elp h ia

2502

BURETTE M ENISCU S READER, A.H.T. Co. S p e c i­

fica tio n . With improved type of background, quick- acting clamp and focusing lens. Designed primarily for observing the position of the meniscus of an aqueous liquid in a burette, which is sharply defined as a curved black line against a white field. Can be used with tubes of from 6 mm to 21 mm diameter, the depth of focus of the lens being sufficient to permit superposition of lines on the front of a tube with those on the back—on burettes with all-round graduations—avoiding parallax. Observa­

tions can be made with either reflected or transmitted light and position of the meniscus at a mercury-gas or mercury-water interface can be accurately observed.

Construction is rigid but light in weight, being of alumi­

num finished in dull black.

Thermometer reading attachment contains a lens of greater magnifying power than that supplied for use with the Burette Reader and of different depth of foeus, so mounted that reflections from the surface of the outside tube of the enclosed scale thermometer such, for example, as a Beckmann thermometer, are reduced to a minimum.

This greatly increases ease and accuracy in reading a thermometer scale graduated in small intervals.

9632

THERM O M ETER READER, A .H .T. Co. S p ecifica­

tio n . W ith improved type of background and quick- acting clamp exactly as furnished with No. 2502 Burette Meniscus Reader, l)ut with a higher power magnifying lens so mounted that reflections from the surface of the outside tube of an enclosed scale thermometer such, for example, as a Beckmann thermometer, are reduced to a minimum.

This greatly increases the ease and accuracy of reading a thermometer scale graduated in small intervals.

The Burette Meniscus Reading Attachment contains a lens of lower magnifying power and of different depth of focus, mounted in a shorter tube, for observing the position of the meniscus of an aqueous liquid in a burette, which is sharply defined as a curved black line against a white field.

2502. B u re tte M en isc u s R e a d e r, A .H .T . Co. Specificatio n , as above d escribed, w ith o u t T h e rm o m ete r R ead in g A tta c h ­ m e n t... 7.50 C ode W o rd ... B ily a 2502-A. T h e rm o m e te r R ea d in g A ttach m en t, only, fo r in te rc h a n g e ­ able use in th e ho ld er of N o. 2502 B u re tte R e a d e r. 5.00 C ode W o rd ... Bim aio

9633 F ield of v iew in B eck- B u re tte M eniscus R ea d - m a n n T h e rm o m ete r

ing A tta c h m e n t g ra d u a te d in 0.01°

9632. T h e rm o m e te r R e a d e r, A .H .T . Co. S p ecification, as a b o v e described, w ith o u t B u re tte M eniscus R ea d in g A tta c h ­ m e n t... 10.00 C ode W o rd ... Ovjiv 9633. B u re tte M e n is c u s R ea d in g A tta c h m en t, only, for in te r­

ch an g eab le use in th e h o ld e r of N o . 9632 T h e rm o m ete r R e a d e r... 2.50 C ode W o rd ... Ovjlp 9633-A. C om b in atio n O u tfit, for th e rm o m e te r a n d b u r e tte m eniscus

re ad in g , co nsisting of N o. 2502 B u re tte M eniscus R ea d e r a n d N o. 2502-A T h e rm o m e te r R ead in g A tta c h ­ m e n t... 12.50 C ode W o rd ... Ovjrc 2502-A

T h e rm o m e te r R ead in g

A tta c h m e n t Field of view on b u ­ r e tte w ith all-ro u n d g ra d u a tio n s, w ith eye in c o rrect po sitio n , i.e.

no p a ra lla x on critic a l lin e A— B

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

INDUSTRIAL

AND ENGINEERING

CHEMISTRY

Ha r iu s o n E . Ho w e, Ed it o r

Surface-T ension M easurem ents o f V iscous L iquids

A. H. PFUND A N D E. W . GREENFIELD, Joh ns H opkins U niversity, Baltim ore, M d .

B y a llo w in g a s m a ll air j e t to im p in g e o n t h e s u r fa c e o f a liq u id , th e r e is p r o d u c e d a s m a ll d e p r e ssio n w h o s e d e p th is a n in v e r se f u n c t io n o f t h e su r fa c e t e n s io n o f t h e liq u id . T h is p r o c e d u r e is p a r tic u la r ly s u it e d to v is c o u s liq u id s .

T

H E usual methods for surface-tension measurements fail when applied to highly viscous fluids. The following method, developed by one of the authors (A. H. P.) in 1932 and tested by the other (E. W. G.) in 1934 is based upon the observation th a t if a small air jet be allowed to impinge on the surface of a liquid, an indentation or depression of the type shown in Figure 1 is produced. The depth of this de­

pression has been found to be an inverse function of the sur­

face tension. The method is a t its best when applied to liquids which are nonvolatile, viscous, and transparent.

The general arrangement of the apparatus is shown in Figure 2, where A is a glass tube drawn down to a bore of about 0.8 mm.

a t its lower end which is separated by about 3 mm. from the liquid surface, C. While there is nothing critical about the di­

mensions of the cell, B, the thickness of the fluid layer in the direc­

tion L M was chosen as 10 mm. The depth of the depression is 1 to 2 mm. since instability sets in when the depth is made con­

siderably greater. Measurements of the depth of the depression are carried out with a short-focus Gaertner telescope, M , sup­

plied with a micrometer eyepiece reading to 0.01 mm. Il­

lumination is effected by means of the small lamp, L, which is replaced by an arc lamp when the liquids are nearly black.

Light coming over the top of the liquid is cut out by the opaque shield, S. Since it is necessary that the distance between the end of the glass tube, A, and the liquid surface be kept constant—

a condition difficult to realize by attempting to fill the cell always to the same level—an arrangement of the type shown in Figure 3 was adopted.

Here the cell, B, which fits neatly between the blocks, DD, is mounted on a plate, E, to which a hinge, II, is attached at one end and a screw, F, at the other. B y means of this screw it is possible to raise or lower the cell bodily and thus to bring the image of the undisturbed surface into coincidence with the telescope cross hair, set to the zero reading of the micrometer.

To facilitate cleaning, the cell is made out of a brass block, 10 mm. thick, from which a U-shaped portion has been removed.

The glass plates forming the sides of the cell are simply held against the carefully machined sides of the brass block with small clamps (not shown).

Fi g u r e 1. Fo r m o f De p r e s s i o n w i t h Su c­ c e s s iv e In c r e m e n t s o f Ai r Pr e s s u r e

81

Fig u r e 3. Ar r a n g e m e n t f o r Ma i n t a i n in g Co n s t a n t Se p a r a t io n b e t w e e n Je t Or i f i c e;

a n d Li q u id Su r f a c e

8 2 IN D U STR IA L A N D E N G IN E E R IN G CHEM ISTRY VOL. 8, NO. 2 For the sake of brevity,

no description of the appara­

tus used in the production and maintenance of constant air pressure will be given. A pressure of about 2.4 cm. of water was found best. Cali­

b r a t i o n w as e f f e c te d by means of the known surface t e n s io n s of pure liquids—

water, glycerol, glycol, di­

butyl phthalate, and several mineral oils—no corrections being a p p lie d fo r density differences. The calibration curve obtained is shown in Figure 4, where the data are plotted on double logarithmic jo » « u m m paper. The equation of this

Surface Tension (dynes/cm j C U rVC i s Fi g u r e 4 . Ca l i b r a t i o n

C u r v e , L i q u i d s o f K n o w n 7 = K a~ ' / 1 Su r f a c e Te n s io n

col1.' 4W D ib u ty i p & a t e ® wh e r e T iS t h e S u r f a C e ^ n s i o n , 104. 6, Oil 108. K a constant, and a th e depth

of the depression.

An advantage of the air-jet method over other methods is brought out in a study of temperature-surface tension rela­

tionships in oils used for the impregnation of cables. The specific case chosen for the sake of illustration relates to a mineral oil designated as No. 100/100. A t 100° C. this oil had a viscosity of 0.5 poise and was therefore fluid; a t 60° C., however, the viscosity has risen to 4 poises and the oil was thick. Surface-tension measurements made by the air-jet method and by the “Jolly balance platinum ring” method are in excellent agreement a t temperatures above 60° C.

As shown in Figure 5, measurements by the platinum ring method become very erratic a t 60°, only to become meaning­

less a t lower temperatures. The jet method, however, is not subject to such limitations. Even a t 25° C. where the oil would not pour—the viscosity having risen to

80

^poises—

the depression had reached a constant depth in

12

seconds and measurements could be carried out with the same ease.

This method is obviously applicable also to molten metals and to opaque materials in general. By directing a jet of pure nitrogen (in place of air) against the surfaces of molten bismuth and tin, it became evident th a t the surface tension of these materials is much greater than th a t of water. Up to the present time no entirely satisfactory method for measur­

ing the depth of the depression has been found.

Another possible application of a modified jet method lies in the measurement of interfacial tension of water in contact with some nonmiscible, viscous liquid such as a heavy oil.

In this case, a small, vertical jet of water, directed upward within the water and striking the oil-water interface perpen­

dicularly, distorts the interface into a small hump or eleva­

tion whose height may be measured as before. Calibration

Fig u r e 5 . Su r f a c e Te n s i o n t>s. Te m p e r a t u r e ( Mi n e r a l Oi l 106)

xx P la tin u m rin g - J o lly balan ce m eth o d 00 A ir-jet m ethod

may be effected through the use of liquids having higher fluidity and a known interfacial tension with water. In the absence of such information it is always possible to make measurements by creating electrically excited ripples (1) a t the interface between water and nonmiscible liquids of high fluidity.

In connection with the preceding work it was noticed th at air jets are extremely sensitive to short sound waves. If an air jet of the previously described type be directed vertically downward on a water surface—the separation between orifice and surface being 7.5 cm. and the pressure equal to 7.5 cm.

of water—the depression immediately disappears as soon as a hissing sound is produced or if keys be rattled. There is a critical jet velocity and separation a t which the sensitiveness is greatest. The behavior of the jet is therefore similar to th a t of the well-known “sensitive flame.” The sensitive jet is well adapted for lecture-room dem onstration: I t is merely neces­

sary to use a vertical projection lantern and to send the light through a flat-bottomed glass dish containing water. By focusing the water surface on the screen, it is found th a t a black spot appears where the water surface is deformed. This spot disappears immediately upon the production of short sound waves.

L ite r a tu r e C ite d (1) P fund, A. H „ Phys. Rev., 32, 326 (1911).

Re c e i v e d N o v em b er 1, 1935. P rese n ted a t th e m eetin g of th e C o m m itte e o n In s u la tio n (N a tio n a l R esearch C ouncil) a t U rb a n a , 111., 1934.

A New B u ret for P oten tiom etric T itrations

L. S. KEYSER, University o f Illinois, Urbana, III.

T

H E burets which are com­

monly used for potentio­

metric titrations are usually the o r d i n a r y s t r a i g h t ty p e or those which have the faucet type of stopcock. In many titrations where a stirrer, elec­

trodes, and other apparatus are necessary in or above the titra t­

ing r e c e p t a c l e , i t h a s b e e n found convenient to use the buret herewith illustrated. I t has the advantage of allowing control of th e s to p c o c k a t a comfortable distance from the encumbering mechanism over the reaction vessel. Although the buret is not available from laboratory supply houses, it can be easily constructed from the ordinary straight buret by anyone possessing a minimum of glass-blowing ability.

The tapered end of the stopcock tip is cut off a t its base as far from the stopcock as possible. The stopcock is then wrapped with asbestos cord or other suitable protection afforded and a length of glass tubing having the same approxi­

m ate dimensions is sealed on. The tube is then bent into the shape shown and the end drawn off to give a tapered point.

R e ceiv ed D ecem ber 31, 1935.

Laboratory Service T esting o f A u tom otive L ubricating Greases

E. N . K LEM G A RD , S h e ll Oil C o., M a rtin ez, C alif.

G

REASE manufacturers in the United States produce a n n u a l l y nearly 300,000,000 pounds of lubricating grease, which is sold for approximately

$18,000,000. Of t h i s t o t a l amount, 150,000,000 pounds of special grease, about 50 per cent, are c o n s u m e d in automotive units. As in other industries, grease manufacturers are in­

tently alert to new developments in mechanical engineering, par­

ticularly in the automotive field.

This is o n ly n a t u r a l , s in c e r o u g h ly one-half of the total am ount of grease produced is c o n s u m e d b y t h e motorist.

Special service tests for automobile lubricating oils and gaso­

line have been more or less standardized, but the service testing of lubricating greases has been largely a m atter of special technic developed as occasion necessitated by the grease manufacturer, automobile manufacturer, institution, or consumer. Because casual observation of service results in equipment on the road often leads to erroneous results and comparisons, laboratory service tests are frequently used to secure more precise data from which definite conclusions may be drawn. In some cases, a series of g re a s e s differing only s l i g h t l y in their usual proper- t i e s m u s t be studied to deter­

mine their relative s e r v i c e v a l u e . R o a d te s ts fo r thousands of miles might be needed to reveal p r a c t i c a l d if f e r e n c e s , but accelerated labora­

tory service tests can be d e v i s e d which enable defi­

nite comparisons to be made in a few hours.

Obviously, serv­

ice tests may be used for proving th at under a given set of conditions one grease is superior to another. The time-honored tests for melting point, pene­

tration, and per cent of water, soap, and ash, while of greatest value as control tests to secure uniform quality, leave too much to the investigator's imagination in predicting service performance. Carefully performed laboratory service tests are believed to be invaluable as indicators, pointing the direction in which definite improvements in automotive greases m ay be made.

Salesmanship m ust necessarily take into consideration

T h e im p o r t a n c e a n d n e c e s s it y o f d e v e lo p ­ in g se r v ice t e s t s o f v a lu e i n fo r m u la t in g i m ­ p ro v ed a u t o m o t iv e g re a se s a re e m p h a s iz e d in v ie w o f t h e g re a se in d u s t r y ’s d e sir e to m e e t m o r e a d e q u a te ly th e d e m a n d s o f m o d e r n ca rs, h ig h -s p e e d d r iv in g , a n d th e c o n s e q u e n t m o r e severe lu b r ic a t io n c o n d i­

t io n s . L a b o r a to ry serv ice t e s t s h a v e b e e n d e v ise d w h ic h p e r m it c o m p a r is o n s o f serv ­ ic e p r o p e r tie s t o b e a s c e r ta in e d m o r e q u ic k ly , e c o n o m ic a lly , a n d p r e c ise ly t h a n in m o r e la b o r io u s ro a d t e s t s . R o a d t e s t s are, h o w e v e r , c o n sid e r e d n e c e s s a r y fo r fin a l e v a lu a tio n o f se rv ice p r o p e r tie s.

color of the grease, odor, cus­

tomer appeal, attractive appear­

ance, and type of container, but performance m ust not be ig n o r e d . The discriminating purchasing agent, chemist, and e n g in e e r a r e f r e q u e n t l y in­

terested in knowing just how good a given lubricating grease is a n d how i t p e r f o r m s in service.

P r e s s u r e -G u n G r e a se

Fig u r e 1. Ap p a r a t u s f o r De t e r­ m in in g Re t e n t i o n Pr o p e r t i e s o f Pr e s s u r e- Gu n Gr e a s e s i n Sp r in g

Sh a c k l e s

M any of the cars on the road are equipped with some form of plain bushing shackle. In so m e cases, needle b e a r i n g s have been fitted into the king pins, and the development of “knee-action” front wheels has brought about modifi­

cations in steering mechanism bearings. However, the chief problem regarding the quality of pressure-gun greases is their ability to “stay in place.” For this reason service tests for determining the retention characteristics of such greases have been developed by grease m anufacturers and are of interest.

As with most lubricating grease problems, the viscosity of the mineral oil content, the consistency of the grease while being applied and while performing within the bearing, and the quality and am ount of soap m ay all influence results obtained in service. For this reason, precise service tests for establishing the value of these items are very difficult. T hat much research remains to be done can be inferred from the fact th a t one finds on the m arket different gun greases m anu­

factured with calcium, aluminum, and sodium soaps. Thus, the “experts,” who in this particular case m ust be the grease manufacturers, do not agree. Perhaps a condition exists which is similar to th a t occurring in the food and clothing industries: th a t which pleases one is rejected by another for psychological reasons. Technically it should be possible to

Fig u r e 2 . Mo d if i e d Ap p a r a t u s f o r De t e r m i n i n g Re t e n t i o n Pr o p e r t i e s

Pro d u ces m ore ra p id v ib ra tio n th a n d evice show n in F ig u re 1 83

84 IN D U ST R IA L A N D E N G IN E E R IN G CHEM ISTRY VOL. 8, NO. 2

Ta b l e I. Ph y s ic a l a n d Ch e m ic a l Te s t s o n Co m m e r c ia l Pr e s s u r e- Gu n Lu b r ic a n t s

L u b ric an t D esig n atio n

P e n e tra tio n a t 77° F . U nw orked W orked

D ro p p in g P o in t U bbe- lohde

K in d of

Soap Ash

S. U. V isco sity of M in eral O il C o n te n t

a t 100° F. T ex tu re

Flow of G rease th ro u g h Saybo U n iv ersal V iscosity T u b e 35° F . 77° F . 100° F .

355 A1 400 3S5 89 A lum inum

%

400 S m ooth

<?./m in.

0 .5

G ./m in . 9 .7

G ./m in

375 C a 301 362 375 97 C alcium l!0 4 301 S m ooth

340 C a 319 347 340 90 C alcium 1.0 6 319 Sm ooth

370 C a 350 375 370 90 C alcjum 350 S m ooth

314 C a 868 315 314 96 C alcium l'.Q l S68 Sm ooth

336 C a 335 323 336 C alcium 335 S trin g y

Sm ooth 0*3 2*. 0 15.1

318 C a 460 320 318 C alcium ll 3 4 460 0 .7 1 1 .0 2 5 .2

345 C a 310 342 345 C alcium 1 .7 m ax. 310 S m ooth 1 .4 1 9 .8

354 C a 315 354 354 C alcium 1 .7 m ax. 315 Sm ooth 2 .0 2 2 .8

335 A1 290 325 335 A lum inum 290 S m ooth 0 .3 7 .9 37 !o

321 C a 3000 (blown

saponifiable oil) 316 321 90 C alcium 3000 S trin g y 1 .1

319 C a 35 (latex) 309 319 88 C alcium 35 S trin g y 0 .2

227 C a 300 207 227 92 C alcium 300

318 C a 500 (poly­

iso b u ty len e) 318 95 C alcium 500

305 C a 310 (m illed) 305 305 91 C alcjum 310 0 .5 Va

285 C a 500 (latex) 285 95 C alcium 500 0 .2 2 .2

282 C a 425 282 C alcium 425 0 .3 5 .0

350 N a 3100 350 i3 5 Sodium 3106 T race 1 .1

450 N a 2500 450 Sodium 2500

390 A1 3000 390 i o i A lum inum 3000 T rac e

400 A1 1000 (app.) 400 A lum inum 1000

350 A1 1000 (app.) 350 A lum inum 1000

Oil 2000/100° F. 2000

determine which of two greases is best adapted to service in a given chassis bearing under given service conditions. How­

ever, the term “given service conditions” is a limitation which greatly restricts our general problem, and atmospheric temperatures, rain, dust, ice, wear, and design are variables which stand in the way of simplified service testing. The following method of testing has been worked out with a view to including the more normal types of operating conditions and thus forms the basis of opinions on retentivity as related to oil viscosity, consistency, type of soap base, and quantity of soap.

T e s t i n g P r e s s u r e - G u n G r e a s e s f o r R e t e n t i v i t y .

Either plain pin or screw-type shackle bolts have been adopted for the testing of pressure-gun greases in the appara­

tus shown in Figures 1 and

2

because they pre­

sent the most im portant c u r r e n t s h a c k le bolt lubrication problems. A m o d e l A F o rd f r o n t spring with shackles and a B u ic k s e r ie s 33-50 rear s p r in g s h a c k le , representing character­

istic plain pin and screw- type shackle bolts, re­

spectively, make it pos­

sib le to s t u d y reten­

tivity.

Fig u r e 4 Fig u r e 3 . Gr e a s e Re t e n t io n

Te s t s

F r o n t sp rin g w ith p la in bushing shackles on ch assis lu b ric a n t te ster.

C h arg e, 2.80 to 2.90 gram s of grease.

The actuating cam shown in Figure 1 was driven by a 3- horsepower electric motor through a 30 to 1 reduction gear.

This mechanism imparts a 2.5-cm. (1-inch) deflection to the spring 60 times per minute. The cam is so designed that after maximum lift it leaves the roller follower and the spring returns freely to normal position. The deflection may also be obtained by means of a suitably designed cam as in Figure 2.

Before each test the spring shackles were completely disas­

sembled and washed thoroughly w ith benzene, care being taken to remove all the old grease from the grease ducts and fittings.

After thorough drying, the shackles and bolts were assembled, making certain that all interchangeable parts were replaced in the positions from which they were taken.

A small screw-type grease gun was filled with the grease to be tested and weighed on a balance to the nearest 0.05 gram. Each shackle was charged with grease until it showed signs of being forced out at the ends of the shackle bolt bushings. The filling gun was then reweighed and a small pad of cotton was used to wipe off the excess grease. The increase in weight of the cotton, subtracted from the loss of weight of the gun, gave the weight of grease charged to the shackle. The clearance between shackle and bushing was maintained at approximately 0.02 cm. (0.008 inch).

One form of grease-retention test consisted of taking a set of six readings during a 2-hour test period, the first four being taken at the end of 15-minute periods and the last two at the end of 0.5-hour periods. The readings were obtained by shutting the motor down and wiping the edges of the shackle bolts and bush­

ings thoroughly with a weighed wad of cotton, and then measur­

ing the increase of weight of the cotton.

An examination of Figures 3, 4, and 5 reveals th a t neither the kind of soap base, the viscosity of the oil content, the penetration value, nor slight variations in soap content alone

M ARCH 15, 1936 ANALYTICAL E D IT IO N 85 make one product better than another. Probably the com­

bination of these factors and the modifying agents present which influence adhesion, aeration, and stability of the grease while in the shackles are the im portant items in determining the retentivity of a pressure-gun grease.

Grease 305 Ca 310 (Figure 4) shows a loss of 22 per cent in the

2

-hour retention test (first number indicates worked pene­

tration; second, soap base symbol; third, Saybolt Universal viscosity of oil content a t 37.78° C., 100° F.). Grease 354 Ca 315 is similar with regard to penetration, type of soap, and mineral oil viscosity, but shows a loss of 28.8 per cent. A possible explanation of this difference is th a t the first grease has been milled to stabilize it, thus increasing its retentivity.

I t therefore m ay be concluded th a t the usual tests for pene­

tration, soap base within certain limits, and oil viscosity do not accurately indicate the degree of retention which m ay be expected from a given pressure-gun grease. I t also follows th a t further research towards establishing a correlation be­

tween retention, pressure viscosity, and stability of the grease film within the bearing are greatly needed.

R e t e n t i v i t y o f P e e s s u r e - G u n G r e a s e s i n P r e s e n c e o f W a t e r . In order to obtain information as to whether or not an aluminum stearate-base grease was more resistant to the action of rain water than a lime-base grease, the retention tester discussed above and shown in Figure 1 was equipped with a water-spray apparatus.

Alterations made in equipment consisted in the addition of a device for spraying water upon the shackles, and the building of a small tank about the apparatus to collect the water sprayed upon the shackles. The spray apparatus consists of two atomizers dipping into a tray o f water. The two atomizers are operated by air under pressure, the intensity of the air jet being controlled through the use of an air valve and a pressure gage. The spray apparatus was placed in position so that a fine spray of water could be thrown up on the shackles.

Modifications of this device have undoubtedly been devised by others for splashing, dripping, or spraying w ater onto the shackles. The device as used is a simple method of obtaining a gentle washing action analogous to w hat m ight be m et in service in storm y weather. The rebound of spray from the side of the tank and other parts of the apparatus results in water contacting the shackles from every direction from which water might come in actual service. The test conditions can also be fairly well reproduced by controlling the air pressure and the level of the w ater in the tray.

T a b l e II. R e t e n t i o n o f G r e a s e

(L u b ric a n t te ste r as sh o w n in F ig u res 1 a n d 2, p la in shackles, 2-hour te st period, fine s p ra y of w ater)

G rease 335 A1 283 G rease 354 C a 327 K in d of soap

P e r c e n t of soap W orked p e n e tra tio n O il v isco sity , S. U . a t 100° F . C h arg e of grease, gram s

T o ta l w a ter sp ra y on sh ack les, lite rs W a te r w iped fro m b e arin g surfaces and

grooves, g ram s

G rease w iped from b earin g surfaces an d grooves, gram s

G rease o b ta in e d b y p ressure-benzene tre a tm e n t

T o ta l grease re ta in e d , gram s P e r c e n t re te n tio n

The spring, shackle bolts, and the crossbar from which the spring and shackles were suspended were assembled outside the tank which surrounds the lift cam. An excess of grease was forced through the Zerk fittings of the apparatus and measurements made as previously described.

A 2-hour test period was selected. This was consistent with previous tests carried out in the absence of water, in which the length of the test period was 2 hours. Except for

A lu m in u m C alcium

10 .2 7 .9

335 354

283 327

2 .8 1 2 .8 1 2 .8 8

12 .5 0 12 .1 5 12.20

0.1 4 1 0 .2 3 5 0 .3 0 2 0 .1 6 0 0 .1 4 9 0 .1 7 9

1.241 1.3 2 0 1.302

1.401 1.469 1.481

50 52 51

Fi g u r e 6 . Un i v e r s a l Jo i n t Gr e a s e Se r v i c e Te s t e r, Vi e w e d f r o m Ab o v e

E le c tric d y n a m o m e te r a t rig h t for a b so rb in g pow er tra n s m itte d . N o te m eth o d fo r d e te rm in in g te m p e ra tu re s w ith in jo in ts b y m eans of th e rm o ­ couples a n d sh ield fo r a cc u m u la tin g grease th ro w n fro m jo in t.

the spray playing on the shackles, the conditions of the test were identical with those of tests carried out on a dry basis.

I t was not possible to carry out observations on the amount of grease leaving the shackles a t 15-minute or 0.5-hour inter­

vals so as to obtain a retention-time curve.

The problem of recovering the grease from the water sprayed on the shackles was given consideration. However, this seemed impractical since the surfaces of the interior of the tank were large and the surfaces of the springs were irregular and likely to retain a certain amount of grease in crevices.

The removal and measurement of the grease retained on the bearing was resorted to since the surface areas were smaller and easier to work with.

The results shown in Table I I were obtained in the test.

The results on the two greases are in fairly close agreement, except in the am ount of water removed from the shackles.

However, these water figures are not very reliable, since losses are bound to occur through evaporation of water and probably also the loss of droplets of water from the shackles in removing shackle bolts. Neither grease showed any evi­

dence of émulsification in the shackles as the result of the entrance of water.

The comparison between these two greases seems to be a fair basis for comparison of calcium- and aluminum-base chassis lubricants under wet conditions, since the oil viscosi­

ties, consistencies, and soap contents of the two greases were similar.

A complete investigation of the effect of w ater on shackle lubrication would of course include an investigation of screw-type shackles as well as plain shackles, and also the effect of different methods of bringing w ater in contact with the shackles. The effect of high-pressure washing should be of special interest in this regard. The effect of oil viscosity, soap content, and glycerol content on retention under wet conditions might also be investigated. However, since the results so far obtained show so little difference in the behavior of calcium- and aluminum-base greases in the presence of water, it is doubtful if much information of value would be obtained by further work on a comparison of aluminum- and calcium-base greases, although a comparison with sodium- base grease would no doubt be of interest.

Ordinarily, it is considered th a t tem perature conditions m et with in pressure-gun grease service are so low th a t high melting point soda-base greases are unnecessary. Since speeds and load are low, extreme pressure agents in most cases appear to be unnecessary.