Industrial and Engineering Chemistry : analytical edition, Vol. 13, No. 8

INDUSTRIAL ^{a n d} ENGINEERING CHEMISTRY

A N A L Y T IC A L E D IT IO N

H A R R IS O N E. HO W E, E D I T O R « ISSUED A U G U S T 15, 1941 » VO L. 13, NO. 8 • C O N S E C U T IV E NO . 16

M ineral Oil D eterioration S y s t e m ...

J. C. Balsbaugh and A. G. Assaf 51S New L aboratory F ra ctio n a tin g C o lu m n Head . . .

Tzeng-Jiueq Suen 519 Speotroch em ical A nalysis of Trace E lem en ts in F er­

tilizers. B oron, M an gan ese, an d Copper . . . . Eugene H. Melvin and Robert T. O ’Connor 520 R ou tin e D e te r m in a tio n of P h osp h oru s an d Su lfu r

in C o k e ... Louis Silverman 524 Role of V elocity G radient in D eterm in in g C upram -

m o n iu m F lu id ity of C ellu lose . . Carl M. Conrad 526 C olorim etric D eterm in a tio n of Copper w ith A m ­

m o n ia ...J. P. Mehlig 533 D eterm in a tio n of S olu b le S ilica in W a t e r ...

H. Lewis Kahler 536 A nhydrous S o d iu m T h io su lfa te, P rim ary Standard

Hazel M. Tomlinson and Frank G. Ciapetta 539 Q u an titative S p ectro ch em ica l M eth od for Z inc D ie

C asting A nalysis . . M. F. Hasler and C. E. Harvey 540 Rapid P relim in ary D e te r m in a tio n of M eltin g P o in ts

Glenn W. Stahl 545 D eterm in in g M eta llic Iron in Iron Oxides an d Slags

John P. Riott 546 M ethods for C larifying O xidized or U sed M ineral

O ils and D eterm in in g S lu d ge . . . . G. O. Ebrey 549 T h iocyan ate M eth od for I r o n ...

J. T. Woods with M. G. Mellon 551 Amyl N itrite . . . R. G. Horswell and Leslie Silverman 555

Cerate O xidim etry. D eterm in a tio n of G lycerol . . Gr. Frederick Smith and F. R. Duke 558 Procedure for V olu m etric D eterm in a tio n of G old by

M eans of P o ta ssiu m Iodide and A rsenious Acid . Victor E. Herschlag 561 Im proved T a n g en tim eter . . . . Howard P. Simons 563 D evice for S ta rtin g S w in gin g o f B a la n c e ...

Richard E. Vollrath 564 M agnetic Stirrer for a n E vacuated S orp tion A ppa­

ratu s . . Samuel A. Woodruff and Alfred I. Stamm 565

MICROCHEMISTRY

M icrobiological A ssay for P a n to th en ic Acid . . . F. M. Strong, R. E. Feeney, and Ann Earle 566 M icroanalysis of G a s e s ...

W. L. Haden, Jr., and E. S. Luttropp 571 Separation of C alciu m N itrate from S tr o n tiu m

N itrate by M on ob u tyl E ther of E th y len e G lycol H. H. Barber 572 R eport on R ecom m en d ed S p ecification s for

M icrochem ical A pparatus . . . . G. L. Royer, H. K. Alber, L. T. Hall^tt, W. F. Spikes, and J. A. Kuck 574 M icrocham ber for Low T e m p e r a tu r e s ...

Zaboj Harvalik 581 D eterm in a tio n of Lead in B iological M aterial . .

Jacob Cholak and Karl Bambach 583 V olum etric T ubes for S m a ll V o l u m e s ...

Frederic E. Holmes 586 M icroscopy of A m in o A cids and T h eir C om pounds

Kaoru Inouye, Russell Sunderlin, and Paul L. Kirk 587

T h e A m e ric a n C h e m ic a l S o c ie ty a s s u m e s n o r e s p o n s ib ility fo r th e s ta te m e n ts a n d o p in io n s a d v a n c e d b y c o n tr ib u to r s to its p u b lic a tio n s .

2 5 ,4 0 0 co p ies of th i s issu e p r in t e d . C o p y r ig h t 1941 b y A m e ric a n C h e m ic a l S o c ie ty .

P u b lic a tio n Office!

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

P u b lis h e d b y th e A m e ric a n C h e m ic a l S o c ie ty , P u b lic a tio n O ffice, 2 0 th &

N o r th a m p to n S ts ., E a s t o n , P e n n a . E n t e r e d as seco n d -c la s s m a t t e r a t th e P o s t Office a t E a s to n , P e n n a ., u n d e r th e A c t o f M a rc h 3, 1879, as 24 tim e s a y ea r I n d u s tr ia l E d itio n m o n th ly o n th e 1 s t; A n a ly tic a l E d itio n m o n th ly on th e 1 5 th . A c c e p ta n c e fo r m a ilin g a t sp e c ia l r a t e o f p o s ta g e p r o v id e d for m S e c tio n 1103, A c t of O c to b e r 3, 1917, a u th o r iz e d J u l y 13, 1918.

A n n u a l s u b s c r ip tio n r a t e , I n d u s tr ia l E d itio n a n d A n a ly tic a l E d itio n sold o n ly a s a u n it , m e m b e rs S 3.00, o th e r s $4 .0 0 . F o re ig n p o s ta g e to c o u n trie s n o t in th e P a n A m e ric a n U n io n , S 2 .2 5 ; C a n a d ia n p o s ta g e , SO.75.

E a s t o n , l V n n a .

A d v e r t i s i n g D e p a r t m e n t : 3 3 2 W e s t 4 2 n d S t r e e t , N e w Y o r k , N . Y . T e l e p h o n e : B r y a n t 9-4-130

S in g le co p ies: I n d u s tr ia l E d itio n , $ 0 .7 5 ; A n a ly tic a l E d i tio n , $0 .5 0 . S p ecial r a t e s to m e m b ers.

N o c la im s c a n b e allo w ed fo r co p ies of jo u r n a ls lo s t in t h e m a ils u n le ss s u c h claim s a r e re c e iv e d w ith in 60 d a y s of th e d a t e of issu e, a n d n o claim s w ill b e allo w ed fo r issu e s lo s t a s a r e s u lt of in s u ffic ie n t n o tic e of c h a n g e of a d d re s s . (T e n d a y s ’ a d v a n c e n o tic e re q u ir e d .) “ M issin g f ro m files*' c a n n o t b e a c c e p te d a s th e r e a s o n fo r h o n o rin g a c laim . A d d re s s claim s to C h a rle s L . P a rs o n s , B u s in e s s M a n a g e r , 1155 1 6 th S tr e e t, N . W ., W a s h in g to n . D . C „ U . S. A.

4

9deai josi (leA&aticli ^—

t h e Reinforced

I n t e r n a t io n a l S iz e 1, T y p e SB ^C e n t r if u g e

1 8 , 0 0 0

r.p.m.

W ITH

MULTISPEED ATTACHMENT

O ther features of the R e in f o r c e d " S ize 1, T y p e S B " include:

• Indicating Tachometer.

• Automatic low voltage cut-off.

• Brush release and hand brake.

• 50 step speed controller.

• Flexible motor drive.

The R e i n f o r c e d S i z e 1, T y p e S B C e n tr ifu g e is particularly suited for the busy research lab ­ oratory b e ca u se of its adaptability to the exact­

in g and various dem ands of this work. It is eq u ip p ed with an all-w elded steel en closin g guard (as show n here) for safety w h en operat­

in g four 250 ml. cu p s at 3,000 r.p.m. or the M u l t i s p e e d A t t a c h m e n t at 18,000 r.p.m.

OR

4— 250 ml. CUPS A T 3,000 r.p.m.

D ue to its efficien cy at high sp eed s and pow er for capacities up to 1 liter, the ",S i z e 1, T y p e SB " has b ecom e very popular with research workers. The portable stand provides sufficient stability and the co n v en ie n c e of an easily m ovable unit without the ex p en se of a perm anent m ounting.

I n te r n a tio n a l C e n tr if u g e s are furnished in m any types and sizes, all of the finest materials and d esign ed , so far as possible, to allow for future adaptation of im proved a ccessories as d ev elo p e d by the n ew principles of ad van ced technique.

W rite for Bulletin C l

IN TE R N A TIO N A L EQUIPMENT CO.

352 W ESTERN A V E N U E Makers of Fine Centrifuges B O S T O N , M A S S .

August IS, 1941 A N A L Y T I C A L E D I T I O N 5

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

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

MULTIPLE UNIT

REG. U. S. PAT. O f f

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

Mm

C h e m ic a l L a b o r a t o r y a t A n n A r b o r

(m d HEYI DUTY FURNACES

T

^U

M

, lik e m a n y other out­

stan d in g u n iversities in the country, h a s found that

H evi D u ty O r g a n ic C o m b u stio n F u r n a c e s g iv e m a n y

y e a r s of satisfactory serv ice. . . . . A sk your laboratory

su p p ly d ea ler or w rite for Laboratory Furn ace B ulletins.

6

Prepared in cooperation with the technical and research staff o f N O R T O N C O M P A N Y , Worcester, Mass.

H o w Y o u

C an Ign ite in the D e v ic e Y o u U s e to F ilter

D u e to its great refractoriness, A L U N D U M (A120 3) laboratory ware can be w ashed and ignited to constant w eigh t as so o n as you have finished a filtration. Thus the devices (dishes, cones, crucibles, discs, thim bles) can be used over and over. Besides their chem ical inertness, detailed in the next paragraph, and their sem iperm anent usefulness, A L U N D U M devices have the advantage o f b ein g offered in various porosities. R A 84 is dense, R A 360 m edium , R A 98 coarse.

R A is H ig h ly R esista n t to A b r a sio n , R ea g en ts and

S o lv en ts

A L U N D U M laboratory ware — the letters R A refer to A L U N D U M m ix ­ tures chem ically controlled — resist all organic solvents, and can be attacked on ly by hydrofluoric acid and strong caustic solutions.

I f you are filtering or extracting, these shapes are especially adapted for the fo llo w in g uses:

D IS C S

For small amounts o f suspended matter.

C O N E S

For Invert Sugar, organic and inorganic filtrations and determinations.

D IS H E S

For washing and drying crystals and washing precipitates.

T H IM B L E S

For extraction o f feeds, tar, chocolate, rubber and fats. Copper and fatty acid determina­

tions.

C R U C IB L E S

For fine (Barium Sulphate) and coarse (Silver Chloride) precipitates. Used also in Mn, Pb, Sn and Si determinations.

Important Footnote: for Crude Fibre de­

terminations, you may obtain the special mixture RA 766, o f greater porosity than

RA 98. Perhaps you have a specific problem in laboratory ware requiring the more-than- ordinary attention which we would give it.

G ettin g the R ig h t R efractor)' C em en ts for R esisto r- W o u n d E le ctr ic F u rn a ces

T h e picture show s an externally w ound A L U N D U M C onical Core with cem ent partially applied. Occasionally, the cem ent w ill react w ith and destroy the resistor elem en t under operating con d ition s. It’s so m eth in g to lo o k out for, i f you ’re d esign in g or constructing electric furnaces for your laboratory.

W rite for our b ook let, "T he Construc­

tio n o f E lectric Furnaces for the Laboratory." It g ives the com p lete story.

NORTON RESEARCH

INGREDIENT NUMBER O N E IN FUSED ALUM INA LA B O R A TO R Y W ARE

NORTON LABORATORY WARE Distributed by the following:

Central Scientific Co., Chicago and Other Cities

Eimer and Amend, New York City Fisher Scientific Co., Pittsburgh Arthur H. Thomas Co., Philadelphia E. H. Sargent & Co., Chicago

Braun Corp., Los Angeles Braun, Knecht, Heiman, San Francisco

Or simply order through your favorite Laboratory Supply House

August 15, 1941 A N A L Y T I C A L E D I T I O N 7

CONSTANT TEMPERATURE

OVEN

AIR DRYING

The C en co C ylindrical Constant Temperature O ven has a drying cham ber 14^2 in ch es in diam eter by IOV4 in ch es d eep . It m ay b e set to operate at any temperature from a few d e g ree s above that of the room to about 210° C. C onstancy at any tem pera­

ture is w ell within the allow able range of tem pera­

ture variation for all ordinary work. Precision of regulation at 100° C is w ell within a variable of 1° C.

95050

Uniformity of tem perature distribution is e x cellen t.

Departure from the average tem perature at any point in the operating range is within 10 C. At m axi­

mum temperature only 400 watts are required — about 40% less than required for an electric toaster or flat iron.

95050A C e n c o - D e K h o tin s k y O v e n , for 115 or 230 volts A .C ... $85.00

V A C U U M D R Y I N G

with accessory

VACUUM CHAMBER

C H I C A G O 1700 Irving Park

Blvd.

Lakeview Station

J g B

S C I E N T I F I C INSTRUMENTS

N e w Y o rk • B o sto n •

m

C H I C A G O

LA B O R A TO R Y A P P A R A T U S

• T o ro n to • San F ra n c is c o

B O S T O N 79 Amherst St.

Cambridge A Station 95055 shown in no. 95050 Oven.

The n e ed for greater sp eed in com pleting dry­

in g operations brought so m any requests for a vacuum oven, similar to No. 95050 C enco- DeKhotinsky O ven, that w e are now offering a vacuum cham ber w hich can b e inserted into the cham ber of this oven. The cham ber m ade of tinned steel permits em ploym ent of tem ­ peratures as high as 150° C and pressures as low as a fraction of a millimeter. C om plete with vacuum connections and dial vacuum g a g e, but w ith o u t thermometer.

95055 V a c u u m C h a m b e r ... $45.00

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

IT’S THE

LONG-RUN COST

THAT COUNTS!

W h e n yo u bu y a H oskins combustion fu rn a c e , y o u ’ll find it la sts so long th a t its m ain te n a n ce cost p e r y e a r a p p ro a ch e s a figure th a t’s triv ia l. N ot o n ly is yo u r se n se of th rift sa tisfie d —yo u r p e rfo rm an ce re q u ire m e n ts a r e also fu lly m et. . . . H oskins M anufacturing C o ., D etro it, M ichigan.

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 T S • • T H E R M O C O U P L E A N D LEA D W IR E • • P Y RO M ETERS • • W E L D IN G W IR E • • H EA T R ES IS T A N T C A S T IN G S • • EN A M ELIN G FIX TU RES • * S P A R K P LU G ELECTR O D E W IR E . * S P E C IA L A L L O Y S O F N IC K E L • • P R O T E C T IO N TUBES

(Left) To ap p ly a Chrome I unit in the FD furnace is as e a sy as wrapping a rope around a stick.

(Right) Type F H -30 3 -A ; operates on A .C . only through a transform er. H e a v y Chrome I unit, g o o d fo r 2 0 0 0 0 F . [Right) O perates directly on the

line without transformer. Tempera­

ture Is controlled b y rheostat.

The form er 5" O .D . of the case is n o w 7 * , w ith corresponding In­

crease In heat-insulation.

A t 2 0 0 0 ° F.,form er case temperature of 3 9 3 ° is n ow 1 3 5 ° cooler. Hold­

ing w attage ha s been reduced 14%.

Heating unit, a single Chrom el coil, that v e ry e a s ily is w rapp ed around the grooved tube.

A given furnace built for one given voltage permits a h ea vier Chrom el unit that lasts longer.

Recom m ended m axim um operat­

ing temperature is 1 8 0 0 ° F. for FD ; and 2 0 0 0 ° F . for FH (below ).

Hoskins com bustion furnaces are cheaper in the long run. Send for descriptive folder.

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

August 15, 1941 A N A L Y T I C A L E D I T I O N 9

L A B O R A T O R Y C O E M ! C A L S

1 9 1

M E R C K & CO. Inc.

RAHWAY, N. J,

NEW YORK • PH ILA DELPHIA • ST. LOUIS Id C o n e d a : M ON TREA L • TO RO N TO

j ÿ i i v "

CONTENT:

A com p reh en sive list o f M erck Laboratory C hem icals w hich are u sed in every branch o f industry

M olecular w eights Chem ical Form ulas

M axim um im p u rities o f M erck R eagent C hem icals, in clu d in g th ose w h ich con ­ form to A.C.S. sp ecification s

Proper storage o f fine ch em icals

^ A tom ic w eights M etric eq u ivalents U seful con version ratios E quivalent o f d egrees B aum é.

W rite to d a y f o r a co p y o f this convenient a n d h elpfu l ca ta lo g

M E R C K & CO . I n c . tÀ ia n u ^a c tu n in ÿ, C€ /e m iitâ R A H W A Y , N. J.

Please send m e a co p y o f the new Me r c k La b o r a t o r y Ch e m ic a l s Ca t a l o g.

N A M E ... ...

C OM PANY...: ...

S T R E E T ...

C IT Y ... S T A T E ...

10

A . H . T . C O . S P E C I F I C A T I O N

FLUO RESCENT DAYLIGHT BALANCE IL L U M IN A T O R

P ro v id in g m a x im u m lig h t on th e front o f t h e b a la n c e b e a m a n d p o in te r

in d e x

BALANCE ILLUM INATOR, FLUORESCENT DAY­

LIGHT, A.H .T. Co. Specification. For use directly on top of an analytical balance case. Reflector insures maximum light on the front of the balance beam and pointer index.

Tem perature rise inside the balance case at beam level, due to heat radiation from the bulb, is negligible.

Consisting of 15-w att fluorescent bulb, 18 inches long, m ounted in ventilated m etal housing finished on inside with high reflecting w hite and on outside in dull black. Overall dimensions, IS 1/« inches long X 6 inches wide X 33/ 3 inches high; m ounted on felt feet; fits a wide variety of analytical balances, i.e., those w ith cases 14‘/ 2 inches or more in width.

The new fluorescent bulb gives a cold, diffused, glareless light w ith characteristics similar to natural daylight. E sti­

m ated life of the bulb is approxim ately 2500 hours. Bulb is of the electric discharge type and em ploys mercury vapor to sustain the arc. Each lam p is furnished w ith ballast, i.e., special choke-coil with arc starting device, as required for operation on 110 volts. Starting is ac­

complished b y m eans of a push-button switch which insures positive operation.

2072-F. Balance Illuminator, Fluorescent Daylight, A.H.T. Co. Specification, as above described, complete with 15-watt, fluorescent daylight bulb, ballast, push-button starting switch, cord and plug. For 110 volts, 60 cycles, a.c.

on ly...'... 14.75

Code Word... Aruhl 10% discount in lots of six

2072-F.

C O O R S M U L L IT E M O R T A R S

Offered as a satisfactory substitute for Agate M ortars because of M u llite’s extrem e hardness and freedom from defects

7329.

COORS MULLITE M ORTARS. Coors M ullite is an alum inum silicate compound, fired at tem ­ peratures above 3000°F, which provides a sm ooth, w hite, hom ogeneous grinding surface comparable with agate in hardness and less brittle in use. Hard materials such as minerals can be ground very satisfactorily in M ullite mortars. T ests indicate that M ullite will replace agate for use in mortars, irrespective of cost or availability of agate. Each M ortar is furnished com plete with pestle of m ullite.

7329. Mortars, Coors Mullite, as above described.

Overall diameter of mortar, mm... 35________50_______ 65_______ 75________ 90_______ 100______ 120 Each, complete with pestle... 2.20 2.90 4.65 7.15 10.50 13.35 18.65 Code Word... Krill Kriuj Krivh Kriwf Krixd Kriyb Kroon

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

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

L A B O R A T O R Y A P PA R A TU S A N D R EA G EN TS

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

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

INDUSTRIAL ^{a n d} ENGINEERING CHEMISTRY

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

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

M ineral Oil D eterioration System

J. C. BA LSBAU G H AND A . G. A SSA F

M a ssa c h u se tts I n s tit u te o f T ech n o lo g y , C am bridge, M ass.

T

cations, such as for electrical insulation and for lubrica­

tion, depends upon an interpretation of the initial properties or characteristics of the oil in terms of the deterioration char­

acteristics in service. Such interpretation depends upon funda­

mental studies, appropriate deterioration tests, and service records. T he general qualities of mineral oils for insulation, lubrication, and other uses can to som e exten t be determined by subjecting the oil to short-tim e

aging tests, although these tests do not fully represent long-tim e service con­

ditions. Provided the results can be properly interpreted, short-tim e tests which last for a few days or w eeks are to be preferred to service tests which may continue for years. Further, arti­

ficial deterioration under laboratory conditions, where there is more flexi­

bility and better control of the variables involved, gives fundam ental informa­

tion about the deterioration mechanism which is difficult to obtain from other tests.

The most common method of deterio­

rating insulating oils is to oxidize the oil either alone or in the presence of other materials, the oxidation being carried out at an elevated temperature to increase its rate. A modified aging treatment is to heat the oil in an inert atmosphere for an extended time, either alone or in the presence of other substances. A combi­

nation of these treatments, which ap­

proximates conditions in practice, con­

sists in oxidizing the oil until a definite quantity of oxygen has reacted and then continuing the deterioration by heating in the absence of oxygen. As catalysts, the materials added may be powdered or bulk metal oxides such as copper and lead oxides, soaps such as copper naphthenate or stearate, or pure metals such as copper (wire or cubes). Paper, which absorbs some of the oxidation products and may possibly be a source of oxygen, may be added in aging processes to approximate conditions in a cable. Other aging treat­

ments consist in subjecting the oil to bombardment or exposing it to ultraviolet light. A different approach to the cable problem consists in aging short lengths of cable by subjecting them to various con­

ditions of temperature and voltage.

However, in the authors’ laboratory aging tests have been made using oxygen or nitrogen (or both), with and w ithout catalysts. The deterioration of an oil is accompanied by the liberation of volatile products, the addition of oxidation prod­

ucts to the oil, and changes in the physical and electrical properties. Since the chemical and physical changes which occur give a measure of the progress of the deterioration, the ideal procedure would be to follow accurately and com pletely all the changes which occur; but this a t present is neither pos­

sible nor practicable. Ordinarily a definite property or set of properties is measured as the deterioration progresses. The properties selected are dictated in m any cases by lim itations of the apparatus used, and to a large extent b y the field of application of the oil. In order th at the lim itations imposed by the apparatus m ay be eliminated as far as practicable, special attention has been given to the design of system s for deteriorating mineral oils by oxidation and heating. T he features th at have been sought are given here:

■

Fi g u r e 1 . El e c­ t r i c a l Me a s u r­

i n g Ce l l

Fi g u r e 2 . Th r e e- Te r m i n a l Pl a t i n u m- Gl a s s El e c t r i c a l Me a s u r i n g Ce l l

515

An all-glass apparatus A closed system

An adequate dispersion of the gas phase in the oil and an adequate circulation of the liquid phase

A system which permits oxygen absorption measure­

ments to be made

A method of withdrawing samples at intervals A means for adding catalysts and other materials Provision for removing or retaining volatile products as desired

The ability to make electrical measurements on the sample in the deteriorating system

A system which will permit making studies on small volumes of oil, so as to make practicable work with straight hydrocarbons or special samples that may be taken from various stages of a refining process

Fi g u r e 4 . De t e r i o r a t i o n Ce l l

Fi g u r e 5 . De t e r i o r a t i o n Ce l l w i t h El e c t r i c a l

Me a s u r i n g Ce l l s

The cell is of the three-electrode type for precise measurements and is of platinum-glass construction to give a minimum elec­

trode effect on the sample, and to permit effective cleaning.

The principal parts of the cell as indicated in Figure 1 are:

a guard section, tube 1, 6.25 mm. (0.250 inch) in outside diameter by 0.175 mm. (0.007 inch) wall, sealed to a No. 15 ground joint, 2, through a graded seal; a measuring section, tube 3, and guard section, tube 4, each 0.250 inch in outside diameter by 0.007 inch wall supported by glass seals 5 and 6 from tube 7, this tube being supported from the assembly supporting guard tube 1 by glass seal 8; a high-voltage section, tube 9, 9.1 mm. (0.364 inch) in outside diameter by 0.007 inch wall supported by three glass pillars, 10 and 11, at each end from guard tubes 1 and 4.

Electrical connections external to the cell are made with 20-mil platinum wire spot-welded to the appropriate electrodes; guarded lead 12 with glass spacer 13 for connection to measuring section 3 and supporting tube 7; high-voltage lead 14 sealed in ground joint at 15; guard connection is made directly to guard support­

ing tube 1 external to the cell with guard tubes 1 and 4 connected together by lead 16 within the cell.

W hile different relative dim ensions m ay be used in the con­

struction of a cell of the typ e described, the cells normally used have been made w ith a measuring section length of 2.5 cm. (1 inch) and a 50-mil spacing, giving a vacuum capaci­

tance of approxim ately 4.lMA*f- The length of the cell shown is determined principally by the size of the deterioration cell in which it is used and the m aintenance of the ground-glass joints external to the oven in which the deterioration cell is placed. T he size of th e cell m ay be decreased from th at shown and described, and can be constructed so th a t th e oil volume required for a measurement is principally th a t contained be­

tw een the measuring electrodes. T hus, it m ay be adopted to measuring sm all volum es of oil, the present cell requiring only 3 cc.

D e te r io r a tio n C ells

The deterioration cells for containing the oil sam ple and other material such as copper and paper, and th e electrical

Fi g u r e 3 . De t e r i o r a t i o n Ce l l

The quantity of oxygen absorbed in a unit w eight of oil is considered to be the independent variable in an oxidation study, although th e tim e during w hich th e oil is subjected to oxidation m ay be used as th at variable. T he latter quantity m ust be considered, but is n ot sufficient in itself, because the rate a t w hich oxygen is absorbed b y an oil varies w ith tim e for a given oil and the rate of absorption as a function of tim e is greatly different for different oils.

E le c tr ic a l M e a su r in g C ells

T h e electrical measuring cell (1) is shown schem atically in Figure 1 and in assembled form in Figure 2. T he cells are also showm as used in the deterioration cells for electrical measure­

m ents during a deterioration test in Figures 5 and 6. These cells are utilized for making such measurements as conduc­

tiv ity , loss factor, and dielectric constant of th e oil and an oil- im pregnated paper sam ple a t intervals during the deteriora­

tion.

August 15, 1941 A N A L Y T I C A L E D I T I O N

Fi g u r e 6 . De t e r i o r a t i o n Ce l l w i t h El e c t r i c a l Me a s u r i n g Ce l l s a n d Pr o­ v i s i o n f o r Wi t h d r a w i n g

Sa m p l e s

Fi g u r e 7 . Oi l- De g a s s i n g Eq u i p­

m e n t

measuring cells (when electrical measurements are desired on the oil sample in th e system during the test), are shown in Figures 3, 4, 5, and 6. T he cell in Figure 4 is used only when the oxidation kinetics is desired, and th e cell in Figure 5 when electrical measure­

ments are to be obtained in addi­

tion. A cell of the typ e shown in Figure 5 is m ounted in an oven

(Figure 8) w ith the degassing apparatus assembled for degas­

sing an oil into the cell. T he cell of Figure 6 has been used for larger volum es of oil sam ples, so as to permit withdrawal of samples for chemical tests during the deterioration. This type of cell also has the electrical measuring cells placed in the main body of the sam ple instead of in connecting tubes as in the cell of Figure 5.

The cell of Figure 5 is shown schem atically in Figure 3.

The principal parts are: a chamber, 1, of approximately 150-cc.

volume for containing the sample and such contact materials as may be desired: a gas and liquid pump consisting of a plunger with “sealed in” iron core operating in tube-2 and ground-glass ball valves, 3 and 4. with ground seats; tubes 9 and 10 with ground joints 11 and 12 for containing the electrical measuring cells; tube 2 with ground joint 16 which is used for admission of the oil sample into the system and for connection with the auto­

matic pressure regulating the oxygen feed system; support 13 serving as a stop for the reciprocating plunger operating in tube 2;

and baffle 14 to prevent the contact materials included with the oil sample, such as copper and paper, from entering tube 7 and fouling the operation of the pump.

The method of operation is as follows: The plunger is given a reciprocating vertical motion by means of a solenoid mounted concentric with tube 2 as shown in Figure 8. The plunger dis­

placement on the upward stroke opens valve 3 and closes valve

4, thus drawing gas from above the sample in chamber 1 through tubes 5 and 6 and then up through valve 3 and tube 7, and dis­

persing it through the sample in chamber 1. The plunger dis­

placement on the downward stroke opens valve 4 and closes valve 3, thus causing oil to flow through tube 8, upward through valve 4, and then successively through tubes 9 and 10 containing the electrical measuring cells, and into the sample chamber, 1.

Experience with a reciprocating glass plunger operating in a glass tube has shown that excessive grinding of the glass surfaces will take place even when the contact surfaces are under oil.

This is prevented in these cells by separating the normal glass con­

tact surfaces by platinum wire fastened to the plunger. This is shown at the top of the plunger in Figure 5. Also the plunger seat (13, Figure 3) is provided with a platinum wire ring to pre­

vent glass-to-glass contact at the bottom of the plunger stroke.

The plungers in these cells have been operated at rates of 10 to 30 strokes per minute, giving a pumping rate for both liquid and gas of the order of 20 to 60 cc. per minute. While these values can be easily increased or decreased, the rates given have been effective.

In the cell shown in Figures 3 and 5, the contact materials such as paper and copper are introduced into the cell through tubes 2 and 5 with the plunger removed from the cell. The paper is in the form of disks, approximately 0.5 cm. in diameter, and the copper in the form of spirals 0.5 cm. in diameter and 2 to 3 cm.

in length, using No. 36 copper wire.

The cell of Figure 4 has a ground flange and cover plate wliich permits use of paper disks approximately the diameter of the cell chamber. These disks have holes in them to permit effective contact of the oil with the paper and adequate gas and liquid circulation. This method permits a maximum amount of paper for a given volume of oil. The pound cover plate is sealed to the flange by water glass applied between the ground surfaces.

In the cell in Figure 6 the aaded materials are put into the cell through one of the ground joints supporting an electrical cell.

In this system an oil sample may be removed from the cell through the capillary tubing, stopcock, and ground joint shown, into a sampling tube mounted on the ground joint. The oil sample is forced into the tube by raising the gas pressure within the cell.

The cell of either Figure 3 or 6 is designed to permit electrical measurements to be made on the electrical cells with the system under a vacuum before or after the oil is degassed into the deteri­

oration cell. Fol­

lowing d e g a s s in g into the system, the oil may be brought to the level of the outlet tube from tubes 9 and 10 con­

t a i n in g t h e elec­

t r i c a l c e l l s , b y operation of the pump. After elec­

t r i c a l m e a s u r e ­ ments are made the system is brought u p t o 7 6 0 - m m . pressure with the g a s u s e d . C o n ­ necting tube 15 in Figure 3 equalizes the pressure above the oil in tube 9 with that of _ the chamber containing the oil sample and thereby prevents the oil from filling tube 9 after gas is a d m i t t e d to th e system.

D e g a ssin g E q u ip m e n t A t th e start of a test, the oil is adm itted into the deterioration cell through th e de­

g a s s i n g e q u i p ­ m ent. T he pur­

pose of degassing

Fi g u r e 8 . De g a s s i n g Eq u i p m e n t a n d De t e r i o r a t i o n Ce l l

Fi g u r e 9 . De g a s s i n g Eq u i p m e n t a n d

El e c t r i c a l Me a s u r i n g Ce l l Ft g u r e 10. Au t o m a t i cOxy­

g e n Fe e d a n d Pr e s s u r e- Ma i n t a i n i n g Ap p a r a t u s

The component parts are: a 500-cc. water- jacketed buret for containing the oxygen or other gas, and using butyl phthalate as the displacement medium; a hydron bellows (containing butyl phthalate) shown in Figure 11 connected to the 500-cc. buret; a mercury manometer with two platinum contacts, one normally immersed in the mercury and the other making contact with the mercury at a system pressure of 760 mm.; and an auto­

matic displacement mechanism shown in part in Figure 11 for controlling the volu­

metric displacement of the system to main­

tain a pressure of 760 mm. in the deterio­

ration cell.

The operation of the system is as follows:

When the system pressure decreases below 760 mm., a circuit is made between the two contacts in the manometer. Closing of this circuit in conjunction with a vacuum tube control circuit and relay energizes the sole­

noid shown in Figure 11. This solenoid when energized draws a wheel (with en­

gaging pin) which is mounted on a steel tube and is normally held in a disengaged position by a spring, into contact with the star wheel shown in Figure 11. The w'heel and tube operate on a continuously rotating shaft at slow' speed and are driven from the shaft through a clutch. The star wheel

is (a) to rem ove dissolved gas and other volatile products in the oil sam ple so as to standardize initial conditions, (6) to filter the sam ple to rem ove any foreign particles, and (c) to permit a low pressure to be maintained in the de­

terioration cell during the admission of the oil, thereby thor­

oughly im pregnating the paper in the cell.

The degassing equipm ent is shown schem atically in Figure 7 and assembled in position for degassing an oil sample into a deterioration cell in Figure 8.

The principal parts of this equipment are: a sampling flask, 1, with male and female ground joints, and a stopcock for controll­

ing the rate at which the oil is admitted to the system at a pres­

sure of approximately 50 microns; a sintered-glass disk, 2, mounted between a male and female ground joint for filtering the oil; an assembly for placing the oil in the form of a thin film and for heating this oil film to approximately 95° C. This assembly consists of nozzles, 7, for spraying the oil onto the interior surface of tube 8, and a jacket formed by tube 5 which permits tube 8 to be heated by steam applied through inlet 4 and drained out at 6. The connection of vacuum pump is made through outlet 3, this arrangement preventing the pump from being fouled by oil.

The oil sample is not heated before admission of the oil to a reduced pressure, and the method of heating the oil a t re­

duced pressure prevents heating in excess of 100° C.

T he degassing equipm ent is also shown in Figure 9 in posi­

tion for degassing an oil directly into an electric measuring cell (of the typ e previously described) for electrical measure­

m ents under vacuum . T his procedure m ay be used for m ak­

ing precise electrical m easurements on th e oil sam ple under carefully controlled conditions.

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

A u to m a tic G as F ee d a n d P res­

s u r e -M a in ta in in g A p p a ra tu s The m aintenance of uniform conditions during the oxidation and th e accurate determ ination of electrical and chemical data have required the use of an auto­

m atic system for feeding gas (oxygen or nitrogen) to the deterioration cell as re­

action w ith the oil occurs. T his system is shown in assembled form in Figure 10.

Fi g u r e 1 1 . Me c h a n i s mwi t h Hy d r o n Be l l o w s f o r Vo l u m e t r i c Di s p l a c e m e n t

August 15, 1941 A N A L Y T I C A L E D I T I O N 519 is mounted on a threaded shaft which when rotated changes the

displacement of the hydron bellows and accordingly the volume of butyl phthalate in the buret.

The control circuit is designed to give a tim e delay to pre­

vent “ chattering” of the mechanism due to system pressure changes produced b y the solenoid pum p. One notch on the star wheel corresponds to a change in the volum etric displace­

ment in the system of 0.2 cc. The system is provided with manual control of the buret volum e by the crank shown in Figures 10 and 11, and provides outlets and controls for oven heating units, a thermoregulator, cooling w ater for the coils, and control for the solenoid operating the pump. The sys­

tem as designed thus permits constant pressure conditions to be maintained in the deterioration system , and the rate at which oxygen is consumed and total absorption as a function of tim e to be determined from buret readings.

D isc u ssio n

The apparatus described has been used for studying m in­

eral oil deterioration under a variety of conditions, such as continuous oxidation a t 760-mm. pressure, and lim ited oxida­

tion w ith only a definite am ount of oxygen adm itted to the system, the system pressure being m aintained w ith nitrogen (2). T he equipm ent described does not include provision for removal of the volatile oxidation products, although this may be effectively accomplished b y connecting an absorption

train in tube 6 (Figure 3), thereby pumping the gas continu­

ously through the absorption train. An electrical measuring cell, including an absorbent paper, m ay be placed in the gas line, tube 6, thereby permitting electrical m easurements of the volatile products. Experience has indicated th at the electrical measurements are of value not on ly for the specific application of mineral oils for electrical use but also for funda­

mental information concerning the m echanism of the deteri­

oration.

Acknowledgment i

The apparatus described in this paper has been developed in a program of research on mineral oil deterioration which until September 1, 1939, was carried on under the sponsorship of the U tilities Coordinated Research, Inc., A ssociation of Edison Illuminating Companies. Since th a t date it has been carried on in cooperation w ith a com m ittee on insulating oils and cable saturants, Herman Halperin, chairman, represent­

ing the sponsors, T he Engineering Foundation, and the Ameri­

can Institute of Electrical Engineers. Funds for this work are being contributed by a group of electric power companies, a group of oil companies, and a group of electrical m anufac­

turing companies in addition to the sponsors.

L ite r a tu r e C ited

(1) Balsbaugh and Howell. Rev. Sci. Instruments, 10, 194 (1939).

(2) Balsbaugh, Howell, and A ssaf, In d. En o. Ch e m., 32, 1497 (1940).

A N ew L aboratory F raction atin g C olum n H ead

T ZE N G -JIU E Q SU EN , T h e T u n g Li Oil W orks, C h u n g k in g , C hina

I

la r g e n u m b e r o f types of columns and heads in use. How­

ever, m ost of them are either very elabo­

rate to construct or v e r y e x p e n s i v e to purchase.

The partial conden­

sation type head of the well-known Peters column (5) is probably the simplest form with which the reflux ratio can be varied at will, b u t w i t h i t t h e amount of reflux can­

not be readily ascer­

tained. The column of Cooper and Fasce (1) possesses the ad­

v a n t a g e t h a t t h e amount of reflux can be d e te r m in e d by counting the number of liquid drops going back to the column.

Its drawback is that, as the area of the c o o lin g s u r f a c e of

the partial condenser is fixed, the reflux ratio can be varied only by varying the rate of flow of the cooling medium.

With liquids boiling above 100° C. the performance was found by the present author to be unsatisfactory. Furthermore, the thermometer reading of their column tends to be low at slow rate of distillation. The head designed by Simons (6) has proved very successful (5), but its construction is rather elabo­

rate.

A relatively simple column head has recently been built by the author and is shown in Figure 1. Its performance was found very satisfactory in actual use.

It is a combination of the type of Peters and Baker and of Cooper and Fasce. The level of the cooling water in the partial condenser, C, can be adjusted by raising or lowering the outlet tube, O, which is not in the same plane with the thermometer pocket, P. The reflux ratio can be estimated by counting the liquid drops at both tips A and T. It must be remembered that the drops at the two tips may not be of the same size and their relative value, if wanted, must be calibrated. The ground joint, J, enables the head to be used with different columns.

L ite r a tu r e C ited

(1) Cooper, C . M.. and Fa3Ce, E. V., Ind. E n o . C h e m . , 20, 420 (1928).

(2) D unstan, A. E., et a I., editors, ‘‘Science of Petroleum ", Vol. II, p. 1629, London, Oxford University Press, 1938.

(3) Goldwasser, S., and Taylor, H. S., J . A m . Chem. Soc., 61, 1751 (1939).

(4) M orton, A. A.. ‘‘L aboratory Technique in Organic C hem istry” , Chap. IV, New York, M cGraw-Hill Book Co., 1938.

(5) Peters, W. A., and Baker, T., I n d . E n o . C h e m . , 18, 69 (1926).

(6) Simons, J. H „ Ibid., Anal. E d., 10, 29 (1938).

(7) W ard. C. C., U. S. Bur. Mines, Tech. Paper 600 (1940).

Spectrochem ical A nalysis o f Trace Elem ents in Fertilizers

B o r o n , M a n g a n e s e , a n d C o p p e r

E UG EN E H. M ELV IN 1 A N D R OBERT T . O’CONNOR1

B u reau o f P la n t In d u str y , U . S. D ep a r tm e n t o f A gricu ltu re, W a sh in g to n , D. C.

AS R ESE A R C H on the nutrition of plants and anim als continues, the im portance of the presence or absence in their food of th e m erest traces of certain elem ents has been more and more emphasized. Thus, for exam ple, it has been shown th at the presence of a few parts per m illion of boron in th e soil w ill prevent the internal cork of apples or th e heart and dry rot of sugar beets, bu t one-half part per million in ir­

rigation w ater w as sufficient to damage some citrus crops in California; application of extrem ely sm all quantities of m an­

ganese w ill cure chlorosis of tom atoes or Pahala blight of sugar cane; w hile copper in only one-sixteenth to one-eighth part per million w ill prevent the permanent w ilt of tobacco, am ounts much in excess result in a stunting of plant growth.

M cM urtrey and Robinson (4) have compiled “A Reference L ist of the Secondary E lem ents and Their R elation to Plant D evelopm ent” , in w hich th ey summarize the known effect of tliirty elem ents on the growth of plant crops. D aniel (1) has sim ilarly summarized the role of thirty-three trace elem ents in animal nutrition.

W ith th e im portance of these secondary elem ents in the growth of plants and nutrition of animals established, knowl­

edge as to their presence and concentration in available mixed fertilizers, where th ey are possible im portant sources, seems desirable. Fertilizer companies customarily guarantee only definite percentages of the primary plant nutrients, nitrogen (Tv), phosphoric acid ( P 2 O 5 ) , and potash (lv>0). The total content of these plant nutrients in th e average m ixed fertilizer now am ounts to about 19 per cent. T he question of w hat constitutes the remaining 81 per cent w as answered in this laboratory b y Lundstrom and M ehring (,?) who determined the complete composition of 44 mixed fertilizers chosen on a

1 P r e s e n t a d d r e s s , N o r th e r n R e g io n a l L a b o r a to r y , B u r e a u o f A g r ic u ltu r a l C h e m is tr y a n d E n g in e e rin g , U . S. D e p a r tm e n t o f A g r ic u ltu r e , P e o r ia , 111.

* P r e s e n t a d d re s s , S o u th e r n R e g io n a l R e s e a rc h L a b o r a to r y , N e w O rle a n s , L a .

basis of relative consum ption of each grade. The chemical m ethods therein involved for the determ ination of im portant secondary elem ents, w hose concentrations range from only 0.0005 to 0.1 per cent, are both com plicated and tim e-con­

suming.

I t is to this typ e of problem th at spectrochem ical analysis is particularly adapted. T he spectrograph has th e advan­

tages of being direct, thereby avoiding error due to chemical m anipulations involved in separations of sm all quantities; of being rapid; and of achieving, w hen concentrations are par­

ticularly low, accuracy comparable to chemical m ethods.

Accordingly, a study of the application of spectrochemical m ethods to the analysis of m ixed fertilizers has been m ade (5) and a procedure devised w hich w ill perm it the sim ultaneous determ ination of three im portant secondary elem ents, boron, manganese, and copper. T his paper describe^ the applica­

tion of this m ethod to the spectrochem ical analysis of the 44 representative mixed fertilizer sam ples collected and analyzed b y Lundstrom and M ehring and compares the results and the tim e required w ith the chemical m ethods.

A p p a ra tu s a n d M e th o d

G e n e r a l M e t h o d o f P r o c e d u r e . A s the concentrations of the secondary elem ents in the mixed fertilizer samples varied over appreciable ranges, th e step-sector m ethod of Scheibe (7, S) w as selected. A H ilger seven-step sector with a step ratio of 2 w as used when photographing each sample, thus perm itting plate calibration and w ide selection of the in­

tensity best suited for the photom etric measurem ent of any line. W hile th is procedure lim its to seven th e number of sam ples w hich can be photographed on a single plate, it pre­

v en ts any possibility of a selected line in the spectrum of any sam ple being too light or too dark to perm it an intensity measurement w hich will fall w ithin the straight-line portion

K

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Fi g u r e 1 . Sp e c t r o g r a m s o p Mi x e d Fe r t i l i z e r Sa m p l e s