INDUSTRIAL a n d ENGINEERING CHEMISTRY
A N A L Y T I C A L E D I T I O N
i S S É i É l i i
W A L T E R J . M U R P H Y , E D I T O R O IS SU E D O C T O B E R 18, 1943 VOL. 15, NO. 10 CONSECUTIVE NO. 20 Editorial Assistant: G . Gl a d y s Go r d o n Manuscript Assistant: St e l l a An d e r s o n Make-up Assistant: Ch a r l o t t e C . Sa y r e
ZSiSttF* B . L . Cl a r k e
T. R. Cu n n i n g h a m
Advisory Board G. E. F. Lt j n d e l l M . G. Me l l o n
R. H. Mü l l e r
H. H. Wi l l a r d
Analysis by Infrared S p e c tr o s c o p y ...
J. Rud Nielsen and Don C. Smith 609
D eterm ination of pH of Textile M a te r ia ls ...
Helmut R. R. Wakeham and Evald L. Skau 616
Photom etric E stim ation of Silicon in M agnesium and M agnesium A llo y s ...
A. J. Boyle and V. V. Hughey 618
Colorimetric D eterm ination of Fluoride in N atural Waters w ith T h orium and A lizarin . N. A. Talvitie 620
Modified Basic Succinate E stim ation of A lu m in u m in M agnesium Alloys . A. J. Boyle and D. F. Musser 621
Iodom etric E stim ation of Zinc in M agnesium Alloys Clyde C. Casto and Albert J. Boyle 623
D eterm ination of T in w ith Mercuric Chloride . . . J. G. Fairchild 625
D eterm ination of S m all A m ounts of Arsenic, A n ti
m ony, and T in in Lead and Lead A llo y s...
C. L. Luke 626
Fixing and D eterm ining O il in Feed W ater and Boiler W ater . . . . C. A. Noll and W. J. Tomlinson 629
D eterm ination of Potash in Fertilizers or Base Goods in Absence of A m m o n iu m Salts and Organic M a t t e r ...Philip McG. Shuey 633
Fluorom etric D eterm ination of Riboflavin in Pork Products . W. J. Peterson, D. E. Brady, and A. O. Shaw 634
Improved Pressure-Regulating Device . B. R. Warner 637
Modified Hershberg M elting-Point Apparatus . . . Morris M. Graff 638
Hydrogen Electrode Half-Cell in Polarography . . . J. Percy Baumberger and Kathleen Bardwell 639
A utom atic Pressure-Regulating M anom eter . . . Roger Gilmont and Donald F. Othmer 641
Apparatus for Photoelectric T i t r a t i o n s ...
Robert H. Osborn, John H. Elliott, and Arthur F. Martin 642
Improved A utom atic Gas E ffu s io m e te r ...
Leonard C. Drake 647
M IC R O C H E M IS T R Y
D eterm ination of Boiling Points of Pure Organic L i q u i d s ... Celso R. Garcia 648
D ithizone M ethod for R apid D eterm ination of Copper . . . G. H. Bendix and Doris Grabenstetter 649
D eterm ination of Tungsten in Low-Grade T ung
sten Ores . . . . F. S. Grimaldi and Victor North 652
Microbiological D eterm ination of Pantothenic Acid A. L. Neal and F. M. Strong 654
Glass Standards for Fluorom etric D eterm inations Erich Loewenstein 658
The Am erican Chemical Society assumes no responsibility for the statements and opinions advanced by contributors to its publications.
28,400 copies of this issue printed. C opyright 1943 by American Chemical Society.
Published by the Am erican C hem ical Society a t Easton, Penna. E d i
torial Office: 1155 16th Street, N . W .t W ashington 6, D . C .; telephone, Republic 5301: cable, Jiechem (W ashington). Business Office: American Chem ical Society, 1155 16th Street, N . W ., W ashington 6, D . C . Advertis
ing Office: 332 W est 42nd Street, New Y o rk 18, N . Y .; telephone, B ryan t
‘J-4430.
Entered as second-class m atter a t the Post Office a t E aston, Penna., under the Act of M arch 3, 1879, as 24 times a year— Ind u strial E d itio n m onthly on the 1st, A nalytical E d itio n m onthly on the 15th. Acceptance for m ailing at special rate of postage provided for in Section 1103, A ct of October 3, 1917, authorized J u ly 13, 1918.
Rem ittances and orders for subscriptions and for single copies, notices of changes of address and new professional connections, and claims for missing num bers should be sent to the Am erican Chem ical Society, 1155 16th Street, X . W ., W ashington 6, D . C. Changes of address for the Industrial E d itio n
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A n nual subscription— Ind u strial E d itio n and Analytical E d itio n sold only as a u n it, members S3.00, nonmembers S4.00. Postage to countries not in the Pan-American U nion S2.25: C anad ian postage $0.75. Single copies—
current issues. Industrial E d itio n S0.75, Analytical E d itio n S0.50; back numbers, Industrial E d itio n SO.80, Analytical E d itio n prices on request;
special rates to members. _ .
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News, Chemical Abstracts, and Jo u rn a l o/ the American Chemical Society.
Rates on request.
Scientist maesuring p H in high-temperature, high-hum idity atmosphere of a greenhouse a t O hio State University.
the measurement of oxidation-reduc-|
tion potentials as in titrating; it is I read directly in volts in such work, f The present model has a limit ofl error of adjustment of ±0.0037 volt;
f
or ±0.05 pH , exclusive of any error in the stated pH of buffer solution, and its reproduceability of reading is | 0.02 pH. I t can use samples as small as 2 ml in volume. At $240.00 it is an outstanding value for accuracy, ver
satility and high-grade construction.
The instrument below is our Glass- Electrode pH Indicator, specialized for use with this measuring electrode and a calomel reference electrode.
Both are sealed at the factory and re
quire only an occasional external cleaning. This cleaning, together with an equally occasional filling of the salt-bridge and replacement of dry cells, constitute the Indicator’s maintenance needs.
There are two ranges: 0-8 pH and 6-14 pH ; the 2 pH overlap is espe
cially convenient for titrations. The limit of error of adjustment is ±0.1 pH, exclusive of course of error in stated pH of buffer solution. At
§160.00 it is widely used because of its. simplicity, speed, convenience and dependability.
pH Checked Reliably In Hot, Humid Labs
Here are two pH Indicators de
signed especially for easy, trouble- free, accurate use even when relative humidity is as high as 95, with ambient temperature at 30 C. The two instruments differ only in their versatility and accuracy of adjust
ment; both are built to the same high standard of dependability.
The instrument shown in use is our Universal pH Indicator. In the ap
plication illustrated, it is being em
ployed with its own self-contained glass measuring electrode, supplied with the Indicator. The instrument can, however, be used with quin- hydrone, hydrogen or any other Nernst-equation measuring electrode supplied by the user, and is direct- reading in pH with any of them.
The Indicator is thus especially use
ful when comparing the results of different electrodes on the same solu
tion, or in any other condition where an all-around instrument is desired.
Other features adapt this Indicator to
Jr l Ad E-96R-4GO(2a)
Direct-reading deflection m eter has two scales, 0 to 8 and 6 to 14 pH . . . w ith 2-pH overlap, especially con-*
venient for titratio ns.
In one setting for each, operator corrects for electrical zero of am plifier and for asym m etry.
Electrode co m p artm e nt contains buffer solution, and test tubes for carry
ing electrodes.
R a n g e - c h a n g in g switch has three positions'. “ OFF,11
“ 6-14,” "8-0.”
15-inch le a d s p e r m it e le c tro d e s to be used outside the case.
Standard 50-ml beaker Is self
alig ning; held firm ly In place by m etal clips.
T herm om eter f a c i I I t a t e s s e t t i n g o f t e m p e r a tu r e co m p e nsator.
S m a l l , ru g g e d , sealed glass e le c tro d e a n d fa c to r y - fille d reference electrode, both of high stab ility . . . self-aligning to prevent breakage.
L E E D S
&.
N O RTH R U P C O M P A N Y , 4920 STEN T O N AVE., PH I LA., PA.M E A S U R IN G IN S T R U M E N T S < T E L E M E T E R S • A U T O M A T IC C O N T R O L S • H E A T - T R E A T IN G F U R N A C E S
Reputation for Reliability
Q^Ylalcers o f c f i n e (fyanlrifnges f o r ^''¡/l lorc th a n ClJ'orhj Q/ e<
I NT E R N A T I O N AL E Q U I P M E N T COMPANY
B O S T O N , M A S S A C H U S E T T S
turers are saddled with heavy responsibility.
On them falls the meticulous job of processing for use in our armed forces. Because of Reputa
tion for Reliability, they have selected Interna
tional’s Capacity Centrifuges to do this important work. Laboratories throughout the nation keep large batteries of these machines in twenty-four- hour continuous operation, making available huge supplies of life-saving blood plas
ma for shipment to our fighting men in all parts of the world. When you buy International you buy International’s Reputation for Reliability.
Olson is one of International's Master Machin
ists. He is turning a special housing which will soon be assembled into the large serum centrifuge. In action — five hundred pounds of accurately machined and balanced rotating parts will swing ten pints of blood at a speed of 2300 revolutions per minute. This delicate operation requires Olson’s brand
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I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 15, No. 10
S T E D M A N P A C K E D COLUM N S
Enlargement of packing only, show
ing’mesh and shape of conical discs.
Type " A " Type **B" Type " O '
The conical type of Stedman Packing is fabricated from 60 x 40 mesh, 0.009-inch diameter wire, 18-8, type 304 stainless steel wire cloth. All connections between the many wire cloth parts are spot welded for strength and to keep the parts in proper relation to each other. A three- section unit of Stedman Packing is shown at the lower part of this page.
The Stedman Packing is inserted in a special Pyrex glass column having a constant inside diameter. This column is fabricated by shrinking a Pyrex tube on a mandrel resulting in a constant bore tube with tolerances of better than 0.001 inch in diameter.
Stedman Packing is not sold separately from the special glass columns, as the efficiency of the packing depends on a proper fit with the column.
The Stedman Packing is furnished in three types of columns. Type
“A " is a plain Pyrex glass constant bore tube with indentations at the lower end to support the packing. This arrangement is convenient for adding some type of insulation or heated jacket of your own design to prevent excessive heat losses. When a plain column of type "A " is heated externally, care must be taken not to overheat the column as this will cause drying of the packing at the column wall and hence loss of packing efficiency. The type "A ” columns are fitted with suitable
"Inter-Ioint" connections— f 24/40 for the J^-inch size, f 29/26 for the Ji-inch and 25-mm. sizes, f 45/50 for the 37-mm. and f 55/50 for the 50-mm. size.
The Type "B" column is identical to the Type "A " but with the addi
tion of a silvered vacuum jacket surrounding the packed section. This type of column is limited in its application by heat losses and is not recommended for materials boiling over 250° F. at atmospheric pressure.
When operating under vacuum, the temperatures should be still lower depending on the vacuum used.
The Type “C " column is a Type "B" column over which an electric heating coil has been wound. This heater is proportioned to maintain uniform temperatures within the column by counteracting heat losses, the heater is then covered with a heavy insulated blanket and finally enclosed in a neat chromium-plated metal jacket. This type of column is suitable for use at temperatures up to approximately 750 °F. A calibration chart is furnished with this type of column for determining the proper input voltage for the heated jacket to establish substantially adiabatic conditions.
Packed Length Inches öi *
S i P ric e s
S Bft 3
“ I
" A "
P la in C o lu m n
" B "
V a c u u m J a c k e te d
" C "
H e a te d J a c k e t Size 105 Stedman Columns 0.387 In. (9.5 Mm.) Diam.
12 J-1061-1 52.00 58.00 86.00
18 J-1061-2 78.00 85.00 125.00
24 1-1061-3 103.00 111.00 167.00
36 J-1061-4 153.00 163.00 247.00
48 J-1061-5 203.00 215.00 325.00
60 J-1061-6 253.00 • • • • • • • •
72 J-1061-7 303.00
--- ---
Size 104 Stedman Columns 0.762 In. (19.0 Mm.) Diam.
12 2418 36 48 60 72
J-1062-1 J-1062-2 J-1062-3 J-1062-4 J-1062-5 J-1062-6 J-1062-7
37.00 55.50 73.00 108.00 143.00 178.00 213.00
46.00 64.00 84.00 121.00 158.00
74.00 104.50 140.00 205.00 268.00
Size 112 Stedman Columns 0.992 In. (25 Mm.) Diam.
12 J-1063-1 33.00 42.00 72.00
18 J-1063-2 49.50 58.50 98.50
24 J-1063-3 65.00 76.00 132.00
36 J-1063-4 96.00 109.00 193.00
48 J-1063-5 127.00 142.00 252.00
60 J-1063-6 158.00
.... ....
72 J-1063-7 189.00 . . . .
---
Size 134 Stedman Columns 1.445 In. (37 Mm.) Diam.
12 J-1064-1 36.00 46.80 79.50
18 J-1064-2 50.75 62.75 110.25
24 J-1064-3 65.55 80.00 142.50
36 J-1064-4 95.00 112.50 204.00
48 J-1064-5 124.20 147.00 267.50
60 J-1064-6 154.20
....
• • • •72 J-1064-7 184.20
--- ----
Size 135 Stedman Columns 1.968 In. (50 Mm.) Diam.
12 J-1065-1 37.50 52.50 85.50
18 J-1065-2 53.50 69.25 117.00
24 J-1065-3 67.50 87.50 150.00
36 J-1065-4 98.00 121.00 213.50
48 J-1065-5 130.00 156.50 277.00
60 J-1065-6 158.50
72 J-1065-7 190.00
--- ---
CONICAL TYPE STEDMAN PACKING CHARACTERISTICS
Packing No. 105 104 112 134 135
Nominal diam. (mm.) 9.5 19 25 37 50
Flood Point capacity
(cc. hr.) 230 637 1080 2480 6500
Flood Point H.E.T.P.
(in.) 0.64 0.86 0.99 1.4 2.0
% Flood Point
H.E.T.P. (in.) 0.45 0.70 0.87 1.8 1.9 Vl Flood Point
'H.E.T.P. (in.) 0.50 0.58 0.76 2.0 3.0 M Flood Point
H.E.T.P. (in.) 0.48 0.61 1.2 1.8
October 15, 1943 A N A L Y T I C A L E D I T I O N 7
R A T O R ! E S ' ♦ H A R R Y V C D l f l l f f O 3 9 3 3 0 R O SELA W N A V E ., DETROIT,
spa ggsa
ÿiii
I P M E N T
S P E C T R O G R A P H I C E Q U I P M E N T G I V E S Q U I C K AND A C C U R A T E A N A L Y S I S
A spectrographic laboratory completely equipped with ARL-DIETERT Spectrographic equipment yields the maximum in efficient and accurate spectro-chemical analysis. M od
ernize and supplement your present spectro
graph laboratory with ARL-DIETERT equip
ment.
Proper source units in particular, producing the electrical discharge to the samples to be analyzed, w ill increase the speed and accuracy of your present laboratory.
ARL-DIETERT supplies a complete line of spectrographic equipment of the most modern type, including source units, grating spectro
graph, projection comparator^densitometer, developing equipment, calculator— plus vari
ous accessories. Write for Modern Analysis Catalogue, 128.
FO U R M O D E R N SOURCE U N IT S The new Multisource U nit is the ideal instrument for research and control analysis.
This new unit combines the sensitivity of the arc with the accuracy of the spark. Thus, it materially improves the accuracy and widens the range of spectrometric analysis of all materials.
The H ig h Voltage Spark U nit as illustrated, is particularly suited to the analysis of aluminum, steel, magnesium, bronze, zinc, and lead. This unit is rapidly becoming the accepted standard of the whole metal industry.
The D. C. Arc Rectifier U nit is particularly suited for general analytical work, including analysis of metals, minerals, salts, paints, glasses, fertilizer, ores, cements, etc.
The A. C. Arc U nit is excellent for the analysis of m inor constituents in metals and salts.
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 Vol. 15, No. 10
ELE C T RI C HEAT T R E A T IN G F U R N A C E S • • H E A T I N G ELE MENT A l l O Y S • • T H E R M O C O U P L E A N D LEAD WIRE • . PYROMETERS . « W E L D IN G WI RE • . HEAT RESISTANT CASTINGS • . EN AM E L IN G FIXTURES • » SPARK PLUG ELECTRODE WIRE • • SPECIAL ALLOYS O F NICKEL • • PROTECTION TUBES
• The h e a tin g unit of th is
C o m b u s tio n F u rn a ce is h e a v y — it’s 7 g a u g e C h ro m e l- A . H ence, it w ili sta n d a lot o f h a rd g o in g . T h is extrem e b ility con stitutes o n e facto r in e c o n o m y o f m ain te n a n ce . A n o t h e r e c o n o m y feature lie s in the fact that the h e a tin g un it c o n sis ts m e re ly o f the w ire itself.
There is n o refractory m o u n tin g . The c o m b u s t i o n t u b e p a s s e s d i r e c t l y th ro u g h the h e lical coil w h ic h is su r
ro u n d e d b y h igh -te m p e ra tu re i n s u la tion. . . . The fu rn a c e s h o w n here is a re la tiv e ly n e w m odel. D u e to its in c re a se d in su la tio n , it h e a ts up in o n e - third le s s tim e, u s e s 1 8 % le s s p o w e r, a n d h a s a c a se te m p erature 120 ° F.
c o o le r (at 2 0 0 0 ° F.) th a n before. The fu rn a c e o p e ra te s o n A .C . th ro u g h a sm a ll transform er,^ w ith te m perature control th ro u g h a rheostat. F o r m o re in fo rm a tio n o n th is F H - 3 0 3 - A , o f m in im u m m a in te n a n c e , w rite to y o u r d e a le r o r to us. . . . H o s k in s M a n u f a c tu rin g C o m p a n y , Detroit, M ic h ig a n .
H O S K I N S P R O D U C T S
October 15, 1943 A N A L Y T I C A L E D I T I O N 9
just part of a day's work for laboratory technicians in refin
eries to boil gasoline over a bunsen burner. As one said
— "W e used to tackle this with a notebook in one hand and a fire extinguisher in the other. But with Pyrex brand flasks we get more determinations than we believed possible without breakage and that has led to important developments in gaso
lines and oils.”
Because Corning discovered, back in 1908, how to make a glass that w o n 't b re a k over flam e, America's fighting forces are get
ting improved gasoline with more
"Y o u H a v e D o n e a G ood Job o f S e n d in g G la s s to W a r"
mileage and higher performance. America's airplanes are flying farther, faster and higher; our mechanized forces are more efficient; and industry, too, benefits from these better motor fuels.
Pyrex brand Engler Flasks fabricated from Chemical Glass No. 774, and Vycor brand Engler Flasks made from 9 6 % Silica Glass No. 790, are widely used in the A. S. T. M. Standard Method of Test in the distillation of Gasoline, Naphtha, Kerosene and other petroleum prod
ucts. The essential properties of mechanical strength, chemical stability and thermal resistance are combined in perfect balance for long-life and economy.
Whatever your laboratory glassware requirements may be, consult your regular laboratory supply dealer.
SEE OUR EXHIBIT, Space 204, at the 19th Exposition o f Chem ical Industries, M adison Square Garden, N ew York, Dec. 6 t o l l , 1943.
Ü
.P Y R E X
BRANDL A B O R A T O R Y W A R E
" P Y R E X ” an d " V Y C O R " are registered trade-m arks and indicate m anufacture b y
C O R N I N G G L A S S W O R K S • C O R N I N G , N E W Y O R K
C orning
—— in cans---
Research in Glass
Vol. 15, No.' 10
PRECISION CONTR HEAT IN
LABORAT
precisely any percentage of the total in p u t of the fu r nace. B uilt- in transformers cn the Com bustion Tube, Crucible and Box type Furnaces, provide the reduced voltage for the heavy heating elements.
A high resistance, compensated pyrometer indicates the temperature at w hich the furnace is being con
trolled and a m anu ally operated index pointer on the pyrometer can be set at the desired temperature, thereby m aking possible a visual check of the control setting as the furnace comes to heat.
R U G G E D C O N S T R U C T IO N
Lindberg Laboratory Furnaces are sturdily b u ilt of heavy sheet steel, backed by courses of high tem pera
ture insulating slab and refractory brick. Heavy, low voltage, heating elements perm it higher operating temperatures w ith longer life and fewer replacements as compared w ith ligh t gauge elements. The clean streamlined shape of the L indberg Laboratory F u r naces matches in appearance other m odern laboratory equipm ent and contributes to the high standard of
laboratory cleanliness. »
Phone or write your dealer today. H e will be glad to give you further information and prices.
Wi t h t h e i n t r o d u c t i o n of Lindberg Furnaces laboratory field, accurate regulation of temperatures is m ade available. Y o u can now select the desired temperatui'e required for carbon and sulphur deter
minations, special organic analyses, determ ination of the critical points of steel, fusions, ignitions, assaying, drying, and countless other laboratory operations where heat is employed.
S M O O T H , “ S T E P L E S S ” P O W E R IN P U T The L indberg In p u t Control, an adaptation of Lind- berg’s famous industrial furnace control, provides a m anual adjustm ent to operate the furnace at any de
sired temperature. This heat regulation is smooth and “stepless” in principle because it can be m ade in
W ell-known Throughout the World as the Leaders in D evel
oping and Manufacturing Industrial Heat Treating Equipment
L I N D B E R G E N G I N E E R I N G C O M P A N Y
Î 4 5 0 W E S T H U B B A R D S T R E E T , C H I C A G O 1 2 , I L L I N O I S
S O L D E X C L U S Q V E L Y T H R O U G H L A B O R A T O R Y E Q U I P M E N T D E A L E R S
CENTRAL SCIENTIFIC
TRr i l / XRK
S C I E N T I F I C I N S T R U M E N T S Q j ^ Q ) L A B O R ,
COMPANY
L A B O R A T O R Y A P P A R A T U S
N EW Y O R K T O R O N TO
CHICAGO
B O ST O N S A N FR A N CISCOOctober 15, 1943 A N A L Y T I C A L E D I T I O N
DEPENDABLE FOR SPEEDY HIGH VACUUM
S ccfu ijjica+it ty a c ti
•PUM PING SPEED
• MERIT FACTOR—40%
Ratio of pumping speed at 1 micron to free air displacement
•VACUUM GUARAN
TEED
0.1 micron or better
•T R O U B L E -F R E E VANES
Located in pump body assure long life and service
W h en you buy a high vacuum pum p you are seeking performance at reduced pressure and not great pum p
ing speed at atmospheric pressure. In other words, the speed of evacuation of the vacuum chamber at the re
quired pressure should be the determining factor. This is true whether the desired operating pressure is in the fractional micron range or whether the pressure is a matter of several microns, as for example the backing pressure of a diffusion pump.
In comparing the Megavac pum p with competitive pumps whose pressure limits are within the same range, the merit factor provides a quick, reliable means of comparison. The merit factor is defined as the ratio, in per cent, of the pum ping speed at 1 micron to the free air displacement of the pum p. As computed from the chart, the merit factor of Cenco-Megavac pum p is shown in the following table:
Si, ml/sec. D, ml/sec. F, %
Megavac (605 rpm) 375 940 40
No. 9201SA Cenco-Megavac P u m p with Yi h.p. motor to operate at 600 rpm on 115 or 230 volts, AC 60 cycles... $155.
THE CO NSTRUCTIO N OF
E L E C T R I C
l a b o r a t o r y
Refractories
| Checked under actual 1 workinp- conditions
If y o u are d e s ig n in g or constructing lab o ra to ry furnaces su itab le for relatively h igh temperatures, or se le ctin g refractory sh apes for use in such furnaces, our b o o k le t "T h e C on stru ctio n o f E le ctric Furnaces for the L a b o r a to r y ” w ill p rove helpfu l. Th e three standard ty p e s o f la b o ra to ry furnaces are fu lly d escrib e d . Fundam ental data are in c lu d e d on the e n e rg y source and the am oun t req uire d ; se le ctio n o f resistor wire/ sa m p le c a lcu la tio n s o f p o w e r requirem ents a n d resistor d e s ig n ; insulation, etc. A l l the furnace asse m b lie s d e scrib e d have b e en a c tu a lly b u ilt a n d tested under la b o ra to ry service co n d itio n s. This b o o k le t is free on request.
N O R T O N • C O M P A N Y • W o r c e s t e r 6/ Ma s s
e l e c t r i c
iv foHrmfnlni furnace
H
1
P I » t i l l^
F U S E DI N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 15, No. 10
October 15, 1943
Manufacture of Synthetic Organics, Pharmaceuticals, Resins, Varnishes, etc.
★ Now that B &A has made this material available in tonnage quantities, you may find that a calcium acetate of high purity has a useful application in your manu
facturing operations.
Call in your B &A technical serviceman for a conference on this as well as other Baker and Adamson fine chemicals.
In the laboratory, chem
ists rely on Baker and Adamson’s complete line of reagent chemi
cals. High quality, uni
formity, and accuracy —
“built-in” from the start.
I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 15, No. 10
UNIFORM as the M e t t l e o f the Iron J aws
In the last century there have been no fighting men with more sheer nerve than those of Michigan and Wisconsin who make up the 32nd — Iron Jaw — Division.
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October 15, 1943 A N A L Y T I C A L E D I T I O N 15
Students training for work as petroleum engineers con
ducting soil analysis tests to detect oil in the earth.
Kimble LaboratoryGlassware is extensively employed in the vital petroleum industry, both in War and in Peace.
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KIMBLE LABORATORY GLASSWARE a n a ly sis an d co n tro l. U sin g sta n d a rd w ill serve yo u w h erever y o u r p r e se n t ite m s w h ere p o ssib le m a y be im p o r - v ita l p r o d u ctio n d ep en d s o n research , ta n t in m in im iz in g d ela y s.
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16 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 15, No. 10
Optical Instruments for the Laboratory
Wartime achievements in research and process control owe much to the optical instruments which extend vision and provide a means of measuring optical characteristics.
The Spencer Colorimeter is designed for con
venience. The built-in illuminator and inclined eyepiece permit a comfortable position for the operator. Direct reading drums and separable cups speed up use.
The Stereoscopic Microscope extends human vision, retaining the natural position and move
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The Standard Laboratory Microscope with mechanical stage is easily equipped to provide the various types of illumination and magni
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October 15, 1943 A N A L Y T I C A L E D I T I O N 17
M E R C K & C O . , I n c . ^¿ a n u ^a cia n ln ,^. C& /em i6t6 R A H WAY, N. J.
Please send me the following charts: Name...a c s - io -43
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18 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 15, No. 10
A.H .T . C O . S P E C I F I C A T IO N
K O F L E R M I C R O H O T S T A G E
( M I C R O M E L T I N G P O IN T A P P A R A T U S ) For d e te rm in in g corrected m icro m e ltin g p oin ts on the
m icroscope stage w ith sam p le s as sm a ll as a sin gle crystal
K O F L E R M IC R O H O T STAGE (Micro Melting Point Apparatus), A.H.T. Co. Specification, electrically heated and with stage calibrated ther
mometers.
For determining corrected micro melting points by means of a microscope with samples as small as a single crystal, permitting con
tinuous observation of changes in the sample before, during and after melting. Useful also for general micro-preparative work, sublima
tions, measurements of refractive indices at elevated temperatures, fusions, heating under controlled conditions, etc., and physico
chemical studies. Sec Ludwig Kofler, Mikro- chcmie, Vol. X V (1934), P- ~4'2; and Kofler, Kofler and Mayrhbfer, “ Mikroskopischc Methodcn in der Mikrochemie" (Vienna, 1936).
For temperatures up to 350°C, with an ac
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The apparatus consists essentially of an in
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a condensing lens system. A threaded post takes either a fork for the micro slide or various sublimation blocks. A vertical rheostat, specially designed for use with this Hot Stage, permits exact reproduction of settings.
The thermometers have been calibrated on the individual Hot Stage with which they are to be used. A set of eight stable test reagents is included with each outfit. They are convenient, not only in acquainting the user with manipula
tion of the instrument, but also for the preparation of a calibration chart for the rheostat.
6886-A. M icro H ot Stage, Kofler, as above described, complete outfit as shown in Fig. 1, i.e., H o t Stage A w ith glass cover, tw o calibrated thermometers M , cooling block H , Fischer sublim ation blocks J a and Jb , glass baffle D , three su blim ation dishes K , Kofler- D ernbach v acuum su blim ation chamber E , fork lifter L, twenty-four micro slides P, set of test reagents T, and vertical rheostat R ; in case, w ith directions for use. For 115 volts, a.c. or d.c... $204.25 6887-A. D itto, H ot Stage A, only, w ith two calibrated thermometers M , cooling block H , glass baffle D and vertical rheostat R , b u t w ith o u t case or other accessories... ... $151.95
6886-A— Fig. 1. Complete Assembly
Fig. 2 Glass Baffle D in position on H o t Stage
Fig. 3
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Fig. 5
Ivofler-Dernbach V acuum C h a m ber in position on Fischer Block More detailed information sent upon request.
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»Analysis by In frare d Spectroscopy
A N ew M ethod A p plied to M ixtures o f N itroparaffins
J . RU D N IE L S E N A N » D ON C. S M IT H 1
University o f O klahom a Research In s titu te , N orm an, Okla.
A m e th o d o f analysis by infrared spectros
copy is described, w h ic h is applicable, i f Beer’s law h o ld s, a n d a set o f wave lengths can be fo u n d su c h th a t a t each wave le n g th only one c o m p o n e n t o f the m ix tu re has strong a b so rption w hile th e other c om po
nents have weak absorption. This m e th o d gives a h ig h degree o f accuracy w ith a m in i
m u m o f c o m p u ta tio n a l w ork. Its ap p lica tion to certain ternary m ixtures o f the four lowest n itro p araffins is described.
with a minimum of computational work. This method is applied here to certain ternary mixtures of the four lowest nitroparaffins, and it can be generalized so as to apply to mixtures of any num
ber of components.
Various experimental factors, which must be considered in ac
curate analytical work, are also discussed.
A pparatus
The infrared spectrograph used was practically identical with that described by Wright (.9). The 60° rock-salt prism had faces 10 by 8 cm. and the collimating parabolic mirror had a focal length of 91.4 cm. (36 inches). A water-cooled Nernst glower operating on a voltage-stabilized line served as the source of radiation. A Weyrich compensated vacuum thermocouple served as receiver. The primary galvanometer deflections were amplified by a balanced photovoltaic cell device. The pri-
R
ECENT improvements in apparatus and technique have made it feasible to apply infrared absorption spectra to the analysis of mixtures of chemical compounds (i, 3, 3, 9). In several industrial laboratories isomeric and other mixtures of compounds which are difficult to differentiate by other means are now analyzed in this manner.Infrared methods of quantitative analysis of binary mixtures are particularly simple and can be applied even when the mix
tures do not follow Beer’s law. Wright (9) has discussed several procedures suitable for industrial use.
When more components are present it may be possible to find for each compound a wave length at which that compound has strong absorption while all the other compounds have negligible absorption. When that is the case each component can be de
termined separately by the simple methods used for binary mix
tures (i). Unfortunately, this condition can seldom be realized with sufficient accuracy, and the general methods of analysis of multicomponent mixtures involve much time-consuming compu
tational labor.
In many cases, however, a set of wave lengths can be found such that at each wave length only one component of the mixture has strong absorption while the other components have weak absorption. In the present paper a simple and practical method of analysis is described which is applicable to such cases, pro
vided Beer’s law holds, and which gives a high degree of accuracy
1 Present address, N a v a l Research Laboratory, W ashington, D . C ,
Fi g u r e 1. Pa r t o f a Re c o r d o f t h e In f r a r e d Sp e c t r u m o f 2 - Ni t r o p r o p a n e
W ave length region, 12.45 to 10.06/x. Upper trace recorded w ith no cell in radiation path, lower traces w itn 0.06-ram. cell in p ath
609
610 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 15, No. 10
A n a ly tica l Procedure
A consideration of the boiling points suggested the following analytical problems as being of particular importance in the control of nitro- paraffin production:
(4) on nitromethane and nitroethane and the data of Wells and Wilson (8) for gaseous nitromethane, the first step in the present work was a careful investigation of the spectra of the four com
pounds in the liquid state. The materials, which had been puri
fied by fractionation in a long column, were kindly supplied by the Commercial Solvents Corporation.
Figure 1 shows a portion of a record obtained with liquid 2- nitropropane. The upper curve is obtained with no absorption cell in the light path. The vertical distance between this curve and a line drawn through the zero positions gives the omission intensity, 70, as a function of wave length. The lower curves are obtained with a cell of 0.07-mm. thickness filled with 2-nitro- propane placed in front of the entrance slit. From these curves and the corresponding zero lines the intensity of the transmitted radiation, 7, is determined. In Figure 2 the per cent transmission, 100 7//0, has been plotted against wave length. Since these curvcs are used here only for choosing the wave lengths most suitable for analysis, the per cent transmission has not been corrected for background radiation nor for losses due to the cell windows.
The following characteristic bands were chosen as the most favorable for analysis: nitro
methane 10.90/i, nitroethane 10.06m, 2-nitropropano II.74/a, 1-nitropropane 8.15m. A glance at the curves will show that at each of these wave lengths the compound indicated has intense ab
sorption, whereas none of the other compounds absorbs strongly. This choice allows the deter
mination of each compound in a mixture with any of the three others. For some mixtures a different choice would permit a more sensitive analysis, but would not lend itself so well to the extension of the work to four-component mix
tures. The most intense bands, those occurring around 6.5m, cannot be used here, since they are common to all nitroparaffins.
A. The determination of nitroethane and 2- nitropropane in nitromethane.
B. The determination of 2-nitropropane and nitromethane in nitroethane.
C. The determination of 1-nitropropane and nitroethane in 2-nitropropane.
D. The determination of 2-nitropropane in 1- nitropropane.
In each case a concentration range of the minor components from 0 to 7 per cent by volume was considered.
Bi n a r y M i x t u r e s. Problem D is typical of seven problems studied. Figure 3 shows a record obtained with known solutions of 2-nitropropane in 1-nitropropane, covering a small region around 11.74m where 2-nitropropane has a strong ab
sorption band. Experimental results of this kind furnish the basis for all methods of infrared spec
troscopic analysis, although these methods may differ considerably in the manner in which the experimental data are obtained or utilized. Com
mon to all of the methods for analysis of binary mixtures is the use of “working curves”— i. e., plots of the ratio (or the logarithm of the ratio) of two deflections (or differences between deflec
tions) against concentration.
mary galvanometer and the amplifier were mounted on a large Mueller support (6, 7) placed on a basement pillar. The second
ary galvanometer was mounted on a smaller Mueller support about 2.5 meters from the recording camera. The deflections could also be read on a scale.
The fixed-thickness absorption-cells and the precision variable
thickness cell used will be described elsewhere.
In fra re d A bsorptio n Spectra o f N itro m e th a n e , N itro e th a n e , 2-Nitropropane, a n d 1-Nitropropane
The four lowest nitroparaffins were selected for this work be
cause of their commercial and scientific importance (5). These compounds are all similar, two of them being isomers, and their boiling point range is rather narrow, necessitating lengthy frac
tionation for complete separation.
Since the only available data on the infrared absorption spectra of the nitroparaffins were the early measurements by Coblentz
WAVELENGTH IN MICRONS 100/--- —— —---
NITROMETHANE
Fi g u r e 2 . In f r a b e d Tr a n s m i s s i o n Cu r v e s f o r Fo u r Lo w e s t Ni t r o p a r a f f i n s
2-NITROPROPANE
w )80
- HNITROFROFANE
October 15, 1943 A N A L Y T I C A L E D I T I O N 611
Fi g u r e 3 . Sm a l l Pa r t o f a Re c o r d Sh o w i n g Ab s o r p t i o n a r o u n d 1 1 .7 4m o p Mi x t u r e s o p 2 - Ni t r o p r o p a n e i n
I - Ni t r o p r o p a n e (a) 0.00% , ((>) 2.00% , (d) 4.00% , (<i) 6.00% by volum e of 2-nitropropano in 1-nitro- propane. Cell thickness
0.071 m m .
The necessary data may be taken from a record such as Figure 3 or may be obtained by visual observation. The detailed procedure is largely a matter of experimental cir
c u m s t a n c e and preference.
Unless the detecting and re
cording devices of the spec
trograph are extremely stable, a single measurement cannot be trusted to be sufficiently accurate. Hence, the wave
length interval concerned must be scanned several times, or the instrument must be set on the correct wave length and several m e a s u r e m e n t s taken to obtain an average.
The number of readings re
quired is determined by the stability of the instrument and the accuracy desired. It is believed that in general the most accurate readings are ob
tained by setting the instru
ment on the correct wave length rather than by scanning, since in the latter procedure
the exact positions of the deflection zero may be doubtful except at the ends of the region scanned. With the instrument used in the present work the data obtained by averaging three or four deflections with the instrument at rest were found to be more accurate than readings obtained with comparable effort in other ways. This procedure was accordingly adopted. It was possible for different observers to check galvanometer deflections of 100 mm. to within 0.2 mm.
Working curves for two binary mixtures are shown in Figure 4 in which the extinction, log h / I , for a suitably chosen wave length is plotted against the concentration of the minor com
ponent. The extinction is preferred over other functions of the deflection ratio, since when the solutions obey Beer’s law a straight line is obtained which minimizes considerably the work required for determining and checking the working curve.
I t requires only about 5 minutes to fill the absorption cell and measure its extinction. On a routine basis the instrument can be set on the correct wave length and the straight-line working curve checked at two points in about 15 minutes, and the analy
ses then follow at the rate of about ten per hour. The working curve should be checked occasionally, since it may shift owing to changes in transmission of the absorption cell with deterioration of the rock-salt faces, accumulation of dirt, etc. For these and several other binary mixtures investigated the error of the analy
sis never exceeded 0.1 per cent of total sample. The smaller con
centrations could have been measured more accurately with a cell of greater thickness; the range of measurable concentrations could have been increased by using a thinner cell.
Te r n a r y Mi x t u r e s. The analysis of a mixture having two minor components is made in three steps: (1) the presence of one minor component is neglected, and the approximate concentra
tion of the other minor component is determined by the procedure for a binary mixture; (2) the approximate concentration of the neglected component is then determined in a similar manner;
and, finally, (3) the approximate concentrations of the two minor components are corrected for the error caused by the neglected component in each case.
r One first chooses a wave length, X', at which minor component 1 has strong absorption and the other two components have
small absorption. A working curve is made for a binary mix
ture of component 1 in the major component at this wave length, the extinction of the ternary mixture is measured, and the ap
proximate value Ci for the concentration of component 1 is deter
mined from this working curve. The more nearly equal the ab
sorption of component 2 and the major component are, the more nearly correct will c, be.
A wave length, X", is chosen at which component 2 has strong absorption and component 1 and the major component have weak absorption. A working curve for component 2 is made and the approximate concentration c2 of component 2 in the mixture is determined.
Finally, the corrected concentrations Ci and oi are determined by
- _ «3 ~ «o -
Ci = C i-- -,---, ci (1)
C2 = C j ---tt —, Ci
where «ô> «i> and are the extinction coefficients at the wave length, X', of the major component and of minor components 1 and 2, respectively; and ej, e', and ej are the extinction coeffi
cients at X". Equations 1 are derived in the next paragraph.
Ta b l e I. De t e r m i n a t i o n o f 2 - Ni t r o p r o p a n e a n d Ni t r o- e t i i a n e i n Ni t r o m e t h a n e
M ix ture
A-l
A-2
A-3
C2-NP CNE
% by volume
7.01 3.07
7.01 2.97
7.13 . 3.07
7.0 2 3.19
0.99 2.97
Av. 7.03 3.0 5
“ Correct’’ 7.00 3.00
5.03 5.10
4.96 5.07
5.25 4.93
5.20 5.01
4.99 4 .89
A v. 5.08 6.00
■•Correct" 5.00 5.00
2.96 6.99
3.06 7.09
3 22 7 03
2'.94 7! 12
2.92 6.87
Av 3.02 7.0 2
"C orrect’' 3.00 7 .00
A.
B .
Fi g u r e 4. Wo r k i n g Cu r v e s
For determ ination of 2-nitroparaffin in 1-nitroparaffin.
length 11.74/i. S lit 0.60 m m . Cell thickness 0.071 m m . F or determ ination of 1-nitroparaffin in 2-nitroparaffin.
length 8.15ji. S lit 0.25 m m . Cell thickness 0.071 m m . W ave W ave
612 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 15, No. 10 The small factors (ei — e<!)/(ei — c„) and (e" — <£)/(«£ —
need be determined only once. The former may be conveniently obtained by dividing the slope of the working curve, already made, for determining component 1 in the major component into the slope of a working curve, made with the same cell and at the same wave length, X', for determining component 2 in the major component. The other correction factor may be determined similarly.
Ta b l e I I . De t e r m i n a t i o n o f Ni t r o m e t h a n e a n d 2 - Ni t r o- PROPANE IN N lT R O E T H A N E
M ixture
B-l
B-2
B-3
C.VW C2 - ,V/J
% by volume
7.11 3 .0 0
7.15 3.23
7.15 3.23
7.09 3.11
6.98 3.18
Av. 7.1 0 3.15
“ Correct” 7.0 0 3.00
5.13 5.25
5.32 5.40
5.32 5.27
5.15 5.26
5.25 5.19
Av. 5.23 5.27
“ Correct” 5.00 5.00
2.98 7.21
3.25 7.20
3.26 7.20
2.93 6.91
s. 2.90 7.08
Av. 3 .00 7.12
"C o rre ct” 3 .00 7.00
In Tables I, II, and I I I are given the results of five entirely independent analyses of each of eight ternary mixtures. The symbols A-l, A-2, etc., designate the different mixtures. The symbols cmr, m b, C\ - u p , and c» - n pare used to designate the con
centrations of nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane, respectively.
Ta b l e II I . De t e r m i n a t i o n o f 1 - Ni t r o p r o p a n e a n d Ni t r o e t h a n e i n 2 - Ni t r o p r o p a n e
M ixture
C-l
C-2
% by volume
Av.
"C orrect’
Av.
■'Correct”
4.03 3.85 3.92 4.11 3.98 3.97 4 .0 0 1. 88 1.S9 1.89 2.01 1.94 1.92 2 . 0 0
2.01 1.81 2 . 1 2 2 . 1 2 1.90 2 . 0 1 2 . 0 0 3.95 3.98 3.88 3.S4 3.93 3.91 4.0 0
While 26 of the 80 measured concentrations deviate from the correct” values by 0.15 per cent by volume or more, only 9 of the observed concentrations deviate from the average by that amount. This indicates that some of the values listed as “cor
rect” are somewhat in error. If all SO measurements are con
sidered, and if the fact that they are not all measurements of the same quantity is neglected, an over-all standard deviation for a single measurement of 0.093 per cent by volume is obtained.
I he time required to determine the working curves was about 45 minutes, and each analysis took about 15 minutes. In routine
analysis the working curves w'ould need to be redetermined only occasionally, say, after sets of ten or twenty analyses.
Theoretical
Beer’s law states that the absorption of each component of a mixture is independent of the presence of the other components, or, more precisely, that the extinction suffered by a beam of monochromatic light on passing through a layer of the mixture is a linear function of the concentrations of the individual com
ponents.
Let Figure 5 represent an absorption cell filled with a liquid mixture. Let I 0 represent the intensity of the incident radia
tion, I'0 the intensity of the radiation transmitted by the front window. I ' the intensity of the radiation having passed through the liquid, and I the intensity of the radiation transmitted by the filled cell. If the liquid mixture obeys Beer’s law,
I ' = / ' X 10~C'oeo + «« + «i« + ... ) I (2) where I is the thickness of the liquid, Co, C\, c2, . . . are the concen
trations of the individual components of the mixture, and e&, ei, t2, . . ■. are their extinction coefficients. If the concentrations are expressed in moles per liter and I in centimeters, the i's are called molecular extinction coefficients. In this paper the con
centrations will be expressed in per cent by volume.
Fi g u r e 5 . Ab s o r p t i o n Ce l l ( Sc h e m a t i c) D efinition of It, l'a, I ' , and I
Substitution of the relations I'o = TJo I ' = i/t2 and
where Ti and 'L\ are the transmission factors for the front and back windows, into Equation 2 and taking logarithms gives
log (Io/D = (eoCo + dCt + e2c2 + . . . . ) I — log Ti — log'Tj or, with obvious abbreviations,
E = (eoCo + 61C1 + C2C2 + . . . . ) I + K (3) We shall call Equation 3 the “cell equation” . E is the extinc
tion for the given wave length used, and K is a positive quantity which will be called the “cell constant”, since it depends largely upon the nature and condition of the windows of the cell. K varies in a gradual manner with the wave length. The extinction coefficients, e0, ti, <2, ..., on the other hand, are rapidly varying functions of the wave length, which are different for different com-
