Industrial and Engineering Chemistry : analytical edition, Vol. 11, No. 12

IN D U S T R IA L

a n d E N C IA E E R M G

C H E M IS T R Y

Vol. 31, Consecutive N o. 47

Harrison E. Howe, Editor

ANALYTICAL EDITION

21,000 Copies of This Issue Printed

Issu ed D ecem ber 15, 1939

Vol. 11, No. 12

De t e r m i n a t i o n o p Io d i n ei n Th y r o i d a n d It s Pr e p a r a­

t i o n s b y Ce r a t e Ox i d i m e t r y...

...Wayne W. Hilty and Dale T. Wilson 037

PlIOTELOMETRIC S l'U D Y OP Le aD - DiTIIIZONE SYSTEM AT

610 M illim icrons Charles L. Guettel 639

Me t h o d f o r De t e r m i n i n g De g u e u n i n De r r i s a n d

Cu b e Lyle D. Goodhue and H. L. Haller 640

Qu a n t i t a t i v e Ab s o r p t i o n Sp e c t r o p h o t o m e t r y . . .

...J. S . Owens 643

An a l y s i so p Or g a n i c Ma t e r i a l sf o r Tr a c e so f Me t a l­

l i c Im p u r i t i e s... ...

. . . . T. M. Hess, J. S. Owens, and L. G. Reinhardt 646

De t e r m i n a t i o n o p Ma g n e s i u m i n Bi o l o g i c a l Ma t e­

r i a l s John P . Nielsen 649

Pa r t i t i o n o p Le s s Ea s i l y Di g e s t e d Ca r b o h y d r a t e

Co m p l e x o f Fo r a g e s...

Russell E. Davis and Charles O. Miller 651

Au t o m a t i c Ef f u s i o m e t e r f o r De t e r m i n a t i o n o f Sp e­

c i f i c Gr a v i t y o f Ga s e s . . . . George V . Feskov 653

Ca p i l l a r y Fl o w m e t e r w i t h Va r i a b l e Or i f i c e s . . .

Johannes H. Bruun 655

f

Me c h a n i c a l l y Op e r a t e d Co n t i n u o u s Li q u i d- Ex t r a c-

t i o n Ap p a r a t u s...

. . George W. Pucher and Hubert Bradford Vickery 656

Le a d- So d i u m Al l o y a s Dr y i n g Ag e n t . Harold Soroos 657

Sm a l l Ce n t r i f u g e Tu b e Fi l t e r...

... Theodore Perrine and William Kump 65S

Ra p i d Ci r c u l a t i n g Di a l y z e r ...

. . . A. R. Taylor, A. K. Parpart, and R. Ballentine 659

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

A c c u r a c y a n d P r e c i s i o n o f M i c r o a n a l y t i c a l D e - ( f & S

TERMINATION OF C A R B O N AND H Y D R O G E N ...

... Francis W. Power 660

Vo l u m e t r i c Es t i m a t i o n o f La c o n Gl a z e d Ca n d i e s

... Nicholas M . Molnar and Joseph Grumer 673

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

Ne w Ch e m i c a l En g i n e e r i n g Bu i l d i n g a t Ca s e

Sc h o o l o f Ap p l i e d Sc i e n c e...

E. A. Arnold and D. O. Hubbard 675

Au t h o r In d e x...678

Su b j e c t In d e x...682

T h e A m erican Chem ical Sooiety assumes no responsibility for the statem ents anil opinions advanced b y contributors to its publications.

P u b l i c a t i o n O f f i c e : E a s t o n , P c n n a . E d i t o r i a l O f f i c e : R o o m 7 0 6 , M i l l s B u i l d i n g , W a s h i n g t o n , D . C .

T e l e p h o n e : N a t i o n a l 0 8 4 8 . C a b l e : J i c c h e m ( W a s h i n g t o n )

P ublished b y the A m erican C hem ical Society, P u b lica tion Office, 20th &

N orth a m pton Sts., E aston, Penna. E ntered as second-class m atter at the P ost Office at E aston, Penna., under the A ct of M arch 3, 1879, as 48 times a year. Industrial E d itio n m onthly on the 1st; A n a ly tical E d ition m on th ly, on the lo t h ; N ews E d ition on the 10th and 20th. A ccepta n ce for m ailing at special rate o f postage provided for in S ection 1103, A c t o f O ctober 3, 1917, authorized July 13, 1918.

Ra t e sf o r Cu r r e n t Nu m b e r s: A nnual subscription rates: In d u s t r i a l a n d En g i n e e r i n g Ch e m i s t r ycom plete $6.00; (a) Industrial E d ition $3.00;

A d v e r t i s i n g D e p a r t m e n t : 332 W e s t 4 2 n d S t r e e t , N e w Y o r k , N . Y . T e l e p h o n e : B r y a n t 9 -4 4 3 0

(6) A nalytical E d ition $2.50; (c) News E d ition $1.50; (a) and (6) together

$5.00. F oreign postage to countries not in the Pan A m erican U nion, $2.40;

(a) $1.20; (6) $0.60; (c) $0.60. Canadian postage one third these rates.

Single copies: (a) S0.75; (6) 80.50; (c) 80.10. Special rates to m embers.

N o claims can be allow ed for copies o f journals lost in tho mails unless such claims are received w ithin six ty days of the date of issue, and no claims wall be allow ed for issues lost as a result o f insufficient notice of change of address. (T e n days a dvance notice required.) “ M issing from files"

cannot be a ccepted as the reason for hon oring a claim . Charles L Parsons Business M anager, M ills B uilding, W ashington, D . C., U S A

4 INDUSTRIAL AND ENGINEERING CHEMISTRY VOL. 11, NO. 12

v V v

¿v .0 ANALYTICAL REAGENTS

cS** for Special Analytical Methods

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

ACID PARA-H YD RO XY-PH EN YLARSO N IC A . R. — A specific precipitant for Titanium and Zirconium. Simpson 85 Chandlee, Jour. I. & E. Chem. Anal. Ed., Vol. 10, P. 642 (1938). (Reprint on request.)

A M M O N IU M SULFATE A . R. FOR B LO O D A N A L Y S IS — Folin & Farmer, Jour. Biol. Chem., Vol. 11, P. 493 (1912).

LEA D A C ET A T E BASIC A N H YD RO U S A . R. — For sugar analysis. W. D. Horne, Jour. Amer. Chem. Soc., Vol. 26, P. 186

(1904).

POTASSIUM PERSULFATE A . R. L O W N ITR O G EN —

Gasometric Micro-Kjeldahl determinations of Nitrogen. D. D. Van Slyke, Jour. Biol. Chem., Vol. 71, P. 235 (1927).

POTASSIUM PERSULFATE A . R. L O W CHLORIN E—

For Determinations of Halogens in Organic Compounds.

Thompson 85 Oakdale, Jour. Amer. Chem. Soc., Vol. 55, P. 1292 (1933).

SODIUM CO BA LTIC NITRITE A . R. TRUO G—

For Determinations of Potassium in Soils. E. Truog, Jour. Amer. Soc. Agron., Vol. 26, P. 537 (1934).

SODIUM TU N GSTATE A . R. FOLIN —

For Determinations of Uric Acid in blood. O. Folin, Jour. Biol. Chem., Vol. 106, P. 311 (1934).

2nd & M allinckro d t Sts.

ST. L O U IS , M O .

C H I C A G O P H I L A D E L P H I A

M O N T R E A L T O R O N T O

7 0 -7 4 G o ld St.

N E W Y O R K , N . Y .

DECEM BER 15, 1939 ANALYTICAL EDITION 5

STANDARD BURRELL GAS APPARATUS

A IVher ever Gases are Analyzed

B U R R E L L Apparatus is known

t h e

S T A N D A R D

f o r y e a r s

THIS LABEL is your PROTECTION

that yo u g et it

Every piece o f genuine Burrell glass-ware is individually marked

M ORE TH AN

25

DIFFERENT M ODELS ARE ILLUS­

TRATED IN BURRELL C A T A L O G 79. M AN Y OTHERS C A N BE "B U ILT-U P". A SK FOR THE M A N U A L—

A L S O . . . .

MODERN APPARATUS

To gas analysts, Burrell m eans all that is m od ern in apparatus, b e ca u s e of the m any im provem ents constantly in corp ora ted to insure m ore a ccu ra te results, m ore con v en ien t operation, m ore fle x i­

bility, and m ore m ech a n ica l p erfection in the apparatus itself— the net result b e in g standard, com p a ra tiv e, re p ro d u cib le m easuring of c o m p o ­ nents.

BUILD YOUR OWN

Burrell leadersh ip d e v e lo p e d the beautiful n ew

“ BUILD-UP" m odels, both Laboratory and Port­

a ble types, w h ich are bou g h t in a c c o r d a n c e with you r current n eed s and ch a n g e d or e x p a n d e d at any later date to co m p ly with you r future regu ire- ments.

INTERCHANGEABLE PARTS

Most Burrell m od els feature the fam ous patented Francis A u to-B u bbler Pipette w h ich elim inates the old-fashion ed stop cock . In trodu ced a few years ago, the Francis Pipette g u ick ly re p la c e d other kinds and today is the most popu lar.

BURRELL TRADE MARK

A ll Burrell gas apparatus h ave standardized in terch a n gea ble glass parts— identified b y the BURRELL LABEL show n a b ove. N one are g e n u in e without this mark o f distinction.

Do you know about Oxsorbent and Cosorbent— the fastest, most thoroughly modern gas absorbents?

BURRELL TECHNICAL SUPPLY COMPANY

1936-42 FIFTH AVENUE . . . . PITTSBURGH, PA. U.S.A.

6 INDUSTRIAL AND ENGINEERING CHEMISTRY VOL. 11, NO. 12

MERCK REAGENTS USED IN THE CHEMISTRY OF IRON

M n — S o d iu m B is m u th a te — assay 8 5 % — M n < ^ .0 0 0 5 % A m m o n iu m P e r s u lfa te — M n <^.0 0 1 %

P — A c i d M o l y b d i c — a ssay 8 5 % — fr e e f r o m C o p p e r M a g n e s iu m C h l o r i d e — < ^ .0 0 0 5 % P

A m m o n iu m C h l o r i d e — <^.0 0 0 2 % P

S i — A c i d P e r c h l o r i c 6 0 & 7 2 % — n o t m o r e th an 0 0 0 % SiC>2 S — C a d m iu m C h l o r i d e — < ^ .0 0 1 5 % S

B a r iu m C h l o r i d e — c le a r ly s o lu b le

M e r c k R e a g e n t M in e r a l A c i d s a n d A m m o n ia W a t e r a re m a r ­ k e t e d in " p o u r - c l e a n ” b o t t le s w it h n e w ly d e v e lo p e d , n o n ­ le a k in g a n d e a sily r e m o v a b l e p la s t ic s c r e w ca p s.

M E R C K & C O . Inc. ¿4ta-»-n^aeùœma

C€ / e m i A t â

R A H W A Y , N . J-

N ew Y o r k • Philadelphia • St. Louis • In Canada: M erck & C o. Ltd., M on treal and T o r o n to From iron ore to pig and cast irons,

the chemist and the metallurgist are dominant factors in the control o f the process and finished products.

A strong, tough, even-grained metal, yet soft enough to drill and cut, are quality factors dependent upon the constituent impurities in the ore, or their elimination through the chemistry o f the blast furnace process. Whether the iron be foun­

dry pig, cast iron pipe, cast iron locom otive cylinders, chilled cast iron wheels, malleable castings, gray iron castings— Merck Analytical Re­

agents gu id e the all im portan t C-Mn-P-Si-S balance.

Chemistry of

DECEM BER 15, 1939 ANALYTICAL EDITION 7

M aterial im provem ents in efficiency and added fea- Y ou r inquiry is invited. N o trouble to subm it pro­

lures o f operation are incorporated in our specifi- posals on you r requirements and, o f course, without

cations. obligation to you.

L w ^ e(l UeS} t ^ ,

J-i'p SO L D W S Z € 4 4 7 4 v 4 p ? 4

I I H O I l % K l f t l « U \ s | | { I I I I O N H P I H M . I M .

^ t'- - \ ■ ; f i - iVf _ , p ' * * , § 4-

Better Laboratory Equipment

L e a d in g F u m e D i s p o s a l S y s t e m

The highly developed and successful fume disposal system embodied in our Kjeldahl nitrogen apparatus is an out­

standing feature.

Combination digestion and distillation units in capacities

6

to 24. Separate units in capacities 6 to 48. All electric, all gas or units of both.

M any unique arrangements are available to save floor space and fit the particular needs of your laboratory.

Shown is an 18 flask capacity combination unit, electric­

ally equipped, arranged distillation decked over digestion.

Additional Users o f Our Kjeldahl Nitrogen Apparatus Since Publication o f Our New Catalogue March 1st , ¹⁹³⁹

B arrow -A gee M em phis, Tenn.

Iow a State, C ollege Am es, Iow a M .F .A . M illin g Co.

Springfield, M o.

F rem ont M ills F rem ont, Nebr.

Collins Flour M ills Pendleton, Oregon State of M issouri Kansas C ity, M o.

T h e H unted M lg. C o.

W ellington, Kansas E isenm ayer M lg. Co.

Springfield, M o.

U. S. Plant Industry G ainesville, Florida and Indio, Calif.

Purdue U niversity L afayette, Indiana A rizona U niversity T u cson, A rizona

State o f M on tana G reat Falls and H arlow ton, M on tana Kansas State C ollege M anh attan , Kansas A m erican Stores C o.

Philadelphia, Pa.

A m erican T o b a cco C o.

R ich m on d, Virginia W ilson & C om pany Oklahom a C ity, Okla.

Arkansas U niversity F ayetteville, Ark.

M on ta n a Flour M ills G reat Falls, M on tana T ri-S tate M lg . C o.

R a p id C ity , S. D . Oregon State C ollege Corvalis, Oregon U. S. F o o d & D rug B uffalo & Kansas C ity F ord M o to r C om pany D earborn, M ichigan

M ich . Stato C ollege Lansing, M ich . Torm inal F lour M ills P ortland, Oregon U nited M ills, Inc.

G rafton, Ohio St. J oe T esting Lab.

St. Joseph, M o.

Nebraska U niversity Lincoln, Nebraska

S tate o f W isconsin Superior, W is.

A . E. Staley M fg . Co.

Painesville, Ohio A rch er-D a n iels-M id- .

land D ecatur, Illinois U nion of S outh A frica N elspruit, Transvaal G olden W est M lg. C o.

Longm on t, C olorado

U . S. W ar D ept.

F ort M ason, Calif.

Lam ar F lou r M ills Lam ar, C olorado Tennessee U niversity K n oxv ille, T enn.

R oya l-S ta folife M ills M em phis, Tennessee T h e Larrow e M lg . C o : R ossford, Ohio State o f Indiana L a fay ette, Ind.

KJELDAHL NITROGEN APPARATUS

and

Associated Apparatus and Laboratory Tables

C R U D E F IB E R C O N D E N S E R An apparatus that will maintain a constant volume of solution and reduce frothing to a minimum. No metal parts are in contact with the solution. Rub­

ber hose connections are eliminated.

“ G O L D F IS C H ” E X T R A C T O R A radically improved ether extraction appa­

ratus that permits a material saving of time on control work and will be found most flexible for research work.

INDUSTRIAL AND ENGINEERING CHEMISTRY VOL. U , NO. 12

★ CHEM ICALLY STABLE

★ M E CH A N IC A LLY STRONG

★ HEAT RESISTANT

★ EASIER TO STA C K

★ EASIER TO USE

★ E C O N O M IC A L TO BUY

1 H E S E n e w P yrex b ra n d W a tch G lasses h ave b e e n sp e cifica lly d e sig n e d to m eet the g r o w in g d em an d for a ch e m i­

ca lly stable, strong, m ore resistant w atch glass. F abricated from P yrex b ra n d Bal­

a n c e d G lass, " P y r e x " W a tch G lasses p o s­

sess all these d esira ble qualities o f the glass itself— great m e ch a n ica l strength, ch em i­

c a l stability and therm al resistance. E ach p rop erty is b a la n ce d , o n e with the other, for m axim um value.

E ach "P y r e x " W a tch G lass is ca refu lly m ou ld ed . Both sizes h a v e the sam e radius

o f curvature for c o n v e n ie n c e in stacking.

W alls are uniform ly h e a v y to p ro v id e greater m e ch a n ica l strength; e d g e s fire- p o lish e d to p reven t ch ip p in g .

P rice d e co n o m ica lly , these n e w W a tch G lasses are m a de in tw o sizes and are p a ck e d in con v en ien t units of tw elve, 1 4 4 to the case, for ease

i n h a n d l i n g . N ow available in sizes listed from y o u r u s u a l s o u rce o f supply.

C ^orning

-means- Research in Glass

Net NET PRICE PER PKG.

Size Quan. Net Price In Assortments of

Dia. Per Price Per 20 50 100

Number and Type mm Pkg. Each Pkg. Pkgs. Pkgs. Pkgs.

9985 WATCH GLASSES 90 144 $.075 $9.72 $9.23 $8.75 $8.26

100 144 .08 10.37 9.85 9.33 8.81

“ PYREX" is a registered trade-mark and indicates manufacture by

C O R N I N G GLASS W O R K S • C O R N I N G , N. Y.

A Timely New Item in Pyrex brand Laboratory Ware

/!4w ^PYREX

_{B R A N D}

WATCH GLASSES

Fabricated from the

Balanced Glass

DECEM BER 15, 1939 ANALYTICAL EDITION 9

A N INEXPENSIVE MUFFLE FURNACE

W I T H W I D E , DE E P H E A T I N G C H A M B E R

Muffle D imensions:

W id th ” - 5 inches Depth - - - - 8 inches H e i g h t ...3 inches

Ideal for Igniting Residues in Dishes

13657

13655 FU R N A C E S, M uffle, E lectric, C enco M o d e l C M 538 w ith muffle dim ensions that will perm it heating o f the m axim um num ber o f the usual lab ora tory vessels for the volu m e o f the heat­

ing cham ber. T h is furnace, w ith ou t tem perature con trol, is for interm ittent use. Safe operating tem perature is a bou t 9 5 0 °C or 1750°F, bu t m a y be run up to as high as 1020°C or 1850°F (bright cherry red) for short intervals. F or continuous use, we recom m end either N o. 13656 Furnaces with rheostat or N o . 13657 Furnaces with rheostat and p y ­ rom eter. P ow er consum ption, 1100 watts. D im ensions, over all: H eight, 15 inches;

width, 17}4 inches; depth, 13}^ inches. M uffle space: H eight, 3 inches; w idth, 5 inches; depth, 8 inches. N e t weight, 35 lbs.

N o ... A B F or volts, A .C . or D .C ... 115 230 E a c h ... $ 3 5 .0 0 $ 3 5 .0 0 13656 F U R N A C E S , M u ffle, E lectric, C enco M o d e l C M 538, with R h eostat, sam e as N o. 13655 F u r­

naces, bu t with the a ddition o f a rheostat for reducing the current, w hen m axim um safe tem perature is reached. N et weight, 41 lbs.

N o ... A B F or volts, A .C . or D .C ... 115 230 E a c h ... 4 7 .5 0 4 7 .5 0 13657 FU R N A C E S, M u ffle, E lectric, C enco M o d e l C M 538, with R h eostat and P yrom eter, same as N o. 13656 Furnaces, b u t with the addition o f a p yrom eter for indicating the muffle tem perature.

N o ... A B F or volts, A .C . or D .C ... 115 230 E a c h ... 7 7 .5 0 ‘ 7 7 .5 0

C H I C A G O 1 7 0 0 Irving P k . B lvd .

L a k e v ie w Station

S C I E N T I F I C I N S T R U M E N T S

New York • Boston •

w

C H I C A G O

L A B O R A T O R Y A P P A R A T U S

Toronto • Los Angeles

B O S T O N 7 9 A m h e rst St.

Cam bridge Station

10 INDUSTRIAL AND ENGINEERING CHEMISTRY VOL. 11, NO. 12

B E C K M A N

G L A S S E L E C T R O D E pH M E T E R S

L A B O R A T O R Y M O D E L G and IN D U S T R IA L M O D E L M B E C K M A N pH M E T E R , Laboratory M o d e l G. F or precise meas-

ments in the laboratory but also suitable for field and factory use. A portable, self-contained, direct reading instrument, with slide wire po­

tentiometer, suitable for practically all substances, requiring on ly 2 to 3 ml o f solution. Similar to the original Laboratory M od el F but with the following im provem en ts:

Combination pH and millivolt scale, permitting both pH determinations and oxidation-reduction potential measurements

New type, factory filled and sealed glass electrode and charged calomel electrode New lock-down electrode switch, for ease in making titrations

A switch shifts the calibration from pH units to millivolts. Range pH 0 to pH 13, or —1300 to +1300 millivolts. The instrument is sensitive to 0.01 pH

and, in general, a practical accuracy of ±0.05 pH can be expected over the range to pH 9.5.

The condition of balance or unbalance is continuously indicated, by means of a lock-down electrode switch, permitting rapid measurements.

Built-in temperature compensator from 10 to 40 °C and asymmetry potential adjustor are provided. In shielded, hardwood carrying case 11 X 9 X 8 inches, total weight 19 lbs.

4919. Glass E lectrode pH M eter, B eckm an Laboratory M o d e l G , as abov e do- scribed, com p lete w ith glass, calom el and platinum electrodes, glass beaker 5 ml ca pa city , beaker holder of Bakelite, one 100 ml dropper b ottle of B uffer M ixtu re pH 3.98 and one 50 m l dropper bottle o f P otas­

sium C hloride solu tion, saturated, in carrying case, with detailed direc­

tions for u se... 195.00 C ode W o r d ... Fabob

4918-R

Industrial M od el M , B eckm an pH M eter

4919

Laboratory M o d e l G , B eckm an pH M eter

B E C K M A N pH M E T E R , Industrial M o d e l M . Designed especially for factory and field use but also suitable for laboratory use. A portable, self-contained instrument o f rugged construction, without slide wire potentiometer, incorporating the follow ing features:

Anew electronic tube voltmeter circuit, permitting con tin u ou s, direct pH readings

New type, factory filled, internally shielded glass electrode and companion calomel electrode, charged, ready for use The scale reads from pH 0 to pH 14 in 0.1 pH divisions, with double graduations of pH 0 to pH 7 and pH 7 to pH 14, the acid or alkaline range being selected by a switch. The instrument is adjusted for normal operation at 25 °C and a control is provided for the compensation of asymmetry potential.

A 50 ml Pyrex beaker is used as a container for the test solution and readings can be made with as little as 10 ml of-sample.

The instrument is entirely self-contained, with necessary dry cells for operation, in case 13‘ A X 9‘ A X 9 inches, weight 24 lbs.

491 8 -R . G lass E lectrode pH M e te r, B eckm an Industrial M o d e l M , as a b ov e described, com plete with shielded glass electrode, sealed calom el electrode, Pyrex glass beaker 50 m l, 100 ml b ottle of saturated K C l solu tion and 1 pt. b o ttle o f B uffer M ixtu re pH 7.0. In carrying case, with directions for use m ounted in the

l id ... 150.00

C o d e W o r d ... Fabnl

C opies o f ttvo n ew p a m p h lets, EE-112, and EE-113, giving detailed d escrip tion o f b oth m odels, to g eth er w ith a ccessories, sen t u p on req u est.

ARTHUR H. THOMAS COMPANY

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

LABORATORY APPARATUS AND REAGENTS

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

Cable Address, “ B alance,” Philadelphia

INDUSTRIAL «■«. ENGINEERING CHEM ISTRY

A N A L YTIC A L EDITION ^ Harrison E. H ow e, Editor

Determination of Iodine

In Thyroid and Its Preparations by Cerate Oxidimetry

WAYNE W . H IL T Y AND DALE T . W ILSON, Eli Lilly and C om pany, Indianapolis, Ind.

I

N A N attempt to develop a procedure which would be superior to that in the U. S. Pharmacopoeia X I for the determination o f iodine in thyroid preparations, the methods presented in the literature b y Middleton (4), Kendall (2), and Harrington and Randall (1), involving fusion with an alkali in the presence o f an oxidizing agent, and b y Trevorrow and Fashena (7), incorporating oxidation in an acid medium, were investigated.

In the former methods the solutions o f the fusion mass are neutralized and made acid, after which an excess of either chlorine or bromine is added for the purpose of oxidizing any iodide to the iodate form. In the authors’ opinion, incon­

sistent results, obtained b y these methods, are due to tech­

nical difficulties in eliminating these excess oxidizing'agents.

The latter method proved to be unsatisfactory for routine analysis.

Further search of the literature revealed the more recent works of Lewis (S) on the determination o f iodides b y eerie sulfate and of Smith (5, 6) on the volumetric oxidation by eerie sulfate and the application of o-phenanthroline as an in­

dicator in this reaction.

Experim ental

The authors’ recent experimental work reveals that when thyroid gland or a mixture o f thyroid gland and a diluent is fused with anhydrous sodium carbonate both inorganic and organic iodine combines with sodium to form sodium iodide.

Since this iodide salt and the unused sodium carbonate are readily soluble in water, the insoluble carbonaceous material can be removed by filtration. The resulting solution, when acidified with hydrochloric acid to make a 2 ili (molar) solu­

tion o f the acid, can be titrated with volumetric eerie sulfate and the percentage o f iodine contained in the original thyroid sample calculated.

The sodium iodide formed in the reaction described above is quantitatively oxidized by the eerie sulfate solution accord­

ing to the following equation:

HOI

Nal + 6Ce(SO,)2 + 3H20 ... NalO, +

3Ce2(SO,)2 T 3H2SO, Reagents

An h y d r o u s So d i u m Ca r b o n a t e, reagent grade.

Ce r i c Su l f a t e So l u t i o n, 0.005 N. Dissolve 1.70 to 1.80 grams of anhydrous ceric sulfate [Ce(SO,)2, molecular weight 332.25] in 1000 cc. of cold, dilute sulfuric acid made by adding 300 cc. of dilute sulfuric acid (one volume of water plus one volume of concentrated sulfuric acid) to 700 cc. of water. The salt

first hydrates and with continued stirring in the cold completely dissolves and is ready to be standardized as follows:

Transfer 2 cc. of standardized ferrous sulfate solution to a 250-cc. beaker, using a calibrated pipct, and dilute to 100 cc.

with 2 M sulfuric acid or hydrochloric acid. Add 1 drop of 0.025 M o-phenanthroline ferrous complex and titrate with the unknown ceric sulfate solution. The end point is from pink to pale green. An overstepped end point can be back-titrated (color change, slightly green to pink).

Normality of Ce(SOt)2 = volume of 0.1 N FeSO, X 20 volume of Ce(SC>4)2 required X

normality of FcSO, This solution has been found to remain stable for periods of at least 2 months.

Fe r r o u s Su l f a t e, 0.1 N. Dissolve 27.80 grams of ferrous sulfate (FeS0,.7H20 ) in 980 cc. of water to which have been added 20 cc. of dilute sulfuric acid (one volume of concentrated sulfuric acid plus one volume of water). Standardize as follows:

Take 25- or 50-ce. portions of the approximately 0.1 N solution of ferrous sulfate with a calibrated pipet and transfer to a 250-cc.

beaker. Dilute to 200 cc. with 2 M sulfuric or hydrochloric acid.

Add 1 drop of 0.025 M o-phenanthroline ferrous complex and titrate with standard potassium dichromate until the pink solu­

tion turns pale green. An overstepped end point can be back­

titrated (color change, pale green to pink).

■n t i-i r u. volume of 0.1 N K 2Cr20 7 required . , _ , Normality of FeSO, = j . 1--- X 0.1

volume of FeSO, required

Po t a s s i u m D i c h r o m a t e, 0.1 N. Dissolve 4.9035 grams of reagent potassium dichromate, which has been pulverized and dried to constant weight at 120° C., in sufficient distilled water to measure exactly 1000 cc. at standard temperature.

o- Ph e n a n t h r o l i n e Fe r r o u s Su l f a t e So l u t i o n, 0.025 M.

o-Phenanthroline monohydrate, molecular weight 198, melting point 90-100° C . Use 1.485 grams for 100 cc. of 0.025 M solution as below. Ferrous sulfate, 0.025 M solution. Use 0.695 gram of ferrous sulfate heptahydrate in 100 cc. of solution.

Make fresh as needed.

Dissolve the ferrous sulfate, add the o-phenanthroline mono­

hydrate, and stir until all is dissolved, giving a dark red solu­

tion. One drop of this indicator serves for each titration in a volume of approximately 150 cc.

Hy d r o c h l o r i c Ac i d, reagent grade.

Procedure for Thyroid Gland

Thoroughly mix 1 gram of thyroid, finely powdered and ac­

curately weighed, with 15 grams of anhydrous sodium carbonate in a nickel crucible of about 125-cc. capacity, and spread an additional 10 grams of anhydrous sodium carbonate evenly over the surface. Heat the crucible in the flame of a Bunsen burner at a rate to attain a dull red color in 10 minutes. Then place the crucible and contents in a muffle furnace and heat at a temperature not to exceed 500° C. for 30 minutes. Cool the mixture and transfer it to a 250-cc. beaker containing 100 cc.

of warm distilled water. Rinse the crucible with 25 cc. of dis- 637

638 INDUSTRIAL AND ENGINEERING CHEMISTRY VOL. 11, NO. 12 tilled water and add it to the beaker. Apply gentle heat to the

beaker and contents to ensure solution of the sodium carbonate and iodide. Filter the solution while still warm and wash the carbonaceous material with several small portions of warm distilled water.

Cool the filtrate and cautiously neutralize with concentrated hydrochloric acid, using litmus paper as an indicator. For each 100 cc. of neutralized solution, add 20 cc. of concentrated h3rdro- chloric acid and titrate with 0.005 N eerie sulfate, using a micro-

Ta b l e I. Co m p a r i s o n o f Re s u l t s f o r Th y r o i d Gl a n d (W eig h t o f sam ple, 1.0000 gram)

Assay M eth od

P roposed

U . S. P. X I

P roposed

U. S. P . X I

Sample

0.005 N C c(SO 02 Required®

0.005 N Na?SjOa

Required® Iod in e

Cc. Cc. %

A 6 .1 3 2 0 .1 9 49

A G. 151 0 .1 9 55

A 6 .4 0 3 0 .2 0 35

A 6 .2 0 3 0 .1971

A 6 .3 5 3 0 .2019

A 2 0 .2 2 0 .2 1 4

A 21.5 0 0 .2 2 8

B 5 .9 5 3 0 .1 8 92

B 5 .9 0 3 • 0 .1 8 76

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

B 5 .7 3 3 0 .1 8 2 2

B 5 .6 5 3 0 .1 7 9 7

B 2 1 .2 6 0 .2 2 5

B 20.0 4 0 .2 1 2

° B lank previously deduoted.

Co m p a r i s o n o f Re s u l t s f o r 6.48-Mg. ( 0 . 1 - Gr a i n) Th y r o i d Ta b l e t s

Ta b l e II.

Assay M eth od

Proposed

U . S. P. X I

° B lank previously deduoted.

T h y roid in

0.005 N 0.005 N Iodine

Per C ent of Labeled

Ce(SO<)t NaiSiOa per A m ou n t of

Sam ple Required® Required® T ablet T h y roid

Grains Cc. Cc. M g.

4 .0 0 1.649 0.0 0 13 1 0 100.46

4 .0 0 1.667 0.0 0 13 2 4 101 .56

4 .0 0 1.722 0.0 0 13 6 8 104.90

4 .0 0 1.740 0.0 0 13 8 2 106.00

4 .0 0 1.676 0.0 0 13 3 2 102.10

4 .0 0 1.640 0.001303 9 9 .9 1

2 .5 0 2 .3 0 0 0 .0 0 09 7 3 7 5 .1 0

2 .5 0 2 .6 0 0 0.0 0 11 0 0 8 4 .9 0

Ta b l e III. Co m p a r i s o n o f Re s u l t s o n Ma n u f a c t u r e r s’ Sa m p l e so f 64.8-Mg. ( 1 - Gr a i n) Th y r o i d Ta b l e t s Assay

M eth od

Proposed

U .S . P. X I

Proposed

U . S. P. X I

Proposed

U . S. P . X I

P roposed

U . S. P. X I mplc

T h yroid in Sample

0.005 N 0.005 N Ce(SO<)i NaiSiOa Required® Required®

Iodine per T a b let

Per C ent of Labeled A m ou n t of

T h y roid

A

Grains 10

Cc.

4 .1 4 9

Cc. M g.

0.0 1 31 9 101.74

A 10 4 .2 4 0 0 .0 1 34 8 102.95

A 10 4 .3 4 8 0.0 1 38 2 106.62

A 10 4 .1 5 5 0.01321 101.79

A 10 4 .0 4 3 0.0 1 28 5 9 9 .1 4

A 10 3 .9 8 3 0.0 1 26 6 9 7 .6 7

A 12 14.80 0.0 1 30 5 100.70

A 12 16.0 0 0.01411 108 .80

A 12 14.58 0.0 1 28 5 9 9 .1 9

B 10 4 .0 9 2 0.0 1 30 0 100.34

B 10 4 .0 7 2 0.01294 9 9 .8 5

B 10 4.131 0.0 1 31 3 101 .30

B 10 4 .1 0 2 0.0 1 30 3 100 .59

B 10 4 .0 1 3 0.0 1 27 5 9 8 .4 0

B 10 4 .0 3 3 0.0 1 28 2 9 8 .8 9

B 12 16.25 0.0 1 43 3 110.50

B 12 16.1 0 0.01420 109.50

C 10 4 .1 1 2 0.0 1 30 7 100.83

C 10 4.171 0.0 1 32 6 102 .28

C 10 4 .1 6 1 0.0 1 32 2 102.13

C 10 4 .2 8 9 0.0 1 36 3 105.17

C 10 4 .2 5 0 0.01351 104.22

C 10 4 .2 3 0 0 .0 1 34 4 1 03.73

C 15 1 9.97 0.01409 1 08 .60

C 15

...

^{1 9.49} 0 .0 1 37 5 1 06.10

D 10 4 .1 1 2 0.0 1 30 7 1 00.83

D 10 4 .0 7 2 0.0 1 29 4 9 9 .8 5

D 10 3 .9 9 3 0.01269 9 7.9 1

D 10 4 .1 9 1 0.0 1 33 2 1 02.77

D 10 4 .1 0 3 0.0 1 30 4 100.61

D 12.72 17.5 9 0.0 1 46 3 112 .10

D 12.72 18.22 0 .0 1 51 5 116.90

buret and 1 drop of o-phenanthroline ferrous sulfate, 0.025 M solution, as indicator, the end point being the first bluish green tinge that remains in the solution for i minute. Conduct a blank test with the same quantities of the same reagents omitting only the thyroid, and fusing as directed, and subtract the volume of 0.005 N eerie sulfate consumed from that consumed by the thyroid.

Each cubic centimeter of 0.005 N eerie sulfate is equivalent to 0.0003178 gram of iodine in thyroid combination.

Procedure for Thyroid Tablets

Weigh not less than 20 of the tablets and reduce them to a fine powder without an appreciable loss. Substitute approxi­

mately 1 gram of tablet mixture, accurately weighed, for the thyroid sample and proceed with the proposed and U. S. P. X I methods for the assay of thyroid gland. The sample weight should be increased so that the amount of thyroid will equal or exceed 259.2 mg. (4 grains).

Percentages of the labeled amount found are calculated on the basis of 0.200 per cent iodine in the thyroid gland.

Accuracy o f M ethod

A mixture consisting of four parts of potassium iodide (99.40 per cent KI) and one part of lactose, having a theo­

retical iodine content of 60.78 per cent, was assayed by both the U. S. P. X I and the proposed methods for thyroid. Re­

sults obtained are listed in Table V.

C om m en ts and Conclusions

Fusion of the thyroid material with anhydrous sodium carbonate does not destroy the carbonaceous material. How­

ever, this does not interfere with the solubility of the sodium iodide formed in the reaction. Attempts to incorporate an oxidizing agent with the anhydrous sodium carbonate to de­

stroy the carbonaceous material proved unsatisfactory, in that it interfered with the eerie sulfate titration.

The sodium chloride formed when the excess sodium car­

bonate is neutralized with hydrochloric acid does not interfere with the oxidation of the sodium iodide. Sulfuric and nitric acids, if used to neutralize the excess sodium carbonate, give salts which are easily oxidized by eerie sulfate and thus give high results.

The data as listed in the tables show the comparable results that may be obtained by the two methods. The proposed method has the advantage of titrating the original iodide formed in the fusion reaction and thus does not introduce any other steps which are likely to interfere with the final result.

The proposed method is applicable for the gland as well as

Ta b l e IV. Co m p a r i s o n o f Re s u l t sf o r 129.6-Mg. ( 2 - Gr a i n) Th y r o i d Ta b l e t s

Per C ent of

° B lank previou sly deducted.

T h y roid 0.005 N 0.005 N Iodine L abeled

A ssay in C c(S O i)i NaiSjOa per A m ou n t ol

M eth od Sample R equ ired“ Required'B‘ T ablet T h yroid

Grains Cc. Cc. M g.

P roposed 10 3 .8 9 4 . . . 0.0 2 47 5 9 5 .4 9

10 3 .9 5 4 . . . 0 .0 2 51 3 9 6 .9 6

10 3 .8 7 5 . . . 0.0 2 46 3 9 5 .0 2

10 3 .8 6 5 . . . 0.02457 9 4 .7 7

10 3 .9 4 4 . . . 0 .0 2 50 7 9 6.7 1

10 3 .9 9 3 . . . 0 .0 2 53 8 9 7.9 1

U . S. P . X I 20 . . . 2 3 .2 0 0 .0 2 45 5 9 4 .7 0

20 . . . 2 3 .0 0 0 .0 2 43 3 9 3 .8 8

° B lank previously deducted.

Ta b l e V. Ac c u r a c y o f Me t h o d

D ev iation

W eight of from

M eth od Sample Iodine T h eory

Oram % %

P roposed 0 .1 0 0 0 6 0 .8 4 + 0 . 0 6

0 .1 0 0 0 6 0 .8 4 + 0 . 0 6

0 .1 0 0 0 0 0 .0 3 - 0 . 1 5

0 .1 0 0 0 6 0 .5 0 - 0 . 2 2

U . S. P . X I thyroid 0 .1 0 0 0 6 2 .3 7 + 1 .5 9

0 .1 0 00 6 2 .1 7 + 1 .3 9

DECEM BER 15, 1939 ANALYTICAL EDITION 639 tablets of all grainages of thyroid, whereas, the authors

know of no other method which gives accurate and consistent results with thyroid tablets.

The proposed method may be modified to make it applicable for the determination of thyroxine in the thyroid gland and its preparations.

Acknow ledgm ents

The writers wish to express their sincere appreciation to Edward J. Hughes and Robert M. Lingle for their assistance in the preparation of this paper.

Literature Cited

(1) Harrington, C. R., and Randall, S. S., Quart. J. Pharm., 2, 501 (1929).

(2) Kendall, E. C., J. Biol. Chem., 43, 149 (1920).

(3) Lewis, D., In d. Enq. Ci i e m., Anal. Ed., 8, 199 (1936).

(4) Middleton, G„ Analyst, 57, 603 (1932).

(5) Smith, G. F., “ Ceric Sulfate” , Vol. I, 3rd ed., Columbus, Ohio, G. Frederick Smith Chemical Co., 1935.

(6) Smith, G. F., “ Ortho-Phenanthroline” , Columbus, Ohio, G.

Frederick Smith Chemical Co., 1935.

(7) Trevorrow, V., and Fashena, G. J., J. Biol. Chem., 110, 29 (1935); 114,351 (1936).

A Photelometric Study of the Lead-Dithizone System at 610 Millimicrons

CHARLES L. G U ETTEL, D evelopm ent Laboratories, C entral S cientific C o., C hicago, III.

I

N ADAPTING the Photelometer (5) to the measurement of the lead-dithizone complex in chloroform for the quan­

titative determination of lead, various filters were tried with a 1-cm. absorption cell and a distilled water reference solu­

tion. In the preliminary work light filters transmitting in the vicinity of 510 mg were used, following the suggestion of Clifford and Wichmann (S). In this spectral range the red lead complex absorbs strongly and the green dithizonc trans­

mits freely. Using the chemical procedure as outlined by the Association of Official Agricultural Chemists (1) for the mixed color method, appreciable spreads were obtained between 0 and 50 micrograms of standard lead solution. However, the small change in transmission for this lead range pre­

cluded its use as a routine method. Using the same chemical procedure, the spread was approximately doubled when a filter having a maximum transmission at G10 mg was sub­

stituted for the blue-green filter. The transmission curves of the lead-dithizone system as shown by Clifford and Wich­

mann (2, Figure 1) indicate that such an increase in the spread is to be expected.

Experim ental

Using the 610 my filter, a study was made to determine the relationship between the lead and dithizone-chloroform concen­

trations which would produce the greatest sensitivity for a given lead range. All reagents and apparatus were carefully purified, following the suggestions of the A. O. A. C. (I). Two batches of Eastman diphenylthiocarbazone (dithizone) were purified inde­

pendently and were used to prepare two stock solutions of 30 mg. of dithizone per liter of redistilled c. p. chloroform. Solu­

tions of 2, 4, 8, 12, and 16 mg. of purified dithizone per liter of re­

distilled chloroform were prepared by diluting the 30-mg. per liter stock solution. Two standard lead solutions (1 ml. = 1 microgram of lead) in 1 per cent nitric acid were prepared from two individual, twice-recrystallized batches of c. p. lead nitrate, using redistilled water from a Pyrex distillation apparatus. The ammonia-cyanide mixture was prepared by pouring a quantity of redistilled ammonia equivalent to 19.1 grams of ammonia into a 500-ml. volumetric flask, adding 100 ml. of a 10 per cent potas­

sium cyanide solution, and diluting to tbe mark.

Procedure

The preparation of the standard lead solutions for color development was based on the method of the A. O. A. C. (I).

Twenty milliliters of the standard lead solution (1 ml. = 1 microgram) were pipetted into a 50-ml. volumetric flask and 1 per cent nitric acid was added to the mark. The resulting solu­

tion represented a 20-microgram lead standard in the proper condition for the color development. Standards ranging from

0 to 50 micrograms of lead were prepared by changing the quan­

tity of the standard lead solution and diluting to the 50-ml. mark with 1 per cent nitric acid.

For color development the procedure was as follows: The 50-ml. aliquot containing the standard solution was poured into a 250-ml. Pyrex separatory funnel, 10 ml. of the ammonia-cyanide mixture were added from a buret, and from another buret 15 ml.

of dilhiione-chlorofoim solution (the concentration of dithizone depending on the lead range to be covered) were added. The separatory funnel was thoroughly shaken and the layers were allowed to separate. The chloroform layer was filtered and read immediately in the Photelometer. The water layer was discarded.

Discussion o f Results

Five dithizone solutions were prepared by the above pro­

cedure and the calibration curves of Figure 1 were obtained.

Each curve covers the range of solutions, the colors of which vary from green to red, and all curves are asymptotic to the vertical axis. The shapes of the curves, including curve E, are characteristic of the instrument when transmission in­

creases with concentration (4). In general, for the filter photometer, actual transmission factors for low transmission values are usually too great. Furthermore, the vertical dis­

placement in the substantially parallel portion of the curves corresponds to approximately 20 micrograms of lead for each change in the standard dithizone solution of 4 mg. per liter;

10 micrograms for a change of 2 mg. per liter.

The curves indicate that 15 ml. of a solution containing 12 mg.

of dithizone per liter are appropriate for a lead range of 15 to 50 micrograms. For a lead range of 0 to 15 micrograms, 15 ml. of a solution containing 4 mg. of dithizone per liter are preferred.

The spread between 0 and 5 micrograms of lead in scale divisions is approximately ten times as great on curve A as on curve E.

However, curve A is valuable only when it is definitely known that the lead concentration of the unknown does not exceed approximately 5 micrograms. For example, using 15 ml. of a solution containing 2 mg. of dithizone per liter, the transmission of solutions containing 10, 20, 30, etc., micrograms of lead would be essentially the same, owing to the asymptotic nature of the curve for transmission factors near unity. Such a condition sug­

gests that if the approximate amount of lead is unknown, a pre­

liminary test should be made using 15 ml. of a more concentrated dithizone solution for which a calibration curve has already been prepared. If the lead is found to be extremely low, a second aliquot of the unknown may be treated with a more dilute dithizone solution, so as to utilize the greater sensitivity of the curves toward the right in Figure 1.

For the range 0 to 50 micrograms of lead two curves are sufficient— namely, B and D. Curve B is appropriate for the

640 INDUSTRIAL AND ENGINEERING CHEMISTRY VOL. 11, NO. 12

The concentrations o f dithizone for curves A , D, C, D , and E are 2.0, 4.0, 8.0, 12.0, and 16.0 m g. per liter, respectively. A different lead standard was used for each p oin t; the circles and crosses indicate different dithizone solutions. Filter, CIO m p, 1-cm . absorption cell. V olu m e o f dithizone

solu tion, 15 ml.

range from 0 to 15 micrograms and curve D is suitable for the region from 15 to 50 micrograms.

Although Clifford and Wichmann specify a blue-green filter for the lead-dithizone system, they make the following statement (3): “ Theoretically a better spread could be ob­

tained by working at 610 mp but the mechanics of the reaction require a small excess of dithizone to be present even at the upper end of the range to hold the lead as PbD. in the chloro­

form phase. Under these conditions the so-called ‘saturated’

color takes the form shown by the dotted line, the transmission being greatly repressed by this excess. Transmission in the green is little affected.”

The importance of an excess of dithizone to prevent the decomposition of the red lead dithizone at the upper end of the lead ranges is recognized. However, the useful range of the calibration curves of Figure 1 obtains for solutions in which an excess of dithizone exists. The upper limit of the useful range of curve A corresponds approximately to a trans­

mission factor of 0.97 (Photelometer reading = 97.0); curve B, approximately 0.95; curve C, about 0.92; etc. Above these transmission factors where the excess of dithizone dis­

appears because of its reaction with the greater quantities of lead, the decomposition of lead dithizone probably occurs on account of the equilibrium Pb + 2D PbD2- Thus, the instability of the complex lead dithizone occurs in the insen­

sitive and unused portion of the calibration curve.

The precision of the instrument for the lead analysis may be determined from the curves of Figure 1. For the range of 0 to 15 micrograms of curve B, the readings cover twenty-two scale divisions which can be estimated within 0.2 division without difficulty and to 0.1 division by careful observers.

This condition indicates a precision greater than 1 per cent.

Thus, the precision of the instrument exceeds the accuracy of the chemical procedure even for this lower lead range.

Because of the possible instability of chloroform-dithizone solutions or the probable difficulty of preparing an exact duplicate of the original chloroform-dithizone solution, it is advisable to check each calibration curve frequently, using in the procedure a standard lead solution equivalent to the lead concentration at the lowest portion of the useful range of the curve. For curve D this standard solution would be a 15-

microgram lead standard, and for curve B a blank dithizone solution (15 ml. of a solution containing 4 mg. of dithizone per liter) would be appropriate. If the Photelometer reading for these reference solutions deviates from the original cali­

bration curves, all abscissas of the points on the curves should be displaced in the same direction an equal distance over the useful range of the curves. This shifting of the curves is legitimate as the useful portions of all curves are substantially parallel.

Acknow ledgm en t

The writer is indebted to members of the staff of this labo­

ratory for their constructive criticisms.

Literature Cited

(1) Assoc. Official Agr. Chem., “ Official and Tentative Methods of Analysis” , p. 375 (1935).

(2) Clifford and Wichmann, J. Assoc. Official Agr. Chem., 19, 132 (1936).

(3) Ibid., p. 146.

(4) Hoffman, J. Biol. Chcni., 120, 51 (1937).

(5) Sanford, Sheard, and Osterberg, A?n. J. Clin. Path., 3, 405 (1933).

A Method for Determin­

ing Deguelin in Derris and Cube

LYLE D. GOODHUE a n d H. L. HALLER Bureau o f E n tom ology and Plant Quarantine, United States D epartm ent o f A griculture, W ashington, D. C.

W

HEN derris or cube is extracted with a suitable solvent, such as chloroform, the resulting extractive can easily be divided into three fractions. The rotenone can be removed by crystallization from carbon tetrachloride (9, 10), and the remaining resin can be separated into an alkali-soluble and an alkali-insoluble portion (5). The last part has been assumed to consist largely of optically active deguelin, since racemic deguelin is often readily obtained on further treatment of this fraction with dilute alkali.

The insecticidal effect of the alkali insoluble fraction, which contains optically active deguelin, has been shown to be of the same order as that of rotenone {12). In its optically in­

active form, however, deguelin and its dihydro derivative are much less toxic than rotenone, except when applied in kero- sene-cyclohexanone solution {2,12). Since the toxicity of the noncrystalline fraction may at times be due largely to the presence of optically active deguelin, a further study of the methods for determining this compound seemed desirable.

By subtracting that portion of the dehydro compound which results from rotenone, deguelin can be estimated by the method of Takei {13) or Tattersfield’s modification {14), which depends on the formation of the dehydro compounds. Other materials similar to rotenone and deguelin would also be ex­

pected to form dehydro compounds, and the results by this method are probably too high. Cahn, Phipers, and Boam {1) report a method for the determination of deguelin that is based on the Goodhue modification (3) of the Gross and Smith red-color test. By this method they find the amount of de­

guelin in a given type of derris resin to be substantially con­

stant. Recently the writers have encountered many samples which appear to have considerable deguelin when tested by both the red-color analysis and the deliydro-compound