A n a l y t i c a l E d i t i o n V o l . 5 , N o . 2
M a r c h
1 5 , 1 9 3 3
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. 25, CONSECUTIVE NO. 10
Pu b l i s h e d b y t h e Am e r i c a n Ch e m i c a l So c i e t y Ha r r is o n E . Ho w e, Ed i t o r
Pu b l i c a t i o n Of f i c e: E a s to n , P a .
Ed i t o r i a l Of f i c e:
R oom 706, M ills B uilding, W ash in g to n , D . C.
Te l e p h o n e: N a tio n a l 0848 Ca b l e: Jieohem (W ashington)
Ad v e r t i s i n g De p a r t m e n t: 332 W est 42nd S t.,
N ew Y o rk , N . Y.
Te l e p h o n e: B ry a n t 9-4430
Analysis of Refrigeration-Grade Liquid Sulfur Dioxide. . . ... F. A. Euslis
C O N T E N T S
19,200 Copies of This Issue Printed
| A Laboratory Esterifying and Fractionating Apparatus . . ...Carrol A . Doran 101 Note on Washing the Potassium Cobaltinitrite Precipitate.
... W. E. Thrun Quantitative Determination of Small Amounts of Hydro
cyanic Acid. . . Nalhan Gales and Andrew J. Pensa Determination of Dextrin, Maltose, and Dextrose in Corn Sirup . W. R. Felzer, J. W. Evans, and J. B. Longenecker International Atomic Weights, 1933 ...
Determination of Sulfur and Chlorine in Gasoline...
...Charles Wirlh III and M. J. Slross 77
79
80
81 84
85 Determination and Occurrence of Fluorides in Sea Water. .
. . . Thomas G. Thompson and Howard Jean Taylor 87 Removal of Corrosion Products from I r o n ...
... Thomas J. Finnegan and Richard C. Corey 89 Quantitative Determination of Formaldehyde and Benzal-
dehyde and Their Bisulfite Addition P rod u cts...
...L. II. Donnally 91 A Mechanical Device to Agitate Analytical Solutions by
Swirling. . . Arthur F. Scolt and Ellon F. Reid, Jr. 92 Colorimetric Determination of Thallium. . Paul A. Shaw 93 Microdetermination of Calcium in Sea Water...
... Paul L. Kirk and Erik G. Moberg 95 Relation between Volume of Respiration Chamber and Con
centration of Carbon Dioxide in End Sample and in Com
posite Sample of Air...M. Kleiber 98 Preparation of Aldehyde-Free Ethyl Alcohol...
... Albert W. Stout and• H. A. Schuelle 100
Determination of Amino Acids and Related Compounds in Honey...R. E. Lolhrop and S. I. Gerller 103 Effect of Alkali Treatment on the Yield of L ig n in ...
... Elwin E. Harris 105 Value of Electrical Methods for Estimating the Moisture
Content of Wheat...II. E. Hartig and B. Sullivan 107 Platinized Silica Gel as an Oxidation Catalyst in Gas
Analysis. I. . Kenneth A. Kobe and Elmer J. Arveson 110 Volumetric Methods of Estimating N it r it e s ...
...Raymond D. Cool and John II. Yoe 112 Determination of Carbon Dioxide in Continuous Gas
Streams. . . William McK. Marlin and Jesse R. Green 114 Apparatus and Methods for Precise Fractional-Distillation
Analysis. II and I I I ... Walter J. Podbielniak 119 Combustion Train for the Determination of Total Carbon
in Soils... T. H. Hopper 142 An Automatic Pressure-Regulating Unit for Vacuum Dis
tillation. . . . E. H. Huntress and E. B. Hershberg 144 A Laboratory Cooling U nit... D. II. Cook 147 An Inexpensive Muencke Blower. . . Richard F. Robey 148 A Stirrer Drive for Laboratory Use. . . Max H . Hubacher 149 Note on the Micro-Dumas Method. . . . M . L. Nichoh 149 A New Method for the Qualitative Detection of Casein in
Woods... T. H. Whilehead 150
S u b scrip tio n to n on-m em bers, In d u s t r i a la n d En g i n e e r i n g Ch e m i s t r y, $7.50 p e r y e ar. F o reig n po stag e $1.60, ex cep t to co u n tries a cc e p tin g m ai a t A m erican d om estic ra te s a n d to C an a d a . An a l y t i c a l Ed i t i o nonly, $1.50 p e r y e ar, single copies 50 cents, to m em bers 40 cen ts. Ne w s Ed i t i o non ly t
$1.50 p e r y e ar. S u b scrip tio n s, changes of a d d ress, a n d claim s for lo st copies sh o u ld be refe rred to C harles L . P arso n s, S ecre ta ry , M ills B u ild in g , W ash in g to n , D . C. T h e C ouncil h as v o te d t h a t no claim s will be allow ed fo r copies of jo u rn a ls lo st in th e m ails, unless such claim s a re receiv ed w ith in s ix ty d a y s of th e d a te of issue, a n d no claim s will be allow ed for issues lo st as a re s u lt of insufficient n o tice of change of ad d ress. (T en d a y s’ a d v an c e n o tic e req u ired .) "M issin g from files” c a n n o t be accep ted as th e reason for hono rin g a claim . If change of ad d ress im plies a change of p o sitio n , please in d ic a te its n a tu re .
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A N A L Y T I C A L E D I T I O N
m onogram
B a k e r & ^ A d A M S O N R eagents
M a n u f a c t u r e d b y G E N E R A L C H E M I C A L C O M P A N Y . . . 40 R e c t o r S t . , N e w Y o r k
Pub lish ed b y th e A m erican C hem ical Society, P u b licatio n Office, 2 0 th & N o rth a m p to n Sts. E a sto n P a
? * “ „ “ ^ ^ . ^ • Æ d e r . t h e « t o f M a r c h 3. 1879, « 4 2 tim es _a y e ar. In d u stria l E d itio n m o n th ly on th e 1 st; N ew s E d itio n on th e lO th a n d 2 0 th ; A n aly tical E d itio n b im o n th ly on th e 15th. A cceptance for m ailfn? a t s o e d a l
ra te o f postage provided for in Section 1103, A ct of O ctober 3. 1917, a u th o rized Tuly 13 1918.
Make Every Analysis One You 1
Swear to . . . on the Witness Stand
Y O U R profession involves re
sponsibility, whether you seek it or not. Y o u r notes, your reports are and must be based on facts.
E ven in routine work you disci
pline yourself to accuracy which approaches the absolute. N o man is infallible, but you never know when you m ay be called upon to swear to your results.
B ut, the Reagents? H ave you a confidence in their purity which justifies your naming your most careful analyses to be absolute fact? Y o u can have. B aker &
Adamson labeled purity is fact.
Each lot, as recorded on the unit packages, has been analyzed by methods and under supervision which leaves no question as to the accuracy of the result. T h e m a
terial you buy m ay have less im
purities than shown on the label;
never more. Y o u can swear to the stated purity of these reagents with the same conviction with which you certify your own work.
Because o f their importance to your cum ulative record o f personal success you will w ant the “ B & A ” label on all your supplies o f labora
tory chemicals.
You cannot fail to identify either the shield
or the B & A
Baker & A d a m s o n R e a g e n t s are carried in sto ck by leading d istrib u to rs.
March 15, 1933 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 5
FOR PRESSURES TO 2000ATM.
TEMPERATURES TO 1 0 0 0 ° C
AUTOCLAVES-
CONTACT APPARATUS G A S C O M P R E SS O R S CIRCU LA TIN G PUMPS LIQ U ID A IR P LA N TS VALVES AND FITTINGS C O K IN G APPARATUS OVENS
B E N Z E N E DETERMIN STEAM SUPERHEATERS
F O R H IG H PR ESS U R E RESEARCH W O R K
A U T O C L A V E S — for batch and continuous experiments in cracking and hydrogenation at temperatures up to 5 2 0 ° C and pressures up to 5 0 0 atm. or higher. Rotating and vibrating autoclaves. A utoclaves agitated b y means of circulating gas. Equipped with stuffing boxes for working with o il- sensitive and oil-dissolving materials and providing o il-free hydrogenation.
C O N T A C T A P P A R A T U S — for pressures up to 1 0 0 0 atm. and temperatures up to 1 0 0 0 ° C. For testing catalysts in ammonia synthesis and gas reactions.
G A S C O M P R E S S O R S — for all gases ex
cept oxygen. Suction capacities of 1 to 4 0 cub. m. per hour and more. End pressures up to 2 0 0 0 atm.
C IR C U L A T IN G P U M P S — for gases and liquids. Capacities of 1 6 to 1 5 0 0 litres and more of actual volum e lifted . A d justable and with volum e meters. End pressures up to 1 0 0 0 atm.
L I Q U ID A IR P L A N T S — with outputs of 1 to 7 .5 litres per hr.
V A L V E S A N D F IT T IN G S — for pressures up to 1 0 0 0 atm. with connecting passages from 2 to 2 5 mm. for fine adjustments.
FO R A N A L Y T IC A L W O R K L O W T E M P E R A T U R E C O K IN G A P P A R A T U S — for determination of low-tem pera- ture tar b y the Franz Fischer and Schrader methods. M a d e of aluminum. Capacities of 2 0 to 2 0 0 gr.
A L U M I N U M O V E N S — for low tem perature coking tests of bituminous ma
terials b y the A . W e in d e l process. For
about 3 kg. —
R O T A T IN G O V E N S — for d e term ination of low-temperature tar. Capacity, 15 kg.
O V E N S — with new control d e vices for catalytic purposes:
B a b o -M y e r system. M a d e of aluminum.
B E N Z IN E D E T E R M IN A T IO N A P P A R A TUS— D .R .G .M ., for determ ination, b y the A . W e in d e l and Tramm methods, of vapor
ized solvents in gases such as benzene and gasoline in tail gases.
S T E A M S U P E R H E A T E R S — D .R .G .M . by the Tropsch process. For gases and liquids.
Capacities, 3 and 8 kg. per hour at 3 7 0 ° C.
M a d e of aluminum.
Full information on any of these products may be had for the asking. O r , better still, if you are engaged in chemical re
search at high pressures and temperatures, our representative may be able to give you valuable assistance— S im p ly fill in and return the coupon below .
ANDREAS HOFER
H O C H D R U C K = A P P A R A T E B A U
M U L H E I M - R U H R G E R M A N Y
A N D R E A S H O F E R General P. O ., Box: 151 New York C ity
Dear Sir:
□ K in d ly send me descriptive literature on your various products.
□ Please have your representative get in touch with us.
N a m e .. . . Company.
A d d re ss..
3 CONSTRUCTIVE
MEASURES
to reduce your
laboratory glassware costs
P Y R E X L A B O R A T O R Y G L A S S W A R E
March 15, 1933 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 7
A N E W catalog o f P Y R E X L ab oratory G lassw are is on its w ay to you now . L o o k through it ca re fu lly — you w ill find evidence o f painstaking effort to m ake it o f m ore service to you. A n alphabetical in dex has been added at the back. R eferen ces to the literature have been am plified as w ell as descriptions o f the w are.
Bu t m ore than that, three im portant steps have been taken to provide you new econom ies on laboratory glassw are.
1 . M a n y new item s, heretofore obtainable only on special order have been added to the standard line.
2. Case quantities have been re
duced on m any item s and a new 25-case consum er’s discount estab
lished on all. F o r yo u r conveni
ence in ordering, net prices per case are show n fo r single cases, 2 5, 50 and 10 0 case quantities.
3. P rices have been reduced on m any item s, effective M a rc h 15 th ,
1 9 3 3 . R eductions are greatest on item s in com m onest use, thus ef
fectin g a m ajor saving on your total glassware costs. T est tubes, fo r exam p le, have had substantial reductions, ran ging as h ig h as 3 7 M % - R eductions on beakers run up to 2 0 % on the most popu
lar size.
W ith these three m easures in effect, it is m ore than ever true econom y to standardize on P Y R E X Lab o rato ry G lassw are. It is the one brand o f glass that you can use fo r all types o f w o rk . Its inherent resistance to therm al shock perm its w a ll thickness adequate fo r rough h an d lin g o f every day usage. T h o ro u g h an
nealin g in tem perature-controlled lehrs assures operators o f the elim in ation o f h arm fu l strain, w ith its hazards o f breakage and in ju ry . T h e trade-m ark “ P Y R E X ” is a pled ge o f uniform quality backed by the w o rld ’ s largest m anufacturer o f technical glassw are.
“PYREX” is a trade-mark and indicates manufacture by Corning Glass Works, Corning, N. Y.
PYREX
A PRODUCT OF CORNING GLASS WORKS
8 A N A L Y T I C A L E D I T I O N
WHEN ORDERING C.P.’ s
A Section of the Control Laboratories which guarantee the high quality of Merck's C. P . ’s.
T
HE United States Pharmacopoeia protects the Pharmacist, the Physician and the Public, for a chemical cannot lawfully be labeled “U.S.P.” unless it strictly conforms to the standards of that official book.
Then there are the “Recommended Specifications for Analyti
cal Reagent Chemicals” of the Committee on Guaranteed Reagents, American Chemical Society.
What o f the chemicals you receive, however, when you order
“ C.P.” and do not specify Merck? There are no uniform official standards for C.P. chemicals corresponding to those prescribed for U.S.P. preparations or those recommended for reagents. Each manufacturer has his own standards, his own methods o f testing, and his own interpretation of tests.
Even though chemicals from two or more manufacturers may show the same purity on their labels, the actual im
purity content may vary widely due to different methods of analysis.
Merck was the first manufacturer in this country to produce laboratory chemicals conforming to definite standards, and was also the first manufacturer to publish methods o f testing them. These tests originally appeared in the 1907 edition o f Merck’s Index. With the gradual improvement in manu
facturing processes and methods o f testing, the quality stand
ards o f Merck’s Laboratory Chemicals have been correspond
ingly raised and the methods o f testing brought up to date.
If you want C.P. chemicals conforming to definite published standards and tested by definite published tests—
Do not specify “C.P.” only—specify “ C.P. M E R C K ”
MERCK & CO. Inc.
Manufacturing Chemists
RAHWAY, N. J.
March 15, 1933 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 9
DUPLICATION OF COLORS
T h is is o n e o f t h r e e H o s k in s f u r n a c e s u s e d b y t h e F er ro E n a m e l C orp. u s e d fo r c o lo r m a t c h in g o f e n a m e ls a n d fo r f u s io n t e s t s o n g r o u n d c o a t f r it s . “ F e r r o ” is n o t e d fo r t h e g o o d a n d u n if o r m q u a lit y o f t h e ir e n a m e ls , w h ic h c o m e s fr o m c lo s e p r o c e s s c o n t r o l ; t h e s e H o s k in s f u r n a c e s a re p a r t o f t h a t c o n t r o l. T h e y a re r u n fr o m 10 t o 20 h r s . a d a y a t t e m p e r a t u r e s f r o m 1200 t o 1800°
F ., u n d e r w h ic h c o n d it io n s t h e C h r o m e l-A h e a t in g
u n i t s la s t a b o u t a y e a r a n d a h a lf , a n d s o m e fo r m o r e
t h a n tw o y e a r s . T h e C h r o m e l-A u n i t is a h e lic a l c o il,
w r a p p e d a r o u n d t h e g r o o v ed m u f f le ; t h e t u r n s o f w ir e
a re c o n c e n t r a t e d , f r o n t a n d b a c k , w h ic h m a k e s fo r
g o o d u n if o r m it y o f t e m p e r a t u r e t h r u o u t t h e m u f f le .
S e n d fo r C a ta lo g 5 3 -L . H o s k in s M a n u f a c t u r in g C o .,
D e t r o it , M ic h .
10 A N A L Y T I C A L E D I T I O N
uccess or ^F ailure Ln every orop —
Stocked by leadi ng Laboratory Suppl y Houses W Æ T
H gà
ÆSP% I Bp®*
t hr ou g h o u t the U n i te d S t a t e s a n d C a n a d a .f t I M o L t G L A S S C O M P A N Y
V I N E L A N D , N E W J E R S E Y .
<p w w > N E W Y O R K • P H I L A D E L P H I A • B O S T O N • C H I C A G O • D E T R O I T
C onsider the b u re tte — a n d its im m easur
a b le im p o rta n c e to the chemist. It tells a decisive story— helps control m a in te n an c e and production costs— d eterm in es vital clinical diagnoses.
Kim ble E xax Burettes h ave e a rn e d w id e recognition fo r th e ir assured a cc u rac y and faultless p e rfo rm a n c e . T h ey a re fa b ric a te d o n ly fro m g la ss tu b in g o f th e h ig h e s t q u a lity a n d re te m p e re d in a s p e c ia lly d esig n ed K im ble a n n e a lin g fu rn a c e to assure m axim um strength. The d ia m e te r an d w a ll thickness a re e x tre m e ly uniform . The positions of g ra d u a tio n marks a re d e t e r m in e d b y e x p e r ts . A ll lin e s a n d num erals a re p la c e d b y a u to m a tic m ul
tip le m achines. T hey a re acid etched fo r p e rm a n e n c y a n d r e a d a b ility , a n d a re fille d with a b rillia n t b lu e glass e n a m e l, fused-in as a p a rt of the glass itself. Every b u re tte is inspected fo r blem ishes an d im perfections, a n d retested fo r acc u rac y.
♦ ♦ ♦
K im ble d esig n ,skill a n d p erfe ctio n a re b u ilt into e v e ry p ie c e of la b o ra to ry glassw are b e a rin g the fam ous " K " . From b ea ke rs a n d flasks to the most in tric ate o f g ra d u a te d la b o ra to ry research a p p a ra tu s , the K im ble line is c o m p lete in e ve ry d e ta il.
Used, a p p ro v e d , and s ta n d a rd iz e d upon b y the nation's outstanding la b o ra to rie s as
" A M E R I C A ' S S T A N D A R D OF A S S U R E D A C C U R A C Y "
A N A L Y T I C A L E D I T I O N
I n d u s t r i a l
V o l u m e 5 A N D E N G I N E E R I N G M a r c h 1 5 ,
num bbh 2 C h e m i s t r y 1933
Pu b l i s h e d b y t h e Am e r i c a n Ch e m i c a l So c i e t y Ha r r i s o n E . Ho w e, Ed i t o r
Analysis of Refrigeration-Grade Liquid Sulfur Dioxide
Official Method of the Sulfur Dioxide Committee, Compressed Gas M anufacturers’ Association
Introduction F. A.
Eu s t i sChairman, Sulfur Dioxide Committee, Compressed Gas Manufacturers’ Association
T
HE experience of the refrigeration industry has demonstrated that extreme refinement in the purity of liquid sulfur dioxide that is to be used as a refrigerant in auto
matic refrigeiating machines is commercially very important.
Obviously, therefore, it has become important to determine re
liably the exact degree of purity of this product, in which all impurities occur only in very minute quantities. Accuracy of analysis of from one to two parts per million is required.
The manufacturers of refrigeration-grade liquid sulfur di
oxide, wishing to avoid controversies in this matter of the purity of their products, created a special committee of chem
ists to draft a standard procedure for the analysis of liquid sulfur dioxide. The chairman of this committee was F. B.
Downing of E. I. du Pont de Nemours & Co., Inc., Wilming
ton, Del., the other members being L. S. Larsen of Ansul Chemical Co., Marinette, Wis., and A. K. Scribner of the Virginia Smelting Co., W est Norfolk, Va. The committee considered all the data that had been collected by the manu
facturers represented, and after a year’s work completed its draft of a standard method of analysis. This was submitted to the full Sulfur Dioxide Committee of the Compressed Gas Manufacturers’ Association, which was aided by a representa
tive of the Calco Chemical Co., who was not a member of the association. The report was approved with very minor changes, and then referred to the Governing Board of the Compressed Gas Manufacturers’ Association, which approved it as the tentative standard of the association.
The manufacturers regard it as the standard method to be used for all control analyses. The method is given in detail below.
Mo is t u r e
Sulfur dioxide for the refrigeration industry is usually guaranteed to contain less than 50 parts per million of mois
ture, while the actual moisture content m ay be as low as 5 parts per million in some cases. This represents from 0.0025
to 0.025 gram per pound of product (453.59 grams). The ac
curate determination of this small amount of moisture (1, 2) presents difficulties, in that the detailed technic and the ex
clusion of outside moisture must be carefully controlled to obtain correct results. The method in outline is simple;
a sample of liquid sulfur dioxide is drawn from the cylinder or drum in question and allowed to evaporate through a tared phosphorus pentoxide tube whose gain in weight is taken as the moisture content of the sample.
Under the best conditions, the experimental error is 0.0002 per cent absolute. However, samples are usually taken out- of-doors and the absolute humidity of the atmosphere has such an effect that during damp or rainy weather it is prac
tically impossible to obtain a representative sample. When the relative humidity of the atmosphere is above 50 per cent at 68° F. (20° C.) or over 3.78 grains per cubic foot, results are very apt to be higher than the actual in spite of all pre
cautions.
Re a g e n t sa n d Ap p a r a t u s. The reagents used are phosphoric anhydride (pentoxide) in powder form and 95 per cent sulfuric acid. The apparatus consists of sample transfer fittings, sample container, heat exchanger, and phosphorus pentoxide drying tubes. Auxiliary pieces of apparatus are a sulfuric acid bubbler, sulfuric acid scrubber, phosphorus pentoxide tower, and aspirator or other source of suction.
Sa m p l e Fi t t i n g s. Two types of fittings may be used. A and B, Figure 1, illustrate the first type, which is more readily avail
able for occasional use. C illustrates the second type, which is recommended for regular use. It consists of a T connecting to the drums or cylinder valve with a union and equipped with a valve on each Branch. Construct this using Prestolite Y-type valves for small cylinders.
Dry all fittings at 105° to 120° C. and use while hot. Dry the valve on the container with a blow torch or other means of heat
ing and then connect fittings A or B to this valve without passing liquid sulfur dioxide through the fitting. Finally place the moisture tube on the rubber stopper and draw the sample. The T fitting C does not require a drying of the drum or cylinder valve. Merely flush this valve and the T fitting C through one of the Y valves and finally collect the sample in the moisture tube through the other valve.
Sa m p l e Co n t a i n e r. For large samples use a half-liter suction flask with a calibration mark at the 500-cc. point; for small samples use a special cylindrical tube of 200 cc. capacity cali
brated for 100 cc. and having a tip at its base of 1 cc. capacity calibrated to 0.01 cc. at its lowestportion.
Dry the containers at 120° C. Since ordinary oven-drying leaves moisture in the air in the flask and on the surface of the
Vol. 5, No. 2 glass, final drying is by means of the preliminary run described
below. Repeated analyses may be made using the same con
tainer without cleaning between runs, provided air is excluded at all times. Sample containers that have not been used for several days should be treated as wet.
He a t Ex c h a n g e r. A preheater is placed between the sample container and the phosphorus pentoxide tubes to prevent cooling of the tared absorption tube. For 190-cc. or 500-cc. samples evaporated slowly, use 1 foot (30.48 cm.) of glass or brass tubing.
For 500-cc. samples evaporated at the maximum rate, use a 6-foot (183-cm.) helix. The tubing need not be larger than 5 mm. inside diameter.
irussre srofffe
The preheater is oven-dried and then finally dried in the pre- liminarv run. Keep it closed when not in use by means of glass or wooden plugs.
Dr y i n g Tu b e s. Two types of drying tube may be used: the Fleming phosphorus pentoxide absorption jar (No. 3890 in A. H. Thomas catalog), or a 4-inch (10-cm.) Swartz U-tube. The Fleming jar is better adapted to 500-cc. samples because of the greater number of runs that may be made before refilling. The Swartz tube is better adapted to 100-cc. samples and throughout its life is free from channeling and has low resistance to flow of gas.
Pack the Fleming jar with a mixture prepared by shaking two parts by volume of powdered phosphorus pentoxide with one part of Gooch asbestos fiber which has been dried at 140° C. This mixture is light, porous, and has long life with minimum tendency to channel. Pack the reagent loosely in the jar on a 0.25-inch (0.6-cm.) layer of glass wool. Prepare a second phosphorus pentoxide tube like the first and place it in the absorption train. All moisture is collected in the first tube. Any change in the second tube is therefore used, with a change of sign, as a cor
rection on the weight of the first tube. A correction for tem
perature, barometric pressure, and surface moisture is thus ob
tained automatically.
Pack the Swartz tube with glass beads coated with phosphorus pentoxide. Use beads of not more than 0.125-incn (0.3-cm.) diameter and allow them to stand in the open air for a few hours so that the moisture on the glass surfaces is in equilibrium with the air. Then place them in a stoppered bottle and add finely pow
dered phospnorus pentoxide in portions with shaking until the sur
faces have taken up all that will stick to them. Fill the Swartz tube with these beads, using a plug of glass wool at each end.
Prepare a duplicate tube without phosphorus pentoxide to be used as a counterpoise. Weigh this tube, whether of Fleming or Swartz type, open to the air so that it is at the prevailing baro
metric pressure. On tests that are only run an hour, brass weights have been found to be satisfactory.
The moisture in refrigeration-grade sulfur dioxide is quantita
tively removed by one phosphorus pentoxide absorption tube.
Au x i l i a r y Ap p a r a t u s. For the purpose of judging the rate of evolution of the sulfur dioxide, a sulfuric acid bubbler may be placed at the end of the train. A 15-cc. pipet cut off just below the bulb and immersed in 15 cc. of concentrated sulfuric acid in a rubber-stoppered bottle makes a safe bubbler.
The Swartz tube may be weighed after sweeping with dry air if desired. To accomplish this, sweep the tube for 3 minutes with 2 liters of air per minute. Set up a train as follows: A sulfuric acid scrubber, a phosphorus pentoxide tower, the Sw'artz tube, and then a manometer connected to an aspirator or other source of suction.
Sa m p l i n g. Tw o sizes of samples may be used: the 500-cc.
sample for the most accurate work, such as for 2000-lb. drums and settlement of disputes, and the 100-cc. sample for local control work and for the analysis of small cylinders when there is no dis
agreement. But, because of the possibilities of a larger experi
mental error in the case of small samples, particularly in times of high humidity, rejections should be made only on the basis of 500-cc. samples.
Flush and carefully dry the drum or cylinder valve and attach the dry fitting A or B. If fitting C is used, connect it directly to the drum valve and flush both drum valve and fitting through one valve of the T. Draw the sample directly from the original drum or cylinder into the especially prepared sample container used for the analysis.
The use of a small cylinder to transfer material from the original container to the laboratory is not permissible.
Pr e p a r a t i o n o f Ap p a r a t u s. Before s t a r t in g the actual determinations, equilibrate the appara
tus by collecting a full-size sample of r e fr ig e r a - tion-grade sulfur dioxide (using the sampling con
nections and dried container), and evaporating it through the assembled absorption train. This is n e c e ssa r y to complete the drying of the sample container, to remove all air from the phosphorus pentoxide tubes, and to dry tubing connections.
In tr a n sfe r r in g the sample container from the c y lin d e r or drum to the a p p a r a tu s , k eep it stoppered but vented through a Bunsen valve.
At the end of the preliminary run, immediately close all stopcocks, beginning nearest the sample container, and then disconnect the absorption train.
After disconnecting the sample container and the preheater tubing, close both securely.
Weigh the absorption tubes preparatory to the moisture determination. The Fleming jars must be weighed filled with sulfur dioxide. The Swartz tubes may be weighed filled with sulfur d io x id e or they may be swept with air. If this is desired, sweep for 3 minutes with phosphorus pentoxide-dried air at the rate of 2 liters per minute and weigh. When weighing the absorption tubes, use a duplicate counterpoise having one end open to the
Fi g u r e 2 . Ap p a r a t u s f o r De t e r m i n a t i o n o f No n c o n d e n- s a b l e Ga s e s i n Li q u i d Su l f u r Di o x i d e
E. Leveling bu lb F - • •
OJl.
K . A . 100-co. &a3 b u re t
B. 3-w ay stopcock
C. C up for a d d itio n of p o tassium hydroxide
D. C o n n ectio n fo r su lfu r dioxide inlet
R u b b er tu b e Pinchcocks
O pen ends of ru b b e r tu b in g G lass sig h t tu b e
air. Also weigh the second Fleming jar used as a compensating tube. Equalize the pressure within all analytical phosphorus pentoxide tubes with the prevailing atmospheric pressure before closing them for weighing.
Pr o c e d u r e. Reassemble the absorption train. Collect the sample directly in the sample container, observing all the pre
cautions given above, and immediately transfer it to the labora
tory and connect it to the absorption train.
Regulate the rate of evaporation of the sulfur dioxide by cau-
March 15, 1933
tiously using a bath of lukewarm water. Allow at least 45 minutes for the evaporation of 100-cc. samples, and at least 1.5 hours for 500-cc. samples, when using the Swartz U-tubes. The Fleming jar requires 45 minutes for 100-cc. samples and at least 4 hours for 500-cc. samples. The rate of evaporation is limited by the back pressure of the absorption train and the danger of blowing out stoppers.
At the close of the evaporation, shut off the stopcocks in the same manner as at the end of the preliminary run and weigh the tubes, using the tare tube as counterpoise.
100 AI „
— r- - % m o istu re 1.46 X cc. sam ple
Where 1.46 is the specific gravity of sulfur dioxide at its boiling point at atmospheric pressure, M is the gain in weight of the first phosphorus pentoxide tube less the increase or plus the de
crease in the second or compensating phosphorus pentoxide tube.
Re s i d u e Te s t
The residue left by the evaporation of refrigeration-grade sulfur dioxide is too small for a quantitative determination to be practicable. Hence, it is determined microscopically and compared with a standard.
Pr o c e d u r e. Use a 200-cc. cylindrical sample container having a 1-cc. tip which at its lowest portion is graduated to 0.01 cc.
Clean this container with cleaning solution, rinse with distilled water, and dry at 120° C. The glass surface should be bright and free of all film. Wipe the cylinder valve and flush. Draw a 100- cc. sample without using any sample connection. Stopper the container either with rubber stopper and Bunsen valve or with a plug of cotton wool. Evaporate to dryness and compare with standard.
Su l f u r i c Ac i d
After evaporation of the sulfur dioxide and careful removal of all sulfur dioxide vapor, as shown by iodine test, the sulfuric acid is titrated with 0.01 N caustic.
Pr o c e d u r e. Use a 125-cc. Erlenmeyer flask, with a calibra
tion mark at the 100-cc. point. Clean with chromic acid cleaning solution, wash out thoroughly, and dry at 120° C. Evaporate a 100-cc. sample, using a plug of cotton wool to stopper the flask.
After the evaporation, remove sulfur dioxide vapor by connecting a Gooch crucible adapter to suction and applying the rubber end to the flask, then breaking the connection. Repeat fifteen times until no odor of sulfur dioxide remains and a drop of 0.01 iV iodine added to the flask is not decolorized. Prepare water for the titration by adding 2 drops of methyl red and adjusting by means of either 0.01 N sodium hydroxide or 0.01 Ar hydrochloric acid to the exact neutral point. Add 25 cc. of this wrater to the flask and titrate with 0.01 N sodium hydroxide.
cc. X A ' X 0.0490-4 X 100 „ „ cc. of SO, X 1 .4 6--- “ % H iS 0 '
No n c o n d e n s a b l e Ga s e s
The 100-cc. sample of sulfur dioxide gas is collected in a 100-cc. gas buret and potassium hydroxide added. The re
sidual gas is read as noncondensable gases.
The results for small amounts of noncondensable gases are read directly to 0.02 per cent and may be estimated to 0.005 per cent.
Re a g e n t. 30 per cent potassium hydroxide solution.
Ap p a r a t u s. The buret is similar to Eimer and Amend, No.
28940, except that it is of 100 cc. capacity and the upper tip is graduated in 0.02 cc. down to the 0.2-cc. mark.
Pr o c e d u r e. With pinchcock II closed, open the cock between A and C, and raise the mercury leveling bottle until the mercury just comes into the cup C. Close the stopcock B, leaving a small globule of mercury in the cup.
Place the cylinder containing the liquid sulfur dioxide on its side so that the ramshom of the lower valve is in the liquid phase.
Connect the apparatus as shown in the diagram. With the spring pinchcock G open, the cylinder valve is cautiously opened until liquid sulfur dioxide runs out at the tube and I. (Some analysts find it more convenient to substitute the use of one foot for pinch
cock G.) The pinchcock H is now opened, the buret stopcock turned into the position shown in the diagram, and the pinchcock G and the cylinder valve closed. When the liquid sulfur dioxide has vaporized as indicated by the globule of mercury, the cylinder valve is opened to allow liquid s ill fur dioxide to escape into the tubing only as fast as it will vaporize.
Allow the gas to sweep out the air in the apparatus, which should be accomplished in 2 or 3 minutes. With pinchcock G closed, quickly turn stopcock B so that it is open between the cylinder and the buret A, lower the leveling bulb and fill the buret with sulfur dioxide gas. Close pinchcock H and open pinchcock G. Turn stopcock B so that it is open between A and C and rim this buret full of gas to waste througn cup C, as it is used only to treat with any small amount of potassium hydroxide left from a previous determination. Refill the buret in the same manner as before with exactly 100 cc. of sulfur dioxide under at
mospheric pressure. Close pinchcock H and turn stopcock into the position shown in the diagram. Add through cup C about 15 to 20 cc. of the potassium hydroxide solution, being careful to exclude all air. After the contraction has ceased, bring the level of the mercury in the bulb to that in the buret and read the volume of residual gas.
cc. of resid u al gas “ % noncondensable gases in liq u id phase
Li t e r a t u r e Ci t e d
(1) Flenner, A. L., and Caverly, W. R ., Refrigerating Eng., 21, N o.
5, 344 (1931).
(2) Scribner, A. K ., Ind. Eng. Chem., Anal. E d.. 3, 255 (1931).
R e c e i v e d N ovem ber 3 , 1 9 3 2 .
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
Note on Washing the Potassium Cobaltinitrite Precipitate
W. E.
T h r u n ,Valparaiso University, Valparaiso, Ind.
T
HE precipitate of potassium cobaltinitrite obtained in micromethods (1~4) for determining potassium becomes increasingly flocculent upon washing with water. It is therefore usually washed in centrifuge tubes by si
phoning. It was found that when the precipitate is washed with a dilute solution of aluminum sulfate (1 per cent) it will be much less flocculent, so that it can be washed by the usual method of drainage after inversion. Three washings with 3 cc. of solution are usually sufficient. If the super
natant liquid from the second washing is not nearly colorless, a fourth washing should be performed.
It was also found that more consistent results can be ob
tained when the precipitate is to be titrated indirectly with solutions of permanganate or eerie sulfate if, upon addition
of sulfuric acid and the oxidizing agent, the precipitate is thoroughly stirred for a while when the tube containing the reacting substances is placed in boiling water. Because of the instability of nitrous acid (1), eerie sulfate should be a better oxidizing agent for this purpose than permanganate, as it furnishes a positive ion to oxidize a negative ion.
Li t e r a t u r e Ci t e d
(1) Jacobs and Hoffman, J . Biol. Chem., 93, 680 (1931).
(2) K ram er and Tisdall, Ibid., 46, 339 (1921).
(3) Leulier, Velluz, and Griffon, B ui. soc. chim. biol., 10, 1238 (1928).
(4) Tischer, Biochem. Z., 238, 148 (1931).
Re c e i v e d Aujcust 11, 1932.
Quantitative Determination of Small Amounts of Hydrocyanic Acid
Na t h a n Ga l e s a n d An d r e w
J.
Pe n s aChemical Laboratory of the Bureau of Food and Drugs, Department of Health, New York,
N .Y.
T
HE most commonly used methods (1) for the determination of hydrocyanic acid have the objection that they are not quantitative for very small amounts.
The method outlined below affords a means by simple technic of determining hydrocyanic acid quantitatively in exceedingly small amounts, the delicacy being measured by the amount of ammonia which can be determined by Nessler’s reagent—namely, one part in one hundred million.
Hydrocyanic acid, known also as formonitrile, is subject to the general characteristic reactions of alkyl nitriles—
namely, hydrolysis with either alkali or acid to form the alkyl acids or their salts and ammonia or its salts. These reactions, where 11 is the alkyl group, are:
R O N + HC1 + 2H 20 — >- R C O O II + NILC1 R C N + K O H + 2HjO — >- RCO OK + N H ,O H and for hydrocyanic acid:
HCN + HC1 + 2H ,0 — >- HCOOH + N il, Cl HCN + KOII + 2H20 — >- HCOOK + NH(OH It is evident from the above reactions that the hydrolysis of hydrocyanic acid must be carried out in a closed system;
for hydrocyanic acid would be volatilized with acid hydrolysis, and ammonia with alkali hydrolysis.
In the industrial manufacture (4) of ammonia and formates a mixture of cyanides (KCN + NaCN) is autoclaved with 5 to 10 parts of water for 20 to 30 minutes between 180° and 190° C. In a series of laboratory experiments samples con
taining standard aqueous potassium cyanide solutions equiva
lent to 0.01, 0.10, and 1.0 mg. of hydrocyanic acid were autoclaved for 30 minutes between 180° and 190° C. and when Nesslerized checked with equivalent ammonium chlo
ride solutions. The hydrolysis of the potassium cyanide solu
tion is due to the alkaline reaction of this salt. This method has two disadvantages, the caustic action on the glass auto
clave and high temperature. The optimum conditions for hydrolysis, as experimentally deduced, were obtained by autoclaving for 30 minutes between 140° and 150° C. in an acid solution.
The glass autoclave is the Leiboff urea apparatus (S) for the determination of urea in blood. This apparatus is essen
tially a brass stand with a thermometer in the hollow of the rod and a circular brass plate containing six grooves from which are suspended the six glass autoclaves. The stand with the suspended autoclaves is set in an oil bath. The glass autoclave, of approximately 35 cc. capacity, is made gas-tight by a ground-glass rod which seals at the neck when the rod is so suspended. Lacking the Leiboff urea apparatus, satisfactory results could be obtained with ordinary medicinal ampoules.
Pr o c e d u r e
D istil the hydrocyanic acid in the usual manner from a solution acidified with tartaric acid and collect the distillate into 10 cc. of 0 .1 N sodium hydroxide. Transfer the distillate, approximately 25 cc., to the autoclave and add 5 cc. concen
trated c. p. hydrochloric acid. Heat slowly in the oil bath
and maintain the temperature between 140° and 150° C, for 30 minutes. After cooling, empty and rinse with dis
tilled water into a 50-cc. beaker. Evaporate slowly on a hot plate almost to dryness to get rid of the excess acid. Dilute with distilled water, transfer to a Nessler tube, and add 5 cc.
of Nessler’s reagent (2). Compare the resulting color with a series of standard ammonium chloride solutions and calculate the parts per million of the cyanide or hydrocyanic acid present in the sample. When the ampoule is used as the autoclave, cool in an ice bath before the addition of the hydrochloric acid and then immediately seal the ampoule.
Ex p e r i m e n t a l Da t a
Solutions containing 1, 2, 3, 4, and 5 cc. of concentrated c. p. hydrochloric acid, 5 cc. of standard potassium cyanide solution (1 cc. equivalent to 0.1 mg. of hydrocyanic acid), and 20 cc. of distilled water were autoclaved for 30 minutes between 140° and 150° C. Hydrolysis was not complete when 1, 2, and 3 cc. of acid were used, whereas 4 and 5 cc.
of acid showed complete hydrolysis and the ammonia evolved checked quantitatively with equivalent standard ammonium chloride solutions.
Autoclaving 5 cc. of standard potassium cyanide solutions with 5 cc. of concentrated c. p. hydrochloric acid and 20 cc.
of water at 100° and 105° C. for 30 minutes showed that the liberation of ammonia was not quantitative, although more was formed at the higher temperature. Complete hydrolysis was obtained between 140° and 150° C. when autoclaved for 30 minutes.
Solutions containing 5 cc. of standard potassium cyanide, 5 cc. of concentrated c. p. hydrochloric acid, and 10 cc. of 0.1 N sodium hydroxide were autoclaved for 30 minutes between 140° and 150° C. Some of these solutions were Nesslerized directly with 5 cc. of Nessler’s reagent, but the acidity was too great for the development of the characteris
tic brownish yellow color. In the others, the excess acid was neutralized with sodium hydroxide before Nesslerization, In these cases a turbidity formed due to impurities in the alkali, such as magnesium, calcium, and aluminum. How
ever, when the excess acid was evaporated and the solution then diluted and Nesslerized, the resulting color was clear and checked quantitatively with ammonium chloride standards.
For 5 cc. of the Nessler’s reagent, the acid content of the solution must not exceed 0.4 cc. of concentrated hydrochloric acid.
Samples containing 5 ,1 0 , 15, 20, and 25 cc. of the standard potassium cyanide solutions were autoclaved in the usual manner with 5 cc. of concentrated c. p. hydrochloric acid and 10 cc. of 0.1 N sodium hydroxide. Upon subsequent re
moval of excess acid and Nesslerization, the characteristic brownish yellow color developed and ranged from a clear light comparable color to the brownish yellow precipitate of the iodide of Millon base, N H j HgO H gl. It is necessary, therefore, when the solution to be Nesslerized contains am
monia derived from more than 0.5 mg. of hydrocyanic acid, to take an aliquot portion for colorimetric comparison.
80
March 15, 1933 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 81 A one-gram sample of powder collected from a copper coil
of a gas heater contained, as determined by this method, a cyanide equivalent to 75 parts per million hydrocyanic acid.
This sample proved to be interesting, for Nesslerization re
sulted in a turbid solution which proved to be due to iron carbonyl, which, present in the original sample, distilled over with the hydrocyanic acid. The iron carbonyl was precipi
tated as iron hydroxide by boiling the alkali solution contain
ing the carbonyl and the cyanide. The filtrate was auto- claved in the usual manner, and when Nesslerized a clear solution resulted.
Ac k n o w l e d g m e n t
The writers express their appreciation to Reginald Miller for his cooperation in this work.
Li t e r a t u r e Ci t e d
(1) A utcnreith, W ., "L ab o rato ry M anual for the D etection of P oi
sons and Powerful D rugs,” 6th American edition, B lakiston, 1928.
(2) Folin, 0 ., “ L aboratory M anual of Biological C hem istry,” A p
pleton, 1923.
(3) LeibofT, S. L „ and K ahn, B. S., J. Biol. Chem., 83, 347-52 (1929).
(4) M ange, L., Industrie Chimique, 5, 286-8 (1918).
Re c e i v e d N ovem ber 23, 1932.
Determination of Dextrin, Maltose, and Dextrose in Corn Sirup
W. R.
Fe t z e r,J. W.
Ev a n s, a n dJ. B.
Lo n g e n e c k e r,Union Starch and Refining Company, Granite City, 111.
C
ORN sirup (glucose, or“glue” as it is called col
loquially by the candy manufacturer) has become an indispensable part of the manu
facture of confectionery. One billion one hundred forty million pounds were refined in 1929, with a value of 34 million dollars. It is produced by the acid hydroyl- sis of corn starch under a pres
sure of approximately 40 pounds, in three different purities—low, regular, and high. “Purity” is defined within the industry as the amount of reducing sugars ex
pressed as dextrose, on a dry substance basis. The “regular”
purity of 43 to 44 forms the bulk of the commercial production.
Corn sirup is a thick, colorless solution of the three carbo
hydrates—dextrin, maltose, and dextrose. The gravity of the sirup will run from 41° to 46° 136. (1° B6. being expressed at 100° F .). Sirups with a gravity of 41° and 42° B6. are more often called “mixing sirups,” and are used by manufac
turers of mixed table sirups. Confectioners’ sirup runs from 43° to 46° B6., the bulk being sold at 43° B6., as this gravity represents the high practical limit at which this heavy, vis
cous sirup may be handled economically.
Although there are m any published analyses for corn sirups or starch hydrolytic products, few are applicable to the com
mercial product, because the sirups used for analysis have been prepared by boiling starch in open vessels, with acids different from those used in the commercial process. Further, most workers employ a low concentration of starch suspension, whereas in the industry it is customary to use a suspension from 22° to 26° B6., the latter figure representing the practical limit for pumping suspended starch. It is well known in the industry that the maximum purity attainable in manufacture is affected by the concentration of the starch suspension used, and it is reasonable to assume that the ratio of the various carbohydrate constituents might be altered by these same concentration differences of the starch.
Many methods have been proposed for the analysis of com sirup. All make use of several algebraic equations obtained from laboratory determinations, such as specific rotation, re
ducing power before and after acid inversion, etc. Almost all employ the solids equation obtained from the moisture de
yin addition in procedure is applied to the method of moisture determination by distillation with toluene, as proposed by Biduiell and Sterling and modified by Rice, to make it applicable to corn sirup. A new method fo r the direct deter
mination of dextrin in corn sirup is proposed.
Based on the method of direct determination of dextrin, a procedure for the complete analysis of corn sirup is presented, which allows two check equations—p u rity and specific rotation. A n aly
ses of several brands of confectioners’ corn sirup are made.
termination. The methods may be roughly grouped as follows:
1.
2.
A lg e b r a ic solution from s o lid s , specific rotation, and reducing sugar equa
tions.
Precipitation of the dextrin by alcohol and solution by algebraic equations.
Fermentation methods.
Destruction of the sugars, followed by polariscopic d e te r m in a tio n of the d e x tr in , and then alge
braic solution.
Algebraic solution for three car
bohydrates requires three equa
tions, and the following are easily available in the laboratory:
® + y + z = 196a: + 138.5.y + 52.7z = 1.1111® + 1.0555ÿ + z =
0.606y + z = solids
specific rotation
reducing sugars as dextrose after acid hydrolysis
purity or reducing sugars as dex
trose on original sirup
It would seem, since dextrin has no reducing power, as shown by the last equation, that the solution for the three carbo
hydrates would be simple, but the experience of the present authors and that of others U ) has been that small experi
mental errors are enormously multiplied, so that the final results, even in simple mixtures such as corn sirup, can be regarded only as approximate.
Recognition of this difficulty has stimulated other investi
gators to the direct determination of dextrin by precipitation by alcohol or a similar chemical, in which dextrin is insoluble but maltose and dextrose are soluble. Keener (5) stated that the precipitation of dextrin by alcohol was a most promising method but that it required further study. Experience in this laboratory has been that precipitation by alcohol is not only a disagreeable determination from an analytical stand
point, but that it also gives unreliable results, as shown in Table I.
Ta b l e I. Da t a o n Pr e c i p i t a t i o n o p De x t r i n b y Al c o h o l W eig h t corn sirup, gram s
W a te r in corn sirup, ml.
W a te r a d d ed , ml.
9 5 % alcohol ad d ed , ml.
F in a l alcohol (calcd.), % D ex trin found, %
5 .0 5 .0 5 .0 5 .0 5 .0
0 .9 0 .9 0 .9 0 .9 0 .9
9 .1 2 0 .1 3 1 .1 4 1 .1 5 2 .1
190 179 168 158 147
90 85 80 75 70
1 9 .8 13 .9 8 .0 4 .0 1 .4
