IN D U S T R IA L andENGINEERING C H E M IS T R Y
Vol. 30, Consecutive No. 27
ANALYTICAL EDITION
20,200 Copies of This Issue Printed
July 15, 1938
H a r r iso n E. H o w e , E d ito r
Vol. 10, No. 7
An a l y s i s o p Ca r a m e l Co l o r...W . R . F e t z e r 3 4 9
Co u n t i n g Dr o p s w i t h Ph o t o e l e c t r i c Re l a y . . . . ... G e o r g e W . J o s t e n 3 5 3
Su l f u r i c Ac i d An a l y s i s o f Ga s e o u s Ol e f i n s . . . . ... M a r y a n P . M a t u s z a k 3 5 4
Vo l a t i l i z i n g Ch r o m i u m a s Ch r o m y l Ch l o r i d e . . . ...F r e d W i l s o n S m i t l i 3 6 0
De t e r m i n a t i o n o f Ac e t a l d e h y d e i n Wi n e s...
... M . A . J o s l y n a n d C . L. C o m a r 3 6 4 Co m p l e t e Re m o v a lo f Fe r r i c Ch l o r i d ef r o m So l u t i o n
b y Co n t i n u o u s Ex t r a c t i o n w i t h Et h e r ...
... S . E . Q . A s h l e y a n d W . M . M u r r a y , J r . 3 6 7
De t e r m i n i n g Co r r o s i o n Re s i s t a n c e o f Ti n Pl a t e ... V . W . V a u r i o , B . S . C l a r k , a n d R . H . L u e c k 3 6 8
Re l a t i o n b e t w e e n Vo l a t i l e Ma t t e r a n d Hy d r o g e n- Ca r b o n Ra t io o f Co a l a n d Ba n d e d Co n s t i t u e n t s
... C . H . F i s h e r 3 7 4
De t e c t i o n o f Co b a l t, Co p p e r, a n d Fe r r o t j s Ir o nw i t h 2 - Ni t r o s o- 1 - Na p h t h o i^ 4 - Su l f o n i c Ac i d...
... L . A . S a r v e r 3 7 S
Im p r o v e d Ku r t Me y e r Ti t r a t i o n...
...S . R . C o o p e r a n d R . P . B a r n e s 3 7 9
Sy s t e m a t i c Sc h e m e o f Id e n t i f i c a t i o n o f Al k a l o i d s . ... K i r b y E . J a c k s o n 3 8 0
Co r r e l a t i o n o f Me t h o d s f o r Me a s u r i n g He a t o f Hy d r a t i o n o f Ce m e n t...
... R . W . C a r l s o n a n d L . R . F o r b r i c h 3 8 2
Se p a r a t i o n o f Ch r y s a n t h e m u m Ca r b o x y l i c Ac i d s . . ... A t h a n A . P a n t s i o s 3 8 6
E v a l u a t i o n o f C o m m e r c i a l A r s e n i o u s O x i d e b y T i t r a t i o n w i t h I o d i n e ...Paul Lundman
C h e m i c a l D e t e r m i n a t i o n o f Q u a r t z ( F r e e S i l i c a ) i n D u s t s . . . Emanuel Kaplan and W. Thurber Fales
De t e r m i n a t i o n o f Fo r m s o f Su l f u r i n In s o l u b l e Re s i d u e s f r o m Hy d r o g e n a t e d Co a l...
R. F. Abernethy, H. M. Cooper, and E. C. Tarpley
D e t e r m i n a t i o n o f S m a l l Q u a n t i t i e s o f M e t h y l B r o m i d e i n A i r . . R . L. Busbey and N. L. Drake
M o d i f i c a t i o n o f t h e M a r k l e y M e l t i n g P o i n t A p p a r a t u s . . . Milton S. Schechter and H. L. Haller
Gr a v i m e t r i c De t e r m i n a t i o n o f Zin c b y Me r c u r i c T h i o c y a n a t e M e t h o d ...W. C . Vosburgh, Gerald Cooper, William J. Clayton, and Harry Pfann
Mo i s t u r e De t e r m i n a t i o n . Charles W. Griffiths
R e d u c t i o n o f S e l e n i o u s A c i d b y T h i o c y a n i c A c i d . .
...William T . Hall
B a l a n c e d C i r c u i t f o r E l e c t r o m e t r i c T i t r a t i o n . . ...E a r l B . Working
Si m p l i f i e d Pr e c i s i o n Oil Ma n o m e t e r...
. . . ...T. C. Chadwick and S. Palkin
Im p r o v e d Tr a p f o r Mo i s t u r e De t e r m i n a t i o n b y Di s t i l l a t i o n...
...Earle E. Langeland and Richard W. P ratt
Ea s i l y Co n s t r u c t e d Or i f i c e...
... Chester P. Baker and William A. McGrath
Mo d e r n La b o r a t o r i e s:
M i c r o c h e m i c a l L a b o r a t o r y o f t h e B i o c h e m i c a l R e s e a r c h F o u n d a t i o n o f F r a n k l i n I n s t i t u t e . .
... Herbert K. Alber and J. Harand 387
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393 394
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403
The American C hem ical Society assum es no responsibility for the statem ents and opinions advanced by contributors to its publications.
P u b lic a tio n OiHce: E a sto n , P a .
K tlitoriul O ffice: R o o m 706, M ills B u ild in g , W a sh in g to n , D . C. A d v ertisin g D ep a rtm en t-. 332 W est 12„d S t r e e t. N ew Y ork . N . Y.
T e le p h o n e : N a tio n a l 0848. C ab le: J ie c h e m (W a sh in g to n ) T elep h o n e s Ilry a n t 9 -U 3 0
Published bv the American Chemical Society, Publication Office, 20th &
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4 INDUSTRIAL AND ENGINEERING CHEMISTRY
Hr
Heat with Hotcone
N o m ore d an g e ro u s flam es, w av erin g a n d b low n o u t flam es, flam es t h a t h e a t th e la b o ra to ry m ore th a n th e o b je c t to be h e a te d —no m o re w aste, risk a n d u n r e lia b ility —w h en th e C enco H o tc o n e ta k e s o v e r la b o ra to r y h e a tin g .
T h e H o tc o n e e lectric h e a tin g ele
m e n t, w hose ch ro m el u n it is w o u n d in a lu n d u m c e m e n t in th e form o f a cone, a n d b e tte r h e a t in su la tio n th a n a n y o th e r h e a te r ev er m a d e m ean s
SPECIFICATIONS
m o re th a n 9 0 % a c tu a l en erg y effi
ciency. A p o lish ed a lu m in u m case m ean s s tre n g th , lig h tn ess a n d fine a p p e a ra n c e . C o n c e n tric sillim an ite rings giving a p e rtu re s from l l/ i to 3 inches a c c o m m o d a te a n y la b o ra to r y vessel.
N o th in g in th e w hole field o f h e a t ing a p p lia n c e s does th e excellent w o rk o f th e H o tc o n e H e a te r for e v a p o ra tio n s, d igestions, ex tra c tio n s, boiling o r d istilla tio n s.
D ia m e te r o f to p , 5 l/ i inches.
H e ig h t o f to p fro m ta b le , inches.
L e n g th o f a lu m in u m ro d , 12 inches.
D ia m e te r o f sm a lle st h e a te r o p en in g , 1}4, inches.
D is ta n c e fro m c e n te r o f o p en in g to ro d , 4 ^ inches.
W a tta g e c o n su m p tio n , 250 w a tts .
PRICES
16500A F o r 110 v o lts 16500B F o r 220 v o lts
$ 6 .5 0 7 .0 0
C H IC A G O 1 700 Irving Pk. Blvd.
Lakeview Station
S C I E N T I F I C
INSTRUMENTS SKI L A B O R A T O R Y A P P A R A T U S
B O S T O N 79 Amherst St.
Cambridge A Station
New York • Boston • C H IC A G O • Toronto • Los Angeles
JULY 15, 1938 ANALYTICAL EDITION
KIMBLE <s> BRAND
jf a t (¡¡¿¿¿M im c e
WEIGHING BOTTLES
W IT H OU TSID E G R O U N D C A PS
(CATALOG No. 15146)
^ e a tu ^ m a S AdwsMtaCf&i
& oe/uf> G U en tiU W om M !
¿gfc The cap protects the top of the bottle from breakage when the bottle is tipped over.
Material within the bottle does not come into contact with any ground surface.
Elimination of penny head top removes one source of breakage.
Bottle and stopper are so designed that an air tight joint is assured.
Increased head room provided by the stopper decreases danger of fluffy material being sucked
out when Stopper is removed.
No chance of contamination of contents from dirt, such as occurs with the old style bottle.
Bottles and stoppers have large, plainly visible corresponding serial numbers.
Every bottle has a small sandblasted area suitable for pencil inscriptions.
A VA ILA B LE SIZES
Diam. (mm) 15 15 25 25 30 40 40
Height of Body (mmj 50 80 40 50 60 50 80
FOR DETAILS on p rices and p a ck a ges, con sult any reputable Laboratory S u pply D ealer in the U n ited States or C anada.
# » *
The Visible G u a r a n t e e of I n v i s i b l e Q u a l i t y
» * »KIMBLE GLASS COM PANY v i n e l a n d , n . j .
N E W Y O R K • • C H I C A G O • • P H I L A D E L P H I A • • D E T R O I T • • B O S T O N
6 INDUSTRIAL AND ENGINEERING CHEMISTRY
TY PE S A AND B
W EBER ELECTRIC DRYING OVENS
W I T H IM P R O V E D T Y P E H E A T IN G U N IT S A N D IN A N E W S T A IN L E S S S T E E L A N D P O L IS H E D A L U M I N U M E X E C U T IO N
Type A W eber Electric Drying Oven Type B W eber Electric Drying Oven
IMPROVED T Y P E HEA TIN G UNIT
An improved type heating unit, which has been used experimentally for over two years, is now incorporated in all Weber Electric Drying Ovens. This unit consists of a loosely coiled nickel chromium resistance wire mounted in a moulded Carborundum tube. As a refractory, the latter is an excellent conductor of heat and retains a minimum of latent heat. The elements are free to expand and contract and are completely protected.
STAINLESS STEEL AND POLISHED A L U M I N U M C O N S T R U C T I O N
The walls, both inside and outside, are now made of Stainless steel instead of Monel metal as formerly; the front casting and the door frame, previously made of dull finished cast aluminum, are now made of brightly polished alu
minum. Both changes greatly improve the appearance.
INCREASED U N I F O R M I T Y OF TEM PE R AT UR E D I S T R I B U T I O N
Tests conducted in our laboratory indicate that the combination of new heating units, their placement to permit even flow of convection currents, and the interior construction result in greater uniformity in temperature dis
tribution throughout the working space than has been obtainable heretofore.
D I RE C T S E T T I N G CE NT IG RA DE SCALE
A feature of the Weber Electric Drying Oven is the Centigrade scale with pointer for setting directly at approxi
mately the desired temperature within the range of the oven selected. This temperature is maintained automatically.
7805. W eber Electric Drying Oven, Type A, as above described, with inside dim ensions 10 X 10 X 10 inches. W ith tw o shelves, providing 160 square inches of working shelf space, b u t w ith out glass door. For operation to 150°C; with heating units wound for 400 watts.
W ith thermom eter, 200°C , and cord and plug for attach m en t to lam p socket. For use on 110 volts a .c ... 75.00 Code W ord... Lucfn 7807. W eber Electric Drying Oven, Type B, as above described, w ith inside dim ensions 12 X 12 X 12 inches. W ith three shelves, providing
324 square inches of working shelf space, and double pane Pyrex glass door, perm itting convenient observation of the whole interior without loss of temperature uniform ity. For operation to 150°C; with heating units wound for 500 w atts. W ith thermom eter, 200°C , and cord and plug for attach m en t to lam p socket. For use on 110 volts a.c... 100.00 Code W ord... Ludaw 7809. D itto, Type BH T , identical with T ype B b u t for operation to 260°C ; with heating units wound for 1000 w atts. M u st be connected directly to a line of sufficient capacity. For use on 110 volts, a .c ; ...150.00 Code W ord... Ludot
Copy o f p a m p h le t EE-106, Sivina detailed description o f above Ovens, w ith listing o f larger sizes, Vacuum Ovens, etc., and results o f laboratory tests, se n t upon request.
ARTHUR H. T H O M A S CO M PANY
R E T A I L— W H O LE SA LE —E X P O R T
LA B O R A TO R Y APPARATUS A ND REAGENTS
W EST W A SH IN G TO N SQUARE P H IL A D E L P H IA , U.S.A.
C able A ddress, “ B a la n c e ,” P h ilad elp h ia
INDUSTRIAL ENGINEERING CHEMISTRY
ANAt l g l l CAL EDITION ♦ H a r r iso n E. H o w e , E d itor
Analysis of Caramel Color
\V. R. FETZER Union S larch an d Refining
S ix te e n m illio n p o u n d s o f c a r a m e l co lo r—
b u r n t su g a r c o lo r in g — a rc p r o d u c e d a n n u a lly in t h e U n i le d S la t e s for u s e in t h e b ev e r a g e , fo o d , a n d p h a r m a c e u t ic a l i n d u s tr ie s. N o u n if o r m m e t h o d s fo r t h e a n a ly s is o f c a r a m e l co lo r h a v e ever b e e n p u b lis h e d , a n d t h e a u t h o r p r e s e n ts th is p a p er o n a n a ly t ic a l p r o c e d u r e w h ic h w ill e v a lu a te a c a r a m e l c o lo r n o t o n ly for ty p e b u t a lso fo r q u a lit y .
C
ARAMEL color, or burnt sugar coloring, is used extensively in carbonated beverages, distilled liquors, wines, pharmaceuticals, extracts, bakery products, candy, soups, and baked beans. Figures on the amount manufactured are not available, as m any concerns make their own coloring.
According to the 1929 census of the D epartm ent of Commerce, fifty-three establishments were producing 1,450,000 gallons of caramel. More recent comparable data are not available but it is believed th a t there are fewer producers of caramel today. The 1935 census gives a production of 1,550,000 gallons and an estimate of production today would be in excess of 1,600,000 gallons. This increase is attributable to increase in am ount of carbonated beverages consumed.
Very little has been published about either the manufac
turing or testing of caramel color. Probably the best article is th a t of Salamon and Goldie, published in 1900 (é¡). These authors presented data on its manufacture, and their tests in modified form are largely in use today. Brewers’ caramel has received more attention than caramel for carbonated beverages, although the latter requires a caramel of more specialized characteristics.
The manufacture, with few exceptions, is carried on by
“burners” who employ rule-of-thumb methods, so th a t there is considerable variation in the finished product. There are many methods of evaluating caramel, each manufacturer having his own tests for standardization of his product.
Consumers, for the most part, are comparatively small users who do not test the caramel, b u t once they have a satisfactory source of supply will change only under the most unusual circumstances. Large users of caramel, with well-equipped laboratories, have their own tests, peculiar to their product.
Their experience with various makes of caramel, in many in
stances, has been as unsatisfactory as th a t of the small user, so th a t they are equally conservative with regard to changing their source of supply.
Com pany, G ranile City, III.
The trouble with caramel color is probably due to the fact th a t the conditions which a caramel m ust meet in specialized uses, such as carbonated beverages and pharmaceuticals, involve several characteristics which are equally im portant.
Too often one is overemphasized or overlooked.
The laboratory has offered little aid to the user who would resort to a chemical analysis. Probably the greatest difficulty lies in the multitude of methods in use, with the consequent lack of uniformity in evaluation by different laboratories.
In addition, most laboratory analyses are not sufficiently comprehensive to cover caramel in general, b u t are built around a specific use. Even the simple test of tinctorial or coloring power of a caramel varies between laboratories, be
cause of failure to follow' a uniform method of measurement.
This paper is presented in the interests of a standardized procedure for the analysis of caramel color. The tests in
clude not only those th a t have been developed in the author's laboratory but those of consumers and manufacturers, modified in some instances to fit the usual laboratory practice and to obtain a more general application. The tests given will evaluate a caramel both as to quality and type.
C a r a m e l T y p e s
Caramel is used in a w'ide range of products and is manu
factured in a number of types, each designed for a specific purpose. These include types for carbonated beverage m anu
facturers (including acidproof, nonacidproof, and foaming), brewers, distillers, bakers, and confectioners. Carbonated beverages, extracts, and distilled liquors require the highest quality of caramel. Caramel satisfactory for bakery and ice cream use may be entirely unsuitable for beverage use.
True beer caramels cannot be used for carbonated beverages, although they serve satisfactorily in the bakery, in ice cream, and in candy. Carbonated beverage caramels, as a rule, cannot be used for hard candy because of their high acid content, which would cause inversion in the candy.
Various types of caramel may be used in carbonated bev
erages. Thus, ginger ales and cola beverages require an acid- fast and tannin-resistant caramel. Root beer and cream soda do not require an acid-fast caramel, b u t one with good tannin resistance. If the root beer is a true root extract, the tannin requirements are greater than if synthetic flavors are used.
However, an acid-fast caramel with high tannin resistance can be used in all carbonated beverages. Thus, any con
sideration of caramel quality m ust take into consideration' the service to which the caramel is put. Although an ap
parently poor caramel m ay give the best of service in an iso
lated instance, it is far safer to demand a high laboratory 319
rating, or a caramel designed for exacting service, than to use a lower quality, where the margin of safety may be so small th a t a slight alteration in ingredients m ay cause precipitation of the caramel.
A n a ly s is o f C a r a m e l
Laboratory testing of caramel is based on a series of tests under specified conditions which bear a relationship to actual conditions. This series of tests will readily differentiate caramel as to grade and quality, b u t the individual m ust determine the grade suitable to his product and the variations in quality th a t his product can stand. This includes a con
sideration of shelf life. Thus, a cola or ginger ale dispensed a t fountains and immediately consumed does not require the same acid-fastness in a caramel as the same beverage when bottled, where the shelf life may be over three months.
The following solutions are used in the tests:
A. Caramel Solution, 1 per cent. Dissolve 10.000 grams of caramel color in distilled water and make to 1 liter.
B. Acid Tannin Solution. Dissolve 0.1 gram of tannic acid
U . S. P. and 15 grams of citric acid U. S. P. in 100 ml. of distilled water. Refilter until clear. This solution deteriorates rapidly and must be prepared daily.
C. Tannic Acid Solution. Dissolve 1 gram of tannic acid U. S. P. in 100 ml. of distilled water. Refilter until clear. Make up solution daily.
D. Alcohol Tannin. Dissolve 0.5 gram of tannic acid U. S. P.
in 100 ml. of 50 per cent alcohol by volume.
E. Alcohol Solution, 50 per cent by volume.
F. Alcohol Solution, 55 per cent by volume.
G. Alcohol Solution, 60 per cent by volume.
H. Alcohol Solution, 65 per cent by volume.
For recording observations, the following notations may be employed:
A. Brilliant at end of 24. hours.
B. Slight haze at end of 24 hours.
C. Slight precipitate at end of 24 hours.
D. Medium precipitate at end of 24 hours.
E. Heavy precipitate at end of 24 hours.
F. Immediate precipitate, in case of acid test during the boiling period.
The 1 per cent stock caramel solution should be examined by transmitted and reflected light, recording observations as (1) brilliant, (2) hazy, or (3) opalescent.
After filtering through a 15-cm. (6-inch) filter paper, observa
tions are recorded as (1) clean, (2) suspended matter, or (3) char.
G e n e r a l T e s ts
S p e c i f i c G r a v i t y . The specific gravity of commercial caramels varies widely, ranging from 34° to 42° B6., with an average of approximately 38.0° B6. A uniform gravity is especially im portant in carbonated beverage caramels, be
cause when large quantities of caramel are used, as in root beer concentrate, variations in Baum6 of the caramel m il affect the final gravity of the concentrate.
High gravities generally result from the burner’s failure to produce the necessary am ount of color in the burning process.
Thus, in adding water to “b u rn t” mass, he cuts back to the desired tinctorial power, without regard for gravity. Such caramels drain with difficulty and very slowly from the con
tainers. Low gravities are generally the result of an attem pt to obtain a freer flowing caramel. W ith a lower gravity, more color m ust be produced in the burning process, so th a t such a caramel m ust be examined carefully for overburning with resultant failure in quality.
Immerse a hydrometer standardized at 15.56° C. (60° F.) in air-free caramel at 15.56° C. (60° F.) and obtain the reading.
If a temperature correction is necessary, employ the arbitrary correction of 2.2224° C. (4° F.) equals 0.1° Bi.
When the sample of caramel is small, particularly if the gravity is high or the viscosity great, it is best to use a Hubbard-Carmick specific gravity bottle, which is designed primarily for asphalt.
T i n c t o r i a l P o w e r . Probably no other p a rt of a caramel analysis has varied more than the measurement of tinctorial powrer. As defined by Salamon and Goldie (£>), the tinctorial power is the Lovibond reading obtained on a caramel solution, made by dissolving 1 gram of color in 1 liter of distilled water, in a 2.5-cm. (1-inch) cell. The trouble may generally be attributed to three causes:
Standard Glasses. The usual Lovibond glasses employed in the measurement of caramel color are the Caramel Series No.
52. These slides were designed for the measurement of color in beer (4) and may or may not match the color produced by com
mercial caramel color. As a rule, beer caramels match very well;
distillers’ caramels do not, as they contain more red than the No.
52 series. The carbonated beverage caramels lie between. In reading a distillers’ or carbonated beverage caramel with No. 52 slides only, the tendency is to employ too many slides in order to secure a match, resulting in too high a tinctorial power. This can be overcome by adding 0.1 to 0.4 red to the No. 52 series.
Light Source. The original Lovibond light for standardization was that reflected from a fog bank by the early morning sun across the meadow from the Lovibond brewery. This is a soft diffused light and may be matched for purposes of standardization by picking a time when similar light conditions exist. The source in the laboratory is the electric light, and the common tendency of chemists is to employ too much light, resulting in readings that are too low. A good source can be obtained by passing the light of a 50-watt lamp through a daylight glass against white crepe filter paper at a 45° angle from the Lovibond cells. Once a source of light has been established, it should be adhered to.
Cells. The definition of tinctorial power calls for measurement in a 2.5-cm. (1-inch) cell. Many laboratories do not have an inch cell, but do possess 0.63- and 1.25-cm. (0.25- and 0.5-inch) cells. In the latter case, the reading on a 0.1 per cent solution is multiplied by two, or the reading on a 0.2 per cent solution is made and called the tinctorial power. This leads to erroneous results, as the Lovibond reading under these conditions is not proportional for all caramel colors and may vary as much as 10 per cent from results obtained by a reading on a 2.5-cm.
(l-inch) cell.
The British Drug House modification of the Lovibond tintometer is an improvement over the older form. Car
bonated beverage caramels require the addition of the red
Fi g u r e 1. Du b o s c q Ty p e o p Ti n t o m e t e r
JULY 15, 1938 ANALYTICAL EDITION 351 series (200) in addition to the No. 52 Caramel Series and it is
advisable to introduce about 0.2 red a t the start, adding the caramel slides until an approximate m atch has been obtained, after which the effect of an additional 0.1 red on the m atch may be studied.
Other types of tintometers are in use. Figure 1 shows a Duboscq type in which a fixed glass standard is used. The degree of variation is measured on the drum, according to the degree of immersion of the plunger above or below the depth of definite solution, matching the glass standard, which is given the arbitrary rating of 100. Figure 2 shows a newer modification of the Duboscq. Lovibond slides are contained in the m etal disks as follows:
Caramel Series 52 30 20 15 10
9 .0 8 .0 7 .0 6 .0 5 .0 4 .0 3 .0 2 .0 1 .0 0 .9 0 . 8 0 .7 0 .6 0 .5 0 .4 0 .3 0 .2 0 .1 Red Series 200 0 .9 0 .8 0 .7 0 .6 0 .5 0 .4 0 .3 0 .2 0 .1
This comparator has the advantage th a t the maximum num
ber of slides which can be used is four, which is desirable with the Lovibond system. In addition, the amount of light passing through the caramel may be altered by the reflector, thus compensating for the brilliance often found in some caramels and also for the differences in light absorption by different combinations of slides. This may also be done in the British Drug House tintom eter by the addition of neutral slides, b u t it has been the author’s experience th a t the em
ployment of these neutral tints complicates rather than aids the matching.
To determine the tinctorial power, dilute 50.0 ml. of stock caramel solution A to 500 ml., and read the color in a 2.5-cm.
(1-inch) cell, using Lovibond glasses Series 52. Add 0.1 to 0.4 red if necessary to secure an exact match.
pH. The pH of a caramel gives an index of its quality and m ay be measured by either glass or quinhydrone elec
trodes. The readings by the former are usually slightly lower. If the quinhydrone electrode is employed, an exces
sive am ount of quinhydrone m ust be used to prevent drifting and the gold electrode m ust be kept clean. An undiluted caramel with a pH higher than 6.0 will mold. High pH also indicates an incomplete “burn” or excessive amounts of al
kali, both of which mean th a t the caramel will increase in tinctorial powrer on aging. Caramels have been examined with pH as high as 9.
Carbonated beverage caramels, undiluted, should run from 2.5 to 3.3 (glass electrode). Caramels with pH less than 2.5 are likely to resinify, and have been known to become rubberlike or even turn to a solid within two months.
The pH of a 15 per cent solution, intended primarily for beer caramels, should run from 4.5 to 5.0 under these condi
tions, comparable to the fermentation pH. Caramels which give higher or lower pH under these conditions when added to the fermenting w ort are said to alter the pH sufficiently to change the flavor of the resulting beer.
The pH of 1 per cent solution in a carbonated beverage caramel should run approximately 3.5. pH lower than 3.3 indicates a caramel w ith excessive residual acidity.
Obtain the pH of a caramel by means of a glass or quinhydrone electrode.
To determine the pH of a 15 per cent solution proceed in the same way on a solution of caramel made by dissolving 15 grams of caramel and making to 100 ml.
To determine the pH of a 1 per cent solution, take 5 ml. of the above solution, add 70 ml. of distilled water, mix thoroughly, and obtain the pH.
V i s c o s i t y . Relative viscosity is im portant with reference to the speed with which a caramel resinifies or ages. Cara
mels with excessive relative viscosity are usually overburnt and lack acid-fastness.
The relative viscosity can easily be determined by using a 50-ml. Mohr buret, filling with caramel a t a definite tem
perature—i. e., 29.44° C. (85° F.)— and collecting 40 ml. in a graduated cylinder.
A s h . The ash normally bears no relationship to quality.
However, in recent years the hydrol from refined corn-sugar processing has been used for caramel, which increases the ash content, depending upon the am ount used, to as high as 8 per cent. Caramels with an ash content greater than 3 per cent, if intended for use in carbonated beverages, should be examined closely for the effect of ash on flavor.
Fi g u r e 2 . Mo d i f i c a t i o n o f Du b o s c q Ti n t o m e t e r
I r o n . Iron in a caramel will often run to excessive limits, entering through the burning equipment, which is often made of mild steel. Only a few manufacturers employ glass-lined or stainless steel equipment because of the cost involved.
Samples of caramel have been examined which have contained 2000 p. p. m. of iron. The effect of this iron on the flavor of a pharmaceutical extract or carbonated beverage can well be imagined.
The ash is dissolved in acid and the iron content measured colorimetrically (1).
S p e c ific T e s t s fo r C a r b o n a te d B e v e r a g e , P h a r m a c e u t ic a l, a n d D is t ille r s ’ C a r a m e l
A c i d T e s t . This test, which is particularly im portant in caramel color used in cola and ginger ale beverages, has been found adequate by an old manufacturer in evaluating caramel color.
Dilute 50.0 ml. of stock caramel solution A to 250 ml. with distilled water, add 7 ml. of concentrated hydrochloric acid (sp. gr. 1.18), cap, and boil gently for 5 minutes. Remove from flame and note whether precipitation has developed. Set aside and record observation 24 hours later.
If the color is satisfactory, a measure of residual acid-fastness may be obtained by repeating the above test, boiling for 30 minutes instead of 5 minutes. Water must be added at intervals to maintain a constant volume.
INDUSTRIAL AND ENGINEERING CHEMISTRY
To 10 ml. of color add 20 ml. of distilled water, mix thoroughly, add 0.5 gram of compressed yeast, and stir until completely suspended.
Pour into a fermentation tube and invert for 15 minutes or until all the air has been elimi
nated. Place tube in posit ion, plug with cotton, and set aside for 48 hours at 26.67° to_ 32.22° C.
(80° to 90° F.). Record the percentage volume of gas produced.
F o a m T e s t . Caramels for carbonated beverage use are of foaming and nonfoaming types. The former are used for root beer and the latter for cola and ginger ale beverages. Foaming caramels are used in
“mug” root beer, where a large stein is drawn, containing a large head of foam. Caramels can be burnt to have foaming qualities, elimi
nating an}' necessity for the addition of saponin or other similar foaming agents.
Under the test outlined below, a caramel designed for cola or ginger ale will give a head of foam lasting from 3 to 6 minutes, with bubbles th a t are large and break quickly. A foaming caramel will give a head of fine bubbles lasting from 30 minutes to 2 hours.
Dissolve 10 grams of caramel in distilled water, make to 100 ml., run into a 250-ml.
glass-stoppered cylinder, and shake for 2 minutes.
Loosen the stopper and place in a water bath at 37.78° C. (100° F.). Observe the time for the head of foam to fall to the liquor surface.
Fi g u r e 3 . Ac id Te s t f o r Ca r b o n a t e d Be v e r a g e Ca r a m e l s
N e u t r a l T a n n i n T e s t . These tests are a measure of caramel’s resistance to flocculation by extractives th a t occur in the various carbonated beverages and pharmaceutical extracts.
1. To 80 ml. of distilled water add 10 ml. of stock caramel solution A, then 10 ml. of stock tannin acid solution C, and mix thoroughly. If clear, set aside for 24 hours and record observa
tions.
2. To 50 ml. of distilled water add 25 ml. of caramel solution, and then 25 ml. of tannic acid solution, and mix thoroughly.
If clear, set aside for 24 hours and record observations.
3. To 13 ml. of caramel solution, add 12 ml. of tannic acid solution, and mix thoroughly. If clear, set aside for 24 hours and record observations.
A c i d - T a n n i n T e s t . This is a combined acid and tannin test.
To 75 ml. of acidulated tannic acid solution B, add 5 ml. of stock caramel solution A and 20 ml. of distilled water, and mix thor
oughly. If clear, record observations at end of 24 hours.
A l c o h o l T e s t s . Dissolve 1 gram of caramel in 100 ml. each of 50, 55, 60, and 65 per cent alcohol by volume. Mix thoroughly and record observations at end of 24 hours.
W h i s k y T e s t . Color 50 ml. of test solution D a distinct brown (the color of a 0.2 per cent solution) and observe 24 hours later.
F e r m e n t a t i o n T e s t . Some beverage manufacturers de
pend upon the residual acidity of a caramel color to preserve their extracts. The residual.acids in a caramel are a combina
tion of those resulting from the catalyst used—i. e., ammo
nium sulfate—and those produced in the burning process—i. e., acetic acid. Titratable acidity data obtained on different makes of caramel are not comparable, since the methods of burning and catalysts used differ. For this reason, pH data are better. As a rule, a pH of a t least 3.0 is required to assure no fermentation, b u t this cannot be taken as a final criterion, as there is considerable variation in the buffering power of caramels, depending on the type of catalyst employed and the method of burning. A measure of the effectiveness of the residual acidity is the fermentation test.
C o m p a t i b i l i t y . One of the most serious difficulties in the use of caramel for carbonated beverages occurs when caramel is added to a sirup or extract already containing caramel, or where two makes of caramel are used in the same plant. The weaker or inferior caramel will often precipitate out.
Filler Paper Test. Run 1 or 2 ml. of a 0.2 per cent solution of caramel onto a large sheet of filter paper. The color from a satisfactory caramel will follow' the water. The color from an inferior caramel will collect in a spot in the center, and the water will proceed to form a larger circular area. Such a caramel is invariably noncompatible.
Solution Test. Dilute 50 ml. of solution A of each caramel to 250 ml. and proceed as follows:
Caramel A, ml.
Caramel B, ml.
D istilled water, ml.
T a b l e I. P h y s i c a l E x a m i n a t i o n Solution
R etained on filter paper Baumé
T inctorial power Acid test, 5 m inutes , Acid test, 30 m inutes N eutral tan nin 1 N eutral tannin 2 N eutral tannin 3 Acid tannin Alcohol, 50%
Alcohol, 55%
Alcohol, 60%
W hisky teat Foam test, minutes Hops test, % Ferm entation test C om patibility:
Filter paper test Solution test pH
pH , 15%
pH , 1%
V iscosity, 29.44° C. (85° F .):
water = 1 Iron, p. p. m.
° Too thick to measure.
Brilliant Brilliant H azy
Clean Clean Clean
3 8 .1 ° 3 9 .1 ° 3 7 .5 °
2 2 .1 19 .5 2 1 .0
A A F
D E F
A A A
A A A
A B F
A A E
A A A
A B C
B E F
A A B
7 6 20
100 100 100
N one N one Trace
OK OK OK
OK OK OK
3 .0 2 .9 3 .3
3 .0 2 .9 3 .3
3 .5 3 .6 3 .7
20. a 65.
< 1 0 . 3 0 . 230.
JULY 15, 1938 ANALYTICAL EDITION 353
Fi g u r e 4 . Sh i p p i n g Fl o o r o f Ca r a m e l De p a r t m e n t
Pour into oil sample bottles, pasteurize, and seal. Set aside for 24 hours and record observations.
T e s t s S p e c ific fo r B r e w e r s’ C a r a m e l
The requirements for a caramel in beer are entirely different from those for a carbonated beverage, pharmaceutical, or distillers’ caramel. Brewers’ caramels are sometimes burnt from m alt sirup and designated m alt caramels; more often they are burnt from mixtures of m alt and corn-sugar sirup.
Excellent brewers’ caramels may be burnt entirely from corn sugar, with the proper burning formula, and add only color to the beer. Those from m alt contribute flavor in addition.
The pH of the caramel, particularly after dilution, is im portant {2, S, 4, 6). The caramel m ust not fade or bleach when boiled with hops and it m ust be chill-proof—i. e., there m ust be no sedimentation or fading when the beer is chilled, either in brewery storage or previous to its consumption.
H o p s T e s t . Rim 200.0 ml. of the stock caramel solution into a 500-ml. flask, add 1.0 gram of dried hops (pale green in color), cover the flask with a small beaker, and boil gently for 15 min
utes. Cool and filter through a Gooch crucible or Hirsch funnel, prepared with a layer of asbestos, over which is a layer of Filter- Cel. Wash and make the filtrate to 1 liter. Compare with a control made from 50.0 ml. of the stock caramel solution diluted with distilled water to 250.0 ml.
Record the percentage of the color remaining after boiling with hops, employing the respective Lovibond readings to de
termine the loss, if any.
C h i l l - P r o o f T e s t . Chill two bottles of beer, to which color is to be added, from 0° to 4° C. (32° to 39° F.) by means of an ice bath. For control purposes, remove the crown cap from one and immediately recap. Remove the crown cap from the other bottle, add 1 gram of color, and recap. Agitate the beer until the caramel is dissolved. Place both bottles in an ice bath or refrigerator for 24 hours and examine for appearance of haze or sediment. Usually 24 hours will suffice for this test.
S u m m a r y
To illustrate the type of d ata obtained by this procedure, three typical analyses of commercial caramel colors sold for carbonated beverages are given in Table I.
L ite r a tu r e C ite d
(1) Assoc. Official Agr. Chem ., Official and T en tativ e M ethods, 4 th ed., p. 516 (1935).
(2) R rian t, Lawrence, J . In st. Brewing, 18, 673 (1912).
(3) D egbom ont, A., A n n . zj/mol., [2] 1, 327-39 (1934).
(4) F aw cett, G. S., J . Soc. Chem. In d ., 1936, 81.
(5) H arm an , H . W ., and Oliver, J. H ., J . In st. Brewing, 31, 577 (1925).
(6) Salam on, A. G., and Goldie, E . L „ J . Soc. Chem. In d ., 19, 301 (1900).
Re c e i v e d June 18, 1937. Presented before the D ivision of Sugar C hem is
try at th e 92nd M eeting of the American Chemical Society, Pittsburgh, Pa., Septem ber 7 to 11, 1936.
C ounting D rops with the P h otoelectric R elay
GEORGE W. JOSTEN
Pasadena J u n io r College, Pasadena, Calif.
T
H E photoelectric relay may be used to count drops of transparent liquids. By suitable regulation of the cross section of the light beam used, drops forming in the beam will reflect and refract sufficient light to act like opaque objects.This will cause the photoelectric cell to produce electrical impulses which may be used to count the number of drops for an interval of time or to regulate the rate of dropping.
In the apparatus used by the author, the beam of light is modified by vertical slits 0.5 cm. wide by 1 cm. long. The beam runs horizontally across the source of drops and directly to the photoelectric cell, being interrupted as the drop forms and returning to normal after it has fallen. W ith the po
tentiometer set a t 226° and an electric relay counter operating on 18.6 volts direct current, it was found possible to count drops up to 478 per minute. Faster counts are difficult be
cause of the tendency of the drops to lose their identity and form a continuous stream.
Drops m ay be enclosed by transparent material, so th a t they are neither mechanically damaged nor chemically con
taminated.
R e c e i v e d March 26, 1938.
Sulfuric Acid Analysis of Gaseous Olefins
MARYAN P. MATUSZAK, P hillips Petroleum Com pany, Bartlesville, Okla.
P r in c ip le s a n d lim it a t io n s g o v e r n in g t h e s e le c t io n o f c o n d it io n s fo r d e t e r m in a t io n o f g a s e o u s o le fin s b y a b s o r p tio n in s u lf u r ic a c id a r e p r e s e n te d b r ie fly . D a ta in d ic a t in g t h e in f lu e n c e o f t h e fo llo w in g p r e v io u sly u n in v e s t ig a t e d fa c to r s u p o n a n a ly t ic a l r e s u lt s a re g iv e n : (1) r e v e r s ib ility o f a b so r p t io n ; (2) s o lu b ilit y o f g a s e o u s p a r a ffin s in s u lf u r ic a c id ; (3) in c r e a s e in s o lu b ilit y o f h y d r o c a r b o n s b e c a u s e o f a c id - s o lu b le a b
s o r p tio n p r o d u c t s ; (4) s o lu b ilit y o f h y d r o c a r b o n s i n p r e c ip ita t e d p o ly m e r p r o d u c ts ; a n d (5) lib e r a t io n o f u n a b s o r b a b le g a s b y o v e r str o n g a b s o r b e n ts , in c lu d in g t h o s e c o n t a in in g silv e r s u lf a t e . S u it a b le a p p a r a tu s a n d t e c h n ic fo r o v e r c o m in g t h e s e e ffe c ts a re d e sc r ib e d . W it h in i t s n a t u r a l l i m i t s o f a p p lic a b ility , t h e im p r o v e d m e t h o d g iv e s, fo r s a m p le s o f a ll p o s s ib le o le fin c o n c e n t r a t io n s , r a p id a n d r e lia b le r e s u lt s .
S
Y STEM ATIC selection of analytical conditions in accordance with the principles and the limitations discussed in this paper makes the determination of gaseous olefins by absorption in sulfuric acid quantitatively accurate.P r in c ip le s
R e l a t i v e R a t e s o f A b s o r p t i o n . Figure 1, based pri
marily on the work of Dobryanski (6), who made the first of several recent studies of the absorption of gaseous olefins by sulfuric acid {2, 3, 6, 11), indicates the relationship between acid concentration and rate of absorption. Dobryanski passed all of a 100-cc. sample of olefin from a gas buret into a cylindrical absorption pipet having no contact tubes. After perm itting the acid on the pipet wall to drain for 5 to 10 minutes, he returned about 50 cc. to the buret. Then, after closing a special stopcock in the U-connection leading to the acid-expansion chamber, thereby preventing disturbance of the acid surface, which had a constant area of about 19.9 sq.
cm., he followed the absorption by direct buret readings.
For each particular combination of unsaturated gas and acid
concentration, the rate of absorption was constant. The observed constant rates of absorption are plotted against acid concentration in Figure 1.
Dobryanski recommended 63 to 64 per cent sulfuric acid for absorbing isobutylene; 83 to 84 per cent acid for propylene, butadiene, and n-butenes; and 100 to 102 per cent acid for ethylene. Figure 1 indicates th a t 63 to 64 per cent acid absorbs isobutylene about 500 times as readily as propylene, and th a t 83 to 84 per cent acid absorbs propylene about 500 times as readily as ethylene. Contact of a gas sample successively with acid of these strengths thus removes in turn isobutylene, propylene, and ethylene.
n-Butenes are absorbed together with propylene because their rate of absorption averages only about twice th a t of pro
pylene {5,6, 11). Separation can be effected readily by a preliminary fractional distillation into three-carbon and four- carbon fractions which then are analyzed separately by sul
furic acid absorption.
The diolefin butadiene, if present, is absorbed, for the most part, with the n-butenes. Its presence is indicated qualita
tively by an intense yellow c o lo r a tio n of th e a c id . Allene appears to be ab
sorbed a t a rate similar to th a t for butadiene (8).
If five-carbon vapors are present, isoprene and ter
tiary amylenes (trimethyl ethylene and unsymmet- rical methyl ethyl ethyl
ene) are absorbed with iso
butylene; n-amylenes (pen- tene-1 and pentene-2) and isopropyl ethylene are ab
sorbed with propylene and n-butenes {4, 10). For separation from propylene and butylenes, fractional distillation and dilution with an inert gas, followed by sulfuric acid absorp
tion, can be used (4).
L o g a r i t h m i c V a r i a t i o n o f A b s o r p t i o n R a t e w i t h A c i d C o n c e n t r a t i o n .
Since the rate of absorp
tion, as is indicated by the straight curves of Fig
ure 1, increases logarith- metically with .increase in 354
