INDUSTRIAL a n d ENGINEERING CHEMISTRY
A N ALYTICA L EDITION
H A R R IS O N E. H OW E, E D I T O R « IS S U ED N O V E M B E R 15, 1940 » V O L . 12, NO. 11 « C O N S E C U T I V E NO. 22
R e c o m m e n d e d S p e c i f i c a t i o n s f o r A n a l y t i c a l R e a g e n t C h e m i c a l s... W. D . Collins et al. 6 3 1 Sp e c t r o p h o t o m e t r i c De t e r m i n a t i o n o f Vi t a m i n A . .
D . T. Ewing, J. M. Vandenbelt, A. D . Em m ett, and 0 . D . Bird 639
S p e c t r o g r a p h i c C h a r a c t e r i s t i c s o f V i t a m i n A M a t e r i a l s ... Ronald L. McFarlan,
Philip K. Bates, and Edward C. Merrill 645
Me a s u r e m e n t o f Gl o s s...
L. A. Wetlaufer and W. E. Scott 647
D e t e c t i o n a n d E s t i m a t i o n o f D i h y d r o r o t e n o n e i n Hy d r o g e n a t i o n Pr o d u c t s o f Ro t e n o n e...
Lyle D . Goodhue and H. L. Haller 652
P r e p a r a t i o n o f S t a b l e S o d i u m T h i o s u l f a t e S o l u t i o n s . . . James L. Kassner and Esther E. Kassner 655
POLAROGRAPHIC M ETH O D FOR LE A D AND ZlNC IN P A IN T S
B. M. Abraham and R. S. Huffman 656
Ef f e c t o f Se l e n i u m o n Kj e l d a h l Di g e s t i o n . . . .
R. B. Bradstreet 657
M e t h y l E s t e r s o f H i g h e r F a t t y A c i d s ...
Flavius W. W yman and Chas. Barkenbus 658
D e t e r m i n a t i o n o f C a r b o n M o n o x i d e . . . Fred Cook 6 6 1 St u d i e s o f Or g a n i c Re a g e n t s a n d Me t h o d s In v o l v
i n g Th e i r Us e ...
John F. Flagg and N . Howell Furman 663
Co l o r i m e t r i c De t e r m i n a t i o n o f Ph o s p h a t e . . . .
S. R. Dickman and R. H. Bray 665
R a p i d D e t e r m i n a t i o n o f H y d r o g e n S u l f i d e a n d M e r c a p t a n S u l f u r i n G a s e s a n d i n A q u e o u s S o l u t i o n s... Joseph A . Shaw 6 6 8 R e d u c t i o n M e t h o d f o r E v a l u a t i o n o f T i t a n i u m
D i o x i d e . .Herm an Skolnik and Wallace M . M cNabb 6 7 2 M o d i f i e d J o n e s R e d u c t o r ... J . E . Edwards 6 7 3 D e t e r m i n a t i o n o f S m a l l A m o u n t s o f B e r y l l i u m i n
S i l i c a t e s... E. B . Sandell 674
Po t a s s i u m- So d i u m Co b a l t i n i t r i t e Pr e c i p i t a t e . . .
R ex J. Robinson and James D . Hausehildt 676
Si m p l i f i e d Di s t i n c t n e s s-o f- Im a g e Gl o s s m e t e r . . .
Robert J. Myers 678
Pr e c i s i o n Fe e d De v i c e f o r Ca t a l y t i c Ex p e r i m e n t s .
Robert L. Burwell, Jr. 681
As p i r a t i n g Un i t f o r Co l l e c t i n g Ai r Sa m p l e s . . . .
Leslie Silverman and W esley B. Wardlow 682
El e c t r i c a l l y He a t e d Ro t a r y Ki l n ...
E. P. Barrett, W. L. Barrett, and P. R. Porath 684
Po r t a b l e Lo w- Pr e s s u r e Ga s Ta n k s...
G. Ro ssRobertson 6 8 6
C a p i l l a r y F l o w m e t e r... Hubert N . Alyea 6 8 6
Mi c r o c h e m i s t r y :
De t e r m i n a t i o n o f Sm a l l Am o u n t s o f Po t a s s i u m
Bernard Klein and Mendel Jacobi 687
Mo d i f i c a t i o n s i n Co m b u s t i o n Mi c r o m e t h o d f o r Ca r b o n a n d Hy d r o g e n...
G. L. Royer, A. R. Norton, and 0 . E. Sundberg 6 8 8
Co l o r i m e t r i c Mi c r o d e t e r m i n a t i o n o f Ar s e n i c . .
Albert L. Chaney and Harold J. Magnuson 691
R e m o v a l o f S t a t i c C h a r g e s f r o m G l a s s w a r e b y U l t r a v i o l e t L i g h t... Clement J. Rodden 693
G e n e r a t o r f o r P r o d u c t i o n o f P u r e C a r b o n D i o x i d e... W. H . Rauscher 694
De t e r m i n a t i o n o f Co p p e r i n Mi n e r a l Oi l s . . . .
A. G. Assaf and W. C. Hollibaugh 695
L o c a l i z a t i o n o f C e r t a i n C h e m i c a l C o n s t i t u e n t s i n P l a n t a n d A n i m a l T i s s u e s . Herman Yagoda 698
Py r e x Al l- Gl a s s Mi c r o e l e c t r o p h o r e s i s Ce l l . .
D avid R. Briggs 703
Mi c r o h y d r o g e n a t i o n Ap p a r a t u s... ...
Arthur N . Prater and A. J. Haagen-Smit 705
Mo d e r n La b o r a t o r i e s:
Bu r e a u o f Mi n e s Me t a l l u r g i c a l La b o r a t o r i e s . .
R. S. Dean 708
T h e A m erican C h em ical S o ciety assum es n o re s p o n sib ility fo r th e s ta te m e n ts a n d op in io n s a d v an c e d b y c o n trib u to rs to its p u b lic a tio n s.
23,000 copies of th is issue p rin te d . C o p y rig h t 1940 b y A m e ric a n C h em ical Sooiety.
P u b l i c a t i o n O f f ic e : E d i t o r i a l O f f ic 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 e c h e m ( W a s h i n g t o n )
P u b lish e d b y th e A m e ric a n C hem ical Society, P u b lic a tio n Office, 2 0 th &
N o rth a m p to n S ts., E a s to n , P e n n a . E n te re d as second-class m a tte r a t th e P o s t Office a t E a s to n , P e n n a ., u n d e r th e A c t of M arch 3, 1879, as 24 tim e s a y e a r . I n d u s tr ia l E d itio n m o n th ly on th e 1 st; A n a ly tic al E d itio n m o n th ly o n th e 15 th . A c ce p ta n c e fo r m ailin g a t sp ecial r a te of p o stag e p ro v id e d for in S e c tio n 1103, A ct of O c to b er 3, 1917, a u th o riz e d J u ly 13, 1918.
A n n u a l s u b sc rip tio n ra te , In d u s t r i a l Ed i t i o n an d An a l y t i c a l Ed i t i o n
sold o n ly as a u n it, $4.00. F o re ig n p o sta g e to c o u n tries n o t in th e P a n
E a s t o n , P e n n a .
A d v e r t i s i n g D e p a r t m e n t : 3 32 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
A m erican U n io n , $2.25; C a n a d ia n po stag e, $0.75. Single copies: I n d u s tria l E d itio n , $0.75; A n a ly tic a l E d itio n , $0.50. Special ra te s to m em bers.
N o claim s c an be allow ed fo r copies of jo u rn a ls lo s t in th e m ails unless su ch claim s a re receiv ed w ith in 00 d a y s of th e d a te of issue, a n d n o claim s w ill be allow ed fo r issues lo st as a re s u lt of insu fficien t n o tic e of ch an g e of a d d ress. (T en d a y s ' a d v an c e n o tic e re q u ire d .) “ M issin g fro m files"
c a n n o t be acc e p te d as th e re a so n fo r h o n o rin g a claim . C h arle s L . P a rso n s, B usiness M an a g e r, M ills B u ild in g , W ash in g to n , D . C ., U . S. A.
4 IN D U S T R IA L A N D E N G IN E E R IN G C H E M IST R Y VOL. 12, N O . 11
FINE CHEMICALS
L A B O R A T O R Y . R E A G E N T S y
•V V
T H E P A C E I N C H E M I C A L P U R I T Y S I N C E 1 8 8 2 *7? */-
B a k e r & A d a m so n
N e w Y o r k D i v i s i o n o f G E N E R A L C H E M I C A L C O M P A N Y , 4 0 R e c t o r St.
S a le * O f f i c e s : A l l a n t , . B a ltim o r e . B o sto n . B u ffa lo . C h ^ o t t e <N. C l • C h ic a g o i> .“ R K a m a « C ity • M ilw a u k e e . M in n e a p o lis . M o n tezu m a (Q a .) . N e w a rk (N . J . ) • N ew Y o r k • I lilla c lc lp m a l t u u u r m
P ro v id e n c e (R . I .) • S t. L o u is • L t i c a (N . i . )
P a c i f i c C o a st S a le s O f f i c e s : S a n F r a n c is c o . L os A n g e le s* P a c i f i c N o rth w e s t S a le s O f f i c e s : W e n a tc h e e (W a s h .) • Y a k im a ( W a s h .;
I n C a n a d a : T h e N ic h o ls C h em ical C om pany, L im ite d . M o n tre a l . T o ro n to . V ancouver
A N A LY T IC A L E D IT IO N 5
SIEVE
SHAKER
Schematic Diagram of E ssential Parts A— Center of mass of sieves
B—Center of mass of loading weight C— Center of gravity of complete as
sembly
D —Upper rotating eccentric mass E— Loading weight
F— Lower rotating eccentric mass G— R idge on platform
H— Sieve-holding bail
S— Helical springs supporting platform
SIEVE SHAKER, Cenco-M einzer, for rapid separation of powdered materials by machine sieving into their various size components. A wide variety of materials from heavy mineral powders to light organic or pharmaceutical powders can be sieved with equal facility. The reproducibility of results for quantitative separations is very high. I t can, therefore, be used in mechanical analysis of industrial materials, wherever machine sieving is permissible. The sieve platform accommodates 8-inch sieves.
Sim plicity of operation is secured through its unusually simple design and construction. As the mechanical power developed by the motor is transmitted directly to the sieves w ithout loss, a motor of only Vis hp is required to do the equivalent of a y i hp motor in shakers utilizing other principles. The device is self- balancing, since the entire moving system is practically a free system , executing its motions about its own center of gravity. The need for weighting to secure stability w ith castings of considerable mass is elimi
nated. As a result of these design features, the weight is within the range of easy portability.
The effectiveness of the Cenco-Meinzer Shaker is excellently demonstrated by the results of a test run with a mixture of finely ground quartz and iron oxide, constituting a material called ore-pulp. This mixture is very difficult to separate because of its tendency to blind the sieves. U sing a 100-gram sample and six sieves of 30, 60, 80, 100, 150, and 200 mesh, 38.5 grams were separated in 5 minutes shaking. Only 15.5 grams of the same material were separated in the same time interval with the same combination of sieves on another commercial type of sieve shaker.
Complete for 115 volts A.C. or D .C. operation with bail for 8-inch sieves, sem isoft rubber cushion, and rubber connecting cord with rubber attachm ent plug, but without siev es...Each SQ0.00
C H IC A G O 1 7 0 0 Irving Pk. Blvd.
Lakeview Station
S C I E N T I F I C
INSTRUMENTS 1 1 LABORATORY
A P P A R A T U S
fe a u a p A r.ß ff.
N e w Yo rk • Boston • C H I C A G O • Toronto • San F ran c isc o
BOSTON 79 Amherst St.
Cambridge A Station
6 IN D U S T R IA L A N D E N G IN E E R IN G C H E M IST R Y VOL. 12, NO. 11
Ju s» lo o k h o w h e a v y it is . T h is is a c t u a l s iz e , 4 1/ 2 ,/th ic k fro m s id e to s id e .
S h o w n f u ll s c a le , th is is a se c tio n of the F D - 2 0 2 m u ffle w it h its 1 1 0 - v o lt C h ro m e l u n it , 13 g a .
H O S K I N S P R O D U C T S
E L E C T R I C H E A T T R E A T I N G F U R N A C E S • • H E A T I N G E L E M E N T A L L O Y S • • T H E R M O C O U P L E A N D LEAD WIR E • ♦ PYROMETERS • • W EL D IN G WI RE • • HEAT RESISTANT CA ST IN G S • • ENAMELING FIXTURES • • SP AR K PLUG ELECTRODE WIRE • • SP EC IA L A L L O Y S O F NICKE L • • PROT EC TION TUBES
YOU CAN’T FRY EGGS ON TOP OF THIS FURNACE I
(Right) This knock-dow n v ie w o f the Hoskins FD m uffle furnace sh o w s the construction in full d e ta il. N o te its ru g g e d sim
p lic ity , an d the g o o d thick insulation on a ll fo u r sid e s.
W h e n you buy a laboratory furnace, you expect it to do something more than just get hot. If you chance to brush the case with your hand, you don’t w ant to get burned. On a warm day, you don't w ant the furnace to radiate a lot of un
comfortable heat. . . . These unpleasant things you avoid, w hen you buy a Hoskins Furnace. The case is quite w arm , but it w o n ’t burn" you.
Hence, it contributes to your comfort, and is economical on power. . . . Our 110-volt furnaces w o n ’t run on 220-volt also. The heating unit shown here is made of 13 gauge (.072" dia.) Chromel " A ” . To run the sam e furnace on 220- volt also , the w ire w ould have to be 17 gauge (.045" dia.).
This is a very plain explana
tion of the greater durability of the Chromel units in Hoskins Furnaces. A g ain , you can’t fry eggs on top of a Hoskins Muffle Furnace; but with them you can turn out uninterrupted w ork, for months on end— in comfort and with economy.
Write for Catalog, to your dealer or to us: Hoskins Manu
facturing Co., Detroit, Mich.
7
MALLINCKRODT CHEMICAL WORKS
S T . L O U IS • C H IC A G O • P H IL A D E L P H IA • NEW Y O R K
ACCURATE COMPUTATION
and Quality Reagents Go Hand in Hand
It goes without saying that accurate calculation is essential in reporting correct analytical determinations.
Unerring mathematics, however, becomes of little avail unless the chemicals employed in exacting laboratory work are free from undesirable contamination. Mallin
ckrodt Analytical Reagents—each scrupulously refined to meet predetermined standards of purity—are especially designed to facilitate analytical precision. Chemists can depend upon Mallinckrodt A.R. Chemicals because they conform to A.C.S. specifications.
S e n d fo r c a t a l o g u e o f a n a ly t ic a l r e a g e n t s a n d o t h e r c h e m ic a ls fo r la b o r a t o r y u s e . I t c o n t a i n s d e t a i le d d e s c r ip t io n s o f c h e m i
c a ls fo r e v e r y t y p e o f a n a l y t i c a l w o r k . . . g r a v im e t r ic , g a s o m e t r ic , c o lo r im e t r ic o r t i t r im e t r i c
8 IN D U S T R IA L A N D E N G IN E E R IN G C H E M IST R Y VOL. 12, NO. 11
W I L E Y L A B O R A T O R Y M I L L
MOUNTED ON NEW TY PE PEDESTAL BASE W ITH MOTOR FOR BELT D RIVE
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
LA B O R A T O R Y A P P A R A TU S AND R E A G E N T S
W E S T W A S H IN G T O N S Q U A R E , P H I L A D E L P H I A , U. S. A.
C a b le A d d r e s s , " B a la n c e ,” P h ila d e lp h ia
4 2 7 5 - R . F r o n t V ie w 4 2 7 5 - R . R e a r
WILEY LABORATORY MILL, Motor Driven Standard M odel, m ounted on heavy pedestal base.
C o n s is t in g o f W il e y M il l c o n n e c t e d t o a h .p . m o t o r b y m e a n s o f a V - b e l t w i t h g u a r d in s u c h - m a n n e r t h a t f e e d i n g h o p p e r i s ' a p p r o x i m a t e l y 3 7 in c h e s a b o v e t h e flo o r . T h e m o t o r s u p p o r t , w h ic h is b u il t i n t o t h e b a s e , is h in g e d fo r a d j u s t i n g t h e b e l t t e n s io n b y m e a n s o f a w r e n c h .
T h e c o m p l e t e o u t f it c a n b e b o lt e d t o t h e flo o r i f d e s ir e d b u t , w i t h o u t f a s t e n i n g , o p e r a t i o n i s p r a c t i c a l l y fr e e fr o m v ib r a t io n . S a m p le s la r g e r t h a n t h o s e w h ic h c a n b e c o ll e c t e d i n t h e r e c e i v in g d r a w e r c a n b e m ille d d i r e c t ly i n t o a b a g o r - o t h e r la r g e c o n t a in e r b y r e m o v i n g t h e b o t t o m p l a t e o n w h ic h t h e d r a w e r s l id e s . T h e b a s e o c c u p ie s o n l y 1 2 x 1 2 in c h e s o f flo o r s p a c e a n d t h e s i d e w h ic h is d ir e c t ly b e n e a t h t h e d r a w e r is v e r t i c a l s o t h a t i t d o e s n o t in t e r f e r e w i t h t h e u s e o f r e c e iv e r s p la c e d o n t h e flo o r .
The W iley Mill furnished w ith this outfit is the Standard Model which was designed for the preparation, w ithout loss of moisture from heating, of certain commercial materials for laboratory analysis. Originally intended for milling all kinds of fertilizer materials, such as tankage, animal hair, hoofs, etc., but since used with great satisfaction for an increasing variety of materials.
Four knives on a revolving shaft work w ith a shearing action against six which are set in the frame. The shearing action of the cutting edges, between which there is always a clearance, tends to avoid changes in the sample, such as tem perature rise, loss of moisture, liquefaction, contam ination,¡etc., caused by crushing and abrasion methods, and makes the W iley Mill satisfactory for use with many materials which can not be reduced by other mechanical means.
A screen is dovetailed into the frame so that none of the material comes out of the grinding chamber until it is fine enough to pass through the mesh. A hinged front permits easy cleaning. Grinding chamber is 8 inches inside diameter x 3 inches deep. Drawer for ground sample is 7 x 3 x 2J4 inches.
4275-R. Laboratory M ill, W iley, Motor Driven Standard M odel, as above described, on pedestal base, complete w ith ]A h.p. motor w ith starting box and thermal overload cutout, J^-inch V-belt, set of wrenches, and three sieves of
14, 1 and 2 mm mesh, respectively. For 110 or 220 volts, 60 cycles, single phase, a.c... 375.00 Code W ord... Elm nr
N O T E — C an b e s u p p lie d o n sp ec ia l o rd e r w ith m o to rs of H t o 1 h .p . a n d fo r v o lta g e a n d c u r r e n t sp ecifica tio n s o th e r th a n a b o v e. P rice s o n re q u e st.
INDUSTRIAL a n d ENGINEERING CHEMISTRY
A N A L Y T I C A L E D I T I O N
P U B L I S H E D B Y T H E A M E R I C A N C H E M I C A L S O C I E T Y • H A R R I S O N E . H O W E , E D I T O R
R ecom m ended Specifications for Analytical Reagent Chemicals
H yd riod ic A cid, C h loroform , C hrom ium and P otassiu m Sulfate, Cobalt N itrate (N ot Low in N ic k el), G lycerol, 8-H y d ro x y q u in o lin e, Lead C arbonate,
M anganese Sulfate, M ercury, S od iu m T u n gstate, Zinc O xide
W . D . C O L L IN S, H . V. FA R II, J . V. F R E E M A N , E . F . M A R SIG L IO , I*. H . M E S S IN G E R , R . A . OSH O R N, J O S E P H R O S IN , E . W IC IIE R S , A N D II. II. W IL L A R D , C o m m itte e o n A n a ly tic a l R e a g e n ts , A m e r ic a n C h e m ic a l S o c ie ty
T
H E specifications given below are intended to serve for reagents to b e used in careful an a ly tica l w ork. T h e lim its and te s ts are based on published work, on th e experience o f m em bers of th e com m ittee in th e exam in ation o f reagent chem icals on th e m arket, and on stu d ies of th e te s ts m ade b y m em bers o f th e co m m ittee a s th e various item s w ere considered. Suggestions for th e im provem ent o f th e specifica
tion s w ill be w elcom ed b y th e com m ittee.
In all th e directions th e acids and am m onium hydroxide referred to are o f fu ll stren gth u nless d ilu tion is specified;
d ilution in d icated as (1 + 3) m eans 1 volu m e of th e reagent or strong solu tion w ith 3 volu m es of w ater; “w ater” m eans d istilled w ater o f a grade suitable for th e te s t described;
reagents used in m aking th e te s ts are supposed to b e o f th e grade recom m ended below or in previous p ublications (1- 11) from th e co m m ittee. D irectio n s for th e preparation o f th e am m onium m o ly b d a te solu tion are given under th e te s t for phosphate in am m onium n itra te (S). A tim e of 5 m in u tes is to b e allow ed for th e appearance of precip itates and before observation of color reactions, u nless som e other tim e is specified.
B lan k te s ts m u st b e m ade on w ater and all reagents used in th e te sts unless th e directions provide for elim in ation of errors due to im purities. S olu tion s of sam ples m u st be filtered for te s ts in w hich insoluble m a tter w ould interfere.
A cid H y d rio d ic
R e q u ir e m e n tsA s s a y . N o t l e s s t h a n 5 4 p e r c e n t H I.
N o n v o l a t i l e M a t t e r . N o t more than 0.010 per cent.
C h l o r i d e a n d B r o m i d e ( a s C l ) . N o t more than 0.05 per cent.
P h o s p h o r u s ( P ) . N o t more than 0 .0 0 0 3 per cent.
S u l f a t e ( S O i ) . N o t more than 0 .0 1 per cent.
H e a v y M e t a l s ( a s Pb). N o t more than 0.003 per cent.
I r o n (Fe). N o t more than 0 .0 0 2 per cent.
T e s ts
A s s a y . Weigh a suitable quantity of the acid; dilute with about 30 times its weight of water; discharge the yellow color,
if any, by adding drop by drop 0.1 N sodium thiosulfate solution and titrate with standard alkali using phenolphthalein as indi
cator.
N o n v o l a t i l e M a t t e r . T o 6 cc. of the acid add 2 drops of sulfuric acid, evaporate in a porcelain crucible, and ignite. The weight of the residue should not exceed 0 . 0 0 1 0 gram.
C h l o r i d e a n d B r o m i d e . D ilute 1.2 cc. to 100 cc. and take aliquots of 5 and 1 cc. T o the 1-ec. aliquot, add 0.04 mg. of chloride ion. D ilute each aliquot to 20 cc., add 1 cc. of am
monium hydroxide, and then slowly, with vigorous stirring, add 2 cc. of 5 per cent silver nitrate solution. H eat to boiling for 5 minutes and stir thoroughly. Cool, shake well, and filter.
To the filtrate add nitric acid until neutral and then 1 cc. more.
The turbidity in the aliquot of 5 cc. should not be greater than the turbidity in the 1-cc. aliquot to which 0.04 mg. of chloride was added.
P h o s p h o r u s . Add 5 cc. of nitric acid to 6 cc. of the acid and evaporate on the steam bath until the iodine is volatilized. Take up with 1 0 cc. of nitric acid, dilute with 5 0 cc. of water, and nearly neutralize with ammonium hydroxide. Add 5 0 cc. of ammonium m olybdate solution and shake the solution (at about
4 0 ° C.) for 5 minutes and allow to stand 0 .5 hour. Any pre
cipitate formed should not be greater than is produced when a quantity of alkaline phosphate containing 0 .0 3 mg. of phos
phorus ( P ) is treated according to the above procedure.
S u l f a t e . D ilute 3 cc. of the acid with 45 cc. of water, neu
tralize with ammonium hydroxide, add 1 cc. of hydrochloric acid, and heat to boiling. Add 3 cc. of 10 per cent barium chloride solution and allow to stand overnight. If any precipitate is formed, filter, wash thoroughly, ignite, and weigh. The weight of the ignited precipitate should not be more than 0.0013 gram greater than the weight of the ignited precipitate from a blank test made with the quantities of reagents used in the test, in
cluding filtration and ignition.
H e a v y M e t a l s . Treat 1 . 2 cc. of the acid with 3 cc. of sul
furic acid and volatilize the iodine. Take up in water, neutralize with ammonium hydroxide, and make up to 50 cc. Add 1 cc.
of 0.1 N hydrochloric acid and pass hydrogen sulfide through the solution. E stim ate lead by comparing with a solution con
taining the same amounts of sulfuric acid and ammonia, to which have been added 1 cc. of 0.1 N hydrochloric acid and 0.06 mg. of lead.
I r o n . D issolve the residue obtained in the test for nonvolatile m atter by heating with 2 cc. of hydrochloric acid and 5 drops of nitric acid and dilute to 100 cc. To 20 cc. add 2 cc. of hydro
chloric acid and 2 cc. of 1 0 per cent ammonium thiocyanate solu
tion. Any red color should not be greater than is produced by 631
632 IN D U ST R IA L A N D E N G IN E E R IN G C H E M IST R Y VOL. 12. NO. 11 0.04 mg. of iron in the same volume of a solution containing the
quantities of reagents used in the test.
C h loroform
N o t e . Chloroform should be supplied and stored in amber glass containers and protected from direct sunlight.
R e q u ir e m e n ts
S p e c i f i c G r a v i t y a t 2 5 ° / 2 5 ° C. 1 .4 7 5 to 1 .4 7 8 . N o n v o l a t i l e M a t t e r . N o t more than 0.001 per cent.
A c e t o n e o r A l d e h y d e . To p a s s test [limit about 0 .0 0 5 p e r
cent as (CH5)2CO].
A c i d a n d C h l o r i d e . To pass test.
F r e e C h l o r i n e ( C l ) . T o pass test.
S u b s t a n c e s D a r k e n e d b y S u l f u r i c A c i d . To p a s s test.
T e s ts
N o n v o l a t i l e M a t t e r . Evaporate 67 cc. (100 grams) on the steam bath and dry the residue at 105° to 110° C. for 0.5 hour.
The weight of the residue should not exceed 0.0010 gram.
A c e t o n e o r A l d e h y d e . A gitate 3 cc. with 1 0 cc. of ammonia- free distilled water in a glass-stoppered cylinder for 5 minutes.
After the liquids separate, transfer 5 cc. of the water extract to another glass-stoppered cylinder containing 4 0 cc. of ammonia- free distilled water, and add 5 cc. of Nessler’s solution. N o turbidity nor precipitate should develop within 1 minute (alde
hydes and ketones).
A c i d a n d C h l o r i d e . Shake 17 cc. with 25 cc. of water for 5 minutes, allow the liquids to separate, and draw off the water.
10 cc. should n ot redden blue litmus paper. Treat another 10 cc.
of the water with 5 drops of 0.1 N silver nitrate. N o turbidity should be produced.
F r e e C h l o r i n e . Shake gently 10 cc. for 2 minutes with 1 0 cc.
of water to which 2 drops each of 1 0 per cent potassium iodide solution and starch solution have been added and allow to sepa
rate. The lower layer should not be colored.
S u b s t a n c e s D a r k e n e d b y S u l f u r i c A c i d . Shake 20 cc.
with 5 cc. of sulfuric acid for 5 minutes in a glass-stoppered cylinder which has been rinsed with sulfuric acid. After the layers have separated the sulfuric acid should be colorless or practically so.
C h r o m iu m a n d P o ta s s iu m S u lfa te
R eq u irem en tsI n s o l u b l e M a t t e r . N o t more than 0.010 per cent.
C h l o r i d e (Cl). T o pass test (limit about 0.002 per cent).
A l u m i n u m ( A l ) . N o t more than 0.02 per cent.
A m m o n i a (N II3). To pass test (limit about 0.010 per cent).
H e a v y M e t a l s . N o t more than 0.015 per cent as sulfates.
I r o n (Fe). N o t more than 0.02 per cent.
T e s ts
I n s o l u b l e M a t t e r . D issolve 10 grams in 100 cc. of water and allow to stand on the steam bath for 1 hour. Filter through asbestos in a Gooch crucible, wash thoroughly, dry a t 105° 0 ., and weigh. The weight of the residue should not exceed 0.0010 gram.
C h l o r i d e . D issolve 0.2 gram in 20 cc. of water and divide nto tw o portions. To one portion add 1 cc. of nitric acid and 1 cc. of 0.1 N silver nitrate. To the other portion add the same volum e of nitric acid and 1 cc. of water. N o appreciable differ
ence should be apparent in the clearness of the tw o solutions.
A l u m i n u m . D issolve 4 grams in 100 cc. of water. Carefully add 4 grams of sodium peroxide. H eat the solution to boiling, filter, and wash w ith a small quantity of hot water. (R etain the residue on the filter for the test for iron.) Add hydrochloric acid to the filtrate to distinct acid reaction, then add a slight excess of ammonium hydroxide, and boil until the odor of am
monia is no longer perceptible. Filter, wash thoroughly with hot water until the washings are colorless, and ignite. The weight of the ignited precipitate should not exceed 0.0015 gram.
A m m o n i a . T o a solution of 0.25 gram of the sample in 10 cc.
of water add 1 0 cc. of 1 0 per cent sodium hydroxide solution and heat in a flask on th e steam bath, taking care that the solution does not come in contact w ith the rim of the flask. A piece of red litm us paper m oistened and placed across the mouth of the flask should n ot turn blue within 0.5 minute.
H e a v y M e t a l s . D issolve 100 grams in 200 cc. of water; add 20 to 50 mg. of mercuric chloride, and 2 cc. of N hydrochloric acid. Filter and pass hydrogen sulfide through the filtrate for
5 minutes. Let stand for 10 minutes, filter, wash, burn off the paper under a well ventilated hood, add 1 drop of sulfuric acid, ignite, and weigh. The weight of the residue should not exceed 0.0015 gram.
I r o n . Wash with hot water the residue remaining on the filter in the test for aluminum until the washings are colorless.
Dissolve the residue from the filter with 5 cc. of hydrochloric acid
( 1 + 1) and wash the filter paper with hot water. Cool and dilute to 80 cc. To 10 cc. add 10 cc. of water, 2 cc. of hydro
chloric acid, and 2 cc. of 1 0 per cent ammonium thiocyanate solution. Any red color should not be greater than is produced
by 0 . 1 mg. of iron in an equal volume of solution containing the
quantities of reagents used in the test.
C o b a lt N itr a te (N o t Low in N ick el)
R e q u ir e m e n tsI n s o l u b l e M a t t e r . N o t more than 0.010 per cent.
C h l o r i d e ( C l ) . N o t more than 0.005 per cent.
S u l f a t e (S O < ). N o t more than 0.010 per cent.
A l k a l i e s a n d E a r t h s ( a s S u l f a t e s ) . N o t more than 0.25 per cent.
C o p p e r . T o pass test (limit about 0.005 per cent).
I r o n (Fe). N ot more than 0.005 per cent.
N i c k e l ( N i ) . N o t m o r e t h a n 0.50 p e r c e n t .
T e sts
I n s o l u b l e M a t t e r . D issolve 5 grams in 50 cc. of hot water and allow to stand on the steam bath for 1 hour. Filter on as
bestos in a Gooch crucible, wash thoroughly, dry at 100° to 105° C. and weigh. The weight of the residue should not exceed 0.0005 gram.
C h l o r i d e . D issolve 1 gram in 20 cc. of water and divide into 2 equal portions. To 1 portion add 1 drop of 0.1 N hydrochloric acid, 1 cc. of nitric acid, and 1 cc. of 0.1 N silver nitrate. Allow to stand 10 minutes, filter w ithout washing, and add 0.025 mg.
of chloride ion. The precipitate should be greater than is formed in the other portion on the addition of 1 cc. of nitric acid and 1 cc.
of 0.1 N silver nitrate.
S u l f a t e . Treat 5 grams with 10 cc. of water and 10 cc. of hydrochloric acid and evaporate to dryness on a steam bath.
Redissolve the residue in about 5 cc. of hot water and 10 cc. of hydrochloric acid and re-evaporate to dryness. D issolve the residue in 1 0 0 cc. of water and 1 ce. of hydrochloric acid and filter. H eat the filtrate to boiling, add 5 cc. of 10 per cent barium chloride solution, and allow to stand overnight. If a precipitate is present, filter, wash, and ignite. The weight of the ignited precipitate should not be more than 0 . 0 0 1 2 gram greater than the weight obtained in a blank test with the same quantities of reagents following the same procedure, including filtration.
A l k a l i e s a n d E a r t h s . Dissolve 2 grams of the sample and
1 gram of ammonium chloride in 2 0 cc. of dilute ammonium hy
droxide (1 + 3), dilute to 90 cc., and pass hydrogen sulfide until the cobalt is all precipitated. Add sufficient water to make the total volume 100 cc., mix well, and filter. Evaporate 50 cc. of the filtrate nearly to dryness, add 0.5 cc. of sulfuric acid, ignite, and weigh the residue. The weight of the residue should not exceed 0.0025 gram.
C o p p e r . Solution No. 1. D issolve 1 gram in 30 cc. o f water and add 0.5 cc. of nitric acid.
D issolve 1 gram in 20 cc. of water, add 0.5 cc. of nitric acid, cool to about 15° C., and add 1 0 cc. of saturated hydrogen sulfide water. N o change in color should be noticeable when compared w ith solution N o. 1.
I r o n . D issolve 1 gram in 20 cc. of water, and add 1 gram of ammonium chloride and sufficient ammonium hydroxide to dis
solve the precipitate first formed. Filter and wash until the filtrate is colorless. Drop on the filter 5 cc. of hot dilute hydro
chloric acid ( 1 + 1) and wash with hot water until the filtrate and washings measure about 45 ec. Cool, add 5 cc. of a 10 per cent ammonium thiocyanate solution, dilute to 50 cc., and mix well. Any red color should not be greater than in a control test made with the same volum e of water and hydrochloric acid to which 0.05 mg. of ferric iron has been added.
N i c k e l . D issolve 0.5 gram in 70 ce. of water, add 3 grams of sodium acetate and 2 drops of acetic acid, and boil for 5 min
utes. Filter while hot and wash with 10 cc. of hot water. Allow the filtrate to cool and render it slightly alkaline by carefully adding 1 or 2 drops of ammonium hydroxide. Add 60 cc. of a 1 per cent alcoholic solution of dim ethylglyoxim e and allow to stand overnight. Filter through a weighed Gooch crucible, wash with alcohol, and dry a t 100° C. The increase in weight should not exceed 0.0125 gram.
G lycerol
R e q u ir e m e n tsC o l o k . T o pass test.
S p e c i f i c G r a v i t y a t 2 5 °/2 5 ° C . N o t less than 1.250 per cent.
N o n v o l a t i l e M a t t e r . N o t more than 0.005 per cent.
N e u t r a l i t y . T o pass test.
C h l o r i d e ( C l ) . N o t more than 0.001 per cent.
S u l f a t e ( S O4) . To pass test (limit about 0 . 0 0 2 per cent).
F a t t y A c i d E s t e r s . T o pass test (limit about 0.07 per cent as glycerol butyrate).
S i l v e r - R e d u c i n g S u b s t a n c e s . T o pass test.
S u b s t a n c e s D a r k e n e d b y S u l f u r i c A c i d . T o pass test.
H e a v y M e t a l s . T o pass test (limit about 0.0005 per cent as lead or iron).
T e s ts
C o l o r . The color of glycerol when viewed downwards against
a white surface in a 50-cc. Nessler tube should n ot be darker than the color of a standard made by diluting 0.3 cc. of ferric chloride color solution (see note) to 50 cc. in a Nessler tube of the same diameter as that containing the glycerol.
S p e c i f i c G r a v i t y a t 2 5 °/2 5 ° C. This value should be deter
mined with a pycnometer a t 25° C. and be not less than 1.250, corresponding to about 96 per cent glycerol.
N o n v o l a t i l e M a t t e r . H eat 20 grams in an open dish, ignite the vapors, and when the glycerol has been entirely consumed ig
nite a t a low red heat. The w eight of the residue should not exceed 0 . 0 0 1 0 gram.
N e u t r a l i t y . A 10 per cent aqueous solution of glycerol should not affect the color of either red or blue litm us paper in
1 minute.
C h l o r i d e . D ilute 5 grams w ith 30 cc. of water, and add 1 cc.
of nitric acid and 1 cc. of 0.1 N silver nitrate solution. Any turbidity should not be greater than th at produced by 0.05 mg.
of chloride ion in an equal volum e of solution containing the quantities of reagents used in the test.
S u l f a t e . D ilute 5 grams w ith 2 5 cc. of water, and add 1 cc.
of 0 .1 N hydrochloric acid and 2 cc. of 1 0 per cent barium chloride solution. Any turbidity should not be greater than is produced
by 0 . 0 1 mg. of sulfate ion in an equal volume of solution con
taining the quantities of reagents used in the test, comparison being made after the sample and standard have stood for 2 0 minutes.
F a t t y A c i d E s t e r s . Weigh 40 grams into a 250-cc. Erlen- meyer flask and add 50 cc. of freshly boiled hot distilled water.
Add 10 cc. of 0.1 N sodium hydroxide solution, cover with a loosely fitting pear-shaped bulb, and leave on the steam bath for 45 minutes. Cool and titrate the excess alkali w ith 0 . 1 N hydro
chloric acid, using 3 drops of bromothymol blue solution as indicator and titrating to a bluish-green end point. Run a blank with 50 cc. of the same water and 10 cc. of the 0.1 iV"
sodium hydroxide solution, heating it for the same length of time and titrating to the same bluish-green end point with 0 . 1 iV- hydrochloric acid. The difference in the amount of acid used in the blank and in the titration of the sample should be less than 3.00 cc.
S i l v e r - R e d u c i n g S u b s t a n c e s . M ix 10 cc. with 10 cc. of 10 per cent ammonium hydroxide. H eat to 60° C., add 0.5 cc.
of 0.1 N silver nitrate solution, and allow to stand in the dark for 5 minutes in a jar of water at 60° C. The color produced should be less than the color produced when hydrogen sulfide is passed through 25 cc. of a solution containing 1 gram of sodium sulfate and 0.04 mg. of lead.
S u b s t a n c e s D a r k e n e d b y S u l f u r i c A c i d . Vigorously shake 5 cc. of glycerol with 5 cc. of sulfuric acid in a glass- stoppered 25-cc. cylinder for 1 minute and allow the liquid to stand for 1 hour. The liquid should not be darker than a stand
ard made up of 0.4 cc. of cobaltous chloride color solution, 3.0 cc. of ferric chloride color solution, and 6.60 cc. of distilled water (see note for preparation of color solutions).
H e a v y M e t a l s . D ilute 2 grams with 10 cc. of water, add 1 cc. of 0.1 N hydrochloric acid and 5 cc. of hydrogen sulfide water, and render alkaline with ammonium hydroxide. N o darkening should be observed.
No t e. Co l o r So l u t i o n s.
Ferric Chloride Color Solution. Ferric chloride is dissolved in a mixture of 25 volumes of hydrochloric acid and 975 volumes of water and the strength adjusted so that the iron content corre
sponds to 45.05 mg. of FeCl3.6H2 0 per cc.
Cobaltous Chloride Color Solution. Cobaltous chloride is dis
solved in a mixture of 25 volumes of hydrochloric acid and 975 volum es of water and the strength adjusted so that the cobalt content corresponds to 59.5 mg. of CoC1s.6 H 20 per cc.
8
-H y d ro x y q u in o lin e
R e q u ir e m e n tsM e l t i n g P o i n t R a n g e . 72.5° to 73.5° C.
I n s o l u b l e i n A l c o h o l . N o t more than 0.050 per cent.
R e s i d u e o n I g n i t i o n . N o t more than 0.50 per cent.
S u l f a t e (S O < ). T o pass test (limit about 0.02 per cent).
S u i t a b i l i t y f o r M a g n e s i u m D e t e r m i n a t i o n s . T o pass test.
T e s ts
M e l t i n g P o i n t R a n g e . Determ ine by the U. S. Pharma
copoeia method.
I n s o l u b l e i n A l c o h o l . D issolve 3 grams in 40 cc. of alcohol, filter through a Gooch crucible, wash with 95 per cent alcohol, dry at 105° to 1 1 0° C., and weigh. The weight of the insoluble material should not exceed 0.0015 gram.
R e s i d u e o n I g n i t i o n . Ignite 1 gram. The weight of the residue should not exceed 0.0005 gram.
S u l f a t e . D issolve 1 gram in 1 cc. of hydrochloric acid and dilute with 20 cc. of water. H eat to boiling and add 1 cc. of barium chloride solution. N o turbidity should be observed after standing for 30 minutes.
S u i t a b i l i t y f o r M a g n e s i u m D e t e r m i n a t i o n s . Dissolve 0.50 gram of magnesium chloride (M gCl2.6H20 ) in water con
taining 1 cc. of dilute hydrochloric acid ( 1 + 1) and make to a volume of 100 cc. D ilute 10 cc. of the solution to 50 cc. and add 3.5 cc. of a solution of the 8-hydroxyquinoline prepared by dissolving 2.5 grams in 5 cc. of warm acetic acid and pouring into 95 cc. of water at 60° C. H eat to 80° C., add with stirring 2 cc.
of ammonium hydroxide, allow to cool for 1 0 minutes, and filter.
The filtrate should be yellow and alkaline and should yield a yellow precipitate when 5 cc. of the magnesium chloride solution are added and the whole is warmed.
L ead C a rb o n ate
R e q u ir e m e n tsI n s o l u b l e i n A c e t i c A c i d . N o t more than 0.03 per cent.
C h l o r i d e (Cl). N o t more than 0.005 per cent.
N i t r a t e ( N 0 3) . T o pass test (limit about 0.005 per cent).
A l k a l i e s a n d A l k a l i n e E a r t h s . N o t more than 0.20 per cent as sulfates.
I r o n (Fe). N ot more than 0.005 per cent.
Z i n c (Zn). To pass test (limit about 0.005 per cent).
T e s ts
I n s o l u b l e i n A c e t i c A c i d . D issolve 5 grams by heating on a steam bath for 1 hour w ith a mixture of 50 cc. of water and 7 cc. of acetic acid. If an insoluble residue remains, filter and wash w ith a mixture of 1 0 0 volum es of water and 2 cc. of acetic acid. D ry at 105° to 110° C. The weight of the residue should not exceed 0.0015 gram.
C h l o r i d e . D issolve 1 gram in 20 cc. of 10 per cent nitric acid and filter if solution is not perfectly clear. Add 1 cc. of 0.1 N silver nitrate solution. A ny opalescence should not be greater than that produced by 0.05 mg. of chloride ion in an equal volume of water containing the quantities of reagents used in the test.
N i t r a t e . Dissolve 1 gram in 7 cc. of water, 1 cc. of sodium chloride solution containing 5 mg. of N aC l per cc., and 2 cc. of acetic acid. If necessary heat on the steam bath to dissolve the sample. Cool and dilute to 30 cc. T o 1 0 cc. add 0.20 cc. of indigo carmine solution ( 1 in 1 0 0 0) and 1 0 cc. of sulfuric acid.
Stir thoroughly and allow to stand for 10 minutes. The blue color should not be completely discharged.
A l k a l i e s a n d A l k a l i n e E a r t h s . D issolve 2 grams by- heating with a mixture of 20 cc. of water and 3 cc. of nitric acid.
D ilute to 100 cc. with water and precipitate the lead completely with hydrogen sulfide. Filter. To 50 cc. of the filtrate add a few drops o f sulfuric acid, evaporate to dryness, and ignite. The weight of the residue should not exceed 0 . 0 0 2 0 gram.
I r o n . Warm the residue obtained in the test for alkalies and alkaline earths with 1 cc. of hydrochloric acid and 2 drops of nitric acid. D ilute to 20 cc. w ith water; add 2 cc. of hydro
chloric acid and 3 cc. of 10 per cent ammonium thiocyanate solution. Any red color should not be greater than is produced in a control test made with 0.05 mg. of iron.
Z i n c . D issolve 3 grams in a mixture of 25 cc. of water and 5 cc. of acetic acid. D ilute with water to 42 cc. Add with stirring 3 cc. of sulfuric acid, and filter. To 30 cc. of the filtrate add 5 drops of nitric acid; heat to boiling and pour into a mixture of 10 cc. of ammonium hydroxide and 20 cc. of water. Filter while hot and wash with 2 cc. of hot water. Neutralize with
6 3 t IN D U S T R IA L A N D E N G IN E E R IN G C H E M IST R Y VOL. 12. NO. II acetic acid, then add 1 cc. more of the acid. Cool and add 2 cc.
of a freshly prepared 1 0 per cent solution of potassium ferro- cyanide. N o turbidity should appear in 10 minutes.
M a n g a n ese S u lfa te
R eq u irem en tsW a t e r o f C r y s t a l l i z a t i o n . 3 2 to 3 8 per cent.
I n s o l u b l e M a t t e r . N o t more than 0.010 per cent.
C h l o r i d e ( C l ) . N o t more than 0 .0 0 5 p e r cent.
A l k a l i e s a n d A l k a l i n e E a r t h s . N o t more than 0.25 per cent.
I r o n (Fe). N ot more than 0.002 per cent.
H e a v y M e t a l s a s Pb. To pass test (limit about 0.001 per cent).
N i c k e l (N i). N ot more than 0.05 per cent.
Z i n c ( Z n ) . To pass test.
S u b s t a n c e s R e d u c i n g P e r m a n g a n a t e . T o pass test.
T e s ts
W a t e r o f C r y s t a l l i z a t i o n . Weigh accurately about 2
grams. H eat a t 150° C . for a few hours, then ignite at about 400° to 500° C . to constant weight. The loss in weight should be from 3 2 to 3 8 per cent.
I n s o l u b l e M a t t e r . D issolve 10 grams in 100 cc. of hot water and allow to stand on the steam bath for 1 hour. Filter on asbestos in a Gooch crucible, wash thoroughly, and dry at 105° to 110° C . T he weight of the residue should not exceed
0 . 0 0 1 0 gram.
C h l o r i d e . D issolve 1 gram in 20 cc. of water, and add 1 cc.
of nitric acid and 1 cc. of 0.1 ¿V silver nitrate. A ny turbidity should not be greater than is produced by 0.05 mg. of chloride ion in an equal volume of water w ith the quantities of nitric acid and silver nitrate used in the test.
A l k a l i e s a n d A l k a l i n e E a r t h s . D issolve 2 grams in about 90 cc. of water and precipitate the manganese by adding sufficient fresh ammonium sulfide solution. H eat on the water bath for about 0.5 hour, cool, dilute with water to 100 cc., mix well, and filter. Evaporate 50 cc. of the filtrate to dryness, ignite, and weigh the residue. The weight of the residue should not exceed 0.0025 gram.
I r o n . D issolve 1 gram in 15 cc. of water, add a drop of nitric acid, and heat to boiling. Cool and dilute with water to 15 cc.
Add 2 cc. of hydrochloric acid and 3 cc. of 10 per cent ammonium thiocyanate solution. Any red color produced should not be greater than that produced in a control test made with 0 . 0 2 mg.
of iron.-
H e a v y M e t a l s . Solution No. 1. D issolve 1 gram of the manganese sulfate in 20 cc. of water and add 1 cc. of 1 N hydro
chloric acid.
D issolve 1 gram of the manganese sulfate in 10 cc. of water, add 1 cc. of 1 N hydrochloric acid and 1 0 cc. of saturated hydrogen sulfide water. N o change in color should be noticeable when compared with solution N o. 1.
N i c k e l . D issolve 1 gram in 200 cc. of water. D issolve 2 grams of sodium acetate in 2 0 cc. of the solution and add 1 0 cc.
of hydrogen sulfide water. After 1 minute, add 5 cc. of glacial acetic acid. Any darkening should not be greater than in a blank to which 0.05 mg. of nickel has been added.
Z i n c . D issolve 1 gram in 20 cc. of water. T o 10 cc. of the solution add 10 cc. of hydrogen sulfide water. N o turbidity which is cleared up by hydrochloric acid should be produced in
2 minutes.
S u b s t a n c e s R e d u c i n g P e r m a n g a n a t e . D issolve 10 grams in 200 cc. of water. Add 3 cc. each of sulfuric acid and phos
phoric acid, then add 0 . 1 cc. o f 0.1 N potassium permanganate.
The pink color should persist for 1 minute, correction being made for any blank on the reagents.
M ercu ry
R e q u ir e m e n tsA p p e a r a n c e . T o pass test.
B a s e M e t a l s . T o pass test (limit to about 0.0001 per cent).
G o l d a n d S i l v e r . N o t more than 0.005 per cent.
T e s ts •
A p p e a r a n c e . The mercury shall have a bright mirrorlike surface free from film or scum. I t shall pour freely from a thoroughly clean, dry glass container w ithout leaving any mer
cury adhering to the glass.
B a s e M e t a l s . Weigh 10 to 20 grams into a tared porcelain crucible. Evaporate the mercury from a h o t plate, in a well-
ventilated hood, w ithout permitting the mercury to boil. The mercury shall retain its bright mirrorlike surface and should not develop any film or scum.
G o l d a n d S i l v e r . After the mercury in the preceding test has evaporated, ignite the crucible at a dull red heat for 5 min
utes, making sure th at mercury which has condensed on the walls of the crucible is driven off. The weight of the residue should not exceed 0.005 per cent of the weight of the sample.
S o d iu m T u n g s ta te
R e q u ir e m e n tsI n s o l u b l e M a t t e r . N ot more than 0.015 per cent.
A l k a l i n i t y . N o t more than 0.20 per cent as N a2C 0 3.
C h l o r i d e ( C l ) . N o t more than 0.01 per cent.
M o l y b d e n u m ( M o ) . N o t more than 0.001 per cent.
N i t r o g e n C o m p o u n d s ( a s N ). N o t more than 0.002 per cent.
S u l f a t e (S O < ). N o t more than 0.01 per cent.
H e a v y M e t a l s . T o pass test (lim it about 0.0005 per cent lead, about 0.0005 per cent iron).
T e sts
I n s o l u b l e M a t t e r . D issolve 10 grams in 100 cc. of water and digest on the steam bath for 1 hour. Filter through a tared Gooch crucible, wash, dry a t 105° C., and weigh. The weight of the residue should not exceed 0.0015 gram.
A l k a l i n i t y . D issolve 2 grams in 50 cc. of cold water and add 2 drops of phenolphthalein solution. A pink color should be produced which should be discharged b y the addition of not more than 0.4 cc. of 0.1 N acid.
C h l o r i d e . Dissolve 1 gram jn 25 cc. of water and bring to a boil. Add 15 cc. of a solution containing 5 cc. of nitric acid and
1 0 cc. of water in which is dissolved 0 . 1 gram of cinchonine alka
loid. Continue to boil for 5 minutes, cool, dilute to 50 cc., mix well, and filter. To 10 cc. of the filtrate add 1 cc. of 0.1 iV silver nitrate. Any turbidity in 2 minutes should not be greater than is produced by 0 . 0 2 mg. of chloride ion in an equal volume of solution containing the quantities of reagents used in the test.
M o l y b d e n u m . D issolve 2 grams in 10 cc. of water and make slightly alkaline if necessary with dilute sodium hydroxide.
D issolve in this solution 0.5 gram of potassium xanthate w ithout warming. Add 10 cc. of chloroform, then add, drop by drop, dilute sulfuric acid (1 + 9), shaking after each addition until the color in the chloroform is no longer intensified. Any color should not be greater than is produced by 0.03 mg. of molybdic anhy
dride (corresponding to 0 . 0 2 mg. of molybdenum) in an equal volume of solution containing the quantities of reagents used in the test.
N i t r o g e n C o m p o u n d s . D issolve 4 grams in 40 cc. of water and add 20 cc. of 10 per cent sodium hydroxide solution and 0.5 gram of aluminum wire. Let stand 3 hours protected from loss or absorption of ammonia. D ecant 30 cc. and add 2 cc. of Nessler’s solution. Any color should not be greater than is pro
duced by a quantity of an ammonium salt corresponding to 0.04 mg. of nitrogen in an equal volum e of solution containing the quantities of reagents used in the test.
S u l f a t e . Dissolve 2 grams in 100 cc. of water and add slowly with stirring 5 cc. of hydrochloric acid. Evaporate to dryness and heat for 20 minutes a t 110° C. Add 30 cc. of water, 2.5 cc.
of hydrochloric acid, and 2 cc. of cinchonine solution [made by dissolving 5 grams of cinchonine in 50 cc. of dilute hydrochloric acid (1 + 3)] and heat just below the boiling point for 30 minutes.
D ilute to 30 cc. and allow to stand until cool. Filter and to 15 cc.
of the filtrate add ammonium hydroxide a drop a t a tim e until a permanent precipitate forms. Add just sufficient hydrochloric acid to redissolve the precipitate and add 5 cc. of 10 per cent barium chloride solution. A ny turbidity should not be greater than is produced by 0 . 1 mg. of sulfate ion in an equal volume of solution containing the quantities of reagents used in the test.
H e a v y M e t a l s . D issolve 2 grams in 20 cc. of water. Add 2 cc. of ammonium hydroxide and 5 cc. of hydrogen sulfide water.
There should be no brown coloration and any green coloration should not be greater than is produced by 0 . 0 1 mg. of iron in an equal volume of solution containing the quantities of reagents used in the test.
Z in c O xide
R e q u ir e m e n tsI n s o l u b l e i n S u l f u r i c A c i d . N o t more than 0.010 per cent.
A l k a l i n i t y . T o pass test.
C h l o r i d e ( C l ) . N o t more than 0.001 per cent.
N i t r a t e (NOs). T o pass test (limit about 0.003 per cent).
