Industrial and Engineering Chemistry : analytical edition, Vol. 9, No. 8

A nalytical E d itio n Vol. 9, No. 8

IN D U S T R I A L

^ E N G I N E E R I N G

C H E M I S T R Y

V o l. 2 9 , C o n s e c u tiv e N o . 31

P u b lis h e d b y t h e A m e r ic a n C h e m ic a l S o c ie t y H a rriso n E . H o w e , E d ito r

A ugust 15, 1937

Publication Office: Easton, Pa. . Editorial Office: Room 706, Mills Building, Washington, D . C. . Telephone: National 0848 Cable: Jiechem (Washington) . Advertising Department: 332 West 42nd Street, New York, N . Y. . Telephone: Bryant 9-4430

C O N T E N T S

19,100 Copies of This Issue Printed

Quantitative Determination of Aluminum by Precipitation with Urea . Hobart II. W illard and Ning Kang Tang 357

Simple and Inexpensive Electric Heating Apparatus . . ... Frilz Breuer 363

Determination of Small Quantities of Oxygen in Gases and Liquids . . I. J . W. MacHallie and J. E. Maconachie 364

Graphic Analysis of Hydrocarbon O i l s ...

...C. II. Fisher and Abner Eisner 366

Arsenate Method for the Determination of Zirconium . ... Walter C. Schumb and Edward J. Nolan 371

Separation of Gold from Tellurium and Selenium . . . ... J . Seath and F. E. Beamish 373 The Peroxide Method for Vanadium. A Spectrophoto-

metric Study . . E . R. Wright with M . G. Mellon 375 Production of Uniform T est Films of Shellac and Other

F i n i s h e s ... Paul F. Bruins 376

Determination of Chromium in F erroclirom e...

...G. Frederick Smith and C. A . Getz 378

Titration of Aromatic Amines with Nitrous Acid . . . ... Joseph Phillips with Alexander Ijowy 381

Extraction of Minute Amounts of M o r p h in e ...

... Charles E. Morgan 383 i

' ’ Determination of Primary Calcium Phosphate in Mixtures of the Calcium O rth o p h o sp h a tes...

II. V. Tartar, Isabel S. Colman, and Luella L. Kretchmar 384

A Rapid Method for Protein D i a l y s i s ...

. . F. W. Bernhart, L. Earle Arnow, and A . C. Bratton 387

Baume Hydrometer Correction Table for Sodium Hydrox­

ide S o lu tio n s ... lohn Griswold 388

The Rare Earth Metals and Their Compounds . . . . . Laurence L. Quill, Richard F. Robey, and Sam Seifter 389

The Evaluation of Rubber and Rubberlike Compositions as Vibration A b so rb ers...Felix L. Yerzley 392

Differentiation of Oils by Enzymic H y d r o l y s i s ...

... K . Venkata Giri and P. N . Bhargava 395

Surface Effects of the Platinum Metals on Silver Assay B e a d s ... E. C. Forbes and F. E. Beamish 397

Modified Capillary Combustion U nit for a Gas Analysis Apparatus . Bert E. Christensen and Robert Carlton 400

Constant-Temperature Bath for Molecular Stills . . . . ... 0 . A . Nelson and II. L. Haller 402

Enclosed Apparatus for Laboratory Crystallizations . . ... John D. Piper and N . A . Kerstein 403

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4 IN D U STR IA L A N D E N G IN E E R IN G CHEM ISTRY VOL. 9, NO. 8

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A UG UST 15, 1937 ANALYTICAL EDITIO N 5

11 MMi ,/ fll

San Francisco-Oakland B RI DGE

T h e San F r a n c is c o -O a k la n d B r id g e is a n o th e r im p r e s s iv e m o n u m e n t to th e s k i ll o f th e in d u s tr ia l c h e m is t.

M o n t h s b e f o r e t h e a r c h i t e c t f i r s t r e a c h e d fo r a p e n c il, y ea rs b e fo r e th e g ia n t e x c a v a to r t o o k its first b ite , th e r e se a r c h c h e m is t in h is la b o r a to r y a n a ly z e d , a n d te s te d , a n d p r o v e d th e q u a litie s o f th e m a te r ia ls to b e u se d in its ’ c o n s t r u c tio n . O n ly w h e n h e h ad c o m p le t e d h is te s ts a c c o r d in g to d e fin ite s ta n d a r d s, c o u ld th e a ctu a l w o r k o f c o n s t r u c tio n b e g in . C h e m ­ istry b u ilt th is b r id g e ju st a s su r e ly as d id th e a r c h ite c ts , th e e n g in e e r s , th e s t e e l w o r k e r s an d o t h e r s w h o p r o ­ d u c e d a n d u tiliz e d th e m a te r ia ls w h ic h m a d e th is u n d e r ta k in g a p r a c ­ tic a l reality.

T h e sta n d a r d s se t b y th e in d u s tr ia l c h e m is t fo r su c h v ita l r e s e a r c h w o r k are n e c e s s a r ily e x a c t in g . A n d ju st a s e x a c t in g are th e sta n d a r d s e s t a b ­ lis h e d fo r th e m a n u fa ctu re o f M e r c k R e a g e n t C h e m ic a ls .

MERCK & CO. I NC. R AHWAY , N

6 IN D U STR IA L A N D E N G IN E E R IN G CHEM ISTRY VOL. 9, NO. 8

L U B R I S E A L

(R E G IS T E R E D T R A D E M A RK)

S T O P C O C K GREASE

A p r o p r ie t a r y l u b r i c a ti n g a n d s e a li n g m d l m o ( Im p ro v e d fo rm u !* . * p llrc ly

L U B R I S E A L (S t o p c o c k G r e a s e ) . A lu b r ic a tin g , s e a lin g a n d r u s t-p r o o fin g m e d iu m , fo u n d in a c t u a l p r a c tic e t o b e n e a r ly a c id a n d a lk a li-p r o o f. R e c o m m e n d e d a s a lu b r ic a n t fo r g la s s or m e t a l s t o p c o c k s a n d fo r s e a lin g d e s ic c a to r s , a n a e r o b ic ja r s a n d s im ila r u te n s ils . O ffered in th r e e d iffe r e n t f o r m u l a e :

I m p r o v e d F o r m u la , m e lt in g p o in t a p p r o x im a t e ly 4 0 ° C ( 1 0 4 ° F ) . R e c o m m e n d e d fo r g e n e r a l

la b o r a t o r y w o r k . I n c o ll/ip s ib le t u b e c o n t a in in g 2 5 g r a m s . P e r t u b e ... .5 0

C o d e W o r d ... X u t y x

1 0 % d is c o u n t i n c a rto n c o n ta in in g 1 2 tu b es

2 0 % “ “ “ “ 1 4 4 “

D it t o , b u t in c a n c o n t a in in g 5 0 0 g r a m s . P e r c a n ... 4 .5 0 C o d e W o r d ... X u u f j

2 0 % d is c o u n t i n c a se c o n ta in in g 1 8 c a n s

H o t W e a t h e r F o r m u la . I d e n t ic a l w it h t h e I m p r o v e d F o r m u la b u t w ith a m e lt in g p o in t o f a p p r o x im a t e ly 5 0 ° C ( 1 2 2 ° F ) . R e c o m m e n d e d fo r u s e a t a t e m p e r a tu r e o f a p p r o x im a t e ly

3 5 °C ( 9 5 ° F ) . I n c o lla p s ib le t u b e c o n t a in in g 2 5 g r a m s . P e r t u b e ... .5 0 C o d e W o r d ... X u u i d

1 0 % d is c o u n t i n c a rto n c o n ta in in g 1 2 tu bes

2 0 % “ “ “ “ 1 4 4 “

O r ig in a l F o r m u la . W h ile n o t a s h o m o g e n e o u s a s t h e I m p r o v e d F o r m u la , t h e o r ig in a l f o r m u la m e lt s a t a p p r o x im a t e ly 4 3 °C ( 1 0 4 .4 ° F ) a n d is p r e fe r r e d b y s o m e w o r k e r s fo r t h is r e a so n . S e e T h e J o u r n a l o f B io lo g ic a l C h e m is tr y , V ol. L X X X I I I , N o . 1 { J u l y , 1 9 2 9 ), p . 2 2 7 .

I n 1 o z . r o u n d t i n b o x . P e r o z ... .5 0 C o d e W o r d ... X u u k z

1 0 % d is c o u n t i n c a rto n c o n ta in in g 1 2 t i n boxes

2 0 % “ “ “ “ 1 4 4 “ “

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C a b le A d d r e ss, " B a la n c e ,” P h ila d e lp h ia

IN D U S T R IA L

a n d E A T G lN E E R I M i

C H E M I S T R Y

H a rriso n E. H o w e, E d itor

Q uantitative D eterm ination o f A lum inum by Precipitation with Urea

IIOBART H . W ILLARD AND N IN G KANG TANG, U n iversity o f M ich ig a n , A nn Arbor, M ich . A N A L Y T IC A L E D IT IO N

A lu m in u m c a n b e a c c u r a te ly se p a ra ted fr o m la r g e a m o u n t s o f c a lc iu m , b a r iu m , m a g n e s iu m , m a n g a n e s e , c o b a lt, n ic k e l, z in c , ir o n , c a d m iu m , a n d cop p er b y p re­

c ip it a t io n a s t h e d e n s e b a sic s u c c in a t e by b o ilin g w it h u r e a th e a c id s o lu t io n c o n ta in ­ in g s u c c in ic a c id . H y d ro ly sis o f th e u rea fo r m s a m m o n ia g r a d u a lly in a h o m o ­ g e n e o u s s o lu t io n , r e s u ltin g in a p H o f 4.2 to 4.6 . O w in g to t h e d e n se n a tu r e o f th e p re­

c ip it a t e , i t is e a s ily filte r e d an d w a sh e d an d sh o w s m u c h le s s a d so r p tio n o f o th e r s a lts

I

num oxide per liter in the pH range 6.5 to 7.5.

Q u a n tita tiv e D e t e r m in a tio n o f A lu m in u m by P r e c ip ita tio n as B a sic S u lf a te

Ma t e r i a l s Us e d. The aluminum metal was a special grade obtained from the Aluminum Company of America and contained 99.94 per cent of Al, 0.03 per cent of Si, 0.01 per cent of Ti, and 0.03 per cent of Fe. The latter two are, of course, always precipi­

tated with the aluminum. The urea was a c. p. grade. Am­

monium chloride was reagent quality material. Ammonium

th a n d o es th e p r e c ip ita te o b ta in e d b y th e u su a l m e th o d s . T h e b a s ic s u lf a t e p r e c ip i­

ta te d in th is w ay is a lso d e n se , b u t th e pH m u s t b e 6.5 to 7.5 a n d se p a r a tio n s in c er­

ta in c a ses are le s s sa tis fa c to r y . T h e a c ­ cu racy o f se p a r a tio n s m a d e b y th e urea m e th o d is far su p er io r to th a t o b ta in a b le by th e u se o f a m m o n ia . T h is is a ttr ib u te d to a c o m b in a tio n o f fo u r im p o r ta n t fa c ­ to rs— a d e n s e p r e c ip ita te , a slo w , u n ifo r m in cre a se in p H , a h o m o g e n e o u s s o lu tio n , an d a lo w final pH .

hydroxide was prepared by passing ammonia from a cylinder through a scrubbing bottle into redistilled water contained in a quartz flask.

P r o c e d u r e . Approximately 0.1 gram of the aluminum metal was weighed into 600-ml. beakers, tall-form, and dissolved in about 5 ml. of dilute hydrochloric acid, gently warming at the end to ensure complete solution. After diluting somewhat, dilute ammonium hydroxide was added until the solution became slightly turbid, then it was cleared with dilute hydrochloric acid, and one or two drops in excess were added. Four grams of urea, 20 grams of ammonium chloride, and 1 gram of ammonium sul­

fate were introduced and the volume was brought to 500 ml.

The solution was then heated to boiling and kept gently boiling for 2 hours after the appearance of an opalescence, after which it was placed on an electric hot plate for 1 hour to allow the pre­

cipitate to settle. The precipitate was filtered off, and that ad­

hering to the beaker removed as thoroughly as possible by means of pieces of filter paper.

To ensure complete removal of the last traces of the precipitate, it was dissolved in a little hydrochloric acid, reprecipitated by the procedure of Blum (2), and filtered through the paper contain­

ing the main portion of the precipitate. The combined precipi­

tates were washed ten times with hot 1 per cent ammonium chloride solution, made alkaline to methyl red with ammonium hydroxide. After ignition to constant weight in a platinum crucible over a blast Meker at approximately 1200° C., it was weighed in a counterpoised weighing bottle. The pH of the filtrate and the amount of aluminum in the filtrate and washings, amounting to 0.078 to 0.1 mg., were determined coloriinetrically

my

Several workers (6 ,1 0 ,1 8 , H ) have reported th a t sulfate which accompanies aluminum when it is precipitated as h y ­ droxide from sulfate solutions, is very difficult to rem ove b y ignition. An exam ination of the ignited oxide obtained above, by fusion with sodium carbonate and finally testin g w ith barium chloride, showed th a t only a negligible am ount of

358 IN D U ST R IA L A N D E N G IN E E R IN G CHEM ISTRY VOL. 9. NO. 8

Ta b l e I . Qu a n t i t a t i v e De t e r m i n a t i o n o f Al u m i n u m b y Pr e c i p i t a t i o na s Ba s ic Su l f a t e

Final pH of AhOa° AIjOj Error

Solution Taken Found AljOj

Gram Gram M g.

7 .0 8 0.1913 0.1 9 1 6 + 0 . 3

7 .0 7 0.1954 0.1 9 5 6 + 0 . 2

7 .0 3 0.1 9 6 0 0.1 9 5 7 - 0 . 3

7 .2 7 0.1 9 5 0 0.1 9 5 4 + 0 . 4

6 .7 7 0 .1 9 1 5 0.1912 - 0 . 3

6 .5 8 0.1909 0.1907 - 0 . 2

7 .0 9 0.1941 0.1 9 4 0 - 0 . 1

7 .1 7 0.1 9 2 0 0.1 9 1 7 - 0 . 3

6 .9 4 0 .1 9 2 0 0.1921 + 0 . 1

6 .9 9 0.1914 0.1 9 1 3 - 0 . 1

° Corrected for impurities in the original metal.

Ta b l e I I . Se p a r a t i o n o f Al u m i n u m f r o m Ot h e r El e m e n t s (Single precipitation)

Am ount Present

Aluminum Taken M etal Added in Precipitate

Gram Gram M g.

0 .1 C a° 1 .0 Trace

0 .1 M g 1 .0 None

0 .1 Ni 0 .1 2 5 0 .7

0 .1 C o . 0 .1 2 5 1 .0

0 .1 Zn 0 .1 2 5 13 .6

0 .1 M u 1 .0 0 .1

0 .1 Cd 0 .1 2 5 0 .4

0 .1 Cu 0 .1 2 5 7 .3

° 0.5 gram of (NH O1SO4 used since 1 gram caused slight precipitation of CaSO*.

sulfate w as retained. Since the earlier work (20) indicated th a t the precipitate w as relatively rich in sulfate, this shows th a t sulfate can be com pletely removed b y igniting to a sufficiently high tem perature (1200° C .). T he results ob­

tained b y the above procedure are given in T able I.

S e p a r a t i o n o f A l u m i n u m f r o m C a l c i u m , M a g n e s i u m , N i c k e l , C o b a l t , Z i n c , M a n g a n e s e , C a d m i u m , a n d C o p p e r .

According to Lundell and K now les (12), alum inum can be separated from the alkalies, alkaline earths, magnesium , and m oderate am ounts of m anganese and nickel b y precipitating according to th e procedure of Blum (2). T he separation from copper, cobalt, and zinc is not satisfactory, from 4 to 20 mg.

remaining after one precipitation, and from 1 to 10 m g. after tw o, using 100 mg. of alum inum and 50 m g. of the accom pany­

ing elem ent (9). From the analytical qualities of the precipi­

ta te obtained b y the present m ethod, considerably better separations m ight be expected.

I t w as found th a t w hen separate solutions containing 0.5 gram of nickel, cobalt, zinc, m anganese, cadmium, and cop­

per as chlorides, together w ith 4 grams of urea and 1 gram of potassium sulfate were heated overnight on a hot plate, partial precipitation occurred. However, if th e solutions contained 10 grams of amm onium chloride in addition to the above, no precipitate formed. T he effectiveness of the separa­

tion of alum inum from these elem ents, and also from calcium and m agnesium , w as determ ined b y precipitating the alum i­

num from individual solutions containing their chlorides, using th e procedure described above. After filtering and washing, the precipitate w as dissolved in hydrochloric acid, and the am ount of accom panying elem ent carried down w as deter­

m ined b y an appropriate standard procedure. T able II gives th e data obtained.

T hese results show th at the separation of alum inum from calcium, magnesium , m anganese, and cadmium, b y a single precipitation w ith urea in the presence of sulfate, is satisfac­

tory. U sing this m ethod only 0.1 m g. of m anganese is carried down b y 0.1 gram of alum inum in the presence of 1 gram of m anganese, while w ith an amm onium hydroxide precipitation, 1.7 m g. of manganese accom panies the alum inum when these sam e am ounts of the tw o elem ents are used. T he separation from nickel, cobalt, zinc, and copper is not very good, although a single precipitation by this m ethod is a t least as effective

w ith the last three of these elem ents as a double one with amm onium hydroxide.

Since th e final pH values of the solutions were 6.7 to 7.0, which is about the sam e as th a t of B lu m ’s m ethod, it is probable th at th e greater purity of the precipitate obtained b y the present m ethod is due to the reasons m entioned above.

T he gradual increase in the pH of the solution, w hich is uni­

form throughout, allows the major part of the alum inum to be precipitated before the pH rises to a poin t where there is danger of precipitating the more basic elem ents.

P r e c ip ita t io n o f A lu m in u m in t h e P r e se n c e o f S u c c in a te

P r e l i m i n a r y I n v e s t i g a t i o n . In th e exploratory work on th e influence of various anions on the quality of the precipi­

tates obtained w ith urea, it w as found th at those form ed in the presence of form ate, oxalate, succinate, benzoate, and phthalate were dense, while th at formed in the presence of acetate w as flocculent (20). Several workers (1, 3, 15) have reported th at the pH values at which hydroxides or basic salts begin to precipitate show som e variation in the presence of different anions.

A series of determinations with different anions was made to determine the pH necessary for complete precipitation. Solutions of 500-ml. volume, containing approximately 0.1 gram of alumi­

num as chloride, 4 grams of urea, and 10 grams of ammonium chloride together with the amounts of the various salts shown in Table III, were heated in a boiling water bath until the appear­

ance of a slight opalescence. The solutions were then rapidly cooled to room temperature and the pH was determined with a quinhydrone electrode. The solutions were then gently boiled for 2 hours, the precipitate was filtered off, the filtrate tested for complete precipitation, and the pH determined.

Further stu d y of the basic acetate m ethod em ployed by M ittasch (16), Funk (7), and Ivling, Lassieur, and Lassieur (11) failed to establish any conditions w hich w ould give a dense precipitate w hen th e neutralization w as caused by the hydrolysis of urea. T he basic form ate m ethod (5, 8) modified b y heating w ith urea w as unsuccessful, as shown b y attem pts to precipitate alum inum in the presence of nickel. If enough fo n n a te w as present to give a dense precipitate, the alum inum w as incom pletely precipitated, and th a t portion w hich did precipitate showed the presence of nickel. W ith 4 grams of amm onium form ate in the solution, only about 60 per cent of the alum inum precipitated, w hile w ith 15 grams present, about 33 per cent cam e down. W ith m uch sm aller am ounts of form ate, the beneficial effect of the anion on the quality of th e precipitate w as not realized. W ork w ith th e succinate show ed th a t conditions w hich w ould give a dense precipitate and quantitative precipitation could be attained easily if succinic acid w as added instead of sodium succinate, since th e latter causes an im m ediate precipitate.

C o n d i t i o n s f o r C o m p l e t e P r e c i p i t a t i o n o f A l u m i n u m i n t h e P r e s e n c e o f S u c c i n a t e . I t w as found th a t th e am ount of succinate present affected n ot only the character of the precipitate bu t also the com pleteness of the precipitation,

T a b l e III. I n f l u e n c e o f C e r t a i n A n i o n s o n t h e p H o f F i r s t O p a l e s c e n c e a n d C o m p l e t e P r e c i p i t a t i o n

pH at First pH after Anion Salt Used Salt Opalescence®

Grama

2 Hours Precipitation

Phosphate fNH^sHPO«*» 3 2 .3 6 . 1 c Complete

Succinate Acid 5 3 .6 4 .0 Complete

Phthalate K H C8H404 3 3 . 8 4 .9 Complete

Sulfate (N H 4),SO< 1 4 .2 6 . 5 - 7 .5 Complete

Form ate HCOONab 3 4 .8 6 .0 Incom plete

A cetate NaCîHjOï* 3 d 5 .5 C om plete

a pH measured at room temperature, opalescence noted at boiling point.

b Original solution contained sufficient hydrochloric acid to prevent forma­

tion of a precipitate while being brought to a boil.

c Precipitation probably com plete in less than 2 hours.

d Precipitate flocculated too rapidly to allow determ ination of this value.

AUGUST 15, 1937 ANALYTICAL EDITIO N « 359 especially w hen other elem ents were present. Three grains

of succinic acid and 10 grams of ammonium chloride in 500 m l. were sufficient to give a dense precipitate, and complete precipitation of alum inum w hen alone. However, if 0.15 gram of nickel or zinc w as present, th e precipitation of the alum inum w as incom plete w ith 3 grams of succinic acid, but qu an titative if 4 grams or 5 grams were used.

Since the pH of the solution and consequently the complete­

ness of precipitation are dependent on th e duration of boiling, this relationship w as studied in a manner similar to the de­

term ination of the solubility of the basic alum inum sulfate precipitate. T he solutions containing 0.1 gram of aluminum, 4 grams of urea, 5 grams of succinic acid, and 10 grams of am m onium chloride in 500 m l. were gently boiled, after the appearance of turbidity, for the lengths of tim e given in Table IV . T h e determ inations were then com pleted as previously described (20).

T his show s th a t for the com plete precipitation of aluminum by heating w ith urea in the presence of succinate and ammo­

nium chloride, it is necessary to boil gently for 1.5 to 2 hours after the appearance of turbidity, and that this procedure results in a pH of about 4.4.

Q u a n tita t iv e D e te r m in a tio n o f A lu m in u m b y th e S u c c in a t e M e th o d

P r o c e d u r e . The aluminum solution was prepared as de­

scribed in the basic sulfate method. After diluting somewhat, 5 grams of succinic acid dissolved in about 100 ml. of water were added, followed by 10 grams of ammonium chloride and 4 grams of urea. The solution was diluted, heated to boiling, and gently boiled for 2 hours after it had become turbid (40 to 45 minutes after it had commenced to boil). The precipitate was allowed to subside for a few minutes, and after a little paper pulp was added, it was filtered and washed ten times with a 1 per cent succinic acid solution, made neutral to methyl red with am­

monium hydroxide. The precipitate adhering to the beaker was removed as in the basic sulfate method, except that in this instance the small precipitate obtained with ammonium hydrox­

ide was filtered on a separate paper. The combined precipitates were ignited to constant weight in a platinum crucible at 1200° C.

The pH of the filtrate was determined with a quinhydrone elec­

trode, and the amount of aluminum remaining in the filtrate (approximately 0.1 mg.) and in the wash waters (negligible) was ascertained colorimetrically as before.

M o d i f i e d P r o c e d u r e . W hen the entire neutralization is dependent on the decom position of urea, considerable tim e is consum ed before precipitation commences, especially when an acid reducing agent is added as in the determ ination of copper, discussed later. T o avoid this, a partial preliminary neutralization w ith dilute amm onium hydroxide was tried.

W hen this reagent w as slow ly added to a cold solution con­

taining urea, amm onium chloride, and succinic acid until barely turbid, a flocculent precipitate w as rapidly formed on heating to boiling. H ow ever, if it was added dropwise to the h o t solution to the point of faintest opalescence, the precipi­

tate obtained on further heating was entirely satisfactory. It w as sligh tly more bulky than th at obtained w ithout pre­

lim inary neutralization, but was still com pact enough to filter and wash rapidly. I t had the distinct advantage of being more easily retained b y the filter paper.

T a b l e IV. E f f e c t o f D u r a t i o n o f B o i l i n g o n p H o f S o l u t i o n a n d C o m p l e t e n e s s o f P r e c i p i t a t i o n Duration of Boiling0 pH of Solution AljOj in Filtrate

H our 8 M g-/I-

0 .2 5 3 .3 0 J „

0 .5 3 .5 8 1.2

1 3 .9 3 0 .8

1 .2 5 4 .0 1 0 .8

1 .5 4 .1 5 0 .2

2 4 .4 0 0 .2

° After the appearance of turbidity. ,

t Sufficient aluminum left in the filtrate to give a precipitate with am­

monium hydroxide.

T a b l e V. Q u a n t i t a t i v e D e t e r m i n a t i o n o f A lu m in u m b y t h e S u c c i n a t e M e t h o d

Duration

of pH of AljOj AljOj Error

Volume Boiling Solution Taken Found AJjOj

M l. Hours* b Oram Gram M g.

500 2 4 .4 3 0.1 9 1 2 0.1911 - 0 . 1

500 2 4 .5 7 0.1906 0.1903 - 0 . 3

500 2 4 .4 4 0.1906 0.1906 * 0 . 0

500 2 4 .3 2 0.1931 0.1927 - 0 . 4

500 2 4 .2 6 0.1899 0.1899 **=0.0

500 2 4 .2 6 0.1899 0.1 8 9 5 - 0 . 4

500 2 4 .4 8 0.1899 0.1 8 9 6 - 0 . 3

250 2 4 .3 6 0.1911 0.1911 ± 0 . 0

250 2 4 .2 2 0.1903 0.1 9 0 0 - 0 . 3

250 2 4.4 4 0.0957 0.0 9 5 6 - 0 . 1

250 2 4 .3 1 0.0 9 6 0 0.0 9 5 8 - 0 . 2

250 • 2 4.5 3 0.0059 0.0059 =*=0.0

250 2 4 .5 0 0.0057 0.0056 - 0 . 1

250 2 4 .6 2 0.0 0 2 5 0.0 0 1 5 - 1 . 0

250 2 4 .5 3 0.0017 0.0005 - 1 . 2

250 3 4 .7 7 0.0021 0.0021 **=0.0

250 3 4 .9 4 0.0023 0.0023 =*=0.0

M odified M ethod

250 0 .5 3 .7 6 0.1894 0.1887 - 0 . 7

250 1 3 .9 6 0.1897 0 .1 8 9 8 + 0.1

500 1 4 .0 1 0.1897 0.1 8 9 8 + 0 . 1

500 1 3 .9 8 0.1905 0.1 9 0 8 + 0 .3

500 c 1 4 .0 0 0.1903 0.1907 + 0 .4

500 c 1 3 .8 6 0.1909 0.1906 - 0 . 3

500J 1 3 .9 8 0.1901 0 .1 9 0 0 - 0 . 1

500d 1 4 .0 3 0.1 9 0 6 0.1 9 0 6 =*=0.0

a After the appearance of turbidity.

& At room temperature.

c Bromophenol blue used as indicator.

d M ethyl orange used as indicator.

Since turbidity appears at approxim ately the pH at which bromophenol blue or m ethyl orange changes color, it is som e­

tim es convenient to em ploy one of these as indicators. It is, of course, not necessary to neutralize to the point of turbidity, but it is very im portant not to overstep it, since this will cause the form ation of a som ewhat flocculent precipitate on further heating. Table V shows the results obtained using both procedures. A correction was m ade for im purities in the m etal.

Experim ents on the ignition of the precipitate showed that heating for 1 hour at 1200 0 C. w as sufficient to attain constant w eight and to convert it into a nonhygroscopic (corundum) form w hich could be weighed directly in a covered crucible w ithout the necessity of placing it in a covered weighing bottle.

I t was also found th at Coors unglazed porcelain crucibles suf­

fered no change in w eight during such ignition and th ey were, therefore, used in place of platinum in m ost subsequent work.

It is evident that alum inum can be quantitatively precipi­

tated b y heating w ith urea in the presence of succinate and ammonium chloride for 1 to 2 hours after the appearance of turbidity if 5 mg. or more are present, and th a t the tim e can be shortened b y partial preliminary neutralization. W ith smaller am ounts, about an hour longer is required. T h e resulting low pH , combined w ith the granular quality of the precipitate, the slow rate of precipitation, and the homoge­

neity of the solution, should allow m uch more satisfactory separations from the more basic elem ents than precipitation by ammonium hydroxide or even as the basic sulfate.

S e p a r a tio n o f A lu m in u m fr o m O th er M e ta ls T his m ethod w as applied to th e separation of alum inum from a considerable number of other m etals. In all cases the w eight of alum inum taken w as corrected for im purities.

W hen a second precipitation w as m ade, the basic succinate was dissolved from the filter into the sam e beaker by hot, dilute hydrochloric acid and the process repeated. T he im ­ purity in the oxide w as determ ined by suitable m ethods.

D e t e r m i n a t i o n o f A l u m i n u m i n t h e P r e s e n c e o f C a l ­ c i u m , B a r i u m , M a g n e s i u m , M a n g a n e s e , a n d C a d m i u m .

These separations and determ inations were m ade by a single precipitation from a volum e of 250 m l. T able V I shows the results obtained, and indicates clearly that b y this m ethod a

360 IN D U STR IA L A N D E N G IN E E R IN G CHEM ISTRY VOL. 9, NO. 8

T a b l e VI. D e t e r m i n a t i o n o f A l u m i n u m i n P r e s e n c e o f C a l c i u m , B a r i u m , M a g n e s i u m , M a n g a n e s e , a n d C a d m iu m b y

P r e c i p i t a t i o n a s B a s i c S u c c i n a t e

E lem ent Al2Oa AhOj Elem ent Error

Added Taken Found with AljOa AliOj

Gram Gram Gram Mg. Mo.

1 .0 Ca 0.1897 0.1 8 9 5 None - 0 . 2

1 .0 Ca 0.1 9 0 5 0.1 9 0 3 None - 0 . 2

1 .0 Ca 0.1 9 0 5 0.1904 None - 0 . 1

1 .0 Ca 0.1 9 0 3 0.1904 None + 0 . 1

1 .0 Ba 0.1909 0.1 9 0 8 None - 0 . 1

1 .0 Ba 0.1 9 0 5 0.1 9 0 5 None =*=0.0

1 .0 Mr 0.1 9 0 6 0.1904 None - 0 . 2

1 .0 Mg 0.1 9 0 6 0.1907 None + 0 . 1

1 .0 Mg 0.1892 0.1894 N one + 0 .2

1 .0 M g 0.1894 0 .1 8 9 0 N one - 0 . 4

1 .0 M n 0.1 9 0 4 0.1906 0 .3 + 0 .2

1 .0 Mn 0.1 9 0 4 0.1906 0 .3 + 0 .2

1 .0 Mn 0.0 9 4 9 0 .0 9 5 0 0 .2 5 + 0 . 1

1 .0 Mn 0 .0 9 4 9 0.0953 0 .2 5 + 0 . 4

1 .0 M n° 0.1 9 0 3 0.1901 0 .2 - 0 . 2

1 .0 M n° 0.1 9 0 6 0.1 9 0 5 0 .2 - 0 . 1

0 .5 Mn 0 .1 8 9 5 0.1897 0 .2 + 0 .2

0 .5 Mn 0 .1 8 9 0 0.1893 0 .2 + 0 . 3

1 .0 Cd 0.1901 0.1901 < 0 .1 =*=0.0

1 .0 Cd 0.1902 0 .1 9 0 0 < 0 .1 - 0 . 2

1 .0 Cd 0.1 9 0 6 0 .1 9 0 7 < 0 .1 + 0 .1

1 .0 Cd 0.1 8 9 7 0.1897 < 0 .1 =*=0.0

Precipitated from 500 ml.

T a b l e VII. D e t e r m i n a t i o n o f A lu m in u m i n t h e P r e s e n c e o f N i c k e l a n d C o b a l t b y P r e c i p i t a t i o n a s B a s i c S u c c i n a t e

Number

Elem ent of Pre­ Al:Oj AljOa N i or Co Error

Added cipitations Volume Taken Found in AIjOj Al,Oa

Gram M l. Gram Gram Mo. Mo.

1 .0 N i 1 250 0.1 9 0 3 0.1921 1 .8 + 1 .8

1 .0 Ni 1 250 0.1901 0.1919 1 .8 + 1 .8

1 .0 Ni 1 500 0.1905 0.1922 1.3 + 1.7

1 .0 Ni 1 500 0.1901 0.1 9 1 8 1.2 + 1 .7

1 .0 N i“ 1 500 0.1897 0.1 9 1 3 1 .0 + 1.6

1 .0 Ni° 1 500 0.1893 0.1 9 1 0 1 .0 + 1.7

1 .0 Ni 1 500 0.0 0 4 9 0.0 0 5 0 Trace + 0 . 1

1 .0 Ni 1 500 0.0056 0.0057 Trace + 0 . 1

0 . 5 Ni 1 250 0.1919 0.1 9 3 5 1.3 + 1 .6

0 . 5 Ni 1 250 0.1 9 0 5 0.1923 1.6 + 1 .8

0 .1 Ni 1 250 0.1901 0.1904 0 .3 + 0 . 3

0 .1 Ni 1 250 0.1901 0.1903 0 .3 + 0 . 2

1 .0 Ni 2 250 0.1903 0.1903 0 .2 ± 0 . 0

1 .0 Ni 2 250 0.1901 0.1903 0 .3 + 0 . 2

1 .0 Ni 2 500 0.1 8 9 5 0.1893 0 .1 - 0 . 2

1 .0 Ni . 2 500 0.1901 0.1 9 0 2 0 .2 + 0 . 1

1 .0 Co 1 250 0.1894 0.1919 1.9 + 2 . 5

1 .0 Co 1 250 0.1 8 9 7 0.1924 2 .0 + 2 .7

1 .0 Co 1 500 0.1 9 1 3 0.1932 1.2 + 1.9

1 .0 Co 1 500 0.1 9 0 6 0.1 9 2 5 1.2 + 1.9

1 .0 Co« 1 500 0.1 9 0 6 0.1921 1.2 + 1 .5

1 .0 Co° 1 500 0.1899 0.1914 1 .2 + 1 .5

1 .0 Co 1 250 0.0 0 5 8 0.0 0 5 8 Trace =*=0.0

1 .0 Co 1 250 0 .0 0 4 0 0.0043 Trace + 0 . 3

0 .5 Co 1 250 0.0964 0.0977 0 .8 + 1 .3

0 .5 Co 1 250 0.0 9 5 4 0.0 9 6 3 0 .6 + 0 . 9

0 .1 Co 1 250 0.0 9 5 4 0.0954 0 .2 =*=0.0

0 .1 Co 1 250 0.0 9 6 8 0.0971 0 .3 + 0 . 3

1 .0 Co 2 250 0 .1 8 9 5 0.1896 0 .1 + 0 . 1

1 .0 Co 2 250 0.1 9 0 2 0.1 9 0 4 0 .1 + 0 . 2

1 .0 Co 2 250 0.1 8 9 9 0.1 9 0 3 0 .1 + 0 .4

1 .0 Co 2 250 0.1904 0.1902 0 .1 - 0 . 2

° M odified procedure.

single precipitation from 250 m l. will satisfactorily separate approxim ately 0.1 gram of alum inum from 1 gram of the above elem ents.

D e t e r m i n a t i o n o f A l u m i n u m i n t h e P r e s e n c e o f N i c k e l a n d C o b a l t . T able V II shows the results obtained w hen this m ethod is applied to the separation of alum inum from nickel and cobalt.

I t is evident th a t one precipitation will effectively separate 0.1 gram of alum inum from an equal am ount of cobalt or nickel or a few m illigram s of alum inum from as m uch as 1 gram. A double precipitation gives a very satisfactory sepa­

ration of 0.1 gram of alum inum from as m uch as 1 gram of these m etals. T his is a m uch better separation than that obtained by th e use of amm onia, which, after one precipita­

tion, leaves 0.6 m g. of nickel and 4.1 mg. of cobalt ou t of 50 m g. w ith th e alum inum w hen one precipitation is m ade, and 1.2 mg. of cobalt after tw o precipitations (9).

D e t e r m i n a t i o n o f A l u m i n u m I n t h e P r e s e n c e o f C o p ­ p e r . W hen this general procedure is applied to the deter­

m ination of alum inum in the presence of copper, the separa­

tion is incom plete, ow ing to th e relatively low solubility of cupric succinate. If, however, th e copper is k ept in the cuprous state, by th e presence of a suitable reducing agent during the precipitation, the separation becomes entirely satisfactory, as the results given in T able V III show.

When a reducing agent was used, 4 grams of hydroxylamine hydrochloride or 10 ml. of freshly prepared 2 N ammonium bisul­

fite and 10 grams of ammonium chloride were added to the aluminum chloride solution. It was diluted to about 150 ml.

and heated to boiling to reduce the copper to the cuprous state.

When the solution had become colorless, 5 grams of succinic acid and 4 grams of urea were added, and the volume was brought to about 250 ml. Dilute ammonium hydroxide was added dropwise to the hot solution to incipient turbidity, and gentle boiling con­

tinued for 2 hours. The precipitate was filtered off while hot and washed with a hot solution containing per liter 10 grams of suc­

cinic acid and cither 10 grams of hydroxylamine hydrochloride or 40 ml. of 2 ¿V ammonium bisulfite, the wash solution having been made neutral to methyl red with ammonium hydroxide.

The determination was completed as described above.

The main points to be noted are that the copper must be com­

pletely reduced to the cuprous state, and the filtration and wash­

ing must be done hot.

T hese data show th a t alum inum can be very satisfactorily separated from large am ounts of copper b y a single precipita­

tion, b y heating w ith urea in the presence of succinate, am­

m onium chloride, and a suitable reducing agent. A double precipitation w ith am m onium hydroxide w ill usually leave as m uch as 8 m g. of copper out of 50 m g. with the alum inum, w hen precipitating 0.1 gram of the latter (9).

T a b l e VIII. De t e r m i n a t i o n o f Al u m i n u m i n t h e o f Co p p e r

Pr e s e n c e

Cu Reducing Al,Oa AljOa Cu in Error

No. Added Agent Taken Found AljOj AhOa

Gram Gram Gram Mo. Mo.

1 0.1 None 0.0947 0.0 9 7 2 + 2 . 5

2 0.1 None 0.0 9 5 3 0.0 9 7 6 + 2 . 3

3 0.01 None 0.0 9 4 5 0.0956 + 1.1

4 0.0 1 None 0.0953 0 .0 9 6 0 + 0 . 7

5 1.0 NHjO H -H Cl 0.1897 0.1901 o.‘ i ‘ + 0 . 4

6 1.0 N H jO H H C l 0.1903 0.1 9 0 1 0.1 - 0 . 2

7 1.0 N H iO H ’HCl 0.0951 0.0 9 5 2 None + 0.1

8 1.0 NHsOH-HCl 0.0949 0.0952 None + 0 . 3

9 1.0 NHjOH -HCl 0.0953 0.0 9 5 3 None =*=0.0

10 1.0 N HiOH-HCl 0.0951 0 .0 9 5 0 None - 0.1

11 1.0 N H4HSO3 0.1891 0.1 8 8 8 0 .0 5 - 0 . 3

12 1.0 NHiHSOa 0.1891 0.1891 0 .0 5 =*=0.0

D e t e r m i n a t i o n o f A l u m i n u m i n t h e P r e s e n c e o f Z i n c .

T he general procedure applied to th e determ ination of alum i­

num in th e presence of zinc gave the results shown in T able IX , which indicate that, even w ith as little as 10 m g. of zinc present, an appreciable am ount is to be found w ith the alum i­

num after a single precipitation. Only 0.1 to 0.2 m g., how­

ever, is found to be present after tw o precipitations, when as much as 1 gram was originally present. T h e superiority of this m ethod over the use of am m onium hydroxide is obvious from the fact th a t in the latter case as m uch as 10 m g. ou t of 50 m g. of the zinc m ay accom pany the alum inum after tw o precipitations (3).

Since zinc m etal is readily volatilized a t elevated tem pera­

tures, it should be possible to rem ove th e sm all am ount w hich accom panies the alum inum b y ignition in a current of hydro­

gen or w ith carbon.

A single precipitation was made in the usual manner from 500 ml. of solution containing 1.0 gram of zinc and approximately 0.1 gram of aluminum. When the ignition was to be made in the presence of carbon, some paper pulp was added before filtration.

The precipitate was ignited in a covered unglazed porcelain crucible over a Meker blast, occasionally lifting the cover to allow the zinc to escape. After ignition for an hour in this man­

ner, the cover was removed, the remainder of the carbon burned off, and the ignition completed in an electrically heated muffle for 1 hour at 1200° C. In determinations 3 to 6 (Table X ), this oxide, after weighing, was ignited for 1 hour at 1000° to 1100° C.