‘16) l l e h t a , Biochem. J . , 19, 958 (1925). 117) hlonier-\Villiams, J . Chem. Soc., 119, SO3 (1921). $ 1 8 ) O’Dwyer, Biochem. J., 20, 656 (1926). (19) Ost and Wilkening, Chem.-Ztg., 34, 461 (1910). ( 2 0 ) Paloheimo, Biochem. Z., 165, 463 (1925). ; 2 1 ) Powell and Whittaker, J. Chem. Soc., 125, 3Z7 ( 192Aj; 127, 132 (1925). (22) Pringsheim, ”Polysaccharide,” p. 96, Berlin, 1973. (23) Rege, Ann. A p p l . B i d , 14, 1 (1927). (24) kiefenstahl, 2. angew. Chem., 37, 169 (1924).
(25) Schmidt, Hoag, and Sperling, 1922-1925. Ber., 54, 1860 (1921); 55, 1530, 1534 (1922); 56, 23 (1923); 58, 1394 (1925). (26) Schorger. J. IXD.ESG. CHEM.,9, 556 (1917). (27) Schwalbe, “Die chemische Untersuchung pflanzlicher Rohsto5e t i n d der daraus abgeschiedenen Zellstoffe,” Hofmann, p. 131, 1920. (28) Schwalbe, Papier-Fabr., 23, 174 (1925). (29) Waksman and Stevens, Soil Science, 26, 113 (1928). (30) Waksman a n d Tenney, I b i d . , 24, 275, 317 (1927). (31) Willstatter and Zechmeister, Bev., 46, 2401 (1913). (32) Wohl a n d Blumrich, Z . angeio. Chem., 34, 7 (1921).
Application of Microscopic Analysis to Mixtures of Metals and Alloys’ Willet F. Whitmore and Frank Schneider2 THE POLYTECHSIC IIISIITUTE,BROOKLPN,h-.Y.
In order to employ microscopic qualitative analysis or prevent identification of to the fullest extent in industrial work it has been the constituents. The lack microscopic tests over necessary to devise a new system of separation of the the ordinary methods of information on the bemetals. A study has therefore been made of the most havior of the reagents to mixof qualitative analysis is obuseful microscopic forms for the identification of certures has limited the applivious when one compares, for tain metals, and the modification of some of the standexample, the microscopic test cation of microscopic tests to ard crystal forms caused by the presence of other metals for tin with the so-called wetconfirmatory tests. E m i c h has been investigated. Photographs of the charactermethod test. I n the latter (S), a noted authority on miistic forms obtained with typical mixtures, showing the presence of tin is concroscopic methods, says: these modifications in form, are submitted. firmed by the reduction of B e h r e n s h a s a p p l i e d his On the basis of the above, and other considerations, mercuric chloride, and the methods to separations, which a new plan of qualitative analysis especially adapted formation of the i n s o l u b l e are admittedly not possible in to microscopic procedure has been developed. This white mercurous chloride conthe case of an unknown mixture plan eliminates the use of hydrogen sulfide, shortens in which all important elements stitutes the entire test. I n m a y be p r e s e n t . Schoorl, the time of analysis, permits working with small microscopic analysis, on the therefore, applied the micro amounts of material, and dispenses with half the filother hand, the tin itself is chemical analysis only to the tering operations required when the usual wet method p r e c i p i t a t e d a s stannous separation within a group and oxalate and the presence of the of analysis is employed. to the identification of a single tin ascertained, not only bv ion. the presence of a precipitate; but also by the color and crystalline form of that precipitate. The time required to make the Behrens and Kley (1) have used the ordinary methods of test is also greatly reduced. It is apparent, therefore, that separation-i. e., with hydrochloric acid, hydrogen sulfide, a system of analysis with such obvious advantages is one of etc.-and have used the microscopic tests in place of the usual great utility, which should be developed t o a high degree of confirmatory tests. This does not utilize the potentialities of microscopic analysis t o the fullest extent. efficiency. I n order to employ these elegant and sensitive methods of The microscopic identification of an element by chemical methods is accomplished by transposing that element into a attack, it should be possible, after a study of the interferences, known crystalline form possessing a definite color, using any t o devise a new method of separation which would conform in suitable reaction. The substance to be tested is dissolved ease and speed of manipulation to the final microscopic in a suitable solvent and a drop of this solution is placed on a tests. This can be accomplished by utilizing all the possimicroscope slide. The reagent is then added t o the drop bilities for identification without further purification and also either in solid or dissolved form. The resulting precipitate avoiding numerous filtrations, gas precipitations, etc. Sevis observed under the microscope. Since most of the forms eral attempts have been made by other investigators t o arrive suitable for this purpose are salts, one of the well-known reac- a t this end, but all the proposed methods have a t least one tions for salt formation is generally employed. The most serious drawback. Chamot ( 2 ) gives a plan using group reuseful of these reactions, so far as chemical microscopy is agents, but no separation is involved. The authors have concerned, is the method of double decomposition. Accord- made a careful study of the effect of these reagents on mixingly in the detection of a basic element, a n acid or a soluble tures of metals and the results of this study show that i t is alkali salt whose anion combines with the metallic element is impossible to identify several metals simultaneously except in a few limited cases. The fact that some separation was added to give a relatively insoluble crystalline product. The microscopic tests, in their present stage of development, necessary was recognized by other investigators. Zepf (e), are limited in their applicability, however. The chief diffi- T.onginescu and Chaborski (d), and Martini and Shamis (i) culty lies in the fact that some of the best reagents can be ap- suggest plans of analysis but either limit themselves to a plied t o more than one element and when dealing with mix- small group of metals or do not take the interferences comtures the resulting interferences may seriously interfere with pletely into account. The authors have therefore attempted t o furnish a plan of * Received November 27. 1929 * This paper is based upon a thesis presented by F r a n k Schneider in analysis which will provide sufficient separation t o prevent interference with the final tests for each element, and include partial fulfilment of t h e requirements f o r t h e degree of bachelor of science all metals usually encountered in qualitative analysis. The in chemistry a t t h e Polytechnic Institute of Brooklyn.
HE superiority of the
T
L Y - 4LY TIC'd L E D I T I O S
Figure 1-Stannous
Oxalate
F i g u r e 2--Sodium A n t i m o n i a t e
Figure 5-Caesium B i s m u t h ( A n t i m o n y Iodide)
Figure 4-Ammonium Magnesium Arsenate
1701.2,
so. 2
Figure 3 -Potassium B i s m u t h Sulfate
F i g u r e 6-Cobalt M e r c u r i thiocyanate
alkali and alkali-earth groups have been omitted frmn this precipitates should he washed a t least twice. tlic first ivadiiiig> scheme, since their identification and separation liaw been n - ~ l l to be joined with the filtrate. --I11the final testa for the individual elemeiits are given as developed (1, 3 ) . reconiniended by Behreiis and Kley (1). General Directions The sample to be analyzed. in shavings or some other finely divided form. should weigh 0.25 t o 0.5 gram. If niicro-apparatus such as described by Emich ( 3 ) is available, the amount can be reduced considerably. S c h e m e of Analysis Add concd. "01; evaporate t o dryne.is: dissolve in HiO; filter Filtrate; add S H , O H and A-HsCl; filter
Residue, dissolve in concd. H&O4 1
Sn
1
Sb
1
1
bi
Residue; kdd Na?O?and
Filtrate; a d d HnO!,
S a O H ; filter
boil and filter
As
Residue, dissolve in acetic acid
Fi!tkate. acidify
Residue; acidify
1
I - -
~
' Hg
I Fe
I
.\I
l
l
Fi!trate: acidify; add S a 6 O s and S H I S C S ; filter I Filtrate
I
P b Cr M n SICo
Cu
Z n Cd S i 1 I g
I t is essential to keep the \-olume of the sdution as small as possible, as t,he final tests are made on the micaroxope slide and a large volume is obviously out of the que~tioii. The volume should never exceed 35 cc. I n the filkations where a large amount is to he handled R small funnel filter and auction or a cerit,rifug-eis used. but in making tests on the slides decanting will often suffice. All
Plan of Separation
To 0.25-0.50 grain of the sample in a n evaporating disli add concentrated nitric acid and evaporate over a water bath to a moist solid or sirupy liquid condition (l).'J I d d watcr arid e\-aporate again to a moist state. Extract with- hot water, but do not boil. Filter through double filter paper. RESIDUE-oxides of tin, antimony, arsenic, and hisinutli. C h u p I. FILTRATE-sitrates of iron. chroinium, aluininurn, lead. zinc, cadmium, copper, cobalt, nickel, magnesium, niaiiganese, and mercury. Add excess aininonium chloride and ainmoiiiuiii hydroxide. Filter. (2) REsIDuE-Hydroxides of iron, chromium, ahminuin. aiid lead and mercuric aniido-nitrat,e. Group 11. FILTR.\TES--Sitrates and ammonia salts of zinc, cadmiuiii. copper. cobalt, nickel, magnesium, manpaiieae. Add hyclrogeri peroxide (3) and boil for five minutes. Filter. RE3IDUE-oXide'; of nianganese; cobalt: and possibly iiickel (4). Group 111. FILTRATE-sitrates and ainmonia salt.; of zinc. cadiniuiii, copper, magnesium. and nickel. Group I]-. .Votes--(lj Care must he exercised to prevent decomposition of the nitrates into insoluble oxides. Practice will enable the analyst to determine for himself the proper state of dehydration. 3 Xumerals in parentheses in the Plan of Separation and Analysis o i t h e Groups refer t o the notes a t the end of each group treatment.
.
I.YDLySTRI.4L d S D E S G I S E E R I S G CHEMISTRY
April 15. 1930
Figure 7-Potassium Copper Lead Sitrate
Figure 10-Copper Mercurithiocyanate
Figure 8-Silver
Dichromate
Figure 11-Zinc Mercurithiocyanate
(2) The volume must be kept as small as possible a t this point and the filter covered with a watch glass t o prevent oxidation of the manganese. ( 3 ) The solution should contain a n escess of ammonium hydroxide a t this point and a t the end of the boiling. If an excess is not present, more ammonia must be added. (4). ,Some nickel may be oxidized at this time, b u t the osidation is incomplete and the nickel must therefore be tested for in both groups.
Analysis of the Groups
GROUPI-The residue from the nitric acid treatment is placed in a small beaker aiid heated, gently a t first, with aqua regia. The solution is then boiled to expel excess nitric acid and divided into two parts. I n cases where the tin content of the metal is high, some stannic oxide will remain irisoluble after this treatment, but enough tin will go into solution to give a good test for the element in any case. 1-To the first part, water is added and an iron nail dropped in. The solution is slightly warmed to start, the action and then is allowed to stand. After about a half hour the clear liquid is decanted and tested for tin with gold chloride or oxalic ac,id. (Figure 1) 2-The second part is evaporated almost to dryness and divided into three parts (I): ( a ) The first part is boiled with a few drops of concentrated potassium hydroxide solution, cooled, and a drop tested on a slide with sodium chloride. It is often necessary to add more sodium chloride, as the amount necessary depends upon the amount of potassium hydroxide used. The characteristic lentil-shaped or prismatic crystals of sodium pyroantimoniate are evidence of t,he presence of antimony. (Figure 2 ) (6) The second part is dissolved in the least possible
Figure 9-Caesium Aluminum Sulfate
Figure 12-Cadmium Mercurithiocyanate
amount of concentrated sulfuric acid, and a drop of this solution is merged on a slide with a drop of concentrated potassium sulfate solution. Colorless hexagonal plates of potassium bismuth sulfate show the preRence of bismuth ( 2 ) . (Figure 3) ( c ) The third portion is dissolved in arnmoriiuiii hydroxide aiid filtered or decanted if a precipitate forms. The filtrate is placed on a slide and a kernel of magnesium or calcium acetate added. The characteristic H-shaped crystals of ainnionium magnesium aryenate show the presence of arsenir. (Figure 4) Notes-(1) At this point it may be well to test for the presence of antimony and bismuth with caesium chloride and potassium . iodide. Crystals of these two salts are placed a t opposite sides of the test drop and the appearance of red or orange hexagons shows the presence of antimony or bismuth or both. (Figure 5 1 (2) Sometimes these plates will be circular at first b u t turn into hexagons later.
GROUP11-The residue is dissolved on the filter paper in the least amount of dilute hydrochloric acid, washed into a beaker, and sodium hydroxide aiid sodium peroxide added. The solution is boiled and filtered. Residue: Group IIA, iron and mercury oxides. Dissolve in hydrochloric acid and take two test, drops. To the first add potassium ferrocyanide. Blue precipitate indicates iron. Seutralize the second drop with ammonia and add ammonium thiocyanate and cobalt chloride. Clusters of blue needles show mercury. (Figure 6) Filtrate: Group I I B , sodium aluminate, chromate, and plumbate. Acidify with acetic acid (1). Divide into three parts: 1-To the first part add copper acetate solution aiid to a
A S A L Y T I C AL E D I T I O S
1%
Vol. 2 ,
so.2
test drop of this solution add a kernel of potassium nitrite. Black cubes show the presence of lead (Figure 7 ) . 2-Add a drop of nitric acid to the second portion, warm, and add a kernel of silver nitrate. Prismatic crystals of varying shades of red indicate the presence of chromium. (Figure 8)
thiocyanate. Blue clustered needles show presence of cobalt. (Figure 6) To another test drop of the ammoniacal solution, add a kernel of dimethyl glyoxime. Red or pink needles show the presence of nickel. (See note 4 under Separation.) GROUPIV-Acidify the solution with hydrochloric acid and add sodium sulfite and boil. Add ammonium thiocyanate solution, cool, and filter. Residue: Copper thiocyanate. Dissolve in ammonia and add mercuric chloride. Green clusters of radiating needlrs shorn the presence of copper. (Figure 10) Filtmte: Chlorides of zinc, cadiiiium, nickel, and magnesium. Make solutioii a 1k a li ne w i t h ammonium liyclrosidc. Divide into three parte: 1-To the first part acid ainiiioiiiuiii niercuri-t,hiocyanate. Feathered m i s s e s indicate zinc; colorless prisms ~ I ~ C the JW p r e s e n c e of c a d m i u m ; triangular or arrowhead-shaped crystals slion prwencc of both zinc and cadmium. (Figures Figure 13-Mercuri-thiocyanates Figure 14-Ammonium Magnesium of Zn a n d Cd ( 1 : l ) 11, 12, and 13) PhosDhate i-To the second portion add kernel (Jf 3-Add a few drops of concentrated hydrocliloric acid and dimethyl glyoxime. Pink or red needles show the presence to a test drop add a very small amount of concentrated cae- of nickel. 3-Add kernel of ammonium phosphate to the third part. sium bisulfate solution. The colorless alum crystals indiCharacteristic four-armed feathery crystals of ainnioniurn magcate the presence of aluminum. (Figure 9) Note-(l) If lead and chromium are both present, lead nesium phosphate shorn presence of magnesium. (Figure 14) chromate will be precipitated upon acidifying the solution and no further tests for these two metals are necessary.
GROUP111-Fuse part of the precipitate with sodium carbonate and sodium nitrate o n a platinum spoon. A green color shows the presence of manganese. Dissolve the remainder of the precipitate in hydrochloric acid and neutralize with ammonium hydroxide; filter if necessary. To a test drop add a drop of ammonium mercuri-
L i t e r a t u r e Cited (1) Behrens and Klep, "biikrochemische Analyse," 1'01. I. (2) Chamot, "Elementary Chemical hlicroscopy," 2nd ed., p . 414. (3) Emich, "Lchrbuch der SIikrochernie," 2nd e d . , p , 8. 173 (4) Longinescu and Chaborski, Bd1. ciiim. pure a p p l . , 26, 3 (1023; ; Client. Z e n f v . , 95, 944 (1924). ( 5 ) Martini and Shamis, "Trabajos al seEundo congreso de guimica l3ueno3 Aires," 1924. (6) Zepf, J2eta1lbOrse. 13, 65% (1923).
Substitute for Amalgamation in Testing Bituminous Materials for Melting Point, Ductility, and Float Test' Hans Eisner IllPERIAL
OIL REFISERIES, LTD.,S A R S I A , OST.
HE melting point (S), ductility (1, S), and float ( A ) tests for bituminous materials are performed in most laboratories by indii7iduals without chemical training. and large quantities of mercury are often left on the plate after amalgamation. Stock ( 2 ) has shonn that 1 cubic meter of air containing 0.001 mg. of mercurial vapor is injurious to health and chronic poisoning will result n-ith prolonged contact. The layer of mercury on the plate mhen coming in contact with the hot bituminous material gives off poisonous mercurial vapors and, as a result, not only the man who is working with it, but also other people, are affected. I n the writer's laboratory an attempt was made to replace this amalgamated plate. The first experiments were with highly polished plates, in the hope that the sample could be easily removed. These attempts failed, as the asphalt stuck tenaciously to the plate, showing that the mercury forms an isolating film between the asphalt and the plate. The next experiment was to cover the plate with a material which must form a thin layer soluble in water-e. g., glycerol. This gave better results. It was observed, however, that the glycerol would not retain a continuous film if the plate 1
Received January 11, 1930.
wa3 polished. The application of glyccrol to a rough, unpolished plate gave better results. Should the surface of the brass plates be too smooth, the surface should be first cleaned and then etched with acid. On applying the glycerol to the surface prepared in this manner, it was found that the film remained unbroken; in fact, a great improvement over a rough, untreated surface was noted. The molds and rings could be taken off the plate with greater ease than when mercury solution had been applied for amalgamating. I n this laboratory etched plates of brass and staiiilesa steel give perfect satisfaction. All impurities are removed from the surface with solvent naphtha, carbon bisulfide, or carbon tetrachloride before applying the glycerol, one drop of xhich is quite sufficient to coi-er one square inch of surface. The quantit,yof glycerol is small and the worker is, a t all times, free from danger of acid burns or mercury poisoning. I n this laboratory the amalgamation of plates and molds has been replaced entirely by the use of glycerol. (1) Am. SOC. Testing Materials, Tentative Method D113-26T (1828). (2) Stock, Z. a n g e v . Chem., 41, 663 (1928). (3) U. S. Dept. Agr., Bull. 1216, Method 53, p. 81. (4) Ibid., Method 50, p. 79.
