ANALYTICAL EDITION
182
seems to have required special technic (17, 26). the authors believe that their modification has removed the objection raised by Mackay (l‘i‘),that the “volumetric determination of sulfuric acid as benzidine sulfate proves troublesome unless great care and high analytical skill are employed, and is, therefore, unsuitable for use as a routine determination to be applied by an untrained staff Although the results above have been confined to coals and cokes. the authors have found that it is also applicable to fuel oils. I n fact there is no reason to believe that it could not be used as a fairly general method for sulfur in organic compounds, judging from the fact that Garelli and Saladini (8) reported that an oxygen bomb can be used for the oxidation of organic compounds. Since the method is both accurate and rapid and has proved particularly suitable as a routine method, it seems desirable for consideration as an alternate to the present standard methods.
.”
LITERATURE CITED (1) Am. 500. Testing Materials, Standards, Pt. 11, p. 689 (1930). (2) Bisson and Christie, J. IND.ENQ.CHEM.,12, 485 (1920). (3) Chatron, Bull. SOC. chim. biol., 13, 300 (1931). (4) Christie and Bisson, J. IND.ENQ.CHEM.,12, 171 (1920). (5) Cooper, H. M. Private communication. (G) Cuny, J. pharm. chim., 12, 485 (1930).
Vol. 5 , No. 3
(7) Friedheim and Nydegger, 2. angew. Chem., 20, 9 (1907). (8) Garelli and Saladini, Atti accad. sci. Torino, Class sci. fis. mal. nut., 66, 163 (1931). (9) Gauvin, Bull. sci. pharmacol., 21, 541 (1914). (10) Heozko, 2.anal. Chem., 51, I (1912). (11) Hillebrand and Lundell, “Applied Inorganic Analysis,” p. 682, Wiley, 1929. (12) Holliger, 2. angew. Chem., 22, 436, 493 (1909). (13) Kahn and Leiboff, J . Biol. Chem., 80, 623 (1928). (14) von Knorre, Chem. Ind. (Germany), 28, 2 (1906). (15) Lesure and Dunez, Bull. soc. chim. b i d , 10, 879 (1928). (16) Leulier and Fouillouze, Bull. sci. pharmacol., 32, 120 (1926). (17) Mackay, J. SOC.Chem. Ind., 49, 233T (1930). (18) Meldrum and Newlin, IND.ENQ.CHEM.,Anal. Ed., I, 231 (1929). (19) Milller, Ber., 35, 1687 (1902). (20) Pohoreoka-Lelesz, Bull. soc. chim. biol., 9, 263 (1927). (21) Raizisa and Dubin, J . Biol. Chem., 18, 297 (1914). (22) Rasohig, 2. angew. Chem., 16 (26), 617 (1903); 16, (34),81C (1903). (23) Schmidt and Honn, Papier-Fabr., 27, 813 (1929). (24) Selvig and Fieldner, JND. ENQ.CHEM.,19, 729 (1927). (26) Stanton, Fieldner, and Selvig, Bur. Mines, Tech. Paper 8, 15 (1929). (26) Btriger, Chemist-Analyst, 26, 6 (1918). (27) Stuber and Kulvarskaya, J . Chem. Ind. (Moscow),7, 163 (1930) (28) Vladimirov, Ibid., 7, 161 (1930). ‘ (29) Zemlyanitzin, Ibid., 5, 1178 (1928). RBICEIVED January 3, 1933. Presented before the Division of Gas and Fuel Chemistry at the 85th Meeting of the American Chemicrtl Society, Washington, D. C., March 26 to 31, 1933.
Estimation of Small Amounts of Antimony in tiopper a
N
BARTHOLOW PARK AND E. J. LEWIS,Michigan College of Mining and Technology, Houghton, Mich.
T
HE separation of small amounts of antimony from large amounts of copper is a time-consuming operation. Several methods are in current use, probably the best known depending upon the tendency of a ferric hydroxide precipitate to occlude antimony. This method of separation is open to criticism, as has been noted by Blumenthal (I), who recommends the addition of potassium permanganate and manganese sulfate to the acid solution of copper. Manganese dioxide precipitates and carries down the antimony. Working with rather large amounts of antimony, about 50 mg. in 25 to 100 grams of copper, he succeeded in recovering it completely by means of a double precipitation with manganese dioxide. This procedure has been modified somewhat and combined with a spectrographic method for the purpose of estimating the extremely small quantities of antimony which are present in the best grades of refined copper. The results given in the tables were obtained by the following method: Five hundred rams of copper were boiled with concentrated hydrochloric acif, washed with distilled water, and dissolved in concentrated nitric acid. The solution was boiled until free from fumes, diluted to about 2 liters, and ammonium hydroxide added until a slight permanent precipitate formed. This was dissolved with a little nitrio acid and the solution again heated t o boiling. Ten cubic centimeters of 3 per cent potassium manganate solution were added and the boiling was continued?:; about 5 minutes. Fifteen cubic centimeters of a 5 per cent solution of manganous sulfate crystals were added and the boiling was continued for 10 or 20 minutes more, after which the beaker was allowed to stand undisturbed overnight. The supernatant liquid was carefully decanted into a clean container and the precipitate brought onto an asbestos and glass wool filter, where it was washed free from copper nitrate with cold distilled water, using suction. The filtrate and washings were combined with the decanted portion, heated to boiling, and treated with permanganate, etc., as before. The precipitate was
dissolved b pouring 50 cc. of concentrated hydrochloric acid over it, followediby a little water. The second recipitate was se arated by putting the entire solution througg the filter, and ager washing was dissolved in the hydrochloric acid solution of the first. The solution of man anese dioxide and antimony was diluted to about 400 cc. an8 neutralized with ammonium hydroxide, after which 10 cc. of concentrated hydrochloric acid were added. Hydrogen sulfide was passed into the solution until precipitation ceased. The solution was allowed to stand undisturbed overnight and then filtered through glass wool and asbestos. The sulfides were washed with water and dissolved by P g hot concentrated nitric acid over the filter, followed by ot concentrated hydrochloric acid and h a l l y by distilled water. The filtrate was evaporated t o 10 cc. in an open beaker on a hot plate. One- or two-tenths cubic centimeter, accurately measured, of this concentrated solution was placed in a hole bored in the top of a pure graphite electrode. After drying a t 100’ C., the electrode was arcked for one minute, using a current of from 10 to 12 amperes a t about 50 volts. The resulting spectrogram was compared with others prepared in the same way from antimony-free copper to which had been added known quantities of antimony. A comparison of the intensities of the antimony lines a t 2598 and 2878 in the spectrograms of the known and unknown samples was made in the manner described by Nitchie (6). Another set of standards was prepared directly from pure copper chloride and accurately weighed antimony trioxide. The required amounts were dissolved, made up to 10 cc., and portions placed directly in graphite electrodes. The standards checked those prepared by the more lengthy process within the limits of error of the method, thus proving the completeness of the separation obtained in the process. The sensitivity of the method may be increased by concentrating the antimony solution to a smaller volume, but this
INDUSTRIAL AND ENGINEERING
May 15, 1933
necessitates a further separation of antimony from copper by means of sodium sulfide after the sulfide precipitate has been obtained. A few samples were treated in this manner, but no apparent increase in accuracy resulted. The presence of as little as 2 parts of antimony in 10,000,000parts of copper can be shown by this procedure. ON SAMPLES OF TABLEI. ANTIMONYDETERMINATIONS COMMERCIAL COPPERFROM VARIOUSSOURCES SAMPL~
TABLE
CHEMISTRY
11. ANTIYONYI N UNMELTED COPPER SUPERIOR MINES
FROM THE
SOURCE
OB
LAKE
ANTIMONY
%
Mass copper Mass copper
Maas copper Mass copper Mass copper Mass copper
Copper oxide
ANTIMONY
%
< 0.00006 0.00002 0.00004 0.0002 0.0004 0.0004 0.001
183
Ahmeek mine Calumet and Hecla conglomerate Champion mine Isle Royale mine Osqeola mme incy mine alumet and Hecla leaching plant
?
< 0.00002 < 0.00002 < 0.00003 < 0.00002 < 0.00002 < 0.00002 < 0.00002
LITERATURB CITED (1) Bl:menthal, 2.anal. Chent., 74, 33 (1928). (2) Nitchie, IND. E m . CHEW,Anal. Ed., 1, 1 (1929).
RECEIVED December 8, 1932.
An Improved Head for Laboratory Fractionating Columns E. C. WAGNERAND J. K. SIMONS Harrison Laboratory of Chemistry, University of Pennsylvania, Philadelphia, Pa.
A
STILLHEAD for ordinary laboratory distillations on a small scale is best made wholly of glass, fitted to the column (or to several columns of different lengths or types) by means of a ground-glass seat. The head should be strong, well balanced, and free from internal complications and also from readily broken external arms If not in one piece, its parts should be connected by ground joints, rather than by rubber tubing, stoppers, etc. The head should be so designed as to provide variable reflux up to total reflux, to permit fairly accurate determination and control of the reflux ratio and accurate observation of the boiling point of the material being condensed, and also to deliver a cool distillate. Examination of a number of published designs (1-7, 9-19) shows that these qualifications are not well combined in any one head.
DESIGNOF HEAD It is believed that the design shown in Figure 1 satisfactorily incorporates the desirable features mentioned. The functions of the ground-glass seat A , the multiple ports B , and the drainage tube C are obvious. Partial condensation of vapors, yielding primary reflux, is effected by condenser D, which is cooled by water or air and is inserted through ground joint d. To obtain greater condensing surface condenser D may be made with a somewhat bulbous tip. The connecting arm E (which may be omitted) eliminates a possible dead vapor space about D. Condenser G is of double spiral type, and is seated in ground joint H . Condenser 1 reduces the temperature of the condensate. If high-boiling liquids are to be distilled, condensers G and I may be cooled by means of a current of air drawn through them, or by a stream of water passed very slowly, so that temperature differences between the hot vapor channels and the parts G, H , I , J, and K will not set up dangerous strains. The connecting tube J is of small bore (about 2 mm.), and is sloped as shown. During distillation part or all of the condensate from G and I may be returned to the column through this tube, thereby increasing the reflux, the distribution being determined by means of stopcock K . It is intended, however, that most of the reflux be produced
by condenser D, thus relieving condenser G of heavy duty during ordinary distillations, while permitting operation at high or even total reflux. With high-boiling liquids it may be necessary to use condenser D little or not a t all, as the incidental condensation in the head and the reflux through J may yield the desired reflux ratio. Tube J, because of its reduced bore, remains sealed with liquid even when all the condensate is drawn off as product. The slope of J should be slight, and the stopcock placed close to the junction, to minimize the volume of liquid held up at this point. The head is insulated, as indicated in the figure, by a covering of magnesia cement, applied as a paste made with water glass. The reflux ratio is ascertained by c o u n t i n g drops from C and from L. Drainage tube C is visible, as the column is glass-jacketed. The short enclosed-scale thermometer P is seated in a ground joint, 'the inserted half of which is i n t e g r a l with the thermometer jacket. The thermometer is graduated from 20' to 300" in 1'; the length of the scale is 8.5 cm. Temp e r a t u r e s are observed through a short telescope lens (the type f u r n i s h e d w i t h t h e Pregl microazotometer is satisfactory), and can be read to 0.1'. The thermometer is calibrated for immersion t o the ground joint. The arrangements shown are considered prefe r a b l e to t h e use of a thermometer-well long FIGURE 1. DIAGRAM OF STILLenough for total immersion HEAD Reduction is to one-fourth of actual of the mercury column, since Hose connections of condensers such a space, when at the size. U and I are in the rear.
