V O L U M E 19, NO. 9
666 111. Influence of Neutral Salts Anal>-& I'res?iJt
I'i,;zs;ium Bromide Found Error
011
'
Salts .\dded
.lli!~i'mole 0 0 0 0 t!
7860 is65 (8i5 is70 i850
Accuracy of
Grams
ACKNOWLEDG>lEST
0007 0002 0008 0003 -0 0 0 i i -0 -0 0 0
0 3345 0 Ti60
-0 0019
0 i784 0 3370
-0 0133 0 0006
0 3346
-0 0018
0 3263
-0 0101
The authors are grateful to R. Bloch, of Palestine Potash, Ltd., Jerusalem, for useful discussions in the course of this investigation. One of the authors (31.I,.) is indebted to Palestine Potash, Ltd., Jerusalem, The Lodzia Textile Co., Ltd., Tel-hviv, and Ata Textile Co., Ltd., Haifa, for a grant which enabled him to carrv out this investigation.
-0 O l O i
Table TV. Determination of Various Amounts of Bromides IiBr Solutwn 10.00 10 00
5.UP 5.02 4 (!4 4 04 2 00 2.00
(pH 9 0 0 , temperature lSJ C.) 0 1 .v Potassium Bromide SaClO Ysed Present Found
30 30 15 15 15 1.5 15
15
Khen the sample solution contains less than 0.04 gram of bromide an accurate analysis may still be carried out by using 0.04 A- hypochlorite, 0.04 S arsenite, and 0.02 .V iodine solutions. The amount of phenol added should be proportionally smaller, whereas the other conditions remain unchanged.
101.50 101.50 50.95 50.95 41.00 41 00 20.30 20 30
101.51 101,5l 50.94 50.92 41 05 41.03 20 32 20.29
Error
+o 01 +o 01 -0 01 -0 03
+ O 05
+o
+o
03 02
-0 01
do not interfere n-ith the analysis. .It, higher ratios considerable errors axe encountered, because the hypobromite is not completely destroyed by phenol and alkali. The disturbing effect of the alkaline earth hydrosides is due to the fact that they tend to absorb hl-pobroiiiite. Lvhich is subsequently not attacked by phenol. This dificulty could possibly be overcome by conversion of tlie calciuni and magnesium ions into soluble compleses-e.g., of hesanietaphojpliates. Experiments in this direction are to be carried out, and it is hoped that the method will also prove suitable of bromine brines, xhich usually contain a high lciuni and magnesium salts. Table IV s h o m the results of a series of analyses of various amounts of potassium bromide, carried out a t pH 9.0. About twice tlie theoretical quantity of sodium hypochlorite \vas used. (In general, an excess of 15 to 20%,is sufficient.) On the basis of these results, the follorving procedure for tlie determination of bromide ions in the presence of chloride ions is recommended. REAGENTS
Reanent; reouired are those used in the work described in the previous paper (3I . The, Iwtnr ot the 0.1 S sodium hvuochlorite solution should - ~~. be dete:inin~tlon the day the bromide analyses are cari,ied out. The reagents nntl the samples for analysis should not contaiii reducing agent3 or ammonium salts. PROCEDURE
to 0.08 gram of potassium bromide. n Erlenmeyer flask of 300-mI. capacity, 15 nil. of hypochlorite are added. The mixture is buffered 1 of 1.7 t o 2.0 nil. of a 5 7 boric acid solution, thus !tal volume to 25 nil. After 5 minutes, 6 ml. of 8 ml. of 0 . 5 7 phenol solution are rapwith vigorous shaking. If the initial aiger than 8 to 10 ml., more alkali should lit, added i n order to bring the final alkalinity to a t least 0.25 S. Slinking is continued for 7 to 10 seconds and then 25 nil. of 0.1 S sodium arsenite are added from a 50-ml. beaker. The 50-nil. benker is rinsed tlvice n-ith distilled water, and then, 5 minutes later, rinsed again with 75 ml. of 5% sodium hicarbonate solution. .icetic acid, 3 S is then added dropwise with vigorous shaking until carbon dioside begins to be evolved. The tit,ration is performed with 0.05 -V iodine solution in the presence of starch, until a permanent light blue color appears. The temperature during titration with iodine should not be over 20' C.
LITERATURE CITED
Bloch, R., Farkas, L., and Lewin, AI., unpublished results. Dixon, T. F., Biochem. J . , 28, 4 8 ( 1 9 3 4 ) . Farkas, L., and Lewin, M . , ASAL. CHEM.,19, 602 ( 1 9 4 7 ) . Kapur, P. L., Verma, M.It., and Khosla, B. D., Ibid., 14, 157 (1942).
Kolthoff, I. XI., and Yutsy, H. C., ICid., 9, 75 ( 1 9 3 7 ) . Meulen, J. H. van der, C'hem. Weelzblad, 28, 82 ( 1 9 3 1 ) . Steiiger, V. .I.,and Kolthoff, I . M.,J . A m . Chem. Soc., 57, 831 (1935).
Willard, H. H., and Heyn, A . H. -I.,ISD.ESG. CHEM.,AXAL. E D , ,15, 321 ( 1 9 4 3 ) . PARTof a thesis submitted by Xlennchem Lewin to the Senate of the Hebrew University, Jerusalem, Palestine, fur the Ph.D. degree.
Hydrogen Discharge Tube GEORGE B. ,IRNOLD
ASD
LEON DONN
Beacon Research Laboratory, The Texas Company, Beacon, S. Y
T
HE high-precision Abbe-type refractometers, recently introduced, 'E, provided with suitable source of illumination for the C (6563 A.) and F (4861 A) lines of the hydrogen spectra, m:ilie possible conventional dispersion measurements of much greater accuracy than those obtained by the method of compensator readings. Many types of hydrogen discharge tubes have heen proposed for the production of the hydrogen spectra (1, S-b) and the description of yet another type would be of little value unless that type of tube offered particular advantages. The tube described in this paper may be operated continuously for several hours \Tit11 little or no attention, provides a light of sufficient intensity for convenient use with an Abbe-type refractometer, requires n relatively low current source, and is easily constructed. I t has been used successfully for several years as fhe source of illumination viith Abbe-type refractometers for making refractive index and dispersion measurements involving the C and F lines of the hydrogen spectra.
:
- E
Figure l.
Hydrogen Discharge Tube
S E P T E M B E R 1947
667
A hydrogen discharge tube of Pyrex is described. It is easily constructed in the laboratory, u s e s a relatively low current source, and m a y be operated for several hours continuously with little attention. The C and F lines of the hydrogen spectra emitted are of s u 5 c i e n t intensity for refractometric or dispersion measurements with an Abbe type of refractometer without special handling. CONSTRUCTION O F TUBE
A scnlc drawing of the tube (8) is shonn in Figure 1. It is constructed of Pyrex which absorbs the ultraviolet portion of the light and permits the tube tohe used without protective goggles. The inner assembly oonsists essentially of t n 6 electrodes and a capillary mounted coaxially within bhe glass ease. A small but very intense lirht is Droduced at the end of the c a d l a r v when the tub; is viewed-doni the axis of the cauillarv.
pumped down t o about 3 mm. of hydrogcn prcssure and the e l m trodes are energized by c o n n e c h g across the secondary of a 5000-v&, 30-milliamperc transformer (similar to those used on luminous signs). A hrightlsvender light is produced. It was found t h a t the color was sensitive t o pressure and after a little experience the color of the light rather than a uressure gage was
.
"
~~
~
-
Only i v e r y s m a l Row of hydrigdn is Lequired ( a bubble every 5 to 10 seconds &smeasured by G). Although this may sound diffiperpendicular t o t h e ;xis of the capillary. The end of the tube at B is flat and about 0.5 em. from the end of the capillary. The electrodcs. C and D are of mire aliiminiim wire and mire slum-
as wcll as tho contacts b e h e n the tunmton leads and the flexibk
Duh& the construction of the tube great care was exercised to
The dcei.rodes were washed v i t h ethyl aliohol and dried. The parts were then carefully assembled to eliminrtte impurities whicli would affect the quality of the light obtained from the finishcd tube. Figure 3.
USE O F T U B E
Early models included sealed tubes containing hydrogen at proper pressure and tubes that were fitted with a single stopcock which permitted periodic refilling with hydrogen. Neither type WBS entirely satisfactory.
TO HYDROGEN CYLINDER
M
Figure 2.
IIydrogen Discharge T u b e Spectra
The tube described has been in use for several years of intermittent operation without deterioration of the quality or intensity of the light. A photograph of the spectra is shown in Figure 3. The top line represents the complete spectra. The second line represents the spectra through n red filter (Wratten KO. 29) and the third line through B blue filter (Wratten No. 75). Although it is poasible t o obtain refractive indices with an Abbe-type refractometer involving the C and F lines of the spectra without filters, in routine operations the use of filters is preferred. The use of the hydrogen discharge tube described in this paper with an Abbe refractometer requires very little aligning except to place the'tube in such il position that the end of the capillary at B is perpendicular t o the face of the prism or t o the sris'of the mirror used on the refractometer.
Hydrogen System ACKNOWLEDGMENT
The design finally adopted was that shown in Figure 1, in which hydrogrn was passcd slon.ly through the discharge tube from E t o F whilc the tubc was omratinn. The arraneement of thc accessories for operating this &he is &own in Figure 2. The cylindcr of electr: lytic or maist hvdroeen is attached to the nerdlo D~
~~~
~
The authors wish to acknowledge the valuable advice and assistance of C. Lewis, glass blower, who constructed many experinental models in the development of this hydrogen discharge tube. LITERATURE CITED
.,
(1) Allen. A. J.. and Franklin. R.
hrokin w i h o u t dffecting ihnt in the tube. The m&omcter. L. measures the hydrogen Gessure in the tube. To operate the tube, the system is evacuated by means of the vacuum D U ~ Dand flushed with eleetrolvtic hvdroeen several times. Prol
