ANALYTICAL CHEMISTRY
246 in Table I exerted any noticeable influence upon the characteristics of the precipitate of nickel dimethylglyoxime.
addition agents tested exerts any influence upon the characterie tics of the precipitated crystals.
SUMMARY
LITERATURE CITED
I n the precipitation of barium sulfate, several addition agents were found to influence the crystal morphology, especially its size, and none was found to influence the extent of coprecipitation, either beneficially or adversely. I n the precipitation of silver chloride, several addition agents influence the flocculation rate, none influences the individual particle size, and one (naphthol yellow) provides protection from photolytic decomposition. I n the precipitation of nickel dimethylglyoxime, none of the
(1) Bogan, E. J., Ph.D. thesis, Ohio State University, 1949. (2) Bogan, E.J., and Noyer, H. V.,ISD. ENG.CHEM., ANAL.ED.,14, 849 (1942). (3) Buckley, H. E., “Crystal Growth,” S e w York, John Wiles “r Sons, 1951. (4) Lindsly, C. H., IND. ENG.CHEM., A s . 4 ~ ED., . 8,176 (1936). ( 5 ) Orlow, I. E., 2.anal. Chum., 98, 320 (1934). RECEIVED for review March 27, 1953. Accepted September 28, 1953. P i i h lirntion 601 from the Chemistry Departinent of Indiana University.
Determination of Sodium Monoxide in Sodium An Addendum LEONARD P. PEPKOWITZ, WILLIAM C. JUDD,
and
RAYMOND J. DOWNER. N. Y.
Knolls Atomic Power Laboratory, General Electric Co., Schenectady,
T
HE interest in liquid metal coolants and in other applications of the mercury extraction method as in the determination of oxygen in zinc ( 2 ) and in tin ( 5 ) has increased rapidly. I n the paper by Pepkowitz and Judd on the determination of sodium monoxide in sodium (S), the data given indicate a precision within j=0.0050/, on replicates from a given sample. However, the over-all precision on a series of samples was within 0.01%. During the 3 years since the publication of the original paper, minor modifications in the procedure have resulted in a significant increase in the precision obtained by the mercury extractiori method (4).
Tahle I. Precision Data for Determination of Oxygen in Sodium Sample No. Distilled sodiuni Heat exchanger 6-82 6-87 P-22 BDE-5 A-24 6-89 BDE-6 6-90 6-91 6PH-1 6-26 6-95
BCT-1 6-98
Sample A
Oxygen, % Sample B
Difference
0.0
0.007 0.013 0.007 0.005 0.011 0.005
0,002 0,001 0.002 0.007 0.003 0.001 0.001 0.001 0.001
0.005 0.003 0.007 0,009 0,005
0
0 0.001 0.003 0,001 0.008
0.012 0.009
0.005 0.011 0.031 Mean Standard deviation
0.0017
fO. 0017
ferences between duplicate pairs is 10,0017,which is a significant increase in precision over the data originally reported. Two modifications in the method were made which allow for this increase in precision. The first is an increase in the purity of the blanket gas with respect to oxygen. This was accompliPhed by passing the gas through NaK bubblers ( 1 ) to remove the oxygen instead of over hot copper. The S a K bubbler is much more convenient as well as effective and the present system has been in continuous use for -2.5 years without any maintenance. The second modification is to heat the extractor by brushing with a gas flame during the amalgamation step. I n the original procedure the extractor was cooled with an air blast in order to prevent undue strains on the glass reactor. However, experience has shown that no adverse effects are caused by the elevated temperature but rather the amalgamation is more complete a t the elevated temperature. The technique has been applied to sodium-potassium alloy (KaK) and to lithium. The NaK sample is easily handled by freezing the NaK contained in the glass sampling tube on dry ice. I t will remain frozen during the initial steps of the procedure, so that i t can be handled in the same manner as a solid sodium sample. The apparatus is modified slightly in that the end of the rubber sleeve which holds sample A in Figure 1 of the original paper (3)is closed with a length of glass tubing sealed a t the end. This is immersed in :t dry ice slurry during the remainder of the analysis to keep the r e sidual NaK sample frozen, By this simple means the original procedure can be adhered to, even though NaK is liquid at room temperature and much more reactive than sodium metal. Somewhat more elaborate precautions are required for lithium, and the description of this apparatus will be the subject of :I forthcoming communication. LITERATURE CITED
The inherent precision was also demonstrated by the adaptation to a remotely operated sampling and analytical system(f ) in which a precision within 0.001% was reported. I n the course of the routine application of the method over the past feF years, a number of different analysts have used the method with a somen h a t uniform precision as shown in Table I. These data are given in pairs. Each pair is the single value obtained on duplicate sodium samples and not on portions of the same sample. The standard deviation for precision of the difI
Present address, 315 Winnacunnorett Road, Hampton, N. H.
(1) Bruggeman, W. H.,and Billuris, G., I d . Labs., 4, 94 (1953). Abstract. (2) Pepkowitz, L. P . , unpublished data. (3) Pepkowitz, I,. P . , and Judd, 1%‘. C., ANAL. CHEM.,22, l2iii: (1950). (4) Pepkowitz, L. P . , Judd, W. C . , and Downer, R. J., Knolls Atomic Power Laboratory, KAPL-972 (1953). ( 5 ) Silverman, L., and Gossen, IT.,Anal. Chim.Acta, 8,436 (1953). RECEIVEDAugust 10, 1953. Accepted October 20, 1953. THE Knoll= Atomic Power Laboratory is operated by the General Electric Co. for thr, Atomic Energy Commission, The work prepared here was carried o‘it under contract No. W-31-109 Eng-52.
