In most of the examples of Table I the chemicals used for conversion of the resin and as reagents for the resin reactions were ionic as is usual in ion exchange technology. But ionic species are not requisite in this technique. The reagent may be molecular as in the simple case of chlorine (chlorine water), which displaced iodide ion from an SAR resin in the iodide form with the resultant production of free brown iodine. I n the nickel-dimethylglyoxime resin reaction, a dimethylglyoxime form of the anionic IRA-400 resin was made by shaking the resin with an ethyl alcohol solution of dimethylglyoxime. Some of the colorimetric products mere desorbed from the resin. The ferric thiocyanate, in IRC-50, was leached from the aqueous solution above. The desorption process, however, is slow and does not affect the immediate production of the colorimetric reaction within the resin. Inasmuch as desorption did not occur with anionic resins this might indicate that the ferric thiocyanate exists as a negative complexe.g., Fe(Ch’S)6---, (S)-which would not be bound by a cationic resin. Thus whether desorption occurs from a cationic or anionic ion exchange resin might be a clue to the charge of an unknown ion. The resins can be prepared in a specific form and stored under water for future use. In some cases it has been possible to air-dry the resin beads. They will still exhibit a t some future date their characteristic chemical properties when moistened or treated with an aqueous solution of a reagent. The permanganate form of SAR, dried and stored for 2 weeks, still exhibited its characteristic reaction with hydrogen peroxide. The sulfide forms of both SAR and IRA-400, however, no longer exhibited the characteristic sulfide reactions after the resins were dried. Though heretofore only colorimetric reactions have been considered it is manifestly possible to carry out chemical reactions by this technique, whether or not color is involved. Thus the cyanide form of SAR adsorbed ferric ions to the limit of its capacity in the formation of a ferricyanide complex which remained adsorbed to the resin.
change Resins,” Wiley, New Yor k
to utilize the characteristic reactions of ionic and molecular species distributed throughout a solid matrix in the form of an ion exchange resin.
1950.
Nachod, F. C., Schubert, J., “Ion Exchange Technology,” Academic Press, New York, 1956. Thorne, P. C. L., Roberts, E. R., “Inorganic Chemistry,” Interscience, New York, 1954. WALTER E. MILLER
ACKNOWLEDGMENT
This work was done under contract with Refining Unincorporated, New York, N. Y. The author wishes to express his appreciation for permission t o publish this article.
Department of Chemistry The City College New York, N. Y.
LITERATURE CITED
RECEIVED for review March 16, 1957. Accepted September 6, 1957.
(1) Kunin, R., Myers, R. J., “Ion Ex-
Corrections Significance of pH in Determination of Vanillin by Ultraviolet Absorption In a recent paper [AXAL.CHEW 29, 1151 (1957)] the authors cited a value of 7.496 for the pK value of vanillin as one obtained by Robinson and Kiang [Trans. Faraday SOC.51, 1398 (1955)l. This value should have been 7.396. Furthermore, activity coefficient considerations were not employed in the calculation of reported pK values. When this refinement, employed in Robinson and Kiang’s calculations, is included the ten measurements made by
us give pK values of 7.38, 7.22, 7.42, 7.43, 7.43, 7.43, 7.42, 7.39, 7.39, and 7.52 with an average of 7.40. This average is in excellent agreement with their value. The authors wish to thank Robinson for bringing the facts to their attention. DUANET . EKGLIS LOUIS A. WOLLERMANN
Characteristics of the BoronBenzoin Complex In the article on “Characteristics of the Boron-Benzoin Complex” [White, C. E., Hoffman, D. E., ANAL. CHEM. 29, 1105 (1957)] the tenth line of the first column on page 1108 should read: mp with a maximum a t 480 mp.
+
A = 10-2 sq.cm. (Ox) (Red) = lo-‘ mole per cc. Kh for Equation 2 = cm. sec.-I Kh for Equation 3 = lo-‘ cm. set. -1 Nernst diffusion layer thlcknese 10-3 cm. Caption for Figure 2, p. 1391: A, “rapid stirring” for “no stirring.” Caption for Figure 8, p. 1395: omit numeral 8 before ferrocyanide. Table 117, footnote a, R1 for Ra. Cantion for Figure 9, p. 1396: Curve A i R1 for R2* H. A. LAITINEN
Square W a v e Titrimetry
In the paper on “Square JTave Titrimetry” [ANAL.CHEM. 29, 1390 (1957)], one major error and several minor ones crept in. Figure 1, page 1390, should have been replaced by the enclosed figure, t o which the discussion a t the bottom of page 1391 and the top of page 1392 refers.
I
Assumed for Equations 1, 2, and 3: n = 1, = 0.5, D = 10-6 sq. cm. sec.-l (I
-”24001
+
Nalcite SAR (CN). F e + + +-+ Nalcite SAR [Fe(CN)e---]
No trace of ferric ion was found in the supernatant liquid above the ferricyanide form of the resin. The colorimetric reactions described have been carried out with as little as one bead of resin. For purely physical reasons, ion exchange resin beads of larger size than those now commercially available would be desirable. Using single beads a spot test technique could be developed. The essential element of the process is that it enables one
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Theoretical responses for reversible case See Equation 1 VOL 29 NO. 12 DECEMBER 1957
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