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Preliminary Investigations on the application of a divinylbenzene (DVB), cross-linked poly( acrylamidoxime) resin for the concentration of trace metals from aqueous solutions is reported. The pH dependence of metal-resin chelation has been determined for Na, Mg, K, Ca, Ti(IV), V(V), Cr(III), Cr(VI), Mn(II), Fe( 11), Fe(III), Co(II), Ni( II), Cu(II), Zn(II), Ag( I ) ,Cd(II), Hg(II), and Pb(I1). The resin exhibits no affinity for the alkali or alkaline earth metals tested over the pH range 2-8, and the resin selectivity has been determined at pH 5 for several of the metals. The order of decreasing Selectivity Is Cu(II), Ni(II), Co(II), Zn(II), Mn(I1).

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4pparently compounds that react readily with hydrogen chloride prevent the normal color reaction.-4bsorption spectra of the reactions of activated GDH with vitamin A when solvent to reagent ratios of 1:0, 1:5, l : , l , 5:1, and 9 : 1 were employed are presented. The extinction coefficients a t 555 mp were essentially the same in the cases of the 1 : 3, 1 : 7, 1 : 5, and 1 : 3 ratios. As the ratios were increased above 1 : 3, the absorption a t 555 mp decreased while the absorption at 337, 353, 372,395, and 422 mp increased and reached maximum values when a 9 : 1 ratio was used. These maxima in and near the ultraviolet resemble to some extent the type absorption spectrum of anhvdro vitamin .4.

When propylene oxide is polymerized or when it is added onto an alcohol or phenol, the terminal hydroxyl groups can be of primary or secondary types, depending on how the epoxide ring opens. The nature of the terminal hydroxyl group becomes important if the polyglycol ether is reacted further, as in the case of polyurethane foams. The primary hydroxyl group reacts much more rapidly with isocyanates than the secondary hydroxyl group, and hence the performance of the polyglycol varies with the ratio of primary to secondary hydroxyl group content. An analytical method has been developed to differentiate the primary from the secondary hydroxyl groups on polypropylene glycol, and a study was made of the variation in the ratios of the two hydroxyl types versus molecular weight of the polyglycol and versus other chemical treatments to which the polyglycol was exposed.

from 20 to 40 ml. The average deviation from the theoretical weight was 0.1% for precipitates that were washed with hydrochloric acid solution.The factor 2.890 converts weight of thallous sulfate to tetraphenylarsonium chlorothallate. The weight of thallous perrhenate is converted to the equimolecular mixture of tetraphenylarsonium perrhenate and tetraphenylarsonium chlorothallate by the factor 2.998. Thallium was not separated from rhenium but was simultaneously precipitated with tetraphenylarsonium chloride. SUMMARYThallium may be quantitatively determined by precipitation from hydrochloric acid solutions containing the element in the trivalent state. The oxidation of the thallous ion may be accomplished with hydrogen peroxide or any other effective oxidizing agent which introduces no interfering substance. The precipitating reagent is a water solution of tetraphenylarsonium chloride. The amount of excess of this reagent is not critical. The precipitate obtained should be washed with hydrochloric acid solution to prevent hydrolysis, and dried in an oven at 110°C. LITERATURE CITED(1) Chrétien and Longi, Bull. soc. chim., 11, 241 (1944).(2) Feigl, "Qualitative Analysis by Spot Tests," 2nd ed., p. 93, New

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