In several papers of this series1 we ha\Te been able to sho\v that tile data obtained in paper chromatogral~hy, apart from their analytical \falue, may be usecl to esplain the complex chemistry of the elements chromatograpl~ecl in the same manner as solvent estraction or ion eschangc equilibrium results.
The paper chromatography of Pa has so .far been mentioned in only two problems, the separation of UX, and UZz, and the separation of as31?a from Nb". In both separations solvents containing HF were employed. In this paper we shall discuss the behaviour of Pa in mistures of acetone-HCl-water.
This stuay was commenced with the aim of increasing the amount of clata on the paper chromatography of tetravalent cations. As only very few solvents had been studied for tetravalent U and no separation noted. between U(IV) and Th(IV), we first loolcecl for a solvent that gave a good RI." difference for the misture U(IV)-Th(IV). Acetone containing 5 "/0 water and 5% cont. HCl gave a good separation in these preliminary tests, while other solvents such as acetone-H&30,, butanol-HCl, butanol-HRr (for the last two seel), did not yielcl notable Zi~_clifferences. The solutions of U(IV) in this work were prepared by shaking a solution of uranyl chloride in the required concentration of HCl with a few ml of zinc amalgam in a micro separation funnel and pipetting off an aliquot just before placing it on the, paper, Since Pa lies between U ancl Th in the periodic table, we thought that it might be possible to obtain a. reduction (at least partially) of the Pa(V) if it were added to the zinc amalgam redlzction with the uranyl chloride; the reduced U(IV) might esert a protective influence on the Pa(IV) during manipulation, Later esperiments proved that this was not the case; however, the first chromatograms showed that there was a distinct difference between the movement of 23"Pa tracer shaken with U and zinc amalgam ancl the pure ?""Pa tracer.
Osiclation of the U(W) with dichromate, ferric chloride, and other oxidants, had a profound influence on the movemenl: of the Pa in these solutions, and since P:\PER CHROMA'l'OC~RXl?HY 01: