Abstract. The precipitation of Pa233 with MnO2 from a solution of thorium nitrate has been studied in some detail and seems quite satisfactory up to 36 gm Th(HO3)4 4H2O per 100 cc solution. The concentration of Pa233 with respect to the manganese dioxide carrier and the thorium precipitated with the carrier appears to be accomplished quite well by either a series of MnO2 cycles or thorium iodate cycles. Volatility methods for both the separation of Pa233 from the original thorium and for its separation from MnO2 are now under investigation. It has been decided that thorium carbonate will the the thorium compound used in the pile at Site X.

Technical report abstract: Since UNH is a highly dissociated compound which ionizes to NO3 and (UO2), the latter ion being very weakly basic, a solution of pure UNH is quite acid (pH about 3). It is possible to titrate to a phenolphthalein and point with standard caustic solution and obtain a figure which represents the free acid plus the NO3 from the the UNH. However, titration of the free nitric acid alone in such a solution presents quite a problem. By precipitating and removing uranium from solution by means of potassium ferrocyanide, the residual free acid may be titrated directly by means of standard caustic using either methyl red or phenolphthalein indicators, with an error of less than 4%. A method is given to determine formic acid, should that acid be present in the mixture.