The mutual solubility of TBP and water has been measured in the presence of nitric acid and of various inert diluents for the TBP. Nitric acid partitions have also been studied. It is concluded that the most important compound formed is HNo3.TBP, and that this m a y be partly hydrated. Several new effects occur above ca. 7 M aqueous acidity. Ideal thermodynamic behaviour is observed only at rather low TBP concentrations ; at high TBP concentrations the deviations from ideality are considerable.

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Evidence is presented pointing to the conclusion that nitrates are extracted by TBP in the neutral, unionized form, always solvated by a definite number of TBP molecules, e.g. Ce(N03)3 .3TBP, UO2(NO3)2 .2TBP ; the compounds formed are sometimes hydrated, sometimes almost unhydrated. The evidence is much fuller for uranyl than for any other nitrate, but all the data support this general conclusion.The nature of the species present in the TBP phase must be investigated before the distribution data for water + TBP systems can be properly understood, The present paper is concerned with experiments bearing on this question.

Efficient methods are given for decreasing or eliminating the nitric acid content of solutions of inorganic nitrates with recovery of oxides of nitrogen and leaving behind no added reagent.The reaction of both formaldehyde and formic acid with nitric acid (2-20N) has been studied at looo. A t constant concentrations of formaldehyde and formic acid the reactions are of apparent third-order over the nitric acid range 2 -1 5~ (rate constants given).Further reaction of formaldehyde or formic acid with nitrate solutions causes precipitation of metal hydroxides as the p H of the solution rises; this may be used as a basis of separation of metals from solution. Nitrates can be converted to other salts such as chloride or sulphate by reaction with formaldehyde after addition of the appropriate acid.Nitrites do not react with formaldehyde in neutral solution, but nitrous acid. liberated by hot acid, decomposes partially into nitric acid which then reacts with formaldehyde as above.