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These results may be best summarized by a consideration of the behavior of Expt. 5 . In this experiment a capillary of 5 . 3 3~ radius was exposed to a toluene solution whose vapor pressure was lowered to 0.082 mm. by the addition of a solute. It was found that liquid toluene condensed in this capillary, which would indicate that the vapor pressure of the toluene in the capillary was less than (21.60 -0.082). The classical theory of capillarity, however, teIls us that the vapor pressure lowering of toluene a t 20" in a tube of this radius should be only 0.009 mm. of mercury. It is therefore obvious that either our experimental work is in error or the classical theory as applied to vapor pressure in capillaries is not correct.We believe the latter to be true and are convinced that this work has been done with sufficient care to warrant such a conclusion. At this point it may be well to add that such a view does not necessarily conflict with the thermodynamic treatment of this question. Thermodynamically the problem is simply the action of a negative pressure upon the vapor pressure of a liquid. This question is rigorously handled by the well-known relationship of Gibbs. What we have shown here is that the negative pressure in the case of small capillaries may be greater than has been assumed to be the case.We have shown that zirconium sulfate can be used to detect potassium and that the test can be applied in the presence of sodium.* Ammonium ions must be eliminated prior to testing for potassium with other reagents such as sodium cobaltic nitrite, chloroplatinic acid or perchloric acid. The sensitivity of zirconium sulfate for potassium in the presence of ammonium ions was therefore investigated.The results indicated that zirconium sulfate solution will detect 0.48 mg. of potassium in 2 cc. of reaction mixture in the presence of large amounts of ammonium sulfate. This was practically the same sensitiveness of this reagent for potassium in the absence of ammonium as in the previous work.In memory of Ira Remsen. Reed and Withrow, THIS JOURNAL, 50, 1515 (1928)

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ZIRCONIUM.IV 13114. Six per cent, potassium iodide must be employed when sodium thiosulfate solutions are standardized with potassium permanganate. Standing is not necessary. The acid concentration may be 0.1 M sulfuric.