The results of a study of the nature of concentrated potassium zincate solutions in alkali are reported. Data from several independent but complementary techniques are mutually consistent and show that electrolytically produced solutions of high concentration are relatively complex, the complexity depending upon the age. It is concluded that initially quasi-colloidal particles, based on Zn(OH), and molecules of solvation, are present. The particles of colloidal character are electroinactive and undergo a first order decay to yield a solution containing the species [Zn(OH)2-2H20], [Zn(OH)3.H20]-and [Zn(OH)4]2-, the actual constitution depending on the concentration.It is shown that previous spectral assignments are erroneous, reported bands at 283 and 310 Acnr' arising from the KOH solution itself. The new data show thc non-colloidal zinc species to be tetrahedral, and not planar or octahedral.It was found that the u1 band (Raman) of Zn(0M);-occurred at 471.2 & 0.9 Acm-' (previocsly accepted value -484 Acm-I).The 430Acm-' value for u3 was confirmed but the expected, weak v2 and v4 bands were not detectable due to the high background and overlapping KOH solution bands.

The protonation of some nitroaniline indicators has been studied in aqueous sulphuric acid over the temperature range 15-55".The log / values of these indicators decrease with increasing temperature and the pKBH+ values vary linearly with temperature. These log / and pK, , + values have also been used to calculate the Hammett acidity function (H,) of the acid media over the temperature range 15-55". MANYweak organic bases are protonated only in concentrated acid solutions to give their conjugate acids. The measurement of the acidity of such solutions poses a difficult problem which Hammett attempted to overcome by introducing the H , acidity function concept, whereby the acidity of a solution is determined relative to standard basic indicators. For the correct formulation of the H , scale, as expressed by equation (l), the conditions that must be met by the indicators are (i) that the pK values of the indicators are accurately established, and (ii) that the indicators are valid H , indicators such that the activity coefficient ratio of the free base to the protonated base for the compounds B and C are equal. The relationship between p K o ~+ and pKBH+ (which throughout the rest of this paper is written simply as pK) as expressed in equation (2) can

Vibrational Frequencies of Sulfur Dioxide Determination and application Quite apart from their own considerable From the well-known relationship of thermodynamics, Cv = dE/dT, and eqn. (5) we have Volume 47, Number 5,

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