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1. The velocity constant for the diacetone alcohol decomposition in the presence of dilute sodium hydroxide has been measured at 5°intervals from 0 to 50°.2. The constancy of ratio of velocity constant to sodium hydroxide concentration has been confirmed over a limited concentration range at 25°.3. The energy of activation, calculated from the Arrhenius equation for a series of temperature intervals, has been shown to be a function of temperature well outside the limits of error. Eact increases consistently from a value of 15,850 cal. at 5°to 17,250 at 32.5 and then decreases by about 400 cal. at 45°. 4. On the addition of 18.5% of methyl alcohol Eact increases by over 1700 cal. but the general character of the Eact-r curve remains little changed to 30°.5. The corresponding B values from the integrated Arrhenius equation, In k = 2.3 B -(£act/ RT), both in water and the methyl alcohol solution parallel these Eact values and furnish experimental evidence for abandoning the unfortunate term "temperature independent constant" for this quantity.6. The data show that the collision theory is inadequate and that the entropy of activation is an important quantity in considering solution reactions.

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The calculated heats of ionization, which are in calories per mole, refer, of course, to the ionization at infinite dilution.The values of pKs calculated are insufficiently accurate for the heat effect of the third ionization step to be calculated. Heat, however, is evolved in this ionization. SummaryWith the quinhydrone electrode measurements of the Ph values of phosphate mixtures have been made which lead to the following values for the ionization constants of phosphoric acid pK, (25°) = 2.10, pKi (37.5°) = 2.16 pKi (25°) = 7.13, pKi (37.5°) = 7.06These figures are compared with those derived from other data. From the data of Britton pK3 at 20°is calculated to be about 12.1.