solid into the more thermally unstable liquid can be predicted from the constant heating rate DSC thermogram where a melting endotherm appears just prior to the initial decomposition. This effect was observed with the present system. This observation, along with the demonstration that decomposition near the melting point obeys the simple autocatalytic scheme proposed, lends credence to the melting theory. It also, however, becomes obvious that as the decomposition occurs at temperatures substantially below the melting point, effects other than chemical or melting begin to play substantial roles in determining the reaction mechanism. The nature and extent of these effects on the cupferron tosylate system are currently being studied. In this regard, a Hammett pa analysis (12) of the kinetics revealed that there is no systematic substitutent effect on the decomposition behavior within the series. Another approach taken indicates when that the substrates are imbedded in potassium bromide matrix and decomposed in the sample beam of an infrared spectrophotometer the sigmoid shaped curve is distorted. Additional work is being done to delineate the cause of this distortion. The results will be reported in the future. Activation Energies. The activation energies Gbtained from the rate data were compared with activation energies -
(12) L. P. Hammett, “Physical Organic Chemistry,” McGrawHill Book Company, Inc., New York, 1940, p 184.
obtained by the method of Rogers and Morris (5). There is no correlation between the respective sets of values. However, there is a striking correlation between the energies determined from constant heating and those determined from the point of maximum reaction during isothermal heating. (The maximum reaction values obtained from the isothermal thermograms correspond to the inflection points of the decomposition histories.) The similarity of values as determined from both methods indicates that analysis of the maximum deflection distance and of the constant heating curve is a measure of maximum decomposition reaction for an autocatalytic reaction. However, these values for activation energy cannot be related back to the proposed reaction mechanism. Therefore, the authors feel that these values are of utility only for comparative studies and have little utility when dealing with kinetically defined activation energies.
ACKNOWLEDGMENT The authors thank Travis E. Stevens of the Rohm & Haas Company, Huntsville, Ala., for samples of the cupferron tosylates.
RECEIVED for review May 29, 1969. Accepted November 21, 1969. A portion of this work was presented at the 158th National Meeting, American Chemical Society, New York, September 1969.
Corrections Activation Analysis for Molybdenum in Samples Containing Large Amounts of Tungsten In this article by Barbara A. Thompson and Philip D. LaFleur [ANAL.CHEM.,41, 1888 (lS69)], the following errors in Table I should be corrected. The last item in column 2 should be 23.96 i:0,23b. Also in Table I items three, four, and five in column 3 should be 0.996’ 23.90 f 0.06‘ 23.75 i0.15‘
Activity Measurements in Concentrated Sodium Chloride-Potassium Chloride Electrolytes Using Cation-Sensitive Glass Electrodes In this article by Rima Huston and James N. Butler [ANAL. y 1 2 and 7 2 1 are mean activity coefficients of NaCl and KCI. Equation J should read:
CHEM., 41, 1695-8 (196911, note that
Equation 3 should read:
256
Theory of Curved Molar Ratio Plots and a New Linear Plotting Method In this article by Kozo Momoki et al. [ANAL.CHEM.,41, 1286 (1969)], there are several errors that should be corrected as follows: ColPage umn 1288 1288 1288 1288 1290 1293 1293 1294 1298
Line
For
changing-ligand concentration 2 5 Beers’ law 2 8 [MrnZnIi 2 22 If the 1 7 seep 1 28“ C’L Equation 27 (Cc)mx = SL . CL TablePV and P Results (title) 2 9 compleses 2
4
Read changing ligandconcentration Beer’s law [*WrnLnlt In the steep C,’ (Cc)m,x
= SL ’ CL’
and Results complexes
1298 Equation 28
” Also in Figures 7, 8, 12, 14, 15, and 16, experimentally weighed conc&tration of ligand used should-be read as there printed or drawn. CL‘ instead of
ANALYTICAL CHEMISTRY, VOL. 42, NO. 2, FEBRUARY 1970
