from eq. 2 using k and estimates of Bo.6) To separate the dipole moment, pO2, from Aa, the change with wave length of A a was estimated from the curves of Figure 1 and divided into the corresponding change in AapOz2 to obtain estimates of 120 and 70 D. ( f 2 0 % ) for the permanent moments of met-and oxyhemoglobin, respectively. The shape effect contribution was then estimated as about -40 X ml. for both molecules. It is unlikely that an intrinsic anisotropy of static polarizability could lead to an orientation parallel to the short axis of the magnitude observed. If there is a mechanism favoring orientation parallel to the long axis of the molecule, such as anisotropy in a fluctuation dipole or in an ion-atmosphere polarization, the above analysis would then yield only a lower limit to the permanent dipole along the twofold axis. From this possibility it can be seen that if the data had suggested case a, no inference about the existence of a permanent dipole could have been made. Calculations of the electric dichroism suggest that no signal should have been observed for case b and the amount of orientation predicted by the Kerr effect, so that this experiment was consistent with the interpretation of the Kerr effect measurements.It is therefore reasonable to conclude that the above experiments and analysis are evidence for a permanent dipole along the twofold axis in hemoglobin at neutral pH. The suggestion of a greater dipole moment for methemoglobin relative to oxyhemoglobin is consistent with the dielectric increment data,* although dipole moments estimated from dielectric increments (400-500 D.) apparently include contributions that are not effective in orientation, such as a randomly oriented fluctuation dipole or an ion-atmosphere polarization about an almost spherical molecule.

The kinetics of the iron(II)-catalyzed dissociation of FeCl24 have been studied by the use of a flow technique. The rate constant for the dissociation is given by £

The rates.of the reactions Co3+ + Cl-;=iCoCl2 + have been studied-in the concentration ranges [Co(III)] = 3.0 to 5.0 X 10-4 M, [Co(II)] = 5.0 to 33.0 X 10-2 M, (Cl-) = 4.8 to 105 X 10~3 , (H+) = 0.4 to 3.0 M,ionic strength = 3.0 M. The approach to equilibrium is given by ¿obsd = ¿'(Cl-) + k" where ¿' = [¿n(H+) + ¿2fAih + ¿3f7C4(Co2+)(H+)]/[(H+) + iGh] and k" = [¿id(H+) + ¿2dA2h + ¿8d(Co2+)(H+)]/(H+). The values of the constants are ku < 2 AT-1 sec.

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