Phase diagrams and light-scattering measurements of a homologous series of dimethylalkylphosphine oxides are used to determine the micellar molecular weights and their relation to consolute phase boundaries in these systems. The temperature dependence of micellar molecular weights is discussed with regard to both light-scattering and solution theory, and it is concluded that, in systems which show consolute boundaries, the lightscattering behavior can be qualitatively explained on the basis of existing theory without invoking any large temperature or concentration dependence of micellar molecular weight. The observed light-scattering behavior can easily be accounted for by the nonideality of a micellar solution and the temperature dependence of micellar-water interactions. Lightscattering measurements at the critical concentration for phase separat,ion of the dimethyldodecylphosphine oxide-water system have also been made and show that, critical opalescence is observed in this system. These results are discussed in the light of existing theoretical treatments of this phenomenon, and the experimental results are shown to agree qualitatively with the theory.

Intrinsic viscosities, sedimentation coefficients, and diffusion constants have been used to determine the size, shape, and hydration of nonionic (dimethyldodecylamine oxide) and anionic (sodium dodecyl sulfate) surfactant micelles. From these data it is concluded that the micelles are small, spherical, and highly hydrated (contain -40'% water by volume) in dilute solution. A model for the micelle is postulated and shown to be in agreement with the experimental data.Few measurements have been made of the hydrodynamic properties of micelles where the results have been used to deduce size, shape, or hydration. Kushner, et uL11-3 measured viscosity as a function of concentration for a number of detergents but concluded that hydration of the micelle was an important factor only for a commercial nonyl phenol-ethylene oxide condensate which gave a high intrinsic viscosity. Tyuzgo4 used diffusion coefficients and Stokes' law to calculate hydration for several salts of fatty acids. Other workers5 also used diffusion coefficients to calculate hydration of a series of methoxy polyoxyethylene decanoates and dodecanoates assuming the particles were spherical. Vetter6 used several pieces of hydrodynamic data to deduce that micelles of Aerosol MA contained water, while Hakala7 ignored hydration to conclude from hydrodynamic data that micelles of sodium dodecyl sulfate were ellipsoidal. On the other hand, Stigter, Mysels, and Williams* compared diffusion data with light scattering molecular weights to conclude that sodium dodecyl sulfate micelles were hydrated if a spherical shape vias assumed.I n order to clarify some of these apparently conflicting results, a numbel of hydrodynamic measurements were made on micellar solutions of very pure nonionic and ionic surfactants and the size, shape, and hydration of the micelles were determined from these data. ExperimentalViscosity. The viscosities of the solutions were measured at 30.00 f 0.02" using an Ostwald-Fenske viscometer with a flow time for water of about 220 sec.Flow times were measured to 0.01 sec. with a stop watch. The average deviation for five to seven measurements of a single solution did not exceed =t0.07 sec. The viscometer was calibrated with distilled water and 10% glycerine and the usual equation, = Apt + Bp/t, was used to calculate the viscometer constants. The absolute viscosity and density of water at 30" were taken to be 0.007976 poiseg and 0.99568 g./ml.,Io respectively. The viscosity and density of the glycerine solution were taken to be 0.01024 poise and 1.01927 g./ml., respective1y.l' The surface tension correction, arising from the difference in shape of the nieniscus in the upper and lower bulbs of the viscometer, mas ignored. This is possible because the quantity of interest is the viscosity of the solution relative to the viscosity at the critical micelle concentration, and the surface tension of these solutions was constant above the

Two compounds, previously isolated from a toxic feed fat and capable of producing hydropericardium in chicks, were further characterized. Mass and other spectral data indicate that they are isomers with the molecular formula C14H,,Cls. A procedure was developed for reductive dehalogenation of l -mg. quantities of chlorinated hydrocarbons, with the resulting saturated hydrocarbons being identified by gas chromatography. Application of this procedure to the toxic compounds produced from each of them a mixture of isomeric perhydrophenanthrenes. This result provides strong evidence that the toxic compounds are hexachlorohexahydrophenanthrenes.URING the fall of 1957, the poultry

Downloaded 26 Sep 2012 to 136.159.235.223. Redistribution subject to AIP license or copyright; see http://jcp.aip.org/about/rights_and_permissions ION-MOLECULE REACTIONS OF METItANE 1931 methane. The reactions C2H2++CH.-+C2Ha++CHa (0.47) (24) -+CaHa++H2+H (0.03) (25) -+C a H4++H2 (0.09) (26) -+C a H 5 ++H·, (0.41) (27) C2Ha++CH.-+CaH5++H2 (0.77) (28) -+CaHs++H·, (0.23)were observed with percentages of the reaction paths as noted in parentheses. These percentages were the same for C2H2+ from ethylene or acetylene and for C2Ha+ from ethylene or ethane. We further agree with the findings of Munson and Field l5 that there is a large difference in the reaction rates for C2Ha+ and C2H2+' They find that the C 2 H 2 + species reacts about five times faster than C2Ha+, and we observe an approximately 30-fold difference in reactivity. We attempted to follow the ionic polymerization chain one step further by impacting C 3 ions on methane. For C3H5+ from propylene and cyclopropane and C3H4+ and CaHa+ from propylene we did not observe any reaction products, from which we conclude that chain-lengthening ion-molecule reactions of these ions with methane have cross sections at least two orders of magnitude smaller than those of the methane primary ions.An energy-distribution difference method for determining ionization potentials and for detecting fine structure, i.e., breaks, in ionization-efficiency curves is described which eliminates the difficulties arising from the thermal-energy spread of the ionizing electrons. Although the technique gives essentially the same results as monoenergetic methods, it is much easier experimentally. Ionization-efficiency curves are given for the inert-gas ions Ar+, Kr+, and Xe+ as well as the molecular ions CO+, N 2 +, and O2+, The "breaks" in the efficiency curves are presented and the results are compared to previously reported monoenergetic electron-impact data.

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