16 M. Stem, unpublished data, Corrosion Laboratory, M.I.T.17 G. Gemmell found that the corrosion rate for mild steel (0.06 per cent C) in deaerated 4 per cent NaCl of pH 5.6 was zero within the experimental variations of such measurements, whereas at pH 3.8 the rate averaged 24 mg/dm2/day (mdd), in agreement with Stern's value for iron. This means that the rate at pH 5.6 must be less than perhaps the order of 0.5 mdd. Pryor and Cohen, J. Electrochem. Soc., 100, 206 (1953), report a value of 0.3 mdd for the corrosion rate of mild steel in deaerated water. . 21 Based on atomic percentages and atomic radii of Cd and Hg, the fraction of surface composed of Cd atoms for 10-13 per cent Cd amalgam is equal to about 0.2. However, in measurements of anodic polarization, this fraction remains constant up to fairly high current densities because the potential for formation of Hg2++ is not approached so long as the surface concentration of Cd is appreciable. Therefore, measured values of b are for an anodic area similar to that which applies to the corrosion process, and, hence, the apparent value of A in eq. (2) under these conditions is equal to unity. Data by Wagner and Traud, op. cit., for zinc amalgam confirm this conclusion. For iron, on the other hand, the anodic surface becomes larger, the higher the value of current density externally applied for anodic polarization, and, hence, A is usually less than unity.

Diffraction dissociation of both the beam and target particles has been observed in 150-GeV/c .ir--p interactions in the Fermilab 30-in.-bubble-chamber--proportional-wirechambe hybrid spectrometer. The dissociations are observed as recoil systems opposite leading particles, the signals of which are separated from background where appropriate by a variant of the Van Hove sector cut, thus allowing the high-mass portion of the spectrum to be observed. Pion dissociation has a cross section of 1758-t. 105 pb, divided among two-, four., and six-prong events; some p0 production is seen and comes primarily from the n--t2n-.ir + channel. The proton dissociation cross section is 1726, 100 pb, again divided among two-, four-, and six-prong events. The final state contains a neutron more frequently than a proton in the twoand six-prong events, a proton more frequently in the four-prong events. Production of A + + is observed in the p +p.irf T -dissociations. transferring four-momenhim to other particles,

No abstract

The Brookhaven National Laboratory twenty-inch liquid hydrogen bubble chamber was exposed to a monoenergetic beam of 2.85-Bev protons, elastically scattered from a carbon target in the internal beam of the Cosmotron. All two-prong events, excluding strange particle events, have been studied by the Yale High-Energy Group. The remaining interactions have been studied by the Brookhaven Bubble Chamber Group. Elastic scattering was found to be mostly pure diffraction scattering at center-ofmass angles up to about thirty-five degrees. Some phase shift and/or tapering of the proton edge was required to fit the data at larger angles. No polarization effects in the proton-carbon scattering were observed using hydrogen as an analyzer of polarized protons. Nucleonic isobar formation in the T=3/2, J = 3/2 state was found to account for a large part of single pion production. High-orbital angular-momentum states were found to be greatly favored in single pion production. The isobar model of Lindenbaum and Sternheimer gave good agreement with the observed nucleon and pion energy spectra. No polarization or alignment effects were observed for the isobar assumed in this model.