In the coulometric reduction of oxides on tin-plate surfaces, the quantity of oxides measured is influenced by the composition of the electrolyte,

Investigation of an alloy-tin couple (ATC) test described by Kamm and associates indicates a good correlation between ATC current and grapefruit juice pack life. The effect of Sn(II) additions to the electrolyte, of the source of the tin anode, of variations in sample and anode area, of resistance of the external and internal circuit, and of scratches on the sample surface is discussed. Increasing alloy-layer thickness decreases the ATC current. ATC measurements made in grapefruit, tomato, and pineapple juices rank various lots of tin plate similarly, but in prune juice a different ranking is observed. This difference is consistent with previous data, which showed the mechanism of corrosion of tin plate for grapefruit and tomato juices to be different from that of prune juice. 8.3.5, 6.3.14

An experimental technique is described wherein the diffusion of hydrogen through a steel specimen is followed by electrode‐potential measurements. In this technique, one surface of the specimen is exposed to acid and the other surface to a sodium dichromate solution. As the hydrogen produced by acid attack at the steel surface diffuses to the other surface, the potential of the surface in contact with the Na2Cr2O7 solution changes with time, and changes of potential ranging from 300 mv to 900 mv are observed. It is believed that the observed potential changes result from the reduction of the dichromate‐produced passive film by diffused hydrogen. The effect of variations in steel composition and thickness, acid composition and concentration, and sodium dichromate concentration on the phenomenon is reported.