Physics progress report

Difficulty encountered in the preparation of a pure postum sample for vapor pressure measurements with the quartz sickle gauge is tentatively ascribed to the existence of lead postumide. The modifications which have been made since June 1, 1948 in the apparatus for the measurement of vapor pressure by effusion are discussed. The apparatus in its new form is essentially complete and awaits the delivery of a Dewar flask before measurements are begun. In the preparation of a sample for the determination of the purity of postum with the vacuum balance, difficulties similar to those in Section 1 above were encountered. Resistivity of Postum - No progress. Ninety-one neutron counts were made for other groups. A specially shaped postum sample has been prepared for use in the attempts to flatten the response of the lead-geometry gamma counter. Patterns obtained from the recently acquired sample of elemental postum show the slight increase in unit cell size previously reported; however, the formation of the PbQ compound was detected much earlier than with the older sample