This article discusses experiments that found that the germicidal action of a specified amount of silver was related to the concentration of silver ions rather than to the physical nature of the silver from which the ions were originally derived. Neither the presence or absence of light nor the change in the density of test organisms within the range of 1,680 – 1,800,000 per milliliter produces a discernible effect on the bactericidal action of silver. Phosphate tends to decrease germicidal efficiency, whereas increases of pH accelerate death rates. Of the several neutralizers studied, a mixture of sodium thiosulfate and sodium thioglycollate was found to be most efficient. In the presence of inefficient neutralizers, bacteriostasis may be mistaken for bactericidal action. When silver‐contaminated glass is reused, some of the silver is desorbed and exerts a germicidal action. In these studies, boiling in sodium chloride solution was the most effective method of removing the silver from glassware. Radioactive Ag110m is useful in determining silver concentrations in solution and the residual remaining on surfaces.
Gamma scintillation spectra were obtained with several sizes of NaI( Tl) crystal, Pilot B plastic, and liquid detectors which were immersed in solutions of gamma-emitting nuclides contained in a 2,3OO-gal tank. The count rates for gamma photons in the Mev energy range were proportional to detector volumes. Integral count rates with plastic and liquid detectors were, respectively, 39% and 335% of the rate with NaI( Tl) . Factors in the selection of detectors for field use are discussed.
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