Effects of trace gases and water vapor on the diffusion coefficient of polonium-218.

The two-filter method described by Thomas and LeClare was used to investigate the effects of trace concentrations of nitric oxide and nitrogen dioxide in dry nitrogen on the diffusion coefficient of radium A (polonium-218). Charged radium A was neutralized in 10 parts per million (ppm) nitrogen dioxide in dry nitrogen, in 8.3 ppm nitric oxide in dry 92 percent nitrogen and 8 percent oxygen, and in nitrogen with 20 and 80 percent relative humidity. No neutralization was seen in dry nitrogen, dry oxygen, dry air, or 10 ppm nitric oxide in dry nitrogen. The diffusion coefficient of the neutral radium A species was found to be 0.079 square centimeters per second, regardless of the relative humidity of the nitrogen gas atmosphere. Lower values were observed for charged species.

Particle size distribution and chemical composition of coal-tar fumes.

The study was intended to characterize the chemical and physical nature of coal-tar fumes emitted from spreading applications of coal tar. Two separate experiments were performed. The first resulted in the determination of a coal-tar fume particle size distribution. The second experiment resulted in the identification of the primary compounds found in collected tar fumes and a determination of their relative concentration.