Mining engineer changes

Le Chatelier served as an army lieutenant during the Franco-Pmssian War in 1870, after which he returned to school to finish his degree. His intention was to become a mining engineer, but he changed his mind when he was offered a professorship in chemistry at the Ecole des Mines in Paris. 

To determine the fate of formaldehyde and formic acid in a coal mine, an unused shaft about 120 m long and 6 m2 in cross sectional area was selected for study. With a ventilation air flow of 190 m3/min and an engine exhaust flow of 1.5 m3/min, complete exhaust dispersion and dilution was observed in about 10 m. Samples collected in the mine air downstream of the diesel engine indicate no significant change in formic acid concentration at increasing distances from the engine (Table VIII). This is certainly not consistent with the loss of formaldehyde in the same interval. The mechanism for loss of formaldehyde is apparently not a gas phase oxidation to formic acid. Interaction with surfaces may be a more suitable explanation of the observed reduction in formaldehyde concentrations. 

Results of analysis of formic acid in diesel engine exhaust subjected to various forms of post-combustion control, i.e., catalytic oxidation and water conditioning, indicate both a reduction of formic acid due to oxidation in the catalyst and dissolution in the water scrubber. In-mine analysis of formic acid at increasing distances from a source of diesel exhaust indicates that no significant change in concentration occurs. This finding contradicts a hypothesis that formaldehyde concentration decreases with increasing distance due to gas phase oxidation to formic acid. Surface reactions may, however, be important sinks for formaldehyde. 

This paper deals mainly with the condensation of trace concentrations of radioactive vapor onto spherical particles of a substrate. For this situation the relation between the engineering approach, the molecular approach, and the fluid-dynamic approach are illustrated for several different cases of rate limitation. From these considerations criteria are derived for the use of basic physical and chemical parameters to predict the rate-controlling step or steps. Finally, the effect of changing temperature is considered and the groundwork is thereby laid for a kinetic approach to predicting fallout formation. The relation of these approaches to the escape of fission products from reactor fuel and to the deposition of radon and thoron daughters on dust particles in a uranium mine is indicated. 

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