Now, representing the general formula of the oxide obtained as PriOy, the ratio of y/x may be calculated by the relation x (atomic weight of praseodymium) + y (atomic w'eight of oxygen)

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Presented at the 116th National Meeting of the American Chemical Society, Atlantic City, N. 3., September 1949. NOTE: References 1, 2, and 4 are considered the first thre papers in this series.1. Phenolphthalein and total alkalinity, expressed as percent Na2O in the undissolved sample.Alkalinity was measured by titrating 50 ml. of 0.3 percent solution of the detergent in distilled water using 0. 1000 N HCl with phenolphthalein and a mixed indicator 2 with an endpoint approximately that of methyl orange. The number of ml. HCI x 2.067 equals percentage of Na2O in the original sample.I Hardness about 100 ppm. 2 0.02 grams methyl red ground in mortar with 7.4 ml. N/20 NaOH, 0.109 Brom cresol green ground with 29 ml. N/20 NaOH. (Make up to 100 ml. with distilled water.) 656May 25, 19512. Surface tension of a 0.3 percent solution in distilled water at room temperature.3. Interfacial tension between a 0.3 percent water solution and mineral and cottonseed oils.Surface and interfacial tension were measured with a DuNouy precision ring tensiometer.4. Emulsifying ability of a 0.3 percent solution for mineral and and cottonseed oils.Emulsifying ability was measured with the following qualitative test: 20 ml. of 0.3 percent detergent solution and 10 ml. of oil were carefully poured in a 1-inch test tube. After 10 quick inversions the size of globules and rate of breakdown were observed. Ratings were as follows:Excellent-small globules, no breakdown in 30 minutes. Good-medium globules, emulsion standing from 15-20 minutes.Fair-large globules, emulsion standing from 3-5 minutes.Poor-large globules breaking down in less than 2 minutes.5. pH of a 0.3 solution.pH was determined with a Leeds and Northup electrometric pH meter using a glass electrode. A correction for sodium ions was made.6. Sequestering ability.Sequestering ability was determined by titrating 100 ml. of 0.3 percent detergent solution at 600 C. with a solution of CaCl2 containing the equivalent of 10 mg. CaCO3 per ml. until the first permanent turbidity was observed. Results were expressed as ppm CaCO3 absorbed by the solution (4).

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In exploratory studies on the removal of radioactive wastes by biological treatment, information on the possibility of maintaining a zooglea-activated sludge on common foods was needed.Experiments were conducted using various organic nutrients.Investigation of the effects of pH and amount of food added indicated that a daily total dose of 1000 p.p.m. of flour and dextrose in a 3 to 1 ratio adjusted to a pH of about 9.0 was optimum for maintaining a good settling sludge with low suspended solids in the supernatant. Studies of the requirements and utilization of nitrogen, phosphorus, and potassium showed that nitrogen and potassium in the feed and Cincinnati tap water were sufficient to maintain a good quality of sludge, but that the daily addition of 3.0 p.p.m. of phosphorus was required.It was concluded that common foods supplemented with essential minerals can be fed to maintain good control of the activated sludge process in the treatment of radioactive waste.