Treatment of Columbia River water with aluminum sulfate and activated silica to coagulate undesirable solids has long been established as a satisfactory method for obtaining high quality process water to cool the Hanford reactors. The activated silica used in this process has been prepared by neutralization of less than 92 per cent of the initial alkalinity of a dilute solution of sodium silicate by mixing with dilute sulfuric acid. This mixture is then aged for a period of time equal to one-fourth to one-half of the gel time of the mixture. The concentration of the resulting activated silica solution is not permitted to exceed 1.6 per cent SiO₂ by weight. This activated silica preparation is presently carried out as a batch process with aging times on the order of one hour. A continuous silica activator recently made commercially available by the Omega Machine Company of Providence, Rhode Island, offers several potential advantages over other activated silica facility designs being considered. This continuous silica activator utilizes neutralization of up to 96 per cent of the initial alkalinity of the sodium silicate. The high percentage of neutralization results in gel times of approximately fifteen minutes for the concentrated solutions (up to 1.6 …

It is usual to determine the density of neutrons by using foils of metals which become radioactive as a result of bombardment in the region under investigation. From the rate of disintegration of the newly formed radioactive element the number of neutrons absorbed can be calculated. By use of the capture cross section of the element of which the foil is composed the density of the neutrons can then be computed. By counting the alpha particles from a bismuth foil of known weight after exposure to neutrons the density of the neutrons which produced this activity can be calculated. The least accurately known value which enters into this evaluation is the capture cross-section of bismuth for pile neutrons. This value may be improved by future measurements. It is of importance only for absolute measurements of neutron density so that relative values can be measured with considerable accuracy on the basis of known data.

Report presenting tests on a scale model of a four-engine transport airplane to determine the stability characteristics, empennage control-surface effectiveness, the effect of propeller rotation on longitudinal stability, and a method for carrying spare wing panels under the fuselage. The effect of two models of wing power operation on the characteristics of the model was studied. The results indicate that the model possess satisfactory stick-fixed longitudinal stability for all normal flight conditions except for high power with flaps extended.