The adsorption of CO on Ba getter films in a pressure range of 10-9 to 10-4mmHg has been investigated by the flow method. The pumping speed of getter film at the initial stage of adsorption is studied in detail in connection with the sticking probability a for CO molecules striking the surface of fresh Ba film. When the ultimate vacuum of the system is poor (in the order of 10-8mmHg), or the gas sample contains impurity gas of the order of 10-4, the pressure of the residual gas not adsorbed by getter film masks that of CO at the initial stage, so that the corresponding pumping speed appears too small. However, from the results obtained under the best condi-tions, the value of a at 0°C is derived to be 0.4 to 1.0 by assuming that the roughness factor of getter films lies between 5 and 10. The increase in the adsorption temperature or surface area results in the increase of the adsorption capacity, but the initial pumping speed appears unchanged probably because of the presence of non-adsorbable impurity gas.
A new barium getter called “Batitan getter” has been devised using a titanium wire as a reducing agent for barium oxide produced by thermal decomposition of barium carbonate. Some properties of this getter are compared with those of Batalum getter. At the out-gassing, the total gas evolution of the former is larger than the latter, which is due to the occluded hydrogen in titanium wire. In both cases, the liberated gas is mainly composed of carbon monoxide and carbon dioxide. The evaporation of barium from “Batitan getter” commences at temperatures (_??_1150°C) lower than the flashing temperature of Batalum getter (_??_1400°C) which complies with chemical thermodynamic considerations. The results of life tests of some vacuum tubes have proved the efficacy of the getter.
When a rubber cord is hit transversely with a bullet, some remarkable phenomena are observed which are different from those under static testing. They are: 1) The elongation of the cord amounts to 2200%, while the static breaking elongation is about 800%. 2) The breaking elongation becomes smaller with the increase of initial tension. 3) The larger the impact velocity and the smaller the initial tension, the larger the elongation. 4) An abrupt bending deformation is developed and propagates along the cord, which may be considered as a kind of shock wave. 5) When the initial tension is low, the propagation velocity of the bending deformation rises rapidly with the increase of the tension. But the rate of the rise becomes slower above a certain value of the tension. The velocity is higher than that of the elastic transverse vibrations under the same tension measured by Melde's method.
The rotary grating method has been applied for rapid measuring of ultrasonic velocities in liquids. In Debye-Sears ultrasonic diffraction system, when an optical grating whose constant is equal to the wavelength is inserted in the light path so as to overlap the ultrasonic grating, the diffraction image is just the same as that when either one of the gratings singly exists. But when the constant of the optical grating is changed, each line of the diffraction image developes its satellite lines and the whole pattern becomes complicated. It is known that when an optical grating of the proper constant d0 is rotated by the angle θ around the optical path, the effective constant d of the grating is given by the law d=d0/sin θ. Hence, by rotating the grating and observing the position at which the satellite lines coincide with the main lines, the angle θ that corresponds to the wavelength can be determined and thus the velocity is calculated if the frequency is known. The range of velocity measurement of the apparatus is 900 m/sec to 2000 m/sec. The accuracy of the measurement depends upon the accuracy of detecting the coincidence of the satellite lines with the main lines. In the present apparatus, the accuracy of coincidence detection is approximately ±0.2°. This means that the error of the velocity measurement is about 0.7% for medium velocity substances (for instance, water) and 0.4% for low velocity substances (for instance, chloroform).
By the method of radioactive tracer, wear-reducing effectiveness of several series of aromatic compounds has been measured and compared with the coefficient of friction, the molecular orientation on metallic surfaces and the chemical structure. There seem to exist close relations among these characteristics. Both the wear and friction in the boundary condition show almost similar tendencies and diminish as the alkyl chain becomes longer, but certain series of aromatic compounds have the best lubrication characteristics in the neighbourhood of 12 atoms of carbon. The lubrication characteristics of dibenzoic compounds are different from those of aliphatic and monobenzoic compounds and the wear with the formers is relatively small in spite of a large friction.
High voltage measurement based on electro-optical effect of ADP crystal plate is described. Though ADP crystal is uniaxial, when voltage is applied across the crystal, the indey ellipsoid in the crystal is rotated and the lengths of the axes change. For a field Ez in z direction across the Z-cut crystal plate, the axes of the ellipsoid are rotated by -45° in xy plane independent of Ez, and the birefringence along z-axis is proportional to Ez. Then the retardation of lights in z direction becomes proportional to applied voltage across the crystal plate. Using Senarmont compensator method, the retardation is measured by rotation of the analyzer. Proportionality of this angle of rotation to the applied voltage makes the measurement of the latter possible. Accuracy of measurement is about ±50 V over any range. Measured value of electro-optical coefficient γ63 of ADP crystal is 8.48×10-7cm/kV.