In the previous report, a semi-theoretical expression for water-suction of wood (cryptomeria) during a short time after soaking was derived. In this report, the temperature effect is discussed. In general, it is obvious that the viscosity of water is one of the most important factors determining the suction velocity, for the viscosity varies with temperature. Besides, it seems that when the temperature of water sucked in wood suddenly drops, both the contraction of gas and the con-densation of water-vapour play prominent parts in the suction process; the meniscus of water sucked in capillaries may rise by the contraction of gas which is in contact with water and is locked within the wood, and the advancing contact angles to internal walls of comparatively hydrophobic capillaries may considerably decrease by the condensation of water-vapour on the walls.
A study is made whether the moisture content and height in fibre direction of a wood specimen (cryptomeria) have effects on the velocity of suction during a short time after soaking by paying attention to the head loss of gas flow through the specimen. As regards the moisture content, water is sucked faster in dry specimen than in normally moist one owing to rapid vapour-sorption of the former. But if the water content of a comparatively hydrophobic specimen amounts to about 24% in the atmosphere of about 960 relative humidity, it is shown that the suction velocity becomes greater than that of normally moist one on account of remarkable decrease in advancing contact angle between water and capillary wall. But, as to a specimen kept in saturated water vapour, the head loss of gas flow in its capillaries may be much greater than that in a normal specimen and the gas in some of the capillaries of the former is more or less trapped there by wet capillary walls, and therefore, the flow of gas which is in contact with rising water meniscus in the capillary is easily obstructed as the capillary walls become wet by water already risen freely in neighbouring capillaries. Change in height of specimen, if the height is less than 10 cm, seems to have no effect on the suction velocity.
Applicability of vacuum arc as a source for evaporating metals is investigated. Intermittent discharge type arc with vibrating electrode and continuous discharge type arc are examined at pressures lower than 5×10-4 mm Hg. With the former type, almost all metals seem able to be used for evaporation; its characteristic is that glossy films of refractory metals such as W, Mo and Pt are easily deposited. Erosion of electrode is always at the cathode causing building up of protrusion on the anode surface. Effect of potential applied to substrate is not so distinctive as in Vodar's experiment; it appears rather contrary to his result. The arcing is typically cathodic, the mechanism of which is also considered. As to the continuous discharge type, some of its fundamental properties are studied. For metals of low boiling temperature such as Zn, this type of arc is easily maintained which seems however too violent for deposition. For refractory metals, the arc appears difficult to be maintained with current below 80A. Pre-heating of the cathode may remove this difficulty.
In order to confirm, whether or not experimental results agree with many empirical and theoretical formulas which have been proposed for dispersed systems with two different substances, dielectric constants of mercury-vaserium mixtures varying 0_??_22.7% in volume ratio and packed glass balls are measured at 20°C by using frequency of 2 megacycles. In the case of glass balls, the size effect of dielectric constants is examined on three different sizes of the ball and the effect is not found up to 0.8 mm in diameter. These results are properly represented by Bruggeman's formula and are in line with the authors' previous report on emulsion. Treatment of the results by “liquid immersed method” is discussed and it is found that the variation of the dielectric constant of dispersed or medium substance can be affected considerably, if a suitable substance is used for mixing. Temperature variation of the dielectric constant of NH4I, for example, is investigated and the results nearly agree with the expectation.
Spectrophotometric study of the colour of pearl has been made on the shell of cultured pearl by removing its seed. The only effective pigment in pearl layer is of orange colour. If this pigmentation is dence, the pearl appears yellow, and if light, the colouring is not affected. So-called body colour of pearl is determined by the structure thus: 1. It is blueish if brownish black organic matter is interlaid between the shell and the seed. 2. If air is present underneath the shell, total reflection of light in the layer makes the pearl appear silvery. 3. Coarse crystalline structure of the layer gives white colouring. So-called surface colour of pearl is by scattering and surface reflection of light. The scattering is caused by two kinds of layer, one rich in organic matter and the other rich in inorganic matter, lying one on top of the other with uneven boundary. Considering that the surface colouring is due to interference of polarized light, the degree of polarization of reflected light is investigated in relation to the colouring. The pearl layer appears as optically monoaxial with its axis perpendicular to the surface.
In perceiving the vibration tangible to the tips of fingers, variation of the perception under varied conditions is studied by using the detecting part of vibration and matching pressure that are already made known. The relation of the frequency of vibration to the strongest perception for each condition is found. Characteristic of threshold vibration has been observed on the writer's own body over a range from 10 cps to 500 cps with a vertical vibration generator by using the detecting part of vibration, matching contact pressure and the condition to produce the strongest perception. The characteristic is represented approximately by φ=3.3×10-2_??_•_??_ where φ: the threshold vibration in μ=10-3mm ƒ: the frequency per sec., h2=0.3: a damping constant, n1=160 cps: 1st order natural frequency of vibration, n2=310 cps: 2nd order natural frequency of vibration. In this expression, bone conduction is not considered.
An investigation has been made of the effects of 2 MeV deuteron bombardment by means of cyclotron on the following optical properties of copper-activated zinc sulfide phosphor, i.e. the luminescent brightness, growth and decay of luminescent emission at room and near liquid air temperatures, and glow curve, under the excitation both in the copper absorption band and in the fundamental absorption band of ZnS host crystal (called “ copper excitation “and” host excitation”, respectively). Deuteron bombardment gives rise to the following effects. The color of the phosphor becomes pale brown, and the luminescent brightness is lowered very much. Principally, the growth of lumines-cence becomes slower, while the decay becomes faster, than with an unbombarded sample. At low temperatures, however, these tendencies are not so remarkable as at room temperature; they seem to die out under the host excitation. Both growth and decay at low temperatures are generally slower than at room temperature. The glow curve of an unbombarded sample has three peaks located at about 320° (called “A” peak), 270° (“B” peak), and 200° K (“C” peak). For a bombarded sample, the “A” peak becomes very small and the “B” peak sharp and small, both shifting to lower temperatures. The “C” peak shifts to a lower temperature and several small peaks are created on its high temperature side. If samples which had different degrees of bombardment are compared with one another, it is shown that the more the sample is irradiated, the smaller the light sum shown by glow curves becomes. The effect of annealing on bombarded samples has been examined, and it is found that the damage can fairly well be removed by annealing the samples at 550°C. The following conclusions can be drawn from the experimental results. 1) Decomposition of zinc sulfide is scarcely produced. 2) Displacement of ions strongly induced by bombardment will produce various types of traps. Most of the aforementioned changes of optical properties caused by bombardment are attributed to these new traps, and moreover many of these traps, especially deep ones, act as killers.
Effects of the length of channel and the kind of granular masses on the flow rate have been investigated. Samples are seashore sands sieved by Japanese Industrial Standard sieves. The hopper by which the sample is supplied is provided with a curved tube of rectangular cross section. By adjusting a stopping plate which can be raised or lowered at will, the outlet area is varied. The obtained results are as follows. If the channel is not connected with the hopper, the relation between the flow rate W from the hopper alone and the raised height of the stopping plate x can be shown as W=Kxn where the constant n is between 1.5 and 1.6. The larger the granule, the larger the constant. When the channel is connected with the hopper, a quite different state is observed. If the length of the channel is long enough, the flow rate W increases with x at first, but when W reaches a certain value it remains constant. The saturation flow rate depends on the inclination and the kind of granules, but is independent of the length of the channel. For granules with small saturation flow rates, the angle of friction against the channel bottom is small but the angle of repose is large. It seems that the internal friction of the mass of granules is at least one important cause of the flow rate becoming saturated.