Within practical ranges of concerned parameters in hot shaping of baked aluminium phenol plastics, physical meaning of bending strength is dealt with and the possibility of controlling the strength of baked body is suggested. Experiments made by the latin square method succeeded in establishing a convenient direction for determining the correct forming pressure. The mode of fracturing is separation, typical of brittle materials. In some cases, chevron-like patterns are observed on fractured faces. The chevron pattern generally appears on fractured faces when the forming pressure is high, the size of specimen is large or the content of liquid phenol plastics is small.
A superconducting “chopper”-amplifier with no movable parts and of d. c. voltage sensitivity better than 10-10 volts when used free from the effect of magnetic field, better than 10-9 volts when used in a magnetic field up to 7 K. Oe., is described. Compactness of cryostat equipment and stability of apparatus were the chief requirements in designing. Though the use in magnetic field and the setting of temperature as desired are not without difficulty, the instrument proved useful for the study of thermoelectric and galvano-magnetic effects in metals at low temperatures.
In measuring the dew point below 0°C with a dew point hygrometer, it is necessary to ascertain whether the dew produced on the mirror is in the form of water or ice, which is not easy to tell. When the dew is in the course of freezing, the dew point is likely to appear lower than the true value. Examination of the cause of supercooling of dew drop by the use of a dew point hygro-meter of photocell type revealed that the minimum of the temperature and the condition of mirror surface are found to be the important factors that decide how the dew is formed. The lower this minimum of temperature and the cleaner the mirror surface, it is more improbable for the dew to become supercooled; below -40.5°±0.5°C, supercooling did not occur, and a mirror of perfect black condensation did not give rise to supercooling, which was found ascribable to the largeness of dew drop.
Dehydration of wood by infrared radiation of 11500Å maximum wavelength is investigated. The radiant energy is from a 100V 250W electric lamp bulb, and air condition at the sample-surface is controlled. Drying rate curves are analyzed according to how the drying is processed and comparison is made between this mode of drying and drying by convection of heated air. The drying is examined concerning the air condition, intensity of radiant energy, sample thickness, initial moisture content, critical moisture content, optical properties of sample material and orientation of tracheids of wood. The orientation of tracheids has a large effect on the rate of drying. Permeation of radiant energy into samples is seen facilitated by making the diffusion of contained water favorable.
The surface potential measurement is applied to make clear the behavior of molecules that-e are adsorbed on a metal surface and cause the boundary lubrication. When spindle oil with or without the addition of stearic acid is spread on a cuprous-oxide-surfaced copper plate, the surface potential increases for 10 to 20minutes. This seems to tell the process of polar molecules in the oil being adsorbed and oriented on the metal surface. The increase of the potential is augmented with the concentration of the acid and is stopped at the concentration of about 0.4%, which suggests the completion of the first monomolecular layer. When a lubricated surface of steadied surface potential is rubbed with care not to originate frictional electricity, the potential undergoes a temporary change, the change being larger as the concentration of the acid is lower, suggesting desorption of adsorbed molecules and re-adsorption. of the acid molecules. When a surface lubricated with pure spindle oil alone is rubbed, the po-tential decreases remarkably recovering very slowly. In this case, even the cuprous oxide layer-seems to be rubbed off. In general, the extent of wear on the surface can be estimated by surface potential measure-ment from the difference between the velocities of adsorption of polar molecules and oxidation of the metal surface.
Benzene solution of tristearin at various temperatures segregates tristearin in single crystals, needle-like crystals or in amorphous state depending on circumstances. The crystals are examined under polarizing and electron microscopes for their shape and microstructure, and they are found. to be of R-form with long spacing of 45Å and short spacing of 4.61Å from their X-ray diffraction patterns. The solution at 20°C gives single crystals of plate form when the concentration is low, but crystals of needle form when the concentration is high. At especially low concentrations, the grown single crystals have screw dislocations in steps of 40Å high. The crystals that grew in needles have also steps which are however 300Å_??_450Å in height suggesting that there are 8-10 molecular layers in every one of these steps.