Many theoretical papers dealing with instantaneous loading of X-ray tubes have been published but none so far with detailed experimental results. The writer measured the temperature of focusing surface on anode by means of a device of reading instantaneous colour temperature using two photomultipliers of special design. The distribution of electron density on the focusing surface was also observed. The instantaneous input power P for a given maximum temperature of the focusing surface is calculated by P=SQ0t-n where S is the actual area of the focused surface, t the loading time, and Q0 and n constants. This formula holds good within experimental error if the loading time is 0.1_??_10 sac. Q0 depends very much on the breadth of the focus, the distribution of erectron density and the high tension circuit system (the wave form of the tube voltage). It also depends on the thick-ness of W-target but slightly. The breadth of the focus, the high tension circuit system and the thick-ness of W-target affect the value of n a little.
In mass spectrometry, it is important to confirm the mass number of spectrum obtained on recorder. To simplify the mass marking, a device was made by employing a servo-system with a magnetron to obtain a perfect linear recording of the spectrum.
A balanced three stage d. c. amplifier has been constructed and employed with sufficient and gain in investigating biophysical electricity. Exceptionally good stability is realized by ap-plying the plate potential for the first stage amplifier from the self-biased cathode potential of the last stage, and the whole circuit operates as self-balanced. The over-all gain, or conductance has been measured to be not less than 100 Ohms. As to the stability, the input equivalent drift voltage of less than 20 microvolts per hour is easily obtained after a few hours' warming-up.
The relation between contact potential and rectification properties of selenium surface after heat treatment was observed. The contact potential increase at first about a few tenth of a volt, remains so for a long time and then decreases. This is a direct evidence of a chemical action between the sur-face layer and the moisture in air. With a stick of woodmetal on selenium surface, the rectification ratio was found to decrease immediately after the heat treatment and become minimum at the maxi-mum contact potential. Some protective coating of insulating nature is effective in increasing the rectification ratio; it has no effect on the number of impurity level but increases the diffusion poten-tial and decreases the capacity of the barrier.