. Conduction of electricity through gases and radio-activity; a text-book with experiments . ntried to overcome this difficulty, but the most successful onesare those which have resulted in the automatic regulating form of this is shown in Fig. 29, in which AB is the mainbulb of the usual form. To this is attached a small side tube ab,with two electrodes, in which is placed in some cases a littlepowdered caustic potash while in others one of the electrodes 64 AUTOMATIC FOCUS TUBE 65 has mica sheets attached. The anode of this small tube isattached to the anode of the main bulb, while
. Conduction of electricity through gases and radio-activity; a text-book with experiments . ntried to overcome this difficulty, but the most successful onesare those which have resulted in the automatic regulating form of this is shown in Fig. 29, in which AB is the mainbulb of the usual form. To this is attached a small side tube ab,with two electrodes, in which is placed in some cases a littlepowdered caustic potash while in others one of the electrodes 64 AUTOMATIC FOCUS TUBE 65 has mica sheets attached. The anode of this small tube isattached to the anode of the main bulb, while the cathode hasa wire W attached, and between this wire and the maincathode is a spark gap H. When, by the continued passage ofthe discharge through the main bulb, the pressure becomes lessand the resistance between the main electrodes consequentlygreater the discharge will then pass across the spark gap, if itis short enough to make its resistance sufficiently small, andthrough the small tube ab. The heat of the discharge throughab will liberate vapor from the caustic potash or the mica. Fig. 29. which will raise the pressure in the whole system and lowerthe resistance and allow the discharge to pass through the mainbulb again. It will continue to pass through AB until thepressure becomes too low again, when it will once more passthrough ab. The pressure is thus automatically longer the spark gap H the lower will the pressure in ABbecome before the discharge will pass across H and throughab. Therefore by adjusting the length of the gap H the bulbmay be made to work at any desired pressure within certainlimits. The longer the spark gap the harder will be the 66 RONTGEN RAYS rays produced. This type of bulb is very regular in its actionand gives very satisfactory results.* A somewhat modified and improved type on the same prin-ciple is shown in Fig. 30. In this a side tube K, containing achemical which gives off vapor when heated and absorbs it
Size: 1881px × 1328px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookid, booksubjectradioactivity
