. The Astrophysical journal. led in from the top, as indicated in the platinum wire used in making up these cells had been pre-viously heated to near the melting-point in a good vacuum, inorder to free it of dissolved gases. Between the last bulb and themolecular pump was inserted a liquid-air trap T. The dotted lineindicates the oven in which the cells C to iv were subsequentlyheated during exhaust. The end of the tube A was left open for PHOTO-ELECTRIC CURRENT AND ILLUMINATION 19 the introduction of the potassium (in the form of balls). A wad ofglass wool was fitted in rather loos
. The Astrophysical journal. led in from the top, as indicated in the platinum wire used in making up these cells had been pre-viously heated to near the melting-point in a good vacuum, inorder to free it of dissolved gases. Between the last bulb and themolecular pump was inserted a liquid-air trap T. The dotted lineindicates the oven in which the cells C to iv were subsequentlyheated during exhaust. The end of the tube A was left open for PHOTO-ELECTRIC CURRENT AND ILLUMINATION 19 the introduction of the potassium (in the form of balls). A wad ofglass wool was fitted in rather loosely at g, and after the potassiumballs had been introduced into A, another plug of glass wool wasinserted at h and the open end closed up \\ith a torch. The potas-sium used was previously washed in ether and then dried betweenfilter-papers. After closing up tube A, the pump was started and the bulbsC to K heated for an hour at 350° C. ]\Ieanwhile the potassium inA was melted and allowed to run into B. During the bake-out of. Fig. 5.^—Arrangement of apparatus to investigate photo-electric effect frommultiph distilled potassium in high vacuum. the rest of the apparatus, the metal in B was heated gently, so thatwhile it did not distil into C, it was yet kept hot enough for thegradual ehmination of any gases that might be contained in the end of the hour, the oven was raised and the metal distiUedfrom B into C Only about three-quarters of the metal in one bulbwas distilled into the next. This permitted the gradual eliminationof sodium which was undoubtedly present in the potassium. After distillation into C, the bulb B was sealed off at ^, and thephoto-electric sensitiveness of the metal in C determined, whileit was still in a molten condition. The potassium was then dis-tilled in succession through the different bulbs, the latter beingsealed off after most of their potassium content had been distilled 20 HERBERT E. IVES, SAUL DUSHMAN, AND E. KARRER out. The whole operatio
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectspectru, bookyear1895
