. The Astrophysical journal. efor the reason that no two of these cells are ahke. About half showillumination-current curves bending upward; the rest show curvesbending downward. The certain elimination of nearly all thegaseous atmosphere and the reduction of all the cells to the samecondition of vacuum, as shown by their characteristic curves, havenot reduced them to uniformity in their behavior to light. The extraordinary diversity of behavior of these cells is shownby the group of curves in Fig. 4. These, obtained (with the excep-tion of cell e) from the new high-vacua cells, were measured
. The Astrophysical journal. efor the reason that no two of these cells are ahke. About half showillumination-current curves bending upward; the rest show curvesbending downward. The certain elimination of nearly all thegaseous atmosphere and the reduction of all the cells to the samecondition of vacuum, as shown by their characteristic curves, havenot reduced them to uniformity in their behavior to light. The extraordinary diversity of behavior of these cells is shownby the group of curves in Fig. 4. These, obtained (with the excep-tion of cell e) from the new high-vacua cells, were measured upona sensitive galvanometer, the currents being about one hundredtimes those worked with in the previous investigation. This shift PHOTO-ELECTRIC CURRENT AND ILLUMINATION 17 of instruments was made partly to make doubly sure that noinstrumental peculiarities were figuring in the results, and partlybecause it was becoming evident that all the illumination-currentpeculiarities were accentuated with high voltages and 12 16 20 Illumination 24 Fig. 4.—Illumination-current characteristics of a group of high-vacua cells It is evident from these curves that the real cause of the non-rectilinear light-current relationship can hardly be the presence ofgas. The striking effects of varying the gas pressure must beascribed to the result of these changes on some other fundamentalcause. Further support for this belief was found in trying the effects ofvery intense illumination on cell p. If the gas present is a real iS HERBERT E. IVES, SAUL DUSHMAN, AND E. KARRER cause of the effects found, it is to be expected that if the appliedvoltage is held below the ionization voltage—that is, 6 or 7 volts—its influence should be minimized. By using a large nitrogen-filledtungsten lamp, illuminations up to 50,000 meter-candles were triedwith only 2 volts applied, the currents being about fifty times thosewith the galvanometer previously employed, or up to 2X10-^amperes (they were measu
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectspectru, bookyear1895
