Scientific American Supplement, No. 492, June 6, 1885

Excerpt: ...of selenium cells? One year ago I made the foregoing suggestion in a paper on A New Form of Selenium Cell, presented before this Association at Minneapolis. I am now at liberty to state that my photo-electric battery, presently to be described, marks an advance in the direction indicated. The current from this battery increases the sensitiveness of the cells to light, and also to reversal of current. One cell whose highest ratio in light was about 83 to 1, with the Leclanche battery, when measured with my battery gave a ratio of 120 to 1. It seems to make the resistance of the cell both higher in dark and lower in sunlight than with the Leclanche battery. But the field is yet open to others, for the discovery of a battery which may be still better for use with selenium cells. 3. The two surfaces of the selenium act differently toward currents sent into them from the contiguous conductors. One surface offers a higher resistance to the current than the other. The former I utilize as the anode surface, as I have found that the cell is more sensitive to light when the current enters at that surface, which is ordinarily the one covered by the gold or other transparent conductor. Some cells have this property but feebly developed; but in one instance the resistance offered to the current by the anode surface was 256 times as high as that offered by the cathode surface to the same current. In the majority of cases, however, the ratio does not exceed ten times. Table B gives some recent results. ------------------------------------------------------------------- TABLE B. SENSITIVENESS TO REVERSAL OF DIRECTION OF CURRENT. -----------------------+--------------+------------------+--------- Resistance No. of cell. Battery. gold gold Ratio anode.cathode. -----------------------+--------------+--------+---------+--------- ohms. ohms. 3/8 inch square. No. 4 5 elements. 20,000 1,000 20 to 1 3 Se. cell. 6,500 400 16.2 Full size, ...