466 © 
C. BE. Fritts—New Form of Selenium Cell. 
sometimes of a very light lead color, at others a very dark 
gray, a violet, a purple, a dull gold color, and occasionally a 
ese colors are caused by h 
“ 
eat. 
I have tried many different metals and substances as bases 
His measurements of this cell are given in table A, annexed 
* 
find several of them 
my pi re 
easuring a new series of selenium cells of my form bye 
far more sensitive to light than any of those mentione Rx 
‘the American Association. for the Advancement of Scienee. 
n to put them on record. 
Their i ex h s tivity 
Brass cell No. 24, measured Sept. 4th, showed twenty-five times the conduc 
ark, and brass cell No. 23, showed about thirty 
“63 t 
n the dark 
exact ratio being 29°63 to 1. . 
me cells again to-day, together with several others, ye 
the results given in the following table. All the cells were m ap 
a ; : 
asured “ 
e, and with 23 
nché battery, except No 23 and 8. The time was between 
Tests oF SELENIUM CELLS IN LIGHT AND DARK. 
Selenium ceil.| Battery. In dark. Sunlight. Ratio. 5 
No. 24. | 23 cells. | 32,500 ohms. | 1,300 ohms. | 25° to 1 | Sept. 4 ae 
24. |93 “ | 48500 “ | 1100 * | 4409to1} “ & | 
23. |10 “ 1,600 « 64 * «| 99-68 tol | * Ss 2 
23, |10 “ 1,510 “ ’ $02 tol |< 
25. |23 “ | 15,000 « re. HOE oto 
22. |93 « 1,5 “ 80. * | Wi tol ys 
22. ied 2,030 Xy a a as 156 tol eo 
6. 123 © 5,040 170 a9°05 ol | 
Bas 2,400 * 50 “= «1:16 se ee 
10. |98 © | 60, *. 13600... | 166 tod Mee Ge 
i 1 oes 1,790“ 250 * TL. wl) yi) Gg 
8, “| 90,000. ~| 1000 .* -[ 30° tot] = ee 
T have a number of others not yet tried, which may give even greater ig 
not astonishing that the electrical resistance of a substance sho 
But is it 
