INORGANIC RESPONSE 
159 
record (a), before warming, slight fatigue is observed, 
in (ce), after cooling, the reverse, or staircase effect, 
appears. 
20°C 20°C 
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_—. “ (6) RCH he oleae pe 
Fic. 101.—InFrivEence or TEMPERATURE ON RESPONSE 
Illumination 20”, obscurity 40”. 
In (a) is shown a series of responses at 20° C.—the record exhibits slight 
fatigue. 
(b) is the slight irregular response at 50°C. (c) is the record on 
re-cooling ; it exhibits ‘staircase’ increase. 
Effect of increasing length of exposure. —If the 
intensity of light be kept constant, the magnitude of 
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Fic. 102. _RESPONSE-CURVES FOR INCREASING DURATION OF ILLUMINATION FROM 
TU Gos a0 
In (a) the source of light was at a distance of 50cm.; in (0) it was at a distance of 
25 cm. 
Note the after-oscillation. 
response of the sensitive cell increases with length of 
exposure. 
But this soon reaches a limit, after which 
