1904.] The Chemical Dynamics of Photographic Development. 467 

 Other results abbreviated : 

 Series II... R = 1-465. Mean dev. = +0-04. TI = 6 mins. 



T 2 = 120 



= + 0-04. TI = 2 



T 2 = 4 



= +0-05. T! = 8 



T 2 = 120 



= + 0-032. T! = 5 



T 2 = 10 



= +0-05. T! = 10 



T 2 - 120 



Range of exposure 1 250. 



development 2 mins. to 2 hrs. 



Log. E. 



4 mins. 



* Constancy of Density ratios. 



The ratios of densities due to different exposures are unchanged by 

 time of development in a non-bromided developer. 



These tables and the curves show that for variations in the time of 

 development from 2 minutes the density ratios and the values of i are 

 unaffected. Every density grows proportionately with the time, a 

 fact which finds its rational explanation in the theory of development 

 proposed. 



For the straight line portion of exposure the equation 

 D = y (log E - log i) holds, and for a single density the expression in 

 brackets is a constant. The development factor, y, is, therefore, 

 strictly proportional to D, and as 



80 



where 



y = y at time t, 

 y^= y infinite dev., 

 which gives the relation between y and the time of development. 



