﻿362 Mr. F. C. Toy on the Theory of the 



those observed by the plotted points. The agreement is very 

 good, and proves the validity o£ equation (6) in the case of a 

 fast emulsion. 



Ker. 7. 



0-8 



Ob 



r ro-4 



0-2 















1 



1 







>< 









10 N = 0-480. 

 W N Q =1-H3. 





\ 









\ 



\ 





















^ 



K 

















u 





\ 





















- \ 



\ 



X 



^) 







































> 





i 



r 



__J- 



5 



To find the relation between the average number of nuclei 

 per grain and the intensity, a plate was exposed behind a 

 step wedge and partially developed. The size of grain 

 selected was the same as used for determining the A, I curve 

 in fig. 4, the plate being exposed for approximately the same 

 time behind the same wedge. At each intensity (I) the total 

 number of nuclei on 200 grains was counted (except at 

 1 = 0*044, where 100 grains were considered sufficient), and 

 hence the average number per grain found. The values are 

 given in Table III., and it will be seen that the curve in 

 fig. 8 is of the same general form as the A, I curve in fig. 4, 

 as is predicted by the theory. 



Table III. 

 Cross-section of grain = 0'98/u, 2 . 



I. 



N . 



L 



N . 



1-000 



0-98 



0-270 



0-24 



0-689 



0-88 



0-180 



005 



0-490 



0-63 



0-128 



0-02 



0-356 



43 



0-044 



o-oo 



