214 H. C. Bolton—Action of Light on Uranium. | 
Employed following developing solutions. | 
A = 1grm. K,Fe,Cy, in 60 grms. water. ! 
B = 20 drops Fe,Cl,* in 60 grms. water. 
C = mixture of 1 part A and 2 parts B. 
D = mixture of 1 part A and 1 part B. 
E = mixture of 2 parts A and 1 part B. 
F = 1 grm. FeO 80, in 60 grms. water. 
No. 20. Sensitizer S. Developer C. Exposed one minute— 
a clear dark lead colored print having a shade of blue. 
No. 21. Sensitizer 8. Developer D. Exposed one minute— 
a brown print with a shade of red. . 
o. 22. Sensitizer S. Developer E. Exposed one minute ; | 
a reddish brown picture. , 
No. 23. Sensitizer 8. Developer, Ist, A; 2d, C. Exposed : 
one minute—a black color nearly resembling nitrate of silver 
prints. In several trials a blue color predominated. 
0.24, Sensitizer S. Developers A and FB. Exposed one 
minute. A clear greenish black picture. 
The photographs enumerated above are but a small portion 
of those taken ; some of the processes were repeated and only 
the best pictures retained. In describing them it is difficult 
to convey in words a correct idea of color, tone, intensity, clear- 
ness, &c. Inexperience in manipulation was often a cause of 
ill success. 
may be fairly imitated, but I candidly confess I have been un- 
able to reproduce the delicacy of line, beauty of tone and finish 
¢ teristic of ordinary gold and silver prints. 
New York, June, 1869. 
* Ordinary commercial solution. 
