SCIENCE IN THE INDUSTRIAL WORLD 



the developing process in an unaccountable man- 

 ner. But this was soon corrected by the discovery 

 of two Americans, Cary Lea of Philadelphia, and 

 W. Cooper of Reading, Pennsylvania, that all this 

 could be overcome by the addition of a little acid to 

 the solution. 



It was presently discovered that the addition of the 

 acid made the plates much more rapid, although any- 

 thing like "snapshot" photography was not possible. 

 But in 1873 Col. Stuart Wortley found that when a 

 strongly alkaline developer was used, plates need only 

 be exposed a fraction of the time ordinarily required, 

 although, as yet, such time for exposures did not cut 

 the second into thousandths, as at present. This dis- 

 covery had a peculiarly stimulating effect upon both 

 scientists and practical photographers, and other im- 

 portant discoveries followed in rapid succession. 



The following year, a famous Belgian chemist, M. J. 

 S. Stas, published an article entitled Researches with 

 Chloride and Bromide of Silver, in which he pointed 

 out that bromide of silver could exist in at least six 

 different states, each state having peculiar properties 

 and different sensitiveness to the action of light. But 

 this paper was written from the standpoint of the 

 chemist rather than that of the photographer, as Stas 

 himself was not personally interested in the art; and 

 for the moment it went unnoticed by the photographers. 

 In point of fact, however, it contained the key to the 

 scientific facts upon which modern rapid photography 

 is based ; and a few photographer-scientists, recognizing 

 the possibility of the suggestions contained in it began 



[232] 



