PHOTOGRAPHY, SCIENTIFIC ASPECTS 



experiments along the lines it suggested. Among these 

 was Dr. D. von Mockhoven, of Ghent, and five years 

 later, in 1879, he announced a process of making rapid 

 dry plates by adding a solution of ammonium bromide 

 to the ordinary gelatine emulsion that had very generally 

 replaced the collodion emulsion by that time. This 

 process he credited to the suggestions made in Stas* 

 paper of five years before, calling attention to this im- 

 portant document in the history of photography that 

 would otherwise have been generally lost sight of. 



It is from this year, therefore, that we must reckon 

 the beginning of rapid dry-plate photography. By this 

 time the wet collodion plate had practically disappeared, 

 replaced by the dry gelatine plate; and Mockhoven's 

 discovery, with those of other scientists and practical 

 photographers, made possible the fraction-of-a-second 

 negative, and paved the way to the "You push the 

 button" camera. 



The modern era of photography may be said to begin 

 with the discovery of Mockhoven and his associates. 

 Yet one more step was necessary to give photography 

 the impetus for becoming the popular fad that it has 

 remained for the last fifteen years. This step was the 

 stroke of genius of the man who conceived the idea of 

 using a flexible transparent film in place of the ordinary 

 glass-plate negative, and rolling a number of these into 

 a coil so that several pictures could be taken without 

 bothering with plates the "kodak" idea, that has since 

 carried the world by storm. This happened about 1888, 

 and the amazing flood of improvements cartridge 

 cameras, daylight-loading cameras, daylight-developing 



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