340 DEFECTS IN NEGATIVES. 



CHAPTER VII. 



DEFECTS IN NEGATIVES, THEIR CAUSES AND CURB. 



Before attempting the production of negatives 

 with the microscope, the beginner is recommended 

 to obtain some skill in ordinary photography, by the 

 perusal of a standard work on the subject, with the 

 subsequent reproduction of views by the camera. 

 This will at least prevent the disappointment occa- 

 sioned by unsatisfactory results, arising from want 

 of skill or errors in development. 



It should, however, be remembered that a wider 

 and more scientific knowledge is required than is 

 generally obtainable by these means. The ordinary 

 photographer has only to place his camera in such a 

 position, that a picture formed by artistic rules is 

 thrown upon the screen. Having given an exposure 

 suitable to the intensity of the illumination, fastness 

 of the plate, and tints in the picture, a latent image 

 is obtained which on the application of a well chosen 

 developer, reproduces every characteristic detail in 

 the original view. The Photo -micrographer in ad- 

 dition to a knowledge of the same kind, must recog- 

 nise and allow for the chemical changes produced in 

 different sensitive compounds by light ; which is it- 

 self modified by agencies beyond the perception of 

 unaided vision. 



