128 DEFECTS IN NEGATIVES. 



CHAPTER VIT. 



Defects in Negatives, Their Causes and Core. 



Before attempting the production of negatives 

 with the microscope, we recommend the beginner 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, how- 

 ever, 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 Micro-photographer in addition to a know- 

 ledge of the same kind, must recognise and allow 

 for the chemical changes produced in different sen- 

 sitive compounds by light ; which is itself modified 

 by agencies beyond the perception of unaided vision. 



Many of these changes and agencies have only 



