CHAPTER XV 



SOME APPLICATIONS OF PHOTOMICROGRAPHY 



AN outline of the photographic processes applied to 

 metallography, so largely used as a control and record 

 in the great steel and other metal industries as to con- 

 stitute the most specialised and important application of 

 photomicrography, has been already given. Apart from 

 these, the ordinary methods detailed for low, medium, 

 and high powers, suffice for practically any application, 

 and there is usually little difficulty in modifying them 

 for work requiring special treatment. In this chapter, 

 however, some of the threads are gathered together, and 

 those devices more particularly applicable to certain 

 branches of science and study collected from the sections 

 in which they are fully described. It is impossible to 

 mention more than a tithe of the purposes for which 

 photomicrography is employed in the control of textile, 

 food-stuff, and other industries, or as a record of adultera- 

 tion and falsification. Wherever the microscope finds 

 application, and permanent records of observations are 

 required, photomicrography is the readiest, most con- 

 venient and accurate means available. Prints can be 

 stored with the written notes of analyses and examina- 

 tions, and have not only the value of records of known 

 facts, but of points unknown or unrecognised at the time, 

 which would inevitably be missed in any written notes, 

 but may become of the highest importance in future 

 researches, and afford accumulated evidence which it 

 would be impossible to obtain otherwise. Its value in 



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