ILLUMINATION OF OBJECTS; ILLUMINATING DEVICES 53 



in the illuminating devices. Any microscope permitting the 

 attachment of a dark-ground illuminator whose lenses are made 

 of quartz may be converted into a fluorescence instrument. 



Although this system of illumination is still so new as to have 

 been tried by but very few workers, its future development 

 seems assured and its usefulness in qualitative chemical analysis 

 of minute fragments of material to be unquestioned. 1 



It is valuable not only in the analysis of inorganic material, 

 such as crushed minerals, soils, mixtures of tiny crystals, etc., but 

 is of equal value in organic analysis, in the examination of foods 

 for adulteration and even in the microscopy of drinking water. 



1 See Heimstadt, Das Fluoreszenz-Mikroskop, Zeit. f. wiss. Mikros., 28 (1911), 

 330; Wasicky, Das Fluoreszenz-Mikroskop in der Pharmakognosie, Pharm. Post, 

 (1913); Lehmann, H., Das Lumineszenz-Mikroskop, seine Grundlagen und seine 

 Anwendungen, Zeit. f. wiss Mikros., 30 (1913) 417. 



