122 



ELEMENTARY CHEMICAL MICROSCOPY 



The Jentzsch Ultracondenser 1 can be placed upon the stage 

 of any compound microscope and is so constructed as to combine 

 in itself a reflecting condenser and cell for containing liquids, 

 vapors or gases. It consists, Fig. 60, of a metal cell M, in which 

 are mounted the two reflecting 

 glass bodies G, G'. These are held 

 in place by the cement S, S. Light 

 rays enter the apparatus through 

 the annular opening 0, strike the 

 silvered spherical surface in G, are 

 reflected to the curved sides of G' 

 and enter the central cell C. The 

 illuminating rays, therefore, are 

 substantially at right angles to the 

 optic axis of the microscope, thus 

 conforming in general to those in 

 the slit ultramicroscope with, how- 

 ever, this difference, that in the 

 slit instrument the rays enter the 

 cell from one side only, while in 

 the Jentzsch cell the rays enter from 

 all sides and meet at the center. 

 This instrument may therefore be 

 considered as occupying an intermediate position between the 

 slit ultramicroscope and the cardioid type of ultramicroscope. 



A cover N fits into the mounting M and is secured in place by 

 a bayonet catch. By turning the cover slightly it is made to 

 press down upon the rubber gasket RR, making a very tight 

 seal against the upper surface of G'. The tubes TT serve for 

 the passage of gas or of liquid through the cell. The cover N is 

 provided with a well-like depression closed at the end by the 

 quartz plate Q. This well permits an objective of long working 

 distance to be focused upon the particles in suspension at the 

 focal point of the illuminating rays. 



When in use the ultracondenser is laid upon the stage of the 

 microscope with the short tube A inserted into the stage opening. 



1 Made by Ernst Leitz, Wetzlar: and C. Baker, London. 



FIG. 60. 



The Jentzsch Ultracon- 

 denser. 



