122 
ELEMENTARY CHEMICAL MICROSCOPY 
The Jentzsch Ultracondenser ^ 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. 6o, 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 O, 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. Jentzsch Ultracon- 
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. 
‘ Made by Ernst Leitz, Wetzlar: and C. Baker, London. 
