124 
ELEMENTARY CHEMICAL MICROSCOPY 
In this new Immersion Ultramicroscope^ both the illuminating 
and observing objectives are beveled at the ends so as to allow 
their front lenses to be brought very close together with their 
axes at right angles; the drop of liquid to be examined is 
placed between the front lenses, clinging by capillarity. No 
cell is employed. The Hght rays having but a very short dis¬ 
tance to travel, even dark colored liquids may be studied. Diffi¬ 
cultly cleanable, expensive cells are thus wholly eliminated, the 
amount of material required for study reduced to a minimum, 
and the images obtained are exceptionally brilliant. 
For the study of hydrosols, water immersion objectives must 
be used, but for colored glass and similar bodies homogeneous 
immersion objectives are required. 
The construction of the instrument is shown in the diagram, 
Fig. 6i. Fitted to the body tube of a compound microscope 
is the objective carrier C into which slides a plate to which is 
screwed the image-forming objective O. To the stage of the 
instrument is attached the mechanism supporting the illuminat¬ 
ing objective I. The micrometer screws S^, provide means 
for the exact adjustment of the beam of light passing in the 
line of the axis of the objective I, so that it will fall normal to the 
optic axis of the microscope. gives an up and down adjust¬ 
ment, forward and back and from side to side. By rack 
and pinion 8“^, the entire illuminating device can be lowered for 
cleaning, for the removal of the objectives, etc. When raised 
in position for use, the screw 5 is turned, thus locking the mecha¬ 
nism in place. 
The trough T serves to catch any drip when the liquid is being 
applied between the objectives. 
When in use, the instrument is placed on a bed plate with 
saddle stand upon an optical bench of the type shown in Figs. 
51 and 57. An apparatus consisting of a condensing lens and 
an adjustable slit, also on saddle stands, serves to throw a 
beam of light from a radiant (arc or Nernst lamp) into the 
objective I. 
In critical work the ocular of the microscope is furnished with 
* Made by C. Winkel, Gottingen, Germany. 
