ULTRAMICROSCOPES 



diagram, diffraction, refractions, reflections and dispersions take 

 place of such characters and to such degrees as to render the 

 detection of micellae impossible. 



No suggestions as to optical combinations or size and intensity 

 of the illuminating light beam may be given which will be applic- 

 able to all materials. As in all 

 other cases of microscopic investi- 

 gation, the proper conditions must 

 be experimentally ascertained for 

 each preparation examined, but it 

 is a safe rule to always avoid too 

 large a slit and too high a magni- 

 fication. 



For the slit ultramicroscope as 

 made by Zeiss two objectives are 

 specially constructed, a dry 7 mil- 

 limeter, 0.4 N.A. achromatic ob- 

 jective for the study of solids, and 

 a 4.4 millimeter water immersion 

 of 0.75 N.A., for use with cells 

 containing solutions. A good gen- 

 eral outfit should include oculars, 

 i, 6, 8, 12 and 18. 



When polarized light is necessary 

 in the study of colloidal reactions 

 a nicol prism as polarizer mounted 

 upon a saddle stand is placed be- 

 tween the lens Ci and the slit S. 

 The analyzer is then placed as 

 usual above the ocular of the mi- 

 croscope M. 



To adjust the illuminating beam of light used with the slit 

 ultramicroscope shown in the diagram, screw the condenser- 

 objective Ca into its holder T. Place the projection lens 2 

 at about 10 to 12 centimeters from the end of T, place the 

 adjustable slit approximately 12 centimeters from 2, the projec- 

 tion lens Ci about 12 to 15 centimeters from the slit, the dia- 



FIG. 29. The Necessity of having 

 Two Sides at Right Angles in the 

 Object for Ultramicroscopic Study. 



