CHAPTER VI 



MICRO-SPECTROSCOPE AND POLARISCOPE, MICRO- 

 CHEMISTRY, MICRO- METALLOGRAPHY, 

 TEXTILE FIBERS 



APPARATUS AND MATERIAL REQUIRED FOR THIS CHAPTER 



Compound microscope; Micro-spectroscope ($ 210); Watch-glasses and 

 shell vials, slides and covers (§229); Various substances for examination (as 

 blood and ammonium sulphide, permanganate of potash, chlorophyll, some 

 colored fruit, etc., (g 230-239), Micro-polarizer (jS 240); Selenite plate (§ 250); 

 Various doubly refracting objects, as crystals, textile fibers, starch, section of 

 bone; Various chemicals, metals, etc. 



MICRO-SPECTROSCOPE 



f! 210. A Micro-Spectroscope, Spectroscopic or Spectral Ocular, is a di- 

 rect vision spectroscope in connection with a microscope ocular. The one de- 

 vised by Abbe and made by Zeiss consists of a direct vision spectroscope prism 

 of the Amici pattern, and of considerable dispersion, placed over the ocular of 

 the microscope. This direct vision or Amici prism consists of a single trian- 

 gular prism of heavy flint glass in the middle and one of crown glass on each 

 side, the edge of the crown glass prisms pointing toward the base of the flint 

 glass prism, i. e., the edge of the crown and flint glass prisms point in oppo- 

 site directions. The flint glass prism serves to give the dispersion or separa- 

 tion into colors, while the crown glass prisms serve to make the emergent 

 rays approximately parallel with the incident rays, so that one looks directly 

 into the prism along the axis of" the microscope. 



The Amici prism is in a special tube which is hinged to the ocular and 

 held in position by a spring. It may be swung free of the ocular. In con- 

 nection with the ocular is the slit mechanism and a prism for reflecting hori- 

 zontal rays vertically for the purpose of obtaining a comparison spectrum 

 (§ 223) . Finally near the top is a lateral tube with mirror for the purpose of 

 projecting an Angstrom scale of wave lengths upon the spectrum (§ 224, 

 Fig. I34-I35)- 



(S an. Apparent Reversal of the Position of the Colors in a Direct Vision 

 Spectroscope. — In accordance with the statements in § 210 the dispersion or 

 separation into colors is given by the flint glass prism or prisms and in ac- 



