CANE SUGAR. 



It is claimed that the polarization of the better grades of sugar can be 

 read with this instrument to -01 Yentzke. 



Optical Parts Of Polariscopes. Below are mentioned the arrange- 

 ments of the optical parts of such polariscopes as are to be found in general 

 use. 



Soleil-Duboscq. The optical parts are shown in Fig. 2!0 : a, colour 

 compensator ; I, lens to make rays of light parallel ; c, polarizer ; d, biquartz 

 plate ; e, compensator ; /, analyser ; k g, focussing telescope. The colour 

 compensator consists of a nicol prism and plate of quartz. When dark-coloured 



FIG. 240. 



F,o. 24!. 



H 10 



FIG. 242. 



13 (5 E3 HH C^IZI I P.O. 243. 



ft g a e c 6 



H G) 123 IZ1 I n. 244. 



ft g & c b 



solutions are being examined the transition tint does not appear, but an 

 approximation thereto may be obtained by rotating the colour compensator. 

 The scale of this instrument is not provided with a vernier, divisions of 

 less than one degree being estimated by the eye ; the normal weight is 

 16*35 grms. 



Soleil-Ventzke-Scheibler. The optical parts are shown in 

 Fig. 241 ', reference being as in Fig. 8J/.0 ; the colour compensator is placed 

 next to the lamp, and in mechanical details this instrument is superior to the 

 Soleil-Duboscq. 



438 



